酸度对D_2EHPA-HCl-HAc体系萃取Ce(Ⅲ)的机理影响

EFFECT ON EXTRACTION MECHANISM OF Ce IN D_2EHPA-HCl-HAc EXTRACTION SYSTEM BY ACIDY

本文在pH>1、0<pH≤1两种不同pH条件下,采用EDTA容量滴定法测定D2EHPA-HCl-HAc体系萃取Ce过程两相中的Ce浓度来考察酸度对Ce分配比的影响,并对D2EHPA以及D2EHPA-HCl-HAc体系负载Ce有机相进行红外光谱测试分析来探究溶液酸度对D2EHPA-HCl-HAc体系萃取Ce(Ⅲ)的机理影响。研究结果表明,当pH>1时,萃取过程的实质主要为萃取剂D2EHPA中基团P-OH与Ce(Ⅲ)发生的置换反应,其反应过程遵循阳离子交换机制;当0<pH≤1时,萃取过程为占主导优势的基团P=O与P-OH同时参与的与Ce(Ⅲ)的配合作用,其反应过程遵循阳离子交换和溶剂化配合双重机制,该机制增强了对Ce的萃取能力,使萃取容量提高。

In the conditions of pH 〉1 and 0〈pH≤1,Ce concentration determined by volumetric precipitation method of EDTA in the two phase of D2EHPA-HCl-HAc extraction system,which is studied the effect on distribution ratio of Ce by acidy in this article.And by infrared spectrum testing and analysis of D2EHPA and the organic phase loading Ce in the D2EHPA-HCl-HAc extraction system,the effect on extraction mechanism of Ce in D2EHPA-HCl-HAc extraction system by acidy is also studied.The results show that displacement reaction between Ce and P-OH happens and the extraction process abide by cation exchange mechanism in the condition of pH〉1.Then both the group of P=O and the group of P-OH can do complex reaction with Ce and the extraction mechanism is the dual mechanism theory of cation exchange mechanism and solvation complex mechanism,which can increase the extraction capacity of Ce in the condition of 0〈pH≤1