Andrey Pranovich - Academia.edu (original) (raw)

Papers by Andrey Pranovich

Research paper thumbnail of Non-cellulosic heteropolysaccharides from sugarcane bagasse – Sequential extraction with pressurized hot water and alkaline peroxide at different temperatures

Xylans were extracted from sugarcane bagasse with hot-water and alkaline peroxide. Xylose units i... more Xylans were extracted from sugarcane bagasse with hot-water and alkaline peroxide. Xylose units in the main chain of xylans are substituted by arabinose at C2 and C3. The arabinoxylans extracted with water at high temperature contained less arabinose. The water-soluble arabinoxylans are more branched, acetylated and low-molar-mass. Water-extracted hemicelluloses contain more lignin than alkaline peroxide extracted. a b s t r a c t The xylan-rich hemicellulose components of sugarcane bagasse were sequentially extracted with pressurized hot-water extraction (PHWE) and alkaline peroxide. The hemicelluloses were found to contain mainly arabinoxylans with varying substitutions confirmed by different chemical and spectroscopic methods. The arabinoxylans obtained from PHWE were found to be more branched compared to those obtained after alkaline extraction. Sequential extraction could be useful for the isolation of hemicellu-loses with different degree of branching, molar mass, and functional groups from sugarcane bagasse, which can be of high potential use for various industrial applications.

Research paper thumbnail of Isolation of Pectic Acids from Bleached TMP Water and Aggregation of Model and TMP Pectic Acids by Calcium

Pectins are important structural elements in spruce fibres. Alkaline peroxide bleaching of spruce... more Pectins are important structural elements in spruce fibres. Alkaline peroxide bleaching of spruce thermomechanical pulp (TMP) causes degradation and demethylation of pectins, yielding high-charge-density pectic acids. The pectic acids in fibres contribute strongly to the negative fibre charge, and the dissolved pectic acids increase the cationic demand of bleached TMP water. In this study, a method to isolate pectic acids

Research paper thumbnail of Polysaccharides in some industrially important hardwood species

Wood Science and Technology, 2005

... Table 3 Amount of cellulose, expressed as mg/g dry wood, for heartwood and sapwood, or stemwo... more ... Table 3 Amount of cellulose, expressed as mg/g dry wood, for heartwood and sapwood, or stemwood, of different hardwood species n Cellulose Acacia crassicarpa SW 3 515 HW 4 500 A. mangium SW 4 478 HW 2 453 Betula pendula S 3 415 ...

Research paper thumbnail of Non-cellulosic heteropolysaccharides from sugarcane bagasse – Sequential extraction with pressurized hot water and alkaline peroxide at different temperatures

Bioresource Technology, 2014

Xylans were extracted from sugarcane bagasse with hot-water and alkaline peroxide. Xylose units i... more Xylans were extracted from sugarcane bagasse with hot-water and alkaline peroxide. Xylose units in the main chain of xylans are substituted by arabinose at C2 and C3. The arabinoxylans extracted with water at high temperature contained less arabinose. The water-soluble arabinoxylans are more branched, acetylated and low-molar-mass. Water-extracted hemicelluloses contain more lignin than alkaline peroxide extracted.

Research paper thumbnail of Chemical Composition of Lipophilic Extractives from Grey Alder (Alnus incana)

BioResources , 2013

The chemical composition of the lipophilic extractives in the hexane extracts from grey alder bar... more The chemical composition of the lipophilic extractives in the hexane extracts from grey alder bark, knotwood, and cones has been investigated by gas chromatography and gas chromatography-mass spectrometry. The efficiency of two extraction methods was compared. The highest amount of lipophilic extractives (about 9% of o.d. material) was observed in grey alder cone, while the lowest (about 3%) was found in knotwood. The three different morphological parts of alder showed significant differences not only in the content but also in composition of extractives, namely fatty acids, triglycerides, and triterpenes. The main identified compounds were triterpenoids (lupen-3-one, lupeol, betulone, betulinol, and betulinic acid) in bark, and triglycerides in cones. The major group in knotwood was free fatty acids (mainly linoleic acid, 18:2).

Research paper thumbnail of Sorption of metal ions to untreated, alkali-treated and peroxide-bleached TMP

Cellulose, 2010

Knowledge about how different metal ions are bound to pulp fibers is very important for optimal m... more Knowledge about how different metal ions are bound to pulp fibers is very important for optimal metal management in pulping processes. A column chromatographic method was used to assess the differences in affinity of 14 metal ions to untreated, alkali-treated and peroxide-bleached thermomechanical pulp (TMP). A method of competition between cations in the column chromatographic experiments was used in the sorption experiments, with an excess of each metal ion compared to the total capacity of the pulp studied. The method is very sensitive and even small differences in affinities can be detected. By combining the results from sorption experiments with four different metal ion mixtures the following order of affinity was obtained: Pb2+ ≫ Cu2+ ≫ Cd2+ > Zn2+ > Ni2+ > Ba2+ > Ca2+ > Mn2+ > Sr2+ > Mg2+ ≫ Rb+ ≈ K+ > Na+ > Li+. All three types of pulps showed the same affinity order. Lead and copper ions were clearly most strongly bound to the pulp fibers. Within the alkali and alkaline earth metal groups the differences in affinity were quite small. The sorption of metal ions to pulp fibers takes place mainly by complexation, where the divalent metal ions are coordinated to functional groups (acid groups) in the fiber phase. Protonation constants and concentrations of acid groups were determined by potentiometric titration. A model with two carboxyl groups and two phenolic hydroxyl groups satisfied best the experimental data. By treatment with alkali and peroxide new acid groups were created and the total binding capacity of hydrogen ions increased from 137 μeq/g for untreated pulp to 187 and 228 μeq/g for alkali-treated and peroxide-treated pulp, respectively.

Research paper thumbnail of Chemical Changes in Thermomechanical Pulp at Alkaline Conditions

Journal of Wood Chemistry and Technology, 2003

Chemical changes in thermomechanical pulp (TMP) from Norway spruce at alkaline conditions were ex... more Chemical changes in thermomechanical pulp (TMP) from Norway spruce at alkaline conditions were examined at pH levels 9, 10, and 11, and temperatures of 40, 50, and 60°C. Alkali treatments were also made in the presence of hydrogen peroxide. The anionic charge of the fibres increased rapidly, following the kinetics of ester bond cleavage. Already at pH 9 and 60°C,

Research paper thumbnail of Dissolved Lignin and Other Aromatic Substances in Thermomechanical Pulp Waters

Journal of Wood Chemistry and Technology, 2005

ABSTRACT

Research paper thumbnail of Determination of anionic groups in wood by time-of-flight secondary ion mass spectrometry and laser ablation-inductively coupled plasma-mass spectrometry

Holzforschung, 2000

... Pectin was abundant in the primary wall, middle lamella cell corners, ray cells, and tori of ... more ... Pectin was abundant in the primary wall, middle lamella cell corners, ray cells, and tori of bordered pits in spruce and pine wood. In birch and aspen wood, pec-tin is mainly located in the cell junctions, the compound middle lamella of fibres and vessels, and ray cells (Hafrén ...

Research paper thumbnail of Distribution of Anionic Groups in TMP Suspensions

Journal of Wood Chemistry and Technology - J WOOD CHEM TECHNOL, 2000

The distribution of anionic groups in fibres, fines, the colloidal fraction, and the dissolved fr... more The distribution of anionic groups in fibres, fines, the colloidal fraction, and the dissolved fraction of thermomechanical pulp (TMP) suspensions was determined. The influence of extraction, alkaline treatment, and peroxide bleaching of spruce TMP were also studied.Spruce TMP was extracted with hexane, treated with alkali, or bleached with peroxide. Suspensions were made at pH 5.5 or 8, and fractionated into long fibres, large fines, small fines, a colloidal fraction, and a dissolved fraction. The surface and total charge of the fractions were determined separately by polyelectrolyte titration. To determine the origin of the charges, the contents of fatty acids, resin acids, and acidic units in polysaccharides in the different fractions were determined by gas chromatography.Extraction of TMP with hexane prior to fractionation increased the measured total and surface charge of the fibres. The removal of wood resin probably uncovered some anionic groups on the fibre surface, or impro...

Research paper thumbnail of Pressurized hot water extraction of Norway spruce hemicelluloses using a flow-through system

Wood Science and Technology, 2011

Norway spruce saw meal was extracted with pressurized hot water at 120-240°C using a flow-through... more Norway spruce saw meal was extracted with pressurized hot water at 120-240°C using a flow-through system. Only small amounts of hemicelluloses were extracted at 120-160°C, but dissolution was significantly enhanced when higher extraction temperatures were applied. All hemicelluloses but only 15% of lignin were removed from wood at 220°C, and even less lignin was extracted at lower temperatures. Partial degradation of cellulose seemed to take place only at 240°C. Of the total amount of extracted hemicelluloses, 4-22% was hydrolyzed to monosaccharides. Although the average molar masses of extracted hemicelluloses decreased with increasing extraction temperature, even at 240°C the extracted carbohydrates occurred, on average, as polysaccharides. Polysaccharides with an average molar mass of 31 kDa were obtained at 170°C. The molecular-mass characteristics and yield of carbohydrates depend on the extraction temperature, which should be chosen based on the end use of the isolated hemicelluloses.

Research paper thumbnail of Kinetics of Acid Hydrolysis of Water-Soluble Spruce O-Acetyl Galactoglucomannans

Journal of Agricultural and Food Chemistry, 2008

Water-soluble O-acetyl galactoglucomannan (GGM) is a softwood-derived polysaccharide, which can b... more Water-soluble O-acetyl galactoglucomannan (GGM) is a softwood-derived polysaccharide, which can be extracted on an industrial scale from wood or mechanical pulping waters and now is available in kilogram scale for research and development of value-added products. To develop applications of GGM, information is needed on its stability in acidic conditions. The kinetics of acid hydrolysis of GGM was studied at temperatures up to 90 degrees C in the pH range of 1-3. Molar mass and molar mass distribution were determined using size exclusion chromatography with multiangle laser light scattering and refractive index detection. The molar mass of GGM decreased considerably with treatment time at temperatures above 70 degrees C and pH below 2. The molar mass distribution broadened with hydrolysis time. A first-order kinetic model was found to match the acid hydrolysis. The reaction rate constants at various pH values and temperatures were calculated on the basis of the first-order kinetic model. Furthermore, the activation energy, E, was obtained from the Arrhenius plot. The activation energy E was 150 kJ mol (-1) for acid hydrolysis of spruce GGM. The apparent rate constant during acid hydrolysis increased by a factor of 10 with a decrease in pH by 1 unit, regardless of temperature. In addition, gas chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry were applied to study the released GGM monomers and oligomers.

Research paper thumbnail of Carbohydrate analysis of plant materials with uronic acid-containing polysaccharides–A comparison between different hydrolysis and subsequent chromatographic analytical techniques

Industrial Crops and Products, 2009

Acid hydrolysis Enzymatic hydrolysis GC-FID GC-MS HPAEC-PAD HPAEC-Borate a b s t r a c t Acid hyd... more Acid hydrolysis Enzymatic hydrolysis GC-FID GC-MS HPAEC-PAD HPAEC-Borate a b s t r a c t Acid hydrolysis, acid methanolysis, and enzymatic hydrolysis were compared for depolymerization of five different plant materials containing uronic acids. The analyzed plant materials were oat spelt, wheat straw, spruce thermomechanical pulp, aspen stemwood, and totally chlorine-free (TCF) bleached hardwood kraft pulp. Furthermore, GC (using both HP-1 and HP-5 capillary columns and FID and MSD detectors), HPAEC-PAD, and HPAEC-Borate techniques were compared for subsequent analysis of the released monosaccharides.

Research paper thumbnail of Hydrolytic stability of water-soluble spruce O-acetyl galactoglucomannans

Holzforschung, 2000

Abstract Water-soluble native O-acetyl galactoglucomannan (GGM) from spruce (Picea) is a polysacc... more Abstract Water-soluble native O-acetyl galactoglucomannan (GGM) from spruce (Picea) is a polysaccharide that can be produced in an industrial scale. To develop GGM applications, information is needed on its stability, particularly under acidic conditions. Therefore, acid ...

Research paper thumbnail of Ultrasound enhancement of cellulose processing in ionic liquids: from dissolution towards functionalization

Green Chemistry, 2007

... The effect of external parameters, such as the reaction temperature, the cellulose–derivatisi... more ... The effect of external parameters, such as the reaction temperature, the cellulose–derivatising ... how seriously the ionic liquids suffered from thermal degradation induced by the acousticirradiation. ... to 25 wt% of cellulose under heating supported by short microwave pulses, while ...

Research paper thumbnail of Allyloxy-modified starch with low degree of substitution for fiber reinforced thermoset starch composites

Composites Science and Technology, 2011

Research paper thumbnail of Studies on mechanical properties of wood fiber reinforced cross-linked starch composites made from enzymatically degraded allylglycidyl ether-modified starch

Composites Part A: Applied Science and Manufacturing, 2010

In a previous work we introduced a new family of thermoset composites of softwood fiber and allyl... more In a previous work we introduced a new family of thermoset composites of softwood fiber and allylglycidyl ether modified potato starch (AGE-starch with a degree of substitution of 1.3 and 2.3) prepared by hot pressing. To improve the processability of AGE-starch with a DS=1.3 (LDS-3) and to increase hygromechanical properties, the LDS-3 matrix has now been partially degraded by α-amylase

Research paper thumbnail of Characterisation and effects of new anionic groups formed during chemithermomechanical pulping of spruce

Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2007

The amount of total anionic groups (TAGs) in laboratory-scale chemithermomechanical pulps (CTMP) ... more The amount of total anionic groups (TAGs) in laboratory-scale chemithermomechanical pulps (CTMP) were assessed by Methylene Blue (MB) and quinoline sorption. The amounts of surface anionic groups (SAGs) were determined by MB sorption followed by X-ray photoelectron spectroscopy (XPS) and by polyelectrolyte (PE) titration. The content of uronic acids in the pulps was determined by acid methanolysis and gas chromatography (GC) and the methyl-esterification degree of pectins by alkaline hydrolysis. Pulps were produced by chemical pretreatments of sapwood chips of Norway spruce (Picea abies) prior to refining in a small-scale batch refiner. The chips were pretreated with alkaline, sulphite, alkaline sulphite and alkaline peroxide liquors. The TAGs in the pulps increased linearly with alkali and sulphite dosages. Sulphonic groups in lignin and new carboxyl groups formed in pectins accounted for a major part of the new anionic groups. New anionic groups were also created in the fibre material due to lignin oxidation in alkaline peroxide treatment. Pretreatment with sulphite resulted in a lower surface lignin content compared to pretreatment with alkali or alkaline sulphite. This may indicate more preferential fibre separation in the primary wall layers than in the middle lamella or be a result of redeposition of alkali-dissolved lignin onto fibre surfaces. The amount of SAGs, determined by XPS, was doubled for the chemically pretreated pulps compared to a reference TMP. This is probably a result of primary wall exposure and substantial pectin demethylation. Sulphonation did not result in more SAGs.

Research paper thumbnail of Sorption of metal ions to untreated, alkali-treated and peroxide-bleached TMP

Cellulose, 2010

Knowledge about how different metal ions are bound to pulp fibers is very important for optimal m... more Knowledge about how different metal ions are bound to pulp fibers is very important for optimal metal management in pulping processes. A column chromatographic method was used to assess the differences in affinity of 14 metal ions to untreated, alkali-treated and peroxide-bleached thermomechanical pulp (TMP). A method of competition between cations in the column chromatographic experiments was used in the sorption experiments, with an excess of each metal ion compared to the total capacity of the pulp studied. The method is very sensitive and even small differences in affinities can be detected. By combining the results from sorption experiments with four different metal ion mixtures the following order of affinity was obtained: Pb2+ ≫ Cu2+ ≫ Cd2+ > Zn2+ > Ni2+ > Ba2+ > Ca2+ > Mn2+ > Sr2+ > Mg2+ ≫ Rb+ ≈ K+ > Na+ > Li+. All three types of pulps showed the same affinity order. Lead and copper ions were clearly most strongly bound to the pulp fibers. Within the alkali and alkaline earth metal groups the differences in affinity were quite small. The sorption of metal ions to pulp fibers takes place mainly by complexation, where the divalent metal ions are coordinated to functional groups (acid groups) in the fiber phase. Protonation constants and concentrations of acid groups were determined by potentiometric titration. A model with two carboxyl groups and two phenolic hydroxyl groups satisfied best the experimental data. By treatment with alkali and peroxide new acid groups were created and the total binding capacity of hydrogen ions increased from 137 μeq/g for untreated pulp to 187 and 228 μeq/g for alkali-treated and peroxide-treated pulp, respectively.

Research paper thumbnail of Hydrophobication and characterisation of O-acetyl-galactoglucomannan for papermaking and barrier applications

Carbohydrate Research, 2012

Norway spruce O-acetyl-galactoglucomannans (GGM) are water-soluble hemicelluloses that have poten... more Norway spruce O-acetyl-galactoglucomannans (GGM) are water-soluble hemicelluloses that have potential to be produced in large scale as a side product of the mechanical pulping industry or by hot-water extraction of wood. Chemical modification is often needed to tailor such water-soluble polysaccharides into industrially valuable compounds. In this work, treatment of GGM with butyric and benzoic anhydride in pyridine/dimethylformamide rendered GGM derivatives, which were hydrophobic and partially soluble in organic solvents. The degree of substitution can be adjusted by varying the quantity of the reagent and reaction temperature. The dn/dc value for the benzoyl ester of GGM was determined in 0.05 M LiBr DMSO in order to obtain accurate molar mass analysis with SEC-MALLS-RI. Novel substances with adjusted hydrophobicity can thus be prepared on one step synthesis from natural hemicelluloses, which then showed a slight increase in the molar mass upon esterification.

Research paper thumbnail of Non-cellulosic heteropolysaccharides from sugarcane bagasse – Sequential extraction with pressurized hot water and alkaline peroxide at different temperatures

Xylans were extracted from sugarcane bagasse with hot-water and alkaline peroxide. Xylose units i... more Xylans were extracted from sugarcane bagasse with hot-water and alkaline peroxide. Xylose units in the main chain of xylans are substituted by arabinose at C2 and C3. The arabinoxylans extracted with water at high temperature contained less arabinose. The water-soluble arabinoxylans are more branched, acetylated and low-molar-mass. Water-extracted hemicelluloses contain more lignin than alkaline peroxide extracted. a b s t r a c t The xylan-rich hemicellulose components of sugarcane bagasse were sequentially extracted with pressurized hot-water extraction (PHWE) and alkaline peroxide. The hemicelluloses were found to contain mainly arabinoxylans with varying substitutions confirmed by different chemical and spectroscopic methods. The arabinoxylans obtained from PHWE were found to be more branched compared to those obtained after alkaline extraction. Sequential extraction could be useful for the isolation of hemicellu-loses with different degree of branching, molar mass, and functional groups from sugarcane bagasse, which can be of high potential use for various industrial applications.

Research paper thumbnail of Isolation of Pectic Acids from Bleached TMP Water and Aggregation of Model and TMP Pectic Acids by Calcium

Pectins are important structural elements in spruce fibres. Alkaline peroxide bleaching of spruce... more Pectins are important structural elements in spruce fibres. Alkaline peroxide bleaching of spruce thermomechanical pulp (TMP) causes degradation and demethylation of pectins, yielding high-charge-density pectic acids. The pectic acids in fibres contribute strongly to the negative fibre charge, and the dissolved pectic acids increase the cationic demand of bleached TMP water. In this study, a method to isolate pectic acids

Research paper thumbnail of Polysaccharides in some industrially important hardwood species

Wood Science and Technology, 2005

... Table 3 Amount of cellulose, expressed as mg/g dry wood, for heartwood and sapwood, or stemwo... more ... Table 3 Amount of cellulose, expressed as mg/g dry wood, for heartwood and sapwood, or stemwood, of different hardwood species n Cellulose Acacia crassicarpa SW 3 515 HW 4 500 A. mangium SW 4 478 HW 2 453 Betula pendula S 3 415 ...

Research paper thumbnail of Non-cellulosic heteropolysaccharides from sugarcane bagasse – Sequential extraction with pressurized hot water and alkaline peroxide at different temperatures

Bioresource Technology, 2014

Xylans were extracted from sugarcane bagasse with hot-water and alkaline peroxide. Xylose units i... more Xylans were extracted from sugarcane bagasse with hot-water and alkaline peroxide. Xylose units in the main chain of xylans are substituted by arabinose at C2 and C3. The arabinoxylans extracted with water at high temperature contained less arabinose. The water-soluble arabinoxylans are more branched, acetylated and low-molar-mass. Water-extracted hemicelluloses contain more lignin than alkaline peroxide extracted.

Research paper thumbnail of Chemical Composition of Lipophilic Extractives from Grey Alder (Alnus incana)

BioResources , 2013

The chemical composition of the lipophilic extractives in the hexane extracts from grey alder bar... more The chemical composition of the lipophilic extractives in the hexane extracts from grey alder bark, knotwood, and cones has been investigated by gas chromatography and gas chromatography-mass spectrometry. The efficiency of two extraction methods was compared. The highest amount of lipophilic extractives (about 9% of o.d. material) was observed in grey alder cone, while the lowest (about 3%) was found in knotwood. The three different morphological parts of alder showed significant differences not only in the content but also in composition of extractives, namely fatty acids, triglycerides, and triterpenes. The main identified compounds were triterpenoids (lupen-3-one, lupeol, betulone, betulinol, and betulinic acid) in bark, and triglycerides in cones. The major group in knotwood was free fatty acids (mainly linoleic acid, 18:2).

Research paper thumbnail of Sorption of metal ions to untreated, alkali-treated and peroxide-bleached TMP

Cellulose, 2010

Knowledge about how different metal ions are bound to pulp fibers is very important for optimal m... more Knowledge about how different metal ions are bound to pulp fibers is very important for optimal metal management in pulping processes. A column chromatographic method was used to assess the differences in affinity of 14 metal ions to untreated, alkali-treated and peroxide-bleached thermomechanical pulp (TMP). A method of competition between cations in the column chromatographic experiments was used in the sorption experiments, with an excess of each metal ion compared to the total capacity of the pulp studied. The method is very sensitive and even small differences in affinities can be detected. By combining the results from sorption experiments with four different metal ion mixtures the following order of affinity was obtained: Pb2+ ≫ Cu2+ ≫ Cd2+ > Zn2+ > Ni2+ > Ba2+ > Ca2+ > Mn2+ > Sr2+ > Mg2+ ≫ Rb+ ≈ K+ > Na+ > Li+. All three types of pulps showed the same affinity order. Lead and copper ions were clearly most strongly bound to the pulp fibers. Within the alkali and alkaline earth metal groups the differences in affinity were quite small. The sorption of metal ions to pulp fibers takes place mainly by complexation, where the divalent metal ions are coordinated to functional groups (acid groups) in the fiber phase. Protonation constants and concentrations of acid groups were determined by potentiometric titration. A model with two carboxyl groups and two phenolic hydroxyl groups satisfied best the experimental data. By treatment with alkali and peroxide new acid groups were created and the total binding capacity of hydrogen ions increased from 137 μeq/g for untreated pulp to 187 and 228 μeq/g for alkali-treated and peroxide-treated pulp, respectively.

Research paper thumbnail of Chemical Changes in Thermomechanical Pulp at Alkaline Conditions

Journal of Wood Chemistry and Technology, 2003

Chemical changes in thermomechanical pulp (TMP) from Norway spruce at alkaline conditions were ex... more Chemical changes in thermomechanical pulp (TMP) from Norway spruce at alkaline conditions were examined at pH levels 9, 10, and 11, and temperatures of 40, 50, and 60°C. Alkali treatments were also made in the presence of hydrogen peroxide. The anionic charge of the fibres increased rapidly, following the kinetics of ester bond cleavage. Already at pH 9 and 60°C,

Research paper thumbnail of Dissolved Lignin and Other Aromatic Substances in Thermomechanical Pulp Waters

Journal of Wood Chemistry and Technology, 2005

ABSTRACT

Research paper thumbnail of Determination of anionic groups in wood by time-of-flight secondary ion mass spectrometry and laser ablation-inductively coupled plasma-mass spectrometry

Holzforschung, 2000

... Pectin was abundant in the primary wall, middle lamella cell corners, ray cells, and tori of ... more ... Pectin was abundant in the primary wall, middle lamella cell corners, ray cells, and tori of bordered pits in spruce and pine wood. In birch and aspen wood, pec-tin is mainly located in the cell junctions, the compound middle lamella of fibres and vessels, and ray cells (Hafrén ...

Research paper thumbnail of Distribution of Anionic Groups in TMP Suspensions

Journal of Wood Chemistry and Technology - J WOOD CHEM TECHNOL, 2000

The distribution of anionic groups in fibres, fines, the colloidal fraction, and the dissolved fr... more The distribution of anionic groups in fibres, fines, the colloidal fraction, and the dissolved fraction of thermomechanical pulp (TMP) suspensions was determined. The influence of extraction, alkaline treatment, and peroxide bleaching of spruce TMP were also studied.Spruce TMP was extracted with hexane, treated with alkali, or bleached with peroxide. Suspensions were made at pH 5.5 or 8, and fractionated into long fibres, large fines, small fines, a colloidal fraction, and a dissolved fraction. The surface and total charge of the fractions were determined separately by polyelectrolyte titration. To determine the origin of the charges, the contents of fatty acids, resin acids, and acidic units in polysaccharides in the different fractions were determined by gas chromatography.Extraction of TMP with hexane prior to fractionation increased the measured total and surface charge of the fibres. The removal of wood resin probably uncovered some anionic groups on the fibre surface, or impro...

Research paper thumbnail of Pressurized hot water extraction of Norway spruce hemicelluloses using a flow-through system

Wood Science and Technology, 2011

Norway spruce saw meal was extracted with pressurized hot water at 120-240°C using a flow-through... more Norway spruce saw meal was extracted with pressurized hot water at 120-240°C using a flow-through system. Only small amounts of hemicelluloses were extracted at 120-160°C, but dissolution was significantly enhanced when higher extraction temperatures were applied. All hemicelluloses but only 15% of lignin were removed from wood at 220°C, and even less lignin was extracted at lower temperatures. Partial degradation of cellulose seemed to take place only at 240°C. Of the total amount of extracted hemicelluloses, 4-22% was hydrolyzed to monosaccharides. Although the average molar masses of extracted hemicelluloses decreased with increasing extraction temperature, even at 240°C the extracted carbohydrates occurred, on average, as polysaccharides. Polysaccharides with an average molar mass of 31 kDa were obtained at 170°C. The molecular-mass characteristics and yield of carbohydrates depend on the extraction temperature, which should be chosen based on the end use of the isolated hemicelluloses.

Research paper thumbnail of Kinetics of Acid Hydrolysis of Water-Soluble Spruce O-Acetyl Galactoglucomannans

Journal of Agricultural and Food Chemistry, 2008

Water-soluble O-acetyl galactoglucomannan (GGM) is a softwood-derived polysaccharide, which can b... more Water-soluble O-acetyl galactoglucomannan (GGM) is a softwood-derived polysaccharide, which can be extracted on an industrial scale from wood or mechanical pulping waters and now is available in kilogram scale for research and development of value-added products. To develop applications of GGM, information is needed on its stability in acidic conditions. The kinetics of acid hydrolysis of GGM was studied at temperatures up to 90 degrees C in the pH range of 1-3. Molar mass and molar mass distribution were determined using size exclusion chromatography with multiangle laser light scattering and refractive index detection. The molar mass of GGM decreased considerably with treatment time at temperatures above 70 degrees C and pH below 2. The molar mass distribution broadened with hydrolysis time. A first-order kinetic model was found to match the acid hydrolysis. The reaction rate constants at various pH values and temperatures were calculated on the basis of the first-order kinetic model. Furthermore, the activation energy, E, was obtained from the Arrhenius plot. The activation energy E was 150 kJ mol (-1) for acid hydrolysis of spruce GGM. The apparent rate constant during acid hydrolysis increased by a factor of 10 with a decrease in pH by 1 unit, regardless of temperature. In addition, gas chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry were applied to study the released GGM monomers and oligomers.

Research paper thumbnail of Carbohydrate analysis of plant materials with uronic acid-containing polysaccharides–A comparison between different hydrolysis and subsequent chromatographic analytical techniques

Industrial Crops and Products, 2009

Acid hydrolysis Enzymatic hydrolysis GC-FID GC-MS HPAEC-PAD HPAEC-Borate a b s t r a c t Acid hyd... more Acid hydrolysis Enzymatic hydrolysis GC-FID GC-MS HPAEC-PAD HPAEC-Borate a b s t r a c t Acid hydrolysis, acid methanolysis, and enzymatic hydrolysis were compared for depolymerization of five different plant materials containing uronic acids. The analyzed plant materials were oat spelt, wheat straw, spruce thermomechanical pulp, aspen stemwood, and totally chlorine-free (TCF) bleached hardwood kraft pulp. Furthermore, GC (using both HP-1 and HP-5 capillary columns and FID and MSD detectors), HPAEC-PAD, and HPAEC-Borate techniques were compared for subsequent analysis of the released monosaccharides.

Research paper thumbnail of Hydrolytic stability of water-soluble spruce O-acetyl galactoglucomannans

Holzforschung, 2000

Abstract Water-soluble native O-acetyl galactoglucomannan (GGM) from spruce (Picea) is a polysacc... more Abstract Water-soluble native O-acetyl galactoglucomannan (GGM) from spruce (Picea) is a polysaccharide that can be produced in an industrial scale. To develop GGM applications, information is needed on its stability, particularly under acidic conditions. Therefore, acid ...

Research paper thumbnail of Ultrasound enhancement of cellulose processing in ionic liquids: from dissolution towards functionalization

Green Chemistry, 2007

... The effect of external parameters, such as the reaction temperature, the cellulose–derivatisi... more ... The effect of external parameters, such as the reaction temperature, the cellulose–derivatising ... how seriously the ionic liquids suffered from thermal degradation induced by the acousticirradiation. ... to 25 wt% of cellulose under heating supported by short microwave pulses, while ...

Research paper thumbnail of Allyloxy-modified starch with low degree of substitution for fiber reinforced thermoset starch composites

Composites Science and Technology, 2011

Research paper thumbnail of Studies on mechanical properties of wood fiber reinforced cross-linked starch composites made from enzymatically degraded allylglycidyl ether-modified starch

Composites Part A: Applied Science and Manufacturing, 2010

In a previous work we introduced a new family of thermoset composites of softwood fiber and allyl... more In a previous work we introduced a new family of thermoset composites of softwood fiber and allylglycidyl ether modified potato starch (AGE-starch with a degree of substitution of 1.3 and 2.3) prepared by hot pressing. To improve the processability of AGE-starch with a DS=1.3 (LDS-3) and to increase hygromechanical properties, the LDS-3 matrix has now been partially degraded by α-amylase

Research paper thumbnail of Characterisation and effects of new anionic groups formed during chemithermomechanical pulping of spruce

Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2007

The amount of total anionic groups (TAGs) in laboratory-scale chemithermomechanical pulps (CTMP) ... more The amount of total anionic groups (TAGs) in laboratory-scale chemithermomechanical pulps (CTMP) were assessed by Methylene Blue (MB) and quinoline sorption. The amounts of surface anionic groups (SAGs) were determined by MB sorption followed by X-ray photoelectron spectroscopy (XPS) and by polyelectrolyte (PE) titration. The content of uronic acids in the pulps was determined by acid methanolysis and gas chromatography (GC) and the methyl-esterification degree of pectins by alkaline hydrolysis. Pulps were produced by chemical pretreatments of sapwood chips of Norway spruce (Picea abies) prior to refining in a small-scale batch refiner. The chips were pretreated with alkaline, sulphite, alkaline sulphite and alkaline peroxide liquors. The TAGs in the pulps increased linearly with alkali and sulphite dosages. Sulphonic groups in lignin and new carboxyl groups formed in pectins accounted for a major part of the new anionic groups. New anionic groups were also created in the fibre material due to lignin oxidation in alkaline peroxide treatment. Pretreatment with sulphite resulted in a lower surface lignin content compared to pretreatment with alkali or alkaline sulphite. This may indicate more preferential fibre separation in the primary wall layers than in the middle lamella or be a result of redeposition of alkali-dissolved lignin onto fibre surfaces. The amount of SAGs, determined by XPS, was doubled for the chemically pretreated pulps compared to a reference TMP. This is probably a result of primary wall exposure and substantial pectin demethylation. Sulphonation did not result in more SAGs.

Research paper thumbnail of Sorption of metal ions to untreated, alkali-treated and peroxide-bleached TMP

Cellulose, 2010

Knowledge about how different metal ions are bound to pulp fibers is very important for optimal m... more Knowledge about how different metal ions are bound to pulp fibers is very important for optimal metal management in pulping processes. A column chromatographic method was used to assess the differences in affinity of 14 metal ions to untreated, alkali-treated and peroxide-bleached thermomechanical pulp (TMP). A method of competition between cations in the column chromatographic experiments was used in the sorption experiments, with an excess of each metal ion compared to the total capacity of the pulp studied. The method is very sensitive and even small differences in affinities can be detected. By combining the results from sorption experiments with four different metal ion mixtures the following order of affinity was obtained: Pb2+ ≫ Cu2+ ≫ Cd2+ > Zn2+ > Ni2+ > Ba2+ > Ca2+ > Mn2+ > Sr2+ > Mg2+ ≫ Rb+ ≈ K+ > Na+ > Li+. All three types of pulps showed the same affinity order. Lead and copper ions were clearly most strongly bound to the pulp fibers. Within the alkali and alkaline earth metal groups the differences in affinity were quite small. The sorption of metal ions to pulp fibers takes place mainly by complexation, where the divalent metal ions are coordinated to functional groups (acid groups) in the fiber phase. Protonation constants and concentrations of acid groups were determined by potentiometric titration. A model with two carboxyl groups and two phenolic hydroxyl groups satisfied best the experimental data. By treatment with alkali and peroxide new acid groups were created and the total binding capacity of hydrogen ions increased from 137 μeq/g for untreated pulp to 187 and 228 μeq/g for alkali-treated and peroxide-treated pulp, respectively.

Research paper thumbnail of Hydrophobication and characterisation of O-acetyl-galactoglucomannan for papermaking and barrier applications

Carbohydrate Research, 2012

Norway spruce O-acetyl-galactoglucomannans (GGM) are water-soluble hemicelluloses that have poten... more Norway spruce O-acetyl-galactoglucomannans (GGM) are water-soluble hemicelluloses that have potential to be produced in large scale as a side product of the mechanical pulping industry or by hot-water extraction of wood. Chemical modification is often needed to tailor such water-soluble polysaccharides into industrially valuable compounds. In this work, treatment of GGM with butyric and benzoic anhydride in pyridine/dimethylformamide rendered GGM derivatives, which were hydrophobic and partially soluble in organic solvents. The degree of substitution can be adjusted by varying the quantity of the reagent and reaction temperature. The dn/dc value for the benzoyl ester of GGM was determined in 0.05 M LiBr DMSO in order to obtain accurate molar mass analysis with SEC-MALLS-RI. Novel substances with adjusted hydrophobicity can thus be prepared on one step synthesis from natural hemicelluloses, which then showed a slight increase in the molar mass upon esterification.