Search results for "Kraft paper"
showing 10 items of 29 documents
Combustion Properties of Birch (Betula pendula) Black Liquors From Sulfur-Free Pulping
2016
Sulfur-free pulping has an environmental advantage over the traditional kraft process. This article describes the combustion properties of the black liquors produced from silver birch (Betula pendula) sawdust using three different cooking processes: two sulfur-free cooks (soda-anthraquinone and oxygen-alkali), and one reference kraft cook. It also considers the corresponding black liquors from an integrated forest biorefinery, in which a hot-water pretreatment of feedstock was performed prior to pulping. With the same cooking time, the total burning times for the sulfur-free black liquors were higher (15–55%) than those for the conventional kraft black liquors. However, no significant diffe…
Description of kraft cooking and oxygen–alkali delignification of bamboo by pulp and dissolving material analysis
2008
Abstract The oxygen delignification of two bamboo ( Bambusa procera ) kraft pulps with kappa numbers of 13.6 and 20.0 were studied under typical conditions. Based on detailed analysis data on both the kraft and oxygen-delignified pulps and the corresponding spent liquors (black liquors and oxygen stage effluents), three yield and four selectivity estimation methods, utilizing component material balances, were tested resulting in the value ranges 96.2–97.9% and 43.5–60.4%, respectively, for oxygen delignification process studied. The traditional selectivity using the viscosity and kappa number relation was 66.9–68.4%. The studied bamboo kraft pulps behaved typically as birch kraft pulps duri…
Delignification of bamboo (Bambusa procera acher)
2004
Abstract Delignification of bamboo ( Bambusa procera acher ) was carried out by conventional kraft and soda pulping under varying conditions to determine the relationships between selected cooking parameters (EA 14–20%, sulfidity 0–45%, maximum temperature 165 and 170 °C, and time at maximum temperature 30–95 min) and pulp properties (kappa number, viscosity, and yield). Results indicated that in order to obtain relatively low kappa numbers (17–24), high sulfidity (35–45%) at lower EA (14–16%) increased both pulp viscosity and yield compared to the case of low sulfidity (0–15%) at higher EA (16–18%). Pulp with lower kappa numbers (11–15) and acceptable viscosities (1080–1190 ml/g) can be ob…
Free and bound chlorophenols in kraft pulp bleaching effluents
1992
Abstract Free (F; hexane extractable) and chemically bound (B; alkali extractable) chlorophenols, catechols and guaiacols were measured from effluents of the C and E stages of chlorobleaching of kraft softwood pulp. Ratio B/F was in moste cases nearly one, but for tetrachloroguaiacol B/F was 20 in C and 2.70 in E stage. Organically bound chlorine (OCl) in chlorophenols was less than one percent of the total AOX (Adsorbable Organic Halogen) emitted.
Characterization of Chlorolignins in Bleached Kraft Pulp Mill Effluents Using Elemental Analysis and Fingerprinting by CuO Oxidation And Hplc
1994
Abstract Elemental analyses and chemical degradation techniques were applied to characterize lignin compounds in different stages of the chlorine bleaching process and in total mill effluent. Ultrafiltration was used for separation of chlorolignins into three nominal molecular weight fractions. Alkaline CuO oxidation products were analyzed by HPLC with diode array detection. Major compounds were identified by reference to authentic compounds. For comparison, native lignins (MWL), kraft lignins, and humic substances were studied as well. The oxygen, carbon and organic chlorine contents were closely similar in the various mill samples and their fractions. In all mill samples, vanillin and 6-c…
Adsorption and separation of black liquor-derived phenol derivatives using anion exchange resins
2017
Abstract Kraft black liquor is the major waste stream of the paper pulping industry. This stream is usually directly incinerated in such facilities for energy production and recycling of the inorganic chemicals involved. However, lignin and other low molecular organic fragments dissolved in black liquor give rise to a large variety of aromatic fine chemicals. Energetic use of black liquor and its components prevents the removal of these valuable compounds from the waste stream. We present an easy protocol for adsorption and selective desorption of low molecular phenol derivatives from black liquor depending on the composition of the desorption system. Furthermore, adsorption experiments in …
Scanning probe microscopy of pine and birch kraft pulp fibres
2000
Abstract Fibres of the conventional pine and birch kraft pulps were characterized by scanning probe microscopy (SPM). The surface characteristics of these pulps taken at the early stages of pulping were compared with those from later stages of pulping (with or without subsequent oxygen/alkali delignification). It was observed that during delignification a granular surface structure was replaced by a fibrillar surface containing various disruptions. The granular and fibrillar regions were particularly well resolved by using phase imaging in tapping mode of SPM. It was concluded that the granular structure corresponded to surface lignin since the decrease in the relative amount of the granula…
Characterization of softwood and hardwood lignoboost kraft lignins with emphasis on their antioxidant activity
2014
Fractionation of softwood and hardwood LignoBoost kraft lignins, using sequential extraction with organic solvents of increasing hydrogen-bonding ability (dichloromethane, n-propanol, and methanol), was carried out. Using SEC, analytical pyrolysis, FTIR and UV/VIS spectroscopy, and chemical analytical methods, four fractions were obtained and characterized in terms of their yield, composition, functionality, lignin structural features, and antioxidant properties. In tests with free radicals (ABTS●+, DPPH●, O2●-) and the ORAC (oxygen radical absorbance capacity) assay, the high radical scavenging capacity of the lignin’s soluble fractions was demonstrated. The antioxidant activity of the fra…
Altered Challenge Response in Whitefish Subchronically Exposed in Areas Polluted by Bleached Kraft Mill Effluents
1999
Exposure to impaired water quality, as in bleached kraft mill effluents (BKMEs), has recently been demonstrated to impair the ability of fish to elicit an acute stress response. Acute stress caused by catching is, in most field studies, an unavoidable incident that may markedly affect physiological functions. Consistently, dissimilar stress responses to catching procedures in exposed and reference animals may lead to altered results. In this study, juvenile whitefish (Coregonus levaretus) were caged for 30 days in two reference areas and three areas affected by different BKMEs, and the immediate effects of low-level handling on physiological functions in four periods within an hour of the s…
Die Wirkung von kurzen oberkörperspezifischen Bewegungs- und Trainingsinterventionen am Arbeitsplatz auf die Parameter Schmerz und Kraft
2019
ZusammenfassungDas systematische Review untersucht die Auswirkungen von oberkörperspezifischen Kurzinterventionen am Arbeitsplatz auf muskuloskelettale Schmerzen sowie den muskulären Kraftzuwachs.Es wurde eine systematische Literaturrecherche in den Datenbanken PubMed und Google Scholar durchgeführt; eingeschlossen wurden ausschließlich randomisierte kontrollierte Studien. Als Interventionsdauer wurden mindestens 4 Wochen definiert und eine Einheit sollte zwischen 10 und 20 Minuten bei einem maximalen Wochenumfang von 75 Minuten betragen. Insgesamt wurden 16 Studien – unterteilt in 11 Cluster – eingeschlossen, welche die Auswirkungen von Kurzinterventionen auf die Variablen Kraft und Schmer…