Cleanable natural-sugar-alcohol-based polyester membrane for highly efficient molecular separation

Achieving zero discharge of salt-containing dye wastewater is essential for sustainable development, which requires precise separation of organic dyes and inorganic salts. This work describes a new strategy for the preparation of cleanable polyester loose nanofiltration (LNF) membranes using inexpensive natural-sugar-alcohols (erythritol, sorbitol, and maltitol) as aqueous monomers. The resulting polyester membrane has a loose structure with hydrophilic properties and negative charge density. The optimized sorbitol/trimesoyl chloride (TMC) membranes exhibited high pure water permeability (80.63 ± 1.72 L·m−2·h−1·bar−1), a high selectivity factor for salt/dye separation at 229.07(dye rejection of 99.6 ± 0.48%, salt rejection of 8.17 ± 0.8%). Moreover, Sorbitol/TMC polyester membranes exhibit excellent compatibility with dye-fouling detergents, antifouling ability, and long-term stability. The unoptimized erythritol/TMC and maltitol/TMC membranes also exhibit high water permeability and accurate dye/salt sieving ability. The results reveal that natural-sugar-alcohol-based polyester membranes are expected to stand out in the future of salt-containing dye wastewater treatment.