Key Steps Influencing the Formation of Aluminosilicate Nanotubes by the Fluoride Route
Résumé
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 H2O 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 29Si, 27Al, and 19F magic angle
spinning nuclear magnetic resonance spectroscopy. The results show that the imogolite nanotubes can be prepared with high yields (>55%) from AlCl3·6H2O and Na4SiO4 aqueous solutions with an Al/Si molar ratio of 2.5, addition of HF for a
F/Si molar ratio of 0.1 À 0.2, and 4 days of crystallization at 98°C.