P204-HCl-HAc体系萃取La的机理分析与萃取平衡常数

Analysis of Extraction Mechanism and Extraction Equilibrium Constant of La in P204-HCl-HAc System

在pH>1条件下,采用EDTA容量滴定法测定P204-HCl-HAc体系萃取La(Ⅲ)过程两相中的La浓度,并分别考察溶液酸度和萃取剂浓度对La分配比的影响;通过对P204以及P204-HCl-HAc体系负载La有机相进行红外光谱测试分析,探究P204-HCl-HAc体系萃取La的机理,并确定其萃取平衡常数。研究结果表明,当pH>1时,萃取过程实质是La离子与基团P-OH遵循阳离子交换机制发生置换,以及与基团P=O发生络合配位作用,其萃取平衡常数KLa为10-0.02。

At pH1,La concentration is determined by EDTA volumetric titration in the two phases of P204-HCl-HAc extraction system,and study is made on the effect of solution acidity and extractant concentration on La distribution ratio.Based on the infrared spectrum testing and analysis of La loaded organic phase in the P204-HCl-HAc system,investigation is made on the extraction mechanism of La in P204-HCl-HAc system and the extraction equilibrium constant is determined.The results show that at pH1,the extraction is actually a displacement reaction between La and group P-OH based on the cation exchange mechanism and complexing and coordination action between La and group P=O with extraction equilibrium constant KLa is 10-0.02.