Stainless steel mesh supported thin-film composite nanofiltration membranes for enhanced permeability and regeneration potential

Highly permeable desalination nanofiltration (NF) membranes with regeneration properties are of great demand in water treatment. To improve the permeability and the regeneration performance while maintaining high salt rejections of the NF membranes, a thin polyamide (PA) film was constructed on the polyvinyl alcohol (PVA) decorated stainless steel mesh (SSL) support for the first time. SEM, AFM, Raman and XPS analyses were conducted to characterize the surface morphologies and chemical structures of the sandwich textured NF membrane (PA-SSL). An integrated surface and structural feature for a typical polyamide NF membrane were observed. The separation performance test further verified the excellent properties of the PA-SSL membrane. A superior separation performance with 45.8 L m−2 h−1 bar−1 water permeability and 98.9% Na2SO4 rejection was achieved, which was much better than NF90, NF270, and other reported highly permeable NF membranes in literatures. Long-term cross-flow operation and reverse filtration tests demonstrated the excellent stability of the resultant membrane. Importantly, the organic polymer layers on the SSL support could be completely removed by calcining, and a fresh polyamide layer could be formed via a recoating method, rendering the PA-SSL membrane with great regeneration potential. The regenerated membranes possessed excellent separation performance as an original one even under 5 cycles of regeneration. Therefore, the calcination and recoating strategy in this work broadens a novel method for the fabrication of sustainable TFC membranes with simultaneously improved permeability and regeneration potential for environmental desalination processes.