Kinetics of the Reduction of Nitrite Oil by Sulfur Dioxide in Aqueous Solution

摘要

Reactions between nitrite and bisulfite ions in aqueous solutions were studied in which sulfur (IV) species are oxidized to sulfate ions and nitrogen (III) species are reduced. The dependence on temperature, ionic strength, acidity, and solution composition was determined. The actual products formed depend primarily on the concentration of bisulfite ion. The importance of these reactions to atmospheric aerosol formation processes is discussed. Under most conditions, the nitrogen product is hydroxylamine-N, N-disulfonate. Two processes are responsible for its formation. The first process (when the bisulfite concentration is greater than 0.1 M) is first order in nitrite ion, second order in bisulfite ion, and independent of acidity and temperature. It has a strong dependence on the ionic strength. The second and dominant process contributes to the product formation under all conditions and is first order in nitrite, bisulfite, and hydrogen ions. This process is independent of ionic strength and has a 12 kcal/mole activation energy. Both processes are insensitive to the choice of buffer. Whenever the hydrogen ion concentraion is nearly equal to that of the bisulfite ion, nitrous oxide is also a product. A mechanism is proposed to account for these results. It consists of a direct reaction of nitrite ion with metabisulfite ion to form hydroxylamine disulfonate, in parallel with a reaction between nitrous acid and bisulfite ion to form nitrososulfonic acid. This rapidly adds a bisulfite ion to form hydroxylamine disulfonate or undergoes hydrolysis to form nitrous oxide. The reaction between nitrite ion and hydroxylamine-N-sulfonate to produce nitrous oxide was also investigated. The reaction is first order in nitrite ion, second order in hydrogen ion, and between zero and first order in hydroxylamine monosulfonate, depending on the concentration. (ERA citation 07:015206)