Extending the applicability of concentration polarization-enabled “click” hydrogel coating of desalination membranes

Reverse osmosis (RO) systems continually struggle with membrane fouling, leading to diminished membrane permeability and therefore elevated energy requirements. Building on prior own research, this study presents further development of an in situ antifouling coating technique for commercial RO flat sheet membranes and spiral-wound modules, deploying a concentration polarization-driven reactive (“click”) coating formation process. Utilizing this approach, zwitterionic (self-synthesized polyacrylates) and nonionic (functionalized “clickable” poly(vinyl alcohol)) coating materials were employed. Relying on comprehensive statistical analysis and the design of experiments (DOE) framework for lab-scale experiments, essential parameters that dictate the efficiency of the coating process were identified. By modulating the extent of concentration polarization, precise control over the permeance of modified membranes and spiral-wound modules was achieved. A robust correlation emerged between the relative permeance change (RPC) post-modification and the relative end permeance change (REPC) during modification. This correlation serves as basis for the real-time prediction and adjustment of final membrane performance, enabled by online flux monitoring during the modification and stopping it a preset REPC value—a relationship substantiated through extensive experiments on both lab-scale and pilot plant platforms. In performance comparisons, the modified membranes consistently surpassed unmodified variants in both selectivity and antifouling resilience. With successful upscaling to commercial TW30-2521 modules in a pilot plant setting, a significant step toward industrial readiness has been made. Overall, this work introduces a scalable, predictable, and controllable in situ coating method for RO membranes and modules that enables balancing enhanced anti-fouling functionality with preserved flux performance at uncompromised solute rejection. • “Clickable” polyzwitterion or polyvinylalcohol for antifouling coatings • Lab-scale validation and optimization of filtration-driven reactive coating • Correlation between flux during coating and permeance of coated membrane • Model-based adjustment of coating thickness and resulting performance • Transfer to antifouling coating of spiral-wound membrane module