Kinetics, equilibrium and thermodynamics of ciprofloxacin hydrochloride removal by adsorption on coal fly ash and activated alumina

In this study, performance of two different adsorbents namely, activated alumina (AA) and coal fly ash (CFA) have been examined for the removal of an antibiotic Ciprofloxacin hydrochloride (CPH) from its aqueous solution. Batch adsorption experiments were conducted to study the effect of various operational parameters such as pH, initial antibiotic concentration, adsorbent dose, and temperature on the adsorption process. The optimal pH for CPH adsorption was found to be 4. The adsorption kinetics was evaluated at different initial antibiotic concentrations and temperatures. Kinetics of adsorption, in all cases, followed pseudo-second-order rate equation for both the adsorbents. Adsorption of CPH was well described by Freundlich isotherm. Thermodynamic analysis unveiled the feasibility, spontaneity, and endothermic nature of overall adsorption process at higher temperatures. Values of G degrees for CFA and AA are -0.029 and -2.714kJ/mol, respectively, at 328K. The corresponding values for H degrees are 6.572 and 28.408kJ/mol and that of S degrees are 0.020 and 0.093kJ/molK, respectively. The study is significant in designing the water treatment plants for the removal of CPH. Overall, it was concluded that AA is a better adsorbent than CFA for the removal of CPH from its aqueous solution.