Dissertations / Theses: 'Surfactant'

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Hines, J. D. "Investigation of surfactants and surfactant mixtures." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337736.

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Stellner, Kevin Lance. "Precipitation of surfactants and surfactant mixtures in aqueous solutions /." Full-text version available from OU Domain via ProQuest Digital Dissertations, 1987.

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3

Kjellin, Mikael. "Structure-Property Relationships of Surfactants at Interfaces and Polyelectrolyte-Surfactant Aggregates." Doctoral thesis, KTH, Chemistry, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3299.

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The first part of this thesis is concerned with thestructure-property relationships in nonionic surfactantsystems. The main aim was to investigate how the surfactantstructure influences the adsorption at interfaces andinteractions between surfactant coated interfaces.Particularly, the effect of the structure of the surfactantheadgroups was investigated. These were sugar-based headgroupwith varying size and flexibility and poly(ethylene oxide)based headgroups with or without an additional amide or estergroup. The hydrophobic part of the surfactant consisted mostlyof straight alkyl chains, except for one type of poly(ethyleneoxide) based surfactant with a dehydroabietic hydrophobe.

The main technique that was used is the surface forcetechnique, with which the forces acting between two adsorbedsurfactant layers on hydrophilic or hydrophobic surfaces can bemeasured. These forces are important for e.g. the stability ofdispersions. The hydrophilic surfaces employed were glass andmica, whereas the hydrophobic surfaces were silanized glass andhydrophobized mica. The adsorption behavior on hydrophilicsurfaces is highly dependent on the type of headgroup andsurface, whereas similar results were obtained on the two typesof hydrophobic surfaces. To better understand how the surfaceforces are affected by the surfactant structure, measurementsof adsorbed amount and theoretical mean-field latticecalculations were carried out. The results show that the sugarsurfactant layers and poly(ethylene oxide) surfactant layersgive rise to very different surface forces, but that the forcesare more similar within each group. The structure-propertyrelationships for many other physical properties have beenstudied as well. These include equilibrium and dynamicadsorption at the liquid-vapor interface, micelle size, micelledynamics, and wetting.

The second part in this thesis is about the aggregationbetween cationic polyelectrolytes and an anionic surfactant.The surface force technique was used to study the adsorption ofa low charged cationic polyelectrolyte on mica, and theaggregation between the adsorbed polyelectrolyte with theanionic surfactant. The aggregation in bulk was studied withturbidimetry, small angle neutron scattering (SANS), and smallangle x-ray scattering (SAXS). An internal hexagonal aggregatestructure was found for some of the bulk aggregates.

Keywords:nonionic surfactant, sugar surfactant,poly(ethylene oxide), amide, ester, polyelectrolyte, SDS,hydrophobic surface, glass surface, mica, adsorption,aggregation, micelle size, surface forces, wetting, dynamicsurface tension, NMR, TRFQ, SANS, SAXS, mean-field latticecalculations.

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Nusselder, Jan Jacob Hendrik. "Surfactant structure and aggregation behavior 1-alkyl-4-alkylpyridinium iodide surfactants /." [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 1990. http://irs.ub.rug.nl/ppn/29074184X.

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Bleta, Rudina. "Systèmes fluorés pour la conception de matériaux poreux : Matrices pour la physisorption de biomolécules." Thesis, Nancy 1, 2007. http://www.theses.fr/2007NAN10111/document.

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Les propriétés d’auto organisation de tensioactifs ainsi que celles de la chimie de la silice ont permis de préparer des matériaux mésoporeux organisés selon une symétrie hexagonale, cubique ou lamellaire dont la taille des pores varie de 2 à plus de 10 nm. Ils sont depuis quelques années le centre d’intérêt d’universitaires et d’industriels qui développent des recherches fondamentales et appliquées. La compréhension globale des mécanismes de synthèse et la maîtrise des propriétés structurales et texturales des matériaux mésoporeux sont nécessaires pour envisager leur utilisation dans un quelconque procédé industriel. Dans ce cadre, nous avons étudié les relations entre les propriétés physico-chimiques d’un tensioactif fluoré C7F15C2H4(OC2H4)8OH et les caractéristiques des silices mésoporeuses. Malgré l’existence d’une phase micellaire, les canaux poreux des matériaux obtenus avec ces solutions micellaires ne sont pas organisés. En revanche, l’addition de la perfluorodécaline provoque une structuration du matériau selon une symétrie hexagonale. L’utilisation de divers fluorocarbures, ayant des structures moléculaires différentes, montre que le phénomène est associé au déplacement de la courbe de point de trouble vers les hautes températures. De plus, il a été montre que la préparation de matériaux à porosité hiérarchisée à partir d'émulsions de type huile dans eau est corrélée à la température d’inversion de phase du système eau/huile/tensioactif. Enfin, les matériaux mésoporeux ont été mis à profit pour immobiliser des enzymes et les résultats montrent que les lipases physisorbées conservent une activité catalytique
The self-assembly properties of surfactants and those of silica chemistry have led to the preparation of ordered mesoporous materials with hexagonal, cubic or lamellar symmetry and with pore sizes varying from 2 to more than 10 nm. Recently, they have aroused of great deal of interest to academics and industrialists for the development of fundamental and applied research. However, their use in any industrial process needs a careful consideration of the total comprehension of the synthesis mechanism as well as the control of their structural and textural properties. In this work, the relation between the physicochemical properties of a fluorinated surfactant, C7F15C2H4(OC2H4)8OH, and the characteristics of mesoporous silica was investigated. In spite of the existence of a micellar phase, only wormlike mesoporous materials were obtained. On the other hand, the addition of the perfluorodecalin led to the organisation of the channels according to a hexagonal symmetry. The use of various fluorocarbons of different molecular structures evidenced that this phenomenon is associated to the shift of the cloud point curve towards higher temperatures. Hierarchically porous silica were also prepared from oil-in-water emulsions and their characteristics were correlated to the phase inversion temperature of the surfactant/water/oil system. Finally, the mesoporous materials were used as hosts for the physisorption of enzymes and the results showed that the catalytic activity of the immobilised lipases is preserved

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Senra, Tonimar Domiciano Arrighi. "N,N,N-trimetilquitosana e N-(2-hidróxi)-propil-3-trimetilamônio quitosana: preparação, caracterização e estudo de suas interações com decanossulfonato de sódio." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/75/75134/tde-20052015-154551/.

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O presente trabalho estudou duas vias reacionais para a preparação de derivados cationizados de quitosana (QCat), sendo que a N-metilação extensiva via reação de quitosana com iodometano (CH3I) resultou em N,N,N-trimetilquitosana (TMQ) enquanto que a reação de quitosana com cloreto de glicidiltrimetilamônio (CGTMA) produziu N-(2-hidroxi)-propil-3-trimetilamônio quitosana (HPTAQ). Planejamento fatorial completo 23 foi aplicado para analisar os efeitos das condições reacionais sobre o rendimento das reações (R) e as características de TMQ e HPTAQ. As características estruturais da quitosana de partida e seus derivados foram analisadas por espectroscopias na região de infravermelho (FTIR) e de ressonância magnética nuclear de hidrogênio (RMN-1H), sendo que esta última também foi utilizada para determinar os graus médios de acetilação (GA), de quaternização (GQ) e de substituição (GS) de quitosana, TMQ e HPTAQ, respectivamente. Viscosimetria capilar foi utilizada para determinar a viscosidade intrínseca ([η]) de quitosana, TMQ e HPTAQ, permitindo estimar a ocorrência de despolimerização e sua relação com as condições reacionais. Todas as amostras de TMQ foram solúveis em água e o valor de GQ variou no intervalo 21,0 - 67,0%; a [η] variou entre 13,7 mL/g - 213,0 mL/g e o rendimento da reação atingiu até 82,0%, sendo que entre as variáveis analisadas a concentração de hidroxido de sódio e excesso de CH3I são as mais relevantes. Quanto às amostras de HPTAQ, apenas aquelas com GS > 12,0% foram solúveis em água,GS ficou no intervalo 1,0 % - 45,5%; [η] variou entre 283,0 mL/g - 446,0 mL/g e o rendimento não foi superior a 33,0%, e entre as variáveis analisadas, temperatura e excesso de CGTMA foram as mais importantes na produção de HPTAQ. As amostras TMQ2 GQ = 46,0%; [η] = 290,0 mL/g) e HPTAQ6 GS = 33,0%; [η] = 293,0 mL/g) foram empregadas em estudo visando a formação de complexos surfactante/polieletrólito (CSP) com decanossulfonato de sódio (DS). As propriedades condutimétricas e tensiométicas dos TMQ2, HPTAQ6 e CSP\'s foram estudadas e mostraram que todos apresentam atividade interfacial (γ <= 52,0 mN.m-1), além de elevado valor de módulo de elasticidade (E >= 31,0 mN.m-1), indicando que as espécies analisadas geram filmes interfaciais com boas propriedade mecânicas e por isso podem ser aplicados como agentes estabilizantes de emulsões. As emulsões do tipo óleo/água preparadas pela incorporação de QCat (TMQ ou HPTAQ) ou de CSP (TMQ/DS ou HPTAQ/DS) foram estáveis por mais de 4 meses, conforme avaliado por medidas de fluorescência e de turbidez.
In this work were studied two different methods for preparing cationized derivatives of chitosan (ChCat), a consisted extensive N-methylation by chitosan reaction with iodomethane (CH3I) resulted in N,N,N-trimethylchitosan (TMCh), and other a reaction of chitosan with chloride glycidyltrimethylammonium (GTMAC) resulted in N-(2-hydroxy)-propyl-3-trimethylammonium chitosan (HPTACh). A complete factorial design (23) was used to analyze the influence of reaction conditions on the yield of the reaction (R) as well as the characteristics of TMCh and HPTACh produced. The structure of chitosan pattern and its derivatives were characterized by infrared spectroscopy (IR) and nuclear magnetic resonance (1H-NMR), considering that the latter was also used to determine the average degree of acetylation (DA), quaternization (DQ) and substitution (DS) of chitosan, TMCh and HPTACh, respectively. Capillary viscometry was used to determine the intrinsic viscosity ([η]) of chitosan, TMCh and HPTACh, allowing to estimate the occurrence of depolymerization and its relationship with the reaction conditions. All samples of TMCh were soluble in water and it was found that DA ranged as 21.0% - 67.0%; the [η] ranged as 13.7 mL/g - 213.0 mL/g and the yield reaction was up to 82.0%, among the variables studied, the concentration of sodium hydroxide and excess CH3I were the most relevant. The HPTACh samples were soluble in water with DS > 12.0%, DS ranged as 1.0% - 45.5%; the [η] ranged as 283.0 mL/g - 446.0 mL/g and the yield was lower than 33.0%, among the variables studied temperature and excess CGTMA were the most important in the production of HPTACh. Among the reaction conditions studied for the synthesis of TMCh the best condition was 2, while for HPTACh the best condition was 6. The samples TMCh2 DQ = 46.0%, [η] = 290.0 ml/g) and HPTACh6 DS = 33.0%, [η] = 293.0 mL/g) were used in a study aiming at the formation of surfactant/polyelectrolyte complex (SPEC) with sodium 1-decanessulfonate (SD). The conductivity and surface tension properties of TMCh2, HPTACh6 and SPEC\'s have been studied and show that all have interfacial activity (γ <= 52.0 mN.m-1), and high value of elasticity modulus (E >= 31.0 mN.m-1), indicating that all species generate interfacial film with good mechanical property and thus can be applied as a stabilizing agent in emulsions emulsions oil/water that were prepared by incorporating ChCat synthesized and SPEC\'s in their formulations, they were stable for more than 4 months, as evaluated by fluorescence and turbidity measurements.

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ALENCAR, Bruna Cabral de. "Influência da dinâmica de sorção/dessorção na biodegradação anaeróbia do alquilbezeno linear sulfonado." Universidade Federal de Pernambuco, 2015. https://repositorio.ufpe.br/handle/123456789/17246.

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CAPES
O LAS é um tensoativo usado na fabricação de produtos de limpeza, sendo sua degradação no tratamento aeróbio altamente eficaz. Todavia, em ambientes anaeróbios, sua biodegradação depende de vários fatores, como a composição e concentração de alguns compostos dos esgotos. Por isso, as eficiências de degradação do LAS neste ambiente são distintas, variando de 0 a 78%. No Brasil, devido a uma carência na área do saneamento, alternativas mais baratas para o tratamento de esgoto estão sendo amplamente utilizadas. Os reatores anaeróbios do tipo UASB são um exemplo destas alternativas, devido a sua alta eficiência de remoção de matéria orgânica. Entretanto, atualmente em uma estação de tratamento de esgoto, o objetivo não é apenas a matéria orgânica de fácil degradação, mas também compostos recalcitrantes e nutrientes. Este trabalho teve como objetivo aplicar em um reator contínuo, alimentado com esgoto real, um modelo de otimização, realizado em laboratório com regime em batelada, para verificar reprodutibilidade da influência de alguns parâmetros na dinâmica de sorção/dessorção do LAS em reatores utilizados em estações de tratamento de esgoto convencionais. Foram realizados dois experimentos. O experimentoI foi o monitoramento de um reator UASB em escala de laboratório. Este reator era alimentado com esgoto de uma estação de tratamento real, ETE Mangueira. Alterações no afluente foram realizadas para proporcionar a adsorção do LAS na biomassa. O pH foi ajustado para 6. Seguindo um planejamento fatorial 2K, o reator foi operado em 4 fases alterando a concentração de óleo, entre 0 e 5 g/L e a oxigenação ou não do LAS. O experimento II foi um teste de laboratório de adsorção e de dessorção, utilizando a mesma biomassa do reator do primeiro experimento. Foram submetidas diferentes concentrações de LAS (10, 20 e 100 mg/L), e diferentes tempos de mistura. Durante o período de operação, observou-se a ocorrência de adsorção e dessorção do LAS no lodo, bem como biodegradação, quando a adsorção foi baixa; as eficiências de degradação do LAS total nas diversas fases experimentais variaram de 0 a 33%. Os homólogos C12 e C13 foram os que sofreram maior degradação durante todo período de operação, com eficiências de 42 e 57% de sua massa inicial, respectivamente, na fase com alteração apenas do pH; o C13 foi o homólogo de maior taxa de adsorção, 97% de sua massa inicial. Isto ocorreu quando a concentração de óleo foi de 5 g/L e não foi realizado aeração do LAS. No teste de adsorção, os resultados obtidos mostraram que a adsorção na biomassa seca depende da disponibilidade de LAS no líquido. No teste de dessorção o comportamento de liberação de LAS no meio aquoso foi lento. Os testes mostraram capacidade reversível da adsorção do LAS, comprovando que a dinâmica de adsorção e dessorção do LAS no reator depende da composição do meio líquido e da forma de operação do reator, e que sua indisponibilidade no meio solúvel impede a degradação. Logo, o processo de adsorção inibe a degradação do LAS em ambientes anaeróbios e os resultados obtidos no teste de otimização em laboratório foram também observados em reatores operados com esgoto real.
LAS is a surfactant used in the manufacture of cleaning products, and its degradation in the highly efficient aerobic treatment. However, in anaerobic environments, biodegradation depends on several factors, including the composition and concentration of certain compounds of sewage. Therefore, the LAS this environmental degradation efficiencies are different, ranging from 0 to 78%. In Brazil, due to a lack in the sanitation area, cheaper alternatives for the treatment of sewage are being widely used. The anaerobic reactor of the UASB type are an example of these alternatives, due to its high removal efficiency of organic matter. However, currently a sewage treatment plant, the aim is not only the organic matter degradation easily, but also nutrients and recalcitrant compounds. This study aimed to apply in a continuous reactor, fed with real wastewater, an optimization model, conducted in laboratory batch system to check reproducibility of the influence of some parameters on dynamic sorption / desorption of LAS reactors used in stations Conventional sewage treatment. Two experiments were conducted. The first was a monitoring of a UASB reactor at laboratory scale. This reactor was fed with sewage a real treatment plant, ETE hose. Changes in the influent were performed to provide the adsorption of LAS biomass. The pH was adjusted to 6. By following a factorial design 2K, the reactor was operated at four stages by changing the concentration of oil, between 0 and 5 g / L and oxygenation or not the LAS. The second experiment was a laboratory test adsorption and desorption using the same biomass from the first reactor experiment. They underwent different concentrations of LAS, 10, 20 and 100 mg / L, and different mixing times. During the operation period, it was observed the occurrence of adsorption and desorption of LAS in the sludge as well as biodegradation when adsorption was low; The degradation efficiency of the total LAS in the different experimental phases ranging from 0 to 33%. The C12 and C13 homologues have suffered the greatest degradation during the entire operating period, efficiency 42 and 57% of their initial mass, respectively, in phase with the pH change only; the C13 was the counterpart of higher adsorption rate, 97% of its initial mass. This occurred when the oil concentration was 5 g / L and aeration was not performed LAS. In the adsorption test, the results showed that adsorption of dry biomass depends on the availability of LAS in the liquid. In desorption test the LAS release behavior in aqueous media was slow. The tests showed reversible adsorption capacity of the LAS, proving that the dynamics of adsorption and desorption of LAS in the reactor depends on the composition of the liquid medium and form of reactor operation, and that their unavailability in the middle soluble prevents degradation. Therefore, the adsorption process inhibits the degradation of LAS in anaerobic environments and the results obtained in laboratory test optimization are also observed in reactors operated with real sewage.

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Valstar, Ank. "Protein-surfactant interactions." Doctoral thesis, Uppsala University, Department of Physical Chemistry, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-1070.

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Protein-surfactant interactions in aqueous media have been investigated. The globular proteins lysozyme and bovine serum albumin (BSA) served as model proteins. Several ionic and non-ionic surfactants were used.

Fluorescence probe measurements showed that at low sodium dodecyl sulfate (SDS) concentration (< 0.1 M) one micelle-like SDS cluster is bound to lysozyme. From dynamic light scattering (DLS) results it was observed that lysozyme in the complex does not correspond to the fully unfolded protein. At high SDS concentration (> 0.1 M) one compact and one more extended lysozyme-SDS complex coexist.

The influence of surfactant alkyl chain length and headgroup on BSA-surfactant complex formation was investigated. In these studies, binding isotherms were determined by nuclear magnetic resonance (NMR), DLS was used to measure the hydrodynamic radii of the complexes and the size of the micelle-like aggregates on BSA was determined using fluorescence probe methods.

It was observed from fluorescence measurements that the number of bound SDS molecules does not depend on the presence of the disulfide bridges. Reduced proteins wrap more efficiently around the micelle-like structures, resulting in somewhat smaller complexes, as observed with DLS.

Concentrated BSA-SDS solutions and the corresponding heat-set gels were investigated using DLS and fluorescence probe methods. Correlation lengths in the gel were determined and it was concluded that SDS forms micelle-like aggregates on BSA in concentrated solution and gel phase. The gel region in the ternary phase diagram BSA-SDS-3.1 mM NaN₃ has been determined at room temperature.

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Warner, Mark Robert Edward. "Surfactant driven films." Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415666.

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Lewis, R. W. "Pulmonary surfactant metabolism." Thesis, Cardiff University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332108.

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11

Kämpfen, Bruno. "Neonatale Surfactant-Therapie /." Bern, 1991. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.

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12

Neimert-Andersson, Kristina. "Synthesis of Novel Polyhydroxyl Surfactants. Influence of the Relative Stereochemistry on Surfactant Properties." Licentiate thesis, KTH, Chemistry, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1687.

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This thesis deals with the synthesis and characterization ofnovel polyhydroxyl surfactants. The first part describes thesynthesis of a number of stereoisomers of a polyhydroxylsurfactant, and the second part concerns surface chemicalcharacterization.

A stereodivergent route for preparation of the hydrophilichead group was developed, featuring consecutive stereoselectivedihydroxylations of a diene. This afforded in total fourdifferent polyhydroxyl head groups. These surfactant headgroups were natural and unnatural sugar analogues, and wereused for the coupling with two different hydrophobic tailgroups.

Three of these surfactants were used to investigate thechiral discrimination in Langmuir monolayers at an air-waterinterface. The isotherms showed a remarkable difference incompressibility between surfactants of diastereomericrelationship and also a pronounced chiral discriminationbetween racemic and enantiomerically pure surfactants favoringheterochiral discrimination.

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Neimert-Andersson, Kristina. "Synthesis of Polyhydroxylated Surfactants : Comparison of Surfactant Stereoisomers and Investigation of Haemolytic Activity." Doctoral thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-461.

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Ramos, Lierge [UNESP]. "Estudos biofísicos da Hemoproteína extracelular de Amynthas gracilis (HbAg) na ausência e na presença de surfactantes." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/151572.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
As hemoglobinas constituem um grupo de proteínas que desempenham um papel vital nos organismos. Suas propriedades intrínsecas, assim como a sua relação estrutura-atividade, envolvem fenômenos tais como a cooperatividade e afinidade por ligantes específicos, como o oxigênio, que estão associados a uma variedade de processos que viabilizam a vida. As hemoproteínas, em especial as hemoglobinas de anelídeos têm sido objeto de estudo de diferentes grupos de pesquisa, devido a sua alta estabilidade oligomérica, resistência à oxidação, alta cooperatividade e afinidade por ligantes específicos, apresentando um alto potencial em aplicações biotecnológicas como, por exemplo, substituto sanguíneo. Estudos sobre a caracterização estrutural e a determinação da estabilidade de hemoproteínas na presença de surfactantes, por meio de várias técnicas como absorção ótica, emissão de fluorescência, CD (Dicroísmo Circular) e espalhamento de luz podem trazer informações sobre esta classe de proteínas, principalmente sobre o mecanismo de oxidação, dissociação e desnaturação. Desta forma, no presente projeto de pesquisa objetivou realizar a caraterização biofísica da hemoglobina extraída de Amynthas gracilis (HbAg) na presença de surfactantes iônicos (SDS e CTAC) nos valores de pH 5,0 e 7,0. Os resultados nos mostram que ambos os surfactantes são capazes de interagir fortemente com a HbAg, sendo que o pH do meio influência diretamente na intensidade da interação proteína-surfactante. O SDS em pH 5,0 interage fortemente com a HbAg formando precipitados de complexo proteína-surfactante, podendo ser observados em baixas concentrações de SDS (0,01 – 0,2 mmolL-1). Enquanto que para o CTAC ocorre uma forte interação entre o surfactante e a HbAg em pH 7,0 em uma faixa de concentração de 0,01 – 0,07 mmolL-1. A formação de agregados nestes sistemas provavelmente ocorre em função do ponto isoelétrico (pI) da HbAg ser ácido (6,0 ±3), assim como o de outras Hb extracelulares, como resultado de uma forte interação eletrostática. As medidas espectroscópicas indicam que com o aumento da concentração dos surfactantes ocorre a ressolubilização dos agregados. Os resultados obtidos neste estudo demonstraram que o SDS e o CTAC promovem o processo de oxidação/dissociação da HbAg em baixas concentrações e que nas concentrações máximas de surfactantes utilizadas neste trabalho o processo de desnaturação da HbAg não é completo.
Hemoglobins are a group of proteins that play a vital role in organisms. Their intrinsic properties, as well as their structure-activity relationship, involve phenomena such as cooperativity and affinity for specific ligands, such as oxygen, which are associated with a variety of processes that make life possible. Hemoproteins, especially hemoglobins of annelids have been studied by different research groups, due to their high oligomeric stability, resistance to oxidation, high cooperativity and affinity for specific ligands, presenting a high potential in biotechnological applications, for example, a blood substitute. Studies on the structural characterization and determination of hemoprotein stability in the presence of surfactants by optical absorption, fluorescence emission, CD and light scattering can bring information about this class of proteins, mainly on the mechanism of dissociation and denaturation. Thus, in the present master's project the main objective was to perform biophysics characterization studies, with the hemoglobin extracted from the annelid of Amynthas gracilis (HbAg) in the presence of ionic surfactants (SDS and CTAC) at pH values 5,0 and 7,0. The results show that both surfactants are capable of interacting strongly with HbAg, and the pH of the medium directly influences the intensity of the protein-surfactant interaction. SDS at pH 5.0 strongly interacts with HbAg forming precipitates of protein-surfactant complex, can be observed with low concentrations of SDS (0.01 - 0.2 mmolL -1). While for CTAC a strong interaction between surfactant and HbAg occurs at pH 7.0 in a concentration range of 0.01-0.07 mmolL-1. The formation of aggregates in these systems probably occurs as a function of the isoelectric point (pI) of HbAg being acid (6.0 ± 3), as well as that of other extracellular Hb, as a result of a strong electrostatic interaction. This study showed that SDS and CTAC promote the oxidation/dissociation process of HbAg at low concentrations and that at the maximum concentrations of surfactants used in this work the denaturing process of HbAg is not complete.

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Osei-Prempeh, Gifty. "FUNCTIONALIZATION OF FLUORINATED SURFACTANT TEMPLATED SILICA." UKnowledge, 2007. http://uknowledge.uky.edu/gradschool_diss/542.

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Surfactant templating provides for the synthesis of ordered mesoporous silica and the opportunity to tailor the pore size, pore structure, particle morphology and surface functionality of the silica through the selection of synthesis conditions and surfactant template. This work extends the synthesis of nanostructured silica using fluorinated surfactant templates to the synthesis of organic/inorganic composites. The effect of fluorinated surfactant templates (C6F13C2H4NC5H5Cl, C8F17C2H4NC5H5Cl and C10F21C2H4NC5H5Cl), which have highly hydrophobic fluorocarbon tails, on functional group incorporation, accessibility, and silica textural properties is examined and compared to properties of hydrocarbon surfactant (C16H33N(CH3)3Br, CTAB) templated silica. Hydrocarbon (vinyl, n-decyl and 3-aminopropyl) and fluorocarbon (perfluoro-octyl, perfluorodecyl) functional group incorporation by direct synthesis is demonstrated, and its effects on silica properties are interpreted based on the aggregation behavior with the surfactant templates. Silica materials synthesized with CTAB possess greater pore order than materials synthesized with the fluorocarbon surfactants. The incorporation of the short vinyl chain substantially reduces silica pore size and pore order. However, pore order increases with functionalization for materials synthesized with the fluorinated surfactant having the longest hydrophobic chain. The incorporation of longer chain functional groups (n-decyl, perfluorodecyl, perfluoro-octyl) by direct synthesis results in hexagonal pore structured silica for combinations of hydrocarbon/fluorocarbon surfactant and functional groups. The long chain of these silica precursors, which can be incorporated in the surfactant micelle core, affect the pore size less than vinyl incorporation. Synthesis using the longer chain fluoro-surfactant (C8F17C2H4NC5H5Cl) template in ethanol/water solution results in highest incorporation of both n-decyl and the fluorocarbon functional groups, with a corresponding loss of material order in the fluorinated material. Matching the fluorocarbon surfactant (C6F13C2H4NC5H5Cl) to the perfluoro-octyl precursor did not show improved functional group incorporation. Higher incorporation of the perfluoro-octyl functional group was observed for all surfactant templates, but the perfluoro-decyl silica is a better adsorbent for the separation of hydrocarbon and fluorocarbon tagged anthraquinones. Incorporating a reactive hydrophilic functional group (3-aminopropyl) suggests further applications of the resulting nanoporous silica. Greater amine incorporation is achieved in the CTAB templated silica, which has hexagonal pore structure; the order and surface area decreases for the fluorinated surfactant templated material.

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Gomez, Gil Leticia. "The interaction between cholesterol and surfactant protein-c in lung surfactant." Doctoral thesis, Universite Libre de Bruxelles, 2009. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210205.

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The presence of cholesterol is critical in defining a dynamic lateral structure in pulmonary

surfactant membranes, including the segregation of fluid-ordered and fluid-disordered phases.

However, an excess of cholesterol has been associated with impaired surface activity both in

surfactant models and in surfactant from injured lungs. It has also been reported that surfactant

protein SP-C interacts with cholesterol in lipid/protein interfacial films. In the present study, we

have analyzed the effect of SP-C on the thermodynamic properties of phospholipid membranes

containing cholesterol and on the ability of lipid/protein complexes containing surfactant

proteins and cholesterol to form and re-spread interfacial films capable of producing very low

surface tensions upon repetitive compression-expansion cycling. We have also analyzed the effect of cholesterol on the

structure, orientation and dynamic properties of SP-C embedded in physiologically relevant

model membranes.

Doctorat en Sciences
info:eu-repo/semantics/nonPublished

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17

Goldsipe, Arthur Clayton. "Molecular-thermodynamic theories of micellization of multicomponent surfactant mixtures and of pH-sensitive surfactants." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/34277.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2006.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 249-264).
This thesis focuses on two research areas that are particularly relevant to the practical application of surfactant science: (1) the micellization of multicomponent surfactant mixtures, and (2) the micellization of pH-sensitive (or amphoteric) surfactants. Surfactant formulations of practical utility typically consist of many surfactant components. In many practical applications, pH-sensitive surfactants are added as a secondary surfactant because they enhance performance properties, including solubility, foaming, and mildness to the skin or to the eyes. In addition, pH-sensitive surfactants may be used eectively in novel applications where pH variations can be utilized to control self-assembly, including controlled drug release, targeted gene delivery, and the fabrication of nanoscale materials for optics, electronics, and sensors. First, a molecular-thermodynamic (MT) theory was developed to account for counterion binding to mixed micelles composed of ionic-nonionic and ionic-zwitterionic binary surfactant mixtures. The theory successfully predicted the degree of counterion binding ([beta]) of monovalent and multivalent ions to mixed micelles as a function of the micelle composition ([alpha]).
(cont.) The theory was also found to be consistent with the concept of critical counterion binding. An inection in the [beta vs. [alpha] curve was correlated to a micelle shape transition. Second, the MT theory was generalized to include pH eects in order to model the micellization of pH-sensitive surfactants. The theory was validated by comparing predictions of critical micelle concentrations (cmc's), micelle aggregation numbers, and micellar titration behavior to experimental data for alkyldimethylamine oxide surfactants, which are cationic in the protonated state (at low pH) and zwitterionic in the deprotonated state (at high pH). The MT theory qualitatively reproduced the minimum in the cmc and the maximum in the micelle aggregation number, which are both observed experimentally at intermediate pH values, resulting from the synergy between the two forms of the pH-sensitive surfactant in the micelle. This self-synergy, which was previously attributed by other researchers to the formation ofsurfactant-surfactant hydrogen bonds in the micelle, was rationalized instead in terms of electrostatic interactions operating between surfactants and bound counterions in the micelle. Very good quantitative agreement was obtained for the predicted cmc's in solutions containing no added salt.
(cont.) In particular, the experimentally observed maximum in the cmc, which originated from changes in the solution ionic strength, was reproduced by the MT theory but not by the empirical regular solution theory (RST). Micellar titration data were also examined in terms of the relative values of the micellar deprotonation equilibrium parameter (pK). The pK was related to the derivative of the electrostatic contribution to the free energy of micellization ( gelec) with respect to . The molecular model of gelec predicted pK > 0 in the limit of micelles composed entirely of the deprotonated form of the pH-sensitive surfactant, consistent with the experimental data. Third, a theory based on RST was developed to model the titration behavior of micelles containing a pH-sensitive surfactant and an arbitrary number of conventional surfactants. The conventional surfactants were successfully modeled as a single eective surfactant, thus considerably simplifying the theoretical analysis of multicomponent surfactant mixtures. The RST description was validated using experimental micellar titration data for single surfactant systems (obtained from the literature) and for binary surfactant mixtures (measured as part of this thesis).
(cont.) Experimental uncertainties in the micellar titration data were examined, and a new method was introduced to account for these uncertainties by using a weighted regression analysis. Fourth, a MT theory was developed to model the micellization of mixtures containing an arbitrary number of conventional surfactants. The maximum micelle radius was examined theoretically for a ternary surfactant mixture. Due to the limited availability of experimental data, only the predicted cmc's were compared with the experimental cmc's. Good agreement was obtained for the predicted cmc's, which were comparable to, and sometimes better than, the cmc's determined using RST. The MT theory was also used to model a commercial nonionic surfactant (Genapol UD-079), which was modeled as a mixture of 16 surfactant components. The predicted cmc agreed remarkably well with the experimental cmc. The monomer concentration was predicted to increase signicantly above the cmc. In addition, the monomer and the micelle compositions were predicted to vary signicantly with surfactant concentration. These composition variations were rationalized in terms of competing steric and entropic eects and a micelle shape transition near the cmc.
(cont.) Finally, the MT theory was further generalized to model the micellization behavior of mixtures of a pH-sensitive surfactant and an arbitrary number of conventional surfactants. Predicted values of the solution pH of mixtures of a pH-sensitive surfactant and an ionic surfactant, as well as of the cmc's of mixtures of two pH-sensitive surfactants, compared favorably with the experimental values. The MT theory was also validated using micellar titration data for varying compositions of mixed micelles containing dodecyldimethylamine oxide (C12DAO) and a cationic, nonionic, or anionic surfactant. The MT theory accurately modeled the titration behavior of C12DAO mixed with the nonionic surfactant. However, C12DAO appeared to interact more favorably with the anionic and the cationic surfactants than waspredicted by the MT theory. The MT theories presented in this thesis represent the rst molecular-based models of the micellization behavior of the following systems: (1) pH-sensitive surfactants, (2) mixtures of three or more conventional surfactants, and (3) mixtures of pH-sensitive surfactants and conventional surfactants. The MT theories resulted in qualitative and quantitative predictions of the micellization properties for a variety of surfactant systems.
(cont.) A simpler theory based on RST was also developed to model titrations of micelles containing pH-sensitive and conventional surfactants. In addition, this thesis resulted in the rst experimental study of the eect of micelle composition on the titration behavior of mixed micelles containing a pH-sensitive surfactant and a conventional surfactant. The resulting MT theories have provided fundamental, physical insight, and they may also decrease the need for the costly and time-consuming process associated with "trial-and-error" surfactant formulation.
by Arthur Clayton Goldsipe.
Ph.D.

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18

Worthman, Lynn-Ann D. "Surfactant protein A (SP-A) affects pulmonary surfactant morphology and biophysical properties." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0014/MQ34241.pdf.

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19

Hockey, Peter Morey. "Pulmonary surfactant and asthma." Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274434.

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20

Wong, Jeffrey. "Simulations of Surfactant Spreading." Scholarship @ Claremont, 2011. http://scholarship.claremont.edu/hmc_theses/1.

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Thin liquid films driven by surface tension gradients are studied in diverse applications, including the spreading of a droplet and fluid flow in the lung. The nonlinear partial differential equations that govern thin films are difficult to solve analytically, and must be approached through numerical simulations. We describe the development of a numerical solver designed to solve a variety of thin film problems in two dimensions. Validation of the solver includes grid refinement studies and comparison to previous results for thin film problems. In addition, we apply the solver to a model of surfactant spreading and make comparisons with theoretical and experimental results.

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21

Brooks, Jason Travis. "Polymers in surfactant mesophases." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259541.

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22

Turner, Matthew S. "Dynamics of surfactant systems." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386906.

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23

Azaga, Rokaya Mohammed Mohammed. "Surfactant aggregation in DESs." Thesis, University of Leicester, 2018. http://hdl.handle.net/2381/43113.

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Deep eutectic solvents (DESs) have attracted significant attention for a wide range of applications including metal deposition, natural product extraction, metal recycling and catalysis. In general they are good at solubilising polar and charged solutes and hence their properties can be tuned. This study aims to investigate how the properties of DESs can be modified by the addition of surfactants. One aim is to understand how and why surfactants aggregate and how their surface activity differs from aqueous solutions. Firstly, the physical properties of three DESs are characterised containing different surfactants. The critical micelle concentrations, CMC are analysed together with the extent of aggregation. It was found that CMC values of SDS in Reline and Glyceline are smaller than in aqueous systems while in Ethaline the value are similar to those in water. Dynamic light scattering and viscosity data show that supramolecular aggregates of SDS in Ethaline change from cylindrical to liquid crystalline phases at about 3 times the CMC concentration. Moreover, the thermodynamic parameters of the micellization indicated that SDS aggregation was enthalpy controlled. The pattern of the micelle aggregation was different to that observed in water. Surfactant aggregates are found to form despite the high ionic strength due to that large choline cations having a low charge density. The interface properties of surfactants were studied and it was found that the aggregation was favoured in media with a higher surface energy as this disfavoured the solubilisation of monomers. The surfactants were found to be less surface active than they were in aqueous solutions. This was proposed to be due to the high ionic strength of the DESs meaning that charge-charge interactions between the interface and the surfactant were less important. The implication of this is demonstrated when surfactants were tested as brighteners in copper electroplating solutions. It was found that surfactants did not affect the deposit morphology as significantly as molecules which specifically adsorbed on the copper surface which indicated the method by which brighteners functioned in DESs was not primarily through charge-charge interactions.

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24

Brockbank, Sharon. "Surfactant stabilised gas microcells." Thesis, University of Bristol, 1997. http://hdl.handle.net/1983/1855f690-b30d-408f-81b4-e35bcbab6b63.

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25

Mears, Sarah Jane. "Polymer, particle, surfactant interactions." Thesis, University of Bristol, 1996. http://hdl.handle.net/1983/50736698-01b4-4c84-bc85-7f94e411a6f2.

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26

Mahmood, Zahid. "Characterisation of surfactant mesophases in mult-phase systems : high sensitivity, surfactant specific electrodes." Thesis, University of Salford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.494543.

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The project involves research being carried out on surfactants and the multi-phase systems that they produce. The aim is to understand the mesomorphous behaviour exhibited by different multi-phase systems when conditions (time, temperature, shear tension, concentration of surfactants) are altered. The characterisation of surfactant mesophases in multi-phase systems can be observed by methods involving: polarising optical microscopy, X-ray diffraction and use of surfactant-specific electrodes to measure conductivity (mV). Investigating ternary systems composed of surfactant: co-surfactant components led to the understanding of the behaviour surfactants exhibit, as they exist in different mesophases. The application of the surfactant ion-specific coated-wire electrode (CWE) to ternary system mixtures presenting liquid crystals of different morphological behaviour (i.e. mesophases), allowed to determine and distinguish between the differing properties of these mesophases in terms of monitoring free surfactant monomer levels. The CWE was applied to surfactant mixtures in the hope of determining important information, for example; observing Nernstian behaviour, monitoring the onset of aggregation, i.e. the CMC or more complex aggregates like the hexagonal or lamellar phase, along with the free surfactant monomer levels present in the latter part of these concentrated mixtures. Whilst also investigating the occurrence of phase transitions between different liquid crystal mesophases and how their effects on the CWE could be explained in terms of electrochemical response or free monomer concentrations. Further modelling allowed for the determination of the interaction behaviour between a surfactant and co-surfactant within a ternary system. To conclude, the limitations of the CWE were determined, along with propositions for future development of drug-selective electrodes, which may be applied in the research for investigating the chemical behaviour of drug systems in solution.

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27

Kojtari, Adeline Bajame Foley Joe Preston. "Studies on surfactant purity, chiral composition, and novel surfactant synthesis in chiral electrokinetic chromatography /." Philadelphia, Pa. : Drexel University, 2009. http://hdl.handle.net/1860/3162.

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28

Agarwal, Vivek. "Microstructure studies in surfactant systems /." View online ; access limited to URI, 2004. http://wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3160026.

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29

Hortenbach, Heiko. "Surfactant-gesteuertes Wachstum von Siliciden." Doctoral thesis, Universitätsbibliothek Chemnitz, 2003. http://nbn-resolving.de/urn:nbn:de:swb:ch1-200300604.

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Die Methode der Reaktiven Abscheidung wurde benutzt, um zu untersuchen ob und in welcher Weise das Silicidwachstum mittels einer Monolage aus Sb, d.h. mittels eines surfactant (surface active agent), gesteuert werden kann. Hierzu wurden unter UHV-Bedingungen die Metalle Mn, Ti und Ni auf geheizte Si(001) bzw. Si(001)-Sb Substrate abgeschieden. Die Probenanalyse erfolgte durch LEED, RBS, XRD, SEM, TEM und AFM. Die Theorie zum surfactant-gesteuerten Wachstum wird vorgestellt und auf das System des reaktiven Silicidwachstums übertragen. Die Probenanalysen zeigen, dass eine Monolage von Sb in der Lage ist das Wachstum der drei untersuchten Silicide zu beeinflussen. Für das System der Höheren Mangansilicide kommt es zu einer Erhöhung der Inseldichte um bis zu zwei Größenordnungen und zu Änderungen in den Orientierungsbeziehungen der Silicidinseln. Beim Wachstum der Titansilicidschichten konnte durch das surfactant die pinhole-Bildung unterdrückt werden. Das dritte untersuchte Silicid ist das Nickeldisilicid. In diesem Fall wird der Ort der Keimbildung von der Si-Oberfläche in das Volumen des Si-Substrates verschoben, d.h. die Oberfläche wird vollständig passiviert, zusätzlich treten neue Orientierungsbeziehungen auf.

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30

Cojocaru, Alice. "Cytoskeletal modulation of surfactant trafficking." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ34059.pdf.

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31

Poirier, Jason S. "Polymer Templating in Surfactant Monolayers." Fogler Library, University of Maine, 2004. http://www.library.umaine.edu/theses/pdf/PoirierJS2004.pdf.

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32

Manning-Benson, Samantha. "The dynamics of surfactant adsorption." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298708.

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33

Casson, Brian Derek. "Phase transitions in surfactant monolayers." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300797.

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34

Simister, E. A. "Neutron reflection from surfactant solutions." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239334.

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35

Nicholls, Richard James. "Surfactant properties in oil solvents." Thesis, University of Hull, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323166.

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36

El, Moaty Ibrahim S. "Surfactant properties of corrosion inhibitors." Thesis, University of Hull, 2011. http://hydra.hull.ac.uk/resources/hull:5807.

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Corrosion is one of the most common, costly and widespread industrial problems in the oil and gas production industry. Surfactant addition is one of many ways to inhibit the corrosion of metals, especially on hard-to-reach surfaces such as the inside of a pipe through which fluid is flowing. The application of small quantities of an inhibitor to production fluids is the most cost-effective method for imparting corrosion protection to a system. Despite the popularity of surfactants as corrosion inhibitors, their actual behaviour inside a pipeline is not well understood. The homologous alkylbenzyldimethylammonium chlorides CnBDMAC series is one of the most common corrosion inhibitors used in the oil industry. This thesis addresses some of the surfactant properties of these corrosion inhibitors which are not studied in detail (or often ignored) through electrochemical studies. Firstly, the adsorption behaviour of these corrosion inhibitors at the air-water interface was investigated as a function of the alkyl chain length, temperature and the concentration of the added electrolyte. The surfactant chain length and brine addition were found to have a great influence on the adsorption behaviour and hence on the critical micelle concentration (cmc). Secondly, the ability of CnBDMAC corrosion inhibitors to stabilize both oil-in-water and water-in-oil emulsions and the phase inversion of the emulsions as the inhibitor structure, temperature, electrolyte concentration and oil type change has been studied. The partitioning behaviour of C16BDMAC between an aqueous brine phase and an oil phase has been investigated as well as a function of electrolyte concentration. Studying the adsorption behaviour of surfactant corrosion inhibitors at solid-liquid interfaces provides important information about their action mechanism, which in turn helps in improving their efficiency. The adsorption behaviour of CnBDMAC molecules has been studied as a function of the surfactant chain length, temperature and electrolyte concentration using the Quartz Crystal Microbalance (QCM) technique. The QCM technique provides an effective, easy to setup and quick in-situ monitoring method for studying qualitatively the adsorption of surfactants at the solid-liquid interface. However, the determined adsorption isotherms were found to overestimate the amount of surfactant adsorbed. Therefore, the depletion method has been used to study the adsorption characteristics of CnBDMAC onto a stainless steel powder. Pipes used in oilfields for crude oil transportation are mainly made of mild steel. Accordingly, it is crucial to understand the adsorption behaviour of these corrosion inhibitors onto the mild steel surface. The effect of surfactant structure, temperature and electrolyte concentration on the adsorption behaviour of CnBDMAC onto mild steel particles using the depletion method has been investigated. In addition, the depletion method has been used to study the adsorption of CnBDMAC onto sand which is one of the main corrosion inhibitor consuming-solids encountered naturally in the oilfield. The adsorption studies performed revealed that these inhibitors have a strong affinity for sand particles, particularly at low temperatures and diluted inhibitor concentrations. Finally, the corrosion inhibition performance of hexadecylbenzyldimethylammonium chloride (C16BDMAC) corrosion inhibitor has been investigated through the linear polarisation resistance technique as a function of the added sand amount. A model has been proposed and applied successfully to determine the percentage decrease in the corrosion inhibition efficiency of C16BDMAC with changes in the amount of sand added.

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Hicks, Jake Thomas. "Surfactant aspects of corrosion inhibition." Thesis, University of Hull, 2007. http://hydra.hull.ac.uk/resources/hull:6996.

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This thesis is concerned with investigating the surfactant aspects of corrosion inhibition. Corrosion inhibitors are of great industrial importance because they are a relatively inexpensive and easily applicable method of protecting oil pipelines against internal corrosion. The performance of corrosion inhibitors is known to depend upon the prevailing conditions within the pipeline. We have used a range of experimental techniques to study corrosion of steel surfaces, adsorption of corrosion inhibitors and the behaviour of inhibitors in mixtures of oil and water in order to understand more about the factors which affect the performance of corrosion inhibitors under oil field conditions. Firstly, electrochemical and weight-loss measurements were used to measure the corrosion rate of steel immersed in aqueous environments under atmospheric conditions and in the presence of dissolved carbon dioxide and hydrogen sulphide. The measurements were repeated in the presence of dodecylbenzyldimethylammonium chloride and I-aminoethyl-2-(8- heptadecenyl)-2-imidazoline acetate, which are thought of as model corrosion inhibitors. Both surfactants were found to effectively reduce the corrosion rate of steel when the dissolved gas was hydrogen sulphide, but were found to increase the corrosion rate in some aerated and carbonated environments. The optical technique ellipsometry has been used to study the adsorption of dodecylbenzyldimethylammonium chloride at the steel-water interface. We have determined the thickness of the surfactant film adsorbed from aqueous solution in the absence of electrolyte. The results are consistent with the formation of a monolayer at inhibitor concentrations close to the critical micelle concentration and possible multilayer formation at higher concentrations. Determination of inhibitor film thickness has not been possible in the presence of electrolyte and corrosive dissolved gases which cause rapid corrosion of the steel surface. The technique has been employed subsequently to study the initial stages of corrosion in the presence and absence of dodecylbenzyldimethylammonium chloride. Scanning electron microscopy and elemental analysis have also been used to examine the changes which occur to the steel surface during corrosion. These results show that the optical properties of the steel surface undergo changes as the steel is attacked by corrosive aqueous solutions and that dodecylbenzyldimethylammonium chloride can increase the rate of these changes or completely suppress them, depending on the nature of the dissolved gas present. Finally, we have investigated the phase behaviour of alkylbenzyldimethylammonium chloride and 1-aminoethyl-2-(8-heptadecenyl)-2- imidazoline acetate using equilibrium partitioning and emulsion phase inversion methods. The results show that variations in common oil field variables, such as temperature, electrolyte concentration and oil type, can lead to the consumption of the aggregated form of water-soluble corrosion inhibitors by partitioning to the oil phase. The results are discussed in terms of the effect of these variables upon the effective geometry of the inhibitor within the monolayer of the aggregates. We have also performed electrochemical corrosion rate measurements in systems containing oil and water, under conditions which cause virtually all of the inhibitor to exist in the oil phase. The results suggest that partitioning of the aggregated form of corrosion inhibitors from water to oil does not adversely affect corrosion inhibition in the aqueous phase.

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38

McLaughlin, Arthur Charles. "Surface properties of surfactant solutions." Thesis, Queen's University Belfast, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334508.

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39

McCoo, Elaine. "Surface properties of surfactant solutions." Thesis, Queen's University Belfast, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333842.

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40

Ashton, P. "Surfactant effects in subcutaneous absorption." Thesis, Cardiff University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380198.

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41

Patel, Rajesh. "Studies of drug-surfactant interactions." Thesis, University College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313319.

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42

Muslim, Abdul-Mueed. "Computer simulations of surfactant monolayers." Thesis, King's College London (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248123.

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43

White, Sarah Jayne. "Polymer surfactant interactions in gels." Thesis, University of Bristol, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385970.

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44

Aessopos, Angelica. "Surfactant instabilities on thin films." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/88902.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.
"June 2005."
Includes bibliographical references (pages 89-92).
The deposition of a surfactant drop over a thin liquid film may be accompanied by a fingering instability. In this work, we present experimental results which identify the critical parameters that govern the shape and extend of the fingering phenomena. It was found that the normalized wavelength, [lambda]/t, scales with Marangoni number, Ma=[Delta][gamma]t/[mu]D, to the -1 exponent for any Marangoni higher than 4.3 · 10⁷. On the other end, for Marangoni < 4.3 · 10⁷ the normalized wavelength scales with Ma to the -0.4 but becomes in addition a funcion of the Prandtl number, Pr=[upsilon]/D, which demonstrates the critical significance of bulk diffusion on the spreding behavior. Finally, we present a numerical implementation of a mathematical model which is capable of reproducing the experimentally observed trends.
by Angelica Aessopos.
S.M.

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45

Tirop, Lucy. "Polymer-surfactant stabilised drug nanoparticles." Thesis, King's College London (University of London), 2012. https://kclpure.kcl.ac.uk/portal/en/theses/polymersurfactant-stabilised-drug-nanoparticles(46bd0161-25d6-4337-ba65-f9fe3627e804).html.

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Wet bead milling, in which the drug is milled in presence of stabilisers such as polymers and surfactants, has enabled the formulation of poorly water-soluble drugs as nanoparticles, with five products having reached the market. During the milling process, the polymer and/or surfactant adsorbs onto the freshly cleaved drug surfaces to provide ionic or steric stabilisation. Despite the success of wet bead milling, mastery of the mechanism behind nanoparticle stabilization is still lacking. To investigate whether any relationship exists between drug, stabiliser and stabilisation, eight structurally different poorly water-soluble drugs were milled in presence of thirteen different pharmaceutically acceptable stabilisers and the resultant particle size determined by photon correlation spectroscopy. Nanoparticles of the BCS class II drugy griseofulvin, could only be produced in presence of anionic stabilisers namely sodium dodecyl sulphate, aerosol-OT or hydroxypropylmethylcellulose acetate succinate. Surfactant adsorption isotherms obtained indirectly by measuring their depletion from solution revealed a maximum surfactant adsorption of ~ 2.2 mg/m2 on the griseofulvin nanoparticle surfaces. The use of ionic surfactants/polymers in oral formulations is however sub-optimal. Consequently, polymer-surfactant co-stabilisation, used to take advantage of the synergy between ionic and non-ionic stabilisers, was investigated by the inclusion of the non-ionic polymer hydroxypropylmethylcellulose (HPMC) into the anionic surfactant-drug slurry prior to milling. The effect of varying HPMC molecular weight and concentration on griseofulvin nanoparticle production was established. Polymer adsorption isotherms were obtained directly via small angle neutron scattering.

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46

Dalton, James Spencer. "The kinetics of surfactant adsorption." Thesis, University of Bristol, 1999. http://hdl.handle.net/1983/d2ce527d-0373-4191-b2d9-8e9e7d81dd9f.

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Cheng, Shu Ian. "Protein separation using surfactant precipitation." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9282.

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Surfactant precipitation applied as a surfactant mediated protein purification technique has considerable potential in protein extraction, and therefore the understanding of the interactions involved and the folding behaviour in the precipitated protein was the first aim of this thesis. The key system parameters such as buffer salt concentration, molar ratio of surfactant to protein and pH which determines the protein stability in protein-surfactant complex formation were evaluated. The surfactant:protein ratio determines saturation of protein binding sites while pH determines the strength of affinity for ionic binding which influences hydrophobic binding with surfactant monomers causing the protein to lose its conformation. The protein-surfactant binding varied for lysozyme, cytochrome c and ribonuclease A with trypsin and α -chymotrypsin, and hence the denaturation profile. In the second aim, protein recovery from surfactant precipitation was enhanced by improving the solvent recovery method and, implementing a new and novel counterionic surfactant recovery method. The effect of a variety of recovery phases and solution conditions on lysozyme recovery was analysed in terms of their ability in maintaining protein stability, recovery yield, and activity. It was found that solvent recovery was limited by solvent polarity and protein solubility, and that the cationic surfactant, trioctylmethylammonium chloride (TOMAC), used to form nonpolar ion pairs with sodium bis-(2-ethylhexyl) sulfosuccinate (AOT) was the most efficient method for recovering protein. The third aim was to assess the influence of protein properties, such as charge and hydrophobicity, on protein separation. The selective extraction of a target protein from mixtures of proteins in both buffer and fermentation broth was investigated. It appears that the optimum surfactant:protein molar ratio for the extraction of the proteins from fermentation broth (lysozyme, cytochrome c and ribonuclease A; 16, 17 and 22 respectively) were similar to those in a buffer system. Lysozyme and ribonuclease A were selectively separated from a binary mixture. The extraction behaviour was well represented by surface charge distribution which is indifferent to system conditions. However, certain broth constituents induced the formation of some unfolded irreversible non-dissolvable precipitate in the recovery process. Finally, the use of non-ionic surfactants, ionic/non-ionic mixed surfactants, and cationic surfactants were investigated in surfactant precipitation system. Non-ionic surfactant does not support direct precipitation of proteins using surfactant or recovery of protein from a protein-surfactant complex, and has no effect in a mixed ionic/non-ionic system. The application of cationic surfactant precipitation to separate trypsin inhibitor was attempted, and good recovery was obtained.

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48

Faizal, Wong Fadzlie Wong. "Protein separation using surfactant precipitation." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/46041.

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Protein precipitation using a variety of surfactants has been shown to have considerable potential as a protein separation technique, and considerable work on using anionic surfactants has been carried out by previous researchers. However, anionic surfactants are only suitable for high pI proteins due to concerns about protein stability. Therefore, the first aim of this work was to develop a surfactant precipitation method for low pI proteins based on using cationic surfactants. The effect of important parameters such as the molar ratio of TOMAC to protein (Rp), and pH on the precipitation of bovine serum albumin, α-amylase, and trypsin inhibitor were examined. Recovery of the TOMAC-protein complex by solvent extraction and counter-ionic surfactant (AOT) was also studied. Varied results were obtained for the three proteins, and were correlated with protein properties, and it was found that the protein’s hydrophobicity and molecular weight were the best predictors for precipitation efficiency and recovery. The second aim of this research was to examine the feasibility of using a biocompatible surfactant – methyl ester sulphonate (MES) as a precipitating-ligand for target proteins in this surfactant precipitation technique. This work was a major breakthrough in the application of a new generation of ‘green’ surfactants for protein extraction. Lysozyme was used as a model protein in a single component system, and the influence of Rp, and pH were examined. Similarly, the recovery of the precipitate using solvent extraction and a counter-ionic surfactant, AOT, was studied. The performance of MES in precipitation was compared to a conventional surfactant, AOT, and it was found that their performance was comparable. This further highlighted its potential to be used as precipitant in protein purification. The third aim of this work was to apply the surfactant precipitation method to the purification of a target protein from a real industrial sample. Bacteriocin produced by Pediococcus acidilactici Kp10 was chosen as a target protein for this purpose. With a concentration of 11.56 mM of AOT (pH 4), precipitate recovery by acetone (0.99 mM NaCl), and a final recovery phase of 20 mM PBS (pH 7), about 86.3% of overall activity recovery, and a purification factor of about 53.8 was obtained. Further, this separation technique was shown to be better than reverse micellar extraction, and aqueous two-phase extraction in terms of performance. Hence, the surfactant precipitation technique was proven to be an effective and a viable separation method.

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Nilsson, Kristina. "Solute exchange across the alveolo-capillary barrier." Lund : Depts. of Clinical Physiology, Malmö University Hospital and Lund University Hospital, Lund University, 1997. http://books.google.com/books?id=A0hrAAAAMAAJ.

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50

Leão, Cláudio. "Desenvolvimento e validação de metodologia para a determinação de monocloroacetato de sódio e dicloroacetato de sódio em cocoamido,N-[(3-dimetilamino)propil],betaína via cromatografia a gás: GC/FID, GC/ECD e GC/MS." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-22082016-150806/.

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O monocloroacetato de sódio (MCAS) e o dicloroacetato de sódio (DCAS) são compostos tóxicos e irritantes ao ser humano e nocivos ao meio ambiente, sendo impurezas indesejáveis na cocoamido propil betaína (CAPB), que é um surfactante anfótero utilizado em produtos de consumo dos segmentos cosmético e domiciliar. Diante dos requisitos de concentração em nível de mg/kg exigidos pelos órgãos reguladores de saúde do governo, tornou-se mandatório o emprego de metodologia com limite de quantificação, precisão e exatidão adequados aos rígidos controles de processo pelos fabricantes da CAPB, bem como, dispor de técnicas convencionais com poder de resolução e proficiência pelo controle de qualidade e neste contexto inseriu-se a cromatografia a gás. Neste estudo foram estabelecidos os procedimentos analíticos que definiram as melhores condições para identificar e quantificar as impurezas MCAS e DCAS na matriz CAPB por meio da cromatografia a gás. A preparação das amostras consistiu da derivação das impurezas MCAS e DCAS a ésteres etílicos e a extração líquido-líquido em hexano para separar dos demais constituintes da matriz. Os modos de detecção acoplados à cromatografia a gás foram a ionização pela chama (GC/FID), a captura de elétrons (GC/ECD) e a espectrometria de massas (GC/MS). A validação comprovou que as metodologias são lineares entre 4 e 50 mg/kg com recuperação de 70 a 120%, apresentam limites de quantificação inferiores a 10 mg/kg e produziram médias e incertezas similares na amostra examinada, constituindo-se alternativas para a determinação de cloroacetatos em betaínas.
The sodium monochloroacetate (MCAS) and the sodium dichloroacetate (DCAS) are toxic and irritating compounds to humans and harmful to the environment, being undesirable impurities in cocoamidepropyl betaine (CAPB), which is a amphoteric surfactant used in consumer products of cosmetic and household segments. Considering the content requirements at level mg/kg defined by governmental health agency, became mandatory the use of analytical methods with appropriate precision, accuracy and quantification limit to rigid process controls by CAPB manufacturers, as well as, to have available conventional techniques with good resolution and proficiency for quality control staff and in this context was inserted the gas chromatography. In this study, the analytical procedures were established to define the best conditions to identify and quantify the impurities MCAS and DCAS in CAPB matrix by gas chromatography. The sample preparation consisted of MCAS and DCAS derivation to ethyl esters and liquid-liquid extraction in hexane to separate them from the other constituents of matrix. The detection modes coupled to gas chromatography were the flame ionization (GC/FID), electron capture (GC/ECD) and mass spectrometry (GC/MS). The validation ensured that the methodologies are linear between 4 and 50 mg/kg with recovery 70 to 120%, presents quantification limits less than 10 mg/kg and produced similar averages and uncertainties in the examined sample, constituting an alternative for determination of chloroacetates in betaines.

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Dissertations / Theses on the topic 'Surfactant'

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