Enhancing antifouling properties of polyamide-based thin-film composite membranes using oxidized polyquaternium-10 via schiff base grafting

Abstract

Addressing the urgent global challenge of water scarcity underscores the critical importance of enhancing polyamide (PA) reverse osmosis (RO) membranes, which are essential for efficient water purification. This study introduces a novel approach by utilizing oxidized polyquaternium-10 (OPQ-10), a hydrophilic and positively charged aldehyde-based cellulose derivative, grafted onto the PA membrane surface through Schiff base reactions. This method specifically targets amino groups to significantly enhance fouling resistance, leading to improved performance against contaminants such as bovine serum albumin (BSA), sodium alginate (SA), and dodecyl trimethyl ammonium bromide (DTAB). Noteworthy advancements include a marked increase in hydrophilicity and surface smoothness, alongside significant improvements in surface charge properties. Specifically, water contact angle decreased dramatically from 64.5° to 36.9°, root mean square roughness reduced from 118.0 nm to 99.7 nm, and the isoelectric point shifted from pH 4.95 to 7.19. These modifications not only bolster the antifouling capabilities of the membranes but also significantly enhance membrane durability under extreme pH conditions. Moreover, without substantial reductions in flux, the sodium chloride (NaCl) rejection improved from 96.6 % to 98.4 %, and it maintained consistent rejection and flux throughout a 300-h long-term performance test. The findings highlight the pivotal role of surface chemistry modifications in extending the functional lifespan of PA membranes and provide robust guidelines for their application in industrial settings, offering a sustainable solution to meet the escalating demands for clean water.