N263-HSCN体系萃取锆铪的动力学

Kinetics of Extraction of Zirconium and Hafnium with N263-HSCN System

采用恒界面池法研究了N263-HSCN体系萃取锆和铪的动力学,考察界面积、萃取槽搅拌速度、温度对萃取锆和铪的影响,从而确定萃取动力学类型。结果表明,当搅拌速度小于130 r min时,萃取过程由扩散反应控制,锆铪的萃取速率常数随搅拌速度的增加而增大;当搅拌速度在130~170 r min时,萃取过程由化学反应控制,锆和铪的萃取速率常数随搅拌速度的增加基本保持不变。随着界面积的增加和温度的提高,锆和铪的萃取速率常数均增加,其表观活化能分别为42.06 kJ/mol和31.77 kJ/mol,说明该萃取过程为相界面处的化学反应控制过程。计算出锆和铪萃取的焓变分别为39.59 kJ/mol和29.30 kJ/mol,熵变分别为-147.53 J(mol·K)和-174.38 J(mol·K),在298.15 K时吉布斯自由能变分别为83.57 kJ/mol和81.29 kJ/mol。

Extraction kinetics of zirconium and hafnium extracted by N263-HSCN system was studied by constant Lewis cell technique.Effects of stirring speed,interfacial area and temperature of extraction tank on extraction of zirconium and hafnium were explored to determine the type of extraction kinetics.The results show that when stirring speed is less than 130 r min,the extraction rate constant of zirconium and hafnium rises with the increase of stirring speed,and the extraction process is controlled by diffusion reaction;When stirring speed is within 130-170 r min,the extraction rate constants of zirconium and hafnium remains basically stable with the increase of stirring speed,and the extraction process is controlled by chemical reaction.With the increase of interfacial area and temperature,the extraction rate constants of zirconium and hafnium rise,the apparent activation energies of zirconium and hafnium extraction are 42.06 kJ/mol and 31.77 kJ/mol respectively,indicating that the extraction process is controlled by chemical reaction process at the phase interface.The enthalpy changes of zirconium and hafnium extraction are 39.59 kJ/mol and 29.30 kJ/mol respectively.The entropy changes are-147.53 J(mol·K)and-174.38 J(mol·K)respectively,and the Gibbs free energy changes are 83.57 kJ/mol and 81.29 kJ/mol respectively at 298.15 K.