Ludox Colloidal silica

When deconvolution is required, the time profile of the exciting pulse is recorded under the same conditions by replacing the sample with a scattering solution (Ludox (colloidal silica) or glycogen). 

Other colloids which have been fractionated and characterized by Fl-FFF include colloidal silica of 10-130 nm diameter [242] or down to 2 nm [17],Xylo-phene (emulsion), Stabisol (silica sol), Ludox (colloidal silica) and emulsion paints [237]. 

Colloidal silica NexSil aqueous colloidal silica (NYACOL, www.nyacol.com) LUDOX colloidal silica (SIGMA-ALDRICH, Inc., http / / WWW. sigmaaldrich. com ... 

E. I. du Pont de Nemours Co., Wilmington, Del., Ludox Colloidal Silica in the Textile... 

Ludox Colloidal Silica. Ludox colloidal silicas (DuPont) were among the first silica materials studied by FFF. In the first paper describing the applicability of FFF to colloidal silica (4), Ludox and related silicas were fractionated by flow FFF the fractionation was verified by transmission electron microscopy (TEM). The theory behind the fractionation and the acquisition of size distribution data was developed, and evidence of aggregation was examined. An example of the fractionation of four colloidal silicas from that study is shown in Figure 2. The primary drawback of this earlier work was the lengthy runs, in some cases requiring over 10 h. Most of the experimental runs on Ludox described in this section were completed in less than 10 min. 

Figure 4. Flow FFF (system Flow I) characterization of three different Ludox colloidal silica suspensions a, fractograms and b, particle size distributions.

Zeolite P-B (B or P Structure Type). Zeolite P-B was crystallized from coprecipitated gels using NaOH solution as the titrant and Ludox colloidal silica sol. The gel was crystallized at 150°-200°C for 45-72 hours. Phosphorus contents up to 23 wt % P203 were achieved in P-B zeolites. 

Table 3. Properties of SAPO-31 samples synthesized with different reagents in n-octane hydroisomerization. Reference sample. All samples contained 1 % Pt. Reaction temperature - 340 °C. Cab-O-Sil - Cab-O-Sil M5 firmed silica. Silicic acid with sp. surface area of 1000 m /g, AS-40 - Ludox colloidal silica, TEOS -tetraethoxysilane. Sample with Reheis F2000 was synthesized with Cab-O-Sil.

A process developed and used at DuPont to make Ludox colloidal silica does not completely deionize the silicate that enters the reactor. Rather, both sodium silicate and ion exchange resin are fed to a heel of water or silica sol. The relative rates are controlled in order to remove most. 

All manufacturers of water-borne colloidal silica publish charts of specific gravity versus silica content. Both manufacturers and users have long used the specific gravity of colloidal silica to determine its concentration. Hence, the correlation between the two has been well established. There is very little difference in the published values of this correlation from manufacturer to manufacturer, indicating that the density of the particles they produce is very similar. The following is a calculation based on such data for Ludox colloidal silica to calculate the density of the silica particles. They are considered to be representative of most of the commercially available silica sols. The one assumption is that the water molecules in the immediate vicinity of the silica particles still retain the density of normal water. Considering the high pressures needed to increase the density of water this would appear to be reasonable. 

New fibers are being developed which dissolve in the slightly alkaline pH of the lung. These fibers may eventually replace the more common alumino-silicate fibers especially in use where human contact with breathable fibers is likely. Alumino-silicate fibers do not have the same small size as asbestos fibers, but the mere fact that they are fibers, could become airborne, and the body has no rejection mechanism, has prompted some countries to view them with suspicion. Having fibers which provide the same thermal properties but which would dissolved in the lung would preempt the possible problem. However, fibers which dissolve in alkaline conditions cannot be used with alkali stabilized colloidal silicas. They need a binder which is stable but acidic in pH as described above. Such products were first developed at DuPont and are now available through W.R. Grace who acquired the Ludox colloidal silica business from DuPont... 

The data is taken from a Ludox Colloidal Silica bulletin It compares Ludox AM and Ludox HS which are both 12 nm sols containing 30% silica. In fact Ludox AM is made using HS as the colloidal silica to which sodium aluminate is added to introduce alumina sites into the particle surface. Ludox AM contains only about 0.2% alumina, which means that about 3-4% of... 

DuPont. Ludox Colloidal Silica Properties, Uses, Storage, and Handling. E.I. DuPont de Nemours and Co., Industrial Chemicals Dept. Product Information Bulletin H-47771-2, Wilmington, DE. 

Ludox colloidal silicas (DuPont) were among the first silica materials studied by FFF. In the first paper... 

Comparison of Mean Particle Diameters Experimental Conditions for Three Ludox Colloidal Silicas Measured under Different... 

An unusual approach to studying the charge on silica particles was employed by Deraska, Yaeger, and Hovorka (201). A Ludox colloidal silica having a particle diameter of 15 nni was subjected to ultrasonic vibration by placing electrodes at nodes and loops they measured the colloidal vibration potential which increased with silica concentration from zero to about 4% silica. The potential is presumably generated by the motion of the charged particles with respect to the fixed electrode. 

Collinson, M. M., N. Moore, P. N. Deepa, and M. Kanungo, 2003. Electrodeposition of porous silicate films from ludox colloidal silicae. Langmuir 19 7669-72. Collinson, M. M., D. A. Higgins, R. Kommidi, and D. Campbell-Rance, 2008. Electrodeposited silicate films Importance of supporting electrolyte. Anal Chem 80 651-56. 

The kinetics of phase separation in MB and MG glasses have been compared in several studies that are reviewed by Weinberg and Neilson [53]. Faber and Rindone [54] prepared a soda-lime-silicate glass by three methods MB from sand and carbonates, MG(I) using Ludox colloidal silica plus nitrates of Na and Ca, and MG(II) using TEOS plus nitrates. Chemical analysis showed that MB and MG(I) were very close in composition, but MG(II) was low in silica because of vaporization of TEOS. The glasses were melted at 1320°C for 48 h under flowing atmospheres of dry... 

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