Oxidation of phenol by green rust and hydrogen peroxide at neutral pH

The reactions involving green rusts (GRs), mixed ferrous–ferric oxides, remain poorly described relative to other iron oxides minerals which have been studied much more extensively. While the role of GRs in the reduction of chlorinated solvents and inorganic contaminants has been investigated, no work has appeared concerning the use of GR to promote Fenton reaction and oxidize organic pollutants.In this study, the catalytic ability of synthetic chloride green rust GR(Cl) was examined by employing the phenol as a model compound for the Fenton-like oxidation at neutral pH. For both tested concentrations of GR (5 g L−1 and 10 g L−1), rapid removal of phenol was observed when H2O2 was added. In GR water suspension, about 62% of phenol was mineralized after 24 h in the presence of H2O2 (155 mM) and GR (10 g L−1), at pH 7. In GR/H2O2 system, HPLC analysis showed that phenol had been transformed after 1 min mainly into catechol and hydroquinone, which corroborates with a Fenton reaction taking place in this system.