Competitive extraction of multi-component contaminants in water by Carboxen-polydimethylsiloxane fiber during solid-phase microextraction.

A headspace analysis for groundwater contaminated with BTEX (benzene, toluene, ethylbenzene, and xylenes) was employed to investigate the feasibility and limitations of Carboxen-PDMS (polydimethylsiloxane) fiber during SPME (solid-phase microextraction). Although the response of the Carboxen-PDMS fiber was much higher than that of conventional PDMS fiber, a reduction of the extracted amount was also observed under multi-component conditions due to competitive replacement. The general affinity of analytes to the fiber was high in the order xylene>ethylbenzene>toluene> benzene. The behavior of the Carboxen-PDMS fiber was examined more precisely at constant compositional ratio, because the analysis of contaminants using Carboxen-PDMS fiber was reported to be possible at known composition. The relative affinity of each component was shown to differ according to the total amount of analytes. Furthermore, the extracted amounts of benzene and toluene did not show a consistent tendency as the concentration of each component increased. These results indicate that caution should be exercised if Carboxen-PDMS fibers are used for the analysis of BTEX in groundwater samples.

Removal characteristics of anionic metals by micellar-enhanced ultrafiltration.

Surfactant-based separation of Fe(CN)(6)(3-) and CrO(4)(2-) using regenerated cellulose membrane was studied in order to assess the potential of micellar-enhanced ultrafiltration for the remediation of wastewater or groundwater polluted with ferriccyanide and chromate. In the ferriccyanide/octadecylamine acetate (ODA) and chromate/ODA systems, removal of ferriccyanide increased from 73 to 92% and to 98%, and that of chromate from 64 to 97% and to >99.9% as the molar ratio of ODA to ferriccyanide and to chromate increased from 1 to 2 and to 3, respectively. In the ferriccyanide/chromate/ODA system, while the removal of ferriccyanide increased from 62 to 72% and to 93%, the removal of chromate from 20 to 38% and to 68% as the molar ratio of ferriccyanide:chromate:ODA increased from 1:1:1 to 1:1:2 and to 1:1:4, respectively. With the molar ratio of 1:1:6, the removal was >99.9 and 98% for chromate and ferriccyanide, respectively. Ferriccyanide ions were more easily bound to ODA micelles because the binding power of ferriccyanide was greater than that of chromate.

Mass transfer of polyaromatic hydrocarbons (PAHs) in a two-liquid-phase system.

Studies were conducted to observe the solubility of phenanthrene, anthracene, and pyrene in four water-immiscible liquids (WILs) and the mass transfer of PAH in a two-liquid-phase (TLP) system. The order of solubility in WILs for three different PAHs was phenanthrene > pyrene >> anthracene. Among the WILs tested in a TLP system, paraffine oil did not affect the mass transfer of three PAHs, while silicone oil reduced the mass transfer of anthracene significantly because paraffine oil had a higher solubilizing capacity for anthracene than silicone oil. When initial PAHs concentration increased up to 2500 mg PAHs/kg soil, the mass transfer of phenanthrene and pyrene were hardly influenced, while that of anthracene was reduced to 40%. As the amount of light paraffine oil decreased, the mass transfer of anthracene decreased significantly compared to that of phenanthrene and pyrene. Based on the present results, it was confirmed that the mass transfer of PAHs from soil to WIL was governed mainly by the solubilizing capacity of WIL for PAHs. This is the first report on the mass transfer of PAHs from soil to WIL, in which the mechanism of TLP process can be understood more clearly.