Type I Diabetes is a multisystem disease having both biochemical and structural consequences. It causes alterations in carbohydrate, protein, and fat metabolisms due to hyperglycemia. Type I diabetes is also correlated with increased formation of free radicals and decreased levels of antioxidant potential. Lower endogeneous antioxidant amounts and elevated lipid peroxidation levels in diabetes constitute the basis of risk factors for the development of diabetic complications. These complications lead to irreversible damages in nearly all vital organs and systems. Since the antioxidant capacity lowered in diabetic conditions, it becomes important to be able to use some common antioxidants, as a complementary treatment strategy for diabetes. The effect of type I diabetes and the recovery role of Vitamin C on the structure, composition and function of the macromolecular content of testicular tissue is still unknown. Therefore, in the current study, it was aimed to investigate the alterations in the macromolecules of rat testes due to Streptozotocin (STZ)-induced type I diabetes using Attenuated Total Reflectance (ATR)-Fourier Transform Infrared (FTIR) spectroscopic and FTIR microspectroscopic techniques. Furthermore it was iv aimed to gain useful information about the recovery role of Vitamin C, as an antioxidant, against the diabetic complications. The detailed spectral analysis revealed that, the macromolecular structure and composition of rat testes are highly affected due to the development of diabetes. The lipid and protein content of diabetic rat testes were shown to decrease considerably, indicating an increase in lipolysis and proteolysis processes. Diabetes was also shown to lead to a decrease in the content of fatty acids and nucleic acids. In addition to the compositional alterations, protein conformation, and protein secondary structural components were also found to alter in diabetic state. Besides, lipid peroxidation levels were found to increase, and the elevated levels of lipid peroxidation products end up with increased levels of unsaturation, and also end up with increased levels of disorderness in diabetic conditions. On the other hand, with the administration of Vitamin C, the diabetes-induced alterations were found to be partially recovered, indicating that after more confirmative researches, Vitamin C may have a chance to be used as a complementary therapy in the treatment of diabetes.

The overall thrust of this project is to gain an insight into a class of surface-tethered cross-linked thin films of poly(N-alkylacrylamides) that display a lower critical solution temperature (LCST).The structure of the alkyl group and the modification of the amide groups determine the LCST and resultant volume-phase transition behavior. The aim of this study involves synthesis and characterization of thin films and to correlate the volume-transition behavior to the structure of the alkyl group. For better understanding the volume-transition behavior, the polymer films are perturbed by the Hofmeister salt series to examine trends between different alkyl groups. While most of the studies have been done with bulk gels, the majority of the applications require the use of gels at surfaces and interfaces. Surface attached polymer networks provide an alternative to bulk gels showing superior response times, thus efficiency. Hence it is significant to understand the impact of confinement on the phase transition behavior of a polymer network. Anchoring a polymer network to a surface produces volume phase transition perpendicular to the substrate. The parallel swelling and collapse of the network is highly restricted due to lateral confinement, thus impacting properties such as structure, mechanical properties, dynamics and permeability of the network. Several studies have been done with poly(N-isopropylacrylamide) anchored to a substrate, which have shown significantly different behavior than unconstrained networks. Notable examples include a gradual as opposed to a sharp volume-phase transition, and significantly less swelling above and below the LCST. These studies only looked at poly(NIPAAm); therefore it remains unknown if these results are universal and will apply to other LCST polymers. Hence, we expanded upon these studies to also investigate a library of different LCST polymers belonging to the category of N-alkylacrylamides. I have synthesized the copolymers comprising of N-alkylacrylamides and methacryloxybenzophenone (MaBP). The benzophenone moiety in MaBP is photoreactive, allowing us to cross-link the copolymers by UV irradiation. Surface attached thin films were fabricated by spin coating the solution of copolymers and cross-linking by UV irradiation. The volume phase transitions of the coatings were studied under the influence of temperature and the salts of the Hofmeister series. Information concerning the state of responsive layers, the precise temperature at which the collapse occurs, and the changes in the molecular environment during the transition were investigated by ellipsometry and ATR-FTIR. In a longer perspective, understanding the transition behavior and the influence of salts governing this transition provides a better understanding of the interactions of biopolymers in natural systems.

Production of and demand for Canadian canola meal have been increased yearly. In order to improve the competitiveness of canola meal domestically and internationally, as well as to develop potential markets for canola meal, it is necessary to develop canola meal-based products that have high feed values and can be easily transported. The objectives of this research were: 1) to investigate the effects of temperature and time of conditioning during pelleting process on the nutritive values of canola meal in terms of chemical profiles, protein and carbohydrate subfractions, and energy values, using the AOAC procedures, CNCPS v6.1 and NRC (2001), respectively; 2) to detect the effects of temperature and time of conditioning during the pelleting process on rumen degradation and intestinal digestion characteristics and predicted protein supply of canola meal, using the in situ procedure, the three-step in vitro procedure, and the NRC 2001 model; and 3) to determine pelleting-induced changes in spectral characteristics of molecular structures of canola meal using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) with univariate and multivariate analysis, and reveal the relationship between molecular structures of protein and carbohydrate and nutrient values, rumen degradation and intestinal digestion characteristics, and predicted protein supply of canola meal. Three different conditioning temperatures (70, 80 and 90ºC) and two different conditioning time (50 and 75 sec) were applied in this research. Two different batches of canola meal from a commercial feed company were selected. A randomized complete block design (RCBD) with 3 × 2 factorial arrangement was employed in this research. Molecular spectral functional groups related to protein, cellulosic compounds, and carbohydrates were used in the spectral study. This research indicated: 1) soluble crude protein (SCP) was decreased and neutral detergent insoluble CP (NDICP) was increased with increasing temperature; 2) the lowest protein rumen degradation of pellets was observed at conditioning temperature of 90 ºC and protein rumen degradation was increased by pelleting; 3) the amount of protein digested in the small intestine tended to increase with increasing conditioning temperature; 4) pelleting under different temperatures and time in the current study shifted the protein digestion site to the rumen, rather than to the small intestine; 5) with respect to predicted protein supply, based on the NRC 2001 model, increasing conditioning temperature tended to increase the metabolizable protein supply of canola meal pellets to dairy cattle; 6) changes in the molecular structure of canola meal induced by pelleting can be detected by ATR-FTIR; 7) not only protein molecular structure characteristics but also carbohydrate molecular structure characteristics play important roles in determining nutrient values, rumen degradation and intestinal digestion characteristics, and the predicted protein supply of canola meal.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2018-02-21T21:24:26Z No. of bitstreams: 1 AlineDeSousaMarques_TESE.pdf: 5792072 bytes, checksum: 2628df662db724e0c0d729e9a2af99c5 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2018-02-22T21:38:32Z (GMT) No. of bitstreams: 1 AlineDeSousaMarques_TESE.pdf: 5792072 bytes, checksum: 2628df662db724e0c0d729e9a2af99c5 (MD5) / Made available in DSpace on 2018-02-22T21:38:32Z (GMT). No. of bitstreams: 1 AlineDeSousaMarques_TESE.pdf: 5792072 bytes, checksum: 2628df662db724e0c0d729e9a2af99c5 (MD5) Previous issue date: 2017-08-18 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Esta tese de doutorado ? um aporte te?rico-pr?tica para o desenvolvimento de estudos que utilizem a bioanal?tica, particulamente materiais biol?gicos provenientes de bact?rias, podendo estes ser isolados, DNA, entre outros, em conjunto com ferramentas quimiom?ticas de an?lise. Para isso, buscou-se identificar diferen?as bacterianas quando submetidas a uma fonte de estresse a partir de diferentes t?cnicas anal?ticas. A primeira abordagem foi realizada partindo da bioespectroscopia, utilizando-se de dados espectrosc?picos obtidos na regi?o do infravermelho. A bioespectroscopia na regi?o do infravermelho ? descrita como uma t?cnica n?o invasiva, de alto rendimento, baixo custo (quando comparado com t?cnica padr?es de an?lise) e objetivas, e que possui um enorme potencial na an?lise de bact?rias, complementando ou mesmo substituindo m?todos de diagn?stico de doen?as convencionalmente conduzidos por especialistas atrav?s de m?todos padr?es de an?lises de alto custo e que necessitam de reagentes espec?ficos. Os dados obtidos a partir da bioespectroscopia em amostras bacterianas s?o complexos e apresentam muitas bandas de sobreposi??o sendo necess?ria a aplica??o de ferramentas matem?ticas para superar estas dificuldades. Para isso, algumas ferramentas matem?ticas, como os m?todos de sele??o de vari?veis, que utilizam a an?lise discriminante linear com Algoritmo de Proje??o Sucessiva (SPA-LDA) e Algoritmo Gen?tico (GA-LDA), geralmente s?o utilizadas com a finalidade de facilitando a extra??o de informa??es relevantes. A espectroscopia na regi?o do infravermelho, em espec?fico infravermelho pr?ximo (NIR) e infravermelho com trasformata de Fourier e reflect?ncia total atenuada (ATR-FTIR), em conjunto com m?todos de sele??o de vari?veis (SPA-LDA e GA-LDA) foram utilizadas na discrimina??o de amostras de bact?rias (Sthaphylococcus aureus, Klebsiella pneumoneae e Pseudomonas aeruginosa). Foram identificados prov?veis biomarcadores como lip?deos e prote?nas em ~1550 cm-1 e 1400 cm-1 e vibra??es de DNA em ~1080 cm-1. Valores de sensibilidade de 75% e 95% para modelos de SPA-LDA e 100% e 93% para modelos GA-LDA foram encontrados. Com base nesses resultados, pode-se concluir que o SPA-LDA e GA-LDA em conjunto com a espectroscopia na regi?o do infravermelho mostraram-se ferramentas eficientes melhorando o tempo e custo de diagn?stico possibilitando o tratamento mais r?pido em rela??o aos m?todos padr?es de diagn?stico e, consequentemente, sendo poss?vel evitar a evolu??o de uma poss?vel infec??o. A segunda abordagem foi avaliar poss?veis mudan?as no perfil lipid?mico de bact?rias resultante de sua exposi??o a uma fonte de estresse externa (Ars?nio (III)), utilizando as cianobact?rias Anabaena sp. e Planktothrix agardhii. Os dados foram obtidos a partir a Cromatografia L?quida- Espectrometria de Massas (LC-MS) que por gerar uma matriz de dados muito extensa foi necess?ria a utiliza??o de uma estrat?gia de sele??o proposta recentemente, definida como ROI (do ingl?s regions of interests) que diminui significativamente o tamanho da matriz de dados obtidas por LC-MS. Resolu??o Multivariada de Curvas com M?nimos Quadrados Alternantes (MCR-ALS) foi utilizado como m?todo de resolu??o das fontes de varia??o, recuperando as informa??es de seus componentes puros que se encontravam misturadas. As massas majorit?rias encontradas, sendo algumas delas 766.54, 565.40 e 871.56 (m/z), determinam que as cianobact?rias estudadas, ao serem submetidas a As(III), sofrem mudan?as relacionadas a estruturas que comp?em os processos fotossint?ticos das mesmas. / This doctoral thesis is a theoretical-practical contribution for the development of studies that use bioanalytical, particularly biological materials from bacteria, which can be isolated, DNA, among others, in conjunction with chemistry analysis tools. For this, it was sought to identify bacterial differences when submitted to a source of stress from different analytical techniques. The first approach was based on biospectroscopy, using spectroscopic data obtained in the infrared region. Biospectroscopy in the infrared region is described as a non-invasive, high-throughput, low-cost (when compared with standard analytical techniques) and objective techniques, and has a huge potential in the analysis of bacteria, complementing or even replacing diagnostic methods of diseases conventionally conducted by skilled persons by standard methods of expensive analyzes and requiring specific reagents. The data obtained from biospectroscopy in bacterial samples are complex and have many overlapping bands and it is necessary to apply mathematical tools to overcome these difficulties. For this, some mathematical tools, such as variable selection methods, using Linear Discriminant Analysis with Successive Projection Algorithm (SPA-LDA) and Genetic Algorithm (GA-LDA), are generally used for the purpose of solving these data, facilitating the extraction of information. Infrared spectroscopy, in specific Near Infrared (NIR) and infrared spectroscopy with Fourier transform and Attenuated Total Reflectance (ATR- FTIR), in conjunction with variable selection methods (SPA-LDA and GA-LDA) was used in the discrimination of bacterial samples (Sthaphylococcus aureus, Klebsiella pneumoneae and Pseudomonas aeruginosa). Possible biomarkers such as lipids and proteins were identified at ~ 1550 cm -1 and 1400 cm -1 and DNA vibrations at ~ 1080 cm -1. Sensitivity values of 75% and 95% for SPA-LDA models and 100% and 93% for GA-LDA models were found. Based on these results, it can be concluded that the SPA-LDA and GA- LDA in conjunction with the infrared spectroscopy showed efficient tools improving the time and cost of diagnosis allowing the treatment faster than the standard methods of diagnosis, and consequently, it is possible to avoid the evolution of a possible infection. The second approach was to evaluate possible changes in the lipid profile of bacteria resulting from its exposure to an external stress source (Arsenic (III)), using the cyanobacteria Anabaena sp. and Planktothrix agardhii. The data were obtained from Liquid Chromatography-Mass Spectrometry (LC-MS), which, in order to generate a very extensive data matrix, required the use of a recent selection strategy, defined as ROI (regions of interest), which significantly decreased the Size of the data matrix obtained by LC-MS. Multivariate Curve Resolution - Alternating Least Squares (MCR-ALS) was used as a method to solve variation sources, retrieving the information of its pure components that were mixed. The majority masses found, such as 766.54, 565.40 and 871.56 (m/z), determine that the studied cyanobacteria, when subjected to As (III), undergo changes related to structures that make up the photosynthetic processes of the same.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-10-18T20:17:23Z No. of bitstreams: 1 AnaCarolinaDeOliveiraNevesMenezes_TESE.pdf: 10687959 bytes, checksum: ac1430b19dc8e137155eb42a1171c56b (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-10-19T20:52:18Z (GMT) No. of bitstreams: 1 AnaCarolinaDeOliveiraNevesMenezes_TESE.pdf: 10687959 bytes, checksum: ac1430b19dc8e137155eb42a1171c56b (MD5) / Made available in DSpace on 2017-10-19T20:52:18Z (GMT). No. of bitstreams: 1 AnaCarolinaDeOliveiraNevesMenezes_TESE.pdf: 10687959 bytes, checksum: ac1430b19dc8e137155eb42a1171c56b (MD5) Previous issue date: 2017-08-09 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Esta tese relata a aplica??o das espectroscopias no infravermelho m?dio, de fluoresc?ncia molecular e espectrometria de massas, combinadas a t?cnicas de an?lise multivariada, para classifica??o de c?lulas cancerosas em cultivo e de les?es pr?-cancerosas atrav?s de plasma sangu?neo. Em um primeiro estudo, matrizes de excita??o/emiss?o de fluoresc?ncia molecular foram obtidas para diferentes linhagens de c?lulas normais (3T3, ARPE, HEK) e cancerosas (HepG2, HeLa, HT-29, 786-0) e modelos de classifica??o foram constru?dos utilizando uma combina??o dos algoritmos OPLS e UPLS-DA. Taxas de acerto de 100% e 75% foram obtidas para as classes Normal e Cancerosa, respectivamente. Ainda, foi avaliada a influ?ncia dos anticorpos anti-MMP-2 e anti-MMP-9 no desempenho dos modelos de classifica??o. Na presen?a dos anticorpos, as taxas de acerto nas classifica??es aumentaram consideravelmente atingindo 100% para ambas as classes, Normal e Cancerosa, atrav?s dos algoritmos OPLS/UPLS-DA. Em um segundo estudo, a espectroscopia ATR-FTIR foi utilizada para obten??o de espectros de plasmas sangu?neos de mulheres saud?veis (negativas para les?o intraepitelial ou malignidade, NILM) e portadoras de les?o intraepitelial cervical (SIL) de baixo (LSIL) ou alto grau (HSIL), causadas pelo v?rus HPV. Modelos multivariados de classifica??o foram constru?dos, visando uma metodologia de rastreamento para o c?ncer cervical. Os algoritmos PCA-LDA/QDA, SPA-LDA/QDA e GA-LDA/QDA foram aplicados como ferramentas de classifica??o e seus desempenhos comparados. De maneira geral, os resultados obtidos atrav?s do algoritmo GA-QDA foram os mais satisfat?rios, utilizando apenas vari?veis espectrais selecionadas que puderam ser relacionadas a grupos funcionais pertencentes a diferentes biomol?culas. Os modelos GA-QDA classificaram corretamente NILM vs. SIL com sensibilidade e especificidade em torno de 90% e 83%, respectivamente. NILM vs. LSIL apresentaram sensibilidade e especificidade variando entre 67-94% e 82-94%, respectivamente. Para NILM vs. HSIL, os valores de sensibilidade e especificidade estiveram entre 76-97% e 73-100%, respectivamente. Em um terceiro estudo, a espectrometria de massas foi aplicada para obter os espectros de lip?dios extra?dos do plasma sangu?neo de mulheres da Classe NILM (n=42) e SIL (n=34). Modelos de classifica??o multivariados foram constru?dos utilizando os classificadores LDA, QDA e SVM. Os modelos baseados em SVM permitiram a discrimina??o das classes com sensibilidade e especificidade de 83.3% e 80.0% para NILM e SIL, respectivamente. Alguns poss?veis lip?dios foram associados a cada classe, tais como prostaglandinas, esfingolip?dios e fosfolip?dios, Tetranor-PGFM e um lip?dio hidroxiperoxidado. Os resultados obtidos em todos os estudos evidenciam a potencialidade das t?cnicas espectrosc?picas e multivariadas como poss?veis metodologias de rastreamento e identifica??o de c?ncer, o que poderia contribuir fortemente para a redu??o da morbidade e mortalidade causadas pela doen?a. / This thesis reports the application of both infrared and molecular fluorescence spectroscopy, as well as mass spectrometry, combined with multivariate analysis techniques for classification of cancerous cells in culture medium and precancerous lesions in blood plasma. In a first study, excitation/emission matrices of molecular fluorescence were obtained for normal (3T3, ARPE, HEK) and cancerous (HepG2, HeLa, HT-29, 786-0) cell lines and classification models were built by using a combination of the algorithms OPLS and UPLS-DA. Correct classification indexes of 100% and 75% were obtained for both classes, Normal and Cancer, respectively. In addition, it was evaluated the influence of the antibodies anti-MMP-2 and anti-MMP-9 in the performance of the classification models. In the presence of the antibodies, the correct classification indexes were considerably improved reaching 100% for both classes, Normal and Cancer, using the algorithms OPLS/UPLS-DA. In a second study, the ATR-FTIR spectroscopy was applied to obtain the spectra of blood plasma of both healthy women (negative for intraepithelial lesion or malignancy, NILM) and women with cervical intraepithelial lesion (SIL) of low grade (LSIL) or high grade (HSIL), caused by HPV virus. Multivariate classification models were built, aiming a screening methodology for cervical cancer. The algorithms PCA-LDA/QDA, SPA-LDA/QDA and GA-LDA/QDA were applied as classification tools and their performance was evaluated. In general, the results obtained by GA-QDA were the most satisfactory, by using only chosen spectral variables that could be related to chemical groups of different biomolecules. The models GA-QDA correctly classified NILM vs. SIL with sensitivity and specificity around 67-94% e 82-94%, respectively. For NILM vs. LSIL, sensitivity and specificity values were about 67-94% e 82-94%, respectively. For NILM vs. HSIL, the sensitivity and specificity values were 76-97% e 73-100%, respectively. In the third study, mass spectrometry was applied to obtain the spectra of lipids extracted from blood plasma of women of NILM (n=42) and SIL (n=34) classes. Multivariate classification models were built by using the classifiers LDA, QDA and SVM. SVM-based models allowed to discriminate the classes with sensitivity and specificity values of 83.3% and 80.0% for NILM and SIL, respectively. Some possible lipids were associated to each class, such as prostaglandins, phospholipids, sphingolipids, Tetranor-PGFM and a hydroperoxide lipid. The results achieved in all studies highlight the potentiality of the spectroscopic and multivariate techniques as possible methodologies for cancer screening, what could effectively contribute to reduce morbidity and mortality caused by cancer.

This doctoral thesis studies the properties and behaviour of phase-separated hydrogels. These can be prepared by interaction of polyelectrolytes with oppositely charged surfactants. Negatively charged polysaccharide hyaluronan and cationic surfactant carbethopendecinium bromide (Septonex), whose properties, behaviour and utilization are described in the first two chapters of theoretical part, were selected for this role. Hyaluronan is naturally-occuring in living organisms and is known for his specific targeting to the tumour cells. Septonex is used as antiseptic and disinfectant. Experimental part of this work is focused on examination of the structure and behaviour of these types of hydrogels especially from rheological point of view. The crucial part of this study was to establish mechanical properties and their dependence on environment. This led to design further studies. Structural analysis was held using the methods of ATR-FTIR, ionic chromatography and ICP-OES helping to measure the inner content of entry materials in the gels and supernatants respectively. The last chapter deals with antimicrobial activity. The results of this study indicate a potential usage of these substances in the field of medical applications.

This study aims to detect how many microplastics and what kind are released from the wastewater treatment plant (WWTP) Skebäck, in Örebro. The study was limited to the analysis of three filters with 50 μm mesh size and one filter with 300 μm mesh size. The samples were taken at different times, two in the fall of 2019 and one in the spring of 2020. Visual characterization was used for the quantification of microplastics, and a lower and upper bound was used. The lower bound represents particles that were deemed identifiable as plastic with high certainty, while the upper bound also includes particles that may have been microplastic. An additional ATR-FTIR analysis was performed on selected microplastics >300 μm.  The presence of microplastics in the effluent from Skebäcks WWTP could be confirmed. The quantity of microplastics per m​3​ (MP/m​3​) trapped on the 50 μm filters were quantified in a range between 0 MP/m​3​ to 291 MP/m​3​ for the lower bound, and 72 MP/m​3​ to 435 MP/m​3​ for the upper bound. The 300 μm filter had considerably less microplastics than the 50 μm filter with 1.8 MP/m​3​. The quantification of fibers on the 50 μm filter and 300 μm filters was not possible due to high blank contaminations. According to the concentration of 63 MP/m​3​ of the lower bound count on the 50 μm filters and the amount of water flowing through Skebäck in 2019, 17 818 935 m​3​, 1.1 billion microplastic particles were released into Svartån that year. In comparison the highest value of the upper bound count, 435 MP/m​3​, gave a release of 7.7 billion microplastic particles. Using the concentration of the 300 μm filter 1.8 MP/m​3​, 32 million microplastics/year were released from Skebäck in 2019. The amount of spheres 50-300 μm released in the effluent from Skebäck was estimated to be 3.7 kg in 2019.

The present work was performed at Sherwin–Williams Sweden group AB with the objective of comparing short-wavelength light emitting diodes (UVB/UVC) with the conventional mercury arc lamp as a curing method of acrylate-based, UV-paint undergoing free-radical polymerization when exposed to UV-radiation. Due to environmental and health risks, mercury-doped radiation sources will be phased out in the near future, according to the United Nations Minamata convention, hence new alternatives are needed. Light-emitting diodes differ from the mercury arc lamp as they provide semi-discrete output intensity lines within the UV spectrum instead of a broad output distribution with several main intensity lines. The power output is also considerably lower compared to the conventional method which limits the irradiance and dose that are key parameters in activating and propagating free-radical polymerization of UV-paint. Seven different light-emitting diodes between 260–320 nm was examinedand compared to the conventional mercury arc lamp. Cured coatings were evaluated by measuring the relative extent of acrylate conversion with ATR-FTIR and micro-hardness indentation test. Both methods correlate to the relative cross-linking density and qualitatively describe the curing process for each radiant source at a specific irradiance and dose. Three different paint formulations with widely different properties were used in the experiments. All three paints were able to cure with one or several light emitting diodes at comparable doses and 10 to 20 times lower irradiance to the conventional mercury arc lamp, resulting in similar acrylate conversion and hardness.

Sodium dithionite (Na2S2O4) is a powerful reducing agent. It has therefore been suggested to be used as an additive in kraft pulping to improve the yield. However, sodium dithionite easily decomposes and it is thus important to determine the effect of different conditions. The aim of this thesis has been to investigate the thermal stability of sodium dithionite under anaerobic conditions using ATR-FTIR spectroscopy under different conditions, such as heating temperature, concentration of the solution, heating time and pH. The stability of sodium dithionite was found to decrease with increasing heating temperature, concentration of sodium dithionite, heating time and pH. Sodium dithionite was found to be relatively stable at moderate alkaline pH:s 11.5 and 12.5, while a rapid decrease in stability with time was noted at higher heating temperatures and concentrations of sodium dithionite. Based on this study on the thermal stability of sodium dithionite, the following conditions are suggested as the most promising, when adding sodium dithionite to the kraft cooking as an additive; pH 12.5, with 0.4 M concentration of the solution, at a heating temperature of 100 °C.

No description available.