Gas chromatographic study of complexing in the system hydrazoic acid-tributyl phosphate-nitric acid-uranyl nitrate

Elution gas chromatography has been used to study complexing of hydrazoic acid with tributyl phosphate (TBP) in hexadecane solution in the presence of nitric acid and/or uranyl nitrate. The study covered the temperature range 298-338 K, with concentrations of either additive up to 0.41 mol dm(-3). The results for hydrazoic acid elution at infinite dilution establish (a) that stoichiometry of the TBP-HNO3 complex is 1:1 and (b) that both 2:1 and 1:1 TBP-UO2(NO3)2 complexes co-exist in the system, the latter increasing in amount as the temperature is raised. Both HNO3 and UO2(NO3)2 act simply to reduce the amount of TBP free to form the 1:1 TBP-HN3 complex. Stability constants for the equilibrium UO2(NO3)2 TBP+TBP4<-->UO2(NO3)2 x 2TBP are presented.