Preparation of magnetic biochar and its catalytic role in degradation of Cu-EDTA by heterogeneous Fenton reaction.

In this study, magnetic biochar (Fe-BC) was synthesized from phoenix tree leaves and FeSO4·7H2O by impregnation-pyrolysis method, and was used to activate H2O2 to degrade Cu-EDTA. The effects of preparation parameters on the degradation of Cu-EDTA by Fe-BC/H2O2 system were investigated by degradation experiments and characterization methods (SEM, BET, FTIR, XRD and XPS). The results showed that the magnetic biochar prepared under the pyrolysis temperature of 400 °C, pyrolysis time of 3 h and iron content of 3 wt% had the best catalytic activity. Within 120 min, the breaking efficiency of Cu-EDTA binding, precipitation efficiency of Cu2+ and removal efficiency of TOC could reach 78.48, 71.65 and 46.54% at the conditions of adding 1.0 g/L magnetic biochar and 25 mM H2O2 and the iron dissolution was only 0.32 mg/L. The characterization results and comparison experiments demonstrated that the catalytic effect of magnetic biochar not only depends on the transfer of electrons to H2O2 by the loaded iron oxides, but also the active oxygen functional groups (OFGs) and persistent free radicals (PFRs) contained on the surface can transfer electrons to H2O2 or even dissolved oxygen to produce an amount of hydroxyl radicals (·OH) and superoxide anion radicals (O2·-).