Green and efficient catalysts for the production of biodiesel are highly important. In this study, a Pickering magnetic interface biocatalyst (Fe₃O₄@PS-NH-lipase) was prepared, which can effectively stabilize the soybean oil-in-methanol emulsion and achieve static transesterification. When the appropriate methanol/soybean oil molar ratio and catalyst loading were chosen, the Pickering interface biocatalyst exhibited outstanding enzymatic activity, reaching a conversion rate of 89.3% after 30 h. Pickering interfacial catalysis (PIC, immobilizing catalytic centers on a carrier and combining it with a Pickering emulsion) shows more significant specific activity, leading to a 1.2-fold improvement in catalytic performance as compared to Pickering assisted catalysis (PAC, relying on the use of nanoparticles for stabilizing Pickering emulsions together with a homogeneous catalyst). Moreover, the recycled catalyst still possesses significant catalytic activity after 5 cycles. This article provides a green and efficient strategy for the effective recovery of biologically active substances and the enhancement of biphasic reactions.

Recently, Pickering interfacial catalyst (PIC) was widely applied for liquid-liquid reactions, in view of not only intensifying the mass transfer through significant reducing both the drop sizes and the diffusion distance, but also supplying a flexible platform for the immobilization of valuable active sites. However, the restriction of the mobility of catalyst somehow decreases the activity of a catalyst. To obtain a promise reaction efficiency, we firstly report a synergistic method to enhance the biphasic reaction by Pickering emulsion and ultrasound concepts, targeted at efficient production of biodiesel. Response surface methodology based on Box-Behnken design was applied to optimize the reaction conditions, such as composition of catalyst, reaction temperature, ultrasound power, methanol to oil molar ratio and catalyst amount. An over 98% yield of biodiesel could be achieved within 2.5 hours by ultrasound assisted Pickering interfacial catalysis, which is over two times higher than that of ultrasound assisted homogeneous transesterification system. Besides, the ultrasound assisted Pickering emulsion shortened the reaction time by 3.6 fold when compared to mechanical stirring assisted Pickering emulsion system.

Microporous membranes are frequently used to remove or concentrate suspended solids. To maximize filtration efficiency for certain high-value liquids, a microporous membrane with a nontraditional asymmetric topology was recently developed to treat bio-based liquids, such as the isolation of proteins/enzymes from concentrates or the concentration of active cells from cultivation media. In this study, compared with both asymmetric and symmetric membranes, we reveal the unique filtration properties of “upper-stream open” asymmetric membrane using four types of fluids comprising monodispersed micro-hydrogels with sizes ranging from 294 to 517 nm. The results indicate that the internal pore structures of the membranes significantly affect the retention of microhydrogels of identical sizes. Asymmetric membranes offer considerable advantages in terms of retention efficiency and particle localization. By applying four classical blocking models along with adsorption models, the primary blockage mechanisms in asymmetric membranes for microgels of different sizes were explored. These results offer a better understanding of the interaction between the membrane and filtrate, assist in membrane selection, and elucidate the experimental results of membrane filtration.