Pii: S0043-1354(99)00120-7

ÐBiosorption 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 con®rmed the ion exchange mechanism involved in the biosorption of metals. Both models ®tted 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 ̄ow-through biosorption systems. The sequence of biomass anities established for the selected heavy metals can be correlated with the chemical pretreatment of the biomass. # 1999 Elsevier Science Ltd. All rights reserved Key wordsÐbiosorption, brown seaweed, heavy metal, ion exchange