José Lívio Gomide

Caracterização tecnológica, para produção de celulose, da nova geração de clones de Eucalyptus do Brasil

Last generation of Eucalyptus clones pulped by the main Brazilian kraft pulp mills were used for this study. Detailed chemical analysis of the woods were carried out to establish the wood quality. Laboratory simulation of a modern continuous digester technique was used for pulp production. Results demonstrated the high quality of Eucalyptus clones wood that are being planted in Brazil for kraft pulp production.

Análise de critérios de qualidade da madeira de eucalipto para produção de celulose kraft

Seventy five Eucalyptus wood clones obtained from different geographic regions in Brazil were used for this study. Based on statistical analysis it was demonstrated that an active alkali charge and also wood lignin and extractive contents presented a significant effect on pulping yield. Wood specific gravity did not present a significant effect on pulping yield but affected wood consumption for pulp production (m3wood/ ton pulp). Wood specific gravity, lignin content and extractive content were recommended as criteria to establish wood quality prior to pulping characteristics determination.

Influência da densidade básica da madeira na qualidade da polpa kraft de clones hibrídos de Eucalyptus grandis W. Hill ex Maiden X Eucalyptus urophylla S. T. Blake

Foram estudados dois clones de Eucalyptus com densidades basicas de 447 e 552 kg/m³. O processo kraft foi utilizado para a producao de celulose, tendo sido aplicadas diferentes cargas de alcali para se obterem polpas com numero kappa 18 ± 0,5. As polpas foram branqueadas pela sequencia ODEopDD, a alvuras de 90 ± 1% ISO, e refinadas, sendo suas propriedades fisico-mecânicas e opticas analisadas. A madeira de baixa densidade mostrou-se mais recomendavel para a producao de celulose, por ter apresentado maior rendimento depurado, viscosidade da polpa mais elevada, ter requerido menor carga de alcali no cozimento, ter proporcionado menor teor de solidos no licor residual e menor consumo de reagentes quimicos no branqueamento. As propriedades mecânicas e estruturais das polpas nao foram afetadas significativamente pela densidade basica das madeiras.

A importância relativa da densidade da madeira e do teor de carboidratos no rendimento de polpa e na qualidade do produto.

The purpose of this study was to evaluate basic density, chemical composition and fiber dimensions of ten Eucalyptus sp wood samples and to verify the impact of this set of parameters and their combination on the Kraft pulping process yield and on bleached pulp quality. Ten eucalypt woods of different species, with basic densities varying from 365 to 544 kg/m³ and total wood carbohydrate contents varying from 70.0 to 74.5%, were transformed into kraft pulp of kappa number 15,5-16,7 and bleached to 90% ISO brightness by the sequence OD(PO)D. Wood basic density showed stronger correlations with fiber dimensions and pulp quality than did chemical composition. However, pulping yield was strongly affected by chemical composition. Lighter woods resulted in higher pulping yields. However, wood specific consumption was lower for denser woods, even though these demanded more drastic pulping conditions to achieve a given kappa number. The pulp quality results suggest that lower density woods should be directed towards fabrication of refined paper (printing and writing grades) while the denser woods should be directed to the sanitary papers segment (tissue grades).

Comparative study on the chemical composition of lipophilic fractions from three wood tissues of Eucalyptus species by gas chromatography-mass spectrometry analysis

Abstract The chemical compositions of lipophilic fractions from Eucalyptus urograndis and Eucalyptus urophylla cultivated in Brazil and Eucalyptus camaldulensis from Mexico were determined by gas chromatography-mass spectrometry (GC-MS) before and after alkaline hydrolysis followed by derivatization. In all fractions, fatty acids (including small amounts of α-and ω-hydroxy fatty acids) and sterols were the most abundant components followed by smaller amounts of long-chain aliphatic alcohols, phenolic acids, and hydrocarbons. The presence of steroid esters and triacylglycerols in all three species was indirectly confirmed by the increased amount of fatty acids and sterols (manly β-sitosterol) in the hydrolyzed fractions compared with the corresponding nonhydrolyzed fractions. The amount of liphophilic compounds (mainly fatty acids and sterols) identified in hydrolyzed fractions of E. urograndis, E. camaldulensis, and E. urophylla corresponded to 1921, 1915, and 634 mg kg−1 of dry matter, respectively. The lower abundance of fatty acids and sterols in the fractions from E. urophylla indicates that problems related to pitch formation will be less severe for this species than for the other two.

Behavior of Eucalyptus Wood Xylans across Kraft Cooking

Abstract The 4-O-methylglucuronoxylans isolated from wood, pulp, and black liquor from six eucalyptus wood species were characterized. The 1H nuclear magnetic resonance (NMR) studies revealed that all eucalyptus wood xylans contain O-2-substituted 4-O-methylglucuronic acid (MeGlcA) groups with hexose residues (9–26%). Their molecular weight (Mw) and polydispersity varied in the range of 26,083–28,405 g.mol−1 and 1.13–1.17, respectively. The xylan retention during pulping increased with increasing degree of MeGlcA substitution in the xylose ring. An average of 54% xylans was retained in the pulp and the remaining 46% were degraded and/or dissolved in the black liquor (39% degraded and 7% dissolved). The average Mw of the xylans retained in the pulp and dissolved in the black liquor is influenced by pulp kappa number and averaged 20,134 and 14,778 g.mol−1, respectively, at kappa 17. The average substitution degree of uronic acids, including MeGlcA and hexenuronic acids (HexA) in the xylans isolated from pulps (kappa 17) and black liquors were 1.05 and 1.13/10 xyloses, respectively. Of the total uronic acids present in the six original woods, an average of 36% w/w was retained in the pulps.

TCF bleaching sequence in kraft pulping of olive tree pruning residues.

The aim of the present work was to find a suitable Kraft cooking process for olive tree pruning (OTP), in order to produce pulp of kappa number about 17. The Kraft pulp produced under optimized conditions showed a viscosity of 31.5 mPa·s and good physical, mechanical, and optical properties, which are suitable for paper production. The physical-mechanical and optical properties were measured before and after bleaching. Although the OTP pulp was bleached to 90.9% ISO brightness (kappa<1), the process demanded a long sequence of stages, OZQPOZQPO. The bleached pulp showed a brightness reversion equal to 1.3%. Furthermore, this bleached pulp did not need a high intensity of beating due to high drainability degree in the unbeaten pulp. So that, OTP is suggested as an interesting raw material for cellulosic pulp production because its properties are comparable to those of other agricultural residues, currently used in the paper industry.

Clones de Eucalyptus versus a produção de polpa celulósica.

The wood quality is defined by combining several intrinsic characteristics of the tree to its use. This research aimed to evaluate some of the wood characteristics of Eucalyptus clones and its performance in kraft pulping. Fifteen clones, 5.8 years-old were used, two trees from each clone, totaling thirty trees. The evaluated wood characteristics were: basic density, fiber dimensions (fiber length, wall thickness, lumen diameter) and chemical composition (cellulose, lignin, hemicelluloses, extractives and ash contents). Four samples were cooked at the laboratory for each tree, using different active alkali, to establish the delignification curve. These alkali loads were selected after exploratory cooking to obtain an eighteen kappa number at the medium point of the curve. In the cooking were appraised the screened, the pulp viscosity and consumed alkali. The yield results varied from 43.4 to 52.0%, the active alkali from 17.5 to 23.4%, the consumed alkali from 15.5 to 20.0% and the pulp viscosity from 19.9 to 61.4 cP.

Caracterização tecnológica da madeira de Eucalyptus benthamii para produção de celulose kraft

The purpose of this study was to evaluate the quality of Eucalyptus benthamii wood for kraft pulp production. A hybrid of Eucalyptus urophylla x Eucalyptus grandis , probably the most planted Eucalyptus clone in Brazil, was also analyzed for comparison purposes. Basic density, chemical composition and fiber dimensions were determined for the two species. The Eucalyptus benthamii wood presented an anatomical structure, basic density and fiber dimensions quite similar to those of other species planted by the Brazilian pulp industry. However, it presented poorer wood quality characteristics when compared to the hybrid urograndis species, with higher amounts of extractives and lignin, lower amount of glucans, more galactans and lower S/G ratio, characteristics leading to lower pulping yield. Additional studies should be carried out to establish its pulping, bleaching and paper strength properties.

Estratégia de análise da qualidade de madeira de Eucalyptus sp. para produção de celulose

A new laboratory technique was tested to determine Eucalyptus sp. wood quality for kraft pulp production. This technique consists in performing four cooks simultaneously using different active alkali charges to establish the wood delignification characteristics. Based on regression equation it is possible to determine the alkali charge necessary to obtain a desired kappa number and the yield, viscosity and the alkali consumed for the target kappa. Statistical analysis demonstrated that a set of four cooks without replication is sufficient to determine the wood quality characteristics.