Efficient H2O2 Oxidation of Organic Dyes Catalyzed by Simple Copper(II) Ions in Bicarbonate Aqueous Solution

Bicarbonate (HCO3-), one of the most abundant anions in fresh water, is relatively nontoxic and cheap. In this work, the degradation of organic dyes with simple copper(II) ions as the catalyst in the HCO3- solution using H2O2 as the oxidant was investigated. It was found that the dyes such as Orange II (AOII), Methyl Orange, Methyl Red, and Toluidine Blue could be efficiently decolorized by the system. The rate of H2O2 decomposition was much slower in the presence of the dyes than that without the pollutants. The formed copper(II) species at different HCO3- concentrations were calculated, and CuCO3 was suggested to be more reactive. The radical scavenging measurements further implied that the produced higher oxidation state of copper, Cu(III), was to be responsible for the dye decolorization. A possible pathway of AOII degradation was also proposed based on the detected intermediate products by electrospray ionization mass spectrometry. This study can provide us a simple, effective, and economical system ideal for the treatment of toxic and nonbiodegradable organic dyes.