Adsorption of Cd(II) on Zn-Al LDHs (Layered Double Hydroxides) Intercalated with Chelating Agents EDTA

Abstract

The hydrotalcite-like compound [Zn 2 Al(OH) 6 ]NO 3 ·mH 2 O (shorted as ZnAl-NO 3) was intercalated with the chelating agent EDTA (ethylene diamine tetraacetic acid) by anion exchange to uptake cadmium ion from aqueous solutions. The materials synthesized in this work were characterized by chemical analysis, FT-IR (fourier transform infrared spectroscopy), XRD (X-ray powder diffraction) to confirm their properties. In order to investigate the optimum conditions for Cd(II) adsorption, the amount of Cd(II) adsorbed by Zn-Al LDHs intercalated with EDTA (ZnAl-EDTA) under different conditions (i.e., adsorbent dosage, temperature and contact time) were determined by ICP-AES (inductively coupled plasma-atomic emission spectrometry). Adsorption isotherms of Cd(II) onto ZnAl-EDTA were measured at varying initial Cd concentrations (0.05 mg/L to 1 mg/L) under optimized conditions. The data were applied to Langmuir and Freundlich isotherms model, and well fitted by the Freundlich isotherms model. The pseudo-second-order kinetic model was more adequate to describe the kinetic in this case.