Uptake of copper (II) ions from acidic aqueous solutions using a continuous column packed with microcapsules containing a β-hydroxyoximic compound

In this paper, the uptake of Cu(II) ions from an acidic aqueous solution using a continuous column packed with microcapsules containing the chelating extractant LIX-860 N-IC was examined. A simple, economical method was employed to synthesise the microcapsules' polymeric matrix consisting of an in situ radical polymerisation method followed by the subsequent impregnation of the extractant compound 5-nonylsalicylaldoxime. The microcapsules had a spherical shape with a rough surface and a strong hydrophobic character that assured that the organic extractant was immobilised on the microspheres' porous structure. During the metal sorption experiments, three different columns were used, and the aqueous feed solution circulated through them at different flow rates in repetitive sorption-desorption cycles. The results of these experiments revealed that the metal extractability was improved when the flow rate of the feed phase decreased and when the largest column was used, likely because of the higher residence time of the solution in the column improving the solution's contact with the microcapsules and also because of an increase in the vacant sites for the sorption process. The experimental data of the metal sorption onto the microcapsules in the fixed bed columns were explained by three different models (Wang, Thomas and dose-response). In general, the three predictive equations fit the dynamic behaviour of the breakthrough curves well. However, the modified dose-response model correlated better with the experimental data than the other model equations, as shown by the statistical parameters determined from the experimental conditions used. (C) 2011 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.