CRYSTALLIZATION KINETICS OF OXALIC-ACID DIHYDRATE - NONISOTHERMAL DESUPERSATURATION OF SOLUTIONS

Oxalic acid dihydrate was dissolved in binary solvents (acetone:water and glycero:water) at various saturation temperatures and then cured at higher temperatures. A temperature programmer was used to both heat and cool the solution in a linear fashion. Desupersaturation was followed as a function of time by measuring the changes in solution concentration, and number-based particle size distributions of the resulting crystals were then determined. A model based on the numerical evaluation of the nucleation and growth rates was developed which describes the amount of oxalic acid dihydrate precipitated with respect to time during nonisothermal crystallization. The model allows for calculation of the nucleation and growth rate constants when used with established values of the nucleation and growth orders.