D2EHPA-HCl-HAc体系萃取Pm(Ⅲ)的机理与平衡常数

在pH>1条件下,采用EDTA容量滴定法测定D2EHPA-HCl-HAc体系萃取Pm(Ⅲ)过程两相中的Pm浓度,分别考察溶液酸度和萃取剂浓度对Pm的分配比的影响,通过红外光谱测试探究D2EHPA-HCl-HAc体系萃取Pm的机理,并确定萃取平衡常数。结果表明,萃取过程的实质是Pm离子与基团P-OH发生置换,遵循阳离子交换机制,以及与基团P=O发生的络合配位作用,其萃取平衡常数KPm为3.02。

Extraction Mechanism of Pm in D2 EHPA-HCl-HAc System and Extraction Equilibrium Constant

In the conditions of pH >1,Pm concentration is determined by volumetric precipitation method of EDTA in the two phase of D2EHPA-HCl-HAc extraction system,the effect of the solution's acidy and extractant concentration on Pm distribution ratio is studied.And the extraction mechanism of Pm in D2EHPA-HCl-HAc system is also studied by measuring infrared spectrum of D2EHPA and the organic phase loading Pm in D2EHPA-HCl-HAc system.Whereby,the extraction equilibrium constant can be calculated.The results show that displacement reaction between Pm(Ⅲ) and P-OH happens and the extraction process abide by cation exchange mechanism in the condition of pH>1.Pm(Ⅲ) and P=O also do coordination complex action at the same time,and extraction equilibrium constant KPm is 3.02.