Preparation of porous particles by liquid–liquid interfacial crystallization

Liquid–liquid interfacial crystallization was proposed as a novel method of controlling crystal shape and size of precipitated solute particles. The crystallization was performed at interface forming two separate phases of aqueous solution and organic solvent in the present study, and progressed by increase of supersaturation caused by the slightly mutual diffusion at the liquid–liquid system. This crystallization process is possible to precipitate particles at room and constant temperature without cooling or heating sources. The liquid–liquid interfacial crystallization method was able to carry out in changing the shape of the interface. A spherical shape was made by droplets in the present liquid atomization process. Crystallization started when the droplets of the solution sprayed into the organic liquid. Our research involved producing glycine porous particles by atomizing glycine solution into 1-butanol and other organic solvent with 3-fluid nozzle. The collision between the solutions in compressed air produced the micro-size droplets of glycine solution. In using 1-butanol liquid, the glycine crystallized at the glycine solution/1-butanol interface. The spherical aggregated particles were obtained in this spray granulation process. In addition, the transformation occurred from unstable β-structure to metastable α-structure with changing crystallization condition, and it was found that α- and β-structure of glycine coexist in the obtained particles from observation by X-ray powder diffraction.