Fast and simple preparation of microparticles of KHCO3 by a freeze-dissolving method with single solvent or additional antisolvent†
Abstract
Microparticles featuring specific attributes are essential for the chemical industries. Microparticles of KHCO3 were prepared by a freeze-dissolving method, with one solvent or with additional antisolvent. Firstly, KHCO3 aqueous solution was dripped into liquid nitrogen to prepare ice spherical particles, and additional antisolvent, ethanol, was used to dissolve the ice scaffolding to isolate the microparticles of KHCO3. In this work we have developed a new freeze-dissolving method with only one solvent, water. After formation of ice particles, a low-temperature saturated aqueous solution of KHCO3 was used to dissolve the ice in frozen spherical particles at low temperature to isolate the microparticles. Both freeze-dissolving methods were 100 times faster and more energy-efficient than the traditional freeze-drying method. The microparticles of KHCO3 obtained by the freeze-drying method and freeze-dissolving with antisolvent and with saturated solution were characterised with SEM and the particle size distributions were compared.