Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--Virginia Commonwealth University, 2004. / Prepared for: Dept. of Chemistry . Bibliography: leaves 272 - 286 . Also available online via the Internet.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Th. 3e cycle--Physico-chim. des matér.--Toulouse--I.N.P., 1979. N°: 50.

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas, Programa de Pós-Graduação em Química, Florianópolis, 2010 / Made available in DSpace on 2012-10-24T23:31:32Z (GMT). No. of bitstreams: 1 277520.pdf: 1692020 bytes, checksum: e5e81cf9e2415e9914ced4b9908d4ad0 (MD5) / O aumento na demanda de biodiesel pelo governo brasileiro com a implementação da mistura B5 (5 % de biodiesel adicionado ao diesel fóssil) além de aumentar a produção de biocombustível do país, reduz os gastos com importação e a emissão de gases responsáveis pelo agravamento do efeito estufa. Neste trabalho foram desenvolvidas duas metodologias analíticas para determinação de parâmetros químicos da qualidade de biodiesel utilizando eletroforese capilar. O primeiro capítulo versa sobre a determinação simultânea dos cátions inorgânicos: sódio, potássio, cálcio e magnésio. Foi utilizado planejamento fatorial fracionário do tipo 2v5-1 para otimização da extração dos analitos da matriz. Os parâmetros de precisão inter-ensaio (RSD %), limite de detecção (LOD), limite de quantificação (LOQ) e coeficiente de determinação (R2) para a metodologia desenvolvida corresponderam a 4,58 - 6,88 %; 0,3 mg L-1, 1,0 mg L-1 e 0,999 respectivamente. A faixa de aplicação foi de 0,5 - 20 mg L-1 para todos os cátions. O estudo de recuperação foi aplicado para avaliar possíveis efeitos de matriz e os resultados variaram na faixa de 88,1-123,0 %. No total oito amostras foram quantificadas e apenas uma teria resultados satisfatórios para comercialização do ponto de vista deste requisito de controle da qualidade. O segundo capítulo trata do desenvolvimento de método para determinação de - monoglicerídeos. Foram tomadas estratégias de preparo de amostras para tornar o método simples e rápido, para tanto, utilizou-se gráficos de superfície de mistura ternária formada entre etanol/água/clorofórmio para medidas de turbidez e teor de iodato formado pela reação de íons periodato com os - monoglicerídeos. Foi observado que a formação de uma única fase miscível entre amostra e o periodato de sódio mostrou-se essencial no processo reacional, obtendo como resultado melhora nas precisões nas medidas. Quanto aos parâmetros de precisão inter-ensaio (RSD %), limite de detecção (LOD), limite de quantificação (LOQ) e coeficiente de determinação (R2) corresponderam a 6,8-13,6 %; 0,16 mg kg-1, 6,28 mg kg -1 e 0,999 respectivamente. A faixa de aplicação foi de 1,57 - 157 mg L-1 para glicerina e - monoglicerídeos. O método pode ser aplicado para estudos dos mecanismos da transesterificação para produção de biodiesel.

At the heart of long term sustainable soil management is chemical fertility through the retention of exchangeable cations. Many current concepts of cation exchange and its relationship with base cation availability remain unchanged over the past century. Despite considerable advancements in analytical techniques many methods used today would be familiar to our forefathers. Comparative studies were undertaken in this thesis to understand how techniques to measure exchangeable soil ions could be enhanced and matched to defined scenarios. The total amount of cations that can be retained electrostatically on soil surfaces is termed the cation exchange capacity (CEC). An ability to systematically and consistently measure CEC is an essential step in soil characterisation. Compulsive exchange methods (using either 1.0 M NH4OAc or 0.05 M BaCl2) at a fixed pH value for determining CEC were scrutinised but acknowledged to be prone to systematic artefacts. The relationship between soil pH, soil texture and CEC was soil specific. When the batch method was compared with the column leach method, the former was more consistent for all soils. For calcareous soils BaCl2 was more suitable but NH4OAc was more generally applicable. The CEC was consistently significantly greater by the compulsive technique when compared with the effective method. The NH4OAc extraction method was applied to soils contaminated with potentially toxic elements (PTEs). The exchangeable concentration of PTEs correlated with total PTE loading. However, the exchangeable Ca decreased with amendment rate confirming an exchange of sites by PTEs. The compulsive technique extracted PTEs that were significantly 2 negatively correlated with soil basal respiration, phosphatase activity, potential nitrification rate (PNR) and the soil microbial biomass carbon. This confirms that of this method is evaluating the bioavailable/bioreactive fraction. Soil cation exchange capacity and exchangeable base cations increased commensurate with the amendment loading of bentonite and charcoal. The exchange capacity was also soil specific. Following amendments, the exchange capacity was higher after six weeks than after thirty weeks. This means that the amendment performance became impaired with time perhaps as the fine soil particles coated the ameliorant causing a decline in CEC. The difference between the effective and compulsive CEC was described as the calculated CEC. This was very sensitive to soil pH and was confirmed in a detailed study at a site where pH plots were amended over a five decade period. As pH rose, so did the exchangeable fraction of Ca, Mg and K. As the pH declined, Al, Fe and Mn exchangeability increased. Extraction techniques must be sympathetic of the soil pH value. The quantification and characterisation of exchangeable cations remains as fundamental a component of soil science today as it was a century ago.

Introduction: Part 1. Greenhouse studies were conducted to investigate the absorption of sodium, potassium, calcium and magnesium by lemon seedlings. The plants were grown in controlled nutrient solutions and analysis of the plant material was made to determine the relationship between the four cations in the different plant organs. Results of the experiment may be summarized as follows:- The occurrence of leaf burn appeared to be associated with a low calcium content, together with a high sodium, potassium or sodium + potassium content. The development of the seedlings was shown to be markedly influenced by the level of calcium supply and to a much lesser degree by the level of potassium supplied. The concentration of sodium, potassium, calcium and magnesium in the stem and leaf varied with position of the tissues on the main axis. The level of sodium was found to influence the distribution of sodium in the leaves, and the sodium content of the leaf, stem and root tissues gave a good reflection of the level of sodium supplied. The effect of the sodium treatment on the uptake of potassium appeared to be dependent on the calcium content of the tissues. Sodium treatment was found not to affect the leaf calcium content. In the stem and root tissues the calcium content was reduced when the calcium level in the nutrient medium was low, and increased the calcium content of these two tissues at the higher level of calcium supply. The sodium supply was shown to reduce the leaf magnesium only slightly, and its affect on the magnesium content of the stem and root tissues was shown to be dependent on the level of calcium supplied. The potassium content of the leaves, stems and roots increased when the supply of potassium was raised. Increasing the potassium level in the nutrient supply was found to cause a very slight reduction in the sodium content of the leaf, but did not affect the sodium content of the stem and root. Potassium did not affect the calcium content of the leaves and increased the stem calcium when sodium was not present in the nutrient media in high concentrations. In the roots potassium only increase the calcium content at the upper level of calcium supply. The magnesium content of the leaf and stem tissues was reduced as the potassium supply was increased. In the roots the general trend was for the magnesium content to increase when the level of potassium treatment was raised. The calcium content of all the plant parts increased with a rise in the calcium supply, the stem and root tissues having a greater percentage increase than the leaves. The sodium content of the plant tissue was reduced as the level of calcium supply was raised. The leaf potassium content decreased with a higher calcium level of supply. In the stem and roots the potassium content was increased by doubling the calcium supply. The calcium treatment had no influence on the magnesium content of the foliage, but in the stem and root tissues a decrease in magnesium content resulted from an increase in the calcium supply. Part II Potato tuber tissue and carrot root tissue were used as experimental material in the investigation of sodium9 potassium9 and calcium uptake by storage tissue. It was shown that when the tissue disks are transferred from distilled water to a solution of salts there is a rapid initial uptake of cation which is neither particularly selective, nor related to metabolism, but dependent on the external concentration. On the other hand, the prolonged active accumulation of cation exhibits selectivity. Potassium absorption by potato tuber tissue was shown to be stimulated by sodium9 whereas the potassium and calcium absorption by carrot root tissue was shown to be reduced by sodium. Similarly the sodium absorption by the carrot root tissue was reduced by potassium, thus suggesting that the cations compete with one another for the same absorption mechanism.

<p> In an investigation on the formation of halogen cations, the I4 2+, Br3+, Br2+ and Cℓ3+ cations have been identified by conductivity, cryoscopy, ultraviolet and visible spectrophotometry, Raman spectroscopy and magnetic susceptibility measurements in strong acids. Bromine trifluorosulphate has been shown to ionise in the SbF5:3SO3/HSO3F system to give the Br(SO3F)2+ ion, and Raman bands of bromine fluorosulphates, CℓSO3F and S2O6F2 have been listed. No evidence has been found for the Cℓ2+ or CℓF+ ions in solution, and the assignment of observed ESR spectra to these cations is criticised.</p> <p> Raman spectra of the adducts AsF5 2CℓF and BF3 2CℓF have shown that they contain the CℓCℓF+ cation and not the CℓFCℓ+ cation. The bending frequency of the CℓF2+ cation has been reassigned, and force constants have been calculated for the CℓF2+ and Cℓ3+ cations.</p> <p> Resonance Raman spectra of the I2+ and Br2+ cations have been observed, and, as few examples of this effect are known, the variation in fundamental and overtone intensities with exciting wavelength have been investigated.</p> / Thesis / Doctor of Philosophy (PhD)

<p> The short term (5000 hours) stability of illite and montmorillonite in sea water was studied by suspending 5.00 gm. aliquots of A.P.I. reference clays Montmorillonite # 25b and Illite # 35 in 500 ml. of artificial sea water (tradename "Instant Ocean") . After 5000 hours, in the montmorillonite samples, Ca and Si concentrations had increased (0.490 mmoles/l and 0.289 mmoles/l respectively), the cation exchange capacity had decreased (104.36 meq/100 gms. to 81.42 meq/100 gms.), the pH had decreased (8.40 to 7.94) but no major mineralogical change was observed. After 5000 hours, in the illite samples, Si concentration had increased (0.045 mmoles/l), the cation exchange capacity remained the same, the pH increased (7.22 to 7.60) and no major mineralogical change was observed. The release of Ca in the illite samples was complicated by the dissolution of calcite and significant changes in concentration of other cations (Na, K, Mg) were not observed.</p> <p> The data for Si, cation exchange and exchangeable cations are compared to that of Lewis (1950), Whitehouse and McCarter (1956), Carrol and Starkey (1958), MacKenzie et al (1965) (1967) and Russell (1970), a model developed by Houston (1972) is used to explain the Ca and Si data for the montmorillonite samples, and the implications of the apparent stability of these minerals to the case for authigenic clay formation from detrital material are discussed.</p> / Thesis / Bachelor of Science (BSc)

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