In this work, biosorption of trivalent chromium by the marine brown algae Sargassum muticum was
37 studied in a batch system. The effect of the solution pH on Cr(III) uptake by Sargassum was
38 investigated. Kinetics and equilibrium experiments were conducted at different pH values (3.0, 4.0 and
39 5.0). Equilibrium data are well described by the Langmuir and Langmuir-Freundlich isotherms and
40 kinetics follows the pseudo-second-order model, at different pH values. The two mass transfer models
41 give comparable results, but they did not provide a perfect representation of the sorption data. The
42 homogeneous diffusivity, Dh, was found to be around 1.6´10-8 cm2 s-1 for 100 mg l-1 Cr(III)
43 concentration.
44 Sargassum muticum was compared with the brown algae Laminaria hyperborean and the red algae
45 Gelidium sesquipedale in terms of uptake capacity. The maximum uptake capacities for Sargassum,
46 Laminaria and Gelidium were, respectively, 56 ± 3, 70 ± 4 and 18 ± 1 mg Cr(III) g-1, at pH = 5.
