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

• Tipo: Artigo em Revista Científica Internacional
• Data: 2009

Autores

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

Revista

Título: Journal of Crystal Growth

Vol. 311 Nº 15

Páginas: 3841-3848

ISSN: 0022-0248

Editora: Elsevier

Indexação

ISI Web of Knowledge - 10 Citações

ISI Web of Science

Scopus - 12 Citações

INSPEC

COMPENDEX

Classificação Científica

CORDIS: Ciências Tecnológicas > Engenharia > Engenharia química

FOS: Ciências da engenharia e tecnologias > Engenharia dos materiais

Outras Informações

ID Authenticus: 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.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 8