Peroxydisulfate Activation for Efficient Degradation of Tetracycline by N-rGO/Fe 3 O 4 : Synthesis, Property, and Mechanism

In response to the high cost of activated persulfate technology, we have successfully prepared a composite catalyst N-rGO/Fe 3 O 4 for reuse through magnetic separation. The degradation efficiency of 60 mg/L tetracycline (TC) reached 100% within 120 min under optimal conditions (c[peroxysulfate, PDS] = 2 mM; m(PDS):m(N-rGO/Fe 3 O 4 ) = 1:6; pH = 3.0), while N-rGO/Fe 3 O 4 maintained a high stability and reusability value in the cycling experiment. We found that in the N-rGO/Fe 3 O 4 + PDS system, SO 4 − · and ·OH radicals were the most dominant reactants for TC decomposition, with non-radical reactions also contributing to TC degradation. Furthermore, we inferred four possible decomposition pathways of TC from the analysis of intermediates: (1) dehydration, (2) demethylation, (3) hydroxylation, and (4) deamidation. This study provides a new strategy for the effective treatment of antibiotic wastewater and hopes to be applied to the treatment of actual antibiotic wastewater in the future. Graphical Abstract