Thermal Degradation of PVC & Mixed Waste Plastics

Sarker M et al. /Journal of Applied Chemical Science 2012, Vol. 1 issue 2: 9 -17 ISSN: 2089-6328 Research Article

Available online at www.jacsonline.org

Thermal Degradation of PVC & Mixed Waste Plastics to Produce Mixture of Hydrocarbon Fuel Moinuddin Sarker*, Mohammad Mamunor Rashid, Muhammad Sadikur Rahman and Mohammed Molla Department of Research and Development, Natural State Research, Inc. 37 Brown House Road (2nd Fl), Stamford, CT 06902, USA Received on: 30-01-12;

Revised on: 18-02-12;

Accepted on: 23-02-12

Abstract Experiments of combination waste plastics such as High Density Polyethylene (HDPE), Low Density Polyethylene (LDPE), Polypropylene (PP) and Polyvinyl Chloride (PVC) were carried out in a steel reactor. The thermal cracking process was carried out in temperature range of 150 ºC to 400 ºC. The principle process products are gaseous and liquid hydrocarbon fractions similar to refinery cracking products. The solid carbon residue of around 8 to 9 % of the total raw materials are similar to coal cokes and contains higher mineral contents than the other two products. Upon further analysis using gas chromatography and Mass spectrometer (GC/MS) and furrier transform infrared spectroscopy (FT-IR) of the liquid hydrocarbon fraction showed similar chemical properties to commercial gasoline and diesel products. The similarity was in the distribution of carbon chains and alkane groups. Analysis using differential scanning calorimeter (DSC) showed the calorific value is comparable as well. The thermal degradation process was shown to be efficient because it was able to convert PVC, which contains 56% chlorine to hydrocarbon products. Specific analysis was done for the identification of chlorine in the liquid hydrocarbon products, and results have shown that the liquid hydrocarbon products contained lower chlorine content than standard chlorine level allowed by EPA. Further research is being conducted on capturing and categorizing the gaseous component and the results will be submitted on the subsequent scientific papers. Keywords: waste plastic, PVC, hydrocarbon, fuel, thermal degradation, LDPE, HDPE, PP Corresponding author*: *E-mail: [email protected];

1. Introduction The growing amount of plastic waste is generating more and more environmental problems worldwide. The present rate of economic growth is unimaginable without saving of fossil energy like crude oil, natural gas or coal. Suitable waste management is another important aspect of sustainable development. Plastic wastes represent a considerable part of municipal wastes; furthermore huge amounts of plastic waste arise as a by-product or faulty product in industry and agriculture. According to estimates, plastic wastes represent 15-25% of municipal waste. The amount of plastic materials was 25 million tons in

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Europe and it reached 35 million tons by 2010 [Aguado J et al. 1999 and Sartorius I et al. 2002]. Nowadays there are three ways to utilize plastic waste; land filling, incineration with or without energy recovery and recycling. The largest amount of plastic wastes is disposed of by land filling (65-70%), and incineration (20-25%). Recycling is only about 10%. Moreover, the problem of wastes cannot be solved by land filling and incineration, because suitable and safe depots are expensive, and incineration stimulates the growing emission of harmful, greenhouse gases such as Nitrous Oxide, Sulfur dioxide, Carbon dioxide etc. Also at present, it J Applied Chem. Sci. 2012, Vol. 1. Issue 2

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Sarker M et al. /Journal of Applied Chemical Science 2012, Vol. 1 issue 2: 9-17 is almost impossible to dispose of waste plastics in land fill due to law, high costs, and higher ecological consciousness of people. Recycling can be divided into further important categories, such as mechanical recycling, and chemical recycling. However, there are also some technological and economic constrains that limit the full and efficient recycling of waste plastics into useful products, e.g. contaminated waste plastics can be only partly recycled into new products and reuse of packaging containers is limited by the collection system. Chemical recycling is virtually a thermal method by which the long alkyl chains of polymers are broken into a mixture of lighter hydrocarbons. This is one of the prospective ways to utilize waste polymers [Manos G et al. 2000, Westphal C et al. 2001, Wong ACY et al. 2002, Lee KH et al. 2002, Joseph PV et al. 2002, Ballice L et al. 2002, and Hwang EY et al. 2002]. Up to the present moment, energy recovery by incineration has seemed to be an alternative option for waste plastics utilization that takes advantage of the high energy content of plastics and reducing the garbage volume. However sometimes, it was questioned due to the lack of raw materials recovery, the low thermodynamic efficiency, the possible emission of toxic gases as mentioned above and necessity of purification of flue gases that is difficult and expensive. Even though, current technologies would confirm the emission requirements, incineration arouses almost always public resistance and objections [Aguado J et al. 2008, Siddique R et al. 2008, and Stelmachowski M, 2003]. Thermal and first of all catalytic cracking process of waste polymers are economically and environmentally accepted methods of their utilization. The products of such processes are liquid mixtures of hydrocarbons boiling in the temperature range ~35360 ºC, gaseous hydrocarbons as well as solid residue, similar to wax and coke. Different type of catalysts, acid silica-alumina or zeolite (HY, HZSM-5, mordenite) containing ones as well as alkaline compounds such as ZnO, CaO and K2O can be applied, [Zhibo Z et al. 1996, Ding W et al. 1997, and Uemichi Y et al. 1998], but in the course of the process all these materials deactivate very quickly. Through the years excellent results have been obtained from Page | 10

J Applied Chem. Sci. 2012, Vol. 1. Issue 2

liquefaction of individual polymers (Polyethylene (PE), Polypropylene (PP) etc. and relatively clean mixed plastics using solid acid catalysts and metalpromoted solid acid catalysts. For example, Venkatesh et al. [1996] and Shabtai et al. [1997] have obtained high yields of liquids that consist predominantly of isoalkanes in the gasoline boiling range from HDPE, PP at relatively low temperature (300-375 ºC) using similar metal catalysts mentioned above. In this paper results of thermal cracking of mixed waste plastics using a steel reactor are presented. It was shown these materials (HDPE, LDPE, PP and PVC) can be thermally cracked giving liquid and fuels with close 85-90% efficiency. The described method in this paper does not utilize any forms of catalyst for the thermal conversion. Directed thermal cracking followed by condensation of the vapors are utilized to obtain liquid hydrocarbon fuel, gaseous hydrocarbon.

2. Experimental Process Waste plastic samples for experiment are collected form Stamford city supermarket and grocery store. Foreign materials are separated manually from the collected waste plastics. Foreign materials are always present in waste plastic such as food particle, dust, sand, paper etc. They are cleaned with liquid soap to rid of the contaminants. Washed waste plastics are then put to air dry in room temperature. During the washing period by- product is produce; this waste water is treated with a developed waste water treatment process. The dried plastics are then cut into smaller pieces. Then they are deposited in a grinder machine to turn into 3-5 mm size to fit into the reactor. Before the setup process the waste plastics are pre analyzed by GC/MS for compound structure identification, FT-IR is used for functional group and band energy contents, TGA is used for indentifying the temperature range for thermal degradation process and EA-2400 equipment is used for carbon, hydrogen and nitrogen percentage measurement of the waste plastics. The samples contained 3% PVC and rest of 97% were mixture of LDPE, HDPE, PP and PS. For experimental purpose we used only 1 kg of waste plastic. Grounded waste plastic (3-5 mm) were setup into the reactor chamber and placed into reactor (seen fig.1). We used temperature range from 150 ºC to 400

Sarker M et al. /Journal of Applied Chemical Science 2012, Vol. 1 issue 2: 9 -17 ºC for the thermal degradation process to convert the plastic samples into liquid product. Initial temperature setup is 150 ºC reactor display temperature was 25 ºC. When temperature increases gradually, the plastics to start to melt and starts to form vapor. At First the vapor is not condensed because it has moisture and it

is not vacuumed for thermal degradation process. When temperature increased up to 200 ºC we noticed that vapor start to come and start to condensed and fuel starts dropping in the collection flask. The process diagram is shown in Fig.1.

Fig.1: Fuel production diagram

Temperature is increased up to 400 ºC gradually until the end of the experimental process. It took a total of 4 hour and 30 mins to complete the whole process. During waste plastic to fuel production process all plastics are unable to turn into liquid, they escape as gas. The sample used for the experiment contained PVC and PVC contains 56% chlorine because of that we used gas cleaning system for removing chlorine from light gas. Chlorinated gas is passes through 0.25 (N) AgNO3 solutions and when light gas passes into AgNO3 solution this chlorinated

compound coming into AgCl2 percipient. Then light gas transfer into Teflon bag for storage. We did not use any catalyst or extra reagent to remove the chlorine. After the experiment finished we collected the chlorine mixture fuel. Production yield percentage 85 % liquid fuel, 6% light gas and solid black residue were 9%. The residue is collected and stored. It has been analyzed and the results are discussed further in the discussion section. So, out of 1000 gm sample we obtained 850 gm fuels, 60 gm light gas and 90 gm was solid black residue. Fuel appearance is light brown and J Applied Chem. Sci. 2012, Vol. 1. Issue 2

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Sarker M et al. /Journal of Applied Chemical Science 2012, Vol. 1 issue 2: 9-17 fuel density is 0.77 g/ml. This fuel has chlorine present for that reason we did not test with any internal

combustion engine. This fuel is flammable and it can be use only for feed stock refinery.

3. Results and Discussion DSC and carrier gas Nitrogen at 20 ml/ min was used for the fuel analysis (fig.2). DSC program setup at temperature range 5 to 400 ºC and ramping range 5 ºC/ minutes. Onset temperature shown 107.02 ºC, peak temperature 108.11 ºC, peak height 14.6376 mW and delta H is 5581.064 J/g. This fuel has an average boiling point of 108.11 0C which indicates it is acceptable amount of energy value. For the sample pre analysis procedure with the FT-IR, 50 L of the fuel is placed in a NaCl cell slide inside the FT-IR chamber. FT-IR uses an inferred technology to indentify the fingerprints of the samples. FT-IR analysis of mixture of HDPE-2, LDPE-4, PP-5 and PVC plastics to fuel (fig.3 and table1) following types of functional groups appeared in order to the wave number. Wave number versus functional groups are elaborated as much as possible ,as example wave number 3619.27 (cm-1) functional group is Free OH, wave number 2887.66 (cm-1) and 2671.82 (cm-1) functional group is C-CH3, wave number 1820.85 (cm-1), 1776.92 (cm-1) and 1772.35 ( cm-1) functional group is Non-Conjugated, wave number 1697.40 (cm-1), 1641.44 ( cm-1), 1605.31 ( cm-1) and 1585.85

(cm-1) functional group is Conjugated, wave number, wave number 1440.94 (cm-1) and 1378.89 (cm-1) functional group is CH3,wave number 1176.79 (cm-1) functional group is Formates, wave number 992.21 (cm-1) functional group is Secondary Cyclic Alcohol, wave number 965.30 (cm-1), functional group is CH=CH- (trans), wave number 907.55 (cm-1), functional group is - CH=CH2, ultimately wave number 721.61 (cm-1), 675.23 (cm-1) and 663.58 (cm-1) functional group is -CH=CH- (cis) as well. As shown in fig.4 the raw PVC plastics contains some similar compounds as the fuel such as, conjugated compound (-CH=CH-(cis). This indicates that the thermal reaction of the plastics were successfully carried into the fuel. For the sample pre analysis procedure of GC/MS 5 L of the fuel is injected inside the capillary column of the GC oven. The syringe is sterilized with carbon disulfide (CS2) prior to and after the sample is injected in the column. GC/MS analysis shown produced fuel inside has some aromatic compound such as Benzene (C6H6) at retention time 3.24 min and trace mass and molecular weight is 78 and 78,

Fig. 2: DSC Graph of Mixed Waste Plastic to Fuel

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Sarker M et al. /Journal of Applied Chemical Science 2012, Vol. 1 issue 2: 9 -17 Toluene (C7H8) appear at retention time 4.78 min and molecular weight is 92, p-Xylene (C8H10) compound shown at retention time at 6.96 minute and compound molecular weight is 106. Waste plastic to fuel production we used plastic HDPE, LDPE, PP and PVC for that reason we got also some chlorinated compound such as Butane, 2-chloro-2-methyl(C5H11Cl) at retention time 3.29 min and chlorinated compound molecular weight is 106. 1-Chloro-4methylcyclohexane (C7H13Cl) and Heptane, 3-chloro3-methyl- (C8H17Cl) compound are appeared at retention time 7.54 min and 8.23 min, both compounds molecular weight are 132 and 148. From GC/MS

analysis we found some oxygenated and alcoholic compound also such as 5, 10-Dioxatricyclo [7.1.0.0(4, 6)] decane (C8H12O2), 1-Nonadecanol (C19H40O). Most of the aliphatic compound appeared in this fuel like alkane and alkenes group are present. This fuel starting hydrocarbon compound C3 and longest hydrocarbon compound C28. We found also acidic compound Oxalic acid (C2H2O4) at retention time 2.13 min. This fuel has chlorine compound we cannot run by any combustion engine but this is ignite. This fuel can be used only for feed stock refinery for further refinery process.

65.0

60

55 2027.32

50

45

1938.28

3619.27

2342.91

40

35 1820.85

30 %T

1776.92

25

20 1585.85

663.58

15

632.12

1605.31

10

1176.79 1126.82

2671.82

5

1071.02

810.22

2731.18

0 1722.35 2887.66

1641.44 1697.40

1288.22

992.21

1440.94

675.23 965.30 907.55

721.61

1378.89

-5.0 4000.0

3600

3200

2800

2400

2000

1800

1600

1400

1200

1000

800

600

400.0

cm-1

Fig. 3: FT-IR Spectrum of Fuel

Table 1: FT-IR Spectrum Functional Group Name Number of Wave 1 2 3 7 8 9 10 11 12 13

Wave Number ( cm-1) 3619.27 2887.66 2671.82 1820.85 1776.92 1772.35 1697.40 1641.44 1605.31 1585.85

Compound Name Free OH (Sharp) C-CH3 C-CH3 Non-Conjugated Non-Conjugated Non-Conjugated Conjugated Conjugated Conjugated Conjugated

Number of Wave 14 15 17 20 21 22 24 25 26

Wave Number ( cm-1) 1440.94 1378.89 1176.79 992.21 965.30 907.55 721.61 675.23 663.58

Compound Name CH3 CH3 Formates Secondary Cyclic Alcohol -CH=CH-(trans) -CH=CH2 -CH=CH-(cis) -CH=CH-(cis) -CH=CH-(cis)


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Sarker M et al. /Journal of Applied Chemical Science 2012, Vol. 1 issue 2: 9-17 99.6 98 96 94 92 1579.88

90 88 86 1380.37

84

2857.99

1426.36

82

1462.82

1039.58

80 2958.49 957.57

78

704.21

%T 76

2924.92

74 72

742.29

70

635.82

607.17

68 66 1072.27 1122.24

64 62 60

1722.28

58 1271.37

56 55.0 4000.0

3600

3200

2800

2400

2000

1800

1600

1400

1200

1000

800

600

400.0

cm-1

Fig.4: FT-IR spectra of PVC waste plastic

Fig. 5: GC/MS Chromatogram of Fuel

As observed in Fig.6, the GC spectrum completely differs from the fuel spectra because the fuel has other plastic compounds in them. However, there are some compound similarities between them. This result verifies that that the thermal reaction was successful. Waste plastic to produced fuel analysis by GC/MS (Perkin Elmer) shown fig.5 and compound analysis table 2. Elite-5 capillary 30 meter length GC column used and carrier gas used helium. Auto sampler method used for GC, syringe capacity 5.0 µL, injection volume 0.5 µL and sample injection speed normal. Sample split flow 101.0 mL/min and initial set Page | 14


point 1.00ML/MIN and sample injector port temperature 280 ºC. GC program setup for sample analysis initial temperature 40 ºC and initial temperature hold at 1 minute and equilibration time 0.5 min, temperature ramping 10 ºC/ minute to 325 ºC and also hold 15 minute for 325 ºC. GC total run time for fuel analysis is 44.50 minutes. For mass detection MS program setup type ms scan ion mode El+, data format centroid, start mass scan 35.00 to end mass scan 528.00 and mass scan time 0.25 sec, inter scan time 0.15 second.

Sarker M et al. /Journal of Applied Chemical Science 2012, Vol. 1 issue 2: 9 -17

Fig.6: GC/MS spectra of PVC waste plastic Table 2: GC/MS Chromatogram Compound List Peak Retention Trace Compound Number Time (M) Mass Name 1 2 3 4 1 1.50 39 Propane 2 1.61 43 Butane 3 1.87 42 Cyclopropane, ethyl4 1.90 43 Pentane 5 2.13 75 Oxalic acid 6 2.48 41 Cyclopropane, 1-ethyl-2-methyl-, cis7 2.56 41 Hexane 8 3.12 67 Cyclopentene, 3-methyl9 3.24 78 Benzene 10 3.29 41 Butane, 2-chloro-2-methyl11 3.59 41 1-Heptene 12 3.71 43 Heptane 13 4.14 41 Cyclohexane, methyl14 4.28 41 Cyclopentane, ethyl15 4.53 81 Cyclobutane, (1methylethylidene)16 4.58 67 5,10Dioxatricyclo[7.1.0.0(4,6)]decane 17 4.78 91 Toluene 18 5.13 41 1-Octene 19 5.28 43 Octane 20 6.16 41 1-Pentanol, 2-ethyl21 6.22 43 1-Octene, 4-methyl22 6.37 41 1-Octene, 6-methyl23 6.86 41 cis-2-Nonene 24 6.96 91 p-Xylene 25 7.01 57 Nonane 26 7.54 81 1-Chloro-4-methylcyclohexane 27 7.66 41 Cyclopentane, butyl28 8.23 55 Heptane, 3-chloro-3-methyl-

Compound Formula 5 C3H8 C4H10 C5H10 C5H12 C2H2O4 C6H12

Molecular Weight 6 44 58 70 72 90 84

CAS Number 7 74-98-6 106-97-8 1191-96-4 109-66-0 144-62-7 19781-68-1

C6H14 C6H10 C6H6 C5H11Cl C7H14 C7H16 C7H14 C7H14 C7H12

86 82 78 106 98 100 98 98 96

110-54-3 1120-62-3 71-43-2 594-36-5 592-76-7 142-82-5 108-87-2 1640-89-7 1528-22-9

C8H12O2

140

286-75-9

C7H8 C8H16 C8H18 C7H16O C9H18 C9H18 C9H18 C8H10 C9H20 C7H13Cl C9H18 C8H17Cl

92 112 114 116 126 126 126 106 128 132 126 148

108-88-3 111-66-0 111-65-9 27522-11-8 13151-12-7 13151-10-5 6434-77-1 106-42-3 111-84-2 931-68-0 2040-95-1 5272-02-6


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Sarker M et al. /Journal of Applied Chemical Science 2012, Vol. 1 issue 2: 9-17 1 29 30 31 32 33 34 35

2 8.58 8.73 8.81 10.24 10.37 10.44 11.31

3 41 43 41 41 57 41 77

36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66

11.79 11.92 12.63 13.26 13.38 13.43 14.10 14.64 14.75 15.94 16.04 17.17 17.26 18.34 18.42 19.45 19.53 20.51 20.57 21.51 21.58 22.54 23.46 24.34 25.20 26.03 26.84 27.64 28.43 29.22 30.01

41 57 83 55 85 55 41 41 56 55 71 83 71 83 71 55 71 55 56 55 57 85 71 85 57 57 57 57 57 57 44

4 1-Decene Decane 2-Decene, (Z)1-Undecene Undecane 5-Undecene, (E)3a,6-Methano-3aH-indene, 2,3,6,7-tetrahydro1-Dodecene Dodecane Cyclododecane 1-Tridecene Tridecane 5-Tridecene, (E)1-Nonadecanol 1-Hexadecene Tetradecane 1-Pentadecene Pentadecane 1-Hexadecene Hexadecane E-14-Hexadecenal Heptadecane 1-Nonadecene Octadecane 1-Nonadecene Eicosane 1-Docosene Eicosane Heneicosane Heneicosane Pentacosane Heneicosane Octacosane Octacosane Octacosane Tetracosane Heptacosane Heptacosane

The residue obtained from the production process is analyzed to identify its calorific value and metal contents according to ASTM test methods. Metal tests by ICP-AES (ASTM D 1976) indicate that the residue has 5674.63 ppm Aluminum, 23,409.3 ppm Calcium and 18,491.6 ppm Sodium just to name a few. Also the residue’s gross heat of combustion according to ASTM D 240 is 5,742 BTU/IB. These Page | 16


5 C10H20 C10H22 C10H20 C11H22 C11H24 C11H22 C10H12

6 140 142 140 154 156 154 132

7 872-05-9 124-18-5 20348-51-0 821-95-4 1120-21-4 764-97-6 98640-29-0

C12H24 C12H26 C12H24 C13H26 C13H28 C13H26 C19H40O C16H32 C14H30 C15H30 C15H32 C16H32 C16H34 C16H30O C17H36 C19H38 C18H38 C19H38 C20H42 C22H44 C20H42 C21H44 C21H44 C25H52 C21H44 C28H58 C28H58 C28H58 C24H50 C27H56 C27H56

168 170 168 182 184 182 284 224 198 210 212 224 226 238 240 266 254 266 282 308 282 296 296 352 296 394 394 394 338 380 380

112-41-4 112-40-3 294-62-2 2437-56-1 629-50-5 23051-84-5 1454-84-8 629-73-2 629-59-4 13360-61-7 629-62-9 629-73-2 544-76-3 330207-53-9 629-78-7 18435-45-5 593-45-3 18435-45-5 112-95-8 1599-67-3 112-95-8 629-94-7 629-94-7 629-99-2 629-94-7 630-02-4 630-02-4 630-02-4 646-31-1 593-49-7 593-49-7

results indicate that the residue is high is energy content but it contains immense amount of metals. So it was concluded that the residue can be used for asphalt for carpeting purposes.

4. Conclusion In this study, a combined process of waste plastic such as LDPE, HDPE, PP and PVC was investigated to

Sarker M et al. /Journal of Applied Chemical Science 2012, Vol. 1 issue 2: 9 -17 develop method for chlorinated plastics hydrocarbon for feedstock refinery. The thermal degradation process is 4 type’s waste plastic with PVC leads to produce organic chlorine compound. This Thermal degradation complex polymer mixtures containing PE, PP was performed at 400 ºC in the presence of PVC. It was found that PVC decreased the amount of liquid products and increased the residue and gases yield. The highest effect was observed for simultaneous presence of PVC in the polymer mixture. The thermal process fuel consists of benzene derivatives toluene and p-Xylene but heteroatoms are also present as organic compounds. PVC affected the amount and distribution of chlorine containing compounds in thermal degradation process liquid hydrocarbon fuel.

Acknowledgement The author acknowledges the support of Dr. Karin Kaufman, the founder and sole owner of Natural State Research, Inc. The authors also acknowledge the valuable contributions of laboratory team members during the preparation of this manuscript.

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Source of support: Nil, Conflict of interest: None Declared


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