Influence of sulfite on radiolytic conversion of nitrate and nitrite in dilute aqueous solutions

Radiation induced degradation of antiepileptic drug primidone in aqueous solution

“…The reason was that SO 3 2À can act as a scavenger of Å OH with a high rate constant of 5.5 Â 10 9 (Eq. (41)) [31] while the final product of its radiolytic conversions is the non-hazardous sulfate ion [44]. The dose constant is less marked than that observed with the NO 2 À ion, but more marked in comparison with other anions in this study.…”

“…The temporary products, NO 2 Å and NO Å2À 2 , ith less oxidizability than Å OH and even continuing react with Å OH (NO 2 Å , shown in Eqs. (33) and NO 2 Å2À shown in the previous paper [43]), tend to be reluctant to degrade the preferably oxidation-degraded primidone in comparison to Å OH [44]. Thus, the dose constant significant decreased at a concentration of 5.0 mM NO 2 À .…”

Effect of dissolved oxygen on the radiolytic conversion of nitrate ions in aqueous solutions in the presence of formate

“…The noticeable effect of irradiation on nitrate in aqueous solutions is observed only in the presence of effective scavengers of OH radicals. 4,5 Earlier, 5 we found that the presence of nitrate and formate in a deaerated aqueous solution can provide deep decomposition of nitrate. In the absence of oxygen, formate actively traps OH radicals and slowly reacts with the reduction products of water radiolysis, 5,6 the hydrated electron eaq and the H atom.…”

“…This is primarily due to the high rate constant of reaction (10); in addition, the majority of redox processes in the irradiated nitrate-nitrite system proceed through a stage of NO • 2 radical formation. 4,5,12 Figure 2 indicates that at a formate concentration of 2×10 -4 -5×10 -4 mol dm -3 the removal of nitrate was almost not observed up to a dose of 6.2 kGy. A small decrease in the absorbance at 0.5-2 kGy (curves 1 and 2) is caused by partial transformation of nitrate to nitrite.…”

Removal of iopromide and degradation characteristics in electron beam irradiation process

“…To investigate the relative contribution of each in IPM removal, an OH • quenching study was performed using SO 3 2− (sulfite). Since the sulfite slowly reacts with e − aq (k sulfite/e − aq = < 1.5 × 10 6 M −1 s −1 [19]), whereas it quickly reacts with OH • (k sulfite/OH • = 5.5 × 10 9 M −1 s −1 [19]), the sulfite was recommended as a suitable OH • scavenger in the E-beam process [30].…”