Electrocatalytic degradation of benzohydroxamic acid in the mining beneficiation wastewater via ferrocene-organic framework cathode coupled with oxygen-contact system: Enhanced cycled bimetallic heterogeneous electro-Fenton process

The rapid expansion of the mining industry has posed challenges to water purification, as beneficiation wastewater containing persistent organic flotation reagents exhibits low biodegradability, necessitating targeted treatment strategies. Benzohydroxamic acid (BHA), as the most common mineral processing reagent, is difficult to be naturally biodegraded due to its oxime group and benzene ring structure. In this study, electro-Fenton degradation of BHA was performed with a novel electroresponsive bimetallic ferrocene-organic framework cathode (FcDA-Ni-Mn) synthesized through in-situ solvothermal method. The cathode comprises bimetal-doped catalytic centers and sandwich complex structure, exhibiting exceptional synergistic electrocatalytic activity. Driven by a voltage of 2.0 V, an electrically induced oxygen-contact reactor (180 mL) with FcDA-Ni-Mn/NiF achieved >90% BHA degradation (1 mmol/L) at the condition of pH 7.0, 1 mM H 2 O 2 , 50 mM/L Na 2 SO 4 within 60 min, reaching an excellent rate constant of 0.045 min −1 . The cycling and practical wastewater experiments revealed remarkable recyclability and practical applicability of FcDA-Ni-Mn. Mechanistic studies reveal that BHA degradation was primarily mediated by reactive oxygen species (·OH, ·O 2 − and 1 O 2 ), with oxidative cleavage occurring predominantly at the oxime group (N O) and its adjacent C C bond. This study elucidates the electro-degradation mechanism of BHA and demonstrates its potential as an effective technology for treating flotation reagents in aquatic environments.