Enhanced peroxydisulfate oxidation via Cu(III) species with a Cu-MOF-derived Cu nanoparticle and 3D graphene network

The contribution of Cu(III) produced during heterogeneous peroxydisulfate (PDS) activation to pollutant removal is largely unknown. Herein, a composite catalyst is prepared with Cu-based metal organic framework (Cu-MOF) derived Cu nanoparticles decorated in a three-dimensional reduced graphene oxide (3D RGO) network. The 3D RGO network overcomes the aggregation of nanosized zero-valent copper and reduces the copper consumption during the PDS activation reaction. The Cu/RGO catalyst exhibits high catalytic activity for 2,4-dichlorophenol (2,4-DCP) degradation in a wide pH range of 3-9, with a low Cu dosage that is only 0.075 times that of previous reports with zero-valent copper. Moreover, a high mineralization ratio (69.2 %) of 2,4-DCP is achieved within 30 min, and the Cu/RGO catalyst shows high reactivity toward aromatic compounds with hydroxyl and chlorinated groups. Unlike normal sulfate radical-based advanced oxidation, alcohols show negligible impacts on the reaction, suggesting that Cu(III), rather than SO₄^- and OH, dominates the degradation process. We believe that PDS activation by 3D Cu/RGO, with Cu(III) as the main active species, provides new insights in selective organic pollutant removal in wastewater treatment.