Simultaneous enzymatic esterification and ester extraction in Pickering emulsions for the recovery of butanol from fermentation broth

The recovery of biobutanol from highly diluted aqueous fermentation broth usually suffers from intensive energy consumption. In this study, we developed a Pickering emulsion system stabilized by silica nanoparticles for the rapid and efficient recovery of low concentrations of butanol (<20 g L-1) from fermentation broth in the form of esters. Each droplet in the emulsion system serves as a microreactor for enzymatic esterification of butanol in the water phase, and the ester product is spontaneously extracted to the oil phase, thereby promoting the esterification reaction. The system offers a significantly larger interfacial area and a 2-5 times improvement in reaction rate compared to the biphasic system. Under optimal conditions, the conversion and extraction of butanol from the fermentation broth into butyl butyrate achieved a yield of 79% in the presence of a Pickering emulsion. This study presents a sustainable and efficient approach for the recovery of biobased butanol.