One- and two-dimensional solid-state magic angle spinning NMR studies on the hydration process of layered sodium disilicate SKS-6.
Three different kinds of silanols, which include isolated silanol, silanol I (with the hydroxyl proton bonded to an oxygen atom in the adjacent layer) and silanol II (with the hydroxyl proton bonded to the non-bridging oxygen at the same silicon atom), are generated during the hydration process of SKS-6 (delta-Na2Si2O5). 1H-1H nuclear Overhauser enhancement spectroscopy reveals that the proton of silanol I has an effective chemical exchange or spin diffusion with the proton of hydrogen-bonded water, while the proton of silanol II is likely far away from the other proton-containing species. 29Si magic angle spinning, 1H-->29Si CP/MAS NMR and 1H-29Si phase-modulated Lee-Goldburg decoupled correlation experiments demonstrate that the local environments of the silicon sites in the final hydrated sample are mainly composed of Q2 [(SiO)2Si(OH)O(-)Na+], Q3 [(SiO)3Si(OH) and (SiO)3SiO(-)Na+] and Q4 [Si(OSi)4] groups.
Ai
Xuanjun
X
State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, The Chinese Academy of Sciences, Wuhan 430071, PR China.
Deng
Feng
F
Dong
Jinxiang
J
Hu
Wei
W
Xu
Hong
H
Ye
Chaohui
C