Abstract
The extraction equilibrium of indium(III) from a nitric acid solution using di(2-ethylhexyl) phosphoric acid (D2EHPA) as an acidic extractant of organophosphorus compounds dissolved in kerosene was studied. By graphical and numerical analysis, the compositions of indium-D2EHPA complexes in organic phase and stoichiometry of the extraction reaction were examined. Nitric acid solutions with various indium concentrations at 25 °C were used to obtain the equilibrium constant of InR3 in the organic phase. The experimental results showed that the extraction distribution ratios of indium(III) between the organic phase and the aqueous solution increased when either the pH value of the aqueous solution and/or the concentration of the organic phase extractant increased. Finally, the recovery efficiency of indium(III) in nitric acid was measured.
Highlights
Indium is a crucial metal in the electronics industry
According to the potential-pH equilibrium diagram [18], when the pH value was below 2.5, the indium ions in an aqueous solution were primarily in the form of In3+
When the pH value was between 1 and 3, indium ions in the aqueous phase were present in the form of In(OH)2+ [5]
Summary
Indium is a crucial metal in the electronics industry. Indium tin oxide (ITO) is widely used and plays an important role in the LCD and solar energy industries. Indium is scarce in the Nature, and is estimated to be 0.05 part per million in the continental crust. In 2009, the average annual price of indium was 500 USD/kg. The price is around the 565 USD/kg [1]. The development of technology for recovery of indium from waste material will be critical needed to meet
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