Wang Tiangui, Li Zuohu
Institute of Process Engineering, Chinese Academy of Sciences, P.O. Box 353, Beijing 100080, China.
J Colloid Interface Sci. 2005 Jan 1;281(1):130-5. doi: 10.1016/j.jcis.2004.06.094.
An understanding of the factors controlling calcite dissolution is important for modeling geochemical cycles and impacts of greenhouse gases on climate, diagenesis of sediments, and sedimentary rocks. It also has practical significance in the investigation of behavior of carbonates in petroleum and natural gas reservoirs and in the preservation of buildings and monuments constructed from limestone and marble. A large number of papers have been published on dissolution kinetics of calcium carbonate in aqueous solutions. But few involved the near-equilibrium region, especially at elevated temperatures and in concentrated solutions. In this paper, the dissolution kinetics of calcium carbonate in concentrated aqueous sodium dichromate solutions at pH 6.0-7.0 and 110-130 degrees C were studied in a 2-L autoclave. The results indicate that the dissolution reaction is mix-controlled, with surface reaction as the prevailing factor. The concentration of calcium ions in solution hardly affects the dissolution rate, but carbon dioxide in the vapor phase inhibits the dissolution reaction. The dissolution rate can be expressed by R = k(1)a(2)(H+) + k(2), and the apparent activation energy is 55-84 kJ mol(-1).
了解控制方解石溶解的因素对于模拟地球化学循环以及温室气体对气候、沉积物成岩作用和沉积岩的影响至关重要。它在研究石油和天然气储层中碳酸盐的行为以及保护由石灰石和大理石建造的建筑物和古迹方面也具有实际意义。关于碳酸钙在水溶液中的溶解动力学已经发表了大量论文。但很少涉及近平衡区域，尤其是在高温和浓溶液中。本文在2升高压釜中研究了碳酸钙在pH值为6.0 - 7.0、温度为110 - 130℃的浓重铬酸钠水溶液中的溶解动力学。结果表明，溶解反应是混合控制的，以表面反应为主导因素。溶液中钙离子的浓度几乎不影响溶解速率，但气相中的二氧化碳会抑制溶解反应。溶解速率可以表示为R = k(1)a(2)(H+) + k(2)，表观活化能为55 - 84 kJ mol(-1)。
