Dissertationen zum Thema „Acid hydrolysis“

Doctor of Philosophy
Department of Biological & Agricultural Engineering
Donghai Wang
Cellulosic ethanol is a renewable source of energy. Lignocellulosic biomass is a complex material composed mainly of cellulose, hemicellulose, and lignin. Biomass pretreatment is a required step to make sugar polymers liable to hydrolysis. Mineral acids are commonly used for biomass pretreatment. Using acid catalysts that can be recovered and reused could make the process economically more attractive. The overall goal of this dissertation is the development of a recyclable nanocatalyst for the hydrolysis of biomass sugars. Cobalt iron oxide nanoparticles (CoFe[superscript]2O[subscript]4) were synthesized to provide a magnetic core that could be separated from reaction using a magnetic field and modified to carry acid functional groups. X-ray diffraction (XRD) confirmed the crystal structure was that of cobalt spinel ferrite. CoFe[superscript]2O[superscript]4 were covered with silica which served as linker for the acid functions. Silica-coated nanoparticles were functionalized with three different acid functions: perfluoropropyl-sulfonic acid, carboxylic acid, and propyl-sulfonic acid. Transmission electron microscope (TEM) images were analyzed to obtain particle size distributions of the nanoparticles. Total carbon, nitrogen, and sulfur were quantified using an elemental analyzer. Fourier transform infra-red spectra confirmed the presence of sulfonic and carboxylic acid functions and ion-exchange titrations accounted for the total amount of catalytic acid sites per nanoparticle mass. These nanoparticles were evaluated for their performance to hydrolyze the β-1,4 glycosidic bond of the cellobiose molecule. Propyl-sulfonic (PS) and perfluoropropyl-sulfonic (PFS) acid functionalized nanoparticles catalyzed the hydrolysis of cellobiose significantly better than the control. PS and PFS were also evaluated for their capacity to solubilize wheat straw hemicelluloses and performed better than the control. Although PFS nanoparticles were stronger acid catalysts, the acid functions leached out of the nanoparticle during the catalytic reactions. PS nanoparticles were further evaluated for the pretreatment of corn stover in order to increase digestibility of the biomass. The pretreatment was carried out at three different catalyst load and temperature levels. At 180°C, the total glucose yield was linearly correlated to the catalyst load. A maximum glucose yield of 90% and 58% of the hemicellulose sugars were obtained at this temperature.

Renewable sources such as cellulose derived biofuels are sought after in order to replace fossil fuel sources that are currently used to meet energy demands. Cellulose is a biological polymer composed of a chain of glucose molecules. Hydrolysis of cellulosic materials then has potential to serve as a source of renewable energy in the form of biofuels. The crystalline structure of cellulose is very stable, and current methods of catalyzed hydrolysis are inefficient for industrial application. This project explores the use of phosphomolybdic acid (PMA) in water to catalyze hydrolysis of microcrystalline cellulose. Temperature of hydrolysis was varied from 40 °C – 100 °C. The amount of soluble hydrolysis product was determined through wet oxidative total organic carbon analysis using a Hach method kit. Total organic carbon content is compared between equimolar amounts of PMA and sulfuric acid, the current industry preference. The yield of total organic carbon in parts per thousand (ppt) is directly correlated to increasing temperatures. Across these temperatures, PMA is more efficient than sulfuric acid in hydrolysis of cellulosic materials. Work is ongoing for glucose-specific product detection as well as evaluating the recyclability of the catalyst.

Abstract New methods are being sought for the production of chemicals, fuels and energy from renewable biomass. Lignocellulosic biomass consists mainly of cellulose, hemicellulose and lignin. Cellulose and hemicellulose can be converted to their building blocks, i.e. sugars, via hydrolysis. This thesis is focused on glucose production from cellulose by dilute acid hydrolysis. Acid hydrolysis has the drawback of limited glucose yields, but it has the potential to become a short-term solution for biochemical production. During acid hydrolysis, the cellulose chain is split into glucose, which undergoes further decomposition reactions to hydroxymethylfurfural, levulinic acid, formic acid and by-products like insoluble humins. The present thesis aims to increase our knowledge on complicated acid-catalysed hydrolysis of cellulose. Glucose decomposition and cellulose hydrolysis were studied independently in laboratory experiments. Kinetic modelling was used as a tool to evaluate the results. The effect of the hydrogen ion on the reactions was evaluated using formic or sulphuric acid as a catalyst. This thesis provides new knowledge of cellulose hydrolysis and glucose decomposition in formic acid, a novel catalyst for high-temperature dilute acid hydrolysis. Glucose yields from cellulose hydrolysed in formic or in sulphuric acid were comparable, indicating that a weak organic acid could function as a cellulose hydrolysis catalyst. Biomass fibres in the form of wheat straw pulp were hydrolysed more selectively to glucose than a model component, microcrystalline cellulose, using formic acid. Glucose decomposition took place similarly in formic and sulphuric acid when the temperature dependence of the hydrogen ion concentration was taken into account, but a significant difference was found between the reaction rates of cellulose hydrolysis in formic acid and in sulphuric acid. The observations can be explained by changes in the cellulose hydrolysis mechanism. Thus, it is proposed in this thesis that side-reactions from cellulose to non-glucose compounds have a more significant role in the system than has earlier been understood
Tiivistelmä Uusia menetelmiä etsitään kemikaalien, polttoaineiden ja energian valmistamiseen uusiutuvasta biomassasta. Eräs biomassa, ns. lignoselluloosa, koostuu pääasiassa selluloosasta, hemiselluloosasta ja ligniinistä. Selluloosa ja hemiselluloosa voidaan muuttaa hydrolyysin avulla niiden rakennuspalikoikseen eli sokereiksi. Tämä väitöskirja keskittyy glukoosin tuottamiseen selluloosasta laimean happohydrolyysin menetelmällä. Happohydrolyysi kärsii rajoittuneesta glukoosin saannosta, mutta sillä on potentiaalia tulla lyhyen aikavälin ratkaisuksi biokemikaalien tuotannossa. Happohydrolyysin aikana selluloosaketju pilkkoutuu glukoosiksi, joka reagoi edelleen hajoamisreaktioiden kautta hydroksimetyylifurfuraaliksi, levuliini- ja muurahaishapoiksi ja kiinteäksi sivutuotteeksi. Tämän tutkimuksen tavoitteena on kasvattaa ymmärrystämme monimutkaisesta happokatalysoidusta selluloosan hydrolyysistä. Glukoosin hajoamista ja selluloosan hydrolyysiä tutkittiin erikseen laboratoriokokein. Kineettistä mallinnusta käytettiin työkaluna arvioimaan tuloksia. Vety-ionien vaikutus reaktioihin arvioitiin käyttämällä muurahais- ja rikkihappoja katalyytteinä. Tämä väitöskirja antaa uutta tietoa selluloosan hydrolyysistä ja glukoosin hajoamisreaktioista muurahaishapossa, joka on uusi katalyytti korkean lämpötilan laimean hapon hydrolyysissä. Glukoosisaannot muurahaishappo-hydrolysoidusta selluloosasta olivat vertailukelpoisia vastaaviin rikkihappo-hydrolyysi saantoihin. Tämä viittaa siihen, että heikko orgaaninen happo voisi toimia selluloosahydrolyysin katalyyttinä. Kun katalyyttinä käytettiin muurahaishappoa, vehnän oljesta tehdyt kuidut hydrolysoituivat selektiivisemmin glukoosiksi kuin mallikomponenttina toimineen mikrokiteisen selluloosan. Kun vetyionikonsentraation lämpötilariippuvuus otettiin huomioon, glukoosi hajosi samalla tavalla sekä muurahais- että rikkihappokatalyytissä, mutta merkittävä ero havaittiin selluloosahydrolyysin reaktionopeudessa. Havainnot voidaan selittää selluloosahydrolyysin mekanismissa tapahtuvilla muutoksilla. Väitöskirjassa esitetään, että sivureaktioilla selluloosasta ei-glukoosi-tuotteiksi on merkittävä vaikutus systeemiin

Master of Science
Department of Biological and Agricultural Engineering
Donghai Wang
Acid catalysts have been successfully used for pretreatment of cellulosic biomass to improve sugar recovery and its later conversion to ethanol. However, use of acid requires a considerable equipment investment as well as disposal of residues. Acid-functionalized nanoparticles were synthesized for pretreatment and hydrolysis of lignocellulosic biomass to increase conversion efficiency at mild conditions. Advantages of using acid-functionalized metal nanoparticles are not only the acidic properties to catalyze hydrolysis and being small enough to penetrate into the lignocellulosic structure, but also being easily separable from hydrolysis residues by using a strong magnetic field. Cobalt spinel ferrite magnetic nanoparticles were synthesized using a microemulsion method and then covered with a layer of silica to protect them from oxidation. The silanol groups of the silica serve as the support of the sulfonic acid groups that were later attached to the surface of the nanoparticles. TEM images and FTIR methods were used to characterize the properties of acid-functionalized nanoparticles in terms of nanoparticle size, presence of sulfonic acid functional groups, and pH as an indicator of acid sites present. Citric acid-functionalized magnetite nanoparticles were also synthesized and evaluated. Wheat straw and wood fiber samples were treated with the acid supported nanoparticles at 80°C for 24 h to hydrolyze their hemicellulose fraction to sugars. Further hydrolysis of the liquid fraction was carried out to account for the amount of total solubilized sugars. HPLC was used to determine the total amount of sugars obtained in the aqueous solution. The perfluroalkyl-sulfonic acid functional groups from the magnetic nanoparticles yielded significantly higher amounts of oligosaccharides from wood and wheat straw samples than the alkyl-sulfonic acid functional groups did. More stable fluorosulfonic acid functionalized nanoparticles can potentially work as an effective heterogeneous catalyst for pretreatment of lignocellulosic materials.

This research was carried for an EC supported project that aimed to produce ethyl levulinate as a diesel miscible biofuel from biomass by acid hydrolysis. The objective of this research was to explore thermal conversion technologies to recover further diesel miscible biofuels and/or other valuable products from the remaining solid acid hydrolysis residues (AHR). AHR consists of mainly lignin and humins and contains up to 80% of the original energy in the biomass. Fast pyrolysis and pyrolytic gasification of this low volatile content AHR was unsuccessful. However, successful air gasification of AHR gave a low heating value gas for use in engines for power or heat with the aim of producing all the utility requirements in any commercial implementation of the ethyl levulinate production process. In addition, successful fast pyrolysis of the original biomass gave organic liquid yields of up to 63.9 wt.% (dry feed basis) comparable to results achieved using a standard hardwood. The fast pyrolysis liquid can be used as a fuel or upgraded to biofuels. A novel molybdenum carbide catalyst was tested in fast pyrolysis to explore the potential for upgrading. Although there was no deoxygenation, some bio-oil properties were improved including viscosity, pH and homogeneity through decreasing sugars and increasing furanics and phenolics. AHR gasification was explored in a batch gasifier with a comparison with the original biomass. Refractory and low volatile content AHR gave relatively low gas yields (74.21 wt.%), low tar yields (5.27 wt.%) and high solid yields (20.52 wt.%). Air gasification gave gas heating values of around 5MJ/NM3, which is a typical value, but limitations of the equipment available restricted the extent of process and product analysis. In order to improve robustness of AHR powder for screw feeding into gasifiers, a new densification technique was developed based on mixing powder with bio-oil and curing the mixture at 150°C to polymerise the bio-oil.

La dégradation du papier par les encres ferrogalliques (EFG) est un défi pour la conservation du patrimoine écrit. Ces encres, composées d'un mélange de sulfate de fer (II), de tannins et de gomme Arabique, sont acides et riches en fer. Par conséquent, les mécanismes de dégradation des manuscrits par les EFG proposés dans la littérature combinent souvent hydrolyse acide et oxydation radicalaire catalysée par le fer, celle-ci impliquant la formation de radicaux HO? par réaction de Fenton. Le mécanisme prédominant reste cependant une question encore ouverte, qui est au c¿ur de ce travail. Dans un premier temps, l'étude cherchait à identifier les espèces réactives de l'oxygène (ERO) par RPE et HPLC, en particulier les radicaux HO?, détectés sur certains échantillons mais en faible quantité et sans corrélation avec la dégradation du papier. La formation d'autres ERO a par contre été mise en évidence, mais reliée à l'oxydation de fer libéré en solution plutôt qu'à la dégradation même du papier. La détermination des cinétiques de dépolymérisation à différentes températures a conduit à des énergies d'activation proches sur papier encré et sur papier acide, suggérant une prédominance de l'hydrolyse acide dans les deux cas. Ceci est confirmé par l'étude des effets de l'oxygène, du pH et du fer sur la dégradation d'une molécule modèle, la cellobiose, qui révèle que la coupure de la liaison glycosidique est liée à l'acidification du milieu lors de l'oxydation du fer. L'atteinte de tels pH acides au sein du papier suppose une présence localisée du fer, effectivement confirmée par des mesures STXM de la distribution des éléments de l'encre et de la gélatine dans une fibre de papier
Degradation of paper by iron gall inks (IGI) is a challenging issue for written heritage conservation. These inks consist of a mixture of iron(II) sulphate, tannins and gum Arabic, and are therefore acidic and iron-rich. Hence, paper degradation by IGI is often attributed to a combination of acid hydrolysis and of iron-catalyzed oxidation involving hydroxyl radicals (HO●) formed by Fenton reaction. Nevertheless, which of these two mechanisms prevails on cellulose depolymerisation remains a largely open question, which is addressed in the present work. The first step was to look at reactive oxygen species (ROS), especially HO●, by trapping reactions coupled with ESR and HPLC. Traces of HO● were identified on some samples, but their presence was not consistent with paper damage. Another type of ROS was detected in higher quantity, but correlated more to oxidation of iron leached species rather than to paper decay itself. The determination of depolymerisation kinetics at different temperatures led, on inked papers, to activation energies only slightly below those obtained on acidic papers, suggesting a dominant acid hydrolysis mechanism with a limited catalytic effect of iron. This is also supported by the detailed study of the respective effects of iron, oxygen and pH towards degradation of cellobiose taken as a model molecule. This approach gave evidence that acidification of the solution during iron oxidation is the driving force for osidic bond cleavage. To reach this pH, localized iron spots have to be present in the paper as was indeed confirmed by the STXM nano-imaging technique that allowed mapping the distribution of ink components and gelatin within a paper fiber

Due to environmental pollution caused by acid mine drainage (AMD), the Department of Water Affairs has developed a National Water Bill for managing and controlling the water environment to prevent AMD pollution. The application of sulphate reducing bacteria have been demonstrated for the treatment of AMD. However, the scale-up application of this technology ultimately depends on the cost and availability of a carbon source. This study evaluated the use of sewage sludge to provide a carbon source for sulphate reduction in synthetic drainage wastewaters. The demonstration of this process in a laboratory-scale reactor proved that sewage sludge could provide a useful model and viable carbon source for evaluation of sulphate reduction as a process for treating AMD. Since sewage sludge is a complex carbon source, hydrolysis reactions controlling the anaerobic digestion of particulate substrate from this medium were optimized by evaluating the effect of pH on hydrolysis. Controlled and uncontrolled pH studies were conducted using a three stage mixed anaerobic reactor. Analysis of the degradation behaviour of the three important organic classes (carbohydrate, proteins and lipids) revealed that each class followed an indvidual trend with respect to pH changes. In addition, the solubilization of organic particulate carbon was also shown to be a function of pH. The hydrolysis pattern of organic substrate and COD solublization was induced at pH 6.5 rather than at high pH values (7.5 and 8.5). The biodegradation activity of sewage sludge was characterized by the API-ZYM1N test system to provide rapid semiquantitative information on the activity of hydrolytic enzymes associated with the degradation of carbohydrates, lipids, proteins and nucleic acids. A wide range of enzyme activities with phosphatases, aminopeptidases, and glucosyl hydralases dominating were displayed. The pattern of substrate hydrolysis correlated to the degradation efficiency of each organic class as a function of pH. The evaluation of scale-up application for sulphate reduction utilizing sewage sludge as a carbon source demonstrated that large water volume flows could possibly be treated with this cost-effective technology. Generation of alkalinity and sulphide in this medium was shown to be successful in the removal of heavy metals by precipitation. The use of this technology coupled to reduced cost involved showed that biological sulphate reduction utilizing hydrolysates of complex organic particulate from sewage sludge ss a carbon source has a potential scale-up application for the treatment of AMD.

N-acylethanolamines (NAEs) are a diverse family of signaling lipids that occur in eukaryotes and their presence is specific to developmental stage and tissue type. In plants, NAEs with an acyl chain ranging from C12 to C18 are common with NAE 18:2 generally being the most abundant type, particularly in desiccated seeds. In Arabidopsis, NAEs negatively regulate growth and mediate stress responses via abscisic acid-dependent and -independent signaling pathway. The function of NAEs is terminated by a highly conserved fatty acid amide hydrolase (FAAH). Because of the significant role NAEs were shown to play in model plant Arabidopsis it is pertinent to elucidate this conserved metabolic pathway in crop species such as tomato. It is hypothesized that NAE pathway occurs in tomato and that there is a functional FAAH that hydrolyzes NAEs.To test this hypothesis, NAE content and composition will be determined in various tissues and developmental stages of tomato by selective lipidomic analysis. Furthermore, a functional homolog of AtFAAH has been identified in tomato and will be biochemically characterized.Thus far, full-length coding sequence of SlFAAH1 and SlFAAH2 were isolated and cloned into a heterologous expression system. The expressed protein will be characterized for its hydrolytic activity against radiolabelled NAE substrates. Temporal expression of SlFAAH1 and SlFAAH2 in different tissues will also be analyzed by quantitative PCR to correlate with the NAE levels. The molecular and biochemical characterization of FAAH in addition to determining the composition of NAEs in tomato will further validate the conserved nature of NAE metabolic pathway in plants.

Thesis (Ph. D.)--University of Maryland, College Park, 2007.
Thesis research directed by: Chemistry. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

La dégradation du papier par les encres ferrogalliques (EFG) est un défi pour la conservation du patrimoine écrit. Ces encres, composées d'un mélange de sulfate de fer (II), de tannins et de gomme Arabique, sont acides et riches en fer. Par conséquent, les mécanismes de dégradation des manuscrits par les EFG proposés dans la littérature combinent souvent hydrolyse acide et oxydation radicalaire catalysée par le fer, celle-ci impliquant la formation de radicaux HO? par réaction de Fenton. Le mécanisme prédominant reste cependant une question encore ouverte, qui est au c¿ur de ce travail. Dans un premier temps, l'étude cherchait à identifier les espèces réactives de l'oxygène (ERO) par RPE et HPLC, en particulier les radicaux HO?, détectés sur certains échantillons mais en faible quantité et sans corrélation avec la dégradation du papier. La formation d'autres ERO a par contre été mise en évidence, mais reliée à l'oxydation de fer libéré en solution plutôt qu'à la dégradation même du papier. La détermination des cinétiques de dépolymérisation à différentes températures a conduit à des énergies d'activation proches sur papier encré et sur papier acide, suggérant une prédominance de l'hydrolyse acide dans les deux cas. Ceci est confirmé par l'étude des effets de l'oxygène, du pH et du fer sur la dégradation d'une molécule modèle, la cellobiose, qui révèle que la coupure de la liaison glycosidique est liée à l'acidification du milieu lors de l'oxydation du fer. L'atteinte de tels pH acides au sein du papier suppose une présence localisée du fer, effectivement confirmée par des mesures STXM de la distribution des éléments de l'encre et de la gélatine dans une fibre de papier
Degradation of paper by iron gall inks (IGI) is a challenging issue for written heritage conservation. These inks consist of a mixture of iron(II) sulphate, tannins and gum Arabic, and are therefore acidic and iron-rich. Hence, paper degradation by IGI is often attributed to a combination of acid hydrolysis and of iron-catalyzed oxidation involving hydroxyl radicals (HO●) formed by Fenton reaction. Nevertheless, which of these two mechanisms prevails on cellulose depolymerisation remains a largely open question, which is addressed in the present work. The first step was to look at reactive oxygen species (ROS), especially HO●, by trapping reactions coupled with ESR and HPLC. Traces of HO● were identified on some samples, but their presence was not consistent with paper damage. Another type of ROS was detected in higher quantity, but correlated more to oxidation of iron leached species rather than to paper decay itself. The determination of depolymerisation kinetics at different temperatures led, on inked papers, to activation energies only slightly below those obtained on acidic papers, suggesting a dominant acid hydrolysis mechanism with a limited catalytic effect of iron. This is also supported by the detailed study of the respective effects of iron, oxygen and pH towards degradation of cellobiose taken as a model molecule. This approach gave evidence that acidification of the solution during iron oxidation is the driving force for osidic bond cleavage. To reach this pH, localized iron spots have to be present in the paper as was indeed confirmed by the STXM nano-imaging technique that allowed mapping the distribution of ink components and gelatin within a paper fiber

Given the volatile, generally high price of crude oil, as well as environmental concerns associated with its use as a fuel, development of alternative energy sources is currently of considerable interest. Lignocellulose-derived energy has the potential to supplant traditional fossil fuels in the future because of its economic and environmental advantages. Lignocellulosic biomass is abundant and renewable. Lignocellulose is primarily composed of cellulose, hemicellulose and lignin, which can be converted by acid hydrolysis to simple sugars used in fermentation to produce biofuels. In this study, hemicellulose was hydrolyzed with different concentrations of hydrochloric acid at different temperatures. The resulting components were analyzed by high performance liquid chromatography (HPLC). The hydrolysis of cellulose was similarly characterized, with two additional parameters, the degree of polymerization (DP) and the crystallinity index (CrI), which were analyzed by Ubbelohde viscometer and X-ray diffraction respectively. The experimental results indicate that the hydrolysis rate of hemicellulose and the generation rate of furfural and 5-hydroxymethylfurfural (HMF) increased with increasing hydrochloric acid concentrations and reaction temperatures. In the selected five monosaccharides, xylose, glucose, mannose, arabinose and galactose, xylose has the highest hydrolysis rate and the accumulation of furfural during xylose hydrolysis is also the highest. Moreover, the hydrolysis rate of cellulose and the generation rate of glucose also increased with increasing hydrochloric acid concentrations and reaction temperatures. DP and CrI, both decreased when the cellulose was treated in concentrated hydrochloric acid. The rate of change of DP increased with the concentrations of acid and the reaction temperatures. The change rate of CrI increases by increasing concentration of acid and the temperature when it is above 0℃, while the CrI index decrease sharply when the reaction temperature was kept below 0℃. Experimental results also show that the hydrolysis rate of cellulose is much lower than that of hemicellulose.

The research presented in this thesis was developed as part of DIBANET, an EC funded project aiming to develop an energetically self-sustainable process for the production of diesel miscible biofuels (i.e. ethyl levulinate) via acid hydrolysis of selected biomass feedstocks. Three thermal conversion technologies, pyrolysis, gasification and combustion, were evaluated in the present work with the aim of recovering the energy stored in the acid hydrolysis solid residue (AHR). Mainly consisting of lignin and humins, the AHR can contain up to 80% of the energy in the original feedstock. Pyrolysis of AHR proved unsatisfactory, so attention focussed on gasification and combustion with the aim of producing heat and/or power to supply the energy demanded by the ethyl levulinate production process. A thermal processing rig consisting on a Laminar Entrained Flow Reactor (LEFR) equipped with solid and liquid collection and online gas analysis systems was designed and built to explore pyrolysis, gasification and air-blown combustion of AHR. Maximum liquid yield for pyrolysis of AHR was 30wt% with volatile conversion of 80%. Gas yield for AHR gasification was 78wt%, with 8wt% tar yields and conversion of volatiles close to 100%. 90wt% of the AHR was transformed into gas by combustion, with volatile conversions above 90%. 5volO2%-95vol%N2 gasification resulted in a nitrogen diluted, low heating value gas (2MJ/m3). Steam and oxygen-blown gasification of AHR were additionally investigated in a batch gasifier at KTH in Sweden. Steam promoted the formation of hydrogen (25vol%) and methane (14vol%) improving the gas heating value to 10MJ/m3, below the typical for steam gasification due to equipment limitations. Arrhenius kinetic parameters were calculated using data collected with the LEFR to provide reaction rate information for process design and optimisation. Activation energy (EA) and pre-exponential factor (ko in s-1) for pyrolysis (EA=80kJ/mol, lnko=14), gasification (EA=69kJ/mol, lnko=13) and combustion (EA=42kJ/mol, lnko=8) were calculated after linearly fitting the data using the random pore model. Kinetic parameters for pyrolysis and combustion were also determined by dynamic thermogravimetric analysis (TGA), including studies of the original biomass feedstocks for comparison. Results obtained by differential and integral isoconversional methods for activation energy determination were compared. Activation energy calculated by the Vyazovkin method was 103-204kJ/mol for pyrolysis of untreated feedstocks and 185-387kJ/mol for AHRs. Combustion activation energy was 138-163kJ/mol for biomass and 119-158 for AHRs. The non-linear least squares method was used to determine reaction model and pre-exponential factor. Pyrolysis and combustion of biomass were best modelled by a combination of third order reaction and 3 dimensional diffusion models, while AHR decomposed following the third order reaction for pyrolysis and the 3 dimensional diffusion for combustion.

Dilute acid pretreatment is a process that is used to enhance ethanol yields in biofuel manufacturing by removing hemicelluloses from plant biomass. This thesis presents a new mathematical model of dilute acid pretreatment that can be used to predict hemicellulose yield profiles at the laboratory scale and inform further investigations at the industrial reactor scale. This work provides a framework for determining the optimal reaction conditions for acid pretreatment and thus has the potential to reduce the cost of commercial bioethanol production from 2nd generation lignocellulosic biomass feedstocks.

Abstract Decreasing oil reserves, the need to reduce CO2 emissions and increasing energy demand are issues that are forcing scientists to search for new opportunities in the field of energy. As a result, biofuels have been considered as one possible solution to solve part of these challenges. This research is one small part of that effort. For both human and economic reasons the use of edible raw materials for biofuel production is not sustainable. This study aims to convert forest industry waste, namely fibre sludge, into reducing sugars (glucose). This platform chemical can then be converted to value-added products, biofuels such as ethanol or butanol for example. Depolymerisation of fibre sludge (cellulose) to glucose monomers was performed firstly by pretreatment with ionic liquids [BMIM]Cl and [AMIM]Cl and secondly hydrolysed by acids (dilute maleic and sulphuric acids) and enzymes. To go further with the research the two pretreatment steps, dissolution and hydrolysis were combined into a one-step reaction by using a task-specific ionic liquid [SBMIM]Cl. With the ionic liquid [AMIM]Cl used for pretreatment in this study, we were able to recover 85% of sugars relative to the initial dry mass of the fibre sludge. Corresponding yield was about 30% without pretreatment. The task-specific ionic liquid [SBMIM]Cl was able to dissolve and hydrolyse fibre sludge in a one-step reaction. This ionic liquid was also able to dissolve wet fibre sludge with a moisture content of up to 50%. Enzymatic hydrolysis of [AMIM]Cl pretreated fibre sludge showed also very promising yields of reducing sugars
Tiivistelmä Biotaloudessa keskeisiä globaaleja haasteita ovat kasvava energiantarve, vähenevät fossiiliset öljyvarannot sekä tarve vähentää energiantuotannon ja liikenteen hiilidioksidipäästöjä, mikä on lisännyt viime vuosina aktiivisuutta biopolttoainetutkimuksen saralla. Biopolttoaineet voidaankin nähdä eräänä mahdollisuutena lisätä uusiutuvien luonnonvarojen käyttöä sekä siten edistää vähähiilistä taloutta. Uusien kestävän kehityksen periaatteita noudattavien energiantuotantomenetelmien kehittämisessä on suosittava biomassoja, jotka eivät kilpaile ruoantuotannon kanssa samoista raaka-aineista. Tässä suhteessa erityisen keskeisessä asemassa ovat mm. teollisuuden sivutuotteet, joita myös tässä työssä on tutkittu. Väitöskirjatutkimuksessa biomassaraaka-aineena on käytetty selluteollisuuden sivutuotteita, erityisesti kuitulietettä. Kuitulietteessä on korkea selluloosa- ja hemiselluloosapitoisuus, minkä vuoksi se soveltuisi ns. platform-kemikaalien valmistuksen raaka-aineeksi ja edelleen arvokkaiden kemikaalien ja polttoaineiden valmistukseen. Tutkimuksessa tavoitteena on ollut kuitulietteen sisältämien polymeerien liuottaminen ja hydrolyysi pelkistyneiksi sokereiksi, erityisesti glukoosiksi, mahdollisimman korkealla saannolla. Kuitulietteen, kuten yleensäkin selluloosan, haasteena on sen niukkaliukoisuus perinteisiin liuottimiin. Tämän vuoksi kuitulietettä esikäsiteltiin ionisissa liuottimissa ([BMIM]Cl ja [AMIM]Cl), jotta depolymerisaatio glukoosimonomeereiksi olisi mahdollinen korkealla saannolla. Esikäsittelyn jälkeen hydrolyysi tehtiin joko laimealla hapolla tai entsymaattisesti. Esikäsittelyä tutkittiin myös ns. spesifisessä ionisessa liuottimessa ([SBMIM]Cl), jossa kuitulietteen liukeneminen ja hydrolyysi tapahtuivat yhdessä vaiheessa. Esikäsittely [AMIM]Cl:ssa mahdollisti sen, että alkuperäisen kuivan kuitulietteen sokereista saatiin talteen 85 % entsymaattisen hydrolyysin jälkeen. Ilman esikäsittelyä vastaava saanto oli noin 30 %. Ionineste, [SBMIM]Cl, onnistui liuottamaan ja hydrolysoimaan kuitulietteen yhdessä vaiheessa, tosin sokerisaannot jäivät alhaisiksi. Märkä kuituliete, jonka kosteuspitoisuus oli 50 %, liukeni myös tähän ioninesteeseen

Thesis (PhD)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: The development of ―energycane‖ varieties of sugarcane for ethanol production is underway, targeting the use of both sugar juice (first generation ethanol) and bagasse (second generation ethanol). Nevertheless, identification of the preferred varieties represents the biggest challenge to the development of energycane due to large number of samples produced during breeding. In the present study, dilute acid pretreatment, enzymatic hydrolysis and fermentation processes were used to evaluate the processability of bagasse (fibrous residue generated after juice sugar extraction) from different varieties of sugarcane to select preferred varieties with the properties of improving combined ethanol yield (ethanol from juice and bagasse) per hectare. The impact of variety selection on combined ethanol yield (ethanol from juice and bagasse) per hectare was also assessed. In the first part of this study, 115 varieties of sugarcane originated from classical breeding and precision breeding (genetic engineering) were screened based on agronomic data and experimental data from biochemical processes (dilute acid pretreatment and enzymatic hydrolysis) applied to the bagasse fraction of each variety. The results showed wide variations in the chemical composition of bagasse between the varieties. Structural carbohydrates and lignin content ranged from 66.6 to 77.6% dry matter (DM) and 14.4 to 23.1% DM, respectively. The majority of precision breeding varieties showed higher arabinoxylan, lower lignin and lower ash content than most of classical breeding varieties. Combined sugar yield from the bagasse after pretreatment and enzymatic hydrolysis also varied significantly among the varieties. Up to 27.9 g/100g (dry bagasse) difference in combined sugar yield was observed. Combined sugar yield was inversely correlated with lignin as well as ash content, but it correlated positively with structural carbohydrates content. Total potential ethanol yields per hectare, calculated based on cane yield, soluble and non-soluble sugar content also differed significantly among the varieties (8,602−18,244 L/ha). Potential ethanol from bagasse contributed approximately one third of the total potential ethanol yield. Interestingly, some of the varieties had combined properties of high potential ethanol yield per hectare and improved bagasse convertibility. Thus, six varieties (3 from each breeding technology) were selected as preferred varieties for further investigation. To enhance sugar yield from bagasse, optimisation of pretreatment was conducted on the selected varieties. Industrial bagasse was included for comparison purposes. The pretreatment optimisation was based on maximising combined sugar yield from the combined pretreatment-hydrolysis process. A central composite design (CCD) was applied to investigate the effects of temperature, acid concentration and residence time on the responses and was later used to determine the maximum combined sugar yield. Pretreatment optimisation was conducted at gram scale (22.9 ml reactor) and at bench scale (1000 ml reactor). Significant differences in sugar yields (xylose, glucose, and combined sugar) between the varieties were observed. The combined sugar yields from the best performing varieties and industrial bagasse at optimal pretreatment-hydrolysis conditions differed by up to 34.1% and 33% at gram and bench scale, respectively. A high ratio of carbohydrates to lignin and low ash contents increased the release of sugar from the substrates. At mild pretreatment conditions, the differences in bioconversion efficiency between varieties were greater than at severe conditions. This observation suggests that under less severe conditions the conversion efficiency was largely determined by the properties of the biomass. Furthermore, it was demonstrated that the pretreatment conditions with temperature ranged from 184 to 200 °C and varying residence time to provide a severity factor between 3.51 and 3.96 was observed to be the area in common where 95% of maximum combined sugar yield could be obtained. Simultaneous Saccharification and Fermentation (SSF) was performed on the unwashed pressed-slurry from bagasse pretreatment at conditions for maximum combined sugar yield at bench scale. Batch and fed-batch SSF feeding strategy at different solid loadings and enzyme dosages were used aiming to reach an ethanol concentration of at least 40 g/L. The results revealed significant improvement in overall ethanol yield after SSF for the selected varieties (84.5–85.6%) compared to industrial bagasse (74.8%). The maximum ethanol concentration from the best performing varieties was 48.6−51.3 g/l and for poor performing varieties was 37.1−38.3 g/l. Ethanol concentration in the fermentation broth was inversely correlated with lignin content and the ratio of xylose to arabinose, but it showed positive correlation with glucose yield from pretreatment-enzymatic hydrolysis. The overall assessment of the varieties showed greater improvement in combined ethanol yields per hectare (71.1–90.7%) for the best performing varieties with respect to industrial sugarcane. The performance in terms of ethanol yields of selected varieties from a number harvest years was evaluated. The results showed considerable variations in ethanol yields across harvests. The results showed that the best variety in terms combined ethanol yield was not maintained across harvests. The differences in ethanol yields were greater among the varieties than across the harvests. Prolonged severe drought significantly affected the ethnol yields of all varieties represented by lower and intermediate lignin content for cane yield compared to that which had highest lignin content. However, carbohydrates content in the bagasse and sugar yield/recovery between the harvest years did not change for the most of the varieties. In summary, the present study provides evidence of the impact of cultivar selection and pretreatment optimisation in increasing conversion efficiency of bagasse. The results demonstrate that varieties with lower lignin and ash content, as well as highly substituted xylan resulted in higher sugar and ethanol yields. These results suggest that lower process requirements can be achieved without adversely affecting juice ethanol and cane yield per hectare. Nonetheless, an attempt to reduce lignin content in the bagasse, to reduce processing requirements for ethanol production, can also target the improvement of crop tolerance toward severe drought conditions.
AFRIKAANSE OPSOMMING: Die ontwikkeling van ―energie-riet‖ rasse vir etanol produksie is goed op dreef, waar beide die sap (eerste generasie etanol) en die bagasse (tweede generasie etanol) geteiken word. Die groot aantal monsters wat tydens teling geproduseer word, bied egter die grootste uitdaging vir die identifisering van nuwe rasse ten einde energie-riet te ontwikkel. In die huidige studie is verdunde suurvoorbehandeling, ensiematiese hidrolise en fermentasie-prosesse gebruik om die verwerkbaarheid van bagasse (veselagtige residu gegenereer na sap suiker ekstraksie) van verskillende suikerrietrasse te evalueer om nuwe variëteite te selekteer wat eienskappe van verbeterde gekombineerde etanolopbrengs (etanol van sap en bagasse) per hektaar toon. Die impak van variëteit-seleksie op gekombineerde etanol opbrengs (etanol van sap en bagasse) per hektaar is ook beoordeel. In die eerste deel van hierdie studie het uit ‗n siftingsproses van 115 suikerriet rasse bestaan wat deur klassieke en presisie (geneties gemodifiseerde) teling gegenereer is. Die sifting was op agronomiese data gebaseer, asook op data van verdunde suur voorafbehandeling en ensimatiese hidrolise eksperimente wat op die bagasse fraksie van elke ras uitgevoer is. Die resultate het op groot variasie in die chemiese samestelling van die bagasse van verskillende rasse gedui. Die strukturele koolhidrate het tussen 66.6 en 77.6% droë massa (DM) gewissel, terwyl die lignien inhoud ‗n variasie van 14.4 en 23.1% DM getoon het. Verder het meeste van die presisie-teling variëteite ‗n hoër arabinoxilaan, maar ‗n laer lignien en as-inhoud as meeste van die klassieke teling rasse gehad. Die gekombineerde suikeropbrengs (GSO) van die bagasse na voorafbehandeling en ensimatiese hidrolise het ook beduidend tussen rasse gewissel, waar ‗n verskil van tot 27.9 g/100g (droë bagasse) waargeneem is. Daar was ‗n omgekeerde korrelasie tussen die gekombineerde suikeropbrengs en die lignien en as-inhoud gewees, maar die opbrengs het ‗n sterk positiewe korrelasie met die strukturele koolhidrate getoon. Die totale potensiële etanol opbrengs per hektaar wat vanaf die suikerriet se oplosbare en nie-oplosbare suikerinhoud bereken is, het ook beduidend tussen rasse verskil (8,602−18,244 L/ha), waar die potensiële etanol opbrengs van die bagasse gedeelte ongeveer een derde van die totale potensiële etanol opbrengs beslaan het. Interessante bevindinge het op sommige rasse met gekombineerde eienskappe van hoë potensiële opbrengs per hektaar asook ‗n hoë omskakelingsvermoë gedui. Derhalwe is ses variëteite (drie van elke telingstegnologie) as voorkeurvariëteite vir verdere studie gekies. Om die etanol opbrengs vanaf die bagasse te verbeter was voorafbehandeling van die voorkeurvariëteite geoptimeer, en waar industriële bagasse vir vergelykingsdoeleindes ingesluit was. Vir die optimering was dit ten doel gestel om die gekombineerde suikeropbrengs van die gekombineerde voorafbehandeling-hidrolise proses te maksimeer. ‗n Sentrale saamgestelde ontwerp (SSO) is gebruik om die effek van temperatuur, suurkonsentrasie en residensietyd op die responsveranderlikes vas te stel wat uiteindelik gebruik is om die maksimum gekombineerde suikeropbrengs te bepaal. Die optimering van die voorafbehandeling is op gram-skaal in ‗n 22.9 ml reaktor, asook op bank-skaal in ‗n 1000 ml reaktor uitgevoer. Beduidende verskille in die suikeropbrengs (xilose, glukose en gekombineerde suiker) is tussen die voorkeurrasse waargeneem. Tussen die rasse wat die beste gevaar het, asook die industriële bagasse, het die gekombineerde suikeropbrengs by optimale voorafbehandeling-hidrolise toestande onderskeidelik met tot 34.1% en 33% op gram-skaal en bank-skaal gevarieer. ‗n Hoë verhouding van koolhidrate tot lignien, asook ‗n lae as-inhoud het tot ‗n toename in die vrystelling van suiker uit die substraat gelei. By matige voorafbehandelingstoestande was die verskille in omskakelingseffektiwiteit tussen rasse groter as onder hewige toestande, wat daarop gedui het dat omskakelingseffektiwiteit grotendeels deur die eienskappe van die biomassa bepaal is. Verder is daar ook gedemonstreer dat die voorbehandelingsomstandighede met temperatuur tussen 184 en 200ºC en verandering van die residensietyd om 'n hewigheidsfaktor van tussen 3.51 en 3.96 te verskaf, 'n gemeenskaplike area gelewer het waar 95% van maksimum gekombineer suiker opbrengs (GSO) verkry kon word. Gelyktydige versuikering en fermentasie (GVF) is na voorafbehandeling op ongewaste, gepersde bagasse substraat by toestande vir die maksimum gekombineerde suikeropbrengs op bank-skaal uitgevoer. Bondel en voerbondel SSF voerstrategie by verskillende vaste ladings en ensiemdoserings is gebruik om 'n etanol konsentrasie van ten minste 40 g/L te bereik. Ná GVF was die algehele etanol opbrengs vir die voorkeurvariëteite (84.5–85.6%) beduidend beter relatief tot die industriële bagasse (74.8%). Die maksimum etanol opbrengs na SSF van die rasse met die beste prestasie was 48.6-51.3 g/L en 37.1-38.3 g/L vir rasse wat swak presteer het. Die etanol konsentrasie in die fermentasiesop was omgekeerd met lignien en die verhouding van xilose tot arabinose gekorreleer, maar was duidelik positief met die glukose opbrengs vanaf voorafbehandeling-hidrolise gekorreleer. ‗n Algemene assessering het op ‗n duidelike verbetering van die voorkeurvariëteite in terme van gekombineerde etanol opbrengs per hektaar gedui (71.1–90.7%), relatief tot die industriële suikerriet. Die prestasie in terme van etanol opbrengs van geselekteerde variëteite is oor 'n reeks oesjare ge-evalueer. Die resultate het aansienlike variasies in etanol opbrengs oor oesjare getoon. Die resultate het gewys dat die beste variëteite in terme van gekombineerde etanol opbrengs nie volhou is oor oeste nie. Die verskille in etanol opbrengste tussen variëteite was groter as die verskille oor oesjare. Verlengde ernstige droogte het die etanol opbrengs van alle variëteite met laer en intermediere lignien inhoud vir rietopbrengs aansienlik beinvloed, in vergelyking met dié wat die hoogste lignien inhoud gehad het. Die koolhidraatinhoud in die bagasse en suiker opbrengs/lewering tussen die oesjare het vir die meeste variëteite egter nie gewissel nie. Ter opsomming, die huidige studie verskaf bewyse van die impak van kultivarseleksie en voorbehandelings optimisering op die verhoging van die omskakelings-doeltreffendheid van bagasse. Die resultate wys dat variëteite met laer lignien- en asinhoud, en hoogs-gesubstitueerde xilaan hoër suiker- en etanol opbrengs gelewer het. Hierdie resultate stel voor dat verminderde voorbehandelingsvereistes bereik kan word sonder om die sap etanol en rietopbrengs per hektar te benadeel. Nieteenstaande, 'n poging om die lignien inhoud van die bagasse te verminder om die verwerkingsvereistes vir etanolproduksie te verminder, kan ook die verbetering van gewas-toleransie tov ernstige droogte-toestande teiken.

Two different sludge pretreatments were investigated in an attempt to improve the management and performance of processes for the co-digestion of biosolids with fats, oils, and grease (FOG). The mechanisms of long chain fatty acids (LCFA) degradation in thermal hydrolysis pretreatment and the influence of pH on LCFA degradation in two-phase co-digestion systems were studied. LCFA thermal hydrolysis was investigated at different temperatures (90-250 °C) and reaction times (30 minutes and 8 hours). Approximately 1% of saturated fatty acids were degraded to shorter chain fatty acids at 140 and 160 °C (8-hr thermal hydrolysis). Only 1% or less of unsaturated fatty acids were degraded from 90 to 160 °C (8-hr thermal hydrolysis). Little degradation (< 1%) of both saturated and unsaturated LCFAs was observed at a 30-min reaction time. Both groups of LCFAs were stable up to 250 °C (30-min hydrolysis). The use of chemical-thermal treatments was also investigated. Only unsaturated LCFAs, C18:1 and C18:2, were degraded when thermally hydrolyzed with hydrogen peroxide coupled with activated carbon or copper sulfate. Semi-continuous, acid-phase digesters (APDs) under different pH conditions were studied in order to understand the effects of pH on FOG degradation. Increases in soluble chemical oxygen demand (SCOD) were observed in all APDs. However, the APDs with pH adjustment appeared to perform better than the controls in terms of solubilizing organic compounds. Approximately 38% and 29% of total COD (TCOD) was solubilized, and maximum volatile fatty acid (VFA) concentrations of 10,700 and 7,500 mg/L TCOD were achieved at pH 6 and 7, respectively; It is useful to note that the feed sludge had a VFA concentration of 2,700 mg/L COD. Higher pH (6.0-7.0) showed less accumulation of LCFA materials and more soluble LCFAs in the APDs. This indicates that the lower pH in the APDs was most likely the cause of precipitation and accumulation of LCFAs due to saturation of unsaturated LCFAs.
Master of Science

The submitted master thesis deals with assessment of the possibility of using of cheese whey for biotechnological production. Study content composition of lyophilized whey, optimization of acid hydrolysis and preparation of cultivating mediums with different content and treatment of cheese whey. Between the aims of this thesis belong also screening of microbial producers, interesting for biotechnology and looks at their growth and production of selected metabolites of cultivation mediums containing cheese whey. All substrates and produced metabolites where examined with UHPLC-PDA-RI and GC-FID: Amount of produced microbial lipids was determined by gravimetric analysis. Examined microorganisms belonged to yeast genus Saccharomyces, Metschnikowia and bacterial genus Lactobacillus and its focused on production of ethanol, microbial lipids and lactic acid. The highest yields with using yeasts were obtained using production medium containing hydrolysed lactose in cheese whey. The highest production, in case of bacteria, was obtained using non-hydrolysed, untreated cheese whey production medium.

With growing environmental concerns, efforts are made to replace petroleum based products with renewable alternatives. This is particularly evident in the packaging industry, where replacing synthetic polymers with renewable materials is of considerable interest. Materials for food packaging need to give protection, acting as a barrier against substances that can adversely affect the food quality such as water and oxygen. In this work, barrier dispersion coatings based on starch were used to produce coated papers which act as barrier against water and oxygen. However, since starch is both a hydrophilic and hygroscopic material, this barrier material becomes problematic to use at high relative humidity. In order to reduce this problem and improve the barrier properties enabling starch based barrier materials to be used in food packaging applications, two approaches were studied. Citric acid was utilized as a cross-linker of the starch and it was found to reduce the moisture sorption, the molecular movement and swelling at high relative humidity. It was seen that cross-linking and hydrolysis due to the low pH both affected the barrier properties significantly, but in opposing directions. By controlling these two reactions it was seen that this could lead to reduced gas permeability. It was also seen that cross-linking of starch by citric acid occurs at low temperatures, 70 °C at pH as high as 6.5. Starch nano-composites were produced by incorporating montmorillonite, to the barrier dispersion to improve the barrier properties. It was seen that the suspension viscosity was reduced by poly(ethylene glycol) and citric acid adsorption on the montmorillonite particles. Also, a tendency for improved barrier properties with reduced aggregate volume fraction and reduced swelling was observed. It was also seen that up scaling this formulation to pilot scale was possible and that promising results were achieved.
Baksidestext With growing environmental concerns, efforts are made to replace petroleum based materials with renewable alternatives such as starch. In this work, dispersions based on starch were used to produce coated papers which act as barrier against substances that can adversely affect the food quality such as water and oxygen. However, since starch is both a hydrophilic and hygroscopic material, this barrier material becomes problematic to use at high relative humidity. Citric acid was utilized as cross-linker for starch and it was found to reduce the moisture sorption, diffusion and swelling at high relative humidity. Both cross-linking and hydrolysis due to the low pH affected the barrier properties significantly, but in opposing directions. By controlling these two reactions it was possible to achieve reduced gas permeability. Starch nano-composites were produced by incorporating montmorillonite clay, to the barrier dispersion. It was seen that the suspension viscosity was reduced by poly(ethylene glycol) and citric acid adsorption on the clay. Also, a tendency for improved barrier properties with reduced aggregate volume fraction and reduced swelling was observed. It was also seen that up scaling this formulation to pilot scale was possible and promising results were achieved.
Renewable Functional Barriers

Regenerated cellulosic fibres are known to undergo catalytic decomposition during hydrolytic treatment in Bronsted and Lewis acids. This process is taking place short after the depolymerisation or scission-reordering of the cellulosic macromolecular chains. Depolymerisation is believed to be connected with the less accessible regions of the fibrous structure and leads to a rapid reduction of the fibres' mechanical performance. Enzyme hydrolytic action is cunrrently used as a way of generating wetstate fibrillation to the surface regions of lyocell regenerated cellulosic fabrics.

Lignocellulosic biomass has potential to chip in the chemical and biofuels supplies in future societies,even though lignocellulose is a recalcitrant structure that has to be treated in several steps. After theirproper life cycle, wood-derived materials such as particleboards have few outcomes today apart fromenergy recovery for heat production. Then, they may be used as lignocellulosic biomass sources in theproduction of molecules of interest. Fermentation from wood-derived monosaccharides imposespreliminary sugar retrieval, for instance through pre-treatment and enzymatic hydrolysis. This studyfocuses on the potential of particleboards waste for chemical and biofuel production by comparingsaccharification through simulated steam explosion pre-treatment and enzymatic hydrolysis betweennative and particleboard-derived wood, with an insight in subsequent fermentation by Saccharomycescerevisiae. Urea-Formaldehyde bound particleboard was investigated, as well as some aspects ofMelamine-Urea-Formaldehyde bound particleboard. Pre-treatment resulted in apparition of lignocellulosic degraded compounds in a much larger extent innative wood than in particleboard, which seemed to be only superficially impacted. Formation ofdegraded compounds from sugars – furfural and 5-hydroxymethylfurfural – was enhanced when pretreatmentwas prolonged. Removal of a substantial fraction of the adhesive contained in theparticleboards was observed, leading to comparable concentrations in free urea, its degradedproducts, and formaldehyde between native wood and particleboards during enzymatic hydrolysis.Enzymatic hydrolysis with cellulases and hemicellulases highlighted a critical role of pre-treatment toenhance final yields, both in native wood and in Urea-Formaldehyde particleboard. Adding 20 minutessteam-explosion type pre-treatment at 160 °C resulted in glucose yields increase from 18.5 % to 32.8% for native wood and from 15.6 % to 37.4 % for particleboard. Prolonging pre-treatment residencetime to 35 minutes resulted in much better glucose extraction for native wood but only slight progressfor the particleboard, as glucose yields reached 64.5 % and 41.1 % respectively. Maximalconcentrations achieved were 277 and 184 mg/gbiomass respectively. Fermentation brought to light high inhibition from both native wood and particleboard sources ofmedia, which were attributed to components or degraded products of lignocellulose that were notanalysed in this project. Ethanol was formed during fermentation, with reduced productivity butincreased yields as compared with the control sample. Inhibition was so strong that no difference couldbe given between native and particleboard wood. In this situation, no inhibition potential of resin orits degradation products could be proved.
Lignocellulosic biomassa har potential att bidra till kemikalier och biobränsletillförsel i framtidasamhällen, trots att lignocellulosa är en rekalcitrant struktur som måste behandlas i flera steg. Idagträmaterial som spånskivor bara används för energiåtervinning och värmeproduktion efter deraslivscykel. De kan därför användas som råvara för framställning av värdefulla molekyler.Fermenteringsprocesser behöver frisättningen av trä monosackarider genom förbehandlingsprocesseroch enzymatisk hydrolys. Studien fokuserar på potentialen för avfall från spånskivor för kemisk ochbiobränsleproduktion. Vi har jämfört sackarifiering mellan nativt trä och spånskivor genom simuleradångaxplosion och enzymatisk hydrolys, med en inblick i efterföljande fermentering av Saccharomycescerevisiae. Spånskivor bunden av urea-formaldehyd undersöktes, liksom vissa aspekter av spånskivorbundna med melamin-urea-formaldehyd. Förbehandlingen producerade högre koncentration av lignocellulosa nedbrytningsprodukter frånnativt trä jämfört med spånskivor. Bildningen av nedbrytningsprodukter från sockerarter - furfural och5-hydroxymethylfurfural - ökade med längre förbehandlingar. En väsentlig fraktion av limmet borttogsfrån spånskivorna, vilket ledde till jämförbara koncentrationer i fri urea, dess nedbrytningsprodukteroch formaldehyd mellan naturligt trä och spånskivor under enzymatisk hydrolys. Enzymatisk hydrolys med cellulaser och hemicellulaser avslöjade den kritiska rollen av förbehandlingför att förbättra utbytet, både i naturligt trä och i urea-formaldehyd spånskiva. Längre (20 minuter)ångexplosion vid 160° C resulterade i högre glukosutbytet (från 18,5% till 32,8% för naturligt trä ochfrån 15,6% till 37,4% för spånskivor). Förlängning av uppehållstiden före behandlingen till 35 minuterresulterade i mycket bättre glukosekstraktion för nativt trä (64,5%) men endast liten framsteg förspånskivan (41,1%). Detta resulterade i maximalt utbyte av 277 mg Glc/g biomassa och 184 mg Glc/ gbiomassa för nativt trä och spånskivor, respektive. Fermentering visade hög hämning från lignocellulosa nedbrytningsprodukter som inte analyserades iprojektet för både nativt trä och spånskällor för media. Etanol bildades under fermentering medreducerad produktivitet men ökade utbyten jämfört med kontrollprovet. Hämningen var så stark attingen skillnad kunde ges mellan naturligt trä och spånskivor. I denna situation kunde ingenhämningspotential för lim eller dess nedbrytningsprodukter bevisas.

This project aimed to optimise a process for the production of hydrolysed collagen from livestock bones. Current commercial hydrolysed collagen production processes from bones are energy intensive and generate large amounts of chemical waste, which can be harmful to the environment or costly to treat. The process developed in this work achieved lower levels of chemical waste, generated a by-product with commercial potential (calcium diphosphate for animal feed) and showed high yields of hydrolysed collagen that met commercial product specifications.

Doctor of Philosophy
Department of Chemical Engineering
Keith L. Hohn
Superparamagnetic iron oxide nanoparticle functionalization is an area of intensely active research, with applications across disciplines such as biomedical science and heterogeneous catalysis. This work demonstrates the functionalization of iron oxide nanoparticles with a quasi-monolayer of 11-sulfoundecanoic acid, 10-phosphono-1-decanesulfonic acid, and 11-aminoundecanoic acid. The carboxylic and phosphonic moieties form bonds to the iron oxide particle core, while the sulfonic acid groups face outward where they are available for catalysis. The particles were characterized by thermogravimetric analysis (TGA), transmission electron microscopy (TEM), potentiometric titration, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray photoelectron spectrometry (XPS), and dynamic light scattering (DLS). The sulfonic acid functionalized particles were used to catalyze the hydrolysis of sucrose at 80˚C and starch at 130˚C, showing a higher activity per acid site than the traditional solid acid catalyst Amberlyst-15, and comparing well against results reported in the literature for sulfonic acid functionalized mesoporous silicas. In sucrose catalysis reactions, the phosphonic-sulfonic nanoparticles (PSNPs) were seen to be incompletely recovered by an external magnetic field, while the carboxylic-sulfonic nanoparticles (CSNPs) showed a trend of increasing activity over the first four recycle runs. Between the two sulfonic ligands, the phosphonates produced a more tightly packed monolayer, which corresponded to a higher sulfonic acid loading, lower agglomeration, lower recoverability through application of an external magnetic field, and higher activity per acid site for the hydrolysis of starch. Functionalizations with 11-aminoundecanoic acid resulted in some amine groups binding to the surfaces of iron oxide nanoparticles. This amine binding is commonly ignored in iron oxide nanoparticle syntheses and functionalizations for biomedical and catalytic applications, affecting understandings of surface charge and other material properties.

Cellulose nanocrystals (CNCs) are frequently prepared by sulfuric acid hydrolysis of a purified cellulose starting material. CNC yields, however, are generally low, often below 20%. This study employs response surface methodology to optimize the hydrolysis conditions for maximum CNC yield. Two experimental designs were tested and compared: the central composite design (CCD) and the Box–Behnken design (BBD). The three factors for the experimental design were acid concentration, hydrolysis temperature, and hydrolysis time. The responses quantified were CNC yield, sulfate group density, ζ-potential, z-average diameter, and Peak 1 value. The CCD proved suboptimal for this purpose because of the extreme reaction conditions at some of its corners, specifically (1,1,1) and (–1,–1, –1). Both models predicted maximum CNC yields in excess of 65% at similar sulfuric acid concentrations (~59 wt %) and hydrolysis temperatures (~65 °C). With the BBD, the hydrolysis temperature for maximum yield lay slightly outside the design space. All three factors were statistically significant for CNC yield with the CCD, whereas with the BBD, the hydrolysis time in the range 60–150 min was statistically insignificant. With both designs, the sulfate group density was a linear function of the acid concentration and hydrolysis temperature and maximal at the highest acid concentration and hydrolysis temperature of the design space. Both designs showed the hydrolysis time to be statistically insignificant for the ζ-potential of CNCs and yielded potentially data-overfitting regression models. With the BBD, the acid concentration significantly affected both the z-average diameter and Peak 1 value of CNCs. However, whereas the z-average diameter was more strongly affected by the hydrolysis temperature than the hydrolysis time, the Peak 1 value was more strongly affected by the hydrolysis time. The CCD did not yield a valid regression model for the Peak 1 data and a potentially data-overfitting model for the z-average diameter data. A future optimization study should use the BBD but slightly higher hydrolysis temperatures and shorter hydrolysis times than used with the BBD in this study (45–65 °C and 60–150 min, respectively).
Master of Science

Endoproteinase Glu-C (EPGIu-C, EC 3.4.21.19), an enzyme isolated from the bacteria Staphylococcus aureus, has been found to cleave specifically at the carboxyl-terminal side of glutamyl and aspartyl peptide bonds. EPGIu-C has been reported to be stable and active in the presence of common denaturants such as guanidinium chloride, urea and sodium dodecyl sulfate (Drapeau, G.R. (1977) Methods in Enzymology, 47:189-191). In order assess the denaturant stability and activity of EPGIu-C, the effect of three common protein denaturants, guanidinium chloride, urea, and sodium dodecyl sulfate (SDS) on the proteolytic activity of EPGIu-C was studied.The kinetics of the hydrolyis reaction catalyzed by EPGIu-C was determined using the chromophoric substrate N-tBOC-L-glutamic acid-a-phenyl ester (BGPE).To compare theurea is significantly greater at the higher concentrations of urea. These results suggest that a complete cleavage of proteins substrate by EPGlu-C might occur more rapidly in 8.0 M urea than in 6.0 M GuCl, since EPGlu-C will be operating at a significantly higher catalytic efficiency in the urea solution.
Department of Chemistry

De forma sustentável o setor sucroalcooleiro nacional apresenta grande potencial para o desenvolvimento tecnológico de fontes alternativas de energia. A partir das novas concepções de emprego de energias alternativas, o resíduo industrial do processamento da cana-de-açúcar passa a ser uma matéria-prima com grande potencial e valor. De forma ilustrativa da potencialidade deste material, os dados de produção de bagaço de cana e suas aplicações estão destacados na parte introdutória, compreendendo a possível integração das usinas com as biorrefinarias. A utilização do bagaço de cana-de-açúcar como combustível para co-geração de energia atende à necessidade de mercado, sendo que a rentabilidade de energia elétrica é altamente viável. Porém, considerando-se que esta matéria-prima apresenta características peculiares para a biorrefinaria, objetivou-se o fracionamento da biomassa. As metodologias são investigadas por abranger a conversão da biomassa(bagaço e palha de cana-de- açúcar) para uma variedade de produtos de maior valor agregado (energia, biomateriais e produtos químicos). As etapas de fracionamento, ou seja, de pré-tratamentos foram: préhidrólise, deslignificação e branqueamento. A pré-hidrólise apresentou-se seletiva para a remoção das hemiceluloses, já para a etapa de deslignificação, mostrou-se mais seletiva para a remoção de ligninas, embora houvesse grande remoção também das hemiceluloses. Para a etapa de branqueamento, a remoção residual de lignina foi atingida, porém também foi removido celulose. A avaliação das etapas de pré-tratamentos foi realizada pela determinação dos rendimentos de processos, da seletividade reacional, bem como pela quantificação dos produtos e resíduos obtidos. Os materiais obtidos nas etapas de pré-tratamentos foram caracterizados e posteriormente submetidos ao processo de hidrólise ácida. São apresentados os resultados de rendimento de obtenção de glicose a partir de celulose, em base celulose inicial e em base celulose reagida. Na primeira parte, discutiram-se os rendimentos gravimétricos das reações de hidrólise ácida que para o material in natura resultaram em maiores rendimentos de hidrólise. Os maiores rendimentos obtidos no estudo de hidrólise de celulose foram obtidos para substratos derivados do bagaço integral na concentração de ácido de 0,14%. Os resultados da quarta, relativa a obtenção de coprodutos, HMF e furfural revelou a geração de baixas concentrações desses inibidores da fermentação etanólica. De forma conclusiva, a associação dos resultados dos processos de pré-tratamentos com os resultados obtidos nas reações de hidrólise poderá ser empregada para compreender as vantagens e desvantagens de cada etapa, mostrando caminhos para um melhor aproveitamento da biomassa vegetal, em especial o bagaço de cana de açúcar. Considerando-se a produção de etanol de segunda geração, determinaram-se também as quantidades de inibidores de fermentação etanólica.
Sustainably the Brazilian sugarcane sector presents great potential for technological development of alternative sources of energy. From the new concepts of employment of alternative energy sources, industrial waste from processing of sugarcane becomes a raw material with great potential and value. Illustratively of the potential of this material, the production data of sugarcane bagasse and their applications are highlighted in the introductory section, including the possible integration of the sugarcane mills to biorefineries. The utilization of crushed sugarcane as fuel for co-generation of energy meets the market need, and the profitability of electricity is highly feasible. However, considering that this raw material has peculiar characteristics to the biorefinery, this work aimed at the fractionation of biomass. The methodologies are investigated for covering the conversion of biomass (bagasse and straw from sugarcane). For a variety of products with higher added value (energy, biomaterials and chemicals). The steps of fractionation, or pre-treatments were pre-hydrolysis, delignification and bleaching. The pre-hydrolysis showed up selective removal of hemicelluloses. On the other hand, the delignification step was more selective for the removal of lignin, although there was also large removal of hemicelluloses. For the bleaching stage, the removal of residual lignin was achieved, but some cellulose was also removed from the pulps. The evaluation of the pre-treatments steps were performed by determined the yields of the processes, the selectivity and the quantification of the reaction products and wastes obtained. The materials obtained by the pre-treatment steps were characterized and further submitted to acid hydrolysis. It were presented the results of glucose yields of production base on initial cellulose and reacted cellulose. The first part of the work discusses the gravimetric yield of the acid hydrolysis reaction that produced the highest yield for the in natura material. The highest yields obtained in this study of cellulose hydrolysis were obtained for substrates derivates from integral bagasse at acid concentration of 0.14%. The results of the fourth step, concerning the production of HMF and furfural, revealed the production of low concentrations of these inhibitors of ethanol fermentation. Conclusively, the association of the results obtaining in the pre-treatment processes with that ones obtained by the hydrolysis processes can be used to understand the advantages and disadvantages of the individual steps, showing trends towards a better utilization of vegetal biomass, especially crushed sugarcane. In terms of second generation ethanol, it was presented the results of the quantification of potential inhibitors of ethanolic fermentation.

Dentre os materiais de fontes naturais e renováveis, a celulose se destaca pela sua abundância, podendo ser encontrada em diversos organismos vivos, como plantas, amebas, bactérias, fungos e alguns animais marinhos. Suas dimensões podem ser reduzidas por quebra das cadeias amorfas, com possibilidade de atingir escalas nanométricas, obtendo-se assim as chamadas nanopartículas de celulose ou nanocelulose. Devido à alta cristalinidade, a nanocelulose possui altos valores de módulo elástico, proporcionando alta capacidade de reforço em matrizes poliméricas, combinados com baixo peso, área superficial elevada e biodegradabilidade. A borracha natural é uma matéria-prima de fonte natural, sendo extraída das seringueiras na forma de látex - dispersão coloidal de partículas de borracha e substâncias não-borrachas em um meio aquoso, com aspecto leitoso. No presente trabalho foram estudados compósitos de borracha natural e nanocelulose. Inicialmente, foi realizada uma análise do látex de nacionalidade brasileira, centrifugado, contendo 60% em massa de sólidos. Os resultados de caracterização do látex centrifugado comercial, a qual consistiu na análise de concentração de sólidos totais e na medida do pH, estavam de acordo com os dados apresentados pelo fornecedor. Além disso, a análise de distribuição de tamanho de partícula indicou que o material apresenta uma população, com tamanho médio de 1,0 ?m. A borracha coagulada com ácido acético apresentou, após mastigação em cilindro aberto, viscosidade Mooney e extrato acetônico igual a, respectivamente, 52,8 e 2,57%. As nanoceluloses foram obtidas por hidrólise com ácido ortofosfórico (NC P) e sulfúrico (NC S), sendo classificadas como nanocristal de celulose (NC). NC P apresentaram comprimento médio, razão de aspecto e cristalinidade igual a, respectivamente, 270 ± 89 nm, 50 ± 24 e 78%; e as NC S apresentaram 209 ± 51 nm, 29 ± 10 e 75%.. Os compósitos de borracha natural com nanocristais de celulose apresentaram, nos ensaios de tração, aumentos nos valores de todas as propriedades analisadas, quando comparados à borracha natural pura. Ao adicionar-se 10 phr de nanocelulose preparada com ácido fosfórico na borracha natural, os valores de resistência à tração na ruptura, alongamento na ruptura e módulo a 300% aumentaram, respectivamente, em 90%, 16% e 52%. Já com a adição de 10 phr de NC S, essas propriedades aumentaram, respectivamente, em 68%, 5% e 109%. O mesmo foi observado para a dureza Shore A. Com a adição de 10 phr de nanocelulose obtida por ácido fosfórico à composição da borracha natural, a dureza Shore A aumentou em cerca de 22%; já com a adição de 10 phr de NCs S, a dureza da borracha natural aumentou em 36%.
Among the natural and renewable sources\' materials, cellulose stands out for its abundance, it can be found in many living organisms, such as plants, amoebas, bacteria, fungi and some marine animals. Its dimensions can be reduced by breaking the amorphous chains, with the possibility of reaching nanometric scales, obtaining the nanocellulose or cellulose nanoparticles. Due to the high crystallinity, the nanocellulose has high elastic modulus value, providing high reinforcement capacity combined with low weight, high surface area and biodegradability. Natural rubber is a raw material from a natural source, extracted from the latex - colloidal dispersion of rubber particles and non-rubbers in a milkylooking aqueous solution. At this work, composites of natural rubber and nanocellulose were studied. Initially, a Brazilian centrifuged latex with 60% of its weight in solids was characterized, by analyzing if the total solids concentration and the pH measurement is in agreement with the data presented by the supplier. In addition, particle size distribution analysis demonstrated that the material had an average size of 1.0 ?m. Then, the mastication in the open cylinder and the Mooney viscosity and acetone extract was measured and them were equal to, respectively, 52.8 and 2.57%. The nanocelluloses obtained by hydrolysis with phosphoric and sulfuric acids are classified as cellulose nanocrystal. NC P present average length, aspect ratio and crystallinity equal to 270 ± 89 nm, 50 ± 24 and 78%; and the NC S had 209 ± 51 nm, 29 ± 10 and 75%. In the tensile test, it was observed that there was an increase in all the mechanical properties analyzed for natural rubber when adding the nanocellulose in its composition. By adding 10 phr of prepared nanocellulose with phosphoric acid in the natural rubber the values of tensile strength at rupture, strain at rupture and modulus at 300% increased, respectively, by 90%, 16% and 52%. When added 10 phr of NC S, these properties increased, respectively, by 68%, 5% and 109%. The same was observed for Shore A hardness. When adding 10 phr of nanocellulose obtained by phosphoric acid in its composition, the Shore A hardness increased by about 22%; When adding 10 phr of NCs S, the hardness increased by 36%.

In this work, the stability of acid-modified activated carbons is assessed in the typical biomass conversion reaction environment of 200 °C, 17 bar water. Activated carbons were modified with a variety of common liquid and gas phase methods and characterized. Acid-modified carbon catalysts were exposed to hot liquid water for 24 h and further characterized to determine the effect of this exposure on their surface chemistry. It was found that the liquid phase acidifying agents of H₂SO₄ and HNO₃ are most effective at adding acidic functionalities to the carbon. Exposure to hot liquid water was found to significantly decrease the carboxylic and sulphonic acid site concentrations on the carbons and slightly increased lactonic group concentrations. Kinetic studies indicate that these surface chemical changes occur within the first 4 h exposure to this environment, and that increased exposure temperature results in more efficient acid site removal. XPS measurements show that H₂SO₄ modification imparts partially stable sulfonic acid groups on the carbon surface while HNO₃ modification imparts nitro groups which are unstable at exposure temperatures above 150 °C. The second part of this work focuses on the application of these acid-modified activated carbon catalysts as well as a variety of mixed metal oxide catalysts to the hydrolysis of the model biomass compound cellobiose. Catalyst screening reactions indicate that amorphous silica alumina catalysts are stable and selective but only slightly active whereas silica niobia catalysts are highly active but less selective and stable. Modified activated carbon catalysts were found to have moderate activity and selectivity. An investigation into the mechanism of silica niobia deactivation was performed and apparent activation energies were found for cellobiose hydrolysis over a variety of mixed metal oxide catalysts. Finally, a novel activated carbon synthesis mechanism was developed based on knowledge of surface site stability. This carbon catalyst was found to be highly active, selective, and stable for cellobiose hydrolysis but further characterization is required to fully understand its effectiveness as a catalyst.

Master of Science
Department of Chemical Engineering
Keith Hohn
Acid catalysts have been shown to be very successful in the pretreatment of cellulosic biomass to improve glucose yield and improve overall yield of ethanol. This report presents the results of a techno-economic study that looks into the use of nanoscale magnetic solid acid catalysts for glucose production. Magnetic solid acid catalysts are an improvement over using diluted acid due to eliminating acid-waste generation and corrosion hazards. Their magnetic nature also allows them to be easily separated from reaction products by an external magnetic force. After the technology is analyzed, a series of unit operations is proposed to go from the laboratory scale to the industrial plant scale. The next step was to develop material and energy balances using HYSYS process simulation software. Capital and operating costs are estimated and all the information is combined into a discounted cash flow economic model. The economic portion of the report uses a probabilistic cost assessment. It is used to quantify the range of risks in the project from swings in feedstock costs, differences in yield from catalysts, and any other significant variables. Both capital costs (initial equipment & construction investment) and operating costs (feedstock supply, chemicals, and personnell) are included with ranges of error based on databases and expert opinion. This method of evaluating investment efficiency can be helpful for predicting the cost benefits of proposed future research. The yield and percent catalyst magnetically recovered is assumed based on laboratory research to simplify the model. A 2000 metric tons of biomass per day facility was analyzed. Using the magnetic solid acid catalyst technology, the capital costs are estimated to be $160 million and this technology saves around 10% of capital costs compared to ethanol plants that uses conventional acid hydrolysis. The yield of the magnetic solid acid catalysts should be around 75% to compete with existing ethanol technologies. The metric used for this report is the discount profitability index (DPI) which is the ratio of future cash flows divided by investment. A DPI “hurdle rate” of 1.3 is used, which is similar to industry economic metrics of projects that include new process plants. The calculated DPI for the project is 1.38 DPI which is higher than using conventional cellulose treatment technologies. The recommendation is continue to study this technology’s large scale applicability before attempting any plant pilot studies.

The objective of this research was to investigate lead speciation in the soil/sediment-water environment and to better understand how the species affect lead mobility under different environmental conditions. The research involved both field soil and sediment samples as well as standard lead solutions. Field samples were fully characterized and extracted by aqueous and organic solvents. The results were compared and evaluated with the metal speciation model, MINTEQA2. Hydrolytic polymerization and organic complexation studies were conducted with standard lead solutions under controlled experimental conditions. Results of the field samples showed that pH, dissolved cations, ionic strength, dissolved organic matter, and nature of the soil/sediment matrix play major roles in the distribution and mobility of lead (Pb) from contaminated sites. In the aqueous equilibration experiment, the magnitude of Pb2+ solubilization was in the order of pH4>pH7>pH9. The results were in good agreement with MINTEQA2 predictions. An important finding of the research is the detection of Pb polymerization species under controlled experimental conditions. At pH 5.22, Pb polymeric species were formed at rate of 0.03 per day. The role of Pb complexation with organic matter was evaluated in both field and standard samples. Different methodologies showed three types of organically bound Pb. A very small fraction of Pb, in the ppb range, was extractable from the contaminated soil by polar organic solvents. Sequential extractions show that 16.6±1.4 % of the Pb is organically complexed. Complexation of Pb with fulvic acid provided new information on the extent of Pb association with soluble organic matter. The overall results of this research have provided new and useful information regarding Pb speciation in environmental samples. The results, in several instances, have provided verification of MINTEQA2 model's prediction. They also revealed areas of disagreement between the models prediction and the experimental results. A positive note regarding the experimental work done in the research is the verification of the mass balance in all the repeated experiments.