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Brännvall, ElisabetORCID iD iconorcid.org/0000-0002-8992-3623
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Publikasjoner (10 av 42) Visa alla publikasjoner
Svärd, A., Brännvall, E. & Edlund, U. (2017). Corrigendum to “Rapeseed straw as a renewable source of hemicelluloses: Extraction, characterization and film formation” [Carbohydrate Polymers 133 (2015) 179–186](S0144861715006529)(10.1016/j.carbpol.2015.07.023). Carbohydrate Polymers, 174, 1240
Åpne denne publikasjonen i ny fane eller vindu >>Corrigendum to “Rapeseed straw as a renewable source of hemicelluloses: Extraction, characterization and film formation” [Carbohydrate Polymers 133 (2015) 179–186](S0144861715006529)(10.1016/j.carbpol.2015.07.023)
2017 (engelsk)Inngår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 174, s. 1240-Artikkel i tidsskrift (Annet vitenskapelig) Published
Abstract [en]

The authors regret that the original version of this article unfortunately contained a mistake in Table 5. The correct Table 5 and associated text is given below. “The rapeseed hemicellulose films presented here had strain-at-break values of 70% (C) and 90% (H), even with no added plasticizers (Table 5).” The authors would like to apologise for any inconvenience caused.

sted, utgiver, år, opplag, sider
Elsevier, 2017
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-234655 (URN)10.1016/j.carbpol.2017.07.037 (DOI)2-s2.0-85026534602 (Scopus ID)
Tilgjengelig fra: 2018-09-07 Laget: 2018-09-07 Sist oppdatert: 2018-12-14bibliografisk kontrollert
Tavast, D. & Brännvall, E. (2017). Increased pulp yield by prolonged impregnation in softwood kraft pulping. Nordic Pulp & Paper Research Journal, 32(1), 14-20
Åpne denne publikasjonen i ny fane eller vindu >>Increased pulp yield by prolonged impregnation in softwood kraft pulping
2017 (engelsk)Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 32, nr 1, s. 14-20Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The effect on kraft cooking proceeded by an impregnation stage performed at 130 degrees C for 30 min was compared to kraft cooking following prolonged impregnation at 105 degrees C for 60-120 min. The alkali consumed during impregnation varied depending on the temperature and time of the impregnation stage. In order to study the impact of the impregnation stage on the subsequent kraft cook, the initial concentration of effective alkali was adjusted to be initially the same in all cooks before cooking for 180-290 min. The alkali consumed in the impregnation stage affected the alkali profile of the cooking stage. The more alkali consumed in impregnation, the lower the demand in cooking. Higher alkali consumption in the impregnation stage also led to faster delignification in the cooking stage. Prolonged impregnation resulted in 1-1.5 percentage points higher yield compared to the reference case. The yield increment was due to a higher cellulose retention. Although the impregnation time was prolonged from 30 min up to 2 h, the higher delignification rate and higher yield only decreased the production rate with 11% compared to the reference.

sted, utgiver, år, opplag, sider
AB SVENSK PAPPERSTIDNING, 2017
Emneord
Effective alkali, Homogeneous delignification Impregnation, Kraft cooking, Softwood, Yield
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-206312 (URN)10.3183/NPPRJ-2017-32-01-p014-020 (DOI)000398384400002 ()2-s2.0-85016432255 (Scopus ID)
Merknad

QC 20170505

Tilgjengelig fra: 2017-05-05 Laget: 2017-05-05 Sist oppdatert: 2017-05-05bibliografisk kontrollert
Svärd, A., Brännvall, E. & Edlund, U. (2017). Rapeseed straw polymeric hemicelluloses obtained by extraction methods based on severity factor. INDUSTRIAL CROPS AND PRODUCTS, 95, 305-315
Åpne denne publikasjonen i ny fane eller vindu >>Rapeseed straw polymeric hemicelluloses obtained by extraction methods based on severity factor
2017 (engelsk)Inngår i: INDUSTRIAL CROPS AND PRODUCTS, ISSN 0926-6690, Vol. 95, s. 305-315Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Rapeseed straw consists of a hard epidermis that is rich in hemicellulose and lignin and a sponge-like interior that consists mainly of cellulose. The stems were subjected to water, alkali or acid as extraction medium. The effects of the extraction conditions were quantified using severity factors and by comparing the effects of different extraction pHs, temperatures and times. Extraction with alkali resulted in a higher yield, 47 g/100 g straw in, compared to water, 6 g/100 g straw in, or an acidic, 5 g/100 g straw in, extraction process. An increase in temperature improved the extraction yield; in particular, more xylan was extracted at an elevated temperature and higher alkalinity. However, at high alkalinity, increased extraction temperatures led to a reduction in the recovery of glucomannan. The highest molecular weights (similar to 35,000 g/mol) of the extracted hemicelluloses were obtained using extraction procedures with 1.5 M NaOH at 110 degrees C and autohydrolysis at 150 degrees C. While these two parameter settings had very similar severity factors, extraction under basic conditions afforded an extract rich in xylan and low in lignin content, whereas autohydrolysis generated a glucomannan-rich extract.

sted, utgiver, år, opplag, sider
Elsevier, 2017
Emneord
Rapeseed/canola straw, Extraction, Autohydrolysis, Severity factor, Hemicellulose
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-200198 (URN)10.1016/j.indcrop.2016.10.038 (DOI)000390621600035 ()2-s2.0-85004143297 (Scopus ID)
Merknad

QC 20170202

Tilgjengelig fra: 2017-02-02 Laget: 2017-01-23 Sist oppdatert: 2018-09-07bibliografisk kontrollert
Svärd, A., Sevastyanova, O., Dobele, G., Jurkjane, V. & Brännvall, E. (2016). COST Action FP1105: effect of raw materials and pulping conditions on the characteristics of dissolved kraft lignins. Holzforschung, 70(12), 1105-1114
Åpne denne publikasjonen i ny fane eller vindu >>COST Action FP1105: effect of raw materials and pulping conditions on the characteristics of dissolved kraft lignins
Vise andre…
2016 (engelsk)Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 70, nr 12, s. 1105-1114Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The composition, molecular weight (MW), and chemical structure of technical lignins as byproducts of pulping influence their application in terms of physical and chemical properties, reactivity, and performance. It is important to know how the analytical data of technical lignins are influenced by the wood species and the parameters of pulping. The present study focuses on kraft pulping and how the wood species (eucalyptus, pine, and spruce) and variable cooking times influence the characteristics of dissolved lignins. The black liquor (BL) was recovered after three different cooking times and the precipitated lignin was characterized by total acid hydrolysis including the determination of the acid insoluble part (Klason lignin, KL) and the sugars in the hydrolysate, elemental analysis, 31P NMR spectroscopy, analytical pyrolysis (Py-GC/MS), gel permeation chromatography (GPC), thermogravimetry (TG), and differential scanning calorimetry (DSC). The results indicate that the phenolic OH content, MW and glass transition temperature increased with longer cooking times for the softwood (SW) lignins. These lignins had also a higher MW (M-w 5500-8000 g mol(-1)), than the eucalyptus lignin (M-w 2200-2400 g mol(-1)). Eucalyptus lignin had higher sulfur content compared to SW.

sted, utgiver, år, opplag, sider
Walter de Gruyter, 2016
Emneord
DSC, eucalyptus, GPC, kraft cooking, lignin, lignin precipitation, pine, P-31-NMR, Py-GC/MS, spruce, TGA
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-199495 (URN)10.1515/hf-2016-0057 (DOI)000389466800002 ()2-s2.0-84998554796 (Scopus ID)
Merknad

QC 20170118

Tilgjengelig fra: 2017-01-18 Laget: 2017-01-09 Sist oppdatert: 2017-11-29bibliografisk kontrollert
Brännvall, E. & Backström, M. (2016). Improved impregnation efficiency and pulp yield of softwood kraft pulp by high effective alkali charge in the impregnation stage. Holzforschung, 70(11), 1031-1037
Åpne denne publikasjonen i ny fane eller vindu >>Improved impregnation efficiency and pulp yield of softwood kraft pulp by high effective alkali charge in the impregnation stage
2016 (engelsk)Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 70, nr 11, s. 1031-1037Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

A pulp yield increase up to 2% can be achieved by impregnation with a liquor containing 2 M effective alkali ( EA) concentration instead of 1 M. The yield increase is due to higher cellulose and glucomannan contents in the pulp, which can be rationalized by less yield loss by peeling, as impregnation is more effective at an elevated EA level. A rapid loading of chips with alkali can be realized due to a high diffusion rate. When the temperature becomes higher in the cooking stage, enough alkali is available for delignification reactions without the risk of alkali depletion in the chip core, so that the delignification is more homogeneous.

sted, utgiver, år, opplag, sider
Walter de Gruyter, 2016
Emneord
carbohydrate composition, homogeneous delignification, impregnation, kraft pulping, pulp yield, softwood pulping
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-196381 (URN)10.1515/hf-2016-0020 (DOI)000385809600004 ()2-s2.0-84994176220 (Scopus ID)
Merknad

QC 20161114

Tilgjengelig fra: 2016-11-14 Laget: 2016-11-14 Sist oppdatert: 2017-11-29bibliografisk kontrollert
Backstrom, M., Jensen, A. & Brännvall, E. (2016). Influence of chip presteaming conditions on kraft pulp composition and properties. Holzforschung, 70(5), 393-399
Åpne denne publikasjonen i ny fane eller vindu >>Influence of chip presteaming conditions on kraft pulp composition and properties
2016 (engelsk)Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 70, nr 5, s. 393-399Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Presteaming is a well-established technique in pulp mills, which improves cooking liquor impregnation by removing air from within and between chips. The aim of the study was to investigate how conditions during steaming affect the subsequent kraft cook and properties of the obtained pulp. It was found that higher pressure and temperature during chip presteaming led to increased degradation and dissolution of hemicelluloses. Lower refinability and tensile index was obtained for pulps cooked after presteaming at high pressure and for a long time.

sted, utgiver, år, opplag, sider
Walter de Gruyter, 2016
Emneord
alkali consumption, kraft cooking, presteaming, pulp properties, softwood, yield
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-187790 (URN)10.1515/hf-2015-0104 (DOI)000375131700002 ()2-s2.0-84967113433 (Scopus ID)
Merknad

QC 20160530

Tilgjengelig fra: 2016-05-30 Laget: 2016-05-30 Sist oppdatert: 2017-11-30bibliografisk kontrollert
Svärd, A., Brännvall, E. & Edlund, U. (2016). Rapeseed straw extraction yields hemicelluloses for renewable materials. Abstract of Papers of the American Chemical Society, 251
Åpne denne publikasjonen i ny fane eller vindu >>Rapeseed straw extraction yields hemicelluloses for renewable materials
2016 (engelsk)Inngår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 251Artikkel i tidsskrift, Meeting abstract (Annet vitenskapelig) Published
sted, utgiver, år, opplag, sider
AMER CHEMICAL SOC, 2016
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-242702 (URN)000431903802557 ()
Merknad

QC 20190220

Tilgjengelig fra: 2019-02-20 Laget: 2019-02-20 Sist oppdatert: 2019-02-20bibliografisk kontrollert
Tavast, D., Li Jansson, Z. & Brännvall, E. (2015). Influence of spruce xylan characteristics on tensile strength of spruce kraft pulp. Holzforschung, 69(1), 1-7
Åpne denne publikasjonen i ny fane eller vindu >>Influence of spruce xylan characteristics on tensile strength of spruce kraft pulp
2015 (engelsk)Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 69, nr 1, s. 1-7Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The aim of the study was to investigate the possibility to use spruce xylan more efficiently by possible relocation of dissolved xylan with certain characteristics from the first part of the kraft cooking to the later part, when precipitation occur. The characteristics of re-located xylan was controlled by replacing half the black liquor (BL) at a late stage of a kraft cook, with the same amount of black liquor containing spruce xylan with known molecular weight and content of uronic acid (UA). Pulp with addition of xylan with high amount of UA groups responded strongly on beating, resulting in improved tensile strength. It is proposed that the best effect of xylan on tensile strength occurs when the xylan penetrates some distance into the subsurface of the fiber wall. Both low molecular weight (M-w) and a high degree of substitution decreases the tendency of xylan to aggregate, which enables the dissolved xylan to penetrate some distance into the exposed fiber surface. Upon beating, this xylan will be exposed thus facilitating improved fiber-fiber joint formation, which leads to increased tensile strength.

Emneord
kraft cooking, spruce, tensile strength, uronic acid, xylan
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-159109 (URN)10.1515/hf-2014-0010 (DOI)000346764600001 ()2-s2.0-84920088278 (Scopus ID)
Forskningsfinansiär
VINNOVA
Merknad

QC 20150129

Tilgjengelig fra: 2015-01-29 Laget: 2015-01-22 Sist oppdatert: 2017-12-05bibliografisk kontrollert
Svärd, A., Brännvall, E. & Edlund, U. (2015). Rapeseed straw as a renewable source of hemicelluloses: Extraction, characterization and film formation. Carbohydrate Polymers, 133, 179-186
Åpne denne publikasjonen i ny fane eller vindu >>Rapeseed straw as a renewable source of hemicelluloses: Extraction, characterization and film formation
2015 (engelsk)Inngår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 133, s. 179-186Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Polymeric hemicelluloses were extracted by autohydrolysis and alkali from a biomass feed consisting of the stems of rapeseed straw according to a full statistical factorial screening design. Water extraction yielded fractions rich in galactoglucomannan, while alkaline extraction yielded primarily xylan. The extracted galactoglucomannan and xylans had similar molecular weights, while the yield of xylan was higher than the yield of galactoglucomannan. The extracted hemicellulose fractions also contained some lignin (7-15%) and traces of Ca, K, Na, and Si. Free-standing films were prepared from the hemicellulose fractions with different xylan:galactoglucomannan ratios. The rapeseed xylan films showed strain-to-break values >60% without any added plasticizers.

Emneord
Rapeseed/canola straw, Extraction, Autohydrolysis, Alkaline extraction, Xylan, Glucomannan, Film
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-175899 (URN)10.1016/j.carbpol.2015.07.023 (DOI)000361920900024 ()26344270 (PubMedID)2-s2.0-84937926293 (Scopus ID)
Forskningsfinansiär
Swedish Research Council Formas, 2013-844
Merknad

QC 20151113

Tilgjengelig fra: 2015-11-13 Laget: 2015-10-26 Sist oppdatert: 2018-09-07bibliografisk kontrollert
Li Jansson, Z. & Brännvall, E. (2014). Effect of Kraft Cooking Conditions on the Chemical Composition of the Surface and Bulk of Spruce Fibers. Journal of wood chemistry and technology, 34(4), 291-300
Åpne denne publikasjonen i ny fane eller vindu >>Effect of Kraft Cooking Conditions on the Chemical Composition of the Surface and Bulk of Spruce Fibers
2014 (engelsk)Inngår i: Journal of wood chemistry and technology, ISSN 0277-3813, E-ISSN 1532-2319, Vol. 34, nr 4, s. 291-300Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

By varying cooking temperature, alkali charge, ionic strength, and cooking time in Kraft pulping of spruce chips, pulps ranging between kappa numbers 20-80 were obtained. The unbleached Kraft pulp fibers were subjected to mechanical peeling in order to separate the surface material from the bulk of the fibers and the carbohydrate composition and lignin content of the two fractions were analyzed. As expected, the lignin and xylan contents were higher on the fiber surface than in the fiber wall. The percentage of xylan on the fiber surface was fairly constant, independent of different pulping conditions or degree of delignification. The lignin proportion on the fiber surface gradually decreased with decreasing kappa number. At a given kappa number, pulping at a higher temperature resulted in less lignin on the fiber surface, probably because of the higher solubility of lignin at higher temperature. Cooking at lower alkali charge also resulted in lower lignin content on the fiber surface at a given kappa number. In this case, there was more time available for degradation of the surface lignin since the lower alkali charge resulted in longer cooking time needed to reach a certain kappa number.

Emneord
Kraft cooking, spruce, carbohydrate composition, fiber surface, lignin content
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-145564 (URN)10.1080/02773813.2013.872661 (DOI)000333988800004 ()2-s2.0-84896352284 (Scopus ID)
Forskningsfinansiär
Vinnova
Merknad

QC 20140612

Tilgjengelig fra: 2014-06-12 Laget: 2014-05-23 Sist oppdatert: 2017-12-05bibliografisk kontrollert
Organisasjoner
Identifikatorer
ORCID-id: ORCID iD iconorcid.org/0000-0002-8992-3623