Ag (I) Catalyzed Oxidation of SO2 in Aqueous Solution Differing Effect of Benzoate Ions in Acidic Medium

Aim: In this paper, we report that sodium benzoate is a good inhibitor for SO2 oxidation in the pH range 4.02-5.25 in the presence of Ag (I). 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[Ag(I)]) [S(lV)]/1 + B [Sodium Benzoate] Methods: Experiments were carried out at 30≤T°C≤40, 4.02≤pH≤5.25, 1×10−3 mol/cm3≤ [S(lV)≤10×10−3 mol/cm3, 5×10−6 mol/cm3≤[Ag(I)]≤2.5×10−5 mol/cm3, 8×10−8 mol/cm3≤ [Sodium Benzoate]≤2×10-4 mol/cm3. Observation: Rate constants and the order of reaction were calculated and the reaction was found to be pseudo- first order in all cases. Result: The effect of pH and temperature are also discussed. The value of apparent activation (Ea) energy was determined to be 24.11 kJ mol-1. The activation of energy was calculated by Arrhenius equation (k = A e-Ea/RT).