On the reactions of CO3•- radicals with NOx radicals

The reactions of CO3.- radicals with NOx radicals were studied by pulse radiolysis of deoxygenated aqueous solutions containing carbonate and nitrate ions. The (OH)-O-. radicals react with carbonate to yield CO3.- and the e(aq)(-) reacts with nitrate to yield NO3.2-, which then converts into NO2.. This conversion has a rate constant of 4.6 x 10(4) s(-1) in alkaline solutions but is catalyzed by HCO3- (k = 2.8 x 10(7) L mol(-1) s(-1)). The CO3.- radicals react rapidly with both NO3.2- (k = 1.0 x 10(9) L mol(-1) s(-1)) and NO2. (k = 4.6 x 10(8) L mol(-1) s(-1)). The expected combination product was short lived and was not observed on the microsecond time scale and the possible peroxynitrite product was not detected following gamma-radiolysis. A similar study with solutions containing carbonate and nitrite shows that NO2.2- reacts with CO3.- faster than NO3.2- and NO reacts with CO3.- faster than NO3.2. (C) 1999 published by Elsevier Science Ltd. All rights reserved.