Enzymatic production of biodiesel from Pistacia chinensis bge seed oil using immobilized lipase

Biodiesel fuel from renewable non-edible woody plant oils has recently attracted more attention due to its environmental benefits and the reduced costs of raw materials. This study investigated the enzymatic transesterification of Pistacia chinensis bge seed oil (PCO) with methanol. The recombinant Rhizopus oryzae lipases (ROL) immobilized on macroporous resin and anion exchange resin, named as MI-ROL and AI-ROL, respectively, were used as biocatalysts. The transesterification reaction catalyzed by the immobilized lipase was investigated in a solvent-free system. The highest biodiesel yields of 92% and 94% were achieved under the optimum conditions (enzyme dosage 25 IU_AI-ROL/g PCO or 7 IU_MI-ROL/g PCO, methanol to oil molar ratio 5:1, water content 20% by weight of oil, temperature 37 °C, and reaction time 60 h). There was no obvious loss in the yield of biodiesel after being consecutively used for five cycles in the transesterification reactions using AI-ROL, while the yield of biodiesel remained above 60% after the MI-ROL was repeatedly used for four cycles.     

Biodiesel preparation,optimization, and fuel properties from non-edible feedstock,Datura stramonium L.

This is a study on the feasibility of biodiesel preparation from a new and promising non-edible feedstock, Datura stramonium L. oil (DSO). First, important physical–chemical properties, such as oil content of seed (21.4 wt%), acid value (7.93 mg KOH/g) and fatty acid composition of expressed oil, were determined. Second, under the optimal two-step catalyzed reaction conditions, the maximum fatty acid methyl ester (FAME) yield (87%) and FAME content of more than 98 wt% were obtained. Furthermore, the fuel properties of DSO biodiesel were determined and evaluated. Compared with Jatrpha curcas L. (JC) and beef tallow (BT) biodiesel, DSO biodiesel possessed the best kinematic viscosity (4.33 mm²/s) and cold filter plug point (?5 °C). Based on the results, D. stramonium L. was identified as a promising species for biodiesel feedstock.     

Influence of feedstock source on the biocatalyst stability and reactor performance in continuous biodiesel production

A biodiesel process in a packed bed reactor was used as a model system to show the strong dependence of the reactor behavior on the developing of chemical environment within the reactor. Ethanolysis runs of babassu and macaw palm oils were carried out in a solvent-free system using Burkholderia cepacia lipase immobilized on silica–PVA matrix. The best performance was found for the reactor running on macaw palm oil, which resulted in a stable operating system and an average yield of 87.6 ± 2.5%. This strategy also gave high biocatalyst operational stability, revealing a half-life of 478 h.     

Biodiesel synthesis combining pre-esterification with alkali catalyzed process from rapeseed oil deodorizer distillate

A two-step technique combining pre-esterification catalyzed by cation exchange resin with transesterification catalyzed by base alkali was developed to produce biodiesel from rapeseed oil deodorizer distillate (RDOD). The free fatty acids (FFAs) in the feedstock were converted to methyl esters in the pre-esterification step using a column reactor packed with cation exchange resin. The acid value of oil was reduced from the initial 97.60 mg-KOH g^? 1 oil to 1.12 mg-KOH g^? 1 oil under the conditions of cation exchange resin D002 catalyst packed dosage 18 wt.% (based on oil weight), oil to methanol molar ratio 1:9, reaction temperature 60 °C, and reaction time 4 h. The biodiesel yield by transesterification was 97.4% in 1.5 h using 0.8 wt.% KOH as catalyst and a molar ratio of oil to methanol 1:4 at 60 °C. The properties of RDOD biodiesel production in a packed column reactor followed by KOH catalyzed transesterification were measured up the standards of EN14214 and ASTM6751-03.     

Enzymatic conversion of corn oil into biodiesel in a batch supercritical carbon dioxide reactor and kinetic modeling

Synthesis of fatty acid methyl esters (FAME) as biodiesel from corn oil was studied in a batch supercritical carbon dioxide (SC-CO₂) bioreactor using immobilized lipase (Novozym 435) as catalyst. Effects of reaction conditions on the contents of FAME, monoacylglycerols (MAG), diacylglycerols (DAG), and triacyglycerols (TAG) were investigated at various enzyme loads (5–15%), temperatures (40–60 °C), substrate mole ratios (corn oil:methanol; 1:3–1:9), pressures (10–30 MPa), and times (1–8 h). The highest FAME content (81.3%) was obtained at 15% enzyme load, 60 °C, 1:6 substrate mole ratio, and 10 MPa in 4 h. A reaction kinetic model was used to describe the system, and the activation energy of the system was calculated as 72.9 kJ/mol. Elimination of the use of organic solvents, chemical catalysts and wastewater as well as reasonably high yields make the enzymatic synthesis of biodiesel in SC-CO₂ a promising green alternative to conventional biodiesel process.     

Preparation of fatty acid methyl esters from hazelnut,high-oleic peanut and walnut oils and evaluation as biodiesel

Refined hazelnut, walnut and high-oleic peanut oils were converted into fatty acid methyl esters using catalytic sodium methoxide and evaluated as potential biodiesel fuels. These feedstocks were of interest due to their lipid production potentials (780–1780 L ha^?1 yr^?1) and suitability for marginal lands. Methyl oleate was the principal constituent identified in hazelnut (HME; 76.9%) and peanut (PME; 78.2%) oil methyl esters. Walnut oil methyl esters (WME) were comprised primarily of methyl esters of linoleic (60.7%), oleic (15.1%) and linolenic (12.8%) acids. PME exhibited excellent oxidative stability (IP 21.1 h; EN 14112) but poor cold flow properties (CP 17.8 °C) due to its comparatively high content of very-long chain fatty esters. WME provided low derived cetane number and oxidative stability (IP 2.9 h) data as a result of its high percentage of polyunsaturated fatty esters. HME yielded a satisfactory balance between all fuel properties when compared to the biodiesel standards ASTM D6751 and EN 14214 due to its high content of monounsaturated fatty esters. Also explored were the properties of blends of HME, PME and WME in ultra-low sulfur (<15 ppm) diesel (ULSD) fuel and comparison to petrodiesel standards ASTM D975, D7467 and EN 590. With increasing content of biodiesel, the oxidative stability, cold flow properties and calorific value of ULSD was negatively affected, whereas lubricity was markedly improved. Kinematic viscosity, specific gravity and surface tension were impacted to lesser extents by addition of biodiesel to ULSD. In summary, HME, PME and WME are suitable based on their fuel properties as biodiesel fuels and blend components in ULSD.     

Biodiesel production from waste tallow

In the present investigation an attempt has been made to use waste tallow as low cost sustainable potential feed stock for biodiesel production. Effect of various process parameters such as amount of catalyst, temperature and time on biodiesel production was investigated. The optimal conditions for processing 5 g of tallow were: temperature, 50 and 60 °C; oil/methanol molar ratio 1:30 and 1:30, amount of H₂SO_4, 1.25 and 2.5 g for chicken and mutton tallow, respectively. Under optimal conditions, chicken and mutton fat methyl esters formation of 99.01 ± 0.71% and 93.21 ± 5.07%, was obtained after 24 h in the presence of acid. The evaluation of transesterification process was followed by gas chromatographic analysis of tallow fatty acid esters. A total of 98.29% and 97.25% fatty acids were identified in chicken and mutton fats, respectively. Both fats were found highly suitable to produce biodiesel with recommended fuel properties.     

Basic ionic liquid immobilized oxides as heterogeneous catalyst for biodiesel synthesis from waste cooking oil

The basic ionic liquid (IL) [Bmin]OH was synthesized and immobilized onto oxide surface to obtain IL/Mg-Al and IL/Mg-Al-La catalysts. The catalysts were characterized by FT-IR, XRD, EDS, BET and basic test. The results proved that the IL immobilized oxides exhibited high activity for biodiesel synthesis from waste cooking oil. The high FAME yield of 98.7% could be obtained at 338 K, 12:1 methanol to oil, 3 wt% catalyst amount and 6 h reaction time by IL/Mg-Al-La catalysts.     

Development of biodiesel from karanja,a tree found in rural India

Development of biodiesel from karanja tree, mainly found in rural India has been investigated. The biodiesel was developed from oil expelled from the seeds of the tree. Molecular weight of the oil was determined and found to be 892.7. Both the acid as well as alkaline esterification were subsequently performed to get the final product. NaOH was found to be a better catalyst than KOH in terms of yield. Maximum yield of 89.5% was achieved at 8:1 molar ratio for acid esterification and 9:1 molar ratio for alkaline esterification, 0.5 wt.% catalyst (NaOH/KOH) using mechanical stirrer.     

Application of response surface methodology for the optimization of supercritical carbon dioxide extraction and ultrasound-assisted extraction of Capparis spinosa seed oil

Caper (Capparis spinosa) seed oil growing wild in Iran was extracted using supercritical CO₂ and ultrasound-assisted extraction methods. The experimental parameters of SFE and UAE were optimized using a rotatable central composite design. The highest yield for SFE was obtained at a pressure of 355 bar, temperature of 65 °C, modifier volume of 140 μL, static and dynamic extraction time of 10 and 35 min, respectively, and for UAE was gained at solvent volume of 23 mL, sonication time of 45 min and temperature of 40 °C. This resulted in a maximum oil recovery of 25.1% and 27.9% for SFE and UAE, respectively. The extracts with higher yield from both methods were subjected to transesterification and GC–MS analysis. SFE and UAE processes selectively extracted the fatty oils with high percentage of omega-6 and omega-9-fatty acids. The major components of the extracted oils from both methods were linoleic, oleic, its positional isomer cis-vaccenic and Palmitic acid.     

Extraction and solubility evaluation of functional seed oil in supercritical carbon dioxide

Hemp (Cannabis sativa L.) seed oil is valued for its nutritional properties and for the health benefits associated with it. Its greatest feature is that the ratio of linoleic acid and linolenic acid is the desirable value of 3:1. In this research, supercritical carbon dioxide was applied to extraction of functional oil from hemp seed. In order to determine the effect of temperature and pressure on the yield of extracted components, the oil was extracted from hemp seed at temperatures between 40 and 80 °C, pressures of 20–40 MPa and a CO₂ flow rate of 3 mL/min. The solubility of hemp seed oil in SCCO₂ determined experimentally was fitted to the Chrastil equation to determine the model parameters. The solubility calculated by Chrastil equation was compared with the experimental data. Finally, the fatty acid profile of the oil was evaluated by gas chromatography-flame ionization detection (GC-FID). There are no significant differences in the compositions of five abundant fatty acid components of the oil obtained at different sampling times with SCCO₂ extraction and other extraction methods.     

Macauba oil as an alternative feedstock for biodiesel: Characterization and ester conversion by the supercritical method

In this work different samples of Brazilian macauba oil obtained from mechanical pressing were characterized and production of esters of fatty acids using a catalyst-free continuous process under supercritical alcohols was assessed. Analysis of oil samples showed that the major fatty acid on pulp oil was oleic acid (mean value 62.8%), the amount of free fatty acid (FFA) was very high (37.4–65.4%), samples contained glycerides (7.4–16.5% TAG, 14.2–16.8% DAG and 1.0–3.4% MAG) and moisture was around 1.0%. Oil was processed in a continuous reactor using supercritical methanol or ethanol and the effects of temperature (573, 598, 623 and 648 K), pressure (10, 15 and 20 MPa), oil to alcohol molar ratio (1:20, 1:30 and 1:40), water concentration (0, 5 and 10 wt% added) and the flow rate of reaction mixture (1.0, 1.5, 2.0, 2.5 and 3.0 mL/min) on process efficiency were evaluated. The highest ester content achieved in reactions with supercritical methanol was 78.5% (648 K, 15 MPa, 1:30 oil:methanol molar ratio, 5 wt% water and 2.5 mL/min flow rate), while with supercritical ethanol was 69.6% (598 K, 15 MPa, 1:30 oil:ethanol molar ratio, 5 wt% water and 2.0 mL/min flow rate). The extent of the reaction was explored using a novel parameter, convertibility, which corresponds to the maximum ester content attainable from the feedstock. According to the convertibility of macauba pulp oil, the highest ester content corresponded to efficiencies of 98.0% and 86.9%, respectively. Results demonstrate that macauba oil might be a potential alternative for biodiesel production, though purification steps should be taken into account to achieve biodiesel specifications.     

Synthesis of biodiesel from edible,non-edible and waste cooking oils via supercritical methyl acetate transesterification

The use of methyl acetate instead of methanol for supercritical synthesis of glycerol-free biodiesel from vegetable oils is a new process and its study is very limited in the literature. In this work, it has been tested for the first time on three edible and non-edible oils with different fatty acid composition. The process was also applied to waste oil with higher free fatty acid (FFA) content. The results demonstrate that the oil composition does not significantly influence the biodiesel yield.The influence of temperature, pressure and molar ratio of reactants was studied. All the oils achieved complete conversion after 50 min at 345 °C, 20 MPa with methyl acetate:oil molar ratio equal to 42:1. The obtained data also allowed calculating the apparent rate coefficients and activation energies.Eventually, some new information on the process was obtained. Thermal degradation of triacetin, which substitutes glycerol as the by-product of the transesterification reaction, was observed. Some indicative experiments were performed to understand the role of the acetic acid produced by FFA esterification.     

Nitration of biodiesel of waste oil: Nitrated biodiesel as a cetane number enhancer

Biodiesel has been produced by transesterification of waste frying oil with methanol catalysed by sodium methoxide. The unsaturated fatty acid methyl esters of the biodiesel produced have been nitrated by two alternative nitration methods, showing an incorporation of nitrogen between 3.43 and 5.10 wt.%, in the chemical form of nitro, nitrate and acetoxy functional groups. A detailed gas chromatography–mass spectrometry analysis has been carried out on the nitrated biodiesel samples in order to identify the nitration products of this complex mixture. The nitrated biodiesel has been added to a base diesel fuel in a 1000 mg L⁻¹ concentration resulting in an increase of the cetane number of the fuel by more than five points, from 54.7 to 60.5.     

Supercritical CO2 extraction of omega-3 rich oil from Sacha inchi (Plukenetia volubilis L.) seeds

Supercritical carbon dioxide (SC-CO₂) was employed to extract omega-3 rich oil from Sacha inchi (Plukenetia volubilis L.) seeds and partially defatted cake. For ground seeds, the supercritical extraction was carried out at temperatures of 40, 50 and 60 °C and pressures of 300 and 400 bar, and for the cold pressed partially defatted cake, the extraction was carried out with 300 bar at 40 °C and with 400 bar at 60 °C. The global extraction yields (X₀), oil solubility, fatty acid composition of the oil and tocopherol content were determined. The seed samples used in this work contained 54.3% oil, of which 50.5% was linoleinc acid (ω-3). The maximum extraction recovery for the seeds as 92% at 400 bar and 60 °C, but on one occasion a recovery of 99.1% oil was obtained when cold pressed extraction was employed, followed by supercritical extraction at 400 bar and 60 °C. A high tocopherol content of about 2–3 g/kg of oil was obtained.     

Synthesis,characterization and application of poly(N-isopropylacrylamide-co-itaconic acid) hydrogels as supports for lipase immobilization

Temperature- and pH-sensitive hydrogels based on N-isopropylacrylamide (NiPAAm) and itaconic acid (IA) were applied for immobilization of lipase from Candida rugosa (CRL). The hydrogels were synthesized by free radical crosslinking copolymerization in the presence of lipase. Characterization of samples by swelling studies, at pH 2.20 and 6.80 at a temperature of 37 °C, scanning electron microscopy (SEM) and Fourier transform infrared analysis (FT-IR) confirmed that the degree of crosslinking, the non-ionic/ionic (NiPAAm/IA) ratio and the enzyme content had impacts on the hydrogel structure, mechanical properties, morphology and swelling kinetics. All hydrogels demonstrated protein loading efficiencies as high as 95 wt.%. A specific activity of the immobilized lipase of around 38 IU/g was attained for an enzyme loading of 20.0 wt.%. As a result, improved pH and temperature optima values were obtained for the immobilized systems in relation to those for the free lipase.     

Transesterified milkweed (Asclepias) seed oil as a biodiesel fuel

The methyl and ethyl esters of milkweed (Asclepias) seed oil were prepared and compared to soybean esters in laboratory tests to determine biodiesel fuel performance properties. The pour points of the methyl and ethyl milkweed esters measured −6 °C and −10 °C, respectively, which is consistent with the high levels of unsaturation characteristic of milkweed seed oil. The oxidative stabilities measured by OSI at 100 °C were between 0.8 and 4.1 h for all samples tested. The kinematic viscosities determined at 40 °C by ASTM D 445 averaged 4.9 mm²/s for milkweed methyl esters and 4.2 mm²/s for soybean methyl esters. Lubricity values determined by ASTM D 6079 at 60 °C were comparable to the corresponding soybean esters with average ball wear scar values of 118 μm for milkweed methyl esters and 200 μm for milkweed ethyl esters.     

Optimization of enzymatic pretreatment for n-hexane extraction of oil from Silybum marianum seeds using response surface methodology

An investigation on enzymatic pretreatment for n-hexane extraction of oil from the Silybum marianum seeds was conducted. The optimum combination of extraction parameters was obtained with the response surface methodology (RSM) at a four-variable and five-level central composite design (CCD). The optimum parameters of enzymatic pretreatment were as follows: enzyme concentration of 2.0% (w/w), temperature of 42.8 °C, reaction time of 5.6 h, and pH of 4.8. After enzymatic pretreatment, the oil was extracted by n-hexane for 1.5 h, and the oil yield on a dry basis was 45.70%, which well matched with the predicted value (45.86%). The results of the effects of the enzymatic pretreatment for n-hexane extraction of oil from the aspects of oil yield, microstructure and the fatty acid compositions showed that the enzymatic pretreatment had not affected on the fatty acid compositions, but could cause structure breakage of the S. marianum seeds and accelerate releasing extra oil, which increased the oil yield by 10.46% compared with n-hexane extraction for 1.5 h without enzymatic pretreatment, and confirmed the efficacy of enzymatic pretreatment for n-hexane extraction of oil from the S. marianum seeds.     

Supercritical CO2 extraction of rosehip seed oil: Fatty acids composition and process optimization

Rosehip seed oil has been extracted using supercritical CO₂ at various operating conditions to optimize extraction process. The effect of extraction conditions on the fatty acids composition in the oil was also observed. The extraction conditions were as follows: pressures (P) of 150, 300 and 450 bar, temperatures (T) of 40, 60 and 80 ^oC, and CO₂ flow rate (F) of 2, 3 and 4 mL/min. A full 3³ factorial design coupled with statistical and graphical analysis of the results, by using analysis of variance (ANOVA) was applied to optimize variables in the process of rosehip seed oil extraction with SC-CO₂. The experimental result showed that the seed oil extracted mainly contained linoleic acid (C18:2) as the most abundant followed by linolenic (C18:3), palmitic (C16:0) and stearic acid (C18:0); and the extraction conditions influenced the fatty acids composition. The analysis of experimental design for process optimization results demonstrates that temperature and pressure were to be the influential variables on the extraction yield of seed oil. Furthermore, the apparent solubility of oil in SC-CO₂ was also determined from the experimental data and correlated using empirical equations for further model developing.     

The effect of flux and residence time in the production of biodiesel from various feedstocks using a membrane reactor

Biodiesel produced from lipid sources is a clean-burning, biodegradable, nontoxic fuel that is free of aromatic hydrocarbons. Current biodiesel production processes are tedious and involve two to three reaction steps each followed by separation and purification. Process integration of reaction and separation in a single step within a membrane reactor (MR) offers several advantages over conventional reactors.This investigation is aimed at studying the effect of membrane flux and residence time on the performance of a membrane reactor in treating a variety of raw and used feedstocks. A membrane reactor having three selectable reactor volumes was designed to decouple the effect of residence time in the reactor from membrane flux on the performance of the reactor. Low free fatty acid (FFA) oils (FFA < 1%), i.e. canola, corn, sunflower and un-refined soy oils, and high FFA waste cooking oil (FFA = 5%) were base transesterified and the quality of the biodiesel produced was determined in terms of free glycerine, mono-glyceride, di-glyceride and tri-glyceride content. All oils were base transesterified without pretreatment.Based on the composition of the final product, the MR could be operated at the upper limit of the flux tested (70 L/m²/h) and a residence time of 60 min. The ASTM D6751 and EN 14214 standards for glycerin and glycerides were reached in the washed biodiesel product for all feedstocks and run conditions. The operating pressure in the reactor was exceeded at 70 L/m²/h in treating waste oils and pre-treated corn oil. For these oils, reasonable operating pressures in the reactor were reached at a membrane flux of 30–40 L/m²/h. The quality of the washed biodiesel always met ASTM and EN standards. The FAME produced from WCO at intermediate fluxes and high residence times met the ASTM and EN standards without water washing.