Industrial & Engineering Chemistry Research, Vol.47, No.4, 1277-1282, 2008
Pure metal chelate solutions by ion exchange
Aqueous solutions of the industrially important metal chelate ferric N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetate (FeHEDTA) have been made by adsorbing an iron salt (nitrate or sulfate) on Dowex MSC-I cation-exchange resin (Na form), flushing out the sodium salt, and eluting with Na(3)HEDTA. The resulting eluate contained FeHEDTA with iron concentrations approaching 2% that were free from sodium salts. Achieving industrially useful iron concentrations (>4.5%) required countercurrent ion exchange using an ISEP system. Careful manipulation of pH was required to prevent plugging due to precipitated iron oxide/hydroxide.