Novel crystal morphology for sodium bicarbonate obtained by using the supercritical anti-solvent process.

The aim of this work was to develop a sustainable single-step process involving supercritical CO 2 as an anti-solvent to recrystallize sodium bicarbonate from an aqueous solution. First, a feasibility study validated the capacity to recrystallize sodium bicarbonate from a hydroalcoholic solution, under a pressure of at least 150 bar, an atomization jet solution velocity of at least 2.6 m·s−1 and a mass flowrate ratio X (CO 2 over solution) of at least 21.6. The crystals obtained were long, thick and zigzag-shaped. In a second step, an optimization of operating conditions was proposed to obtain crystals exhibiting an isometric habit. The most favourable conditions leading to the thickest and shortest crystals were 150 bar, 50 °C, an atomization velocity of 2.6 m·s−1, and a solute concentration of 0.45 g·(kg solvent)−1. No significant influence of higher pressure or higher atomization velocity was observed. [Display omitted] • Implementation of a single-step process of sodium bicarbonate recrystallization using supercritical CO 2 • Formation of a novel crystal morphology: long and thick zigzag shapes • A mechanism of Crystallization by Particle Attachment (CPA) suggested [ABSTRACT FROM AUTHOR]