Desorption, testing

In column sorption/desorption tests, a dimensionless time is often used and termed pore volume [268]. One pore volume (e.g., Vp) is the volume of pores (e. g., voids) present in the column that may be filled with water. The number of pore volumes passed through the column is thus ... 

It is important to differentiate between the two different types of sorption/ desorption tests (i. e.,batch and column-leaching), and the sorption characteristics determined from one should not be confused with the other. Sorption isotherms obtained with batch equilibrium tests are applied mainly to solid suspensions. The physical model, assumed with this situation, is one of a completely dispersed solid particle system, where all solid particle surfaces are exposed and available for interactions with the contaminants of concern. In contrast, column-leaching tests are performed with intact solid samples, and the sorption characteristics obtained from them are the results of contaminant interactions with a structured system where not all-solid particle surfaces are exposed or available for interactions with the contaminants. 

The second type of MgH powder was purchased from ABCR GmbH Co. KG, sold under the trade name MG-5026. Its average purity claimed by the supplier is 98% (remaining Mg). For simplicity, it will be referred to hereafter as the ABCR powder. Volumetric desorption tests were very reproducible, giving the average value of desorbed hydrogen equal to 7.5 wt.% which is nearly identical to the theoretical purity-corrected capacity of 7.51 at 98% purity. This testifies to... 

Figures 2.23 and 2.24 show the desorption curves and the Arrhenius plots for the calculation of the apparent activation energy of the Tego Magnan powder milled for 20 and 100 h, respectively. In both cases desorption tests were made under 0.1 MPa...

DSC tests show a substantial reduction of the hydrogen desorption onset (red circles) (T J and peak (T ) temperatures due to the catalytic effects of n-Ni as compared to the hydrogen desorption from pure MgH also milled for 15 min. (Fig. 2.57). It is interesting to note that there is no measurable difference between spherical (Fig. 2.57a) and fdamentary (Fig. 2.57b) n-Ni, although there seems to be some effect of SSA. We also conducted desorption tests in a Sieverts apparatus for each SSA and obtained kinetic curves (Fig. 2.58), from which the rate constant, k, in the JMAK equation was calculated. The enhancement of desorption rate by n-Ni is clearly seen. At the temperature of 275°C, which is close to the equilibrium at atmospheric pressure (0.1 MPa), all samples desorb from 4 to 5.5 wt.% within 2,000 s. 

Abiotic soil desorption measurements are probably the most important tests to precede measurement of microbial degradation. Desorption tests measure the site-specific soil/water partition coefficients for the contaminants of interest. Several experimental protocols are available for measuring partition coefficients (Wu Gschwend, 1986 Rogers, Tedaldi Kavanaugh, 1993). At the two extremes of bioavailability and biodegradability, contaminants can either be detected near their solubility limit or can be undetectable in the aqueous phase. Measurements of aqueous phase and soil phase concentrations in equilibrium may... 

Figures 1 and 2 show the abundance of the aliphatic and olefinic ion series (CnH2n+i)+ and (CnH2n-i)+, respectively, that resulted from deactivated parent H-mordenite catalysts at temperature conditions near 360°C. Desorption temperature precision was approximately 4°C. While reproducibility results are not shown, agreement was obtained between the results of duplicate desorption tests on separate samples of the same catalyst batch and the curves given in Figures 1, 2, and 3.

Hoshino, K., Kato, S., Tanabe, S., Ataka, Y., Ogawa, S. and Shimofuji, T. (2005) Measurement of VOC and SVOC emitted from automotive interior materials by thermal desorption test chamber method. Proceedings of the 10th International... 

Podoll, R. T., and W. R. Mabey. 1987. Factors to consider in conducting laboratory sorption/ desorption tests. In Fate and Effects of Sediment-Bound Chemicals in Aquatic Systems (K. L. Dickson, A. W. Maki, and W. A. Brungs, Eds.), SETAC Special Publications Series, pp. 99-108. Pergamon Press, New York. 

Tagami, H., Kanamaru, Y., Inoue, K. et al. Water sorption-desorption test of the skin in vivo for functional assessment of the stratum corneum. J. Invest. Dermatol. 78, 425-428 (1982). 

Kraus u. Dugone (33) stellen bei der Desorption von Butadien-Styrol-Copolymerisaten an RuB mit dem schleehten Losungsmittel w-Heptan nur geringe Desorption test. Nach Adsorption aus Heptan und an-schlieBender Desorption in Benzol bleibt mehr adsorbiert als dem Gleich-gewichtswert bei der Adsorption aus Benzol entspricht. 

ETES/ Catalyst mole initial desorption test... 

Figure 4. The change in 0Hoo n the water desorption test for ETES films on silica. (1% ETES in ct-chloronaphihalene )...

In the water desorption test the VTES films on flamed silica proved to be more resistant to change than the VTES films on air-dried silica. This difference is illustrated by the data in Figure 7. On air-dried surfaces after one hour adsorption time the VTES produced a film that initially had a low water contact angle and was not significantly altered in the desorption experiment. By allowing 20 hours contact with the solution a more hydrophobic film was obtained but it was quickly desorbed to a condition equivalent to that for only an hour adsorption time. On flamed silica, in contrast, the film adsorbed after 20 hours adsorption time showed only a slight tendency to lose its hydrophobic character. 

Acid-Base Catalyzed Adsorption. It was found that the addition of low molecular weight organic acids and bases to the adsorbate solutions produced ETES and VTES films that were much more hydrophobic and resistant to the water desorption test than the films formed by the tri-ethoxysilanes alone. Tables I and II list the values of yc and 0H2o for the films produced in the presence of various acids and bases. Also included are the data for the films formed by ETES and VTES alone. In all cases the adsorption time was 20-24 hours, the solvent was a-chloro-naphthalene and the triethoxysilane concentration was 1% by weight. 

The resistance of these films to alteration in the water desorption test is also indicated in Tables I and II and further illustrated by the data in... 

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