Comprehensive Investigation of Important Factors Governing Metal-Ion Adsorption by an H-Type Granular Activated Carbon

Abstract

A comprehensive experimental investigation of metal ion adsorption by Filtrasorb 200, an H-type activated carbon, was carried out. Potentiometric titration of the carbon showed that surface charge was increased with a decrease in pH. Its absolute value increased with an increase in ionic strength. Higher pH and ionic strength and lower initial concentration increased the metal-ion removal percentage. The removal capacity for a single metal ion was in the following descending order: Cu > Zn ≈ Co. Experiments with competitive metal ions showed that adsorption of zinc and cobalt ions was reduced dramatically with the addition of copper, while adding zinc or cobalt was less important for copper removal.

Kinetic study showed that most copper removal occurred in the first hour and was completed within 4 h. Mass transfer was an important controlling factor in the metal uptake rate. The effect of pH on the removal kinetics seemed to be insig nificant; however, higher ionic strength and initial metal concentration can result in faster adsorption. Adsorption kinetics was much faster for copper than for zinc. The addition of competitive metal ions did not affect other metal-ion adsorption kinetics.

Keywords:

• Adsorption
• Metal ions
• Equilibrium
• Kinetics
• Multi-component
• Competitive effect

ACKNOWLEDGMENT

This work was supported by a research grant (RP 3981604) from the National University of Singapore.