5709萃取钴的宏观动力学研究

The Kinetics of Cobalt Extraction with Extractant 5709

采用改进的恒界面池进行了异已基膦酸(1-甲基-庚基)酯(国内代号5709)-庚烷体系从硫酸介质中萃取钴(Ⅱ)的动力学研究.以组分活度代替浓度处理实验数据对有关参数进行了关联,并建立了相应的数学模型(?)=1.435×10^(-3)(a_c_o)-b[(a_(HA)_2)_b]^(1/2)·N^(1/2)/2.55×10~3(a_(H)_b·N^(1/2)+[(a_(HA)_2)_b]^(1/2)实验结果表明,5709萃取钴(Ⅱ)动力学的过程控制为混合控制机制,即为水相中钴离子的扩散和相界面钴的1—2络合物生成的化学反应为主要控制步骤.在水相pH值较高时,控制步骤以前者为主导;在水相pH值较低时,则以后者为主要控制步骤.

The kinetics of cobalt extraction with extractant 5709 (Hexyl-phosphonicAcid Mono-1-Methylheptyl Ester )-Heptane-CoSO4-H2SO4 system was studied with a modified constant interface cell. The extraction kinetics was found to be a mixed controlling regime, i. e., diffusion of cobalt in aqueous phase and chemical reaction of the diffusion of 1 - 2 complex of cobalt at the interface. At higher pH, diffusion was the dominant step, at lower pH, the formation of complex was the dominant step. A mathematic model was established as follows: The apparent activation energy E thus calculated as 8.57 kcal/mol, also sup-ported the mixed controlling regime oi the extraction kinetics ot cobalt.