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Your search keyword '"Yak, Hwa Kwang"' showing total 19 results
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19 results on '"Yak, Hwa Kwang"'

18. Dry ice-originated supercritical and liquid carbon dioxide extraction of organic pollutants from environmental samples

Author

Chiu, Kong-Hwa, Yak, Hwa-Kwang, Wai, Chien M., and Lang, Qingyong

Subjects
*LIQUID carbon dioxide, *POLLUTANTS, *ORGANIC compounds, *COMPRESSED air
Abstract

Packed in a high-pressure vessel and under calculated conditions, dry ice can be used as a source of carbon dioxide for supercritical CO2 extraction or liquid CO2 of organic compounds from environmental samples. Coupled with a fluid modifier such as toluene, dry ice-originated supercritical CO2 (Sc CO2) achieves quantitative extraction of many volatile organic compounds (VOCs) and semivolatile organic compounds (SOCs) including polycyclic aromatic hydrocarbons (PAHs), n-alkanes, and polychlorinated biphenyls (PCBs) from solid matrices. Compared to contemporary manual or automated supercritical fluid extraction (SFE) technologies, this novel technique simplifies SFE to a minimum requirement by eliminating the need of a high-pressure pump and any electrical peripherals associated with it. This technique is highly suitable to analytical areas where sample preservation is essential but difficult in the sampling field, or where sample collection, sample preparation, and analysis are to be done in the field. [Copyright &y& Elsevier]

Published
2005
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19. Selective extraction of strontium with supercritical fluid carbon dioxide

Author

M. Wai, Chien, Yak, Hwa-Kwang, Chen, Xiaoyuan, Lee, Suh-Jane, and Kulyako, Yurii

Abstract

Strontium (Sr2+) can be selectively extracted from aqueous solutions into supercritical fluid CO2 at 60 °C and 100 atm with dicyclohexano-18-crown-6 (DC18C6) using CF3(CF2)6CO2– (PFOA–) or CF3(CF2)6CF2SO3– (PFOSA–) as a counter anion; at a mole ratio of Sr2+ : DC18C6 : PFOA– = 1:10:50, the extraction of Sr (5.6 × 10–5 M) from water at pH 3 is near quantitative whereas Ca2+ and Mg2+ at equal concentration are only extracted to a level of 7 and 1%, respectively; PFOSA– is an effective counter anion for selective extraction of Sr2+ from 1.3 M HNO3 with DC18C6 in supercritical CO2.

Published
1999
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