The alginate extraction residue (RES) from the Brazilian Sargassum filipendula was successfully employed as biosorbent in this binary equilibrium study, revealing a greater affinity and selectivity for Cr(III) than for Zn(II). Experimental results also revealed that the process is of endothermic nature and well adjusted by Langmuir-Freundlich binary model. The X-ray photoelectron spectroscopy (XPS) analysis revealed that coordination with hydroxyl groups of RES prevailed in Cr removal, followed by carboxyl-metal complexation. As far as Zn(II) is concerned, ion exchange with carboxylate groups of RES was the largest contributor. Nevertheless, scanning electron microscopy coupled with Fourier transform infrared spectroscopy indicated the participation of sulfate functions in a minor degree.

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A partir de um estudo de equilíbrio em banho finito utilizando o resíduo da extração de alginato da alga Sargassum filipendula como bioadsorvente, isotermas de adsorção binária dos ions Cr(III) e Zn(II) foram obtidas em diferentes temperaturas e revelaram que o sistema possui caráter endotérmico, com maior afinidade do resíduo pelo Cr. Os modelos de equilíbrio de Langmuir não competitivo e Langmuir-Freundlich se ajustaram melhor os dados do Cr e do Zn (50ºC), respectivamente.