Adsorption study of levofloxacin on reusable magnetic nanoparticles: Kinetics and antibacterial activity

Abstract

Adsorption of levofloxacin (LEV) onto the surface of superparamagnetic iron oxide nanoparticles (SPION, Fe3O4) and Fe3O4@SiO2 nanocomposites was investigated in terms of pH, adsorbate dose, contact time, and temperature. The adsorbent nanomaterials, i.e., Fe3O4 and Fe3O4@SiO2 were synthesized via coprecipitation and modified Stober method, respectively. The particle size, surface morphology, and elemental composition of the synthesized materials were characterized by TEM, FESEM, and EDS, respectively. Batch experiments were carried out to study the sorption kinetics and isotherms of LEV onto the surface of synthesized adsorbent materials. The pseudo-second-order kinetics described the adsorption kinetic data fitting better than the pseudo-first-order kinetics. Moreover, the Langmuir adsorption isotherm data obeyed efficiently than that of Freundlich isotherm. The maximum adsorption capacity of LEV on Fe3O4 nanoparticles ranged from 6.094 to 6.848 mg g−1. The appropriate contact time was 240 min for both Fe3O4 and Fe3O4@SiO2 nanomaterials. The best elimination of LEV was obtained at pH ~ 6.5 with the maximum removal efficiency of 80.2%. The calculated value of activation energy suggests a chemisorption process, while the values of enthalpy and Gibbs free energy indicated exothermic adsorption and spontaneous process at low temperature, respectively. The synthesized Fe3O4@LEV nanoparticles were also studied as antibacterial agents against different types of gram-positive bacteria; M. luteus, B. subtilis, and S. aureus and gram-negative bacteria; K. pneumonia, P. aeruginosa, and E. coli by agar-well diffusion method. The Fe3O4@LEV nanoparticles possess enormous potential to be recovered and reused by the magnetic property of synthesized Fe3O4 nanoparticles.