摘要
本文研究了N_2H_5NO_3-Fe(Ⅲ)-HNO_3体系和模拟强放废液中Np(Ⅴ)的电解还原,讨论了酸度、温度、肼和铁浓度对Np(Ⅴ)电解还原速度常数和还原率的影响。Np(Ⅴ)的电解还原对Np(Ⅴ)的浓度呈一级反应。在1.5mol/l HNO_3,0.2mol/l肼和2g/l Fe(Ⅲ)存在下,29mA/cm^2电流密度,温度为30℃时,电解还原反应速度常数K为3.42×10^(-2)min^(-1),反应的活化能为38kJ/mol。提高酸度可以加快还原反应的速度和还原率。模拟强放废液中Np(Ⅴ)的电解还原进行得更快,比同酸度的N_2H_5NO_3-Fe(Ⅲ)-HNO_3体系的K值提高7-10倍。当料液酸度为1.5mol/l HNO_3,在0.2mol/l肼存在下,以29mA/cm^2电流密度,电解还原半小时,几乎100％Np(Ⅴ)被还原成Np(Ⅳ)。
The electroreduction of Np(Ⅴ) is studied in the N2H5NO3-Fe (Ⅲ) -HNO3 system. Various factors effecting the electrolytic reduction rate of Np(Ⅴ) are studied, and they are acidity of feed solution, temperature, hydrazine and iron ion concentration etc. The electrolytic reduction reaction of Np(Ⅴ) has a first order relationship with respect to Np(Ⅴ) concentration, ie. d[Np(Ⅴ)]/ dt=k [Np(Ⅴ)]. When the electrolytic solution contains 1.5mol/l HNO3, 0.2mol/l N2H,NO3 and 2g/l Fe3+, the current density is 29mA/cm2, at 30℃, the apparent rate constant k= 3.42×10-2 min-1, the activation energy is 38kJ/mol. The increase of nitric acid concentration improves both the reduction fraction and reduction fate. The electrolytic reduction of Np(Ⅴ) is greatly enhanced in synthetic high active waste solution., the apparent electrolytic reduction rate constant K is 7-10 times as great as that in N2H5NO3-Fe(Ⅲ)-HNO3 system with the same HNO3 concentrations.
出处
《核化学与放射化学》
CAS
CSCD
北大核心
1989年第3期169-176,共8页
Journal of Nuclear and Radiochemistry
关键词
镎
电解还原
强放废液
Neptunium, Elecrolytic reduction of Np(Ⅴ), High active waste.
