High temperature oil-water separation based on superwettable membranes for removing water from condensation reactions

With the rapid development of industry, oily wastewater has caused serious environmental problems. Highly efficient oil-water separation based on superhydrophobic materials holds promise; however, superhydrophobic surfaces often lose their superhydrophobicity when exposed to hot water. Consequently, oil-water separation under high temperature is rarely explored. Herein, a heat resistant superhydrophobic porous glass membrane is fabricated by the vapor phase growth of a network layer of silicone nanofilaments using economical ethyltrichlorosilane as the only surface modifier. The superhydrophobic porous glass membrane possesses hot water resistance and can be used for highly efficient separation of water from oil under high temperatures, regardless of the water/oil ratio, the composition of the oil, and the temperature. Taking advantage of the superior performance in oil-water separation at high temperatures, we successfully adopted such a superhydrophobic membrane for removing water from condensation reactions such as amidation and esterification reactions. It was demonstrated that both the reaction rate and the conversion can be improved significantly. The idea to use superhydrophobic oil-water separation materials for condensation reactions paves the way for industrial synthesis of amides and esters.