Insights in the biocatalyzed hydrolysis, esterification and transesterification of waste cooking oil with a vegetable lipase

Direct synthesis of Fe-aluminosilicates from red mud for catalytic deoxygenation of waste cooking oil

Conversion of red mud (RM) that contains a high level of silica, alumina and iron minerals into heterogenous catalysts, offers a route for the utilization of abundant toxic by-products of bauxite refining. In this study, the conversion of red mud into mesoporous Fe-aluminosilicate produced selective catalysts for the deoxygenation of waste cooking oil to green diesel hydrocarbons. Direct conversion of red mud in the presence cetyltrimethylammonium bromide into Fe-aluminosilicate (RM-CTA) produced a highly mesoporous structure with oligomeric Fe2O3 clusters within the pores. When red mud was treated with citric acid (RM-CA-CTA), a wide distribution of Fe2O3 particles was obtained on the aluminosilicate external surface. TEM analysis showed a well-defined hexagonal mesoporosity of Fe-aluminosilicate obtained from untreated red mud, while the treated red mud produced lower regularity mesopores. RM-CTA exhibits 60% WCO conversion and 83.72% selectivity towards liquid products with 80.44% diesel hydrocarbon (C11-C18) yield. The high selectivity was due to the high acidity of Fe-aluminosilicate to dissociate the C-O bond and the regularity of mesostructure for efficient hydrocarbon diffusion, preventing a cracking reaction.

Biocatalysis of triglycerides transesterification using fungal biomass: a biorefinery approach

BACKGROUND

The use of microbial biomasses, such as fungal biomass, to catalyze the transesterification of triglycerides (TG) for biodiesel production provides a sustainable, economical alternative while still having the main advantages of expensive immobilized enzymes.

RESULTS

Biomasses of Aspergillus flavus and Rhizopus stolonifera were used to catalyze the transesterification of TG in waste frying oil (WFO). Isopropanol as an acyl-acceptor reduced the catalytic capability of the biomasses, while methanol was the most potent acyl-acceptor with a final fatty acid methyl ester (FAME) concentration of 85.5 and 89.7%, w/w, for R. stolonifer and A. flavus, respectively. Different mixtures of the fungal biomasses were tested, and higher proportions of A. flavus biomass improved the mixture's catalytic capability. C. sorokiniana cultivated in synthetic wastewater was used as feedstock to cultivate A. flavus. The biomass produced had the same catalytic capability as the biomass produced in the control culture medium. Response surface methodology (RSM) was adopted using central composite design (CCD) to optimize the A. flavus biomass catalytic transesterification reaction, where temperature, methanol concentration, and biomass concentration were selected for optimization. The significance of the model was verified, and the suggested optimum reaction conditions were 25.5 °C, 250 RPM agitation with 14%, w/w, biomass, 3 mol/L methanol, and a reaction duration of 24 h. The suggested optimum conditions were tested to validate the model and a final FAME concentration of 95.53%. w/w was detected.

CONCLUSION

Biomasses cocktails might be a legitimate possibility to provide a cheaper technical solution for industrial applications than immobilized enzymes. The use of fungal biomass cultivated on the microalgae recovered from wastewater treatment for the catalysis of transesterification reaction provides an additional piece of the puzzle of biorefinery. Optimizing the transesterification reaction led to a valid prediction model with a final FAME concentration of 95.53%, w/w.

Preparation of 2-Arachidonoylglycerol by Enzymatic Alcoholysis: Effects of Solvent and Water Activity on Acyl Migration

Enzymatic alcoholysis was performed in an organic medium to synthesize 2-monoacylglycerol (2-MAG) rich in arachidonic acid. The results showed that solvent type and water activity (a_w) significantly affected the 2-MAG yield. Under the optimum conditions, 33.58% 2-MAG was produced in the crude product in t-butanol system. Highly pure 2-MAG was obtained after two-stage extraction using 85% ethanol aqueous solution and hexane at first stage and dichloromethane and water at second stage. Isolated 2-MAG was used as substrate to investigate the effect of solvent type and a_w on 2-MAG acyl migration in a lipase-inactivated system. The results indicated that non-polar solvents accelerated the acyl migration of 2-MAG, whereas isomerization was inhibited in polar solvent systems. The a_w exhibited the strongest inhibition effect on 2-MAG isomerization at 0.97, but also affected the hydrolysis of glycerides and lipase selectivity.

Biocatalysts Synthesized with Lipase from Pseudomonas cepacia on Glycol-Modified ZIF-8: Characterization and Utilization in the Synthesis of Green Biodiesel

This research presents results on the production of biodiesel from the transesterification of acylglycerides present in palm oil, using the biocatalysts ZIF-8-PCL and Gly@ZIF-8-PCL synthesized by immobilization of Pseudomonas Cepacia Lipase as catalytic materials and using pure ZIF-8 and Gly@ZIF-8 (modified ZIF-8) as supports. The Gly@ZIF-8 carbonaceous material was prepared by wet impregnation of ZIF-8 with ethylene glycol as the carbon source, and then thermally modified. The calcination conditions were 900 °C for two hours with a heating rate of 7 °C/min in an inert atmosphere. A textural characterization was performed, and results showed superficial changes of materials at the microporous and mesoporous levels for the Gly@ZIF-8 material. Both the starting materials and biocatalysts were characterized by infrared spectroscopy (FTIR) and Raman spectroscopy. During the transesterification, using the two biocatalysts (ZIF-8-PCL and Gly@ZIF-8-PCL), two supernatant liquids were generated which were characterized by infrared spectroscopy (FTIR), gas chromatography coupled to mass spectrometry (GC-MS), and nuclear magnetic resonance (NMR). The results show that the two routes of synthesis of supports from ZIF-8 will be configured as effective methods for the generation of effective biocatalysts for biodiesel production.