Fabrication of oil-in-natural deep eutectic solvents Pickering interfacial catalysis: Boosting a sustainable platform for enzymatic esterification of high-acid oil.

Traditional oil-in-water Pickering interfacial biocatalysis remains challenged by issues related to emulsion stability and catalytic efficiency. This study introduces an innovative Pickering emulsion system, utilizing high-acid value oils as the oil phase and natural deep eutectic solvents (NADES) as the aqueous-like phase. The interface was stabled by modifying SiO2 nanoparticles that were functionalized with 3-aminopropyltriethoxysilane (APTES) following the immobilization of CALB@SiO2-APTES (Candida antarctica Lipase B, CALB). CALB@SiO2-APTES served a dual role both an emulsifier and a biocatalyst in esterification reactions. Significantly, O/NADES Pickering emulsion demonstrated exceptional catalytic efficiency when applied to high-acid crude oils, exhibiting a 5.2-fold increase compared to the Novozym 435 system. Moreover, the substrate scope of O/NADES Pickering emulsion was also elucidated. We further investigated the recovery of Pickering emulsion, observing no significant decline in catalytic efficiency after 5 batches. This study affords a versatile platform that enables the exploration of new frontiers in Pickering emulsion catalysis.