International Journal of Bioengineering & Biotechnology 2016; 1(1): 1-5 http://www.openscienceonline.com/journal/ijbb
Determination of Optimum Moisture Content of Neem Seed for Biodiesel Production Abbah E. C.*, Asoegwu S. N., Nwandikom G. I. Department of Agricultural and Bioresources Engineering, Federal University of Technology Owerri, Imo State, Nigeria
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To cite this article Abbah E. C., Asoegwu S. N., Nwandikom G. I. Determination of Optimum Moisture Content of Neem Seed for Biodiesel Production. International Journal of Bioengineering & Biotechnology. Vol. 1, No. 1, 2016, pp. 1-5. Received: April 4, 2016; Accepted: April 21, 2016; Published: May 18, 2016
Abstract This research work was on the determination of optimum moisture content of neem seed for biodiesel production. This study therefore, is intended to consider the production of biodiesel from neem seed in terms of quantity and optimum moisture content that gives the maximum yield of biodiesel by transesterification. The main materials used in this research are neem seeds and it was gotten from Federal University of Technology (FUTO) and Ihiagwa environment. The study result shows that presence of moisture in neem seeds can be an impediment to production of biodiesel just as free fatty acid (FFA).Thus in most conventional biodiesel production processes, refined raw materials are used otherwise the reaction could either seize to occur or result in low biodiesel yield and quality. The neem seeds used were first sun dried and finally oven dried to various moisture contents of 14.1, 12.3, 10.5, 8.2, and 6.8%wb respectively. The dried seeds which measured 10kg per sample were ground using attrition mill and the oil was extracted using solvent extraction (Soxhlet extraction method, nhexane) process. During the transesterification process, the non-edible neem seed oil was used as the feedstock with potassium hydroxide (KOH) and methanol as catalyst and alcohol respectively. The free fatty acid content of the refined oil was 8.42mg/KOH which corresponds to free fatty acid (FFA) value of 4.20%. The FFA was further reduced to less than 1% by two step acid esterification processes. From the results, various yields of both neem oil and biodiesel were obtained and it was found that the treatment at moisture content of 8.2%wb gave the highest yield of neem oil and neem biodiesel of 4.5 and 86.2% respectively. The regression models of the yield of both oil and biodiesel against moisture content gave R2 values of 0.951 and 0.956 respectively.
Keywords Neem Seed, Moisture Content, Neem Biodiesel, Neem Oil, Transesterification
1. Background of Study Biodiesel is defined by ASTM International as a fuel composed of monoalkyl esters of long-chain fatty acids derived from renewable vegetable oils or animal fats meeting the requirements of ASTM D6751 [1]. It could be used in conventional compression ignition engines as heating oil [2], [3]. It is a clean burning alternative fuel, produced from domestically grown renewable resources such as vegetable oils, edible and non-edible oils; it contains no petroleum products, but can be blended at any concentration with diesel from fossil sources to create a biodiesel blend, [4]. Biodiesel
is now recognized as an alternative fuel because it has several advantages over conventional diesel including being environmentally friendly, renewable and non-toxic [5]. Methods commonly used for producing biodiesel involve various stages including oil extraction, purification (degumming, deacidification, dewaxing, dephosphorization, dehydration, etc.) and esterification and/or transesterification process. These stages consume over 70% of the total production cost of biodiesel [6] due to presence of water and free fatty acids. Conventionally, alkali catalyst, such as sodium and potassium hydroxides, are the most preferred catalysts in biodiesel production [7]. In the conventional transesterification of fats and vegetable
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Abbah E. C. et al.: Determination of Optimum Moisture Content of Neem Seed for Biodiesel Production
oils to biodiesel, presence of free fatty acids and moisture content always bring about negative effects due to soap formation, excess catalyst consumption, and low production of the biodiesel. Therefore, feeds tocks for biodiesel production should be free from water [8]. A small amount of moisture (0.1%) in the transesterification reaction would decrease the ester conversion from vegetable oil [9]. Anya et al., [10] reported that the yield of the alkyl ester decreases due to presence of moisture and free fatty acid as they cause soap formation, consume catalyst and reduce the effectiveness of the catalyst. Moisture content from the vegetable oil is removed by heating in oven for 1hour at 383K [11]. Meher et al., [12] reported a precautionary step to prevent moisture absorbance and maintenance of catalytic activity bypreparing the mixture of potassium hydroxide and methanol. It is found that even a smallamount of moisture in the feedstock during esterification reaction and presence of FFA mightcause reduction in conversion of fatty acid methyl ester and formation of soap [13]. Ma and Hanna, [14] stated that even refined oils and fats contain small amounts of FFAs and moisture. Presence of water speeds up hydrolysis of triglycerides and increases FFAs content in vegetable oils [15]. Therefore, it is essential to minimize the moisture content in feedstocks prior to Transesterification process so
as to ensure maximum biodiesel yield. Many researchers have worked on various aspects of production of biodiesel from neem seed but none have looked into determining the specified quantity of neem seed at particular moisture content that gives optimum yield of biodiesel. This study therefore, is intended to consider the production of biodiesel from neem seed in terms of quantity and optimum moisture content that gives the maximum yield of biodiesel by transesterification.
2. Materials and Methods 2.1. Materials The main materials used in this research are neem seeds and it was gotten from Federal University of Technology (FUTO) and Ihiagwa environment. The quantity of seeds collected measured 95kg before being processed to produce biodiesel. 2.2. Methods The various stages of neem seed preparation for oil extraction starting from harvesting of the fresh neem seed, depulping and drying of the seeds are shown in Figure 1.
Neem seed Neem kernelDried neem seed Figure 1. Various stages of neem seed preparation before oil extraction.
The cleaned seed kernels still within their endocarp were sun dried in the open at 50° for three days to allow for their easy removal after soaking for 5mins and washing removing the endocarp. The seed was weighed, divided into five portions each and further oven-dried to various moisture contents of 14.1, 12.3, 10.5, 8.2 and 6.8%wb respectively, which was initially at 18%wb. The moisture content of the neem seed was confirmed using a moisture meter. Each of the samples was further divided into five portions for replication. The moisture content was determined from the various separated samples of the neem seed noting the initial and final weight [1], after which the percentage moisture was calculated using equation 1. % Moisture content =
х 100
(1)
The weight of the seed samples was separated based on various moisture contents, (W1) was measured, constant weight (W2) was obtained. The dried seeds were grinded
using attrition mill in order to reduce the particle size as well as increase the surface area which in turn increases the oil yield after which 10kg of each treatment was measured out for oil extraction. Soxhlet extraction method (nhexane) was used during the extraction of neem oil, [16]. The quantity of the extracted crude neem oil was recorded at the end of the extraction process and the percentage extracted oil was determined using equation 2. %
!
"
#
$ 100
(2)
The percentage moisture content of the extracted oil was calculated using the formula in equation 3. % % &'() * +' +'
,- ,. ,/ ,.
Where: W1 = weight of empty Petridish W2 = weight of Petridish + weight of oil
$ 100
(3)
International Journal of Bioengineering & Biotechnology 2016; 1(1): 1-5
W3 = weight of Petridish + final weight of oil The refined neem oil sample of 10g was weighed and transferred into an already weighed dry Petri dish that was placed in an oven; it was allowed to dry at 100°C for 1 hour. The sample was cooled in desiccators and weighed again. The process was repeated every 1 hour until a constant weight was obtained and equation 3 above was used to determine the moisture content. A two step process acid catalyzed esterification followed by alkali catalyzed Transesterification was employed before base catalyzed Transesterification [17]. The alcohol used was methanol and potassium hydroxide (KOH) as catalyst in the ratio of 6:1, 7:1 and 8:1 respectively. After the Transesterification the upper ester layer contained traces of KOH, methanol and glycerol and the biodiesel was washed
3
by spraying hot water over it to remove unreacted methanol and residual catalysts which may corrode engine components[18].
3. Results and Discussion Table 1 shows yield of neem oil and biodiesel based on different moisture contents. The first column is the treated neem seed at different moisture contents, the second column is the measured quantities of ground neem treatments, third column represents the quantity of extracted neem oil, the fourth column is quantity of biodiesel gotten by trans esterification of extracted neem oil based on various moisture content levels, the fifth and sixth column shows the percentage yield of neem oil and neem biodiesel.
Table 1. Yield of neem oil and neem biodiesel based on different moisture content. Treatments (moisture contents (%)
Quantity of grinded neem seeds (kg)
Quantity of Neem oil extracted (kg)
Quantity of neem biodiesel (kg)
Neem oil yield (%)
Neem biodiesel yield (%)
14.1
10
0.11
0.05
1.1
45.0
12.3
10
0.18
0.11
1.8
61.1
10.5
10
0.20
0.12
2.0
60.0
8.2
10
0.29
0.25
2.9
86.2
6.8
10
0.19
0.13
1.9
68.4
From the tableit shows that the treatment of moisture content of 8.2% gave the highest yield of neem biodiesel of 86.2%. It also gave the highest quantity of extracted oil, neem biodiesel and neem oil yield of 0.29, 0.25kg and 1.9% respectively. Meher et al., [12] reported that the oil content in Castor bean, Hemp and Pongame seed is around 50, 35 and 30-40% respectively while that of Neem seed contains 30% oil content. However, the oil content of neem seed obtained in this study is lower and even when compared to Kartika et al., [19] which reported oil content of 38% from jatropha curcas seed oil. According to Ketaren [20], the differences in physical and chemical properties are influenced by the type of seed plants, environmental and climatic conditions where the plants grow. Therefore, environmental and climatic factors must have affected the physical and chemical properties of the neem seeds.
Figure 3. Graph of neem biodiesel yield vs moisture content.
From the graphs it can be deduced that the treatment of moisture content of 8.2% assumed the peak value of 86.2% for neem oil yield while the treatment of moisture content of 6.8% assumed the lowest value of 68.4%. The regression equations of graphs (Figures 2 and 3) of yield of neem oil and neem biodiesel against moisture content are given in equations 4 and 5. 0.558 $3 4 18.36 $7 8 193.3 $ 4573.0 ;< 7 0.111 $3 4 3.784 $7 8 41.31 $ 451.63 ;< 7
Figure 2. Graph of neem oil yield vs moisture content.
0.951= (4) 0.956= (5)
Where y represents the neem oil and biodiesel yields and $ represents the moisture content at different levels. It can be observed from both graphs that above 10% moisture content, neem oil and neem biodiesel yield were found to be less. This was due to presence of high value of
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Abbah E. C. et al.: Determination of Optimum Moisture Content of Neem Seed for Biodiesel Production
moisture and free fatty acid (FFA) as reported by [21]. The Authors reported that high moisture content in the seeds will affect the amount of free fatty acids as well as esterification and Transesterification process. High water levels can cause hydrolysis and fatty acids in biodiesel is converted into free fatty acids thereby increasing the acid number that can corrode engine parts and injection system. The yield of biodiesel produced ranged between 45% 86.2% with an average of 64.12%. Figure 3 shows that treatment with 8.2% moisture content of neem seeds produces a higher yield of 86.2% biodiesel compared to treatment of other neem seeds. Quantitatively, the lower the moisture content of neem seedsused as feedstock, the higher the yield of biodiesel obtained. This is presumably due to the lower water content in the treatment sample (8.2%) and chance of Saponification reaction is got smaller as the process of conversion of oil into biodiesel was unabated. Fukuda [22] and Sudradjat et al., [23] reported that the presence of excessive water can cause some reaction turned into a saponification reaction that will produce soap, the soap will react with the base catalyst and reduce catalyst efficiencythereby increasing the viscosity, gel formation and complicate the separation of the methylesters of glycerol. Furthermore, Kusdiana and Saka [8] also stated that even refined oils and fats contain small amounts of FFAs and water. Presence of water speeds up hydrolysis of triglycerides and increases FFAs content in vegetable oils [15]. The result was similar to that of Vicente et al., [24], who stated that the use of refined sunflower oil containing less amount of water, after separation and purification stages, biodiesel yield was higher than 98wt. % and that was because of the fact that the yield loss due to soap formation and methyl ester dissolution in glycerol were negligible. More so, the result is related to that of Van Gerpen [25] who observed that refined feedstock such as neem seed could provide methyl ester yield ranging from 93% to 98% compared to crude raw materials providing methyl esters yield ranging from 67% to 86% and to that of Antczak et al., [26], in which the yield of biodiesel from refined vegetable oils was reported to be close to 99%.
4. Conclusion In this research, biodiesel was produced from neem seed at different moisture content levels ranging from 14.1, 12.3, 10.5, 8.2 and 6.8% respectively. The optimum yield of neem oil and neem biodiesel was obtained at the treatment of 8.2%. The result shows that presence of moisture in neem seeds can be an impediment to production of biodiesel just as free fatty acid (FFA). Many researchers have proved that biodiesel production is faced with problems especially when low quality raw materials containing higher amount of moisture and free fatty acids (FFAs) contents are used. Thus in most conventional biodiesel production processes, refined raw materials are used otherwise the reaction could either seize to occur or result in low biodiesel yield and quality.
References [1]
ASTM (2008). Standard specification for biodiesel fuel (B100) blend stock for distillate fuels. In: Annual Book of ASTM Standards, ASTM International, West Conshohocken, Method D6751-08; alcoholysis for biodiesel fuel production and application of the reaction to oil processing. J Mol Catal B: Enzym. 76: 133-142.
[2]
Anindita Karmakar; Subrata Karmakar; Souti Mukherjee (2012). “Biodiesel production from neem towards feedstock diversification: Indian perspective” Renewable and Sustainable Energy Reviews 16: 1050 1060D1.
[3]
Wardle, D. A. (2003). Global Sale of Green Air Travel Supported Using Biodiesel. Renewable and Sustainable Energy Reviews, 7 (1): (February 2003), 1-64.
[4]
Chisti, Y., (2008). Biodiesel from microalgae beats bioethanol. Trends in Biotechnology, 26: 126-131.
[5]
Aworanti O. A, Agarry S. E. and Ajani A. O. (2013). Statistical Optimization of Process variables for biodiesel production from waste cooking oil using heterogeneous base catalyst. British Biotechnology Journal. 3(2): 116-132.
[6]
Zeng J., Wang X., Zhao B., Sun I., and Wang Y. (2009). Rapid In Situ Transesterification of Sunflower Oil. Industrial Engineering Chemical Resources, 48 (2): 850-856.
[7]
Ofor M. O., and Nwufo M. I. (2011). The search for alternative energy sources: Jatropha and moringa seeds for biofuel production. Journal of Agriculture and Social Research (JASR). 11(2): 87-94.
[8]
Kiakalaieh, A. T, Amin, N. A. S., Zarei, A, Noshadi, A, (2013). Transesterification of waste cooking oil by heteropoly acid (HPA) catalyst: Optimization and kinetic model, Applied Energy, 102: 283-292.
[9]
Solanki R. C; Naik S. N; Srivastava A. P. and Santosh S. (2011). Physical and mechanical properties of neem fruit and seedrelevant to depulping and decortication. J. Agric. Eng., 48(3): 52-57.
[10] Anya, Uzo Any; Nwobia, Noelle Chioma and Ofoegbu, Obinna (2012). “Optimized reduction of free fatty acid content on neem seed oil, for biodiesel production” Journal of Basic and Applied Chemistry, 2(4): 21-28. [11] Srivastava P. K, Verma M. (2007). Triglycerides –Based Diesel fuels”, Renewable and Sustainable Energy Reviews. 111-133. [12] Meher, L. C., Sagar, D. V. and Naik, S. N. (2006). Technical aspects of biodiesel production by transesterification—a review, Renewable and Sustainable Energy Reviews 10: 248– 268. [13] Karmakar, A.; Karmakar, S.; Mukherjee, S. (2011). Biodiesel production from neem towards feedstock diversification: Indian perspective. Renewable Sustain. Energy Rev., 16 (1): 1050-1060. [14] Ma F. and Hanna M. A. (1999). Biodiesel production: a review. Bioresources Technology; 70: 1–15. [15] Ragit, S. S, Mohapatra, S. K, Kundu, K, Gill, P (2011). Optimization of neem methyl ester from transesterification process and fuel characterization as a diesel substitute. Biomass Bioenergy, 35 (3): 1138-1144.
International Journal of Bioengineering & Biotechnology 2016; 1(1): 1-5
5
[16] AOAC (Association of Official Analytical Chemist), (1990). Official Methods of Analysis (15th edn), AOAC; Washington DC.
neem oil using two step transesterification. International Journal of Engineering Research and Application. 2(3): 488492.
[17] Aransiola, E. F, Ojumu, T. V, Oyekola, O. O and Ikhuomoregbe, D. I. O. (2012). A Study of Biodiesel Production from Non-Edible Oil Seeds: A Comparative Study. The Open Conference Proceedings Journal, (Suppl 2-M1) 1-5.
[22] Fukuda, H. 2001. Biodiesel Fuel Production by Transesterification of Oils. Journal of Bioscience and Bioengineering. 92 (5); 405-416.
[18] Hanumanth, Mulimani, Hebbal, O. D, and Navindgi, M. C, 2012. Extraction of Biodiesel from Vegetable Oils and Their Comparisons International Journal of Advanced Scientific Research and Technology 2 (2). [19] Kartika, A., S. Yuliani., Danu, A., dan Sugiarto. (2009). Rekayasa Proses Produksi Biodiesel Berbasis Jarak Pagar (Jatropha curcas) melalui Transesterifikasi In Situ. Prosiding Seminar Hasil, IPB. 131-138. [20] Ketaren, S. (1986). Pengantar Teknologi Minyak dan Lemak Pangan. UI Press, Jakarta. [21] Sathya, T, Manivannan, A, (2013). Biodiesel production from
[23] Sudradjat, R., I. Jaya, dan Setiawan. D. (2005). Process Optimization Estrans on Biodiesel fromJatropha oil. Journal of Forest Research. Forest Products Research and Development Centre, Bogor. 23 (4): 239-257. [24] Vicente G, Martınez M, Aracil J. (2004). Integrated biodiesel production: a comparison of different homogeneous catalysts systems. Bioresources Technology. 92: 297–305. [25] Van Gerpen J. (2005). Biodiesel processing and production. Fuel Proc Technol; 86: 1097–107. [26] Antczak MS, Kubiak A, Antczak T, Bielecki S. (2009). Enzymatic biodiesel synthesis—key factors affecting efficiency of the process: review. Rev Enferm; 34: 1185–1194.
