Lignin oxidation mechanisms under oxygen delignification conditions. Part 1. Results from direct analyses

Holzforschung ◽  
2011 ◽  
Vol 65 (4) ◽  
Author(s):  
Anna Kalliola ◽  
Susanna Kuitunen ◽  
Tiina Liitiä ◽  
Stella Rovio ◽  
Taina Ohra-aho ◽  
...  
Keyword(s):  
Lignin Degradation ◽  
Mechanistic Model ◽  
Quantitative Information ◽  
Kraft Lignin ◽  
Oxygen Delignification ◽  
Analysis Techniques ◽  
Softwood Kraft Lignin ◽  
Lignin Reactivity ◽  
Oxidation Mechanisms ◽  
Reactor Pressure

Abstract Oxidation of softwood and hardwood kraft lignins was observed under conditions of oxygen delignification (90°C and 110°C; 0.6 and 0.9 MPa) as a function of time by means of a number of analysis techniques and quantitative information was obtained on the degradation and formation of various compounds and structures. The decrease in reactor pressure was monitored during a 4-h reaction period. During the first 60 min, lignin reactivity was high, while a very intense stage took place during the first 20 min. The reactions decelerated after the first 60 min and after 120 min the reactions did not significantly advance. The oxygen consumption after 4-h reaction was 1.3–1.5 mole O2 per 1 mole lignin depending on the conditions. In the first 20 min, 50%–60% of the oxygen was consumed and the consumption increased only slightly after 60 min. At 90°C, the changes in all observed quantities were smaller throughout the whole 4-h reaction period than at 110°C. Under the studied conditions, increasing the reaction temperature, rather than the pressure, had primary significance in the increasing rate of lignin degradation. Hardwood kraft lignin was more reactive than softwood kraft lignin. The results obtained in this study are the basis for the development of a mechanistic model for the oxygen delignification process of pulps to be published in subsequent papers.

Bleaching ability of pre-hydrolyzed pulps in the context of a biorefinery mill

TAPPI Journal ◽  
2013 ◽  
Vol 12 (11) ◽  
pp. 49-53 ◽  
Author(s):  
CHRISTINE CHIRAT ◽  
LUCIE BOIRON ◽  
DOMINIQUE LACHENAL
Keyword(s):  
Carbon Content ◽  
Acid Hydrolysis ◽  
13C Nmr ◽  
Kraft Lignin ◽  
Kappa Number ◽  
Hydroxyl Groups ◽  
Kraft Pulps ◽  
Quaternary Carbon ◽  
Oxygen Delignification

Autohydrolysis and acid hydrolysis treatments were applied on mixed softwood chips. The cooking ability was studied by varying the alkali and duration of the cook. Pulps with kappa numbers varying from 30 to 70 were obtained. The bleaching ability of these pulps was studied and compared to control kraft pulps. The prehydrolyzed pulps were shown to be more efficiently delignified by oxygen than the control kraft pulps starting from the same kappa number. Furthermore, the final bleaching was also easier for these pulps. It was also shown that extensive oxygen delignification applied on high-kappa pre-hydrolyzed pulps could be a way to improve the overall yield, which is a prerequisite for the development of such biorefinery concepts. Lignin was isolated from the control kraft and the two pre-hydrolyzed kraft pulps and analyzed by 13C NMR. Lignins from pre-hydrolyzed kraft pulps had similar free phenolic groups content to the control kraft lignin, but their aliphatic hydroxyl groups and β-O-4 content were lower than for the control lignin. The quaternary carbon content was the same for all the samples.

scholarly journals Integrated quantitative PIXE analysis and EDX spectroscopy using a laser-driven particle source

2021 ◽  
Vol 7 (3) ◽  
pp. eabc8660
Author(s):  
F. Mirani ◽  
A. Maffini ◽  
F. Casamichiela ◽  
A. Pazzaglia ◽  
A. Formenti ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Materials Science ◽  
Quantitative Information ◽  
Pixe Analysis ◽  
Materials Analysis ◽  
Particle Source ◽  
X Ray ◽  
Analysis Techniques ◽  
Sample Structure ◽  
Elemental Characterization

Among the existing elemental characterization techniques, particle-induced x-ray emission (PIXE) and energy-dispersive x-ray (EDX) spectroscopy are two of the most widely used in different scientific and technological fields. Here, we present the first quantitative laser-driven PIXE and laser-driven EDX experimental investigation performed at the Centro de Láseres Pulsados in Salamanca. Thanks to their potential for compactness and portability, laser-driven particle sources are very appealing for materials science applications, especially for materials analysis techniques. We demonstrate the possibility to exploit the x-ray signal produced by the co-irradiation with both electrons and protons to identify the elements in the sample. We show that, using the proton beam only, we can successfully obtain quantitative information about the sample structure through laser-driven PIXE analysis. These results pave the way toward the development of a compact and multifunctional apparatus for the elemental analysis of materials based on a laser-driven particle source.

Degradation of natural and Kraft lignins by the microflora of soil and water

1977 ◽  
Vol 23 (4) ◽  
pp. 434-440 ◽  
Author(s):  
Don L. Crawford ◽  
Suellen Floyd ◽  
Anthony L. Pometto III ◽  
Ronald L. Crawford
Keyword(s):  
Molecular Weight ◽  
Microbial Degradation ◽  
Lignin Degradation ◽  
Kraft Lignin ◽  
Lignin Biodegradation ◽  
Incubation Periods ◽  
Molecular Weight Fractions ◽  
Soil And Water ◽  
Different Molecular Weight ◽  
Microbial Attack

The comparative rates of microbial degradation 14C-lignin-labeled lignocelluloses and 14C-Kraft lignins were investigated using selected soil and water samples as sources of microorganisms. Natural lignocelluloses containing 14C primarily in their lignin components were prepared by feeding plants uniformly labeled L-[14C]phenylalanine through their cut stems. 14C-Kraft lignins were prepared by pulping lignin-labeled lignocelluloses. Rates of lignin biodegradation were determined by monitoring 14CO2 evolution from incubation mixtures over incubation periods of up to 1000 h. Observed rates of lignin degradation were slow in all cases. Kraft lignins appeared more resistant to microbial attack than natural lignins, even though they were decomposed more rapidly during the first 100–200 h of incubation. Similar degradation patterns were observed in both soil and water. Individual samples, however, varied greatly in their overall rates of degradation of either lignin type. A Kraft-lignin preparation was separated into a variety of molecular weight fractions by column chromatography on LH-20 Sephadex and the biodegradability of the different molecular weight fractions determined. The lower molecular weight fractions of the Kraft lignin were decomposed at a significantly faster rate by the microflora of soil than were the fractions of higher molecular weight.

scholarly journals Improved Procedure for Electro-Spinning and Carbonisation of Neat Solvent-Fractionated Softwood Kraft Lignin

2021 ◽  
Author(s):  
Inam Khan ◽  
Bongkot Hararak ◽  
Gerard Franklyn Fernando
Keyword(s):  
Cross Section ◽  
Circular Cross Section ◽  
Kraft Lignin ◽  
Binary Solvent ◽  
Natural Polymers ◽  
Solvent Fractionation ◽  
Custom Made ◽  
Treatment Procedures ◽  
Softwood Kraft Lignin ◽  
Soluble Lignin

Abstract In general, the electro-spinning of lignin requires it to be functionalised and/or blended with synthetic or natural polymers. This paper reports on the use of solvent fractionated lignin-lignin blend to electro-spin BioChoice® softwood Kraft lignin. The blend consisted of acetone-soluble and ethanol-soluble lignin in a binary solvent of acetone and DMSO. Solvent fractionation was used to purify lignin where the ash content was reduced in the soluble lignin fractions from 1.24% to ~0.1%. The corresponding value for conventional acid-washing in sulphuric acid was 0.34%. A custom-made electro-spinning apparatus was used to produce the nano-fibres. Heat treatment procedures were developed for drying the electro-spun fibres prior to oxidation and carbonisation; this was done to prevent fibre fusion. The lignin fibres were oxidised at 250⁰C, carbonised at 1000⁰C and 1500⁰C. The cross-section of the fibres was circular and they were observed to be void-free. The longitudinal sections showed that the fibres were not fused. Thus, this procedure demonstrated that solvent fractionated lignin can be electro-spun without using plasticisers or polymer blends using common laboratory solvents and subsequently carbonised to produce carbon fibres with a circular cross-section.

Gas dispersion in the oxygen delignification process

TAPPI Journal ◽  
2021 ◽  
Vol 20 (5) ◽  
pp. 311-318
Author(s):  
JARI KAYHKO ◽  
HEIKKI MUTIKAINEN ◽  
KARI PELTONEN ◽  
RIKU KOPRA ◽  
MARKUS HONKANEN
Keyword(s):  
Bubble Size ◽  
Oxygen Delignification ◽  
Noticeable Effect ◽  
Gas Dispersion ◽  
New Information ◽  
Oxygen Bubble ◽  
The Mean ◽  
Mixer Rotation ◽  
Reactor Pressure

There has been very little knowledge about the state of gas dispersion in the oxygen delignification process, even though this has a major impact on the performance of the reactor. This paper presents a new continu-ous inline method for measuring oxygen bubble size distribution in the reactor, as well as results from studies con-ducted in softwood and hardwood lines. This new measurement worked well, and new information about oxygen bubble size, as well as how different reactor conditions affected the distribution, was obtained. For example: • In the softwood line, the mean volume-weighted bubble size was about 0.1 mm, whereas in the hardwood line, this size was almost 10 times higher. For both lines, there was considerable variation in the measured bubble size over the long term. • For both lines, an increase in mixer rotation speed caused a discernible decrease in the bubble size, and an increase in oxygen charge caused a discernible increase in the bubble size. • In the softwood line, no coalescence of the bubbles in the reactor was observed, but in the hardwood line, some coalescence of the larger bubbles occurred. • In the test conducted in the hardwood line, the use of brownstock washer defoamer caused a discernible increase in oxygen bubble size. • In the hardwood line, reactor pressure had a noticeable effect on the amount of delignification, which indicated that improving mass transfer of oxygen (e.g., by decreasing the oxygen bubble size, in this case) should also have an increasing effect on the delignification.

Methylation of softwood kraft lignin with dimethyl carbonate

2015 ◽  
Vol 17 (2) ◽  
pp. 1077-1087 ◽  
Author(s):  
Sanghamitra Sen ◽  
Shradha Patil ◽  
Dimitris S. Argyropoulos
Keyword(s):  
Thermal Stability ◽  
Dimethyl Carbonate ◽  
Kraft Lignin ◽  
Softwood Kraft Lignin

Methylation of lignin is essential for inducing thermal stability when a multitude of thermoplastic applications are envisaged.

Breaking the Oxygen Delignification Barrier: Lignin Reactivity and Inactivity

2001 ◽  
pp. 92-107 ◽  
Author(s):  
Lucian A. Lucia ◽  
Michael M. Goodell ◽  
Fadi S. Chakar ◽  
Arthur J. Ragauskas
Keyword(s):  
Oxygen Delignification ◽  
Lignin Reactivity

Carbohydrate-free and highly soluble softwood kraft lignin fractions by aqueous acetone evaporation fractionation

2017 ◽  
Vol 32 (4) ◽  
pp. 485-492 ◽  
Author(s):  
Anna-Stiina Jääskeläinen ◽  
Pia Willberg Keyriläinen ◽  
Tiina Liitiä ◽  
Tarja Tamminen
Keyword(s):  
Kraft Lignin ◽  
Aqueous Acetone ◽  
Softwood Kraft Lignin

scholarly journals Insights into the Potential of Hardwood Kraft Lignin to Be a Green Platform Material for Emergence of the Biorefinery

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1795
Author(s):  
Juliana M. Jardim ◽  
Peter W. Hart ◽  
Lucian Lucia ◽  
Hasan Jameel
Keyword(s):  
Research And Development ◽  
Polymer Blends ◽  
Carbon Fibers ◽  
Aromatic Compounds ◽  
Critical Review ◽  
Black Liquor ◽  
Kraft Lignin ◽  
Softwood Kraft Lignin ◽  
Structure Properties

Lignin is an abundant, renewable, and relatively cheap biobased feedstock that has potential in energy, chemicals, and materials. Kraft lignin, more specifically, has been used for more than 100 years as a self-sustaining energy feedstock for industry after which it has finally reached more widespread commercial appeal. Unfortunately, hardwood kraft lignin (HWKL) has been neglected over these years when compared to softwood kraft lignin (SWKL). Therefore, the present work summarizes and critically reviews the research and development (R&D) dealing specifically with HWKL. It will also cover methods for HWKL extraction from black liquor, as well as its structure, properties, fractionation, and modification. Finally, it will reveal several interesting opportunities for HWKL that include dispersants, adsorbents, antioxidants, aromatic compounds (chemicals), and additives in briquettes, pellets, hydrogels, carbon fibers and polymer blends and composites. HWKL shows great potential for all these applications, however more R&D is needed to make its utilization economically feasible and reach the levels in the commercial lignin market commensurate with SWKL. The motivation for this critical review is to galvanize further studies, especially increased understandings in the field of HWKL, and hence amplify much greater utilization.

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