Nephelometric measurements to investigate the influence of nucleation and growth kinetics on the evolution of new born crystals

The use of turbidimetric techniques has been applied since long time for the characterization of the particles in a suspension. Turbidimeters, based on the detection of on-axis light attenuation, are generally adopted for the characterization of moderately concentrated suspension and have been applied to fines detection. Nephelometers, based on the detection of scattered light, are more suitable for the characterization of more diluted suspensions, which is the case when nucleation starts. In this work the use of a nephelometric probe for the investigation on crystallization kinetics is reported. An experimental investigation on the nucleation of potassium sulphate crystals from aqueous solution was carried out by applying the isothermal method. The nephelometer allowed detecting the nuclei appearance. Moreover the recorded signal during the first period of time after nucleation can be related to the increase of the crystal mass in suspension, which accounts for nucleation and crystal growth processes.