Growth rates of sucrose crystallization from pure solutions of initial relative supersaturation levels between 0.094 and 0.181 were studied in agitated crystallizer at 313.13 K. Birth and spread model was applicable for the obtained growth rate data in this range of supersaturation and used to estimate the principal growth parameters. The estimated interfacial free energy varied inversely with supersaturation from 0.00842 to 0.00461 J/m 2 , respectively. The obtained kinetic coefficient changed with the initial supersaturation from 9.45 × 10 − 5 to 2.79 × 10 − 7 m/s. The corresponding radius of the 2D (two dimensional) critical nucleus varied from 7.47 × 10 − 9 to 1.46 × 10 − 9 m. Predominance of surface integration or volume diffusion mechanism during the growth process was assessed using the calculated activation free energies of the 2D nucleation process. An acceptable confirmation of the calculated radius of the critical 2D nucleus was found using atomic force microscopy (AFM) technique. The calculated interfacial free energy between the saturated sucrose solution and the crystal surface was found to be 0.02325 J/m 2 .

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A pseudo second-order kinetic expression was presented to explain the dissolution kinetics of solids in solution. The kinetic constant, initial dissolution rate, and theoretical saturation concentration according to pseudo second-order kinetic expression was defined. The proposed expression successfully represents the published dissolution kinetic profiles of alumina, digoxin, benzoic acid, lead chloride, and lecithin in solutions. A pseudo second-order kinetics based on fractional conversion successfully represents the dissolution kinetics of ulexite in ammonium acetate solutions. The pseudo second-order kinetics enabled the prediction of dissolution kinetics for higher residence time from experimental data obtained in relatively short time.