12 results on '"Simões, Rogério"'
Search Results
2. Potential of Acacia melanoxylon for Pulping
- Author
-
Pereira, Helena, Simões, Rogério, Santos, António, Gominho, Jorge, Lourenço, Ana, and Anjos, Ofélia
- Subjects
fibres morphology ,kraft pulp ,papermaking potential ,Acacia melanoxylon ,pulp yield - Abstract
Most of the fibre raw materials used by the pulp and paper industry are from a small number of tree species. For instance, Eucalyptus and Pinus species are the major industrial pulpwood sources obtained from forests characterized by a relatively low biodiversity. The large monoculture areas also increase environmental risks such as those related to biotic attacks or forest fires. Diversification of industrial fibre sources has therefore been a matter of research and the characterization of different raw materials has been made in view of their pulping potential. Acacia melanoxylon R. Br. (blackwood) grows well in Portugal in pure or mixed stands with Pinus pinaster Aiton, and is valued as a timber species with potential for sawmills. In addition, the wood anatomical and chemical characteristics also allow to consider the species as an alternative raw material for the pulp industry. Acacia species, with their relatively short, flexible and collapsible fibres, have potential to produce papers with good trade-offs between light scattering/tensile strength and smoothness/tensile strength, at low energy consumption in refining. The pulping and paper making potential of blackwood has been studied by several authors showing an overall good pulping aptitude under the same experimental conditions of kraft pulping as used for eucalypt pulping with pulp yields ranging between 47 and 58 %. The presence of heartwood should be taken into account because it decreases the raw-material quality for pulping due to the higher extractives content. Heartwood proportion should therefore be considered as a quality variable when using A. melanoxylon wood in pulp industries. This chapter describes the characterization of the A. melanoxylon wood pulping performance, regarding yield and kappa number, and the pulp and paper properties. The application of fast spectroscopic technologies for pulp quality determination is also described. info:eu-repo/semantics/publishedVersion
- Published
- 2018
3. Papermaking potential of Acacia dealbata and Acacia melanoxylon
- Author
-
Santos, António J. A., Anjos, Ofélia M. S., Simões, Rogério, and uBibliorum
- Subjects
Acacia dealbata ,stomatognathic diseases ,Papermaking potential ,Eucalyptus globulus ,stomatognathic system ,Wood pulp ,Fibre flexibility ,Paper properties ,Kraft pulp ,Acacia melanoxylon - Abstract
The pulping and papermaking potential of Acacia dealbata and Acacia melanoxylon were studied using Eucalyptus globulus as a reference. Pulp yield, alkali consumption and delignification in the kraft process, of both species, compare very well with the reference. Pulp yield can be higher than that of E globulus and the residual lignin content lower after cooking, which is in good agreement with the lower lignin and extractives content of the wood samples used. Pulps produced from Acacia have slightly lower fibre length and coarseness and higher fibre width and wet fibre flexibility than E globulus pulps. As a consequence of fibre characteristics, the paper produced from Acacia is denser and exhibits higher tensile and burst strength, and lower tear resistance than that from E globulus, at a given PFI revolution. For the same sheet density E globulus displays higher strength properties, but the consequence of achieving this is a lower drainage rate and higher energy consumption in refining.
- Published
- 2006
4. The Potential of Hydrothermally Pretreated Industrial Barks From E. globulus as a Feedstock for Pulp Production.
- Author
-
Neiva, Duarte M., Gominho, Jorge, Fernandes, Luís, Lourenço, Ana, Chemetova, Catarina, Simões, Rogério M. S., and Pereira, Helena
- Subjects
HYDROTHERMAL deposits ,BARK ,EUCALYPTUS globulus ,FEEDSTOCK ,PULPING ,PAPER product manufacturing ,DELIGNIFICATION - Abstract
This study focused on the use of industrialeucalyptus globulusbark as an alternative fiber source for bleached pulp and paper production. Bark has high extractives and ash contents (7.7% and 3.5%, respectively) but a mild hydrothermal pretreatment was tested, decreasing its values to 2.8% and 2.4%, respectively. Untreated and pretreated bark were kraft pulped at 15% and 20% (as Na2O) active alkali conditions. The pretreatment improved delignification when using low active alkali; kappa number 25.4 vs 17.5, and shives 3.1% vs 0%, respectively, with untreated and pretreated bark. The pretreatment resulted in a lower chemical demand to obtain pulps with similar yield and kappa number. It was possible to produce bleached pulps with good handsheet optical, physical, and mechanical properties with slightly lower values than those of industrial eucalypt wood pulps; e.g., brightness > 85% vs 87%, tear index > 4.2 vs 5.6 mn.m2.g−1, tensile index > 62 vs 69 n.m.g−1for bark and wood pulps, respectively. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
5. Determination of sugar content in Pinus pinaster and its corresponding hollocellulose, cellulose and kraft pulps
- Author
-
Duarte, Ana Paula, Gaiolas, Carla Sofia Cardona Jorge, Belgacem, Mohamed Naceur, Simões, Rogério, and uBibliorum
- Subjects
Pinus pinaster ,Kraft pulp ,Sugar ,Polysaccharide ,Hollocellulose - Abstract
This paper deals with the study of the polysaccharide complex from Portuguese Pinus pinaster, as well as from its main components, i.e., holocellulose, cellulose and pulps obtained using different cooking conditions. Nordic Pinus sylvestris was also studied in order to compare it with Portuguese pine. Two methods were used: one consisted of the hydrolysis of polysaccharides with trifluoroacetic acid (TFA) and quantification of the amount of each sugar using High Performance Liquid Chromatography (HPLC). The latter approach used here consisted of the hydrolysis of the samples under scrutiny by sulphuric acid and converting it into alditols, which were then esterified before injecting to Gas Chromatography coupled with Mass Spectrometry. Myo-inositol was used as an internal standard. The results obtained by the two methods showed that the TFA procedure prevents monosaccharide degradation, comparatively with the sulphuric acid one. In fact, the overall sugar yield was found systematically higher than 93% for TFA hydrolysis, whereas that corresponding to H2SO4 treatment never exceeded 77%. The sugar composition of both pines was found very similar and the sulfidity level (from 10 to 55%) did not affect the pulp sugar composition. The glucose/mannose and xylose/arabinose ratios were found to be around 3.5 for both Portuguese and Nordic pines. Finally, kraft pulping of Pinus pinaster was found to affect drastically galactose, mannose and arabinose.
- Published
- 2003
6. Effect of carry-over on the kinetics of chlorine dioxide delignification of an unbleached hardwood kraft pulp
- Author
-
Simões, Rogério, Barroca, Maria J. M. C., Castro, José Almiro A. M., and uBibliorum
- Subjects
Kinetics ,Eucalyptus globulus ,Mathematical model ,stomatognathic system ,polycyclic compounds ,Bleaching ,Carry-over ,Hardwood pulp ,Kraft pulp - Abstract
This work is concerned with the kinetics of the prebleaching stage of a kraft pulp of Eucalyptus globulus with chlorine dioxide. Its main purpose is to discuss the influence of the degree of washing, expressed as the COD of the pulp, on the kinetics and stoichiometry of chlorine dioxide delignification. The effect of the carry-over on the rate of delignification of a Do stage was studied over time for pulps with different initial organic charges (COD). A set of experiments was specially designed to discriminate the individual role of lignin and of COD upon the initial consumption of chlorine dioxide. A modified mathematical model, taking into account the reactions of chlorine dioxide with both lignin and the carry-over, has been developed. In this model, the initial chlorine dioxide consumption (in the fast phase of reaction) is dependent on two factors: the carry-over of the pulp and the temperature of operation. However, the carry-over does not affect the corresponding initial depletion factor for the Kappa number. The role of the dissolved organic material, carried with the pulp, upon the rate of reaction in the slow period is better described in the stoichiometry. The fit of the experimental results obtained for pulps with different COD reveals good prediction capabilities for both Kappa number and chlorine dioxide concentration in a conventional D0 stage.
- Published
- 2002
7. Effect of unbleached pulp kappa number on the kinetics of chlorine dioxide delignification
- Author
-
Simões, Rogério, Barroca, Maria J. M. C., Castro, José Almiro A. M., and uBibliorum
- Subjects
Floor kappa number ,stomatognathic diseases ,Eucalyptus globulus ,Kinetics ,Mathematical model ,stomatognathic system ,Unbleached pulp kappa number ,Bleaching ,Kraft pulp ,Chlorine dioxide - Abstract
Chlorine dioxide delignification of different unbleached kraft pulps from Eucalyptus globulus, having Kappa numbers of 12 to 18, was studied in the temperature range of 285 K to 358 K. The effect of the unbleached pulp Kappa number on the initial fast phase of delignification was investigated with respect to the depletion factors for Kappa number and chlorine dioxide concentration, as proposed by Barroca et al. Furthermore, the behaviour of the floor lignin content of the pulp, or the floor Kappa number, was analysed within this range. The results show that all pulps exhibit a similar pattern, with respect to temperature, in depletion factors for Kappa number and chlorine dioxide concentration. The degree of normalised delignification and chlorine dioxide consumption is very similar and independent of the Kappa number of the unbleached pulps. Moreover, the results reveal that there is a strong correlation between the floor lignin content and the temperature, and that this correlation is applicable to a wide range of unbleached pulp Kappa numbers, since the residual Kappa number is independent of its initial value. The results enable the general application of a kinetic model to kraft pulps with different unbleached Kappa numbers.
- Published
- 2001
8. Prediction of Five Softwood Paper Properties from its Density using Support Vector Machine Regression Techniques.
- Author
-
García-Gonzalo, Esperanza, Santos, António J. A., Martínez-Torres, Javier, Pereira, Helena, Simões, Rogério, García-Nieto, Paulino José, and Anjos, Ofélia
- Subjects
SOFTWOOD ,PAPER industry ,SUPPORT vector machines ,REGRESSION analysis ,MECHANICAL behavior of materials ,OPTICAL properties - Abstract
Predicting paper properties based on a limited number of measured variables can be an important tool for the industry. Mathematical models were developed to predict mechanical and optical properties from the corresponding paper density for some softwood papers using support vector machine regression with the Radial Basis Function Kernel. A dataset of different properties of paper handsheets produced from pulps of pine (Pinus pinaster and P. sylvestris) and cypress species (Cupressus lusitanica, C. sempervirens, and C. arizonica) beaten at 1000, 4000, and 7000 revolutions was used. The results show that it is possible to obtain good models (with high coefficient of determination) with two variables: the numerical variable density and the categorical variable species. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
9. Potential and limitation of Trametes versicolor laccase on biodegradation of Eucalyptus globulus and Pinus pinaster kraft pulp
- Author
-
Oudia, Atika, Queiroz, João, and Simões, Rogério
- Subjects
- *
EUCALYPTUS , *CLUSTER pine , *LACCASE , *SULFATE pulping process - Abstract
Abstract: Two Eucalyptus globulus and one Pinus pinaster kraft pulps were submitted to laccase-mediator system (LMS) to evaluate the effect of the treatment on biodelignification and subsequently on hexenuronic acid content (HexA). As expected, the hexenuronic acid content of unbleached E. globulus kraft pulps is substantially higher than the corresponding values for unbleached P. pinaster pulp. Besides, the two unbleached E. globulus pulps revealed different HexA content, having an important effect the raw material. The amount of HexA is quite high in the unbleached clone E. globulus (64.1mmol/kg), while it is moderately high in the industrial E. globulus kraft pulps (52.1mmol/kg). These values represent between 29.1 and 38.5% of kappa number of these pulps. For unbleached P. pinaster kraft pulps, the contribution of hexenuronic acid to the pulp kappa number was considerably lower. The three unbleached pulps were submitted to an optimized laccase-violuric acid treatment and the results have shown that the delignification extent for hardwood and softwood were different, but also different for the same species. For E. globulus, it was observed that 49.3% of kappa number has reduced for the clone eucalypt, while 42.2% of kappa number reduction was observed for the industrial eucalypt pulp, with the same laccase-mediator system conditions. On the other hand, laccase-mediator system removes 35.9% of the initial kappa number of the unbleached softwood pulp. From the standpoint of the low delignification extent, the amount of lignin removed was almost twice. The effect of laccase-mediator system is mostly on lignin and the hexenuronic acid decrease slightly in the pulps. [Copyright &y& Elsevier]
- Published
- 2008
- Full Text
- View/download PDF
10. Pyrolysis-GC/MS and TG/MS study of mediated laccase biodelignification of Eucalyptus globulus kraft pulp
- Author
-
Oudia, Atika, Mészáros, Erika, Simões, Rogério, Queiroz, João, and Jakab, Emma
- Subjects
- *
ELECTRONIC equipment , *LACCASE , *EUCALYPTUS globulus , *THERMAL analysis - Abstract
Abstract: Biobleaching studies using laccase mediator system (LMS) were carried out, under optimized conditions, on two unbleached Eucalyptus globulus kraft pulps, one produced by conventional way, with kappa number of 16.1, and another with kappa number of 14.5, obtained by modified kraft procedure with a high liquor/wood ratio and with black liquor replacement in the middle of the cooking. The pulp properties before and after LMS and alkaline extraction were evaluated in terms of kappa number, hexeneuronic acid content, viscosity, brightness and acid insoluble lignin content. The original milled wood sample and the kraft pulps were characterized by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and thermogravimetry/mass spectrometry (TG/MS). Eucalypt wood lignin produces guaiacol and syringol derivatives during pyrolysis. These lignin products can be detected with high sensitivity using the selected ion chromatograms even in the bleached pulp of low lignin content (about 0.5%). Py-GC/MS revealed that the lignin moieties were similarly altered during biobleaching as during pulping, which is exemplified by the preferential removal of aldehyde groups from the alkyl side groups. Semi-quantitative analysis of the pyrograms indicates that the lignin content of the biobleached pulps is reduced by about half in comparison with the unbleached pulps. The TG/MS results show that the hemicellulose content of wood was strongly modified during pulping resulting in higher thermal stability. [Copyright &y& Elsevier]
- Published
- 2007
- Full Text
- View/download PDF
11. Chemical composition and kraft pulping potential of 12 eucalypt species.
- Author
-
Neiva, Duarte, Fernandes, Luís, Araújo, Solange, Lourenço, Ana, Gominho, Jorge, Simões, Rogério, and Pereira, Helena
- Subjects
- *
SULFATE pulping process , *EUCALYPTUS , *DELIGNIFICATION , *PLANT variation , *PLANT morphology - Abstract
Eucalypts are among the most important short-rotation hardwoods, planted worldwide for the pulp and paper industry. Even though the genus comprises over 700 species, only about a dozen species are used for pulping purposes, therefore, showing the potential for diversification. Six-year-old eucalypt trees from 12 species ( Eucalyptus botryoides, Eucalyptus camaldulensis, Eucalyptus globulus, Eucalyptus grandis, Corymbia maculata, Eucalyptus ovata, Eucalyptus propinqua, Eucalyptus resinifera, Eucalyptus rudis, Eucalyptus saligna, Eucalyptus sideroxylon, and Eucalyptus viminalis ) were analyzed for chemical composition, fiber morphological, pulping and handsheet paper properties to determine their kraft pulping suitability. The 12 species showed substantial differences regarding extractives (6.1–18.9%), lignin (21.6–30.8%) and holocellulose content (55.4–70.1%). The high inter-species variation in chemical composition produced pulps with different yields (between 38.9 and 49.8%) and degree of delignification (kappa number between 11.6 and 24.2). The combination of these results with the morphological and handsheet properties suggests that E. globulus, E. ovata, E. grandis, E. saligna and E. botryoides have the best overall characteristics for kraft pulping. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
12. Analytical pyrolysis study of biodelignification of cloned Eucalyptus globulus (EG) clone and Pinus pinaster Aiton kraft pulp and residual lignins
- Author
-
Oudia, Atika, Mészáros, Erika, Jakab, Emma, Simões, Rogério, Queiroz, João, Ragauskas, Arthur, and Novák, Lajos
- Subjects
- *
PYROLYSIS , *EUCALYPTUS globulus , *GAS chromatography/Mass spectrometry (GC-MS) , *CLUSTER pine - Abstract
Abstract: This study centred on the analysis of lignin in situ of cloned eucalypt and pine kraft pulps. Trametes versicolor laccase-violuric acid system (LMS) delignifications were performed on a softwood (Pinus pinaster) and a hardwood (Eucalyptus globulus) conventional kraft pulp with an initial kappa number of 34.5 and 15.5, respectively. The LMS treated pulps were then subjected to alkaline extraction stages (E). The kappa number data show that LMS is effective at biodelignifying both softwood and hardwood kraft pulps. However, under the conditions employed in this study, a greater level of biodelignification was obtained with LMS E. globulus (hardwood) than with LMS P. pinaster (softwood), but the amount of lignin removed was higher for the softwood pulp. The original milled wood samples, kraft pulps, biodelignified kraft pulps, and isolated residual lignin and milled wood lignins from the two wood samples have been characterized by pyrolysis-gas chromatography/mass spectrometry. The analysis of the pyrograms indicates that the lignin compositions of the two wood species and corresponding pulps are very different, as expected; however, the knowledge of the chemical mechanisms of delignification is very limited and requires additional work. Analytical pyrolysis is one the few degradative methods for the analysis of biopolymers that has shown a sufficient degree of success. [Copyright &y& Elsevier]
- Published
- 2009
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.