The efficiency of CWPO with iron minerals has been found to depend greatly on the dissolution of iron from the solid , , ,  and . Therefore, the iron mineral is used as dissolved iron source and the oxidation proceeds mostly via homogeneous Fenton. However, it has to be mentioned that the kinetics is considerably slower than that of conventional Fenton. Xue et al.  investigated the degradation of pentachlorophenol with magnetite under ambient conditions, analyzing the effect of some chelating agents, like ethylenediaminetetraacetic LY2157299 (EDTA), carboxy-methyl-cyclodextrin (CMCD) oxalate, tartrate, citrate and succinate. They concluded planktonic organisms those agents favor the dissolution of iron from the solid, thus promoting the occurrence of homogeneous reaction. Almost complete conversion of pentachlorophenol was achieved but after 9 h reaction time and a significant concentration of dissolved iron (14 mg L−1) was measured. Consistent with these results, Matta et al.  showed that the addition of EDTA and CMCD improved remarkably the conversion of 2,4,6-trinitrophenol in the presence of magnetite from 25 to 50 and 62%, respectively.