Biosorption of metals in brown seaweed biomass

Biosorption of Cd by biomass of the brown seaweeds Durvillaea, Laminaria, Ecklonia and Homosira presaturated with Ca, Mg or K was coupled with the release of these light ions. The feasibility of biomass pre-treatment to develop a better biosorbent was evaluated by its biosorption performance, the degree of its component leaching (measured by the weight loss and TOC) as well as by the number of ion-exchange sites remaining in the biomass after the pre-treatment. Multicomponent Langmuir and ion exchange models applied to the equilibrium sorption data for pH 4.5 confirmed the ion exchange mechanism involved in the biosorption of metals. Both models fitted well the experimental data and their parameters can be used in the derivation of dimensionless ion-exchange isotherms which are instrumental in predicting the behavior of the biosorbents in dynamic flow-through biosorption systems. The sequence of biomass affinities established for the selected heavy metals can be correlated with the chemical pretreatment of the biomass.