Co2O3 Catalyzed Oxidation of SO2 in Aqueous Solution Differing Effect of Benzamide in Alkaline Medium

Abstract

We report that benzamide is a good inhibitor for SO2 oxidation in the pH range 7.8-9.4 in the presence of Co2O3. Based on the observed results the following rate law is given and a free radical mechanism has been proposed. -d[S(lV)]/dt = (k1+k2[Co2O3]) [S(lV)]/1+B [benzamide]. Experiments were carried out at 30 ≤ T °C ≤ 40, 7.8 ≤ pH ≤ 9.4, 1×10 mol/dm ≤ [S(lV)] ≤ 6 × 10 mol/dm, 0.1 g/L ≤ [Co2O3] ≤ 0.4g/L, 1×10 mol/dm ≤ [benzamide] ≤ 5×10 mol/dm. Rate constants and the order of reaction were calculated and the reaction was found to be pseudo-first order in all cases. The effect of pH and temperature are also discussed. The value of apparent activation (Ea) energy was determined to be 8.7 kJ mol. The activation of energy was calculated by Arrhenius equation. (k = A e).