首页> 外文期刊>Iranian Journal of Chemistry and Chemical Engineering >Improved Extraction-Separation of Lanthanum/Europium Ions by Bis(2-ethylhexyl)phosphoric Acid Using 12-Crown-4 as an Ion Selective Masking Agent
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Improved Extraction-Separation of Lanthanum/Europium Ions by Bis(2-ethylhexyl)phosphoric Acid Using 12-Crown-4 as an Ion Selective Masking Agent

机译:使用12-Crown-4作为离子选择性掩蔽剂的双(2-乙基己基)磷酸改进镧/ Euro离子的萃取分离

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摘要

The extraction-separation of lanthanum and europium ions with bis(2-ethylhexyl) phosphoric acid (DEHPA) in cyclohexane was improved by adding 12-crown-4 (12C4) to the aqueous phase as a masking agent. In the presence of this crown ether the extraction curve of lanthanum ions versus pH shifts to the higher pH region, while the curve is not influenced for the europium ions. Consequently the separation of these ions is enhanced. The treatment of the extraction data in the presence of 12C4 allows to determine the stability constant of the lanthanum-crown ether complex in the aqueous phase. The results have been compared with those reported using 18-crown-6 (18C6). This comparison shows that the improvement in the separation of La/Eu in the presence of 12C4 is the same order as in the presence of 18C6. The influence of temperature on the extraction of the studied cations in the absence and the presence of 12C4 by DEHPA in cyclohexane is studied in the range 293-305 K. This study leads to assess the thermodynamic parameters i.e. the free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) changes associated with the extract ion process as well as those of the complexation of lanthanum ions by 12C4 in aqueous phase.
机译:通过在水相中添加12-crown-4(12C4)作为掩蔽剂,可以改善双环(2-乙基己基)磷酸(DEHPA)中镧和euro离子的萃取分离效果。在存在这种冠醚的情况下,镧离子相对于pH的萃取曲线移至较高的pH区域,而while离子对该曲线没有影响。因此,增强了这些离子的分离。在12C4存在下对萃取数据的处理可以确定镧-冠醚络合物在水相中的稳定性常数。将结果与使用18-crown-6(18C6)报告的结果进行了比较。该比较表明在12C4存在下La / Eu分离的改进与在18C6存在下的改进顺序相同。在293-305 K范围内,研究了温度对在环己烷中不存在和存在DEHPA的情况下由DEHPA萃取12C4阳离子的影响。该研究旨在评估热力学参数,即自由能(ΔG°),焓(ΔH°)和熵(ΔS°)的变化与萃取离子过程以及水相中12C4与镧离子的络合有关。

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