Ciprofloxacin adsorption performance of Co-doped UiO-66

Abstract

The presence of ciprofloxacin in various water sources, even at low concentrations, causes health risks and serious environmental pollution as well as development of antibiotic resistance. So, it is critically necessary to remove ciprofloxacin effectively from the effluent. Co-doped UiO-66 was synthesized through one-step hydrothermal method and evaluated as an adsorbent for ciprofloxacin adsorption. Ciprofloxacin adsorption was systematically investigated revealing adsorption isotherms, kinetics, and thermodynamics. The findings revealed that Freundlich isotherm model (maximum adsorption capacity: 45.17 mg g-1) at optimum experimental conditions (pH: 5, contact time: 90 min and adsorbent dosage: 0.3 g L-1) and acquired data were fitted using pseudo-second-order kinetic model. The ciprofloxacin adsorption was determined to be a spontaneous and endothermic from thermodynamic experiments. Effects of coexisting compound in the aqueous solutions on the Co-doped UiO-66 adsorption performance were studied using different concentrations of NaCl solution. The ciprofloxacin removal slightly decreased in the case of increasing the concentrations of Na+ ions. Regeneration of the Co-doped UiO-66 was carried out in methanol + acetic acid solution and repeated adsorption experiments were conducted to reveal reusability of the Co-doped UiO-66. Its ciprofloxacin adsorption capacity reduced to 38.0 mg g-1 after the four cycles indicating that the Co-doped UiO-66 was a reusable and potential adsorbent for ciprofloxacin adsorption process. Co-doped UiO-66 was evaluated as an adsorbent for ciprofloxacin removal from aqueous solutions. High ciprofloxacin adsorption capacity was achieved through the various adsorption mechanisms. Repeated adsorption-desorption cycles showed the Co-doped UiO-66 sample was a promising reusable adsorbent for ciprofloxacin adsorption processes.image