可氧化再生的“核-壳”结构磁性吸附剂Mn0.6Zn0.4Fe2O4@SiO2-CeO2对水中氧氟沙星的吸附机制

Adsorption mechanism of ofloxacin in water with "core-shell" magnetic adsorbent Mn0.6Zn0.4Fe2O4@SiO2-CeO2 capable of oxidation regeneration

  • 摘要: 为去除水中难生物降解的氧氟沙星(OFLX),突破吸附剂固液分离和再生难的瓶颈,采用SiO2和CeO2功能化修饰Mn0.6Zn0.4Fe2O4磁性纳米颗粒,制备得到磁性纳米复合物吸附剂Mn0.6Zn0.4Fe2O4@SiO2-CeO2,利用XRD、FTIR、SEM、TEM、和振动样品磁强计等对Mn0.6Zn0.4Fe2O4@SiO2-CeO2进行了系统表征。3种动力学模型(拟一级动力学、拟二级动力学和颗粒内扩散模型)、3种等温线模型(Langmuir、Freundlich和D-R模型)和吸附热力学的研究结果表明:该吸附过程的速率由颗粒内扩散和液膜扩散等多种因素共同控制;该吸附过程以物理吸附为主,化学吸附为吸附速率控制步骤;吸附过程可自发进行,为放热和熵减小的过程。FTIR和XRD的表征结果表明,π-π共轭作用、分子间氢键和配位作用等是Mn0.6Zn0.4Fe2O4@SiO2-CeO2和OFLX之间的主要相互作用力。经6次吸附-氧化原位再生循环后,Mn0.6Zn0.4Fe2O4@SiO2-CeO2对OFLX平衡吸附量为27.00 mg·g−1。研究结果可为难生物降解的OFLX的控制技术研究提供基础理论数据。

     

    Abstract: 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 magnetic nanocompsite adsorbents. The as-prepared Mn0.6Zn0.4Fe2O4@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 Mn0.6Zn0.4Fe2O4@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 Mn0.6Zn0.4Fe2O4@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.

     

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