Catalytic behavior of chromium supported silica for decolorization of neutral red dye using oxidation reaction

Abstract

The heterogeneous catalyst, chromium doped silica was prepared by impregnation method and investigated for the decolorization of neutral red dye which was used as a pollutant molecule in this study. The XRD result detected new diffraction peaks for chromium oxide at 24.6°, 32.92°, 40.8°, 41.4° and 44°. The FTIR results improved the existence of Cr+3 within the structure of silica due to the shifting of the absorption peaks to the higher wave numbers. The TGA/DSC results detected the significant influence of temperature on the appearance of chromium phases supported silica. This was evidence during the experimental work through the change in color of the synthesized catalyst from light green for the catalysts calcined at 200°C and 300°C to yellow for that calcined at 500 °C. Different reaction variables such as, effect of chromium ions, pH values, amount of hydrogen peroxide and effect of reaction temperature were studied to estimate their effect on the decolorization efficiency of neutral red dye. The maximum catalytic activity achieved was 92% at a solution pH of 5.5, catalyst dosage of 1.5 g/L, 0.1 mL of H2O2 /100 mL of reaction volume and initial dye concentration of 10 mg/L after 60 min of reaction time.