Prebleaching of eucalypt kraft pulp with OP stages: Effect of an acid pretreatment or chelation step

TAPPI Journal ◽  
2012 ◽  
Vol 11 (6) ◽  
pp. 31-38
Author(s):  
TATIANA M. PÓVOAS ◽  
DINA A.G. ANGÉLICO ◽  
ANA P.V. EGAS ◽  
PEDRO E.G. LOUREIRO ◽  
LICÍNIO M. GANDO-FERREIRA ◽  
...  
Keyword(s):  
Eucalyptus Globulus ◽  
Comparative Evaluation ◽  
Kraft Pulp ◽  
Kraft Pulps ◽  
Acid Pretreatment ◽  
High Brightness ◽  
Pulp Viscosity ◽  
Brightness Reversion

We conducted a comparative evaluation of different treatments for the bleaching of eucalypt kraft pulps beginning with OP stages. The treatments tested were (1) an acid chelation stage with DTPA (OQP sequence); (2) a hot acid stage (AOP sequence); and (3) a chelant addition into the alkaline oxygen stage ((OQ)P and A(OQ)P sequences). The latter strategy was also studied for environmental reasons, as it contributes to the closure of the filtrate cycle. The OQP sequence leads to the highest brightness gain and pulp viscosity and the lowest peroxide consumption caused by an efficient metals control. Considering that the low biodegradability of the chelant is a problem, the A(OQ)P sequence is an interesting option because it leads to reduced peroxide consumption (excluding OQP) while still reaching high brightness values and similar brightness reversion to OQP prebleaching, with only a viscosity loss of 160 dm3/kg. Therefore, a hot acid stage could be considered when a separate acid Q stage is absent in a prebleaching sequence of Eucalyptus globulus kraft pulps involving OP stages.

Effect of lignin content and magnesium-to-manganese ratio on the selectivity of oxygen delignification in softwood kraft pulp

2001 ◽  
Vol 73 (12) ◽  
pp. 2059-2065
Author(s):  
Lucian A. Lucia ◽  
Rachel S. Smereck
Keyword(s):  
Chemical Process ◽  
Kraft Pulp ◽  
Lignin Content ◽  
Dry Mass ◽  
The Other ◽  
Kraft Pulps ◽  
Oxygen Delignification ◽  
Pulp Viscosity ◽  
Softwood Kraft Pulp ◽  
Temperature Time

A series of oxygen delignification experiments were performed on two softwood kraft pulps that had differing starting lignin contents. One had an initial kappa of 40 and the other 25, corresponding to lignin contents of 6% and 3.75% by dry mass, respectively. Several chemical process modifications were examined to determine their influence over the delignification selectivity and final pulp viscosity. A 2k factorial format was used to assess the significance of varying the temperature, time, and Mg/Mn ratio during the oxygen delignification of the pulps. It was found that the lower lignin content pulp displayed greater delignification selectivity than the higher lignin content pulp. Kappa numbers, viscosity values, and ICP metals contents were determined and are the basis of discussion for the results obtained.

scholarly journals EFFECT OF ADDITION OF DEINKED PULP TO BLEACHED KRAFT PULP ON TISSUE PAPER PROPERTIES

Wood Research ◽  
2021 ◽  
Vol 66 (3) ◽  
pp. 505-516
Author(s):  
Monika Stankovská ◽  
Mária Fišerová ◽  
Juraj Gigac ◽  
Elena Opálená
Keyword(s):  
Water Absorption ◽  
Kraft Pulp ◽  
Kraft Pulps ◽  
Initial Water ◽  
Paper Properties ◽  
High Brightness ◽  
Tissue Paper ◽  
Tensile Index ◽  
Bleached Kraft Pulp ◽  
Eucalyptus Kraft Pulp

The influence of addition of deinked pulps with low and high brightness to bleached eucalyptus and pine kraft pulps on functional tissue paper properties was studied. Deinked pulps with low and high brightness had some different functional properties. Deinked pulp with high brightness has higher bulk, porosity, water absorption after immersion, initial water absorption, bulk softness as well as brightness. On the contrary, the difference in relative bonded area and porosity e between deinked pulps with low and high brightness was moderate. The mixed pulps laboratory pulp sheets from bleached eucalyptus kraft pulp or bleached pine kraft pulp with addition of 20, 40 and 80% of deinked pulp with low brightness or deinked pulp with high brightness were prepared. The addition of the deinked pulp with high or low brightness to bleached kraft pulp leads to increasing of bulk, bulk softness as well as high water absorption after immersion and initial water absorption. The tensile index rapidly decreased by the addition of deinked pulps with high brightness to bleached eucalyptus and pine kraft pulps. Similarly, the addition of deinked pulp with low brightness to bleached pine kraft pulp led to rapid decreasing of tensile index. On contrary, with the addition of deinked pulp with low brightness to eucalyptus kraft pulp, the decreasing of tensile index was less pronounced. Mixed pulp from bleached eucalyptus kraft pulp with a small content of deinked pulp with low brightness with functional properties suitable for production of tissue papers was found as optimal.

Optimization of elemental chlorine-free bleaching for a softwood kraft pulp • part 2: economic analysis of chemical and steam consumption

TAPPI Journal ◽  
2010 ◽  
Vol 9 (9) ◽  
pp. 47-53 ◽  
Author(s):  
BRIAN N. BROGDON
Keyword(s):  
Chlorine Dioxide ◽  
Previous Investigation ◽  
Kraft Pulp ◽  
Energy Costs ◽  
Alkaline Extraction ◽  
Stage Versus ◽  
Kraft Pulps ◽  
Steam Consumption ◽  
Elemental Chlorine ◽  
Softwood Kraft Pulp

Our previous investigation [1] re-analyzed the data from Basta and co-workers (1992 TAPPI Pulping Conference) to demonstrate how oxidative alkaline extraction can be augmented and how these changes affect chlorine dioxide consumption with elemental chlorine-free (ECF) sequences. The current study manipulates extraction delignification variables to curtail bleaching costs with a conventional U.S. Southern softwood kraft pulp. The economic advantages of ~0.35% to 0.65% H2O2 peroxide reinforcement in a 70°C (EOP)-stage versus 90°C (EO)-stage are predisposed to the brightness targets, to short or long bleach sequences, and to mill energy costs. Minimized bleaching costs are generally realized when a 90°C (EO) is employed in D0(EO)D1 bleaching, whereas a 70°C (EOP) is economically advantageous for D0(EOP)D1E2D2 bleaching. The findings we disclose here help to clarify previous ECF optimization studies of conventional softwood kraft pulps.

Kraft pulp of high brightness without chlorination

1991 ◽  
Vol 6 (4) ◽  
pp. 151-160a
Author(s):  
Per Larsson ◽  
Olof Sarnuelson
Keyword(s):  
Kraft Pulp ◽  
High Brightness

scholarly journals Cellulose Nanofibril (CNF) Films and Xylan from Hot Water Extracted Birch Kraft Pulps

2019 ◽  
Vol 9 (16) ◽  
pp. 3436 ◽  
Author(s):  
Marc Borrega ◽  
Hannes Orelma
Keyword(s):  
Food Packaging ◽  
Kraft Pulp ◽  
Barrier Properties ◽  
Hot Water ◽  
Kraft Pulps ◽  
Cellulose Nanofibril ◽  
Vapour Permeability ◽  
Transparent Films ◽  
Cnf Films ◽  
Birch Kraft Pulp

The effects of xylan extraction from birch kraft pulp on the manufacture and properties of cellulose nanofibril (CNF) films were here investigated. Hot water extractions of bleached and unbleached kraft pulps were performed in a flow-through system to remove and recover the xylan. After the extraction, the pulps were oxidized with 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) and fibrillated in a high-pressure microfluidizer. Compared to CNF from bleached kraft pulp, the CNF dispersions obtained from water-extracted pulps were less viscous and generally contained a higher amount of microfiber fragments, although smaller in size. In all cases, however, smooth and highly transparent films were produced from the CNF dispersions after the addition of sorbitol as plasticizer. The CNF films made from water-extracted pulps showed a lower tensile strength and ductility, probably due to their lower xylan content, but the stiffness was only reduced by the presence of lignin. Interestingly, the CNF films from water-extracted bleached pulps were less hydrophilic, and their water vapour permeability was reduced up to 25%. Therefore, hot water extraction of bleached birch kraft pulp could be used to produce CNF films with improved barrier properties for food packaging, while obtaining a high-purity xylan stream for other high-value applications.

Genetic control of kraft pulp yield in Eucalyptus globulus

2010 ◽  
Vol 40 (5) ◽  
pp. 917-927 ◽  
Author(s):  
Desmond J. Stackpole ◽  
René E. Vaillancourt ◽  
Geoffrey M. Downes ◽  
Christopher E. Harwood ◽  
Brad M. Potts
Keyword(s):  
Genetic Control ◽  
Eucalyptus Globulus ◽  
Kraft Pulp ◽  
Near Infrared ◽  
Genetic Correlations ◽  
Basic Density ◽  
Pulp Yield ◽  
Narrow Sense Heritability ◽  
Selection Gradients ◽  
Economic Worth

Pulp yield is an important breeding objective for Eucalyptus globulus Labill., but evaluation of its genetic control and genetic correlations with other traits has been limited by its high assessment cost. We used near infrared spectroscopy to study genetic variation in pulp yield and other traits in a 16-year-old E. globulus trial. Pulp yield was predicted for 2165 trees from 467 open-pollinated families from 17 geographic subraces. Significant differences between subraces and between families within subraces were detected for all traits. The high pulp yield of southern Tasmanian subraces suggested that their economic worth was previously underestimated. The narrow-sense heritability of pulp yield was medium (0.40). The significant positive genetic correlation between pulp yield and diameter (0.52) was at odds with the generally neutral values reported. The average of the reported genetic correlations between pulp yield and basic density (0.50) was also at odds with our nonsignificant estimate. Pulp yield of the subraces increased with increasing latitude, producing a negative correlation with density (–0.58). The absence of genetic correlations within subraces between pulp yield and density suggests that the correlation may be an independent response of the two traits to the same or different selection gradients that vary with latitude.

Analytical pyrolysis study of biodelignification of cloned Eucalyptus globulus (EG) clone and Pinus pinaster Aiton kraft pulp and residual lignins

2009 ◽  
Vol 85 (1-2) ◽  
pp. 19-29 ◽  
Author(s):  
Atika Oudia ◽  
Erika Mészáros ◽  
Emma Jakab ◽  
Rogério Simões ◽  
João Queiroz ◽  
...  
Keyword(s):  
Eucalyptus Globulus ◽  
Pinus Pinaster ◽  
Kraft Pulp ◽  
Analytical Pyrolysis ◽  
Pyrolysis Study

scholarly journals Chemical characteristics and Kraft pulping of tension wood from Eucalyptus globulus labill

2012 ◽  
Vol 36 (6) ◽  
pp. 1163-1172 ◽  
Author(s):  
María Graciela Aguayo ◽  
Regis Teixeira Mendonça ◽  
Paulina Martínez ◽  
Jaime Rodríguez ◽  
Miguel Pereira
Keyword(s):  
Eucalyptus Globulus ◽  
Lignin Content ◽  
Strength Properties ◽  
Kraft Pulping ◽  
Pulp Yield ◽  
Chemical Characteristics ◽  
Kraft Pulps ◽  
Opposite Wood ◽  
Alkali Consumption ◽  
Pulp Strength

Tension (TW) and opposite wood (OW) of Eucalyptus globulus trees were analyzed for its chemical characteristics and Kraft pulp production. Lignin content was 16% lower and contained 32% more syringyl units in TW than in OW. The increase in syringyl units favoured the formation of β-O-4 bonds that was also higher in TW than in OW (84% vs. 64%, respectively). The effect of these wood features was evaluated in the production of Kraft pulps from both types of wood. At kappa number 16, Kraft pulps obtained from TW demanded less active alkali in delignification and presented slightly higher or similar pulp yield than pulps made with OW. Fiber length, coarseness and intrinsic viscosity were also higher in tension than in opposite pulps. When pulps where refined to 30°SR, TW pulps needed 18% more revolutions in the PFI mill to achieve the same beating degree than OW pulps. Strength properties (tensile, tear and burst indexes) were slightly higher or similar in tension as compared with opposite wood pulps. After an OD0(EO)D1 bleaching sequence, both pulps achieved up to 89% ISO brightness. Bleached pulps from TW presented higher viscosity and low amount of hexenuronic acids than pulps from OW. Results showed that TW presented high xylans and low lignin content that caused a decrease in alkali consumption, increase pulp strength properties and similar bleaching performance as compared with pulps from OW.

Reactions of aromatic structures in brightness reversion of fully-bleached eucalyptus kraft pulps

Holzforschung ◽  
2009 ◽  
Vol 63 (3) ◽  
Author(s):  
Anna-Stiina Jääskeläinen ◽  
Katri Toikka ◽  
Anni Lähdetie ◽  
Tiina Liitiä ◽  
Tapani Vuorinen
Keyword(s):  
Resonance Raman ◽  
Kraft Pulps ◽  
Brightness Reversion ◽  
Vis Spectroscopy ◽  
Uv Resonance Raman ◽  
Hexenuronic Acid

Abstract The role of aromatic structures in brightness reversion of fully bleached pulps was studied by UV resonance Raman (UVRR) and reflectance UV-Vis spectroscopy. The results clearly showed that ageing increased the aromatic band at approximately 1600 cm-1 in the UVRR spectra and the lignin band at approximately 280 nm in the UV-Vis spectra. This increase was probably due to increased conjugation of lignin and it was observed for all pulps regardless of the bleaching sequence. In addition to these lignin reactions, other unsaturated structures, such as hexenuronic acid groups, reacted during ageing.

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