Clay minerals for adsorption of veterinary FQs: Behavior and modelling.

The adsorption of two veterinary fluoroquinolones, Enrofloxacin (ENR) and, for the first time, Marbofloxacin (MAR), was investigated on kaolinite and montmorillonite clays with the aim of evaluating the efficiency of these adsorbents in removing pharmaceuticals from soils and waters. Experiments were carried out at two different pHs in tap water and aqueous salt solution. Adsorption isotherms show that these drugs were adsorbed in remarkable amounts by the three materials examined (STx-1, SWy-1, kaolinite) with different mechanisms, as confirmed by XRD (X-ray diffraction) analysis. Different thermodynamicmodels have been applied and the best fit was obtained by means of Langmuir interactions models. In order to remove FQs from contaminated wastewaters, the three clays were contacted with water samples collected from ditches near cattle and swine farms obtaining a quantitative removal. The results proved that such minerals are suitable for the remediation of environmental matrices