羟基Fe、Al柱撑蒙脱石对庆大霉素的吸附行为

以蒙脱石(Mont)为原料,在不同OH/Fe物质的量比(x)和Fe/Al物质的量比(y)柱撑条件下制备出系列羟基铁(x OH/Fe-Mont)、羟基铝(OH/Al-Mont)和羟基铁铝(y Fe/Al-Mont)柱撑蒙脱石,采用XRD和FT-IR对柱撑蒙脱石进行表征,并研究了柱撑改性对蒙脱石对庆大霉素(Gen)吸附行为的影响.结果表明:柱撑蒙脱石对Gen吸附量显著提高,且Mont(42.83mg/g)OH/Al-Mont(63.50mg/g)1.5OH/FeMont(70.50mg/g)0.025Fe/Al-Mont(87.20mg/g),吸附Gen最佳p H值为9.等温吸附适于采用Freundlich方程拟合,吸附动力学符合伪二级动力学方程,吸附3h可超过平衡吸附量的80%.XRD分析表明,羟基铁和羟基铝主导柱撑(y≤0.5)蒙脱石层间距扩增是吸附量增加的主要原因,而y Fe/Al-Mont中y≥1.0时,层间距并不是吸附量变化的的主导机制;FT-IR分析表明阳离子交换是Gen和铝离子进入蒙脱石的主导机制.

Adsorption behavior of gentamicin on hydroxy-Fe-Al intercalated montmorillonite

Pristine montmorillonite (Mont) samples were used as raw materials to prepare hydroxyl-Fe-pillared Mont (xOH/Fe-Mont, x: molar ratio of OH/Fe), hydroxyl-Al-pillared Mont (OH/Al-Mont) and hydroxyl-Fe-Al-pillared Mont (yFe/Al-Mont, y: molar ratio of Fe/Al) composites for the adsorption of gentamicin (Gen). These composites were comprehensively characterized through X-ray diffraction (XRD) and Fourier transformed infrared (FT-IR) spectroscopy to reveal the adsorption behavior of pristine and modified Mont for Gen. The adsorption capacity of the Mont composites was significantly enhanced after modification, with the adsorption order of pristine Mont (42.83mg/g) << OH/Al-Mont (63.50mg/g) < 1.5OH/Fe-Mont (70.50mg/g) << 0.025Fe/Al-Mont (87.20mg/g). Specifically, the Mont composites showed the maximum adsorption capacity at pH 9. Furthermore, Freundlich adsorption isotherm model could well fit the experimental data. The pseudo-second-order kinetic model could sufficiently describe the kinetics of Gen adsorption, showing that over 80% of the equilibrium adsorption capacity of Gen can be obtained in 3h. XRD analysis demonstrates that the interlayer expansion in hydroxyl-Fe and hydroxyl-Al dominant (y≤0.5) pillared montmorillonite was the dominant reason for the enhancement of adsorption capacity of Gen. However, this is not a crucial indication for the enhancent in adsorption capacity of hydroxyl-Fe-Al-pillared Mont (y≥1.0). Through the FT-IR analysis, cationic exchange was the dominant mechanism for entering of both Gen and and hydroxyl-Al into the interlayer of hydroxyl-Al Mont.