Thermodynamical and structural insights of orange II adsorption by Mg{sub R}AlNO{sub 3} layered double hydroxides

Journal Article · Sun May 15 00:00:00 EDT 2011 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2011.03.018· OSTI ID:21494295

Mustapha Bouhent, Mohamed ^[1]; Derriche, Zoubir ^[1]; Denoyel, Renaud ^[2]; Prevot, Vanessa; Forano, Claude ^[3]

---

1. Laboratoire de Physico-Chimie des Materiaux, Catalyse et Environnement, UST d'Oran, Bp 1505 Oran El M'naouer (Algeria)
2. MADIREL, Laboratoire Chimie Provence, Universite d'Aix-Marseille I, II et III, UMR CNRS 6264, Campus de Saint Jerome, Avenue Escadrille-Normandie-Niemen, F-13397 Marseille Cedex 20 (France)
3. Laboratoire des Materiaux Inorganiques, UMR CNRS 6002, Universite Blaise Pascal, F-63177 Aubiere Cedex (France)

[Mg{sub 1-x} Al{sub x}(OH){sub 2}][(NO{sub 3}){sub x}, nH{sub 2}O] Layered Double Hydroxide (LDH) sorbents with variable Mg/Al molar (R=(1-x)/x) ratios were investigated for adsorption of azo dye, orange II (OII) at various pH and temperature conditions. Mg{sub 2}AlNO{sub 3} displays the highest adsorption capacity with 3.611 mmol of OII per gram of Mg{sub 2}AlNO{sub 3} at 40 {sup o}C. Adsorption isotherms have been fitted using the Langmuir model and free energy of adsorption ({Delta}G{sup o}), enthalpy ({Delta}H{sup o}) and entropy ({Delta}S{sup o}) were calculated. The experimental values for {Delta}G{sup o} in temperature range between 10 and 40 {sup o}C were found to be negative indicating that a spontaneous process occurred. Positive calculated enthalpy values, characteristic of an endothermic process were found. Characterization of solids (PXRD, FTIR, UV-vis, TGA/DTA, adsorption isotherm BET analysis, SEM and Zetametry) before and after adsorption showed that adsorption proceeds in two steps. First, adsorption occurs at the LDH surface, followed by intercalation via anion exchange. -- Graphical Abstract: Structural and thermodynamical insight of adsorption/Intercalation of OII in Mg{sub R}Al LDH Display Omitted Highlights: {yields} The nitrate containing hydrotalcite-like compounds (Mg{sub R}AlNO{sub 3} LDH) were prepared by the coprecipitation method. {yields} Adsorption of anionic orange dye(OII) is studied on LDHs at different temperatures. {yields} The adsorption process is well described by the Langmuir isotherm model. {yields} Mg{sub 2}AlNO{sub 3} displays the highest adsorption capacity with 3.611 mmol of OII per gram of Mg{sub 2}AlNO{sub 3} at 40 {sup o}C. {yields} Adsorption process does not occur on the surface of the LDH only but an intercalation process is also occurring concomitantly according to the thermodynamical values.

• OSTI ID: 21494295
• Journal Information: Journal of Solid State Chemistry, Vol. 184, Issue 5; Other Information: DOI: 10.1016/j.jssc.2011.03.018; PII: S0022-4596(11)00115-0; Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ADSORPTION
ADSORPTION ISOTHERMS
ALUMINIUM HYDROXIDES
AZO DYES
COPRECIPITATION
DIFFERENTIAL THERMAL ANALYSIS
ENTHALPY
ENTROPY
FREE ENERGY
INFRARED SPECTRA
ION EXCHANGE
MAGNESIUM HYDROXIDES
NITRATES
SCANNING ELECTRON MICROSCOPY
TEMPERATURE RANGE 0273-0400 K
THERMAL GRAVIMETRIC ANALYSIS
X-RAY DIFFRACTION
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
AZO COMPOUNDS
CHEMICAL ANALYSIS
COHERENT SCATTERING
DIFFRACTION
DYES
ELECTRON MICROSCOPY
ENERGY
GRAVIMETRIC ANALYSIS
HYDROGEN COMPOUNDS
HYDROXIDES
ISOTHERMS
MAGNESIUM COMPOUNDS
MICROSCOPY
NITROGEN COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PRECIPITATION
QUANTITATIVE CHEMICAL ANALYSIS
SCATTERING
SEPARATION PROCESSES
SORPTION
SPECTRA
TEMPERATURE RANGE
THERMAL ANALYSIS
THERMODYNAMIC PROPERTIES