Catalytic effect of siderite on H2O2 oxidation of carmine dye: Performance, mechanism and kinetics

The role of siderite in catalyzing the H2O2 degradation of carmine was studied by using batch experiments. The effects of the size of siderite particles, ratio of H2O2 to siderite, initial pH, reaction time, and reaction temperature were examined, and the degradation mechanism and kinetics were discussed. The size of siderite slightly affected the degradation of carmine, and the ratio of H2O2 to siderite significantly influenced degradation; a ratio of 6:1 resulted in maximum carmine degradation. Although the optimal reaction pH was 3, excellent degradation efficiency was also found at pH 4 and 5. In the H2O2 /siderite system, the kinetic reaction order is 1.04, and the rate constant is 10.15 min(-1); 99.97% of the chroma was removed, and 80.61% of the TOC was degraded when the ratio of H2O2 to siderite was 6:1 with an initial pH of 3. The slow release of Fe2+ in siderite played an important role in the catalytic H2O2 degradation of carmine. Moreover, siderite was cycled eight times without affecting decolorization efficiency. The experimental data illustrated that siderite provided the catalyst for the Fenton process and that siderite has great application value and potential in carmine degradation; this data serves as a foundation for the industrial use of recycled natural mineral materials.