Catalytic degradation of pharmaceutical and personal care products in aqueous solution by persulfate activated with nanoscale FeCoNi-ternary mixed metal oxides

Recently, pharmaceutical and personal care products (PPCPs) have received considerable attention for their potential risks to ecosystems and human health. In this work, nanoscale FeCoNi-ternary mixed metal oxides (TMMO) were prepared for activating persulfate (PS) to degrade PPCPs. 2,4-dihydroxybenzophenone (BP-1) was selected as a representative PPCP to test the effect of various operating parameters on removal efficiencies, including PS concentrations, catalyst dosages, pH and temperature. Since a synergistic catalytic effect was found between the transition metal elements, the FeCoNi-TMMO catalyst showed high catalytic activity, stability and recyclability. Moreover, the FeCoNi-TMMO/PS system exhibited excellent universality for various PPCPs. The electron paramagnetic resonance analysis confirmed that ^⋅OH, SO₄^⋅-, O₂^⋅- and ¹O₂ could all be generated in this system. Quenching experiments confirmed that these reactive oxygen species contributed to BP-1 removal, and O₂^⋅- played a crucial role. Based on these results, the possible mechanism of FeCoNi-TMMO activating PS was proposed. The degradation products of BP-1 were determined, and the transformation pathways mainly included hydroxylation, sulfate substitution reaction, polymerization and bond breaking reaction. Finally, the toxicity of the products was evaluated by the ECOSAR program. This work provides comprehensive insight into the FeCoNi-TMMO/PS system as a new strategy for PPCPs removal.