Guava seed biochar appears as a new alternative of the effective support to the immobilization of Burkholderia cepacia lipase (BCL) by physical adsorption. The objective of this work was to evaluate the potential of this immobilized biocatalyst in the transesterification reaction of crude coconut oil and ethanol and to understand the mechanism of the reaction through the study of molecular docking. The best loading of BCL was determined to be 0.15 genzyme/gsupport having a hydrolytic activity of 260 U/g and 54% immobilization yield. The products of transesterification reaction produced a maximum yield at 40 °C under different reaction conditions. The monoacylglycerols (MAGs) conversion of 59% was using substrate molar ratio oil:ethanol of 1:7 with the reaction time of 24 H. In addition, the highest ethyl esters yield (48%) had the molar ratio of 1:7 with the reaction time of 96 H and maximum conversion of diacylglycerols (DAGs) was 30% with the molar ratio of 1:6 with the reaction time of 24 H. Molecular Docking was applied to clarify the mechanisms of transesterification reaction at the molecular level. MAGs and DAGs are compounds with excellent emulsifying properties used in industrial production of several bioproducts such as cosmetic, pharmaceuticals, foods, and lubricants.

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Enzymes are promising tools for achieving an environmentally benign process. However, enzymes are required to be immobilized on economically competent supports to be reusable and maintain their activity. In this work, the aim was to evaluate the application of the biochar for immobilization of Burkholderia cepacia lipase (BCL) by physical adsorption (PA) and covalent binding (CB). Additionally, it was observed that regarding the biochemical properties, the optimal pH was 4.0 for the BCL immobilized by PA and pH 7.0 for the BCL free and immobilized by CB. Among the kinetic parameters, the maximal velocity (Vmax) for the free enzyme was 2500 µmol g−1·min−1, and for the PA- and CB-immobilized biocatalyst the values of Vmax were 2000 and 3333 µmol g−1·min−1, respectively. The Michaelis-Menten constant (Km) value for the free lipase was 665 mM and for the biocatalysts immobilized by PA and CB the Km values were 219 and 369 mM, respectively. Immobilized LBC exhibited superior thermal stability. The reusability tests showed that the LBC immobilized by PA preserved 50% of the initial activity after 16 cycles. Thus, biochar is a by-product of a renewable source; therefore, it is a promising alternative for lipase immobilization demonstrating its potential for use in a wide range of greener industrial processes.

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A água produzida de petróleo antes de ser condicionada ao descarte ou rejeição, necessita passar por uma série de tratamentos, dentre estes a coagulação, etapa importante para a remoção de material orgânico e inorgânico. O uso de coagulantes ambientalmente corretos apresenta-se como uma alternativa viável para o tratamento de água e tem mostrado vantagens em relação aos químicos, especificamente em relação à biodegradabilidade, baixa toxicidade e baixo índice de produção de lodos residuais. Sendo assim, este trabalho tem como objetivo avaliar diferentes métodos de preparo do coagulante à base de moringa e determinar a sua eficiência de remoção do teor de óleos e graxas presentes na água produzida de petróleo. Cinco métodos de preparo do coagulante à base de moringa foram propostos. Os ensaios de coagulação/floculação foram realizados variando a concentração de Moringa oleifera Lam entre 50 ppm a 300 ppm, com amostras de água produzida sintética (APS) a fim de determinar a melhor concentração do coagulante em cada método de preparo. De maneira geral, os resultados mostraram-se eficientes, alcançando uma remoção máxima de óleo em água de 96%, na concentração de 100 ppm, para o coagulante preparado na forma mesh 20 ( ).