Poly(vinyl alcohol)-based highly permeable TFC nanofiltration membranes for selective dye/salt separation

Loose nanofiltration (LNF) membranes possessing high water permeance and outstanding dye/salt selectivity are highly desirable for fractionating dyes and salts for textile wastewater . Herein, inexpensive and nontoxic poly(vinyl alcohol) (PVA) was utilized as an aqueous monomer via interfacial polymerization to fabricate novel highly permeable LNF membranes upon activation by sodium hydroxide . Systematic chemical and structural analyses indicated that the prepared polyester membrane formed was loose, hydrophilic , and negatively charged. The properties of the LNF membranes were optimized by adjusting the curing temperature (70 °C–100 °C). The optimized PVA-based membrane (PVA-M70°C) showed excellent water permeability (52.6 L m −2  h −1  bar −1 ), favorable dye rejection (> 90.0 %) and low salt rejection (NaCl and Na 2 SO 4 rejection rates were lower than 5 % and 18 %, respectively). Furthermore, the PVA-M membrane demonstrated excellent antifouling properties and long-term stability. Considering the biodegradable nature and low cost of PVA, PVA-based polyester membranes show great promise for LNF membrane production on an industrial scale. This work advances the use of PVA as a green aqueous monomer in fabricating highly permeable LNF membranes for efficient dye/salt selectivity .