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Kinetics of Calcite Dissolution in pH-region of Acid Rain.

Research Project

Project/Area Number 02650448
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field 資源開発工学
Research InstitutionTohoku University

Principal Investigator

CHIDA Tadashi  Tohoku Univ. Fac. of Eng. Professor, 工学部, 教授 (10005499)

Co-Investigator(Kenkyū-buntansha) NIIBORI Yuichi  Tohoku Univ. Fac. of Eng. Research Associate, 工学部, 助手 (90180562)
Project Period (FY) 1990 – 1991
Project Status Completed (Fiscal Year 1991)
Budget Amount *help
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1991: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1990: ¥1,300,000 (Direct Cost: ¥1,300,000)
Keywordsdissolution rate / calcite / activation energy / Stirring Reynolds Number / viscosity / weak acid region / acid rain / 環境問題 / 炭酸ガス / 炭酸塩鉱物 / pHフリ-ドリフト法 / 数学モデル
Research Abstract

The dissolution of limestone collected from Akiyoshidai, Yamaguchi Pref., Japan, In dilute hydrochloric acid solution has been followed by measurement both calcium concentration and pH as a function of time, under various conditions of Initial pH, temperature and stirring rate. The initial dissolution rate increases as the stirring rate increasing. The Arrhenius plot shows that apparent activation energy at 7OOrpm of stirring rate is 15kJ/mol for Initial pH4 and 25kJ/mol for Initial pH5.
The viscosity of water depends on temperature and differs about two times within the range from 5゚C to 40゚C in this experimental conditions, so stirring rate cannot express the real conditions of bulk fluid. In spite of stirring rate, Stirring Reynolds Number Re_s, which is one of non-dimension numbers possible to express fluid condition, defined as pd^2n/mu, where rho is the density of water, d characteristic length of stirring rate, n the revolutions per second, mu the viscosity of water, is proposed.
The initial dissolution rate at initial pH4 is almost proportional to Re_s and is independent from temperature. These facts suggest that the dissolution reaction process of calcite is much faster than the mass transport process of species. In the case of Initial pH5, the initial dissolution rate increases as Re_s Increasing and as temperature raising. The apparent activation energy of initial dissolution rate at Re_s = 7X10^4 for initial pH4 is lkj/mol and for initial pH5 is 12kJ/mol. These values are smaller than those obtained from stirring rate, because the previous studies have not considered fluid condition in estimation of the activation energy.
The facts mentioned above suggest that dissolution of calcite in weak acid region Is mass transport controlled reaction.

Report

(3 results)
  • 1991 Annual Research Report   Final Research Report Summary
  • 1990 Annual Research Report
  • Research Products

    (6 results)

All Other

All Publications (6 results)

  • [Publications] T.Shibuya,Y.Niibori,N.Tsuchiya,& T.chida: "Dissolution Mechanisum of Calcite" Abstracts of 1991 Joint Annual Meeting of SMGJ,JAM,PEG & MSJ. A-2 (1991)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] 渋谷 健,新堀 雄一,土屋 範芳,千田 佶: "弱酸性域における方解石の溶解速度" 資源地質学会誌. (1992)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] T. Shibuya, Y. Niibori, N. Tsuchiya & T. Chida: "Dissolution Mechanism of Calcite" Abstracts of 1991 Joint Annual Meeting of SMGJ, JAM, PEG & MSJ. A-2 (1991)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] T. Shibuya, Y. Niibori, N. Tsuchiya & T. Chida: "Dissolution Rate of Calcite in Weak Acid Region" J. of Minelogical Society of Japan. (1992)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] "Dissolution Mechanism of Calcite" T.Shibuya,Y.Niibori,N.Tsuchiya & T.Chida. A-2 (1991)

    • Related Report
      1991 Annual Research Report
  • [Publications] 渋谷 健,新堀 雄一,土屋 範芳,千田 佶: "弱酸性域における方解石の溶解速度" 資源地質学会誌. (1992)

    • Related Report
      1991 Annual Research Report

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Published: 1990-04-01   Modified: 2016-04-21  

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