Biodiesel fuel production by the transesterification reaction of soybean oil using immobilized lipase

The enzymatic alcoholysis of soybean oil with methanol and ethanol was investigated using a commercial, immobilized lipase (Lipozyme RMIM). The effect of alcohol (methanol or ethanol), enzyme concentration, molar ratio of alcohol to soybean oil, solvent, and temperature on biodiesel production was determined. The best conditions were obtained in a solvent-free system with ethanol/oil molar ratio of 3.0, temperature of 50 degrees C, and enzyme concentration of 7.0% (w/w). Three-step batch ethanolysis was most effective for the production of biodiesel. Ethyl esters yield was about 60% after 4 h of reaction.     

Improved Enzyme Stability in Lipase-Catalyzed Synthesis of Fatty Acid Ethyl Ester from Soybean Oil

In this work, we describe the optimization of the ethanolysis of soybean oil by the enzyme Lipozyme™ TL-IM in the lipase-catalyzed biodiesel synthesis and the improvement of the enzyme stability over repeated batches. The studied process variables were: reaction temperature, substrate molar ratio, enzyme content, and volume of added water. Fractional factorial design was used to analyze the variables so as to select those with higher influence on the reaction and then perform a central composite design to find the optimal reaction conditions. The optimal conditions found were: temperature, 26 °C; substrate molar ratio, 7.5:1 (ethanol/oil); enzyme content, 25% in relation to oil weight; and added water, 4% in relation to oil weight. Under these conditions, the yield conversion obtained was 69% in 12 h. The enzyme stability assessment in repeated batches was carried out by washing the immobilized enzyme with different solvents (n-hexane, water, ethanol, and propanol) after each batch. In the treatment with n-hexane, around 80% of the enzyme activity still remains after seven cycles of synthesis, suggesting its economical application on biodiesel production.     

A new green technology: hydrothermal electrolysis for the treatment of biodiesel wastewater

Recently, biodiesel has become more attractive as an alternative diesel fuel because it is renewable, biodegradable, non-toxic, and environmentally friendly. In this study, we have developed a new green process called ??hydrothermal electrolysis??, by which industrial wastewater can be converted to more value-added chemicals under high-temperature and high-pressure aqueous conditions. We prepared model biodiesel wastewater and carried out hydrothermal electrolysis experiments by using both a continuous flow reactor and a batch autoclave. Current efficiencies and the effects of reaction time and reaction temperature on the decomposition of biodiesel wastewater and removal of total organic carbon (TOC) were investigated under various operating conditions. It was found that conversions of both TOC and glycerol inside the model biodiesel wastewater increased with increasing applied current. With the autoclave, the maximum glycerol conversion was recorded as 83% by applying 1 A current at 250 °C, whereas with the flow reactor, 75% of glycerol was converted into gas and liquid products under the effect of 1 A current for 60 min at a reaction temperature of 280 °C. In the case of TOC removal from the liquid product solution, under identical conditions, it was found that 23 and 15.9% TOC conversions were achieved by the batch and continuous flow reactors, respectively.     

New eutectic ionic liquids for lipase activation and enzymatic preparation of biodiesel

The enzymatic preparation of biodiesel has been hampered by the lack of suitable solvents with desirable properties such as high lipase compatibility, low cost, low viscosity, high biodegradability, and ease of product separation. Recent interest in using ionic liquids (ILs) as advanced reaction media has led to fast reaction rates and high yields in the enzymatic synthesis of biodiesel. However, conventional (i.e., cation-anion paired) ILs based on imidazolium and other quaternary ammonium salts remain too expensive for wide application at industrial scales. In this study, we report on newly-synthesized eutectic ILs derived from choline acetate or choline chloride coupled with biocompatible hydrogen-bond donors, such as glycerol. These eutectic solvents have favorable properties including low viscosity, high biodegradability, and excellent compatibility with Novozym(?) 435, a commercial immobilized Candida antarctica lipase B. Furthermore, in a model biodiesel synthesis system, we demonstrate high reaction rates for the enzymatic transesterification of Miglyol(?) oil 812 with methanol, catalyzed by Novozym(?) 435 in choline acetate/glycerol (1:1.5 molar ratio). The high conversion (97%) of the triglyceride obtained within 3 h, under optimal conditions, suggests that these novel eutectic solvents warrant further exploration as potential media in the enzymatic production of biodiesel.     

Biodiesel Production from Various Oils Under Supercritical Fluid Conditions by Candida antartica Lipase B Using a Stepwise Reaction Method

In this study, we evaluate the effects of various reaction factors, including pressure, temperature, agitation speed, enzyme concentration, and water content to increase biodiesel production. In addition, biodiesel was produced from various oils to establish the optimal enzymatic process of biodiesel production. Optimal conditions were determined to be as follows: pressure 130 bar, temperature 45 °C, agitation speed 200 rpm, enzyme concentration 20%, and water contents 10%. Among the various oils used for production, olive oil showed the highest yield (65.18%) upon transesterification. However, when biodiesel was produced using a batch system, biodiesel conversion yield was not increased over 65%; therefore, a stepwise reaction was conducted to increase biodiesel production. When a reaction medium with an initial concentration of methanol of 60 mmol was used and adjusted to maintain this concentration of methanol every 1.5 h during biodiesel production, the conversion yield of biodiesel was 98.92% at 6 h. Finally, reusability was evaluated using immobilized lipase to determine if this method was applicable for industrial biodiesel production. When biodiesel was produced repeatedly, the conversion rate was maintained at over 85% after eight reuses.     

Synthesis of Biodiesel from Palm Oil in Capillary Millichannel Reactor: Effect of Temperature,Methanol to Oil Molar Ratio,and KOH Concentration on FAME Yield

Application of microtube reactor for the continuous synthesis of biodiesel has been widely studied due to excellent performance in liquid-liquid phase reaction. In order to commercialize biodiesel production, integration of microtube reactor is highly recommended. Therefore, in this study, synthesis of biodiesel was carried out in capillary millichannel reactor with inner diameter of 1.59 mm using methanol and potassium hydroxide (KOH) as base catalyst with palm oil as a feedstock. The influences of reaction temperature, methanol to oil molar ratio, and KOH concentration on the production of fatty acid methyl ester (FAME) were examined. The highest FAME yield was achieved at 60 ˚C with 23:1 methanol to oil molar ratio and 5 wt% of KOH concentration.     

Synthesis of Rapeseed Biodiesel Using Short-Chained Alkyl Acetates as Acyl Acceptor

In this study, we conducted experiments using a response surface methodology to determine the optimal reaction conditions for the enzymatic synthesis of biodiesel from rapeseed oil and short-chained alkyl acetates, such as methyl acetate or ethyl acetate, as the acyl acceptor at 40 °C. Based on our response surface methodology experiments, the optimal reaction conditions for the synthesis of biodiesel were as follows: methyl acetate as acyl acceptor, catalyst concentration of 16.50%, oil-to-methyl acetate molar ratio of 1:12.44, and reaction time of 19.70 h; ethyl acetate as acyl acceptor, catalyst concentration of 16.95%, oil-to-ethyl acetate molar ratio of 1:12.56, and reaction time of 19.73 h. The fatty acid ester content under the above conditions when methyl acetate and ethyl acetate were used as the acyl acceptor was 58.0% and 62.6%, respectively. The statistical method described in this study can be applied to effectively optimize the enzymatic conditions required for biodiesel production with short-chained alkyl acetates.     

Enzymatic Synthesis of Biodiesel via Alcoholysis of Palm Oil

The enzymatic alcoholysis of crude palm oil with methanol and ethanol was investigated using commercial immobilized lipases (Lipozyme RM IM, Lipozyme TL IM). The effect of alcohol (methanol or ethanol), molar ratio of alcohol to crude palm oil, and temperature on biodiesel production was determined. The best ethyl ester yield was about 25 wt.% and was obtained with ethanol/oil molar ratio of 3.0, temperature of 50 °C, enzyme concentration of 3.0 wt.%, and stepwise addition of the alcohol after 4 h of reaction. Experiments with 1 and 3 wt.% of KOH and 3 wt.% of MgO were carried out to compare their catalytic behavior with the enzymatic transesterification results. The commercial immobilized lipase, Lipozyme TL IM, showed the best catalytic performance.     

Transesterification of Waste Frying Oil and Soybean Oil by <Emphasis Type="Italic">Combi</Emphasis>-<Emphasis Type="Italic">lipases</Emphasis> Under Ultrasound-Assisted Reactions

This work describes the use of an ultrasound system for the enzymatic transesterification of oils using combi-lipases as biocatalyst. The reactions were carried out evaluating the individual use of waste oil and fresh soybean oil, and the immobilized lipases CALB, TLL, and RML were used as biocatalysts. It was performed in a mixture design of three factors to obtain the ideal mixture of lipases according to the composition of fatty acids present in each oil, and the main reaction variables were optimized. After 18 h of reaction, ultrasound provided a biodiesel yield of about 90% when using soybean oil and 70% using the waste oil. The results showed that ultrasound technology, in combination with the application of enzyme mixtures, known as combi-lipases, and the use of waste oil, could be a promising route to reduce the overall process costs of enzymatic production of biodiesel.     

亚/超临界乙醇液化秸秆纤维素解聚反应研究与机理初探

利用间歇式高压反应釜,在反应温度200～330 ℃、乙醇用量0～150 mL条件下,考察了亚/超临界乙醇直接液化秸秆纤维素的解聚行为,并初步探讨了其液化机理。结果表明,反应温度、乙醇用量和反应停留时间对秸秆纤维素的液化均有显著影响,反应温度由200 ℃升高至330 ℃,重油和气体收率分别增加了12.55%、28.83%;乙醇用量增加,反应压力随之升高,乙醇进入超临界状态,残渣和气体收率相比单纯热裂解分别降低11.10%和8.44%。通过GC/MS、FT-IR分析生物油组分和残渣特性,表明秸秆纤维素在亚/超临界乙醇中断键裂解,且酮类和乙酯类化合物是生物油的主要成分。     

Kinetic study of a complex triangular reaction system in alkaline aqueous-ethanol medium using on-line transmission FTIR spectroscopy and BTEM analysis

The kinetics of the base-catalyzed reaction of methyl 4-hydroxybenzoate in aqueous-ethanol solvent medium was studied and analyzed via combined on-line transmission FTIR spectroscopy and Band-Target Entropy Minimization (BTEM) technique. This reaction is considered complex since it involves simultaneous hydrolysis and ethanolysis reactions of methyl 4-hydrozybenzoate (MP) to form ethyl 4-hydroxybenzoate (EP) as an intermediate and sodium 4-hydroxybenzoate as a final product. The pure component spectra of the reactive species involved in the reaction were reconstructed using BTEM technique. Their corresponding real concentrations were calculated and subsequently used for analyzing the kinetics of this triangular reaction system. The effects of temperature and solvent mixture compositions were studied. In general, the results show that the rates of both hydrolysis and ethanolysis reactions increase with temperature. Addition of ethanol to the solvent mixture also reduces the rates of the hydrolysis reactions. The effect of solvent mixture on the rate of ethanolysis reaction is more complex and influenced by at least two competing factors, namely the concentration of ethoxide ion in the solution and the stabilization effect on the reactant. The enthalpy and entropy activation parameters, ΔH^‡ and ΔS^‡, of both the hydrolysis and ethanolysis reactions were determined using the Eyring equation and the activation parameters confirm the associative nature in the elementary steps in these reactions. Finally, it is shown that the dominant synthetic pathway in this triangular system changes from direct hydrolysis of methyl 4-hydrozybenzoate to the indirect pathway via ethanolysis and then hydrolysis depending on the solvent mixture composition.     

Heterogeneous catalytic synthesis of ethanol from biomass-derived syngas

The selective catalytic conversion of biomass-derived syngas into ethanol is thermodynamically feasible at temperatures below roughly 350 degrees C at 30 bar. However, if methane is allowed as a reaction product, the conversion to ethanol (or other oxygenates) is extremely limited. Experimental results show that high selectivities to ethanol are only achieved at very low conversions, typically less than 10%. The most promising catalysts for the synthesis of ethanol are based on Rh, though some other formulations (such as modified methanol synthesis catalysts) show promise.     

酸化油固定床酶法合成生物柴油研究

酸化油是油脂工作中以皂脚、油脚经酸化处理得到的产品.它的主要成份是游离脂肪酸及中性油,是生产脂肪酸的重要原料,但生产过程中有水解废水的产生,若将其直接排放,既污染了环境又浪费了资源.     

Organic Phase Synthesis of Ethyl Oleate Using Lipases Produced by Solid-state Fermentation

This paper reports a study of the enzymatic esterification of oleic acid and ethanol. The reaction was catalyzed by lipases produced by solid-state fermentation with Rhizopus sp. Olive oil and perlite were used as an inducer and inert support, respectively. Synthesis of ethyl oleate was carried out in a 10-mL batch reactor with magnetic stirring. The effects of substrate ratios, biocatalyst concentration, and temperature on the reaction rate and conversion efficiency were evaluated. The highest reaction rate (1.64 mmol/L min) was reached with an oleic acid/ethanol mol ratio of 1:5 (oleic acid 50 mM:ethanol 250 mM) and 1 g of biocatalyst. Conversions approaching 100% were obtained after 60 min of reaction at 45 degrees C with n-hexane as a solvent. The initial reaction rate increased proportionally with respect to biocatalyst concentration, which suggests that the reaction rate was not controlled by mass transfer. The biocatalyst retained more than 80% of its catalytic activity after 7 months of storage at 4 degrees C. The results demonstrate that the biocatalyst produced by Rhizopus sp. in solid-state fermentation can be successfully used for ethyl oleate synthesis over short reaction periods under conditions when ethanol is in excess.     

Enzymatic conversion of waste cooking oils into alternative fuel—Biodiesel

Production of biodiesel from pure oils through chemical conversion may not be applicable to waste oils/fats. Therefore, enzymatic conversion using immobilized lipase based on Rhizopus orzyae is considered in this article. This article studies this technological process, focusing on optimization of several process parameters, including the molar ratio of methanol to waste oils, biocatalyst load, and adding method, reaction temperature, and water content. The results indicate that methanol/oils ratio of 4, immobilized lipase/oils of 30 wt% and 40°C are suitable for waste oils under 1 atm. The irreversible inactivation of the lipase is presumed, and a stepwise addition of methanol to reduce inactivation of immobilized lipases is proposed. Under the optimum conditions the yield of methyl esters is around 88–90%.     

Evaluation of the catalytic effect of ZnO as a secondary phase in the Ni0.5Zn0.5Fe2O4 system and of the stirring mechanism on biodiesel production reaction

In search of efficient ways to produce biodiesel under environmentally friendly conditions, catalytic reactions have been explored with emphasis on replacing homogeneous by heterogeneous catalysis with the use of new catalyst types, such as the spinel ferrites, which are described as a viable option, since they are stable, highly active, inexpensive, reusable, and allow the easy recovery of the reaction medium through the application of magnetic fields. In this context, the present work proposes to contribute to the consolidation of the catalytic viability of the Ni_0.5Zn_0.5Fe₂O₄ system obtained by combustion reaction, because although previous studies indicate the catalytic effectiveness of this system in polyphasic form, the present work seeks as differential to evaluate the influence of the secondary phases and magnetization of the Ni-Zn system in the conversion to biodiesel, and for this purpose, it aims to evaluate the catalytic effect of ZnO formed as secondary phase and obtained concomitantly in the Ni-Zn ferrite synthesis, besides evaluating the effect of the stirring mechanism used in biodiesel production reaction by the ethyl transesterification of soybean oil. The synthesized Ni-Zn ferrites and ZnO sample were characterized by X-ray diffraction (XRD), nitrogen adsorption textural analysis (BET), particle size distribution, and then, tested in two reactor types, one with magnetic stirring, and another of mechanical stirring, to observe the magnetization effect of the material, and the characterization of the obtained biodiesels by gas chromatography (GC) and acidity index. The performed catalytic tests showed that the Ni-Zn ferrites promoted excellent ester conversions with values near and above 94%, thus confirming that although ZnO also promotes good ester conversion (83.9%), the catalytic effectiveness of the Ni-Zn ferrite is evident and independent of secondary phases. Moreover, the catalytic tests performed in the magnetic stirring reactor using the Ni-Zn ferrites as catalysts made it possible to realize that their magnetic properties may be interference in the catalytic effectiveness, being this, a more determining factor than the surface characteristics.     

Optimization of Biodiesel Production from Castor Oil Using Response Surface Methodology

The short supply of edible vegetable oils is the limiting factor in the progression of biodiesel technology; thus, in this study, we applied response surface methodology in order to optimize the reaction factors for biodiesel synthesis from inedible castor oil. Specifically, we evaluated the effects of multiple parameters and their reciprocal interactions using a five-level three-factor design. In a total of 20 individual experiments, we optimized the reaction temperature, oil-to-methanol molar ratio, and quantity of catalyst. Our model equation predicted that the following conditions would generate the maximum quantity of castor biodiesel (92 wt.%): a 40-min reaction at 35.5 °C, with an oil-to-methanol molar ratio of 1:8.24, and a catalyst concentration of 1.45% of KOH by weight of castor oil. Subsequent empirical analyses of the biodiesel generated under the predicted conditions showed that the model equation accurately predicted castor biodiesel yields within the tested ranges. The biodiesel produced from castor oil satisfied the relevant quality standards without regard to viscosity and cold filter plugging point.     

Real‐Time Monitoring of Mass‐Transport‐Related Enzymatic Reaction Kinetics in a Nanochannel‐Array Reactor

To understand the fundamentals of enzymatic reactions confined in micro‐/nanosystems, the construction of a small enzyme reactor coupled with an integrated real‐time detection system for monitoring the kinetic information is a significant challenge. Nano‐enzyme array reactors were fabricated by covalently linking enzymes to the inner channels of a porous anodic alumina (PAA) membrane. The mechanical stability of this nanodevice enables us to integrate an electrochemical detector for the real‐time monitoring of the formation of the enzyme reaction product by sputtering a thin Pt film on one side of the PAA membrane. Because the enzymatic reaction is confined in a limited nanospace, the mass transport of the substrate would influence the reaction kinetics considerably. Therefore, the oxidation of glucose by dissolved oxygen catalyzed by immobilized glucose oxidase was used as a model to investigate the mass‐transport‐related enzymatic reaction kinetics in confined nanospaces. The activity and stability of the enzyme immobilized in the nanochannels was enhanced. In this nano‐enzyme reactor, the enzymatic reaction was controlled by mass transport if the flux was low. With an increase in the flux (e.g., >50 μL min^?1), the enzymatic reaction kinetics became the rate‐determining step. This change resulted in the decrease in the conversion efficiency of the nano‐enzyme reactor and the apparent Michaelis–Menten constant with an increase in substrate flux. This nanodevice integrated with an electrochemical detector could help to understand the fundamentals of enzymatic reactions confined in nanospaces and provide a platform for the design of highly efficient enzyme reactors. In addition, we believe that such nanodevices will find widespread applications in biosensing, drug screening, and biochemical synthesis.     

The effect of particle size on hydrolysis reaction rates and rheological properties in cellulosic slurries

The effect of varying initial particle sizes on enzymatic hydrolysis rates and rheological properties of sawdust slurries is investigated. Slurries with four particle size ranges (33 microm < x < or = 75 microm, 150 microm < x < or = 180 microm, 295 microm < x < or = 425 microm, and 590 microm < x < or = 850 microm) were subjected to enzymatic hydrolysis using an enzyme dosage of 15 filter paper units per gram of cellulose at 50 degrees C and 250 rpm in shaker flasks. At lower initial particle sizes, higher enzymatic reaction rates and conversions of cellulose to glucose were observed. After 72 h 50 and 55% more glucose was produced from the smallest size particles than the largest size ones, for initial solids concentration of 10 and 13% (w/w), respectively. The effect of initial particle size on viscosity over a range of shear was also investigated. For equivalent initial solids concentration, smaller particle sizes result in lower viscosities such that at a concentration of 10% (w/w), the viscosity decreased from 3000 cP for 150 microm < x < or = 180 microm particle size slurries to 61.4 cP for 33 microm < x < or = 75 microm particle size slurries. Results indicate particle size reduction may provide a means for reducing the long residence time required for the enzymatic hydrolysis step in the conversion of biomass to ethanol. Furthermore, the corresponding reduction in viscosity may allow for higher solids loading and reduced reactor sizes during large-scale processing.     

Thermal decomposition of perfluoroalkanesulfonyl fluorides: The pyrolysis of perfluoro-n-octane-1-sulfonyl fluoride

The preliminary data obtained from thermal decompositions of perfluoro-n-octane-1-sulfonyl fluoride in a continuous tubular-flow reactor are reported. The pyrolysis results in a radical reaction producing fluorocarbons, with high conversions and with yields depending on the experimental conditions. The reaction mixture composition also depends on the experimental conditions, so it is possible to obtain a prevalent formation of either light or heavy fluorocarbons.