Liquid–liquid extraction of aluminium(III) from mixed sulphate solutions using sodium salts of Cyanex 272 and D2EHPA

Liquid–liquid extraction of aluminium(III) from sulphate medium using sodium salt of Cyanex 272 and D2EHPA in kerosene have been studied. The influences of the following parameters were investigated: equilibrium pH, extractant concentration, organic/aqueous phase ratio, temperature and diluent type. Extraction of Al(III) increased with increasing equilibrium pH and extractant concentration. Maximum Al(III) extraction was achieved in the equilibrium pH range of 3.2–3.6 and 3.5–4.2 for Na-Cyanex 272 and Na-D2EHPA, respectively. Temperature had a positive effect on Al(III) extraction in case of Na-Cyanex 272. On the other hand, when Na-D2EHPA was used, increasing temperature had negligible effect on Al(III) extraction. Aliphatic diluents were preferred compared to aromatic diluents because of higher extraction, good separation factor, short equilibrium time and good phase separation. Quantitative Al(III) extraction efficiency was achieved with 0.30 M extractant in two stages, at an aqueous:organic (A:O) phase ratio of 1:1. Complete stripping of Al(III) from the loaded organic containing 2.4 g/L Al(III) was carried out using 1.0 M H2SO4 at an A:O phase ratio 1:1 in a single stage.