Formation and Transformation Behavior of Sodium Dehydroacetate Hydrates
Xia Zhang,
Chuang Xie,
Yaohui Huang,
Baohong Hou,
Ying Bao,
Junbo Gong,
Qiuxiang Yin,
Sohrab Rohani
Affiliations
Xia Zhang
State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, No. 92 Weijin Road, Nankai District, Tianjin 300072, China
Chuang Xie
State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, No. 92 Weijin Road, Nankai District, Tianjin 300072, China
Yaohui Huang
State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, No. 92 Weijin Road, Nankai District, Tianjin 300072, China
Baohong Hou
State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, No. 92 Weijin Road, Nankai District, Tianjin 300072, China
Ying Bao
State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, No. 92 Weijin Road, Nankai District, Tianjin 300072, China
Junbo Gong
State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, No. 92 Weijin Road, Nankai District, Tianjin 300072, China
Qiuxiang Yin
State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, No. 92 Weijin Road, Nankai District, Tianjin 300072, China
Sohrab Rohani
Department of Chemical and Biochemical Engineering, The University of Western Ontario, London, ON N6A 5B9, Canada
The effect of various controlling factors on the polymorphic outcome of sodium dehydroacetate crystallization was investigated in this study. Cooling crystallization experiments of sodium dehydroacetate in water were conducted at different concentrations. The results revealed that the rate of supersaturation generation played a key role in the formation of the hydrates. At a high supersaturation generation rate, a new sodium dehydroacetate dihydrate needle form was obtained; on the contrary, a sodium dehydroacetate plate monohydrate was formed at a low supersaturation generation rate. Furthermore, the characterization and transformation behavior of these two hydrated forms were investigated with the combined use of microscopy, powder X-ray diffraction (PXRD), Raman spectroscopy, Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM) and dynamic vapor sorption (DVS). It was found that the new needle crystals were dihydrated and hollow, and they eventually transformed into sodium dehydroacetate monohydrate. In addition, the mechanism of formation of sodium dehydroacetate hydrates was discussed, and a process growth model of hollow crystals in cooling crystallization was proposed.
