Improvement of kraft pulp bleaching by treatments with laccase, urea, and refining

Holzforschung ◽  
2013 ◽  
Vol 67 (6) ◽  
pp. 651-658 ◽  
Author(s):  
Xueyu Du ◽  
Maria E. Eugenio Martín ◽  
Jiebing Li
Keyword(s):  
Lignin Content ◽  
Size Exclusion ◽  
Kraft Pulps ◽  
Pulp Bleaching ◽  
Lignin Fraction ◽  
Nuclear Magnetic Resonance Spectra ◽  
Kraft Pulp Bleaching ◽  
Mediator System ◽  
Exclusion Chromatography ◽  
Hexenuronic Acid

Abstract Unbleached Eucalyptus kraft pulps were treated by three methods and the bleaching effects have been evaluated. The treatments were performed by a laccase-mediator system (LMS), refining (R), and urea (U) alone and in combination of these methods. The bleached pulps were characterized in terms of κ number, hexenuronic acid content, brightness, and viscosity. In addition, the lignin-carbohydrate complexes (LCCs) were fractionated and characterized with regard to the fractionation yield, lignin content, and carbohydrate composition. Moreover, the 1H nuclear magnetic resonance spectra were recorded and the thioacidolysis-gas chromatography and thioacidolysis-size exclusion chromatography analyses were performed. The LMS treatment resulted mainly in a slightly better delignification as manifested by a κ number (K no.) reduction of 0.8 units. The effects of the U treatment included delignification (1.4 κ units), hexenuronic acid removal (3 μmol g-1), and improved pulp brightness (3.4 ISO units). The R treatment darkened the pulp (3 ISO units), whereas the bleaching of the R-pulp by subsequent LMS or U treatment enhanced the brightness (0.5 unit more) or delignification (0.3 unit more). The residual lignin in the pulp samples was present mainly as xylan-lignin. The Klason lignin content from the xylan-lignin fraction decreased as the degree of delignification increased. The pulp darkening followed by the R treatment was interpreted as the result of the formation of condensed lignin structures, but these condensed lignins were substantially removed by the subsequent LMS or U treatment.

Fluorescence spectroscopy for chromophore studies on bleached kraft pulps

Holzforschung ◽  
2007 ◽  
Vol 61 (5) ◽  
pp. 509-515 ◽  
Author(s):  
Sirje Liukko ◽  
Ville Tasapuro ◽  
Tiina Liitiä
Keyword(s):  
Fluorescence Spectroscopy ◽  
Fluorescence Spectra ◽  
Lignin Content ◽  
Excitation Wavelength ◽  
Kraft Pulps ◽  
Carbonyl Groups ◽  
Residual Lignin ◽  
Pulp Bleaching ◽  
Peroxide Bleaching ◽  
Brightness Reversion

Abstract Fluorescence techniques are highly sensitive and, since aromatic lignin is the most likely source of natural pulp fluorescence, they are suitable for detailed investigation of residual lignin in bleached pulps. Such investigations are important to our understanding of the bleachability and brightness reversion of pulps. In this study, the effect of bleaching on pulps was evaluated using fluorescence spectra of two softwood kraft pulps bleached in six elemental chlorine-free and totally chlorine-free sequences. Fluorescence spectra were recorded in each bleaching stage using four different instrument settings. In general, pulp fluorescence at excitation wavelengths of 270 and 350 nm increased as bleaching proceeded. Below a certain lignin content, however, pulp fluorescence measured at an excitation wavelength of 430 nm decreased with the residual lignin content. Carbonyl groups have a quenching effect on fluorescence, and the formation of carbonyl groups after oxygen and ozone delignification induced a decrease in pulp fluorescence. The increase in pulp fluorescence after peroxide bleaching stages was due to the removal of carbonyl groups. Reactions of chromophores during brightness reversion also had an effect on pulp fluorescence. These findings demonstrate that fluorescence spectroscopy provides an interesting tool for pulp bleaching studies.

Inhomogeneities in the Chemical Structure of Hardwood Lignins

Holzforschung ◽  
2003 ◽  
Vol 57 (3) ◽  
pp. 255-265 ◽  
Author(s):  
H. Önnerud ◽  
G. Gellerstedt
Keyword(s):  
Secondary Wall ◽  
Lignin Content ◽  
Middle Lamella ◽  
Size Exclusion ◽  
Wall Material ◽  
Thermomechanical Pulp ◽  
Aryl Ether ◽  
Spruce Wood ◽  
Exclusion Chromatography ◽  
The Difference

Summary Bauer-McNett fractions of an aspen chemi-thermomechanical pulp showed a significant variation with respect to lignin content and sugar composition, and two of the fractions were found to be particularly rich in middle lamella and secondary wall material, respectively. The secondary wall lignin of aspen was found to contain larger amounts of non-condensed β-O-4 aryl ether structures than the middle lamella lignin and the difference was attributed to a larger amount of syringyl structures as revealed by thioacidolysis. Size exclusion chromatography of the thioacidolysis products from birch and spruce wood showed a larger part of lignin oligomers being present in the degraded spruce lignin. Moreover, birch lignin had a lower phenolic content than both aspen and spruce lignin. Thioacidolysis followed by Raney-nickel desulphuration was used for the analysis of hardwood lignin trimers.

Size-exclusion chromatographic study of ECF and TCF softwood kraft pulp bleaching liquors

2011 ◽  
Vol 18 (7) ◽  
pp. 1049-1056 ◽  
Author(s):  
Jukka Kukkola ◽  
Juha Knuutinen ◽  
Jaakko Paasivirta ◽  
Sirpa Herve ◽  
Piia Pessala ◽  
...  
Keyword(s):  
Kraft Pulp ◽  
Size Exclusion ◽  
Chromatographic Study ◽  
Pulp Bleaching ◽  
Kraft Pulp Bleaching ◽  
Size Exclusion Chromatographic ◽  
Softwood Kraft Pulp

Effects of D0-stage temperature, pH, and kappa factor on chlorine dioxide decomposition and D0-(EP)-D1 bleaching performance for eucalypt pulps

TAPPI Journal ◽  
2016 ◽  
Vol 15 (4) ◽  
pp. 285-295 ◽  
Author(s):  
UMIT SEZGI ◽  
JANAINA RESENDE ◽  
LEWIS SHACKFORD ◽  
JORGE COLODETTE ◽  
MARCELA ANDRADE
Keyword(s):  
Chlorine Dioxide ◽  
Kraft Pulp ◽  
Significant Variable ◽  
Optimum Conditions ◽  
Pulp Bleaching ◽  
Elemental Chlorine ◽  
Kraft Pulp Bleaching ◽  
Eucalyptus Kraft Pulp ◽  
Hexenuronic Acid ◽  
Proper Operation

Mills have largely used chlorine dioxide (ClO2) for eucalyptus kraft pulp bleaching. Different mills have observed significant variation in ClO2 demand to reach full brightness (≥90 ISO). These large differences in ClO2 consumption derive from many factors. The most significant include differences in carryover loads and hexenuronic acid (HexA) contents and the level of chlorate formation across bleaching. Handling of pulp with high HexA content and ClO2 losses to chlorate can be minimized by proper operation of the ClO2 stages across the bleach plant. An oxygen delignified eucalyptus kraft pulp with a kappa of 10-12 units contains only 4-6 units actually derived from lignin. This scarce amount of lignin (0.6%-0.9%) is not able to consume high ClO2 doses and, as a consequence, the excess ClO2 applied can end up being converted into chlorate. Hence, proper optimization of ClO2 bleaching stages can save significant amounts of this oxidant. This study focused on optimizing ClO2 bleaching for a typical oxygen delignified eucalyptus kraft pulp of kappa number 11.7. Elemental chlorine free bleaching was carried out with the D0-(EP)-D1 sequence. The following conditions were varied in the D0 stage: temperature, end pH, and kappa factor. The results indicated that maximum ClO2 bleaching efficiency is achieved when minimum chlorate is formed, especially when ClO2 bleaching is adjusted in such a way that residual active chlorine is maintained to a minimum. The most significant variable affecting chlorate formation is pH; however, ClO2 doses (ClO2 concentration) also play a very important role. Chlorate formation is more intense in the D1 stage in relation to the D0 stage. Optimum conditions to run the D0 stage were 90°C, 3.5 pH, and 0.22 kappa factor.

Size exclusion chromatographic and UV-VIS absorption analyses of unbleached and bleached softwood kraft pulps using LiCl/1,3-dimethyl-2-imidazolidinone as a solvent

Holzforschung ◽  
2007 ◽  
Vol 61 (3) ◽  
pp. 236-241 ◽  
Author(s):  
Masahiro Yanagisawa ◽  
Akira Isogai
Keyword(s):  
Kraft Pulp ◽  
Total Yield ◽  
Degree Of Polymerization ◽  
Size Exclusion ◽  
Kraft Pulps ◽  
Residual Lignin ◽  
Light Scattering Detection ◽  
Exclusion Chromatography ◽  
Photodiode Array ◽  
Sulfite Pulp

Abstract Unbleached and bleached kraft pulps and holocellulose prepared from softwood were totally soluble in 8% LiCl/1,3-dimethyl-2-imidazolidinone (LiCl/DMI). The solutions were analyzed by size exclusion chromatography with photodiode array and multi-angle laser light scattering detection (SEC-PDA-MALLS). The mobile phase consisted of 1% LiCl/DMI. The degree of polymerization (DP) and DP distribution of the softwood kraft pulps were determined, as well as the DP distribution of residual lignins based on their UV-VIS absorption patterns. Changes in DP for kraft pulps after a conventional bleaching sequence were evaluated, and the residual lignins were analyzed in the same way. Approximately half of the residual lignin in unbleached and bleached kraft pulps was present in polysaccharide fractions with high DP, which represented approximately 90% of the total yield. Some characteristic differences in the UV-VIS absorption pattern were observed between kraft pulps bleached with oxygen and chlorine. DP, DP distribution of polysaccharides, and distribution of residual lignin were clearly different for unbleached kraft pulp, unbleached sulfite pulp, and holocellulose. An unbleached kraft pulp prepared from hardwood showed different properties to the corresponding softwood preparation. The UV-VIS absorption patterns due to residual lignins were also very characteristic for the various pulps and holocellulose.

scholarly journals Influence of bleaching technologies on the aerobic biodegradability of effluents from Eucalyptus kraft pulps factories

1999 ◽  
Vol 42 (3) ◽  
pp. 323-330 ◽  
Author(s):  
Gladys Vidal ◽  
Manuel Soto ◽  
Ramón Méndez ◽  
Juan Manuel Lema
Keyword(s):  
Specific Treatment ◽  
Oxygen Demand ◽  
Organic Load ◽  
Partial Substitution ◽  
Kraft Pulps ◽  
Pulp Bleaching ◽  
Chlorine Bleaching ◽  
Kraft Pulp Bleaching ◽  
Eucalyptus Kraft Pulp ◽  
Aerobic Biodegradability

Aerobic biodegradability of effluents from different Eucalyptus kraft pulp bleaching processes was studied. Bleaching effluents were obtained from: i) Chlorine Bleaching (CB) processes, with partial substitution of chlorine by chlorine dioxide and ii) Total Chlorine Free (TCF) processes. The overall biodegradability, in terms of Chemical Oxygen Demand (COD) was higher for TCF effluents (96-98%) than for CB ones (82-93%). Taking into account the higher organic load of CB effluents, this fact implied a much higher residual COD for them (100-180 mg/L) than for TCF effluents (10-30 mg/L). Furthermore, a refractory fraction of molecular weight higher than 43,000 Da was found in CB effluent, which implied the necessity of a further specific treatment. The toxicity was completely removed after the biological treatment

Behavior of xylans from Eucalyptus species. Part 1. The influence of structural features of eucalyptus xylans on their retention in kraft pulp

Holzforschung ◽  
2013 ◽  
Vol 67 (2) ◽  
pp. 115-122 ◽  
Author(s):  
Andréia S. Magaton ◽  
Teresa Cristina F. Silva ◽  
Jorge Luiz Colodette ◽  
Dorila Piló-Veloso ◽  
Flaviana Reis Milagres
Keyword(s):  
Average Molecular Weight ◽  
Structural Features ◽  
Kraft Pulping ◽  
Size Exclusion ◽  
Pulp Yield ◽  
Eucalyptus Species ◽  
H Nmr ◽  
Uronic Acid Content ◽  
Exclusion Chromatography ◽  
Hexenuronic Acid

Abstract 4-O-methylglucuronoxylans were isolated from the wood and pulp of different Eucalyptus species (E. dunni, E. grandis, E. nitens, E. urograndis and E. urophylla) and characterized by 1H NMR spectroscopy and size-exclusion chromatography (SEC). The content of 4-O-methylglucuronic acid (MeGlcA) varied between the eucalyptus species from 1.90 to 2.80 expressed as MeGlcA/10 xyloses, whereas in the pulp, the total uronic acid content was approximately 1.02, from which the half was hexenuronic acid (HexA). From the MeGlcA linked to the xylan chain 9–26% are substituted in position O-2 by hexose units. The Mw of the xylans extracted from wood ranged between 26.1 and 28.4 kDa. The retention of 4-O-methylglucuronoxylans (51.3–58.7%) during kraft pulping was high, and the retention is related to the content of MeGlcA group, the content of MeGlcA group substituted at O-2, and the average molecular weight of the xylans. The parameters observed affect the overall pulp yield and pulp properties.

scholarly journals Lignin fractionation as an efficient route for enhancing Polylactide thermal stability and flame retardancy

2018 ◽  
Vol 1 (1) ◽  
pp. 14-24 ◽  
Author(s):  
Lucie Costes ◽  
Mario Aguedo ◽  
Loic Brison ◽  
Sylvain Brohez ◽  
Aurore Richel ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Cone Calorimeter ◽  
Melt Processing ◽  
Size Exclusion ◽  
Lignin Fraction ◽  
Cone Calorimeter Test ◽  
Exclusion Chromatography ◽  
Fire Properties ◽  
Combustion Behaviors ◽  
Internal Mixer

Abstract Due to its variable botanical origin, functionality, reactivity, and heterogeneity, using lignin in industrial application is not an easy task. In the present study, we investigate the effect of lignin fractionation as a simple way for reducing the variability in its properties. Kraft lignin was separated by ultrafiltration membranes in two fractions with a specific molecular weight and the properties of each fraction were characterized through FTIR, XPS, TGA and cone calorimeter test. Lignin fractions display different thermal and combustion behaviors. Thus, the two fractions have been evaluated as flame retardant additives for polylactide (PLA). PLA composites, containing well dispersed lignin (20 wt%), were produced by melt blending in an internal mixer. The thermo-degradant effect of each fraction on PLA during melt processing was investigated by rheological analysis and size exclusion chromatography while the composites thermal stability and fire properties were evaluated using TGA and cone calorimeter test. Results showed that using appropriate lignin fraction enables for obtaining PLA composites presenting enhanced properties

The degradation of Indulin ATR by Streptomyces: chemical characterization of the water soluble acid precipitable products

1989 ◽  
Vol 67 (2) ◽  
pp. 350-355 ◽  
Author(s):  
P. F. Vidal ◽  
J. Bouchard ◽  
E. Chornet ◽  
R. P. Overend ◽  
H. Giroux ◽  
...  
Keyword(s):  
High Performance ◽  
Protein Complexes ◽  
Chemical Characterization ◽  
Water Soluble ◽  
Size Exclusion ◽  
Produce Water ◽  
Lignin Fraction ◽  
Exclusion Chromatography ◽  
Soluble Acid

Two strains of Streptomyces, S. badius and S. virdosporus, when incubated with kraft lignin (Indulin ATR) produce water soluble acid precipitable compounds. We show by a combination of elemental analysis, amino acid analysis, and FTIR that these are complexes of lignin fragments strongly associated with proteins. The latter, which can be separated by solvent extraction, are added by the microorganisms themselves. The lignin fraction, which represents approximately 60% of the complex weight, consists of lower molecular weight, lower methoxyl content Indulin fragments. KeyWords: lignin, Indulin, lignin–protein complexes, Fourier transform infrared spectrophotometry, high performance size exclusion chromatography, Streptomyces.

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