Study on EDTA-chelated copper adsorption by granular activated carbon

Abstract

Equilibrium and kinetic experiments on uptake of single-species copper, EDTA, and EDTA-chelated copper by an H-type granular activated carbon under various factors, such as pH, ionic strength and EDTA concentration were carried out in this study. Adsorption of copper ions was increased with an increase in solution pH when the solution contained single-species or EDTA-chelated copper ions. The solution pH increased significantly from its lower initial value, which resulted from the adsorption of hydrogen ions by the carbon. The efficiency for the single-species metal ion removal was increased from 5 to 95% when the solution pH was increased from 2 to 7.5. EDTA-chelated metal ion removal, however, was increased from 7 to 97% as the pH was increased from 1.5 to 7.5. EDTA adsorption percentages increased when the solution pH was increased and the initial concentration was decreased. Slightly higher EDTA-chelated copper removal was observed when the ionic strength was higher and the ratio of EDTA to copper concentrations was 1:1. Kinetic experiments demonstrated that the copper adsorption occurred rapidly in the first hour. No further change in the removal was observed after 3 and 6 h for single-species or EDTA-chelated, respectively. The EDTA-chelated copper adsorption kinetics was enhanced with an increase in EDTA concentration and a decrease in ionic strength. © 2000 Society of Chemical Industry