oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2020 ( 4 )

2019 ( 18 )

2018 ( 79 )

2017 ( 69 )

Custom range...

Search Results: 1 - 10 of 2020 matches for " wood pulping "
All listed articles are free for downloading (OA Articles)
Page 1 /2020
Display every page Item
Análise de critérios de qualidade da madeira de eucalipto para produ??o de celulose kraft
Gomide, Jose Livio;Fantuzzi Neto, Humberto;Regazzi, Adair José;
Revista árvore , 2010, DOI: 10.1590/S0100-67622010000200017
Abstract: 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.
Estimating pure diffusion contributions in alkaline pulping processes
Costanza,Vicente; Costanza,Pedro;
Latin American applied research , 2002,
Abstract: a model that predicts isothermal alkali diffusion and reaction with acetyl groups in moist wood chips was derived and approximated. system parameters were estimated from unsteady-state experimental data. simulation results reinforce the idea that the diffusion effect is not fully exploited in pulping processes. traditionally, digestion is conducted at high temperature, where delignification reaction kinetics is enhanced and the reaction effect is predominant. this approach is being reviewed by modern industry since energy and environmental savings associated with low temperature operation might compensate for high-yield productivity. the concentration of alkali at the center of the chip is a measure of the completeness of wood deacetylation, which translates into the aptitude of the final product for pulping purposes. this concentration is predicted here from the solution to a pair of coupled ode's. since alternatives combining both low and high-temperature processes are being studied, the results in this paper provide basic data for optimization analysis.
Estimating pure diffusion contributions in alkaline pulping processes
Vicente Costanza,Pedro Costanza
Latin American applied research , 2002,
Abstract: A model that predicts isothermal alkali diffusion and reaction with acetyl groups in moist wood chips was derived and approximated. System parameters were estimated from unsteady-state experimental data. Simulation results reinforce the idea that the diffusion effect is not fully exploited in pulping processes. Traditionally, digestion is conducted at high temperature, where delignification reaction kinetics is enhanced and the reaction effect is predominant. This approach is being reviewed by modern industry since energy and environmental savings associated with low temperature operation might compensate for high-yield productivity. The concentration of alkali at the center of the chip is a measure of the completeness of wood deacetylation, which translates into the aptitude of the final product for pulping purposes. This concentration is predicted here from the solution to a pair of coupled ODE's. Since alternatives combining both low and high-temperature processes are being studied, the results in this paper provide basic data for optimization analysis.
Chemical composition of Schinus molle L. wood and kraft pulping process
Mejía-Díaz, L. A.;Rutiaga-Qui?ones, J. G.;
Revista mexicana de ingeniería química , 2008,
Abstract: the determination of the chemical composition of the wood is fundamental in the proposition of its most appropriate uses, as in the case of suggesting the wood for the pulping process kraft. the purpose of this work consisted in determining the basic chemical composition of schinus molle l. wood and to carry out cooking kraft to evaluate the yield and the kappa number. the tree of s. molle belongs to the family anacardinaceae, which is broadly established in mexico. the chemical analysis included the determination of ph, ash content, solubility in organic solvents, quantity of lignin and holocellulose. to evaluate the pulp yield and kappa number, a factorial experimental design 2x2x2 was applied, having as factors and levels the following ones: temperature (160, 165 °c), charge of chemical reagents (16, 18%), cooking time (90, 100 min). finally, based on the results of this work the possible use of this wood for the kraft pulping process is proposed.
MILD ALKALINE TREATMENT ACTIVATES SPRUCE WOOD FOR ENZYMATIC PROCESSING: A POSSIBLE STAGE IN BIO-REFINERY PROCESSES
Yan Wang,Mikael E. Lindstrom,Gunnar Henriksson
BioResources , 2011,
Abstract: The structure of wood is so compact that enzymes are too large to penetrate into the structure and thereby attack the wood components for modifications that can be valuable for various purposes. Here we present a pretreatment method based on traditional kraft pulping, which opens the wood structure, so that enzymes are able to attack the wood components. To study this kind of chemical pretreatment, spruce wood samples were treated at similar conditions used in kraft cooking at varying intensities (H-factors). To verify if the structure was “opened” for enzymes, the pretreated wood samples were incubated with a cellulolytic culture filtrate, and the released reducing sugar concentration after the enzymatic hydrolysis was measured. The results indicated that un-pretreated wood fibers could not be attacked by the enzymes, but already relatively mild pretreatment was sufficient for letting the culture filtrate attack wood polysaccharides, and more intensive treatments opened the structure further. The mildest treatments did not cause any significant yield losses of lignin (Klason lignin). Some galactogluco-mannans were however lost during the pretreatments. The mechanisms behind the effect and the technical significance of the method are discussed.
APPLICATION OF SURFACTANTS AS PULPING ADDITIVES IN SODA PULPING OF BAGASSE
Yahya Hamzeh,Ali Abyaz,Mahsa O-Sadat Mirfatahi Niaraki,Ali Abdulkhani
BioResources , 2009,
Abstract: The effects of several non-ionic commercial surfactants and their dosage on soda pulping and ECF bleaching of soda and soda-surfactant pulps of bagasse were investigated. The properties of bleachable pulps obtained with conventional soda and with soda-surfactants were studied and compared. The results showed application of surfactants during the soda pulping of bagasse decreased kappa number and improved the yield and brightness of resulting pulp. Using the surfactants reduced alkali consumption during pulping. The bleaching experiments showed that the pulps obtained with the three types of applied surfactants namely, ELA-2, FAE-20, and PEG1000 could be easily bleached with D0ED1 or D0EpD1 sequences. The addition of most used surfactants in soda pulping of bagasse led to higher brightness in comparison to reference pulp with the same bleaching sequence. Strength properties of bleached pulps obtained with surfactants were higher than the pulp obtained with conventional soda pulping.
Papermaking fibers from giant reed (Arundo donax L.) by advanced ecologically friendly pulping and bleaching technologies
Shatalov, A. A.,Pereira, H.
BioResources , 2006,
Abstract: The anatomical structure and chemical composition of the stem-wall material of giant reed is considered from the viewpoint of raw material characterization for industrial fiber production. The effect of stem morphology (nodes and internodes) on pulping results and general pulp properties is discussed. The advantages of application of modern organic solvent based (organosolv) pulping technologies to giant reed are shown in comparison with the conventional (kraft) method. The conditions optimization for Ethanol-Alkali pulping (a selected organosolv pulping process) is given, and the chemical kinetics of the principal macromolecular components during ethanol-alkali pulping is described. The bleachability of organosolv pulps by short totally chlorine free (TCF) bleaching sequences using hydrogen peroxide and ozone as the active bleaching chemicals without pulp pre-delignification is examined and compared with kraft pulps. The enzymatic pre-treatment of reed organosolv pulps by commercial xylanase preparation is considered as a possibility toward the improvement of pulp bleachability.
Tratamientos aplicables para la reducción de la DQO recalcitrantede efluentes de pulpados quimimecánicos y semiquímicos(revisión)
Area,María C; Ojeda,Sergio A; Barboza,Olga M; Bengoechea,Dora I; Felissia,Fernando E.;
Revista de ciencia y tecnolog?-a , 2010,
Abstract: semichemical and chemimechanical pulping processes, due to their high yield, do not have efficient recovery systems based on combustion of dissolved organic matter. the substances discharged with the effluent of a pulp plant vary depending on the process, but generally are colored materials, materials which could be easy and difficult to biodegrade, and toxic materials. after the biological treatment of the effluent, certain amount of organic matter which is difficult to degrade remains, known as recalcitrant, and measured as chemical oxygen demand (cod). there are different methods for the elimination or degradation of these substances, as physico-chemical treatment, conventional biological treatments also with fungi, and integrated treatment processes. this paper presents a review of these methods, related to their efficiency in removing the cod of the effluent.
Effect of Optical Brightening Agent (OBA) on Bleaching Process on Paper of Eucalyptus Kraft Pulp  [PDF]
Bianca Moreira Barbosa, Fernando Gomes, Jorge Colodette, Danila Carvalho, Mauro Manfredi
Natural Resources (NR) , 2013, DOI: 10.4236/nr.2013.45046
Abstract:

In integrated factories of pulp and paper, the bleaching control is made by kappa number and/or brightness. However, the product paper is evaluated and valued for its whiteness. The level of final brightness of pulp certainly affects the demand for optical brighteners in paper manufacturing, nevertheless, there is not a direct correlation between consumption of optical brightener and final brightness, being the method of bleaching pulp, especially from the final stage of bleaching, also important in relation to this demand. Therefore, this study aimed to evaluate the potential of using the parameter whiteness as a tool to control bleaching pulp, instead of the traditional brightness and evaluate the impacts of different methods of bleaching and the pulp final brightness level in action of optical brighteners, to improve their performance. It was observed that the whiteness and brightness of the pulp are highly correlated and that the control of the bleaching plant can be done by any one of these two parameters. It was also concluded that, considering current prices of bleaching reagents and of optical brighteners, it is better to bleach the pulp up to lower brightness values (e.g. 88% ISO) and use larger amounts of optical brighteners to brighten the mass until the whiteness of 130 CIE. This conclusion is valid for whiteness measured before the size press. Further studies are needed to validate this conclusion considering the finished product.

Effects of Ethanol Addition and Biological Pretreatment on Soda Pulping of Eulaliopsis binata  [PDF]
Archana Gautam, Amit Kumar, Dharm Dutt
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2016, DOI: 10.4236/jbnb.2016.72010
Abstract: Morphological characteristics and proximate chemical analysis of E. binata showed it as a suitable raw material for writing and printing grade paper. Maximum pulp yield (43.58%) of kappa number 17.38 with 0.9% screening rejects was obtained at 12% of active alkali (as Na2O) pulping temperature 130°C, cooking time 120 min and solid to liquor ratio 1:4. During bio-soda pulping of E. binata, pulp yield decreased slightly while pulp brightness, tensile index, burst index and double fold numbers were improved by 4.1%, 24.94%, 14.03% and 48.45% respectively compared to soda pulping. During ethanol-soda pulping of E. binata, pulp yield, pulp brightness, tensile index, burst index and double fold numbers were improved by 3.9%, 6.6%, 32.18%, 35.40% and 77.31% respectively compared to soda pulping.
Page 1 /2020
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.