N. Rawat, P. Mohapatra, V. Manchanda
Jun 27, 2006
Citations
0
Influential Citations
7
Citations
Journal
Journal of Solution Chemistry
Abstract
Abstract2-(5-Bromo-2-pyridylazo)-5-(diethylamino) phenol (Br-PADAP) forms a 1:1 complex with the uranyl ion in the presence of sulphosalicylic acid, which acts as stabilizer for this complex in the triethanol amine/perchloric acid buffer system. A change in the stoichiometry of the complex was seen at pH<5. Kinetic measurements were carried out using stopped-flow spectrophotometer in the presence of an excess concentration of U(VI) in the pH range 6.5 to 8. The dependence of the pseudo-first-order rate constant, k(obs), on the concentrations of U(VI), ligand and hydrogen ion showed that Br-PADAP reacts with UO2(OH)+ to form an intermediate species (equilibrium constant = 1.28×104mol.dm−3) that then rearranges (rate constant = 5.6×10−2s−1) to form the product species. UO2(OH)+ is present in equilibrium with the unreactive species UO2(OH)2, as well as with the unreactive sulfosalicylic acid complex.