Background and Aim:We studied the biosorption of lead(II) and cadmium(II) from aqueous solutions by the brown algae Sargassum sp. biomass in a batch system.

The heavy metal uptake was quite rapid, reaching 88-96% of the equilibrium capacity of biosorption in 15 minutes.

Material and Methods: Kinetic data were analyzed using the pseudo first-order, pseudo second-order, and saturation and second-order rate equations.

Results: The pseudo second-order and saturation rate equations gave the best fit with the experimental data(R² > 0.99). The data obtained from experiments of single-component biosorption isotherm were analyzed using the Freundlich, Langmuir, Freundlich-Langmuir and Redlich-Peterson isotherm models. The Redlich-Peterson equation was found to provide the best fit with the experimental data (R² > 0.99). Also the other models described the isotherm of lead(II) and cadmium(II) biosorption with relatively high correlation coefficients (R² > 0.93).

Conclusion: Using the Langmuir model, the maximum uptake capacities (q_m) of Sargassum sp. for Pb²⁺ and Cd²⁺ were 1.70 and 1.02mmolg^-1, respectively.