Publication Date:
2015-10-27
Description:
Imogolite is usually formed by means of a three-step process involving the use of large amounts of water with long crystallization times and low yields, preventing large-scale synthesis. These drawbacks can be overcome by synthesis in the presence of fluoride, an approach which has been demonstrated to be suitable for the synthesis of other phyllosilicates. In the present study, the nature of the Al and Si sources, the Al/Si molar ratio, the volume of H 2 O for the redispersion of the gel after desalination, the F/Si molar ratio, as well as the crystallization temperature and time have been varied to investigate their role in the crystallization of imogolite. The structural properties of the as-synthesized samples were characterized by X-ray diffraction, infrared spectroscopy, and 29 Si, 27 Al, and 19 F magic angle spinning nuclear magnetic resonance spectroscopy. The results show that the imogolite nanotubes can be prepared with high yields (〉55%) from AlCl 3 ·6H 2 O and Na 4 SiO 4 aqueous solutions with an Al/Si molar ratio of 2.5, addition of HF for a F/Si molar ratio of 0.1–0.2, and 4 days of crystallization at 98°C.
Print ISSN:
0009-8604
Electronic ISSN:
1552-8367
Topics:
Geosciences
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