石膏脱水途径及可溶性硬石膏γ-CaSO4的复水机理,ACS Omega

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石膏脱水途径及可溶性硬石膏γ-CaSO4的复水机理
ACS Omega ( IF 3.7 ) Pub Date : 2019-04-26 00:00:00 , DOI: 10.1021/acsomega.8b03476
Yongbo Tang ₁ , Jianming Gao _{1,

2} , Chuanbei Liu ₁ , Xuemei Chen ₁ , Yasong Zhao ₁

Affiliation

采用热力学理论研究了不同温度和水蒸气压下石膏的脱水产物。此外，还通过蒙特卡罗（MC）模拟研究了可溶性硬石膏的再水化机理。热力学计算结果表明，石膏的脱水机理显着依赖于环境温度和水蒸气压。在高温低水蒸气压区，石膏一步脱水生成γ-CaSO _{4 (CaSO}₄ ·2H ₂ O→γ-CaSO ₄ )；随着水蒸气压的增加，石膏经历CaSO ₄ ·2H ₂ O→γ-CaSO ₄ →β-CaSO ₄ ·0.5H ₂ O反应路径，并且随着水蒸气压进一步增加，发生两步转化路径CaSO观察到₄ ·2H ₂ O→β-CaSO ₄ ·0.5H ₂ O→γ-CaSO _{4 。}还发现石膏在低温和高水蒸气压区域稳定并且不会脱水形成任何半水硫酸钙。最后，通过MC模拟研究了可溶性硬石膏的复水机理。模拟结果与实验数据一致，支持了γ-CaSO ₄在高相对湿度下再水合形成CaSO ₄ ·0.67H _{2 O的发现。}MC模拟揭示的另一个重要结果是，γ-CaSO ₄具有从极度干燥的大气中捕获水分子的非凡能力，这在某些领域非常有用，例如在干燥过程中，甚至用于从极度干燥的大气中提取液态水。气氛。

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Dehydration Pathways of Gypsum and the Rehydration Mechanism of Soluble Anhydrite γ-CaSO4

The dehydration products of gypsum under different temperature and water vapor pressure were investigated by thermodynamic theory. Additionally, the rehydration mechanism of soluble anhydrite was also studied by Monte Carlo (MC) simulations. The thermodynamic calculation results reveal that the dehydration mechanism of gypsum significantly depended on ambient temperature and water vapor pressure. In the high-temperature and low water vapor pressure region, gypsum dehydrates to form γ-CaSO₄ in a single-step process (CaSO₄·2H₂O → γ-CaSO₄); with increasing water vapor pressure, gypsum undergoes the CaSO₄·2H₂O → γ-CaSO₄ → β-CaSO₄·0.5H₂O reaction path and as water vapor pressure increases further, the occurrence of a two-step conversion path CaSO₄·2H₂O → β-CaSO₄·0.5H₂O → γ-CaSO₄ was observed. It was also found that gypsum is stable in the low-temperature and high water vapor pressure region and does not dehydrate to form any calcium sulfate hemihydrate. Finally, the rehydration mechanism of soluble anhydrite was studied by MC simulations. The simulation results are in agreement with the experimental data and support the finding that γ-CaSO₄ rehydration forms CaSO₄·0.67H₂O in high relative humidity. Another important result revealed by the MC simulation is that γ-CaSO₄ has an extraordinary ability to capture water molecules from an extremely dry atmosphere, which is very useful in some fields, such as in drying processes and even for extracting liquid water from extremely dry atmosphere.

更新日期：2019-04-26

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