Adsorption of metanil yellow azoic dye from aqueous solution onto Mg-Fe-NO3 layered double hydroxide

Abstract

We report the preparation and characterization of a layered double hydroxide (LDH) adsorbent for azoic dye, metanil yellow (yellow GX; YGX) removal. The nanoparticles of Mg-Fe-LDH-NO3 adsorbent were prepared with Mg/Fe molar ratio of 3:1 by a hydrothermal process and coprecipitation method at pH 9.5 and were characterized by X-ray powder diffraction (XRPD), thermal gravimetric analysis (TGA), elemental analysis, and Fourier transform infrared spectroscopy (FT-IR). The size and morphology of nanoparticles were examined by scanning electron microscopy (SEM). The XRD patterns indicate that the intercalation of YGX between the LDH layers has not occurred and surface adsorption has happened. In the adsorption experiments, the Gibbs free energy ΔG0 values, the enthalpy ΔH0, and entropy ΔS0 was determined. The isotherms showed that the adsorption of YGX by Mg-Fe-LDH-NO3 was both consistent with Langmuir and Freundlich equations. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.