FeC2O4•2H2O enables sustainable conversion of hydrogen peroxide to hydroxyl radical for promoted mineralization and detoxification of sulfadimidine

Abstract

Safe treatment of antibiotics requires efficient removal of both antibiotics and their degraded intermediates. In this study, we demonstrate that FeC2O4•2H2O enables the more sustainable conversion of H2O2 to •OH than commonly used FeSO4•7H2O, promoting the detoxification of a typical antibiotic sulfadimidine. It was found that the FeC2O4/H2O2 system could completely degrade 250 mg L−1 of sulfadimidine within 40 min at pH 3.0, along with decreasing the contents of chemical oxygen demand and total organic carbon by 295.0 and 33.5 mg L−1, respectively, more efficient than those in a classical Fenton system (FeSO4/H2O2). Analysis of sulfadimidine degraded intermediates and toxicity evaluation suggested that the FeC2O4/H2O2 treatment could more effectively decrease the overall toxicity of the sulfadimidine solution than the FeSO4/H2O2 counterpart. The sustainability of FeC2O4•2H2O in H2O2 conversion to •OH was attributed to its controlled release of Fe2+ into the solution to prevent the quenching of •OH by excessive Fe2+, as well as the simultaneous release of C2O42− to complex with Fe2+ and Fe3+, which could inhibit iron sludge formation and accelerate Fe3+/Fe2+ redox cycle. This study provides a promising Fenton system for the safe treatment of antibiotics and sheds light on the potential of FeC2O4•2H2O in environmental remediation.