A Comparative Adsorption Study with Various Adsorbents for the Removal of Ciprofloxacin Hydrochloride from Water

Abstract

In this study, the removal of ciprofloxacin hydrochloride (a fluoroquinolone antibiotic) by using various effective adsorbents such as activated carbon, montmorillonite, modified montmorillonite (commercial name Cloisite 20A), and alumina was investigated. Adsorption experiments were performed to determine and compare the adsorption capacities of these adsorbents. The adsorption capacities of adsorbents were examined at different initial concentrations of ciprofloxacin hydrochloride. Activated carbon was found to be having the best adsorption capacity for the removal of ciprofloxacin hydrochloride. For the solution having an initial ciprofloxacin hydrochloride concentration of 4 ppm, the adsorption capacities of adsorbents were obtained as 1.86 mg g−1 for activated carbon, 1.67 mg g−1 for modified montmorillonite, 1.15 mg g−1 for alumina, and 0.60 mg g−1 for montmorillonite. And also, about 92% of the ciprofloxacin hydrochloride was removed from the water using the activated carbon. In addition, Langmuir, Freundlich, and Temkin isotherm models were employed to express the adsorption process. For all adsorbents, Freundlich isotherm model provided best fitting to the experimental data because of very high values of R2 (> 0.99). Kinetic models of pseudo-first order, pseudo-second order, Elovich, and Weber-Morris intraparticle diffusion model were utilized to evaluate the experimental adsorption data. Adsorption kinetics data were well represented by pseudo-second order kinetic model with values of R2 (> 0.999).