Law Chi-Kin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references. / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.iii / Table of Contents --- p.iv / List of Tables --- p.vi / List of Figures --- p.viii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- The Gaussian´ؤ3 Method --- p.1 / Chapter 1.2 --- The G3 Method with Reduced Mφller-Plesset Order and Basis Set --- p.2 / Chapter 1.3 --- The Gaussian-3X Method --- p.2 / Chapter 1.4 --- Calculation of Thermodynamical Data --- p.3 / Chapter 1.5 --- Remark on the Location of Equilibrium and Transition Structures --- p.3 / Chapter 1.6 --- Natural Bond Orbital (NBO) Analysis --- p.4 / Chapter 1.7 --- Scope of the Thesis --- p.4 / Chapter 1.8 --- References --- p.5 / Chapter Chapter 2 --- Gaussian´ؤ3 Heats of Formation for (CH)6 Isomers --- p.6 / Chapter 2.1 --- Introduction --- p.6 / Chapter 2.2 --- Methods of Calculation and Results --- p.7 / Chapter 2.3 --- Discussion --- p.9 / Chapter 2.4 --- Conclusion --- p.11 / Chapter 2.5 --- Publication Note --- p.12 / Chapter 2.6 --- References --- p.12 / Chapter Chapter 3 --- A Gaussian-3 Investigation of N7 Isomers --- p.14 / Chapter 3.1 --- Introduction --- p.14 / Chapter 3.2 --- Computational Method and Results --- p.16 / Chapter 3.3 --- Discussion --- p.16 / Chapter 3.4 --- Conclusion --- p.24 / Chapter 3.5 --- Publication Note --- p.24 / Chapter 3.6 --- References --- p.24 / Chapter Chapter 4 --- A Gaussian-3 Study of N7+ and N7- Isomers --- p.27 / Chapter 4.1 --- Introduction --- p.27 / Chapter 4.2 --- Computational Method and Results --- p.29 / Chapter 4.3 --- Discussion --- p.30 / Chapter 4.3.1 --- The N7+ isomers --- p.30 / Chapter 4.3.2 --- The N7- isomers --- p.37 / Chapter 4.4 --- Conclusion --- p.41 / Chapter 4.5 --- Publication Note --- p.41 / Chapter 4.6 --- References --- p.41 / Chapter Chapter 5 --- "Thermochemistry of Chlorine Fluorides ClFn, n = 1-7, and Their Singly Charged Cations and Anions: A Gaussian-3 and Gaussian-3X Study" --- p.45 / Chapter 5.1 --- Introduction --- p.45 / Chapter 5.2 --- Methods of Calculations --- p.47 / Chapter 5.3 --- Results and Discussion --- p.48 / Chapter 5.3.1 --- Comparison of the G3 and G3X methods --- p.48 / Chapter 5.3.2 --- Assessments of the experimental results --- p.54 / Chapter 5.3.3 --- "Bond dissociation energies of ClFn, ClFn+, and ClFn-" --- p.57 / Chapter 5.3.4 --- Summary of the thermochemical data --- p.58 / Chapter 5.4 --- Conclusion --- p.59 / Chapter 5.5 --- Publication Note --- p.60 / Chapter 5.6 --- References --- p.60 / Chapter Chapter 6 --- A Gaussian-3 Study of the Photoionization and Dissociative Photoionization Channels of Dimethyl Sulfide --- p.63 / Chapter 6.1 --- Introduction --- p.63 / Chapter 6.2 --- Methods of Calculations --- p.64 / Chapter 6.3 --- Results and Discussion --- p.64 / Chapter 6.3.1 --- Bond cleavage reactions --- p.67 / Chapter 6.3.2 --- Dissociation channels involving transition structures --- p.68 / Chapter 6.4 --- Conclusion --- p.70 / Chapter 6.5 --- Publication Note --- p.70 / Chapter 6.6 --- References --- p.70 / Chapter Chapter 7 --- "Theoretical Study of the Electronic Structures of Carbon and Silicon Nanotubes, Carbon and Silicon Nanowires" --- p.72 / Chapter 7.1 --- Introduction --- p.72 / Chapter 7.2 --- Models and Computational Methods --- p.74 / Chapter 7.3 --- Results and Discussion --- p.75 / Chapter 7.4 --- Conclusion --- p.87 / Chapter 7.5 --- Publication Note --- p.87 / Chapter 7.6 --- References --- p.87 / Chapter Chapter 8 --- Conclusion --- p.90 / Appendix A --- p.91 / Appendix B

The demand for energy continues to grow but concerns over climate change means that conventional fossil fuels will eventually need to be replaced. The solution to the energy crisis will require a combination of both conventional energy sources with CO2 capture and renewable technologies. While many renewable technologies exist, it is not common that CO2 capture is incorporated into the process. Biomass is an ideal feed-stock for bio-energy production as it is CO2 neutral. Many thermochemical conversion technologies exist, but the Alkaline Thermal Treatment (ATT) reaction is particularly interesting because it combines conventional thermochemical conversion with CO2 capture in order to create a process that is potentially CO2 negative. By reacting biomass with a metal hydroxide, high purity H2 can be produced while simultaneously locking the carbon as a stable carbonate, which is a form of Bio-energy with Carbon Capture & Storage (BECCS). The H2 can then be used for applications ranging from Fischer-Tropsch synthesis to PEM fuel cells. Group I & II hydroxides were investigated for their ability to react with cellulose (a biomass model compound) in the ATT reaction scheme. Comparison between both groups indicated that NaOH and Ca(OH)2 were the best hydroxides from groups I & II respectively. However, the amount of H2 produced during the ATT of cellulose with Ca(OH)2 is considerably lower than with NaOH. A 10% Ni/ZrO2 catalyst was then added to increase the yield of H2 from the reaction between cellulose and Ca(OH)2. It was found that at 20% catalyst loading, the amount of H2 produced and the suppressed level of CO2 was similar to the ATT with NaOH. Several other catalytic metals were also investigated and found to have the following H2 production activity: Ni > Pt≈Pd > Co > Fe, Cu. Since Ni was the most active and has a considerably lower cost than noble metals it was chosen for additional studies. The ATT reaction in the presence of Ni has two distinct steps in the formation of H2 from cellulose. The presence of Ca(OH)2 enhances the formation of linear oxygenates from cellulose. These oxygenates are then reformed over the Ni-based catalyst to H2 and CO2, the latter of which is captured by Ca(OH)2 to form CaCO3. If either Ca(OH)2 or Ni was removed from the reaction, the yield H2 fell significantly. Although the reactants and the catalyst are all solid materials, they do not need to be physically mixed. The Ni-based catalyst produced H2 primarily through the reforming of gaseous species and therefore could be placed ex-situ of the cellulose and Ca(OH)2 mixture. However, placing the catalyst away from Ca(OH)2 prevented CO2 capture. In order to remedy this Ca(OH)2 was mixed with the Ni-based catalyst and mixture was placed ex-situ of pure cellulose. This created a process whereby cellulose could be decomposed thermally followed by a single gas-phase Alkaline Thermal Treatment (GATT) reforming step of the pyrolysis vapors to H2 with suppressed CO2.

Thesis (Doctor of Engineering in Chemical Engineering)--Cape Peninsula University of Technology, 2017. / The search for alternatives to fossil fuel is necessary with a view to reducing the negative environmental impact of fossil fuel and most importantly, to exploit an affordable and secured fuel source. This study investigated the viability of municipal solid waste gasification for a fuel cell system. Potential solid fuels obtained from the study in the form of refuse-derived fuel (RDF) had high heating value (HHV) between 18.17 MJ/Kg - 28.91 MJ/Kg with energy density increased from 4142.07 MJ/m3 to 10735.80 MJ/m3. The molecular formulas of RDF derived from Ladies Smith drop-off site, Woodstock drop-off site and an average molecular formula of all thirteen municipal solid waste (MSW) disposal facilities were CH1.43O1.02, CH1.49O1.19, and CH1.50O0.86 respectively. The comparative ratios of C/H were in the range of 7.11 to 8.90. The Thermo Gravimetric Analysis showed that the dehydration, thermal decompositions, char combustions were involved in the production of gaseous products but flaming pyrolysis stage was when most tar was converted to syngas mixture. The simulation of RDF gasification allowed a prediction of the RDF gasification behaviour under various operating parameters in an air-blown downdraft gasifier. Optimum SFR (steam flowrate) values for RDF1, RDF2 and RDF3 were determined to be within these values 2.80, 2.50 and 3.50 and Optimum ER values for RDF1, RDF2 and RDF3 were also determined to be within these values 0.15, 0.04 and 0.08. These conditions produced the desired high molar ratio of H2/CO yield in the syngas mixture in the product stream. The molar ratios of H2/CO yield in the syngas mixture in the product stream for all the RDFs were between 18.81 and 20.16. The values of H2/CO satisfy the requirement for fuel cell application. The highest concentration of heavy metal was observed for Al, Fe, Zn and Cr, namely 16627.77 mg/Kg at Coastal Park (CP), 17232.37 mg/Kg at Killarney (KL), 235.01 mg/Kg at Tygerdal (TG), and 564.87 mg/Kg at Kraaifontein (KF) respectively. The results of quantitative economic evaluation measurements were a net return (NR) of $0.20 million, a rate of return on investment (ROI) of 27.88 %, payback time (PBP) of 2.30 years, a net present value (NPV) of $1.11 million and a discounted cash flow rate of return (DCFROR) of 24.80 % and 28.20 % respectively. The results of the economic evaluations revealed that some findings of the economic benefits of this system would be viable if costs of handling MSW were further quantified into the costs analysis. The viability of the costs could depend on government responsibility to accept costs of handling MSW.

Insight into the effect of secondary interactions, fluorination, as well as substituent effects on strong ionic hydrogen bonds has been acquired through studies of FHF-, NFnH3-n•••F- (n = 0..2) and [M-H]- (M = Glycine, Alanine, Valine, Serine) clustered with ROH (R = H, CH3, C2H5). Excellent agreement was observed between thermochemical values obtained from high pressure mass spectrometry measurements and those predicted from MP2(full)/6-311++G(d,p)//B3LYP/6-311++G(d,p) calculations. In the examination of the clustering of FHF-, a strong correlation between the hydrogen bond strength and the gas phase acidity of the solvent was observed. In addition, several interesting observations on various structural and thermochemical properties were made for each of the three solvents. Upon formation of clusters with water, it was found that the large entropic advantage of one particular structure, which was not the most enthalpically favored, was significant enough to make it the predominant species within the ion source. In the case of methanol solvation, no evidence of secondary interaction of the methyl group and any other moiety could be found. The structural details revealed from calculations of the ethanol-solvated clusters indicate that secondary interactions between the terminal methyl group and FHF- had an impact on the length of both the FHF and OHF bonds present. In an attempt to gain insight into the effects of fluorination on hydrogen bonding, clusters of NFnH3-n (n = 0..2) and F- have been computationally investigated. The hydrogen bond energy in NH3∙∙∙F-, NFH2∙∙∙F- and NF2H∙∙∙F- were calculated to be -67.9 kJ∙mol-1, -120.2 kJ∙mol-1 and -181.2 kJ∙mol-1, respectively, and clearly show the effect of fluorination on hydrogen bond strength in amine-fluoride systems. The change in enthalpy and entropy for the clustering of methanol to NF2H∙∙∙F- to form the fluoride bound dimer of methanol and difluoramine has been measured via high pressure mass spectrometry to be -68.3 kJ∙mol-1 and -90.5 J∙K-1∙mol-1. These values are in excellent agreement with the calculated analogues, -70.9 kJ∙mol-1 and -88.5 J∙K-1∙mol-1. Finally, an examination of the thermochemical properties associated with the formation of a hydrogen bond linkage between protic solvents and deprotonated amino acids has been performed. In addition to observations of the effect of side chain substitution, a comparison between measured and calculated properties has provided insight into the thermochemical effects arising from the isomeric nature of this clustering system. A new theoretical model describing the impact of a distribution of isomers on thermochemical measurements made via high pressure mass spectrometry is given. When this new model was applied, and the distribution of isomers correctly accounted for, the measured values of 〖∆H〗^°, 〖∆S〗^° and 〖∆G〗_298^° consistently agreed, to a very high degree of accuracy, with those predicted by MP2(full)/6-311++G(d,p)//B3LYP/6-311++G(d,p) calculations. As well, IR spectra for the clustering of deprotonated glycine with ROH have been calculated and analyzed to demonstrate the ability of techniques such as IRMPD to identify the presence of a distribution of isomers.

Insight into the effect of secondary interactions, fluorination, as well as substituent effects on strong ionic hydrogen bonds has been acquired through studies of FHF-, NFnH3-n•••F- (n = 0..2) and [M-H]- (M = Glycine, Alanine, Valine, Serine) clustered with ROH (R = H, CH3, C2H5). Excellent agreement was observed between thermochemical values obtained from high pressure mass spectrometry measurements and those predicted from MP2(full)/6-311++G(d,p)//B3LYP/6-311++G(d,p) calculations. In the examination of the clustering of FHF-, a strong correlation between the hydrogen bond strength and the gas phase acidity of the solvent was observed. In addition, several interesting observations on various structural and thermochemical properties were made for each of the three solvents. Upon formation of clusters with water, it was found that the large entropic advantage of one particular structure, which was not the most enthalpically favored, was significant enough to make it the predominant species within the ion source. In the case of methanol solvation, no evidence of secondary interaction of the methyl group and any other moiety could be found. The structural details revealed from calculations of the ethanol-solvated clusters indicate that secondary interactions between the terminal methyl group and FHF- had an impact on the length of both the FHF and OHF bonds present. In an attempt to gain insight into the effects of fluorination on hydrogen bonding, clusters of NFnH3-n (n = 0..2) and F- have been computationally investigated. The hydrogen bond energy in NH3∙∙∙F-, NFH2∙∙∙F- and NF2H∙∙∙F- were calculated to be -67.9 kJ∙mol-1, -120.2 kJ∙mol-1 and -181.2 kJ∙mol-1, respectively, and clearly show the effect of fluorination on hydrogen bond strength in amine-fluoride systems. The change in enthalpy and entropy for the clustering of methanol to NF2H∙∙∙F- to form the fluoride bound dimer of methanol and difluoramine has been measured via high pressure mass spectrometry to be -68.3 kJ∙mol-1 and -90.5 J∙K-1∙mol-1. These values are in excellent agreement with the calculated analogues, -70.9 kJ∙mol-1 and -88.5 J∙K-1∙mol-1. Finally, an examination of the thermochemical properties associated with the formation of a hydrogen bond linkage between protic solvents and deprotonated amino acids has been performed. In addition to observations of the effect of side chain substitution, a comparison between measured and calculated properties has provided insight into the thermochemical effects arising from the isomeric nature of this clustering system. A new theoretical model describing the impact of a distribution of isomers on thermochemical measurements made via high pressure mass spectrometry is given. When this new model was applied, and the distribution of isomers correctly accounted for, the measured values of 〖∆H〗^°, 〖∆S〗^° and 〖∆G〗_298^° consistently agreed, to a very high degree of accuracy, with those predicted by MP2(full)/6-311++G(d,p)//B3LYP/6-311++G(d,p) calculations. As well, IR spectra for the clustering of deprotonated glycine with ROH have been calculated and analyzed to demonstrate the ability of techniques such as IRMPD to identify the presence of a distribution of isomers.

Effect of Na2CO3 on formation of hexagonal boron nitride (h-BN) by carbothermic method has been studied by subjecting B2O3-C and Na2CO3-added B2O3-C mixtures to N2 (g) atmosphere. Na2CO3 amount in the mixtures was changed in the range of 0-40 wt. %. Time and temperature were used as experimental variables. Reaction products were analyzed by XRD and scanning electron microscope. Na2CO3 was found to increase both the amount and the particle size of h-BN similar to CaCO3 [1]. Na2CO3 was found to be less effective than CaCO3 in increasing the amount while it was more effective than CaCO3 in increasing the particle size of h-BN forming.

Relative densities and heat capacity ratios have been measured for selected aqueous systems. These measurements have been used to calculate apparent molar volumes and heat capacities. Densities of aqueous sodium bromide have been measured from 374 to 522 K and 10.00 to 30.00 MPa using a recently developed high temperature and pressure vibrating tube densimeter. These data have been used to test the utility of an automated high temperature and pressure densimetric data analysis program. Apparent molar volumes and heat capacities of several aqueous rare earth sulphate systems at 298.15 K and 0.10 MPa have been reported, and discussed in terms of ionic contributions. Single ion partial molar volumes and heat capacities for aqueous trivalent rare earth species have been estimated in a review of apparent molar data from the literature and through the use of semi-empirical Debye-Huckel equation. These singles ion properties have subsequently been used to estimate the single ion properties of the monosulphate and disulphate rare earth complex species. Rigorous relaxation calculations are presented in a discussion of apparent molar heat capacities, where relaxation contributions are shown to be negative. Apparent molar volumes and densities for aqueous L-histidine, L-phenylalanine, L-tyrosine, L-tryptophan, and L-dopa have been used to estimate reported partial molar properties have been added to several reported properites for other amino acids and peptides to construct an additivity scheme that utilises the revised Helgeson, Kirkham, and Flowers (HKF) equations of state for neutral organic species. A volumetric study of aqueous glycine, L-serine, and glyclylglycine has been conducted at temperatures from 298 K to 423 K and pressures from 0.10 to 30.00 MPa. These data have been used to evaluate HKF coefficients in a discussion of peptide stability at elevated temperatures and pressures. / xvii, 220 leaves : ill. ; 28 cm.

Sous conditions de fort déséquilibre thermodynamique, les populations des états internes émettant dans le VUV et l’infrarouge ne suivent plus une distribution de Boltzmann mais sont contrôlés par des processus collisionels et radiatifs. Nous avons développé un nouveau modèle collisionel-radiatif (CR) comprenant les mécanismes d’excitation et d’ionisation par impact d’électrons et de particules lourdes, ainsi que les transitions radiatives. Une revue exhaustive des diverses données expérimentales et théoriques nous a conduit à sélectionner les formulations les plus appropriées. Les transitions radiatives on été traitées via le concept de facteur d’échappement, égal à 0 pour les transitions dans le VUV, et à 1 pour les transitions dans l’infrarouge, en accord avec les récents calculs de la littérature. Nous avons interfacé notre modèle CR avec un code d’écoulement et un code spectral en vue de prédire les luminances récemment mesurées dans le tube à choc EAST de la NASA. Nous avons choisi deux conditions représentatives d’une rentrée hypervéloce sur Terre: V∞=10.6 et 11.12 km/s, à pression p∞=13.3 Pa. Nous avons comparé les densités d’électrons prédites par le modèle d’écoulement avec celles extraites des caméras CCD et avons obtenu un excellent accord, validant de fait le modèle d’ionisation et nous permettant de déterminer la position du choc. Ensuite, nous avons comparé les profils de luminance prédits par le modèle CR mesurés dans le VUV et l’infrarouge avec les données expérimentales et avons obtenu un excellent accord. Nous avons ainsi montré que les collisions par impact de particules lourdes sont cruciales et doivent être déterminés précisément en vue de prédire le flux radiatif dans le VUV, lequel peut représenter 60% du flux total reçu par le vaisseau spatial lors de sa rentrée dans l’atmosphère terrestre. / Under nonequilibrium, the populations of the electronic states that strongly radiate in the VUV and IR are no longer governed by a Boltzmann distribution but rather by collisional and radiative processes. A new collisional-radiative (CR) model was developed including the key processes chief among them electron-impact excitation and ionization, heavy-particle impact excitation and bound-bound transitions. A comprehensive review of the available experimental and theoretical reaction rates governing these processes was undertaken to produce a reliable set of rates. The bound-bound radiative mechanisms were treated using the escape factor concept, set to zero for VUV lines and set to one for infrared lines, in accordance with literature results. The CR model was interfaced with the a flowfield solver and with a radiation code to predict the nonequilibrium VUV and IR radiation spectra very recently measured in the EAST facility at NASA Ames Research Center. Two shock-tube conditions representative of a Lunar return reentry trajectory were selected: V∞=10.6 and 11.12 km/s, both at p∞=13.3 Pa. The electron number density profiles inferred from experiments were compared with the prediction of the flowfield model, showing excellent agreement in trend and absolute magnitude for both freestream conditions, and thus validating the ionization model and providing a way to accurately locate the shock front in the CCD images. Then, the experimental intensity profiles were compared with the prediction of the CR model. Excellent agreement between predicted and measured intensity profiles was obtained for both freestream conditions, when adjusting the heavy-particle impact excitation rate constants of Park (1985), suggesting that the nonequilibrium peak intensities observed in the VUV and IR spectral ranges are controled by heavy-particle impact processes.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2018-09-24T11:02:42Z No. of bitstreams: 2 Dissertação - Nayara Regina Bispo Assis - 2018.pdf: 4706402 bytes, checksum: bc4aff9973f2874ecdb3edc6374f50a6 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-09-24T11:16:38Z (GMT) No. of bitstreams: 2 Dissertação - Nayara Regina Bispo Assis - 2018.pdf: 4706402 bytes, checksum: bc4aff9973f2874ecdb3edc6374f50a6 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-09-24T11:16:39Z (GMT). No. of bitstreams: 2 Dissertação - Nayara Regina Bispo Assis - 2018.pdf: 4706402 bytes, checksum: bc4aff9973f2874ecdb3edc6374f50a6 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-08-23 / The general objective of this work was to analyze the approach of Citizenship and Scientific Literature in the contents of thermochemistry in the textbooks of Chemistry of the National Program of Didactic Book (PNLD) from 2008 to 2018. This research had as premise a qualitative methodological approach, of the type study of case. For data collection, bibliographical and documentary analysis and the treatment of data in a posteriori categories were used. The categories found were: historical perspective of Science; scientific literacy; Education for environmental citizenship and the multicultural approach. The results were obtained through the observation of the data extracted from the textbooks. It was possible to infer that the historical content was approached very superficially, most of the books were destined to small boxes with images of scientists, very few historical texts and lack of activities that rescued the content. In environmental issues, the works of PNLD 2008 were not addressed with such emphasis we have been the predominance of conservative environmental education. In this way, the problems are presented in a synthetic and partial way. As for the PNLD 2012, 2015 and 2018 books, the approach was more intensified; more texts, issues and activities were found to help promote sustainable development. The category of literacy was examined the predominance of texts written by the production agents of the textbook and few texts of varied sources and textual genres. The multicultural category needs to be more explored, because, if there were predominance of images of white men in contrast few of black men, very few images of women and absence of Indians. It still needs more punctual discussions that better emphasize the genres in their different pluralities, because it is a necessity that the issues can be defended in all the areas. Thus, the observations collected were compared to the authors cited as a bibliographical contribution indicating that despite the advances some Chemistry books throughout the PNLD still do not contemplate the formation for citizenship. / O objetivo geral deste trabalho foi analisar a abordagem da Cidadania e Letramento Científico nos conteúdos de termoquímica nos livros didáticos de Química do Programa Nacional do Livro Didático (PNLD), de 2008 a 2018. Esta pesquisa teve como premissa uma abordagem metodológica qualitativa, do tipo estudo de caso. Para a coleta de dados, foram utilizadas as análises bibliográfica e documental; o tratamento de dados em categorias deu-se a posteriori. As categorias encontradas foram: perspectiva histórica da Ciência; letramento científico; Educação para cidadania ambiental e a abordagem multicultural. Os resultados foram obtidos por meio da observação dos dados extraídos dos livros didáticos. Foi possível inferir que o conteúdo histórico é abordado de forma muito superficial; na maioria dos livros são destinados pequenos boxes com imagens de cientistas, muito poucos textos históricos e falta de atividades que resgatassem o conteúdo. Nas questões ambientais, as obras do PNLD 2008 não foram abordadas com tanta ênfase; temos que houve o predomínio da educação ambiental conservadora. Desta forma, os problemas são apresentados de maneira sintética e parcial. Já nos livros do PNLD 2012, 2015 e 2018, a abordagem foi mais intensificada; foram encontrados mais textos, questões e atividades que auxiliassem na promoção do desenvolvimento sustentável. Na categoria do letramento foi examinada a predominância de textos escritos pelos agentes de produção do livro didático e poucos textos de fontes e gêneros textuais variados. A categoria multicultural necessita ser mais explorada, pois, encontrou-se predomínio de imagens de homens brancos e, em contrapartida, poucas de homens negros, muito poucas imagens da mulher e ausência de índios. Verifica-se que ainda é preciso discussões mais pontuais que ressaltem melhor os gêneros nas suas diferentes pluralidades, pois é uma necessidade que as questões possam ser defendidas em todas as áreas. Dessa forma, as observações coletadas foram comparadas aos autores citados como aporte bibliográfico, indicando que, apesar dos avanços alguns livros de Química ao longo do PNLD, ainda não é contemplada a formação para a cidadania.

Orientador: Claudio Airoldi / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-08T11:57:09Z (GMT). No. of bitstreams: 1 Melo_JulioCesarPerinde_M.pdf: 1442179 bytes, checksum: c934efefecaccf6b884d1b01f49ce162 (MD5) Previous issue date: 2007 / Resumo: A celulose é um biopolímero abundante que apresenta considerável inércia química. A modificação deste polissacarídeo baseia-se nas reações de suas hidroxilas, as quais determinam a química e a estrutura deste carboidrato. A celulose foi quimicamente modificada por um procedimento ainda não descrito na literatura, no qual a celulose é adicionada ao anidrido fundido sem o uso de solventes. O grau de modificação dos derivados foram analisados por análise elementar de CHN e pela titulação dos grupos ácidos, obtendo-se 2,82 ± 0,05, 3,07 ± 0,05 e 2,99 ± 0,07 mmol g para CelX [X = anidrido malêico (AM), anidrido succínico (AS) e anidrido ftálico (AF), respectivamente]. A banda em 1717 cm referente ao estiramento de ácido carboxílico comprovando o sucesso das reações. Através da técnica de ressonância magnética nuclear de carbono-13 no estado sólido comprovou-se a presença de ácido e éster nos materiais pelo sinal em torno de 170 ppm. As curvas, termogravimétricas bem como suas derivadas, mostraram as resistências térmicas dos materiais até 530 K; o material CelAF apresenta a perda de um grupo ácido benzóico no intervalo de 459 a 489 K. Os difratogramas de raios x mostraram a permanência da estrutura cristalina da celulose, sugerindo que as reações ocorrem nas regiões de baixa cristalinidade, regiões superficiais e regiões mais internas. Os materiais foram testados frente a capacidade de adsorção de metais e os valores foram: para cobalto 1,75, 2,46 e 2,43 mmol g e para níquel 2,40, 2,46 e 2,26 mmol g para CelAM, CelAS e CelAF, respectivamente. Os efeitos interativos metal/centro básico foram determinados através de titulações calorimétricas cujos resultados permitiram a obtenção das grandezas termodinâmicas. Os valores entálpicos são baixos e endotérmicos, com valores entrópicos positivos, mostrando a espontaneidade da reação através dos valores de energia livre de Gibbs. Os materiais foram preparados por um procedimento fácil, rápido e sem o uso de solventes. Estes são pré-requisitos básicos na indústria e assim, estes biopolímeros modificados quimicamente, apresentam-se como candidatos no emprego de remoção de metais em efluentes / Abstract: Cellulose is a widely available biopolymer in nature and its draws considerable chemical interest due its various useful applications. The polysaccharide modification is primarily based on their hydroxyl group reactivity, which determines the carbohydrate chemistry and their related structures. The chemical modification of cellulose was carried out in a solvent-free procedure in which the cellulose was added to the molten anhydride. This procedure has not been previously reported in the literature. The degree of substitution was calculated from elemental C,H,N analysis results and acid group titration process and the results were 2.82±0.05, 3.07±0.05 and 2.99±0.07 mmol g for CelX (X=maleic anhydride (MA), succinic anhydride (SA) and phthalic anhydride (PA), respectively. The FTIR spectra of the materials showed band at 1717 cm assigned to carbonyl stretching frequencies of carboxyl and ester groups. Additionally, C NMR spectra of the materials showed peaks around 170 ppm related to the presence of carbonyl carbon, thus confirming the successful completion of reactions by adopted synthesis procedure. Analysis of TG and its derivative curve showed the relative thermal stabilities of materials up to 530 K. CelPA was degradable in the temperature range 459 ¿ 489 K with loss of benzoic acid. X-ray diffraction pattern of the materials indicated the cellulose structure remained intact under the rigorous reaction condition, which suggests the occurrence of reactions mainly at low crystalline and superficial regions. Meal adsorption capacities were for Co:1.75, 2.46, 2.43 and for Ni: 2.40, 2.46 2.26 mmol g, respectively, for CelMA, CelSA, and CelPA, respectively. Interactions of metal-basic centers were determined in a calorimetric titration process. The interaction resulted in an endothermic process with low enthalpy values. The positive entropy and the calculated Gibb¿s free energy value indicated the spontaneity of the reaction process. In conclusion, all materials were prepared adopting an easy, rapid and solvent-free procedure, which confirms the requirements of a cost effective and industrial viable process. In additin, the method supports the principles of green-chemistry / Mestrado / Quimica Inorganica / Mestre em Química