Cr(III) uptake by marine algal biomass: equilibrium and kinetics

• Author(s): Vilar, Vitor ; Freitas, Olga ; Costa, Pedro ; Botelho, Cidália ; Martins, Ramiro ; Boaventura, Rui
• Date: 2011
• Persistent ID: http://hdl.handle.net/10198/7111
• Origin: Biblioteca Digital do IPB
• Subject(s): Sargassum; Gelidium; Laminaria; Equilibrium; Sargasskinetics; Marine algae
• Document Type: Article
• Language: English

Description

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.