Nonlattice Cation-SO42鈥?/sup> Ion Pairs in Calcium Sulfate Hemihydrate Nucleation
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- 作者：Guangming Jiang ; Hailu Fu ; Keith Savino ; Jiajing Qian ; Zhongbiao Wu ; Baohong Guan
- 刊名：Crystal Growth & Design
- 出版年：2013
- 出版时间：November 6, 2013
- 年：2013
- 卷：13
- 期：11
- 页码：5128-5134
- 全文大小：496K
- 年卷期：v.13,no.11(November 6, 2013)
- ISSN：1528-7505
文摘
A novel 鈥淸MSO4](2鈥?i>b)鈥?/sup> ion pair鈥?directed mechanism is presented to describe the role of nonlattice cations (Mb+) in the nucleation of calcium sulfate hemihydrate (CaSO4路0.5H2O, HH) in glycerol aqueous solution. By forming [MSO4](2鈥?i>b)鈥?/sup> ion pairs, univalent M+ ions (Li+, Na+, NH4+, and K+) and bivalent M2+ ions (Cu2+, Zn2+, Mn2+, and Mg2+) significantly increased the concentration of lattice ions (Ca2+ and SO42鈥?/sup>), resulting in a higher supersaturation of HH and shortening the induction time of HH nucleation. Meanwhile, [MSO4](2鈥?i>b)鈥?/sup> ion pairs replaced free SO42鈥?/sup> as dominant reactants for HH nucleation. They carried SO42鈥?/sup> and decoupled them at the nucleation sites for nucleus formation. The efficiency of Mb+ ions on promoting HH nucleation is governed by its pairing and decoupling capability with SO42鈥?/sup>. The difference between Mb+ ion and SO42鈥?/sup> in limiting diffusion coefficient (螖DMb+0) could characterize these two capabilities and was a robust indicator of the efficiency of Mb+ ion. This work provides a new understanding of cation-assisted crystallization and helps identify regulators for nucleation control.