Oxidation absorption of nitric oxide from flue gas using biochar-activated peroxydisulfate technology

•Biochar-activated peroxydisulfate system is used for the first time to oxidize NO from flue gas.•NO is mainly removed by the produced free radicals such as ·OH and SO4−·.•·OH is identified as the first important free radical for oxidizing NO.•SO4−· is determined to be the second important free radical for oxidizing NO.•The maximum NO removal efficiency is up to 95.2%.