Bleachability of Alkaline Pulps. Part 1. The Importance of β-Aryl Ether Linkages in Lignin

Holzforschung ◽  
2000 ◽  
Vol 54 (6) ◽  
pp. 609-617 ◽  
Author(s):  
G. Gellerstedt ◽  
W. Wafa Al-Dajani
Keyword(s):  
Hydrogen Peroxide ◽  
Structural Studies ◽  
Kraft Pulps ◽  
Residual Lignin ◽  
Aryl Ether ◽  
Different Types

Summary Analytical and structural studies were done on different types of alkaline pulps and their isolated residual lignins. Although having the same degree of delignification after cooking, some pulps were easier to bleach than others. All isolated residual lignins were found to contain β-aryl ether (β-O-4) structures in reasonable amounts when analysed by thioacidolysis (≥10 % of the native lignin value). At decreasing kappa numbers, there was also a corresponding decrease in the amount of β-aryl ether structures in the residual lignin. Moreover, a high β-aryl ether content in the unbleached residual lignin after cooking was found to contribute to a better bleachability of the pulp, especially when hydrogen peroxide stages were involved. At the same degree of delignification, the superior bleachability of alkaline sulfite pulps over kraft pulps was shown to be attributable to a higher content of β-aryl ether linkages in the former type of pulps.

Impacts of Changing Operational Parameters of In Situ Chemical Oxidation (ISCO) on Removal of Aged PAHs from Soil

2012 ◽  
Vol 15 (2) ◽  
Author(s):  
Paula Cajal-Mariñosa ◽  
Ruth G. de la Calle ◽  
F. Javier Rivas ◽  
Tuula Tuhkanen
Keyword(s):  
Hydrogen Peroxide ◽  
Removal Efficiency ◽  
Contaminated Soil ◽  
Chemical Oxidation ◽  
Contaminant Removal ◽  
Operational Parameters ◽  
In Situ Chemical Oxidation ◽  
Different Types ◽  
Wood Impregnation

AbstractThe removal efficiency of two different types of peroxide addition, catalyzed hydrogen peroxide (CHP) and sodium percarbonate (SPC) were compared on a highly PAH-contaminated soil from a wood impregnation site. In an attempt to simulate real in situ reagents delivery, experiments have been carried out in acrylic columns. The main parameters affecting contaminant removal were the reagent’s temperature and the total addition of peroxide (g

Initiating ECF bleaching sequences of eucalyptus kraft pulps with Z/D and Z/E stages

Holzforschung ◽  
2010 ◽  
Vol 64 (1) ◽  
Author(s):  
Juan C. García ◽  
Francisco López ◽  
Antonio Pérez ◽  
M. Angels Pèlach ◽  
Pere Mutjé ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Chlorine Dioxide ◽  
Ecological Impact ◽  
Substantial Reduction ◽  
Reference Sequence ◽  
Kraft Pulps ◽  
Eucalyptus Kraft Pulp ◽  
The Impact ◽  
Ecf Bleaching ◽  
Ozone Bleaching

Abstract Ozone bleaching is a common practice in pulping, and also of eucalyptus, where it is usually applied in combination with bleaching sequences based on oxygen, hydrogen peroxide, or chlorine dioxide. Ozone has been proven to be a highly efficient and competitive bleaching chemical in terms of delignification efficiency, low costs, and reducing ecological impact. The objective of the present work was to evaluate technology with ozone/alkaline extraction (Z/E) and ozone/chlorine dioxide (Z/D) for bleaching of eucalyptus kraft pulp. Primarily, the impact of these bleaching steps on refinability and quality of pulp should be investigated. As reference, the sequence D*(EP)D (hot chlorine dioxide, extraction in presence of hydrogen peroxide, chlorine dioxide) was selected, which is considered as the state-of-the-art bleaching in elemental chlorine free (ECF) bleaching technology. Various bleaching sequences with ozone in their first step (Z/D(EP)DP, Z/D(EP)DD, Z/EDP, Z/EDD and A*Z/EDP) were found to provide kraft pulps of similar brightness and in similar yield as the reference sequence D*(EP)D. The kappa number, viscosity, and the contents of glucose and xylose, and hexenuronic acid of the pulps were also similar. In addition, the Z sequences resulted in a substantial reduction of the total chlorine dioxide consumption (more than 30.3% in all cases). The A*Z/EDP sequence, which proved to be the most efficient, yielded 87.5% ClO2 reduction. The studied bleaching sequences also resulted in substantially improved brightness reversal with regard to the reference sequence. The sequence A*Z/EDP was also the most efficient as regards the removal or organochlorines (OX) from the pulp and their reduction in the effluents (AOX). Ozone bleaching sequences improved paper strength, especially with the A*Z/EDP sequence.

The association of trace elements with manganese minerals in Australian soils

Soil Research ◽  
1966 ◽  
Vol 4 (1) ◽  
pp. 29 ◽  
Author(s):  
RM Taylor ◽  
RM McKenzie
Keyword(s):  
Hydrogen Peroxide ◽  
Trace Elements ◽  
Nitric Acid ◽  
Different Types ◽  
The Common ◽  
Manganese Minerals

In widely different types of Australian soils birnessite and lithiophorite appear to be the common forms of occurrence of mineralized manganese. These mineral forms were dissolved out of the soil by hydrogen peroxide acidified to pH 3 with nitric acid and analyses of the extracts were made. It was found that the concentration of trace elements is generally quite high in these minerals. In particular, most of the soil cobalt (average 79%) was contained in or associated with these minerals where they were present.

Identification of residual lignin markers in eucalypt kraft pulps by Py–GC/MS

2001 ◽  
Vol 58-59 ◽  
pp. 425-439 ◽  
Author(s):  
J.C. del Rı́o ◽  
A. Gutiérrez ◽  
J. Romero ◽  
M.J. Martı́nez ◽  
A.T. Martı́nez
Keyword(s):  
Kraft Pulps ◽  
Residual Lignin

Sensitized chemiluminescence reaction between hydrogen peroxide and periodate of different types of Mn-doped ZnS quantum dots

2010 ◽  
Vol 55 (30) ◽  
pp. 3479-3484 ◽  
Author(s):  
JunXiao Liu ◽  
Hui Chen ◽  
Ling Lin ◽  
Chao Lu ◽  
JinMing Lin
Keyword(s):  
Hydrogen Peroxide ◽  
Quantum Dots ◽  
Different Types ◽  
Mn Doped

Fate of Residual Lignin during Delignification of Kraft Pulp by Trametes versicolor

1998 ◽  
Vol 64 (6) ◽  
pp. 2117-2125 ◽  
Author(s):  
Ian D. Reid
Keyword(s):  
Trametes Versicolor ◽  
Kraft Pulp ◽  
Lignin Degradation ◽  
Water Soluble ◽  
Kraft Pulps ◽  
Residual Lignin ◽  
Spruce Wood ◽  
Single Ring ◽  
Enzyme Bleaching ◽  
By Products

ABSTRACT The fungus Trametes versicolor can delignify and brighten kraft pulps. To better understand the mechanism of this biological bleaching and the by-products formed, I traced the transformation of pulp lignin during treatment with the fungus. Hardwood and softwood kraft pulps containing 14C-labelled residual lignin were prepared by laboratory pulping of lignin-labelled aspen and spruce wood and then incubated with T. versicolor. After initially polymerizing the lignin, the fungus depolymerized it to alkali-extractable forms and then to soluble forms. Most of the labelled carbon accumulated in the water-soluble pool. The extractable and soluble products were oligomeric; single-ring aromatic products were not detected. The mineralization of the lignin carbon to CO2 varied between experiments, up to 22% in the most vigorous cultures. The activities of the known enzymes laccase and manganese peroxidase did not account for all of the lignin degradation that took place in the T. versicolor cultures. This fungus may produce additional enzymes that could be useful in enzyme bleaching systems.

Methionine-enkephalin modulation of hydrogen peroxide (H2O2) release by rat peritoneal macrophages involves different types of opioid receptors

Neuropeptides ◽  
2008 ◽  
Vol 42 (2) ◽  
pp. 147-158 ◽  
Author(s):  
Stanislava Stanojević ◽  
Vesna Vujić ◽  
Katarina Mitić ◽  
Nataša Kuštrimović ◽  
Vesna Kovačević-Jovanović ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Opioid Receptors ◽  
Peritoneal Macrophages ◽  
Methionine Enkephalin ◽  
Different Types

Voltammetric analysis of the bleachability of softwood kraft pulps

Holzforschung ◽  
2004 ◽  
Vol 58 (6) ◽  
pp. 581-587 ◽  
Author(s):  
Robert Bourbonnais ◽  
Loredana Valeanu ◽  
Michael G. Paice
Keyword(s):  
Chlorine Dioxide ◽  
Acid Content ◽  
Black Spruce ◽  
Kappa Number ◽  
Western Hemlock ◽  
Kraft Pulps ◽  
Residual Lignin ◽  
Redox Mediators ◽  
Voltammetric Analysis ◽  
Hexenuronic Acid

Abstract Kraft and oxygen delignified pulps with various kappa numbers were prepared from black spruce and western hemlock chips. The bleachability (ratio of kappa number decrease to chlorine dioxide applied) of the different pulps at the same kappa number varied with both wood furnish and delignification process. Thus, unbleached kappa number alone is not a reliable indicator of bleachability for these pulps. This may be due in part to the variable hexenuronic acid content of the pulps; those with higher ratio of hexenuronic acid content to kappa number (HexA/kappa) are harder to bleach. Voltammetric analysis of the same kraft pulps in the presence of redox mediators was found to measure both the content and reactivity of residual lignin. Peak current ratios of redox mediators correlated with pulp bleachability for all pulps. These ratios may therefore provide a more accurate prediction of bleachability than unbleached kappa number.

The Influence of Molding Powder Breakup on the Sintered Ceramic Quality

2014 ◽  
Vol 698 ◽  
pp. 513-518 ◽  
Author(s):  
Natalya Belousova ◽  
Sergey Veselov ◽  
Ruslan Kuzmin ◽  
Elena Melnikova
Keyword(s):  
Physical Properties ◽  
Fractional Composition ◽  
Ceramic Materials ◽  
Structural Studies ◽  
Sintered Ceramic ◽  
Press Powder ◽  
Molding Powder ◽  
Different Types ◽  
Properties Of Materials

This paper assesses the moldability of press-powder with different fractional composition. Different types of defects that occur in ceramic materials due to insufficient or overpressure of molding of press powderare analyzed. Based on results of structural studies and evaluation of the physical properties of materials recommendations on the molding selection modes of press-powders with different fractional composition that provide the absence of defects in the compacts and obtaining quality dense ceramics are formulated.

Structural studies on different types of ferroelectric liquid crystalline substances

2011 ◽  
Vol 35 (1) ◽  
pp. 3-13 ◽  
Author(s):  
D. Obadović ◽  
M. Stojanović ◽  
A. Bubnov ◽  
N. Éber ◽  
M. Cvetinov ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Molecular Conformation ◽  
Large Angle ◽  
Structural Studies ◽  
Layer Spacing ◽  
Different Types ◽  
Intermolecular Distances ◽  
Chiral Liquid Crystals

Structural studies on different types of ferroelectric liquid crystalline substances Structural studies of ferroelectric liquid crystalline substances of different molecular structure have been reviewed. The discussion of the results deals mainly with the structure of chiral liquid crystals forming the smectic mesophase with ferroelectric order, as the research on ferroelectric liquid crystals, due to their high potential for application in electro-optics and photonics, has recently become one of the most attractive fields. Based on data of polarizing optical microscopy and X-ray diffraction obtained for unoriented samples we have identified the type of the mesophases, the temperature of the phase transitions and outlined the phase diagrams. An analysis of the relation between the molecular conformation and different types of phase transitions has been performed. The layer spacing and the average intermolecular distances have been determined for all studied phases from the positions of the small and the large angle diffraction peaks, respectively.

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