Synthesis and metal ion uptake studies of chelating resins derived from formaldehyde–furfuraldehyde condensed phenolic Schiff bases of 4,4′-diaminodiphenylether and o-hydroxyacetophenone

Two new chelating resins (o-HAP-DDE-HCHO and o-HAP-DDE-FFD), having multiple functional groups are synthesised by condensing the Schiff base of o-hydroxyacetophenone-4,4′-diaminodiphenylether (o-HAP-DDE) with formaldehyde and furfuraldehyde, respectively. The extent of loading of metal ions Cu(II) and Ni(II) was studied in both competitive and non-competitive conditions varying the time of contact, metal ion concentration and the pH of the reaction medium. Both the resins are able to preferentially remove Cu(II) from the mixture of Cu(II) and Ni(II) at a pH 5.89 in the batch operation, maximum % uptake being 76.8 and 84.1, respectively, for o-HAP-DDE-HCHO and o-HAP-DDE-FFD. The furfuraldehyde condensed resin was found to be more effective in removing Cu(II) ions than the formaldehyde condensed resins in batch technique. The resins exhibited little affinity for alkali and alkaline earth metal ions. Further, the furfuraldehyde condensed resin was utilised in column operation for removing Cu(II) ions. Elution study with HCl (>1.0 mol l−1) resulted in removal of nearly 40–50% of loaded Cu(II) from the resin column.