Anti-solvent crystallization: Particle size distribution with different devices

Abstract

Particle size distribution (PSD) is one of the critical attributes of crystals. PSD not only influences downstream processes but also controls final product performance in crystallization. In this work, we have used the model system of methanol–water-paracetamol for carrying out anti-solvent crystallization to produce paracetamol crystals. With reference to a base case of anti-solvent crystallization in a stirred tank, we have used three devices connected to the stirred tank with an external loop with full recycling. A peristaltic pump was used to circulate the contents of the stirred tank in an external loop comprising a simple tube, a fluidic oscillator (FO), and a vortex diode (VD). Anti-solvent was introduced at a point lying between the pump and these three devices to understand the influence of these devices on mixing and potential particle breakage. The PSD of crystals obtained with these three devices are compared with that of the base case for one supersaturation ratio (SSR = 1.63). The results indicated the potential of manipulating the PSD of crystals with a strategy of using fluidic devices in an external loop. The overall arrangement can be potentially extended to continuous crystallization.