Studies On Solvent Extraction Behavior Of Rare Eatrh Elements, Gallium And Indium

(Ⅲ) and indium （Ⅲ）. In recent years, rare earth elements （REEs）, gallium （Ⅲ） andindium （Ⅲ） received more and more attention in high-technology. For example,gallium （Ⅲ） and indium （Ⅲ） are used as semiconductor materials such as InP orGaAs. REEs are applied to phosphors, glass, laser, ceramic technology and so on.However, the mutual separation of REEs is widely recognized to be difficult becauseof their similar physical and chemical properties. And also, the two metals of gallium（Ⅲ） and indium （Ⅲ） show similar chemical behaviors.With the increasing demand for high purify REEs gallium （Ⅲ） and indium （Ⅲ）,the separation and purification of these metal ions have gained considered attention.As a branch of solvent extraction, sysnergistic extraction has become a commonmethod for the extraction and separation of metal ions. It can not only enhance theextraction efficiency and the stability of extracted complexs, but also improve theextraction selectivity. In the present work, sec-nonylphenoxy acetic acid （CA100） wasselected as the main extractant.Firstly, the synergistic solvent extraction of REEs with mixtures of CA100and2,2’-bipyridyl （bipy） in n-heptane from nitrate medium have been studied. Themixtures of CA100and bipy have significant synergistic effects on all the REEs.Holmium （Ⅲ） was selected as the example to investigate the extraction mechanism.The extracted compound is determined asHo（NO₃）₂HA₂B with the mixture instead ofHoH2A5, which is extracted by CA100alone. The mixtures exhibit differentextraction effects on different REEs. Furthermore, the mixtures of CA100with bipyare proved to have great potential for the separation of Y from lanthanoids accordingto the separation factors.Secondly, the synergistic extraction of gallium （Ⅲ） and indium （Ⅲ） fromchloride medium with mixtures of CA100and other organic extractans, includingtrialkyl amine （N235）, N,N-di（1-methyl-heptyl） acetamide （N503）, tributyl phosphate（TBP）, and tiralkyl phosphine oxide （Cyanex923） has been investigated. The mixturesexhibit different extraction effects on gallium （Ⅲ） and indium （Ⅲ）. Compared withsingle CA100system, only CA100＋C923mixtures have higher separation ability ofgallium （Ⅲ） and indium （Ⅲ）. Therefore, CA100＋C923can be considered for theseparation of the two metal ions at the appropriate ratio of the extractants. Synergisticeffects are only found when indium （Ⅲ） is extracted with mixtures of CA100andN235. The methods of slope analysis and constant mole are used for the determinationof the reaction. The extracted complexes with CA100and CA100＋N235aredetermined asInCl₂HA_2（o）,andInCl₂H₃A₄B, respectively.