Enhanced degradation of benzene in aqueous solution by sodium percarbonate activated with chelated-Fe(II)

•Benzene degradation performance in CA/SPC/Fe(II) system is investigated.•The primary reactive oxygen species for benzene degradation are HO and O2-.•The additions of CIT and OA ensure high benzene removal at wider pH range.•The additions of CIT and OA can eliminate the adverse effect of HCO3−.•Effective oxidation of benzene in actual groundwater is achieved.