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Biosorption of Copper by Grape Stalks and Pine Bark Biomasses

R. Machado, C. Santos, M. Joana Neiva Correia, J.R. Carvalho

Department of Chemical Engineering, Instituto Superior Técnico, Av. Rovisco Pais, 1045-001, Lisbon, Portugal


Received 30 June 2002; accepted 15 January 2003



ABSTRACT

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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