Adsorption mechanism of ofloxacin in water with "core-shell" magnetic adsorbent Mn 0.6 Zn 0.4 Fe 2 O 4 @SiO 2 -CeO 2 capable of oxidation regeneration

In order to remove ofloxacin (OFXL), which is difficult to biodegrade in water, and break through the bottleneck of solid-liquid separation and regeneration of adsorbents, Mn0.6Zn0.4Fe2O4 magnetic nanoparticles were modified by SiO2 and CeO2 to prepare Mn0.6Zn0.4Fe2O4@SiO2-CeO2 (MFSC) magnetic nanocompsite adsorbents. The as-prepared MFSC were systematically characterized using X-ray diffraction, infrared spectroscopy, scanning electron microscope, transmission electron microscope, vibration sample magnetometer. The investigation results of three kinetic models (quasi-first-order kinetics, quasi-second-order kinetics, and intraparticle diffusion models), three isotherm models (Langmuir, Freundlich and D-R models) and adsorption thermodynamics show that the adsorption rate is controlled by multiple factors such as intra-particle diffusion and liquid film diffusion; the adsorption process is dominated by physical adsorption, and the chemical adsorption is the rate-controlling step; the adsorption process is spontaneously and exothermic with entropy increase. The characterization results of infrared spectroscopy and X-ray photoelectron spectroscopy indicate that the interaction forces between MFSC and OFLX include π-π conjugation, hydrogen bonding and coordination. After six cycles of adsorption-oxidation regeneration in situ, the equilibrium adsorption capacity of MFSC for OFLX is 27.00 mg·g−1. The research results can provide basic theoretical data on the control technology of nonbiodegradable OFLX.