Zinc and cadmium biosorption by untreated and calcium-treated Macrocystis pyrifera in a batch system

► We study the simultaneous adsorption of zinc and cadmium on the brown alga Macrocystis pyrifera. ► The treatment with calcium improved the biosorbent uptake capacity. ► Several models were applied to obtain the rate limiting mechanisms and thermodynamic parameters. ► In bicomponent solutions, about 75% of the biosorption occurs without competition. ► The recovery the metals was possible using HNO3 with no damage for the biosorbent.