氨基羟基脲与Pu(Ⅳ)的还原动力学研究

研究了氨基羟基脲(HSC)与Pu(Ⅳ)的还原反应动力学，其动力学方程式为：-d_c（Pu(Ⅳ)）/d_t=kc（Pu(Ⅳ））c^1.06（HSC）c^-0.43（H⁺）c^-0.58（NO₃^-），在22.1℃时反应速率常数k＝(11.8±1.1)（mol/L）^-0.046?s^-1，活化能为(71.0±1.0)kJ/mol。研究了氨基羟基脲浓度、H⁺浓度、硝酸根浓度、Fe³⁺浓度、UO₂²⁺浓度对氨基羟基脲与Pu(Ⅳ)还原反应速率的影响，增加氨基羟基脲浓度，降低H⁺浓度、硝酸根浓度，Pu(Ⅳ)还原速度增加；UO₂²⁺浓度和Fe³⁺浓度对Pu(Ⅳ)还原速度基本无影响。

Kinetics of Reaction Between Pu(Ⅳ)and Hydroxysemicarbazide in Nitric Acid Solution

The kinetics of reaction between Pu(Ⅳ) and hydroxysemicarbazide (HSC) in nitric acid solution was studied. The rate equation is found to be: ：-d_c（Pu(Ⅳ)）/d_t=kc（Pu(Ⅳ））c^1.06（HSC）c^-0.43（H⁺）c^-0.58（NO₃^-）, wherek＝(11.8±1.1) （mol/L）^-0.046?s^-1 at 22.1 ℃ and the activation energy E_a＝(71.0±1.0) kJ/mol. Effects of c(HSC), c(H⁺), c(Fe³⁺), c(UO₂²⁺), ionic strength and temperature on reduction rate of Pu(Ⅳ) were investigated. The results show that Pu(Ⅳ) can be rapidly reduced to Pu(Ⅲ) by HSC under normal conditions. The reaction rate can be accelerated by increasing concentration of hydroxysemicarbazide or temperature, and decreasing concentration of HNO₃ or ionic strength. The influence of UO₂²⁺ and Fe³⁺ on reaction rate is negligible.