Jorge Luiz Colodette

Effect of extractives on wood color of heat treated Pinus radiata and Eucalyptus pellita

Heat treatment can change wood color without any use of environmentally harmful chemicals, and the efficiency of this process depends on the raw material to be treated. The objective of this study was to evaluate the influence of extractives on the color change of Eucalyptus pellita and Pinus radiata wood during heat treatment. The extractives were extracted in cold water and in dichloromethane as well as totally removed and the wood was treated at 170°C and 200°C for three hours under atmospheric pressure and in presence of air for evaluating the lightness (L*), green-red coordinate (a*), blue-yellow coordinate (b*), color saturation (C) and tonality angle (H) values. Pinus radiata wood was more resistant to discoloration by heat treatment. The removal of total and cold water-soluble extractives before heat treatment changed the L* value of Pinus radiata, a* value of Eucalyptus pellita, and b*, C, and H values of both species. Removal of extractives soluble in dichloromethane did not affect the color of heat treated wood. Thus, understanding the influence of extractives on heat treated wood can allow adapting the raw material to the process for enhancing the applicability of heat treatment for changing wood color.

Avaliação da madeira e da polpação kraft em clones de eucaliptos

Low cost and high quality cellulose production demands appropriate wood. The selection of superior clones has been done based on some criteria as basic density, gravimetric yield of pulping and wood chemical composition, especially of cellulose, hemicelluloses, extractive and lignin contents. This study aimed at evaluating the characteristics of the Eucalyptus wood, by destructive methods, and the Kraft pulping production in six clones. Five 3-year-old trees of s each clone, planted in a spacing of 3.0 x 3.3 m, were sampled in Cocais, Guanhaes, Rio Doce and Santa Barbara, in Minas Gerais State, Brazil. The basic density was measured in disks collected at 1.3 m from the ground (DBH) and in whole tree chips (composed sample). The chemical composition was measured in sawdust samples, taken from DBH. The pulping was carried out from whole tree chips. It was verified that the density measured in DBH was slightly superior to that measured in the whole tree chips. The general wood chemical composition was very much affected by the planting site and type of clone. Mountain sites produce wood with higher contents of cellulose and lower contents of hemicelluloses. The F clone wood from Santa Barbara and Cocais presented lower qualities in relation to the other studied clones. The bests kraft pulping yields were achieved from the the clone B from Guanhaes and Santa Barbara.RESUMO ‐ A producao de celulose de baixo custo e alta qualidade requer madeira adequada e bem selecionada. A selecao de clones superiores tem sido realizada com base em criterios como densidade basica, rendimento gravimetrico da polpacao e composicao quimica da madeira, especialmente de celulose, hemiceluloses, extrativos e ligninas. O objetivo deste trabalho foi avaliar as caracteristicas da madeira de Eucalyptus, por metodo destrutivo, e a producao de polpa celulosica kraft em seis clones. Utilizaram-se cinco arvores de cada clone, aos 3 anos de idade, plantadas em espacamento 3,0 m x 3,3 m, nas regioes de Cocais, Guanhaes, Rio Doce e Santa Barbara, Estado de Minas Gerais. A densidade basica foi medida em discos extraidos a 1,3 m de altura do solo (DAP) e em cavacos da arvore inteira (amostra composta). A composicao quimica foi medida em amostras de serragem, retiradas no DAP. Os cozimentos foram efetuados a partir de cavacos da arvore inteira. Verificou-se que a densidade medida no DAP foi ligeiramente superior a medida nos cavacos da arvore toda. A composicao quimica geral da madeira foi muito influenciada pelo tipo de clone, local de plantio e interacao. Locais mais montanhosos produziram madeira com maior teor de celulose e menor de hemicelulose. A madeira do clone F da regiao de Santa Barbara e Cocais apresentaram madeiras de qualidade inferior para producao de polpa celulosica. Os melhores rendimentos de polpacao kraft foram alcancados com o clone B nas regioes de Guanhaes e Santa Barbara. Palavras-chave: Celulose, madeira e Eucalyptus. WOOD EVALUATION AND KRAFT PULPING IN EUCALYPTS CLONES

Enhancement of eucalypt pulp yield through extended impregnation cooking

Abstract The improvement caused by eucalypt chip impregnation on kraft pulping performance was assessed for terminating the cook at kappa in the range of 15–27 and at controlled residual effective alkali (REA) of 6–8 g/L NaOH. Extended impregnation cooking of eucalypt chips (EIC) increased about 1 % lignin- and HexA-free screen yield gains in relation to conventional cooking (CC), regardless of kappa number in the range of 15–27. The EIC technology allows for cooking eucalypt wood to kappa number up to 27, without rejects production, but without significant improvement in lignin- and HexA-free screen yield and with larger chlorine dioxide (ClO2) consume during bleaching. The optimum kappa number for both CC and EIC cooking was about 19 with similar refinability and strength properties for both technologies, CC and EIC. It was concluded that extended impregnation cooking is an attractive technique for enhancing bleached eucalypt Kraft pulp yield.

NSSC pulping of fast growing trees

Abstract Neutral sulphite semichemical pulping (NSSC) of Schizolobium amazonicum (Paricá), a fast-growing Amazonian tree, was compared with that of Eucalyptus grandis (eucalypt), one of the most important wood sources for the Brazilian pulp industry, and with mixtures of both woods in different proportions (mix). Wood chips prepared from 7-year old trees were steamed, cooked using the NSSC process and defibered in a 12” disc refiner in three stages. The paricá wood produced pulp of lower yield (75 %) than eucalypt (77 %) at 16 % sulfite/150 min/170 °C. The paricá and eucalypt pulps were bleached to about 68 and 74 % ISO brightness, respectively, by the QPFAS sequence. Paricá consumed more energy for refining in comparison with the eucalypt wood. The wood mix produced lower yield and brightness than the single species processed separately.

Addition of corn fiber xylan to eucalyptus and pinus pulp and its effect on pulp bleachability and strength

Abstract Corn fibers are a significant residue of agriculture due to the huge amounts, which has fueled interest in a more rational use of its components, particularly regarding hemicelluloses. The impact of hemicellulose redeposition on printer and writing (P&W) paper grade pulp properties are discussed in this paper. Xylans extracted from corn fibers (16.9 % xylans) by cold caustic extraction (CCE) were added to commercial brown pulps (eucalypt and pine) in the oxygen delignification (O-stage) and further bleached to 90 % ISO brightness. Hemicelluloses deposition occurred at variable degree (up to 7 % on pulp weight). Pulp bleachability was not impaired by xylan deposition for eucalypt and pine pulps. Xylan deposition onto fibers was more efficient in eucalypt pulp than pine. Pulp beatability and strength properties were improved by xylan deposition for P&W paper grades.

The effect of reaction wood on bleached eucalypt kraft pulp production - Part I

Wood quality is the key element for the production of high-performance, high-bleachability cellulose pulp. The presence of reaction wood may have significant impact on its various applications. This study investigated the effect of reaction wood on the production of bleached eucalypt kraft pulp. Normal and reaction wood eucalypt chips were compared regarding their indepth chemical composition and kraft pulping. The Kraft pulps derived from normal and reaction wood were compared for bleachability, chemistry and quality. Reaction wood requires less effective alkali to reach a given delignification degree, but retains less yield in relation to normal wood. At the kappa number 18±0.5, the brown pulp derived from reaction wood contains less cellulose and hemicelluloses, more HexA and lower viscosity in relation to that of normal wood. Although the pulp derived from reaction wood showed slightly lower efficiency in the oxygen delignification stage it performed better across ECF bleaching, reaching a brightness 1% higher at fixed chemical charge. The final bleached pulp derived from reaction wood showed lower viscosity and higher brightness reversion in relation to normal wood. Thus, reaction wood chips can be used for production of bleached grade pulps without major concern, if combined in small fractions to normal wood. ADDRESSES OF THE AUTHORS: Walter Torezani Neto Boschetti (walterboschetti@gmail.com), Jorge Luiz Colodette (colodett@ufv.br), Ana Márcia Macedo L. Carvalho (ana.marcia@ufv.br), Robsnéia Adriana Ribeiro (adrianaribeiro_qui@yahoo.com.br), Diego Pierre de Almeida (adpdiego@yahoo.com.br), and Carolina Marangon Jardim (cmjardim@gmail.com), Federal University of Viçosa, Department of Forest Engineering, Viçosa, Brasil. Corresponding author: Walter Torezani N. Boschetti

Washing, bleaching and characterisation of eucalyptus pulp from ethanol pulping

The present study analyzed eucalyptus pulp produced by the ethanol-based organosolv process submitted to different bleaching strategies. Washing tests with ethanol and alkaline solution, cold caustic extraction (CCE), oxygen delignification and bleaching through Dhot(EP)DP bleaching sequence were performed. Different washing strategies were investigated. In washings with NaOH solution, different charges, times and temperatures were tested. The best result was obtained with NaOH charge of 40 kg/t, 3 min and 90°C, reducing the kappa number by 33 %. CCE of the brown stock resulted in a reduction of the kappa number by 29%. The highest kappa number reduction was reached by bleaching with the O/ODhot(EP)DP sequence. Delignification degree in the oxygen stage was 79.2%, indicating no need for prior treatments as ethanol or alkaline solution. The final bleached pulp had a brightness of 91.7% ISO, viscosity of 546 cm/g and low content of hemicelluloses.