Glass, porous, adsorption

We have also added for comparison in Column 2 of Table 1 the date of Sidorov [10] which indicate the shifts of the fundamental rOH band of porous glass upon adsorption of the same compounds from gas. In Column 4 [14] we compare our data with those obtained by Mecke for the shifts of the second overtone (3rOH) band of phenol dissolved in the same liquids. In the last column of the Table the shifts of the fundamental OH frequency of methanol, dissolved in the same solvents... 

Mason, G. (1988). Determination of the pore-size distributions and pore space interconnectivity of Vycor porous glass from adsorption—desorption hysteresis capillary condensation isotherms. Proc. R. Soc. Lond. A, 415, 453-86. 

Colloidal Alumina Alumina is available in a colloidal form which can be deposited on firebrick or glass beads, or on the wall of an open tubular column, to give a porous adsorptive layer which may be modified by addition of a liquid or other adsorbent such as colloidal silica. This way a wide variety of selective separating layers can be prepared. 

G. Kason, Deterainatlon of the Pore Size Distributions and Pore Space Interconnectivity of Vycor Porous Glass from Adsorption-Desorption Hysteresis Capillary Condensation Isotberas, Proc. Roy. Soc., 415A (1988) 453-486. 

Fig. 3.2 Adsorption isotherms for argon and nitrogen at 78 K and for n-butane at 273 K on porous glass No. 3. Open symbols, adsorption solid symbols, desorption (courtesy Emmett and Cines). The uptake at saturation (calculate as volume of liquid) was as follows argon at 78 K, 00452 nitrogen at 78 K, 00455 butane at 273 K, 00434cm g .

Fig. 4.25 Adsorption isotherms showing low-pressure hysteresis, (a) Carbon tetrachloride at 20°C on unactivated polyacrylonitrile carbon Curves A and B are the desorption branches of the isotherms of the sample after heat treatment at 900°C and 2700°C respectively Curve C is the common adsorption branch (b) water at 22°C on stannic oxide gel heated to SOO C (c) krypton at 77-4 K on exfoliated graphite (d) ethyl chloride at 6°C on porous glass. (Redrawn from the diagrams in the original papers, with omission of experimental points.)...

The support materials for the stationary phase can be relatively inactive supports, e.g. glass beads, or adsorbents similar to those used in LSC. It is important, however, that the support surface should not interact with the solute, as this can result in a mixed mechanism (partition and adsorption) rather than true partition. This complicates the chromatographic process and may give non-reproducible separations. For this reason, high loadings of liquid phase are required to cover the active sites when using high surface area porous adsorbents. 

Chromatographic Packings Prepared by Physical Adsorption of Polymers on Silica or Porous Glass... 

In 1971, Hiatt et al. found that polyethylene oxide (PEO) of molecular weight about 100000 prevented the adsorption of rabies virus to porous glass with an average pore diameter of 1250 A. The support was modified by passage of one void volume of 0.4% solution of the polymer in water, followed by 5 or more volumes of distilled water or buffered salt solution. The virus was effectively purified from the admixtures of brain tissue fluid by means of size-exclusion chromatography on the modified glass column [28]. 

Changes in relative peak intensity and marginal line shifts have been observed for benzene adsorbed on porous glass (26). More significantly, infrared spectroscopic evidence had been found in the appearance of inactive fundamentals for the lowering of molecular symmetry of benzene on adsorption on zeolites (47). 

A second type of defect is associated with boron or aluminum impurities that are present in SiCh- In porous glass Muha (129) observed a rather complex spectrum which results from hyperfine interaction with 10B and UB isotopes. The spectrum is characterized by g = 2.0100, g = 2.0023, an = 15 and a a. = 13 G for nB. The paramagnetic defect is apparently a hole trapped on an oxygen atom which is bonded to a trigonally coordinated boron atom. This center is irreversibly destroyed upon adsorption of hydrogen. 

A disadvantage of the reversed-phase HPLC technique or that of Derenbach et al. [82] is that it is only semi-quantitative. Against this is the fact that the technique using silanised porous glass is easy to keep free of contamination, has a comparatively high adsorption capacity, and permits the fractionated desorption of accumulated material. 

M. L. Ferrer and F. del Monte, Study of the Adsorption Process of Sulforhodamine B on the Internal Surface of Porous Sol-Gel Silica Glasses through Fluorescence Means, Langmuir, 2003, 19, 650. 

Various methods ofachieving preconcentration have been applied, including Hquid -hquid extraction, precipitation, immobihzation and electrodeposition. Most of these have been adapted to a flow-injection format for which retention on an immobihzed reagent appears attractive. Sohd, sihca-based preconcentration media are easily handled [30-37], whereas resin-based materials tend to swell and may break up. Resins can be modified [38] by adsorption of a chelating agent to prevent this. Sohds are easily incorporated into flow-injection manifolds as small columns [33, 34, 36, 39, 40] 8-quinolinol immobilized on porous glass has often been used [33, 34, 36]. The flow-injection technique provides reproducible and easy sample handhng, and the manifolds are easily interfaced with flame atomic absorption spectrometers. 

Since 1950, the scope and nature of these effects have been studied in greater detail. Amberg and McIntosh 67) were the first to use porous glass as the adsorbent and studied water adsorption. In later work 68, 69) butane, ethyl chloride, and ammonia were adsorbed. Flood and Heyding... 

Fio. 2. Length changes of porous glass produced by water adsorption as a function of free-energy lowering ( ) (67),... 

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