An extensive experimental Investigation was conducted with activated carbons to establish the adsorption capacities of heavy metals (Cd2+, Ni2+, Cu2+, and Zn2+) in the presence of complexing agents (EDTA, triethylenetetramine (TRIEN), citrate, etc.). Adsorption equilibria are explained by species charges and carbon surface charge characteristics. In the pH range 7.5—8.0, the active sites are positively charged. The adsorption capacities of Cd2+ (and other heavy metals), free ligands, and cadmium-ligands are also a function of feed metal concentration, types of ligands, molar ratio of ligand/metal, and pH. Complete metal-ligand species distributions are calculated by computer solutions of multiple reaction equilibria. For an equilibrium cadmium concentration of 0.1 mM (pH 7.5-8.0), the sequence in adsorption capacity for cadmium chelates is Qcd-EDTA > Qcd-chrate > Qcd-TRIEN > Qcd-tartrate. A relationship between the adsorption capacity, surface charge of activated carbon, and the average species charge for various cadmium ligands systems is presented.
|Number of pages||23|
|Journal||Chemical Engineering Communications|
|State||Published - Nov 1 1983|
Bibliographical noteFunding Information:
This research was supported in part by the U.S. Environmental Protection Agency Grant CR-80 7760 and a graduate fellowship (to M. Jevtitch) from the Rotary Foundation. The authors gratefully acknowledge the valuable contributions of Alfred B. Craig, Jr. of the U.S. EPA.
ASJC Scopus subject areas
- Chemistry (all)
- Chemical Engineering (all)