In the present work, the use of powdered Chlorella vulgaris algal cells for copper biosorption was studied. The effects of contact time, biosorbent dose, equilibrium pH, and the presence of lead or/and zinc ions on the biosorption of copper were studied. The experimental results showed that C. vulgaris algal cells were effective in removing copper ions from aqueous solutions. The copper biosorption was dependent on equilibrium pH, and biosorbent dose. The presence of lead, zinc or both metals in aqueous solutions suppressed the removal of copper ions. Thermodynamic parameters for the biosorption of copper on algal cells depict the spontaneous nature of the biosorption process. The Langmuir, Freundlich, and Dubinin-Radushkevich isotherm models fitted the experimental data. The biosorption of copper on algal cells was rapid where equilibrium was attained within 15 min. The results of the kinetics studies revealed that the biosorption of copper on algal cells followed pseudo-second order kinetics. (c) 2005 Elsevier Ltd. All rights reserved.