1990 Fiscal Year Final Research Report Summary
Kinetic Study on the Chemical and Isotope Exchange Reactions Between Aqueous Solutions and Solid Compounds.
| Project/Area Number |
63420019
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
鉱物学(含岩石・鉱床学)
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| Research Institution | Tohoku University |
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Principal Investigator |
OHMOTO Hiroshi Tohoku Univ., Faculty of Science, Professor, 理学部, 教授 (60194304)
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| Co-Investigator(Kenkyū-buntansha) |
SUNAGAWA Ichiro Tohoku Univ., Professor Emeritus, 名誉教授 (20004426)
AOKI Kenichiro Tohoku Univ., Faculty of Science, Professor, 理学部, 教授 (00004276)
HAYASHI Kenichiro Tohoku Univ., Faculty of Science, Research Associate, 理学部, 助手 (40124614)
KITAKAZE Arashi Tohoku Univ., Faculty of Science, Research Associate, 理学部, 助手 (90035064)
TSUKAMOTO Katuso Tohoku Univ., Faculty of Science, Research Associate, 理学部, 助手 (60125614)
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| Project Period (FY) |
1988 – 1990
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| Keywords | Hydrothermal solution / Chemical reaction / Isotope exchange reaction / Kinetics / Reaction rate / Solubility |
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| Research Abstract |
The primary objective of this research was to develop a new experimental method for studies of the kinetics of reactions between minerals and solutions over a wide range of temperature and pressure. We have developed three new experimental methods and facilities, which are far superior to those used by previous investigators. The first one is an in situ observation method using a differential interference microscope and the principle of chemical titration ; the newly developed experimental facility is applicable to studies on reactions between a variety of solids (both organic and in organic) and solutions (both aqueous and non-aqueous) at temperatures upto-300^ﾟC and pressures up to-200 bars. The new experimental facility was used to determine the various kinetic parameters (reaction rates, mechanisms, solubility, etc.) governing the dissolution/growth of gypsum, barium nitrate, K-alum, and CdI_2 in aqueous solutions at 25^ﾟC, and barite in aqueous solutions at 25^ﾟ-200^ﾟC. The second
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new development is a high temperature photospectroscopic method for determination of the speciation of aqueous solutions during reactions with a solid compound. This method was successfully applied to the PbS-NaCI-H_2O system in the temperature range of 25^ﾟ to 350^ﾟC. The third new development is an application of the sulfur hydrolysis reaction to control the redox state of fluids, which is essential for studies on reaction kinetics of a mneral and solution involving redox reactions. This method was successfully applied to determine the reaction rates and the solubilities of gold and pyrite in aqueous solutions at 250^ﾟ-350^ﾟC. The reaction products from these experiments were analyzed for the sulfur isotopic compositions ; these data were used to obtain kinetic information on the redox reactions among aqueous species at high temperatures. The results of investigations described above, and those obtained from other studies in this project, are important steps toward establishing the principles governing the migration and accumulation of important elements in the Earth's crust and in the hydrosphere. Less
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