Zhu Jianping, Yang Kuo, Chen Yang, Fan Guangxin, Zhang Li, Guo Benkai, Guan Xuemao, Zhao Ruiqi
Henan Key Laboratory of Materials on Deep-Earth Engineering, School of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo 454003, China.
Henan Key Laboratory of Materials on Deep-Earth Engineering, School of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo 454003, China.
J Hazard Mater. 2021 May 5;409:124504. doi: 10.1016/j.jhazmat.2020.124504. Epub 2020 Nov 9.
Ordinary Portland cement (OPC) clinker mainly consist four minerals, tricalcium silicate (CS), dicalcium silicate (CS,), tricalcium aluminate (CA), and tetracalcium aluminoferrite (CAF). To learn the doping behaviors of Zn in OPC clinker, a series of samples were prepared by calcinating the mixtures of CaCO, SiO, AlO, FeO, and ZnO. Our results from energy-dispersive spectroscopy, X-ray diffraction and density functional theoretical simulations show that a small amount of ZnO enter CS and CS by replacing Ca ions while most incorporate into CAF by substituting Fe atoms, resulting in a decrease of CA in OPC as dosage increases. Further analyses from partial density of states and distributions of bond order-bond length indicate that the doping preference can be ascribed to the similar electron contributions and small structure distortions between host and guest ions. Unlike the strong Fe‒O bond, the newly formed Zn‒O is much weaker. The weak Zn‒O may be responsible for the limited solubility of Zn in CAF. These results provide a possibility of increasing solubility of Zn in OPC clinker by increasing the contents of CA and CAF, thus will be very meaningful in the synthesis of OPC clinker by utilizing Zn-bearing alternative raw materials.
普通硅酸盐水泥（OPC）熟料主要由四种矿物组成，即硅酸三钙（CS）、硅酸二钙（CS₂）、铝酸三钙（CA）和铁铝酸四钙（CAF）。为了研究锌在OPC熟料中的掺杂行为，通过煅烧碳酸钙、二氧化硅、氧化铝、氧化铁和氧化锌的混合物制备了一系列样品。我们通过能量色散光谱、X射线衍射和密度泛函理论模拟得到的结果表明，少量的氧化锌通过取代钙离子进入CS和CS₂，而大部分通过取代铁原子掺入CAF中，随着用量的增加，导致OPC中CA减少。通过态密度分布和键序-键长分布的进一步分析表明，掺杂偏好可归因于主体和客体离子之间相似的电子贡献和较小的结构畸变。与强的Fe‒O键不同，新形成的Zn‒O键要弱得多。较弱的Zn‒O键可能是锌在CAF中溶解度有限的原因。这些结果为通过增加CA和CAF的含量来提高锌在OPC熟料中的溶解度提供了可能性，因此在利用含锌替代原料合成OPC熟料方面将非常有意义。
