N.Boudaoud& al. / Mor. J. Chem. 2 N°5 (2014) 517-520 EDE4
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Study of interactions organic polluant/clay Anionic for environmental protection
N. Boudaoud(a) *, H. Miloudi(a), A. Tayeb(a) , M. D. Ureña-Amate(b), A. Bengueddach(a)
(a) département de chimie laboratoire de chimiedes matériaux université d’Oran Algérie
(b) Departamento de Quimica y Fisica de la Universidad de Almeria Espagne.
*Corresponding author. E-mail : boudaoud_2007@yahoo.fr
Received 13 Sept 2014, Revised 01 Oct 2014, Accepted 24 Oct 2014
Abstract
Because of the increaseduse of pesticides in order to satisfy the economic needsin the agriculture production which is more and intensive. Many studies are done on the consequence of these pesticides on the soil and their pollution treatment [1]. The interest of the double lamellar hydroxides (HDL) in this field consist first of all in their exchange properties which offer the caught of the pollutants; on the other hand,in their use as a model of soil to the comprehension the pollution phenomenon . The present work deals with how to catch. The pesticide Methomylwithin the phase Mg1_xAl8(OH2)[XnH2o]. The isothermmodelisation absorption by Freundlich equation, completed RX and IR analyses permit to precise the interaction mechanism[4]. The isotherm shape varies depending on the intercalary nature. To move from type S to the type L (Giles and al classification) with in the some isotherm is attributed to the interaction first, of the surface then with the whole solid. The type S suggests the interactions between the Methomyl molecules are more important.
Keywords : Adsorption, Methomyl, Layered Double Hydroxides, Hydrotalcites, Pesticides, Environment.
1. Introduction
The HDL are the mixed lamellar hydroxide of di and trivalent metals. The structure is described by the leaves piling (M(OH)2) which are the same as those of brucite. The trivalent metal presence leads to positive charged leaves the electro neutrality is ensured by the anion spices solvated by water[1,2]present with in the leaves area [4] such as phases exist as minerals: hydrotalicites [Mg-Al],hydrocalumite[Ca-Al]the green rust [Fe+2- Fe+3]. Otherwise, these minerals are rare in nature where the clay materials are essentially cationic clay (plylosilicates).in seventies; the Miyata[9] works about the soft chemistry synthesis of HDL permitted their development. There are somany combinations(metals and leaves) that is possible to vary the chemical and physical HDL properties which increase the catalysis interest [6]. In another hand, the strongest ionic exchange capacities (3 to 4meq\g) very reative hydroxide area favorises the chemisorptions. The HDL give also the possibility to catch the chemical pollutants[3,4]. It has already proved that the treatment of polluted water by nitrates, phosphate or chromates is efficient. The HDL are also as support or catalyser to decrease chemical pollutants [6].
N.Boudaoud& al. / Mor. J. Chem. 2 N°5 (2014) 517-520 EDE4
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2. Experimental
2.1. Synthesis
All HDL have been prepared by co precipitated method at constant pH (S. Miyata, 1975) [5,7,9].It consist to realize a controlled precipitation by alcalin solution which contain thesalt of the two cations.So,the phase [ Mg2AlCO3]has been synthesized at an ambient temperature by a progressive addition of Mg(NO3)6H2O 0,5 M and Al(NO3)3,6H2O 0,25M solution and Na2CO32M and NaOH 1M solution in reactor contained 100 ml deionised and carbonate less water under magnetic shaking. The pH is maintained constant to the value 10 ± 0.1by the addition of NaOH 2M.After 24 H at 85°C has been washed and centrifuged 3 times then let to dry at 65°C.
2.2.Isotherm adsorption
The methomyl isotherm adsorptionhave been enregisted at 25°C in a closed reactor under magnetic shaking.
10mg of clay are dispersed in 25 ml of Methomyl solution of a variable concentration (Ci=2 to 6 mmol/L).After 24 h the solid has been separated from the solution by centrifugation the Methomyl
20 40 60 80
MgAl-500
Mg-Almethomyl
Mg-AlCO3
2theta
4000 3500 3000 2500 2000 1500 1000 500
0,0 0,2 0,4 0,6 0,8 1,0 1,2
* *
* *
*
% transmitance
Wavelength(cm-1
Mg2AlCO3 Mg2Almethomyl methomyl
Figure 1. Schematic representation of HDL Figure 2. XRD patterns of [MgAl-CO3], [MgAl- methomyl], [MgAl-500]
Figure 3. show the FT-IR includesthe infrared spectra ofHDLphases[Mg2AlCO3], [Zn2Al CO3],[Mg2Al500]andpatterns of the most representative.
N.Boudaoud& al. / Mor. J. Chem. 3 N°X (2015) 517-510 EDE4
519 concentration is determined by UV visible spectrometer [Methomyl:λ= 254 nm).The isotherms concerned by the quantity of Methomyl CS adsorbed by clay are represented in figure 4.
2.3.pH influence
The PH influence on the Methomyladsorptionby [Mg2AlCO3] has been examined. At pH<5the clay is partly dissolved. If the pH<7 struggle with the carbonate anions is very probable[8,10S].The figure 5 show that the maximum absorption at 5<PH<7 which correspond to natural water.
3. Conclusion
The HDL offer to catch the organic pollutants. The Methomyl isotherm adsorptions are between type S and L. This shows the moderate interactions between organic pollutants and clay.The absorptionby exchange concerns first the surface then the whole solid. It depends on many factors: pH, charge density of leaver the clay morphology and solid / liquid.
Acknowledgments
The authors thank O. Tayeb for her help in the translation in English.
1,00 1,05 1,10 1,15 1,20 1,25
0 2 4 6 8 10
d
b a c
qe(mmole/g)
ce(mmole/l)
2 3 4 5 6 7 8 9 10 11
9,30 9,32 9,34 9,36 9,38 9,40 9,42
adsorbed pestecide(mmole/L)
pH
Figure 5.Influence of the pH on Methomyl adsorption on [Mg2AlCO3]
Figure 4. Methomyl adsorption isotherms for (a) [Mg2AlCO3], (b)[Zn2AlCO3],(c)[Mg2Al500], (d)[Mg2Aledta] at 25°C [Mg2AlCO3]
N.Boudaoud& al. / Mor. J. Chem. 3 N°X (2015) 517-510 EDE4
520 References
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