In Situ Determination of Interfacial Energies between Heterogeneously Nucleated CaCO3 and Quartz Substrates: Thermodynamics of CO2 Mineral Trapping
In Situ Determination of Interfacial Energies between Heterogeneously Nucleated CaCO3 and Quartz Substrates: Thermodynamics of CO2 Mineral Trapping
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DOI：
10.1021/es3014826
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发表时间：
2013-01-01
影响因子：
11.4
通讯作者：
Waychunas, Glenn A.
中科院分区：
文献类型：
--
作者：
Fernandez-Martinez, Alejandro;Hu, Yandi;Waychunas, Glenn A.
碳酸盐矿物的沉淀（矿物捕获）被认为是确保二氧化碳长期地质储存的最安全的封存机制之一。然而，很少有人知道的热力学因素控制的程度，在矿物表面的非均质成核暴露在多孔储层中的流体。本研究的目的是确定控制碳酸盐矿物在原始石英（100）表面上的非均质成核的热力学因素，这些表面被假定为砂岩储层的代表。为了探测溶液中CaCO 3在石英（100）表面的成核过程，采用了掠入射原位小角X射线散射技术。用此方法，通过测量不同溶液过饱和度下的成核速率，得到了控制CaCO_3异相成核的有效界面自由能α ' = 36 +/-5mJ/m ~ 2。该值低于控制方解石均质成核的界面能（α约为120 mJ/m（2）），表明在环境压力和温度条件下，碳酸钙在石英（100）上的非均质成核是有利的，成核势垒比均质成核所预期的低2.5%至15%。这些观测结果产生了重要的定量参数，很容易在水库规模的成核反应输运模型中使用。
The precipitation of carbonate minerals-mineral trapping-is considered one of the safest sequestration mechanisms ensuring long-term geologic storage of CO2. However, little is known about the thermodynamic factors controlling the extent of heterogeneous nucleation at mineral surfaces exposed to the fluids in porous reservoirs. The goal of this study is to determine the thermodynamic factors controlling heterogeneous nucleation of carbonate minerals on pristine quartz (100) surfaces, which are assumed representative of sandstone reservoirs. To probe CaCO3 nucleation on quartz (100) in solution and with nanoscale resolution, an in situ grazing incidence small-angle X-ray scattering technique has been utilized. With this method, a value of alpha' = 36 +/- 5 mJ/m(2) for the effective interfacial free energy governing heterogeneous nucleation of CaCO3 has been obtained by measuring nucleation rates at different solution supersaturations. This value is lower than the interfacial energy governing calcite homogeneous nucleation (alpha approximate to 120 mJ/m(2)), suggesting that heterogeneous nucleation of calcium carbonate is favored on quartz (100) at ambient pressure and temperature conditions, with nucleation barriers between 2.5% and 15% lower than those expected for homogeneous nucleation. These observations yield important quantitative parameters readily usable in reactive transport models of nucleation at the reservoir scale.