Carbon dioxide, partial pressure

SolubiHty of carbon dioxide in ethanolamines is affected by temperature, amine solution strength, and carbon dioxide partial pressure. Information on the performance of amines is available in the Hterature and from amine manufacturers. Values for the solubiHty of carbon dioxide and hydrogen sulfide mixtures in monoethanolamine and for the solubiHty of carbon dioxide in diethanolamine are given (36,37). SolubiHty of carbon dioxide in monoethanolamine is provided (38). The effects of catalysts have been studied to improve the activity of amines and provide absorption data for carbon dioxide in both mono- and diethanolamine solutions with and without sodium arsenite as a catalyst (39). Absorption kinetics over a range of contact times for carbon dioxide in monoethanolamine have also been investigated (40). 

Table VI summarizes the material presented in the previous discussion. It correlates the changes in oxygen and carbon dioxide partial pressures, showing the pathological causes for the imbalances. In addition, it contains the various diagnoses of acid-base abnormality (using same numbers as in Figures 1 and 2 and Table I). Considering the format of Table VI as a tic-tac-toe set-up, we can label the nine portions by the letters A-I for identification in Table VII which gives examples of various conditions associated with such blood gas abnormalities (20-30).

Snider, G. L. Interpretation of the Arterial Oxygen and Carbon Dioxide Partial Pressures A Simplified Approach for Bedside Use. Chest (1973), 6, 801 - 806. 

The amount of carbon dioxide in the atmosphere is proportional to the partial pressure. Thus if partial pressure is expressed in units of the present level, the amount will become 56 X 1015 pco2 moles, where pco2 is the partial pressure of carbon dioxide. Expressing the reservoir in units of 1015 moles and the exchange rate in 1015 moles/y, the equation for the time rate of change of carbon dioxide partial pressure, assuming no other sources or sinks, becomes... 

The difference between the total dissolved carbon in the surface and in deep-sea reservoirs depends on productivity. And the difference between the alkalinity in these reservoirs depends on productivity and also corat, the calcium-carbonate-to-organic-carbon ratio. The carbon dioxide partial pressure depends on the difference between total carbon and alkalinity in the surface reservoir, and all these depend on the total amount of carbon and alkalinity at the start of the calculation in the three reservoirs combined. By adjusting the values of these various parameters and repeating the calculation, I arrive at the following values for a steady-state system that is close to the present-day ocean with a preindustrial level of atmospheric carbon dioxide ... 

Fig. 7-5. Outgoing long-wave planetary radiation as a function of temperature, comparing clear and cloudy skies for carbon dioxide partial pressure equal to one and four times the current level.

These values are based upon a pH of 5.5, temperature of 50°C, carbon dioxide partial pressure of 0.12 atm, calcium sulfite supersaturation ratio of 1.0, and calcium sulfate supersaturation ratio of 1.25. 

Minute ventilation versus alveolar carbon dioxide partial pressure... 

Alveolar carbon dioxide partial pressure versus minute ventilation... 

Nitrous oxide decreases tidal volume and increases the rate of breathing and minute ventilation. Although arterial carbon dioxide partial pressures tend not to be affected the normal ventilatory responses to carbon dioxide and to hypoxia are depressed. Alveolar collapse in structured lung segments may be more rapid in the presence of nitrous oxide than with oxygen due to its greater solubility. Similarly, it depresses mucous flow and chemotaxis. In theory these factors predispose to postoperative respiratoiy complications. 

In higher vertebrates this enzyme is quite abundant in the brain mainly as the cytosolic isoenzymes CA II, CA IV, and the membrane-bound isoform CA XIV (104,175 179). The inhibition of the brain CAs causes a selective increase of the cerebral blood flow with concomitant rise of carbon dioxide partial pressure (104,175-179). As a result CA inhibitors are recognized as potent candidates for treatment of... 

The dew point of the gas depends on the gas pressure and the carbon dioxide partial pressure. At fixed carbon dioxide composition, the dew point is lowered as total pressure decreases at fixed total pressure, the dew point is lowered as carbon dioxide composition decreases. Calculated dew points for a synthesis gas with 30 mol % carbon dioxide, for both ideal and real gas behavior, are shown in Figure 3 for syn gas pressures up to 1500 psia. 

The dew point must be warmer than -56.6°C to permit use of liquid carbon dioxide absorbent because pure liquid carbon dioxide cannot exist below the triple point. The carbon dioxide partial pressure, i.e., gas phase CO2 mol fraction times total pressure, of synthesis gas mixtures with -56.6°C dew points is plotted versus synthesis gas pressure in Figure 4. Increasing the H2 CO ratio at fixed total pressure decreases the carbon dioxide partial pressure required for a -56.6°C dew point. Liquid carbon dioxide can be used to absorb sulfur molecules for any combination of gas pressure and carbon dioxide partial pressure which lies above the curves of Figure 4. 

Although the process requires the treated gas to have a certain minimum carbon dioxide partial pressure for removal of sulfurous compounds with liquid carbon dioxide, promising new SNG processes under development produce medium to high carbon dioxide content crude gases ideally suited for acid gas removal via the CNG process (12,13). The novel features of the CNG process have been demonstrated with bench-scale process development units second generation process development units are in various stages of... 

It is now possible to write equations for the activities of aqueous carbon dioxide, bicarbonate, and carbonate in terms of carbon dioxide partial pressure and hydrogen ion activity, by rearranging equations 1.6, 1.9, and 1.12. 

Before proceeding, a few general comments will be helpful. In most cases at least one of the four carbonate system analytical quantities (total alkalinity, total CO2, carbon dioxide partial pressure, and pH) will be known. The equilibrium equations relating these quantities, along with those for water and calcite, will be used frequently in calculations. Also, in cases where calcite dissolution and... 

Park, P.K., Gordon, L.I., Hager, S.W., and Cissel, M.C. (1969) Carbon dioxide partial pressure in the Columbia River. Science 166, 867-868. 

Fig. 9. Schematic design of a carbon dioxide partial pressure (pC02) electrode. C02 diffuses through the membrane into or out of the electrolyte where it equilibrates with HCO, thus generating or consuming protons. The respective pH change of the electrolyte is sensed with a pH electrode and is logarithmically proportional to the pC02 in the measuring solution. Since the electrolyte may become exhausted, one can replace it through in/out lines. These can also be used to re-calibrate the pH electrode. Therefore, the electrode is retractable by means of a mechanical positioner...

Biosensors. Sensors are required to adequately monitor bioreactor performance. Ideally, one would like to have online sensors to minimize the number of samples to be taken from the bioreactor and to automate the bioreactor process. Most bioreactors have autoclavable pH and dissolved oxygen (D.O.) electrodes as online sensors, and use offline detectors to measure other critical parameters such as glucose and glutamine concentration, cell density, and carbon dioxide partial pressure (pC02). An online fiber-optic-based pC02 sensor is commercially available and appears to be robust.37 Probes are also commercially available that determine viable cell density by measuring the capacitance of a cell suspension. Data from perfusion and batch cultures indicate that these probes are reasonably accurate at cell concentrations greater than 0.5 X 106 cells/mL.38,39... 

Figure 4.5 Relationship between pH, carbon dioxide partial pressure, and estimated corrosion rate on carbon steel at 100°F (38°C)Z...

Whether corrosive constituents are removed at the oil or gas well or just before they enter cross country lines is a matter of economics (i.e., cost of the line, ease of replacement, etc). When dehydration or gas purification is not performed at the wellhead, severe corrosion may occur. Laboratory data on the corrosion rate vs partial pressure of carbon dioxide (Figure 4.5 in Chapter Four) often do not give a good estimate of the corrosiveness of the fluid because variables other than carbon dioxide partial pressure also affect metal loss. When the gas contains less than 15% oil (corrosion is low when there is more than 15% oil in the gas) and velocities are high, the chemical composition of the water, rather than the carbon dioxide partial pressure, appears to control the corrosion. The pH of the system calculated from the water composition has been used to determine whether or not a well is corrosive. To date, however, there is not a one-to-one correlation between the in situ pH and corrosiveness. 

A in. (6 mm) for vessels and exchangers with hydrogen sulfide partial pressures greater than 10 psi (0.07 MPa) or carbon dioxide partial pressures less than 4 psi (0.03 MPa). 

Maximum corrosion allowance. Primarily used for wet carbon dioxide equipment when the carbon dioxide partial pressure is less than 4 psf (30 kPa) and for sour water equipment when the hydrogen sulfide partial pressure exceeds 10 psi (70 kPa)... 

Conditions of rock weathering, sediment formation and therefore geochemical processes as a whole were different in the geological past (Veizer, 1973) oxygen and carbon dioxide partial pressures were different and there were more basic rocks available for weathering. The Precambrian sediments of the Canadian and Scottish shields are discussed by J. G. Holland and Lambert (1973) in relation to the composition of the continental crust. 

Neal, C., W. Alan House, and K. Down (1998). Assessment of excess carbon dioxide partial pressures in natural waters based on pH and alkalinity measurements. Science Total Environment. 210-211, 1-6, 173-185. 

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