Nature-inspired construction of multifunctional composited membrane by in situ formation TA-APTES NPs for selective adsorption of tetrabromobisphenol a and oil-water separation

Abstract

In this work, a novel in-situ synthetic TA-APTES NPs multifunctional imprinted membrane was fabricated by tanning-inspired coating for selective adsorption of tetrabromobisphenol a (TBBPA) and oil-water emulsion separation. Tannic acid (TA) from natural plants can be cross-linked with 3-aminopropyltriethoxysilane (APTES) by a simple green method to form nanosphere structures with secondary reaction sites. With TA-APTES coating, the membrane can be quickly converted from hydrophobic to super-hydrophilic. TEOS is not only used as a cross-linking agent in imprinting process，but also can be used for TA-APTES hybridization on the membrane surface to introduce stable silicone hydroxyl groups to the membrane surface. The modified membranes showed good hydrophilicity with a water flux of 27,272Lm−2 h−1 at 0.1Mpa, which was 18 times higher than that of pure PVDF membranes. In addition, the separation efficiency of four different types of oil-water emulsions (n-hexane, petroleum ether, dichloromethane and kerosene) reached 99.6%, 98.3%, 95.6%, and 98.7%, respectively. Among them, the oil water emulsion flux of dichloromethane could reach 1000.1. what's more, the prepared membranes also maintained relatively high selective separation efficiencies of TBBPA in oil-water mixtures. To better explain the mechanism of the TBBPA reaction process, the active sites in the TBBPA reaction process were calculated and predicted by density generalization theory (DFT). The Br and phenolic hydroxyl groups on the benzene ring of TBBPA showed higher activity and might be the main reaction sites. In addition, the imprinted composite membranes can be easily regenerated and reused without performance loss through a simple cleaning process. The coating process inspired by natural polyphenol chemistry has the advantage of being green, cost-effective and low energy, showing real potential in multifunctional membrane applications.