Application of multicomponent adsorption models to the biosorption of CR(VI), CU(II), and CD(II) ions on rhizopus arrhizus from ternary metal mixtures

Abstract

Instantaneous and equilibrium metal uptake performance of Rhizopus arrhizus was studied using aqueous solutions containing Cr(VI), Cu(II), and Cd(II) ions in ternary mixtures. Application of the multicomponent Langmuir model to describe the three-metal system revealed its nonideal characteristics, whereby the values of the equilibrium constants and the maximum capacities for the metals differed for each system. For that reason, the ternary biosorption equilibria of Cr(VI), Cu(II), and Cd(II) ions with R. arrhizus were further investigated by using the multicomponent Freundlich model. From the equations of the multicomponent Freundlich model, three-dimensional (3-D) biosorption isotherm surfaces were simulated depicting the equilibrium behavior of the three-metal system.