Stefan M Willför

Stefan M Willför
  • Åbo Akademi University

About

261
Publications
101,733
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
13,080
Citations
Current institution
Åbo Akademi University

Publications

Publications (261)
Conference Paper
Full-text available
In our previous papers, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and pyrolysis coupled with gas chromatography-mass spectroscopy (Py-GC-MS) techniques were used to investigate the thermochemical conversion of the agricultural biomass, namely the of oilseed rape (Brassica napus L.) and of the Spanish broom (Spartium...
Article
In the context of three-dimensional (3D) cell culture and tissue engineering, 3D printing is a powerful tool for customizing in vitro 3D cell culture models that are critical for understanding the cell-matrix and cell-cell interactions. Cellulose nanofibril (CNF) hydrogels are emerging in constructing scaffolds able to imitate tissue in a microenvi...
Article
Full-text available
Fabricating bio‐latex colloids with core–shell nanostructure is an effective method for obtaining films with enhanced mechanical characteristics. Nano‐sized lignin is rising as a class of sustainable nanomaterials that can be incorporated into latex colloids. Fundamental knowledge of the correlation between surface chemistry of lignin nanoparticles...
Article
The valorization of industrial lignin essentially requires fractionation resulting in lower structural heterogeneity and polydispersity. So far, extensive fractionation approaches based on extraction with solvents, gradient acid precipitation, and membrane-based filtration have been developed to reduce the polydispersity and heterogeneity of techni...
Article
Continuous filtering adsorption has drawn growing interest in the exploration of uranium resources in seawater and reduction in the environmental risks of uraniferous wastewater from nuclear industries. For most filtering adsorbents, repeated filtration, high membrane thickness, and high pressure are normally essential to achieve both a high reject...
Article
To date, the energy-intensive production and high-water content severely limits nanocellulose applications on a large scale off-site. In this study, adding water-soluble polysaccharides (PS) to achieve an integrated process of water-redispersible nanocellulose production was well established. The addition of PS, in particular carboxymethylated-gala...
Article
In this work, we synthesized new bio-composites as adsorbents to remove methylene blue (MB) from aqueous solutions. These hydrogels, based on 2-hydroxyethylmethacrylate (HEMA), were prepared by free-radical copolymerization with itaconic acid (IA) or acrylic acid (AA) monomers in combination with different amounts of cellulose nanofiber (CNF). The...
Article
Full-text available
In analogue to the biorefinery concept, the separation process of lignocellulosic biomass is the most critical step to obtain its main components, namely cellulose, hemicelluloses and lignin. Moreover, the applied fractionation approach has a decisive impact on the characteristics and subsequent valorization strategies of the distinguished fraction...
Article
It is significant to develop new adsorbents with excellent adsorption performance and convenient operation ability for removing pollutants from wastewater owing to the growing environmental problems. In this paper, a novel ultralight aerogel-based adsorbent with highly porous structure and good mechanical integrity was fabricated based on the inter...
Article
The efficient extraction of the aquatic uranium element has drawn growing research interest because of its importance for both nuclear energy acquirement and water environmental remediation. Large-capacity, rapid filtration adsorption is promising, but remains challenging in capturing aquatic uranium ions. Herein, cyanoethyl substitution was found...
Article
Full-text available
Lithography-based digital light processing (DLP) 3D printing has gained increasing interest in the fabrication of custom-designed hydrogel scaffolds. Current research development calls for the versatility of the bio-based resin formulations...
Article
Bark wastes today are viewed as a high-value resource for biorefinery due to their chemical richness and diversity. This work presents a comprehensive chemical characterization of the inner bark and the outer bark of Eucalyptus camaldulensis cultivated in Algeria. The extractives were first isolated with an Accelerated Solvent Extractor (ASE) and t...
Article
The result of this study is the chemical characterization of sapwood (SW) and heartwood (HW) of Fraxinus angustifolia native to Algeria. Lipophilic and hydrophilic extractives were isolated by means of an accelerated solvent extractor (ASE) using hexane and the acetone/water mixture respectively. The acid hydrolysis and methanolysis methods were us...
Article
Full-text available
Industrial lignin fractionation is attracting increasing interest due to its enormous potential in the development of high value-added materials. However, the widely reported fractionation approaches are primarily focused on the separation of fractions with a low polydispersity index (PDI). In this study, based on the detailed characteristic examin...
Article
We propose an injectable nanocomposite hydrogel that is photo-curable via light-induced thiol-ene addition between methacrylate modified O-acetyl-galactoglucomannan (GGMMA) and thiolate cellulose nanocrystal (CNC-SH). Compared to free-radical chain polymerization, the orthogonal step-growth of thiol-ene addition allows a less heterogeneous hydrogel...
Article
In the present work, new biocomposite hydrogels were prepared based on the vinyl monomer 2-methacroyloxyethyltrimethyl ammonium chloride (ClAETA) in the presence of nanofibrillated cellulose (CNF) for the removal of the emerging contaminant nafcillin sodium monohydrate (NFX). The hydrogels were synthesized via free radicals, with the amount of CNF...
Article
Full-text available
Knowledge about the carbohydrate composition of pulp and paper samples is essential for their characterization, further processing, and understanding the properties. In this study, we compare sulfuric acid hydrolysis and acidic methanolysis, followed by GC-MS analysis of the corresponding products, by means of 42 cellulose and polysaccharide sample...
Article
Full-text available
Two series of well-defined lignin fractions derived from birch and spruce alkaline lignin (AL) by sequential solvent fractionation (i-PrOH-EtOH-MeOH) were engaged in a structure–property-application relationship study. The bacterial-derived alkaliphilic laccase (MetZyme) extensively catalyzed the oxidation and polymerization of AL fractions in an a...
Article
In Betula celtiberica (Iberian white birch) stemwood, the content and composition of lipophilic and hydrophilic extractives were determined; these have not been reported previously in this species. The total gravimetric amount of extractives was 2.2% of dry wood, of which lipophilic extractives accounted for 0.39% and hydrophilic extractives 1.84%...
Article
Full-text available
Hydrogels with ion exchange properties were synthesized from compounds derived from wood biopolymer hemicellulose and from commercial vinyl monomers to be tested as active materials for the removal of Cu(II), Cr(VI), and As(V) ions. The hemicellulose O-acetyl galactoglucomannan (GGM) was used as the precursor material, and through a transesterifica...
Article
Full-text available
The main goal of the study was to examine and compare the inhibition effect of knotwood extractives of Scots (Pinus sylvestris) and black pine (Pinus nigra) against the two white-rot fungi and two brown-rot fungi. Knotwood was extracted in a Sox-hlet apparatus. Extracts were chemically analyzed, and the inhibitory effect of purified pinosylvins and...
Article
Full-text available
The effectiveness of pressurized hot-water extraction conditions for obtaining galactoglucomannans (GGMs) from Pinus halepensis suitable for applications like coatings and films packaging was investigated. For this purpose, high molar masses with high yields are required, presenting a serious challenge for hot-water extraction processes. The extrac...
Article
Full-text available
Hazelnut (HS) and walnut (WS) shells, an abundant by-product of the processing industries of these edible nuts, are traditionally considered as a low-value waste. However, they are a source of valuable compounds with an interesting chemical profile for the chemical and pharmaceutical sectors. In this study, the lipophilic and hydrophilic extracts p...
Article
Full-text available
The 1,4-linked glucans such as xyloglucan and amylose are known to form a complex with iodine/iodide ions and to also be precipitated with CaCl2 in the presence of iodine. Here, we show that iodine gas could be specifically incorporated into xyloglucan. Furthermore, we show that [¹²⁵I]I2 gas is, over time, incorporated at high levels into the entir...
Article
An efficient separation technology for hydrolysates towards a full valorization of bamboo is still a tough challenge, especially regarding the lignin and lignin-carbohydrate complexes (LCCs). The present study aimed to develop a facile approach using organic solvent extraction for efficiently fractionating the main components of bamboo hydrolysates...
Article
Full-text available
Aiming at tailoring the bonding strength of a thermosetting lignin-containing phenol-formaldehyde (LPF) wood adhesive, different fractions of an industrial hardwood alkaline lignin have been prepared through sequential solvent fractionation (i-PrOH, EtOH, and MeOH). Those fractions were comprehensively characterized by GPC, GC, Py/GC-MS, and NMR te...
Article
In this work we present a green method to prepare aerogel membranes based on cellulose nanofibers (CNFs) crossed-linked with poly (ethylene imine) (PEI) and further decorated with silver nanoparticles (Ag NPs). The nanosized Ag NPs were reduced and immobilized on the surface of the pore walls inside the aerogel. The as-prepared composite aerogel me...
Article
Full-text available
Many of current bio-based materials are not fully or partly used for material utilization, as the composition of their raw materials and/or possible applications are unknown. This study deals with the analysis of the wood extractives from three different tissue of larch wood: Sapwood mainly from outer part of the log, and sound knotwood as well as...
Article
Full-text available
Bark of Norway spruce (Picea abies [L.] Karst.) trees contains large amounts of polyphenolic stilbene glucosides. Stilbene-rich bark extracts could be utilized as e.g., preservatives due to their antioxidative, antifungal, and antibacterial properties. As stilbenes are photosensitive compounds, ultraviolet (UV) light induces a well-known intramolec...
Article
In this work nanocellulose substrates e. g. cellulose nanofibrils and nanocrystals were isolated from an abundant renewable resource Ampelodesmos mauritanicus fibers. Cellulose nanocrystals CNCs were isolated from the fibers by means of acid hydrolysis while cellulose nanofibrils (CNFs) were isolated by combination of TEMPO-mediated oxidation and m...
Article
Full-text available
Suberin fatty acids were extracted from outer bark of Silver birch (Betula pendula Roth.) using an isopropanolic sodium hydroxide solution. Laboratory sheets composed of lignocellulosic fiber networks were prepared from unbleached and unrefined softwood kraft pulp and further impregnated with suberin fatty acid monomers and cured with maleic anhydr...
Article
The main aim of this study was to chemically characterise the polymeric fraction of birch pulp extractives. We showed that 70–96% of the material in extracts of fully bleached birch kraft elemental chlorine-free (ECF) pulp from three Finnish mills consists of compounds that are undetectable by conventional gas chromatography (GC) analysis, i.e. hig...
Article
Full-text available
See https://ojs.cnr.ncsu.edu/index.php/BioRes/article/view/BioRes_14_3_5807_Wagner_Identification_Antimicrobial_Compounds_Larch. Larch bark is an undervalued material, but it has unique and valuable characteristics and compounds. The objective of this study was to extract and characterize molecular compounds of bark materials from different larch...
Article
Several physical and chemical properties of waste fish oils (FOs) and used cooking oils (UCOs) were of acceptable levels for utilization as renewable fuels in marine engines. However, the relatively high acid number of FOs and its increase with ageing might lead to increased risk of corrosion. The physical properties density and kinematic viscosity...
Article
Full-text available
Owing to their superior mechanical strength and structure similarity to extracellular matrix (ECM), nanocelluloses as a class of emerging biomaterials have attracted great attention in 3D bioprinting to fabricate various tissue mimics. Yet, when printing complex geometries, the desired ink performance in terms of shape fidelity and object resolutio...
Article
Full-text available
Wood biorefining currently involves large-scale industrial processes where a notable portion of raw materials, namely hemicelluloses and lignin, are either lost with the process water, degraded, or burnt for energy. Value-added utilization of polymeric hemicelluloses is challenging due to their intermediate molar mass and the presence of other wood...
Article
To achieve full utilization of lignocellulosic biomass and easy integration of nanomaterials production, it is essential to develop an efficient fractionation to overcome the highly recalcitrant nature of lignocellulose and facilitate the subsequent valuable conversion. Herein, in a combined process based on the formic acid rapid-fractionation of b...
Article
Full-text available
Cellulose nanofibrils (CNFs) in the form of hydrogels stand out as a platform biomaterial in bioink formulation for 3D printing because of their low cytotoxicity and structural similarity to extracellular matrices. In the present study, 3D scaffolds were successfully printed with low-concentration inks formulated by 1 w/v % 2,2,6,6-tetramethylpiper...
Article
Full-text available
Main conclusion Poplar trees displayed an increased plant height due to the transgenic knockdown of PCBER1, a gene of lignan biosynthesis. The wood composition was slightly altered in both overexpression and knockdown lines. The gene PHENYLCOUMARAN BENZYLIC ETHER REDUCTASE1 (PCBER1) is well known as an important gene in the synthesis of lignans, a...
Article
Full-text available
In this work we have analyzed the pine and spruce softwood lignin fraction recovered from a novel pressurized hot water extraction pilot process. The lignin structure was characterized using multiple NMR techniques and the thermal properties were analyzed using thermal gravimetric analysis. Acetylated and selectively methylated derivatives were pre...
Article
Full-text available
Hemicelluloses, the second most abundant polysaccharides right after cellulose, represent complex biopolymers whose structural features are not yet fully understood. Hence, the applicability of functionalized hemicellulose derivatives is still limited. Thus, the development of practical methods to reveal their structure is essential. Anionic, carbo...
Article
The aim of the study was to find appropriate non-chlorinated solvent systems for the extraction and separation of pure pinosylvin (PS) and pinosylvin monomethylether (PSMME) from Scots pine/Norway spruce wood residues. The extraction was performed in a pressurized solvent extractor and the purification and isolation of pure substances was done by f...
Article
Hot-water extraction has shown a great potential in a green biorefinery, however, efficient separation of lignin and carbohydrates is still a big challenge, especially to lignin-carbohydrate complexes (LCCs). The aim of present study was to develop a facile approach for efficiently fractionating LCCs from hot-water extraction liquor of spruce wood,...
Article
Full-text available
In this study, the characteristics of nanocellulose extracted from bleached softwood and hardwood pulps by formic acid hydrolysis followed by TEMPO-mediated oxidation were compared using transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared analysis (FT-IR), X-ray diffraction (XRD), and thermal gravimetri...
Article
We present for the first time approaches to 3D-printing of nanocellulose hydrogel scaffolds based on double crosslinking, first by in situ Ca2+ crosslinking and post print by chemical crosslinking with 1,4-butanediol diglycidyl ether (BDDE). Scaffolds were successfully printed from 1% nanocellulose hydrogels, with their mechanical strength being tu...
Article
Hemicelluloses, the second most abundant polysaccharide right after cellulose, are in practice still treated as a side-stream in biomass processing industries. In the present study, we report an approach to use a wood-derived and side-stream biopolymer, spruce wood hemicellulose (galactoglucomannan, GGM) to partially replace the synthetic PLA as fe...
Article
Full-text available
Wood-derived biopolymers have attracted great attention over the past few decades due to their abundant and versatile properties. The well-separated three main components, i.e., cellulose, hemicelluloses, and lignin, are considered significant candidates for replacing and improving on oil-based chemicals and materials. The production of nanocellulo...
Article
This paper describes the chemical composition of sapwood (SW) and heartwood (HW) of Pinus halepensis Mill stem. Extractives were first isolated by accelerated solvent extraction and then analysed by gas chromatography-mass spectrometry (GC-MS). The cellulosic polysaccharide content present in the pre-extracted wood samples was determined with acid...
Article
To promote the efficient utilization of lignocellulosic materials, one-step fractionation by formic acid-based organosolv process under pressure has been studied for converting lignocellulose in its main components. Lignin and hemicelluloses were selectively dissolved, while cellulose was not obviously degraded. Under optimized conditions (85% form...
Article
Aqueous size-exclusion chromatography (SEC) equipped with refractive index (RI) and multiangle laser light scattering (MALLS) detectors were applied to evaluation of charged molecules content in a series of polysaccharide derivatives with different average molar mass (MM) values. It was shown that a minor amount of residual charged groups in the po...
Article
Bamboo chips were efficiently fractionated using an integrated process of autohydrolysis and formic acid to induce rapid delignification. Autohydrolysis pretreatment facilitated oligosaccharide production, while the subsequent rapid-delignification using formic acid at a low liquid/solid ratio with a relatively short reaction time allowed obtaining...
Article
Accurate determination of the distribution of substitutions in the primary molecular structure of heteropolysaccharides and their derivatives is a prerequisite for their increasing application in the pharmaceutical and biomedical fields, which is unfortunately hindered due to the lack of effective analytical techniques. Acetylated galactoglucomanna...
Article
The production of biofuels and other chemicals from lignocellulosic biomass is limited by the inefficiency of enzymatic hydrolysis. Here a biomimetic composite material consisting of bacterial cellulose and wood-based hemicelluloses was used to study the effects of hemicelluloses on the enzymatic hydrolysis with a commercial cellulase mixture. Bact...
Article
In this work we have characterized a mild soda pulped birch (betula pendula) lignin after a novel pressurized hot water extraction pilot process. In the process hemicelluloses are first isolated from woods chips with hot water at oxygen-starved conditions, followed by mild alkali pulping at oxygen-starved conditions to remove lignin from the cellul...
Chapter
Natural resources are abundant in numerous forms such as animals, plants, bacteria, and other organisms. Proteins and polysaccharides that can be recovered from natural resources and have good biocompatibility have found many promising high value applications, such as in the tailoring of aerogels for bioactive scaffolds in biomedical treatments. To...
Article
Knowledge gaps in the biosafety data of the nanocellulose (NC) for biomedical use through various routes of administration call for closer look at health and exposure evaluation. This work evaluated the potentially immunogenic contaminants levels, e.g. endotoxin and (1,3)-β-D-glucan, in four representative NCs, i.e. wood-based NCs and bacterial cel...
Article
Antibacterial properties of wood structural components and extractives were investigated against methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli O157:H7 by placing bacterial inoculum on the model surfaces and incubating them for 2, 4, and 24 h. After incubation, the amount of viable bacteria on the surfaces was studied. The...
Article
Hypothesis Amphiphilic character of surfactants drives them at the interface of dispersed systems, such as emulsions. Hemicellulose-rich wood extracts contain assemblies (lignin-carbohydrate complexes, LCC) with natural amphiphilicity, which is expected to depend on their chemical composition resulting from the isolation method. Lignin-derived phen...
Article
Full-text available
Approaches to increase the efficiency in developing drugs and diagnostics tools, including new drug delivery and diagnostic technologies, are needed for improved diagnosis and treatment of major diseases and health problems such as cancer, inflammatory diseases, chronic wounds, and antibiotic resistance. Development within several areas of research...
Article
Full-text available
The incentives for utilizing a versatile range of renewable feedstocks in novel ways are continuously increasing. Sulfated polysaccharides from green algae, such as ulvan, are interesting due to the rare sugar constituents which can be utilized for new materials and chemicals in industry. However, before valorization fractionation needs to be perfo...
Article
Bamboo was fractionated using formic acid based on a one-step organosolv process under high pressure (at 145 °C for 45 min, 0.3 MPa) and at atmospheric pressure (at 101 °C for 120 min), respectively. High-pressure formic acid lignin, atmospheric formic acid lignin and milled wood lignin of bamboo were subjected to comprehensive structural character...
Article
The feasibility of replacing sodium hydroxide with calcium hydroxide in peroxide bleaching of kraft pulp was assessed. The bleaching experiments were carried out in small scale on two different starting pulps, with a preliminary study and a more narrow follow-up study. The preliminary study showed that the required amount of Ca(OH)2 was quite low c...
Article
The lipophilic and hydrophilic extractives in the sapwood (sW) and heartwood (hW) of stems from Pinus halepensis Mill and Eucalyptus camaldulensis Dehnh trees grown in the north of Algeria were analyzed. The extraction of dried samples was carried out in an accelerated solvent extractor (ASE). The lipophilic substances were first extracted with n-h...
Article
Extraction of hemicelluloses with subcritical water is an efficient and environmentally benign way of fractionating biomass, including lignocelluloses. The composition and extraction behavior of hemicelluloses from wood depends significantly on the species, which affects the obtained product and the requirements of the extraction process. The curre...
Article
High purity (>99.5%) NaCMC solution was heated in ion-exchanged water and in an aqueous 10 mM NaHCO3 buffer solution and studied as a function of time and temperature. The effects of thermal treatment on viscosity, pH, molecular weight and cationic demand of the solutions were measured. It was found that the anionic groups of carboxymethylcellulose...
Article
Nanocellulose-based biomaterials for biomedical and pharmaceutical applications have been extensively explored. However, studies on different levels of impurities in the nanocellulose and their potential risks are lacking. This article is the most comprehensive to date survey of the importance and characterization of possible leachables and extract...
Article
Full-text available
The identification of compounds in Scots pine (Pinus sylvestris L.) knotwood (KnW), obtained by extracting with hydrophilic organic solvents, has been performed previously almost exclusively by gas chromatography-mass spectrometry (GS-MS) equipped with long GC columns (≥25 m). That means that the molar mass (MM) of the majority of the identified co...
Article
The traditional method to isolate cellulose nanocrystals (CNCs) is to subject cellulosic materials to strong acid hydrolysis by mineral acids, which usually cause problems such as corrosion of equipment, the need of large amount of water, the difficulty of acid recovery, and over-degradation of cellulose. Thus, a green and sustainable approach for...
Article
Full-text available
Crosslinking-aided gelation was utilized to prepare hydrogels from softwood polysaccharides, with spruce galactoglucomannans (GGM)—a group of largely unexploited hemicelluloses—as the main component, aiming at conversion into sponge-like aerogels. Cellulose nanofibrils were used for the formation of a reinforcing network, which was further crosslin...
Article
Full-text available
Polysaccharides are finding an increasing number of applications in medical and pharmaceutical fields thanks to their biodegradability, biocompatibility, and in some cases bioactivity. Two approaches were applied to use hemicelluloses as crosslinkers to tune the structural and mechanical properties of nanofibrillated cellulose (NFC) hydrogel scaffo...
Article
Plant polysaccharides constitute arguably the most complex family of biomacromolecules in terms of the stereochemistry and regiochemistry of their intramolecular linkages. The chemical modification of such polysaccharides introduces an additional level of complexity for structural determinations. We have developed an integrated analytical procedure...
Article
Full-text available
New types of hydrogels derived from O‐acetyl galactoglucomannan (AcGGM) hemicellulose have been synthesized and characterized. The objective of this work was to analyze the sorption capacity (S) of three types of hydrogels containing AcGGM derivatives incorporated into the carboxylic groups of the polymer chain in the AA hydrogel, sulfonic groups i...
Article
Full-text available
The chemical content and composition of the lipophilic extracts from seeds of some fir species: Abies alba, A. cephalonica, A. concolor and A. koreana, as well as of a few spruce species: Picea abies, P. orientalis and P. pungens, were examined. The amount of lipophilic extractives diverse among the tree species; from 9.8% to 41%. The chemical char...
Article
In order to preserve the polymeric structure and the acetylation degree of extracted galactoglucomannans and, at the same time, achieve high yield, ground spruce wood was subjected to a series of sequential two-stage extractions with an Accelerated Solvent Extraction (ASE) apparatus using plain water at 170°C. The total combined extraction time was...
Article
A high temperature in-line pH control system was used during hot-water extraction of spruce wood for enhancing the extraction towards high yield of water-soluble high-molar-mass hemicelluloses. Extractions of 2-4 mm wood particles and industrial size wood chips at 180 degrees C and pH set points 5.15, 4.85, and 4.50 were performed, as well as refer...
Article
Pulp mills constantly look for opportunities to increase their production capacity without major investments, as well as to save in overall bleaching costs. Peracetic acid (PAA) is used in post bleaching of kraft pulps to increase pulp brightness, to prevent brightness reversion in pulp storage, and to prohibit problems caused by extractives. Howev...
Article
Full-text available
Arbutus andrachne and Platanus orientalis grow naturally in Turkey. They do not occur in stands but can be seen as solitary trees. A. andrachne is seen in coastal parts of Anatolia, whereas P. orientalis can be found from west to the east of Turkey, mostly in river banks. Lipophilic extractives, hydrophilic extractives, and suberin monomers from Ar...
Article
The pressurized hot-water extraction (PHWE) process of Norway spruce sawdust has been optimized aiming at the production of a hemicellulose-rich fraction consisting mainly of galactoglucomannans (GGM). The independent process parameters temperature, reaction time, and liquid-to-wood (L/W) ratio were in focus of the statistical modeling. The main ta...
Article
Full-text available
The objective of the present study was to evaluate the potential of pressurized hot water extracted hemicellulose fractions from various wood species as feeds for ruminants. In Experiment 1, the fermentability of several hemicellulose extracts was screened using an in vitro gas production method. The samples were extracted from spruce (Picea abies)...
Article
Synthesis of lignopolyurethane foams based on wastes from biochemical industries, both freshly obtained technical-grade hydrolytic lignins and those stored in dumps for a long time, was studied. It was found out that the lignopolyurethane foams obtained have high heat-insulating properties conforming to the standards of heat-insulating materials. I...
Article
Extraction of ground spruce sapwood with pressurized hot water in an accelerated solvent extractor (ASE) at 170°C during 20, 60, and 100 min resulted in isolation of galactoglucomannans and aromatic substances, including lignin. The isolated lignin preparations were characterized by spectrometric (UV, FT-IR, 1H NMR, liquid and solid-state 13C NMR),...
Article
Ground spruce wood was extracted with pressurized hot water in an accelerated solvent extractor (ASE) at 170°C during 20, 60, and 100 min. Released aromatic substances (from 2.2 to 2.5% on wood basis) were isolated on XAD-7 resin and fractionated into lignin, oligomeric aromatic substances (OAS), and compounds insoluble in methanol (IMC). The separ...
Conference Paper
Peracetic acid (PAA) is used in post-bleaching of Kraft pulps in order to increase brightness, to avoid brightness reversion during storage, and to improve pitch control by diminishing the negative effects of extractives in the final pulp. The reactions between PAA and the extractives are very complex and special emphasis needs to be put on the req...
Article
The aim of this study was to isolate lignin from spruce wood with an accelerated solvent extractor (Dionex ASE 350) using low concentration alkali solutions. Two concentrations of alkali were studied - 1% and 2% aqueous NaOH. Extraction was performed for 4 hours total time, but different extraction sequences were studied: 1 cycle per 240 minutes st...

Network

Cited By