Iron(III) Removal from Aluminum Sulfate Solutions by Sorption

Sorption of aluminum(III) and iron(III) from their individual solutions and of iron(III) impurity from Al2(SO4)3 solutions on macroporous resins, Puromet MTS9560 phosphonic acid cation exchanger and Puromet MTS9300 and Puromet S991 iminodiacetate ion exchangers, was studied. All the three resins show higher affinity for iron(III) than for aluminum(III). The Puromet MTS9560 cation-exchange resin shows the highest selectivity to iron(III) in sorption from an aluminum sulfate solution after introduction of sulfuric acid to its concentration of 2.2–2.5 M, and iminodiacetate ion-exchange resins, in sorption from a solution with рН 2.2–2.6. The Puromet MTS9300 resin synthesized on the styrene matrix surpasses the Puromet S991, resin synthesized on the acrylate matrix in the ability to uptake iron(III). Passing a solution containing 184 g L–1 Al2(SO4)3 and 2.9 g L–1 iron(III) with рН 2.3 through a column packed with Puromet MTS9300 resin leads to deep removal of the iron(III) impurity to the residual concentration no higher than 0.002 g L–1. Iron(III) can be desorbed from the resin virtually completely with a 1 M sulfuric acid solution.