**3.4 Study of the adsorption in batch and determination of nitrate ions**

#### *3.4.1 Calibration curve*

A series of vials of 50 ml each containing 1 mL of 0.5% sodium salicylate is introduced: 8, 6, 4, and 2 ml of KNO3 solution (50 mg L<sup>1</sup> ) with, respectively, 2, 4, 6, and 8 ml of water. The contents of each flask are then evaporated to dryness in an oven (75–80°C) to produce a residue which is dissolved with 2 ml of concentrated H2SO4. After 10 min of rest has passed, 15 ml of distilled water and then 15 ml of a basic solution made up of 40% NaOH, 6% sodium potassium tartrate, and then 50 ml with distilled water are then allowed to develop the yellow color characteristic of the complex nitrate formed. The nitrate ion concentrations in the liquid phase were determined by a spectrophotometric method (spectrophotometer type JASCOV-630 λ = 415 nm).

The calibration curve obtained (**Figure 3**) is in good agreement with the Beer-Lambert law.

#### *3.4.2 Assays of nitrate ions in balance*

The Zn3Al-Cl-LDH is contacted with a potassium nitrate solution (0.4 g/L) for 5 min, 10 min, 20 min, 30 min, and 60 min. Before washing Zn3Al-Cl-LDH after

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

**Figure 3.** *Curve calibration of spectrophotometer used for determination of NO3* � *adsorbed.*

adsorption and which is intended for the dielectric analysis. The filtrate is recovered corresponding to each time and fee in 1 mL is put in a 50 mL flask and then the following procedure used for the tracing of the calibration curve.
