Removal of copper from aqueous solutions by adsorption on activated carbons

The adsorption isotherms of Cu(II)) ions from aqueous solutions in the conc entration range 40-1000 mg l(-1) on two samples of granulated and two sampl es of activated carbon fibres containing varying amounts of associated oxyg en have been reported. The adsorption isotherms are type I of BET classific ation showing initially a rapid adsorption tending to be asymptotic at high er concentrations. The amounts of oxygen associated with the carbon surface has been enhanced by oxidation with nitric acid and ammonium persulphate i n the solution phase and with oxygen gas at 350 degreesC and decreased by d egassing of the oxidized carbon samples at 400, 650 and 950 degreesC. The a dsorption of Cu(II) ions increases on oxidation and decreases on degassing. The increase in adsorption on oxidation depends on the nature of the oxida tive treatment while the decrease in adsorption on degassing depends on the temperature of degassing. This has been attributed to the increase in the carbon-oxygen acidic surface groups on oxidation and their decrease on dega ssing. Suitable mechanisms consistent with the results have been proposed. (C) 2001 Elsevier Science B.V. All rights reserved.