Ultrasound-assisted Pickering Interfacial Catalysis for Transesterification: Optimization of Biodiesel Yield by Response Surface Methodology

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.