The metastable zone width (MZW) is one of the most essential parameters in industrial crystallization. The MZW is an area between the dissolution points and onset nucleation. This study demonstrated the determination of MZW of glycine in the presence of various carboxylic acids. MSZW of glycine was determined using the polythermal method described by Nyvlt. The experiments were performed in a 250 mL agitated double‐jacketed nucleation cell. Temperature control was ensured by a temperature control unit, cooling thermostat and IR lamp. The temperature of solution and nucleation were monitored by a temperature sensor Pt100 connected to the computer. The mixing of the solution was performed with a magnetic stirrer, and the stirring speed was set at 300 rpm. The experiments were carried out at different cooling rates of 4 °C/h, 12 °C/h, 16 °C/h and 20 °C/h in the presence of 50, 100 and 250 ppm acetic acid, tartaric acid and citric acid concentrations. Nucleation parameters were determined according to Nyvlt approach. Experimental results showed that carboxylic acids had a significant influence on MSZW of glycine. It was also detected that the dependence of the value of the metastable zone width of glycine was associated with the carboxylic acid type and concentrations. In the presence of all carboxylic acids studied, MSZW widened with the increasing the concentrations of carboxylic acids.
Anahtar Kelimeler: Metastable zone width, Glycine, Crystallization, Additive, Carboxylic acid
|
