The study focuses on the simulation of dynamic biosorption in single and binary systems containing Cu(II) and Ni(II) ions using Sargassum filipendula (a marine algae). The Langmuir equilibrium models for single and binary systems were used to represent the equilibrium between solid and liquid phases. A mathematical model was used to describe the biosorption in fixed-bed columns. This model considers that the mass transfer in the biosorbent is the controlling step, which is described by the LDF (Linear Driving Force) concept. The mathematical model adequately fitted the breakthrough curves for both monocomponent and binary systems. The higher affinity of marine algae biomass for Cu(II) (over Ni(II)) was confirmed by the presence of an overshoot on Ni(II) breakthrough curves. The output detected in the experimental breakthrough curves was also predicted by the mathematical model. (C) 2011 Elsevier B.V. All rights reserved.