Removal of Eriochrome Black T by sulfate radical generated from Fe-impregnated biochar/persulfate in Fenton-like reaction

[Display omitted] •A Fe impregnated biochar catalyst (Fe-BC) was evaluated in Fenton oxidation using sulfate radical.•Optimal ratio of Fe-BC:persulfate (PS):EBT was 0.50:0.27:0.10g/L.•Removal rate of EBT in Fenton-like reaction with Fe-BC/PS within 2h was 85–88%.•Catalytic activity by sulfate radical was influenced by iodide, phosphate and humic acid.•Sulfate radical generated from PS was much stronger than the hydroxyl radical induced from H2O2. A new heterogeneous Fenton catalyst, Fe-impregnated biochar catalyst (Fe-BC) was synthesized and evaluated in detail for its catalytic activity with sulfate radical under various conditions. The optimum conditions for the removal of Eriochrome Black T (EBT) by Fe-BC were determined as 0.27g/L K2S2O8 (PS) and 0.5g/L Fe-BC for 0.1g/L EBT, and which resulted 85–88% removal efficiency within 2h. The effective oxidation of EBT was observed over a pH range of 2–4 and temperature of 25–45°C and maintained EBT removal efficiency of 77.6–92.7%. Under optimum conditions, the catalytic activity was faster in the order of PS>PS+HP>H2O2 (HP) >>Fe-BC (without oxidants). The catalytic activity of Fe-BC for EBT can be identified in two stages, which occur rapidly within 30min (1st stage) and followed by slow oxidation until 120min (2nd stage). Catalytic activity by sulfate radical was also dominantly influenced by other pollutant such as iodide, phosphate and humic acid. Overall, the sulfate radical generated from Fe-BC/PS was found more economical with strong oxidation efficiency for use in Fenton-like reaction for treating organic pollutants compared with conventional Fenton reaction with H2O2.