Monday, April 30, 2007

Biosorption of cadmium(II) and zinc(II) in binary system by Sargassum sp

Cristiane A. Henriques, Aderval S. Luna, Antonio Carlos A. da Costa, and Bianca Barbosa D. Santos. Programa de Pós-graduação em Engenharia Quimica, Universidade do Estado do Rio de Janeiro - Instituto de Quimica, Rua São Francisco Xavier, 524 - PHLC - sala 310, Rio de Janeiro, 20559900, Brazil

A basic investigation on the simultaneous removal of Cd(II) and Zn(II) ions from aqueous solutions by Sargassum sp. was conducted at room temperature in batch conditions. The kinetics of the biosorption process followed a pseudo-second order model. Results indicated that cadmium and zinc uptake could be individually described by the Langmuir adsorption model. The maximum uptake capacities of the studied sorbent was equal to 1.1 mmol/g for cadmium and 0.7 mmol/g for zinc. This can be considered an excellent result when compared to conventional adsorbent materials. Thus Sargassum sp. has a great potential for removing cadmium and zinc ions especially when concentration of these ions are low in samples such as wastewater streams. However, when the solution contained both the metal ions, the total combined metal uptake capacity was reduced. The mechanism of this “interference” is difficult to elucidate due the complexity of biosorbent. At the same time, it is possible to estimate this “interference” from the modeling of the simultaneous equilibrium data using Langmuirian expressions.