Adsorción de ciprofloxacina y diclofenaco sobre arcillas naturales e hidrolizadas usando vasos agitados

Abstract

Emerging contaminants such as ciprofloxacin and diclofenac are not adequately removed in wastewater treatment plants, affecting the environment. These drugs are of particular interest as they appear on the EU watch list. Several processes, such as adsorption on carbonaceous materials and agricultural waste, have been successfully tested. Against this background, the objective of this work was to find environmental, economical, and effective solutions for the removal of contaminants such as ciprofloxacin and diclofenac on clays in stirred vessel adsorption processes. The clays were characterized by determining the zero-charge point, functional groups, specific surface area, and adsorption capacity. In addition, acid hydrolysis was performed to increase their specific surface area and adsorption capacity, especially in the removal of DCF, which increased by 40 to 60%. All clays adsorbed ciprofloxacin up to 270 mg/g. Acid treatment did not significantly increase the adsorption capacity of this drug. Instead, hydrolyzed clays achieved the adsorption of diclofenac, which natural clays were unable to adsorb, indicating that ciprofloxacin has a greater affinity with clays than diclofenac. Finally, it was shown that the adsorption kinetics for all clays in the removal of CPX and DCF fit the pseudo-second-order model, indicating rapid adsorption. The equilibrium model that best fit for CPX was Freundlich, which suggests multi-layer adsorption, and for DCF was Langmuir, indicating monolayer adsorption.