Abstract
The objective of this study is to obtain the knowledge about the chemical changes of trichloroethylene (TCE) or tetrachloroethylene (PCE) in the processes of activated carbon adsorption and extraction by supercritical carbon dioxide.
TCE was extracted from 3 kinds of TCE loaded activated carbon samples -adsorbed from 100 ppm of aqueous solution, adsorbed from N2 gas blown through TCE saturated aqueous solution and adsorbed directly-. The infrared spectra of the fluids filtered by zeolite for dehydration after extraction showed normal TCE spectra. So, TCE did not change chemically in these processes.
The infrared spectra of some fluids for the activated carbon samples adsorbed from 50 ppm of PCE aqueous solution revealed the presence of not only PCE, but of TCE also. The dechlorination of PCE to TCE was found to occur in activated carbon fixed bed with adsorption from PCE aqueous solution. Produced TCE was able to be separated from PCE in the activated carbon fixed bed by “chromatographic effect”. In the process of extraction by supercritical carbon dioxide, PCE was found not to change chemically.
So, using the process of “activated carbon adsorption-supercritical carbon dioxide extraction”, TCE or PCE were able to be recovered witiout contaminations of water or products by decompositions, such as hydrolysis.
