Environmental technology | 2021
Reuse of Adsorption Residuals for Enhancing Removal of Ciprofloxacin from Wastewater.
Abstract
AbstractCosts of water treatment can be reduced significantly if the spent adsorbents can be reused or regenerated.\u200f In this study, two residuals of iron adsorbed onto low-cost activated carbon (Fe-MCAC and Fe-MLAC) are reused as new adsorbents for the removal of ciprofloxacin (CIP) from pharmaceuticals wastewater. The residuals were characterized by SEM, XRD, FTIR, Raman spectra, N2-adsorption desorption. The adsorption mechanisms, performance, kinetics, isotherm, thermodynamic and reusability of residuals for CIP removal were evaluated. The isotherm data was well defined by Freundlich model for both adsorbents (residuals). Moreover, the CIP adsorption follows the pseudo-second-order kinetic model. The maximum adsorption capacity of CIP on Fe-MCAC and Fe-MLAC was 476.19 and 416.67\u2005mg/g, respectively. The maximum removal of CIP was obtained at pH 7 for both new adsorbents. The optimum contact time was found to be 30\u2005min and 60\u2005min for Fe-MCAC and FE-MLAC, respectively. The values of free energy change and enthalpy change for adsorption of CIP indicated the spontaneous, endothermic nature of the adsorption. In addition, the adsorption process was assisted by increasing randomness due to the value of entropy change. Therefore, the residuals of iron adsorption onto activated carbons could be reused as new low-cost adsorbents for antibiotics removal from wastewater.