Clean-up of water polluted with veterinary sulfonamide antibiotics by high silica zeolite y: from model studies to real applications and regeneration techniques

The anionic nature of veterinary sulfonamide antibiotics (sulfa drugs) makes them highly mobile along soil profile and is responsible for their accumulation into water bodies. Owing to their environmental diffusion and persistence, sulfonamides are responsible to induce high level of resistance in bacteria through by-pass mechanism. To limit the diffusion of resistance determinants, it is of utmost importance to identify sustainable strategies against this antibiotic class to be adopted for water cleanup purpose. Recently, a high silica zeolite Y (SiO2/Al2O3 = 200) revealed an excellent ability to extract sulfonamides from pure water in terms of kinetics, capacity and irreversibility of the adsorption. In this study, the favorable adsorption kinetics and properties of the zeolite was confirmed in the presence of both acidic and neutral models of humic monomers (namely, caffeic acid and vanillin) in the 5-8 pH range. Sulfa drugs were quickly removed also when the sorbent was applied to fresh and sea waters. A displacement of adsorbed sulfa drugs from zeolite pores was observed for longer contact time and the mechanism was identified. Finally, among several regeneration techniques applied to exhausted zeolite samples, thermal treatment and solvent extraction showed the best performance.