Competitive biosorption of cadmium(II) and zinc(II) ions from binary systems by Sargassum filipendula.

The present work describes our study on the competitive biosorption of Cd(II) and Zn(II) ions onto Sargassum filipendula from single component and binary systems. Results showed that S. filipendula was an efficient biosorbent for the removal of Cd(II) and Zn(II) ions from an aqueous solution. The equilibrium experimental data for the single component system for the two metallic species fitted well to Langmuir and Langmuir-Freundlich isotherm models. Seven isotherm models were tested with the equilibrium data for modeling of the binary system. Based on the sum of squares error, the Langmuir-Freundlich isotherm model showed the best fit to the binary adsorption data. The influence of the additional cation on the behavior of the biosorption of Cd(2+) and Zn(2+) was analyzed comparing single component and binary isotherms. It was observed that Zn(2+) had a relevant effect on the Cd(2+) biosorption, but the interference of Cd(2+) on the sorption of Zn(2+) was considerably less intense.

Kinetic modeling and equilibrium studies during cadmium biosorption by dead Sargassum sp. biomass.

A basic investigation on the removal of cadmium(II) ions from aqueous solutions by dead Sargassum sp. was conducted in batch conditions. The influence of different experimental parameters; initial pH, shaking rate, sorption time, temperature and initial concentrations of cadmium ions on cadmium uptake was evaluated. Results indicated that cadmium uptake could be described by the Langmuir adsorption model, being the monolayer capacity negatively affected with an increase in temperature. Analogously, the adsorption equilibrium constant decreased with increasing temperature. The kinetics of the adsorption process followed a second-order adsorption, with characteristic constants increasing with increasing temperature. Activation energy of biosorption could be calculated as equal to 10 kcal/mol. The biomass used proved to be suitable for removal of cadmium from dilute solutions. Its maximum uptake capacity was 120 mg/g. It can be considered an optimal result when compared to conventional adsorbing materials. Thus Sargassum sp. has great potential for removing cadmium ions especially when concentration of this metal is low in samples such as wastewater streams.

Captaçäo do cádmio e seu efeito no crescimento de chlorella homosphaera e Scenedesmus quadricauda em condiçöes laboratorias / Cadmium uptake and its effect on the growth of chlorella homosphaera and scenedesmus quadricauda cells in laboratory conditions

resumo:O efeito tóxico e a captaçäo de captaçäo de cádmio durante o crescimento de Chlorella homosphaera e Scenedesmus quadricauda foram estudados em diferentes concentraçöes de 4 mg/l e 2 mg/l, respectivamente.Para as duas espécies estudadas, este efeito foi diretamente proporcional à concentraçäo do metal e, inversamente proporcinal à concentraçäo celular