Separation of trace amounts of aluminium on a strong anion-exchange resin loaded with a sulphonated azo dye

Abstract

The sulphonated azo dye Chromotrope 2B is sorbed quantitatively by the strong anion exchanger AG 1-X8. A chelating resin is obtained, which is able to sorb aluminium from aqueous solutions selectively. The distribution equilibria were investigated under different conditions and interpreted on the basis of a Donnan equilibrium based model for the resin. A separation and pre-concentration method for aluminium in natural waters is proposed, based on the use of the modified resin in a column at ambient pressure. The selectivity with respect to other metal ions was good; this was to be expected because Chromotrope 2B in solution is also selective for aluminium. Recoveries of 100 ± 1% were obtained, with a pre-concentration factor of 50, at a total aluminium concentration of 2 × 10^–6 mol kg^–1.