Reversible absorption capacity

Comparative study of various amines for the reversible absorption capacity of carbon dioxide... 

Aqueous solution of a-amino amides has been found to exhibit good reversible absorption capacity of carbon dioxide compared to amino alcohols when carbon dioxide is absorbed under 1 atm. However, the absorption capacity of a-amino amides is highly dependent on the partial pressure of carbon dioxide, the absorption capacity being considerably decreasing when carbon dioxide is absorbed under 0.1 atm. 

As shown above, the reversible absorption capacity of a-amino amides was comparable with those of amino alcohols when CO2 was absorbed under 1 atm. However, aqueous solutions of compounds 1-7 slowly undenwent hydrolysis when they were kept at 100 °C for a long time. Chemical stability is one of the... 

As discussed above, the reversible absorption capacity of the solution of amide 8 was better than those of amino alcohols under 1 atm of COj, though the absorption rate of the former compound was slower. However, when CO2 absorption was carried out by bubbling a gaseous mixture of COj and Ng in a ratio of 1 9, the COj loading value of the solution of 8 significantly dropped as compared to that of monoethanolamine, as shown in Table 2. The absorption ability of the solution of 8 became poor and its reversible absorption capacity was no better than that of monoethanolamine, either, under these conditions employed. This may be interpreted that the absorption ability of the tertiary amide 8 was highly dependent... 

All of above results suggest that such pillararene-based SOF materials with permanent porosity can be expected to have potential application in gas absorption. As displayed by the gas sorption isotherms measured up to 1 atm at 298 K, P5-SOF exhibits remarkably higher absorption capacity for CO2 through the dipole-dipole interactions between CO2 and hydrojyl groups, compared with CH4 and N2 under the same condition. The selectivity for CO2 is estimated to be 339 1 over N2, and 375 1 over CH4. It is also worth mentioning that this is the first report of a pillararene-based SOF material with a permanent porous stmcture and with extraordinarily selective and reversible absorption capacity for CO2 compared with that of most of the reported SOF materials with intrinsic cavities. Furthermore, it also provides a glimpse into the novel potential of P5-SOF materials in gas capture and further environmental engineering. 

In most processes, a reversible absorption of heat is accompanied by a change in temperature, and a calculation of the corresponding entropy change requires an evaluation of the integral of q/T. The term q is related to the heat capacity of the system which is usually expressed as a function of temperature. In a constant volume process, for example, the entropy change is... 

Solubility The reported relationship between water absorption and solubility of proteins has not been consistent. Water absorption capacity of sunflower concentrates increased slightly as the solubility index of the protein decreased (17). Hermansson (2 ) reported that a highly soluble protein exhibits poor water binding, but a reverse relationship between water absorption, evidenced by swelling and solubility, was not observed. In a later report, Hermansson (27) stated that solubility measurements give no information as to whether or not a protein will bind water. 

Carbon dioxide and some other gases which require removal from process streams are acidic. In order to improve the absorptive capacity of physical solvents, basic (alkaline) chemicals are added. The choice of chemical additive is determined by the ability to pick up the component of interest and to be able to release it again in the de-sorber. The absorption must be reversible and preferably by dropping the pressure. 

Alkanolamine solutions are generally used as chemical absorbent for the recovery of acid compounds from flue gases. Although the reaction between carbon dioxide and a variety of amino compounds, represented by monoethanolamines, has been widely studied , there is still a great need to develop more effective and chemically more stable absorbents. In the present study, we have prepared several different types of amino compounds and compared their capacity for the reversible absorption of carbon dioxide at different temperatures and under different pressures of carbon dioxide. 

In particular, these ILs when supported on silica gel effect fast and reversible CO2 absorption. The CO2 absorption capacity at equilibrium is 50 mol% of the ionic liquid but in the presence of water (1 wt%), the ionic liquids can absorb equimolar amounts of... 

Unfortunately, when hydride alloys traditionally used for compressors are cycled at temperatures over 100 C, their performance can deteriorate through a process termed "disproportionation." In relatively few cycles, reversible hydrogen absorption capacity is lost, which would cause a hydride compressor to stop working. 

A directly synthesized NaAlH4 doped with 4mol% of TiQ3 exhibited reversible hydrogen absorption over 116 cycles. After an activation process, the particular sample showed very stable reversible hydrogen capacities and sorption rates [137]. 

Table 1 shows the summary of absorption and desorption kinetics and hydrogen reversible capacity of Mg hydrides with ceramic catalysts at 300°C. 

The Li-Mg-B-N-H structure possesses storage capacity of more than 10 wt.% at around 150-200 "C. However, the reversibility of the hydrogen sorption characteristics was determined using pressure-composition isotherms as shown in Figure 6. From this study, we found reversible hydrogen absorption-desorption behavior (-3-4 wt.%) of the new complex hydride Li-Mg-B-N-H. The improvement in temperature and reversible hydrogen storage capacity were unaffected even after ten... 

For the final purification, a sequence of normal phase chromatography, size exclusion chromatography, reversed-phase (RP)-HPLC and other techniques are used. There are no general rules as to how to proceed but, due to the high capacity and low irreversible absorption of Sephadex, size exclusion should be used in the very beginning, whilst HPLC is better employed for the final purification steps. 

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