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 SO 2 oxidation in the pH range 7.8-9.4 in the presence of Co 2 O 3. Based on the observed results the following rate law is given and a free radical mechanism has been proposed.-d[S(lV)]/dt = (k 1 +k 2 [Co 2 O 3 ]) [S(lV)]/1+B [benzamide]. Experiments were carried out at 30 ≤ T °C ≤ 40, 7.8 ≤ pH ≤ 9.4, 1×10-3 mol/dm 3 ≤ [S(lV)] ≤ 6 × 10-3 mol/dm 3 , 0.1 g/L ≤ [Co 2 O 3 ] ≤ 0.4g/L, 1×10-3 mol/dm 3 ≤ [benzamide] ≤ 5×10-3 mol/dm 3. 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 (E a) energy was determined to be 8.7 kJ mol-1. The activation of energy was calculated by Arrhenius equation. (k = A e-Ea/RT).