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在pH>1条件下,采用EDTA容量滴定法测定D2EHPA-HCl-HAc体系萃取Pr(Ⅲ)过程两相中的Pr浓度分别考察溶液酸度和萃取剂浓度对Pr的分配比的影响,通过对D2EHPA以及D2EHPA-HCl-HAc体系负载Pr有机相进行红外光谱测试。分析探究了D2EHPA-HCl-HAc体系萃取Pr的机制,并确定萃取平衡常数。研究结果表明,当pH>1时,萃取过程的实质是Pr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KPr为1×100.13。
Under the conditions of pH> 1, the concentration of Pr in the two phases of Pr (Ⅲ) extracted by D2EHPA-HCl-HAc system was measured by EDTA titration. The effects of solution acidity and extractant concentration on the distribution ratio of Pr were investigated. And D2EHPA-HCl-HAc system loaded Pr organic phase for infrared spectroscopy. The mechanism of extracting Pr from D2EHPA-HCl-HAc system was explored and the extraction equilibrium constant was determined. The results show that when pH> 1, the essence of the extraction process is the replacement of the Pr ion with the group P-OH, following the cation exchange mechanism and the complexation coordination with the group P = O, the extraction equilibrium constant KPr is 1 × 100.13.