Extraction of indium from sulfuric acid solutions by mixtures of di-(2-ethylhexyl)phosphoric and octanoic acids

The extraction of indium. from sulfuric acidic solutions by mixtures of di(2-ethylhexyl)phosphoric (D2EHPA, HR) and octanoic (HA) acids was studied. The state of D2EHPA in octanoic acid was investigated by IR-spectroscopy. It was shown that the nonideal behavior in this system occurs due to the partial dimerization of D2EHPA in organic phase. A strong antagonistic effect observed during the extraction of indium is caused by a HR-HA interaction at the expense of formation of intermolecular hydrogen bonds. Low indium concentrations and high excess of extracting agent, as well as application of "inert" diluents, result in the formation of In(HR2)(3) compound in organic phase.