Polpação acetosolv de bagaço de cana e madeira de eucalipto

AUTOR(ES)
DATA DE PUBLICAÇÃO

1992

RESUMO

Acetosolv pulping of sugar cane bagasse and Eucalyptus grandis wood was studied with the objective to make adequate the conditions of this process for national feedstocks and to promote the integral use of lignocellulosic materials. The pulping of extracted and depithed sugar cane bagasse (8.0% humidity, 1.2% ash, 22.7% lignin and 53.2% cellulose) and eucalyptus wood chips (15.4% humidity, 0.5% ash, 3.5% extratives, 29.0% lignin and 54.7% cellulose) was performed in 93% acetic acid under reflux and normal pressure, using an inorganic acid as catalyst. The yield and Kappa number of these pulps was optimized with respect to cooking time, solvent/material ratio, nature and quantity of the catalyst and size of the wood chips. A more complete analysis of the pulps included determination of the viscosity, characterization by X-ray difraction and infrared spectrometry (IR). The isolated lignin was characterized by its Klason lignin content, IR spectrometry and C nuclear magnetic ressonance (NMR). During the pulping of sugar cane bagasse, yield and Kappa number of the pulps stabilized after 2 h of cooking. An increase of the solvent/material ratio reduced significantly the Kappa number. With 2 h of cooking and a solvant/material ratio of 14:1, an increase of the HCI quantity from 0.11% to 0.34% w/w reduced the Kappa number from 18 to 15 without reducing the pulp yield (56%). An increase of quantity of HBr from 0.14% to 0.28% w/w reduced the Kappa number from 17 to 12 and the pulp yield from 57% to 53%, respectively. In the acetosolv pulping of 0.4-0.6 mm thick wood chips, an increase of the solvent/material ratio decrease the pulp yield and the Kappa number. Reducing the thickness of chips to 0.1-0.3 mm, the Kappa number of the pulp was further reduced. Using 0.4-0.6 mm wood chips, solvent/material ratio of 7:1, 3 h of cooking and extracting the pulp with a Soxhlet, an increase of the HCI quantity from 0.11% to 0.34% w/w reduced the pulp yield from 60% to 56%, and the Kappa number from 18 to 14. Using 0.14% to 0.28% w/w of HBr, the pulp yield was reduced from 60% to 56% and the Kappa number from 15 to 13, respectively. The use of HCIO4 or FeCl3 as catalysts produced pulps with high percentages of rejects from sugar cane bagasse as well as from eucalyptus wood. With LiCl and ZnCl2, or in the absence of a catalyst, no pulp was obtained. The lignin was isolated in 50% to 92% yield with respect to the initial Klason lignin content and showed a content of Klason lignin of 86% to 93%. The IR and C-RMN spectra confirmed acetylation during the pulping process.

ASSUNTO(S)

quimica inorganica

ACESSO AO ARTIGO

Documentos Relacionados