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|Titolo:||Adsorption of sulfonamide antibiotics onto high silica zeolites: from multidisciplinary model studies to applications to real waters|
|Autori interni:||MARTUCCI, Annalisa|
|Data di pubblicazione:||2014|
|Abstract:||Owing to their environmental diffusion and persistence, sulfonamide antibiotics (sulfa drugs) are responsible to induce high level of resistance in bacteria. The sulfonamide anionic nature makes them highly mobile along soil profile and is responsible for their accumulation into water bodies. In order to limit the diffusion of resistance determinants, it is of utmost importance to identify adsorbents for this antibiotic family to be adopted for water cleanup purpose. Three high silica zeolites (Y, MOR, ZSM-5) have been tested for their capability to extract sulfonamides from water. Kinetics, capacity and reversibility of the adsorption have been studied along with sulfonamide arrangement into the porosities of each zeolite [1-3]. The sulfa drugs irreversibly adsorbed onto zeolite Y at ca. 26% on average and with the process equilibrium reached in less than 1 min [1,3]. The favorable adsorption kinetics was confirmed when zeolite Y was applied to both fresh and sea waters although the dissolved organic matter occurring in natural water compartments can be retained as well but with a kinetics less favorable than that shown by sulfa drugs. The main host-guest & guest-guest interactions between zeolites and sulfa drugs were defined by IR and SS-NMR analysis, and augmented by computational studies. H-bonds and van der Waals type interactions between single molecules and zeolite Y or ZSM-5 were responsible for the irreversible extraction of sulfa drugs from water [1,3]. The occurrence of intramolecular medium strength H-bond in small sized sulfa drugs upon adsorption inside zeolite Y cage revealed the formation of dimeric species whose amidic or imidic tautomeric form were identified [1,3]. Rietveld refinement and IR analysis revealed that sulfa drugs incorporation into MOR caused a close vicinity of the heterocycle ring to the side pocket oxygens [2,3]. At 65°C, MOR gave rise to a sulfachloropyridazine reaction product with a 100% selectivity and SN-Ar mechanism . Among the regeneration strategies approached, the thermal treatment and solvent extraction gave the best results.  I. Braschi, G. Paul, G. Gatti, M. Cossi, L. Marchese. RSC Advances, 3 , 7427 (2013).  A. Martucci, M.A. Cremonini, S. Blasioli, L. Gigli, G. Gatti, L. Marchese, I. Braschi. Micropor. Mesopor. Mat. 170 , 274 (2013).  S. Blasioli, A. Martucci, G. Paul, L. Gigli, M. Cossi, C.T Johnston, L. Marchese. J. Coll. Interface. Sci., 419 , 148 (2014).|
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