可氧化再生的“核-壳”结构磁性吸附剂Mn_(0.6)Zn_(0.4)Fe_(2)O_(4)@SiO_(2)-CeO_(2)对水中氧氟沙星的吸附机制

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

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SiO_(2)和CeO_(2)功能化修饰Mn_(0.6)Zn_(0.4)Fe_(2)O_(4)磁性纳米颗粒,制备得到磁性纳米复合物吸附剂Mn_(0.6)Zn_(0.4)Fe_(2)O_(4)@SiO_(2)-CeO_(2),利用XRD、FTIR、SEM、TEM、和振动样品磁强计等对Mn_(0.6)Zn_(0.4)Fe_(2)O_(4)@SiO_(2)-CeO_(2)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Mn_(0.6)Zn_(0.4)Fe_(2)O_(4)@SiO_(2)-CeO_(2)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,Mn_(0.6)Zn_(0.4)Fe_(2)O_(4)@SiO_(2)-CeO_(2)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。

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_(0.6)Zn_(0.4)Fe_(2)O_(4)magnetic nanoparticles were modified by SiO_(2)and CeO_(2)to prepare Mn_(0.6)Zn_(0.4)Fe_(2)O_(4)@SiO_(2)-CeO_(2)magnetic nanocompsite adsorbents.The as-prepared Mn_(0.6)Zn_(0.4)Fe_(2)O_(4)@SiO_(2)-CeO_(2)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_(0.6)Zn_(0.4)Fe_(2)O_(4)@SiO_(2)-CeO_(2)and OFLX includeπ-πconjugation,hydrogen bonding and coordination.After six cycles of adsorption-oxidation regeneration in situ,the equilibrium adsorption capacity of Mn_(0.6)Zn_(0.4)Fe_(2)O_(4)@SiO_(2)-CeO_(2)for OFLX is 27.00 mg·g^(−1).The research results can provide basic theoretical data on the control technology of nonbiodegradable OFLX.