Study on catalytic activity of Co(II) in Rhodamine B decolorization by peroxymonocarbonate in aqueous solution

Abstract

Decolorization of Rhodamine B (RhB) by peroxymonocarbonate (HCO4–) in aqueous solution was investigated in this study. All experiments were conducted in a 50 mL batch reactor at room temperature (26 ± 1°C) and pH of 9.0. The oxidizing agent (peroxymonocarbonate) was prepared in‐situ by the reaction between hydrogen peroxide and bicarbonate (molar ratio of H2O2:HCO3– is 2:1). The catalytic effect of four metal ions including Co(II), Cu(II), Fe(II), Mn(II) on the decolorization by HCO4– was evaluated. Co(II), the metal ion giving the best catalytic effect, has been selected to study the stability of peroxymonocarbonate agent. To clarify the role of H2O2 and HCO4– in oxidizing RhB dye, a series of experiments were conducted at different concentrations of HCO3‐ and Co(II) catalyst. UV and ultrasound irradiations were also tested for enhancing the decolorization rate. The results revealed that in the presence of Co(II) ion, HCO4– becomes more reactive and a synergic effect on the RhB degradation has been observed when both Co(II) and HCO4– are present in the oxidation system. And under UV light, complete decolorization of RhB by peroxymonocarbonate agent could be obtained after only 20 minutes of irradiation.