Biosorption of chromium(III) by Sargassum sp biomass

Chromium is present in different types of industrial effluents, being responsible for environmental pollution. Traditionally, the chromium removal is made by chemical precipitation. However, this method is not completely feasible to reduce the chromium concentration to levels as low as required by environmental legislation. Biosorption is a process in which solids of natural origin are employed for binding heavy metals. It is a promising alternative method to treat industrial effluents, mainly because of its low cost and high metal binding capacity. In this work the chromium biosorption process by Sargassum sp. seaweed biomass is studied. Sargassum sp. seaweed, which is abundant in the Brazilian coast, has been utilized with and without milling. The work considered the determination of chromium-biomass equilibrium data in batch system. These studies were carried out in order to determine some operational parameters of chromium sorption such as the time required for the metal-biosorbent equilibrium, the effects of biomass size, pH and temperature. The results showed that pH has an important effect on chromium biosorption capacity. The biosorbent size did not affect chromium biosorption rate and capacity.5213314

Modeling of copper(II) biosorption by marine alga Sargassum sp in fixed-bed column

The biosorption of copper(II) by the marine alga Sargassum sp. was investigated in a batch reactor and in a fixed-bed column (temperature = 30 degreesC; pH 3.5). Langmuir and Freundlich sorption models were used to represent the equilibrium data. Experimental breakthrough curves in a fixed-bed column were obtained with a flow rate of 6 ml/min and feed concentration of 1, 2, 3 and 6 meq/l. A model that describes the dynamics of copper(II) ion sorption in the column was obtained from the mass balance in the fluid phase and the biosorbent. According to mass transfer three equations are available to represent the rate of adsorption. The model parameters: mass transfer coefficients, axial dispersion coefficients and constants of the kinetic equation, had their values adjusted from the experimental breakthrough curves. The model in which the mass transfer is controlled by diffusion in the biosorbent best represented the fixed-bed column dynamics. (C) 2002 Elsevier Science Ltd. All rights reserved.38579179

BIOSORPTION STUDY OF Ni2+ AND Cr3+ BY Sargassum filipendula: KINETICS AND EQUILIBRIUM

In this work, the biosorption of Cr3+ and Ni2+ by Sargassum filipendula pre-treated with CaCl2 was studied. Kinetic and equilibrium experiments were carried out for mono- and multi-component solutions in a batch reactor at pH 3.0 and 30 degrees C. The results from the kinetic experiments showed that Cr3+ adsorbs slower than Ni2+. This behavior was explained by means of a mechanistic analysis, which showed that Cr3+ uptake presented three adsorption stages, whereas Ni2+ 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 Cr3+ removal are slower, the biomass had a stronger affinity for this ion. Almost all Ni2+ is desorbed from the biomass as Cr3+ 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 Cr3+/Ni2+ adsorption, which is a system rarely found in the literature and that provides information that could be used in process modeling and simulation.31121122

Biosorption of Chromium(III) and Copper(II) Ions onto Marine Alga Sargassum sp in a Fixed-bed Column

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