Solvent Extraction of Iron(III) and Aluminum(III) and Separation from Rhodium(III) in Chloride Solutions Added Tin(II) with Tri-n-octylamine

Chloride is one of the effective medium in which platinum group metals (PGMs) can be brought into a solution, thus chlorocomplexes are particularly important in the process chemistry of PGMs separations. Rh(III) chlorocomplexes are poorly extracted into organic solvents, which is due to the charge of the complex as well as those inert character in a solution, that is, formation of RhCl 6–n (H 2 O) n(3–n)– (n = 1–6). The problem of solvent extraction of Rh from chloride solutions has not yet been solved and there is no effective industrial extractant for Rh. Adding Sn(II) to a Rh(III) feed is a good procedure which can be used to make Rh react more easily to extraction. However, the impurities such as Fe(III) and Al(III) are also leached together from spent automobile catalysts with chlo- ride solutions. Therefore, the investigation of effect of Sn(II) on extraction of Fe(III) and Al(III) as impurities is important for the extraction of Rh from chloride solutions added Sn(II). In the present study, the effect of Sn(II) on extraction of Fe(III) and Al(III) from chloride solutions contained Sn(II) with tri-n-octylamine (TOA) was investigated for the separation from Rh(III). Al(III) was not extracted with TOA, either with or without Sn(II). Meanwhile, the extraction of Fe(III) decreased with increase in the concentration of Sn(II) and the separation of Rh(III) from Fe(III) was possible by concentrating Rh(III) and Sn(II) in the organic pahse.