The oil from J. curcas is the most important product obtained from the plant. For the maximum yield of oil, the seeds should be harvested at maturity. The seed yield depends on the following main factors: rainfall, soil type, fertility of soil, genetics, age of the plant, and different propagation strategies. The oil from seeds is of great interest to the investors mainly because it holds several properties like less viscosity, better oxidation stability, low acidity, good cold properties, and lesser processing costs. Moreover, Jatropha oil is odorless and colorless when fresh but turns yellow on standing due to oxidation. The presence of more than 75% of unsaturated fatty acids in Jatropha oil reflects its low pour point (270 K) and cloud point (275 K). The calorific value of the oil ranges from 37.83 to 42.05 MJ/kg (Achten et al. 2008). The oil content of kernel ranges from 45 to 60% by weight and that from the seed shell varies from 30 to 50%. Due to the presence of phorbol esters and curcin in seeds and oil, it is considered toxic for consumption but safe for biodiesel production. In addi­tion, oil from Jatropha has been highlighted as a potential nonedible feedstock for biodiesel production mainly due to its high cetane number similar to diesel. This property makes it a good alternative fuel which can be applied to conventional engines (Tapanes et al. 2008). In addition, Jatropha oil is also used for production of soaps and biocides (insecticide, molluscicide, fungicide, and nematicide) (Shanker and Dhyani 2006).

Table 12.2 shows the fatty acid composition of J. curcas oil. The Jatropha oil is rich with unsaturated fatty acids like oleic and linoleic acids with minor amounts of saturated fatty acids such as palmitic and stearic acids. The amount of fatty acids in the oil varies from one country to another. Fatty acid composition can be altered to some extent through interspecific hybridization or gene silencing (Achten et al. 2008).

Due to high amount of unsaturated fatty acids such as oleic and linoleic acids in Jatropha oil, the biodiesel produced from it has desired low temperature properties. The physicochemical properties of Jatropha oil are shown in Table 12.3. Jatropha oil is renewable, clean, and safer to use. In short, J. curcas has been referred to as “Green gold” in Biofuel industry due to its potential benefits of oil to produce bio­diesel which can replace petroleum-based diesel (Koh and Mohd Ghazi 2011; Abdulla et al. 2011).

Table 12.2 Fatty acid composition of crude Jatropha curcas oil (Berchmans and Hirata 2008)

Table 12.3 Physicochemical properties of Jatropha oil (Achten et al. 2008)

Once seeds are harvested from the plant, they are used for oil extraction or expulsion. The process of obtaining oil from seeds is as old as mankind, but the procedures and infrastructure have gained much improvement these days. In addition to the seeds, the other inputs are machines, infrastructure, and energy. Outputs include Jatropha oil as main product and seed cake, which is an important by-product in the process. Two main methods have been identified for oil extraction, namely, (1) mechanical extraction and (2) chemical extraction. Before extraction, the seeds have to be sun dried for 3 weeks or oven dried 105°C to expel the water content. For mechanical pressing, the seeds are used as such. On the other hand, for chemical extraction, only powdered kernels can be used. The conventional method of oil extraction is mechanical pressing.

It is normally done on a small scale and especially in rural areas by using either manual ram press or electric screw press. The main drawback here is that only a small amount of oil can be expelled through these presses. Pretreatment of seeds like cooking is shown to increase the oil yield to a better extent. In chemical method of extraction, я-hexane solvent is the most widely used one. But this requires lots of time for extraction.

Recently, aqueous oil extraction technique has given satisfactory yield. Since this process is environmental friendly, it does not produce harmful volatile organic compounds that could harm the atmosphere. Lack of commercial availability of

particular enzymes and the long process time required by the enzymes to liberate the oil bodies are considered as the major drawback of this procedure. In another method, namely, enzyme-assisted three-phase partitioning (TPP), a combination of sonication and enzyme treatment is used. The main advantages of this procedure are higher yield and lesser reaction time. But the high cost of enzyme and higher energy input for sonication can be an obstacle (Aderibigbe et al. 1997; Forson et al. 2004; Achten et al. 2008; Abdulla et al. 2011).

Table 12.4 gives an outline of different researches done for oil extraction and their respective yields.

Rosalam Hj. Sarbatly and Emma Suali

Abstract The integration of a membrane contactor with a photobioreactor serves two major purposes for the mitigation of CO2 by microalgae, i. e., to enhance the mass transfer and interfacial contact between two different phases and to increase the exchange process of CO2-O2 by microalgae in the photobioreactor. The membrane integrated with a photobioreactor for CO2 mitigation by microalgae can be consid­ered as a relatively new field, and only four or five related research efforts have been published in the literature, suggesting that a significant amount of work remains to be done in this field. In addition, all of the authors agreed that a membrane contactor is capable of achieving better mass transfer than the conventional approach of using a separation column in the gas-liquid separation process. One significant problem associated with using a membrane as a CO2-O2 gas exchanger is its susceptibility to pore fouling due to the micron-size cells of the microalgae. However, pore fouling can be prevented by using a hydrophobic membrane contactor and appropriate oper­ating conditions, both of which are discussed in detail in this work.

Keywords CO2 sequestration • Microalgae • Membrane photobioreactor • Biomass

14.1 Introduction

I nterest in microalgae has been increasing in many fields of research, including biofuels and pharmaceutics, because of their high photosynthetic rate. With an aver­age growth rate that is estimated to be 40 times greater than that of a fast-growing plant (Suali et al. 2012), microalgae are capable of producing biomass, on a dry — weight basis, that contains 20-80% lipids, mainly triglycerides.

R. Hj. Sarbatly (*) • E. Suali

School of Engineering and Information Technology, Universiti Malaysia Sabah, Jalan UMS, 84000 Kota Kinabalu, Sabah, Malaysia e-mail: rslam@ums. edu. my; emma. suali@gmail. com

R. Pogaku and R. Hj. Sarbatly (eds.), Advances in Biofuels, 241

DOI 10.1007/978-1-4614-6249-1_14, © Springer Science+Business Media New York 2013

Microalgal biomass is being considered as a renewable and sustainable energy source; the algae require nutrients that are widely available for producing the biomass. In addition, microalgae have the ability to utilize and convert CO2 into biomass, which can be harvested and used as biofuel (Sarbatly and Suali 2012), thereby pro­viding an alternative source of energy.

The ability of microalgae to utilize greater quantities of CO2 compared to ter­restrial plants makes them one of the most promising biological approaches for CO2 mitigation. Microalgae can remove significant quantities of CO2 from the atmo­sphere because they optimize the photosynthesis process by maximizing CO2 utili­zation and oxygen production. The CO2 is usually supplied to a microalgae culture system via CO2-enriched air. Thus, the CO2 supply also alters the circulation of cells in the culture system through the formation of bubbles, thereby enhancing the mass transfer rate of gas in the culture system. The mass transfer of gaseous O2 away from the sites where photosynthesis is occurring is important because, if the concentra­tion of O2 is allowed to increase, the CO2 utilization by microalgae will be decreased.

The current conventional injection technique that is used to supply CO2 to the cul­ture system creates bubbles that have random sizes. This can impede the uniform dis­persion CO2 throughout the media culture, which will have an adverse effect on the productivity of the microalgae. In addition, the injection of non-uniform, excessive concentrations of CO2 can result in high hydrodynamic stress that can kill the microal­gae and increase the release of CO2 to the atmosphere. Thus, dispersion devices are essential for the success of the process, and membrane contactors have high potential for successful use as a dispersion device. A photobioreactor that uses a membrane contactor as a dispersion device is referred to as a membrane photobioreactor.

The efficiency of a membrane photobioreactor for sequestering CO2 depends strongly on the CO2 concentration (Cheng et al. 2006), because this is associated with the transfer of O2 from the liquid phase to the gas phase and the transfer of CO2 from the gas phase to the liquid phase. The equilibrium that initially existed between the algal cultures in the solution and the inlet gas flow rate and composition is altered when the membrane module is integrated into the system. The membrane allows the recirculation of unused CO2 and also allows the operation of the system at lower gas pressures. To optimize the photosynthesis process, the periods of CO2 availability and light availability must be in phase with each other (Ferreira et al. 1998; Carvalho and Malcata 2001). Thus, the use of a membrane photobioreactor for CO2 mitigation must be coordinated carefully with the culture technique in order for the microalgae to optimize the photosynthesis process.

Agricultural sector has long been a major national economic contributor in Malaysia. Oil palm is by far the most important plantation crop in Malaysia, accounting for 5.0 million hectares in planted area and a production of 18.9 million tonnes of crude palm oil in 2011 (MPOB 2012). At the same time, it also generates large amounts of biomass as empty fruit bunches (EFB), mesocarp fiber (MF), palm kernel shell (PKS), and palm oil mill effluent (POME) from the palm oil mills and pruned oil palm fronds and felled oil palm trunks in the plantations. It was estimated that a total of about 80 million tonnes of dry oil palm biomass was produced in 2010 and is expected to increase to about 100 million tonnes by 2020 (Agensi Inovasi Malaysia 2011).

On current course, most of the solid biomass will remain in the plantations with a small amount being utilized for bioenergy generation. The oil palm biomass could be more efficiently used for the production of higher-value-adding bioenergy, bio­fuels, and bio-based chemicals. The timeline of technology availability for the development of the biomass industry is outlined in Fig. 2.4.

A scenario of utilizing an additional 20 million tonnes of oil palm biomass by 2020 for higher-value uses has the potential of contributing a gross national income (GNI) of additional RM30 billion to the national economy by 2020 (Agensi Inovasi Malaysia 2011). In addition, the National Biomass Strategy 2020 offers Malaysia a way to meet its renewable energy target, reduce emissions (12% CO2e abatement), and create about 66,000 jobs. The strategy also offers an opportunity for Malaysia to build several biofuel and bio-based chemical downstream clusters to ensure the nation benefits from the downstream value creation potential. It also creates addi­tional businesses opportunities in other related industries.

To ensure this opportunity is realized, the government is taking decisive and concerted efforts across ministries and agencies as well as engaging extensively with the private sector to realize these investment opportunities. The government is committed to generating new wealth creation from biomass and making it a reality for the nation with the establishment of 1Malaysia Biomass Alternative Strategy (1MBAS) taskforce as a one stop point of contact for all biomass utilization activi­ties (Agensi Inovasi Malaysia 2012).

The shortage of wood (due to resource depletion) for furniture coupled with its high and fluctuating costs has increased the zeal for many researchers to seek for alterna­tives. OPW in the form of solid residues such as EFB, OPT and OPF have been used currently in producing good quality furniture (Abdul Hamid et al. 2005). The high — density gradient which exists along the radial and longitudinal direction of the OPT makes it less attractive to be used either as lumber or plywood (Loh et al. 2011). However, other studies have improved upon these properties to make OPT suitable for high-quality lumber. Abdul Khalil et al. (2010) have used OPT and EFB in pro­ducing special plywood using phenol formaldehyde. They concluded that hybridi­sation of EFB with OPT produced a better quality plywood in terms of bending strength, shear strength and screw withdrawal compared to that produced from OPT alone. Pretreatment of OPT veneers with low molecular weight phenol formalde­hyde (LMWPF) improves its surface roughness and density in which the plywood produced is able to control liquid penetration to more than 30 s (Loh et al. 2011). Hoong et al. (2012) recently reported on a new method of producing high bonding strength plywood (of 259% stiffness) from OPT using low molecular weight phenol formaldehyde (LmwPF) resin. Other studies (Paridah et al. 2006; Anis et al. 2003; Sulaiman et al. 2009) have also produced high-quality plywood from OPT. Laminated veneer lumber from OPT together with other palm furniture has been produced and on sale in Japan (Abdul Hamid et al. 2005).

The production of binderless particle boards from OPTs (Lim and Gan 2005; Ratnasingam et al. 2008) and steam-exploded pulps and fibres from the OPF (Laemsak and Okuma 2000) has been reported. OPW solid residues have also been utilised for the production of fibreboards as furniture, building and wall-partitioning materials (Wahid et al. 2005).

In most parts of Africa and some parts of Asia, OPLs are traditionally used as roofing and partitioning materials of huts and mud houses. In order to make the roofs durable and strong, clay is used to bind the OPLs to the ceiling beams of the hatches.

Processed palm wood is found to be resistant to termites, mould and wood rot thus makes them applicable for use in both moist and dry conditions. Again, the production of palm wood for furniture is reported to be environmentally safe (emitting about 1.5 kg CO2/kg product) compared to the production of steel, aluminium and glass with CO2 emissions of 23.9, 12.0 and 8.4 kg CO2/kg product (Wahid et al. 2005).

Y. H. Taufiq-Yap and H. V. Lee

Abstract To date with the day of less dependence with fossil-based energy, there has been extensive research into the area of generation for alternative fuel—biodiesel for utilization in diesel engine. Development of effective catalyst is important for continuous biodiesel production. Select a right catalyst together with suitable feed­stock is necessary to create an economically viable and sustainable energy source. Although homogeneous catalyzed reaction showed superior transesterification activity than heterogeneous system, but the focus on the development of solid green catalyst becomes more attractive due to the point of easy process and economics concern. Furthermore, the catalytic activity of solid catalyst was comparable to that of the existing liquid catalyst. This chapter reviews various types of homogeneous and heterogeneous catalysts used for transesterification of high free fatty acid oil (Jatropha oil). The process involves single-step or two-step reactions which rely on the physicochemical properties and flexibility of catalyst.

Keywords Biodiesel • Heterogeneous catalyst • Homogeneous catalyst transes­terification

10.1 Introduction

The exponential increment in petroleum crude oil demand as energy source and deleterious environmental impacts with the restrictions imposed by environment conservation agencies have created an impulse to develop new sustainable energy sources and alternative fuels. Biodiesel plays a major role in energy sector due to its similar combustion properties with petrodiesel (Altin et al. 2001), which can be used in compression-ignition (diesel) engine with little or no modification. Chemically,

Y. H. Taufiq-Yap (*) ♦ H. V. Lee

Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, Selangor, Malaysia e-mail: yap@science. upm. edu. my; leehweivoon@yahoo. com

R. Pogaku and R. Hj. Sarbatly (eds.), Advances in Biofuels, 153

DOI 10.1007/978-1-4614-6249-1_10, © Springer Science+Business Media New York 2013

biodiesel is a mono-alkyl ester of long chain that can be prepared from triglycerides of renewable feedstock (vegetable oils or animal fats) by transesterification with methanol in the presence of catalyst. This process reduces the viscosity to a value comparable to that of diesel and hence improves combustion (Leung et al. 2010). Their physicochemical properties such as energy content, cetane number, and vis­cosity are similar to those of petroleum-based diesel fuels. Furthermore, biodiesel consists of several technical and economic advantages which make this 100% natu­ral energy alternative to petroleum-based fuels (Wardle 2003). The advantages are:

1. It prolongs engine life and reduces the need for maintenance (biodiesel has better lubricating qualities than fossil diesel and less sulfur content).

2. It is safer to handle, being less toxic, more biodegradable, and having a higher flash point.

3. It reduces exhaust emissions.

4. Production of by-product (glycerol) is another value adding characteristic which makes commercialization of biodiesel more viable. (Crabbe et al. 2001).

The pH stability of free and immobilized lipase were studied by incubating at 25°C in phosphate buffers of varying pH (3-10) for 1 h. The hydrolytic activity was deter­mined at optimum pH and temperature. After the incubation time, the immobilized beads were separated from the buffers, filtered, and air dried at room temperature, and its catalytic activity was measured as described in Sect. 12.5.2. Relative activi­ties were calculated as the ratio of activity of immobilized enzyme after incubation to the activity at optimum reaction pH.

Enzyme surface contains large number of acidic and basic groups. Depending on the pH of the medium, the charges on these groups may vary. This in turn alters the activity, structural stability, and solubility of the enzyme molecule. Also a change in pH can lead to the breakage of ionic bonds that hold the tertiary structure of the enzyme and also affect the charges on amino acids inside the active site so that the enzyme cannot form enzyme-substrate complex. In short, the effect of acid H+ ions and basic OH- ions on enzymatic activity is caused by a change in stereo configura­tion at or in the neighborhood of enzyme molecule’s active site (Seyhan et al. 2002). Relative activities of both free and immobilized lipase as a function of pH are depicted in Fig. 12.5b.

The thermal stability of free and immobilized lipase were tested by incubating at various temperatures in the range of 25-60°C for 1 h at pH 7. Lipase activity at optimum temperature was found out as in Sect. 12.5.2. Relative activity as a func­tion of temperature is shown in Fig. 12.5c. Optimum temperature for free lipase was found to be 30°C and that of immobilized lipase was found to be 40°C. It shows that immobilization resulted in higher activation energy for the enzyme. The elevated activation energy than the free enzyme implies an increased energy barrier, which

Fig. 12.5 (a) Leakage of protein from the beads as a function of incubation time in phosphate buffer of pH 7.0; (b) pH stability of free and immobilized lipase; (c) temperature stability of free and immobilized lipase at pH 7; (d) storage stability of free and immobilized lipase at 4°C in dif­ferent buffers; (e) reusability of immobilized lipase forp-NPP hydrolysis; (f) time course of olive oil hydrolysis by immobilized lipase with and without cross-linking

means that the immobilized enzyme needs an elevated temperature to attain its highest activity. It was also noted that the hybrid matrix used here could withstand a temperature up to 60°C, beyond which there was slow disintegration of the matrix. This implies that immobilized B. cepacia lipase can be applied at higher tempera­ture. The study demonstrates that the hybrid matrix used here shows good thermal resistance which comes as an important property in industrial applications.

Characterization of the degradation products or intermediates of different types of biomass (Boocock et al. 1980; Yokoyama et al. 1984; Matsumura et al. 2005) dur­ing gasification is important to obtain more detailed information on the chemistry of biomass conversion. When biomass wastes containing heteroatoms such as sul­fur, nitrogen, and halogens are subjected to hydrothermal processes, a series of toxic heteroatom compounds that can cause deterioration to the environment is formed. Previous researches about heteroatomic compounds used nondirect or batchwise measurements where cooling processes were necessary. During this pro­cess, some heteroatomic compounds could change chemically and some analytical information could be lost. The time for collecting the data was also quite long. Mass spectrometry has not extensively been applied to direct measurements. Research conducted by our group where nondirect measurements and cooling pro­cesses were necessary has shown that hydrogen can be formed from various bio­wastes by degrading them using hydrothermal process (Yildiz Bircan et al. 2011; Ishida et al. 2009).

We have developed an online measurement system for heteroatomic compounds at desired temperatures by using a lithium attachment mass spectrometer (Li-IAMS) (Alif et al. 2011, 2012). By this method the cooling process was eliminated and a shorter measurement time was achieved.

Ion-attachment mass spectrometry (IAMS) (Fujii et al. 2001; Tsukagoshi et al. 2012) is a “soft” ionization similar to chemical ionization in which a cation is attached to the analyte molecule. This technique is preferably applied to electro­negative compounds without fragmentation because ionization occurs by attach­ment of a lithium (or alkaline) ion to the gas molecules to be analyzed.

The objective of this study is to determine the mechanism of heteroatomic com­pounds formed through the hydrothermal reaction of biowaste. Specifically, l — cysteine as a model sample and durian fruit as real biomass have been analyzed focused on sulfur compounds. In addition, the effect of alkaline, Ca(OH)2, on the suppression of sulfur compounds has also been studied.

A. H. Kamaruddin, N. A. Serri, J. H. Sim, S. F.A. Halim, and S. R.A. Rahaman

Abstract The rapid increase in the crude oil prices due to diminishing reserves of fossil fuels and the increased rate of world energy consumption have drawn atten­tion of the researchers for alternative energy source. Biodiesel, also known as fatty acid methyl ester (FAME), has become more attractive as an alternative fuel resource because of its environmental benefit such as biodegradable, nontoxic, and low emis­sion profiles. Presently, Malaysia is now looked upon as the pioneer palm biofuel producer. Malaysia is well known to be the largest producer of palm oil and palm oil products. Therefore, sustainability of feedstock for biodiesel production is not an issue for the present demand of alternative energy resources. Currently, industries are implementing chemical routes using alkaline catalyst which is a non­environmental friendly process and the presence of impurities as by-product needs to go through further purification steps in the downstream process. The green tech­nology of enzymatic transesterification is suggested as an alternative method for biodiesel production. The study of transesterification from edible and nonedible oil such as crude palm oil (CPO), waste cooking oil, and sea mango oil by immobilized lipase is highlighted. The transformation of palm oil into value-added product bio­diesel can help to increase its commercial value of palm oil.

Keywords Biodiesel • Transesterification • Green technology • Plant oils [4] [5]

Heterogeneous catalyzed transesterification is a merit process to produce superior grade of biodiesel and by-product glycerol in a simpler pathway. Transesterification activity of solid catalyst is as high as homogeneous catalyst with the presence of the characteristics, which were discussed in Fig. 10.2. However, crude biodiesel from heterogenized catalyzed reaction cannot be use directly in vehicle engine as it does not meet the EN 14214 or ASTM D6751 standard. Biodiesel (ASTM or EN) standard is needed to ensure the following important factors in the fuel production process are satisfied: (1) complete transesterification reaction (conversion of oil and selec­tivity of methyl ester), (2) removal of glycerin, (3) removal of catalyst, (4) removal of alcohol, (5) removal of soap product, and (6) complete esterification of FFAs (Balat and Balat 2010). The products are sometime contaminated with alcohol, and un-reacted oil and metal leaching from the solid catalyst during transesterification step. Besides, soap may be generated during the process also contaminates both biodiesel and glycerol phases.

Generally, there are three main approaches for biodiesel purification (Table 10.7) (Leung et al. 2010). The main purpose to perform this step is to wash out the residue catalyst, alcohol, free glycerol from crude biodiesel, and un-reacted raw oil, to make the product competent to ASTM or EN standards. In the case of biodiesel from homogeneous catalyzed reaction, extra chemical treatment is required to remove liquid catalyst. Chemicals (hydrochloric/sulfuric acids or CaO) are used for neur — tralization reaction of alkali or acid catalyst in order to remove the catalyst in the form of metal salts. Unlike homogenized purification step, solid catalyst can be easily removed via gravity separation without extra chemical treatment; the purified biodiesel was obtained from one of these alternative ways (wet wash, dry wash, or membrane extraction).

10.2 Conclusion

Nowadays, the price of biodiesel is still rather high, compared to petrodiesel fuel. The conventional technology used in biodiesel production for industrial scale is based on the transesterification of refined feedstock with methanol using basic homogeneous catalysts. This technology may cause problems in extra purification steps to remove liquid catalyst from the product. Hence, this issue has stimulated the transformation of homogeneous catalyzed reaction to heterogeneous system for economy feasible production cost and better biodiesel quality. From the commercial point of view, solid base catalysts are more effective than acid catalysts and enzymes. The transesterification activity of heterogeneous base-catalyzed reaction is more reactive than the solid acid catalyst in terms of lower reaction temperature, shorted reaction time, and smaller catalyst amount. Besides, some of the solid base catalysts possess similar or better reactivity than homogeneous base catalyst. To develop an

ideal heterogeneous base catalyst with high transesterification activity, the catalyst system should have high surface area with large porous system together with high basicity and strong basic strength on the active sites. The large porous system of catalyst is essential for reaction between large triglyceride molecules with long alkyl chain to avoid diffusion problems. The presence of strong basic active sites enables the reaction to begin and to proceed at an acceptable rate by forming the methoxide anion from the reaction between methanol and basic site of the catalyst. Furthermore, a catalyst with hydrophobic surface is important to improve the adsorption of feedstock with hydrophobic characteristic on the catalyst surface and to prevent the deactivation of catalytic sites by the strong adsorption of polar by­products such as water and glycerol. Although the catalysts presented above seem to be good candidates for biodiesel production, some of these catalysts are not pass­ing through a truly heterogeneous pathway. Great research efforts are still under way to develop the right catalyst with several requirements, i. e., tolerate to high FFA oil, catalyzed esterification and transesterification simultaneously, resistant to cata­lyst poisoning and leach resistant of catalyst active components, active in mild reac­tion condition, and high conversion and selectivity of product. Other than catalyst, selecting of suitable biodiesel feedstock is crucial to achieve the objectives: (1) lower price feedstock to reduce the production costs and (2) to avoid the pressure on the demand of food purpose.

The effect of reaction time on the extent of transesterification reaction was studied for 0-24-h time with immobilized lipase, and the results are shown in Fig. 12.7f. Other reaction parameters remained the same as mentioned in the optimization baseline. A 50% biodiesel yield was obtained at the end of 12 h of reaction time. Complete conversion and 100% yield of ethyl esters were obtained at the end of 24-h reaction time.

In literature, a conversion of 96% of ethyl esters was reported using the same enzyme with a reaction time of 48 h (Hsu et al. 2004). A 71% conversion in 8 h was reported by using ethanol and immobilized Chromobacterium viscosum lipase (Shah et al. 2004a, b). The reaction time mentioned in this study of 24 h can be reduced if we could produce immobilized enzyme with smaller size or increase the mixing intensity.

12.7 Conclusion

Production of biodiesel by chemical catalysts has the disadvantages that the process is energy consuming, requires water treatment, difficulty in recovery of glycerol, and formation of many unwanted products. On the other hand, enzymatic trans­esterification omits these difficulties and can obtain high purity biodiesel at milder working conditions. In order to be economical, the enzyme can be immobilized in some natural matrices, thus cutting down the production cost by reusing the immo­bilized lipase.

Immobilization of lipases is gaining importance due to a broad variety of indus­trial applications they catalyze. In this study, lipase from B. cepacia was first cross — linked with glutaraldehyde followed by entrapment into hybrid matrix of alginate and к-carrageenan polymers. The effect of various parameters like pH, temperature, reusability, enzyme leakage, solvent, and storage stability on immobilized lipase was studied. A higher activity yield of 89.26% was observed after immobilization. The immobilized lipase also retained 84.02% of its initial activity following two weeks of storage in T/Ca buffer at 4°C. Comparative kinetic parameters K and V

m max

values were found to be 0.39 |rM and 10 |rmol/min for free lipase and 0.45 |rM and 9.09 |rmol/min for immobilized lipase, respectively. A significant enzyme leakage reduction of 65.76% was observed as compared to the enzyme immobilized in hybrid matrix without cross-linking. The immobilized lipase also gave better results for hydrolysis of olive oil. Reduced enzyme leakage, higher thermal stability, and better storage stability were the salient features achieved by this method of enzyme immobilization. By this work, an improved entrapment approach of lipase cross­linking followed by entrapment onto a hybrid matrix of alginate and к-carrageenan was studied. This enhanced cross-linked matrix is a step closer in design of a better immobilized lipase for the biofuel industry.

Biodiesel optimization using the immobilized lipase was carried out for J. curcas oil in a stirred tank reactor. The optimal conditions for processing 10 g of Jatropha oil were 35°C, 1:10 molar ratio of oil to ethanol; 1 g water; 5.25 g immobilized lipase; 200 rotations per minute; and 24-h reaction time. At the above-mentioned optimal conditions, 100% yield of biodiesel was obtained. This shows that cross — linked B. cepacia lipase entrapped in a matrix of alginate and k-carrageenan could be a promising biocatalyst in the biofuel industry.

Acknowledgments We would like to acknowledge the Ministry of Science, Technology and Innovation (MOSTI) for the financial support through FRGS Grant (FGRG0244-TK-1/2010).