Biodiesel Production Yield Research Articles

Using wet microalgae for direct biodiesel production via microwave irradiation

To address the large energy consumption of microalgae dewatering and to simplify the conventional two-step method (cellular lipid extraction and lipid transesterification) for biodiesel production, a novel process for the direct conversion of wet microalgae biomass into biodiesel by microwave irradiation is proposed. The influences of conventional thermal heating and microwave irradiation on biodiesel production from wet microalgae biomass were investigated. The effects of using the one-step (simultaneous lipid extraction and transesterification) and two-step methods were also studied. Approximately 77.5% of the wet microalgal cell walls were disrupted under microwave irradiation. The biodiesel production rate and yield from wet microalgae biomass obtained through the one-step process using microwave irradiation were 6-fold and 1.3-fold higher than those from wet microalgae obtained through the two-step process using conventional heating.

Reactive Extraction of Jatropha Seed for Biodiesel Production: Effect of Moisture Content of Jatropha Seed and Co-solvent Concentration

Biodiesel is one among the promising renewable fuels, holding various advantages compared with fossil fuel. In this study, reactive extraction of jatropha seed for biodiesel production was investigated. The effect of moisture content of jatropha seeds and cosolvent concentration was examined to determine the best performance of the biodiesel production yield. The co-solvent used is hexane. Design of experiments (DOE) was used to study the effect of moisture content of jatropha seed and co-solvent of hexane concentration on the yield of biodiesel. Generally, the moisture content of jatropha seeds and co-solvent concentration affected biodiesel production yield. The experimental result also shows that the transesterification rate was improved when compared to the system without co-solvents. It was found that the production of biodiesel achieved an optimum level of 68.3% biodiesel yield at the following reaction conditions, i.e. moisture content of jatropha seed of 1% and hexane to oil ratio of 6.9 (w/w).

Molecular Cloning and Heterologous Expression of a True Lipase in Pichia pastoris Isolated via a Metagenomic Approach

Lipases are important enzymes for various biotechnological applications. By using functional expression screening, lipZ03, a novel lipase gene, was isolated from a soil-derived metagenomic library. The gene was supposed to encode a protein of 617 amino acids with a C-terminal targeting signal region and four potential N-linked glycosylation sites. The protein sequence shared a conserved GXSXG motif (X represents any amino acid residue) with other microbial lipases. Gene lipZ03 was expressed in Pichia pastoris and the molecular weight was estimated to be approximately 65 kDa by electrophoresis. The optimum reaction temperature and pH value for LipZ03 was 50°C and 9.0, respectively. The enzyme was highly stable in the temperature range of 40–60°C and under alkaline conditions (pH 8–10). Lipolytic activity was significantly enhanced by Ca²⁺ and Mg²⁺ ions, but dramatically inhibited by Cu²⁺, Ni²⁺ and Hg²⁺ ions and EDTA. The purified enzyme preferentially hydrolyzed relatively long-chain triacylglycerols and was a true lipase rather than an esterase. Using a multi-stepwise methanol supply, the purified LipZ03 achieved a conversion yield of biodiesel production up to 74% after 36 h. Some interesting characteristics described here showed that the recombinant lipase may have potential to be a useful enzyme in industrial applications.

Characterization of the acylglycerols and resulting biodiesel derived from vegetable oil and microalgae (Thalassiosira pseudonana and Phaeodactylum tricornutum)

Algal biofuels are a growing interest worldwide due to their potential in terms of sustainable greenhouse gas displacement and energy production. This article describes a comparative survey of biodiesel production and conversion yields of biodiesel via alkaline transesterification of acylglycerols extracted from the microalgae Thalassiosira pseudonana and Phaeodactylum tricornutum, grown under silicate or nitrate limitation, and that of model vegetable oils: soybean, and rapeseed oil. Acylglycerols were extracted with n-hexane and the total yield per biomass was determined by gravimetric assay. Under our conditions, the total acylglycerol yield from the microalgae studied was 13-18% of total dry weight. The biodiesel samples were analyzed using gas chromatography-flame ionization detector to determine quantitative information of residual glycerol, mono-, di-, and tri-acylglycerol concentrations in the biodiesel. All of the algal-based biodiesel demonstrated less mono-, di-, and tri-acylglycerol concentrations than the vegetable-based biodiesel under identical transesterification conditions. The fatty acid compositions of all the feedstock oils and their resultant biodiesel were also analyzed and reported. Based on the fatty acid methyl ester compositions of our samples we qualitatively assessed the suitability of the algal-derived biodiesel in terms of cetane number (CN), cold-flow properties, and oxidative stability.

Biodiesel production from crude canola oil by two-step enzymatic processes

Crude canola oil (CCO) contains about 100–300 ppm of phospholipids, which have shown negative effects on biodiesel/buffer solution phase separation, resulting in low biodiesel production yield. Therefore, phospholipids should be removed before transesterification by a degumming process for efficient production of biodiesel. In this study, two-step enzymatic processes (degumming and transesterification) were carried out for the production of biodiesel from CCO. Degumming of CCO was performed using phospholipase A2 as a degumming reagent. The initial phospholipid content was reduced to less than 5 ppm by enzymatic degumming. The effects of three formulations of enzyme catalyst on the efficiency of transesterification were investigated. As a result, conversion rates of degummed CCO to fatty acid methyl esters (FAME) were 68.56%, 70.15%, and 84.25%, respectively. Lipase formulation composed of a 1:1 (vol:vol) enzyme mixture of Rhizopus oryzae and Candida rugosa showed the best performance among those tested. In order to recover and reuse the lipase catalyst efficiently, a 1:1 enzyme mixture of R. oryzae and C. rugosa was immobilized on silica gel. The immobilized lipase was used in subsequent transesterification optimization experiments. Optimization of transesterification was performed by response surface methodology (RSM). A total of 20 experiments based on RSM were carried out, and the optimal reaction conditions appeared to be 24.4% (w/w) immobilized catalyst, 13.5% (w/w) buffer solution, and 15.8% (w/w) methanol based on oil mass. Conversion rate of degummed CCO to FAME was determined to be 88.9% under optimal conditions.

Influence of various parameters on reactive extraction of Jatropha curcas L. for biodiesel production

Reactive extraction ( in situ transesterification) of Jatropha curcas L. (Jatropha) seeds for biodiesel production is influenced by a variety of parameters, including seeds size, agitation speed, reaction temperature, reaction time, catalyst concentration and molar ratio of alcohol compare to the oil. In this study, these parameters were studied in the ranges of <0.5–4 mm seeds particle size, 200–300 rpm, agitation speed, 30–60 °C reaction temperature, 10–60 min reaction time, 0.1–0.2 N NaOH concentration and 100–600 molar ratio of methanol-to-oil. It was established that the smallest particle size (below 0.71 mm) resulted in the highest yield of biodiesel production. The biodiesel yield was found to be independent of intensity of the mixing once it reached 300 rpm, whereas reaction temperature did not exhibit any significant effect on the yield. It was also demonstrated that alkaline reactive extraction was complete in 20–30 min. The concentration of NaOH can affect biodiesel yield in both positive and negative way. Low concentration of NaOH (0.05 N) resulted in low yield, but at higher concentrations (0.2 N), emulsions form, due to a saponification side reaction, adversely affecting the yield. In this case, a NaOH concentration of 0.15 N produced the highest yield. It was also discovered that when the methanol-to-oil ratio reached 400, the biodiesel yield reached a constant state. The optimal conditions in this study are approximately <0.71 mm seeds particle size, 300 rpm mixing speed, 30 °C reaction temperature, 30 min reaction time, 0.15 N NaOH concentration and methanol:oil molar ratio of 400.

Optimization of biodiesel production from camelina oil using orthogonal experiment

Camelina oil is a low-cost feedstock for biodiesel production that has received a great deal of attention in recent years. This paper describes an optimization study on the production of biodiesel from camelina seed oil using alkaline transesterification. The optimization was based on sixteen well-planned orthogonal experiments (OA 16 matrix). Four main process conditions in the transesterification reaction for obtaining the maximum biodiesel production yield (i.e. methanol quantity, reaction time, reaction temperature and catalyst concentration) were investigated. It was found that the order of significant factors for biodiesel production is catalyst concentration > reaction time > reaction temperature > methanol to oil ratio. Based on the results of the range analysis and analysis of variance (ANOVA), the maximum biodiesel yield was found at a molar ratio of methanol to oil of 8:1, a reaction time of 70 min, a reaction temperature of 50 °C, and a catalyst concentration of 1 wt.%. The product and FAME yields of biodiesel under optimal conditions reached 95.8% and 98.4%, respectively. The properties of the optimized biodiesel, including density, kinematic viscosity, acid value, etc., were determined and compared with those produced from other oil feedstocks. The optimized biodiesel from camelina oil meets the relevant ASTM D6571 and EN 14214 biodiesel standards and can be used as a qualified fuel for diesel engines.

Extracted fat from lamb meat by supercritical CO 2 as feedstock for biodiesel production

The feasibility of enzymatic production of biodiesel from waste animal fats using supercritical fluid technology for the extraction and reaction has been investigated. The operating conditions that resulted in the optimum extraction and biodiesel production yields were identified. The effects of extraction temperature, pressure and supercritical CO 2 (SC-CO 2) flow rate were investigated in the ranges of 35–55 °C, 300–500 bar and of 3–5 ml min −1, respectively, and optimized using response surface methodology (RSM). In addition, the effects of reaction temperature, methanol:fat molar ratio and enzyme loading on biodiesel production yield were investigated in the ranges of 35–60 °C, 3:1–6:1 and 10–50%, respectively. The optimum conditions for supercritical fluid extraction (SFE) were determined to be 45 °C, 500 bar and 3 ml min −1; at which, 87.4% of total fat content was extracted from freeze dried meat. The statistical analysis however, showed that pressure has negligible effect on the extraction yield, which is extremely important, as it allows saving energy by using lower pressure. On the other hand, biodiesel yield of 40% was obtained using extracted fat as feedstock in SC-CO 2 medium at 50 °C, 200 bar, 4:1 methanol:fat molar ratio and 30% loading of lipase enzyme, after 24 h of reaction. The experimental results were used to fit a suitable reaction kinetic model using non-linear regression analysis to estimate the model parameters.

Mesoporous Li/ZrO2 as a solid base catalyst for biodiesel production from transesterification of soybean oil with methanol

Mesoporous 0.1M/ZrO2 (M = Li, Na, K, Mg, Ca) solid base catalysts were successfully synthesized by using a sol–gel method. The catalytic activities of the catalysts were tested via transesterification reactions of soybean oil with methanol. Both 0.1Mg/ZrO2 and 0.1Ca/ZrO2 catalysts showed no catalytic activity in this reaction, while Li, K modified ZrO2 catalysts achieved high yield of biodiesel production. Besides, under the optimum reaction conditions, a FAME yield of as high as 98.2% was achieved on 0.1Li/ZrO2 catalyst calcined at 650 °C.

Biodiesel production from rice bran oil and supercritical methanol

In this study, production of biodiesel from low cost raw materials, such as rice bran and dewaxed-degummed rice bran oil (DDRBO), under supercritical condition was carried out. Carbon dioxide (CO 2) was employed as co-solvent to decrease the supercritical temperature and pressure of methanol. The effects of different raw materials on the yield of biodiesel production were investigated. In situ transesterification of rice bran with supercritical methanol at 30 MPa and 300 °C for 5 min was not a promising way to produce biodiesel because the purity and yield of fatty acid methyl esters (FAMEs) obtained were 52.52% and 51.28%, respectively. When DDRBO was reacted, the purity and yield were 89.25% and 94.84%, respectively. Trans-FAMEs, which constituted about 16% of biodiesel, were found. They were identified as methyl elaidate [ trans-9], methyl linoleaidate [ trans-9, trans-12], methyl linoleaidate [ cis-9, trans-12], and methyl linoleaidate [ trans-9, cis-12]. Hydrocarbons, which constituted about 3% of the reaction product, were also detected.

Lipase catalyzed transesterification of soybean oil using ethyl acetate, an alternative acyl acceptor

Methanol, the acyl acceptor usually used in the commercial process of biodiesel production, is associated with some problems such as immiscibility with oils and lipase deactivation. To overcome these barriers, ethyl acetate was proposed as an alternative acyl acceptor for the production of biodiesel from soybean oil using an immobilized lipase, Novozym 435, Ethyl acetate mixed well with soybean oil, and only slightly inhibited the lipase activity by 5%. The effects of various environmental parameters, such as the composition of soybean oil and ethyl acetate, lipase content, and reaction temperature, were investigated to determine the optimal conditions for biodiesel production. As a result, the highest biodiesel production yield, 63.3 (±0.6)%, was obtained by using an ethyl acetate and soybean oil mixture with a 6∶1 molar ratio, with 8% of the immobilized lipase based on the weight of oil added at 70°C and 600 rpm.

Biodiesel production using a mixture of immobilizedRhizopus oryzae andCandida rugosa lipases

Biodiesel conversion from soybean oil reached a maximum of 70% at 18 h using immobilized 1,3-specificRhizopus oryzae lipase alone. Biodiesel conversion failed to reach 20% after 30 h when immobilized nonspecificCandida rugosa lipase alone was used. To increase the biodiesel production yield, a mixture of immobilized 1,3-specificR. oryzae lipase and nonspecificC. rugosa lipase was used. Using this mixture a conversion of greater than 99% at 21 h was attained. When the stability of the immobilized lipases mixture was tested, biodiesel conversion was maintained at over 80% of its original conversion after 10 cycles.