Biosorption of Dyes by Brown Algae

This chapter describes the Reactive Black 5 (RB5) dye sorption from artificial solutions using biomasses of two brown algae- Macrocystis pyrifera and Undaria pinnatifida. Different assays were conducted in order to determine the kinetics of the biosorption process (the equilibrium state was reached after 400 min) and the best experimental conditions for the sorption. CaCl₂-treated biomass showed higher dye removal than HCl-treated or non-treated biomass. Percentage of dye removal increased from 20% to 99% for 0.1 g to 0.6 g of biosorbent, respectively. In addition, the removal increased at a lower pH, being the maximum at pH 1. The maximum adsorption capacity (26.31 mg g⁻¹) on M. pyrifera biomass was much higher than that on U. pinnatifida biomass (12.64 mg g⁻¹). Desorption was possible by increasing the pH, achieving the maximum recovery (100 %) at pH 12. In this way, M. pyrifera and U. pinnatifida biomasses could be repeatedly used as sorbents for RB5 dye.