Zhai Hang, Chen Qiyuan, Duan Yan, Liu Bin, Wang Bu
College of Resources and Environment, Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, Southwest University, Chongqing 400716, China.
Department of Civil and Environmental Engineering, University of Wisconsin─Madison, Madison, Wisconsin 53706, United States.
Inorg Chem. 2024 Mar 11;63(10):4574-4582. doi: 10.1021/acs.inorgchem.3c04005. Epub 2024 Feb 27.
The aqueous carbonation of calcium silicate (CS), a representative alkaline-earth silicate, has been widely explored in studies of carbon dioxide (CO) mineralization. In this context, we conducted a specific comparison of the carbonation behaviors between the crystalline calcium silicate (CCS) and amorphous calcium silicate (ACS) across a pH range from 9.0 to 12.0. Interestingly, we observed opposite pH dependencies in the carbonation efficiencies (i.e., CaO conversion into CaCO in 1 M NaCO/NaHCO solution under ambient conditions) of CCS and ACS─the carbonation efficiency of CCS decreased with increasing the solution basicity, while that of ACS showed an inverse trend. In-depth insights were gained through Raman characterizations, indicating that these differing trends appeared to originate from the polymerization/depolymerization behaviors of silicates released from minerals. More specifically, higher pH conditions seemed to favor the carbonation of minerals containing polymerized silica networks. These findings may contribute to a better understanding of the fundamental factors influencing the carbonation behaviors of alkaline earth silicates through interfacial coupled dissolution and precipitation processes. Moreover, they offer valuable insights for selecting optimal carbonation conditions for alkaline-earth silicate minerals.
作为一种典型的碱土金属硅酸盐，硅酸钙（CS）的水相碳酸化在二氧化碳（CO₂）矿化研究中得到了广泛探索。在此背景下，我们对结晶硅酸钙（CCS）和无定形硅酸钙（ACS）在pH值为9.0至12.0范围内的碳酸化行为进行了具体比较。有趣的是，我们观察到CCS和ACS的碳酸化效率（即在环境条件下1 M Na₂CO₃/NaHCO₃溶液中CaO转化为CaCO₃的效率）对pH值的依赖性相反——CCS的碳酸化效率随溶液碱度的增加而降低，而ACS则呈现相反趋势。通过拉曼表征获得了深入见解，表明这些不同趋势似乎源于矿物释放的硅酸盐的聚合/解聚行为。更具体地说，较高的pH条件似乎有利于含聚合二氧化硅网络的矿物的碳酸化。这些发现可能有助于更好地理解通过界面耦合溶解和沉淀过程影响碱土金属硅酸盐碳酸化行为的基本因素。此外，它们为选择碱土金属硅酸盐矿物的最佳碳酸化条件提供了有价值的见解。
