Adsorption temperature effect

Heats of Adsorption. Temperature effects were determined by measuring adsorption at three temperatures. As seen from TABLE IV, the K values vary with temperature such that for butylate, K increases with temperature, while for alachlor and metolachlor, K decreases with temperature. These results indicate that butylate becomes more adsorbed to Keeton soil as the temperature increases while alachlor and metolachlor become less adsorbed as temperature increases. In order to obtain a quantitative measure of these effects, heats of adsorption (AH) were calculated as described previously in the Materials and Methods section (equation 3). TABLE IV contains values for the average molar distribution constants (Kd) for butylate, alachlor, and metolachlor which were plotted vs the inverse temperatures (1/°K) to obtain the AH s shown in Figure 3. 

Adsorption temperature, effect on TPD spectra of oxygen on Pd-doped tin(IV) oxide, 74,75 Airborne chemicals, detection and identification, 299-307 Alcohol sensors, general discussion, 333... 

Other effects may also contribute to band broadening causing reduced achievable plate counts. Besides the already-mentioned wall adsorption, temperature effects (Joule heating) may reduce plate numbers. Sample application can have a strong influence on plate count, especially when large volumes and/or high sample concentrations are injected. Mobility differences between buffer constituents and analyte ions lead to asymmetric (triangular) peaks caused by electrodispersion, which is extremely noticeable with smaller molecules. Differ-... 

Figure 4.46. Thermal desorption spectra after electrochemical O2 supply to Ag/YSZ through the electrolyte for 10 min. Each curve corresponds to different adsorption temperature and current in order to achieve nearly constant initial coverage. Desorption was performed with linear heating rate, p=l K/s (Inset) Effect of potential on peak temperature.31 Reprinted with permission from Academic Press.

All heat evolutions which occur simultaneously, in a similar manner, in both twin calorimetric elements connected differentially, are evidently not recorded. This particularity of twin or differential systems is particularly useful to eliminate, at least partially, from the thermograms, secondary thermal phenomena which would otherwise complicate the analysis of the calorimetric data. The introduction of a dose of gas into a single adsorption cell, containing no adsorbent, appears, for instance, on the calorimetric record as a sharp peak because it is not possible to preheat the gas at the exact temperature of the calorimeter. However, when the dose of gas is introduced simultaneously in both adsorption cells, containing no adsorbent, the corresponding calorimetric curve is considerably reduced. Its area (0.5-3 mm2, at 200°C) is then much smaller than the area of most thermograms of adsorption ( 300 mm2), and no correction for the gas-temperature effect is usually needed (65). 

Adsorption behavior and the effect on colloid stability of water soluble polymers with a lower critical solution temperature(LCST) have been studied using polystyrene latices plus hydroxy propyl cellulose(HPC). Saturated adsorption(As) of HPC depended significantly on the adsorption temperature and the As obtained at the LCST was 1.5 times as large as the value at room temperature. The high As value obtained at the LCST remained for a long time at room temperature, and the dense adsorption layer formed on the latex particles showed strong protective action against salt and temperature. Furthermore, the dense adsorption layer of HPC on silica particles was very effective in the encapsulation process with polystyrene via emulsion polymerization in which the HPC-coated silica particles were used as seed. 

In Fig.7, the effect of the adsorption temperature of HPC in preparing the polymer-coated latices on the flocculation behavior of the system is demonstrated. It was found that both systems show almost the same behavior in flocculation, but evince a fairly different behavior in protection. The HPC-coated latex suspension treated at room temperature flocculated in a 1.2 Mol MgCl2 aqueous... 

Also, concerning the effect of the temperature on the reaction rates, different assumptions were made here with respect to our previous work.10 In that case, only the hydrogen and CO adsorption were regarded as activated steps, in order to describe the strong temperature effect on CO conversion. In contrast, due to the insensitivity of the ASF product distribution to temperature variations (see Section 16.3.1), other steps involved in the mechanism were considered as non-activated. In the present work, however, this simplification was removed in order to take into account the temperature effect on the olefin/paraffin ratio. For this reason, Equations 16.7 and 16.8 were considered as activated. 

The adoption of new hypotheses for the reactants adsorption, the removal of all the empiric laws and parameters, and a reevaluation of the temperature effect on product distribution have allowed us to obtain significant improvements with respect to our previous work,10 in terms of both fitting ability and model consistency. 

While inert and displacement purge regeneration is widely used in liquid phase separations, there are few industrially relevant inert purge systems employed in gas phase separations. It is sufficient to note that an inert purge regeneration can be done and it will generally be most effective at relatively high adsorption temperatures. 

Mills AC, Biggar JW (1969) Solubility-temperature effect on the adsorption of gamma and beta—BHC from aqueous and hexane solutions by soils materials. Soil Sci Am Soc Am Proc 33 210-216... 

Extensive studies of the acidity and basicity of zeolites by adsorption calorimetry have been carried out over the past decades, and many reviews have been published [62,64,103,118,120,121,145,146,153,154]. For a given zeolite, different factors can modify its acidity and acid strength the size and strength of the probe molecule, the adsorption temperature, the morphology and crystallinity, the synthesis mode, the effect of pretreatment, the effect of the proton exchange level, the Si/Al ratio and dealumination, the isomorphous substitution, chemical modifications, aging, and coke deposits. 

The effect of temperature on ammonia adsorption by ZSM5 samples has been investigated by microcalorimetry, varying the adsorption temperature from 150 to 400°C [235]. The initial heats of adsorption were independent of temperature up to 300°C. When the adsorption temperature increased, there was a competition between the formation of ammonium ions on Brpnsted sites and their decomposition. The total number of titrated sites decreased with increasing adsorption temperature. It appeared that an adsorption temperature between 150 and 300°C is appropriate for these calorimetric experiments. 

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