A novel pathway for high performance RO membrane: Preparing active layer with decreased thickness and enhanced compactness by incorporating tannic acid into the support

Abstract

We report a novel pathway for preparing polyamide (PA) thin-film composite (TFC) reverse osmosis (RO) membrane with high permselectivity by incorporating tannic acid (TA) into the polysulfone (PSf) support. The support and RO membrane were characterized systematically. The results showed that (1) the support surface was enriched with TA due to the high hydrophilcity of TA and (2) TA endowed the RO membrane with a thinner and more compact PA active layer. The influencing mechanism of TA on the PA layer formation was discussed. TA affected the formation of PA layer through changing the m-phenylenediamine (MPD) molecules absorption behavior and the formation of the nascent film. The RO membrane desalination performances for both brackish water and seawater were evaluated. Due to the thinner and more compact PA active layer, PSf/TA-RO (the membrane prepared on PSf/TA support) possessed a higher rejection and a comparative flux compared to PSf-RO (the membrane prepared on PSf support). This work provides an effective way for preparing high performance RO membranes via utilizing support to tailor the aqueous phase monomer absorption and the formation of the nascent film.