Prediction of vapor-moisture equilibriums for a wood-moisture system using a modified UNIQUAC model

A modified UNIQUAC model has been extended to describe and predict the equilibrium relative humidity and moisture content for wood. The method is validated over a range of moisture content from oven-dried state to fiber saturation point, and over a temperature range of 20-70 degrees C. Adjustable parameters and binary interaction parameters of the UNIQUAC model were estimated from experimental data for Caribbean pine and Hoop pine as well as data available in the literature. The two group-interaction parameters for the wood-moisture system were consistent with using function group contributions for H2O, -OH and -CHO. The result reconfirms that the main contributors to water adsorption in cell walls are the hydroxyl groups of the carbohydrates in cellulose and hemicelluloses. This provides some physical insight into the intermolecular force and energy between bound water and the wood material. (c) 2006 Elsevier Ltd. All rights reserved.

Thermochemical characterisation of straws and high yielding perennial grasses

The research is concerned with thermochemical characterisation of straws and high yielding perennial grasses. Crops selected for this study include wheat straw (Triticum aestivum), rape straw (Brassica napus), reed canary grass (Phalaris arundinacea) and switch grass (Panicum virgatum). Thermogravimetric analysis (TGA) was used to examine the distribution of char and volatiles during pyrolysis up to 900 °C. Utilising multi-heating rate thermogravimetric data, the Friedman iso-conversional kinetic method was used to determine pyrolysis kinetic parameters. Light and medium volatile decomposition products were investigated using pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS) up to 520 °C. The 22 highest yielding identifiable cellulose, hemicellulose and lignin biomass markers were semi-quantified taking into consideration peak areas from GC chromatograms. Notable differences can be seen in butanedioic acid, dimethyl ester (hemicelluloses decomposition products), 2-methoxy-4-vinylphenol (lignin marker) and levoglucosan (intermediate pyrolytic decomposition product of cellulose) content when comparing perennial grasses with straw. From results presented in this study, perennial grasses such as switch grass, have the most attractive properties for fast pyrolysis processing. This is because of the observed high volatile yield content of 82.23%, heating value of 19.64 MJ/kg and the relatively low inorganic content.

Thermochemical characterisation of Parinari polyandra Benth fruit shell

The aim of this work is to investigate the thermochemical characteristics of Parinari polyandra Benth fruit shell. An agricultural waste residue is investigated using standard methods including thermogravimetric analysis (TGA), proximate and ultimate analysis, structural composition and bomb calorimeter. The proximate and ultimate analyses were carried out to determine the ash and fixed carbon contents, volatile matter, and elemental compositions. The structural composition analysis determined the hemicellulose, cellulose, and lignin content of the biomass. The measured calorific value obtained was 20.5. MJ/kg. The TGA and DTG profiles indicate the waste fruit shells are viable for pyrolysis reaction. The inorganic contents are relatively low with potassium found to be the most abundant element. The hemicelluloses and cellulose contents are indicative of relatively higher rate of pyrolysis and comparable with established biomass utilised for bio-oil production.

Structural and chemical modifications of typical South African biomasses during torrefaction

Torrefaction experiments were carried out for three typical South African biomass samples (softwood chips, hardwood chips and sweet sorghum bagasse) to a weight loss of 30wt.%. During torrefaction, moisture, non-structural carbohydrates and hemicelluloses were reduced, resulting in a structurally modified torrefaction product. There was a reduction in the average crystalline diameter (La) (XRD), an increase in the aromatic fraction and a reduction in aliphatics (substituted and unsubstituted) (CPMAS 13C NMR). The decrease in the aliphatic components of the lignocellulosic material under the torrefaction conditions also resulted in a slight ordering of the carbon lattice. The degradation of hemicelluloses and non-structural carbohydrates increased the inclusive surface area of sweet sorghum bagasse, while it did not change significantly for the woody biomasses.

Enzymatic upgrading of eucalypt paper-grade kraft pulp within dissolving pulp production

Dissolving-grade pulps are commonly used for the production of cellulose derivatives and regenerated cellulose. High cellulose content, low content of non-cellulosic material, high brightness, a uniform molecular weight distribution and high cellulose reactivity are the key features that determine the quality of a dissolving pulp. The first part of this work was an optimization study regarding the application of selected enzymes in different stages of a new purification process recently developed in Novozymes for purifying an eucalypt Kraft pulp into dissolving pulp, as an alternative to the pre-hydrolysis kraft (PHK) process. In addition, a viscosity reduction was achieved by cellulase (endoglucanase) treatment in the beginning of the sequence, while the GH11 and GH10 xylanases contributed to boost the brightness of the final pulp. The second part of the work aimed at exploring different auxiliary enzyme activities together with a key xylanase towards further removal of recalcitrant hemicelluloses from a partially bleached Eucalypt Kraft pulp. The resistant fraction (ca. 6% xylan in pulp) was not hydrolysable by the different combinations of enzymes tested. Production of a dissolving pulp was successful when using a cold caustic extraction (CCE) stage in the end of the sequence O-X-DHCE-X-HCE-D-CCE. The application of enzymes improved process efficiency. The main requirements for the production of a dissolving pulp (suitable for viscose making) were fulfilled: 2,7% residual xylan, 92,4% of brightness, a viscosity within the values of a commercial dissolving pulp and increased reactivity.

Wood-derived biomaterials for biomedical applications

Driven by the global trend in the sustainable economy development and environmental concerns, the exploring of plant-derived biomaterials or biocomposites for potential biomedical and/or pharmaceutical applications has received tremendous attention. Therefore, the work of this thesis is dedicated to high-value and high-efficiency utilization of plant-derived materials, with the focus on cellulose and hemicelluloses in the field of biomedical applications in a novel biorefinery concept. The residual cellulose of wood processing waste, sawdust, was converted into cellulose nanofibrils (CNFs) with tunable surface charge density and geometric size through 2,2,6,6-tetramethylpiperidinyloxy (TEMPO)-mediated oxidation and mechanical defibrillation. The sawdust-based CNFs and its resultant free-standing films showed comparable or even better mechanical properties than those from a commercial bleached kraft pulp at the same condition, demonstrating the feasibility of producing CNFs and films thereof with outstanding mechanical properties from birch sawdust by a process incorporated into a novel biorefinery platform recovering also polymeric hemicelluloses for other applications. Thus, it is providing an efficient route to upgrade sawdust waste to valuable products. The surface charge density and geometric size of the CNFs were found to play key roles in the stability of the CNF suspension, as well as the gelling properties, swelling behavior, mechanical stiffness, morphology and microscopic structural properties, and biocompatibility of CNF-based materials (i.e. films, hydrogels, and aerogels). The CNFs with tunable surface chemistry and geometric size was found promising applications as transparent and tough barrier materials or as reinforcing additive for production of biocomposites. The CNFs was also applied as structural matrices for the preparation of biocomposites possessing electrical conductivity and antimicrobial activity by in situ polymerization and coating of polypyrrole, and incorporation of silver nanoparticles, which make the material possible for potential wound healing application. The CNF-based matrices (films, hydrogels, and aerogels) with tunable structural and mechanical properties and biocompatibility were further prepared towards an application as 3D scaffolds in tissue engineering. The structural and mechanical strength of the CNF matrices could be tuned by controlling the charge density of the nanocellulose, as well as the pH and temperature values of the hydrogel formation conditions. Biological tests revealed that the CNF scaffolds could promote the survival and proliferation of tumor cells, and enhance the transfection of exogenous DNA into the cells, suggesting the usefulness of the CNF-based 3D matrices in supporting crucial cellular processes during cell growth and proliferation. The CNFs was applied as host materials to incorporate biomolecules for further biomedical application. For example, to investigate how the biocompatibility of a scaffold is influenced by its mechanical and structural properties, these properties of CNF-based composite matrices were controlled by incorporation of different hemicelluloses (O-acetyl galactoglucomanan (GGM), xyloglucan (XG), and xylan) into CNF hydrogel networks in different ratios and using two different approaches. The charge density of the CNFs, the incorporated hemicellulose type and amount, and the swelling time of the hydrogels were found to affect the pore structure, the mechanical strength, and thus the cells growth in the composite hydrogel scaffolds. The mechanical properties of the composite hydrogels were found to have an influence on the cell viability during the wound healing relevant 3T3 fibroblast cell culture. The thusprepared CNF composite hydrogels may work as promising scaffolds in wound healing application to provide supporting networks and to promote cells adhesion, growth, and proliferation.

Pirólise termoquímica de pós da fibra de coco seco em um reator de cilindro rotativo para produção de bio-óleo

This master thesis aims at developing a new methodology for thermochemical degradation of dry coconut fiber (dp = 0.25mm) using laboratory rotating cylinder reactor with the goal of producing bio-oil. The biomass was characterized by infrared spectroscopy with Fourier transform FTIR, thermogravimetric analysis TG, with evaluation of activation energy the in non-isothermal regime with heating rates of 5 and 10 °C/min, differential themogravimetric analysis DTG, sweeping electron microscopy SEM, higher heating value - HHV, immediate analysis such as evaluated all the amounts of its main constituents, i.e., lignin, cellulose and hemicelluloses. In the process, it was evaluated: reaction temperature (450, 500 and 550oC), carrier gas flow rate (50 and 100 cm³/min) and spin speed (20 and 25 Hz) to condensate the bio-oil. The feed rate of biomass (540 g/h), the rotation of the rotating cylinder (33.7 rpm) and reaction time (30 33 min) were constant. The phases obtained from the process of pyrolysis of dry coconut fiber were bio-oil, char and the gas phase non-condensed. A macroscopic mass balance was applied based on the weight of each phase to evaluate their yield. The highest yield of 20% was obtained from the following conditions: temperature of 500oC, inert gas flow of 100 cm³/min and spin speed of 20 Hz. In that condition, the yield in char was 24.3%, non-condensable gas phase was 37.6% and losses of approximately 22.6%. The following physicochemical properties: density, viscosity, pH, higher heating value, char content, FTIR and CHN analysis were evaluated. The sample obtained in the best operational condition was subjected to a qualitative chromatographic analysis aiming to know the constituents of the produced bio-oil, which were: phenol followed by sirigol, acetovanilona and vinyl guaiacol. The solid phase (char) was characterized through an immediate analysis (evaluation of moisture, volatiles, ashes and fixed carbon), higher heating value and FTIR. The non-condensing gas phase presented as main constituents CO2, CO and H2. The results were compared to the ones mentioned by the literature.

Fiber, a component for health gastrointestinal endocrine system

Dietary fiber was classified according to its solubility in an attempt to relate physiological effects to chemical types of fiber. Soluble fibers (B-glucans, gums, wheat dextrin, psyllium, pectin, inulin) were considered to have benefits on serum lipids, while insoluble fibers (cellulose, lignin, pectins, hemicelluloses) were linked with laxation benefits. More important characteristics of fiber in terms of physiological benefits are viscosity and fermentability. Viscous fibers (pectins, B-glucans, gums, psyllium) are those that have gel-forming properties in the intestinal tract, and fermentable fibers (wheat dextrin, pectins, B-glucans, gum, inulin) are those that can be metabolized by colonic bacteria. Objective: To summarize the beneficial effects of dietary fiber, as nutraceuticals, in order to maintain a healthy gastrointestinal system. Methods: Our study is a systematic review. Electronic databases, including PubMed, Medline, with supplement of relevant websites, were searched. We included randomized and non-randomized clinical trials, epidemiological studies (cohort and case-control). We excluded case series, case reports, in vitro and animal studies. Results: The WHO, the U.S. Food and Drug Administration (FDA), the Heart Foundation and the Romanian Dietary Guidelines recommends that adults should aim to consume approximately 25–30 g fiber daily. Dietary fiber is found in the indigestible parts of cereals, fruits and vegetables. There are countries where people don’t eat enough food fibers, these people need to take some kind of fiber supplement. Evidence has been found that dietary fiber from whole foods or supplements may (1) reduce the risk of cardiovascular disease by improving serum lipids and reducing serum total and low-density lipoprotein (LDL) cholesterol concentrations, (2) decreases the glycaemic index of foods, which leads to an improvement in glycemic response, positive impact on diabetes, (3) protect against development of obesity by increasing satiety hormone leptin concentrations, (4) reduced risk of developing colorectal cancer by normalizes bowel movements, improve the integrity of the epithelial layer of the intestines, increase the resistance against pathogenic colonization, have favorable effects on the gut microbiome, wich is the second genomes of the microorganisms, (5) have a positive impact on the endocrine system by gastrointestinal polypeptide hormonal regulation of digestion, (6) have prebiotic effect by short-chain fatty acids (SCFA) production; butyrate acid is the preferred energy source for colonic epithelial cells, promotes normal cell differentiation and proliferation, and also help regulate sodium and water absorption, and can enhance absorption of calcium and other minerals. Although all prebiotics are fiber, not all fiber is prebiotic. This generally refers to the ability of a fiber to increase the growth of bifidobacteria and lactobacilli, which are beneficial to human health, and (7) play a role in improving immune function via production of SCFAs by increases T helper cells, macrophages, neutrophils, and increased cytotoxic activity of natural killer cells. Conclusion: Fiber consumption is associated with high nutritional value and antioxidant status of the diet, enhancing the effects on human health. Fibers with prebiotic properties can also be recommended as part of fiber intake. Due to the variability of fiber’s effects in the body, it is important to consume fiber from a variety of sources. Increasing fiber consumption for health promotion and disease prevention is a critical public health goal.

The initial phase of sodium sulfite pulping of softwood : A comparison of different pulping options

Single stage and two-stage sodium sulfite cooking were carried out on either spruce, pine or pure pine heartwood chips to investigate the influence of several process parameters on the initial phase of such a cook down to about 60 % pulp yield. The cooking experiments were carried out in the laboratory with either a lab-prepared or a mill-prepared cooking acid and the temperature and time were varied. The influences of dissolved organic and inorganic components in the cooking liquor on the final pulp composition and on the extent of side reactions were investigated. Kinetic equations were developed and the activation energies for delignification and carbohydrate dissolution were calculated using the Arrhenius equation. A better understanding of the delignification mechanisms during bisulfite and acid sulfite cooking was obtained by analyzing the lignin carbohydrate complexes (LCC) present in the pulp when different cooking conditions were used. It was found that using a mill-prepared cooking acid beneficial effect with respect to side reactions, extractives removal and higher stability in pH during the cook were observed compared to a lab-prepared cooking acid. However, no significant difference in degrees of delignification or carbohydrate degradation was seen.  The cellulose yield was not affected in the initial phase of the cook however; temperature had an influence on the rates of both delignification and hemicellulose removal. It was also found that the  corresponding activation energies increased in the order:  xylan, glucomannan, lignin and cellulose. The cooking temperature could thus be used to control the cook to a given carbohydrate composition in the final pulp. Lignin condensation reactions were observed during acid sulfite cooking, especially at higher temperatures. The LCC studies indicated the existence of covalent bonds between lignin and hemicellulose components with respect to xylan and glucomannan. LCC in native wood showed the presence of phenyl glycosides, ϒ-esters and α-ethers; whereas the α-ethers  were affected during sulfite pulping. The existence of covalent bonds between lignin and wood polysaccharides might be the rate-limiting factor in sulfite pulping.

Different dietary fibres included in the gestation and lactation diet shape sow's microbiota, modify colostrum and milk composition and affect piglet growth and health

This thesis reports three experimental studies that may contribute to understand how the sources or types of dietary fibres (DFs) included in sow diet with similar level of total DFs influence the composition of colostrum and milk and their related effects on offspring performance and gut microbiota. The first study showed that decreasing the level of hemicelluloses (HCs) in sow’s lactation diet increased the proportion of butyrate and the concentration of volatile fatty acids (VFAs), copper and threonine in milk. Simultaneously, the post-weaning growth of low birthweight piglets was improved, and the diarrhoea occurrence was reduced during the second week post-weaning. The second study showed that the level of HCs in the diet of lactating sows affected their faecal microbiota, modified the VFA profile in sow’s faeces during lactation and barely impacted the faecal microbiota of slow and fast growing piglets. The third study showed that replacing a source soluble DFs by one of insoluble DFs in sow’s diet during late gestation and lactation reduced farrowing duration, increased total VFAs and lactoferrin concentrations in colostrum, improved growth performance from birth to 1 day of lactation, during the post-weaning period and throughout the study, and reduced diarrhoea occurrence during the first week post-weaning. Finally, a fourth study proposed a workflow to analyse low biomass samples from the umbilical cord blood aiming at investigating the existence of a pre-birth microbiota with no substantial findings to confirm this hypothesis. Overall, the results of these studies confirmed that, besides the level of DFs, the sources, and the types of DFs included in the sow's diet shape the sow's microbiota, influence the composition of colostrum and milk, and improve offspring performance, but with limited impacts on the microbiota of piglets.