Ferrate(VI) based chemical oxidation for the remediation of aged PCB contaminated soil: Comparison with conventional oxidants and study of limiting factors

•Fe(VI) oxidant is more efficient than conventional oxidants in PCBs removal.•Combined Fe(VI)/HSO5− treatment can remove approximatively 40% of PCBs.•High carbonates content negatively affects the action of Fe(VI) oxidation.•The soil matrix has a strong impact on efficiency of ferrate(VI) oxidation.