A deterministic formulation and on-line monitoring technique for the measurement of salt concentration in non-isothermal antisolvent crystallization processes

A complete framework to measure and anticipate the salt concentration during crystallization process is presented. On-line monitoring of the solute concentration based on conductivity of the solution is implemented. The conductivity of the dissolved compound is dependent on its concentration in the solvent and temperature. Therefore, a calibration test is applied and an experimental exponential model of concentration as a function of conductivity is developed in the whole operating range of antisolvent feed rate and temperature. A deterministic model which can predict the behaviour of the amount of salt with respect to the crystal growth parameter is introduced. To validate the model and assess the merits of the proposed strategy, the crystallization of sodium chloride in water using ethanol as antisolvent is performed in an experimental bench-scale semi-batch crystallizer.