898
J. Phys. Chem. A 2010, 114, 898–903
Effects of the Polymorphic Transformation of Glutaric Acid Particles on Their Deliquescence and Hygroscopic Properties Ming Chee Yeung,† Tsz Yan Ling,†,‡ and Chak K. Chan*,†,§ Department of Chemical and Biomolecular Engineering and DiVision of EnVironment, Hong Kong UniVersity of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China ReceiVed: August 26, 2009; ReVised Manuscript ReceiVed: NoVember 9, 2009
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 R-form and the thermodynamically stable β-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 R-form deliquesced at 85-86% relative humidity (RH), whereas some R-form transformed to the β-form rather than completing full deliquescence. The β-form absorbed water slowly at 87-89% RH, which was higher than the deliquescence relative humidity (DRH) of the R-form. The water-uptake process was not completed in 5 h, but the particles deliquesced quickly (
