Activation of H2O2 by nano zero-valent iron (nZVI) enables fast sulfadiazine degradation: mechanistic insights and process optimization

Background Antibiotic contamination in aquatic systems demands advanced oxidation solutions. This study develops a nano zero-valent iron (nZVI)-activated peroxide system to address sulfadiazine (SDZ) persistence and associated ecological risks. Methods Structural properties of nZVI were analyzed by TEM/XRD. Process parameters were optimized through Box-Behnken design. Degradation mechanisms were investigated via radical quenching experiments, HPLC-MS analysis, and acute toxicity bioassays. ‌ Significant findings The system achieved complete SDZ (20 mg L⁻¹) removal within 5 min under optimal conditions (pH 2.44, 0.12 g L⁻¹ nZVI, 0.009% H₂O₂), showing strong agreement with pseudo-first-order kinetics (k = 0.637 min ⁻¹, R²=0.998). Hydroxyl radicals dominated SDZ degradation, generating 12 transformation products through amino oxidation, hydroxylation, and sulfonamide bridge cleavage. Toxicity reduction (60–90% EC50 improvement) confirmed effective detoxification. This work establishes nZVI-driven peroxide activation as a viable strategy for antibiotic wastewater remediation. Graphical abstract