Surfactant effects on polyamide thin-film composite membranes fabricated by co-solvent assisted interfacial polymerization

The water treatment industry has faced growing challenges due to increasing demand and pollution, emphasizing the need for advanced membrane-based technologies. Reverse osmosis (RO) has gained attention for seawater desalination, drinking water production, and wastewater treatment. However, limited research has been conducted on RO membranes tailored for these applications. In this study, polyamide (PA) thin-film composite RO membranes were fabricated using co-solvent assisted interfacial polymerization (CAIP). m-Phenylenediamine (MPD) and trimesoyl chloride (TMC) were used as monomers, and sodium dodecyl sulfate (SDS) was introduced into the aqueous phase to enhance miscibility between the aqueous and organic phases. The supporting layers were prepared using polysulfone (PSf), NMP, and lithium chloride (LiCl) on non-woven substrates. The effects of SDS on membrane morphology, hydrophilicity, and performance were systematically evaluated. Membranes fabricated via CAIP showed improved surface morphology, higher water flux, and comparable or enhanced salt rejection compared to those made by conventional IP. The optimized membrane with 0.1 wt% SDS achieved up to 95 % salt rejection and high permeability, confirming that SDS addition effectively tuned the membrane structure. These findings demonstrated the potential of CAIP membranes for efficient and sustainable water treatment applications.