左氧氟沙星在铁氧化物表面的吸附：动力学和pH的影响

通过批吸附动力学、等温吸附试验，并结合X射线光电子能谱(XPS)技术和衰减全反射-傅里叶变换红外光谱(ATRFTIR)，揭示不同pH下左氧氟沙星(LEV)在铁氧化物表面的吸附机制。结果表明：溶液pH对LEV在针铁矿表面的吸附影响较大，不同pH下，其吸附动力学更符合准二级动力学模型(R²>0.98)。在pH为4时，3 h左右达到吸附平衡，而在pH为8时，12 h达到吸附平衡，并且pH为4的吸附量约是pH为8的2倍。XPS和ATR-FTIR的结果一致表明，静电作用和化学吸附是其主要吸附机制，在低pH(pH为4)时，LEV在针铁矿表面主要以单核双齿形态被吸附，在高pH(pH为8)时，主要以双核双齿形态被吸附。在中间pH(pH为6)时，由于静电排斥作用，导致其吸附量最大。

Effects of kinetics and pH on adsorption of levofloxacin on iron oxide surfaces

Batch adsorption kinetics, adsorption isotherm experiments, X-ray photoelectron spectroscopy(XPS) technology, and attenuated total reflection-fourier transform infrared spectroscopy(ATR-FTIR) were used in this investigation to gain insights into the levofloxacin (LEV) adsorption process on the surface of iron oxides at various pH values. Solution pH had a significant impact on LEV adsorption, and adsorption kinetics at different pH values were a good fit for the pseudo-second-order kinetic model(R²>0.98). At pH 4, adsorption equilibrium was reached in about 3 h, whereas it took 12 h at pH 8. The total amount adsorbed at pH 4 was almost twice of that at pH 8. XPS and ATR-FTIR results consistently indicated that electrostatic interaction and chemical adsorption were the main adsorption mechanisms. LEV was mainly adsorbed in bidentate binuclear form on the goethite surface at low pH(pH<6), and bidentate binuclear at high pH (pH>8). Adsorption capacity was greatest at intermediate pH(pH=6) due to electrostatic repulsion.