Graphene oxide-polyvinyl alcohol nanofiltration membranes for efficient dye removal in practical conditions

Removing organic dye in industrial wastewater requires developing advanced membrane technology using simple filtration methods. Graphene oxide (GO) has emerged as a promising two-dimensional material for fabricating high-performance nanofiltration membranes. Previous studies on GO-based membranes have reported efficient removal of dye within relatively low feed concentrations. Here, we modified GOMs with a hydrophilic and neutral polymer of polyvinyl alcohol (PVA) via a simple and scalable dead-end filtration method. Under practical industrial conditions with a feed dye concentration of 100 ppm, the PVA-coated GOMs (GPMs-C) exhibit over 99 % removal of small molecular dyes, i.e. methylene blue (MB) and alizarin red S (ARS). Moreover, GPMs-C exhibits promising stability after 144 h of long-term filtration, with rejection rates remaining at >80 % and >95 %, respectively, for MB and ARS. Via in-depth analysis, we propose that the size exclusion mechanism mainly contributes to the high rejection of GPMs-C. Our study highlights the filtration properties of polymericcoated GO-based membranes and demonstrates its promising potential for next-generation membrane technology addressing industrial-level applications.