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Grape Stalks Waste as Low Cost Biosorbents: An Alternative for Metal Removal from Aqueous Solutions

Abstract Grape stalks waste generated in the wine production process has been investigated as metal sorbent for Pb(II), Ni(II), Cu(II), and Cd(II) from aqueous solutions. Kinetic studies revealed that the initial uptake was rapid and equilibrium was established in one hour. The results obtained from batch experiments at initial pH 6.0±0.5 were described by the Langmuir isotherm. The highest value of the Langmuir maximum uptake, (q max ), was found for cadmium (0.248 mmol g−1) followed by lead (0.241 mmol g−1), nickel (0.181 mmol g−1), and copper (0.159 mmol g−1). Column experiments were also performed at a constant metal concentration of around 0.250 mmol dm−3 at pH 6.0±0.5 and the results were modelled by means of the reactive transport code RETRASO (REactive TRAnsport of SOlutes) applying a Langmuir sorption mechanism as well. The values obtained from both experimental approaches are found to coincide fairly well. The Langmuir constants (L mol−1) determined are: Copper (1.5 · 103 and 1.0 · 104), Nickel (1.4 · 103 and 2.5 · 103), Lead (8.3 · 104 and 3.5 · 103), and Cadmium (7.0 · 103 and 4.5 · 103), where values in parenthesis correspond to the batch and column determinations, respectively.