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INVERTIS JOURNAL OF RENEWABLE ENERGY Volume 8

January-March 2018

No. 1

Patron Umesh Gautam CONTENTS Plant oils (Dewaxed & Degummed) as a fuel for diesel engine R.N. Singh and Shaishav Sharma

Chief Editor Z.H. Zaidi

Editors R.M. Mehra Sharda University Mohd Parvez Al-Falah University

Assistant Editor Sumit Kumar Gautam

1

Design, fabrication and testing of solar concrete collector at Kakinada Mithilesh Pakala, G. Anil Kumar and Madhav Koka

10

Performance analysis of valve regulated lead-acid battery in solar street light system under field conditions in India Manish Singh Bisht and Hiren Chandra Borah

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Enhanced photocatalytic performance of ZnO nanocrystals with different morphological variation and their structural characterization Samapti Kundu and Swapan Kumar Pradhan

24

Photocatalytic studies of nanocrystalline Brookite TiO2 obtained by mechanical alloying of V2O5 and anatase TiO2 stoichiometric mixture Rajib Kumar Mandal, Samapti Kundu and Swapan Kumar Pradhan

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Production of Biofuels in India Anita Sharma

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Growth, structural and optical properties of new semi-organic crystal of tris-thiourea zirconium chloride (TTZrC) waste water M. Manimegalai, F.A.Selvin, P.N. Selvakumar, J. Annaraj and S. Chandrasekaran

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: 10.5958/2454-7611.2018.00001.2 Plant oils (Dewaxed & Degummed) as 1-9 a fuel for DOI dieselNo. engine Invertis Journal of Renewable Energy, Vol. 8, No. 1, 2018 ; pp.

Plant oils (Dewaxed & Degummed) as a fuel for diesel engine R.N. SINGH1* and SHAISHAV SHARMA2 School of Energy and Environmental Studies, Devi Ahilya VishwaVidyalaya, Indore, MP-452001. 2 Sardar Patel Renewable Energy Research Institute, Vallabh Vidya Nagar, Gujrat. *E-mail: [email protected]

1

Abstract A multi cylinder naturally aspirated diesel engine with matching alternator was operated successfully with dual fuel (diesel, blended dewaxed degummed Jatropha oil/ karanja oil/ rice bran oil). Its performance was verified through extensive, short (6 hours) and long duration trials (200 hours). Study reveals that CI engine can be run satisfactorily without any change in engine using up to 10% blending of dewaxed degummed plant oil (directly and without preheating) with diesel; but above that preheating of the blend of dewaxed degummed plant oil with diesel is necessary. Preheating of the blended fuel (above 10% blending) at 60ºC is required to reduce the viscosity of blend. Maximum blending of plant oil with diesel depends upon the quality of the plant oil. In case of refined plant oil, blending may be as high as 75%. Key words : Jatropha oil, Dewaxing & Degumming, blending, diesel engine, engine performance.

1.

Introduction

rural areas, which does not have access to commercial energy sources, will have to be provided with hydrocarbon fuels for their energy requirements. The country faces the problems of effectively meeting the growing energy demand and at the same time curb the resulting environmental degradation. In this scenario, biofuels offer an attractive alternative for providing energy with less pollution. Biofuels are renewable fuels derived from biological raw material. They are biodegradable and have beneficial effect on engine exhaust emission as compared to diesel (Tewari, 2003).

India ranks fourth in the world in terms of consumption of crude oil petroleum products in 2013 (http://www.eia.gov). Although the present per capita energy consumption is very low, which according to World Bank report 2011 is about 614 kg of oil equivalent, the growth in energy demand in all forms is expected to continue owing to the rapid development in the industrial and successive sector, increasing population and rising standard of living, with stabilization expected not before the middle of the current century.

Biofuels, straight or modified, are known to offer several advantages as engine fuel. Biofuel in the form of straight vegetable oil may be used as a fuel in existing diesel engines. However, some precautions should be taken into account because some of their physicochemical properties must be adjusted through temperature control to ensure enhanced combustion, thus avoiding premature aging of the engine (Bernat et al. 2012).

The consumption of fossil-diesel has increased to 68.88 million metric tons in 2013. The fossil diesel demand is expected to increase by 81.60 million metric tons by the end of twelfth five year plan in 2017 (Indian Petroleum & Natural Gas Statistics, GOI, 2013-14). The transport sector alone consumes about 68% of the oil and gas in the country. A large part of India's population, mostly in the 1

R.N. Singh and Shaishav Sharma

as per the ASTM standards (ASTM, 1983). The various characteristics studied were kinematic viscosity, density, gross heating value, flash point, cloud point and carbon residues.

Biofuels have proved to be a good substitute for fossil diesel in the transport sector. These have gained worldwide acceptance as a solution for problems of environmental crisis, energy security, energy access and economic efficiency.

For dewaxing, known weight of plant oil was refrigerated at temperature of 8-10°C in a refrigerator for the period of 12-15 hours and later decanted into another container. For calculating the percentage of wax in the oil precipitated wax, it was centrifuged. This led to the settling down of wax at the bottom of the tube.

Mustafa et al., (2009) tested preheated crude sunflower oil for combustion and emission properties against petroleum based diesel fuel in a naturally aspirated, indirect injection engine. There was a significant 34% improvement in the emissions of unburnt hydrocarbons.

For degumming, known amount of dewaxed oil was taken and it was heated with agitation at temperature of 65°C. Later 0.25% phosphoric acid and 2.5% hot distilled water (65°C) was added and temperature was maintained for 45 minutes with continuous agitation. After settling the precipitate at room temperature for 3 hours, clean oil was drained into other container. To calculate the percentage of gum, precipitate gum was centrifuged with the help of centrifugal separator and settled gum was weighed (Singh, 2007, Singh et al. 2014).

Golimowski et al. (2013) studied the performance of common rail diesel tractor engine which was run on raw rapeseed oil against the engine fueled with diesel. The engine fueled with raw rapeseed oil observed a power drop of 12-14% as compared to the engine fueled with diesel. Karikalan and Chandrasekaran (2013) investigated the emission characteristics of C.I. engine using vegetable oil with Selective Catalytic Reduction technique. The results from the experiments prove that vegetable oil and its blends are potentially good substitute fuels for diesel engine in the near future when petroleum deposits become scarcer. It was noted that continuous availability of the vegetable oils needs to be certain before embarking on the major use of it in I.C. engines. Similarly Wanderv et al. (2011) also studied the performance of a mono-cylinder diesel engine using soy straight vegetable oil as fuel with varying temperature and injection angle. They observed that the use of straight Vegetable Oil as fuel is feasible, but durability tests must be performed, mainly to discover potential maintenance problems. To minimize the problems associated with plants oil work was initiated on dewaxing and degumming of plant oils and their use as engine fuel. 2.

2.1 Experimental Setup A multi cylinder naturally aspirated diesel engine with matching alternator as per details specified in Table 1 was used. An electrically heated loading resistance was used for loading the engine. The general method used for measurement of fuel consumption in CI engines is based on gravimetric analysis. In this method, time was measured for consumption of 50 ml of fuel in the CI engine. In case of plant oil, which had very high viscosity as compared to diesel, it was heated and blended with diesel. Since viscosity is the function of temperature, volumetric measurement may not give the correct fuel consumption. Considering this, weight basis online digital liquid flow meter was designed and developed. The unit consists of two insulated oil containers (capacity 6 kg each), two pan type weighing machine (capacity 10 kg each), two solenoid valves, two inlet connections with valve which received oil from the liquid tank one by one, and a common outlet through individual solenoid valve, which was connected to the engine. The equipment was provided with timer control, which will change

Material and Methods

Non edible plant oils generally contain about 34% wax and gum. Dewaxing and degumming of plant oil is required not only for smooth running of the CI engine but also to prevent engine failure even if plant oils are blended with diesel (Singh, 2011). Non-edible plant oils were dewaxed degummed as per standard procedure (Sharma 1986). Characterizations of diesel and plant oils were done

2

Plant oils (Dewaxed & Degummed) as a fuel for diesel engine

Table 1: Engine details Name and Model of engine

:

Kirlosker, Electric GAA 10 ES

General Details

:

Bore x Stroke Compression ratio Rated output Fuel injection opening pressure Injection timing

: : : : :

Constant speed, single cylinder, naturally aspirated, four stroke, direct injection, 102 x 116 mm 17.5: 1 7.5 KVA or 6.0 kW at 1500 rpm 200-205 kg cm–2 26° BTDC

A microprocessor based flue gas analyzer was used for the measurement of emission concentrations. The fuel flow rate was measured on weight basis. The mixture of Jatropha oil and diesel was heated in an electrically heated and thermally insulated oil tank, before feeding to the DG set. Experiments were

the oil flow to the engine from one container to another after a set interval of time. The blend of plant oils and diesel was preheated in a well-insulated electrically heated oil tank having control panel before feeding to the engine.

Fig. 1. Schematic of the experimental set up for blended plant oils

3


not only for smooth running of the CI engine but also to prevent engine failure even if the plant oils are blended with diesel (Yarbrough et al. 1981, Vander and Hugo 1981). Wax & gum do not burn properly in the engine and create problems of choking of valves and fuel injectors in long-term use. It is therefore necessary to remove wax and gum from the fresh oil before it could be used in CI engine.

initially carried out on the engine at five loads (14%, 35%, 42%, 63% and 84%) using diesel. Further experiments were conducted using blends of plants oil and diesel in the proportion of 10:90, 20:80, 25:75, 50:50 and 60:40 at 14, 35, 42, 63 and 84% engine loads. In addition to emission data, parameters related to the performance of engine such as fuel consumption, crank oil temperature, noise level, rpm of engine, flue gas composition and its temperature were also measured & recorded. A sampling port was provided in the exhaust pipe for measuring flue gas temperature and to collect flue gas samples. The test was conducted as per BIS Code No. 13018 (1990). Schematic of the experimental set up is shown in Fig. 1.

3.2 Performance of CI Engine To check maximum possible blending of plant oil with diesel, without sacrificing the engine performance and emissions, blends of dewaxed and degummed plants oil and diesel in the ratio of 10:90, 20:80 25:75, 50:50, 60:40 and 75:25 were prepared. These blends were tested at 5 loads i.e. 14%, 35%, 42%; 63% and 84% of engine rated capacities. Engine performance was found satisfactory up to 50% of dewaxed and degummed Jatropha/karanja oil blended with 50 % diesel and heated at a temperature of 60ºC. However for refined rice bran oil engine performance was found satisfactory up to 75% blend with 25% diesel and heated at a temperature of 60ºC. With the blends having mixture 60:40 ratio of dewaxed degummed Jatropha or karanja oil and diesel, the engine produced white smoke with unburnt oil particles. Similar results have also been reported by Pramanik (2003) for Jatropha oil.

Specific energy consumption in diesel and dual fuel mode were calculated from the fuel consumption and the calorific value of diesel and blends of diesel & Jatropha oil. The calorific value of diesel and Jatropha oil was determined from bomb calorimeter, while the calorific value of different blends was calculated as per their composition. 3.

Results and Discussion

3.1 Characterization of Fuels Physical and chemical properties of the different fuels such as diesel, dewaxed and degummed plant oils used in the study are shown in Table 2. It was observed that with increase of temperature, viscosity and density of the diesel and plant oils and their blends decreased. Although viscosity of blended plant oils came very close to diesel at 80ºC but as the flash point of the diesel is 76ºC, in further trials the blend was heated only up to 60ºC for safety reason.

3.2.1 Effect of concentrations of Jatropha oil in diesel on specific energy consumption and brake thermal efficiency In general the specific energy consumption (SEC) increased with the increase in concentration of dewaxed degummed Jatropha oil dewaxed degummed Jatropha oil in diesel. The increase in SEC of blends of dewaxed degummed Jatropha oil with diesel may be due to their lower calorific value

Fresh plant oil contains about 3-4% wax and gum. Dewaxing and degumming of plant oils are required

Table 2. Characteristic of fuels Fuels

Diesel DDJO RRBO DDKO

Viscosity at 40ºC, cS

Density at 40 ºC, kg/m3

Flash point, °C

Cloud point, °C

Carbon residues, %

Fee fatty acid, %

Calorific value, kcal/kg

Wax & gum, %

4.33 38.96 42.92 39.28

788.96 887.20 884.26 899.08

66-76 245 256 226

13 -4 -2 15

0.03 0.34 0.20 0.22

0.00 1.14 0.03 1.20

10404 8765 8689 8691

0.00 2.34 0.00 2.50

4


at all the tested loads. The SEC value was found to be highest at blends containing 50/50, de-waxed degummed jatropha oil/diesel and corresponding brake thermal efficiency was lowest among all the blends at all the tested loads. Higher percentage of dewaxed degummed jatropha oil blends has higher density and led to more discharge of fuel for the same displacement of the plunger in the fuel injection pump (Pramanik, 2003). Table 3 shows that increasing the percentage by volume of the Jatropha oil in the blends leads to a reduction in the exhaust gas temperature in general. The reduction in the exhaust gas temperature for the fuel blends may be attributed to the effect of water present in the Jatropha oil. Similar

compared to diesel. Brake thermal efficiency decreased with the increase in concentration of dewaxed degummed jatropha oil in diesel (Table 3). The decrease in brake thermal efficiency of blends of dewaxed degummed jatropha oil with diesel may be attributed to their poor spray characteristics, which is again due to their higher viscosity and surface tension than that of fossil-diesel. The poor spray pattern may affect the homogeneity of air fuel mixture, which in turn lowers the heat-released rate thereby causing reduction in brake thermal efficiency. However, blends containing 25:75, de-waxed degummed jatropha oil/diesel have lowest SEC and highest brake thermal efficiency among all the blends

Table 3. Performance of CI engine at different blends of dewaxed & degummed Jatropha oil Mode of operation

Engine Engine LFCR, load, output, kg/h % kW

SEC, MJ/ kWh

ηbth, Sound Engine CO, % Pressure ext. % level, db Temp., C

HC, %

NOx, ppm

Diesel 10% DDJO+90% D 20% DDJO +80%D 25% DDJO +75%D 50% DDJO +50%D

14 14 14 14 14

2.80 2.58 2.65 2.89 2.81

1.756 1..627 1.703 1.821 1.890

27.25 27.06 27.11 26.36 26.98

13.21 13.30 13.28 13.66 13.34

98.73 98.72 97.5 99.53 97.00

189 198 228 186 193

0.80 0.47 0.26 0.17 0.78

0.41 0.37 0.30 0.27 0.18

378 319 242 197 136

Diesel 10% DDJO +90%D 20% DDJO +80%D 25% DDJO +75%D 50% DDJO +50%D

35 35 35 35 35

7.47 6.87 6.74 7.48 7.46

2.489 2.348 2.397 2.520 2.802

14.49 14.65 15.00 14.09 15.06

24.84 24.57 24.00 25.55 23.90

98.60 99.12 98.35 99.70 97.57

254 256 272 250 252

1.02 0.41 0.24 0.19 0.91

0.50 0.42 0.38 0.35 0.26

654 648 414 298 229

Diesel 10% DDJO +90%D 20% DDJO +80%D 25% DDJO +75%D 50% DDJO +50%

42 42 42 42 42

8.99 8.27 8.27 8.96 8.90

2.718 2.504 2.625 2.716 2.967

13.14 12.98 13.39 12.69 13.29

27.40 27.73 26.89 28.38 27.09

99.267 99.00 98.94 98.75 98.93

275 279 253 277 274

1.11 0.37 0.54 0.17 1.14

0.55 0.48 0.42 0.39 0.25

721 704 423 389 293


63 63 63 63 63

14.08 13.76 13.57 14.12 14.34

3.586 3.483 3.548 3.596 4.056

11.07 10.85 10.03 10.65 11.35

32.53 33.18 32.63 33.80 31.72

100.50 99.60 100.16 99.63 100.15

357 358 346 373 348

1.66 0.41 0.39 0.385 1.64

0.57 0.45 0.43 0.33 0.22

1153 1090 663 659 651


84 84 84 84 84

19.34 18.46 18.70 19.11 19.17

4.517 4.37 4.423 4.605 5.188

10.15 10.15 9.98 10.08 10.86

35.45 35.48 36.08 35.71 33.16

101.50 101.43 101.15 100.37 100.80

467 440 448 433 418

2.33 0.43 0.224 0.117 2.03

0.58 0.51 0.48 0.47 0.37

1546 1295 808 581 538

5


combustion of lube oil. Another cause is the oil film formed around the cylinder absorbing hydrocarbons, preventing them from burning, and then releasing them into the exhaust gas. In general, hydrocarbon concentrations in the emission decreased with increasing percentage of dewaxed degummed jatropha oil in the blends.

trends were also reported by Forson et al., 2004 while evaluating performance of Jatropha oil blends in a single cylinder diesel engine. 3.2.2 Emission characteristics of CI engine with blends of diesel and Jatropha oil The pollutant in the blends of Jatropha oil, even up to 50:50 was less than diesel alone (Table 3). However, in case blend of 20:80, the pollutant is very low. Details descriptions are as follows:

3.2.2.3 Nitrogen Oxides (NOx) Nitrogen oxides and particularly nitrogen dioxides effect human beings and animals. It causes irritation in the mucous membrane of the respiratory tract and can lead to infection. Various epidemiological investigations have shown a connection between deterioration of the lung function, respiratory tract symptoms and increased nitrogen dioxide concentration.

3.2.2.1 Carbon Monoxide (CO) Carbon monoxide is formed when the fuel flame temperature decreases and the progression to CO2 is not complete. This happens when the flame front approaches the relatively cool cylinder liner and combustion slows or stops. It also happens in the crevice volume that is between the outer diameter of the piston and the cylinder wall, where the flame front is extinguished. The other source of carbon monoxide is when the engine is being operated on too rich fuel to air ratio and there is insufficient oxygen for complete combustion.

The NOx emission is strongly related to lean fuel with high cylinder temperature or high peak combustion temperature. A fuel with high heat release rate at premix or rapid combustion phase and lower heat release rate at mixing - controlled combustion phase will produce NOx emission. NOx emissions are lower in the blended Jatropha oil, except at 50:50 blend as compared to diesel (Table 3).

Carbon monoxide (CO) value as shown in Table 3, becomes lower with increasing blends up to 25:75, dewaxed degummed jatropha oil/diesel and beyond that it increases at all tested loads. For the blends containing 25:75 dewaxed degummed jatropha oil/ diesel, all the emissions (CO, CO2, NO & NO2), except hydrocarbons were least compared to other blends at all tested loads (Table 3).

Almost similar trends were observed with dewaxed degummed karanja oil and refined rice bran oil (Table 4). However over the entire load dewaxed degummed karanja oil/refined rice bran oil produced higher NO emission than diesel. It is more effective at higher concentration and engine loads. This is may be due to higher peak pressure at higher loads, which in turn causes higher combustion temperature. The formation of NO is favored by higher combustion temperature and presence of oxygen. In general plant oil produce less NOx than diesel. However few investigators do not confirm this finding. Most probably oil characteristics, which change with storage period, are responsible for the different observations.

3.2.2.2 Hydrocarbon (HC) The hydrocarbons cause no adverse effects on human health. Aliphatic hydrocarbons produce undesirable effects only at concentrations of 102 to 103 times higher than those usually found in the atmosphere. No adverse effects have been observed for levels below 500 ppm. Aromatic hydrocarbons are more reactive than aliphatic ones and cause irritation of the mucous membranes. Unburnt hydrocarbons are the results of the incomplete combustion of fuel. Similar to carbon monoxide, unburnt hydrocarbons result from flame quenching in crevice regions and at cylinder walls. Other causes of unburnt hydrocarbons are running engine on too rich fuel to air ratio with insufficient oxygen and the incomplete

For diesel, higher viscosity translates into lower spray angle, higher penetration and lower atomization. It was believed that the same phenomena would apply to plant oils. However a study by Ryan and Bagby (1993) discovered that plant oils exhibit a different characteristic during the injection process

6


Table 4. Effect of fuels on CI engine performance and emission characteristics at maximum possible blends Mode of operation

Engine Engine LFCR, load, output, kg/h % kW

SEC, MJ/ kWh

ηbth, Sound Engine CO, % Pressure ext. % level, db Temp., C

CO2, HC, NOx, % % ppm

Diesel (50% D +50% DDJO) (50% D+50% DDKO) (25% D+75% RRBO)

42% 42% 42% 42%

8.99 8.90 8.85 8.90

2.718 2.967 2.907 3.183

13.14 13.29 13.32 13.65

27.40 27.09 27.03 26.37

99.27 98.93 97.35 96.70

275 274 270 263

1.11 1.14 0.83 0.56

5.04 4.72 4.68 4.71

0.55 721 0.25 704 0.20 853 0.02 1000

Diesel (50% D+50% DDJO) (50% D+50% DDKO) (25% D+75% RRBO)

63% 63% 63% 63%

14.08 14.34 14.14 14.03

3.586 4.056 4.006 4.20

11.07 11.35 11.35 11.43

32.53 31.73 31.70 31.50

100.50 100.15 96.80 97.40

357.00 348.00 363.00 338.00

1.66 1.64 0.95 0.73

6.46 6.53 5.83 6.33

0.57 0.22 0.04 0.03


84% 84% 84% 84%

19.34 19.17 18.90 19.12

4.517 5.18 5.043 5.319

10.15 10.86 10.56 10.62

35.45 33.16 34.09 33.89

101.5 100.8 98.30 98.60

467.00 418.00 456.00 439.00

2.33 2.03 1.27 0.93

8.13 0.58 1546 8.08 0.37 1295 7.47 0.063 1925 8.06 0.05 1909


98% 98% 98% 98%

22.59 22.20 22.55 22.28

5.38 5.914 6.087 6.192

10.35 10.69 10.79 10.66

34.77 33.68 33.37 33.81

99.50 99.90 100.70 99.50

540.00 524.00 539.00 525.00

2.43 1.96 2.17 1.39

9.34 8.87 9.32 9.47

0.62 0.15 0.08 0.14

1153 1090 1517 1519

1726 1640 1881 1988

D- Diesel, DDJO - Dewaxed degummed Jatropha oil blends with diesel at 60°C mixtures temperatures, DDKO -- Dewaxed degummed karanja oil blends with diesel at 60°C mixtures temperatures, RRBO - Refined Rice bran oil blends with diesel at 60°C mixtures temperatures, SEC- Specific energy consumption, LFCR - Liquid fuel consumption rate, ηbth, -- Brake thermal efficiency owing to the chemical reactions that take place at high temperature in the combustion chamber. Cracking of the double bond produces high volatile compounds at the fringe of spray, which leads to a higher spray angle, in spite of the higher viscosity of plant oils. Different results obtained with different plant oils which may be due to the reasons mentioned above.

oils. The increase in exhaust gas temperature may be responsible for reduction in brake thermal efficiency. Bhatt et al. (2001) have also reported similar result while working with karanja oil in a single cylinder engine. 4.

Conclusions

Following conclusions have been drawn based on experimental results.

Singh (2011) tested straight vegetable oil of jatropha in irrigation pump set. It was found that jatropha oil could be successfully used as irrigation pump fuel, however at an interval of every 25 - 30 hours of operation, fuel injection nozzle and head needs to be cleaned in spite of maintaining the Jatropha oil temperature between 80 to 90°C. The engine exhaust temperature increased with the use of blended plant oil, but it is not following uniform trends (Table 3 & 4). The increase in exhaust gas temperature may be due to delayed combustion because of slower combustion characteristics of plant 7

1.

Dewaxing and degumming of plant oil is essential for smooth running of the CI engine.

2.

CI engine can be run satisfactorily without any change in engine up to 10% blending of dewaxed and degummed plant oil directly (without preheating) with diesel.

3.

CI engine can also be run on blended dewaxed and degummed Jatropha oil with diesel even up to 50%, but preheating of mixture is required at 60ºC to reduce


viscosity, when blending of oil with diesel is more than 10 %. 4. 5.

Among tested oil Jatropha oil was found better than other oils.

Forson F.K., Oduro E.K. and Donkoh E.H., Performance of Jatropha oil blends in a diesel engine. Renewable Energy. 29, (2004) 1135-1145.

[6]

Golimowaski W., Pasyniuk P. and Berger W.A., Common rail diesel tractor engine performance running on pure plant oil. Fuel, 103, (2013) 227231.

[7]

http://www.eia.gov/countries/countrydata.cfm?fips=in.

[8]

Indian Petroleum and Natural Gas Statistics. (2013-14). Ministry of Petroleum & Natural Gas. Government of India.

[9]

Karikalan L. and Chandrasekaran M., Investigation on Emission Characteristics of C.I Engine using Vegetable Oil with SCR Technique. International Journal of Renewable Energy Research. 3(4), (2013) 969-975.

Nomenclature BIS CH4 CI CO CO2 cS DDJO DDKO D Fig. FFA h HC kCal kg kWh MW NO NO2 O2 RRBO SEC ηbth

: : : : : : : : : : : : : : : : : : : : : : :

Bureau of Indian Standards Methane Compression Ignition Carbon Monoxide Carbon Dioxide Centistokes Dewaxed degummed Jatropha oil Dewaxed degummed karanja oil Diesel Figure Free Fatty Acid Hour Hydrocarbon Kilo calories Kilogram Kilo watt hour Mega watt Nitric oxide Nitrogen dioxide Oxygen Refined rice bran oil Specific energy consumption Brake thermal efficiency

[10] Mustafa Canakci, Ahmet Necati Ozsezen and Ali Turkcan, Combustion analysis of preheated crude sunflower oil in an IDI diesel engine. Biomass Bioenergy 33, (2009) 760-767. [11] Pramanik K., Properties and use of Jatropha curcas oil and diesel blends in compression ignition engine. Renewable Energy 250, (2003) 239-248. [12] Ryan T.W. and Bagby M.O., Identification of chemical changes occurring during the transient injection of selected vegetable oils. SAE Paper no. 930933, (1993). [13] Sharma B.K., Industrial Chemistry - Oils, Fats, Waxes and Soaps. Goal Publishing House, Subhash Bazar, Meerut, India. (1986). [14] Singh R.N., Straight vegetable oil: An alternative fuel for cooking, lighting and irrigation pump. IIOABJ; 2(7), (2011) 44-49.

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[5]

American Society for Testing of Materials (ASTM) (1983). Annual Book of ASTM Standards. Philadelphia: ASTM 19103.

[2]

Bhatt Y.C., Murthy N.S. and Datta R.K., Karanja (Pongamia Glabra) oil as a fuel for diesel engines. Agril. Engg. Today, 25(5-6), (2001) 45-57.

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BIS Code No.13018 (1990). Internal Combustion Engine - method of test for pressure charge engine.

[4]

Esteban B., Riba J.R., Baquero G., Puig R. and Rius A., Characterization of the surface tension of vegetable oils to be used as fuel in diesel engines. Fuel, 102, (2012) 231-238.

[15] Singh R.N., Investigations on operation of IC engine using producer gas and non-edible plant oils and their esters in duel fuel mode. Unpublished PhD thesis submitted to Devi Ahilya University, Indore (M P), (2007). [16] Singh R.N., Shaishav Sharma and Vyas D.K., "Studies on Effect of Long Term Storage of Jatropha Oil, Blends of Jatropha Oil with Diesel and Bio-diesel on Quality" Nature & Environment, 19(2), (2014) 158-162. [17] Tewari D.N., Biofuel to be the future fuel. Proc. of Energy Challenges of 21st Century: Biofuel

8


a solution (2003) 17-20. [18]

[19]

Colombo A.L. and Lusa D., Performance analysis of a mono-cylinder diesel engine using soy straight vegetable oil as fuel with varying temperature and injection angle. Biomass and Bioenergy. 35(9), (2011) 3995-4000.

Van der walt A.N. and Hugo F.J., Diesel engine test with sunflower oil as an alternative fuel. Beyond the Energy Crisis- Opportunity and Challenges Vol. II. Third International Conference on Energy Use Management. Berlin (West). Eds. RA Fazzolare and C R Smith 192733. Pergamon Press, Oxford, (1981).

[20]

Wander P.R., Altafini C.R., Moresco A.L.,

9

Yarbrough C.M., Lepori W.A. and Engler C.R., Compression ignition performance using sunflower seed oil. ASDAE Paper Number 813576. St. Joseph, MI: ASAE. (1981).

DOIKoka No. : 10.5958/2454-7611.2018.00002.4 Mithilesh Madhav Invertis Journal of Renewable Energy, Vol.Pakala, 8, No.G.1,Anil 2018Kumar ; pp. and 10-15

Design, fabrication and testing of solar concrete collector at Kakinada MITHILESH PAKALA1, G. ANIL KUMAR2 and MADHAV KOKA2 Department of Mechanical Engineering, University college of Engineering Kakinada, Kakinada, AP, India 2 School of Renewable Energy and Environment, University College of Engineering Kakinada, Kakinada, AP, India *E-mail: [email protected] 1

Abstract An improvised passive solar concrete collector system have been designed, fabricated and tested at Kakinada location to investigate the feasibility of the same in green building aesthetics by embedding serpentine copper tubes within concrete slab over coated with black paint and engulfed by acrylic sheet at two different inclination angles 0o and 30o for water heating requirements in domestic applications. Key words : Passive solar collector, green building, solar energy, water heating, solar concrete collector.

1.

Introduction

the concrete is robust, durable and requires less maintenance than the traditional glass collectors which are sensitive and require daily cleaning of the surface for better efficiency.

In general, collectors are the devices used to collect energy that can be utilized for requisite use. Solar concrete collector is a device that can be used to collect solar energy which can be converted into usable heat energy for thermal applications. Several studies were carried out in this regard by several researchers for example A. Keste & S.R. Patil[1], V. Krishnavel[2], Ajinkya Sable[3] and Richard O'Hegarty[4] as one of the most durable building material. The theoretical advantages of which can now be transformed into practically implementable technical stuff by suitable selection of concrete mixture.

Several types of collectors are available for several means of applications. Here we try to explore the benefits of concrete collectors as a means of collecting solar energy that can be utilized for tapping available heat content that can be consumed for water heating requirements with in a green building system. The proposed study had been carried out on one of the domestic building top in Kakinada (16.9891° N, 82.2475° E) in India. 2.

As concrete is a mixture of aggregate composed of crushed stone stirred with portland cement in water at a proportional rate that binds the whole content to form a high strength ductile structure by chemical reactions with in the components. Unfinished concrete exhibit absorptivity of 0.65 which shows that it can absorb nearly 65 percent of solar radiation that strikes the surface of the collector while black polished concrete can further increase absorptivity by 31 percent. Hence concrete is selected as the material for making these collectors because

Fabrication of the collector

Concrete is the main component which is used to make this solar collector. Concrete is used because it is cheap and is easily available. The concrete slab is made of a mixture of sand, cement and stones in the ratio 1:2:2. The concrete used is Portland cement mixed with fine aggregates (sand) and course aggregate (stones). To increase the strength of the concrete steel rods of 6mm diameter are placed in between the layers. A copper tube of length 5 meters and diameter of 0.012 m is used to send cold water 10

Design, fabrication and testing of solar concrete collector at Kakinada

Fig. 3. Sectional view of slab

permeable. This curing process is the reaction between the cement used and the water. During moulding the fresh concrete is porous and is prone to dehydration quickly. As the curing process takes place, the concrete will be hydrated and the strength will gradually increaseleading to increase in strength that means the concrete turns from being porous to non-porous. Traditionally, the process of curing can be done either by spraying or stagnating water on the concrete surface. Stagnating the water is the process where the concrete is submerged in water (ponding) to prevent dehydration. The common curing method is to use wet jute bags to cover the fresh concrete. The slab was left for seven days for curing by spraying water, so that it retains moisture content to attain desired strength. Black paint is painted on the slab as shown in figure 4 to increase the heat absorbing capacity of the slabso that the water sent through slab gets heated up quickly.

Fig. 1. Copper tube

Fig. 2. Copper tube placed inside concrete

through the concrete slab. It has a thermal conductivity of 401 W/mK. It is bent at regular intervals such that it fits in the required dimensions. The copper tube is bent in the form of serpentine and is kept in between the cement layers as shown in figure 1 and 2. The dimensions of the slab (l × b × h) are 0.71m × 0.56m × 0.1m. Now, the concrete slab of 0.71m × 0.56m × 0.1m (l × b × h) dimensions is moulded with steel rods and copper tube placed inside it. This slab is allowed to dry for 2 days before removing from the mould. A cross sectional view of the entire arrangement is shown in figure 3.

Fig. 4. Slab painted black

The acrylic glass is a 3 mm thick transparent plastic sheet whose length and breadth are similar to that of the slab which is shatter proof and flexible

Curing the concrete is an essential step which is necessary for making the concrete stronger and less 11

Mithilesh Pakala, G. Anil Kumar and Madhav Koka

under 16.9891° N latitude, we adjusted solar collector at an angle of 30° with surface facing south. Since most of the buildings slab was horizontal and some may permit the building aesthetics angular orientations, here we have studied heat output at two different angles 0° and 30°. The slab has inlet and outlet at two different ends. These are connected with their respective connections. The inlet is connected to the overhead tank through which the water flows continuously through the copper tube. This water gets heated by the heat absorbed by the slab which absorbs the energy radiated from the sun. This heated water is collected from the outlet on the other side as shown in figure 6. As acrylic glass is used, an increase in temperature of the water by 1°C to 4°C at the outlet has been noticed and indicated in the tables 1 and 2 along with comparisons of earlier work carried out in this regard.

Fig. 5. Collector with acrylic glass

unlike glass is used to produce double reflection, a process in which the light from the sun is captured inside a two surface area where the reflected ray from a surface is again reflected back onto the same surface by again reflecting it. This double reflection takes place just below the glass where the light tries to escape out through glass after reflected from the surface of the slab. Thus absorbing capacity of the slab can be improvised to achieve maximum capacity. This glass is kept at a height of 1 inch above the concrete slab by constructing a concrete lining around the slab for perfect sedentary and protected by a rubber beading under itto restrict airflow and prevent scratches on it by the concrete slab. This entire arrangement on upper part of the concrete slab is enclosed by aluminium beading using screws as shown in figure 5. 3.

Fig. 6. Simple circuit of concrete water heater when the collector is installed at 30°

This heated water can be stored in an insulated tankfor later use or the water output can be connected to an auxiliary heating source as shown in figure 7 to heat the water in absence of solar power for example during night as well as on cloudy or rainy days to ensure continual operation.

Experimental Procedure

Installation of a solar water heating system should be carried out after determining the direction, angle and location of the collector to be installed. We have to make sure that the location of installation of the collector is exposed to maximum sunlight throughout the day. Thus concrete slab is placed on the terrace of the building, where there is abundant sunlight throughout the day without any interruptions. To obtain maximum output from the solar collectors should face the sun continuously. To ensure maximum output the collectors should be oriented at an angle equal to the latitude of the location or it should be adjusted with ±15° with respect to latitude location where the collector is installed. Since the location where the work has been carried out comes

Fig. 7. Circuit of concrete water heater with auxiliary heater

4.

Observations

After concrete slab development, performance testing was carried out as mentioned earlier at two different angles 0° and 30°. During testing the 12


Table 1. Readings when slab is at 0° Time (hourly)

10:00 am 11:00 am 12:00 pm 1:00 pm 2:00 pm 3:00 pm 4:00 pm 5:00 pm 6:00 pm

Ambient Temperature (°c)

Temperature of Normal concrete slab (°c)

Temperature of slab painted black (°c)

Temperature of Slab with acrylic glass (°c)

32 33 34 36 38 36 34 31 30

34.4 36.1 37.0 39.8 42.0 40.7 38.6 35.8 32.5

36.0 38.4 40.6 43.2 45.2 42.1 39.2 37 33.1

38.6 41.7 45.8 47.6 49.7 46.2 43.2 39.3 34.5

collector is tested under different conditions such as without any paint, with black paint and finally with acrylic glass on top of black painted concrete slab. Output temperature measurements collected at regular (hourly) intervals were noted in the following tables 1 and 2 whose analytical graphical representations were replicated in figures 8 and 9 respectively. From these tabulations, it is clearly evident that, at 0° tilt angle the hourly average readings of both the water output and the ambient temperature are

observed to be 42.9°C and 33.7°C respectively. Here it should be noted that the water has been heated 9.2°C more than the ambient temperature. Similarly at 30° tilt angle the hourly average readings of both the water output temperature and the ambient temperature are observed as 45.3°C and 33.7°C respectively (from table 2). Here it should be emphasized that the water has been heated 11°C more than the ambient temperature.

Fig. 8. Temperature variation of collector at 0°

13

Mithilesh Pakala, G. Anil Kumar and Madhav Koka

Table 2. Readings when slab is at 30° Time (hourly)

10:00 am 11:00 am 12:00 pm 1:00 pm 2:00 pm 3:00 pm 4:00 pm 5:00 pm 6:00 pm

Ambient Temperature (°c)

Temperature of Normal concrete slab (°c)

Temperature of slab painted black (°c)

Temperature of Slab with acrylic glass (°c)

32 33 34 36 38 36 34 31 30

36.1 37.6 38.9 41.3 42.8 40.8 38.8 36.5 33.6

37.2 39.8 41.6 45.2 48.4 45.2 41.8 38.3 34.6

40.5 43.7 47.6 50.1 52.9 50.4 46.3 40.5 35.7

Fig. 9. Temperature variation of collector at 30°

5.

except the side which faces the sun. Where ever there is a scope for passive solar collector system in green building development, it remains as a viable alternative for water heating requirements in domestic applications.

Result and Conclusion

From this experimentation, it can be concluded that the observed water temperature is found to be almost nearer to that of the output temperatures attained by [1] and slightly less than [2] and [4] even for lesser parametric dimensions adopted in this design. From this study we had noticed that the scope for increase in temperature can be attained by reducing the diameter of the copper tube to an optimum value with low evaporative fluid flow and by cascading the concrete slabs in series as well as insulating the solar concrete collector on all sides

References [1]

14

Keste A. and Patil S.R., Investigation of Concrete Solar Collector: A Review, IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) ISSN(e) : 2278-1684, ISSN(p) : 2320-334X, PP : 26-29.


[2]

[3]

Krishnavel V., Experimental analysis of concrete absorber solar water heating, (2014), http://dx.doi.org/10.1016/j.enbuild.2014. 08.025 0378-7788/© 2014 Elsevier.

/dx.doi.org/10.1016/j.reffit.2017.06.001, Resource-E?cient Technologies, Elsevier B.V. [4]

Ajinkya Sable, Experimental and economic analysis of concrete absorber collector solar water heater with use of dimpled tube. http:/

15

Richard O'Hegarty, Oliver Kinnane and Sarah McCormack, Parametric analysis of concrete solar collectors, International Conference on Solar Heating and Cooling for Buildings and Industry SHC (2015), doi: 10.1016/j.egypro.2016.06.262.

DOI No. : 10.5958/2454-7611.2018.00003.6 Manish and Hiren Chandra Borah Invertis Journal of Renewable Energy, Vol.Singh 8, No.Bisht 1, 2018 ; pp. 16-23

Performance analysis of valve regulated lead-acid battery in solar street light system under field conditions in India MANISH SINGH BISHT* and HIREN CHANDRA BORAH Ministry of New and Renewable Energy Govt. of India, C.G.O Complex, Lodhi Road, New Delhi-110003, India *E-mail: [email protected] Abstract Batteries form an integral part of solar street lighting systems. Failure of battery in solar street lighting applications can render the complete system useless. At National Institute of Solar Energy (NISE), MNRE, Govt. of India, the whole campus is covered with solar street lights for illumination. It was observed that the batteries installed in these systems last for just 1-2 years. The aim of the study was to analyse degradation in capacity of lead-acid VRLA batteries after two years of operation under actual field conditions. The test results indicate the causes due to which the field batteries degrade much faster than the reference batteries installed and operated in lab environment. Key words : VRLA battery capacity, solar street light, photovoltaic.

1.

Introduction

are found to work relatively well in practical applications (Nieuwenhout et al., 2001) but the field exposure significantly reduces the available energy or capacity of lead-acid batteries in short period of time (M. Gustavsson and D. Mtonga, 2004). After this they are unable to provide satisfactory performance due to decrease in available energy. The reduction in Ah capacity of the batteries makes them unfit to provide for desired autonomyperiod. This results in decreasing performance of the system and eventually complete system shutdown. Batteries in solar street light systems are prone to early damage due to continuous exposure to the field environment. It occurs either due to high operating temperatures or due to low current being generated from the module. Normally, the load on the battery or D.O.D. is constant and as per design so the discharge pattern abnormality could be neglected in solar street lighting systems.

Solar is an intermittent source. So, a storage medium is always required to provide power backup during non-sunshine hours. In SPV applications this requirement is fulfilled by secondary batteries in which lead-acid batteries dominate. These batteries find extensive use in off-grid SPV applications such as solar street lights, solar home lighting systems and also in small and medium scale solar power plants. Such SPV applications are being extensively deployed throughout the globe for rural electrification. In developing countries like India, these are also a vital product to achieve national objective of power for all.It also enhances the solar inclusion in the country. A Solar Street Lighting System (SSLS) is one of the widely practiced solar applications.A typical solar street light system consists of - a solar module, a mounting stand, a LED light as a load, a charge controller and a battery placed inside a battery box to safeguard it from environmental effects. Usually the recurring cost of the batteries is higher than the other components (Banks, 1998; Diaz and Lorenzo, 2001). Solar modules

This article presents results from the study of VRLA batteries operating under same load profile but in different field conditions. The analysis period was 2 years and the results were compared with reference batteries which were operated in ideal 16

Performance analysis of valve regulated lead-acid battery in solar street light system under field conditions in India

conditions for SSLS under same load profile and same time period. This work was carried out in National Institute of Solar Energy, Ministry of New and Renewable Energy, Government of India, Gurgaon (Haryana), which is nodal centre of Union Government of India for characterization of Solar Energy Systems and R & D in field of solar energy. The institute stretches for around 200 acres. The whole campus is illuminated by solar street lights covering the pathways, lawns, parks, outdoor test beds, security gates, building rooftops, guest-house rooftop and around premises of the institute. These batteries receive regular maintenance such as cleaning the terminals, inspecting wires and loose connections and are also replaced immediately to ensure continuity of street light systems. It was observed that the batteries were good for only 2 years whereas they were claimed to work satisfactorily for 4 years. 2.

SSLS (Solar Street Lighting Systems) at NISE (National Institute of Solar Energy)

The SSLS deployed at NISE (fig. 1) were procured by Ministry of New and Renewable Energy (MNRE), Government of India under Jawaharlal Nehru National Solar Mission (JNNSM)[1]. These were deployed at the campus to promote use of solar products, create awareness among public, reduce the lighting bills and dependency on conventional grid power and to study technical and financial viability of SSL systems in India. This project was initiated in 2010 and since then this practice in being maintained with reinstallations and new installations.

Fig. 1. SSLS at NISE

per system will be required throughout the life of the system which is a significant expense. 3.

Testing Methodology

The testing methodology involved selecting 12 random samples of batteries from a lot of new street lights bought for installation in the campus. Initial capacity examination of all the 12 batteries was performed as per IS: 15549 standard formulated by Bureau of Indian Standards (BIS) 2 and the corresponding values were recorded (fig. 2). Under capacity test a charged battery is discharged at its C10 rate till low voltage cut-off is reached and the ampere-hours delivered are noted. This test was carried out at 27°C .The capacity is corrected at 27 °C by the following formula:

The system specification consist of a 40W monocrystalline SPV module, a 9W LED light, a 5A charge controller and a 12V, 40 Ah VRLA battery. The LED lights switch on and off automatically depending upon availability of current from SPV module. Under normal conditions these lights operate typically from 7 P.M to 5 A.M in summers and from 6 P.M to 6:30 A.M in winters. Proper shade free area for the module and maintenance of balance of system is ensured through proper maintenance plan.

Capacity at 27°C = C1+[C1 × R × (27-t)] 100

Since a solar module is rated for performance warranty of 25 years so the system is expected to work satisfactorily for at least 20 years. If the field life of a battery is assumed to be 3 years, approx. 7 batteries

Where: C1 = observed capacity at t°C, R 17

= variation factor, .43 for C10 and above, and

Manish Singh Bisht and Hiren Chandra Borah

Fig. 2. Initial capacity of all samples

't' = average cell temperature measured at terminals in °C.

The samples were marked for identification and 10 batteries were deployed in street light systems at different locations in the campus and the remaining two were kept as reference. The reference batteries were subjected to a programmed load profile inside the lab resembling to the batteries deployed in street lights. They were charged in the day time and discharged in night with the same current as that of SSLS batteries. The programme was so prepared that the operating timings of all batteries were synchronised with each other. Basically, field

These capacity tests were performed with the help of a Life Cycle Network (LCN) Machine, made Bitrode Corporation, USA. This LCN machine is a programmable power supply with an electronic load and inbuilt data logger. It is interfaced with a computer and the data could be monitored in real time and recorded. This machine confronts to the international standards of testing and is regularly calibrated.

Fig. 3. Test results at end of 1 year

18


circuits and were subjected to the same load profile.

operating conditions were simulated for the reference batteries. Temperature sensors were also installed with the street lights to record ambient temperature and the temperature within the battery box.

3.2 Testing at end of two years For one more complete year the batteries were properly observed and subjected to same maintenance plan as performed in first year. Then these batteries were disconnected from operation to examine the capacity values. All these batteries were removed from their individual systems after sunset so as to allow them to recover the charge lost during night. The testing day was so selected when there had been a proper sunny week to ensure that the batteries remained charged and reflected real capacity values. Prior to testing the voltage levels of all samples were recorded which reflected fully charged state. The capacity test performed on all the samples for two test runs and the values reflected by second test run were recorded.

3.1 Testing at end of 1st Year For one year all 12 samples were observed. The samples installed in the street lights were further divided into two groups each containing 5 street lights. One of the groups was subjected to complete maintenance profile involving cleaning of solar modules, inspection of wires and battery etc. The other group was also given the same maintenance profile except for the cleaning of solar modules which was left to receive cleaning through natural means only. It was done to analyse the effect of manual cleaning of modules in SSLS on the battery performance. The reference samples were also subjected to regular maintenance and inspection.

4.

After one year of operation all the samples were bought to the testing circuit for capacity examination and the corresponding values were recorded. The day of testing was so selected that there had been a proper sunny week prior to the day so that full charge condition of the batteries can be assumed. Two test run were subjected on each battery and the values of second test run were recorded. After capacity analysis, all the samples were replenished with full charge and restored to their previous systems. The reference batteries were also reconnected to their

Test Results and Discussion

The batteries had been operational in the street light systems for about one year and were properly maintained. All the batteries were subjected to same depth of discharge or load profile. The maintenance profile of all the field systems was same except for the cleaning of solar module which was performed only in 5 systems. At end of one year it was found that the reference samples had degraded by about 10% of the initial average capacity of all samples. The degradation in the samples which received cleaning

Fig. 4. Test results at end of 2nd year

19


importance and also the whole unit is located at a particular place. Also there are many terms and conditions reflected in the power purchase agreement which force the plant owner to keep the plant in sound health. But the same theory is not valid for street lighting systems since these systems are scattered installations and also no workforce is deployed for their maintenance. Also the modules in these systems are rarely cleaned by the beneficiary. Accountability is also a big concern here. These systems are given revival only when the fault has occurred. The dust accumulated on the modules causes low current being generated by the module and hence the battery remains in partial state of charge or near fully discharged condition. This results in premature ageing of the batteries used in street lighting systems. It has also been identified that the wrong orientation of modules is also a big cause of low current being generated by the module. When module is installed in vertical position sufficient space is available in the lower portion so that the dust accumulation is not a big problem. But when the module is installed in the horizontal position the accumulated dust covers the cell area thus causing low current to be generated. It also effects the life of battery since it remains undercharged.

of modules was found to be 30% of the initial average values. Similarly, the samples in which modules were not cleaned manually, showed degradation of 46% of the initial average capacity values. After two years of operation, under same load profile, the tests for available energy showed that the degradation in reference batteries was about 27% of the initial average capacity values. The systems in which solar modules had been cleaned showed degradation of about 62% of the initial average capacities. The systems in which modules were not cleaned manually showed degradation of about 81% as compared with the initial average capacities. Also the recorded temperature values show that in the conventional design of battery boxes used in India the temperature inside the battery box rose to 60°C when the ambient was around 42°C (fig. 5). The above work shows that the main causes for early ageing of VRLA batteries in SSLS in India are: •

Unclean modules resulting in low charging current to battery hence forcing the battery to operate on partially charged mode.

•

High operating temperatures inside the battery box.

Analysis of the operating temperature also revealed a major cause for early ageing of batteries. It was found that the typical design of battery boxes used in India results in high operating temperatures inside the battery box as compared to ambient. When the ambient ishighest in peak summer the operating temperature reaches to about 65°C inside the battery box. As a thumb rule it is assumed that the life of a

The solar modules in a SSLS are seldom cleaned manually due to height and non-accountability. This results in accumulation of dust on the module. In a power plant a lot of manpower is deployed for maintenance which follows a proper maintenance plan from cleaning of modules to checking output voltage. It is easy because a plant had greater financial

Fig. 5. Ambient temp vs. battery box temp

20


together result in accelerating the battery to end of its life in just 2 years. The first cause can be easily overcome by implementing proper and regular maintenance plan covering all the components of the system. It will ensure that maximum charging current is available for the battery thus replenishing the charge lost in powering load. It will also keep the D.O.D. of the battery as low as it is designed for. The second cause will need an innovative and proper designing of the battery box which could not only keep the temperature inside near to the ambient but also protect the battery completely from environmental conditions. During the maintenance work it was also observed that the battery terminals and battery box attracted rust which could lead to operational problems. Also the battery box paint used to shed inside on the battery due to high temperatures which could even lead to short circuiting of terminals. For optimum performance of a battery it is advised that the battery should be regularly maintained i.e. cleaning of terminals, applying gel on terminals, cleaning of battery box, cleaning of modules, inspecting contacts and wires and measuring module voltage from time to time.

Fig. 6. Wrong orientation

Fig. 8. Un-cleaned Battery

One big step could also be inclusion of the local people in the project as they are direct beneficiary. They should be trained on basic operation and maintenance and made accountable of the systems in their locality.

Fig. 7. Right Orientation

VRLA battery reduces to half by every 8°C rise in standard operating temperatures. All these factors 21


References [1]

www.mnre.gov.in

[2]

www.bis.org

[3]

Gustavsson M. and Mtonga D., Lead-acid battery capacity in solar home systems. Field tests and experiences in Lundazi, Zambia, Solar Energy, 79, (2005) 551-558.

[4]

Abavana C.G., Renewable energy for rural electrifica-tion: The Ghana Initiative. Seminar on Rural Energy Provision in Africa, International Solar Energy Society, Nairobi, Kenya, (2000).

[5]

Armenta-Deu C., Prediction of battery behaviour in SAPV application. Renewable Energy, 28, (2003) 1671-1684.

[6]

Dlaz´P. and Egido M.A., Experimental analysis of battery charge regulation in photovoltaic systems. Progress in Photovoltaic Research and Application, 11, (2003) 481-493.

[7]

Dlaz´P. and Lorenzo E., Solar home system battery and charge regulator testing. Progress in Photovoltaic Research and Application 9, (2001) 363-377.

[8]

Huacuz J.M., Flores R., Agredano J. and Munguia G., Field, (1995).

[9]

Performance of lead-acid batteries in PV rural electrification kits, Solar Energy, 55(4), 287-299.

Fig. 9. Rusted Battery Box

5.

Conclusion

Under normal operation a VRLA battery is working satisfactorily and the degradation is within limits. However, same battery is showing significant degradation when deployed in field even though the system receives complete and regular maintenance. But degradation becomes severe if the battery is deployed in field and the module is not cleaned manually once in a while. It causes the battery to reach its end of life in just two years which raises concern.

[10] Lorenzo E., In the field: Realities of some PV Rural Electrification Projects. Renewable Energy World, (2000) 38-51.

When the whole world is busy in designing cost effective systems for rural electrification, especially in developing countries, low performance of batteries in these systems would hinder their success. It would not only increase the operating cost of systems but will also deface the impression of technology. The biggest enemy of battery life comes out to be the temperature which is higher than the ambient inside batter6y box. It requires introduction of an innovative design to combat the temperature effect. Also the cooperation of end-users should be sought for better system life. The training of end user and awareness among them is very necessary. 6.

[11] Nieuwenhout F.D.J., van Dijk A., van Roekel G., van Dijk D., Hirsch D., Arriaza H., Hankins M., Sharma B.D. and Wade H., Experience with solar home systems in developing countries: A review. Progress in Photovoltaic Research and Application 9, (2001) 455-474. [12] PVPS, Lead-acid battery guide for stand-alone photovol-taic systems, IEA Photovoltaic Power Systems Programme (PVPS), (1999) 33. [13] PVPS, Testing of batteries used in standalone PV power supply systems, Test Procedures and Examples of Results, IEA Photovoltaic Power Systems Programme (PVPS), (2002) 43.

Acknowledgements

[14] Reinders A.H.M.E., Pramusito, Sudradjat A., van Dijk R., Mulyadi R. and Turkenburg W.C., Sukatani revisited: On the performance

This work was supported by the staff and administration of NISE. 22


of nine-year-old solar home systems and street lighting systems in Indonesia. Renewable and Sustainable Energy Reviews, 3, (1999) 1-47. [15]

[16]

photovoltaic systems. Journal of Power Sources 53, (1995) 245-253.

Sauer D.U., Electrochemical storage for photovoltaic. In: Luque, A., Hegedus, S. (Eds.), Handbook of Photovoltaic Science and Engineering. John Wiley & Sons Ltd, West Sussex, England, (2003) 799-862. Spiers D.J. and Rasinkoski A.D., Predicting the service lifetime of lead/acid batteries in

23

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Spiers D.J. and Rasinkoski A.A., Limits to battery lifetime in photovoltaic applications. Solar Energy, 58(4-6), (1996) 147- 154.

[18]

Stapleton G., Gunaratne L. and Konings P.J.M., The Solar Entrepreneur s Handbook. Global Sustainable Energy Solutions Pty Ltd., Ulladulla, (2002).

DOI No. : 10.5958/2454-7611.2018.00004.8 Samapti Kundu and Swapan Invertis Journal of Renewable Energy, Vol. 8, No. 1, 2018 ; pp.Kumar 24-29 Pradhan

Enhanced photocatalytic performance of ZnO nanocrystals with different morphological variation and their structural characterization SAMAPTI KUNDU and SWAPAN KUMAR PRADHAN* Materials Science Division, Department of Physics, University of Burdwan Golapbag, Burdwan-713104, West Bengal, India *E-mail: [email protected] Abstract Nanocrystalline ZnO powder and different morphological structure of ZnO (both Rod and Flower like) are synthesized through mechanical alloying and a simple wet chemical route without using any template at room temperature respectively. Here, we report primarily different morphological structure of ZnO and their microstructure interpretations by analyzing X-ray diffraction patterns employing Rietveld refinement and field emission scanning electron microscopy (FESEM). UVVis spectrum reveals the change in optical band gap of ZnO due to morphological changes. The photocatalytic activity of these nanostructures has also been presented. The ZnO nanostructures like nanorods and nanoflowers exhibit an excellent photocatalytic activity in compare to that of nanoparticles. Being a wide band gap semiconductor, these unique nanostructures will have a prospective application in ZnO based dye sensitized solar cells. Key words : ZnO; Wet Chemical Route; Morphology; Rietveld Analysis; Photocatalytic Activity.

1.

Introduction

(NRs) and nanoflowers (NFs) through mechanical alloying and wet chemical route at room temperature[7]. From an application and technological point of view, we have attempted the photodecomposition of methylene blue (MB) dye using these ZnO nanostructures (NPs, NRs and NFs). ZnO NRs and NFs are found to exhibit a promising photocatalytic activity.

Water pollution resulting from toxic organic pollutants is a severe global issue[1]. Photocatalysis through metal oxide semiconductors act as benchmarks for such environmental remediation[2]. Amongst the large number of semiconducting nanomaterials, ZnO offers favorable properties such as high direct band gap (3.37 eV), large exciton binding energy (60 meV), high mechanical and chemical firmness, low cost and environmental sustainability, hence it has been identified as a promising catalyst for the photodegradation applications[2-5]. To enrich the catalytic behaviour of ZnO, nanostructures of different morphology and size have been achieved through various physical and chemical methods[3-4]. In this article, we report systematic studies on the synthesis of highly crystalline ZnO nanostructures processing different morphologies such as nanopowders (NPs), nanorods

2.

Experimental

2.1 Synthesis The nanocrystalline ZnO nanopowder was synthesized by mechanica alloying the commercial grade ZnO precursors. To synthesize ZnO NRs and NFs two solutions were prepared separately by dissolving 0.038 mol ammonium persulphate ((NH4)2S2O8) and 0.191 mol of sodium hydroxide (NaOH) in 20 ml of D. I. water

24

Enhanced photocatalytic performance of ZnO nanocrystals with different morphological variation

each. While stirring 0.9 g zinc metal powder (Merck chemical) in 10 ml D. I. water, the mixture of the two aforementioned solutions was added dropwise. By Changing the concentration of {NaOH+(NH4)2S2O8} morphological change from ZnO NR to ZnO NF have been obtained. 2.2 Materials Characterization Rietveld software MAUD version 2.26[6] was used to carry out simultaneous refinement of both material structure and microstructure by a least squares refinement method of the XRD patterns obtained by employing Ni filtered CuKα radiation from a Bruker D8 Advanced diffractometer. The surface morphologies were revealed from the FESEM images. Photocatalytic activity of ZnO nanostructures were evaluated by using 500 watt halogen lamp as visible light irradiation source[5] and also by monitoring the residual concentration of MB dye in presence of ZnO nanostructures (photocatalyst) by using a SHIMA-DZU UV-1800 model UV-Vis spectrophotometer.

Fig. 1. Observed (•) and simulated (–) XRD patterns of ZnO nanopowders/particles, nanorods and nanoflowers as revealed from the Rietveld powder structure refinement analysis. IO-IC represents the difference between the observed and simulated patterns.

(c) respectively. It is well observed that all the patterns are indexed with ZnO phase (ICSD database no. 65121, Sp. Gr. P63mc ; hexagonal; a=b= 3.25682 Å; c= 5.21251 Å) which confirms the complete formation of ZnO nanocrystals. Rietveld analysis output clearly shows that in case of nanorods and nanoflowers, peaks are less broadened and clearly resolved than those of the powder pattern. More clearly, it can be seen that peak width of all the reflections obtained for the ZnO NPs, which was prepared by mechanical alloying, are almost equal; however in case of NRS and NFs, the peak for (002) is less broadened in comparison to other reflections. This indicates that ZnO powder is composed of isotropic particles, however in case NRs and NFs particles are anisotropic and are elongated along the plane. From the profile fitting residue (I0-IC), it is clear that fitting quality of these patterns are considerably good. The structural and microstructural parameters of ZnO NPs, NRs and NFs obtained from Rietveld analysis are shown in Table 1 and Table 2 respectively.

2.2 Materials characterization XRD patterns obtained by employing Ni filtered CuKα radiation from a Bruker D8 Advanced diffractometer. Photocatalytic activity of brookite TiO2 nanostructures were evaluated by using 500 watt halogen lamp as visible light irradiation source[4] and also by monitoring the residual concentration of RhB dye in presence of brookite TiO2 nanostructures (photocatalyst) by using a SHIMADZU UV-1800 model UV-Vis spectrophotometer. 3.

Result and Discussion

3.1 Phase Identification and Phase content estimation Typical Rietveld analysis outputs of XRD patterns of ZnO nanopowders (NPs), nanorods (NRs) and nanoflowers (NFs) are shown in figure 1 (a), (b) and

Table 1. Variation of Structural parameters with morphological change of ZnO nanocrystals. Shape NP NR NF

Lattice Parameters (Å) 3.2467 3.2526 3.2550

5.2051 5.2090 5.2110 25

Atomic Coordinates

Oxygen Occupancy

0.3690 0.3710 0.3806

1.0070 1.1030 1.1250

Samapti Kundu and Swapan Kumar Pradhan

Table 2. Variation of crystallite size with morphological change of ZnO nanocrystals. Shape NP

NR

NF

Diffracting Plane

Crtallite Size (nm)

(100) (002) (101) (100) (002) (101) (100) (002) (101)

17.22 17.22 17.22 15.39 41.66 31.40 14.81 29.81 15.16

3.2 Optical Properties Room temperature UV-visible absorbance spectra of powder, rod and flower like ZnO nanocrystals are shown in fig. 2. A comparative result clearly reveals that a progressive red shift is observed in the transformation from ZnO nanopowder → nanorod → nanoflower[7].

Fig. 3. Photoluminescence spectra of ZnO (a) NP, (b) NR and (c) NFs.

nm , is generally assigned as the defect related transition arising out of excess oxygen in the ZnO crystal[7]. This broad peak within the green yellow band region is mainly responsible for the promising photocatalytic performance of ZnO nanorods. 3.3 Surface Morphology Surface morphologies of ZnO NPs, NRs and NFs are shown in fig. 4 (a), (b) and (c) respectively. Some agglomerated ZnO nanopowders and ZnO NRs obtained after 5h of mechanical alloying and 5h of reaction time is shown in figure 2(a) and (b)

Fig. 2. UV-Visible Absorbance spectra of ZnO (a) NP, (b) NR and (c) NFs.

Fig. 3 represents the room temperature PL spectrum of ZnO NP, NR and NFs. The high energy UV-emission peak at ~ 399 nm appears due to recombination of excitons through an exciton-exciton collision process. the broad one, approximately within the range of 550-600 nm centered around 570 26


Fig. 4. FESEM images of ZnO (Nanopowders (NPs), Nanorods (NRs) and Nanoflowers (NFs).

respectively. Figure 4 (c) shows the flower like morphology resulting from the superposition of a number of ZnO NRs. It is also observed to taht ZnO NRs are one end tied to a common (thread/string) line and the other free end blossomed over all possible directions. 4.

Photocatalytic Activity and Mechanism

The photocatalytic properties of ZnO nanocrystals (particles, rods and flowers) are evaluated in terms of the photodegradation of methylene blue in aqueous solution under visible light irradiation (λ > 420 nm) at room temperature. Figure 5 (a), (b) and (c) shows the UV-Vis absorption spectra of aqueous solution of MB (initial concentration 5 mgL–1, 100 mL) during the contact

Fig. 5. (a), (b) and (c) are absorbance spectral change of MB dye solution in presence of ZnO NP, NR and NF respectively.

27

Samapti Kundu and Swapan Kumar Pradhan

with the same amount (20 mg) of the different photocatalysts ZnO NP, NR and NF respectively for various time duration under visible light irradiation. The photocatalytic activity of ZnO NP, NR and NFs are compared by computing the variation in MB concentration (C) at irradiation time (t) relative to its initial value (C0) at irradiation time (zero). Fig. 6 elucidates the visible light exposure time dependent degradation of MB dye via the as synthesized NP, NR and NFs like ZnO nanocrystals in terms of the relative concentration ratio C/C0. The percentage of degradation is calculated by using equation {C0 – C/C0} × 100

Fig. 7. Schematic diagram of the photocatalytic activity of ZnO nanocrystals.

(1)

Remarkable 57.16%, 74.80% and 66.65% of the dye is degraded by the presence of ZnO NP, NR and NF respectively. Reaction rate constants are calculated assuming first order kinetics (eqn 2) for low pollutant concentration ln(C0/C) = kt

reactions.[8] After excitation of light, an electron in the valence band (VB) of the semiconductor is excited to the conduction band (CB) with the simultaneous generation of a hole in the VB. The excited electrons are trapped by O2 to form superoxide (.O-2) and the holes left in the valence band can react with adsorbed water (or surface hydroxyl) to form very reactive hydroxyl radicals (.OH) which then reacts with the adsorbed pollutant molecules (MB dye) to produce oxidized species and decomposed products. (Fig. 7).

(2)

Fig. 4 (b) confirms first order kinetics with k = 0.0055, 0.0088 and 0.0069 min–1 for ZnO NP, NR and NF respectively. The photocatalytic properties of semiconductors depend on the ability to create electron-hole pairs and the formation of free radicals for secondary

5.

Conclusions In a nutshell, we have demonstrated the synthesis

Fig. 6. (a) Plot of C/C0 (%) (where C0 and C are the concentrations of dye before and after irradiation respectively) for MB as a function of irradiation time in the presence of ZnO NP, NR and NFs respectively, (b) Plot of ln(C0/C) as a function of irradiation time.

28


of ZnO NCs (NP, NR and NF) through simple mechanical alloying and wet chemical route without using any template at room temperature. The crystal structure and microstructure of different ZnO NCs have been elucidated by analyzing their XRD pattern through Rietveld refinement method and surface morphology has also been confirmed through FESEM images.Optical properties of ZnO NCs has also been evaluated through UV-Vis and PL spectroscopy. We have also demonstrated the photocatalytic activity of ZnO NCs and it has been noticed that flower and rod like ZnO NCs show superior photocatalytic activity than that of ZnO NPs. 6.

Acknowledgment

The authors are thankful to the University Grants Commission (UGC) India, for granting the "Centre of Advanced Study" programme under the thrust area "Condensed Matter Physics including Laser Applications" to the Department of Physics, Burdwan University under the financial assistance of which the work has been carried out. S. Kundu wishes to thanks Department of Science and Technology (DST) for providing INSPIRE research fellowship to carry out the research work.

[2]

Adhikari S., Sarkar D., "Metal oxide oxide semiconductor for dye degradation," Mater. Res. Bull, 72, (2015) 220-228.

[3]

Warule S.S., Chaudhari N.S., Kale B.B. and More M.A., "Novel sonochemical assisted hydrothermal approach towards the controllable synthesis of ZnO nanorods, nanocups and nanoneedles and their photocatalytic study," Cryst. Eng. Comm., 11, (2009) 2776-2783.

[4]

Abbas K.N. and Bidin N., "Morphological driven photocatalytic activity of ZnO nanostructures," App. Surf. Sci, 394, (2017) 498508.

[5]

Kole A.K., Tiwary C.S. and Kumbhakar P., "Ethylenediamine assisted synthesis of wurtzite zinc sulphide nanosheets and porous zinc oxide nanostructures: near white light photoluminescence emission and photocatalytic activity under visible light irradiation," Cryst. Eng. Comm., 15, (2013) 5515-5525.

[6]

Lutterotti L., MAUD version 2.26, http:// www.ing.unitn.it/~maud/.

[7]

Kundu S., Sain S., Satpati B., Bhattacharyya S.R. and Pradhan S.K., "Structural interpretation, growth mechanism and optical properties of ZnO nanorodssynthesized by a simple wet chemical route," Rsc. Adv., 5, (2015) 23101231113.

[8]

Kar A., Sain S., Kundu S., Bhattacharyya A., Pradhan S.K. and Patra A., "Influence of Size and Shape on the Photocatalytic Properties of SnO2 Nanocrystals," Chem. Phys. Chem., 16, (2015) 1017-1025.

References [1]

Thankkachan R.M., Joy N., Abrahan J., Kalarikkal N., Thomas S. and Oluwafemi O.S., "Enhanced photocatalytic performance of Zno nanostructure produced via a quick microwave assisted route for the degradation of rhodamine in aqueous solution," Mater. Res. Bull, 85, (2017) 133-139.

29

No.Pradhan : 10.5958/2454-7611.2018.00005.X Rajib Kumar Samapti Kundu and SwapanDOI Kumar Invertis Journal of Renewable Energy,Mandal, Vol. 8, No. 1, 2018 ; pp. 30-32

Photocatalytic studies of nanocrystalline Brookite TiO2 obtained by mechanical alloying of V2O5 and anatase TiO2 stoichiometric mixture RAJIB KUMAR MANDAL1, SAMAPTI KUNDU2 and SWAPAN KUMAR PRADHAN2* 1 AKPC Mahavidyalaya, Bengai, Hooghly-712611, West Bengal, India. 2 Materials Science Division, Department of Physics, The University of Burdwan, Golapbag, Burdwan-713104, West Bengal *E-mail: [email protected] Abstract We report the synthesis and visible light induced catalytic activity of brookite TiO2 nanocrystals. Brookite TiO2 nanostructure has been prepared by mechanical alloying the stoichiometric mixture of V2O5 and anatase TiO2 powders for 15h at room temperature in a planetary ball mill. The visible light driven photocatalytic activity have also been investigated with Rhodamine B dye molecules. The adsorption of the dye molecules on the photocatalyst surface have played a critical role in their selective photodegradation under visible light illumination. Key words : Brookite TiO2, Mechanical alloying, Photocatalytic study

1.

Introduction

2.

Titanium dioxide (TiO2) has been extensively explored because of its superior photocatalytic activity under visible light irradiation, high chemical stability and low cost[1, 2]. However the wide band gap (3.2 eV) of TiO2 only shows it to absorb the ultraviolet light (< 387 nm) that limits the utilization of solar light since UV light in solar light is less than 5%. Hence much effort has been devoted to fabricate TiO2-based photocatalyst which is capable of efficient utilization of the visible light. Recently, many studies have attempted to increase the photocatalytic activity efficiency of TiO2 by doping it with other metal oxides[1, 3]. In the present study, we report the synthesis of nanocrystalline brrokite TiO 2 by mechanical alloying of Orthorhombic V2O5 (O-V2O5) and anatase TiO2 (a-TiO2) stoichiometric mixture. Here a phase transition of TiO2 from anatase to brookite phase is observed during mechanical alloying. In addition the photocatalytic performance of brookite TiO2 (b-TiO2) prepared by ball milling the decomposition of Rhodamine B solution exposed to visible light.

Experimental

2.1 Synthesis Stoichiometric Titanium dioxide (purity 99.5%, Loba Chem.), Vanadium pentoxide(purity 99.5%, Sigma-Aldrich) were weighed (BPMR 20:1) in 1:1 mol fractions respectively. Powders were then kept inside a 80 ml chrome-steel (c-s) vial filled with 30 (c-s) balls of 10 mm diameter . Mechanical Alloying of the powder mixture inside the vial was carried out at room temperature in a planetary ball mill (modelP5, M/S Fritsch, GmbH, Germany) at 200 rpm. 2.2 Materials characterization XRD patterns obtained by employing Ni filtered CuKα radiation from a Bruker D8 Advanced diffractometer. Photocatalytic activity of brookite TiO2 nanostructures were evaluated by using 500 watt halogen lamp as visible light irradiation source[4] and also by monitoring the residual concentration of RhB dye in presence of brookite TiO2 nanostructures (photocatalyst) by using a SHIMADZU UV-1800 model UV-Vis spectrophotometer. 30

Photocatalytic studies of nanocrystalline Brookite TiO2 obtained by mechanical alloying of V2O5

3.


3.1 Nanostructure characterization by XRD Fig. 1 represents the XRD patterns of (a) unmilled a-TiO2-O-V2O5 mixture and (b) ball milled b-TiO2 nanocrystals. In Fig. 1 (a) shows that the unmilled mixture are composed of Anatase-TiO2 (JCPDF 211272; Tetragonal; Sp.Gr. I41/amd; a=b=3.7852 Å, c=9.5139 Å) and orthorhombic V2O5 (JCPDF 41-1426; Sp. Gr. Pmmn; a = 11.51 Å, b = 3.56 Å, c = 4.37 Å) reflections only. All reflections are well resolved and it clearly indicates that the particle sizes of both starting ingredients are quite large and they are almost free from lattice strain. Fig. 2(a) shows that after 15h of mechanical alloying of a-TiO2 and O-V2O5 are completely disappeared in the XRD pattern, indicating a complete transformation to b-TiO2. Peak broadening of all the reflections are observed after 15h of mechanical alloying which indicates the rapid reduction of particle size.

Fig. 2. Absorbance spectral change of RhB dye solution in presence of brookite TiO2.

Fig. 3. Plot of C/C0 (%) (where C0 and C are the concentrations of dye before and after irradiation respectively) for RhB as a function of irradiation time in the presence of brookite TiO2 nanocrystals.

Fig. 1. XRD patterns of (a) unmilled a-V2O5-O-TiO2 mixture and (b) ball milled brookite TiO2 nanocrystals.

of Rhodamine B have been decreased with the increase of exposure time in presence of brookite TiO2 nanocrystals. Since Rhodamine B can be decomposed by OH radical which is generated by activated photocatalyst, Fig. 2 indicates the photocatalytic activation of brookite TiO2 nanocrystals under visible light. Fig. 3 and fig. 4 shows the corresponding concentration changes and the reaction rate (k) as a function of irradiation time in presence of brookite

3.2 Photocatalytic Studies The photocatalytic performance of synthesized brookite TiO2 nanocrystals have been examined by the decomposition of Rhodamine B solution under visible light. Fig. 2 represents UV-visible absorption spectra of Rhodamine B solutions which contain brookite TiO2 nanocrystals. The solution have been exposed to visible light upto 240 min. The absorbance 31

Rajib Kumar Mandal, Samapti Kundu and Swapan Kumar Pradhan

photocatalytic study shows that photodegradation rate of RhB by brookite TiO2 nanocrystals is much faster than that using pure TiO 2 as previously reported. 5.

Acknowledgment

The authors are thankful to the University Grants Commission (UGC) India, for granting the "Centre of Advanced Study" programme under the thrust area "Condensed Matter Physics including Laser Applications" to the Department of Physics, Burdwan University under the financial assistance of which the work has been carried out. S.Kundu wishes to thank Department of Science and Technology (DST) for providing INSPIRE fellowship to carry out the research work. Fig. 4. Plot of C/C0 (%) (where C0 and C are the concentrations of dye before and after irradiation respectively) for RhB as a function of irradiation time in the presence of brookite TiO2 nanocrystals.

References

TiO2 photocatalyst. The percentage of degradation is calculated by using equation. {C0-C/C0} × 100

[1]

Jianhua L., Rong Y. and Songmeri L., "Preparation and characterization of the TiO2V2O5 photocatalyst with visible light activity", Rare metals, 25, (2006) 636-642.

[2]

Wang Y., Y.R. su, L. Qiao, L.X. liu, Q. Su. C.Q. Zhu and X.Q. Liu, " Synthesis of one dimensional TiO 2 /V 2 O 5 branched heterostructures and their visible light photocatalytic activity towards rhodamine B", Nanotechnology, 22, (2011) 225702.

[3]

Choi S., Lee M.S. and Park D.W., "Photocatalytic performance of TiO 2/V 2 O5 nanocomposite powder prepared by DC arc plasma", Curr. Appl. Phys., 14, (2014) 433-438.

[4]

Kole A.K., Tiwary C.S. and Kumbhakar P., "Ethylenediamine assisted synthesis of wurtzite zinc sulphide nanosheets and porous zinc oxide nanostructures: near white light photoluminescence emission and photocatalytic activity under visible light irradiation", Cryst. Eng. Comm., 15, (2013) 5515-5525.

(1)

Reaction rate constants are calculated assuming first order kinetics (eqn 2) for low pollutant concentration. ln (C0/C) = kt

(2)

The degradation rate of RhB with brookite TiO2 as photocatalyst is ~62% where as for pure TiO2 the degradation rate is ~ 27%[2]. 4.

Conclusions

In summary, We have demonstrated the synthesis of brookite TiO2 nanocrystals through a simple mechanical alloying of orthorhombic-V2O5 and anatase TiO 2 stoichiometric mixture. The

32

of Biofuels India DOI No. : 10.5958/2454-7611.2018.00006.1 Invertis Journal of Renewable Energy, Vol.Production 8, No. 1, 2018 ; pp. in 33-38

Production of Biofuels in India ANITA SHARMA Chemistry Department, N.A.S. (PG), College, Meerut *E-mail: [email protected] Abstract The energy strategy of a country aims at efficiency and security and to provide access which being environment friendly and achievement of an optimum mix of primary resources for energy generation. Renewable energy resources are indigenous, non-polluting and virtually inexhaustible. India is endowed with abundant renewable energy resources. Therefore, their use should be encouraged in every possible way As, the conventional sources of energy drying up at faster rate, the alternate sources should be explored, examined and implemented in no time. Key words : Biofuel; Algae; Cellulosic Ethanol; Jatropha.

1.

Introduction

involved in the formation of fossil fuels, such as coal and petroleum, from prehistoric biological matter.

India is one of the fastest growing economies in the world. The Development Objectives focus on economic growth, equity and human well being. Energy is a critical input for socio-economic development. Fossil fuels will continue to play a dominant role in the energy scenario in our country in the next few decades. However, conventional or fossil fuel resources are limited, non-renewable, polluting and, therefore, need to be used prudently. On the other hand, renewable energy resources are indigenous, non-polluting and virtually inexhaustible. India is endowed with abundant renewable energy resources. Therefore, their use should be encouraged in every possible way. India's energy security would remain vulnerable until alternative fuels to substitute/supplement petrobased fuels are developed based on indigenously produced renewable feed stocks. Biofuels are environment friendly fuels and their utilization would address global concerns about containment of carbon emissions. 2.

'Biofuels' are liquid or gaseous fuels produced from biomass resources and used in place of, or in addition to, diesel, petrol or other fossil fuels for transport, stationary, portable and other applications. Biofuels can be derived directly from plants or indirectly from agricultural, commercial, domestic and/or industrial wastes[1]. 2.1 First-generation biofuels "First-generation" or conventional biofuels are biofuels made from food crops grown on arable land. With this biofuel production generation, food crops are thus explicitly grown for fuel production, and not anything else. The sugar, starch, or vegetable oil obtained from the crops is converted into biodiesel or ethanol, using transesterification, or yeast fermentation. 2.2 Second-generation biofuels Second generation biofuels are fuels produced from agricultural residues containing cellulosic biomass such as the stalks, leaves, bagasse and husks of rice, wheat, woodchips, sawdust or energy crops.1[2]4 Whereas first generation biofuels are made from the sugars and vegetable oils found in arable crops, second generation biofuels are made from

Types of biofuels

A biofuel is a fuel that is produced through contemporary biological processes, such as agriculture and anaerobic digestion, rather than a fuel produced by geological processes such as those 33

Anita Sharma

lignocellulosic biomass or woody crops, agricultural residues or waste plant material (from food crops).

3.2 Second-generation biofuels Second generation biofuels are fuels produced from agricultural residues containing cellulosic biomass such as the stalks, leaves, bagasse and husks of rice, wheat, woodchips, sawdust or energy crops.1[2]4 Whereas first generation biofuels are made from the sugars and vegetable oils found in arable crops, second generation biofuels are made from lignocellulosic biomass or woody crops, agricultural residues or waste plant material (from food crops).

2.3 Third-generation biofuels A self-published article by Michael Briggs, at the UNH Biofuels Group, offers estimates for the realistic replacement of all vehicular fuel with biofuels by using algae that have a natural oil content greater than 50%, which Briggs suggests can be grown on algae ponds at wastewater treatment plants[3]. This oil-rich algae can then be extracted from the system and processed into biofuels, with the dried remainder further reprocessed to create ethanol.

3.3 Third-generation biofuels A self-published article by Michael Briggs, at the UNH Biofuels Group, offers estimates for the realistic replacement of all vehicular fuel with biofuels by using algae that have a natural oil content greater than 50%, which Briggs suggests can be grown on algae ponds at wastewater treatment plants[3]. This oil-rich algae can then be extracted from the system and processed into biofuels, with the dried remainder further reprocessed to create ethanol.

2.4 Fourth-generation biofuels Similarly to third-generation biofuels, fourthgeneration biofuels are made using non-arable land. However, unlike third-generation biofuels, they do not require the destruction of biomass. This class of biofuels includes electrofuels and photobiological solar fuels. Some of these fuels are carbon-neutral. The conversion of crude oil from the plant seeds into useful fuels is called transesterification. 3.

3.4 Fourth-generation biofuels

Types of biofuels

Similarly to third-generation biofuels, fourthgeneration biofuels are made using non-arable land. However, unlike third-generation biofuels, they do not require the destruction of biomass. This class of biofuels includes electrofuels and photobiological solar fuels. Some of these fuels are carbon-neutral. The conversion of crude oil from the plant seeds into useful fuels is called transesterification.

A biofuel is a fuel that is produced through contemporary biological processes, such as agriculture and anaerobic digestion, rather than a fuel produced by geological processes such as those involved in the formation of fossil fuels, such as coal and petroleum, from prehistoric biological matter. 'biofuels' are liquid or gaseous fuels produced from biomass resources and used in place of, or in addition to, diesel, petrol or other fossil fuels for transport, stationary, portable and other applications. Biofuels can be derived directly from plants or indirectly from agricultural, commercial, domestic and/or industrial wastes[1].

4.

Production of biofuels

The following fuels can be produced using first, second, third or fourth-generation biofuel production procedures. Most of these can even be produced using two or three of the different biofuel generation procedures.

3.1 First-generation biofuels

4.1 Ethanol

"First-generation" or conventional biofuels are biofuels made from food crops grown on arable land. With this biofuel production generation, food crops are thus explicitly grown for fuel production, and not anything else. The sugar, starch, or vegetable oil obtained from the crops is converted into biodiesel or ethanol, using transesterification, or yeast fermentation.

Ethanol fuel is the most common biofuel worldwide, particularly in Brazil. Alcohol fuels are produced by fermentation of sugars derived from wheat, corn, sugar beets, sugar cane, molasses and any sugar or starch from which alcoholic beverages such as whiskey, can be made (such as potato and fruit waste, etc.). The ethanol production methods 34

Production of Biofuels in India

used are enzyme digestion (to release sugars from stored starches), fermentation of the sugars, distillation and drying. The distillation process requires significant energy input for heat (sometimes unsustainable natural gas fossil fuel, but cellulosic biomass such as bagasse, the waste left after sugar cane is pressed to extract its juice, is the most common fuel in Brazil, while pellets, wood chips and also waste heat are more common in Europe) Waste steam fuels ethanol factory where waste heat from the factories also is used in the district heating grid.

soy, rapeseed, jatropha, mahua, mustard, flax, sunflower, palm oil, hemp, field pennycress, Pongamia pinnata and algae. Pure biodiesel (B100, also known as "neat" biodiesel) currently reduces emissions with up to 60% compared to diesel Second generation B100. Biodiesel can be used in any diesel engine when mixed with mineral diesel. Biodiesel is also an oxygenated fuel, meaning it contains a reduced amount of carbon and higher hydrogen and oxygen content than fossil diesel. This improves the combustion of biodiesel and reduces the particulate emissions from unburnt carbon. However, using pure biodiesel may increase NOx-emissions. Biodiesel is also safe to handle and transport because it is nontoxic and biodegradable, and has a high flash point of about 300 °F (148 °C) compared to petroleum diesel fuel, which has a flash point of 125 °F (52 °C)[6].

Ethanol can be used in petrol engines as a replacement for gasoline; it can be mixed with gasoline to any percentage. Most existing car petrol engines can run on blends of up to 15% bioethanol with petroleum/gasoline. Ethanol has a smaller energy density than that of gasoline; this means it takes more fuel (volume and mass) to produce the same amount of work. An advantage of ethanol (CH3CH2OH) is that it has a higher octane rating than ethanol-free gasoline available at roadside gas stations, which allows an increase of an engine's compression ratio for increased thermal efficiency. In high-altitude (thin air) locations, some states mandate a mix of gasoline and ethanol as a winter oxidizer to reduce atmospheric pollution emissions.

In the USA, more than 80% of commercial trucks and city buses run on biodiesel. In France, biodiesel is incorporated at a rate of 8% in the fuel used by all French diesel vehicles. 4.3 Other bioalcohols Methanol is currently produced from natural gas, a non-renewable fossil fuel. In the future it is hoped to be produced from biomass as biomethanol. The methanol economy is an alternative to the hydrogen economy, compared to today's hydrogen production from natural gas. Butanol (C4H9OH) is formed by ABE fermentation (acetone, butanol, ethanol) and experimental modifications of the process show potentially high net energy gains with butanol as the only liquid product. Butanol will produce more energy and allegedly can be burned "straight" in existing gasoline engines (without modification to the engine or car),[7] and is less corrosive and less watersoluble than ethanol, and could be distributed via existing infrastructures. DuPont and BP are working together to help develop butanol. E. coli strains have also been successfully engineered to produce butanol by modifying their amino acid metabolism[8].

Ethanol is also used to fuel bioethanol fireplaces. As they do not require a chimney and are "flueless", bioethanol fires[4] are extremely useful for newly built homes and apartments without a flue. The downsides to these fireplaces is that their heat output is slightly less than electric heat or gas fires, and precautions must be taken to avoid carbon monoxide poisoning. Corn-to-ethanol and other food stocks has led to the development of cellulosic ethanol. According to a joint research agenda conducted through the US Department of Energy, the fossil energy ratios (FER) for cellulosic ethanol, corn ethanol, and gasoline are 10.3, 1.36 and 0.81, respectively[5]. 4.2 Ethanol Biodiesel is the most common biofuel in Europe. It is produced from oils or fats using transesterification and is a liquid similar in composition to fossil/mineral diesel. Chemically, it consists mostly of fatty acid methyl (or ethyl) esters (FAMEs). Feed stocks for biodiesel include animal-fats, vegetable oil,

4.4 Green diesel Green diesel is produced through hydrocracking biological oil feedstocks, such as vegetable oils and animal fats[9]. Hydrocracking is a refinery method 35

Anita Sharma

of smaller companies, such as Elsbett, offer engines that are compatible with straight vegetable oil, without the need for after-market modifications.

that uses elevated temperatures and pressure in the presence of a catalyst to break down larger molecules, such as those found in vegetable oils, into shorter hydrocarbon chains used in diesel engines[10]. It may also be called renewable diesel, hydrotreated vegetable oil[10] or hydrogen-derived renewable diesel [35] . Green diesel has the same chemical properties as petroleum-based diesel[36]. It does not require new engines, pipelines or infrastructure to distribute and use, but has not been produced at a cost that is competitive with petroleum[9]. Gasoline versions are also being developed[11]. Green diesel is being developed in Louisiana and Singapore by Conoco Phillips, Neste-Oil, Valero, Dynamic Fuels, and Honeywell UOP as well as Preem in Gothenburg, Sweden, creating what is known as Evolution Diesel.

Vegetable oil can also be used in many older diesel engines that do not use common rail or unit injection electronic diesel injection systems. Due to the design of the combustion chambers in indirect injection engines, these are the best engines for use with vegetable oil. This system allows the relatively larger oil molecules more time to burn. Some older engines, especially Mercedes, are driven experimentally by enthusiasts without any conversion, a handful of drivers have experienced limited success with earlier pre- "Pumpe Duse" VW TDI engines and other similar engines with direct injection. Several companies, such as Elsbett or Wolf, have developed professional conversion kits and successfully installed hundreds of them over the last decades.

4.5 Bio-fuel gasoline In 2013 UK researchers developed a genetically modified strain of Escherichia coli (E.Coli), which could transform glucose into biofuel gasoline that does not need to be blended[12]. Later in 2013 UCLA researchers engineered a new metabolic pathway to bypass glycolysis and increase the rate of conversion of sugars into biofuel, while KAIST researchers developed a strain capable of producing short-chain alkanes, free fatty acids, fatty esters and fatty alcohols through the fatty acyl (acyl carrier protein (ACP)) to fatty acid to fatty acyl-CoA pathway in vivo. It is believed that in the future it will be possible to "tweak" the genes to make gasoline from straw or animal manure.

Oils and fats can be hydrogenated to give a diesel substitute. The resulting product is a straight-chain hydrocarbon with a high cetane number, low in aromatics and sulfur and does not contain oxygen. Hydrogenated oils can be blended with diesel in all proportions. They have several advantages over biodiesel, including good performance at low temperatures, no storage stability problems and no susceptibility to microbial attack. 4.7 Bioethers Bioethers (also referred to as fuel ethers or oxygenated fuels) are cost-effective compounds that act as octane rating enhancers. "Bioethers are produced by the reaction of reactive iso-olefins, such as iso-butylene, with bioethanol" . Bioethers are created by wheat or sugar beet. They also enhance engine performance, whilst significantly reducing engine wear and toxic exhaust emissions. Though bioethers are likely to replace petroethers in the UK, it is highly unlikely they will become a fuel in and of itself due to the low energy density[14] . Greatly reducing the amount of ground-level ozone emissions, they contribute to air quality.

4.6 Vegetable oil Straight unmodified edible vegetable oil is generally not used as fuel, but lower-quality oil has been used for this purpose. Used vegetable oil is increasingly being processed into biodiesel, or (more rarely) cleaned of water and particulates and then used as a fuel. As with 100% biodiesel (B100), to ensure the fuel injectors atomize the vegetable oil in the correct pattern for efficient combustion, vegetable oil fuel must be heated to reduce its viscosity to that of diesel, either by electric coils or heat exchangers. This is easier in warm or temperate climates. MAN B&W Diesel, Wärtsilä, and Deutz AG, as well as a number

When it comes to transportation fuel there are six ether additives: dimethyl ether (DME), diethyl ether (DEE), methyl teritiary-butyl ether (MTBE), ethylter-butyl ether (ETBE), ter-amyl methyl ether

36

Production of Biofuels in India

(TAME), and ter-amyl ethyl ether (TAEE)[15].

substitute, or a mixture of alcohols that can be blended into gasoline. Gasification normally relies on temperatures greater than 700 °C. Lower-temperature gasification is desirable when co-producing biochar, but results in syngas polluted with tar.

The European Fuel Oxygenates Association (EFOA) credits methyl Ttertiary-butyl ether (MTBE) and ethyl ter-butyl ether (ETBE) as the most commonly used ethers in fuel to replace lead. Ethers were introduced in Europe in the 1970s to replace the highly toxic compound[16]. Although Europeans still use bio-ether additives, the US no longer has an oxygenate requirement therefore bio-ethers are no longer used as the main fuel additive.

4.10 Solid biomass fuels Examples include wood, sawdust, grass trimming domestic refuse, charcoal, agricultural waste, nonfood energy crops, and dried manure. When solid biomass is already in a suitable form (such as firewood), it can burn directly in a stove or furnace to provide heat or raise steam. When solid biomass is in an inconvenient form (such as sawdust, wood chips, grass, urban waste wood, agricultural residues), the typical process is to densify the biomass. This process includes grinding the raw biomass to an appropriate particulate size (known as hogfuel), which, depending on the densification type, can be from 1 to 3 cm (0.4 to 1.2 in), which is then concentrated into a fuel product. The current processes produce wood pellets, cubes, or pucks. The pellet process is most common in Europe, and is typically a pure wood product. The other types of densification are larger in size compared to a pellet and are compatible with a broad range of input feedstocks. The resulting densified fuel is easier to transport and feed into thermal generation systems, such as boilers.

4.8 Biogas Biogas is methane produced by the process of anaerobic digestion of organic material by anaerobes. It can be produced either from biodegradable waste materials or by the use of energy crops fed into anaerobic digesters to supplement gas yields. The solid byproduct, digestate, can be used as a biofuel or a fertilizer. Biogas can be recovered from mechanical biological treatment waste processing systems. Landfill gas, a less clean form of biogas, is produced in landfills through naturally occurring anaerobic digestion. If it escapes into the atmosphere, it is a potential greenhouse gas. Farmers can produce biogas from manure from their cattle by using anaerobic digesters[17]. 4.9 Syngas

5.

Syngas, a mixture of carbon monoxide, hydrogen and other hydrocarbons, is produced by partial combustion of biomass, that is, combustion with an amount of oxygen that is not sufficient to convert the biomass completely to carbon dioxide and water.[45] Before partial combustion, the biomass is dried, and sometimes pyrolysed. The resulting gas mixture, syngas, is more efficient than direct combustion of the original biofuel; more of the energy contained in the fuel is extracted.

Conclusion

Biofuels are derived from renewable bio-mass resources and, therefore, provide a strategic advantage to promote sustainable development and to supplement conventional energy sources in meeting the rapidly increasing requirements for transportation fuels associated with high economic growth, as well as in meeting the energy needs of India's vast rural population. Biofuels can increasingly satisfy these energy needs in an environmentally benign and cost effective manner while reducing dependence on import of fossil fuels and thereby providing a higher degree of National Energy Security.

Syngas may be burned directly in internal combustion engines, turbines or high-temperature fuel cells. The wood gas generator, a wood-fueled gasification reactor, can be connected to an internal combustion engine. Syngas can be used to produce methanol, DME and hydrogen, or converted via the Fischer-Tropsch process to produce a diesel

References [1]

37

"What is biofuel? definition and meaning". BusinessDictionary.com. Retrieved 30 May 2015.

Anita Sharma

[2]

Krishnan G.S., Can second generation ethanol fuel India's growth? Opnion on Chemical Industries. Business Standard (2013).

[3]

Briggs, Michael, "Widescale Biodiesel Production from Algae". UNH Biodiesel Group (University of New Hampshire). Archived from the original on 24 March 2006. Retrieved 2007-01-02, (August 2004).

[4]

Bio ethanol fires information bio ethanol fireplace. (2009)

[5]

Farrell A.E., et al. "Ethanol can Contribute to Energy and Environmental Goals". Science. 311: 506-8. doi:10.1126/science.1121416. PMID 16439656. (2006).

[6]

"Biofuels Facts". Hempcar.org. Retrieved 201007-14.

[7]

"ButylFuel, LLC Main Page". Butanol.com. 2005-08-15. Retrieved 2010-07-14.

[8]

Evans Jon, "Biofuels aim higher". Biofuels, Bioproducts and Biorefining (BioFPR). Retrieved 2008-12-03. (14 January 2008).

[9]

diesel: A comparison". Progress in Energy and Combustion Science (2010). [11] Jessica Ebert, "Breakthroughs in Green Gasoline Production". Biomass Magazine. Retrieved 14 August 2012. [12] Summers Rebecca, Bacteria churn out first ever petrol-like biofuel New Scientist, Retrieved 27 April 2013. (24 April 2013). [13] Choi Y.J. and Lee S.Y., "Microbial production of short-chain alkanes". Nature. 502: 571-4. doi:10.1038/nature12536. PMID 24077097. (2013). [14] "Biofuels - Types of Biofuels - Bioethers". Retrieved 30 May 2015. [15] Sukla, Mirtunjay Kumar, Thallada Bhaskar; Jain A.K., Singal S.K. and Garg M.O., "BioEthers as Transportation Fuel: A Review" (PDF). Indian Institute of Petroleum Dehradun. Retrieved 15 February 2014. [16] "What are Bio-Ethers?" (PDF). . The European Fuel Oxygenates Association. Archived from the original (PDF) on 2014-03-06.

"Alternative & Advanced Fuels". US Department of Energy. Retrieved 7 March2012.

[17] "BIOGAS: No bull, manure can power your farm." Farmers Guardian (25 September 2009): 12. General OneFile. Gale.

[10] Knothe Gerhard, "Biodiesel and renewable

38

DOI No. : 10.5958/2454-7611.2018.00007.3 Growth, structural and opticalEnergy, properties zirconium chloride (TTZrC) Invertis Journal of Renewable Vol. of 8, new No. semi-organic 1, 2018 ; pp.crystal 39-45of tris-thiourea

Growth, structural and optical properties of new semi-organic crystal of tris-thiourea zirconium chloride (TTZrC) M. MANIMEGALAI1,4, F.A.SELVIN2, P.N. SELVAKUMAR3, J. ANNARAJ4* and S. CHANDRASEKARAN5 1 Department of Chemistry, NMSSVN College, Madurai, Tamil Nadu, India - 625019 2 Department of Physics, NMSSVN College, Madurai, Tamil Nadu, India - 625019 3 Department of Physics, V.V. College of Engineering, V.V. Nagar, Arasur, Tamil Nadu, India - 628565 4 Department of Materials Science, School of Chemistry, Madurai Kamaraj University, Madurai, Tamil Nadu, India - 625019 5 Department of Chemical and Bioengineering, University of Ulsan, Ulsan, South Korea - 680 749 *E-mail: [email protected] Abstract A novel semi-organic crystal of Tris Thiourea Zirconium Chloride (TTZrC) semi-organic material has been synthesized and reported for the first time. Grown crystal was characterized by XRD, FTIR,UV-Vis, PL and FE-SEM analyses. The grown semi-organic crystal could potentially be useful for various opto-electronic device applications. Key words : Tris Thiourea Zirconium Chloride, Semi-oranic crystals, XRD, optical studies, thiourea

1.

Introduction

[SC(NH 2 ) 2 ] have been used with significant performances. Among these organic materials, thiourea has a long history as a ligand in coordination chemistry being able to coordinate with metals via either sulphur(S) or nitrogen (N) donors (see Scheme 1). Also it is are markable inorganic matrix modifier due to its large dipole moment and ability to form extensive network of hydrogen bonds which is widely studied[9]. Non-centrosymmetry is the main requirement for obtaining optical frequency doubling, optical sum and difference frequency generation, optical parameters amplification[1]. Thiourea is a centro symmetric molecule, while it becomes noncentrosymmetric behavior among metal coordination, resulting in forming stable semi-organic compounds with good physio chemical behavior. Previously, some well-known organo metallic crystals were grown using thiourea are ZTS, ZTC and BTCC[10-12]. Semi-organic materials doped transition metals and rare-earth ions have been investigated intensively in the viewpoint of various

Recently, there has been a significant interest to design and construction of semi-organic materials with superior nonlinear optical and fluorescence properties due to their potential applications such as, telecommunication, integrated optics, light emitting diodes, and optical information processing[1], which possess high threshold and wide transparency range[2]. Semi-organic materials are expected to have large and relatively strong nonlinear optical properties. It explains the extensive search for better optical materials among semi-organic materials, which share the properties of both organic and inorganic material[3]. The existing strong ligand bond in semi-organic materials permits the combine advantages of organic and inorganic complex crystals, such as good stability, high nonlinear and molecule engineering features[4-7]. Generally, the organic ligands of small π electron systems such as thiocyanate (SCN)-, urea [OC (NH2)2] and thiourea 39

M. Manimegalai, F.A.Selvin, P.N. Selvakumar, J. Annaraj and S. Chandrasekaran

Scheme 1 (i) Resonance structure of thiourea and (ii) Reaction mechanism of thiourea bonding with metal ions (inspired from Ref (****))

attained using Perkin Elmer Lambda 35 and VARIAN Cary Eclipse Fluorescence Spectrophotometer employing 150 Watts Xe arc discharge lamp as the excitation source. Finally the surface morphologies of the prepared materials were analyzed using Field Emission-Scanning Electron Microscope.

optical device applications[13]. Herein, we report the growth of novelsemi-organic crystal using a transition metal chlorideion (ZrCl 2) doped with thiourea by slow-evaporation method and they were characterized by powder XRD, FTIR, UV-Vis, PL and FESEM analyses. The reported and discussed results could potentially be useful for various photonic applications. 2.

4.

Grown crystal of TTZrC have been uniformly crushed using agatemortarto make fine powder and subjected to powder X-ray diffraction studies using a Rich Seifert powder X-ray diffractometer with a scan rate (2θ) of 10-80°, where the source of CuKα radiation (λ=1.5406A) target were used. Grown TTZrC material exists in the polycrystalline nature as illustrated in their XRD pattern (Fig. 1). The observed d-spacings of Zr doped thiourea samples match strongly with the standard pattern of thiourea (JCPDS No. 01-083-2252) which crystallizes in the orthorhombic crystal system.

Materials and Methods

Pure salts of Zirconium (IV) chloride and thiourea were purchased from Sigma Aldrich. Tristhiourea Zirconium chloride was synthesized by the mixing of aqueous methanolic solutions (1:1) of Zirconium chloride (23 mg) and thiourea (69 mg) and in the stoichio metric ratio of 1:3 at constant stirring for 5 hours. The synthesized salt was purified by repeated recrystallization for three times. 3.


Experimental Characterizations

The crystal structure was identified by powder X-ray diffraction (XRD) analysis (Richseifert diffractometer). The functional groups present in the prepared semi-organic material were clearly identified by FT-IR analysis (Perkin Elmer spectrum BX model at a resolution 2 cm –1 ). The optical absorption spectra and luminescence spectra were

The functional groups present in the grown crystals were clearly identified by FTIR spectroscopic analysis. The infrared spectral analysis has been carried out to understand the chemical bonding and it provides useful information regarding the molecular structure of the compound. As illustrated 40

Growth, structural and optical properties of new semi-organic crystal of tris-thiourea zirconium chloride (TTZrC)

Fig. 1. X-ray powder diffraction pattern of TTZrC crystal.

peak at 1685 cm–1 is attributed to NH2 bending mode. The (CN) symmetric stretching mode is detected at 1088 cm–1. The characteristic bands of thiourea at 1485 and 728cm–1 are due to asymmetric and symmetric υ(C=S) stretching vibrations. It is well-known that

in Fig. 2 and Table 1, broad peak located in between 2687 cm–1- 3553 cm–1 corresponds to symmetric and asymmetric stretching modes of NH2 grouping of zirconium coordinated thiourea. The (NCN), NH3+ stretching vibration was observed at 2032 cm–1. The

Fig. 2. FT-IR spectrum of TTZrC crystal.

41

M. Manimegalai, F.A.Selvin, P.N. Selvakumar, J. Annaraj and S. Chandrasekaran

Table 1. Assignment of IR absorption bands for the TTZrC crystal from the FTIR spectrum Frequency in cm–1 473 601 615 690 712 728 745 1088 1122 1286 1395 1417 1485 1504 1618 1685 1727 1849 2032 2687 3553

Assignments Assymmertric S-Zr-S Stretching and C-N deformation N-C-N bending S-O stretching C=S symmetric stretching C=S symmetric stretching C=S symmetric stretching C=S stretching (CN) symmetric stretching N-C-N stretching weak C=S stretching C=S asymmetric stretching C=S asymmetric stretching N-C-N asymmetric stretching N-C-N stretching Metal complex and NH2stretching NH2 bending N-H stretching N-H stretching N-C-N stretching; NH3+ stretching NH2 stretching NH2 stretching

thiourea exhibits asymmetric and symmetric υ(NH2) stretching vibrations in the high frequency region of 3400-3000 cm –1 those were not shifted to lower frequencies upon its complexation with metal, indicating that the thiourea did not undergo complexation with metal through nitrogen atom, while it occurred via sulphur atoms[14]. The increase in the frequency can be attributed to the greater double bond character of the carbon to nitrogen bond on complex formation[15]. The presence of metalsulphur bonds present in the compound is also evident from the peaks at 479-473 cm –1 due to asymmetric S-Metal-S stretching as well as C-N deformation[16]. In addition, synthesized compounds showed weak C=S stretching vibrations in the 12511296 cm–1 range[17]. The N-H stretching vibration, present in the ligand around 3200 cm–1 disappears in the complex spectra. These results are comparable with the previously available reports[18].

TTZrC crystal, where the excitation wavelength is about ~ 380 nm. Usually the luminescence spectra provides the crucial information regarding the intrinsic/extrinsic impurities and recombination of electronic transitions associated with the material which is essential quality of a material to be utilized in photonics and biomedical applications[19]. Three strong and five weak PL peaks are observed for TTZrC (Fig. 3). The peaks observed at 408 and 420 nm are mainly due to the S2- vacancies. The peak observed in the blue green emission at 487 nm and green emission about at 518 nm is attributed to the native point defects in the prepared samples. It was reported that, the PL intensity is highly dependent on the crystalline and structural perfection of the grown crystals. A very strong blue-green PL band can be observed which is ranging from 408 nm to 555 nm. Emission from "Zr" ion is according to dipole transition of 4f-5d which has a permitted purity and spin with a fairly strong vibration force[22-24].

Fig. 3 showed the emission spectrum of the grown 42

Growth, structural and optical properties of new semi-organic crystal of tris-thiourea zirconium chloride (TTZrC)

Fig. 3. Photoluminescence spectrum of TTZrC Crystal.

(αhυ)2 vs photon energy extrapolated to x-axis at y=0 gives the energy band gap value. The calculated band gap values of TTZrC is about ~2.9743eV. It should be noted that, a good band gap and optical transmittance is very desirable for any crystal to find applications in photonics and optoelectronics. Transmission spectral analysis important and favor for any

The UV-Vis spectrum of TTZrC crystal revealed the transparent wavelength region in the visible region and it is represented in Fig 4a. The absorbance of TTZr Ccrystal showed higher absorbance in the UV region