Adsorption Equilibrium and Thermodynamic Studies of Ciprofloxacin from Aqueous Solutions by Magnetic Bentonite Nanocomposites

Objectives: Today, due to increasing usage of antibiotics and their destructive effects on health and environment, it is necessary to remove them from receiving waters. Although there are few studies on the use of magnetic nanocomposites for removal of different antibiotics, but the effect of this adsorbent on the removal of Ciprofloxacin (CIP) has not been evaluated yet. Therefore, this study was conducted to investigate the removal of CIP by magnetic Bentonite nanocomposites (Fe3O4- BNP) as an adsorbent. Methods: Batch studies were performed to evaluate and optimize the effects of various parameters such as contact time, temperature of the solution, CIP concentrations and Fe3O4-BNP dosage. The adsorbent characteristics were determined using SEM and FT-IR spectroscopy. Also, the adsorbent surface area was measured by BET technique. Results: the optimal values for the factors affecting CIP removal were calculated. It was revealed that the maximum CIP removal was obtained at pH = 7, temperature = 55°C, CIP concentration = 10 mg/L, Fe3O4-BNP dosage = 1.25 g/L and contact time= 90 min. The maximum removal percentage was 99.25%. It was also revealed that Langmuir isotherm is the best fitted isotherm model. The thermodynamic parameters like ΔG0, ΔH0 and ΔS0 changes for the adsorption of CIP have also been computed and discussed. The heat of adsorption implied that the adsorption was exothermic in nature. Conclusion: The Fe3O4-BNP was successfully applied for the uptake of CIP from industrial wastewater and separated easily by means of magnetic separation.