Analysis of Degradation Products from Wood and Methods for Detoxification of Lignocellulose Hydrolysates
(2002)- Abstract
- In order to produce fuel ethanol from lignocellulose, it is necessary to hydrolyse the sugar-containing constituents hemicellulose and cellulose. During acid hydrolysis, a number of compounds are formed or liberated in addition to the fermentable monomeric sugars. Several of these compounds might act as inhibitors during the fermentation of the sugars to ethanol. Thus, in order to obtain high ethanol yields and productivities it is necessary to remove these inhibiting compounds prior to fermentation.
A previously well-known detoxification method, alkali detoxification, was carefully investigated with the intention to explain the mechanism behind the detoxification effects as well as to elucidate the optimal conditions... (More) - In order to produce fuel ethanol from lignocellulose, it is necessary to hydrolyse the sugar-containing constituents hemicellulose and cellulose. During acid hydrolysis, a number of compounds are formed or liberated in addition to the fermentable monomeric sugars. Several of these compounds might act as inhibitors during the fermentation of the sugars to ethanol. Thus, in order to obtain high ethanol yields and productivities it is necessary to remove these inhibiting compounds prior to fermentation.
A previously well-known detoxification method, alkali detoxification, was carefully investigated with the intention to explain the mechanism behind the detoxification effects as well as to elucidate the optimal conditions during treatment. The effect of treatments with different forms of alkali on 21 compounds in the hydrolysate was quantified after separation using reversed phase high-performance liquid chromatography (RP-HPLC) and capillary electrophoresis. It was discovered that the inhibitors are not physically removed, but rather chemically converted by this treatment. It was also concluded that compounds added or formed during the treatment might have positive effects on the yeast during fermentation. Furthermore, it was realised that the alkali methods need careful optimisation to obtain maximum detoxification effect in unison with minimum degradation of fermentable sugars.
In addition, a novel method for detoxification was developed, namely countercurrent supercritical fluid extraction. This method relies on the partitioning of inhibitors between the hydrolysate and a supercritical carbon dioxide phase in a pressurised countercurrent flow system. It was discovered that this method decreased the concentration of inhibitors more than the alkali treatments. Moreover, as the extracted inhibitors were trapped and concentrated subsequent to the extraction, this method facilitated the analysis of inhibitors. A relationship between retention in RP-HPLC and extractability was established for the aromatic compounds identified in the hydrolysate.
Furthermore, the enzymatic degradation and simultaneous product formation of glucomannan and O-acetyl-galactoglucomannan, two major hemicellulose constituents, were studied. (Less) - Abstract (Swedish)
- Popular Abstract in Swedish
Med dagens alla transporter finns det ett mycket stort behov av tillgång till billigt och miljövänligt drivmedel. Det bränsle som används i särklass mest är bensin framställd från råolja. Ett problem med bensinen är att den inte tillverkas från förnyelsebara råvarukällor. Detta innebär att när oljan tar slut så går det inte att tillverka mer bensin. Däremot är det idag möjligt att tillverka bränsleetanol från förnyelsebara råvaror från växtriket, t ex trä. En mycket stor fördel med att använda bränsleetanol i jämförelse med bensin, som är ett fossilt bränsle, är att det tillförs ingen extra koldioxid till atmosfären. Det vill säga att den koldioxid som frigörs vid tillverkningen och förbränningen... (More) - Popular Abstract in Swedish
Med dagens alla transporter finns det ett mycket stort behov av tillgång till billigt och miljövänligt drivmedel. Det bränsle som används i särklass mest är bensin framställd från råolja. Ett problem med bensinen är att den inte tillverkas från förnyelsebara råvarukällor. Detta innebär att när oljan tar slut så går det inte att tillverka mer bensin. Däremot är det idag möjligt att tillverka bränsleetanol från förnyelsebara råvaror från växtriket, t ex trä. En mycket stor fördel med att använda bränsleetanol i jämförelse med bensin, som är ett fossilt bränsle, är att det tillförs ingen extra koldioxid till atmosfären. Det vill säga att den koldioxid som frigörs vid tillverkningen och förbränningen av etanolen kan tas upp igen av växtligheten. Däremot vid förbränning av bensin frigörs stora mängder koldioxid som varit bunden i miljontals år. Tyvärr har dagens växtlighet ingen möjlighet att ta tillvara all denna koldioxid och som en konsekvens av detta ökar koldioxidhalten i atmosfären och växthuseffekten skyndas på ytterligare.
Idag kan man ganska lätt och kostnadseffektivt tillverka bränsleetanol från t ex majs och sockerrör. Tyvärr så är tillgången på majs och sockerrör begränsad och dessutom så är råvaran förhållandevis dyr. Däremot finns det stora mängder skogsavfall, jordbruksrester samt industriavfall som kan användas som billig råvara för etanoltillverkning. I Sverige finns det framförallt stora mängder barrved.
Trä består till största delen av cellulosa, hemicellulosa och lignin. Cellulosan och hemicellulosan är polymerer som är uppbyggda av sockermolekyler. Dessa sockermolekyler måste frigöras innan de går att jäsa till etanol. För att frigöra dessa sockermolekyler krävs det att man bryter ned (hydrolyserar) träet. Detta kan göras genom behandling med syra vid höga temperaturer. Tyvärr så bildas och frisätts andra ämnen än sockermolekylerna under hydrolysen. Ett flertal av dessa ämnen har visat sig hämma (inhibera) den jäst som används vid jäsningen. Således krävs det att inhibitorerna oskadliggörs innan fermentationen för att etanoltillverkningen ska vara ekonomiskt försvarbar. Detta kan genomföras med olika detoxifieringsmetoder som antingen tar bort eller bryter ner de aktuella inhibitorerna.
I detta arbete har två olika detoxifieringsmetoder undersökts. Dels detoxifiering med alkali, dvs. behandling vid höga pH-värden. Dels har en ny metod utvecklats som är baserad på extraktion av inhibitorerna med koldioxid vid höga tryck i ett flödessystem. För att kunna utvärdera de kemiska effekterna av dessa detoxifieringsmetoder måste de misstänkta inhibitorerna kunna analyseras. Därför utvecklades även analysmetoder baserade på vätskekromatografi för ett flertal kända inhibitorer. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/464925
- author
- Persson, Per LU
- supervisor
- opponent
-
- Prof Riekkola, Marja-Liisa, Laboratory of Analytical Chemistry, Department of Chemistry, University of Helsinki, Helsinki, Finland
- organization
- publishing date
- 2002
- type
- Thesis
- publication status
- published
- subject
- keywords
- galactoglucomannan, mass spectrometry, liquid chromatography, sugar degradation, detoxification, fermentation inhibitors, lignocellulose hydrolysates, Ethanol production, softwood, Analytical chemistry, Analytisk kemi, countercurrent supercritical fluid extraction
- pages
- 150 pages
- publisher
- Per Persson, Department of Analytical Chemistry, Lund University
- defense location
- Lecture hall B, Chemical Centre, Lund University, Sölvegatan 39, Lund
- defense date
- 2002-10-04 10:15:00
- ISBN
- 91-7422-008-X
- language
- English
- LU publication?
- yes
- additional info
- Article: Effect of Different Forms of Alkali Treatment on Specific Fermentation Inhibitors and on the Fermentability of Lignocellulose Hydrolysates for Production of Fuel EthanolPer Persson, Jessica Andersson, Lo Gorton, Simona Larsson, Nils-Olof Nilvebrant and Leif J. JönssonJ. Agric. Food Chem. 50(19) (2002) 5318-5325. Article: Limits for Alkaline Detoxification of Dilute Acid HydrolysatesNils-Olof Nilvebrant, Per Persson, Anders Reimann, Filipe de Sousa, Lo Gorton and Leif J. JönssonSubmitted to Appl. Biochem. Biotechnol. Article: Supercritical Fluid Extraction of a Lignocellulosic Hydrolysate of Spruce for Detoxification and to Facilitate Analysis of InhibitorsPer Persson, Simona Larsson, Leif J. Jönsson, Nils-Olof Nilvebrant, Björn Sivik, Florentina Munteanu, Lars Thörneby and Lo GortonBiotechnol. Bioeng. 79(6) (2002) 694-700. Article: Countercurrent Supercritical Fluid Extraction of Phenolic Compounds from Aqueous MatricesPer Persson, Zoran Barisic, Arieh Cohen, Lars Thörneby and Lo GortonAnal. Chim. Acta 460 (2002) 1-12. Article: Degradation of Glucomannan and O-Acetyl-Galactoglucomannan by Mannoside- and Glucoside-HydrolasesJon Lundqvist, Per Hägglund, Torny Eriksson, Per Persson, Dominik Stoll, Matti Siika-aho, Lo Gorton and Henrik StålbrandManuscript The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Analytical Chemistry (S/LTH) (011001004)
- id
- 5a945a76-7888-453a-8a9a-e8ac987ea7b2 (old id 464925)
- date added to LUP
- 2016-04-04 10:13:27
- date last changed
- 2018-11-21 20:57:31
@phdthesis{5a945a76-7888-453a-8a9a-e8ac987ea7b2,
abstract = {{In order to produce fuel ethanol from lignocellulose, it is necessary to hydrolyse the sugar-containing constituents hemicellulose and cellulose. During acid hydrolysis, a number of compounds are formed or liberated in addition to the fermentable monomeric sugars. Several of these compounds might act as inhibitors during the fermentation of the sugars to ethanol. Thus, in order to obtain high ethanol yields and productivities it is necessary to remove these inhibiting compounds prior to fermentation.<br/><br>
<br/><br>
A previously well-known detoxification method, alkali detoxification, was carefully investigated with the intention to explain the mechanism behind the detoxification effects as well as to elucidate the optimal conditions during treatment. The effect of treatments with different forms of alkali on 21 compounds in the hydrolysate was quantified after separation using reversed phase high-performance liquid chromatography (RP-HPLC) and capillary electrophoresis. It was discovered that the inhibitors are not physically removed, but rather chemically converted by this treatment. It was also concluded that compounds added or formed during the treatment might have positive effects on the yeast during fermentation. Furthermore, it was realised that the alkali methods need careful optimisation to obtain maximum detoxification effect in unison with minimum degradation of fermentable sugars.<br/><br>
<br/><br>
In addition, a novel method for detoxification was developed, namely countercurrent supercritical fluid extraction. This method relies on the partitioning of inhibitors between the hydrolysate and a supercritical carbon dioxide phase in a pressurised countercurrent flow system. It was discovered that this method decreased the concentration of inhibitors more than the alkali treatments. Moreover, as the extracted inhibitors were trapped and concentrated subsequent to the extraction, this method facilitated the analysis of inhibitors. A relationship between retention in RP-HPLC and extractability was established for the aromatic compounds identified in the hydrolysate.<br/><br>
<br/><br>
Furthermore, the enzymatic degradation and simultaneous product formation of glucomannan and O-acetyl-galactoglucomannan, two major hemicellulose constituents, were studied.}},
author = {{Persson, Per}},
isbn = {{91-7422-008-X}},
keywords = {{galactoglucomannan; mass spectrometry; liquid chromatography; sugar degradation; detoxification; fermentation inhibitors; lignocellulose hydrolysates; Ethanol production; softwood; Analytical chemistry; Analytisk kemi; countercurrent supercritical fluid extraction}},
language = {{eng}},
publisher = {{Per Persson, Department of Analytical Chemistry, Lund University}},
school = {{Lund University}},
title = {{Analysis of Degradation Products from Wood and Methods for Detoxification of Lignocellulose Hydrolysates}},
year = {{2002}},
}