Utilization of MWCNTs/Al₂O₃ as adsorbent for ciprofloxacin removal: equilibrium, kinetics and thermodynamic studies

Abstract

In the present study, the adsorption behavior of ciprofloxacin (CIP) from aqueous solution onto MWCNTs/Al₂O₃ was studied using batch experiments. Physical characterization of MWCNTs/Al₂O₃ was determined by SEM, XRD, and BET. The effective parameters investigated included: initial CIP concentration, contact time, MWCNTs/Al₂O₃ mass, and temperature. Based on experimental results and correlation coefficients, the rate of CIP adsorption followed the pseudo-second-model kinetics. Complete compatibility of the adsorption isotherm process was achieved with the Langmuir model, and the maximum adsorption capacity reached 41.73 mg/g under the optimized conditions (pH = 7, MWCNTs/Al₂O₃ dose = 1.2 g/L, contact time = 60 min, initial concentration = 10 mg/L, and temperature= 45 °C). The adsorption capacities based on the Langmuir model at different temperatures, 273, 288, 303, and 318 K, were equal to 72.18, 75.92, 79.65, and 83.47 mg/g, respectively. The determined parameters of the thermodynamic studies demonstrated the endothermic and spontaneous nature of the biosorption. The mean free energy was estimated from D–R isotherm model to be 0.316–0.707 KJ/mol, which clearly proved that the adsorption experiment followed a physical process. The data suggest that MWCNTs/Al₂O₃ could be used as a highly effective adsorbent material with a high capacity for the removal of antibiotics from water and wastewater.

Keywords:

• Ciprofloxacin
• MWCNTs/Al₂O₃
• wastewater treatment
• thermodynamics
• kinetics
• isotherms

Acknowledgment

Open Access funding provided by the Qatar National Library.

Additional information

Funding

The authors would like to acknowledge an award from Zahedan University of Medical Sciences for the financial support of this study.