Hierarchically structured cellulose triacetate-based membrane via gel-regulated interfacial polymerization for desalination

The easily compacted filter layer, low water flux, and rapid flux decay remain bottlenecks for cellulose triacetate (CTA)-based reverse osmosis (RO) membranes for desalination. Focusing on these issues, hierarchically structured CTA-based membranes were fabricated by embedding sodium alginate (SA) gel as the interlayer between CTA (DMSO as solvent) and polyamide (PA) layers via gel-regulated interfacial polymerization (IP). The SA gel regulates the diffusion rate of phenylenediamine and the IP rate, reducing the PA layer's cross-linking with an ideal thickness and proper surface roughness. Notably, the resulting RO membranes exhibited a high salt rejection rate of 96.87 % and an enhanced water flux from 11.80 L m −2  h −1 to 15.78 L m −2  h −1 after the addition of 0.1 wt% SA gel, surpassing that of some previously reported CTA-based RO membranes. More importantly, the hierarchically structured CTA-based RO membrane, which was not readily compatible, presented prominent potential free chlorine resistance with the enhanced water flux of 17.80 L·m −2  h −1 and desirable stability over 700 min. Overall, this study offers a new paradigm for the high-performing CTA-based RO membranes for desalination. Synopsis As for the ‘trade-off’ drawback between salt rejection and water flux, this study provide a new paradigm for hierarchically structured CTA-based RO membranes posing high salt rejection while maintaining an increased water flux, exceeding that of some previously reported CTA-based RO membranes.