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

Abstract

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 SFGa/In reached 995, which is higher than those obtained with its analogues such as Cextrant 230 (SFGa/In = 471) and BEADP (SFGa/In = 201) at the optimum acidity conditions. The extracted complexes were determined to be HGaCl4L2 and InCl3L2. 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, H2SO4 and HNO3. A process was established for the separation and purification of gallium, by which the purity of Ga2O3 increases from 98.4% to 99.97% with a yield of 92.5%.