Qin Ling, Xie Qijie, Bao Jiuwen, Sant Gaurav, Chen Tiefeng, Zhang Peng, Niu Ditao, Gao Xiaojian, Bauchy Mathieu
School of Civil Engineering, Qingdao University of Technology, Qingdao 266033, China.
Post-doctoral Mobile Stations of Civil engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
ACS Sustain Chem Eng. 2024 Jun 24;12(27):10075-10088. doi: 10.1021/acssuschemeng.3c07814. eCollection 2024 Jul 8.
Calcium carbonate (CaCO) precipitation plays a significant role during the carbon capture process; however, the mechanism is still only partially understood. Understanding the atomic-level carbonation mechanism of cementitious materials can promote the mineralization capture, immobilization, and utilization of carbon dioxide, as well as the improvement of carbonated cementitious materials' performance. Therefore, based on molecular dynamics simulations, this paper investigates the effect of Si/Al concentrations in cementitious materials on carbonation kinetics. We first verify the force field used in this paper. Then, we analyze the network connectivity evolution, the number and size of the carbonate cluster during gelation, the polymerization rate, and the activation energy. Finally, in order to reveal the reasons that caused the evolution of polymerization rate and activation energy, we analyze the local stress and charge of atoms. Results show that the Ca-Oc bond number and carbonate cluster size increase with the decrease of the Si/Al concentration and the increase of temperature, leading to the higher amorphous calcium carbonate gel polymerization degree. The local stress of each atom in the system is the driving force of the gelation transition. The presence of Si and Al components increases the atom's local stress and average charge, thus causing the increase of the energy barrier of CaCO polymerization and the activation energy of carbonation.
碳酸钙（CaCO₃）沉淀在碳捕获过程中起着重要作用；然而，其机制仍仅被部分理解。了解胶凝材料的原子级碳酸化机制可以促进二氧化碳的矿化捕获、固定和利用，以及改善碳酸化胶凝材料的性能。因此，基于分子动力学模拟，本文研究了胶凝材料中Si/Al浓度对碳酸化动力学的影响。我们首先验证了本文所使用的力场。然后，我们分析了网络连通性演化、凝胶化过程中碳酸根簇的数量和大小、聚合速率以及活化能。最后，为了揭示导致聚合速率和活化能演化的原因，我们分析了原子的局部应力和电荷。结果表明，Ca - Oc键数和碳酸根簇大小随着Si/Al浓度的降低和温度的升高而增加，导致无定形碳酸钙凝胶的聚合度更高。系统中每个原子的局部应力是凝胶化转变的驱动力。Si和Al组分的存在增加了原子的局部应力和平均电荷，从而导致CaCO₃聚合的能垒和碳酸化活化能增加。
