High flux and ultra‐thin poly‐dimethyldiethoxysilane/poly(vinylidene fluoride) composite membrane for alcohols recovery from aqueous solution by pervaporation

Abstract

AbstractPervaporation (PV) of membrane separation technology has become an efficient approach to separate alcohols from aqueous solution. In this study, focusing on increasing the total flux and breaking the trade‐off in PV, an ultra‐thin and high flux poly‐dimethyldiethoxysilane (PDMDES)/poly(vinylidene fluoride) (PVDF) composite membrane was prepared. By employing various means, the characterizations of PDMDES/PVDF composite membrane were extensively investigated and the promising results indicated the high hydrophobicity and good affinity to alcohols. To be specific, PDMDES selective layer with different thicknesses, the thinnest of which was approximately 265 nm, were fabricated, and better PV performance can be achieved in a thickness range of 1.10 ~ 1.69 μm. The optimal PV performance of PDMDES/PVDF composite membrane was obtained in separating methanol from 5 wt% methanol/water solution at 40°C, resulting in a total high permeation flux of 5.38 kg m−2 h−1 and a higher pervaporation separation index (PSI) of 18.63 kg m−2 h−1.Highlights The ultra‐thin and high flux composite membranes for alcohols recovery via pervaporation (PV) are prepared by using monomer in membrane preparation through a simple fabrication method. The trade‐off is broken in the ultra‐thin composite membrane compared with traditional composite membrane. The influence between membrane thickness and PV performance is investigated through experimental tests, and the results show that the ultra‐thin composite membrane has a total high permeation flux of 5.38 kg m−2 h−1.