No description available.

The low temperature phase behavior of the system H2O-NaCl-FeCl2 was examined using synthetic fluid inclusions. Experiments were conducted along the 5 wt% NaCl (relative to the total solution) pseudobinary, with FeCl2 concentrations varying from 2 to 33 wt%, and along the pseudobinary defined by mixing known amounts of FeCl2-4H2O with a 5 wt% NaCl solution, with final FeCl2 concentrations varying from 0 to 29 wt%. Synthetic fluid inclusions in quartz were prepared in cold-seal pressure vessels at 500 degrees C - 800 degrees C and 2 or 3 kilobars. The fO2 conditions were controlled by the Ni-NiO equilibrium curve. The liquid released from the capsule upon opening was initially colorless, but turned yellow-orange after contact with atmospheric O2. The clear color is characteristic of ferrous iron solutions, whereas the yellow-orange color is consistent with the presence of Fe3+ in solution. This color change suggested that the unopened capsules initially contained ferrous iron in solution, which oxidized to ferric iron when exposed to the atmosphere. Borisenko (1977) reported a eutectic temperature of -37 degrees C for the system H2O-NaCl-FeCl2. In this study, it was not possible to verify this temperature due to the persistence of a metastable liquid down to liquid N2 temperatures (~-196 degrees C). Final ice melting temperatures were obtained for concentrations less than 24 wt% FeCl2 and show a decrease in temperature with increase in FeCl2 concentration. For more concentrated solutions, final melting temperatures could not be obtained because the samples could not be frozen. / Master of Science

A comprehensive study was conducted on the effects of de-icer and anti-icer chemicals on cement-based materials. Portland cement mortars and concretes were exposed to over 16 chloride-based and non-chloride-based generic and commercial products and changes in cement-based material properties were measured. Deleterious chemical actions of several types of these products on cement-based materials were observed, departing from the well-known position that attributes the concrete damage from such salts mainly to physical actions under freezing and thawing exposure. Independent of freezing and thawing exposure, mortars and concretes exposed to concentrated calcium chloride and magnesium chloride solutions were found to undergo severe deterioration whereas those exposed to sodium chloride did not. The mechanisms of deterioration are complex with factors such as concentration, temperature, and availability of calcium hydroxide playing important roles. It was found that the formation of calcium oxychloride of the form 3Ca(OH)2.CaCl2.12H2O, and the 3- and 5-form magnesium oxychloride, 3Mg(OH)2.MgCl2.8H2O and 5Mg(OH)2.MgCl2.8H2O, were the main causes for the severe deterioration, and to a lesser extent brucite, gypsum, and magnesium silicate hydrate (M-S-H). The instability of these oxychloride compounds when subjected to conditions normally encountered in sample preparation is suggested as the reason why field investigations have failed to relate distressed concrete to chemical attack by such de-icer and anti-icer chemicals. Concentrated solutions of calcium magnesium acetate were also found to be harmful to cement-based materials by dissolution of calcium hydroxide and formation of calcium acetate hydrate, whereas low concentrated solutions tended to cause slow deterioration by magnesium attack forming brucite, gypsum, and M-S-H. Potassium acetate chemicals did not cause significant deterioration in mortars when these products were diluted (25% by mass), but undiluted products (50% by mass) caused considerable distress in concrete specimens. The combined effect of chemical attack impairing concrete mechanical properties and subsequent salt scaling damage was proposed as the most likely mechanisms of field deterioration.

A comprehensive study was conducted on the effects of de-icer and anti-icer chemicals on cement-based materials. Portland cement mortars and concretes were exposed to over 16 chloride-based and non-chloride-based generic and commercial products and changes in cement-based material properties were measured. Deleterious chemical actions of several types of these products on cement-based materials were observed, departing from the well-known position that attributes the concrete damage from such salts mainly to physical actions under freezing and thawing exposure. Independent of freezing and thawing exposure, mortars and concretes exposed to concentrated calcium chloride and magnesium chloride solutions were found to undergo severe deterioration whereas those exposed to sodium chloride did not. The mechanisms of deterioration are complex with factors such as concentration, temperature, and availability of calcium hydroxide playing important roles. It was found that the formation of calcium oxychloride of the form 3Ca(OH)2.CaCl2.12H2O, and the 3- and 5-form magnesium oxychloride, 3Mg(OH)2.MgCl2.8H2O and 5Mg(OH)2.MgCl2.8H2O, were the main causes for the severe deterioration, and to a lesser extent brucite, gypsum, and magnesium silicate hydrate (M-S-H). The instability of these oxychloride compounds when subjected to conditions normally encountered in sample preparation is suggested as the reason why field investigations have failed to relate distressed concrete to chemical attack by such de-icer and anti-icer chemicals. Concentrated solutions of calcium magnesium acetate were also found to be harmful to cement-based materials by dissolution of calcium hydroxide and formation of calcium acetate hydrate, whereas low concentrated solutions tended to cause slow deterioration by magnesium attack forming brucite, gypsum, and M-S-H. Potassium acetate chemicals did not cause significant deterioration in mortars when these products were diluted (25% by mass), but undiluted products (50% by mass) caused considerable distress in concrete specimens. The combined effect of chemical attack impairing concrete mechanical properties and subsequent salt scaling damage was proposed as the most likely mechanisms of field deterioration.

The excessive intake of sodium is related to hypertension and consequently to an increased risk of cardiovascular diseases. The consumption of sodium exceeds the nutritional recommendations in most industrialized countries. Sodium chloride is the main source of sodium in the diet. In developed countries, meat products are one of the major sources of sodium in the form of sodium chloride. This study was aimed at producing a Hamburg-type dry fermented sausage with low sodium levels, but keeping the traditional characteristics appreciated in this product. For this purpose, we evaluated potassium chloride and magnesium chloride as partial substitutes for sodium chloride (45, 50 and 55% substitution on mass basis). The pH, temperature, weight loss, lactic acid bacteria counts, aerobic mesophilic bacteria counts, Salmonella, total and fecal coliforms were assessed during and after the production of dry fermented sausages. At the end of the production the sausages were also submitted to proximate composition, mineral, water activity, objective color and sensory analyses. Results indicate that the replacement of 45 to 55% NaCl with KCl or MgCl2 yields Hamburg-type dry fermented sausages that have physico-chemical and microbiological characteristics suitable for trading. These products were within the Brazilian legal limits for moisture, protein, fat, water activity, coliforms and Salmonella. Among the formulations developed, the highest moisture was found in MgCl2-containing sausages, which also had the lowest contents of ash and chloride. Water activity was lower in the sausages with KCl. Although the replacement of 45% NaCl with KCl or MgCl2 have improved the sensory characteristics of Hamburg-type dry fermented sausage, the replacement of 50% NaCl with KCl and 55% NaCl with MgCl2 also appear to be viable, since they yielded products with sensory acceptability similar to that of control. / A ingestão excessiva de sódio está sendo relacionada com hipertensão e conseqüentemente com o aumento do risco de doenças cardiovasculares. O consumo de sódio excede a recomendação nutricional na maioria dos países industrializados. A principal fonte de sódio na dieta é o cloreto de sódio. Em países industrializados, os produtos cárneos são uma das principais fontes de sódio na forma de cloreto de sódio. Com o objetivo de produzir um salame tipo hamburguês com diminuição dos riscos associados ao sódio, mantendo as características já tradicionalmente apreciadas neste produto, no presente estudo avaliou-se a substituição do cloreto de sódio, em diferentes níveis (45, 50 e 55%), por cloreto de potássio e por cloreto de magnésio. Foram avaliados os parâmetros de pH, temperatura, perda de peso, contagens de bactérias ácido láticas, microrganismos mesófilos aeróbios, Salmonella, coliformes fecais e coliformes totais durante a fabricação e ao final da produção dos salames. Ao final da produção dos salames foram avaliados ainda a composição centesimal, minerais, atividade de água, cor objetiva e características sensorais. Os resultados do presente estudo indicam que a substituição de 45 a 55% do NaCl de salame tipo hamburguês por KCl ou MgCl2 (em base de massa) resulta em produtos com características físico-químicas e microbiológicas adequadas para a comercialização, permanecendo dentro dos padrões legais do Brasil para teores de umidade, proteína, gordura, atividade de água, contagens de coliformes e ausência de Salmonella. Dentre as formulações avaliadas, maior umidade foi encontrada naquelas contendo MgCl2, que também apresentaram menores valores de cinzas e cloretos. Quanto aos valores de atividade de água, estes foram menores nas formulações com KCl. Ainda que as substituições de 45% do NaCl por KCl ou MgCl2 tenham melhorado as características sensoriais do salame tipo hamburguês, as substituições de 50% do NaCl por KCl e de 55% do NaCl por MgCl2 também parecem ser viáveis, uma vez que resultaram em produtos com aceitação sensorial semelhante a do controle.

Submitted by Marilene Donadel (marilene.donadel@unioeste.br) on 2017-12-01T22:57:34Z No. of bitstreams: 1 Juliana_Dotto_2013.pdf: 2822116 bytes, checksum: 3b8be919381051b7c1e0d2252f604aed (MD5) / Made available in DSpace on 2017-12-01T22:57:34Z (GMT). No. of bitstreams: 1 Juliana_Dotto_2013.pdf: 2822116 bytes, checksum: 3b8be919381051b7c1e0d2252f604aed (MD5) Previous issue date: 2013-02-19 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This study evaluated the efficiency of organic coagulants like seeds of Moringa oleifera Lam extracted in saline solutions of sodium chloride and potassium chloride1,0 (MO-NaCl and MO-KCl, respectively) and inorganic coagulants like aluminum sulfate and ferric chloride to the treatment of textile wastewater. Initially, it has been evaluated the best pH for each coagulant studied to then optimize the concentration of the coagulants and settling time. For this finality, it has been used velocity of rapid mixing (VMR) and slow (VML) at 100 rpm and 20 rpm, respectively and time of rapid mixing (TMR) and slow (TML) for 2 minutes and 20minutes, respectively. The parameters analyzed were pH after treatment, absorbance at a wavelength of maximum absorption for each dye present in the wastewater (Procion Orange HER and Procion Red HE-7B), color, turbidity and COD. In the test for optimization of coagulants concentration and settling time, also was evaluated the amount of sludge generated at each concentration studied. Thus, organic coagulants showed superior results in comparison with inorganic coagulants in the treatment of textile wastewater, especially MO-KCl, which showed removal of 86,8% for absorbance of the dye Procion Orange HER, 75,65% for absorbance of the dye Procion Red HE-7B, 70,67%forcolor, 85,97% for COD and 64,07% for turbidity. Based on the results obtained, MO-KCl presented a promising coagulant in the treatment of textile wastewater. / O presente estudo avaliou a eficiência dos coagulantes orgânicos sementes de Moringa oleifera lam extraídas em soluções salinas de cloreto de sódio e cloreto de potássio 1,0 (MO-NaCl e MO-KCl) respectivamente, além dos inorgânicos sulfato de alumínio e cloreto férrico no tratamento de água residuária têxtil. Inicialmente, avaliou-se o melhor pH de trabalho para cada coagulante estudado, para, em seguida, otimizar a concentração do coagulante e o tempo de sedimentação. Para isto, utilizou-se velocidade de mistura rápida (VMR) e lenta (VML) de 100 rpm e 20 rpm respectivamente, e tempo de mistura rápida (TMR) e lenta (TML) de 2 minutos e 20 minutos, respectivamente. Os parâmetros analisados foram pH após tratamento, absorbância no comprimento de onda máximo de cada corante presente na água residuária (Laranja Procion HER e Vermelho Procion HE-7B), cor, turbidez e DQO. Além destes, no teste para otimização da concentração de coagulante e tempo de sedimentação, avaliou-se a quantidade de lodo gerado em cada concentração estudada. Assim, os coagulantes orgânicos apresentaram resultado superior aos inorgânicos no tratamento da água residuária têxtil, com destaque para a MO-KCl, que apresentou remoção de 86,8% para absorbância do corante Laranja Procion HER, 75,65% para absorbância do corante Vermelho Procion HE-7B, 70,67% para cor aparente, 85,97% para DQO e 64,07% para turbidez. Com base nos resultados obtidos a MO-KCl pode ser considerada um coagulante promissor para o tratamento da água residuária têxtil.

No description available.

Industrial activities of mankind are feared to damage the environment irretrievably. Especially the release of huge amounts of harmful gases causes concern. In this regard the environmental pollution caused by the one billion motor vehicles on earth is particularly important. The platinum-group metals (PGM) are well known for their catalytic activity. They are used extensively for reducing the amounts of hydrocarbons, carbon monoxide and nitrogen oxides from the exhausts gas emitted by automobiles. In 2012 20% of platinum and 27% of palladium produced were used in the manufacture of catalytic converters. With the increasing use of PGM-containing autocatalysts, the reclaiming of PGMs from spent catalysts has become essential. Particularly attractive hydrometallurgical methods are those based on the use of halide ions e.g. sodium chloride, as complexing agent in conjunction with nitric acid as oxidant. The chemical reactions between mixtures of aluminium chloride and nitric acid have been studied, but the electrochemical reactions have received little attention. The research reported in this dissertation is aimed at providing data relating to the electrochemical behaviour of platinum in mixtures of aluminium chloride and nitric acid. The construction of Pourbaix diagrams of platinum in chloride environments confirmed that the stable chloro-complexes [PtCl4]2- and PtCl6]2-, as well as platinum oxides (PtO and PtO2) could play a role under the experimental conditions employed in this study. From the thermodynamic results it can be concluded that the systems deserving consideration favour high chloride concentrations and high temperatures. Notable anodic reactions found were the adsorption of chloride on the platinum surface and the gradual formation of [PtCl6]2-, followed by the formation of platinum oxides at 1.00 to 1.01 V. The results show that anodic currents diminished with lower chloride concentrations. A seemingly anomalous anodic behaviour at 35 °C and 45 °C could be explained in terms of a competition between platinum oxide formation and the formation of platinum chloro-complexes. Evidence for the following cathodic reduction reactions was found: hydrogen evolution, reduction of dissolved oxygen to hydrogen dioxide (-1.3 V SHE), nitrate ion reduction to nitrite ions (-0.01 V SHE), nitrite ion reduction to nitric oxide (-0.85 V SHE) and reduction of PtO and PtO2 to Pt (at -1.00 V and 1.01 V SHE, respectively). A brief study was undertaken in an attempt to relate the electrochemical results to the leaching of platinum from a virgin automotive exhaust catalyst. The recovery was low for mixtures with low chloride concentrations, which could be expected from the electrochemical polarisation curves obtained in electrolytes with different chloride concentrations. The maximum platinum recovery attained, was 60% at 45 °C in a mixture containing 0.6 M AlCl3 and 0.9 M HNO3. / MSc (Chemistry), North-West University, Potchefstroom Campus, 2014

Industrial activities of mankind are feared to damage the environment irretrievably. Especially the release of huge amounts of harmful gases causes concern. In this regard the environmental pollution caused by the one billion motor vehicles on earth is particularly important. The platinum-group metals (PGM) are well known for their catalytic activity. They are used extensively for reducing the amounts of hydrocarbons, carbon monoxide and nitrogen oxides from the exhausts gas emitted by automobiles. In 2012 20% of platinum and 27% of palladium produced were used in the manufacture of catalytic converters. With the increasing use of PGM-containing autocatalysts, the reclaiming of PGMs from spent catalysts has become essential. Particularly attractive hydrometallurgical methods are those based on the use of halide ions e.g. sodium chloride, as complexing agent in conjunction with nitric acid as oxidant. The chemical reactions between mixtures of aluminium chloride and nitric acid have been studied, but the electrochemical reactions have received little attention. The research reported in this dissertation is aimed at providing data relating to the electrochemical behaviour of platinum in mixtures of aluminium chloride and nitric acid. The construction of Pourbaix diagrams of platinum in chloride environments confirmed that the stable chloro-complexes [PtCl4]2- and PtCl6]2-, as well as platinum oxides (PtO and PtO2) could play a role under the experimental conditions employed in this study. From the thermodynamic results it can be concluded that the systems deserving consideration favour high chloride concentrations and high temperatures. Notable anodic reactions found were the adsorption of chloride on the platinum surface and the gradual formation of [PtCl6]2-, followed by the formation of platinum oxides at 1.00 to 1.01 V. The results show that anodic currents diminished with lower chloride concentrations. A seemingly anomalous anodic behaviour at 35 °C and 45 °C could be explained in terms of a competition between platinum oxide formation and the formation of platinum chloro-complexes. Evidence for the following cathodic reduction reactions was found: hydrogen evolution, reduction of dissolved oxygen to hydrogen dioxide (-1.3 V SHE), nitrate ion reduction to nitrite ions (-0.01 V SHE), nitrite ion reduction to nitric oxide (-0.85 V SHE) and reduction of PtO and PtO2 to Pt (at -1.00 V and 1.01 V SHE, respectively). A brief study was undertaken in an attempt to relate the electrochemical results to the leaching of platinum from a virgin automotive exhaust catalyst. The recovery was low for mixtures with low chloride concentrations, which could be expected from the electrochemical polarisation curves obtained in electrolytes with different chloride concentrations. The maximum platinum recovery attained, was 60% at 45 °C in a mixture containing 0.6 M AlCl3 and 0.9 M HNO3. / MSc (Chemistry), North-West University, Potchefstroom Campus, 2014

No description available.