Adsorption of Direct Red 23 Azoic Dye from Aqueous Solution Onto Mg-Al-Fe-NO3 Layered Double Hydroxide

We report the preparation and characterization of a Mg-Al-Fe-LDH-NO3 layered double hydroxide (LDH) adsorbent for azoic dye, Direct Red 23 removal. The nanoparticles of adsorbent were prepared with Mg/(Al+Fe) molar ratio of 3:1 by a hydrothermal process at pH 9.5. The XRD patterns indicate that the intercalation of dye between the LDH layers has not occurred and surface adsorption has happened. In the adsorption experiments, the Gibbs free energy G values, the enthalpy H, and entropy S were determined. The isotherms showed that the adsorption of dye by Mg-Al-Fe-LDH-NO3 was both consistent with Langmuir and Freundlich equations.