Rainer Ekman

Polysaccharides Dissolved from Norway Spruce in Thermomechanical Pulping and Peroxide Bleaching

Abstract Methanolysis, followed by GC analysis, was used to determine the amount and composition of sugar units comprising the carbohydrates present in water samples from unbleached and peroxide bleached thermomechanical pulp (TMP). Circulation experiments were carried out in the laboratory to simulate white water system closure in mechanical pulp mills. Water samples from simulated “closed” water systems were fractionated to determine the composition of the neutral and anionic polysaccharides released from the TMP samples. Decreasing fresh water consumption from 100 to 10 m3/t, for both unbleached and peroxide bleached TMP, had little influence on the overall sugar composition of the carbohydrates in the water samples. Alkaline peroxide bleaching resulted in substantial changes in the sugar composition of the carbohydrates comprising the dissolved and colloidal substances (DCS) in the water samples. The polysaccharides released from unbleached TMP were comprised of neutral (88%) and anionic (12%) polysac...

Composition of Nonpolar Extractives in Bark of Norway Spruce and Scots Pine

Abstract The composition of nonvolatile extractives soluble in petroleum ether was investigated separately for inner and outer bark of Norway spruce (Picea abies (L.) Karst) and Scots Pine (Pinus silvestris (L.)). The bark extractives of one spruce and one pine tree were prefractionated by thin-layer chromatography and the detailed composition of free and esterified fatty acids, free and esterified sterols, triterpenoid alcohols and fatty alcohols, resin acids and diterpene aldehydes was determined by gas chromatography. Bark of four other trees was analysed by a routine method based on direct gas chromatography of the extracts. Fatty acids, resin acids and sterols accounted for ca 80% of extractives in inner bark and for 50% in outer bark. Qualitative differences between the extractives in inner and outer bark were noticed. The total amount of fatty and resin acids was about 1.54 of spruce and pine bark dry weight and the amount of sterols was 0.2–0.5%. These levels are low considering possible technical...

Effects of alkaline treatment on dissolved carbohydrates in suspensions of Norway spruce thermomechanical pulp

Abstract The effects of alkaline treatment on dissolved carbohydrates in suspensions of Norway spruce thermomechanical pulp (TMP) were studied by agitating 1% consistency TMP suspensions at different pH values (5.4 to 12) for 3 h at 60°, followed by acidification and centrifugation to obtain water samples for analysis. It was found that at pH values above 8, dissolved galactoglucomannans were deacetylated, resulting in their substantial adsorption onto the TMP. Galacturonans began to dissolve from the TMP at pH values greater than 8. The amount of arabinogalactans apparently remained constant throughout the various alkaline treatments. At pH values above 10, arabino-(4-O-methylglucurono)xylans began to dissolve from the TMP. The amount of dissolved and colloidal substances (DCS), measured by TOC, could be substantially decreased by alkaline treatment of filtrate from the 1% consistency suspension, followed by acidification and remixing the filtrate with its original pulp. At 10 m3/t specific water consump...

Possibility of Increasing Mechanical Pulp Yield by Enzymatic Treatment

The major polysaccharides dissolved in thermomechanical pulping of Norway spruce (Picea abies) are the O-acetyl-galactoglucomannans. Enzymatic treatment of a TMP Suspension with an isolated acetyl esterase produced by Aspergillus oryzae resulted in deacetylation of dissolved galaetoglucomannans which led to their adsorption onto the TMP fibers. The potential yield gain due to this treatment amounted to 1% based on the initial dry fiber used in preparation of the Suspension. Industnal application of this biotechnical method may lead to decreased yield losses in mechanical pulping and, possibly, improvements in mechanical pulp strength.

Senescence-related Changes in the Composition of Free and Esterified Sterols and Alcohols in Sphagnum fuscum

Summary The content and composition of sterols, triterpenoid alcohols, n-aliphatic alcohols and hydrocarbons were studied by GC and GC/MS in the green (capitulum) and senescent parts of Sphagnum fuscum . The content of esterified sterols and triterpenoid alcohols, on a dry weight basis, was highest in the capitulum (740 μg · g -1 d.wt.) and very low in older parts (90 μg · g -1 d.wt. in the 3—6 cm segment and 20 μg · g -1 d.wt. in the 21—24 cm segment). Likewise the content of free sterols and triterpenoid alcohols was high in the capitulum (680 μg · g -1 d.wt.) and decreased with increased shoot age (380 μg and 240 μg · g -1 d.wt. in the 3—6 cm and 21—24 cm segments, respectively). The dominant components of the esterified sterols and triterpenoid alcohols were an unidentified component B (33.8%), cycloartenol (16.2%), methylene cycloartanol (9.5%), stigmasterol (16.2%) and campesterol (9.5%). At the depth of 21—24 cm esterified sitosterol was dominant. The major components among the free sterols and triterpenoid alcohols in the capitulum were stigmasterol (56.5%), campesterol (15.9%), sitosterol (10.9%) and an unidentified compound A (17.4%). The proportion of free sitosterol increased with increased shoot age (41.7% in the 21—24 cm segment) as did the proportion of free triterpenoid alcohols (cycloartenol and methylene cycloartanol), the level of which was extremely low in the capitulum. The contents of both free and esterified phytol (200 μg and 360 μg · g -1 d.wt., respectively) were highest in the capitulum and decreased with increased shoot age. At the depth of 21—24 cm only traces of free phytol and very small amounts of esterified phytol (20 μg · g -1 d.wt.) were found. The contents of hydrocarbons and n-alcohols of the esters were at about the same level in the capitulum and the 3—6 cm segment (i.e. 360 μg and 340 μg · g -1 d.wt. n-alcohols and 260 μg and 230 μg · g -1 d.wt. hydrocarbons, respectively), but distinctly lower in the 21—24 cm segment (170 μg · g -1 d.wt. n-alcohols and 100 μg · g -1 d.wt. hydrocarbons). The content of free n-alcohols was highest in the 3—6 cm segment (230 μg · g -1 d.wt.). The first signs of decay of S. fuscum shoots at the microscopic level ( i.e. occasionally damaged stem centre) were observed at the depth of 21—24 cm.

Esterified long-chain hydroxy acids in green and senescent parts of the peat moss Sphagnum fuscum

Abstract The bifunctional long-chain acids in extracts and alkaline hydrolysates of extractive-free tissues from the green and senescent parts of Sphagnum fuscum were investigated by GC and GC/MS. A series of C14– C26hydroxy acids was liberated by alkaline hydrolysis of senescent tissue demonstrating the presence of insoluble polymeric lipid esters in the moss. In the corresponding hydrolysates of the topmost green parts of the shoot the amounts of these acids were significantly smaller. It is suggested that the presence of such polymeric esters in S. fuscum contributes to the cell-wall resistance of this peat-forming moss.

Behaviour of extractives in a bark steam dryer

Abstract The bark extractives from steam drying of bark residues at a pulp mill were studied in order to evaluate their role in the formation of deposits in the dryer. The lipid compositions of bark, condensate and deposit samples taken from a back-pressure steam dryer plant were analyzed by gas chromatography and mass spectrometry. The main lipid groups released from bark and found in the condensate were free fatty acids and resin acids, dominated by unsaturated C 18 acids and dehydroabietic acid respectively. The release of these acid groups was 0.3% of the dry bark feed, corresponding to 50 wt% of the free fatty acid and resin acid content of the bark feed. It was assumed that these acids contribute by their tackiness to the formation of deposits at various sites of the dryer. The deposit samples taken from the dryer contained the same lipid compound groups as the bark raw material. However, their extract and lipid contents varied considerably, 2.9–40% and 0.5–18% on a dry ash-free basis, respectively, depending on their site in the dryer. The lipid composition of the deposit on a recycling fan was close to that of the condensate containing large amounts of fatty acids and resin acids. The deposit on heat exchanger tubes consisted of bark dust containing degraded bark suberin, and of fatty acids and resin acids carried with the steam.

Content of Polymerized Lipids in Stems and Leafy Branches of Sphagnum fuscum

Summary Segments of Sphagnum fuscum shoots from the depth of 18–20 cm at Karevansuo bog, SW-Finland, contained 2.2 mg · g-1 DW polymerized lipids, of which 93 % were derived from the leafy branches and 7 % from the stem part. The composition of the polymer monomers was qualitatively similar in the leafy branches and stems (i.e. long-chain hydroxy acids, dicarboxylic acids, fatty acids and fatty alcohols), but quantitative variation occurred between the monomer groups. The lipid polymers of the cell wall preparations from leafy branches were characterized by a high proportion of hydroxy acid monomers (62%), with 18-hydroxyoctadec-9-enoic acid and 9, 16+10, 16-dihydroxyhexadecanoic acids as major members. The stem was characterized by high proportions of hydroxy acids (43.5 %) and fatty acids (43.5 %).

Behaviour of Organic Compounds in Biomass Drying

In the thermal drying of wet biomass with steam or flue gases prior to conversion or combustion, organic compounds are released and constitute a load on the environment as emissions to the air or as effluents to natural waters. They can also cause operational problems by contributing to the formation of deposits in downstream sections. The release of these organic detrimental substances was studied both under atmospheric and pressurized conditions. Laboratory-scale fluidized-bed drying experiments were carried out at the temperature range of 150 – 350 °C for pine and birch barks and peat. The hydrophilic and lipophilic compounds released were analyzed by different chromatographic methods. In addition, dust, deposit and condensate samples from industrial bark and peat dryers were analyzed.