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1
Silva, Pedro. "Organic solvent nanofiltration (OSN) modelling : from pure solvents to highly rejected solutes." Thesis, Imperial College London, 2007. http://hdl.handle.net/10044/1/11906.
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Blasucci, Vittoria Madonna. "Organic solvents for catalysis and organic reactions." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31723.
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Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2010.Committee Chair: Charles Eckert; Committee Co-Chair: Charles Liotta; Committee Member: Amyn Teja; Committee Member: Christopher Jones; Committee Member: William Koros. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Böcking, Axel [Verfasser]. "Membrane Transport Properties and Process Design in Nanofiltration with Organic Solvents and Aqueous Solvent Mixtures / Axel Böcking." Düren : Shaker, 2020. http://d-nb.info/1213472598/34.
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Zobel, Mirijam [Verfasser], and Reinhard [Akademischer Betreuer] Neder. "Nanoparticle crystallization and solvent interface restructuring especially for ZnO nanoparticles in organic solvents / Mirijam Zobel. Gutachter: Reinhard Neder." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2016. http://d-nb.info/1081544090/34.
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Chun-Te, Lin Justin. "Organic solvent nanofiltration membrane cascades for solvent exchange and purification." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/11977.
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Oliveira, Flavia Lucia Bottini Omena de. "Avaliação da indução de cristalinidade de policarbonato." Universidade do Estado do Rio de Janeiro, 2008. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=2895.
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Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de JaneiroNeste trabalho foram investigados os comportamentos térmico e mecânico e as características morfológicas de amostras de policarbonato de bisfenol-A (PC) com cristalinidade induzida por exposição ao vapor de solvente. A técnica de indução de cristalização foi empregada em três amostras de policarbonato de bisfenol-A de diferentes massas molares. Filmes vazados a partir de soluções de PC em clorofórmio e amostras moldadas por compressão foram expostos a um ambiente contendo vapor de acetona. Os filmes foram expostos por diferentes períodos de tempo e analisados em equipamentos de Calorimetria Diferencial de Varredura, Microscopia Óptica com luz polarizada e Espectroscopia na Região do Infravermelho com Transformada de Fourier, para caracterizar a indução de cristalinidade. A indução de cristalinidade foi confirmada e a fase cristalina apresentou estrutura esferulítica. As amostras de maior massa molar mostraram maior teor de cristalinidade. O desempenho mecânico das amostras cristalinas de policarbonato mostrou diferenças, com a mudança de seu comportamento mecânico de dúctil para frágil, independente da massa molar
In this work were investigated the thermal and mechanical behaviors and the morphological characteristics of bisphenol-A polycarbonate (PC) samples with crystalline induction by solvent vapor exposure. The crystallization induction technique was employed on three samples of bisphenol-A polycarbonate of different molar mass. Films cast from PC solutions in chloroform and compression molded samples were exposed to an environment containing acetone vapor. The films were exposed for different periods of time and analyzed on Differential Scanning Calorimeter, Polarized Light Optical Microscope and Fourier Transform Infra Red devices to characterize crystalline induction. The crystalline induction was confirmed and the crystalline phase has presented spherulitic structure. The highest molar mass samples have shown higher crystallinity degrees. Mechanical performance of crystalline samples has shown differences with the change of its mechanical behavior from ductile to fragile, independently of the molar mass
7
Sommerville, Douglas R. "Diffusion of ethanol in organic solvents." Thesis, Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/19449.
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Jene, Quitz. "Surfactant-modified enzymes in organic solvents." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385432.
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Sherwood, James. "Bio-based solvents for organic synthesis." Thesis, University of York, 2013. http://etheses.whiterose.ac.uk/4999/.
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Scrutiny over solvent selection in the chemical industry has risen in recent decades, popularising research into neoteric solvent systems such as ionic liquids and supercritical fluids. More recently bio-based solvent products have been considered as replacements for conventional petroleum derived solvents. Because they bear a close resemblance to existing solvent products, bio-based solvents can be readily absorbed into the fine chemical industries. This work develops a methodology for identifying reactions of concern with respect to current solvent selection practice, and then implementing a high performance bio-based solvent substitute. In this thesis, kinetic studies of heteroatom alkylation, amidation, and esterification are documented, and the solvent effect dictating the rate of each reaction ascertained. With the ideal properties for the solvent known, bio-based solvent candidates were screened for suitability in each case study. This process, which employs computational tools, was also applied to model the productivity of the Biginelli reaction as a representative multi-component heterocycle synthesis. A strong case is made for limonene and p-cymene as bio-based solvents for all but heteroatom alkylation from the case studies listed above. Alkylations with nitrogen nucleophiles are instead suited to high polarity solvents, and to this end some bio-based amides were investigated.
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Zhang, Shulin. "Studies of Solvent Displacement from Solvated Metal Carbonyl Complexes of Chromium, Molybdenum, and Tungsten." Thesis, University of North Texas, 1990. https://digital.library.unt.edu/ark:/67531/metadc331992/.
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Flash photolysis techniques were applied to studies of solvent displacement by Lewis bases (L) from solvated metal carbonyl complexes of Cr, Mo, and W. On the basis of extensive studies of the reaction rate laws, activation parameters , and linear-free-energy-relationships, it was concluded that the mechanisms of solvent displacement reactions depend on the electronic and steric properties of the solvents and L, as well as the identities of the metal atoms. The strengths of solvent-metal bonding interactions, varying from ca. 7 to 16 kcal/mol, and the bonding "modes" of solvents to metals are sensitive to the structures of the solvent molecules and the identities of the metal centers. The results indicate dissociative desolvation pathways for many arene solvents in (solvent)Cr(CO)_5 (solvent = benzene, fluorobenzene, toluene, etc.) complexes, and are consistent with competitive interchange and dissociative pathways for (n-heptane)M(CO)_5. Different types of (arene)-Cr(CO)_5 interactions were suggested for chlorobenzene (CB) vs. fluorobenzene and other non-halogenated arenes, i.e. via σ-halogen-Cr bond formation in the CB solvate vs. π-arene-Cr bond formation through "isolated" double bonds in solvates of the other arenes. The data also indicate the increasing importance of interchange pathways for solvent displacement from the solvates of Mo and W vs. that of Cr.
11
Stawikowska, Joanna. "Characterisation of organic solvent nanofiltration membranes." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/14732.
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Interests in application of organic solvent nanofiltration (OSN) technology based on synthetic membranes to molecular separation processes have been growing rapidly in recent years. The main classes of OSN flat sheet polymeric membranes are integrally skinned asymmetric (ISA) and thin film composite (TFC) membranes. A general goal of OSN membrane research is to improve membrane performance for specific non-aqueous applications, or to develop new separation processes. Most of the time the research is performed via trial–and–error methods, leading to extension of development time and increase of costs. This is partially because the structure of OSN membranes, particularly the size of their permeation pathway is largely unknown. The filtration characteristics are mainly determined by the membrane structure, which is dependent on various fabrication methods as well as polymer chemistry. However, a direct correlation between these factors has not been understood in detail, because the current characterisation techniques have limitations in studying polymer structures with dimensions at the macromolecular level. The pore size in nanofiltration (NF) membranes is believed to be less than 2 nm, which is a lengthscale at the edge of most available material characterisation techniques. For this reason, advanced methods to study the membrane morphology need to be explored or developed with the aim of elucidating the NF membrane structure, transport mechanisms, and to understand the relationship between the membrane structure and the separation characteristics. These objectives guided the work to development of a nanoscale characterisation method based on imaging the porous regions via probing the NF pores with nanoparticles (NP). Given that the probes provide high electron contrast, it is possible to map the pores formed between the polymer entanglements in the transmission electron microscope (TEM). This technique measures the pore size in situ, thus, a membrane is characterised during its operational state. The pore size was found to correlate well with the solute rejection and flux measured for a range of ISA and TFC membranes. The pore size distributions were then used together with a pore–flow model to simulate rejection curves. A further insight into the membrane structure, particularly the surface structure, was provided by atomic force microscopy (AFM), particularly phase imaging. This method was applied to characterisation of polymer packing at the membrane surface, leading to analysis of the correlations between the phase shift, filtration parameters and membrane preparation methods.
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See, Toh Yoong Hsiang. "Molecular separations with organic solvent nanofiltration." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/11320.
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This thesis firstly describes the application of organic solvent nanofiltration (OSN) in the recycle of asymmetric hydrogenation catalysts through the retention of the (often) larger catalyst whilst allowing the smaller products to penneate. This improves the catalyst tum over number (TON) and the further addition of the ionic liquid (IL) CyPhoslOl markedly improves the enantiomeric excess in the asymmetric hydrogenation of dimethyl itaconate using Ru-BINAP. The high molecular weight of the catalyst and IL allows them to be simultaneously recycled using an OSN membrane. Although this work identifies significant potential to further the application of OSN in homogeneous catalyst recycle, there is a lack of commercially available OSN membranes with good chemical stability across a range of organic solvents and with the ability to separate compounds in the NF range of 200-1000 g morl. The central part of this thesis addresses these issues through the development of various integrally skinned asymmetric polyimide OSN membranes. A consistent method to describe the penneation property of the molecular weight cut off (MWCO) has been developed. This allows the detennination of membrane performance and integrity across a range of different membranes and solvents. The variation of membrane separation perfonnance across the NF range has been achieved through cfanging various membrane fonnation parameters. Crosslinking of these membranes significa~tly enhances the chemical stability allowing stable perfonnances in a range of organic solvents including polar aprotic solvents. Coupling chemical crosslinking with the fonner methodology simultaneously improves the membrane chemical stability and allows membranes to be tailored for specific separations. Finally, this work also examines some initial steps leading to the scale up of OSN membranes to pilot scale through the use of spiral bound elements.
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Low, Jian-Shen. "A study of organic solvent nanofiltration." Thesis, Loughborough University, 2009. https://dspace.lboro.ac.uk/2134/35066.
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This thesis is concerned with the principal features of solvent resistant nanofiltration (SRNF), and in particular its potential in fuel processing. In the recent and more established literature, dense polydimethylsiloxane (PDMS) has been identified as a potential SRNF membrane with separation properties at a molecular level. This thesis investigates the transport and separation mechanisms of dense PDMS membranes in SRNF applications relating to the filtration of organic solvents (mixtures are mixed to simulate fuel). Simulated fuels were created which comprised representative organic solvents with organometallic (OM) and poly-nuclear aromatic (PNA) solutes. The solvent flux and solute rejection behaviour of the solvent-solute systems were studied using a cross-flow air-driven filtration apparatus and a range of operating regimes.
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Pilissão, Cristiane. "Aminólise enantiosseletiva do (R,S)-mandelato de metila e síntese do acetato de geranoíla mediada por lipases." Florianópolis, SC, 2006. http://repositorio.ufsc.br/xmlui/handle/123456789/89096.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas. Programa de Pós-Graduação em Química.Made available in DSpace on 2012-10-22T16:41:45Z (GMT). No. of bitstreams: 1 235685.pdf: 1733584 bytes, checksum: 300d8602199004129acc4b1fc6eca375 (MD5)
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Fuente, Adrian. "Auditory damage associated with solvent exposure evidence from a cross-sectional study /." Thesis, Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/b4020375x.
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Böcking, Axel [Verfasser], Matthias [Akademischer Betreuer] Wessling, and Jens-Uwe [Akademischer Betreuer] Repke. "Membrane transport properties and process design in nanofiltration with organic solvents and aqueous solvent mixtures / Axel Böcking ; Matthias Wessling, Jens-Uwe Repke." Aachen : Universitätsbibliothek der RWTH Aachen, 2020. http://d-nb.info/1218787872/34.
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Sanvoisin, Jonathan. "Biotransformations using lipase enzymes in organic solvents." Thesis, Durham University, 1993. http://etheses.dur.ac.uk/5647/.
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Enzymatic transformations in organic solvents have received increasing attention over the past 10 years and lipases have become by far the most popular enzymes in this area.The initial aim of the research was to assess the effect of small modifications to the acyl donor in the transesterification reactions mediated by the Candida cylindracea lipase. 2.2.2-Trichloroethyl butyrate (TCEB) was used as a standard for the rate studies. In the event the acyl donor, trichloroethyl methoxyacetate (TCEMA), accelerated the transesterification reaction with hexan-1-ol by an order of magnitude over that with TCEB. This observation, and the absence of an acceleration with trichloroethyl methoxypropionate (and ethyl 2- fluorobutyrate over ethyl butyrate) suggested that the effect is due to the ~oxygen. A solvent activity profile indicated that the most hydrophobic solvents supported faster initial rates. This was attributed to the ability of the hydrophilic solvents to strip the hydrated water from the enzyme surface thus deactivating it. The switch to organic solvents allowed a wider temperature range to be studied. For the reactions between heptan-2-ol and TCEMA the reaction could be conducted in the temperature range -23 C to 80 C. It was of interest to assess how the alcohol moiety effected the transesterification reaction. A series of alcohols were presented to the enzyme and a pattern emerged with substrates containing an acetylene functionality being processed faster than those with a vinyl group, which were faster than those containing a methyl group (all other groups being the same). A series of heterocyclic alcohols were presented to the enzyme and it was observed that the order of reaction was thiophene > furan > pyridyl. The secondary alcohols in this series, 2-thiopheneethan-1-ol and o pyridylethan-1-ol, were resolved at various temperatures from -1soc to sooc with no variation in. enantioselectivity. These are the first resolutions to be accomplished at temperatures below zero degrees.
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Cherry, Nicola. "Organic brain damage and occupational solvent exposure." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60012.
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309 cases of organic dementia, cerebral atrophy or psycho-organic syndrome, admitted for 5 days or more to one of 18 Quebec hospitals, were individually matched to a psychiatric referent, admitted with some other diagnosis, and a general hospital referent. Lifetime occupational history was obtained by telephone. Occupational solvent exposure was assessed by (i) individual ratings blind to case status and (ii) a job-exposure matrix. Subjects working with moderate or high solvent concentrations for at least 10 years were considered exposed. With the psychiatric referent series an odds ratio of 1.44 (90% CI 1.03-2.01) was calculated for individual exposure ratings and 1.41 (90% CI 0.89-2.23) for the job matrix. The increased risk was found largely in those with diagnoses of both organic dementia or cerebral atrophy and an alcohol related condition. A similar pattern of risk was found with the general hospital referents. Adjustment for possible confounders did not appreciably alter the risk estimates.
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Lazuen-Garay, A. "Solvent-free synthesis of metal-organic frameworks." Thesis, Queen's University Belfast, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546378.
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Silva, Marta Sofia Fragoso da. "Polyimide and polyetherimide organic solvent nanofiltration membranes." Master's thesis, FCT - UNL, 2007. http://hdl.handle.net/10362/1133.
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Integrally asymmetric skinned Lenzing P84 and Matrimid 5218 polymide membranes and Ultem
1000 polyetherimide membranes were prepared. Crosslinking of membranes using aliphatic
diamines resulted in marked improvement in chemical stability. This however resulted in a
decline in flux with only Lenzing P84 demonstrating good flux in DMF. Further variation of
membrane dope parameters and operating conditions allowed for good control of the MWCO of
membranes made from Lenzing P84. SEM pictures of Lenzing P84 membranes revealed a
significant difference in membranes morphology. The presence of macrovoids increased when
using more DMF in the dope solution. These studies demonstrate the possibility of developing
OSN membranes using different polyimides and opens up future possibilities for controlling the
MWCO of these membranes. Preliminary modelling demonstrates that good control of the
MWCO could extend the application of OSN membranes to allow the fraction of molecules in
the NF range.
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Marchetti, Patrizia. "Organic solvent nanofiltration in the peptide industry." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/11651.
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In recent years the application of membrane technology to molecular separation processes has stimulated interest and showed great potential in a number of industrial fields. Ultrafiltration membranes have been successfully applied to downstream separation of therapeutically active peptides, to overcome some of the limitations of the conventional techniques in terms of costs, scale-up, selectivity and solvent recovery. In this research project, Organic Solvent Nanofiltration of peptide solutions is studied, and this understanding is applied to the development of innovative membrane-based purification strategies for industrial case studies. Basic understanding of transport mechanisms was approached by investigating solvent transport through ceramic nano- and ultrafiltration membranes, and developing a predictive phenomenological model for the transport of solvents and solvent mixtures. Effects of solvent-membrane interactions strongly affected the solvent permeation through nanofiltration membranes, while they were found to be negligible in the ultrafiltration range. The effect of the organic solvent on the permeation of neutral and charged solutes (monovalent salts, a small molecule and peptides) in organic/water mixtures was studied, with particular attention to the role of preferential solvation in the solvent mixture. It was found that the solvent composition and the complex association of counter-ions and buffers highly affect membrane permeation and rejection of organic molecules. It is proposed that all these components change the relative solute-membrane affinity. Since permeation of peptides in organic/water mixtures is affected by complicated matrices of input parameters, a Design of Experiment approach was proposed to efficiently investigate the nanofiltration of model peptides in acetonitrile/water solutions. Statistical models for solvent flux, peptide and ion rejection were obtained by Analysis of Variance and interpreted from a phenomenological point of view. The statistical models were used to asisst process development for two industrial case studies: (1) concentration and salt/solvent exchange of a first therapeutic peptide were optimised, based on the integration of the statistical DoE models with the process simulation for concentration and diafiltration; (2) the nanofiltration-assisted synthesis of a second therapeutic peptide, based on the coupling between nanofiltration and reaction in one unique process, was developed and compared to the established process by techno-economical analysis. The so-called "Reactive Peptide Nanofiltration" was found to be advantageous in terms of economics, efficacy, impact on the market, and on the environment. In conclusion, nano ltration was found to be a solid and competitive technique for application to peptide processes. On the basis of the results of this research, Lonza decided to invest in a new nano ltration plant for the downstream of peptides with ceramic membranes. The advantages of nanofiltration technology, in terms of development of more efficient materials (stable in critical solvents and harsh acid/basic conditions), improvement of membrane performances (selectivity, lifetime) and integration of nanofiltration with other techniques in hybrid processes seem therefore promising in overcoming the hesitancy of industries to modify the established processes and invest in new nano ltration plants, by making the payback period for the return of investment more attractive. It is plausible to think that this technology will shortly become a primary choice for new separation and purification processes.
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Gupta, Abhinaba. "Polydicyclopentadiene : a novel organic solvent nanofiltration membrane." Diss., University of Iowa, 2012. https://ir.uiowa.edu/etd/3460.
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Macroscopic, hollow thimbles were synthesized from dicyclopentadiene with the Grubbs second generation catalyst at a monomer:catalyst loading of 10,000:1. A series of Buchwald-Hartwig and Sonogashira coupling reactions were completed on the interior of the thimbles followed by extraction of the product to the exterior using hexane. In all examples, palladium was retained by the membranes at ≥99.9% levels. Both polar and apolar molecules with molecular weights from 101 to 583 g mol-1 permeated these thimbles with values for flux of 10-5 to 10-6 mol cm-2 h-1, but selected molecules did not permeate them and had flux values 104 to 105 times slower. The difference in flux was large between molecules that permeated and those that did not permeate, but no trend was observed that correlated flux with molecular weight or hydrophobicity. Rather, molecules that did not permeate the membranes had large cross-sectional areas that led to low rates of diffusion within the highly cross-linked polydicyclopentadiene membranes.
Membranes were fabricated from the ring opening metathesis polymerization of dicyclopentadiene with the Grubbs first generation catalyst at a monomer:catalyst loading of 5,000:1. Mixtures of fatty acid salts were separated using polydicyclopentadiene membranes. Mixtures of fatty acids could not be separated by the membranes, but when triisobutylamine was added to the fatty acids, cis-fatty acid salts had slower permeation though the membranes than saturated and trans-fatty acid salts. Oleic, petroselinic, vaccenic, linoleic, and linolenic acid salts with triisobutylamine had slower permeation relative to the permeation of stearic and elaidic acid salts.
Organic catalysts were retained from organic molecules using nanoporous polydicyclopentadiene membranes. Acid or base was added to organic catalysts that increased the critical areas of the organic catalysts to the size range (>0.5 nm2) where PDCPD membranes could retain them. The catalysts by themselves were too small to be retained by the membrane, but the salts were in the range where PDCPD retains molecules.
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Nascimento, Jefferson Patrício. "Esfoliação química do grafite natural em misturas de solventes orgânicos: a obtenção de grafenos de poucas camadas." CNEN - Centro de Desenvolvimento da Tecnologia Nuclear, Belo Horizonte, 2013. http://www.bdtd.cdtn.br//tde_busca/arquivo.php?codArquivo=280.
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O grafeno é um material bidimensional (2D) com espessura monoatômica, formado por
átomos de carbono com hibridização sp2. Ele é a base das estruturas grafíticas, como os fulerenos,
os nanotubos de carbono e o grafite, possuindo excepcionais propriedades eletrônicas, térmicas,
mecânicas e ópticas. Entre os métodos de obtenção do grafeno, a esfoliação química do grafite em
fase líquida é altamente promissora, pois pode ser escalonada, possibilitando a produção de grandes
volumes. Além disso, apresenta alta versatilidade em termos de funcionalização química do grafeno
e produção de filmes finos para a confecção de compósitos e de eletrodos transparentes e
condutores.
Desde que as singulares propriedades mecânicas e condutoras das nanoestruturas de carbono
estão associadas a espécies individuais isoladas, a dispersão e estabilização de grafenos em
diferentes líquidos são de extrema importância em estudos fundamentais e aplicados. Para tal, o
potencial atrativo entre as folhas no grafite deve ser balanceado por um potencial repulsivo. Assim,
o custo energético das interações grafeno-solvente, que depende fortemente do material de partida e
das propriedades dielétricas do meio, precisa ser entendido.
Teorias de solubilidade têm sido recentemente aplicadas a nanoestruturas de carbono. Neste
estudo, usamos os parâmetros de solubilidade de Hansen para a proposição de solventes e misturas
capazes de esfoliar em fase líquida o grafite natural da empresa Nacional de Grafite Ltda..
Utilizando um algoritmo no Matlab baseado nos parâmetros de solubilidade de Hansen,
selecionou-se cinco misturas de solventes orgânicos, onde o clorofórmio é um dos componentes. O
grafite natural na forma bruta e pré-esfoliada foi esfoliado em dispersões estáveis de grafenos, as
quais foram caracterizadas por espectroscopia no UV-Vis e Raman, MET e DLS.
As dispersões produzidas nas misturas de menor valor de D0, apesar de apresentarem uma
menor concentração de material disperso, apresentaram flakes de tamanho maior e com poucas
camadas de grafeno. Já nas misturas com maior valor de D0, observou-se uma maior concentração
de material disperso, com grafenos de dimensões maiores e menores, porém com maior número de
camadas.Graphene is a two-dimensional material (2D) composed by a monoatomic thickness sheet of carbon atoms with sp2 hybridization. It is the basis of graphitic structures, such as fullerenes, carbon nanotubes and graphite, possessing exceptional electronic, thermal, mechanical and optical properties. The method of graphene obtention through graphite exfoliation in liquid phase is highly promising because it can be staggered, allowing the production of large quantities. In addition, it presents high versatility in terms of chemical functionalization of graphene and thin films production for the manufacture of composites and transparent and conducting electrodes, respectively. Since natural and mechanical properties of conductive carbon nanostructures are associated with individual isolated species, dispersion and stabilization of graphene in different liquids are of utmost importance in basic and applied studies. For this purpose, the attractive potential between the graphene sheets in the graphite must be balanced by a repulsive potential. Thus, the energy cost of graphene-solvent interactions, which strongly depends on the starting material and the dielectric properties of the medium, needs to be understood. Solubility theories have recently been applied to carbon nanostructures. In this study, we have used the Hansen solubility parameters for proposing solvent mixtures able to exfoliate the natural graphite from the Nacional de Grafite Ltda. company in the liquid phase. Using an algorithm in Matlab based on the Hansen solubility parameters, we have selected five mixtures of organic solvents, where chloroform is one of the components. The natural graphite in raw form and pre-exfoliated was exfoliated in stable dispersions of few-layer graphenes, which were characterized by UV-Vis and Raman spectroscopy, transmission electron microscopy (TEM) and dynamic light scattering (DLS). Dispersions produced in mixtures of lower value of D0, despite having a lower concentration of dispersed material, showed larger flakes size with few-layers of graphene. Mixtures with a higher value of D0 presented a higher concentration of dispersed material, but particles with smaller dimensions and a greater number of layers.
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Husain, Zainul Abideen. "Coupling reactions and separations in propane-organic-aqueous tunable solvent systems." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29719.
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Thesis (M. S.)--Chemical Engineering, Georgia Institute of Technology, 2009.Committee Chair: Eckert, Charles; Committee Co-Chair: Liotta, Charles; Committee Member: Meredith, Carson. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Chan, E. K. M. "Micelle formation by block copolymers in organic solvents." Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370405.
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Srour, Rafif K. "Metal-surface reactions in mixed aqueous organic solvents." Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3582.
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Thesis (Ph. D.)--West Virginia University, 2004.Title from document title page. Document formatted into pages; contains xix, 140 p. : ill. Includes abstract. Includes bibliographical references (p. 133-140).
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Gao, Huizhen. "A new approach to fractionation of natural organic matter - using ion retardation resin." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/29836.
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Dioum, Ndeye. "Biocatalysis of immobilized lipoxygenase in organic solvent media." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0033/MQ64344.pdf.
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Lee, Nicholas Conrad Jellicoe. "Oxidation profiles of ZDDP's in hydrocarbon solvents." Thesis, Brunel University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386350.
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Khamessan, Ali. "Chlorophyllase biocatalysis of chlorophyll in organic solvent media." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28798.
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Cette recherche comprend l'etude de la bioacatalyse de la chlorophyllase partiellement purifiee a partir d'algue (Phaeodactylum tricornutum) dans differents milieux organiques incluant les solvants miscibles et non miscibles a l'eau et les systemes micellaires tertiaires. Les quantites optimales d'eau et de solvant, choisi en fonction de son degre d'hydrophobicite et incluant l'acetone, l'ethanol, le propanol, le butanol, le pentanol, l'hexanol, le toluene, le pentane, l'hexane, l'heptane et l'octane, necessaire a la catalyse de l'effet hydrolytique de la chlorophyllase, ont ete mesurees. Les valeurs d $V sb{ rm max}$ obtenues mesurant l'activite hydrolytique de la chlorophyllase sont plus elevees chez les solvants miscibles a l'eau (log P 0.8). L'activite hydrolytique de la chlorophyllase decroit d'approximativement 12 fois lorsque le nombre de carbone pour les alcools, passent de 2 a 5. Certains resultats a partir du FTIR ("Fourier transform infrared spectroscopy") tendent a montrer que le phytol pourrait agir comme un donneur d'electron, ainsi, si un compose nucleophilique approprie est ajoute a un syteme biphasique, la solubilite de la chlorophylle dans l'hexane augmentera et l'activite hydrolytique de la chlorophyllase augmentera. En milieu biphasique (hexane/eau), l'addition de solvants polaires tels que l'acetone, l'ethanol, et le propanol augmente l'activite de la chlorophyllase et ce seulement a certaines concentrations. La mesure optimale de l'activite hydrolytique de la chlorophyllase en milieu micellaire tertiaire (tampon/hexane/surfactant) utilisant les polysorbates et les Spans ainsi que differentes chai nes hydrophobiques comme surfactant indique que les concentrations necessaires de surfactants sont dependantes a la fois de la chai ne hydrophobique et du groupement polaire. Toutefois, l'utilisation du Span 85 s'est avere plus approprie et les valeurs de $V sb{ rm max}$ obtenues mesurant l'activite enzymatique de la chlorophyllase sont 288 fois
31
Soroko, Iwona. "Polyimide organic solvent nanofiltration membranes-formation and function." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/6882.
Full textAbstract:
This thesis offers a comprehensive study that analyses the relationship between polyimide (PI) organic solvent nanofiltration (OSN) membrane formation parameters, membrane structure, and membrane functional performance. The dissertation starts by addressing the structure-related problem of macrovoid formation, which arises when more open membranes are prepared. Incorporation of TiO2 nanofillers into the membrane matrix results in macrovoid-free, organic/inorganic PI/TiO2 mixed matrix membranes without compromising rejection. Subsequently, a detailed analysis of the membrane formation process, considering the dope solution composition, evaporation step, and structural properties of polyimides, was conducted. The effect of the choice of polymer/solvent/co-solvent/non-solvent was found to be very profound and qualitatively predictable through introduction of a complex solubility parameter. Increasing value of complex solubility parameter can predict higher rejections. The study of the evaporation in PI OSN membrane formation has shown that this optional step is undesirable, as its presence results in unaltered rejection and significantly lower flux. Nevertheless, the presence of a co-solvent, regardless of whether it is volatile or not, was found to be required as it promotes formation of a dense membrane top layer. We have also studied sensitivity of PI OSN membranes to small perturbations in polymer characteristics, such as: molecular weight, alternating diisocyanates to form the PI chain, and copolymerisation method (block vs random). Finally, we proposed a less hazardous route for the PI OSN membrane formation process, which would reduce environmental impact without compromising the separation performance of the existing membranes.
32
Loh, Xun Xing. "Polyaniline membranes for use in organic solvent nanofiltration." Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/11347.
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Moreira, Roger Cardoso. "Desenvolvimento de metodologia para separação de aminas quaternárias utilizando eletroforese não aquosa em microssistemas." Universidade Federal de Goiás, 2015. http://repositorio.bc.ufg.br/tede/handle/tede/5899.
Full textAbstract:
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This study describes the development of an analytical methodology for the separation of quaternary amines using nonaqueous electrophoresis microchips coupled with capacitively coupled contactless conductivity detection (C4D). Initially, preliminary experiments were performed to evaluate two electrokinetic modes for sample introduction on chip, known as gated and floating approaches. Gated injection showed repeatability slightly better than floating mode. In addition, it also provided better analytical responses on the C4D system. During the development of analytical methodology for NAME-C4D, the electrolyte composition was optimized to ensure satisfactory separations on electrophoresis microchips. The electrolyte composed of sodium deoxycholate (NaDCHA) at concentration of 10 mmol/L dissolved in a mixture of MeOH/ACN at the ratio 90:10 (v/v) exhibited separations with high efficiency and resolution above 1. Then, it was realized the optimization of potential injection, separation and detection parameters (frequency and amplitude). Running electrolyte was prepared in both DMSO and DMF, however, the use of a mixture containing MeOH/ACN provided best analytical performance. The best results were obtained with electrolyte containing 10% ACN and 90% MeOH. In addition, different electrolyte compositions were also evaluated, but the electrolyte containing NaDCHA offered results slightly better when compared to others. The optimization of running buffer allowed the separation of nine quaternary amines in electrophoresis channels with effective length of 7.0 cm with analysis time lower than 120 s. The peak resolution was higher than 1 and the calculated separation efficiencies ranged from 77.000 to 185.000 pratos/m. This excellent performance was achieved using NAME conditions under high electric fields. The developed methodology was used for the analysis of quaternary amines in samples containing high salinity levels through the standard addition method. Linear correlation coefficients were obtained up to 0,990 for eight quaternary amines. Lastly, the use of NAME-C4D allowed to observe a strong dependence of the detector response according to the carbon number of quaternary amine molecules.
O presente trabalho descreve o desenvolvimento de uma metodologia analítica para separação de aminas quaternárias utilizando eletroforese não aquosa em microchips (NAME, do inglês non-aqueous microchip electrophoresis) com detecção condutométrica sem contato acoplada capacitivamente (C4D, do inglês capacitively coupled contactless conductivity detection). Inicialmente foi realizado um estudo para avaliação de dois modos de introdução da amostra nos microchips, denominados de gated e floating. O modo gated apresentou repetitividade ligeiramente melhor que o modo floating, além de proporcionar melhores respostas do detector C4D. No desenvolvimento da metodologia utilizando NAME-C4D, foi realizado um estudo para encontrar a composição ideal do eletrólito para as separações eletroforéticas. O eletrólito constituído de deoxicolato de sódio (NaDCHA), na concentração de 10 mmol/L, dissolvido em uma mistura de MeOH/ACN na proporção 90:10 (v/v), apresentou separações com alta eficiência e resolução superior a 1. A partir de então, foi realizada a otimização dos potenciais de injeção, separação e dos parâmetros de detecção (frequência e amplitude). Durante o desenvolvimento da metodologia, foram avaliados eletrólitos preparados em outros dois solventes, DMSO e DMF. Porém, a mistura de MeOH/ACN como solvente forneceu os melhores resultados, desta maneira também foi avaliada a adição de diferentes proporções de MeOH/ACN. Os melhores resultados foram obtidos com o eletrólito contendo 10% de ACN e 90% de MeOH. Na sequência, foram avaliadas diferentes composições do eletrólito, com a adição de outros compostos em substituição ao NaDCHA. Todos os eletrólitos avaliados apresentaram ótimas separações, porém o eletrólito com NaDCHA apresentou resultados ligeiramente superiores. Com a otimização da metodologia desenvolvida, obteve-se separações eletroforéticas de nove aminas quaternárias em microssistema contendo comprimento efetivo de 7,0 cm, com um tempo de análise inferior a 120 s. As separações apresentaram resolução superior a 1 e valores de eficiência entre 77,000 e 185,000 pratos/m, uma vez que com a utilização de solventes orgânicos, foi possível a aplicação de campos elétricos elevados. A metodologia desenvolvida foi avaliada através da determinação das aminas quaternárias, pelo método de adição de padrão, em uma matriz com elevada salinidade. Foram obtidos coeficientes de correlação lineares acima de 0,990 para oito aminas quaternárias. Durante o desenvolvimento do trabalho, foi observada uma clara dependência das respostas analítica em função da quantidade de carbono da molécula.
34
Yang, Jixin. "Time resolved infrared spectroscopy of transient species in conventional and supercritical fluid solutions." Thesis, University of Nottingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289335.
Full text
35
Butler, Rachel. "Control of polymer morphology using compressed fluids." Thesis, University of Liverpool, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272749.
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36
Rivals, FreÌdeÌric. "Multianionic phosphazenates : ligands of extremely high metal loading capacity." Thesis, University of Liverpool, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250456.
Full text
37
Emer, Enrico <1979>. "Acqua: solvente elettivo in Organocatalisi e Biocatalisi." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/1467/1/enrico_emer_tesi.pdf.
Full textAbstract:
Water is a safe, harmless, and environmentally benign solvent. From an eco-sustainable chemistry
perspective, the use of water instead of organic solvent is preferred to decrease environmental
contamination. Moreover, water has unique physical and chemical properties, such as high dielectric
constant and high cohesive energy density compared to most organic solvents. The different interactions
between water and substrates, make water an interesting candidate as a solvent or co-solvent from an
industrial and laboratory perspective. In this regard, organic reactions in aqueous media are of current
interest. In addition, from practical and synthetic standpoints, a great advantage of using water is
immediately evident, since it does not require any preliminary drying process.
This thesis was found on this aspect of chemical research, with particular attention to the mechanisms
which control organo and bio-catalysis outcome. The first part of the study was focused on the aldol
reaction. In particular, for the first time it has been analyzed for the first time the stereoselectivity of the
condensation reaction between 3-pyridincarbaldehyde and the cyclohexanone, catalyzed by morpholine
and 4-tertbutyldimethylsiloxyproline, using water as sole solvent. This interest has resulted in countless
works appeared in the literature concerning the use of proline derivatives as effective catalysts in organic
aqueous environment. These studies showed good enantio and diastereoselectivities but they did not
present an in depth study of the reaction mechanism. The analysis of the products diastereomeric ratios
through the Eyring equation allowed to compare the activation parameters (ΔΔH≠ and ΔΔS≠) of the
diastereomeric reaction paths, and to compare the different type of catalysis. While morpholine showed
constant diasteromeric ratio at all temperatures, the O(TBS)-L-proline, showed a non-linear Eyring diagram,
with two linear trends and the presence of an inversion temperature (Tinv) at 53 ° C, which denotes the
presence of solvation effects by water. A pH-dependent study allowed to identify two different reaction
mechanisms, and in the case of O(TBS)-L-proline, to ensure the formation of an enaminic species, as a keyelement
in the stereoselective process. Moreover, it has been studied the possibility of using the 6-
aminopenicillanic acid (6-APA) as amino acid-type catalyst for aldol condensation between cyclohexanone
and aromatic aldehydes. A detailed analysis of the catalyst regarding its behavior in different organic
solvents and pH, allowed to prove its potential as a candidate for green catalysis. Best results were
obtained in neat conditions, where 6-APA proved to be an effective catalyst in terms of yields. The catalyst
performance in terms of enantio- and diastereo-selectivity, was impaired by the competition between two
different catalytic mechanisms: one via imine-enamine mechanism and one via a Bronsted-acid catalysis.
The last part of the thesis was dedicated to the enzymatic catalysis, with particular attention to the use of
an enzyme belonging to the class of alcohol dehydrogenase, the Horse Liver Alcohol Dehydrogenase
(HLADH) which was selected and used in the enantioselective reduction of aldehydes to enantiopure
arylpropylic alcohols. This enzyme has showed an excellent responsiveness to this type of aldehydes and a
good tolerance toward organic solvents. Moreover, the fast keto-enolic equilibrium of this class of
aldehydes that induce the stereocentre racemization, allows the dynamic-kinetic resolution (DKR) to give
the enantiopure alcohol. By analyzing the different reaction parameters, especially the pH and the amount
of enzyme, and adding a small percentage of organic solvent, it was possible to control all the parameters
involved in the reaction. The excellent enatioselectivity of HLADH along with the DKR of arylpropionic
aldehydes, allowed to obtain the corresponding alcohols in quantitative yields and with an optical purity
ranging from 64% to >99%.
38
Emer, Enrico <1979>. "Acqua: solvente elettivo in Organocatalisi e Biocatalisi." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/1467/.
Full textAbstract:
Water is a safe, harmless, and environmentally benign solvent. From an eco-sustainable chemistry
perspective, the use of water instead of organic solvent is preferred to decrease environmental
contamination. Moreover, water has unique physical and chemical properties, such as high dielectric
constant and high cohesive energy density compared to most organic solvents. The different interactions
between water and substrates, make water an interesting candidate as a solvent or co-solvent from an
industrial and laboratory perspective. In this regard, organic reactions in aqueous media are of current
interest. In addition, from practical and synthetic standpoints, a great advantage of using water is
immediately evident, since it does not require any preliminary drying process.
This thesis was found on this aspect of chemical research, with particular attention to the mechanisms
which control organo and bio-catalysis outcome. The first part of the study was focused on the aldol
reaction. In particular, for the first time it has been analyzed for the first time the stereoselectivity of the
condensation reaction between 3-pyridincarbaldehyde and the cyclohexanone, catalyzed by morpholine
and 4-tertbutyldimethylsiloxyproline, using water as sole solvent. This interest has resulted in countless
works appeared in the literature concerning the use of proline derivatives as effective catalysts in organic
aqueous environment. These studies showed good enantio and diastereoselectivities but they did not
present an in depth study of the reaction mechanism. The analysis of the products diastereomeric ratios
through the Eyring equation allowed to compare the activation parameters (ΔΔH≠ and ΔΔS≠) of the
diastereomeric reaction paths, and to compare the different type of catalysis. While morpholine showed
constant diasteromeric ratio at all temperatures, the O(TBS)-L-proline, showed a non-linear Eyring diagram,
with two linear trends and the presence of an inversion temperature (Tinv) at 53 ° C, which denotes the
presence of solvation effects by water. A pH-dependent study allowed to identify two different reaction
mechanisms, and in the case of O(TBS)-L-proline, to ensure the formation of an enaminic species, as a keyelement
in the stereoselective process. Moreover, it has been studied the possibility of using the 6-
aminopenicillanic acid (6-APA) as amino acid-type catalyst for aldol condensation between cyclohexanone
and aromatic aldehydes. A detailed analysis of the catalyst regarding its behavior in different organic
solvents and pH, allowed to prove its potential as a candidate for green catalysis. Best results were
obtained in neat conditions, where 6-APA proved to be an effective catalyst in terms of yields. The catalyst
performance in terms of enantio- and diastereo-selectivity, was impaired by the competition between two
different catalytic mechanisms: one via imine-enamine mechanism and one via a Bronsted-acid catalysis.
The last part of the thesis was dedicated to the enzymatic catalysis, with particular attention to the use of
an enzyme belonging to the class of alcohol dehydrogenase, the Horse Liver Alcohol Dehydrogenase
(HLADH) which was selected and used in the enantioselective reduction of aldehydes to enantiopure
arylpropylic alcohols. This enzyme has showed an excellent responsiveness to this type of aldehydes and a
good tolerance toward organic solvents. Moreover, the fast keto-enolic equilibrium of this class of
aldehydes that induce the stereocentre racemization, allows the dynamic-kinetic resolution (DKR) to give
the enantiopure alcohol. By analyzing the different reaction parameters, especially the pH and the amount
of enzyme, and adding a small percentage of organic solvent, it was possible to control all the parameters
involved in the reaction. The excellent enatioselectivity of HLADH along with the DKR of arylpropionic
aldehydes, allowed to obtain the corresponding alcohols in quantitative yields and with an optical purity
ranging from 64% to >99%.
39
Quinones, Casilda. "Influence of three organic solvents on soil microbial activity." Thesis, The University of Arizona, 1985. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1985_420_sip1_w.pdf&type=application/pdf.
Full text
40
Dall'Ora, Lucia. "Characterization and modeling of organic solvents sorption and transport in PDMS membranes for organic/organic separations." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
Find full textAbstract:
This study is mainly focused on the investigation of which are the main characteristics affecting the membranes’ performances and how they are influenced by the presence of different organic solvents.
Two different PDMS membranes were prepared and studied, the two materials have the same chemical structure but different number of active sites for the cross-linking process. This choice was made to investigate how the swelling of a polymer can affect membrane characteristics.
The first experiment performed with these PDMS membranes was the dynamic vapor sorption of organic solvents. Both hydrocarbons and alcohols were tested in order to understand how the polymeric material interacts with the different chemical species. It is evident from the results, the higher affinity between polymer and hydrocarbons with respect to alcohols. The sorption isotherms so obtained were modelled using different theories, trying to estimate the strengths and limits of each of them.
From the same sorption experiments, kinetic data for the evaluation of transport phenomena were obtained and Fick’s law was applied to calculate values of the diffusion coefficient.
In the second part of this study, the same membranes were tested in presence of pure liquid organic solvents, performing some filtration experiments. Fluxes through the membranes were measured and an evaluation of rejection and Molecular Weight Cut Off were given.
In the end, the membranes were tested in presence of organic solvents binary mixtures. As before, fluxes through the membranes were measured and selectivities were calculated.
It was possible to observe how these membranes are not able to separate hydrocarbons but they show higher selectivity in presence of a mixture of a hydrocarbon and an alcohol.
In conclusion, this research provides a guidance on which experiments can be performed to characterize a membrane material and help to understand how many different parameters can affect the separation process.
41
Gates, Richard J. "Dynamics of the Solvent Exchange Reaction of Weakly Bound Organic Solvents to Group 6 Transition Metal Carbonyls and the Molybdenum Hexacarbonyl Mediated Pauson-Khand Reaction." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/2936.
Full textAbstract:
Many organometallic reactions are solvent-dependent, suggesting solvent molecules interact with reaction intermediates. Studies of the solvent exchange reaction of group 6 transition metal carbonyls with moderately binding ligands have provided insight into these interactions, however, studies of the mechanism for this reaction with weakly binding ligands have not been performed. Experiments were conducted on the nanosecond time scale in methylcyclohexane over the temperature range of 4 to 44 °C using Step Scan FTIR (SS FTIR) spectroscopy with weakly binding ligands benzene and mesitylene. Upon photolysis of the metal hexacarbonyls, the kinetically favored product (M(CO)5(solv)), decays following pseudo-first-order kinetics to the thermodynamical favored product, M(CO)5(L). The decay is fit using a single exponential decay with a single exponential instrument response function, time zero and an offset. An Arrhenius plot yielded activation energies of 23.7 kJ/mol (M = Mo, L = benzene), 35.1 kJ/mol (M = W, L = benzene) and 29.8 kJ/mol (M = Mo, L = mesitylene). DFT calculations using NWCHEM gave binding energies of 45.8 and 54.3 kJ mol-1 for Mo(CO)5C6H12 and W(CO)5C6H12. The experimental and computational results suggest the exchange mechanism proceeds through an associative pathway, were slightly negative values of the entropy of reaction denote that the transition state has greater metal solvent bond breaking character then the more moderately binding ligands in the literature. Density Functional theory was used to calculate C-O vibrational frequencies of metal carbonyl complexes measured in our work and other complexes from the literature, with density functionals B3LYP, M06 and M06-L. Measured and computational frequencies were compared to obtain both an overall vibrational shift and a scaling factor. Scaling factors were found to be 0.9519±0.0095 for B3LYP, 0.9429 ± 0.0087 for M06 and 0.9565 ± 0.0095 for M06-L with overall shifts of 102 ± 16, 121 ± 15, 93 ± 17 cm-1, respectively. The molybdenum mediated Pauson-Khand reaction, a [2+2+1] cyclo-addition begins very similarly to the solvent exchange reaction on molybdenum. The initial product, the solvated complex, decays away with pseudo-first-order kinetics as the solvent is replaced by the C-C triple bond in 2-(2-propen-1-yl)-2-(2-propyn-1-yl)-,1,3-diethyl ester. An Arrhenius plot over the temperature range of -8 to 20° C yielded an energy of activation of 15.6 kJ/mol.
42
Martin, Laura Joy. "Properties of fluorinated surfactants and polymers in organic solvents." Thesis, University of Bristol, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420900.
Full text
43
Padmanabhan, Anita Rema. "Novel Simultaneous Reduction/Oxidation Process for Destroying Organic Solvents." Digital WPI, 2008. https://digitalcommons.wpi.edu/etd-theses/465.
Full textAbstract:
Trichloroethylene (TCE) is one of the most common groundwater pollutants in the United States and is a suspected carcinogen. The United States Environmental Protection Agency (EPA) estimated that between 9% and 34% of the drinking water sources in the United States may contain TCE, and have set a maximum contaminant level of 5 ìg/L for drinking water. Traditional treatment technologies such as granular activated carbon and air stripping have only had marginal success at removing TCE from contaminated sites. Chemical oxidation processes have provided a promising alternative to traditional treatment methods. The objective of this research was to examine the conditions under which zero valent iron (Fe0) activates persulfate anions to produce sulfate free radicals, a powerful oxidant used for destroying organic contaminants in water. With batch experiments, it was found that persulfate activated by zero valent iron removed TCE more effectively than persulfate oxidation activated by ferrous iron. This laboratory study also investigated the influence of pH (from 2 to 10) on TCE removal. TCE was prepared in purified water and a fixed persulfate/TCE molar ratio was employed in all tests. The results indicated that this reaction occurred over a wide range of pH values. The production and destruction of daughter products cis 1,2 dichloroethylene and vinyl chloride were observed. The effect of persulfate dose on this reaction was also studied. Results showed that a molar ratio of 10/1/1 (persulfate/ZVI/TCE) yielded over 95 percent TCE destruction. Increasing the persulfate dose resulted in greater TCE destruction as well as destruction of the daughter products. Kinetic experiments at a molar ratio of 10/1/1 (persulfate/ZVI/TCE) show that approximately 90 percent of the TCE was destroyed in less than 15 minutes.
44
Eisenhart, Andrew. "Quantum Simulations of Specific Ion Effects in Organic Solvents." University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1626356392775228.
Full text
45
Lake, Deborah M. "Weight loss of orthodontic bonding resins in organic solvents." Thesis, The University of Sydney, 1986. http://hdl.handle.net/2123/4887.
Full text
46
Campbell, James. "The development of hybrid polymer-metal organic framework membranes for organic solvent nanofiltration." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/33219.
Full textAbstract:
The most common membranes used for organic solvent nanofiltration (OSN) are integrally skinned asymmetric membranes formed via the immersion precipitation phase inversion process. These membranes are flexible, durable and easy to produce. However control of the porous properties of these membranes is not possible on a molecular level. Integrally skinned asymmetric membranes always exhibit signs of a pore size distribution, which leads to rejections not being optimum. Metal organic frameworks (MOFs) were added to polymeric OSN membranes in an attempt to improve the control over porous properties and separation properties above those achievable using integrally skinned asymmetric polymer membranes. MOFs are crystalline materials with regular porous structures. MOFs have been used for gas separation purposes. This thesis describes the fabrication of hybrid polymer/MOF membranes for OSN applications. MMM fabrication is the tradition approach to create a hybrid polymer/MOF membrane, and contains discrete particles of MOF in a continuous polymer phase. The advantage of MMMs is that they are easy to produce; however, due to the discrete nature of the MOF in the membrane; the permeation of molecules through the membrane is not completely controlled by the MOF. MMMs were shown to have little difference in performance to polymer nanofiltration membranes for OSN. In order for the MOF to exhibit more control over the permeation properties of membranes, in-situ growth (ISG) membranes were developed, whereby MOF material is grown within the pre-existing pores of polymer membranes. Using the MOF HKUST-1 and ultrafiltration polyimide supports ISG membranes were produced and were shown to outperform MMMs in terms of both solute retention and flux decline. Energy-dispersive X-ray spectroscopy (EDX) was used to reveal the distribution of HKUST-1 throughout ISG membranes, which was found to be even across the surface and throughout the cross-section, showing that a continuous phase of MOF had been grown.
47
Ross, Alistair Chassels. "Enzyme inactivation at the aqueous/organic interface." Thesis, University of Strathclyde, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366528.
Full text
48
Murdan, Sudaxshina. "Non-ionic surfactant-based organogels : their structures and potential as vaccine adjuvants." Thesis, University College London (University of London), 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299134.
Full text
49
Rohan, James Francis. "A fundamental investigation of the lithium/organic solvent interface." Thesis, University of Southampton, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239679.
Full text
50
Oster, Vanessa Viebrantz. "Influência do tempo de extração e da razão amostra: solvente no processo de extração do óleo do caroço do pequi visando a produção de biodiesel." Universidade Federal do Tocantins, 2013. http://hdl.handle.net/11612/547.
Full textAbstract:
Problemas ambientais causados pelo uso excessivo de energia proveniente do
petróleo estão fazendo com que os países busquem a diversificação da matriz
energética. Dentro deste contexto, é que a produção de biodiesel, a partir de óleos
vegetais, vem se destacando no cenário energético. A extração da matéria-prima
usada na produção desses biocombustível é uma fase de extrema importância,
por isso, faz-se necessário determinar qual a melhor forma de sua realização,
caracterizando os principais fatores químicos e físicos que interferem nesse
processo. Visando otimizar o processo de extração do óleo do caroço do pequi,
este trabalho baseou-se na realização de experimentos que buscaram identificar o
teor aproximado de óleo no caroço do pequi e ainda qual o melhor solvente
orgânico, entre hexano, etanol e a mistura desses solventes, para a extração do
óleo do caroço do pequi para a produção de biodiesel. A partir dos dados obtidos
nos ensaios realizados neste trabalho, pode ser observado que o putâmem do
pequi apresenta um teor elevado de óleo, em méidia de 31%, quantidade superior
a encontrada no grão da soja, que hoje é a matéria – prima base para a produção
de biodiesel. Observou-se ainda que a misturas dos dois solventes orgânicos
(hexano + etanol) na razão de 1:1 mostrou-se mais eficiente no processo
extraíndo aproximadamente 34% do óleo presente no caroço do pequi.The environmental problems caused by the excessive use of energy from petroleum are causing countries seek to diversify sources of energy. Within this context, is that the production of biodiesel from vegetable oils, has been increasing in energy scenario. The extraction of the raw material used in producing these biofuels is an extremely important step, so it is necessary to determine the best form of his achievement, featuring the main chemical and physical factors that affect this process. In order to optimize the extraction process of oil pits pequi, this work was based on the realization of experiments that attempted to identify the approximate oil content in the pits pequi and yet which is the best organic solvent, hexane between ethanol and the mixture of these solvents for oil extraction from the seed pequi for biodiesel production. Starting from the data obtained in the tests performed in this study, it can be observed that the pits pequi has a high content of oil, around 31%, much higher than found in soy beans, which today is raw - material basis for biodiesel production. It was also observed that mixtures of two organic solvents (hexane + ethanol) at a ratio of 1:1 was more efficient in the process of Extracting approximately 34% of the oil present in the pits pequi.