The high cost of the CO₂ sequestration in saline aquifers is a barrier to the implementation of them. However, a large portion of the cost is invested to purify and transport the CO₂ from the flue gas stream of the emission sources. Therefore, the possibility of injecting impure CO₂ will reduce the costs strongly. The diffusion coefficient is an important factor that plays a significant role in different aspects of the process. In spite of its importance, it is got less attention due to complex experimental procedures and low range of temperature and pressure applicability in the experimental conditions. To shed light on the effects of the impurity on the diffusion coefficient of CO₂-water systems, two types of impurities (SO₂ and N₂) in two levels are considered in this study through the molecular dynamics simulation approach. Simulations are done on a wide range of pressure and temperature conditions to cover a wide range of operational conditions for CO₂ sequestration projects. The outcomes of these simulations were used in the direct numerical simulations to analyze the effect of the diffusion coefficient matrix changes on the CO₂ dissolution process such as dissolution flux, the motion and shape of convective fingers, and their patterns. Results indicate that impurity has a great impact on the diffusion coefficient, and consequently on the CO₂ dissolution behavior. We hope that reported results will pave the way for future studies regarding impure CO₂ sequestration in saline aquifers. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd.

中文翻译：

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CO2-SO2-水和 CO2-N2-水系统的扩散系数及其对 CO2 封存过程的影响：分子动力学和溶解过程模拟

咸水层中CO ₂封存的高成本是实施它们的障碍。然而，大部分成本用于从排放源的烟道气流中净化和运输CO ₂。因此，注入不纯CO ₂的可能性将大大降低成本。扩散系数是一个重要因素，在过程的不同方面起着重要作用。尽管它很重要，但由于复杂的实验程序和实验条件下的温度和压力适用范围低，它很少受到关注。为了阐明杂质对 CO _{2 -}水系统扩散系数的影响，两种杂质（SO₂和 N ₂ ) 在本研究中通过分子动力学模拟方法考虑了两个水平。模拟是在各种压力和温度条件下进行的，以涵盖 CO ₂封存项目的各种操作条件。这些模拟的结果用于直接数值模拟，以分析扩散系数矩阵变化对 CO ₂溶解过程的影响，例如溶解通量、对流指的运动和形状及其模式。结果表明，杂质对扩散系数有很大影响，因此对 CO ₂溶解行为。我们希望报告的结果将为未来关于咸水层中不纯 CO ₂封存的研究铺平道路。© 2021 化学工业协会和 John Wiley & Sons, Ltd.