Effects of the FeII/CuII interaction on copper aging enhancement and pentachlorophenol reductive transformation in paddy soil.

The present study investigated copper aging and pentachlorophenol (PCP) reductive transformation under the effects of the Fe(II)/Cu(II) interaction in paddy soil in south China. Kinetic measurements demonstrated that the PCP reductive transformation rate (k) could be promoted in the presence of no more than 0.375 mM Cu(II) and inhibited in the presence of no less than 0.5 mM Cu(II). The highest k value in the presence of 0.25 mM Cu(II) corresponds to the lowest redox potential (E(p)) value of active Fe species. The increasing trend in E(p) of the active Fe species is consistent with the declining trend in the k value of PCP reduction and vice versa. Dissolved Cu(II) is gradually transformed into immobilized Cu species during PCP reduction, which indicates that Cu aging is enhanced by the Fe(II)/Cu(II) interaction. These findings improve our general understanding of the Fe(II)/Cu(II) interaction on soil iron redox chemistry for polychlorinated pesticide detoxification and heavy metal immobilization.