研究了三正辛胺从HCl介质中萃取Pd(Ⅱ)的动力学和萃取机理,结果表明:三正辛胺和Cl-的质量浓度对萃取速率有较大的影响,ln(kf (Pd)/kb(Pd))与lnCoTOA和ln[Cl-]分别成直线关系,直线斜率分别为2和-2.界面反应步骤是TOA萃取Pd(Ⅱ)速率的控制步骤,正向萃取反应活化能为21.154kJ· mol-1,推导得出了萃取速率和正、逆向萃取速率常数比(kf(Pd)/kb(Pd))的理论方程,当[Cl-]≥0.10mol·L-1 或 [H+]≥0.10mol·L-1时,理论计算值与实测值吻合.
The kinetics and mechanism of extraction of palladium(Ⅱ) from HCl solution by tri-n-octylamine (TOA) in o-xylene were studied. The extraction rate depends on the concentration of TOA and Cl- , and the rate-determining step is interfacial reaction. The plots of ln(kf(Pd)/kb(Pd)) versus lnCoTOA and ln[Cl-] lie on a straight line with slopes of 2 and -2, respectively. The activation energy(Ea) of forward extraction reaction of palladium(Ⅱ) by TOA is 21.154kJ·mol-1. Theoretical equations of extraction rate and ratio of kf(Pd) to kb(Pd),(kf(Pd)/kb(Pd)),were deduced. The results calculated by the theoretical equation are in agreement with the experimental results when [Cl-]≥0.10mol·L-1 or [H+]≥0.10mol·L-1.
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