Adsorption of copper(II) and EDTA-chelated copper(II) onto granular activated carbons

Abstract

Waste streams generated by electroless copper plating in the printed circuit boards manufacturing industry often contain copper complexed by strong chelating agents such as EDTA. The consequence of metal complexation by chelating agents is that alternative treatment to chemical precipitation is often necessary to achieve the low metal concentrations required by increasingly stringent environmental regulations. This paper examines the feasibility of using activated carbon to remove EDTA-chelated copper(II) species as well as free copper(II) ions from aqueous solution. The adsorption characteristics of copper(II) and EDTA-chelated copper(II) on two granular activated carbons prepared from coal and coconut shell were evaluated. Adsorption equilibrium data of copper(II) on the two carbons corresponded well to the Langmuir model. The coconut shell-based carbon exhibited a greater adsorption capacity for copper(II) than the coal-based carbon under similar experimental conditions. Solution pH had a considerable in¯uence on copper(II) adsorption by the two carbons. Low adsorption levels of copper(II) at pH 3 and high adsorption levels in the pH range of 4±6 were observed. However, a reverse adsorption trend was observed when the chelating agent EDTA was added to the copper(II) solution. Adsorption of EDTA-chelated copper(II) by the two carbons was higher at pH 3 than at pH 6. The contrasting adsorption behaviour of copper(II) ions and EDTAchelated copper(II) species can be readily explained in terms of electrostatic interaction in that solution pH in¯uences the surface charge of the carbons as well as the charge property of copper(II) ions and EDTA-chelated copper(II) species.

Removal of Cu2+ from aqueous solution by chitosan-coated magnetic nanoparticles modified with α-ketoglutaric acid

“…The species formed by hydrolysis of copper salt are discussed by Chu and Hashim [40], and Baes and Mesmer [41]. As they explained, the main hydrolyzed copper species in the pH range of 3-6 appear to be Cu 2+ (unhydrolyzed species), Cu(OH) + , and Cu(OH) 0− 2 .…”

Dispersion of chitosan on perlite for enhancement of copper(II) adsorption capacity

“…The species formed by hydrolysis of copper salt are discussed by Chu and Hashim [43] and Baes and Mesmer [44]. The main hydrolyzed copper species in the pH range of 3-6 appear to be Cu(II) (unhydrolyzed species), Cu(OH) + , and Cu(OH) 2 0− .…”

Effect of EDTA on divalent metal adsorption onto grape stalk and exhausted coffee wastes

“…Gyliene et al [30] found around 45% decrease on copper sorption onto chitosan at pH 3 and 1:0.5 metal-EDTA molar ratio; Chu and Hashim [32] reported that copper removal efficiency at pH 6 decreases from 80% to 30% and to 40% when using as sorbent coal-based and coconut shell-based activated carbons, respectively, at 1:1 metal-EDTA molar ratio.…”

“…While sorption of different heavy metal ions on its free form on low cost sorbents has been widely studied [27][28][29], little effort has been focused on studying the effect of organic complexing agents on metal ions removal [4,[30][31][32][33][34].…”