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?10-3 mol/dm3 ≤ [S(lV)] ≤ 6 ? 10-3 mol/dm3, 0.1 g/L ≤ [Co2O3] ≤ 0.4g/L, 1?10-3mol/dm3 ≤ [benzamide] ≤ 5?10-3 mol/dm3. 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-1. The activation of energy was calculated by Arrhenius equation. (k = A e-Ea/RT).
Kinetics, Autoxidation, SO2, Co2O3, Catalysis, Inhibition, Benzamide