氨基羟基脲与Np(Ⅵ)的还原动力学

研究了氨基羟基脲(HSC)浓度、H~+浓度、NO_3~-浓度、Fe3+浓度、UO2+2浓度、反应温度对氨基羟基脲与Np(Ⅵ)还原反应速率的影响,获得了其动力学方程。实验结果表明:增加氨基羟基脲浓度和提高反应温度,降低H~+浓度和NO_3~-浓度,可以提高氨基羟基脲与Np(Ⅵ)还原速率;在UO2+2存在或Fe3+浓度小于1×10-3 mol/L时,对氨基羟基脲与Np(Ⅵ)的还原没有明显影响。氨基羟基脲还原Np(Ⅵ)的动力学方程式为:-dc(Np(Ⅵ))/dt=kc(Np(Ⅵ))c2.52(HSC)c-0.53(H+)c-0.61(NO_3~-),在4.00℃时k=(1 037±60)(mol/L)-1.40·s-1,活化能Ea=(64.03±6.4)kJ/mol。

Kinetics of Reaction Between Np(Ⅵ) and Hydroxysemicarbazide in Nitric Acid Solution

The effects of c(HSC), c(H⁺), c(Fe³⁺), c(UO²⁺₂), ionic strength and temperature on the reduction rate of Np(Ⅵ) by hydroxysemicarbazide (HSC) were investigated. The results show that Np(Ⅵ) can be rapidly reduced to Np(Ⅴ) by HSC. The reaction rate of Np(Ⅵ) with HSC can be accelerated by increasing concentration of HSC and temperature，decreasing concentration of HNO₃ and ionic strength. The kinetic equation for the reduction of Np(Ⅵ) by hydroxysemicarbazide is: -dc(Np(Ⅵ))/dt=kc(Np(Ⅵ))c^2.52(HSC)c^-0.53(H⁺)?c^-0.61(NO^-₃) where k=(1037±60) （mol/L）^-1.40?s^-1 at 400 ℃. The activation energy is E_a=(64.03±6.4) kJ/mol. No significant effect on the reduction of Np(Ⅵ) by hydroxysemicarbazide is observed when the concentration of Fe³⁺ is less than 1 × 10^-3 mol/L or in the presence of UO²⁺₂.