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Annsofi Jonsson - One of the best experts on this subject based on the ideXlab platform.
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influence of air and nitrogen sparging on flux during ultrafiltration of Hemicelluloses extracted from wheat bran
Separation and Purification Technology, 2019Co-Authors: Johan Thuvander, Annsofi JonssonAbstract:Abstract Ultrafiltration can be used to concentrate arabinoxylan isolated from wheat bran. Prefiltration with diatomaceous earth and air sparging during ultrafiltration of the alkaline Hemicellulose solution were both found to increase the flux, while nitrogen sparging had no effect. The flux of the untreated solution was 51 L/m2 h, while the flux after prefiltration of the solution with diatomaceous earth was 62 L/m2 h. After 5 h of air sparging during ultrafiltration of the prefiltered solution the flux was 230 L/m2 h. However, sparging the prefiltered solution with nitrogen gas had no effect on the flux. This shows that the increase in flux was not due to the reduction of concentration polarization by sparging per se. Size-exclusion chromatography showed that sparging with air caused a reduction in the size of Hemicelluloses >100 kDa to 10–100 kDa, which is believed to be due to oxidative degradation of Hemicelluloses. This size reduction of the Hemicelluloses is likely the main cause of the increased flux. The retention of Hemicelluloses during ultrafiltration with a ceramic membrane with a nominal cut-off of 10 kDa was 96% in all experiments, except at the end of the experiment with the prefiltered, air-sparged solution, when the retention decreased to 93% due to the size reduction of the Hemicelluloses. Air sparging seems to be an efficient flux enhancing method with limited negative influence on the molecular size of Hemicelluloses.
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extraction of galactoglucomannan from thermomechanical pulp mill process water by microfiltration and ultrafiltration influence of microfiltration membrane pore size on ultrafiltration performance
Chemical Engineering Research & Design, 2016Co-Authors: Johan Thuvander, Annsofi JonssonAbstract:Galactoglucomannan is the major Hemicellulose in process water from thermomechanical pulping of spruce. The recovery of Hemicelluloses from this process water would both reduce the load on pulp mill water treatment plants and yield a biopolymer suitable as a raw material for renewable products. One method of recovering these Hemicelluloses is two-stage filtration employing microfiltration to remove large contaminants, such as suspended matter and colloidal extractives, followed by ultrafiltration to concentrate and purify the Hemicelluloses from low molecular mass contaminants. This investigation shows that a microfiltration membrane with a pore size of 0.1μm removes colloidal extractives while still maintaining a high amount of high molecular mass Hemicelluloses in the microfiltration permeate. The removal of extractives resulted in an increase in the initial flux during the subsequent ultrafiltration step from 90 L/m2h to over 200 L/m2h. (Less)
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impact of prefiltration on membrane performance during isolation of Hemicelluloses extracted from wheat bran
Separation and Purification Technology, 2013Co-Authors: Holger Krawczyk, Anders Arkell, Annsofi JonssonAbstract:Hemicelluloses extracted from wheat bran have to be separated from impurities in order to obtain a valuable product at high concentration and purity. A previous investigation showed that separation by ultrafiltration is possible, but the flux was low due to the high viscosity of the solution and the presence of gel-forming substances in the solution. In this investigation the influence of prefiltration on solution viscosity and ultrafiltration performance was investigated. The viscosity of the Hemicellulose solution after extraction was considerably reduced with both prefiltration methods tested, leading to a substantial increase in flux during ultrafiltration. The highest flux achieved without pretreatment was about 75 l/m2 h, and was increased to 225 and 440 l/m2 h after dead-end filtration and microfiltration, respectively. However, the loss of Hemicelluloses was considerable during microfiltration, but <5% during dead-end filtration. After prefiltration by dead-end filtration, Hemicelluloses could be successfully concentrated and purified by ultrafiltration. Eighty percent of the initial volume was removed during concentration at an average flux of 155 l/m2 h. At the same time, the concentration and purity of the Hemicelluloses increased from 7.6 g/l and 15% to 31.6 g/l and 31%, respectively. The results obtained in this investigation indicate that dead-end filtration could be a useful form of pretreatment before ultrafiltration when recovering Hemicelluloses extracted from wheat bran.
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combined membrane filtration and enzymatic treatment for recovery of high molecular mass Hemicelluloses from chemithermomechanical pulp process water
Chemical Engineering Journal, 2013Co-Authors: Holger Krawczyk, Petri Oinonen, Annsofi JonssonAbstract:Hemicelluloses with high molecular mass are needed for the manufacture of value added products such as food packaging barrier films. In this work such molecules were recovered from chemithermomechanical pulp (CTMP) process water using an innovative three-stage process comprising membrane separation and enzymatic treatment with laccase. Microfiltration followed by ultrafiltration was found to be a suitable combination in the first stage, providing a concentrated and purified Hemicellulose fraction suitable for enzymatic treatment. In both membrane processes a high average flux (260 and 115 l/m2 h) and a low fouling tendency were observed. A marked increase in the average molecular mass of Hemicelluloses with bound lignin moieties was achieved by laccase treatment in the second stage. The enzymatically crosslinked Hemicelluloses were finally recovered in the third stage using ultrafiltration. In the final high molecular mass solution the Hemicellulose concentration was 54 g/l, the contribution of Hemicelluloses to the total solids content 43%, and the viscosity of the solution 27 mPa s. The results demonstrate that a Hemicellulose fraction of high quality can be produced from CTMP process water, and that this could constitute a suitable feedstock for the production of, for example, barrier films for renewable packaging.
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isolation of Hemicelluloses by ultrafiltration of thermomechanical pulp mill process water influence of operating conditions
Chemical Engineering Research & Design, 2010Co-Authors: Tobias Persson, Annsofi JonssonAbstract:Hemicelluloses could be used to replace fossil-based materials in several high-value-added products. Today, vast amounts of Hemicelluloses are discharged from pulp mills all over the world as waste, but these could be isolated by membrane filtration, and utilized in various applications. In this study, the Hemicellulose galactoglucomannan was isolated from process water from a thermomechanical pulp mill using ultrafiltration. The retention of Hemicelluloses and lignin, and the flux and fouling of three ultrafiltration membranes (ETNA01, ETNA10 and UFX5) were studied at various operating conditions. One of the membranes (UFX5) was found to have a high Hemicellulose retention (above 90%) independent of flux and pressure. With the ETNA01 membrane it was impossible to combine a high flux with high Hemicellulose retention, while with the ETNA10 membrane the Hemicellulose retention could be increased above 90% by running at transmembrane pressures above the critical flux. The UFX5 membrane could be used at the temperature of the process water in the pulp mill (75-85 degrees C), while the ETNA10 membrane could only withstand temperatures below 60 degrees C, increasing the cost due to the need to cool the process water. However, the susceptibility of UFX5 to fouling was much greater than for ETNA10, which would increase the cleaning cost of the UFX5 membrane. (C) 2010 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved. (Less)
Chaoguang Tian - One of the best experts on this subject based on the ideXlab platform.
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evidence of a critical role for cellodextrin transporte 2 cdt 2 in both cellulose and Hemicellulose degradation and utilization in neurospora crassa
PLOS ONE, 2014Co-Authors: Ruimeng Gu, Bang Wang, Jingen Li, Chaoguang TianAbstract:CDT-1 and CDT-2 are two cellodextrin transporters discovered in the filamentous fungus Neurospora crassa. Previous studies focused on characterizing the role of these transporters in only a few conditions, including cellulose degradation, and the function of these two transporters is not yet completely understood. In this study, we show that deletion of cdt-2, but not cdt-1, results in growth defects not only on Avicel but also on xylan. cdt-2 can be highly induced by xylan, and this mutant has a xylodextrin consumption defect. Transcriptomic analysis of the cdt-2 deletion strain on Avicel and xylan showed that major cellulase and hemicellulase genes were significantly down-regulated in the cdt-2 deletion strain and artificial over expression of cdt-2 in N. crassa increased cellulase and hemicellulase production. Together, these data clearly show that CDT-2 plays a critical role in Hemicellulose sensing and utilization. This is the first time a sugar transporter has been assigned a function in the Hemicellulose degradation pathway. Furthermore, we found that the transcription factor XLR-1 is the major regulator of cdt-2, while cdt-1 is primarily regulated by CLR-1. These results deepen our understanding of the functions of both cellodextrin transporters, particularly for CDT-2. Our study also provides novel insight into the mechanisms for Hemicellulose sensing and utilization in N. crassa, and may be applicable to other cellulolytic filamentous fungi.
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Evidence of a critical role for cellodextrin transporte 2 (CDT-2) in both cellulose and Hemicellulose degradation and utilization in Neurospora crassa
2014Co-Authors: Pengli Cai, Bang Wang, Li Wan, Chaoguang TianAbstract:CDT-1 and CDT-2 are two cellodextrin transporters discovered in the filamentous fungus Neurospora crassa. Previous studies focused on characterizing the role of these transporters in only a few conditions, including cellulose degradation, and the function of these two transporters is not yet completely understood. In this study, we show that deletion of cdt-2, but not cdt-1, results in growth defects not only on Avicel but also on xylan. cdt-2 can be highly induced by xylan, and this mutant has a xylodextrin consumption defect. Transcriptomic analysis of the cdt-2 deletion strain on Avicel and xylan showed that major cellulase and hemicellulase genes were significantly down-regulated in the cdt-2 deletion strain and artificial over expression of cdt-2 in N. crassa increased cellulase and hemicellulase production. Together, these data clearly show that CDT-2 plays a critical role in Hemicellulose sensing and utilization. This is the first time a sugar transporter has been assigned a function in the Hemicellulose degradation pathway. Furthermore, we found that the transcription factor XLR-1 is the major regulator of cdt-2, while cdt-1 is primarily regulated by CLR-1. These results deepen our understanding of the functions of both cellodextrin transporters, particularly for CDT-2. Our study also provides novel insight into the mechanisms fo
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deciphering transcriptional regulatory mechanisms associated with Hemicellulose degradation in neurospora crassa
Eukaryotic Cell, 2012Co-Authors: Chaoguang Tian, Spencer Diamond, Louise N GlassAbstract:Hemicellulose, the second most abundant plant biomass fraction after cellulose, is widely viewed as a potential substrate for the production of liquid fuels and other value-added materials. Degradation of Hemicellulose by filamentous fungi requires production of many different enzymes, which are induced by biopolymers or its derivatives and regulated mainly at the transcriptional level through transcription factors (TFs). Neurospora crassa, a model filamentous fungus, expresses and secretes enzymes required for plant cell wall deconstruction. To better understand genes specifically associated with degradation of Hemicellulose, we applied secretome and transcriptome analysis to N. crassa grown on beechwood xylan. We identified 34 secreted proteins and 353 genes with elevated transcription on xylan. The xylanolytic phenotype of strains with deletions in genes identified from the secretome and transcriptome analysis of the wild type was assessed, revealing functions for known and unknown proteins associated with Hemicellulose degradation. By evaluating phenotypes of strains containing deletions of predicted TF genes in N. crassa, we identified a TF (XLR-1; xylan degradation regulator 1) essential for Hemicellulose degradation that is an ortholog to XlnR/XYR1 in Aspergillus and Trichoderma species, respectively, a major transcriptional regulator of genes encoding both cellulases and hemicellulases. Deletion of xlr-1 in N. crassa abolished growth on xylan and xylose, but growth on cellulose and cellulolytic activity were only slightly affected. To determine the regulatory mechanisms for Hemicellulose degradation, we explored the transcriptional regulon of XLR-1 under xylose, xylanolytic, and cellulolytic conditions. XLR-1 regulated only some predicted hemicellulase genes in N. crassa and was required for a full induction of several cellulase genes. Hemicellulase gene expression was induced by a combination of release from carbon catabolite repression (CCR) and induction. This systematic analysis illustrates the similarities and differences in regulation of Hemicellulose degradation among filamentous fungi.
Johan Thuvander - One of the best experts on this subject based on the ideXlab platform.
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techno economic impact of air sparging prior to purification of alkaline extracted wheat bran Hemicelluloses by membrane filtration
Separation and Purification Technology, 2020Co-Authors: Johan ThuvanderAbstract:Abstract Air sparging of alkaline-extracted wheat bran Hemicelluloses prior to ultrafiltration has been shown to increase the flux. The techno-economic impact of air sparging on the cost of concentration and purification of wheat bran Hemicelluloses by ultrafiltration and diafiltration was studied in this work. Two alkaline Hemicellulose solutions were purified until the conductivity of the diafiltration permeate was
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influence of air and nitrogen sparging on flux during ultrafiltration of Hemicelluloses extracted from wheat bran
Separation and Purification Technology, 2019Co-Authors: Johan Thuvander, Annsofi JonssonAbstract:Abstract Ultrafiltration can be used to concentrate arabinoxylan isolated from wheat bran. Prefiltration with diatomaceous earth and air sparging during ultrafiltration of the alkaline Hemicellulose solution were both found to increase the flux, while nitrogen sparging had no effect. The flux of the untreated solution was 51 L/m2 h, while the flux after prefiltration of the solution with diatomaceous earth was 62 L/m2 h. After 5 h of air sparging during ultrafiltration of the prefiltered solution the flux was 230 L/m2 h. However, sparging the prefiltered solution with nitrogen gas had no effect on the flux. This shows that the increase in flux was not due to the reduction of concentration polarization by sparging per se. Size-exclusion chromatography showed that sparging with air caused a reduction in the size of Hemicelluloses >100 kDa to 10–100 kDa, which is believed to be due to oxidative degradation of Hemicelluloses. This size reduction of the Hemicelluloses is likely the main cause of the increased flux. The retention of Hemicelluloses during ultrafiltration with a ceramic membrane with a nominal cut-off of 10 kDa was 96% in all experiments, except at the end of the experiment with the prefiltered, air-sparged solution, when the retention decreased to 93% due to the size reduction of the Hemicelluloses. Air sparging seems to be an efficient flux enhancing method with limited negative influence on the molecular size of Hemicelluloses.
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extraction of galactoglucomannan from thermomechanical pulp mill process water by microfiltration and ultrafiltration influence of microfiltration membrane pore size on ultrafiltration performance
Chemical Engineering Research & Design, 2016Co-Authors: Johan Thuvander, Annsofi JonssonAbstract:Galactoglucomannan is the major Hemicellulose in process water from thermomechanical pulping of spruce. The recovery of Hemicelluloses from this process water would both reduce the load on pulp mill water treatment plants and yield a biopolymer suitable as a raw material for renewable products. One method of recovering these Hemicelluloses is two-stage filtration employing microfiltration to remove large contaminants, such as suspended matter and colloidal extractives, followed by ultrafiltration to concentrate and purify the Hemicelluloses from low molecular mass contaminants. This investigation shows that a microfiltration membrane with a pore size of 0.1μm removes colloidal extractives while still maintaining a high amount of high molecular mass Hemicelluloses in the microfiltration permeate. The removal of extractives resulted in an increase in the initial flux during the subsequent ultrafiltration step from 90 L/m2h to over 200 L/m2h. (Less)
Herbert Sixta - One of the best experts on this subject based on the ideXlab platform.
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Ionic liquid extraction method for upgrading eucalyptus kraft pulp to high purity dissolving pulp
Cellulose, 2014Co-Authors: Annariikka Roselli, Michael Hummel, Alireza Monshizadeh, Thaddeus Maloney, Herbert SixtaAbstract:High purity cellulose from wood is an important raw material for many applications such as cellulosic fibers, films or the manufacture of various cellulose acetate products. Hitherto, multi-step refining processes are needed for an efficient Hemicellulose removal, most of them suffering from severe cellulose losses. Recently, a novel method for producing high purity cellulose from bleached paper grade birch kraft pulp was presented. In this so called IONCELL process, Hemicelluloses are extracted by an ionic liquid–water mixture and both fractions can be recovered without yield losses or polymer degradation. Herein, it is demonstrated that bleached Eucalyptus urograndis kraft pulp can be refined to high purity acetate grade pulp via the IONCELL process. The Hemicellulose content could be reduced from initial 16.6 to 2.4 wt% while persevering the cellulose I crystal form by using an optimized 1-ethyl-3-methylimidazolium dimethylphosphate-water mixture as the extraction medium. The degree of polymerization was then reduced by a sulfuric acid treatment for subsequent acetylation of the pulp, resulting in a final Hemicellulose content of 2.2 wt%. When pre-treating the pulp enzymatically with endoxylanase, the final Hemicellulose content could be reduced even to 1.7 wt%. For comparison, the eucalyptus kraft pulp was also subjected to cold caustic extraction and the same subsequent acid treatment which led to 3.9 wt% of residual Hemicelluloses. The performance in acetylation of all produced pulps was tested and compared to commercial acetate grade pulp. The endoxylanase-IONCELL-treated pulp showed superior properties. Thus, an ecologically and economically efficient alternative for the production of highest value cellulose pulp is presented.
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ionic liquid extraction method for upgrading eucalyptus kraft pulp to high purity dissolving pulp
Cellulose, 2014Co-Authors: Annariikka Roselli, Michael Hummel, Alireza Monshizadeh, Thaddeus Maloney, Herbert SixtaAbstract:High purity cellulose from wood is an important raw material for many applications such as cellulosic fibers, films or the manufacture of various cellulose acetate products. Hitherto, multi-step refining processes are needed for an efficient Hemicellulose removal, most of them suffering from severe cellulose losses. Recently, a novel method for producing high purity cellulose from bleached paper grade birch kraft pulp was presented. In this so called IONCELL process, Hemicelluloses are extracted by an ionic liquid–water mixture and both fractions can be recovered without yield losses or polymer degradation. Herein, it is demonstrated that bleached Eucalyptus urograndis kraft pulp can be refined to high purity acetate grade pulp via the IONCELL process. The Hemicellulose content could be reduced from initial 16.6 to 2.4 wt% while persevering the cellulose I crystal form by using an optimized 1-ethyl-3-methylimidazolium dimethylphosphate-water mixture as the extraction medium. The degree of polymerization was then reduced by a sulfuric acid treatment for subsequent acetylation of the pulp, resulting in a final Hemicellulose content of 2.2 wt%. When pre-treating the pulp enzymatically with endoxylanase, the final Hemicellulose content could be reduced even to 1.7 wt%. For comparison, the eucalyptus kraft pulp was also subjected to cold caustic extraction and the same subsequent acid treatment which led to 3.9 wt% of residual Hemicelluloses. The performance in acetylation of all produced pulps was tested and compared to commercial acetate grade pulp. The endoxylanase-IONCELL-treated pulp showed superior properties. Thus, an ecologically and economically efficient alternative for the production of highest value cellulose pulp is presented.
David Plackett - One of the best experts on this subject based on the ideXlab platform.
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sustainable films and coatings from Hemicelluloses a review
Biomacromolecules, 2008Co-Authors: Natanya Majbritt Louie Hansen, David PlackettAbstract:This review summarizes the results of past research on films and coatings from Hemicelluloses, biopolymers that are as yet relatively unexploited commercially. The targeted uses of Hemicelluloses have primarily been packaging films and coatings for foodstuffs as well as biomedical applications. Oxygen permeability of Hemicellulose films, an important characteristic for food packaging, was typically comparable to values found for other biopolymer films such as amylose and amylopectin. As expected, the modification of Hemicelluloses to create more hydrophobic films reduced the water vapor permeability. However, modified Hemicellulose coatings intended for food still exhibited water vapor permeabilities several magnitudes higher than those of other polymers currently used for this purpose. Research on Hemicelluloses for biomedical applications has included biocompatible hydrogels and coatings and material surfaces with enhanced cell affinity. Numerous possibilities exist for chemically modifying hemicellulos...
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sustainable films and coatings from Hemicelluloses a review
Biomacromolecules, 2008Co-Authors: Natanya Majbritt Louie Hansen, David PlackettAbstract:This review summarizes the results of past research on films and coatings from Hemicelluloses, biopolymers that are as yet relatively unexploited commercially. The targeted uses of Hemicelluloses have primarily been packaging films and coatings for foodstuffs as well as biomedical applications. Oxygen permeability of Hemicellulose films, an important characteristic for food packaging, was typically comparable to values found for other biopolymer films such as amylose and amylopectin. As expected, the modification of Hemicelluloses to create more hydrophobic films reduced the water vapor permeability. However, modified Hemicellulose coatings intended for food still exhibited water vapor permeabilities several magnitudes higher than those of other polymers currently used for this purpose. Research on Hemicelluloses for biomedical applications has included biocompatible hydrogels and coatings and material surfaces with enhanced cell affinity. Numerous possibilities exist for chemically modifying Hemicelluloses, and fundamental studies of films from modified Hemicelluloses have identified other potential applications, including selective membranes.