摘要
开展了高氯酸体系中以肼为还原剂,铂黑为催化剂催化还原U(Ⅵ)的动力学研究。通过考察U(Ⅵ)浓度、肼浓度、酸度以及催化剂用量等条件对反应过程的影响,确定了该反应的初始动力学速率方程为-dc(UO22+)/dt=kc0.39(UO22+)c0.36(N2H5+)c-0.51(H+),在60℃、固液比0.002kg/L时,速率常数k=3.2×10-3(mol/L)0.76/min。研究了温度对反应速率的影响,结果表明,在20～75℃范围内,随着温度升高,反应速率加快,反应过程由化学反应控制转变为扩散控制过程。并在此基础上推测了可能的反应机理,认为肼在催化剂表面的吸附分解是整个反应的控制步骤。
The kinetics of platinum-catalyzed reduction of U（VI） with hydrazine in perchloric acid media was studied. By investigating the influence of U （VI） concentration, hydrazine concentration, acidity and catalyst amounts （S/L） on the reaction, the reaction rate equation is obtained： -dc（UO22＋）/dt=kc0.39（UO22＋）c0.36（N2H5＋）c-0.51（H＋）,, and the rate constant is k=3.2×10-3（mol/L）0.76/minmin at 60 ℃ and the solid-to-liquid ratio of 0. 002 kg/L. The effect of temperature was also investigated. The results show that while increasing the temperature, the reaction accelerates and the reaction process shifts from reaction-controlled to diffusion- controlled. Based on the above results, a possible reaction mechanism with the dissociation of adsorbed hydrazine on the catalyst as the the control step, is explored.
出处
《核化学与放射化学》
CAS
CSCD
北大核心
2012年第4期213-217,共5页
Journal of Nuclear and Radiochemistry
关键词
肼
铂黑
铀(Ⅵ)
催化还原
hydrazine
platinum black
U（Ⅵ）
catalytic reaction
