Role of some organic inhibitors on the oxidation of dissolved sulfur dioxide by oxygen in rainwater medium

• DOI: 10.1007/s11356-013-2253-1
• Publication Date: 2013-11-18T01:23:03Z
• Authors: Yogpal Dhayal; C. P. S. Chandel; K. S. Gupta
• Keywords: Rainwater Harvesting

In August 2012, eight rainwater samples were collected and analyzed for pH and metal ions, viz., iron, copper, and manganese. The pH was within the range 6.84-7.65. The rate of oxidation of dissolved sulfur dioxide was determined using these rainwater samples as reaction medium. Kinetics was defined by the rate law: -d[S(IV)]/dt = R o = k o[S(IV)]], where k o is the first-order rate constant and R o is the rate of the reaction. The effect of two volatile organic compounds-ethanol and 2-butanol-was examined and found to inhibit the oxidation as defined by the rate law: k obs = k o/(1 + B [Inh]), where k obs is the first-order rate constant in the presence of the inhibitor, [Inh] is the concentration of the inhibitor, and B is the inhibitor parameter-an empirical constant. In the pH range of collected rainwater samples, the values of first-order rate constants ranged from 3.1 × 10(-5) to 1.5 × 10(-4) s(-1) at 25 °C. The values of inhibition parameter were found to be (5.99 ± 3.91 × 10(4)) (ethanol) and (3.95 ± 2.36) × 10(4) (2-butanol) at 25 °C.