The removal of copper from aqueous solutions by biosorption onto grape-stalks and pine bark biomass is reported. The adsorption isotherms were determined, along with the effect of different variables, such as the pre-treatment of the biomass, pH, metal concentration and reaction time on the copper removal efficiency. The uptake capacity for copper with grape stalks and with pine bark is 19.9 mg/g and 49.8 mg/g, respectively. In both cases, the biosorption is favoured by an increase in pH. The pre-treatment of the pine bark with a solution containing 0.005M of calcium chloride increases 20% its uptake capacity. The kinetics of copper biosorption in both biomasses was studied and a pseudo second order model was used to fit the experimental data. Copper biosorption is a fast process and within the first 2 minutes 80% of the metal is removed from the solution. The elution experiments shows that all the copper bound to the grape stalks could be eluted using a solution containing 1 molar of sodium sulphate and 0.1 M of tri-sodium citrate, and no more than 84% (maximum) of the copper bound to pine bark could be eluted using an acid solution of H₂SO₄ 3.7 M. The biomasses did not loose their binding capacity for, at least, four cycles of biosorption/elution.


Keywords: Grape stalks; pinus-bark; biosorption; elution



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