Lipophilic extractives in Eucalyptus globulus kraft pulps. Behavior during ECF bleaching

resumo

The composition of E. globulus kraft pulp lipophilic extractives and their behaviour during an ECF (DEDED) bleaching sequence were investigated. Sterols; fatty acids, including several alpha- and omega-hydroxyfatty acids; and long-chain aliphatic alcohols are the major lipophilic extractives of the unbleached pulp. During the bleaching, about 80% of the aliphatic extractives are removed from pulp (ca. 70% of the sterols, 70% of the fatty acids, and 90% of the long-chain aliphatic alcohols). The decrease of sterols is mainly due to the degradation of beta-sitosterol by chlorine dioxide, while the decrease of fatty acids and alcohols is essentially assigned to their extraction and elimination with the alkaline filtrates. The major chemical transformations in pulp extractives composition and structure occur in the last bleaching stages.

palavras-chave

CHLORINATED COMPOUNDS; PITCH DEPOSITS; CHEMICAL-COMPOSITION; WOOD EXTRACTIVES; MILL; TCF; GLUCURONOXYLAN; COMPONENTS; AOX

categoria

Materials Science

autores

Freire, CSR; Silvestre, AJD; Neto, CP

nossos autores

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