Removing copper, zinc, and lead ion by granular activated carbon in pretreated fixed-bed columns

Adsorption experiments by pretreated fixed-bed columns for single-species (Cu, Zn, and Pb) and multi-species (Cu-Zn, Cu-Pb, and Cu-Pb-Zn) metal ions were carried out in this study. It was demonstrated that the breakthrough occurred more slowly with an increasing influent pH and a decreasing flow rate. An increase in ionic strength slightly increased copper removal, but it did not affect zinc removal. Experiments on competitive adsorption illustrated that the removal of metal ions was decreased when additional metal ions were added. The effect was more significant for zinc as the activated carbon was less favourable for its removal. The removal of these three metal ions by the activated carbon columns followed the descending order: Cu > Pb > Zn. Copper and zinc removal was increased significantly when EDTA was added to the influent. At the same time, the removal of copper was almost the same as that of zinc. An increase in ionic strength caused a decrease in the removal of copper and zinc ions complexed with EDTA. (C) 2000 Elsevier Science B.V. All rights reserved.