Iron and copper redox interactions in UV-seawater: A kinetic model approach

Abstract

The redox interaction between iron and copper was experimentally studied in UV-seawater (UV-SW) and a kinetic model was developed to simultaneously reproduce the coupled Fe and Cu redox chemistry. The kinetic model included a combination of chemical reactions and their equilibrium and rate constants. The interactions between Cu(I) and Fe(II), Cu(I) and Fe(III) and Cu(II) and Fe(II) under different oxygen and H2O2 concentrations were considered. The Cu(I) oxidation rate under oxygen saturation conditions linearly decreased in the presence of Fe(II) and increased in the presence of Fe(III). The effect of Fe(II) was one order of magnitude higher than that for Fe(III).The kinetic model considered the competition between Fe and Cu in the UV-SW by reactive oxygen species, the direct reaction between Fe and Cu, and the formation of Fe-Cu species such as cuprous ferrite and cupric ferrite. This inorganic kinetic model is the previous step to be able to incorporate the role of organic binding ligands in the Fe and Cu redox interaction in natural waters and represents an advance in the Fe and Cu coupled marine biogeochemical cycles.