| Calcite Dissolution in Deionized Water from 50°C to 250°C at 10 MPa: Rate Equation and Reaction Order |
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| 作者姓名： | GONG Qingjie DENG Jun WANG Qingfei YANG Liqiang SHE Min |
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| 作者单位： | State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences, Beijing 100083;State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences, Beijing 100083;State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences, Beijing 100083;State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences, Beijing 100083;State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences, Beijing 100083 |
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| 基金项目： | This research was supported by the Ministry of Science and Technology of China (Grant No. 2003CB214603) and the State Key Laboratory of Geological Processes and Mineral Resources (Grant No. GPMR200636). |
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| 摘 要： | Carbonate minerals and water （or geofluids） reactions are important for modeling of geochemical processes and have received considerable attention over the past decades. The calcite dissolution rates from 50℃ to 250℃ at 10 MPa in deionized water with a flow rate varying from 0.2 to 5 mL/min were experimentally measured in a continuous flow column pressure vessel reactor. The dissolution began near the equilibrium with c/ceq 〉 0.3 and finally reached the equilibrium at 100℃-250℃, so the corresponding solubility was also determined as 1.87, 2.02, 2.02 and 1.88×10^-4.mol/L at 100℃, 150℃, 200℃ and 250℃ respectively, which was first increasing and then switching to decreasing with temperature and the maximum value might occur between 150℃ and 200℃. The experimental dissolution rate not only increased with temperature, but also had a rapid increase between 150℃ and 200℃ at a constant flow rate of 4 mL/min. The measured dissolution rates can be described using rate equations of R = k（1-c/ceq）n or R = kc-n. In these equations the reaction order n changed with temperature, which indicates that n was a variable rather than a constant, and the activation energy was 13.4 kJ/mol calculated with R = k（1-c/ceq）n or 18.0 kJ/mol with R = kc^-n, which is a little lower than the surface controlled values. The varied reaction order and lower activation energy indicates that calcite dissolution in this study is a complex interplay of diffusion controlled and surface controlled processes.
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| 关 键 词： | 方解石 分解 溶度 动力学 反应级数 |
| 收稿时间： | 1/3/2008 12:00:00 AM |
| 修稿时间： | 2008/5/15 0:00:00 |
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