Reinforced graphene oxide–acrylamide/sodium acrylamide hydrogel composite-coated meshes for the separation of stabilized oil–surfactant emulsions from greywater

Abstract

Kitchen greywater, which is high in fats, oils, and grease (FOG), as well as surfactants, poses a significant environmental threat due to its ability to contaminate water sources and impair wastewater infrastructure. In this study, a reinforced composite hydrogel composed of acrylamide (AM), sodium acrylate (Na-Ac), and graphene oxide (GO) is synthesized via graft polymerization and applied as a coating over stainless-steel meshes with various pore sizes (200, 255, and 405 µm) to treat oil/surfactant/water mixtures. Experiments are conducted with various acrylamide (AM) compositions (50, 55, and 60 wt%) and graphene oxide (GO) loadings (10, 20, and 40 mg) to investigate the influence of composition and mesh size on the separation efficiency. Oil removal efficiency as high as 89% and surfactant removal up to 80% were achieved with the proposed hydrogel membranes The statistical models yielded near-ideal fits for both responses (R² = 0.9994 for oil removal and R² = 1.000 for surfactant removal), indicating excellent predictive reliability across the tested formulation and operating conditions. These findings suggest that the AM/GO hydrogel-coated mesh can be effectively tuned to target either oil, surfactant, or combined removal, making it a promising candidate for compact or modular treatment units. In this way, the recovered water could be reused for secondary purposes, contributing to more sustainable kitchen wastewater management and supporting multiple Sustainable Development Goals (SDGs).

keywords: Acrylamide, Graphene oxide, Greywater treatment, Hydrogels, Membrane separation, Oil-surfactant emulsions.