BIOSORPTION STUDY OF Ni AND Cr BY Sargassum filipendula: KINETICS AND EQUILIBRIUM

In this work, the biosorption of Cr and Ni by Sargassum filipendula pre-treated with CaCl2 was studied. Kinetic and equilibrium experiments were carried out for monoand multi-component solutions in a batch reactor at pH 3.0 and 30 oC. The results from the kinetic experiments showed that Cr adsorbs slower than Ni. This behavior was explained by means of a mechanistic analysis, which showed that Cr uptake presented three adsorption stages, whereas Ni adsorption presents only two. The mono-component equilibrium data, along with binary kinetic data obtained from mono-component experiments, showed that, although the kinetics for Cr removal are slower, the biomass had a stronger affinity for this ion. Almost all Ni is desorbed from the biomass as Cr adsorbs. The binary equilibrium data also presented this behavior. The binary data was also modeled by using modified forms of the Langmuir, Jain and Snoeyink, and Langmuir-Freundlich isotherms. However, the prediction obtained presented low accuracy. An alternative modeling with artificial neural networks was presented and the results showed that this technique could be a promising tool to represent binary equilibrium data. The main contribution of this work was to obtain experimental data for Cr/Ni adsorption, which is a system rarely found in the literature and that provides information that could be used in process modeling and simulation.