Clay minerals for adsorption of veterinary FQs: Behavior and modeling

• MAR and ENR adsorption on clay minerals was investigated in water.
• Models based on Langmuir interactions best fit experimental data for both FQs.
• Clay minerals were tested for removing FQs from contaminated ditch waters.
• The procedure is effective for remediation of FQs-polluted waters.

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 thermodynamic models 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.