Polydopamine-modified magnetic foam composites synergistically activate peroxymonosulfate with visible light for sulfadiazine degradation and oil–water separation

This study used a CuSO4/H2O2 catalyst to accelerate the oxidation and polymerization of dopamine in solution to facilitate the rapid deposition of polydopamine (PDA) onto a melamine foam. Dopamine provided the Fe3O4 adhesive layer and additional photocatalytic electron transfer channels for the foam. Stearic acid (SA) was used as the final incorporation on the surface of melamine foam(MF) to further superhydrophobically modify the magnetic foam (MF@PDA/Fe3O4) to obtain superhydrophobic magnetic MF@PDA/Fe3O4@SA foam. The foam has excellent capacity, acid resistance, alkali resistance, flame retardant, and salt resistance and can be conveniently separated, recycled, and recovered using magnetism. At the same time, peroxymonosulfate (PMS) can be activated to generate super-active radicals. Within 16 min, the degradation rate of sulfadiazine (SDZ) reached 99.8 %. Trapping experiments and EPR analysis confirmed the critical roles of ·OH, ·SO4− and 1O2 in SDZ removal. The wide pH working range (1.0 ∼ 13.0) and the slight toxicity of photocatalytic intermediates indicate that the as-prepared MF@PDA/Fe3O4@SA/PMS system has good application potential. The foam has potential practical applications in emergency oil spill rescue and oil/organic solvent wastewater treatment. Furthermore, this study provides a promising strategy for designing and fabricating a novel magnetic foam and photoactivated PMS synergistic system to eliminate pharmaceutical antibiotics effectively.