Review of the recent six-year chlorination resistance strategies of polyamide reverse osmosis and nanofiltration membrane

Polyamide reverse osmosis (RO) and nanofiltration (NF) membranes are widely used for water treatment, but their sensitivity to chlorine remains a key issue. Excessive chlorination damages polyamide membranes and affects their long-term performance. Chlorine resistance strategies need to be proposed for the chlorination mechanism under different chlorination conditions. Although polyamide chlorine-resistant membranes for RO and NF are developing rapidly, there is no comprehensive review of recent works, and previous reviews have not sorted out the chlorination mechanisms under different conditions. After a brief overview of polyamide thin film composite (PA-TFC) membranes, this paper comprehensively summarizes the chlorination mechanisms of conventional poly(diamine) amides and poly(piperazine) amides. Then, recent advances in improving the chlorine resistance of polyamide RO and NF membranes over the last six years are discussed. Finally, based on the limitations of the current research process and research materials, this paper proposes directions for future research, such as enhancing the synergistic effect of chlorine resistance and anti-biofouling, and optimizing the chlorine resistance evaluation system. This paper aims to provide a comprehensive theoretical basis as well as new insights and practical guidance to optimize membrane performance in applications. • Comprehensive summary of the chlorination mechanisms of PA-TFC membranes under different chlorination conditions • Chlorine-resistance modification strategies over the past six years are summarized. • Evaluation and comparison of various modification techniques to improve chlorine resistance • Challenges and outlook for advancements of chlorine resistance in PA-TFC RO and NF membranes are elaborated.