CO2 absorption

Carbonate is measured by evolution of carbon dioxide on treating the sample with sulfuric acid. The gas train should iaclude a silver acetate absorber to remove hydrogen sulfide, a magnesium perchlorate drying unit, and a CO2-absorption bulb. Sulfide is determined by distilling hydrogen sulfide from an acidified slurry of the sample iato an ammoniacal cadmium chloride solution, and titrating the precipitated cadmium sulfide iodimetrically. 

Various processes attempt to improve on the basic potassium carbonate process by using activators to increase the rate of CO2 absorption such as the Catacarb, Benfield, and Giammarco—Vetrocoke processes. 

Fig. 8.24 shows an example of a semi-closed plant (Cycle El) as studied by Chiesa and Lozza [17]. The CO2 absorption takes place downstream of the HRSG after further cooling with water removal. 

The reaction engineering model links the penetration theory to a population balance that includes particle formation and growth with the aim of predicting the average particle size. The model was then applied to the precipitation of CaC03 via CO2 absorption into Ca(OH)2aq in a draft tube bubble column and draws insight into the phenomena underlying the crystal size evolution. 

Figure 9-79E. CO2 absorption from atmosphere effect of tower pressure on ICqs at veirious liquor rates. Reproduced by pemrrission of the American Institute of Chemical Engineers, Spector, N. A., emd Dodge, B. F., Trans. AI.Ch.E., V. 42 (1946) p. 827 all rights reserved.

Figure 9-80. CO2 absorption in sodium hydroxide (NaOH). Used by permission of Leva, M., Tower Packings and Packed Tower Design, 2nd Ed., U.S. Stoneware Co. (now, Norton Chemical Process Products Coip.) (1953).

Figure 9-81. CO2 absorption effect of carbonate on Koa. Reproduced by permission of the American Institute of Chemical Engineers, Leva, M., AI.Ch.E. Jour., V. 1 (1955) p. 224 all rights reserved.

Figure 5.29 Special-type multi-purpose micro devices and mixing tee used for investigation of CO2 absorption. Comparison of their reactor performance as a function of the residence time. Micro bubble columns ( ) 1100 pm x 170 pm, (A) 300 pm x 100 pm and (T) 50 pm x 50 pm Interdigital mixer ( ) (40 pm) caterpillar mixer (A) (850 pm ramp) mixing tee (0) (1 mm) [5],...

Rotational spectroscopy and microwave astronomy are the most accurate way to identify a molecule in space but there are two atmospheric windows for infrared astronomy in the region 1-5 im between the H2O and CO2 absorptions in the atmosphere and in the region 8-20 xrn. Identification of small molecules is possible by IR but this places some requirements on the resolution of the telescope and the spacing of rotational and vibrational levels within the molecule. The best IR telescopes, such as the UK Infrared Telescope on Mauna Kea in Hawaii (Figure 3.13), are dedicated to the 1-30 xm region of the spectrum and have a spatial resolution very close to the diffraction limit at these wavelengths. 

Roberts, D. and Danckwerts, P. V. Chem. Eng. Sci. 17 (1962) 961. Kinetics of CO2 absorption in alkaline solutions. I. Transient absorption rates and catalysis by arsenite. 

Figure 30. IR spectrum of the recovered product after furan has been compressed at 3.5 GPa and irradiated with 50 mW of the 458-nm line of an Ar laser. Asterisks indicate the CO2 absorption bands.

Figure 6 illustrates another highly developed application of our FTIR facility. Trace (A) shows the complete absorbance spectrum, 600-3600 cm-1, of a CVS bag sample of a typical auto exhaust. While dominated by water vapor and CO2 absorption, several interesting features are visible. For instance, the carbon monoxide band is readily apparent, as is absorption due to heavy hydrocarbon (indicated by the broad unresolved C-H stretch band). In Trace (B) absorption due to CH4, NO2, formaldehyde and as well, water and heavy hydrocarbon can clearly be seen. In Trace (C),... 

Danckwerts and Gillham, in Trans. I. Chem. E., 44, 42, March 1966, studied the rate of CO2 absorption into an alkaline buffered solution of K2CO3 and KHCO3. The resulting reaction can be represented as... 

At least six major phytotoxic air pollutants have been shown to reversibly inhibit apparent photosynthetic rates in plants (1 - ). Studies indicate that these phytotoxicants ranked in the following order according to the relative amount of inhibition effected after several hours of exposure to equal pollutant concentrations HF>Cl2-03>S02>N02>N0. A summary of the experimental results which compares measured depressions in CO2 uptake rates of barley and oat canopies after 2-hr pollutant exposures in environmental chambers appears in Figure Typical inhibition and recovery rate curves for exposures that reduced CO2 absorption rates by 20 percent at the end of the 2-hr fumigations are also shown. Similar data have been obtained for alfalfa, another important crop species which was cultured and exposed under identical conditions In contrast, equivalent... 

In real atmospheres a wide array of pollutant combinations may occur. Plant responses described here represent only experimental combinations of major pollutants shown to inhibit CO2 absorption rates. Effects of other important phytotoxic atmospheric pollutants such as ethylene should also be examined along with more complex mixtures. Information regarding the responses of a wider range of plants subjected to varied environmental conditions would further aid in clarifying the problem. 

In concentrations approximating present air quality standards (Table III), O3 or SO2 in combination with NO2 could measurably suppress CO2 uptake rates of sensitive plants if exposed under favorable growing conditions. In the controlled environmental chamber studies, 1-hr exposures to 10 pphm O3 (which is slightly above the primary and secondary standards — i.e., 8 pphm for 1 hr) for example, depressed alfalfa CO2 absorption rates by approximately four percent. Exposures to 15 pphm hr SO2 in combination with an equal amount of NO2 reduced uptake rates by 7 percent. Alfalfa, barley or oat canopies exposed to these pollutants singly required higher concentrations (i.e., 1- to 2-hr treatments with more than 20 pphm SO2 or 40 pphm NO2) to measurably reduce canopy uptake rates. 

Bacterial inactivation is achieved by CO2 absorption in the liquid phase, even though the reason why it happens is still not clear. In this respect, batch- and semi-continuous operating modes are substantially different. In the batch system the residence time, i.e., the time of contact between gas- and liquid phase, must be sufficient to allow the diffusion of CO2 in the liquid, and is therefore a fundamental parameter to assure a desired efficiency. In the semi-continuous system the contact between the phases is localized in the surface of the moving micro-bubbles. In this second case, the efficiency of the process is influenced by temperature, pressure, gas flux, bubble diameter, and other parameters that modify the value of the mass-transfer coefficient. Therefore, it is not correct to use the residence time as a key parameter in the semi-continuous process. In fact, a remarkable microbial inactivation is reached even with an exposure time of 0 min (i.e., pressurizing and immediately depressurizing the system) these two steps are sufficient to allow CO2 to diffuse through the liquid phase. 

Kumagai et a/.[37] studied the relationship between the rate of CO2 absorption inside the micro-organism and the value of the operating pressure and were successful in correlating the rate of absorption with a kinetic constant of inactivation. Recent work of Enamoto et al. [38] confuted the hypothesis that the inactivation is due to the explosion of the cell during the depressurization step. 

Absorption is a process in which a component in a gas stream is absorbed by a liquid stream, such as the CO2 absorption in ammonia and methanol production lines. 

In the same samples, a second absorption feature was detected that is associated with the dopant ions themselves. These ligand-field transitions allow distinction among various octahedral and tetrahedral Co2+ species and are discussed in more detail in Section III.C. The three distinct spectra observed in Fig. 4(b) correspond to octahedral precursor (initial spectrum), tetrahedral surface-bound Co2+ (broad intermediate spectrum), and tetrahedral substitutional Co2+ in ZnO (intense structured spectrum). Plotting the tetrahedral substitutional Co2+ absorption intensity as a function of added base yields the data shown as triangles in Fig. 4(b). Again, no change in Co2+ absorption is observed until sufficient base is added to reach critical supersaturation of the precursors, after which base addition causes the conversion of solvated octahedral Co2+ into tetrahedral Co2+ substitutionally doped into ZnO. Importantly, a plot of the substitutional Co2+ absorption intensity versus added base shows the same nucleation point but does not show any jump in intensity that would correspond with the jump in ZnO intensity. Instead, extrapolation of the tetrahedral Co2+ intensities to zero shows intersection at the base concentration where ZnO first nucleates, demonstrating the need for crystalline ZnO to be... 

In this section, four examples illustrating the application of the rate-based modeling approach discussed above are presented. First three reactive absorption processes -namely absorption of NOx, coke gas purification and CO2 absorption by aqueous... 

The CO2 absorption is hindered either by slow chemical reactions in which the dissolved gas molecules are converted into the more reactive ionic species, or by low... 

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