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^-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 (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).

Keywords

Kinetics, Autoxidation, SO₂, Co₂O₃, Catalysis, Inhibition, Benzamide