Adsorption of Cd2+ and Cu2+ on Ion-Exchange Beads from Cellulose/Alginic Acid Blend.

Our previous work has proved that mechanical properties of a blending alginate with cellulose was significantly enhanced in a wet state and maintained its biodegradability. In this article, ion-exchange beads were prepared from cellulose and alginate in 6 wt% NaOH/4 wt% urea aqueous solution by using an emulsion phase separation method. The structure and morphology of the beads were characterized by scanning electron microscope (SEM) and Fourier transform infrared (FTIR) spectra, and the adsorption behaviors to Cd2+ and Cu2+ ions were measured by atomic absorption spectrometry (AAS). The effects of pH, adsorption time, ion concentration, temperature, and reusability of the beads on the adsorbed amount of Cd2+ and Cu2+ ions in aqueous solution were investigated by a batch method. The results indicated that the beads had a spherical shape, with ∼4–20 µm of diameter and relatively high ion-exchange capacity (3.81 mmol g−1). The combined action of Cd2+ and Cu2+ ions on beads generally was found to be antagonistic. The selectivity of the beads for the adsorption of Cd2+ ions was higher than that of Cu2+ ions. The adsorbed amount was given to a maximum for Cd2+ ions at pH 2.2, and for Cu2+ ions at pH 3.2. The adsorbed amount of the beads reached the values of 0.7 and 0.5 mmol g−1 for Cd2+ and Cu2+ ions, respectively. The beads could be regenerated by using 1 mol L−1 HCl aqueous solution, up to 95% recovery, and the adsorption–desorption cycles, performed over 10 times, maintained the adsorption capacity, indicating a good reusability. [ABSTRACT FROM AUTHOR]