Adsorption of enrofloxacin onto natural zeolite: Kinetics, thermodynamics, isotherms and error analysis

Abstract

Classical wastewater treatment processes are not efficient for removal of so-called emerging contaminants. Croatian natural zeolite - clinoptilolite has been used as alternative material for efficient removal of enrofloxacin (ENRO) from aqueous solution. The influences of the initial ENRO concentration, contact time and temperature on adsorption performance are experimentally verified by a batch method. The kinetic data are analyzed using pseudo-first-order and pseudo-second-order kinetic models. The equilibrium data are fitted to two parameters adsorption isotherm models: Freundlich, Langmuir and Dubinin-Radushkevich. Linear and non-linear methods are used for comparing the best fitting of the isotherms. By comparing values of correlation coefficient and the error functions, it is found that Langmuire and Freundlich models best fit the enrofloxacin adsorption onto clinoptilolite. Values of thermodynamic parameters were calculated using adsorption equilibrium constant obtained from the Langmuir isotherm. The results suggest that the ENRO adsorption on natural zeolite a non-spontaneous and endothermic process. This study shows that natural zeolite can be an important low-cost adsorbent for ENRO removal.