Removal of cadmium (Ⅱ) from aqueous solution by granular activated carbon supported magnesium hydroxide

• Granular activated carbon supported magnesium hydroxide was prepared.
• Effect of magnesium content on Cd removal efficiency was discussed.
• GAC and Mg-GAC characteristics were analyzed.
• Adsorption data agreed well with a pseudo-second-order kinetic model.

Granular activated carbon supported magnesium hydroxide (Mg-GAC) was successfully prepared by an environmentally friendly preparation process. Effects of magnesium ion concentration on magnesium content and the removal efficiency of Mg-GAC for cadmium (II) were discussed. The raw GAC and Mg-GAC were detected by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) for comparison. The results showed that magnesium hydroxide was well distributed within the pores of GAC. From the batch experiment results, the cadmium (II) could be removed by the Mg-GAC effectively. These studies showed that cadmium (II) adsorption on GAC and Mg-GAC (magnesium content was 1.87%) was 3.47 mg/g and 8.08 mg/g, respectively with 27 mg/L initial concentration, at pH 6 and temperature 25°C, which indicated that Mg-GAC had a better adsorption capacity than untreated granular activated carbon. Besides, the adsorption data agreed well with a pseudo-second-order kinetic model.

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