Abstract
Using the spectrophotometric method, as a new method, the influence of dextran on the sucrose solubility and metastable zone width has been studied. In agreement with the literature the experimental data show that the dextran has a negligible effect on the sucrose solubility. The results also show that this impurity decreases the sucrose metastable zone width. The study of the nucleation kinetics performed, using Nyvlt’s approach, shows that the dextran accelerates the nucleation and that the nuclei are formed in the solution by instantaneous nucleation. The presence of dextran in the system causes a decrease in the growth rate of sucrose. The growth process of sucrose is governed by a Birth and Spread mechanism. The kinetic parameters of sucrose growth in aqueous solutions without and with dextran were estimated.
Highlights
Crystallization is an important process in industrial operations
Dextran can be formed if sugar cane stays in the sun for too long before being treated in mills, which decreases the amount of sugar available
The results show that the orders obtained from the experimental data for the different systems are found close to 1 indicating that the growth process of sucrose is governed by a Birth and Spread mechanism (B+S) [18]
Summary
Crystallization is an important process in industrial operations. In sugar manufacturing, crystallization is a crucial step that determines the quality of the final product, which requires control of its fundamental parameters. Impurities in supersaturated solutions significantly affect the nucleation, growth rate, morphology, and the agglomeration rate of the crystals [1]. Among these impurities, we find the dextran which has already been recognized as a serious problem in sugar processing [2]. Dextran is a branched polymer of dextrose (glucose) of very high molecular weight, belonging to the group of colloids It is one of the exopolysaccharides excreted by various soil microorganisms, which play an important role at the molecular level in the formation and conservation of soils (dextran, xanthan, rhamsan, and succinoglycan). Dextran can be formed if sugar cane stays in the sun for too long before being treated in mills, which decreases the amount of sugar available
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