Adsorption of Ciprofloxacin on Clay Minerals in Argentinian Santa Rosa-Corrientes Soils

Abstract

The presence of antibiotics in soils is increasing drastically in last decades due to theintensive farming industry and excessive human consumption. Clay minerals are one of the soilcomponents with great adsorption capacity for organic pollutants. The study of interactions betweenantibiotics and mineral surfaces will give us scientific knowledge of these pollutants through soils.In this work, we study the adsorption of the antibiotic ciprofloxacin in the clay mineral fraction ofsoils from the Argentinian zone of Santa Rosa (Corrientes), in a collaborative research of experimentsand atomistic modelling calculations of the intercalation of ciprofloxacin in the interlayer space ofmontmorillonite. Adsorption and desorption isotherms were performed and compared with differentisotherm models. Additionally, enthalpy, entropy, and free energy were determined from equilibriumconstants at a function of temperature. All these experiments and calculations lead to the conclusionsthat two adsorption types of ciprofloxacin are found on clay minerals: one weakly sorbed that isreleased during the desorption experiments, and other one strongly joined that remains in the soil.