Esterification of succinic acid with oleyl alcohol catalyzed by immobilized Candida antarctica lipase B (Novozym 435) was investigated in this study. Response surface methodology (RSM) based on a five-level, four-variable central composite design (CCD) was used to model and analyze the reaction. A total of 21 experiments representing different combinations of the four parameters including temperature (35-65°C), time (30-450 min), enzyme amount (20-400 mg), and alcohol:acid molar ratio (1:1-8:1) were generated. A partial cubic equation could accurately model the response surface with a R(2) of 0.9853. The effect and interactions of the variables on the ester synthesis were also studied. Temperature was found to be the most significant parameter that influenced the succinate ester synthesis. At the optimal conditions of 41.1°C, 272.8 min, 20 mg enzyme amount and 7.8:1 alcohol:acid molar ratio, the esterification percentage was 85.0%. The model can present a rapid means for estimating the conversion yield of succinate ester within the selected ranges.
In order to characterize enzyme activity and stability corresponding to temperature effects, thermodynamic studies on commercial immobilized lipase have been carried out via enzymatic transesterification. An optimum temperature of 40 degrees C was obtained in the reaction. The decreasing reaction rates beyond the optimum temperature indicated the occurrence of reversible enzyme deactivation. Thermodynamic studies on lipase denaturation exhibited a first-order kinetics pattern, with considerable stability through time shown by the lipase as well. The activation and deactivation energies were 22.15 kJ mol(-1) and 45.18 kJ mol(-1), respectively, implying more energy was required for the irreversible denaturation of the enzyme to occur. At water content of 0.42%, the initial reaction rate and FAME yield displayed optimum values of 3.317 g/L min and 98%, respectively.
In this study, methyl ester (ME) was produced by transesterification of palm oil (CPO) (cooking grade) using activated carbon supported calcium oxide as a solid base catalyst (CaO/AC). Response surface methodology (RSM) based on central composite design (CCD) was used to optimize the effect of reaction time, molar ratio of methanol to oil, reaction temperature and catalyst amount on the transesterification process. The optimum condition for CPO transesterification to methyl ester was obtained at 5.5 wt.% catalyst amount, 190°C temperature, 15:1 methanol to oil molar ratio and 1 h 21 min reaction time. At the optimum condition, the ME content was 80.98%, which is well within the predicted value of the model. Catalyst regeneration studies indicate that the catalyst performance is sustained after two cycles.
Biodiesel (fatty acids alkyl esters) is a promising alternative fuel to replace petroleum-based diesel that is obtained from renewable sources such as vegetable oil, animal fat and waste cooking oil. Vegetable oils are more suitable source for biodiesel production compared to animal fats and waste cooking since they are renewable in nature. However, there is a concern that biodiesel production from vegetable oil would disturb the food market. Oil from Jatropha curcas is an acceptable choice for biodiesel production because it is non-edible and can be easily grown in a harsh environment. Moreover, alkyl esters of jatropha oil meet the standard of biodiesel in many countries. Thus, the present paper provides a review on the transesterification methods for biodiesel production using jatropha oil as feedstock.
Aquaculture activity has increased the population of crab, hence increasing the generation of related wastes, particularly the shell. In addition, the number of molting process in crabs compounds further the amount of waste shell generated. As such, in the present work, the application of the waste crab shell as a source of CaO in transesterification of palm olein to biodiesel (methyl ester) was investigated. Preliminary XRD results revealed that thermally activated crab shell contains mainly CaO. Parametric study has been investigated and optimal conditions were found to be methanol/oil mass ratio, 0.5:1; catalyst amount, 4 wt. %; and reaction temperature, 338 K. As compared to laboratory CaO, the catalyst from waste crab shell performs well, thus creating another low-cost catalyst source for producing biodiesel as well as adding value to the waste crab shell. Reusability of crab shell CaO has also been studied and the outcome confirmed that the catalyst is capable to be reutilized up to 11 times, without any major deterioration.
Response surface methodology (RSM) was carried out to study the effect of temperature, pH, and heating time as input variables on the yield and degree of esterification (DE) as the output (responses). The results showed that yield and DE of extracted pectin ranged from 2.27% to 9.35% (w/w, based on dry weight of durian rind) and 47.66% to 68.6%, respectively. The results also showed that a 2nd-order model adequately fitted the experimental data for the yield and DE. Optimum condition for maximum yield and DE was achieved at 85 degrees C, a time of either 4 or 1 h, and a pH of 2 or 2.5.
Diacylglycerol (DAG) and triacylglycerol (TAG) as responses on optimization of DAG production using a dual response approach of response surface methodology were investigated. This approach takes the molecular equilibrium of DAG into account and allows for the optimization of reaction conditions to achieve maximum DAG and minimum TAG yields. The esterification reaction was optimized with four factors using a central composite rotatable design. The following optimized conditions yielded 48 wt % DAG and 14 wt % TAG: reaction temperature of 66.29 degrees C, enzyme dosage of 4 wt %, fatty acid/glycerol molar ratio of 2.14, and reaction time of 4.14 h. Similar results were achieved when the process was scaled up to a 10 kg production in a pilot packed-bed enzyme reactor. Lipozyme RM IM did not show any significant activity losses or changes in fatty acid selectivity on DAG synthesis during the 10 pilot productions. However, lipozyme RM IM displayed higher selectivity toward the production of oleic acid-enriched DAG. The purity of DAG oil after purification was 92 wt %.
An industrial grade acidic crude palm oil (ACPO) pre-treatment process was carried out using ethanesulfonic acid (ESA) as a catalyst in the esterification reaction. ESA was used in different dosages to reduce free fatty acid (FFA) to a minimum level for the second stage of biodiesel production via alkaline transesterification reaction. Different process operating conditions were optimized such as ESA dosage (0.25-3.5% wt/wt), methanol to ACPO molar ratio (1:1-20:1), reaction temperature (40-70 °C), and reaction time (3-150 min). This study revealed the potential use of abundant quantities of ACPO from oil palm mills for biodiesel production. The lab scale results showed the effectiveness of the pre-treatment process using ESA catalyst. Three consecutive catalyst recycling runs were achieved without significant degradation in its performance. Second and third reuse runs needed more reaction time to achieve the target level of FFA content. Esterification and transesterification using ESA and KOH respectively is proposed for biodiesel industrial scale production. The produced biodiesel meets the international standards specifications for biodiesel fuel (EN 14214 and ASTM D6751).
Lipase from Candida rugosa was immobilized by entrapment on poly(N-vinyl- 2-pyrrolidone-co-2-hydroxyethyl methacrylate) (poly[VP-co-HEMA]) hydrogel, and divinylbenzene was the crosslinking agent. The immobilized enzymes were used in the esterification reaction of oleic acid and butanol in hexane. The activities of the immobilized enzymes and the leaching ability of the enzyme from the support with respect to the different compositions of the hydrogels were investigated. The thermal, solvent, and storage stability of the immobilized lipases was also determined. Increasing the percentage of composition of VP from 0 to 90, which corresponds to the increase in the hydrophilicity of the hydrogels, increased the activity of the immobilized enzyme. Lipase immobilized on VP(%):HEMA(%) 90:10 exhibited the highest activity. Lipase immobilized on VP(%):HEMA(%) 50:50 showed the highest thermal, solvent, storage, and operational stability compared to lipase immobilized on other compositions of hydrogels as well as the native lipase.
Synthesis of layered double hydroxides (LDHs) of Zn/Al-NO3- hydrotalcite (HIZAN) and Zn/Al-diocytyl sodium sulfosuccinate (DSS) nanocomposite (NAZAD) with a molar ratio of Zn/Al of 4:1 were carried out by coprecipitation through continuous agitation. Their structures were determined using X-ray diffractometer spectra, which showed that basal spacing for LDH synthesized by both methods was about 8.89 A. An expansion of layered structure of about 27.9 A was observed to accommodate the surfactant anion between the interlayer. This phenomenon showed that the intercalation process took place between the LDH interlayer. Lipase from Candida rugosa was immobilized onto these materials by physical adsorption method. It was found that the protein loading onto NAZAD is higher than HIZAN. The activity of immobilized lipase was investigated through esterification of oleic acid and 1-butanol in hexane. The effects of pore size, surface area, reaction temperature, thermostability of the immobilized lipases, storage stability in organic solvent, and leaching studies were investigated. Stability was found to be the highest in the nanocomposite NAZAD.
In this study, biodiesel was produced from sludge palm oil (SPO) using tolune-4-sulfonic monohydrate acid (PTSA) as an acid catalyst in different dosages in the presence of methanol to convert free fatty acid (FFA) to fatty acid methyl ester (FAME), followed by a transesterification process using an alkaline catalyst. In the first step, acid catalyzed esterification reduced the high FFA content of SPO to less than 2% with the different dosages of PTSA. The optimum conditions for pretreatment process by esterification were 0.75% (w/w) dosage of PTSA to SPO, 10:1 M ratio, 60 °C temperature, 60 min reaction time and 400 rpm stirrer speed. The highest yield of biodiesel after transesterification and purification processes was 76.62% with 0.07% FFA and 96% ester content. The biodiesel produced was favorable as compared to EN 14214 and ASTM 6751 standard. This study shows a potential exploitation of SPO as a new feedstock for the production of biodiesel.
The fuel crisis and environmental concerns, mainly due to global warming, have led researchers to consider the importance of biofuels such as biodiesel. Vegetable oils, which are too viscous to be used directly in engines, are converted into their corresponding methyl or ethyl esters by a process called transesterification. With the recent debates on "food versus fuel," non-edible oils, such as Jatropha curcas, are emerging as one of the main contenders for biodiesel production. Much research is still needed to explore and realize the full potential of a green fuel from J. curcas. Upcoming projects and plantations of Jatropha in countries such as India, Malaysia, and Indonesia suggest a promising future for this plant as a potential biodiesel feedstock. Many of the drawbacks associated with chemical catalysts can be overcome by using lipases for enzymatic transesterification. The high cost of lipases can be overcome, to a certain extent, by immobilization techniques. This article reviews the importance of the J. curcas plant and describes existing research conducted on Jatropha biodiesel production. The article highlights areas where further research is required and relevance of designing an immobilized lipase for biodiesel production is discussed.
Agro-waste from the bark of Metroxylon sagu (sago) was studied as a low cost and effective oil sorbent in dry and aqueous environments. Sorption study was conducted using untreated sago bark (SB) and esterified sago bark (ESB) in used engine oil. Characterization study showed that esterification has successfully improved the hydrophobicity, buoyancy, surface roughness and oil sorption capacity of ESB. Sorption study revealed that water uptake of SB is higher (30 min static: 2.46 g/g, dynamic: 2.67 g/g) compared with ESB (30 min static: 0.18 g/g, dynamic: 0.14 g/g). ESB, however, showed higher oil sorption capacity in aqueous environment (30 min static: 2.30 g/g, dynamic: 2.14) compared with SB (30 min static: 0 g/g, dynamic: 0 g/g). ESB has shown great poTENTial as effective oil sorbent in aqueous environment due to its high oil sorption capacity, low water uptake and high buoyancy.
Hermetia illucens larvae by nature are a decomposer which fed on organic wastes. This study explores the potential of producing biodiesel using lipids from H. illucens larvae. Three types of organic wastes (sewage sludge, fruit waste and palm decanter cake from oil palm mill) were selected based on considerable generation and disposal concern in the area of study as well as lack of investigations as feed for Hermetia illucens larvae in current literatures. Growth rate of the larvae was determined with studying the changes in the biomass per day. H. illucens larvae fed with fruit waste and palm decanter cake have shown growth rates of 0.52±0.02 and 0.23±0.09 g d(-1), respectively. No positive sign of growth were observed in the larvae fed with treated sewage sludge (-0.04±0.01 g d(-1)). Biodiesel as fatty acid methyl ester (FAME) was synthesized by transesterification of the larvae lipid using sulphuric acid as catalyst in methanol. FAME produced was ascertained using ATR-FTIR spectroscopy and GC-MS. The main compositions of fatty acid were found to be C12:0, C16:0 and C18:1n9c. Fatty acid composition of C12:0 fed with fruit waste, sewage sludge and palm decanter was found to be most abundant in the larvae lipid. The amount of C12:0 obtained was 76.13%, 58.31% and 48.06%, respectively. In addition, fatty acid of C16:0 was attained at 16.48% and 25.48% fed with sewage sludge and palm decanter, respectively. Based on the findings, FAME derived from larvae lipids is feasible to be used for biodiesel production.
Biodiesel is a green (clean), renewable energy source and is an alternative for diesel fuel. Biodiesel can be produced from vegetable oil, animal fat and waste cooking oil or fat. Fats and oils react with alcohol to produce methyl ester, which is generally known as biodiesel. Because vegetable oil and animal fat wastes are cheaper, the tendency to produce biodiesel from these materials is increasing. In this research, the effect of some parameters such as the alcohol-to-oil molar ratio (4:1, 6:1, 8:1), the catalyst concentration (0.75%, 1% and 1.25% w/w) and the time for the transesterification reaction using ultrasonication on the rate of the fatty acids-to-methyl ester (biodiesel) conversion percentage have been studied (3, 6 and 9 min). In biodiesel production from chicken fat, when increasing the catalyst concentration up to 1%, the oil-to-biodiesel conversion percentage was first increased and then decreased. Upon increasing the molar ratio from 4:1 to 6:1 and then to 8:1, the oil-to-biodiesel conversion percentage increased by 21.9% and then 22.8%, respectively. The optimal point is determined by response surface methodology (RSM) and genetic algorithms (GAs). The biodiesel production from chicken fat by ultrasonic waves with a 1% w/w catalyst percentage, 7:1 alcohol-to-oil molar ratio and 9 min reaction time was equal to 94.8%. For biodiesel that was produced by ultrasonic waves under a similar conversion percentage condition compared to the conventional method, the reaction time was decreased by approximately 87.5%. The time reduction for the ultrasonic method compared to the conventional method makes the ultrasonic method superior.
New polyurethane (PU) nanocomposites were prepared from a dispersion of 0 - 5% montmorillonite (MMT) clay with isocyanate and soya oil polyol that was synthesized via transesterification of triglycerides to reduce petroleum dependence. FT-IR spectra indicate the presence of hydrogen bonding between nanoclay and the polymer matrix, whereas the exfoliated structure of clay layers was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Optical microscopy, mechanical and thermal analyses were done to investigate significant improvement of the nanocomposites. The results showed PU-3% nanoclay (NC) showed optimum results in mechanical properties such as tensile and flexural strength but the lowest in impact strength.
Pinto bean pod polysaccharide (PBPP) was successfully extracted with yield of 38.5g/100g and the PBPP gave total carbohydrate and uronic acid contents of 286.2mg maltose equivalent/g and 374.3mgGal/g, respectively. The Mw of PBPP was 270.6kDa with intrinsic viscosity of 0.262dm(3)/g, which composed of mannose (2.5%), galacturonic acid (15.0%), rhamnose (4.0%), glucose (9.0%), galactose (62.2%), xylose (2.9%) and arabinose (4.3%) with trace amount of ribose and fucose. The result suggested that PBPP has a spherical conformation with a highly branched structure. Fourier Transform Infrared analysis showed that PBPP has a similar structure as commercial pectin with an esterification degree of 59.9%, whereas scanning electron microscopy study showed that the crude polysaccharide formed a thin layer of film that was made of multiple micro strands of fibre. PBPP exhibited substantial free radical scavenging activity (7.7%), metal reducing capability (2.04mmol/dm(3)) and α-amylase inhibitory activity (97.6%) at a total amount of 1mg. PBPP also exhibited high water- and oil-holding capacities (3.6g/g and 2.8g/g, respectively). At a low concentration, PBPP exhibited emulsifying activity of 39.6% with stability of 38.6%. Apart from that, PBPP was able to show thickening capability at low concentration (0.005kg/dm(3)).
Functional polysaccharide was isolated from Momordica charantia, with a yield of 36% (w/w). M. charantia bioactive polysaccharide (MCBP) was an acidic and branched heteropolysaccharide with a molecular weight of 92 kDa. Fourier transform infrared spectroscopic analysis indicated that MCBP was a pectin-like polysaccharide with an esterification degree of 53% and it contains numerous monosaccharides, predominantly glucose, galactose, and galaturonic acid. The results also showed that MCBP exhibited free radical scavenging activity (31.9%), ferric reducing antioxidant power (0.95 mM), α-amylase inhibition (89.1%), and angiotensin-converting enzyme inhibition (94.1%). In the terms of functionality, MCBP showed a lower water-holding capacity but higher in oil-holding capacity, emulsifying activity and foaming capacity compared to citrus pectin. Scanning electron microscopy images demonstrated that MCBP formed gels with a porous structure, and flow analysis showed that the gel solution exhibited pseudoplastic shear-thinning behavior. These findings indicated that MCBP is a promising functional macromolecular carbohydrate for the food and nutraceutical industries.
Acylglycerols are widely used in the food industry due to their antimicrobial, emulsifying and nutritional properties. This study investigated the key reaction parameters, mass transfer mechanisms, and kinetic features of lipase-catalyzed esterification in a solvent-free system. Taguchi method was further employed to explore the relationship between "reaction parameter - yield composition". The results revealed that the maximum selectivity were achieved fror MAG (57.72 %), DAG (82.67 %) and TAG (79.29 %) under different enzymatic conditions. Fatty acid-to-glycerol molar ratio had the greatest impact on DAG selectivity, contributing 38.08 % of total impact level. Mass transfer analysis showed that external mass transfer limitation could be effectively overcome at stirring speeds above 600 rpm. Kinetic analysis confirmed that the reaction followed the Ping-Pong BiBi mechanism with alcohol and acid inhibition (SSE = 0.000643). This work provided a theoretical basis for developing more efficient and selective catalytic processes, aiding in quality control, reactor design, and industrial scale-up.
In this work, lipase from Candida rugosa was immobilized onto chitosan/graphene oxide beads. This was to provide an enzyme-immobilizing carrier with excellent enzyme immobilization activity for an enzyme group requiring hydrophilicity on the immobilizing carrier. In addition, this work involved a process for the preparation of an enzymatically active product insoluble in a reaction medium consisting of lauric acid and oleyl alcohol as reactants and hexane as a solvent. This product enabled the stability of the enzyme under the working conditions and allowed the enzyme to be readily isolated from the support. In particular, this meant that an enzymatic reaction could be stopped by the simple mechanical separation of the "insoluble" enzyme from the reaction medium. Chitosan was incorporated with graphene oxide because the latter was able to enhance the physical strength of the chitosan beads by its superior mechanical integrity and low thermal conductivity. The X-ray diffraction pattern showed that the graphene oxide was successfully embedded within the structure of the chitosan. Further, the lipase incorporation on the beads was confirmed by a thermo-gravimetric analysis. The lipase immobilization on the beads involved the functionalization with coupling agents, N-hydroxysulfosuccinimide sodium (NHS) and 1-ethyl-(3-dimethylaminopropyl) carbodiimide (EDC), and it possessed a high enzyme activity of 64 U. The overall esterification conversion of the prepared product was 78% at 60 °C, and it attained conversions of 98% and 88% with commercially available lipozyme and novozyme, respectively, under similar experimental conditions.