Vapor-permeation dehydration of isopropanol using a flexible and thin organosilica membrane with high permeance

Abstract

Ultrathin, defect-free organosilica membranes on porous commercialized polymeric nanofiltration membranes (polythersulfone, PES) were fabricated via flow-induced deposition (FD) with a rinse step. Herein, we compare the FD approach with and without the rinse step and describe the effect on the formation of BTESE layers, along with separation performances during the vapor permeation (VP) dehydration of isopropanol (IPA)/water solutions (IPA: 90 wt%). The rinse strategy of reducing the BTESE layer (less than 100 nm) effectively enhanced the membrane permeance without compromising selectivity. The rinsed membrane showed high water permeance (1.8 × 10−6 mol m−2 s−1 Pa−1) that almost equaled that of a polymeric support (2.0 × 10−6 mol m−2 s−1 Pa−1), and a separation factor of about 800 for this VP process at 105 °C (1.1 wt% IPA in the permeate side). Moreover, these membranes demonstrated stable permeation properties under surroundings that included both vapor and liquid for the VP and pervaporation dehydration of IPA/water mixtures under high temperature. The membranes also demonstrated fine flexibility in a vast array of bending radii (more than 1.5 mm). This work has shown that the rinse process is an effective strategy for fabricating an ultrathin organosilica top layer on porous polymeric supports via the FD approach.