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The base (such as CaO)-catalyzed heterogeneous preparation of biodiesel encounters a number of obstacles including the need for CaO pretreatment and the reactions being incomplete (typically 90-95% yields). In this study, a number of glymes were investigated as benign solvents for the CaO-catalyzed transesterification of soybean oil into biodiesel with a high substrate loading (typically soybean oil >50% v/v). The triglyceride-dissolving capability of glymes led to a much faster reaction rate (>98% conversions in 4h) than in methanol alone (typically 24h) and minimized the saponification reaction when catalyzed by anhydrous CaO or commercial lime without pre-activation. The use of glyme (e.g. P2) as co-solvent also activates commercial lime to become an effective catalyst without calcination pretreatment. The SEM images suggest a dissolution-agglomeration process of CaO surface in the presence of P2, which could remove the CaCO3 and Ca(OH)2 layer coated on the surface of lime., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Glymes (i.e. glycol diethers) were explored as alternative benign solvents for enzymatic reactions, specifically the lipase-catalyzed transesterification. Long-chain glymes were found highly compatible with immobilized Candida antarctica lipase B (iCALB), leading to higher enzyme activities and stabilities than t-butanol and ionic liquids (e.g. the rate of transesterification in diethylene glycol dibutyl ether (G2-Bu) was 77% higher than that in t-butanol). Furthermore, soybean oil was found fully miscible with glymes, which enabled a homogeneous reaction mixture for the enzymatic preparation of biodiesel. In the presence of glymes, CALB showed a very high tolerance to high methanol concentrations (up to 60-70% v/v), and nearly stoichiometric triglyceride conversions could be obtained under mild reaction conditions. A laboratory scale-up achieved a high conversion of soybean oil (95.5%). This study suggests that glymes can be environmentally friendly and inexpensive solvents for lipase-catalyzed reactions, such as the enzymatic preparation of biodiesel., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

A deepeutectic solvent (DES) consisting of choline chloride andglycerol (1:2 molar ratio) was prepared and used as the solvent inCaO-catalyzed transesterification of rapeseed oil to produce biodiesel.In addition to its solvent role, DES activated commercial CaO to bea catalyst for the transesterification reaction. The yield of fattyacid methyl ester (FAME) with the addition of DES reached 91.9%, whilethe FAME yield with no DES was only 4.0%. The commercial CaO samplesbefore and after reaction were characterized by Powder X-ray diffraction(XRD), Fourier transform infrared spectroscopy (FT-IR), and ScanningElectronic Microscopy (SEM). These measurements indicate that thesurface of commercial CaO is typically covered by a layer of CaCO3and Ca(OH)2which inhibits the activity of CaO,while the addition of DES can eliminate this inhibiting layer leadingto CaO activation. [ABSTRACT FROM AUTHOR]

Abstract: The present study aims to isolate the lipids from microalgae by supercritical CO2 (SC-CO2) extraction followed by a further enrichment of crude lipids to produce high-purity docosahexenoic acid (DHA) by an urea complexation method. Our systematic approach indicates the optimum conditions of supercritical CO2 extraction were obtained as follows: 35MPa, 40°C, ethanol (95%, v/v) as the co-solvent, and the mass ratio of material to co-solvent 1:1. Under these conditions, 33.9% of lipid yield and 27.5% of DHA content were achieved. Despite the relatively low lipid yield, supercritical CO2 extraction has exhibited many advantages over the Soxhlet extraction for the DHA enrichment such as high DHA purity and superb product quality. Furthermore, urea complexation method on DHA enrichment considerably increased the DHA purity from 29.7% to 60.4% with an enrichment ratio of 60.6%, under the optimum complexation conditions of urea/fatty acid 2:1, complexation time 8h, and the complexation temperature of −10°C. [Copyright &y& Elsevier]

Review: 389 refs. [ABSTRACT FROM AUTHOR]

Review: 406 refs. [ABSTRACT FROM AUTHOR]