The radiolysis at room temperature and 118 °C of aqueous solutions containing sodium nitrate and either sodium formate or 2-propanol

Abstract

Deoxygenated sodium nitrate solutions (≤ 2.5 × 10−2 M) containing sodium formate (≤ 0.5 M) have been irradiated at room temperature and 118 °C. With formate concentrations ≤ 5 × 10−2 M, G(NO2−) increased ~25% over the temperature range. Calculations suggest part of this increase in G(NO2−) may arise from an increase in the overall solvated electron yield. With 0.5 M sodium formate solutions containing 2.5 × 10−2 M sodium nitrate, G(NO2−) rose from 3.6 at room temperature to ~14 at 118 °C, suggesting the occurrence of a chain reaction at higher formate concentrations. G(H2O2) and G(H2) were not functions of temperature for all the above solutions.The pH dependence of G(NO2−) was determined at room temperature for sodium nitrate solutions containing either sodium formate or 2-propanol. The G(NO2−) as a function of pH could only be modelled satisfactorily with rate constants from the literature in the sodium formate case.It is concluded that the solvated electron yield in irradiated aqueous solutions at elevated temperatures cannot be confidently deduced from measurements made with nitrate as an electron scavenger in the presence of formate ions or alcohols.