Study of the amine primene 81R sulphate-Fe2(SO4)3 extraction equilibrium system at low temperatures

Abstract

The extraction of iron(III) from aqueous sulphate solutions by Primene 81R sulphate at low temperatures was studied as a function of iron(III) and amine sulphate concentrations. In the range of temperatures between 8 and 5°C a complex with the stoichiometric formula 4(RNH3)2SO4·[Fe(OH)SO4]2 is extracted. The extraction reaction may occur by adduct formation between the amine sulphate and the species [Fe(OH)SO4]2 from the aqueous phase and not by an anion exchange reaction. The extracted complex is a monomer in benzene solution; the spectral study suggests that the [Fe(OH)]4+2 unit is present in its structure and the sulphate groups act as bidentate ligands.