HCl post-treatment and pervaporation performance of boron-doped organic silicon membrane for the dehydration of ethyl acetate/water mixture

Boron-doped silica membrane (B-SiO₂ membrane) was prepared using the sol-gel method, with 1, 2-bis(triethoxysiliconyl) ethane (BTESE) and boric acid as raw materials and ethanol as the solvent. The effects of the B/BTESE molar composition and feed liquid temperature on the structure and dewatering properties of the B-SiO₂ membranes were investigated. The results show that boron is successfully doped into the SiO₂ skeleton, Si-C-C-Si bond condensation forms lots of hydrothermal stable Si-O-B bonds and Si-O-Si bonds, resulting in an increase in surface hydrophilicity, a decrease in pore size and an improvement in pervaporation and dehydration performance. The B-SiO₂ membrane was subjected to HCl post-treatment to evaluate its long-term stability. Following boron acid modification and HCl post-treatment, all the SiO₂ membranes exhibited microporous characteristics with a decrease in the specific surface area and pore size. Although membranes’ thickness showed minimal variation, the pervaporation dehydration performance was substantially enhanced. After a 216 h long-term stability test, the membranes exhibited excellent performance, with a stable flux of 2.61 kg·m⁻²·h⁻¹ and a separation factor above 552.