Nano-sized magnetic iron oxides as catalysts for heterogeneous Fenton-like reactions-Influence of Fe(II)/Fe(III) ratio on catalytic performance

► Nano-sized Fe(II, III) oxides tested as catalysts for heterogeneous Fenton reaction. ► All showed relatively low catalytic activity for phenol oxidation at neutral pH. ► Fe(II)-containing oxides (e.g. magnetite) not stable in presence of H2O2 but oxidized. ► Residual Fe(II) content in the catalyst core is of minor benefit for catalytic activity. ► Selectivity of oxidation tested with structurally distinct compounds.