Sustaining RO membrane performance in chlorinated environments: from fabrication to restoration

ABSTRACT

Schematic overview divided into two sections. Left panel illustrates fabrication strategies for chlorine-resistant membranes: monomer replacement, bulk doping, surface coating, and chemical grafting. Right panel illustrates repair strategies for chlorine-damaged membranes: chemical reductive regeneration, external and embedded defect sealing, and reversible sacrificial layer regeneration.

With the escalating global freshwater scarcity, reverse osmosis (RO) membranes have become the most widely adopted technology for seawater desalination. However, aromatic polyamide RO membranes are highly sensitive to active chlorine, and chlorine disinfection induces irreversible membrane degradation, severely restricting long-term stable operation. As chlorine disinfection remains irreplaceable in RO pretreatment, enhancing polyamide chlorine resistance and extending membrane lifespan are critical to cost reduction. This review adopts a full-lifecycle perspective to establish a framework from proactive resistance enhancement to post-damage repair. Fabrication strategies are classified into monomer replacement, bulk doping, surface coating, and chemical grafting, comparing their chlorine resistance, mechanisms, and engineering feasibility. For damaged commercial membranes, four restoration approaches-chemical reductive regeneration, surface defect sealing, embedded responsive self-healing, and reversible sacrificial-layer regeneration-are reviewed, delineating their applicable damage thresholds and limitations. Future directions targeting complex chlorine damage mechanisms and durable repair strategies are outlined, providing theoretical guidance for sustainable chlorine-resistant RO membrane deployment.