No abstract

This paper reports for the first time the development in the size and shape of sodium chloride crystals during antisolvent crystallization in ethanol under different sonication modes. Sonication using 98 kHz and a calorimetric power of 6 W was applied either continuously for a range of crystallization times (5−90 s) or intermittently (5 s pulse). Under silent conditions, a crystallization time of 90 s generated crystals with an average size of 73.8 ± 6.9 μm, in comparison to 8.7 ± 2.8 μm under 90 s of continuous sonication. However, it was observed that within the first 5 s of sonication at the beginning of the crystallization, the average crystal size was already reduced to 7.0 ± 3.3 μm. If the system was left to crystallize further to 90 s without ultrasound, the crystal size grew only slightly to 8.2 ± 1.4 μm. When a 5 s burst of ultrasound was applied during the crystallization process, a bimodal distribution of small (from sonication) and large crystals (from the silent period) was obtained. These results imply that the major influence of sonication is crystal nucleation rather than fragmentation, and equilibrium is reached with 5 s sonication by precipitating most of the crystals in solution.

In this work wet granulation experiments were carried out in a planetary mixer with the aim to develop a novel analytical tool based on surface texture analysis. The evolution of a simple formulation (300 g of microcrystalline cellulose with a solid binders pre-dispersed in water) was monitored from the very beginning up to the end point and information on the kinetics of granulation as well as on the effect of liquid binder amount were collected. Agreement between texture analysis and granules particle size distribution obtained by sieving analysis was always found. The method proved to be robust enough to easily monitor the process and its use for more refined analyses on the different rate processes occurring during granulation is also suggested.

Highlights ZIF-8 synthesis under different mixing speeds, US frequencies, powers and time. ZIF-8 crystals were formed after 5 s of reaction time. Sonication produced smallest crystals with an average size of 80 nm. Varying frequency and power did not significantly affect the crystal properties. Ultrasound has both positive and negative impact on crystal properties.

No abstract