Adsorption mechanism of ofloxacin in water with "core-shell" magnetic adsorbent Mn_0.6Zn_0.4Fe₂O₄@SiO₂-CeO₂ 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, Mn_0.6Zn_0.4Fe₂O₄ magnetic nanoparticles were modified by SiO₂ and CeO₂ to prepare Mn_0.6Zn_0.4Fe₂O₄@SiO₂-CeO₂ magnetic nanocompsite adsorbents. The as-prepared Mn_0.6Zn_0.4Fe₂O₄@SiO₂-CeO₂ were systematically characterized using XRD, FTIR, SEM, TEM, 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 FTIR and XRD spectroscopy indicate that the interaction forces between Mn_0.6Zn_0.4Fe₂O₄@SiO₂-CeO₂ and OFLX include π-π conjugation, hydrogen bonding and coordination. After six cycles of adsorption-oxidation regeneration in situ, the equilibrium adsorption capacity of Mn_0.6Zn_0.4Fe₂O₄@SiO₂-CeO₂ for OFLX is 27.00 mg·g⁻¹. The research results can provide basic theoretical data on the control technology of nonbiodegradable OFLX.