Carbon dioxide dissolution into water

Another interesting result of carbon dioxide solubility in water is that it constitutes the basis for the phenomenon of spontaneous and violent liberation of dissolved C02 to the atmosphere in a stratified lake, as in the case of Lake Nyos in Cameroon mentioned above (see Section 6.1.3). When dissolved C02 seeps from a hydrothermal vent into a stratified lake, the pressure and low temperature favor the dissolution and saturation in the lower strata of the lake. Because of its high solubility, more than five volumes of C02 can dissolve in one volume of water. As for any other gas, however, its solubility depends on temperature and pressure, making the... 

The two main mechanisms for removing carbon dioxide from the air are photosynthesis and dissolution into water (primarily the oceans). 

The investigated spray process is based on the dissolution of supercritical carbon dioxide (SCCO2) into the liquid which shall be atomized. Therefore, CO2 is one of the central substances within this project. The carbon dioxide is provided by YARA with a purity of 99.9% (v/v). The critical temperature of CO2 is 304.13 K the critical pressure amounts 7375 MPa. The solubility of CO2 in water is in the order of 2-5 wt.% at 313 K and a pressure range of 2-15 MPa [5]. The solubility of CO2 in polymers is in the range of 10 wt.% at 353 K and 14 MPa [6]. 

Experimental investigations of carbon dioxide mineral trapping have been started, but there is little understanding of the processes involved on the molecular level, due to the complex nature of the brine and the physical conditions present in the brine aquifers. One such complexity issue is the dissolution of CO2 from the gaseous phase into aqueous solution. This process is thermodynamically unfavorable with a ArG° value of 2.00 kcal/mol, in pure water at STP [3]. This becomes even more thermodynamically unfavorable as salts are introduced into the solution. Figure 17.1 shows how the solubility of CO2 in aqueous solution is also dependent upon the salt concentration and salt composition, even from simple salt solutions. According to Fig. 17.1, there is no correlation with size and the ability for the solution to uptake the C02. 

Kistler was first to recognize that silica gel would dissolve if subjected to supercritical conditions when the gel pores contained water, so he exchanged the liquid by washing the gel with ethanol [147], It is customary to exchange solvents, but even evacuation of organic solvents (alcohols, ethers, etc.) would sometimes result in gel dissolution. The main reason for this lies in the fact that typical sol-gel solvents have high values of critical parameters (Pc, T ), which increases their solvent power. Critical parameters of certain typical sol-gel solvents (water, methanol, ethanol, and carbon dioxide) are shown in Table 24.1. A way to bypass this problem is to exchange sol-gel solvent with liquid carbon dioxide, which can be transformed into supercritical fluid at relatively moderate conditions [141,147]. 

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