Long-Term γ-Radiolysis Kinetics of NO₃⁻ and NO₂⁻ Solutions

Abstract

Radiolysis kinetics in NO(3)(-) and NO(2)(-) solutions during γ-irradiation were studied at an absorbed dose rate of 2.1 Gy·s(-1) at room temperature. Air- or argon-saturated nitrate or nitrite solutions at pH 6.0 and 10.6 were irradiated, and the aqueous concentrations of molecular water decomposition products, H(2) and H(2)O(2), and the variation in the concentrations of NO(3)(-) and NO(2)(-) were measured as a function of irradiation time. The experimental data were compared with computer simulations using a comprehensive radiolysis kinetic model to aid in interpretation of the experimental results. The effect of nitrate and nitrite, present at concentrations below 10(-3) M, on water radiolysis processes occurs through reactions with the radical species generated by water radiolysis, (•)e(aq)(-), (•)O(2)(-), and (•)OH. The changes in H(2) and H(2)O(2) concentrations observed in the presence of nitrate and nitrite under a variety of conditions can be explained by a reduction in the radical concentrations. The kinetic analysis shows that the main loss pathway for H(2) is the reaction with (•)OH and the main loss pathways for H(2)O(2) are reactions with (•)e(aq)(-) and (•)OH. Nitrate and nitrite compete for the radicals leading to an increase in the concentrations of H(2) and H(2)O(2). Post-irradiation measurements of H(2), H(2)O(2), NO(2)(-) and NO(3)(-) concentrations can be used to calculate the radical concentrations and provide information on the redox conditions of the irradiated aqueous solutions.

Degradation of microcystin-LR in water by glow discharge plasma oxidation at the gas–solution interface and its safety evaluation

“…(3)e(7)) Yakabuskie et al, 2011). Put together, all this information may thus explain the lowered degradation rate with addition of NaNO 3 .…”

“…The addition of NaNO 3 and NaNO 2 results in reduction of removal efficiency since hydrated electron ð$e À eq Þ can be quickly scavenged by NaNO 3 and $OH can be scavenged by NaNO 2. Although NO 3 À is not a direct scavenger of $OH, it has been reported that the concentration of $OH achieved in the radiolysis of pure water is about one hundred times higher than that with additive of 1 mM NO 3 À in pure water (Yakabuskie et al, 2011). This is because that the added NO 3 À can be transformed into NO 2 À under the discharge plasma (Eq.…”

Evaluation of the potential of p-nitrophenol degradation in dredged sediment by pulsed discharge plasma

“…Phosphate and nitrate can react rapidly with e aq À , and they are usually chosen as e aq À scavengers (Buxton et al, 1995;Yakabuskie et al, 2011;Zhang et al, 2012). e À aq þ NO À 3 /NO 2À 3 k ¼ 9:7 Â 10 9 M À1 s À1 (1)…”

The Effects of Cathodic Reagent Concentration and Small Solution Volumes on the Corrosion of Copper in Dilute Nitric Acid Solutions

“…Under these conditions the radiolysis of the aerated vapor will produce HNO 3 , 10-12 which will be absorbed into condensed H 2 O in contact with the aerated vapor. [13][14][15] The effect of radiation on the corrosion of Cu has been studied in both aqueous solutions [16][17][18][19][20][21][22][23] and in humid air, 24 usually at dose rates well in excess of those anticipated on a container surface, but with contrasting observations. In both aerated and deaerated chloride solutions (150°C, 27 Gy/h), radiation appeared to be beneficial, leading to the formation of an apparently protective Cu 2 O film.…”