| 초록 |
Emulsions and foams of CO2 and water are of high interest in various fields, including enhanced oil recovery, drug delvery systems, and microelectronics fabrication. High-pressure CO2 may also be utilized as non-toxic alternative to harmful volatile organic solvents. A set of high-pressure apparatus for generating CO2-in-water foam was utilized to measure the viscosity of the CO2-in-water foam in a range of experimental conditions from 35 to 55 oC up to the pressure of 3,500 psi. The effects of temperature, pressure, as well as capillary shear stress were analyzed for water-soluble surfactant that contains functional groups of trisiloxane as CO2-phile. Aqueous 2 wt.% surfactant solutions were mixed with the equal weight of CO2 to form 50:50 emulsions in the high-pressure apparatus. The apparent viscosity was calculated from the pressure drop measured in various lengths of capillary tubes by using Hagen-Poiseuille equation. The viscosity was measured as high as a few tens of centipoise when the surfactant was effective in forming stable foam. From observations of apparent viscosities with varying shear rate, the CO2-in-water emulsions exhibited shear-thinning behaviors. |
