Dried raw and protonated biomasses of the brown seaweed Fucus vesiculosus and the red seaweed Gracilaria tikvahiae were used to study their biosorption performance for copper, zinc, nickel, and cobalt. Representative samples of both species were collected from Chincoteague Bay, Virginia. A series of “sorbate” or metal concentrations (10-450 mg L-1) were selected for each metal to compare the seaweeds' biosorption performance at pH 4.5 ± 0.1 and 25±1 °C. Samples were analyzed on Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-AES). Langmuir and Freundlich adsorption isotherm models for single solute systems were used to assess sorption performance. Both raw and protonated Fucus vesiculosus exhibited higher affinity for metal ions than Gracilaria tikvahiae, at both high and low ends of the concentration ranges. The protonated red seaweed species had maximum metal uptake values of 0.99 mequiv g-1 (copper), 0.39 mequiv g-1 (zinc), 0.66 mequiv g-1 (nickel) and 0.79 mequiv g-1 (cobalt). In comparison, protonated Fucus vesiculosus sorbed higher amounts (1.63, 1.10, 1.40, and 1.69 mequiv g-1 of the metals in the same order). The prospects of using the brown seaweed species in the treatment of industrial wastewaters in place of expensive, conventional ion-exchange resins are envisaged.

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