Adsorption of Chloride Anion from Aqueous Solution by Calcined (Mg-Al) Hydrotalcites of Different Mg/Al Ratio
Hydrotalcites (HT-X) of different Mg/Al ratio (X is Mg/Al molar ratio, 3 and 4) was synthesized by co-precipitation method. Calcined HTLCs (CHT-X) at 500°C have been shown to recover their original layered structure by taking up chloride ion from aqueous solution. Adsorption of chloride by CHT-X was investigated in batch mode. The kinetics study showed that the pseudo-second-order kinetics model could be used to describe the adsorption process satisfactorily. The equilibrium isotherm showed that the Langmuir model gave a better fit to the experimental data than the Freundlich model. The maximum adsorption capacity of CHT-3 was 83.33 mg/g; CHT-4 was 90.09 mg/g .The samples of different Mg/Al ratio have different crystallite size, thus showing different adsorption capacity. As the Mg/Al ratio increases from 3 to 4; the electric charge density between the layers becomes weaker; the interlayer spacing increases; the sample shows greater adsorption capacity. The HT-X where characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron dispersive X-ray analysis (EDX).
Zhong Cao, Lixian Sun, Xueqiang Cao, Yinghe He
D. J. Wan et al., "Adsorption of Chloride Anion from Aqueous Solution by Calcined (Mg-Al) Hydrotalcites of Different Mg/Al Ratio", Advanced Materials Research, Vols. 233-235, pp. 420-426, 2011