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

Highlights: • A Cu nanoparticle/3D RGO nanocomposite is reported for PDS activation. • PDS activation with Cu/RGO shows high activity and mineralization ratio for 2,4-dichlorophenol. • The Cu/RGO shows high reactivity to aromatic compounds with hydroxyl and chlorinated groups. • Cu(III) is proposed to be the main reactive oxidant in Cu/RGO/PDS system. 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.