Elaboration de composites à base de bentonites et de polymères. Interactions avec les colorants

Abstract

The study of the adsorption of dyes by composites prepared with bentonite of Maghnia and three polymers: poly (N-vinylpyrrolidone), poly (vinylalcohol) and poly (acrylamide) was studied. Two types of dyes are used, anionic: blue, orange and red telon used in the textile industry and another cationic dye: methylene blue often used in the medical field. The prepared composites were characterized by IR, DRX, ATG, BET and zeta potential surface charge measurement. The results of the XRD clearly show an intercalation of three polymers between the sheets of two bentonite samples (Bt-Na) with an interlayer distance of 22.04 Å for the composite prepared from poly (vinylpyrrolidone): PVP significantly higher than the two other composites. The ATG confirms this result with a percentage of 23%. On the other hand, a low intercalation using the anhydrous bentonite (Bt) which the PVP being located on the surface of the bentonite. The study of the retention of the different dyes by the composites shows that the adsorption of these dyes is higher and faster for the composite PVP/Bt-Na compared to that of PVP/Bt reaching 99.99% for the methylene blue, 99.02% for telon blue, 62.5% and 49.61% for orange and telon red respectively. The kinetic adsorption results are better described by the expression of the pseudo second-order model. On the other hand, the adsorption isotherms of dyes by PVP/Bt-Na and PVP/Bt are satisfactorily described by the Freundlich model. The thermodynamic parameters obtained indicate that the adsorption of telon blue and methylene blue is spontaneous and exothermic process.