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.