Spectra sodium silicate

Based on the characteristic shape of edge components in the EPR spectra of products formed by the mechanical treatment, UV irradiation (see Figure 7.31), or y-irradiation of nitrogen-doped vitreous silica, these components were assigned to =Si-N -Si= radicals. Mackey et al. [106] recorded an individual EPR spectrum of =Si-N -Si= radicals in sodium silicate glass. 

Figure 4 is a spectrum of a filter from the Proficiency Analytical Testing Program (PAT) conducted by the National Institute of Occupational Safety and Health (NIOSH) which contained 103 micrograms as determined by this lab. PAT filters are prepared with 2 mg of sodium silicate as a contaminant. A baseline approximation as described fo Figure 1 is not possible due to the interfering peak at 845 cm. When a spectrum of this type is encountered, a line is drawn from the two minimums on either side of the quartz doublet peak as illustrated by the dotted line in Figure 4. 

Figure 1 illustrates a high resolution 29si spectrum for a sodium silicate solution l 4.51-The individual resonances comprising this spectrum are grouped into bands each of... 

Figure 23 Room-temperature 99.4-MHz 29Si 2D INADEQUATE NMR spectrum of sodium silicate recorded in 1.5 days. Dashed lines show connectivities between pairs of spins. From Ref. 83, reproduced by permission of the American Chemical Society.

Fig. 5.15. The x-ray photoelectron oxygen Is spectrum of a sodium silicate glass (30 Na,O-70 SiO,), showing contributions from bridging oxygens (BO) and nonbridging oxygens (NBO) (after Jen and Kalinowski, 1989 reproduced with the publisher s permission).

Figure 5.2 Typical 29Si-NMR spectrum of sodium silicate solution with 3 mol% [Si02] and R= 1.5. Reproduced with permission from [2], Copyright (1986) Elsevier...

Figure 2. Binding energy (EV). ESC A 0(ls) spectrum of a sodium silicate glass, 30% Na 0 + 70% 5/0. (Reproduced, with permission, from Ref. 18. Copyright 1979, North-Holland Publishing Co.)...

Figure 2. NMR spectrum of a sodium silicate solution in D20 with a ratio of R = Na Si =0,14, The spectrum shows the resonance of the principal building units of a poly silicate. This and all of the other spectra were run on a Bruker WM 250, Conditions measuring time 1 h 8-s pulse length 0,8-s acquisition time.

Figure 5. Si NMR spectrum of a sodium silicate with a ratio of R z=i Na Si == 0,25, The lines due to small rings and cages are marked by asterisks and are next to the bands of the principal building units.

Figure 3. Si NMR spectra of aqueous alkaline sodium silicate solutions with atomic ratios Na Si = LO and concentrations 0.65 M in Si (8). Only bands B, C, D and E are shown, although bands D and E are not well separated for this solution. Key natural abundance Si, 49.7 MHz spectrum (a) Si enriched to 95.3%, 15.7 MHz spectrum (b). Conditions peaks unsplit for enriched sample ( ), assignments are given peak is spurious (f) chemical shift scale given with respect to signal for monomer, Q high-frequency-positive convention is used. Irradiation frequency increases to the left.

Figure 2. High-resolution Si NMR spectrum of a sodium silicate solution ([Si02] = 3.0 mol% R = 1.5). All chemical shifts are referenced to Si(OH)4 at 0 ppm (-71.3 ppm relative to TMS) [15].

Saumagne, P., and M. L. Josien, 1959. New technique for infrared spectroscopy of solid samples. Solid inclusion in poly(tetrafluoroethylene) disks. Publ. Group. Avan. Methodes Spectrog. 138. Schaefer, C., F. Matossi, and K. Wirtz, 1934. Infrared reflexion spectrum of silicates. Z. Physik. 89 210. Scheler, H., 1962. Solvolysis of inorganic salts. I. Formation of sodium trihydrogen orthosilicates by the methanolysis of sodium orthosilicate. Z. Anorg. Allgem. Chem. 314 298. 

The EDX spectrum (Fig. 11.8) shows the main surface scale impurity peaks of silica, aluminium, sodium, chloride and iron. If this EDX is compared to that of a new, clean membrane surface (Fig. 11.9), the clean surface shows sulphur, carbon and oxygen, which is typical of a porous polysulphone support. It was concluded that the scale is amorphous, composed of aluminosilicate and silicate. These compounds are normally found in trace amounts in brine solutions. Analysis showed that the surface could be cleaned with hydrochloric acid and analysis of the dissolved scale was similar to the EDX spectrum analysis. Review of the plant operation determined that the precipitation was the result of high pH in combination with high silica concentrations in the brine. 

Fortnum (4, 5), in his Raman spectrum study of aqueous ions, observed four distinct lines at 448, 607, 777, and 935 cm-1 which he attributed to the silicate ion. He adds that a fifth line is observed at 1040 cm 1 in solutions having little or no added sodium hydroxide however, this line disappears in solutions having large amounts of sodium hydroxide with an increase in sharpness and intensity of the 777- and 935-cm-1 lines. He says that there are two species which could have been present to give rise to the 1040-cm 1 lines either hydrolyzed silicate ion, SiO(OH)3 , or a dimer, H4Si2072. ... 

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