Hydrogen-bond mediated and concentrate-dependent NaHCO_(3) crystal morphology in NaHCO3–Na2CO3 aqueous solution: Experiments and computer simulations  

作　　者：Qiaoqiao Liu Guihong Lin Jian Zhou Liangliang Huang Chang Liu 

机构地区：[1]College of Chemical Engineering,Nanjing Tech University,Nanjing 210009,China [2]Zhangjiagang Institute of Nanjing Tech University,Suzhou 215699,China [3]Guangdong Provincial Key Laboratory for Green Chemical Product Technology,School of Chemistry and Chemical Engineering,South China University of Technology,Guangzhou 510640,China [4]School of Chemical,Biological&Materials Engineering,University of Oklahoma,Norman 73019,United States

出　　处：《Chinese Journal of Chemical Engineering》2023年第3期49-58,共10页中国化学工程学报（英文版）

基　　金：supported by the National Natural Science Foundation of China (21878143);the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)。

摘　　要：Adding Na_(2)CO_(3) to the NaHCO_(3) cooling crystallizer, using the common ion effect to promote crystallization and improve product morphology, is a new process recently proposed in the literature. However, the mechanism of the impact of Na_(2)CO_(3)on the crystal morphology is still indeterminate. In this work, the crystallization of NaHCO_(3)in water and Na_(2)CO_(3)–NaHCO_(3) aqueous solution was investigated by experiments and molecular dynamics simulations(MD). The crystallization results demonstrate that the morphology of NaHCO_(3) crystal changed gradually from needle-like to flake structure with the addition of Na_(2)CO_(3). The simulation results indicate that the layer docking model and the modified attachment energy formula without considering the roughness of crystal surface can obtain the crystal morphology in agreement with the experimental results, but the lower molecules of the crystal layer have to be fixed during MD. Thermodynamic calculation of the NaHCO_(3) crystallization process verifies that the common ion effect from Na^(+)and the ionization equilibrium transformation from CO_(3)^(2-) jointly promote the precipitation of NaHCO_(3) crystal. The radial distribution function analysis indicates that the oxygen atoms of Na_(2)CO_(3) formed strong hydrogen bonds with the hydrogen atoms of the(0 1 1) face, which weakened the hydration of water molecules at the crystal surface, resulting in a significant change in the attachment energy of this crystal surface. In addition, Na+and CO_(3)^(2-) are more likely to accumulate on the(011) face,resulting in the fastest growth rate on this crystal surface, which eventually leads to a change in crystal morphology from needle-like to flake-like.

关 键 词：NaHCO_(3) Crystal morphology Hydrogen bond Molecular simulation 

分 类 号：TQ131.12[化学工程—无机化工]