Unsteady-state transfer of impurities during crystal growth of sucrose in sugarcane solutions

• Type: Article in International Scientific Journal
• Date: 2009

Authors

Martins, PM (Author) FEUP; Ferreira, A (Author) FEUP; Polanco, S (Author) Other; Rocha, F (Author) FEUP; Damas, AM (Author) ICBAS; Rein, P (Author) Other

Journal

Title: Journal of Crystal Growth

Vol. 311 No. 15

Pages: 3841-3848

ISSN: 0022-0248

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 11 Citations

ISI Web of Science

Scopus - 12 Citations

INSPEC

COMPENDEX

Scientific classification

CORDIS: Technological sciences > Engineering > Chemical engineering

FOS: Engineering and technology > Materials engineering

Other information

Authenticus ID: P-003-HGH

DOI: 10.1016/j.jcrysgro.2009.05.021

Abstract (EN): In this work, we present growth rate data of sucrose crystals in the presence of impurities that can be used by both sugar technologists and crystal growth scientists. Growth rate curves measured in a pilot-scale evaporative crystallizer suggest a period of slow growth that follows the seeding of crystals into supersaturated technical solutions. The observed trend was enhanced by adding typical sugarcane impurities such as starch, fructose or dextran to the industrial syrups. Maximum growth rates of sucrose resulted at intermediate rather than high supersaturation levels in the presence of the additives. The effects of the additives on the sucrose solubility and sucrose mass transfer in solution were taken into account to explain the observed crystal growth kinetics. A novel mechanism was identified of unsteady-state adsorption of impurities at the crystal surface and their gradual replacement by the crystallizing solute towards the equilibrium occupation of the active sites for growth. Specifically designed crystallization experiments at controlled supersaturation confirmed this mechanism by showing increasing crystal growth rates with time until reaching a steady-state value for a given supersaturation level and impurity content.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 8