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Valorization of Kraft Lignin by Fractionation and Chemical Modifications for Different Applications
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. (Wallenberg Wood Science Center)
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Abstract

Lignin is one of the most abundant biopolymers. Approximately 70 million tons of technical lignin is generated annually, but only little is used for products other than energy. The complexity of lignin hinders full utilization in high-value products and materials. In spite of the large recent progress of knowledge of lignin structure and biosynthesis, much is still not fully understood, including structural inhomogeneity. We made synthetic lignin at different pH’s and obtained structural differences that might explain the structural inhomogeneity of lignin.

Technical lignins from the chemical pulping are available in large scale, but the processes result in alterations, such as oxidation and condensation. Therefore, to utilize technical lignin, modifications, such as fractionation and/or chemical modifications are necessary. Fractionation with ceramic membranes is one way to lower the polydispersity of lignin. The main advantage is their tolerance towards high temperature and harsh conditions. We demonstrated that low Mw lignin was extracted from industrially produced LignoBoost lignin aiming: i) to investigate the performance of the membrane over time; ii) to analyze the antioxidant properties of the low Mw lignin.

Chemical modification can also improve the properties of lignin. By adding moieties, different properties can be obtained. Amination and methacrylation of kraft lignin were performed, as well as lignin-silica hybrid materials with potential for the adsorption were produced and investigated.

Non-modified and methacrylated lignin were used to synthesize lignin-St-DVB porous microspheres to be utilized as a sorbent for organic pollutants. The possibility to substitute styrene with methacrylated lignin was evaluated, demonstrating that interaction between lignin and DVB, and porosity increased.

Lignin has certain antibacterial properties. Un-modified and modified (aminated) lignin samples and sphere nanoparticles of lignin were tested for their effect against gram-positive and gram-negative bacteria’s and an injectable hydrogel was developed with encapsulated lignin for being used as an injectable gel for the open wounds. Results demonstrated promising antibacterial efficiency of lignins against gram-positive, more especially better inhibition with aminated lignins against gram-positive and negative bacterium.

 

 

Abstract [sv]

SAMMANFATTNING

Lignin är en av de mest förkommande biopolymererna och ca 70 miljoner ton av tekniskt lignin produceras årligen, men endast en mindre del används till andra applikationer än energiproduktion. Ett hinder för användning av lignin i mer komplexa produkter och material är dess komplexa struktur. Trotts senare års stora framsteg när det gäller kunskap om ligninets struktur, är mycket alltjämt dåligt förstått, exempelvis angående den strukturella inhomogeniteten hos lignin. Vi har studerat detta genom att göra syntetiskt lignin vid olika pH, och erhöll strukturella skillnader som kan vara en förklaring till den strukturella inhomogeniteten.

Tekniska ligniner från kemisk massatillverkning är tillgängliga i stor skala, men processerna resulterar i strukturella modifieringar hos ligninet, såsom oxidationer och kondensationer. Därför är fraktionering och modifiering av tekniskt lignin lämpligt. Fraktionering med hjälp av keramiska membran är ett sätt att minska polydisperiteten hos lignin. Den största fördelen är membranens stora tolerans mot höga temperatur och aggressiva kemikalier. Vi använde filtrering på keramiska membran för att framställa lågmolekylärt lignin från den industriella kvaliteten LignoBoost, för att utvärdera membranens prestanda över tid, och analysera antioxidantegenskaperna hos det lågmolekylära ligninet.

Kemisk modifiering kan också användas för att förbättra egenskaperna hos lignin. Genom att koppla på grupper, kan egenskaperna ändras. Amidering och metakrylering av sulfatlignin utfördes liksom tillverkning av lignin-silikon-hybridmaterial, med potential för adsorption, och materialen undersöktes.

Omodifierat och metakrylerat lignin användes tillsammans med styren för att syntetisera porösa mikrosfärer som testades som absorbent för organiska föroreningar. Utvärdering visade att metakrylering ökade interaktionen mellan lignin och polystyren och ökade porositeten.

Lignin har viss antimikrobiell aktivitet. Omodifierade och amiderade ligninprover och sfäriska nanopartiklar av lignin testades för sin verkan mot gram-positiva och gram-negativa bakterier. Resultaten visade lovande resultat för antimikrobiell aktivitet, och särskilt för amiderade ligniner när det gäller grampositiva bakterier. En injicerbar hydrogel med inkapslat lignin utvecklades också för behandling av öppna sår.

 

 

Place, publisher, year, edition, pages
Stockholm, Sweden: KTH Royal Institute of Technology, 2018. , p. 92
Series
TRITA-CBH-FOU ; 2018-61
Keywords [en]
Lignin Valorization- LignoBoost Lignin-Clean Flow Black Lignin- Characterization-Chemical modifications-Fractionation-applications
National Category
Paper, Pulp and Fiber Technology
Research subject
Chemical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-239356ISBN: 978-91-7873-046-9 (print)OAI: oai:DiVA.org:kth-239356DiVA, id: diva2:1264845
Public defence
2018-12-14, F3, Lindstedtsvägen 26, Stockholm, 14:00 (English)
Opponent
Supervisors
Note

QC 20181122

Available from: 2018-11-22 Created: 2018-11-21 Last updated: 2018-11-26Bibliographically approved
List of papers
1. A possible explanation for the structural inhomogeneity of lignin in LCC networks
Open this publication in new window or tab >>A possible explanation for the structural inhomogeneity of lignin in LCC networks
2017 (English)In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 51, no 6, p. 1365-1376Article in journal (Refereed) Published
Abstract [en]

Lignin has a very complex structure, and this is partly due to the monomers being connected by many different types of covalent bonds. Furthermore, there are multiple covalent bonds between lignin and polysaccharides in wood, and it is known that the structure of lignin covalently bound to the hemicellulose xylan is different to lignin bound to the hemicellulose glucomannan. Here, synthetic lignin (DHP) is synthesized at different pH and it is shown that lignin made at lower pH has a structure more similar to the lignin bound to xylan, i.e., having higher relative content of beta-O-4 ethers. It is hypothesized that xylan due to its carboxylic acids forms a locally lower pH and thus "direct" the lignin structure to have more beta-O-4 ethers. The biological significance of these results is discussed.

Place, publisher, year, edition, pages
SPRINGER, 2017
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-217020 (URN)10.1007/s00226-017-0941-6 (DOI)000413010900008 ()2-s2.0-85021955403 (Scopus ID)
Note

QC 20171124

Available from: 2017-11-24 Created: 2017-11-24 Last updated: 2018-11-22Bibliographically approved
2. Membrane filtration of kraft lignin: Structural charactristics and antioxidant activity of the low-molecular-weight fraction
Open this publication in new window or tab >>Membrane filtration of kraft lignin: Structural charactristics and antioxidant activity of the low-molecular-weight fraction
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2018 (English)In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 112, p. 200-209Article in journal (Refereed) Published
Abstract [en]

Lignin, which is the second most abundant biomass component and has carbon-rich phenolic content, is a promising renewable raw material for multiple applications, such as carbon fibers, adhesives, and emulsifiers. To use lignin efficiently, it is important to ensure its purity and homogeneity. As a result, the separation of lignin into fractions with high purity and narrow molecular-weight distributions is likely a prerequisite for several applications. Ultrafiltration using ceramic membranes has many advantages, including enabling direct lignin extraction from Kraft pulp cooking liquors without pH and temperature adjustment. One challenge with membrane filtration using such a system is the potential for reduced membrane performance over time, which is associated with fouling. In this study, LignoBoost Kraft lignin was fractionated using a ceramic membrane with a molecular weight cut-off of 1 kDa. The separation behavior during ultrafiltration fractionation was investigated and the antioxidant properties of the recovered low-molecular-weight (low-MW) lignin samples were evaluated. Using this model system, the permeate fluxes were unstable during the 100 h of membrane operation. However, a decrease in the average MW in the permeate over time was observed. The shift in MW was most pronounced for virgin membranes, while a more stable MW distribution was evident for membranes subjected to multiple cleaning cycles. According to 2D NMR analysis, low-MW lignin that was recovered after 100 h of operation, consisted of smaller lignin fragments, such as dimers and oligomers, with a high content of methoxy-groups. This was confirmed using the size exclusion chromatography method, which indicated an weigh average molecular weight in the range of 450–500 Da. 31P NMR spectroscopy showed that, despite the lower total content of phenolic OH groups, the low-MW sample had a higher proportion of non-condensed phenolic OH groups. The results of the antioxidant tests demonstrated the strong potential of lignin and its low-MW fraction as a natural antioxidant, particularly for lipid-containing systems. The low-MW lignin fraction showed better antioxidant activity than the non-fractionated LignoBoost lignin in the kinetic oxygen radical absorbance capacity (ORAC) test and demonstrated three-fold stronger inhibition of the substrate (fluorescein) than the reference antioxidant Trolox (a water-soluble derivative of vitamin E).

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Antioxidant activity, LignoBoost lignin, Low-MW lignin, Structural analysis, Ultrafiltration
National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-220194 (URN)10.1016/j.indcrop.2017.11.042 (DOI)000425561900026 ()2-s2.0-85036614166 (Scopus ID)
Note

QC 20171218

Available from: 2017-12-18 Created: 2017-12-18 Last updated: 2018-11-22Bibliographically approved
3. Peculiarities of synthesis and properties of lignin-silica nanocomposites prepared by sol-gel method
Open this publication in new window or tab >>Peculiarities of synthesis and properties of lignin-silica nanocomposites prepared by sol-gel method
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2018 (English)In: Nanomaterials, Vol. 8, no 11, p. 1-18Article in journal (Refereed) Published
Abstract [en]

The development of advanced hybrid materials based on polymers from biorenewable sources and mineral nanoparticles is currently of high importance. In this paper, we applied softwood kraft lignins for the synthesis of lignin/SiO2 nanostructured composites. We described the peculiarities of composites formation in the sol-gel process through the incorporation of the lignin into a silica network during the hydrolysis of tetraethoxysilane (TEOS). The initial activation of lignins was achieved by means of a Mannich reaction with 3-aminopropyltriethoxysilane (APTES). In the study, we present a detailed investigation of the physicochemical characteristics of initial kraft lignins and modified lignins on each step of the synthesis. Thus, 2D-NMR, 31P-NMR, size-exclusion chromatography (SEC) and dynamic light scattering (DLS) were applied to analyze the characteristics of pristine lignins and lignins in dioxan:water solutions. X-Ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) were used to confirm the formation of the lignin–silica network and characterize the surface and bulk structures of the obtained hybrids. Termogravimetric analysis (TGA) in nitrogen and air atmosphere were applied to a detailed investigation of the thermal properties of pristine lignins and lignins on each step of modification. SEM confirmed the nanostructure of the obtained composites. As was demonstrated, the activation of lignin is crucial for the sol-gel formation of a silica network in order to create novel hybrid materials from lignins and alkoxysilanes (e.g., TEOS). It was concluded that the structure of the lignin had an impact on its reactivity during the activation reaction, and consequently affected the properties of the final hybrid materials.

Place, publisher, year, edition, pages
MDPI, 2018
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-239348 (URN)10.3390/nano8110950 (DOI)
Note

QC 20181122

Available from: 2018-11-21 Created: 2018-11-21 Last updated: 2018-11-22Bibliographically approved
4. Methylene Blue dye sorption by hybrid materials from technical lignins
Open this publication in new window or tab >>Methylene Blue dye sorption by hybrid materials from technical lignins
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2018 (English)In: Journal of Environmental Chemical Engineering, ISSN 2160-6544, E-ISSN 2213-3437, Vol. 6, no 4, p. 4997-5007Article in journal (Refereed) Published
Abstract [en]

New hybrid sorbents were synthesized from technical lignins and silica and were applied for the removal of Methylene Blue dye (MB) from aqueous solution. Kraft softwood lignins from LignoBoost (LBL) and CleanFlowBlack (CFBL) processes were used to understand the influence of molecular weight and functionality of initial lignins on the properties of the final hybrids. The synthesized materials were applied as adsorbents for the removal of MB from aqueous solutions. The effects of parameters such as contact time, initial concentration of dye and initial pH on the adsorption capacity were evaluated. The hybrids exhibited higher adsorption capacity than the initial macromolecules of lignin with respect to MB. The hybrid based on CFBL exhibited an adsorption capacity of 60 mg/g; this value was 30% higher than the capacity of the hybrid based on LBL, which was 41.6 mg/g. Lignin hybrid materials extract 80-99% of the dye in a pH range from 3 to 10. The equilibrium and kinetic characteristics of MB uptake by the hybrids followed the Langmuir isotherm model and pseudosecond-order model, rather than the Freundlich and Temkin models, the pseudo-first-order or the intraparticle diffusion model. The attachment of the dye to the hybrid surface was confirmed via FE-SEM and FTIR spectroscopy. The mechanism for MB adsorption was proposed. Due to the high values of regeneration efficiency of the surface of both lignin-silica hybrid materials in 0.1 M HCl (up to 75%) and ethanol (99%), they could be applied as effective sorbents in industrial wastewater treatment processes.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Lignin, Silica, Hybrids, Adsorption, Methylene Blue dye, Water treatment
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:kth:diva-235458 (URN)10.1016/j.jece.2018.07.041 (DOI)000444046700127 ()2-s2.0-85050740163 (Scopus ID)
Funder
Knut and Alice Wallenberg Foundation
Note

QC 20180928

Available from: 2018-09-28 Created: 2018-09-28 Last updated: 2018-11-22Bibliographically approved
5. Synthesis and structure characterization of polymeric nanoporous microspheres with lignin
Open this publication in new window or tab >>Synthesis and structure characterization of polymeric nanoporous microspheres with lignin
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2018 (English)In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, no 10, p. 5843-5862Article in journal (Refereed) Published
Abstract [en]

Nanoporous microspheres with divinylbenzene (DVB), styrene (St), and lignin were synthesized by an emulsion-suspension polymerization method. Several types of lignins were used: (1) kraft lignin before (L-unmod) and after modification with methacryloyl chloride (L-Met) and (2) low-molecular-weight kraft lignin unmodified (LWL-unmod) and modified with methacrylic anhydride (LWL-Met). LWL was prepared by ultrafiltration of industrial black liquor using a ceramic membrane with a molecular weight (Mw) cut-off of 5 kDa. The synthesis was optimized by addition of different amounts of lignins. The microsphere texture was characterized using low-temperature nitrogen adsorption and small angle X-ray scattering analyses. The microspheres were nano- and mesoporous with a specific surface area in the range of 0.1-409 m(2)/g. The morphology of the copolymers was studied using field emission scanning electron microscopy and atomic force microscopy. The thermal properties were studied using differential scanning calorimetry and thermogravimetric analysis methods. A significant difference in the microsphere roughness is affected by lignins due to the presence of lignin nanoparticles at the surface of the microspheres. Molecular modeling was used to predict the sorption properties of the copolymers affected by various fields around the particles. The particle size, polydispersity and zeta potential of the St + DVB, L-Met + St + DVB and L-unmod + St + DVB samples were measured by dynamic light scattering. Additionally, the point of zero charge of the samples was determined using potentiometric titration. The materials studied have a great potential for sorption processes due to their developed porosity and the presence of a number of active surface functionalities. [GRAPHICS] .

Place, publisher, year, edition, pages
SPRINGER, 2018
Keywords
Lignin, Chemical modification, Composites, Microspheres, Nanopores, Sorption process
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-235564 (URN)10.1007/s10570-018-2009-7 (DOI)000444769300027 ()2-s2.0-85052302119 (Scopus ID)
Note

QC 20181001

Available from: 2018-10-01 Created: 2018-10-01 Last updated: 2018-11-22Bibliographically approved
6. Lignin based hydrogel for the antibacterial application
Open this publication in new window or tab >>Lignin based hydrogel for the antibacterial application
Show others...
(English)Manuscript (preprint) (Other academic)
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:kth:diva-239424 (URN)
Note

QC 20181122

Available from: 2018-11-22 Created: 2018-11-22 Last updated: 2018-11-22Bibliographically approved

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Available from 2019-11-22 11:08

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