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Optimization of Copper(II) Adsorption onto Novel Magnetic Calcium Alginate/Maghemite Hydrogel Beads Using Response Surface Methodology

Magnetic calcium alginate hydrogel beads (m-CAHBs, 3.4 mm average diameter) composed of maghemite nanoparticles and calcium alginate were prepared and characterized by scanning electron microscopy (SEM) coupled with energy dispersive X-ray analysis (EDX). The response surface methodology was used to model and optimize the adsorption removal of Cu(II) from aqueous solution by m-CAHBs. Adsorption experiments were also carried out to examine the effect of three parameters, such as pH (2.0–6.0), adsorbent dosage (2.0–6.0 g L–1) and initial Cu(II) ion concentration (250–750 mg L–1). Maximum percent removal was attained under the optimum conditions with pH 2.0, 2.0 g L–1 adsorbent dosage for 250 mg L–1 initial Cu(II) ion concentration. The amount of Cu(II) adsorption after 6 h was recorded as high as 159.24 mg g–1 for 500 mg L–1 initial Cu(II) ion concentration. The adsorption kinetics indicated that the adsorption process was better described by the pseudo-second-order kinetic model. Desorption experiments ind...