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.

Effects of the partial removal of wood hemicelluloses on the properties of kraft pulp

The objective of this work was to study the effects of partial removal of wood hemicelluloses on the properties of kraft pulp.The work was conducted by extracting hemicelluloses (1) by a softwood chip pretreatment process prior to kraft pulping, (2) by alkaline extraction from bleached birch kraft pulp, and (3) by enzymatic treatment, xylanase treatment in particular, of bleached birch kraft pulp. The qualitative and quantitative changes in fibers and paper properties were evaluated. In addition, the applicability of the extraction concepts and hemicellulose-extracted birch kraft pulp as a raw material in papermaking was evaluated in a pilot-scale papermaking environment. The results showed that each examined hemicellulose extraction method has its characteristic effects on fiber properties, seen as differences in both the physical and chemical nature of the fibers. A prehydrolysis process prior to the kraft pulping process offered reductions in cooking time, bleaching chemical consumption and produced fibers with low hemicellulose content that are more susceptible to mechanically induced damages and dislocations. Softwood chip pretreatment for hemicellulose recovery prior to cooking, whether acidic or alkaline, had an impact on the physical properties of the non-refined and refined pulp. In addition, all the pretreated pulps exhibited slower beating response than the unhydrolyzed reference pulp. Both alkaline extraction and enzymatic (xylanase) treatment of bleached birch kraft pulp fibers indicated very selective hemicellulose removal, particularly xylan removal. Furthermore, these two hemicellulose-extracted birch kraft pulps were utilized in a pilot-scale papermaking environment in order to evaluate the upscalability of the extraction concepts. Investigations made using pilot paper machine trials revealed that some amount of alkalineextracted birch kraft pulp, with a 24.9% reduction in the total amount of xylan, could be used in the papermaking stock as a mixture with non-extracted pulp when producing 75 g/m2 paper. For xylanase-treated fibers there were no reductions in the mechanical properties of the 180 g/m2 paper produced compared to paper made from the control pulp, although there was a 14.2% reduction in the total amount of xylan in the xylanase-treated pulp compared to the control birch kraft pulp. This work emphasized the importance of the hemicellulose extraction method in providing new solutions to create functional fibers and in providing a valuable hemicellulose co-product stream. The hemicellulose removal concept therefore plays an important role in the integrated forest biorefinery scenario, where the target is to the co-production of hemicellulose-extracted pulp and hemicellulose-based chemicals or fuels.

The Impact of Aspen and Alder on the Quality of NHBK

The purpose of this work was to study the effect of aspen and alder on birch cooking and the quality of the pulp produced. Three different birch kraft pulps were studied. As a reference, pure aspen and alder were included. The laboratory trials were done at the UPM Research Centre in Lappeenranta, Finland. The materials used were birch, aspen and alder mill chips that were collected around the area of South-Carelia in Finland. The chips used in the study were pulped using a standard kraft process. The pulps including birch fibres were ECF-bleached at laboratory scale to a target brightness of 85 %. The bleached pulps were beaten at low consistency by a laboratory Voith Sulzer refiner and tested for optical and physical properties. The theoretical part is a study of hardwoods that takes into accounts the differences between birch, aspen and alder. Major sub-areas were fibre and paper-technical properties as well as chemical composition and their influence on the different properties. The pulp properties of birch, aspen and alder found in previous studies were reported. Russian hardwood forest resources were also investigated. The fundamentals of kraft pulping and bleaching were studied at the end of theoretical part. The major effect of replacing birch with aspen and alder was the deterioration (lowering) of tensile and tear strengths. In other words, addition of aspen and alder to a birch furnish reduced strength properties. The reinforcement ability of the tested pulps was the following: 100 % birch > 80 % birch, 20 % aspen > 70 % birch, 20 % aspen, 10 % alder. The second thing noted was that blending of birch together with aspen and alder give better smoothness, optical properties and also formation. It can be concluded, that replacement of birch with alder during cooking by more than 10 % can negatively affect on the paper-technical properties of birch pulp. Mixing pure birch and aspen pulps would be more beneficial when producing printing paper made from chemical pulp.

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;

Estimation of hexenuronic acids and kappa number in kraft pulps of Eucalyptus globulus by Fourier transform near infrared spectroscopy and multivariate analysis

Fourier transform near infrared (FT-NIR) spectroscopy was evaluated as an analytical too[ for monitoring residual Lignin, kappa number and hexenuronic acids (HexA) content in kraft pulps of Eucalyptus globulus. Sets of pulp samples were prepared under different cooking conditions to obtain a wide range of compound concentrations that were characterised by conventional wet chemistry analytical methods. The sample group was also analysed using FT-NIR spectroscopy in order to establish prediction models for the pulp characteristics. Several models were applied to correlate chemical composition in samples with the NIR spectral data by means of PCR or PLS algorithms. Calibration curves were built by using all the spectral data or selected regions. Best calibration models for the quantification of lignin, kappa and HexA were proposed presenting R-2 values of 0.99. Calibration models were used to predict pulp titers of 20 external samples in a validation set. The lignin concentration and kappa number in the range of 1.4-18% and 8-62, respectively, were predicted fairly accurately (standard error of prediction, SEP 1.1% for lignin and 2.9 for kappa). The HexA concentration (range of 5-71 mmol kg(-1) pulp) was more difficult to predict and the SEP was 7.0 mmol kg(-1) pulp in a model of HexA quantified by an ultraviolet (UV) technique and 6.1 mmol kg(-1) pulp in a model of HexA quantified by anion-exchange chromatography (AEC). Even in wet chemical procedures used for HexA determination, there is no good agreement between methods as demonstrated by the UV and AEC methods described in the present work. NIR spectroscopy did provide a rapid estimate of HexA content in kraft pulps prepared in routine cooking experiments.

Comparison of Py-GC/FID and Wet Chemistry Analysis for Lignin Determination in Wood and Pulps from Eucalyptus globulus

The kraft pulps produced from heartwood and sapwood of Eucalyptus globulus at 130 degrees C, 150 degrees C, and 170 degrees C were characterized by wet chemistry (total lignin as sum of Klason and soluble lignin fractions) and pyrolysis (total lignin denoted as py-lignin). The total lignin content obtained with both methods was similar. In the course of delignification, the py-lignin values were higher (by 2 to 5%) compared to Klason values, which is in line with the importance of soluble lignin for total lignin determination. Pyrolysis analysis presents advantages over wet chemical procedures, and it can be applied to wood and pulps to determine lignin contents at different stages of the delignification process. The py-lignin values were used for kinetic modelling of delignification, with very high predictive value and results similar to those of modelling using wet chemical determinations.

Reactivity of syringyl and guaiacyl lignin units and delignification kinetics in the kraft pulping of eucalyptus globulus wood using Py-Gc-Ms/FID

Eucalyptus globulus sapwood and heartwood showed no differences in lignin content (23.0% vs. 23.7%) and composition: syringyl-lignin (17.9% vs. 18.0%) and guaiacyl-lignin (4.8% vs. 5.2%). Delignification kinetics of S- and G-units in heartwood and sapwood was investigated by Py-GC–MS/FID at 130, 150 and 170 °C and modeled as double first-order reactions. Reactivity differences between S and G-units were small during the main pulping phase and the higher reactivity of S over G units was better expressed in the later pulping stage. The residual lignin composition in pulps was different from wood or from samples in the initial delignification stages, with more G and H-units. S/G ratio ranged from 3 to 4.5 when pulp residual lignin was higher than 10%, decreasing rapidly to less than 1. The S/H was initially around 20 (until 15% residual lignin), decreasing to 4 when residual lignin was about 3%.

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 ºC 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 ºC 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 OA HT D(EP)DD showed the lowest bleaching performance among all.

Folkförsörjningsministeriets beslut angående reglementering av mat och förfriskningar, som serveras i förplägningsrörelser, samt prisen på dem i kraft f.o.m. 22.2.1945

14 x 20 cm

Analytics for the modified kraft pulps

Tämän diplomityön tavoitteena on kehittää sopiva analyyttinen menetelmä muokatun kraft-sellukuidun substituutioasteen (DS) kvantitatiivista määrittämistä varten. Muokkauksella tarkoitetaan tässä yhteydessä joko kovalenttisesti tai adsorption avulla tapahtuvaa molekyylin kiinnittymistä sellukuidun pinnalle. Työn kirjallisuusosuudessa käsitellään lyhyesti eri muokkaustapoja ja yhdisteitä joiden avulla voidaan saavuttaa haluttuja ominaisuuksia sellusta valmistetuille lopputuotteille. Lisäksi kirjallisuusosuudessa käydään läpi käyttötarkoitukseen soveltuvimpia suoria ja epäsuoria analyysimenetelmiä. Analyysimenetelmistä kaikkein lupaavimpia testattiin työn kokeellisessa osassa. Diplomityön kokeellisessa osassa keskityttiin kehittämään muokatulle sellulle kvantitatiivista menetelmää DS:n määrittämiseksi Fourier-muunnos infrapuna-vaimennettu kokonaisheijastus (FTIR-ATR) spektrometrillä. Kirjallisuuskatsauksessa ei löytynyt yhtään dokumentoitua tutkimusta, jossa FTIR-ATR menetelmää olisi käytetty muokatun sellukuidun kvantitatiiviseen tutkimukseen. Muiden analyysimenetelmien, kuten alkuaineanalyysin, termogravimetrisen analyysin (TGA) ja valomikroskopian avulla pyrittiin tuottamaan lisätietoa muokkauksesta. Kvantitatiivisen FTIR-ATR menetelmän kehitykseen käytetyt muokatut sellukuidut olivat selluloosa-asetaattia ja selluloosa betainaattia. Saatujen tulosten perusteella muokattujen sulfiitti- ja kraft sellukuitujen DS:n kvantitatiivinen määrittäminen on mahdollista FTIR-ATR menetelmällä. Vähäinen kalibrointipisteiden määrä vaikeutti tarkan analyysimenetelmän tekemistä. Kehitetyn menetelmän suurimpina ongelmina olivat kiinteiden näytteiden heterogeenisyys sekä mahdollisten epäpuhtauksien tunnistaminen. Jatkotutkimusten avulla kehitettyä menetelmää on kuitenkin mahdollista käyttää muokattujen sellukuitujen jatkuvaan analysointiin selluteollisuudessa.

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)