Potencial de hidróxidos duplos lamelares de Zn-Al e Mg-Fe para adsorção de 2-nitrofenol

Abstract

Two Zn-Al and Mg-Fe layered double hydroxides (LDH) were synthesized by coprecipitation method in order to increase the adsorption potential of 2-nitrophenol (2-NP). Both adsorbents were characterized by the techniques of XRD (X-Ray Diffraction), FTIR (Fourier Transform Infrared Spectroscopy), SEM (Scanning Electron Microscopy), AFM (Atomic Force Microscopy), EDS (Dispersive Energy Spectroscopy) and N2 adsorption/desorption isotherms (BET/BJH). The kinetics, isotherms and thermodynamics were evaluated. The Elovich model was the most adequate to describe experimental data of 2-NP kinetic adsorption onto Zn-Al-LDH, while the pseudo-second order model was the most adequate to describe experimental data of 2-NF kinetic adsorption onto Mg-Fe-LDH. For both LDH, the adsorption isotherm data were best described by the Freundlich model, where the maximum adsorption capacities were 290 and 165 mg g-1 for Zn-Al-LDH and Mg-Fe-LDH, respectively. The thermodynamic results revealed a spontaneous and endothermic process. Both adsorbents showed promising results and can be used to remove 2-NP from wastewater.