【摘要】 采用X射线衍射(XRD),傅立叶红外光谱(FT-IR)和魔角旋转核磁共振波谱(27Al-MASNMR)研究了在不同碱化度(R=OH/Al)下合成的Al胶体的结构.结果表明:在不同碱化度(R=2.6,2.7,2.8,2.9,3.0)下合成的新鲜Al胶体具有无定形性质,红外光谱中725 cm-1处(Al-O)Td键和核磁共振中6.3×10-5化学位移处的Al(O)4信号峰同时证明不同碱化度Al胶体和Al13溶液一样具有特殊的Keggin结构;红外光谱中(Al-O)Td强度随碱化度的增加而增强,表明高碱化度Al胶体(R=3.0)具有更多的Keggin结构;红外光谱中分为位于622 cm-1和550cm-1处(Al-O)oh和(Al-OH2)oh键的减少和消失表明高碱化度Al胶体(R=3.0)胶体中Keggin结构聚合程度更高;由于Keggin结构具有较高的正电荷数,高碱化度胶体具有更高的吸附性能.更多还原

【Abstract】 The X-ray diffraction(XRD),Fourier transform infrared spectra(FT-IR) and 27Al magic angle apinning(MAS) nuclear magnetic resonance spectroscopy were used to investigate the structure characteristics of Al gels that were synthesized under different basicity(R=OH/Al).The results show that the fresh Al gels with different basicity(R=2.6,2.7,2.8,2.9 and 3.0) have amorphous property.The(Al-O)Td vibration band at 725 cm-1 of IR and characteristic peak of Al(O)4 at 6.3×10-5 chemical shift of NMR both indicate that the Al gels has unique Keggin structure of Al13 species in solution.The intensity of(Al-O)Td band of IR increases with the increasing of basicity,which indicates that the Al gel with high basicity(R=3.0) has more Keggin structure.The decrease and disappearance of(Al-O)oh and(Al-OH2)oh IR bands at 622 cm-1 and 550 cm-1 indicate that the aggregation extent of Keggin structure of Al gel with high basicity(R=3.0) is higher.The Al gel with high basicity has better adsorption performance because of more positive charge of Keggin structure.更多还原