Mechanistic study of carmoisine dye degradation in aqueous solution by Fenton process

The carmoisine azo dye (AR14) solution 1 g/L was degraded by Fenton process under the following conditions: [Fe2+] = 3.57 mmol/L, [H2O2] = 194 mmol/L at pH = 3.0. The degradation pathway of AR14 by the Fenton process was investigated by means of IR, LC-MS-MS and Ion Chromatography analysis. Some aromatic anions such as 5,8-dihydroxy-2-nitronaphthalen-1-o late, benzoate, 5-hydroxy-4-nitro-2-sulfonatobenzoate and naphthalene-1-sulfonate were formed and identified. Moreover, a quantitative analysis of inorganic ions (sulfate and nitrate) produced during the degradation process helped to verify molar balance with regard to original sulfur and nitrogen elements. A feasible degradation pathway of AR14 was proposed and discussed. The reaction mechanisms proposed in this research should prove useful for future application of the technology to dyes decolorization. (C) 2020 Elsevier Ltd. All rights reserved.