**2.1 Synthetic adsorbent and characterization techniques**

The coprecipitation method was used to prepare Zn3-Al-Cl-LDH described by [19], with constant pH (pH = 7) and molar ratio (R = Zn2+/Al3+). Pure ZnCl2 (0.3 mol) and AlCl3.6H2O (0.1 mol) solution with a molar ratio of R = 3 is dissociated in distilled water (250 mL) to produce solution (a) and solution (b) containing NaOH (0.8 mol) and NaCl (0.05 mol) in 250 mL of distilled water. After solution (b) is added to solution (a) with vigorous stirring at pH = 7 with an N2 start to control contamination by carbonate ions. The precipitate was thoroughly washed with deionized water and dried at 60°C for 24 h to obtain the LDH of formula (Zn2.93Al (OH) 7.86) (Cl. 1.87 H2O noted Zn3Al-Cl-LDH according to [20].

In the X-ray powder diffraction (XRD), the samples were recorded on an X-ray diffractometer (SIEMENS D 501) with a radiation of λKα1 = 1.5405 Å and λKα2 = 1.5444 Å. The patterns were recorded from 2° to 76° 2θ angles at a step size of 0.02° and at a speed of 5°/min.

The Perkin-Elmer 16 PC Fourier transform spectrometer (FTS) was used for infrared measurements. The samples were prepared in a pellet of 13 mm diameter and 1 mm thickness using 2 mg of product diluted in 200 mg of KBr. The FT-IR spectra were recorded in absorbance in the wave number range of 400–4000 cm<sup>1</sup> at 25°C with a resolution of 1 cm<sup>1</sup> .

The frequency range from 20 Hz to 1 MHz was performed for impedance spectroscopy measurements, with eight points per decade at room temperature utilizing an impedance analyzer (Hewlett Packard 4192A). The electrical contacts were performed using silver electrodes, which were deposited on the two circular faces of the sample [19]. The magnitude of the applied signal is 0.6 V peak to peak. An amount of 200 mg is pelleted to analyze the impedance [19]. The granulated powder was compacted under a hydraulic press with 250 MPa pressure into discs of 13 mm diameter and 1 mm thickness approximately [19]. The impedance spectra

*Experimental and Theoretical Study of the Adsorption Behavior of Nitrate Ions by Layered… DOI: http://dx.doi.org/10.5772/intechopen.90883*

were recorded at different adsorption times (5, 10, 20, 30, and 60 min). The analysis and theoretical fitting by impedance spectroscopy using complex empirical functions were carried out utilizing the software ZView 2.2 and Origin 8 for modeling of the ionic conductivity and the imaginary function according to the real function, respectively.
