Hydrogen peroxide and supercritical carbon dioxide: a new bleaching stage for Eucalyptus kraft-O(2) pulps

Kraft pulp is currently bleached largely by the elemental chlorine free (ECF) technology with oxygen, chlorine dioxide, and hydrogen as active agents. This technology brought about significant environmental improvements in relation to standard processes based on chlorine gas and hypochlorite, but there is still need for further improvements. This study presents a novel environmentally friendly bleaching stage - the so-called `hydrogen peroxide in supercritical carbon dioxide`, P((SC-CO2)) - that can be adapted to current ECF bleaching processes, with preference in cases where hydrogen peroxide is already used. In this study, the P((SC-CO2)) stage was evaluated as a replacement to the last peroxide stage of the D(EP)DP bleaching sequence and to the first peroxide stage of the D(EP)DP sequence, for an oxygen delignified eucalypt kraft-O(2) pulp. The P((SC-CO2)) stage was run with 0.5% hydrogen peroxide, at 15% consistency, 70 degrees C, and 73 bar. The reaction time was 30 min. The performances of regular P stages and the new P((SC-CO2)) stage were compared. Promising results were observed with the DEP((SC-CO2))DP sequence; the P((SC-CO2)) decreased kappa number from 2.7 to 2.1, and the hexenuronic acid groups from 17.0 to 12.4 mmol kg(-1). The P((SC-CO2)) stage showed poor performance when applied in the D(EP)DP((SC-CO2)) sequence. It is concluded that the process presents potential but requires further optimization to improve selectivity and efficiency.

Na 1 Nachlass Max Horkheimer, 99 - Korrespondenzen u.a. mit Siegfried Kracauer und Alexander Mitscherlich (p. III 8, 213-408)

4 Briefe mit Antwort von Kohlhammer Verlag an Max Horkheimer, 1953, 1957; 12 Briefe mit Antwort und Beialge von Professor Hans Kohn an Max Horkheimer, 1953-1958; 3 Briefe mit Antwort von Professor Hans Kohn an Theodor W. Adorno, 1957-1958; 1 Brief mit Antwort von Professor Hans Kohn an Helmut Viebrock, 1958; 1 Brief von Theodor W. Adorno an Helmut Vriebrock, 1957; 2 Briefe mit 1 Antwort zwischen Rudolph Kolisch und Max Horkheimer, 1957; 1 Telegram von Professor Rudolph Kolisch an R. K., 1956; 1 Brief von Max Horkheiemr an den Kölner Universitäts-Verlag, 1957; 1 Drucksache von der Kölner Zeitschrift für Soziologie, 1953; 1 Drucksache von dem Kongress für Internationale Wissenschaftsgeschichte, 1951; 1 Brief mit Beilage von dem Königsteiner Kreis an Max Horkheimer, 1951; 1 Drucksache mit Beilage von der Zeitschrift "Konkret", 1958; 2 Briefe mit 1 Antwort zwischen Sekretärin Mathilde Koppen und Max Horkheimer, 1951, 1956; 2 Telegramme von Fritz Kortner an Max Horkheimer, 1952; 4 Briefe mit Antwort von Siegfried Kracauer an Max Horkheimer, 1951-1956; 1 Brief von Max Horkheimer an Professor Alexander Mitscherlich, 1956; 1 Brief mit Antwort von Hildegard Krämer an Max Horkheimer, 1956; 2 Briefe mit 1 Antwort von Dr. Rudolf Krämer-Badoni an Max Horkheimer, 1950, 1951; 2 Briefe mit Antwort von Professor Julius Kraft an Max Horkheimer, 1956, 1958; 1 Brief mit Antwort von Max Horkheimer an den Präsident d. LVA Heinrich Kraft, 1955; 2 Briefe mit Antwort von Werner Kraft an Max Horkheimer, 1953; 1 Brief von Angelo Kramer an Max Horkheimer, 1955; 2 Briefe von dem Architekt Ferdinand C. A. F. Kramer an Max Horkheimer, 1952; 2 Briefe mit Antwort von dem evangelischen Studentenpfarrer Dr. Rudolf Krapp an Max Horkheimer, 1958; 1 Brief mit Antwort und Beilage von dem Rechtsreferendar Heinz Kraus, 1956; 1 Drucksache von dem Frankfurter Studentenlied, 1956; 1 Aktennotiz von Professor Otto F. Kraushaar, 1953; 1 Brief von Max Horkheimer an den Regierungspräsident Wiesbaden,1952; 1 Aktennotiz von Klaus Kremer, 1958; 1 Brief von Dr. Stephanie Krenn an Max Horkheimer, 1952; 1 Aktennotiz von Dean Krasomil, 1952; 1 Brief mit Beilage von Anneliese Kreutz an Max Horkheimer, 1955; 1 Brief von Anneliese Kreutz an Professor Wilhelm Sturmfels, 1955; 1 Brief mit Antwort und Beilage von Robert H. Kreutzer an Max Horkheimer, 1954; 1 Brief mit Antwort von Professor Hans Hermann Kritzinger an Max Horkheimer, 1952; 2 Briefe mit Antwort von dem Betriebspsychologe Ludwig Kroeber-Keneth an Max Horkheimer, 1954; 1 Brief mit Antwort und Beilage von Professor Oswald Kroh an Max Horkheimer, 1952; 1 Todesanzeige von Professor Oswald Kroh, 1955; 1 Brief mit Antwort von Professor Wilhelm Kromphardt an Max Horkheimer, 1958; 1 Brief mit Antwort von Max Horkheimer an den Zirkus Krone, 1956; 1 Gutachten über Hans Joachim Krüger, 1958; 1 Brief mit Antwort von Melitta Krüger an Max Horkheimer, 1958; 2 Briefe mit Antwort und Beilage von dem Privatdozent Otto Kühne an Max Horkheimer, 1954, 1957; 1 Brief von Max Horkheimer an den Ministerialrat Dr. Dr. Kühn, 1953; 1 Vermählungsanzeige von Walter Kühn, 1957; 1 Aktennotiz von dem Rundfunk Dr. Kuhnert, ohne Jahr; 1 Brief von P. W. Krüger an Max Horkheimer, 1951; 1 Vermählungsanzeige mit Antwort von Hans K. Kullmer, 1953; 3 Briefe mit Antwort und Beilage von Dr. rer. pol. Ulrich Küntzel an Max Horkheimer, 1952; 1 Brief mit Antwort von dem Professor Fritz Baade an Max Horkheimer, 1952; 3 Breife mit Antwort von dem Verlag Walter de Gruyter an Max Horkheimer, 1954, 1955; 1 Brief mit Antwort von Max Horkheimer an den Kürschners Deutscher Gelehrten-Kalender, 1954; 2 Drucksachen von der Sektkellerei Kupferberg & Co, 1956; 3 Briefe mit Antwort von dem Reisebüro Kuoni an Max Horkheimer, 1957; 1 Brief mit Antwort von Max Horkheimer an das Kurhaus "Zur Rose" Bad Meinberg, 1956; 2 Briefe mit Antwort und Beilage von der Kurhessische Gesellschaft für Kunst und Wissenschaft an Max Horkheimer, 1954; 1 Gutachten von Thomas Gabor Kürthy, 1958; 1 Brief mit Antwort von Max Horkheimer an den Generaldirektor Dr. Kuss, 1953; 1 Brief mit Antwort von Professor Joseph J. Kwiat an Max Horkheimer, 1955;

A influência dos ácidos hexenurônicos no rendimento e na branqueabilidade da polpa kraft

This study investigated the impact of pulp hexenuronic acids (HexAs) content on pulping yield by changing cooking reaction temperature. The bleachability of pulps containing variable amounts of HexAs was also investigated. The cooking at 170 degrees C produced pulp of kappa number, HexAs and screen yield of 16.2, 49.4 mmol/kg and 50.2%, respectively, whereas the cooking at 156 degrees C resulted pulp of kappa 17.0, 61.3 mmol/kg HexAs and 50.8% screened yield. The pulp produced at lower cooking temperature also showed better bleachability as evaluated by the total amount of active chlorine required to achieve 90% ISO. The sequence OAHTD(EP) DD showed the lowest bleaching performance among all.

Application of crude xylanase from Bacillus licheniformis 77-2 to the bleaching of eucalyptus Kraft pulp

Alkalophilic Bacillus licheniformis 77-2 produced an extracellular alkali-tolerant xylanase with negligible cellulase activity in medium containing corn straw. The effectiveness of crude xylanase on treatment of eucalyptus Kraft pulp was evaluated. A biobleaching experiment was carried out to compare the chlorine saving with pulp treated and untreated by the enzyme. Two-stage bleaching was employed, using a ClO2 chlorination and NaOH extraction (DE sequence). With the enzymatic treatment, in order to obtain the same value of Kappa number and brightness, respectively 28.5 and 30% less ClO2 was required in comparison to the enzymatically untreated samples.

Kraft pulp from juvenile and mature woods of corymbia citriodora

Kraft pulp produced from juvenile and mature wood from thirty-two-year-old Corymbia citriodora trees was evaluated. The stem was subdivided into regions of juvenile and mature wood, and then it was transformed into chips. These materials were then cooked in the Laboratory of Pulp and Paper at São Paulo State University (UNESP, Botucatu, SP, Brazil) and the physico-mechanical properties of the pulps were determined. The results showed that: (1) the pulp yields of mature wood were up to 4.4% greater in comparison to the juvenile wood, (2) the juvenile wood pulp required a shorter refining time than mature wood to reach the same Schopper-Riegler degree, (3) the juvenile wood pulp presented lower specific volume, and (4) the mature wood pulp presented greater air resistance, tensile, tear and burst index values, stress-strain factor, and stretch than the juvenile wood pulp.

Effect of s/g ratio on kraft pulping and ecf bleaching of some poplars and eucalyptus

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Lignin chemistry and topochemistry during kraft delignification of Eucalyptus globulus genotypes with contrasting pulpwood characteristics

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estudos da polpação kraft, branqueamento e refino de eucalyptus grandis x eucalyptus urophylla

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Cellulose micro/nanofibres from Eucalyptus kraft pulp: Preparation and properties

There is growing interest in cellulose nanofibres from renewable sources for several industrial applications. However, there is a lack of information about one of the most abundant cellulose pulps: bleached Eucalyptus kraft pulp. The objective of the present work was to obtain Eucalyptus cellulose micro/nanofibres by three different processes, namely: refining, sonication and acid hydrolysis of the cellulose pulp. The refining was limited by the low efficiency of isolated nanofibrils, while sonication was more effective for this purpose. However, the latter process occurred at the expense of considerable damage to the cellulose structure. The whiskers obtained by acid hydrolysis resulted in nanostructures with lower diameter and length, and high crystallinity. Increasing hydrolysis reaction time led to narrower and shorter whiskers, but increased the crystallinity index. The present work contributes to the different widespread methods used for the production of micro/nanofibres for different applications. (C) 2012 Elsevier Ltd. All rights reserved.

Enzymatic upgrading of eucalypt paper-grade kraft pulp within dissolving pulp production

Dissolving-grade pulps are commonly used for the production of cellulose derivatives and regenerated cellulose. High cellulose content, low content of non-cellulosic material, high brightness, a uniform molecular weight distribution and high cellulose reactivity are the key features that determine the quality of a dissolving pulp. The first part of this work was an optimization study regarding the application of selected enzymes in different stages of a new purification process recently developed in Novozymes for purifying an eucalypt Kraft pulp into dissolving pulp, as an alternative to the pre-hydrolysis kraft (PHK) process. In addition, a viscosity reduction was achieved by cellulase (endoglucanase) treatment in the beginning of the sequence, while the GH11 and GH10 xylanases contributed to boost the brightness of the final pulp. The second part of the work aimed at exploring different auxiliary enzyme activities together with a key xylanase towards further removal of recalcitrant hemicelluloses from a partially bleached Eucalypt Kraft pulp. The resistant fraction (ca. 6% xylan in pulp) was not hydrolysable by the different combinations of enzymes tested. Production of a dissolving pulp was successful when using a cold caustic extraction (CCE) stage in the end of the sequence O-X-DHCE-X-HCE-D-CCE. The application of enzymes improved process efficiency. The main requirements for the production of a dissolving pulp (suitable for viscose making) were fulfilled: 2,7% residual xylan, 92,4% of brightness, a viscosity within the values of a commercial dissolving pulp and increased reactivity.

A influência dos ácidos hexenurônicos no rendimento e na branqueabilidade da polpa kraft

This study investigated the impact of pulp hexenuronic acids (HexAs) content on pulping yield by changing cooking reaction temperature. The bleachability of pulps containing variable amounts of HexAs was also investigated. The cooking at 170 degrees C produced pulp of kappa number, HexAs and screen yield of 16.2, 49.4 mmol/kg and 50.2%, respectively, whereas the cooking at 156 degrees C resulted pulp of kappa 17.0, 61.3 mmol/kg HexAs and 50.8% screened yield. The pulp produced at lower cooking temperature also showed better bleachability as evaluated by the total amount of active chlorine required to achieve 90% ISO. The sequence OAHTD(EP) DD showed the lowest bleaching performance among all.

A study into the permeability and compressibility of Australian bagasse pulp

This is an experimental study into the permeability and compressibility properties of bagasse pulp pads. Three experimental rigs were custom-built for this project. The experimental work is complemented by modelling work. Both the steady-state and dynamic behaviour of pulp pads are evaluated in the experimental and modelling components of this project. Bagasse, the fibrous residue that remains after sugar is extracted from sugarcane, is normally burnt in Australia to generate steam and electricity for the sugar factory. A study into bagasse pulp was motivated by the possibility of making highly value-added pulp products from bagasse for the financial benefit of sugarcane millers and growers. The bagasse pulp and paper industry is a multibillion dollar industry (1). Bagasse pulp could replace eucalypt pulp which is more widely used in the local production of paper products. An opportunity exists for replacing the large quantity of mainly generic paper products imported to Australia. This includes 949,000 tonnes of generic photocopier papers (2). The use of bagasse pulp for paper manufacture is the main application area of interest for this study. Bagasse contains a large quantity of short parenchyma cells called ‘pith’. Around 30% of the shortest fibres are removed from bagasse prior to pulping. Despite the ‘depithing’ operations in conventional bagasse pulp mills, a large amount of pith remains in the pulp. Amongst Australian paper producers there is a perception that the high quantity of short fibres in bagasse pulp leads to poor filtration behaviour at the wet-end of a paper machine. Bagasse pulp’s poor filtration behaviour reduces paper production rates and consequently revenue when compared to paper production using locally made eucalypt pulp. Pulp filtration can be characterised by two interacting factors; permeability and compressibility. Surprisingly, there has previously been very little rigorous investigation into neither bagasse pulp permeability nor compressibility. Only freeness testing of bagasse pulp has been published in the open literature. As a result, this study has focussed on a detailed investigation of the filtration properties of bagasse pulp pads. As part of this investigation, this study investigated three options for improving the permeability and compressibility properties of Australian bagasse pulp pads. Two options for further pre-treating depithed bagasse prior to pulping were considered. Firstly, bagasse was fractionated based on size. Two bagasse fractions were produced, ‘coarse’ and ‘medium’ bagasse fractions. Secondly, bagasse was collected after being processed on two types of juice extraction technology, i.e. from a sugar mill and from a sugar diffuser. Finally one method of post-treating the bagasse pulp was investigated. The effects of chemical additives, which are known to improve freeness, were also assessed for their effect on pulp pad permeability and compressibility. Pre-treated Australian bagasse pulp samples were compared with several benchmark pulp samples. A sample of commonly used kraft Eucalyptus globulus pulp was obtained. A sample of depithed Argentinean bagasse, which is used for commercial paper production, was also obtained. A sample of Australian bagasse which was depithed as per typical factory operations was also produced for benchmarking purposes. The steady-state pulp pad permeability and compressibility parameters were determined experimentally using two purpose-built experimental rigs. In reality, steady-state conditions do not exist on a paper machine. The permeability changes as the sheet compresses over time. Hence, a dynamic model was developed which uses the experimentally determined steady-state permeability and compressibility parameters as inputs. The filtration model was developed with a view to designing pulp processing equipment that is suitable specifically for bagasse pulp. The predicted results of the dynamic model were compared to experimental data. The effectiveness of a polymeric and microparticle chemical additives for improving the retention of short fibres and increasing the drainage rate of a bagasse pulp slurry was determined in a third purpose-built rig; a modified Dynamic Drainage Jar (DDJ). These chemical additives were then used in the making of a pulp pad, and their effect on the steady-state and dynamic permeability and compressibility of bagasse pulp pads was determined. The most important finding from this investigation was that Australian bagasse pulp was produced with higher permeability than eucalypt pulp, despite a higher overall content of short fibres. It is thought this research outcome could enable Australian paper producers to switch from eucalypt pulp to bagasse pulp without sacrificing paper machine productivity. It is thought that two factors contributed to the high permeability of the bagasse pulp pad. Firstly, thicker cell walls of the bagasse pulp fibres resulted in high fibre stiffness. Secondly, the bagasse pulp had a large proportion of fibres longer than 1.3 mm. These attributes helped to reinforce the pulp pad matrix. The steady-state permeability and compressibility parameters for the eucalypt pulp were consistent with those found by previous workers. It was also found that Australian pulp derived from the ‘coarse’ bagasse fraction had higher steady-state permeability than the ‘medium’ fraction. However, there was no difference between bagasse pulp originating from a diffuser or a mill. The bagasse pre-treatment options investigated in this study were not found to affect the steady-state compressibility parameters of a pulp pad. The dynamic filtration model was found to give predictions that were in good agreement with experimental data for pads made from samples of pretreated bagasse pulp, provided at least some pith was removed prior to pulping. Applying vacuum to a pulp slurry in the modified DDJ dramatically reduced the drainage time. At any level of vacuum, bagasse pulp benefitted from chemical additives as quantified by reduced drainage time and increased retention of short fibres. Using the modified DDJ, it was observed that under specific conditions, a benchmark depithed bagasse pulp drained more rapidly than the ‘coarse’ bagasse pulp. In steady-state permeability and compressibility experiments, the addition of chemical additives improved the pad permeability and compressibility of a benchmark bagasse pulp with a high quantity of short fibres. Importantly, this effect was not observed for the ‘coarse’ bagasse pulp. However, dynamic filtration experiments showed that there was also a small observable improvement in filtration for the ‘medium’ bagasse pulp. The mechanism of bagasse pulp pad consolidation appears to be by fibre realignment. Chemical additives assist to lubricate the consolidation process. This study was complemented by pulp physical and chemical property testing and a microscopy study. In addition to its high pulp pad permeability, ‘coarse’ bagasse pulp often (but not always) had superior physical properties than a benchmark depithed bagasse pulp.

Genome-wide association study identifies a locus at 7p15.2 associated with endometriosis

Endometriosis is a common gynecological disease associated with pelvic pain and subfertility. We conducted a genome-wide association study (GWAS) in 3,194 individuals with surgically confirmed endometriosis (cases) and 7,060 controls from Australia and the UK. Polygenic predictive modeling showed significantly increased genetic loading among 1,364 cases with moderate to severe endometriosis. The strongest association signal was on 7p15.2 (rs12700667) for 'all' endometriosis (P = 2.6 x 10(-)(7), odds ratio (OR) = 1.22, 95% CI 1.13-1.32) and for moderate to severe disease (P = 1.5 x 10(-)(9), OR = 1.38, 95% CI 1.24-1.53). We replicated rs12700667 in an independent cohort from the United States of 2,392 self-reported, surgically confirmed endometriosis cases and 2,271 controls (P = 1.2 x 10(-)(3), OR = 1.17, 95% CI 1.06-1.28), resulting in a genome-wide significant P value of 1.4 x 10(-)(9) (OR = 1.20, 95% CI 1.13-1.27) for 'all' endometriosis in our combined datasets of 5,586 cases and 9,331 controls. rs12700667 is located in an intergenic region upstream of the plausible candidate genes NFE2L3 and HOXA10.