| 초록 |
CO2 has been regarded as a useful chemical having many advantages that it is cheap, nonflammable, nontoxic, chemically inert, recyclable, and readily accessible to supercritical region. Especially, supercritical CO2 have interesting solvating characteristics and provide greatly increased mass transfer rates in various fields such as an organic synthesis, electrochemical synthesis, and polymerization, etc. In spite of these advantages, CO2 is also regarded as a poor solvent because the solubility of polar chemicals in CO2 which is nonpolar is very low. For this reason, the usage of CO2 as a reaction solvent with water has lagged. Recently, the efforts to overcome these disadvantages of CO2 are lively carried out by many chemists and engineers. One of these is the research about the formation of emulsion that polar chemicals of nano(nm) or micro(μm) size droplets in diameter were dispersed in CO2. It is desired that many polar chemicals will be soluble in CO2, therefore, it is applied in various fields such as reaction, separation, electroplating process etc. in supercritical CO2. Among these, the electroplating process in supercritical CO2 used the emulsion phenomena have been researched in my laboratory and this process will be resulted in reducing the aqueous plating solution. In formation of emulsion of immiscible phases like water or the aqueous plating solution and CO2 emulsion, the IFT has an influence in formation of emulsion. Therefore these data are requisite as a basic information to understand the emulsion with CO2. Unfortunately, the measurement of the IFT in high pressure CO2 was hardly carried out except for several studies. In this research, we manufactured the apparatus for IFT by using the capillary rise method in high pressure and measured the IFT of 1)water+CO2 at 20oC, 25oC, 38oC, and 71oC, 2)nickel plating solution+CO2 at 40oC, 55oC and 70oC, 3)nickel plating solution+CO2+surfactant (0.1, 0.3 wt%) at 40oC, 55oC and 70oC, and 4)nickel plating solution+CO2+surfactant (0.1, 0.3 wt%) + ethanol(10 vol%) at 40oC, 55oC and 70oC in the ranges of 0.1MPa~20.0MPa by using the capillary rise method. The consistency of experimental data was confirmed by comparing of experimental data and others data at 38oC and 71oC. |
