Particle breakage using wet mill, ultrasonic, and hydrodynamic cavitation

In-line fluidic devices and mills are often used for controlling crystal size distribution during crystallization. In this work, we investigated the breakage of organic crystals in three particle breakage devices. Paracetamol was selected as a model API (active pharmaceutical ingredient). In order to focus the investigation on particle breakage, we have used paracetamol suspended in its saturated solution and eliminated possible changes in particle size because of crystallization or dissolution. Particle breakage in a wet mill (WM), which is one of the commonly used particle breakage devices, is compared with the two cavitation-based devices: one based on ultrasonic or acoustic cavitation (AC) and the other based on hydrodynamic cavitation (HC). The particle size distributions (PSD) were measured by using laser diffraction. Kapur function analysis was used to study the effect of various conditions, such as rotational speed, intensity, or pressure drop, on the specific breakage rates and breakage mechanisms. The vortex-based HC device used in this work generated more fine particles than any other technique at a similar power consumption.