Study on EDTA-chelated copper adsorption by granular activated carbon

Equilibrium and kinetic experiments on uptake of single-species copper, EDT A, and EDTA-chelated copper by an H-type granular activated carbon under va rious factors, such as pH, ionic strength and EDTA concentration were carri ed out in this study. Adsorption of copper ions was increased with an incre ase in solution pH when the solution contained single-species or EDTA-chela ted copper ions. The solution pH increased significantly from its lower ini tial value, which resulted from the adsorption of hydrogen ions by the carb on. The efficiency for the single-species metal ion removal was increased f rom 5 to 95% when the solution pH was increased from 2 to 7.5. EDTA-chelate d metal ion removal, however, was increased from 7 to 97% as the pH was inc reased from 1.5 to 7.5. EDTA adsorption percentages increased when the solu tion pH was increased and the initial concentration was decreased. Slightly higher EDTA-chelated copper removal was observed when the ionic strength w as higher and the ratio of EDTA to copper concentrations was 1:1. Kinetic e xperiments demonstrated that the copper adsorption occurred rapidly in the first hour. No further change in the removal was observed after 3 and 6 h f or 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. (C) 2000 Society of Chemical Industry.