This thesis involves a study of the thermodynamics of liquid mixtures containing N-methyl-2pyrrolidone (NMP) and hydrocarbons or ethers. NMP is a polar liquid which is used in liquid extraction procedures for the separation of polar and nonpolar hydrocarbons. It was considered important enough to devote an entire thesis to the properties of NMP related to its interactions with simple hydrocarbons and ethers. The thesis consists of four parts: Part one is devoted to liquid-liquid equilibria. Experimental results at 298.2 K, are presented for the mixtures: NMP + an aromatic hydrocarbon + an n-alkane. Firstly, the effect increasing the chain length of the alkane has on the liquid-liquid equilibria was investigated, by studying mixtures of the type: an n-alkane + toluene + NMP; where the n-alkane refers to n-hexane or n-nonane or n-tetradecane or n-hexadecane. Secondly, the effect of substitution on the benzene ring on the equilibria was studied by measuring the liquid-liquid equilibria for the mixtures: n-hexadecane + an aromatic hydrocarbon + NMP; where the aromatic hydrocarbon refers to toluene or o-xylene or m-xylene or p-xylene or mesitylene or ethyl benzene. The chain length of the n-alkane had a significant effect on the liquid-liquid equilibria. Methyl substitution on the benzene ring had a small effect on the liquid-liquid equilibria. Part two is devoted to activity coefficients at infinite dilution. Experimental results at 298,15 K, determined using gas-liquid chromatography, are presented for the mixtures: NMP (solvent) + n-pentane or n-hexane or n-heptane or n-octane or cyclopentane or cyclohexane or cycloheptane or I-hexene or 1-heptene or l-octene or diethyl ether or diisopropyl ether. The magnitudes of the infinite dilution activity coefficients had the following order: n-alkanes > cycloalkanes > l-alkenes > ethers. Part three is devoted to excess molar enthalpies. Experimental results at 298.15 K are presented for the mixtures: NMP + an aromatic hydrocarbon. Here, an aromatic hydrocarbon refers to one of benzene or toluene or o-xylene or m-xylene or p-xylene or mesitylene or ethyl benzene. Isothermal flow microcalorimetry was used to determine the excess molar enthalpies. Increased methyl substitution on the' benzene ring manifests itself as a reduction in the association between NMP and the aromatic hydrocarbon. Part four is devoted to excess molar volumes. Experimental results at 298.15 K are presented for the mixtures: NMP + an aromatic hydrocarbon. Here, an aromatic hydrocarbon refers to one of benzene or toluene or o-xylene or m-xylene or p-xylene or mesitylene or ethyl benzene. Densitometry was used to determine the excess molar volumes. The excess molar volumes were negative for all the mixtures. / Thesis (M.Sc.)-University of Natal, 1997.

Separation processes are fundamental to all chemical engineering industries. Solvent separation, either liquid-liquid extraction or extractive distillation, is a specialised segment of separation processes. Solvents can be used either to optimise conventional distillation processes or for azeotropic systems, which can not be separated by conventional means. This work focuses on the performance of monoethanolamine (MEA) as a solvent in extractive distillation. Furthermore, the methodology of solvent evaluation is also studied. The preliminary assessment of solvent selection requires the determination of selectivity factors. The selectivity factor is defined as follows: P• = y,." . y, where y" is the activity coefficient at infinite dilution of the solute in the solvent. Subscript 1 and 2 refer to solute 1 and 2. A large selectivity factor implies enhanced separation of component 1 from 2 due to the solvent. Activity coefficients at infinite dilution were determined experimentally (gas-liquid chromatography) and predicted theoretically (UNIFAC group contribution method) for twenty-four solutes at three temperatures. Solutes used were alkanes, alkenes, alkynes, cyclo-alkanes, aromatics, ketones and alcohols. Most of this experimental work comprises data for systems which have not been measured before. Predicted and experimental values for y' were compared. For systems such as these (with polar solvents and non-polar solutes), UNIFAC results are not accurate and experimentation is vital. The experimental selectivity factors indicated tihat MEA could be an excellent solvent for hydrocarbon separation. Three binary azeotropic systems were chosen for further experimentation with MEA n-hexane (1) - benzene (2): fJ,~ = 31. Compared to other industrial solvents this is one of the largest values and MEA could serve as an excellent solvent. cyclohexane (1) - ethanol (2): fJ,~ = 148. This high value indicates an excellent solvent for this system. Acetone (1) - methanol (2): fJ,~ = 7.7. Further work involved vapour-liquid equilibrium experimentation at sub-atmospheric pressures in a dynamic recirculating stil l. The binary components with a certain amount of MEA were added to the still. The vapour and liquid mole fractions for the binary azeotropic components were measured and plotted on a solvent-free basis. The results are summarised below: n-hexane - benzene: Amount MEA added to still feed: 2%. MEA improved separability slightly. Further addition of MEA resulted in two liquid phases forming. cyclohexane - ethanol: Amount MEA added to still feed: 5% and 10%. Two liquid phases were formed for cyclohexane rich mixtures. Addition of MEA improved separability but did not remove the azeotrope. acetone - methanol: Amount MEA added to still feed : 5%, 10% and 20%. The ternary mixture remained homogenous and separability improved with addition of MEA. The binary azeotrope was eliminated. Due to the hetrogenous nature of the cyclohexane - ethanol system liquid-liquid equilibrium experimentation was performed to complete the analysis. Viable separation processes are possible for (a) cyclohexane - ethanol mixtures and for (b) acetone - methanol mixtures using MEA as the solvent. Comparison of various solvents used for the separation of acetone from methanol was possible by constructing equivolatility curves for the ternary systems. Results showed that MEA may possibly be the best solvent for this extractive distillation process. This study provides the following results and conclusions: • New thermodynamic data, important for the understanding of MEA in the field of solvent separations, was obtained. • Results show that the UNIFAC contribution method cannot be used to accurately predict polar solvent - non-polar solute y«> values. Experimentation is essential. • Selectivity factors indicate that MEA could be an excellent solvent for hydrocarbon separation. • The separation of the azeotropic cyclohexane - ethanol mixture is possible with a combination of extractive distillation and liquid-liquid extraction or simply liquid-liquid extraction using MEA as the solvent. • The separation of the azeotropic acetone methanol mixture is possible with extractive distillation using MEA as the solvent. The solvent MEA is possibly the best solvent for this separation. / Thesis (M.Sc.Eng.)-Univeristy of Natal, Durban, 2000.

Optimisation attempts within the petrochemical industry have led to interest in alternate solvents. The most widely used commercial solvents for the separation of hydrocarbons, by extractive distillation, are N-methylpyrrolidone and sulfolane. There has also been reference made to other solvents, such as N-formylmorpholine and the ethylene glycols [mono-, di-, tri- and tetra], being used. The alternate solvents proposed for this study were N-formylmorpholine, triethylene glycol and diethylene glycol. Infinite dilution activity coefficients, γ∞, provided a means of comparing the ease of separation of the different solutes using different solvents in extractive distillation. There is a substantial database of γ∞ measurements for systems involving N-methylpyrrolidone and hydrocarbons. A fairly large data set of γ∞ values of hydrocarbons in N-formylmorpholine has also been measured. Very little work has been conducted on the γ∞ values of hydrocarbons in either diethylene glycol or triethylene glycol. Gas liquid chromatography is one of the more common methods used to measure γ∞. To enable the measurement of γ∞ at higher temperatures, a pre-saturator was installed prior to the column. This ensured that the carrier gas entering the column was saturated with solvent and prevented the elution of solvent from the column. The γ∞ values of 25 solutes; including n-alkanes, alk-1-enes, alk-1-ynes, alcohols and aromatics; were measured at temperatures of 333.15, 348.15 and 363.15 K. The γ∞ measurements in N-formylmorpholine were used to verify this experimental set up and technique. Once the experimental set up had been proven, γ∞ in N-methylpyrrolidone, triethylene glycol and diethylene glycol were measured. Selectivities and capacities, at infinite dilution, of several solute combinations in the four solvents were then compared. In a few of these separation cases, the alternative solvents appeared to have better separation performance than N-methylpyrrolidone. The γ∞ values of three of the solutes in N-formylmorpholine and N-methylpyrrolidone were also measured using the novel cell design and measurement procedure suggested by Richon. It was found that this new technique required further development for the case of volatile solvents, since the results obtained using this technique did not compare favourably with the literature data. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2012.

This study is an investigation into the biodegradation potential of a TCE contaminated aquifer located at the Atomic Weapons Establishment in the UK, and the remediation prospects by employing biological and biotechnological processes such as bacterial community structure and diversity assessment, toxicity and isotopic fractionation.  Quarterly monitoring of boreholes from the former military site suggested that the plume is predominantly aerobic and therefore reliance cannot be placed only on natural attenuation.  In addition the contaminated plume contains a variety of volatile organic chemicals, petroleum, diesel and metals, which introduces potential co-metabolites as well as additional toxicity.  Assessment of the natural bacterial community of the site revealed sufficient bacterial counts to support intrinsic bioremediation and the presence of multiple additional contaminants.  Variable toxicity responses not solely explainable by TCE were observed with a broad functional bacterial diversity, which could be bio-stimulated (with substrates such as the terpenes carvone, pulegone and linalool as well as the aromatic compound cumene) or bio-augmented (with <i>Dehalosporillium multivorans</i>) to increase rates of TCE degradation.  Other additional agents such as iron filings were able to stimulate rapid rates of TCE degradation.  There is also evidence of potential TCE degraders within the more heavily contaminated boreholes (the finding of <i>Pseudomonas putida</i>).  Lastly isotopic fractionation suggests that degradation of TCE is occurring on site.

Dissertation research involves development of Mobile Order Theory thermodynamic models to mathematically describe and predict the solubility, spectral properties, protonation equilibrium constants and two-phase partitioning behavior of solutes dissolved in binary solvent mixtures of analytical importance. Information gained provide a better understanding of solute-solvent and solvent-solvent interactions at the molecular level, which will facilitate the development of better chemical separation methods based upon both gas-liquid and high-performance liquid chromatography, and better analysis methods based upon complexiometric and spectroscopic methods. Dissertation research emphasizes chemical equilibria in systems containing alcohol cosolvents with the understanding that knowledge gained will be transferable to more environmentally friendly aqueous-organic solvent mixtures.

The purpose of this dissertation is to investigate the thermodynamic properties of nonelectrolyte solutes dissolved in ternary solvent mixtures, and to develop mathematical expressions for predicting and describing that behavior in the solvent mixtures. Thirty-four ternary solvent systems were studied containing either alcohol (1-propanol, 2-propanol, 1-butanol, and 2-butanol), alkane (cyclohexane, heptane, and 2,2,4-trimethylpentane) or alkoxyalcohol (2-ethoxyethanol and 2-butoxyethanol) cosolvents. Approximately 2500 experimental measurements were performed. Expressions were derived from the Combined Nearly Ideal Multiple Solvent (NIMS)/Redlich-Kister, the Combined Nearly Ideal Multiple Solvent (NIMS)/Bertrand, Acree and Burchfield (BAB) and the Modified Wilson models for predicting solute solubility in ternary solvent (or even higher multicomponent) mixtures based upon the model constants calculated from solubility data in sub-binary solvents. Average percent deviation between predicted and observed values were less than 2%, documenting that these models provide a fairly accurate description of the thermodynamic properties of nonelectrolyte solutions. Moreover, the models can be used for solubility prediction in solvent mixtures in order to find the optimum solvent composition for solubilization or desolubilization of a solute. From a computational standpoint, the Combined Nearly Ideal Multiple Solvent/Redlich-Kister equation is preferred because the needed model constants can be calculated with a simple linear regressional analysis. Model constants for the Modified Wilson equation had to be calculated using a reiterative trial-and-error method. The C++ program for the Modified Wilson equation applied to ternary and heptanary solvent mixtures is attached.

RESUMO O objetivo deste estudo foi comparar a citotoxicidade in vitro dos solventes utilizados em terapia de retratamento endodôntico: óleo de casca de laranja, eucaliptol, xilol, clorofórmio e halotano através da avaliação da citotoxicidade de cada solvente em diferentes concentrações finais e condições de contato com as células de fibroblastos de linhagem NIH 3T3. O experimento foi dividido em 4 etapas: etapa 1- os solventes foram misturados em meio de cultura (DMEM) nas concentrações finais de 0, 5, 10, 25, 50 e 100% e depositados sobre a cultura de células para o tempo de 5 minutos; etapa 2-os solventes foram misturados em meio de cultura nas concentrações finais de 0, 10 e 25% e depositados sobre a cultura de células para os tempos de 10 e 15 minutos; etapa 3a- os solventes foram depositados sobre as células de fibroblastos (contato direto) e acrescido de meio de cultura; etapa 3b-onde os fibroblastos receberam o meio de cultura e sobre este depositado os solventes testes (contato indireto) nas concentrações finais de 0, 5 e 10% para o tempo de 5 minutos; etapa 4- os solventes foram previamente solubilizados com o álcool absoluto na proporção de 1:1 e depois misturados ao meio de cultura na concentração final de 5% para o tempo de 5 minutos. A avaliação foi realizada pela contagem celular através de método de exclusão de células coradas pelo azul Trypan. Os resultados obtidos nos permitiram concluir que todos os solventes testados são citotóxicos in vitro, sendo que o óleo de laranja foi o menos tóxico, ao permitir alguma viabilidade celular. Observou-se ainda que o preparo prévio dos solventes influenciou no percentual de células viáveis. / SUMMARY The aim of this study was to compare in vitro solvents used in endodontic retreatment therapy: orange oil, eucalyptol, xylene, chloroform and halothane through cytotoxicity evaluation of each solvent in different final concentration and contact conditions to NIH 3T3 fibroblasts cells lines. The experiment was divided in four stages: stage 1- the solvents were mixed in culture medium (DMEM) in final concentrations of 0, 5, 10, 25, 50 and 100% placed on the cells in culture for periods of 5 minutes; stage 2- the solvents were mixed in culture medium in finals concentrations of 0, 10 and 25% placed on the cells in culture for periods of 10 and 15 minutes; stage 3a- the solvents were placed on the fibroblasts cells (direct contact) and added culture medium; stage 3b- the fibroblasts cells get first culture medium and after that solvents were placed (indirect contact), in bouth the finals concentrations were 0, 5 and 10% for periods of 5 minutes; stage 4- solvents were previously solubilized in absolut alcohol in 1:1 proportion and mixed in culture medium in 5% final concentration for periods of 5 minutes. The evaluation were achieved by cellular counting through dyed exclusion method-Trypan blue. The results showed that all solvents were toxic in vitro, and orange oil was less toxic and it allowed some cellular viability. And we could observe that a previous solvents preparation influenced in the viable cells percentage.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING / Vita. / Includes bibliographical references. / by Timothy George Peter Gutowski. / Ph.D.

Dispatchable low carbon electricity has been identified as a key requirement for low carbon electricity systems because these systems must provide reliable electricity services to an increasing portion of the world’s population while utilising an increasing share of nondispatchable assets such as renewable and nuclear generators. Fossil fuel generators can provide dispatchable low carbon electricity by leveraging post-combustion carbon capture technologies assuming post-combustion capture (PCC) plants can operate in a flexible and efficient manner. This thesis explores the connection between solvent analysis techniques and the optimal operation of PCC plants with a particular focus on process optimisation and control under flexible and transient conditions. The connection between solvent analysis measurements and PCC plant process control and optimisation strategies is established. An ideal set of analysis technique criteria is established for flexible post-combustion capture plants. Currently available solvent analysis techniques are surveyed and evaluated against the ideal set of criteria. Specific weaknesses of current techniques are highlighted and two novel solvent analysis techniques are introduced to address these weaknesses. The first provides continuous amine concentration and CO2 loading measurements at process flow conditions by inferring solvent chemical composition from physical properties. This method was evaluated by deploying an instrument prototype to a post-combustion pilot plant to continuously analyse solvent during a test campaign which simulated flexible plant operation. The measurement results were compared against industry standard solvent analysis techniques and the inferential technique was found to produce sufficient measurement accuracy and sensitivity while providing a faster, lower cost and more robust measurement technique. The second technique combines the strengths of several currently available CO2 loading techniques to measure CO2 gas evolved from an acidified solvent under vacuum conditions. The technique was found to provide superior measurement accuracy and sensitivity compared to currently available methods when measuring lab standard solutions. The integration of these novel analysis techniques into advanced process control systems is proposed and future method improvements are suggested.

Notre étude est axée sur la recherche de nouveaux solvants éco-compatibles de substitution dans le cadre de la directive européenne REACH. Plus particulièrement, le but du projet est de substituer les solvants toxiques tels que la N-méthylpyrrolidone (NMP), le crésol et le phénol utilisés dans l'industrie des vernis d'émaillage par des solvants de moindre toxicité qui permettent de synthétiser ces vernis dans ces solvants tout en conservant les mêmes propriétés. Pour la synthèse de leur vernis d'émaillage qui est par exemple utilisé pour le revêtement des fils de cuivre, l'entreprise IVA utilise en grande quantité la NMP (CMR-18), le phénol et le crésol (toxique, irritant, corrosif..). Lors du processus de revêtement, les solvants contenus dans le vernis sont brûlés. Pour substituer ces solvants, nous allons dans un premier temps, étudier le mécanisme de polymérisation et ainsi comprendre le rôle des solvants impliqués. Ensuite, nous allons procéder à la caractérisation des polymères constituants les vernis (les polyesterimides et les polyamide-imides) en synthétisant des « authentiques » qui ont été caractérisés -entre autre- par analyse infrarouge. En fin, nous effectuerons un criblage de différents solvants « moins toxiques » afin de réaliser la synthèse des polymères dans ce(s) nouveau(x) solvant(s). Les solvants utilisés seront soit commerciaux, soit synthétisés à partir de la biomasse. Lorsque les vernis d'émaillage non toxiques seront obtenus dans un ou plusieurs nouveaux solvants de moindre toxicité, nous évaluerons leurs propriétés d'application / Our study is focused on the search of new solvents eco-compatible alternative development in the framework of the European directive REACH. More particularly, the aim of the project is to substitute the toxic solvents such as N-methyl pyrrolidone (NMP), the cresol and phenol used in the industry of the varnishes of enamelling by solvents of lesser toxicity which enable you to synthesize these varnishes in these solvents while maintaining the same properties. For the synthesis of their varnish of enameling which for example is used for the coating of the copper wires, company IVA uses in great quantity NMP (CMR-1B), phenol and cresol (toxic, irritant, corrossive….). During the process of coating, the solvents contained in varnish are flaring. To substitute these solvents, we will in a first time, study the mechanism of polymerization and thus understand the role of solvents involved. Then, we will proceed to the characterization of the polymer constituents the varnish (the poly (esterimide) s and the polyamide-imides) by synthesizing "authentic" which were characterized ideally by infrared analysis. Finally, we will conduct a screening of different solvents "less toxic" in order to achieve the synthesis of polymers in this/these new solvent(s). The solvents used will be either commercial, or synthesized from biomass. When the varnish of enameling non toxic will be obtained in one or several new solvents of lesser toxicity, we will assess their application properties