Electroplating wastewater contains various transition metals in the form of complexation, such as Cr3+, Cr6+, Cu2+, Ni2+, Zn2+ and Fe2+. The deep treatment of the wastewater usually requires pre-decomplexation, i.e. removal of ligands. This study showed that those transition metals were capable of activating ozone to generate �OH radicals by electron transfer under strongly acidic conditions, to oxidize and removal the ligands. The �OH-exposure by ozone in electroplating wastewater was further quantified by investigating the degradation kinetics of benzoic acid, a typical �OH probe compound. Ozone-exposure was rapidly reduced and �OH-exposure was clearly increased in the presence of transition metals. The promotion effect of those metals on ozone activation was also compared. The degradation of EDTA, a widely used ligand, was subsequently studied, and efficient decomplexation was successfully achieved in electroplating wastewater using ozone oxidation. The results suggest that the coexisting transition metal in the electroplating wastewater could be well made use of to enhance the decomplexation by ozonation.

Enhanced decomplexation of EDTA from electroplating wastewater using ozonation initiated by the coexisting transition metals

248th National Meeting (2014)

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