Effects of the polymorphic transformation of glutaric acid particles on their deliquescence and hygroscopic properties.
Effects of the polymorphic transformation of glutaric acid particles on their deliquescence and hygroscopic properties.
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DOI：
10.1021/jp908250v
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发表时间：
2010-01
期刊：
影响因子：
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通讯作者：
M. Yeung;Tsz Yan Ling;C. Chan
中科院分区：
文献类型：
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作者：
M. Yeung;Tsz Yan Ling;C. Chan
研究了谷氨酸（GA）颗粒的多晶型对其常温潮解性能的影响。通过拉曼光谱测量表征了GA的多晶型状态，包括亚稳态α-形式和结晶稳定的β-形式。通过拉曼和光学观察研究了GA颗粒的潮解。结果发现，α-型在85-86%相对湿度（RH）下潮解，而一些α-型转化为β-型，而不是完全潮解。β-型在87- 89%RH下缓慢吸水，这高于α-型的潮解相对湿度（DRH）。吸水过程在5 h内未完成，但当RH增加至约90%时，颗粒迅速潮解（<15 min），表明β形式的传质延迟，需要90%的较高RH才能穿过动力学屏障。我们发现，多晶型转化改变了GA颗粒的潮解特性，这可能解释了文献报道的GA颗粒的DRH值（83-90%）的差异。在未来的实验室实验和气溶胶热力学模型中应考虑这种转变。
The effects of the polymorphism of glutaric acid (GA) particles on their deliquescence properties at room temperature were studied. The polymorphic states of GA, including the metastable alpha-form and the thermodynamically stable beta-form, were characterized by Raman spectral measurements. The deliquescence of GA particles was also studied by Raman and optical observations. It was found that the alpha-form deliquesced at 85-86% relative humidity (RH), whereas some alpha-form transformed to the beta-form rather than completing full deliquescence. The beta-form absorbed water slowly at 87-89% RH, which was higher than the deliquescence relative humidity (DRH) of the alpha-form. The water-uptake process was not completed in 5 h, but the particles deliquesced quickly (<15 min) when the RH was increased to about 90%, indicating that mass transfer was delayed in the beta-form and that a higher RH of 90% was needed to cross the kinetic barrier. We showed that polymorphic transformation alters the deliquescence properties of GA particles, which might explain the discrepancies in DRH values of GA particles (83-90%) reported in the literature. This transformation should be taken into account in future laboratory experiments and aerosol thermodynamic models.