Al-SBA-15有序介孔材料对溶液中诺氟沙星的吸附研究

On the adsorption of norfloxacin in the aqueous solution by the mesoporous silica AlSBA-15

以诺氟沙星(NOR)为目标有机物,对铝改性SBA-15(AlSBA-15)吸附水中有机污染物的特性进行了研究。采用直接合成法制备了Al-SBA-15,并通过X射线衍射(XRD)、N2吸附-脱附、透射电镜(TEM)、X射线荧光光谱(XRF)及红外光谱(FT-IR)技术对样品进行了表征。结果表明,Al-SBA-15对NOR的吸附符合准二级动力学模型和Freundlich等温吸附模型。溶液p H值对Al-SBA-15吸附NOR的性能影响显著,中性p H值下吸附效果最佳,在p H=7条件下,AlSBA-15对诺氟沙星(初始质量浓度为20 mg/L,Al-SBA-15投加量为0.5 g/L)的吸附去除率和平衡吸附量分别为94.15%和37.66 mg/g。推测Al-SBA-15对NOR的吸附机理为表面络合和静电协同作用,且在低p H值或高p H值条件下,静电作用对吸附效果影响较大。

The present paper has engaged in a study of the adsorption capacity of aluminum-modified A1 - SBA - 15 by taking norfloxacin （NOR） as a model compound. The said Al - SBA - 15 has been gained directly synthesized by adopting a triblock poly P123 as a template, and the tetraethoxysilane （TEOS） as the silica source and aluminium isopropoxide. The said material Al - SBA - 15 has been characterized by X-ray diffraction （XRD）, N2 adsorption-desorption, the transmission electron microscopy （TEM）, the X.ray fluorescence （XRF） and Fourier transform infrared spectroscopy （FT- IR）. The specific surface area of Al - SBA - 15 accounts for 523.7 m2/g whereas the molar rate （St：Al） is ll.46. What is more, it is possible to use the pseudo-first-order model to explain the adsorptive kinet- ics mechanism while the Freundlieh model helps to depict it more appropriately than with Langmuir isotherm. The analysis results show that the trivalent metal ion （Al3＋ ） is in a position to form surface complex compound with NOR so that the residual of silicon hydroxyl of Al - SBA - 15 can participate in the adsorption process at highly concentrated NOR solution. And, the adsorption capacity of Al - SBA - 15 wouldn＇t cease to increase until the concentration of NOR in the water increased to the adsorption maximum limit up to 88.24 mg/g and all the adsorption space of Al - SBA - 15 is taken by the saturat- ed NOR, The solution pH tends to have a significant effect on the adsorption capacity of Al - SBA - 15 with its optimal adsorption capacity of Al - SBA - 15 being in its neutral state. And, then, when pH value was 7.0, the removal rate of NOR （the initial concentration of 20 mg/L, Al SBA- 15 0.5 g/L） proves to be able to reach 94.15% with the equilibrium concentration of NOR on Al - SBA - 15 being 37.66 mg/g. What is more, the surface complex compound and the electrostatic interaction can both he able to control the adsorption process of NOR on Al- SBA - 15, though, at low and high pH value, the electrostatic interaction may play a more important role in the adsorption process. Thus, it can be seen that Al - SBA - 15 enjoys a very high adsorption capacity of Al3＋ due to the great specific surface area of mesoporous silica, which makes it highly effective to remove NOR from the water solution.