The Freundlich and Langmuir isotherms were used to describe the biosorption of Cu(II), Pb(II), and Zn(II) onto the saltbush leaves biomass at 297 K and pH 5.0. The correlation coefficients (R) obtained from the Freundlich model were 0.9798, 0.9575, and 0.9963 for Cu, Pb, and Zn, respectively, while for the Langmuir model the R-2 values for the same metals were 0.0001, 0.1380, and 0.0088, respectively. This suggests that saltbush leaves biomass sorbed the three metals following the Freundlich model (R-2 > 0.9575). The K-F values obtained from the Freundlich model (175.5 center dot 10(-2), 10.5 center dot 10(-2). and 6.32 center dot 10(-2) mol center dot g(-1) for Pb, Zn, and Cu, respectively), suggest that the metal binding affinity was in the order Pb > Zn > Cu. The experimental values of the maximal adsorption capacities of saltbush leaves biomass were 0.13 center dot 10(-2), 0.05 center dot 10(-2). and 0.107 center dot 10(-2) mol center dot g(-1) for Pb. Zn, and Cu, respectively. The negative Delta G degrees values for Pb and the positive values for Cu and Zn indicate that the Pb biosorption by saltbush biomass was a spontaneous process. (c) 2006 Elsevier Ltd. All rights reserved.