Commercially available dry-cleaning solvents, such as hydrocarbon from petroleum distillates (aromatic, paraffin, naphthene) and tetrachloroethylene (perc), have done serious damages to our environment. In order to overcome these environmental problems, we have developed dry-cleaning washing systems for textile articles with liquid CO
2 as a substitute solvent. Liquid CO
2 is well known to be a greatly promising solvent because it is inexpensive, nontoxic and non-flammable. In this study, cleanings of some artificially soiled fabrics using both liquid CO
2 in high pressure equipment and aqueous surfactant solutions in H
2O and organic solvent (AK-225), with mechanical force by means of a magnetic stirrer, have been carried out to estimate and compare their detergencies obtained from reflectance measurements. As a result, the cleaning of oil stains made with motor oil with liquid CO
2 has a detersive efficiency of about 44%. The detergency increases with the addition of AOT, while it decreases with the addition of PEG. This increase of detergency with the addition of AOT might be due to the formation of O/W emulsions composed of a large amount of AOT in the mixture of liquid CO
2 and water, because the solubility of AOT is higher in water than in liquid CO
2, and thus CO
2 droplets in the water phase would be able to encapsulate oil stains such as those caused by motor oil. On the other hand, in the case of cleanings of water-soluble stains (coffee, red wine,
etc.) using liquid CO
2, the detergency remarkably increases, even with the addition of small amounts of aqueous surfactant solutions to liquid CO
2.
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