Nanocomposite UF membrane of PVC/nano-silica modified with SDS for carwash wastewater treatment

This study presents an investigation of a novel fouling-resistant mixed matrix membrane (MMM) composed of ultrafiltration PVC incorporating silica nanoparticles modified with sodium dodecyl sulfate (SiO₂-SDS) for carwash wastewater treatment. The hydrophilic SiO₂-SDS was synthesized by modifying SDS molecules onto the surfaces of silica nanoparticles (SiO₂ NPs). Later, SiO₂-SDS NPs were incorporated into a PVC polymeric matrix at an optimized ratio. The prepared virgin membrane and MMMs were characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy-energy dispersive X-ray (SEM-EDX) spectroscopy, and atomic force microscopy (AFM). The results revealed that MMMs prepared with 0.15 wt% SiO₂-SDS NPs exhibited optimum characteristics and performance, where the highest thickness of 118.71 ± 0.42 μm and maximum porosity of 81.40 ± 0.23% were obtained. The pure water flux of this membrane reached 127.75 ± 1.72 L m⁻² h⁻¹, which is better than that of other modified membranes. This membrane achieved high removal of total suspended solids and chemical oxygen demand of 93% and 78%, respectively, when used with real carwash wastewater. Additionally, the 0.15 wt% SiO₂-SDS NPs exhibited stable performance during prolonged operation, resulting in the best flux recovery ratio of 80% among other tested membranes, signifying its superior fouling resistance bestowed by the hydrophilic nature of the incorporated SiO₂-SDS NPs.