2000 Fiscal Year Final Research Report Summary
Fundamental studies on the removal of an oily contaminant in aqueous solutions by the application of the LB technique
| Project/Area Number |
10680113
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
家政学一般(含衣・住環境)
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| Research Institution | Kyoto University of Education |
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Principal Investigator |
GOTOH Keiko Kyoto University of Education, Associate protessor, 教育学部, 助教授 (30243356)
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| Project Period (FY) |
1998 – 2000
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| Keywords | Langmuir-Blodgett technique / Quartz crystal microbalance technique / arachidic acid / silane coupling agent / quartz glass / contact angle / surface free energy / saponification |
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| Research Abstract |
A well-defined model system was constructed by the application of the Langmuir-Blodgett technique to investigate the removal processes of oily contaminants in aqueous solutions.. Silica glass plates were treated with γ -aminopropyltriethoxysilane (APTES) and methyltriethoxysilane (MTES). The wettability of the substrates decreased by the silanization. Untreated and MTES-treated silica glass were negatively charged and APTES-treated glass was positively charged in water. Arachidic acid was used as a model oily contaminant. The surface pressure-area isotherms and the Brewster angle microscopic images of the spreading monolayers of arachidic acid on water were obtained, and the solid-condensed films were transferred onto the substrates by the vertical dipping method. The substrates with the LB films were ultrasonically washed in aqueous solutions. The detergency evaluated from the change in FT-IR spectra of the substrate decreased as a result of the silanization, especially for the APTES
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treated glass. The wettability and the surface charge of the substrate played important roles in the detergency. The removal of the LB films from the APTES-treated glass increased with increasing surfactant or ethanol concentration. The removal rate was strongly dependent on temperature. The monolayers of arachidic acid were transferred onto the gold electrodes of the quartz crystal microbalance (QCM) and then the QCM was cleaned in aqueous solutions containing sodium chloride, sodium hydroxide, surfactants and/or ethanol. The detergency was evaluated from the frequency change of the QCM.The detergency had a good correlation with the free energy change due to the penetration of a thin liquid layer between the arachidic acid films and the gold surface in the zone of contact, which was calculated using the experimentally determined contact angles and surface free energies. The saponification of arachidic acid by alkali as well as the penetration was shown to contribute to the oil removal. The exposure of the 172 nm UV eximer in air and the following ultrasonic washing were effective for the removal. Less
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