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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)。
In this paper, the electrochemical reduction of Np (Ⅴ) in N_2H_5NO_3-Fe (Ⅲ) -HNO_3 system and simulated discharge was studied. The effects of acidity, temperature, hydrazine and iron concentration on the rate constant and reduction rate of Np (Ⅴ) influences. Electrolytic reduction of Np (V) reacted first-orderly to the concentration of Np (V). When the current density is 29mA / cm ~ 2 in the presence of 1.5mol / l HNO_3, 0.2mol / l hydrazine and 2g / l Fe (Ⅲ), the rate constant K of electrolytic reduction is 3.42 × 10 ~ 2) min ~ (-1), the activation energy of the reaction is 38kJ / mol. Increase the acidity can speed up the reduction reaction rate and reduction rate. Electrolytic reduction of Np (Ⅴ) in simulated effluent was faster than that of N_2H_5NO_3-Fe (Ⅲ) -HNO_3 with the same acidity. When the acidity of the feed liquid is 1.5mol / l HNO3, almost 100% Np (V) is reduced to Np (IV) by electrolysis at a current density of 29mA / cm ~ 2 for half an hour in the presence of 0.2mol / l hydrazine.