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Liquid-liquid extraction of indium (III) from aqueous acid solutions by acid organophosphorus compounds

1992; Elsevier BV; Volume: 30; Issue: 1-3 Linguagem: Inglês

10.1016/0304-386x(92)90094-g

1879-1158

Taichi Sato, Keiichi Sato,

Extraction and Separation Processes

The distribution of indium (III) between sulphuric, nitric or hydrochloric acid solution and a solution of di-(2-ethylhexyl)-phosphoric acid (DEHPA) or 2-ethylhexyl 2-ethylhexyl-phosphonic acid (EHEHPA) in kerosene has been investigated under various conditions. The organic extracts were examined by infrared and nuclear magnetic resonance spectroscopy. As a result, it was found that the extraction efficiency for indium (III) of DEHPA is higher than that of EHEHPA, and that the effect of the kind of aqueous acid solution on the extraction of indium (III) is in the order HNO3 > H2SO4 > HCl at low aqueous acidity, but that this order becomes the reversed at higher acidity. The extraction by DEHPA shows that the distribution coefficient from sulphuric or nitric acid solutions diminishes monotonically with increasing aqueous acidity, while the distribution coefficient from hydrochloric acid solutions decreases monotonically with increasing aqueous acidity below 1 mol dm−3, and above this, acid concentration rises with acidity up to 5 mol dm−3 and falls again at higher acidities. The extraction curve of EHEHPA resembles that of DEHPA, although the distribution coefficient from hydrochloric acid solutions decreases slightly with aqueous acidity above 1 mol dm−3. The equilibrium equations are proposed on the basis of the results obtained.