Structural studies of imogolite and allophanes by aluminum-27 and silicon-29 nuclear magnetic resonance spectroscopy

摘要: High-resolution aluminum-27 and silicon-29 nuclear magnetic resonance spectra of natural synthetic imogolites allophanes obtained using high-field“magic-angle” sample-spinning (MASS) techniques indicate that the imogolite protoimogolite components are characterized by sharp (≈3 ppm) resonances at −78±1 ppm from tetramethylsilane (in accord with Barron et al. 1982), quite narrow (≈10 11.7 Tesla) resonances, 5.2±1 Al(H2O) 6 3+ Wilson 1984). However, usually contain significant intensity arising a less well defined material, broad (≈20 centered −90±2 tetramethylsilane, second relatively (≈15 58.5±2 . Similar characteristic spectral features exhibited amorphous Si:Al (1:1) gel, presumably presence framework aluminosilicate materials in most allophanes.