Nanointerface engineering of leach-resistant hybrid graphene oxide-metal oxide-sand composites for sustainable removal of emerging pollutants

The practical deployment of photocatalytic nanomaterials in water treatment is hindered by catalyst leaching, nanoparticle aggregation, and poor long-term stability. Herein, we report a scalable nanointerface engineering strategy to construct hierarchical nano-micro composites by immobilizing graphene oxide (GO)-metal oxide hybrid coatings onto granular sand through a water-based, binder-assisted layer-by-layer assembly using polyvinyl alcohol as an interfacial linker. GO was hybridized with representative metal oxide photocatalysts (TiO 2 , W-TiO 2 , ZnO, and WO 3 ) to create heterostructured coatings with enhanced adsorption and photocatalytic activity. Comprehensive physicochemical characterization confirmed the uniform deposition and integration of the nanophases on the sand substrate without detectable structural degradation. Using triamterene as a model emerging pharmaceutical contaminant, TiO 2 -GO-sand achieved 87–90% removal under UV and visible-light irradiation while maintaining high performance (~ 100%) over a broad pH (3–8). Under optimized conditions, high removal efficiencies were also achieved for rhodamine B and methylene blue. Kinetic analysis followed pseudo-second-order behavior with apparent rate constants of 0.043–0.057 min − 1 . Radical scavenging tests revealed an adsorption-assisted photocatalytic mechanism dominated by synergistic •OH and •O 2− pathways, with adsorption contributing approximately 57% of the total triamterene removal. No detectable GO or TiO 2 leaching was observed after 12 months of continuous aqueous exposure, and the composite maintained stable performance over 20 regeneration cycles. Validation in hospital wastewater and river water further confirmed robust pollutant removal under realistic conditions. This work establishes a universal nano-micro interface engineering strategy for developing durable, scalable and environmentally-safe photocatalytic composites, advancing the practical implementation of nano-micromaterial-enabled water purification technologies.