Open and throughfall precipitation samples were collected at Haliburton Forest for a total of nine events from July – November of 2009. The following species were analyzed quantitatively: NO3-, SO42-, Cl-, HCOO-, C2O42-, NH4+, Na+, K+, Ca2+, and Mg2+. Wet deposition inputs to the system were quantified and the sources of wet-deposited species were probed. The throughfall method was employed to quantify inputs to the forest floor and probe canopy-precipitation interactions. Leaf wash samples at three heights aided in the interpretation of throughfall data and allowed for an examination of vertical profiles of dry deposition to the canopy. Results suggest possible nitrate foliar leaching during the growing season, although this appears to cease during senescence. This finding supports previous evidence that Haliburton Forest has shifted from nitrogen-limitation toward nitrogen-saturation and estimated total atmospheric N inputs to the system are close to the proposed critical load of 10 kg N ha-1 yr-1.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Thesis (doctoral)--Göteborgs universitet, 1983. / Extra t.p. with thesis statement inserted. Bibliography: p. 127-130.

CAPES / No presente trabalho foi estudado a influência do pH final de precipitação, tempo e modo de agitação, onde foi avaliado o modo de agitação mecânico e por ultrassom na obtenção do dióxido de cério. Para a otimização do processo, fez-se o uso de uma ferramenta chamada Planejamento Fatorial, na qual, a partir dos dados experimentais fornece uma estimativa para melhores condições levando em consideração uma variável resposta. As variáveis resposta adotadas no trabalho foram Temperatura Final de Decomposição e Tamanho médio de Partícula. O dióxido de cério foi obtido a partir da decomposição térmica do complexo tris(8-hidroxiquinolinato)cério(III), que foi sintetizado por meio da técnica de precipitação química, empregando o quelante 8-hidroxiquinolina e caracterizado por meio de espectroscopia na região do infravermelho (FTIR) e microscopia eletrônica de varredura (MEV), foi também realizado o estudo do comportamento térmico do complexo, com auxílio da térmogravimetria (TG), térmogravimetria derivada (DTG) e análise térmica diferencial (DTA); o dióxido de cério foi caracterizado por meio de FTIR e difratometria de raios X (DRX), a partir dos dados de DRX foi calculado o tamanho médio de partículas com o auxílio da fórmula de Scherrer. O Planejamento Fatorial indicou para variável resposta Temperatura Final de Decomposição, que para ambos modos de agitação as melhores condições de síntese são para maiores valores de pH´s finais de precipitação, o tempo de agitação não teve influência significativa a 95% de significância, dentro da faixa estudada. Para variável resposta Tamanho Médio de Partícula, o teste mostrou para os dois modos de agitação, que nenhuma das variáveis teve influência significativa a 95% de significância, dentro da faixa estudada, atribuindo então o tamanho médio de partículas somente ao método de síntese. Não houve diferença significativa entre os modos de agitação também. / In the present work, it was investigated the influence of the final pH of precipitation, agitation time and mode of agitation, which assessed the mechanical agitation mode and ultrasound to obtain the cerium dioxide. For process optimization, it was used a tool called Planning Factor, which provides an estimative of better conditions, considering a response variable from the experimental data. The responsible variable adopted in this work was Decomposition Final Temperature and Particle Average Size. The cerium dioxide was obtained from the thermal decomposition of the complex tris (8-hydroxyquinolinate) cerium (III), synthesized by chemical precipitation using 8-hydroxyquinolinechelator and characterized by infrared spectroscopy (FTIR) and scanning electronic microscopy (SEM). In addition, it was performed the study of the complex thermal behavior with assistance of thermogravimetry (TG), derivative thermogravimetry (DTG) and differential thermal analysis (DTA); The cerium dioxide was characterized by FTIR and X-ray diffraction (XRD), in which it was based to the determination of the particle average size using Scherrer's formula. The Factorial design pointed out to response variable Decomposition Final temperature that, for both modes of agitation, the best synthesis conditions are for higher values of final pH's precipitation. Also, the stirring time had no significant influence when used the 95% significance studied range. For response variable Average Size, the test pointed out to both ways of stirring, when none of the variables had significant influence at 95% significance within the studied range, assigning the average particle size only to the method of synthesis. Thereby, there was no significant difference between the stirring modes.

Orientadores: Everson Alves Miranda, Pedro de Alcantara Pessoa Filho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-11T18:24:37Z (GMT). No. of bitstreams: 1 Silva_LucimaraLopes_M.pdf: 1727791 bytes, checksum: ee5f8523aa0284257e3f3d3d6955af8c (MD5) Previous issue date: 2008 / Resumo: A precipitação de proteínas com sais é uma etapa de purificação freqüentemente encontrada em bioprocessos. Porém, a necessidade de um tratamento posterior para recuperação do sal e purificação da proteína torna o processo de precipitação com sais convencionais oneroso, além de limitado por questões ambientais. A precipitação com sais voláteis é uma alternativa à precipitação convencional, tendo como principal vantagem a fácil remoção destes sais dos precipitados e efluentes líquidos através da elevação da temperatura ou diminuição da pressão. A indução do "salting-out" de proteínas por estes sais para foi inicialmente investigada por nosso grupo de pesquisa, no entanto, algumas proteínas apresentaram indícios de desnaturação, embora a eficiência da precipitação tenha sido verificada. Para esclarecer esta questão, o objetivo deste trabalho foi avaliar o efeito do sal volátil carbamato de amônio na atividade de cinco enzimas (a-amilase, lisozima, celulase, peroxidase e lipase). Realizaram-se ensaios mantendo-se as enzimas a 4,0ºC por 60 min em soluções 1,0 a 5,0 molal deste sal. Depois da remoção do sal volátil, as massas secas foram dissolvidas em tampões apropriados e estas soluções tiveram sua concentração de proteína e atividade enzimática determinadas. Experimentos similares com sais convencionais também foram feitos, assim como ensaios de precipitação com carbamato de amônio em forças iônicas de 5,0 a 9,0 molal. a-Amilase, lisozima e lipase não tiveram perda de atividade em soluções salinas de 1,0 a 5,0 molal, enquanto que celulase e peroxidase mostraram uma perda de atividade média de 55% e 44%, respectivamente. Análises dos experimentos similares com sulfatos de amônio e de sódio levam à conclusão que estas duas enzimas desnaturaram em presença do sal volátil carbamato de amônio. Os ensaios de precipitação não mostraram nenhuma desnaturação enzimática ou separação de fases para a-amilase e lipase, enquanto que a celulase e a peroxidase precipitaram com alguma perda de atividade. Os balanços de massa e de atividade determinados para estes casos não permitiram uma conclusão definitiva sobre o efeito do sal volátil sobre estas duas enzimas durante a precipitação. / Abstract: Salting-out is a precipitation method frequently found in downstream processing schemes of proteins. However, the need for post-precipitation treatment for salt recovery and final purification of the protein may lead precipitation with conventional salts to be costly and limited for environmental questions. Precipitation with Volatile salts is an alternative to conventional precipitation, presenting as main advantage the easy salt removal from precipitates and liquid effluents by a temperature increase or a pressure reduction. Protein salting-out induction with these salts was pioneered by our research group. However, there was evidence of some denaturation, although efficient precipitation was verified for all proteins studied. To address this question, the objective of this work was to evaluate the effect of ammonium carbamate volatile salt on the specific activity of five enzymes (an a-amylase, a lysozyme, a cellulase complex, a peroxidase and a lipase). Experiments were made with enzymes kept at 4.0ºC for 60 min in solutions 1.0 to 5.0 molal of this salt. After this salt removal, the dried masses were dissolved in appropriate buffers and these solutions had their protein concentration and enzymatic activity measured. Similar experiments with conventional salts were also carried-out which the desalination made by gel permeation columns as well as precipitation assays with ammonium carbamate at ionic strength from 5.0 to 9.0 molal. a-Amylase, lysozyme and lipase did not undergo activity loss in salt solutions from 1.0 to 5.0 molal, whereas cellulase and peroxidase showed an average activity loss of 55% and 44%, respectively. Analysis of similar experiments with ammonium sulfate and sodium sulfate led to the conclusion that these two enzymes denatured with volatile salt ammonium carbamate. The precipitation assays did not show enzyme denaturation or separation of phases for a -amylase and lipase while celullase and peroxidase precipitated with some activity reduction. Mass and activity balances determined for these cases did not allow a definitive conclusion about the effect of ammonium carbamate on these two enzymes during the precipitation. / Mestrado / Desenvolvimento de Processos Biotecnologicos / Mestre em Engenharia Química

Made available in DSpace on 2016-08-19T12:56:42Z (GMT). No. of bitstreams: 1 Dissertacao Irata.pdf: 3144382 bytes, checksum: c6e6615b3bf42aec9baa1245f95165df (MD5) Previous issue date: 2013-10-04 / The oil´s behavior s study, mainly the hard fractions, including asphaltenes and resins, have became extremely important, since the relations between theses constituents during the oil mixing operations and its derivatives may bring several problems with the asphaltenes precipitance. Undesirable, the precipitance may cause pipe s obstruction during the oil s extraction, slowing down the production and rising up the expenses. These facts have motivated this work, that seek determine the influence of temperature and adding particulate materials, in the beginning of asphaltenes precipitation (IP) in models solutions, intending in better characterize the precipitation process, once many of the models applied to determinate the stability and compatibility between these oils, for example, are based on data from the beginning of the precipitation (IP). The technique spectroscopy near Infrared was used to determine the precipitation of asphaltenes in the temperature range from 10 to 30 ºC and with different particle materials (calcareous, sandstone, clay) and a optical microscopy technique determining IP with no temperature variations, contributing as basis for the obtained value, using the NIR technique. The results will designate the temperature variation, with little influences on precipitation, according to the literature. Particle adding (calcareous and clay) have proved to be significant, modifying significantly the asphaltenes precipitation outset, however, the same thing hasn t been noticed with the sandstone particles. / O estudo do comportamento do petróleo, principalmente das frações pesadas, que incluem asfaltenos e resinas, tem se tornado extremamente importante, visto que as relações entre esses constituintes durante as operações de misturas de petróleos e de petróleos e seus derivados, podem trazer inúmeros problemas com a precipitação dos asfaltenos. Indesejável, a precipitação pode ocasionar obstruções de tubulações durante a extração do petróleo, diminuindo a produtividade e aumentando os custos, o que motivou a realização deste trabalho que objetiva determinar a influência da temperatura e da adição de materiais particulados, no início de precipitação (IP) dos asfaltenos em soluções modelos, no intuito de melhor caracterizar o processo de precipitação, uma vez que muitos dos modelos empregados para determinar a estabilidade e a compatibilidade entre petróleos, por exemplo, baseiam-se nos dados do início de precipitação. A técnica de Infravermelho Próximo (NIR) foi utilizada para determinar o início de precipitação (IP) dos asfaltenos na faixa de temperatura de 10 a 30ºC e com diferentes materiais particulados (calcário, arenito e argila) e a técnica de microscopia óptica na determinação do IP servindo como base para os valores obtidos com uso da técnica NIR. Os resultados indicaram variações de temperatura, pouco influentes na precipitação, em acordo com a literatura. As adições de particulados (calcário e argila) mostraram-se significativas, alterando relevantemente o início de precipitação dos asfaltenos, no entanto, o mesmo não foi observado para os particulados de arenito.

Please read the abstract in the section 00front of this document. / Thesis (PhD (Chemistry))--University of Pretoria, 2008. / Chemistry / unrestricted

No description available.

Ion exchange and precipitation technologies were examined for the selective separation and recovery of silver and mercury from COD waste solutions. Batch equilibrium studies were conducted to determine ion exchange selectivity of several commercial and regenerated resins. Resin capacity and metal ion recovery efficiency were evaluated in continuous-flow column studies. Solubility studies were included to determine if metal ions could be selectively separated and included in a treatment regime for removal and recovery of silver and mercury from the waste solution. Reduction of waste volume was also an important consideration for precipitation of metal ions. The results indicated that ionic strength considerations dictate overall treatment and recovery efficiency. Silver and mercury ions were removed by ion exchange while iron and chromium uptake did not occur. Highest removal efficiencies were observed for a mercury-specific resin and an anionic resin compared to cationic or mixed resins. Column capacity was severely impacted by the acidic, high strength, waste solution. Additional studies showed that the solution ionic strength and dissolved solids concentration were more important than solution pH in determining ion exchange preference and column capacity. Reuse of column regenerant solutions in the COD test procedure indicated the strength of sulfuric acid was critical in obtaining complete oxidation of a synthetic waste solution. / M.S.

D. Tech. Chemical, Metallurgical and Materials Engineering / This study provides experimental data and new perspectives on selective precipitation of platinum group metals (PGMs) in the presence of base metals while at the same time reviewing the mass transfer characteristics and models associated with metal sulphides precipitation in liquid-liquid and gas-liquid systems. In this study, the objective was to investigate and validate the concept of selective precipitation of platinum from chloride media using sulphur-bearing liquids or gases.