三辛胺萃取一氯乙酸的特性及机理

Extraction behavior and mechanism of mono-chloroacetic acid by tri-octylamine

为深入认识反应萃取机理 ,以一氯乙酸为被萃溶质 ,三辛胺 (TOA )为反应萃取剂 ,分别以正辛醇、苯、正己烷、四氯化碳和氯仿为稀释剂 ,进行了萃取平衡特性及负载溶剂红外光谱分析的实验研究。结果表明 ,TOA能负载比其浓度还高的羧酸 ;稀释剂对萃取能力的影响与酸的浓度有关 ;相同稀释剂、不同 TOA浓度条件下的负载量十分接近 ;5种稀释剂的饱和负载量的大小顺序依次为正己烷、四氯化碳、苯、氯仿、正辛醇 ,即极性越弱 ,饱和负载量越大。TOA与一氯乙酸在非极性稀释剂中更易形成 2 :1、 3:1型酸胺比的萃合物。红外光谱分析结果表明 ,负载有机相中存在羧酸的聚集体。同时 ,还探讨了离子对型萃合物百分率 (I)

This paper investigated the reactive extraction mechanism of mono-chloroacetic acid by tri-octylamine (TOA) in various diluents, such as octanol, benzene, hexane, carbon tetrachloride and chloroform. The extraction equilibrium of mono-chloroacetic acid and the IR spectra of organic-sample-loading solvent were also studied. The results showed that the extraction equilibrium behavior varied with the acid concentration in the aqueous phase. With the same diluent, the TOA loadings were similar for various TOA concentrations. For relatively low acid concentrations, the extraction capacity in a polar diluent was higher than that in an inert diluent. The acid formed 2∶1 and 3∶1 complexes with TOA more easily in the inert diluent than in the polar diluent. The relationship between the molar fraction of the ion-pair association and the extraction equilibrium was also investigated. The IR spectrum results prove that dimer exists in the organic phase.