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Hemicelluloses (HC) are the second most abundant plant polysaccharides after cellulose, constituting 25-30% of plant materials. In spite of their abundance, HC are not effectively utilized. Recently, considerable interest has been directed to HC-based biomaterials because of their high oxygen barrier properties, which has potential in food packaging applications. In this study, HC were extracted from sugarcane bagasse and southern yellow pine using a hydrothermal technique which utilizes hot compressed water without catalyst. The parameters affecting the yield of extracted HC such as temperature, time and pressure, were tested and optimized. Eighty four percent of xylose was extracted from sugarcane bagasse at the optimum condition, 180 °C 30 min and 1 MPa pressure. In the case of southern yellow pine, 79% of the mannose was extracted at 190 °C for 10 min and 2 MPa pressure. Concentration and isolation of HC from bagasse and southern yellow pine HC extract were performed by membrane filtration and freeze drying systems. Isolated HC were characterized by FT-IR and 13C NMR techniques and used as a starting material for film preparation. Films were prepared in 0/100, 50/50, 60/40, 70/30 and 80/20% ratios of HC and sodium carboxymethylcellulose (CMC). Thirty five percent of sorbitol (w/w of HC and CMC weight) was also added as a plasticizer. Films were evaluated by measuring water absorption, water vapor permeability (WVP), tensile property and oxygen barrier capability. At 55% relative humidity (RH) and 25 °C the water absorption of both sugarcane bagasse and southern yellow pine HC-based films tended to increase as HC content increased. The lowest WVP of sugarcane bagasse (3.84e-12 g/Pa h m) and southern yellow pine HC films (2.18e-12 g/Pa h m) were determined in 60/40 HC/CMC films. Tensile test results showed that as HC content increases the Young’s modulus decreases, deflection at maximum load and percentage of strain at break increase. It implies that the film properties are changing from stiff to elastic. The oxygen permeability for 60/40 bagasse HC/CMC film was 0.005265 cc μm / (m2 day kPa) and for 70/30 pine HC/CMC film was 0.007570 cc μm /(m2 day kPa).

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Hemicelluloses are the most abundant plant polysaccharides available next to cellulose. The industrial usage of hemicelluloses however is very limited to nonexistent. As wood is processed in the Kraft pulping process, a large fraction of these hemicelluloses is degraded to low molecular weight isosaccharinic acids, which end up in the black liquor with the degraded lignin. The extraction of hemicelluloses prior to pulping and re-introducing them as a wet-end additive has been shown to improve the paper tensile -, burst- and tear index properties. It has also been proven that the pre-extraction of hemicelluloses does not negatively affect the downstream paper products. The objective of this project was to study the modification of extracted wood based hemicelluloses, focusing on glucuronoxylan in Eucalyptus grandis (E. grandis), by chemical and physical methods identified from literature. The methods investigated were; cationisation, carboxymethylation and ultrasound treatment. The modified hemicelluloses were applied as a wet-end additive to E. grandis pulp to test their effect on strength properties. An addition protocol for the new hemicelluloses additives was developed in this investigation. The E. grandis glucuronoxylan was extracted by using the mild alkali extraction method of Höije et al. The characterization of the extracted solids from the pure E. grandis chips showed that 4-O-methylglucuronoxylan was extracted with an average uronic acid content of 17.3 wt.%. The hemicelluloses yield was 50.75 wt.%, based on dry biomass, containing 40.76 wt.% xylose units. The solids still contained 26.6 wt.% lignin after extraction. The presence of lignin in the extracted solids indicated that the delignification step in the extraction method used, was not sufficient for the E. grandis biomass. The molecular weight of the extracted glucuronoxylan was 51 589 g.mol-1. It was proven that the modification methods from literature are applicable to E. grandis glucuronoxylan, producing cationic, carboxymethyl and low uronic acid content 4-O-methylglucuronoxylan. The cationic E. grandis glucuronoxylan produced had a degree of substitution between 0.05 and 0.73 and an uronic acid content ranging between 6.12 and 12.70 wt.%. The carboxymethylated E. grandis glucuronoxylan had a degree of substitution between 0.05 and 0.11 with a uronic acid content between 10.2 and 21.4%. The sonication of E. grandis glucuronoxylan resulted in products with molecular weights ranging from 54 856 to 57 347 g.mol-1 and uronic acid contents between 13.0 and 18.4 wt.%. Handsheet formation with the modified hemicelluloses added, showed that the cationic E. grandis glucuronoxylan improved handsheet strength and surface properties the best. Cationic E. grandis glucuronoxylan also outperformed the industrial additive, cationic starch at a dosage level of 1.0 wt.%. The addition protocol development for cationic E. grandis glucuronoxylan showed it is possible to add cationic hemicellulose before refining, which results in maximum contact time with the pulp fibres without inhibiting the effect of the additive. Cationic hemicellulose additive added before refining led to a decrease in refining energy required to reach the desired strength properties. It was concluded that the cationisation and carboxymethylation methods chosen from literature were applicable to the South African grown E. grandis glucuronoxylan. The cationic glucuronoxylan showed the best improvement in handsheet strength and surface properties. Cationic E. grandis glucuronoxylan could be added before refining in the papermaking process for maximum effectiveness of this new strength additive. The use of hemicellulosic additives will be more sustainable than starch, due to the presence of hemicelluloses in the initial biomass that enters the pulp and paper process. / AFRIKAANSE OPSOMMING: Hemiselluloses is die mees volopste plantpolisakkariede naas sellulose, alhoewel die industriële gebruik van hierdie hemiselluloses tans nog beperk is. In die huidige verwerking van hout met behulp van die Kraft verpulpingsproses word die hemiselluloses gedegradeer na lae molukulêre massa isosakkariniese sure wat saam met die lignien in die swartloog afvalstroom eindig. Die ekstraksie van hierdie hemiselluloses vóór die verpulpingsproses, en latere byvoeging as ‘n sterktebymiddel in die papier vervaardigings proses, kan die papier treksterkte, bars-, en skeur eienskappe verbeter. Dit is aangetoon dat die ekstraksie van hemiselluloses vóór die verpulpingsproses nie die opbrengs en kwaliteit van papierprodukte negatief beïnvloed nie. Die doelwit van hierdie projek was om die modifikasie van hemiselluloses, ge-ekstraheer uit Eucalyptus grandis (E. grandis) hout vóór verpulping, deur middle van chemiese en fisiese metodes uit literatuur te ondersoek. Die projek het spesifiek gefokus op glukuronoxilaan verkry uit E. grandis en wat gemodifiseer is met met behulp van kationisasie, karboksimetilering en ultraklank behandeling. Die gemodifiseerde hemiselluloses is daarna benut as ‘n nat-kant bymiddel tot E. grandis pulp, om die sterkte eienskappe van papier te ondersoek. ‘n Toevoegingsprotokol is vir die nuwe hemisellulose bymiddel ontwikkel in hierdie ondersoek. Die glukuronoxilaan is deur middle van die matige alkali-ekstraksie metode van Höije geekstraheer. Karakterisering van die vastestof residu wat uit die suiwer E. grandis biomassa geekstraheer is het getoon dat 4-O-metielglukuronoxilaan geëkstraheer is, met ‘n gemiddelde glukuronosuurinhoud van 17.3 massa%. Die hemisellulose opbrengs was 50.75 massa%, gebaseer op droë biomassa, en dit het 40.76 massa% xylose-eenhede bevat. Die lignieninhoud van die soliedes was 26.6 massa% na ekstraksie. Die teenwoordigheid van die lignien het daarop gedui dat die delignifikasie (van die metode) van E. grandis biomassa nie voldoende was nie. Die molekulêre massa van die geëkstraheerde glukuronoxilaan was 51 589 g.mol-1. Dit is bewys dat die modifikasiemetodes toepasbaar is op die E. grandis glukuronoxilaan, en dat kationiese, karboksiemetiel en lae glukuronosuur 4-0-metielglukurono-xilaan geproduseer is. Die kationiese glukuronoxilaan het ‘n graad van substitusie tussen 0.05 en 0.73 gehad, met ‘n glukuronosuur inhoud tussen 6.12 en 12.70 massa%. Die karboksiemetielglukuronoxilaan het ‘n graad van substitusie tussen 0.05 en 0.11 gehad, met glukuronosuurinhoude tussen 10.2 en 21.4 massa%. Die ultraklankbehandelde glukuronoxilaan het molekulêre massas tussen 54 856 en 57 347 g.mol-1 gehad met glukuronosuurinhoude tussen 13.0 en 18.4 massa%. Papier handvelproduksie van die pulp waar tydens die gemodifiseerde hemiselluloses toe gevoeg is, het aangedui dat die kationiese E. grandis glukuronoxilaan die grootste sterkte- en oppervlakeienskappe verbetering getoon het. Die kationiese glukuronoxilaan het ook, in terme van verbetering van pulpeienskappe, die industrieële kationiese stysel bymiddel oortref, by ‘n doserings vlak van 1.0 massa%. Die toevoegingsprotokol ontwikkeling vir die kationiese E. grandis glukuronoxilaan het getoon dat hemiselluloses byvoeging tot die papiermaakproses vóór die raffinerings stadium die mees gunstige was, met dosering tussen 0.5 en 2.0 massa%. Die byvoeging van kationiese hemiselluloses vóór raffinering het gelei tot ‘n afname in raffineringsenergie wat benodig word om die verlangde sterkteeienskap te verkry. Dit is bevesting gekose kationisasie- en karboksimetilerings metodes toepasbaar op die Suid Afrikaanse E. grandis glukuronoxilaan was. Die kationiese glukuronoxilaan het die grootste verbetering in pulpeienskappe, in terme van handvelsterkte en oppervlakeienskappe, getoon. Kationiese glukuronoxilaan moet vóór raffinering tot die papiermaakproses bygevoeg word vir maksimum doeltreffendheid van hierdie nuwe sterktebymiddel. Die gebruik van hemisellulose bymiddels sal meer volhoubaar wees as stysel, omdat die hemiselluloses wat in die biomassa aanwesig is, in die proses teruggrplaas word.

京都大学 / 新制・課程博士 / 博士(エネルギー科学) / 甲第24922号 / エネ博第464号 / 新制||エネ||87(附属図書館) / 京都大学大学院エネルギー科学研究科エネルギー社会・環境科学専攻 / (主査)教授 河本 晴雄, 教授 亀田 貴之, 准教授 南 英治 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

The sulfite pulping process is today practised in only a small number of pulp mills around the globe and the number of sulfite mills that use sodium as the base (cation) is less than five. However, due to the increasing interest in the wood based biorefinery concept, the benefits of sulfite pulping and especially the sodium based variety, has recently gained a lot of interest. It was therefore considered to be of high importance to further study the sodium based sulfite process to investigate if its benefits could be better utilized in the future in the production of dissolving pulps. Of specific interest was to investigate how the pulping conditions in the initial part of the cook (≥ 60 % pulp yield) should be performed in the best way. Thus, this thesis is focused on the initial phase of single stage sodium bisulfite cooking of either 100 % spruce or 100 % pine wood chips. The cooking experiments were carried out with either a lab prepared or a mill prepared cooking acid and the temperature and cooking time were varied. Activation energies for different wood components were investigated as well as side reactions concerning the formation of thiosulfate and sulfate. / Single stage sodium bisulfite cooking was carried out on either spruce or pine wood chips to investigate the influence of several process parameters in the initial phase of such a cook i.e. between 100 % and 60 % pulp yield. The cooking experiments were carried out with either a lab prepared or a mill prepared cooking acid and the temperature and time in the initial stage were varied. The influence of dissolved organics and inorganics components in the cooking liquor on the final pulp properties and side reactions were investigated. The impact of temperature and time on the pulp components were analyzed with respect to carbohydrates, lignin, extractives and thiosulfate. Kinetic equations were developed and the activation energies for delignification and carbohydrate dissolution were calculated using the Arrhenius equation. It was found that if using a mill prepared cooking acid, this had a beneficial effect with respect to side reactions, better extractives removal and higher pH stability during the cook, compared to a corresponding cook with a lab prepared cooking acid. Cooking with mill prepared and lab prepared cooking acids showed the same behaviour with respect to delignification and carbohydrate degradation, but the lab acid experiments resulted in a higher thiosulfate formation during the cook. The cellulose yield was not affected at all during the initial phase of the sulfite cook verifying earlier results by other researchers. The temperature had an influence on both the delignification rate and the rate of hemicelluloses removal.  The corresponding activation energies were found to increase in the following order; cellulose, xylan, glucomannan and lignin. / <p>Artikel 1: "The Initial Phase of Sodium Bisulfite Pulping of Spruce: Part 1" ingick i avhandlingen som manuskript. Nu publicerad.</p>

Este trabalho visa a valorização da fração de xilana presente na polpa kraft branqueada de eucalipto como matéria prima para a produção de xilitol e derivados de xilose. O presente estudo é dividido em dois objetivos principais. A primeira parte é dedicada ao estudo da otimização do processo de extração da xilana da polpa kraft industrial. Para fazer este estudo foi estabelecido um planejamento fatorial utilizando como variáveis a concentração da solução de hidróxido de sódio, o tempo de extração e a razão sólido/líquido (polpa/solução). A resposta empregada para avaliar a eficiência das extrações foi o rendimento de xilana extraída. A melhor condição de extração foi obtida com solução de hidróxido de sódio 14% (m/v), 180 minutos e razão sólido/líquido de 0,06, resultando em 98% de xilana extraída. Na segunda parte, estudou-se o processo de recuperação da xilana a partir das soluções de extração por técnicas de precipitação utilizando ácidos e/ou álcoois. Devido à presença de impurezas no precipitado, estudou-se também o efeito da lavagem dos mesmos. A partir da caracterização das amostras isoladas pode-se concluir que as xilanas isoladas utilizando metanol, isopropanol, ácido clorídrico e ácido nítrico apresentaram graus de pureza comparáveis à de amostras comerciais de xilana. / This work aims the extraction of xylans present in bleached eucalyptus kraft pulp. The extracted xylans can be used as raw material for the production of xylitol and xylose derivatives. The study is divided in two main objectives: The first part is dedicated to optimize the conditions to extract xylan from industrial Kraft pulps. To achieve this, a factorial planning design was established using as variables the concentration of sodium hydroxide solution, extraction time and the solid (pulp) to solution ratio. The response to employed to evaluate the extraction efficiency was the recovery xylan yield. The best extraction condition was obtained with 14% (w/v) sodium hydroxide, 180 minutes and solid (pulp) to liquid ratio of 0.06, which lead to approximately 98% of xylan recovery yields. In the second part of this work, the recovery of the pure xylan from the aqueous solution was carried out by precipitation techniques using acids and / or alcohols. Due to the presence of impurities in the precipitates, it was also studied the effect of washing to purify the samples. From the characterization of the isolated samples it can be concluded that xylans precipitated by using methanol, isopropanol, hydrochloric acid and nitric acid, produced xylans samples with similar level of purity when compared to the commercial standard xylan.

Este trabalho visa a valorização da fração de xilana presente na polpa kraft branqueada de eucalipto como matéria prima para a produção de xilitol e derivados de xilose. O presente estudo é dividido em dois objetivos principais. A primeira parte é dedicada ao estudo da otimização do processo de extração da xilana da polpa kraft industrial. Para fazer este estudo foi estabelecido um planejamento fatorial utilizando como variáveis a concentração da solução de hidróxido de sódio, o tempo de extração e a razão sólido/líquido (polpa/solução). A resposta empregada para avaliar a eficiência das extrações foi o rendimento de xilana extraída. A melhor condição de extração foi obtida com solução de hidróxido de sódio 14% (m/v), 180 minutos e razão sólido/líquido de 0,06, resultando em 98% de xilana extraída. Na segunda parte, estudou-se o processo de recuperação da xilana a partir das soluções de extração por técnicas de precipitação utilizando ácidos e/ou álcoois. Devido à presença de impurezas no precipitado, estudou-se também o efeito da lavagem dos mesmos. A partir da caracterização das amostras isoladas pode-se concluir que as xilanas isoladas utilizando metanol, isopropanol, ácido clorídrico e ácido nítrico apresentaram graus de pureza comparáveis à de amostras comerciais de xilana. / This work aims the extraction of xylans present in bleached eucalyptus kraft pulp. The extracted xylans can be used as raw material for the production of xylitol and xylose derivatives. The study is divided in two main objectives: The first part is dedicated to optimize the conditions to extract xylan from industrial Kraft pulps. To achieve this, a factorial planning design was established using as variables the concentration of sodium hydroxide solution, extraction time and the solid (pulp) to solution ratio. The response to employed to evaluate the extraction efficiency was the recovery xylan yield. The best extraction condition was obtained with 14% (w/v) sodium hydroxide, 180 minutes and solid (pulp) to liquid ratio of 0.06, which lead to approximately 98% of xylan recovery yields. In the second part of this work, the recovery of the pure xylan from the aqueous solution was carried out by precipitation techniques using acids and / or alcohols. Due to the presence of impurities in the precipitates, it was also studied the effect of washing to purify the samples. From the characterization of the isolated samples it can be concluded that xylans precipitated by using methanol, isopropanol, hydrochloric acid and nitric acid, produced xylans samples with similar level of purity when compared to the commercial standard xylan.

Abstract Lignins have polyphenolic structures, making them candidates to replace phenols and polyphenols in polymers. Lignins are highly recalcitrant, making their refining challenging, requiring harsh temperatures and pressures. Lignins could be partially modified under milder conditions for their use in biopolymers. The main purpose of this research was to upgrade Indulin AT, a kraft pine lignin, to enhance its properties. The first part of this thesis dealt with formic acid aided pressurized hot water extraction (FAPHWE) of hemicelluloses from birch hardwood as the first step in separating the components of a lignocellulosic feedstock (LCF). More than half of the hemicelluloses were extracted as hydrolysis products, while keeping the cellulose hydrolysis products in the extract under 5% and the lignin under 3%. In the second part of this work, a method to determine the amount of phenolic hydroxyl groups (OHph) in lignins was assessed. The Δ&#949; IDUS method was found to be useful for comparing the OHph of pine kraft and birch milox lignins, albeit not as precise as carbon-13 nuclear magnetic resonance spectroscopy (13C-NMR). The third part of this thesis explored the tuning of the molar mass (MM) and OHph of Indulin AT by aqueous ethanol fractionation. The results showed that a higher water content favored the extraction of fractions with low MM and low OHph. A high ethanol content favored the extraction of fractions with medium MM and high OHph. A 50–60 wt% ethanol content allowed for near complete solubilization of Indulin AT, which could be beneficial for a single-phase chemical reaction. The fourth part of this research dealt with the depolymerization of Indulin AT in an ethanol-water solvent with formic acid as hydrogen donor. The properties of interest were MM, polydispersity (PDI), OHph, and formaldehyde uptake capability (FUC). The results of the reaction were affected predominantly by temperature. Higher temperatures led to lower MM and PDI, and higher OHph and FUC. The results of this thesis suggest that, in a biorefinery, the first step before delignification of an LCF could be FAPHWE. It was found that the properties of Indulin AT (OHph, FUC, and MM) could be enhanced by chemical depolymerization and physical fractionation. Modified lignins with higher OHph and FUC could be utilized in biopolymer applications such as phenolic resins and polyurethanes. / Tiivistelmä Ligniini on rakenteeltaan polyfenoli, mikä tekee siitä mahdollisen fenolien korvaajan polyfenolien valmistuksessa. Ligniinin rakenne on hyvin kestävä, mikä tekee sen jalostuksesta haastavaa vaatien usein korkean lämpötilan ja paineen käyttöä. Tästä huolimatta ligniiniä voidaan tietyssä määrin muokata miedommissa olosuhteissa, mikä lisää sen käyttökelpoisuutta biopolymeerien raaka-aineena. Tämän tutkimuksen tarkoitus oli jalostaa Indulin AT -kraft ligniiniä siten, että sen ominaisuudet paranevat. Aluksi väitöstyössä tarkasteltiin puun hemiselluloosan muurahaishappokatalysoidun kuumavesiuutton soveltuvuutta lignoselluloosaraaka-aineiden fraktioinnin ensimmäiseksi vaiheeksi. Yli puolet hemiselluloosasta voitiin uuttaa monosakkarideiksi samalla, kun selluloosasta uuttui alle 5 % ja ligniinistä alle 3 %. Seuraavaksi arvioitiin fenolisten hydroksyyliryhmien määritysmenetelmää. Δ&#949; IDUS metodin havaittiin olevan hyödyllinen ainakin sulfaattimenetelmän havupuuligniinien ja Milox-prosessin koivuligniininäytteiden vertailussa, vaikkakaan se ei ole yhtä tarkka kuin ydinmagneettiseen resonanssispektroskopiaan (NMR) perustuva analyysi. Tämän jälkeen tutkittiin mahdollisuuksia tuottaa etanoli-vesiliuosfraktioinnilla jakeita, joissa ligniinillä on haluttu molekyylikoko ja fenolisten hydroksyyliryhmien pitoisuus. Tulokset näyttivät, että korkea vesipitoisuus suosii pienen molekyylikoon ja matalan OHph -pitoisuuden sisältäviä jakeiden uuttumista. Korkea etanolipitoisuus suosii keskikokoisen molekyylikoon jaetta, jossa ligniinillä on korkea OHph -pitoisuus. 50–60 m-% etanolipitoisuudessa Indulin AT liukenee lähes täydellisesti, mikä voi olla edullista kemiallisten reaktioiden toteuttamiseen yhdessä faasissa. Lopuksi tutkimuksessa tarkasteltiin ligniinin osittaista depolymerisointia etanoli-vesiliottimessa muurahaishapon toimiessa vetylähteenä. Tarkasteltavat tuotteen ominaisuudet olivat molekyylikoko, polydispersiteetti, fenolisten hydroksyyliryhmien määrä ja formaldehydin sitomiskapasiteetti. Lämpötilan havaittiin olevan merkittävin depolymerisointireaktioon vaikuttava tekijä. Korkea lämpötila johtaa pienempään molekyylikokoon ja kapeampaan molekyylikokojakaumaan sekä suurempaan hydroksyyliryhmien määrään ja formaldehydin sitomiskykyyn. Tämän työn tulokset viittaavat siihen, että hemiselluloosan vesiuutto happamissa olosuhteissa voi olla biojalostamon ensimmäinen vaihe, ennen delignifiointia. Lisäksi havaittiin, että ligniinin ominaisuuksia voidaan muokata kemiallisella depolymerisoinnilla ja fysikaalisella fraktioinnilla. Korkeamman hydroksyyliryhmäpitoisuuden ja formaldehydin sitomiskyvyn muokattuja ligniinejä voidaan hyödyntää biopolymeerisovellutuksissa, kuten fenolisissa hartseissa ja polyuretaaneissa.

Détermination du potentiel prébiotiques des hémicelluloses de bois résineux / Determining the prebiotic potential of softwood hemicellulose

La biomasse lignocellulosique est composée d’hémicelluloses à hauteur de 30%. Les hémicelluloses sont elles-mêmes composées de saccharides, qui sont de véritables plateformes chimiques car ils peuvent être dérivés en de nombreux produits différents dont l’intérêt porté à leur égard est grandissant. Dans le cadre d’une bioraffinerie papetière, les hémicelluloses ont été solubilisées sous forme de monosaccharides et d’oligosaccharides via une étape d’autohydrolyse. Des traitements d’hydrolyse secondaire acide et enzymatique ont ensuite été appliqués à l’hydrolysat dans différentes conditions afin d’hydrolyser un maximum d’oligosaccharides en monosaccharides dans le premier cas, et un maximum de xylanes en xyloses dans le second cas. Ces traitements ont été optimisés pour permettre une application à un pilote industriel. / Lignocellulosic biomass is made of 30% of hemicelluloses. Hemicelluloses are themselves made of saccharides that are true platform chemicals due to their ability to be transformed into many different products. Within the context of a biorefinery, hemicelluloses were solubilized as monosaccharides and oligosaccharides after a water pre-hydrolysis treatment. Secondary acid and enzymatic hydrolysis treatments were further applied to the obtained hydrolysate to depolymerize as much oligosaccharides as possible to monosaccharides (acid hydrolysis) and to depolymerize as much as xylans as possible to xyloses (enzymatic hydrolysis). Treatments were optimized to pilot scale.