Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The simultaneous biosorption of chromium(III) and copper(II) ions onto Sargassum sp. alga in a fixed-bed column reactor was investigated. Experiments were undertaken to determine the effect of the feed concentration (1, 2, 3 and 6 mequiv/l) and the composition of the metal ion solution [0.25, 0.50 and 0.75 Cu(II)/Cr(III) ratio] on the behaviour of the breakthrough curves. A mathematical model was applied to describe the biosorption in a fixed-bed column. Equilibrium was described in this model in terms of a binary Langmuir-type adsorption process, together with mass transfer in the biosorbent based on the Linear Driving Force (LDF) model. The partial differential equations for the system were solved numerically by the finite volume method. The proposed mathematical model for the biosorption process provided a satisfactory description of the dynamics of metal ion removal in the column relative to the experimental data obtained. The adsorptive capacity of the biomass for Cr(III) ions in the binary system was greater than that for Cu(II) ions. The developed model could provide a useful tool for the optimization of Cr(III) and Cu(II) ion removal processes by Sargassum sp. biomass and the design of the corresponding fixed-bed columns.O TEXTO COMPLETO DESTE ARTIGO, ESTARÁ DISPONÍVEL À PARTIR DE FEVEREIRO DE 2015.285449464Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CNPq [478496/2007-9]