Solid-state NMR study of locations and dynamics of interlayer cationsand water in kanemite

Solid state water motions revealed by deuterium relaxation in 2H2O-synthesized kanemite and 2H2O-hydrated Na+-Zeolite A

“…In any case, these IR spectra clearly indicate that water in kanemite is much different than bulk water or ice, with low O-H bond stretching frequencies that are consistent with the solid state. The multiple peaks are consistent with the multiple forms of -O-H expected from the crystal structure, where the electron densities for silanol (Si-O-H) hydrogens and the O-H hydrogens of the water molecules directly coordinated to Na + are resolved, and at least two other types of water have been proposed [22,27]. Further detailed information must be obtained from the NMR analysis.…”

“…For comparison, the effective diameter of a water molecule is 0.28 nm and the diameter of a Na + ion is 0.19 nm [26]. X-ray crystallography and 23 Na solid state NMR of kanemite both show one Na + -binding site [22,27], but NMR studies of Zeolite A have shown variation in the location and coordination of Na + ions [28].…”

“…The temperatures reported on these instruments are accurate to ca. ±3 K down to 123 K. Single pulse excitation 29 Si, 27 Al, and 23 Na MAS spectra for 2 H 2 O-synthesized kanemite and 2 H 2 O-hydrated Zeolite A were obtained at room temperature on the solid state CMX-300 and Infinity 500 spectrometers. Theoretical 2 H NMR calculations were carried out with Mathematica Ò programs developed by the authors.…”

Reaction of layered sodium disilicate SKS-6 with calcium chloride solution as revealed by solid state NMR spectroscopy: Exploring the calcium ion extracting mechanism of SKS-6

“…In the silicate layer of SKS-6, each tetrahedral silicon atom is bonded to three other tetrahedral silicon atoms via bridging oxygen atoms, leaving one coordination oxygen atom in a non-bridging form (having a negative charge) [5]. For kanemite, its crystal structure consists of alternating single layer sheets of SiO 4 tetrahedra [(SiO 3 ) 3 SiO À Na + ] or [(SiO 3 ) 3 SiOH] and hydrated sodium ions layer [23][24][25]. When SKS-6 is surrounded by water molecules, sodium ions bound to the non-bridging oxygen atoms will be attacked by water molecules and the framework SiO 4 tetrahedra will begin to hydrolyze, leading to the formation of kanemite phase.…”

Reactivity and applications of layered silicates and layered double hydroxides

“…[18][19][20] The local structures and dynamics of interlayer Na cations and water have also been studied by solid-state 1 H-, 29 Si-and 23 Na-NMR. 21 The interlayer water is present in two different states (bound as well as free) in kanemite, as revealed by quasi-elastic neutron scattering (QENS), thermogravimetry (TG) and 2 H-NMR measurements. 22 It has also been found by 2 H-NMR T 1 relaxation study that the hydrated water in kanemite is in the solid state (icelike) at room temperature.…”