Preparation and properties of poly (ether sulfone) (PES)/mesoporous silica (MS) composite membranes for diffusion dialysis

PES/P(SSS-co-AA) composite membranes with -SO₃ − /-COO − were fabricated via in-situ copolymerization; • Carboxyl-functionalized mesoporous silica (CMS) was incorporated to form ion transportation channels; • The obtained composite membranes exhibited outstanding OH − permeability (U OH ) and selectivity (S). The practical application of poly (ether sulfone) -based cation-exchange membranes in alkaline diffusion dialysis is severely constrained by the intrinsic permeability-selectivity trade-off. Herein, mesoporous silica (MS) and carboxyl-functionalized mesoporous silica (CMS) nanoparticles are doped into the PES/P(SSS-co-AA) matrix via an in-situ blending strategy to fabricate a series of composite membranes for overcome trade-off. Separation performance is evaluated by diffusion dialysis (DD) tests in a NaOH/Na 2 WO 4 system. The results indicate that CMS incorporation significantly enhanced the membrane hydrophilicity. The optimized membrane with 6 wt% CMS loading achieves a hydroxide dialysis coefficient (U OH ) of 0.013 m/h and a separation factor (S) of 40.6. Compared with the unmodified MS-filled membrane (M6, S = 36.0), the CMS membrane (C6, S = 40.6) exhibits a 13% enhancement in ion-selectivity. In contrast to the pristine membrane (M0, S = 26.4), MS and CMS-modifications increase the separation selectivity by approximately 37% and 54%, respectively. The enhanced separation performance is attributed to the synergistic effect of negatively charged carboxylate groups (–COO − ) and hydrogen-bonding networks. The coexistence of Donnan exclusion toward WO 4 2− and accelerated OH − transport via the Grotthuss mechanism effectively alleviates the intrinsic permeability-selectivity. Download: Download high-res image (164KB) Download: Download full-size image