Effects of solvent, supersaturation ratio and silica template on morphology and polymorph evolution of vanillin during swift cooling crystallization (Open Access)--颗粒学报PARTICUOLOGY

Ouyang, J., Xing, X., Chen, J., Zhou, L., Liu, Z., & Heng, J. Y. Y. (2022). Effects of solvent, supersaturation ratio and silica template on morphology and polymorph evolution of vanillin during swift cooling crystallization. Particuology, 65, 93-104. https://doi.org/10.1016/j.partic.2021.09.003

Effects of solvent, supersaturation ratio and silica template on morphology and polymorph evolution of vanillin during swift cooling crystallization (Open Access)

Jinbo Ouyang ^a *, Xiaohong Xing ^a, Jian Chen ^a, Limin Zhou ^a, Zhirong Liu ^a, Jerry Y.Y. Heng ^b

a Jiangxi Province Key Laboratory of Polymer Micro/Nano Manufacturing and Devices, East China University of Technology, Nanchang 330013, China
b Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK

10.1016/j.partic.2021.09.003

Volume 65, June 2022, Pages 93-104

Received 27 July 2021, Revised 24 August 2021, Accepted 6 September 2021, Available online 15 September 2021, Version of Record 14 October 2021.

E-mail: oyjb1001@163.com

Highlights

• Swift cooling crystallization of vanillin was investigated in different solvents.

• Morphology and polymorph evolution of vanillin were discussed.

• High supersaturation ratio exceeds 7.0 generating 100% metastable form II in water.

• Stable form I was obtained in other solvents at selected supersaturations.

Abstract

Swift cooling crystallization of vanillin was investigated in water, ethanol, isopropanol and ethyl acetate. Morphology and polymorph evolution of vanillin were discussed in terms of solvent, supersaturation ratio and silica template. PXRD, DSC, FTIR and microscope were used to identify polymorphs of vanillin. Results showed that the nucleated polymorphs of vanillin depended largely on the solvent, supersaturation ratio and silica template. Low supersaturation ratios favor the nucleation of stable form I in water, and high supersaturation ratio exceeds 7 generating 100% metastable form II. However, if the supersaturation ratio is too high (S>8), liquid–liquid phase separation will occur, and no crystals could be obtained. In other solvents such as ethanol, isopropanol and ethyl acetate, only form I was obtained. However, it should be noted that the morphology of form I prepared in ethanol, isopropanol and ethyl acetate is distinct from that obtained in water, the former is flake-like and the latter is rod-like. The nucleation of vanillin from different solution was also studied with the presence of SiO₂, SiO₂–NH₂ and SiO₂−COOH templates, which did not change the nucleated polymorph of vanillin, but changed the nucleation and growth rate of stable form I.

Graphical abstract

Keywords

Vanillin; Supersaturation ratio; Nucleation; Polymorph; Template

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