Pervaporation performance and characterization of organosilica membranes with a tuned pore size by solid-phase HCl post-treatment

Organic–inorganic hybrid silica membranes were prepared from 1, 2 bis (triethoxysilyl)ethane (BTESE) by sol–gel processing at temperatures as low as 100°C, followed by solid-phase HCl-assisted post-treatment to tune the silica network by reducing the pore size. The Brunauer–Emmett–Teller (BET) surface area, thermogravimetric (TG) and positron annihilation lifetime (PAL) showed reduced pore sizes and a densified network structure of BTESE powder after the HCl-assisted treatment. The HCl-assisted treatment increased the permeance ratios of both He-to-N2 and He-to-C3H8, while the permeance of He was decreased. During the pervaporation (PV) dehydration of a 90wt% (wt%) isopropanol (IPA) aqueous solution at 75°C, a BTESE membrane fired at 100°C with HCl treatment showed a stable PV water flux of 2.46kgm−2h−1 and a separation factor of 3960 for more than 80h, confirming the successful preparation of BTESE membranes at low firing temperatures. The BTESE-derived silica networks were successfully and easily controlled by this novel HCl-assisted post-treatment. [Display omitted] •BTESE membranes were prepared at 100 to 300°C by sol–gel method on α-Al2O3 support.•BTESE membrane fired at 100°C showed a PV water flux of 3.41kgm−2h−1 with α of 230.•Solid-phase HCl post-treatment was applied to tune BTESE membrane pore size.•PV water flux kept constant while α increased from 230 to 3960 after HCl treatment.•PAL and BET results proved successful tuning of pore size via solid-phase HCl treatment.