The Adsorption Characteristics of EDTA-Chelated Copper Ion by Activated Carbon in a Column Test

Abstract

ABSTRACT The adsorption behavior of EDTA—chelated copper on activated carbon is described based on a consideration of electrostatic interaction and complexation of species. In this paper a series of column adsorption experiments is conducted to obtain more design data. Experimental studies indicate the adsorption behavior? of chelated copper on activated carbon varies over the entire pH range, depending on the surface charge characteristics of activated carbon and the species distribution of metal and ligand. The extent of adsorption of copper and EDTA is significantly different at lower pH values. The extent of adsorption of EDTA—Cu chelates is higher than that of free copper ions in the solution. One modified model, termed the Bed-Depth-Service-Time (BDST) model, is used to relate the service time of a column to the bed mass. It is shown that the model data adequately describe the adsorption behavior of EDTA-chelated copper on activated carbon. The estimated constants might be used to estimate the service time of carbon dosage, but because deviation exists between the fitting curve and the experimen- tal data obtained at later experimental periods, more study will be necessary to modify the model equation.