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1
Vatin, Marin. "Modélisation multi-échelle de solutions organiques et systèmes interfaciaux pour l’extraction liquide-liquide." Thesis, Université de Montpellier (2022-….), 2022. http://www.theses.fr/2022UMONS009.
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Cette thèse présente un ensemble de modèles et de méthodes pour la description structurale et thermodynamique des solutions organiques et des systèmes interfaciaux rencontrées dans le contexte de l’extraction liquide-liquide. Les modèles et méthodes sont basés sur une approche qui est essentiellement à l’échelle moléculaire et ont une forte composante numérique. Une étude basée sur une approche par dynamique moléculaire a été utilisée afin d’étudier la séparation de phase d’un mélange eau-huile. Elle a aussi été utilisée afin de simuler les solutions organiques dont l’organisation supramoléculaire a été vérifiée par des comparaisons entre les spectres de diffusions des rayons X aux petits angles expérimentaux et issus de ces simulations moléculaires. L’organisation supramoléculaire a pu être caractérisée plus finement au cours d’études consacrées à l’agrégation en phase organique en présence de molécules extractantes de type malonamide (DMDOHEMA) et de sels de nitrate d’europium grâce à des traitements numériques poussés présentés dans cette thèse ; notamment par le calcul des distributions moyennes des espèces chimiques formées dans les solutions organiques. A partir de ces distributions, des modèles thermodynamiques des phénomènes d’agrégation en phase organique basés sur des approches numériques et analytiques ont été élaborés. Ces modèles ont notamment permis de calculer les énergies de formation des espèces en solution en fonction de leur composition, des nombres d’agrégation moyen en très bon accord avec les données expérimentales, d’étudier les mécanismes associés au phénomène de « formation de la troisième phase » par un modèle de percolation et l’étude de super-espèces et enfin, de calculer des grandeurs associées à la cinétique de formations des agrégats en phase organiqueThis thesis presents a set of models and methods for the structural and thermodynamic description of organic solutions and interfacial systems encountered in the context of liquid-liquid extraction. The models and methods are based on an approach that is essentially molecular. It has a strong numerical component. A study based on a molecular dynamics approach was used to investigate the phase separation of a water-oil mixture. It has also been used to simulate organic solutions whose supramolecular organization has been verified by comparisons between the experimental and the molecular simulations signals associated with small angle X-ray scattering. The supramolecular organization has been characterized more finely during studies devoted to the aggregation in organic phase in the presence of extractant malonamide molecules (DMDOHEMA) and of europium nitrate salts thanks to advanced numerical treatments presented in this thesis. These numerical treatments allowed the calculation of the mean distributions of the chemical species formed in the organic solutions. From these distributions, thermodynamic models of the aggregation phenomena in the organic phase based on numerical and analytical approaches have been developed. These models allowed the calculation of the energies of formation of the species in solution according to their composition, and the determination of the mean aggregation numbers in very good agreement with the experimental data, the study of the mechanisms associated with the phenomenon of “third phase formation” thanks to a super-species percolation model and the calculation of quantities associated with the kinetics of formation of aggregates in organic phase
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El, maangar Asmae. "L’extraction raisonnée de métaux stratégiques par des hydrotropes." Thesis, Université de Montpellier (2022-….), 2022. http://www.theses.fr/2022UMONS004.
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L’extraction liquide-liquide (LL) est la technologie principale de séparation employée dans les procédés hydrométallurgiques pour le recyclage des métaux stratégiques nécessaires à l’économie circulaire. La mise en œuvre industrielle du recyclage repose sur le contrôle du transfert d’espèces entre une solution concentrée d’électrolytes contenant les cations métalliques à extraire sélectivement et une solution de tensioactif lipophile associé à un solvant non miscible à l’eau et des « modificateurs de phase ». Une limitation des procédés d’extraction LL tel qu’utilisés actuellement est la formation de la 3ème phase. De plus, ils induisent un lourd impact environnemental en raison de l’utilisation de volumes élevés de réactifs et l’emploi intensif de solvants organiques non respectueux de l’environnement. Une des stratégies pour répondre à ces problématiques est d’utiliser des systèmes à base d’hydrotropes.Les hydrotropes sont une famille de molécules utilisés pour des applications en biochimie analytique, pharmaceutique et en cosmétique. Ces molécules n’ont jamais été étudiées dans le cadre du recyclage des métaux. Cette thèse est consacrée à la compréhension et la mise en œuvre d’hydrotropes pour l’extraction des métaux, ainsi qu’à l’identification des forces motrices mises en jeu.Ce travail décrit via la démarche « iénaïque », associant les approches supramoléculaire et colloïdale, ce qui se passe lorsque l’on remplace respectivement le diluant, le modificateur de phase et même l’extractant par des hydrotropes. Deux types d’hydrotropes sont étudiés : des hydrotropes qui sont des tensioactifs neutres courts et des hydrotropes électrolytes comme le salicylate de sodium. Dans chaque cas, la détermination des diagrammes de phases et de la nanostructuration des phases sont des préalables nécessaires à la compréhension des forces moléculaires à l’origine des transferts mesurés. L’utilisation des techniques de fluorescence de rayons X, de diffusion de rayons X et des neutrons, de tensiométrie interfaciale ainsi que de calorimétrie ont été déterminantes pour la compréhension des mécanismes sous-jacents à l’extraction hydrotropique.Au prix d’une augmentation de complexité des schémas procédés liés à la solubilité de l’hydrotrope dans les phases aqueuses, nous démontrons que l’emploi d’hydrotropes à la place du diluant ou même à la place de l’extractant, compris par la décomposition « iénaïque », amènent à un gain d’un ordre de grandeur en intensification de procédé et/ou en volume d’effluents produits, ouvrant la voie à l’extraction « raisonnée » des métaux en vue de leur recyclage depuis la mine urbaineLiquid-liquid extraction (LLE) is the main separation technology used in hydrometallurgical processes for the recycling of strategic metals needed for a circular economy. The industrial implementation of recycling relies on the control of the transfer of species between a concentrated solution of electrolytes containing the metal cations to be selectively extracted and a solution of lipophilic surfactant associated with a water-immiscible solvent and “phase modifiers”. A limitation of LLE processes as currently used is the formation of the 3rd phase. In addition, they induce a heavy environmental impact due to the use of high volumes of reagents and the intensive use of non-environmentally friendly organic solvents. One possible strategy to overcome these problems is by using hydrotrope-based systems.Hydrotropes are a family of molecules used for applications in analytical biochemistry, pharmaceuticals and cosmetics. These molecules have never been studied in the context of metal recycling. This thesis is devoted to the understanding and implementation of hydrotropes for metal extraction, as well as to the identification of the driving forces involved.This work uses the “ienaics” approach to measure and understand what happens when the diluent, the phase modifier and even the extractant are replaced by hydrotropes, respectively. Two types of hydrotropes are studied: hydrotropes that are short neutral surfactants and electrolyte hydrotropes such as sodium salicylate. In each case, the determination of the phase diagrams and the nanostructuration of the phases are necessary prerequisites to understand the molecular forces at the origin of the measured transfers. The use of X-ray fluorescence, X-ray and neutron scattering, interfacial tensiometry and calorimetry techniques have been decisive for the understanding of the mechanisms underlying hydrotropic extraction.At the cost of an increase in complexity of the process schemes related to the solubility of the hydrotrope in the aqueous phases, we demonstrate that the use of hydrotropes instead of the diluent or even instead of the extractant, understood by the “ienaics” decomposition, leads to a gain of an order of magnitude in process intensification and/or in volume of effluents produced, opening the way to the “reasoned” extraction of the metals for their recycling from the urban mine
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Sebogisi, Baganetsi Karabo. "Separation of racemates via host-guest chemistry." Thesis, Cape Peninsula University of Technology, 2012. http://hdl.handle.net/20.500.11838/730.
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Thesis submitted in fulfilment of the requirements for the degree
Magister Technologiae: Chemistry
in the Faculty of Applied Science
at the
CAPE PENINSULA UNIVERSITY OF TECHNOLOGY
2012Chirality is very important to the pharmaceutical industry as enantiomers have the same macroproperties except for their optical and pharmacological activity. Industrial research has thus focused to find the most effective resolution technique. However, our aim was to obtain more information regarding the discrimination process. In this project the structures of the hydrates of di-quininium L-malate, (2QUIN+)(L-MA2-)•2H2O and the di-quininium D-malate, (2QUIN+)(D-MA2-)•2H2O have been investigated. (-)-Quinine (QUIN) did not show selectivity between the D and L malic acid and the structure of (2QUIN+)(DL-MA2-)•2H2O was obtained. Effect of solvents was demonstrated in the study and the structure of (QUIN+)(D-MA-)•H2O) was reported. The relationship between C-O bonds of the carboxylate and carboxylic moieties and ÄpKa was explored in salt and co-crystal formation. Kinetics of absorption was conducted for the reaction of (+)-deoxycholic acid (DCA) with n-propylamine and DCA with racemic sec-butylamine. The rate constants of the reactions were determined. Kinetics of desolvation was performed on the powder samples of mixtures of DCA and sec-butylamine and DCA with di-n-butylamine. Non-isothermal methods were used where a series of TG analyses was carried out at different heating rates (2, 4, 10, 32 K min-1). The structures of DCA with n-propylamine and di-n-butylamine were elucidated. The selectivity of DCA was investigated. The host compound was found to be able to successfully resolve racemic sec-butylamine (2-BUAM) and 2-amino-3-methylbutane (MeBUAM). The structures of DCA with enantiomers of these guests are reported in the study. The structures of R-BUAM and S-BUAM were solved in different space groups while R-MeBUAM and S-MeBUAM crystallized in the same space group.
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Valdovinos, H. F., S. Graves, T. Barnhart, and R. J. Nickles. "Simplified targetry and separation chemistry for 68Ge production." Helmholtz-Zentrum Dresden - Rossendorf, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-166311.
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Introduction
68Ge (t½ = 270.8 d, 100% EC) is an important radionuclide for two reasons: 1) once in equilib-rium with its daughter nuclide 68Ga (t½ = 68 min, 89 % β+, 3 % 1077 keV γ), it can be used as a positron source for attenuation correction and calibration of PET/MRI scanners; and 2) it can be employed as a generator of 68Ga for radiophar-maceutical preparation. Most isotope production facilities produce it using natural gallium (60.1% 69Ga, 39.9% 71Ga, melting point: 39 °C) as target material for proton bombardment at energies > 11.5 MeV, the threshold energy for 69Ga(p,2n)68Ge [1]. A maximum cross section of ~330 mb for natGa(p,x)68Ge occurs at ~20 MeV [1], hence proton energies in this neighborhood are mandatory for large scale production. Galli-um targetry is challenging due to its low melting point and corrosivity, hence compounds such as Ga2O3 (melting point: 1900 °C) or GaxNiy alloys (melting points > 800 °C) [2], have been used as target compounds [3,4,5]. The separation chem-istry technique employed by large-scale produc-tion facilities is liquid-liquid extraction using CCl4 [6,7]. In this work, two simple methods for GaxNiy alloy preparation are presented as well as a simple germanium separation procedure using a commercially available extraction resin.
Material and Methods
GaxNiy alloys were prepared by two methods (A,B). A) electrodeposition over 1.3 cm2 of a gold disk substrate. Ga2O3 and NiSO4.6H2O were dis-solved in a mixture of (27%) H2SO4 and NH4OH at pH 1.5 in a 3:2 mass ratio so that the Ga:Ni molar ratio was 4:1. The solution was then transferred to a 15 mL plating cell, in which a current of 29 mA/cm2 was applied with a platinum anode at 1 cm from the gold surface. B) Ga pellets were fused together with Ni powder at different Ga:Ni molar ratios using an induction furnace (EIA Power Cube 45/900). The resulting alloy pellets were then rolled to foils using a jeweler’s mill pressed between Nb foils to avoid contamination.
Target irradiations were performed on a GE PETtrace at 16 MeV protons. The electroplated alloys were mounted on a custom-made solid target irradiation system with direct water-jet cooling applied to the backside of the gold disk. The alloy foils were placed on top of in a 1.2 cm diameter, 406 μm deep pocket made of Nb and sealed against a 51 μm Nb foil using a teflon O-ring. The alloys were in direct contact with the Nb foil to allow thermal conduction. At the rear of the Nb pocket is a water-cooling stream to transfer heat convectively during irradiation.
Ge separation was achieved based on the difference in distribution coefficients between Ge, Ga, Zn, Cu, Ni and Co at different HNO3 molarities in DGA resin (Triskem International). Initial tests on the resin were performed after two pilot irradiations on natural gallium (a,b). a) 16 MeV protons were directed downward on an external beam-line (−30 °) onto 640 mg of molten elemental natGa pooled on a water-cooled niobium support. b) 330 mg natGa pellet was melted in the same Nb pocket well used with the alloys and was also sealed against a 51 μm Nb foil. The irradiated gallium was left to decay for 2 weeks and then was dissolved in 6 mL of concentrated HNO3. The solution was then passed through 200 mg of DGA resin packed in a 5 mm diameter column at a flow rate of 1.1 mL/min. A separation profile for Ge, Ga and Zn was obtained by collecting 0.2–1.0 mL fractions, which were analyzed by gamma ray spectroscopy on a HPGe detector.
Two thick NiGa4 foils have been irradiated, one for 69Ge production and for radiocobalt, from 58Ni(p,α), separation quantification; and the other one for 68Ge production with the idea of preparing a mini-generator (< 13 MBq) of 68Ga for local use in phantom imaging work and animal studies.
Results and Conclusion
A) Each electroplating batch consisted of 66.5 ± 2.9 mg of Ga2O3 mixed with 44.9 ± 3.6 mg of NiSO4.6H2O (n = 9) in the 15 mL plating cell. Higher concentrations resulted in inefficient electroplating yields due to precipitation. 66 ±
6 % of the total Ga+Ni mass in solution, that is 39.5 ± 3.3 mg of Ga-Ni was deposited after 3 d. Three plating batches over one disk resulted in a maximum target thickness of 86.7 mg/cm2. A fourth batch did not add any significant amount of alloy and salt precipitation became a problem. The electroplated surface looked homogeneous at 10× magnification on a microscope and the targets were able to withstand up to 30 μA without presenting any dark spots.
B) Alloys with Ga:Ni molar ratios of 1.0, 2.0, 2.9, 3.7 and 5.2 were fused by induction heating. TABLE 1 summarizes the results from manipulating these foils. These alloys were analyzed by X-ray fluorescence using a 109Cd excitation source quantifying the x-rays peaks: 9.26 keV for Ga and 7.48 keV for Ni. A linear relationship between the ratio of count rates of these two peaks to the alloy Ga:Ni molar ratio was found and employed for the characterization of the electroplated Ga-Ni layers.
Results from the irradiations over natGa on Nb supports are presented in TABLE 2.
TABLE 3 presents the results from irradiating two thick NiGa4 foils made by induction heating.
Figure 1 contains the separation profile with DGA. 91% of the 68Ge is eluted in 2 mL of de-ionized water.
We developed two simple methods for NiGa4 alloy manufacture. With a melting point > 800 °C and 80% presence of natGa, it is a more convenient target for 68Ge production compared to Ga encapsulated in Nb. The separation method based on the extraction resin DGA yields similar results as the liquid-liquid extraction method mentioned in [6,7], but we believe this is a more convenient method since it only requires a single trap-and-release step and not many extraction steps.
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Wang, Yafei. "Species Chemistry and Electrochemical Separation in Molten Fluoride Salt." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/102614.
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Fluoride salt-cooled high-temperature reactor (FHR) is a safer and potentially less expensive alternative to light water reactor due to the low pressure of primary system, passive decay heat cooling system, chemically inert coolant salt, and high-temperature power cycle. However, one challenge presented by this reactor is that fission products may leak into the primary system from its TRISO particle fuel during normal operation. Consequently, the circulating fission products within the primary coolant would be a potential radioactive source. On the other hand, the containment material of the molten salt such as nickel-based alloys may be corroded, and its species may stay in the salt. Thus, the installment of the primary coolant clean-up system and the study on the contaminant species' chemistry and separation are necessarily needed.
Electrochemical separation technique has been proposed as the online coolant clean-up method for FHR for removing some impurities from the salt such as lanthanides and corrosion products. The present research focuses on the electrochemical separations of fission products and corrosion products in molten FLiNaK salt (46.5LiF-11.5NaF-42KF mol%) which is the surrogate of the primary coolant candidate FLiBe (67LiF-33BeF2, mol%) for FHR. The main objective is to investigate the electrochemical behaviors of fission products and corrosion products in molten FLiNaK salt to achieve its separations, and provide fundamental properties to instruct the conditions needed to be applied for a desired electrochemical separation.
La and Ce are two main elements concerned in this study since they are major lanthanide fission products. Electrochemical behavior of LaF3 in molten FLiNaK salt was studied on both W and Mo inert working electrodes. Although the standard reduction potential of La (III) is more cathodic than that of the primary salt melt constituents K (I) and Na (I), the electrochemical separation of La from molten FLiNaK salt was achieved by merely using inert working electrode because of the formed LaF63- when KF or NaF exists as the salt constituents. Fundamental properties of La in molten FLiNaK salt were also studied at various situations by electroanalytical methods including cyclic voltammetry (CV), chronopotentiometry (CP), and potentiodynamic polarization scan (PS). Ce is another fission product to be separated out from molten FLiNaK salt. Both inert (W) and reactive working electrodes (Cu and Ni) were utilized to realize the extraction of Ce. The electrochemical behaviors of Ce observed on inert W electrode are similar to the ones obtained in FLiNaK-LaF3 system. Reactive electrodes Cu and Ni were used to precede the electrochemical deposition potential of Ce by forming intermetallic compounds. It turned out only Ni electrode was feasible for preceding the deposition potential and the intermetallic compound was identified as CeNi5.
The dissolution of chromium metal in the form of chromium fluoride into molten FLiNaK salt is the main concern of alloy corrosion in FHR. To understand the alloy corrosion and removal of the corrosion products from the FHR salt coolant, the electrochemical behavior and fundamental properties of Cr in molten FLiNaK salt were investigated in the present study as well. A new analysis method for the Cr two-step electrochemical reaction in the salt was developed. The method can be applied to other two-step reactions as well.
Liquid bismuth was proposed to be the extraction media for liquid/liquid multistage separation of fission products in molten salt reactor. It also can be used as the cathode to extract the fission product of which the electrodeposition potential is close to or more negative than that of the main constituents of molten salt. Activity and activity coefficient are essential factors for assessing the extraction behavior and viability of bismuth in separating fission products. Hence, in the present study, the activity and activity coefficient of fission products and alkali metals (Li and K) at different concentrations and temperatures were determined by experiment and simulation methods respectively.
To conduct the parametric study for the electrochemical reaction process and predict fundamental properties, an electrochemical model including single-step reversible, irreversible, and quasi-reversible reactions, multiple-reaction, and two-step consecutive charge transfer reaction was developed based on MOOSE. Although the model was not applied to analyze the experimental data in the present study, this model provides an efficient and easy way to understand the effect of various parameters on electrochemical reaction process.
The present study supplied a comprehensive study on the electrochemical separation of fission products and corrosion products in molten FLiNaK salt and will contribute greatly to the development of FHR.Doctor of Philosophy
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Starkey, Jason A. "Biochemical applications of microcolumn separation techniques." [Bloomington, Ind.] : Indiana University, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3278220.
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Thesis (Ph. D.)--Indiana University, Dept. of Chemistry, 2007.Source: Dissertation Abstracts International, Volume: 68-09, Section: B, page: 5919. Adviser: Milos V. Novotny. Title from dissertation home page (viewed May 9, 2008).
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Chen, Jian. "Chemistry and physics in low Reynolds number micro steady streaming devices /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/9928.
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Davies, Clair. "Capillary Electrophoretic Separation of Sulfoxides." TopSCHOLAR®, 1998. http://digitalcommons.wku.edu/theses/338.
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Chiral sulfoxides are most widely used in asymmetric synthesis. Their application as chiral synthons has now become a well-established and reliable strategy, mainly due to availability and high asymmetric induction exerted by the chiral sulfinyl group. Very few articles have been published on the separation of chiral sulfoxides; most involve HPLC or GC. The first separation of optically active sulfoxides was described by Phillips and co-workers. To date no work has been reported using capillary electrophoresis for the separation of alkylaryl sulfoxides. A series of alkylaryl sulfoxides were synthesized. Conditions for their separation were investigated using a modified 125 mM Boric acid (pH 8.5)/ 75 mM SDS buffer solution (MEKC buffer). Synthetic procedures for the preparation of these sulfoxides will be presented as well as separation results. The separation is based on the differential partition of solutes between the micelle and the bulk solution.
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Wildervanck, Alexander Franciscus. "Separation of enantiomers of Baclofen." Master's thesis, University of Cape Town, 1996. http://hdl.handle.net/11427/20462.
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(3-(Aminomethyl)-4-chlorobenzenepropanoic acid (Baclofen), 3-(p-chlorophenyl)pyrrolidone (Baclofen lactam) and 3-(p-Chlorophenyl)glutaramide (baclofen's synthetic precursor) were individually used as substrates in co-crystallisation experiments with several resolving agents. Experiments were conducted in the solid state and in solution. The (-) enantiomer of the lactam and the ( +) enantiomer of the glutaramide were found to cocrystallise selectively with (2R,3R)-( +)-tartaric acid and (S)-(-)-a.-Methylbenzylamine respectively. Both these dissociable diastereomers Vere analysed by X-ray crystallography. HPLC analysis of the lactam retrieved from the former co-crystals indicated only partial separation of its (+) and (-) enantiomers. X-ray crystallographic, thermal, and polarimetric analyses were perfom1ed on the ( + )- and (-)-salts of the latter co-crystals. The solubilities of these salts in methanol were found to differ by a factor of 4. A solubility diagram was established showing the phase equilibria of various ratios of these two salts in methanol. The(+) enantiomer of the glutaramide was separated from the methylbenzylamine in the (+) salt by treatment with HCI. This enantiomer was converted to (R)-(-)-Baclofen by means of a Hofinann Rearrangement with an overall yield of 40%. The enantiomeric excess of (R)-(".")-Baclofen was 99.7%.
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Vujovic, Dejana. "Separation of close isomers by enclathration." Doctoral thesis, University of Cape Town, 2001. http://hdl.handle.net/11427/9744.
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Includes bibliographical references.In this thesis the principles of molecular recognition were employed in the separation of closely related guests and guest exchange. The industrially important isomeric compounds such as xylenois, lutidines and cresols were successfully separated using different host compounds. Separation of aminobenzonitrile isomers was investigated in solution and in the solid state.
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Horne, Alicia. "Separation of close isomers by enclathration." Doctoral thesis, University of Cape Town, 1997. http://hdl.handle.net/11427/19647.
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The selective inclusion properties of the host compound 1, 1-bis-( 4- hydroxyphenyl)cyclohexane were investigated. This host readily forms inclusion compounds with the isomers of phenylenediamine, benzenediol, picoline and lutidine, as well as selected solvents including methanol, ethanol, i-propanol, n-butanol, ethyl acetate and dioxane. The crystal structures of the complexes formed were elucidated, and comparisons were made between the packing of the complexes, and the intermolecular interactions between the host and guest components of the complexes. The complexes were characterised using thermal analysis and X-ray powder diffraction. The lattice energies of the complexes were calculated to determine their relative stability. The kinetics of desolvation of the picoline and lutidine inclusion compounds were studied, using isothermal and non-isothermal thermogravimetry. These experiments yielded the kinetic models as well as the activation energies of the desolvation reactions. Competition experiments were performed to determine which isomers of the compounds mentioned above were enclathrated preferentially by the host, and the observed selectivity was related to differences in complementary between the host and guest components in each complex. Inclusion compounds were formed between the host and the solid guests (benzenediol and phenylenediamine) by means of solid-solid reactions. The complexes were formed by grinding the two powdered starting components together in a ball mill. The resulting products were analysed by X-ray powder diffractometry. Competition experiments were also performed in the solid state to determine whether the selectivity of the host differed from that observed in solution.
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Li, Yuan-Yao. "Air separation with monolithic adsorbents." Thesis, University of Bath, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242787.
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Gamini, Seneviratne Weerasekara Mudiyanselage. "Phase separation of polymer blends." Thesis, University of Sussex, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293398.
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Clark, Jonathan Edward. "Unique Applications of Nanomaterials in Separation Science." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1282335513.
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Danial, John Shokri Hanna. "Imaging lipid phase separation in droplet interface bilayers." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:34bb015f-2bc1-43bb-bc29-850e0b55edac.
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The spatiotemporal organization of membrane proteins is implicated in cellular trafficking, signalling and reception. It was proposed that biological membranes partition into lipid rafts that can promote and control the organization of membrane proteins to localize the mentioned processes. Lipid rafts are thought to be transient (microseconds) and small (nanometers), rendering their detection a challenging task. To circumvent this problem, multi-component artificial membrane systems are deployed to study the segregation of lipids at longer time and length scales. In this thesis, multi-component Droplet Interface Bilayers (DIBs) were imaged using fluorescence and interferometric scattering microscopy. DIBs were used to examine and manipulate microscopic lipid domains and to observe, for the first time, transient nanoscopic lipid domains. The techniques and results described here will have important implications on future research in this field.
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Chagger, Harnit Kaur. "Carbon molecular sieves for air separation." Thesis, University of Newcastle Upon Tyne, 1994. http://hdl.handle.net/10443/851.
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Carbon is one of the naturally occurring elements and has an atomic weight 12.01 atomic mass units (amu) and atomic number 6. It has six electrons and has an electronic configuration of: ls2 2S2 1p2 in the ground state. This element exists in different crystalline forms-diamond, graphite, buckminsterfullerene1 and carbyne2. Carbon also has the ability of catenation via formation of σ and π bonds.
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Snowden, Martin John. "Phase separation in polymer/particle mixtures." Thesis, University of Salford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293881.
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McCleese, Christopher. "Femtosecond Time-Resolved Spectroscopy Studies of Interfacial Charge Separation Processes." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case149182204612303.
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Leonard, Kinson Stephen. "Metal ion removal by adsorptive bubble separation methods." Thesis, University of Central Lancashire, 1986. http://clok.uclan.ac.uk/20249/.
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The present work involves a study of various parameters which affect the removal of mercury(II) from solution, using a dissolved-air flotation technique. Initially, removal of mercury(II) was achieved from aqueous solution using a laboratory-scale apparatus and optimum removal using various coagulating agents was investigated. The mercury(II) concentration was determined by cold vapour atomic absorption spectrometry. The effect of pH, admitted water volume, coagulation time, and nature and quantity of added tensides and polymeric flocculants was studied using experimentally established optimum removal conditions. The optimum percentage removal achieved using iron(III) chloride, aluininium(III) sulphate and copper(II) sulphide in aqueous solution was 75.6, 33.1 and 99.3, respectively. A major source of mercury(II) in effluents is from depleted brine in the chlor-alkali industry and so removal from solutions containing high chloride ion concentrations was investigated. For solutions containing 17Z w/v sodium chloride, the optimum percentage removal of mercury(II) using iron(IILchlor.idetsodium_sylphi4,_ and copper(II) suiphide was 18.7 and 89.0, respectively. The efficiency of the laboratory process was assessed under industrial conditions by using a pilot plant at a chloralkali works. The optimum percentage removal of mercury(II) using iron(III) chloride, aluminium(III) sulphate and copper(II) sulphide from brine effluent was 92.8, 93.0 and 91.4, respectively. A study was undertaken to investigate the surface chemical interactions of flotation by using a microelectrophoresis technique. Model iron(III) and copper(II) sols were prepared by forced hydrolysis and the effect of pH, tensides and polymeric flocculants on electrophoretic mobility was determined.
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Tavares, Cabral João Pedro Beija. "Polymer mixtures : dynamics, equilibrium & phase separation." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272209.
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Henderson, J. S. "Combined microfiltration and membrane-based affinity separation." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325959.
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Bono, Awang. "Sorptive separation of simple water soluble organics." Thesis, University of Surrey, 1989. http://epubs.surrey.ac.uk/848477/.
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The primary objective of this thesis was to examine the major factors affecting the sorptive separation of simple water soluble organics, eg alcohols, aldehydes, ketones, carboxylic acids, with hydrophobic adsorbents. The model system considered is the separation of aqueous ethanol with an adsorbent formed by pelletizing micron sized hydrophobic silicalite crystals. The structural characteristics of the bi-dispersed silicalite pellets are examined in Chapter 2. The size distribution of the crystals was measured by various techniques and fitted a log-normal distribution with a median size of 3.78 um. The macropore size distribution of the pellets was determined by mercury porosimetry and showed a unimodal distribution with a mean macropore diameter of 0.6 um. The pellets had a macropore volume of 0.202 cm[3]/g, a macropore voidage of 0.26 and a density of 1.285 g/cm[3] . The sorption equilibria for the system {ethanol-water}/silicalite crystals is considered in Chapter 3. The basic difference between vapour and liquid phase sorption and the fundamental constraint caused by the inaccessibility of the adsorbed phase to direct measurement are considered first. This is followed by the development of a novel technique which for the first time enables the direct measurement of the individual adsorption isotherms for microporous solids. Comparison of the measured data with the predictions based on the available theories of adsorption from solution show considerable discrepancy. This is traced to the inherent assumption of no volume change of mixing common to all the proposed theories. For the system {ethanol-water}/silicalite the adsorbed phase exhibits as much as 30% volume change of mixing. The packing density and the total number of molecules adsorbed is therefore a very strong function of composition. Chapter 4 is devoted to a rigorous thermodynamic analysis of the adsorption equilibria for the system {ethanol-waterl/silicalite. The relevant thermodynamic relationships are derived first without any a priori assumption other than the existence of a distinct adsorbed phase. The major significance of the analysis presented is that for the very first time it is based on measured rather than predicted adsorbed phase composition. For the {ethanol-water }/silicalite system, the behaviour of the adsorbed phase is shown to be radically different from that of the bulk solution. The bulk liquid exhibits strong positive deviation from Raoult's law indicating that water-water and ethanol-ethanol molecular interactions dominate over that between unlike species. The adsorbed phase activity coefficients, however, show strong negative deviation from Raoult's law; indicating that ethanol-water interactions overshadow that between the like molecules. The major practical consequence of this observation is that surface modification of the hydrophobic crystals is unlikely to alter the selectivity significantly. The analysis presented also enables a direct thermodynamic consistency test of the adsorption data which has not been previously reported. The models proposed to describe intraparticle mass transfer are critically reviewed in Chapter 5 and the macropore-micropore diffusion model is identified as the most realistic for silicalite pellets. The intracrystalline diffusion rates were measured directly and their analysis reveals fundamental differences between uptake of pure ethanol and pure water consistent with the observed equilibrium behaviour. This information is used to determine the controlling mechanism for mass transfer between a flowing fluid and silicalite pellets. The time constants for external film mass transfer, macropore diffusion and micropore diffusion are estimated at 2.72, 82.32 and 0.07 seconds respectively. The controlling mechanism is therefore macropore diffusion with intracrystalline diffusion playing an insignificant role. This a direct consequence of the small crystal size and the relatively rapid intracrystalline diffusivity of water and ethanol in silicalite. The above information is pulled together in a mathematical model to describe the dynamics of adsorption of ethanol-water mixtures onto a fixed-bed of silicalite pellets. The model allows for axial dispersion, external film mass transfer and describes the intraparticle mass transfer in terms of a macropore diffusion model. The model partial differential equations are solved by the orthogonal collocation technique. A detailed sensitivity analysis is conducted which confirms axial dispersion and external film mass transfer coefficients can be confidently predicted from the available literature correlations. The isotherm is measured independently which leaves only the effective macropore diffusivity to be obtained by matching with experimental breakthrough curve. Such curves were obtained on a carefully designed small pilot adsorption unit with considerable attention to the distortions caused by the entrance and exit effects and the sampling procedures. The effective macropore diffusivity recovered is 4.0x10[-6] cm[2]/s which suggests a tortuosity of 3.2 for the silicalite pellets. This model and the parameter values determined independently provides a valuable tool for future scale-up and design studies.
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Xiong, Pa N. "Polyamines for Separation of Rare Earth Elements and Carbon Dioxide Sequestration." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1468326121.
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Philibert, Gwenaelle Sophie. "Improved Separation of Biological Compounds Using Enhanced-Fluidity Liquid Chromatography." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1322479367.
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Newsome, Toni Elwell. "Development of Electrospun Nanomaterials and Their Applications in Separation Science." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1394798760.
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Soga, K. Geoffrey (Kenneth Geoffrey). "Equilibrium phase separation in polymer brushes." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40445.
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The equilibrium properties of polymers end-grafted to an impenetrable interface, the "polymer brush", are investigated. Relevant concepts and techniques of statistical polymer physics are discussed; in particular, a simulation technique that is very efficient for studying polymer brushes is introduced. This technique is demonstrated through simulations of a well characterized polymer brush system. The results of original investigations of phase separation in polymer brushes are also presented. An instability in the lateral monomer density of a polymer brush is observed under sufficiently poor solvent conditions. The onset of this instability is found to agree with a previous prediction. A compositional instability is found in the lateral densities of a two-component polymer brush under conditions of sufficient immiscibility between the two components. The effects of varying solvent conditions are considered. Finally, the onset of the compositional instability is determined using the technique of the self consistent mean field, and the results compared to simulation.
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Carpenter, Alexis Anne. "The separation of lipoproteins and the determination of cholesterol in human serum /." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74624.
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A flow-injection system is described which employs immobilized cholesterol esterase and cholesterol oxidase for the determination of total serum cholesterol. Hydrogen peroxide generated by the enzymatic reaction is measured directly at a home-made amperometric thin-layer flow-cell held at +600 mV vs Ag/AgCl. Serum samples are passed through an anion exchange resin to remove possible interferences prior to detection. The accuracy and precision of the system were evaluated with the use of certified reference materials for serum cholesterol and were found to conform to the recommended guidelines of the Laboratory Standardization Panel at the National Institutes of Health.The use of sulfated polysaccharides as an affinity medium for the separation of the major classes of lipoproteins with subsequent determination of their cholesterol content was investigated. Several immobilization procedures for the covalent attachment of heparin to controlled-pore glass (CPG) were attempted. Separation of $ alpha$- (high-density) and $ beta$- (low- and very-low-density) lipoproteins was achieved on one of the heparin-CPG preparations and incorporation of this material into a chromatographic system with on-line determination of cholesterol was investigated.
Separation of $ alpha$- and $ beta$-lipoproteins was also achieved using sulfated dextran beads. A simple two-step procedure separates these two fractions in 10 minutes, and the cholesterol content is determined using the flow-injection system described above.
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Dobson, Regina Louise. "Electrocoagulation concept for the separation of ultrafines." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/11855.
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Craige, S. F. "The separation, characterisation, and properties of bitumen constituents." Thesis, Liverpool John Moores University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372076.
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Prangle, Anita Susann. "Chiral drug bioanalysis using reduced-dimension separation systems." Thesis, University of Sunderland, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369863.
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Essery, Richard Lawrence Howard. "Surface effects and anisotropy in polymer phase separation." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240942.
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Akintoye, Ayodele. "Continuous chromatographic biochemical reaction-separation." Thesis, Aston University, 1989. http://publications.aston.ac.uk/9739/.
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Combined bioreaction separation studies have been carried out for the first time on a moving port semi-continuous counter-current chromatographic reactor-separator (SCCR-S1) consisting of twelve 5.4cm id x 75cm long columns packed with calcium charged cross-linked polystyrene resin (KORELA V07C). The inversion of sucrose to glucose and fructose in the presence of the enzyme invertase and the biochemIcal synthesis of dextran and fructose from sucrose in the presence of the enzyme dextransucrase were investigated. A dilute stream of the appropriate enzyme in deionised water was used as the eluent stream. The effect of switch time, feed concentration, enzyme activity, eluent rate and enzyme to feed concentration ratio on the combined bioreaction-separation were investigated. For the invertase reaction, at 20.77% w/v sucrose feed concentrations complete conversions were achieved. The enzyme usage was 34% of the theoretical enzyme amount needed to convert an equivalent amount of sucrose over the same time period when using a conventional fermenter. The fructose rich (FRP) and glucose rich (GRP) product purities obtained were over 90%. By operating at 35% w/v sucrose feed concentration and employing the product splitting and recycling techniques, the total concentration and purity of the GRP increased from 32% w/v to 4.6% and from 92.3% to 95% respectively. The FRP concentration also increased from 1.82% w/v to 2.88% w/v. A mathematical model was developed for the combined reaction-separation and used to simulate the continuous inversion of sucrose and product separation using the SCCR-S1. In the biosynthesis of dextran studies, 52% conversion of a 2% w/v sucrose concentration feed was achieved. An average dextran molecular weight of 4 millIon was obtained in the dextran rich (DRP) product stream. The enzyme dextransucrase was purifed successfully using centrifugation and ultrafiltration techniques.
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Dooley, Chad Johnathan. "New Nanomaterials for Photovoltaic Applications: A Study on the Chemistry and Photophysics of II-VI Semiconductor Nanostructures." Thesis, Boston College, 2009. http://hdl.handle.net/2345/705.
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Thesis advisor: Torsten FiebigThis dissertation examines the chemistry and photophysics of semiconductor quantum dots with the intent of studying their capabilities and limitations as they pertain to photovoltaic technologies. Specifically, experiments are presented detailing the first time-resolved measurements of electron transfer in electronically coupled quantum rods. Electron transfer from the conduction band of CdTe was measured to occur on the 400 fs timescale (kET = 2.5 x 1012 s-1), more than 500x faster than previously believed. Additionally, the direct optical promotion of an electron from the valence band of CdTe was observed, occurring on the timescale of the pump pulse (~50 fs). Based on the determined injection rates, a carrier separation efficiency of > 90% has been calculated suggesting these materials are sufficient for use in solar energy capture applications where efficient carrier separation is critical. To this end, model photovoltaic cells were fabricated, and their power conversion efficiency and photon-to-current generation efficiency characterized. In devices based of CdSe and heteromaterial quantum rods we observed fill-factors on the order of 10-20% though with power conversion efficiencies of < 0.02%. It was discovered that using a high temperature annealing step, while critical to get electrochemically stable photoelectrodes, was detrimental to quantum confinement effects and likely removed any hQR specific capabilities. Additionally, a detailed study on the role of nucleotide triphosphate chemistry in stabilizing emissive CdS nanoparticles is presented. Specifically it was observed that in a neutral pH environment, GTP selectively stabilizes CdS quantum dots with diameters of ~4 nm while the other naturally occurring ribonucleotides do not yield emissive product. The selectivity is dependent on the presence of the nucleophilic N-7 electrons near a triphosphate pocket for Cd2+ complexation as well as an exocyclic amine to stabilize the resulting product particles. However, in an elevated pH environment, the nucleobase specificity is relaxed and all NTPs yield photo-emissive quantum dots with PLQEs as high as 10%
Thesis (PhD) — Boston College, 2009
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
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Katata, Lebogang Maureen. "Separation of readily biodegradable aminocarboxylate complexes by electrodriven methods." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/19537.
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Thesis(PhD)--Stellenbosch University, 2008.ENGLISH ABSTRACT: Aminopolycarboxylic acids (APCAs) are chelating agents widely used to inactivate various metal ions by complex formation in industrial and household applications. Ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) are the widely used agents. Their use is under scrutiny due to their persistence in the environment because they cannot readily biodegrade. This led to the introduction of readily biodegradable agents namely ethylenediaminedisuccinic acid (EDDS) and iminodisuccinic acid (IDS) as alternatives especially to EDTA. Therefore, there was an interest to study the separation of EDDS, IDS and other APCAs using a simple, quick and accurate method. Capillary electrophoresis was used to determine the separation and speciation of iminodisuccinic acid with various metal ions at various pH levels. Speciation modelling was also utilized to compare and validate the presence and distribution of metal-ligand species. The obtained CE results were compared with speciation profiles and a reasonable agreement was obtained. The degradation studies at various time intervals for the metal-ligand (ML) complexes of DTPA, S,S-EDDS, IDS and R,S-IDS with various metal ions (Cd2+, Cr3+, Cu2+, Fe3+, Mn2+, Pb2+ and Zn2+) at pH 7 and 9 was evaluated using CE. New peaks were observed in some ML complexes when the pH was changed from pH 9 to 7. Sharp peaks were seen for CuL (L = DTPA, S,S-EDDS, IDS and R,S-IDS), FeDTPA and FeEDDS at both pH s. While small broad peaks were observed for FeIDS, CrL and MnL complexes. CuDTPA and CuEDDS complexes showed a greater stability over some considerable time as compared to CuIDS, CuR,S-IDS and other metal complexes at pH 9. This work also investigated the effect of various cationic electroosmotic flow (EOF) modifiers and counter anions on the CE separation of EDTA, EDDS and IDS as Cu(II) complexes. The performance of the modifiers was evaluated in terms of migration times, resolution and plate numbers. The best results were observed when Tetradecyltrimethylammonium bromide (TTAB) and Cetyltrimethylammonium bromide (CTAB) was used as modifiers in order to reverse the EOF in the fused silica capillary. This resulted in short analysis time and better peak shapes. The effect of different counteranions attached to EOF modifiers on the separation was also shown. It was also found that the counter anions of EOF modifiers used influences the separation of the complexes. The EOF modifiers namely Cetyltrimethylammonium chloride (CTAC) and Tetradecyltrimethylammonium chloride (TTAC) were further utilized for the determination of EDTA in South African river waters and industrial effluents. A method for the simultaneous separation of Fe (III) complexed with EDTA, S,S -EDDS and IDS was developed by CE and high-performance liquid chromatography (HPLC). The recalcitrant EDTA is used in combination with readily biodegradable analogues like EDDS and IDS in many commercial products. The methodology performance was evaluated in terms of linearity, limit of detection (LOD), limit of quantitation (LOQ) and reproducibility for both CE and HPLC methods. The LOD values obtained from HPLC were low when compared with CE. The applicability of both methods was demonstrated for the analysis of cosmetic products such as foam bath and shower cream. The results obtained by both CE and HPLC were found to be comparable and are in good agreement.
AFRIKAANSE OPSOMMING: Aminopolikarboksiel sure (APCAs) is komplekseer middels wat algemeen gebruik word om verskillende metaal ione te deaktifeer deur kompleks vorming in industriële en huishoudige toepassings. Etileendiamientetraasynsuur (EDTA) en dietileentriamienpentaasyn suur (DTPA) is die mees algemene APCA s. Hul gebruik word deesdae noukerig ondersoek as gevolg van hul volharding in die omgewing. Daar is n intense soektog na bio-afbreekbare agente soos etieleendiamiendisuksien suur (EDDS) and iminodisuksien suur (IDS) wat as plaasvervangers kan dien vir nieafbreekbare EDTA. Daar is dus n behoefte om te kyk na eenvoudige, vinnige en noukeurige metodes vir die bepaling van EDTA, EDTA , IDS en ander APCA s. Kapillere elektroforese (CE) was gebruik vir die skeiding en spesiering van iminodisuksien suur met verskillende metale by verskillende pH s. Spesiasie modellering was ook gebruik om die teenwoordigheid en verspreiding van metaal- spesies te vergelyk. Die CE uitslae was met die spesiasie profiele vergelyk en n redelike ooreenkoms was gevind. Die degraderings studies as n funksie van tyd was met CE bestudeer vir verskillende metal-ligand (ML) samestellings van DTPA, S,S-EDDS, IDS en R,S-IDS met verskillende metal ione (Cd2+, Cr3+, Cu2+, Fe3+, Mn2+, Pb2+ en Zn2+) by pH 7 en 9. Nuwe pieke was opgemerk in sommige ML samestellings wanneer die pH van pH 9 na 7 verander. Hoë pieke was vir CuL (L = DTPA, S,S-EDDS, IDS and R,S-IDS), FeEDTA en FeEDDS by alle pH s gevind. Lae, breë pieke was vir FeIDS, CrL en MnL komplekse gevind. CuDTPA en CuEDDS komplekse het n goeie stabiliteit gewys oor ʼn redelike tyd as dit met CuIDS, CuR,S-IDS en ander metal komplekses by pH 9 vergelyk word. In hierdie werk was die effek van verskillende kationiese elektro-osmotiese stroom (EOF) modifiseerders ook ondersoek. Veral die effek wat teen ioone op die CE skeidings het van EDTA, EDDS en IDS asook Cu(II) komplekse was ondersoek. Die effek van die modifiseerders was ondersoek en ge-evalueer in terme van migrasie tye, resolusie en plaat getalle. Die beste skeidingskondisies was bereik wanneer tetradesieltrimetielammonium bromied (TTAB) and setieltrimetielammonium bromied (CTAB) as modifiseerders gebruik word. Hierdie kondisies het ook aanleiding gegee tot korter ondersoek tye en beter piekvorme. Die effek van verskillende teen ioone wat aan die EOF modifiseerders gekoppel was het ook interresante resultate opgelewer. Die EOF modifiseerders setieltrimetielammonium chloried (CTAC) en tetradesieltrimetielammonium chloried (TTAC) was ook gebruik vir die bepaling van EDTA in Suid Afrikaanse rivier waters en industrieel afloop. ʼn Metode vir die gelyktydige skeiding van Fe(III) met EDTA, S,S’-EDDS en IDS was met behulp van CE en hoedruk vloeistof chromatography (HPLC) ontwikkel. Die metodologie was ondersoek ingevolge lineariteit, limiet van deteksie (LOD), limiet van kwantifisering (LOQ) en die herhaalbaarheid van CE en die HPLC metodes. Die LOD waardes verkry vanaf HPLC was swakker vergeleke met die verkry deur CE. Die toepaslikheid van al die metodes was vir die ontleding van kosmetiese produkte soos bad skuim en stortbad room getoets. Die uitslae deur CE en HPLC was vergelykbaar en ʼn goeie ooreenkoms was gevind.
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Setford, S. J. "Combined bioreaction and separation in centrifugal fields." Thesis, Aston University, 1992. http://publications.aston.ac.uk/9781/.
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The aim of this work has been to investigate the principle of combined centrifugal bioreaction-separation. The production of dextran and fructose by the action of the enzyme dextransucrase on sucrose was employed to elucidate some of the principles of this type of process. Dextran is a valuable pharmaceutical product used mainly as a blood volume expander and blood flow improver whilst fructose is an important dietary product. The development of a single step process capable of the simultaneous biosynthesis of dextran and the separation of the fructose by-product should improve dextran yields whilst reducing capital and processing costs. This thesis shows for the first time that it is possible to conduct successful bioreaction-separations using a rate-zonal centrifugation technique. By layering thin zones of dextrasucrase enzyme onto sucrose gradients and centrifuging, very high molecular weight (MW) dextran-enzyme complexes were formed that rapidly sedimented through the sucrose substrate gradients under the influence of the applied centrifugal field. The low MW fructose by-product sedimented at reduced rates and was thus separated from the enzyme and dextran during the reaction. The MW distribution of dextran recovered from the centrifugal bioreactor was compared with that from a conventional batch bioreactor. The results indicated that the centrifugal bioreactor produced up to 100% more clinical dextran with MWs of between 12 000 and 98 000 at 20% w/w sucrose concentrations than conventional bioreactors. This was due to the removal of acceptor fructose molecules from the sedimenting reaction zone by the action of the centrifugal field. Higher proportions of unwanted lower MW dextran were found in the conventional bioreactor than in the centrifugal bioreactor-separator. The process was studied on a number of alternative centrifugal systems. A zonal rotor fitted with a reorienting gradient core proved most successful for the evaluation of bioreactor performance. Results indicated that viscosity build-up in the reactor must be minimised in order to increase the yields of dextran per unit time and improve product separation.
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Taddei, L. E. M. "Bioreaction and separation in batch chromatographic columns." Thesis, Aston University, 1994. http://publications.aston.ac.uk/9768/.
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The objective of this work has been to study the behaviour and performance of a batch chromatographic column under simultaneous bioreaction and separation conditions for several carbohydrate feedstocks. Four bioreactions were chosen, namely the hydrolysis of sucrose to glucose and fructose using the enzyme invertase, the hydrolysis of inulin to fructose and glucose using inulinase, the hydrolysis of lactose to glucose and galactose using lactase and the isomerization of glucose to fructose using glucose isomerase. The chromatographic columns employed were jacketed glass columns ranging from 1 m to 2 m long and the internal diameter ranging from 0.97 cm to 1.97 cm. The stationary phase used was a cation exchange resin (PUROLITE PCR-833) in the Ca2+ form for the hydrolysis and the Mg2+ form for the isomerization reactions. The mobile phase used was a diluted enzyme solution which was continuously pumped through the chromatographic bed. The substrate was injected at the top of the bed as a pulse. The effect of the parameters pulse size, the amount of substrate solution introduced into the system corresponding to a percentage of the total empty column volume (% TECV), pulse concentration, eluent flowrate and the enzyme activity of the eluent were investigated. For the system sucrose-invertase complete conversions of substrate were achieved for pulse sizes and pulse concentrations of up to 20% TECV and 60% w/v, respectively. Products with purity above 90% were obtained. The enzyme consumption was 45% of the amount theoretically required to produce the same amount of product as in a conventional batch reactor. A value of 27 kg sucrose/m3 resin/h for the throughput of the system was achieved.
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Patel, N. M. "Speciation and separation of fission product rhodium." Thesis, Loughborough University, 1985. https://dspace.lboro.ac.uk/2134/7406.
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The rhodium speciation in nitric acid has been identified, primarily by the use of 103Rh Nuclear Magnetic Resonance Spectroscopy. The results have indicated that the rhodium species in stored high level waste (HLW) will range from the hexaaquo ion, {Rh(H20)6}3+-to complexes of the general formula {Rh(H20)6-n(NO2)nl(3-n)+, depending on the nitrite ion concentration. The solvent extraction of these complexes by dinonylnaphthalene sulphonic acid and various organo-phosphine sulphides has been investigated, and an integrated scheme for recovering rhodium from HLW is proposed.
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Kim, Theodore Joon. "In Situ Dielectric Monitoring and Kinetic Analysis of Phase Separation." W&M ScholarWorks, 1993. https://scholarworks.wm.edu/etd/1539625805.
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VitreÌ, CeÌcile. "Silica based solid supports for synthesis and separation." Thesis, University of Southampton, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274655.
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Robson, William. "The separation of the polar constituents of petroleum." Thesis, University of Plymouth, 2018. http://hdl.handle.net/10026.1/12226.
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Identification of the heteroatom (nitrogen, sulphur, and oxygen; NSO)-containing compounds of petroleum is of key importance when considering industrial and environmental issues associated with crude oil production. The inherent molecular complexity of petroleum is such that detailed compositional investigations must ideally be preceded by some form of pre-fractionation. However, the more commonly performed methods of crude oil fractionation are often insufficient in the extent to which they separate oils, not allowing defined “molecular” fractions to be obtained and thus hindering more detailed investigations. The following work therefore focused on the development of chromatographic methods to aid in the characterisation of NSO compounds present within crude oils. A novel solid phase extraction (SPE) procedure was developed utilising both ion exchange and adsorption chromatography. The method enabled fractions broadly defined as ‘saturated’ hydrocarbons; ‘aromatic’ hydrocarbons; basic nitrogen compounds; naphthenic acids; phenols and other oxygen-containing species; carbazoles; sulfoxides; and thiophenes, to be isolated reproducibly and quantitatively from relatively small crude oil samples (~ 0.5 g). Assessment of method selectivity with a suite of ‘model’ compounds showed that the resulting fractions were quite well defined, with classes of ‘model’ compounds being isolated within discrete fractions. Application to five crude oils of widely varying properties and origins, such as API gravity (12.1−38.3°), demonstrated the potential for the wide-ranging use of the method. Sample recoveries were high (77−98%) with simple evaporative losses accounting for the majority of sample loss. Repeatability was also high, demonstrated by triplicate analyses of ‘model’ compound mixtures, oils spiked with ‘model’ compounds and oils alone. Subsequent, more detailed, analysis of the fractions using multidimensional gas chromatography-mass spectrometry (GC×GC-MS) and liquid chromatography-highresolution accurate mass-mass spectrometry (LC-HRAM-MS) showed the advantages of the new isolation method. For example, alkylated series (C1-5) of quinolines, carbazoles, fluorenones, dibenzothiophenes and xanthones were identified within their predicted fractions. Furthermore, comparison of mass spectra obtained from GC×GC-MS analyses with reference spectra resulted in the tentative identification of compounds hitherto not previously reported in crude oils, again illustrating the advantage of the isolation method. Novel series of thioxanthones, tocopherols (E vitamins) and terpenoidal sulfoxides and ketones were assigned within the isolated fractions. Following the successful evaluation of the method, the scheme was subsequently employed to investigate the effects of changing geochemical parameters on the composition of isolated NSO-containing compounds. For example, studies of NSO fractions from series of crude oils at different stages of thermal maturity or of biodegradation, led to the identification of a number of potential new molecular markers within the basic-nitrogen and ketone fractions. This work shows clear potential for the developed NSO isolation method to be used in further compositional studies as a tool to aid in geochemical investigations.
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Lifsey, Karen Marie. "Liquid crystal polymers : a unique class of separation media." Thesis, University of East Anglia, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365163.
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Meeson, Stephen Russell. "The separation of enantiomers by high performance liquid chromatography." Thesis, University of Newcastle Upon Tyne, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278414.
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Ruddick, Andrew. "Separation and mobility modelling of biopolymers by capillary electrophoresis." Thesis, University of York, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338551.
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Rossi, Sara. "Enantioselective receptors for racemate separation of amino acids' derivatives." Thesis, University of Southampton, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289912.
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Hemström, Petrus. "Hydrophilic Separation Materials for Liquid Chromatography." Doctoral thesis, Umeå universitet, Kemi, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1350.
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The main focus of this thesis is on hydrophilic interaction chromatography (HILIC) and the preparation of stationary phases for HILIC. The mechanism of HILIC is also discussed; a large part of the discussion has been adapted from a review written by me and professor Irgum for the Journal of Separation Science (ref 34). By reevaluating the literature we have revealed that the notion of HILIC as simply partitioning chromatography needed modification. However, our interest in the HILIC mechanism was mainly inspired by the need to understand how to construct the optimal HILIC stationary phase. The ultimate stationary phase for HILIC is still not found. My theory is that a non-charged stationary phase capable of retaining a full hydration layer even at extreme acetonitrile (> 85%) concentrations should give a HILIC stationary phase with a more pure partitioning retention behavior similar to that of a swollen C18 reversed phase. The preparation of a sorbitol methacrylate grafted silica stationary phase is one of our attempts at producing such a stationary phase. The preparation of such a grafted silica has been performed, but with huge difficulty and this work is still far from producing a column of commercial quality and reprodicibility. This thesis also discusses a new method for the initiation of atom transfer radical polymerization from chlorinated silica. This new grafting scheme theoretically results in a silica particle grafted with equally long polymer chains, anchored to the silica carrier by a hydrolytically stable silicon-carbon bond. The hydrolytic stability is especially important for HILIC stationary phases due to the high water concentration at the surface.
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Lloyd, Michael C. "Novel materials for membrane separation processes." Thesis, Aston University, 1995. http://publications.aston.ac.uk/9680/.
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The aim of this work was to synthesise a series of hydrophilic derivatives of cis-1,2-dihydroxy-3,5-cyclohexadiene (cis-DHCD) and copolymerise them with 2-hydroxyethyl methacrylate (HEMA), to produce a completely new range of hydrogel materials. It is theorised that hydrogels incorporating such derivatives of cis-DHCD will exhibit good strength and elasticity in addition to good water binding ability. The synthesis of derivatives was attempted by both enzymatic and chemical methods. Enzyme synthesis involved the transesterification of cis-DHCD with a number of trichloro and trifluoroethyl esters using the enzyme lipase porcine pancreas to catalyse the reaction in organic solvent. Cyclohexanol was used in initial studies to assess the viability of enzyme catalysed reactions. Chemical synthesis involved the epoxidation of a number of unsaturated carboxylic acids and the subsequent reaction of these epoxy acids with cis-DHCD in DCC/DMAP catalysed esterifications. The silylation of cis-DHCD using TBDCS and BSA was also studied. The rate of aromatisation of cis-DHCD at room temperature was studied in order to assess its stability and 1H NMR studies were also undertaken to determine the conformations adopted by derivatives of cis-DHCD. The copolymerisation of diepoxybutanoate, diepoxyundecanoate, dibutenoate and silyl protected derivatives of cis-DHCD with HEMA, to produce a new group of hydrogels was investigated. The EWC and mechanical properties of these hydrogels were measured and DSC was used to determine the amount of freezing and non-freezing water in the membranes. The effect on EWC of opening the epoxide rings of the comonomers was also investigated
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Wang, Jinyan, and Jinyan Wang. "Development of Novel Separation and Sensor Platforms Based on Polymerized Phospholipid Vesicles." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/621293.
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Analyte-membrane and analyte-membrane receptor interactions are related to drug absorption through transmembrane diffusion and cellular signal transduction, respectively. Therefore, the study of these interactions plays key roles in new drug development. Membrane-based chromatography using artificial phospholipid vesicles as stationary phases provides a high-throughput approach to screen analyte-membrane interactions. Additionally, by incorporating membrane receptors into the vesicle stationary phases, analyte-membrane receptor interactions can be studied. However, the inherent instability of artificial phospholipid vesicles limits their application. This work has explored the utilization of polymerized phospholipid vesicles in developing highly stable separation and sensing platforms based on analyte-membrane or analyte-membrane receptor interactions. The processes of vesicle polymerization using polymerizable lipids and polymer scaffolding are also characterized and optimized.In order to improve the stability of stationary phases in membrane-based chromatography, polymerized phospholipid vesicles made of polymerizable bis-SorbPC lipids were covalently immobilized on the inner wall of silica capillaries to serve as stationary phases. The polymerized vesicle stationary phases showed enhanced stability against drying/rehydration and shear forces compared to non-polymerizable counterparts. Aliphatic amines were separated using the polymerized vesicle stationary phases based on their different interactions with the vesicle membranes in both open-tubular capillary liquid chromatography (CLC) and capillary electrochromatography (CEC) formats. This application broadens the range of membrane-based stationary phases to include polymerized phospholipid vesicles, which provide enhanced stability. Biosensors that detect ligands based on ligand-receptor interactions using artificial phospholipid vesicles generally do not allow ligand identification. A pull-down assay was developed using novel silica core-polymerized vesicle shell particles combined with MALDI-MS for the simultaneous detection and identification of peptide/protein ligands that bind to membrane receptors. The polymerized vesicle shell survived MS vacuum conditions and showed higher stability against organic solvent treatment compared to non-polymerizable counterparts. As a proof of concept, cholera toxin binding subunit (CTB) was successfully detected using ganglioside GM1-functionalized core-shell particles. The assay has the potential to differentiate among multiple ligands that bind to the same receptor and identify unknown ligands in a complex ligand mixture.In addition to using polymerizable lipids, polymer scaffolding is also used to stabilize phospholipid vesicles, although the formation of polymer scaffolds in nanometer-sized vesicles is difficult to characterize. Polymer scaffolds were successfully synthesized inside vesicles composed of non-polymerizable DOPC lipids (100-200 nm in diameter), by doping small molecule linear monomers and cross-linkers into the vesicle lamellar region followed by photochemical initiation. It was found that DOPC vesicles containing polymer scaffolds formed by different linear monomers showed similar stability against surfactant treatment. This study adds new insights to the current understanding and characterization of the polymer scaffolding process.
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Castagnola, Norma B. "Spectroscopic studies and photochemical charge separation in Zeolite encapsulated donor-acceptor systems /." The Ohio State University, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488190595942664.
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Grant, Christine Sharon. "Surfactant enhanced electro-osmotic dewatering of mineral ultrafines." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/11704.
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Kumar, Parveen. "Inclusion chemistry in periodic mesoporous hosts growth of quantum-confined materials and gas separation membranes /." Cincinnati, Ohio : University of Cincinnati, 2007. http://www.ohiolink.edu/etd/view.cgi?ucin1186772727.
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Thesis (Ph. D.)--University of Cincinnati, 2007.Advisor: Dr. Vadim V Guliants. Title from electronic thesis title page (viewed Dec. 6, 2007). Includes abstract. Includes bibliographical references.