The reversible reaction kinetics of neptunium with nitrous and nitric acids

In order to understand the equilibrium state, conversion process and mechanism of Np(V)/Np(VI) in nitric acid solution, the redox kinetics of neptunium with nitrous and nitric acids was studied spectrophotometrically by an nonlinear fitting method. The rate equation of the redox reaction was acquired. Apparent activation energy of forward reaction and reverse reaction are approximately the same of 80 kJ/mol. Varying the concentrations of nitric and nitrous acids will change the reaction rate of forward and reverse reaction in different degrees. As a result, the equilibrium state of Np(V)/Np(VI) is altered, but it is not influenced by temperature.