Evaluation, interpretation, and representation of three-metal biosorption equilibria using a fungal biosorbent

Equilibrium metal uptake performance of Rhizopus arrhizus was studied using aqueous solutions containing Cr(VI), Fe(III) and Cu(II) ions in ternary mixtures. The multimetal biosorption equilibria were described by the multicomponent Langmuir and Freundlich models. The multicomponent Langmuir model generally described the experimental results better than the multicomponent Freundlich model. To represent the three-metal biosorption equilibrium data, three-dimensional (3-D) biosorption surfaces instead of two-dimensional biosorption isotherm curves and triangular equilibrium diagrams whereby the effect of the third ion is not ignored were used. For three-metal biosorption with equal initial molar concentrations, the relative surface coverage of Cr(VI), Fe(III), and Cu(II) on the biomass was approximately 45-55, 36-41 and 8-14%, respectively. (C) 2001 Elsevier Science Ltd. All rights reserved.