Fabrication of polyamide thin-film nano-composite (PA-TFN) membrane with hydrophilized ordered mesoporous carbon (H-OMC) for water purifications

To enhance the performance of thin-film composite (TFC) membranes, nano-fillers are often used as additives in the polymerization process. Nano-fillers have to be hydrophilic to be dispersed in the aqueous phase to make thin-film nano-composite membrane (TFN) by interfacial polymerization. In this study, hydrophilized ordered mesoporous carbons (H-OMCs) were explored for TFN preparation. H-OMC was prepared from silica template, and argon atmospheric pressure plasma (APP) was applied to enhance surface hydrophilicity. m-Phenylenediamine (MPD) with trimesoyl chloride (TMC) was polymerized to make polyamide (PA) thin-film layer. The results indicated that 5% loading of H-OMCs increased membrane surface hydrophilicity, wettability and pure water permeability. Measurement of bovine serum albumin (BSA) adsorption on the membranes showed that with increasing H-OMCs loading, BSA adsorption was decreased. The enhanced membrane surface hydrophilicity might have contributed to the decreased BSA adsorption. With increasing amounts of H-OMCs up to 6%, rejection of monovalent ion (NaCl) was reduced from 68% to approximately 50%, but the rejection of divalent ions (Na2SO4) decreased only slightly from 94% to around 90%. Incorporation of the H-OMCs into the thin-film layer of the membrane did not change solution permeability in NaCl solution and slightly increased the solution permeability with Na2SO4. Overall, surface hydrophilicity, electrical properties and porous structure of the thin-films are significant factors limiting protein adsorption and enhancing membrane performances.