Selective extraction and separation of gallium(III) from indium(III) in chloride medium using di(2-ethylhexyl) (N, N′-di(2-ethylhexyl) amino methyl) phosphonate and stripping with water

An aminophosphonate extractant, di(2-ethylhexyl) (N, N′-di(2-ethylhexyl) amino methyl) phosphonate (abbreviated as L ) was synthesized and applied for the extraction and separation of gallium and indium from chloride solution. The maximum separation factors SF Ga/In reached 995, which is higher than those obtained with its analogues such as Cextrant 230 ( SF Ga/In  = 471) and BEADP ( SF Ga/In  = 201) at the optimum acidity conditions. The extracted complexes were determined to be HGaCl 4 L 2 and InCl 3 L 2 . The extraction reactions of gallium and indium were both endothermic. The loading capacities of 30 vol%  L for Ga and In were 32.9 g/L and 25.2 g/L, respectively. The loaded gallium and indium in organic phase can be effectively stripped by distilled water, H 2 SO 4 and HNO 3 . A process was established for the separation and purification of gallium, by which the purity of Ga 2 O 3 increases from 98.4% to 99.97% with a yield of 92.5%.