Enzymatic Production of Biodiesel fronl Jatropha Oil

Chapter

10

Enzymatic Production of Biodiesel fronl Jatropha Oil GULAR S. TIIAKun, BIIAGWAN S. SANODIYi\, G.B.K.S. Pl{ASAD AND

P.S.

BISLN

10.1 INTRODUCTION Today's trclnsportation sl'rvices in industrialized countries arc primarily based on fossil fuels espec ially crude oil derivatives. The spread of this fossil energy intensive approach to developing countries and econ o miL' s in transitions with large popu lation may be constrained by limited resource availability and concerns ilbout environment and human health. One of the most important questions that are haunting us today is the global warming, climate change and the soil & e nvironnwntal pollution. lncreasing industrialization in the developing world is leading to spiraling inCl"cas(' in the d e mand of fossi l fuel. Biodiesel is one Stich option for which many countries are taking initiatives in this direction (Frclncis ct tTl., 2005). Biodicsel is a source of renewable energy that is made from biological sources c1nd is an attractive alte rncltive to fossil dit'sel fu e l because of its environm ental benefits. It is biodegmdablc, non-toxic, clnd has a low emission profile (Fukuda et nl., 200"1; Du ct nl., 2004; Wardle, 2003; Tomas('vic ilnd iVlcuinkovic, 2003). With cln increasing focus on renewable sourCl'S of energy in terms of Il1drketing, usage, distribution and general acceptance, the opporhll1ities for producers of biodiese l are promin ·'nt. Heccntly, more and more attention have been paid to enzymatic production of biodiescl, since no complex operations are nced('d for the recovery of glycerol and also for eliminating tIll' catalyst ill1d salt in comparison with chemical methods using alkclline catalyst (Du et aI., 2007; Iso ct nl., 2001 and Du ct til., 2005). However, the cosl of lipase is the main hurdle of the industrialization of lipase-cataly zed biodiesel production (Ban et nl., 20m , Du ct nl., 2007). Utilizing whol1e cell biocatillyst for biodiescl fuel production is one way to reduce the cost of lipase since it can avoid the complicated processes of isohltion, purif,i cation and immobilization of extracel lular lipase which account for a large part in the lipase cost (Ban et ill., 200l, Du eI nl., 2007). It has been demonstrated that

266

GULAB S. THAKUR, BHAGWAN S. SANODIYA, G.RK.S. PRASAD AND P.S. EISEN

whole cell of /"\.01'.11:11(' could effici('ntly catalyze the methanolysis of vegetable oils for bindiesel production in solVl'nt-free system (Ban ct Ill., 2001, Du et nl., 2007, Zeng ct I1l., 20(6) . Stepwisl' ,ldditiol) ot Illdhanol was recnmnwnded. to minimize the negative effect of mclhc1l1ol on the cKtlvity of {(ory:t1c whole cell (Ban l'1 Ill., 200"1). /l7tro!,III1 CllmlS, an ,lgro-forestry crop is a genus comprising of 70 species growing in tropical and sub-tropi cal cOllntries. Jatrophil grows as a natural habitat across sub­ Sahara AlTica , Indict, South+ast Asiil and Chinil . It grows rapidly, takes approximately 2-3 yeclrs to n~ach Illilturity and generate economic yields. It has il productive lifespan in excess of 30 YCMS. The fatty acid composition of Jatropha nil is similar to other edible oils but the presence of some anti-nutritional (clCtors such as toxic phorbol esters renders this oil unsuitable for cooking pllrposcs (Shah ct 01., 200'1). Jatropha oil is thus a promising candidate for biodiescl production in terms of availilbility and cost.

Transesterification of vegetable oils is an important reaction that produces fatty acid alkyl esters that Me valuable intermediates in oleo chemistry, and methyl and ethyl esters which arc excellent substitutes for diesel fuel. TransesterifiCiltion as an industrial process is lIsu em ployed are sodium or potassiulll al"koxidcs, as well as their carbonates. Sodium methoxide, for example, is moisture-sensitive, and the substrates (oil and alcohol) must be essentially anhydrous (free of water) for the reaction to proceed to the right to a great extent without hydrolysis of t he p;·oducts. Sodium methoxide (0.5 mol %) is very reactive and can easily give >98%

268

GULAB S. THAKUR, BHAGWAN S. SANODlYA, G.B.K.S. PRASAD AND P.S. BISI'N

alkyl ester in 30 mill. Acid catalysts can be, but are rarely, used because they are co rrosive and result in slower reactions and a low yield of fatty acid methyl ester. Vegetable oils with high free fatty acid contents are better esterified with acid catalysts. No soap is formed with acid catalysts, but higher temperature and higher substrate molM ratios may bl:! needed . The preferred acid catalysts are sulfuric (Freedman et (II., 1984), hydrochloriC, sulfonic, and organic-sulfuric acids because they give high yields of fatty acid alkyl esters. Acid catalysts require a substrate molar ratio of up to 30:1 at 55-80°C wilh a 0.5-1 mol % catalyst concentration to yield approximately 99 % biodiesel in 50 h (Marchetti ct (II., 2007). Other acid-based catalysts such as methanolic HCl or methanolic H 2S04 that are routinely used to prepare fatty acid methyl ester for gas chromatographic ancllysis of fatty acids could be used for biodiesel production (Srivastava et (II., 2006). In ge neral, using chemical catalysts results in a falty acid methy l ester yield> 98% . Transeste rification or alcoholysis reaction can be carried out with enz.ymes, and numerous examples abound in the literature (Shaw et nl., 1991; Kaieda et aI., 2001; Al­ Zuhair ct (Ii., 2006; Pizarro and Park, 2003, Park ct nI., 2005; Ou et aI., 2004, 2006; Wang et ai., 20Cl6; Nie et ai., 2006). There is a current inte rest in using lipases as th e biocatalyst to commercially convert vegetable oils and fats to fatty acid methyl esters as biodiesel fuel, since it is more efficient, highly selective, involves less energy consumption (reactiollS can be carried out in mild conditions), and produces less side products or waste (environmentally favorable) . Most of the recent research involved determining the best enzyme source and optimizing the reaction conditions (substrate molar ratio, solvent (Park et IIi., 2005) or no solvent (Ou ct al., 2006), temperature, water content (Pizarro and Park, 2003, Park ct Ill., 2005; Ou ct (Ii., 2004), free fatty acid level (i\l-Zuhair c:t 111., 2006), percent conversion, acyl migration (Du ct al., 2005), and substrate flow rate in packed bed bioreactors) to improve the yield of biodiesel comparable to base-catalyz.ed reactions and for possible industl'ial scaJe-u p and use. Enzymes have several advantages over chemical catalysts such as mild reaction conditions; specificity, reuse; and enzymes or whole cells can be immobilized, can be gene tically engineered to improve their efficiency, accept new substrates, are 1110re thermostable, and are considered natural, and the reactions they catalyze are considered" green" reaclions. i\ major problem with lipase reaction with methanol is enzyme inactivation by methanol. This problem has been studied and presumably solved by Shimada ct nl., (2002), who reported that the stepwise addition of methanol will alleviate methanol inactivation of Cn/ldida nJltarctica iipase and results in 90% yield of falty acid methyl ester from \v(\ste oil. This enz.yme WelS stable for 100 days and could be reused up to 50 times without a significant loss of activity . few studies have considered the nature of the alcohol used in the transesterification reaction . The addition of cosolvents such as t-butanol (Li ct aI., 2006) appeared to prevent methanol inactivation of tl1e lipase. Enzyme-catalyzed alcoholysis reactions can be performed in the presence or absence of a solvent, and it requires less energy and practically no pudfication to obtain FAME compared to base-catalyzed alcoholysis, where soap formation presents downstream processing disadvantages. Biocatalyst removal , if immobiJized lipase is used, is . by simple filtration or is not required if a packed bed bioreactor is used for the continuous production of biodieseI. In general, enzyme catalysts at 4-10 wt % resutt in fatty acid methyl esters yields of 55-97% in 3-120 h at 30-50 °C (Pinto et nl., 2005).

ENZYMf.TIC PRODUCTION OF BIOmJ:SEL FROM JATROPHA OIL

10.3 SOURCE

or

269

LIPASES

Lip"ses are found in all living organisms and arE' broadly classified as intracellular and cxlrc1cl'~f uliH. llwy are also classified 011 the b,lSi5 of the sources from which they are obtained, slich as lllicworganism, anilllal, .and plant. LipclS(~S Ciln be produced in high yields from microorganisms such as bacteria and fungi. rn practice, microbial lipases are commonly used by till' industry. The selection of a lipase for lipid mod ification is based on the nature of modification sought, for illstilnce, position-specific modification of triacylglycerol, fatty t1cids- specific modification, modification by hydrolysis, and modificcltion by synthesis (direct synthesis tlnd transesterification). The literature survey showed the USE' llf lipases frolll some of the following sources. Microbiallipases are derived from Aspergilllls lIiger, Kneil/lls tll!'r/llo/C(lVOrllIlS, Call1fieia cylilldl'l1cca, COlldido rugosa, Cilrollio/>oclcrilllll Vi~CtlSIl/l1, Ceo/ric/III/II ((lI/didlllll, FII50rilllii 11!'/('I'ospOrtUll, FlIsarilllll oxyspol'llm, HII/1/ico/l7 itlllligillOS(', Nfllcor wieitei, ()o~l'0rn lactis, PCllicillilli1i Cyc/Opilllll, PCI/icil/illlli roqucforti, P5CIIt!OIl/lllltlS 17('rtl.'\iIl0517, P~[,1/dOIIl(Jlla~ ccpl7cin, r~cllriollt(llltlS jl11orcsCt'lIs, fJ~clld(ll'/()11115 pHtidn, f,hizoplls l71'riti:II ,';, Rlli:opllS /)OrCI75, J\itiz.0I}II~ titCfIIIOSII ,C , Rlzizoj1l1s II S/ll II ii, [Vli:oI'1l5 st%llija, glzi:ojllls filsi!rmllis, J,lti:O)l1l5 .. i,.(i,1l1115, /~/II:OJ7I1S tlc/cll/llr, Rlti:orll5 cllillCIISis, Rlli:nj'lIs jl1p[illiclIS NR-t.OO, /~lti ::'(l/){{'; IIlicro:'{/(lrtl ..;, RIII:olllllcor lIIiellel, Rlti:oplls lligriClIlIs, Rliizoplls IIIVeIIS, RllizoplIs ory:ac, RJllzollllS rlli::opodiJol'lllis, Rltizoplts slol(}lI~rcr NRRL 1478, RllOdotomla 1'11/11'11, and Sttlj1/lylocot'clis ltyicIIs, to nalllc a few (Selilppan and Akoh, 2(05). Animal sources

are frolll pancreatic lipases, c11ld plant lipases arc from papaya latex, oat seed lipase, and C onto the interface initiates a sequence of events before complete ciltc1lysis can be ilchicved. Adsorption leilds to activation and substrate binding followed by cat. J. Mol. (~tI/lll. R: EII:YIII.16: 53-58. Kaieda M, Samukawa T, Matsumoto I, BcHl M, Kondo A, Shimada Y ('1999). Bindicsel fuel production froln plant oil calalyzed loy Rlliwl'"s Ol~/Z'JC lipase in a water - containing s),stcln without an organic solvent. j. Biosci. BioclIg., 88(6): 627-631. Kaieda, M., Smnuk"wa, T., Kondo, A., Fukuda, H. (2000) Effert of methanol and water contents on production of hiodiesel fuel from plant oil catalyzcd by VMious Iipas(;'s in " solvent­ free system. f. Bio~ci. Bioel/g. 91: 12-15. Korbitz, W. (1999) Biodiesel production in Europe and North America, an encouragine prospect. Rellcwabie El1ergy, l6: 1078-1083. Lai,

c.,

Zullaikah, 5., V"li, 5.R., ju, Y. (2005) Lipasecatalyzed production of biodiesel from rice brCln oil. / Clzelll TeciInDI Bio/edillol, 80: 331-337.

Li, L., Du, W., Liu, D., Wang, L., Li, Z. (2006) Lipase-catalyzed transesterification of rapeseed oils for hiodiesel production with a novel organic solvent as the reaction medium. j . Mol. Ca/il/. B: EIlZYIII., 43: 58-62. Linko, Y. Y., Liimsii, M., Wu, X., LJosukainen, W., 5appiilii, J., Linko, P. (1998) Biodegl'ildabJt> prodllCL~ by lipase. biot'a/"lysis. /. Biolcclnwl. 66: 41-50. Ma, F., Hanna, M. A. ('1999) Bicdiesel production: a review. Biarrsolil'. Tecl1l1ol. , 79:1--15. Mamol'Ll, 1.5.0., Baoxue, c., Masashi, E. (200'1). Production of biodiesel fuel from triglycerides and alcohol using I mlllobilized lipase. J. Mol. Co/a/. 16: 53-58. Marchetti, j. tv\., Miguel. V. U., Erl'ilzu, A. F. (2007) Possible methods for biodiescl production. R.cnewahle Sustainahle Energy Rev., 11 : 1300-131l.

ENZYMATIC PRODUCTION 01' BIOD/I,SEL FROM JATROPHA

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OIL

Matsullloto, T., T'lkahashi, S.A" K,li,'dc1, i\ i. , i,eds, M., Tanaki,l, A., fukuda, II. (200l) . Yeast wh(1\e­ cell bioGlt