Tuning the Pore Structures of Organosilica Membranes for Enhanced Desalination Performance via the Control of Calcination Temperatures

Abstract

Microporous organosilica membranes based on 1,2-bis(triethoxylsilyl)ethane (BTESE) were fabricated via an acid-catalyzed sol-gel technique. In the preparation process, the calcination temperature plays a significant role in structural and surface properties of the organosilica networks. With an increase in calcination temperature, the surface hydrophilicity decreased due to the enhanced condensation of Si-OH groups in the networks. N2 adsorption results suggest that the pore structures of BTESE membranes was clearly dependent on the calcination temperature. The pore sizes of the membranes were quantitatively determined by using the Normalized Knudsen-based permeance (NKP) model. In pervaporation tests, the membranes with higher calcination temperatures showed higher salt rejections and lower water permeances, which was attributed to the changes in pore size and surface chemistry of pore walls. The BTESE membranes calcined at 200 °C exhibited superior hydrothermal stability in temperature cycles up to 70 °C and high reproducibility in concentration cycles with NaCl concentrations of 0.2–13 wt%, showing great promise for desalination applications of high-salinity water.

Bis(triethoxysilyl)ethane (BTESE)–Organosilica Membranes for H2O/DMF Separation in Reverse Osmosis (RO): Evaluation and Correlation of Subnanopores via Nanopermporometry (NPP), Modified Gas Translation (mGT) and RO Performance

“…All these three materials, BTESE, BTESEhy and BTESA, had similar bridge lengths with two carbon atoms, and the difference between these three materials was the degree of saturation of each bond (single, double and triple bond of each organic bridge) [ 46 ]. In addition, BTESE membranes also had been widely used in PV and VP for H 2 O/alcohols (e.g., EtOH, IPA, Butanol (BuOH) [ 47 , 48 , 49 , 50 ], H 2 O/NaCl [ 51 ], H 2 O/Acetic Acid (AA) [ 52 ], H 2 O/Ethyl Acetate (EA) [ 53 ] and H 2 O/Acetone (Ace) [ 54 ] separations. It should be noted that Dong et al directly compared the separation performance of PV and RO using the same membranes.…”