Effective removal of ciprofloxacin from aqueous solutions using magnetic metal-organic framework sorbents: mechanisms, isotherms and kinetics

Metal-organic framework sorbents [MIL-100(Fe), MOF-235(Fe)], Fe3O4 nanoparticles and metal-organic framework loaded on iron oxide nanoparticles [Fe3O4@MIL-100(Fe) and Fe3O4@MOF-235(Fe)] were prepared and examined for ciprofloxacin (CIP) removal. The results showed that sorption kinetics of CIP by Fe3O4@MIL-100(Fe) follows the Elovich and pseudo-second-order models indicating that the sorption is both chemisorption and physical adsorption, whereas the sorption to other sorbents occurs mainly by physical sorption. The sorption isotherm studies revealed that Langmuir model provided the best fit to all the experimental data. The thermodynamic studies showed that CIP removal is spontaneous (Delta GA degrees = 2.28 kJ/mol) and endothermic (Delta HA degrees = 18.39 kJ/mol). It was also found that among the sorbents investigated for CIP removal, Fe3O4@MIL-100(Fe) has the highest maximum monolayer adsorption capacity of 322.58 mg/g.