Dear Abdessamad Battas,

You should study its adsorption efficiency in batch (thermodynamics) and column (kinetics):

1-Batch Experiment (thermodynamics)

Batch adsorption experiments are carried out for solutions of nitrate in the concentrations range of 10-700 mg.L-1. Experiments are performed in 100 mL Erlenmeyer flasks containing 0.125 g clay complex.  25 mL of nitrate solutions having known initial concentration are then introduced to each flask. The flasks are shaken in an electric shaker for three hours at room temperature and then the content of each flask is centrifuged for 5 minutes and filtered through 0.45 µm cellulose filters.  The equilibrium concentration of nitrate is measured. 

Analysis of adsorption isotherms

Equilibrium relationships between adsorbent and adsorbate are described by adsorption isotherms. The most common models for adsorption processes are Langmuir and Freundlich adsorption isotherms. Langmuir isotherm is widely used for modeling equilibrium data and determination of the adsorption capacity. Its linear form is given by equation (1):

 Ce / Qe   =   1/ (K Qmax)    +    Ce / Qmax          (1)

Where:

Ce: equilibrium concentration of adsorbent (mg. L-1).

Qe: equilibrium mass of adsorbent per gram of adsorbate (mg. g-1).

K: Langmuir constant (L. mg-1).

Qmax: maximum mass of adsorbent removed per gram of adsorbate (mg. g-1).

 Freundlich isotherm describes equilibrium on heterogeneous surface and its linear form is given by equation (2):

                      Log qe = log kf + (1\n) log Ce          (2)

Where:

Ce: Equilibrium concentration of solute (mg. L-1)

qe: The amount of solute adsorbed per unit weight of adsorbent (mg. g-1).

k: The relative adsorption capacity of the adsorbent. (mg. g-1)

n: The intensity of the adsorption (L. mg-1).

2  Filtration experiments (column) (kinetics)

Column filter experiments are performed with 50/1 (w/w) mixtures of quartz sand and clay complex (13 cm layer) in a column of 18 cm length and 4 cm diameter. The mass of both clay complex and sand is 3 g and 147g, respectively. The bottom of the column is covered by 3 cm layer of wool. Quartz sand is thoroughly washed by distilled water and dried at 105 0C for 24 h. 50 mg. L-1 of nitrate are  prepared by dilution of the stock solution with distilled water and are passed individually through the columns. The flow rate is adjusted to 2.0 mL/min. at 25 Cº. Ten fractions of 100 mL each are collected and the concentration of the nitrate is measured.

In case you need more information on removal of pollutants by clay, you can visit my Research Gate profile; there are about 15-18 papers discussing similar treatment to what your are going to do.

Hoping this will be helpful,

Rafik.

Dear Rafik Karaman

Thank you M. Rafik for your answer, I will use your proposition

Dear Abdessamad Battas,

you can study this adsorption in determinig the adsorption isotherms . solutions incuding nitrate ions and amont dried at 120°c for 2 hours. for 200ml we need 0.200g of clay and 50 ml of nitrate solutions less than 600mg/L. T he best way is a static batch. in dynamic way we can loss material. the frendlich and langmuir isotherms are the most significative.

The détermination of nitrates contrations can be followed by colorometric or spectrophotometric methods.

Thank you M. Ramdane,

yes absolutely. But I found difficulty with concentration determination with the spectrophotometer methods  (UV-visible), whenever he gives a different concentration.

I want to know if I have to use another method or the problem is in the spectrophotometer?

Dear abdessamad,

To ensure the reliability of the spectrophotometer  we can calibrate it. we start firstly by finding the absorption band of the chosen color solution. Then we select  this band on the equipment to perform a trendline. That chemists call in general calibration curve or calibration. Generally it is a straight line. If this is not the case, a problem may be associated to the equipment.