Photocatalysis and micro-electrolysis featured floatable solar-driven interfacial purifier toward phenolic wastewater

This study fabricated a floatable silicate-based photothermal porous composite using nano-Fe, nano-TiO₂, carbon dots, cenospheres, NaHCO₃, and bentonite as main raw materials. Serving as an efficient solar-driven interfacial purifier (SIP) for phenolic wastewater, it integrates photocatalysis and micro-electrolysis, with excellent buoyancy, thermal insulation, light absorption, water uptake, and reduced water evaporation enthalpy-enabling a high water evaporation rate of 1.67 kg•m^-2•h^-1. Ball-milling of nano-Fe, nano-TiO₂, and carbon dots optimized the composited powder's surface area and metallic iron content for superior micro-electrolysis. The coupled photocatalysis/micro-electrolysis generated diverse active radicals to degrade phenol via multiple pathways, while water evaporation enhanced these reactions by inducing high-speed flow around the micropore's mouth. Under 1.0 kW•m^-2 solar irradiation for 4 h, the condensate achieved 90.7% phenol removal and 82.36% total organic carbon (TOC) removal. The floating SIP also purified residual water simultaneously, reaching an overall TOC removal ratio of 78.28% (4.9 times that of the separating SIP's 19.6%) and effectively removing hazardous intermediates under the convection flow. Additionally, the floating SIP performed well in purifying various phenolic pollutants. This floating solar-driven interfacial purification system would contribute to a novel strategy for high-quality treatment of the phenolic wastewater.