Biosorption of cadmium with brown macroalgae.

Sorption experiments for cadmium removal using two brown macroalgae Lessonia nigrescens and Durvillaea antarctica were carried out. Although both types of algae were capable of retaining cadmium, differences in their performance were observed. The optimum pH was 3.7±0.2, and to achieve the equilibrium, 5 days of contact time were necessary for both biosorbents. The maximum experimental uptake obtained was similar for the two biosorbents: 95.3 mg Cd g(-1) by D. antarctica and 109.5 mg Cd g(-1) by L. nigrescens. The Langmuir model described the equilibrium sorption isotherms very well for both biosorbents and the Lagergren pseudo primer order model described the sorption kinetics for L. nigrescens satisfactorily and the Ho and Mckay pseudo second order model for D. antarctica. It was found that cadmium uptake by D. antarctica was faster than by L. nigrescens.