| Project/Area Number |
10650756
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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 |
反応・分離工学
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| Research Institution | Niigata University |
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Principal Investigator |
TAGUCHI Yoji Niigata University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (90018490)
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| Co-Investigator(Kenkyū-buntansha) |
KIMURA Isao Niigata Univ., Center for Cooperative Research, Associate Professor, 地域共同研究センター, 助教授 (00169921)
YAMAMOTO Satoshi Niigata Univ., Faculty of Agriculture, Professor, 農学部, 教授 (30018543)
AOYAMA Kiyomichi Niigata Univ., The Research Institute for Hazards in Snowy Areas, Associate Professor, 積雪地域災害研究センター, 助教授 (50018488)
KANO Naoki Niigata Univ., Faculty of Engineering, Research Associate, 工学部, 助手 (00272857)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 1999: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1998: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | Crystallization / Spherical ice / Impurities / Inclusion phenomena / Phosphate ion / Ammonium ion / Sulfate ion / Nitrate ion / 氷 / Inclusion / アンモニアイオン |
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| Research Abstract |
The inclusion phenomena of phosphate and ammonium ions into spherically shaped ice and the melting of the ice were examined beside acidic substances, and the following results were obtained.
1. From the melting of the spherically shaped ice formed by freezing a solution containing phosphate and ammonium ions as impurities, it was observed that the concentration (C) of both ions in the effluent was always high at the initial stage of melting, depending upon the melting methods which were applied. This suggests that the impurities (salts) were concentrated near the surface of the ice. When the growth rate of the spherical ice was lowered, or when the concentration (CィイD20ィエD2) of the impurity was decreased, a higher concentration ratio (C/CィイD20ィエD2) of phosphate and ammonium ions was observed. These inclusion phenomena were similar to those observed for sulfate, nitrate, and chloride ions which are usually included in acid snow as acidic substances.
2. The concentration distribution of ph
… More
osphate and/or ammonium included in spherical ice, having a diameter of 7 cm, was examined by slicing the ice from side to side and then melting it. A peak showing the maximum amount of ions was observed near the center of the ice spheres. The existence of a peak in the ice is apparently in conflict with the concentration change in the effluent when melting as mentioned above. In order to explain the conflict it was presumed that fast melting of the ice around the center, for example by melting point depression, resulted in the appearance of some cracks through which the melt around the center oozes from. This assumption has not yet been verified.
3. The phosphate and ammonium ions in the solution, adjusted to 0 - 0.5 ℃, were adsorbed on the spherical ice crystals, which were prepared with only water. The maximum adsorption amount was observed after a contact time of about 10 seconds. The amount of phosphate was larger than that of ammonium ; a relatively larger difference of selectivity was recognized. The adsorption isotherms were considered to be the Langmuir-adsorption type.
For further explanation of the inclusion phenomena of phosphate and ammonium ions into spherically shaped ice, we should construct a model for the estimation of a distribution curve by considering the growth rate of ice and the adsorption rate. Less
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