Designing High-Performance Nanofiltration Membranes for High-Salinity Separation of Sulfate and Chloride in the Chlor-Alkali Process

Enormous demand exists for separation of high-salinity solutions across various industries, especially in those high-pollution businesses which are urgently looking for high-throughput and precise-selective nanofiltration (NF) membranes stably operating at elevated concentrations and other harsh environments. This work develops a novel NF membrane (i.e., high-performance thin-film composite (H-TFC)) through straightforward structure design instead of complex post-treatment to achieve high performance during high-salinity separation of sulfate and chloride ions. Through manipulating dope composition and coagulation bath temperature, unique macro- and microstructures of the H-TFC membrane were designed: (1) The substrate possesses the best ratio of the spongy and fingerlike layers, which not only provides low resistance transport channels to improve the membrane permeability (13.0 L m2– h–1 bar–1) but also ensures enough strength and minimum defects to treat high-salinity solutions. (2) The unique nominal p...