Dissertations / Theses on the topic 'Sulfate(lauryl)'

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The main anionic surfactants world widely used are the sodium dodecyl benzene sulfonate (LAS) and sodium dodecyl sulfate (DSS), which are mainly used in the manufacturing of domestic and personal hygiene products. As a consequence of the great and increasing consumption of LAS and DSS there is an increasing wareness regarding the adverse effects of these compounds to the organisms and environment. The present study aimed to evaluate the acute and chronic toxicity of the compounds LAS and DSS to the cladocerans Daphnia similis, Ceriodaphnia dubia and Ceriodaphnia silvestrii. It was also evaluated the toxicity of the water and sediments of four reservoirs and one stream of São Paulo State Analyses of LAS concentrations in the water of these reservoirs were also performed by Liquid chromatography. Acute toxicity tests indicated a value of CE(I)50;48h for LAS of 14.17 mg L-1 to D. similis, 11.84 mg L-1 to C. dubia and 13.51 mg L-1 to C. silvestrii. Significant changes in the viability of the cladoceran offsprings were observed for C. dubia and C. silvestrii exposed to the LAS, with values of CENO equal to 1.0 mg L-1 to C. dubia and 2.5 mg L-1 to C. silvestrii. It was concluded that the maximum permissible concentration of 0.5 mg L-1 surfactants as established by the resolution CONAMA nº. 357/2005 (Brazilian Ministry of Environment) in order to protect aquatic communities is adequate, considering the sensitivity of the native species C. silvestrii. The results of the acute toxicity tests with DSS indicated a CE(I)50;48h value of 12.82; 4.37 and 5.42 mg L-1, for D. similis, C. dubia and C. silvestrii, respectively. A CENO value of 2.0 mg L-1 was obtained in the chronic toxicity tests for C. silvestrii. The surfactant LAS was detected in all the water samples collected in the Lobo (Broa), Lagoa Dourada and Fazzari reservoirs, but at concentrations lower than 5 mg L-1 (the method limit of detection). The toxicity tests with environmental samples revealed that there is no toxicity in the water of the Lobo and Lagoa Dourada sampled, however the water of Monjolinho Reservoir was toxic to D. similis and Fazzari stream was toxic to D. similis and C. dubia. Only the sediment of Monjolinho Reservoir was not toxic to cladocerans.
Os principais surfactantes aniônicos disponíveis no mercado mundial são o dodecil benzeno sulfonato de sódio (LAS) e o dodecil sulfato de sódio (DSS), utilizados principalmente em produtos de limpeza doméstica e de higiene pessoal. Devido ao grande consumo mundial de LAS e de DSS há uma crescente preocupação sobre os efeitos adversos destes compostos no ambiente e aos organismos. Este trabalho teve por objetivo avaliar a toxicidade aguda e crônica do LAS e do DSS aos organismos-teste Daphnia similis, Ceriodaphnia dubia e Ceriodaphnia silvestrii. Foi também avaliada a toxicidade da água e dos sedimentos em quatro reservatórios e um riacho do estado de São Paulo por meio de testes de toxicidade aguda e da análise quantitativa do surfactante LAS. Os testes de toxicidade aguda indicaram uma CE(I)50;48h do LAS de 14,17 mg L-1 para D. similis, 11,84 mg L-1 para C. dubia e 13,51 mg L-1 para C. silvestrii. Nos testes crônicos realizados foi observada significativa alteração viabilidade da progênie de C. dubia e C. silvestrii exposta ao LAS, com valores de CENO igual a 1,0 mg L-1 para C. dubia e 2,5 mg L-1 para C. silvestrii. Pode-se concluir que o valor máximo permissível de surfactantes de 0,5 mg L-1, estabelecido pela Resolução CONAMA nº. 357/2005 em águas destinadas à proteção das comunidades aquáticas, é adequado para a espécie nativa C. silvestrii. Nos testes de toxicidade aguda de DSS foram obtidos valores de CE(I)50;48h de 12,82; 4,37 e 5,42 mg L-1, para D. similis, C. dubia e C. silvestrii, respectivamente. No ensaio de toxicidade crônica obteve-se valor de CENO igual a 2,0 mg L-1 para C. silvestrii. O surfactante LAS foi detectado nas amostras de água dos Reservatórios do Lobo (Broa), Lagoa Dourada e Represa do Monjolinho em concentração inferior a 5 mg L-1. Os testes revelaram que não há toxicidade aguda aos cladóceros da água da Lagoa Dourada e do Reservatório do Lobo, havendo, contudo, toxicidade da água da Represa do Monjolinho para D. similis e da água do Córrego do Fazzari para os cladóceros D. similis e C. dubia. Somente a amostra de sedimento da Represa do Monjolinho não causou toxicidade aos cladóceros.

La composition de la couche adsorbee a l'interface de systemes diphasiques : eau+nacl; dodecane, dodecylsulfate de sodium ou dodecylbenzenesulfonate comme agent de surface et butanol, pentanol ou alcool benzylique comme coagent de surface, est determinee par application de la loi de gibbs

Tensoativo aniônico com amplo espectro de utilização, o álcool laurílico etoxilado sulfatado (SLES) é um dos álcoois graxos mais consumidos nos segmentos de cosméticos e detergentes. Da forma como esse processamento ocorre no Brasil, a cadeia de produção compreende transformações nos segmentos agrícola e industrial, cujos consumos de recursos e geração de rejeitos podem proporcionar impactos ambientais significantes, que devem ser conhecidos e dimensionados. Este estudo realizou uma avaliação do desempenho ambiental da produção de SLES para o arranjo tecnológico médio praticado no país, utilizando, para tanto, a metodologia de Avaliação de Ciclo de Vida (ACV). Os resultados obtidos mostraram que os estágios responsáveis por impactos ambientais mais significativos são: (i) processamento de álcool laurílico a partir de óleo de palmiste produzido na Ásia; (ii) geração de energia térmica a partir de queima de combustíveis fósseis para uso em operações diversas nos processos industriais; e (iii) a produção de óxido de etileno a partir de ativos petroquímicos. A partir desta avaliação foram então concebidas e modeladas alternativas de processo cuja introdução na cadeia de produção resultaria, ao menos em tese, em melhoria do desempenho ambiental global do processamento de SLES. Cada solução foi então organizada dentro de um cenário específico; são eles: Cenário I: obtenção de SLES a partir de óleo de palmiste produzido no Brasil; Cenário II: produção de SLES a partir de álcool laurílico sintético; Cenário III: geração de energia térmica para os estágios industriais de processo a partir de queima de biomassa; e Cenário IV: produção de SLES tendo como ativo de formulação óxido de etileno derivado de cana-de-açúcar. A técnica de ACV foi, mais uma vez aplicada à situação com vistas a examinar os efeitos, em âmbito sistêmico, proporcionados pelas modificações. O estudo conclui que a substituição do óleo de palmiste importado da Ásia por equivalente produzido no Brasil ou mesmo, por forma alternativa derivada de fonte sintética traria melhorias no desempenho ambiental em praticamente todas as categorias de impacto analisadas. Já a alternativa de uso de biomassa para produção de energia térmica apresenta melhores desempenhos em termos de Mudanças Climáticas e Depleção de Recursos Fósseis, mas resultam em efeitos negativos em termos de Ocupação do Solo, Eutrofização e Ecotoxicidade em comparação à situação original. Por fim, a incorporação de óxido de etileno de origem renovável ao processo não se reverteu em vantagens expressivas para o desempenho ambiental global do processo em nenhuma das categorias de impacto avaliadas. Uma análise ampla efetuada em termos de Balanço de CO2 para os cinco cenários avaliados demonstrou que a incorporação de ativos de fonte renovável resulta em alteração do perfil de impactos quanto à categoria de Mudanças Climáticas entre os cenários com relação às estimativas originais. Isso se deve essencialmente à incorporação ao balanço de parcelas referentes à fixação de CO2 do ar via fotossíntese e emissões de CO2 biogênico ocorridas durante o estágio agrícola, que passaram a ser consideradas por conta desta análise.
Sodium lauryl ether sulfate (SLES), a multi-purpose anionic surfactant, is one of the most used fatty alcohols for cleaning and personal care products. The chain of production in Brazil involves transformations in the agricultural and industrial sectors, tapping resources and generating waste, and can lead to significant environmental impact yet to be known and quantified. The present study assessed the environmental performance of the production of SLES for the average technological disposition in Brazil, using the methodology of Life Cycle Assessment (LCA). Results show that the stages responsible for the most significant environmental impact are: (i) processing of lauryl alcohol from palm kernel oil produced in Asia; (ii) generation of thermal energy from burning fossil fuel in various operations of the industrial process; and (iii) production of ethylene oxide from petrochemical sources. From this assessment, we designed alternative processes that if introduced in the chain of production, would in theory result in better global environmental performance of SLES processing. Each solution was then organized within specific scenarios, namely: Scenario I: obtainment of SLES from palm kernel oil produced in Brazil; Scenario II: production of SLES from synthetic lauryl alcohol; Scenario III: generation of thermal energy for the industrial stages of processing from burning biomass; and Scenario IV: production of SLES from ethylene oxide derived from sugarcane. LCA modeling was applied to examine the systemic effects made by these modifications. The study concludes that environmental performance improvements in virtually all impact categories analyzed could be achieved by replacing palm kernel oil imported from Asia by an equivalent produced in Brazil, or even by an alternative form derived from a synthetic source. The use of biomass for thermal energy, on the other hand, has better performance in terms of Climate Change and Fossil Depletion, but negative effects in terms of Agricultural Land Occupation, Eutrophication, and Ecotoxicity when compared to the original scenario. Finally, the incorporation of renewable origin ethylene oxide did not lead to expressive advantages for global environmental performance in any of the categories. A wide analysis of CO2 Balance for the five analyzed scenarios showed that the incorporation of renewable sources would result in improvements in Climatic Change when compared to the original estimations. This is due, essentially, to the incorporation of the balance of percentages of air CO2 fixation through photosynthesis and biogenic CO2 emissions that occur during the agricultural stage, which are taken into account in this analysis.

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Surfactants are commonly used as cleansing agents and yet there are concerns they may also have a role in skin irritation. Presently, the lack of suitable methods for quantitative and qualitative analysis of surfactant deposition on skin has hindered the in-depth investigation of such effects. Here, we report the application of reverse phase liquid chromatography electrospray ionisation mass spectrometry (LC/ESI-MS/MS) assays for two surfactants commonly used in consumer products, namely sodium lauryl ether sulphate (SLES) and laurylamidopropyl betaine (LAPB), to a baseline study aiming to assess deposition levels on human skin. The linearity of the assays was established at 3-20 ng, with coefficient of variation below 5%. Detection limits were 100 pg for LAPB and 1 ng for SLES; quantitation limits were 500 pg for LAPB and 2.5 ng for SLES. The baseline study was conducted using a panel of 40 healthy volunteers. Skin extract samples were taken in triplicate from forearms, using ethanol. SLES was detected on most volunteers, with 75% of them having SLES deposits in the range of 100-600 ng/cm2. LAPB was detected on the skin of all volunteers with 85% of them having deposit levels within the concentration range of 1-100 ng/cm2. These results demonstrate the extent to which commonly used surfactants remain on the skin during the day. The analytical methods reported here can be applied to the investigation of surfactants in relation to general skin condition and the development and optimisation of new consumer wash products.
EPSRC

Les resultats experimentaux (cinetique rapide d'adsorption, parametre d'equilibre des isothermes d'adsorption et variation du potentiel zeta des particules de charbon) montrent une augmentation de la capacite d'adsorption du dodecylsulfate de sodium en presence d'ions metalliques et une inhibition mutuelle de l'adsorption en presence d'alcools aliphatiques et de composes organiques

Dans cette these sont etudiees les proprietes dynamiques d'un systeme eau/toluene/sds/butanol qui forme spontanement des structures de type cellulaire a l'echelle nanoscopique, ou l'huile est confinee dans des cellules polyedriques separees par un film d'eau. A temperature ambiante le systeme est liquide et l'arrangement des cellules est macroscopiquement desordonne. Lorsque la temperature augmente le systeme devient viscoelastique et forme des structures cellulaires cristallines cubiques. La combinaison de differentes techniques experimentales a permis d'explorer la dynamique a differentes echelles d'espace (1 nm a 1 m) et de temps (1 ns a 100 s). Il en resulte une image complete de la dynamique dans ces structures cellulaires. La spectroscopie par echo de spin neutron (nse) a permis de sonder ces systemes a l'echelle locale de la cellule. Elle met en evidence que les cellules sont soumises a des fluctuations de forme. L'analyse des donnees fait de plus apparaitre un processus diffusif qui est attribue a des fluctuations de position des cellules dans la cage formee par leurs voisines. Une augmentation significative de la dynamique des fluctuations des cellules est observee lorsque le reseau cellulaire s'ordonne. Ce comportement nous a permis de preciser le role de ces fluctuations dans la stabilite de ces structures. L'etude par diffusion dynamique de la lumiere (dls) fait apparaitre deux modes diffusifs bien distincts. Le mode rapide correspond a un processus de compression-dilatation du reseau cellulaire. Ce processus a pour origine la nature dynamique de la structure a l'echelle de la cellule (mise en evidence par nse). Le coefficient de diffusion du mode lent et celui du sds mesure par diffusion rmn decrivent un meme processus diffusif qui correspond a une diffusion macroscopique des cellules. L'existence de ce processus diffusif dans le domaine cubique permet de rendre compte des proprietes viscoelastiques des structures cellulaires cubiques.

Étude de la complexation de métaux de transition (nickel, cobalt) par des ligands bidentes du type hydroxy-8 quinoline dans des milieux homogènes (eau et méthanol) et des milieux microhétérogènes (solution micellaire, microémulsion), tant du point de vue thermodynamique que cinétique

Après une bibliographie concernant la structure des phases lyotropes et leurs défauts ainsi qu'une description des techniques cryogéniques utilisées en microscopie électronique, les résultats concernant les phases H, Q et L du système SDS-Formamide observées en cryofracture sont présentés. En plus des phases H, Q et L détectées en diffraction des rayons X, apparaît une structure à cylindres flexibles caractérisée par des défauts (dislocations, disinclinaisons, domaines focaux, joints de flexions et de torsions). Nous pensons que ces défauts sont une étape vers la transition HQ. Le modèle de structure de la phase à cylindres flexibles que nous proposons est discuté et comparé aux modèles proposés par d'autres auteurs. La nature de la fracture et les transitions de phases sont également discutées

Les mécanismes contrôlant l'extraction d'ions par flottation ionique à l'aide de tensioactifs ioniques à longue chaîne sont décrits à travers l'étude de la récupération du baryum par le laurylsulfate de NA. Mise au point d'un modèle, appliqué à la récupération du zirconium dans les solutions acides de nitrate d'uranyle

Ce travail concerne l'etude de l'interface entre l'air et une solution aqueuse contenant a la fois des chaines d'un polymere neutre thermosensible qui precipite au-dela de tc 32 \c, le poly(n-isopropylacrylamide) (pnipam), et des molecules tensioactives de dodecyl sulfate de sodium (sds). Separement, ces deux especes s'adsorbent de maniere forte et spontanee aux interfaces hydrophile/hydrophobe. De plus, en volume, a partir d'une concentration critique en sds appelee cac, elles interagissent entre elles pour former des complexes polymere-tensioactif. Grace a la reflectivite des neutrons, les differentes structures adoptees par ce systeme mixte a l'interface air-solution en fonction de la temperature et de la concentration en sds ont ete mises en evidence. En particulier, il a ete montre que pour le polymere seul et a des concentrations en sds inferieures a la cac, la densite d'adsorption du polymere augmente fortement avec la temperature et n'est pas affectee par la presence de tensioactifs. Au-dela de la cac, l'adsorption du polymere diminue avec la concentration en sds. Cette desorption progressive du polymere est due a l'interaction en volume entre le pnipam et le sds. Dans le cadre general de la comprehension de la stabilite des mousses, des films minces de mousses formes a partir de solutions aqueuses de pnipam avec et sans sds ont ete etudies par la technique de thin film balance. Les resultats montrent que, sous certaines conditions, il est possible de former des films metastables de tres grande epaisseur et remarquablement homogenes a partir de solutions de pnipam. Ces films sont stabilises par les interactions repulsives entre queues de polymere adsorbees sur les interfaces du film. L'addition de sds entraine un diminution importante de l'epaisseur des films. Dans tous les cas, avec et sans tensioactifs, il existe une correlation directe entre l'epaisseur des films de mousse et la quantite de pnipam adsorbee a l'interface libre.

Nous avons synthetise et caracterise plusieurs series de carboxylates binucleaires de ruthenium a valence mixte de formule generale ru#2(rco#2)#4x, ou x=cl, rco#2, dodecylsulfate et r=ch#3(ch#2)#n, (c#nh#2#n#+#1o)#mph. Une serie de carboxylates de ruthenium divalent de formule ru#2(rco#2)#4 a chaine aliphatique lineaire a aussi ete synthetisee et etudiee. Les proprietes mesomorphes de ces produits ont ete etudiees par microscopie optique en lumiere polarisee, calorimetrie differentielle a balayage et diffraction de rayons x de poudre. Les carboxylates divalents presentent une mesophase colonnaire hexagonale ordonnee, tres similaire a celle qui avait ete obtenue pour les carboxylates de cuivre et de rhodium. Le mesomorphisme des carboxylates de ruthenium a valence mixte s'est revele fortement dependant de la nature de l'anion et du type de carboxylate. Le parametre clef dans l'apparition de mesophases est le remplissage efficace de l'espace, obtenu par utilisation d'anions a longue chaine ou de carboxylates equatoriaux encombrants. Un modele structural pour la mesophase colonnaire hexagonale des pentacarboxylates est propose. Les etudes spectroscopiques (infrarouge, raman) montrent que la vibration ru-ru est peu sensible a la nature des produits etudies. De plus, sa frequence reste pratiquement inchangee lors de la transition vers la phase cristal liquide. Le comportement magnetique des carboxylates de ruthenium a valence mixte est caracterise par un etat paramagnetique avec un fort ecart en champ nul. La presence d'interactions intermoleculaires depend de la nature de l'anion, ainsi que de certains parametres structuraux. Aucun changement de structure electronique n'a ete detecte pour les pentacarboxylates lors de la transition vers la mesophase, contrairement a la situation trouvee dans les carboxylates divalents. L'intercalation de pyrazine introduit des interactions intermoleculaires antiferromagnetiques dans les carboxylates a valence mixte, et conduit a la modification des proprietes spectroscopiques ainsi qu'a la perte du caractere mesogene des carboxylates divalents

Etude de la reduction electrochimique de l'acetophenone, l'oxyde de mesityle et l'ethylideneacetone en milieu aqueux en presence d'agents de surface anioniques (laurylsulfate de sodium), d'agents de surface cationiques (bromure de benzyltrimethylammonium et bromure de cetyltrimethylammonium) et d'agents de surface non ioniques (brij 35 et poly(oxyethylene))

abstract: Gas diffusion layers (GDLs) are a critical and essential part of proton exchange membrane fuel cells (PEMFCs). They carry out various important functions such as transportation of reactants to and from the reaction sites. The material properties and structural characteristics of the substrate and the microporous layer strongly influence fuel cell performance. The microporous layer of the GDLs was fabricated with the carbon slurry dispersed in water containing ammonium lauryl sulfate (ALS) using the wire rod coating method. GDLs were fabricated with different materials to compose the microporous layer and evaluated the effects on PEMFC power output performance. The consistency of the carbon slurry was achieved by adding 25 wt. % of PTFE, a binding agent with a 75:25 ratio of carbon (Pureblack and vapor grown carbon fiber). The GDLs were investigated in PEMFC under various relative humidity (RH) conditions using H2/O2 and H2/Air. GDLs were also fabricated with the carbon slurry dispersed in water containing sodium dodecyl sulfate (SDS) and multiwalled carbon nanotubes (MWCNTs) with isopropyl alcohol (IPA) based for fuel cell performance comparison. MWCNTs and SDS exhibits the highest performance at 60% and 70% RH with a peak power density of 1100 mW.cm-2 and 850 mW.cm-2 using air and oxygen as an oxidant. This means that the gas diffusion characteristics of these two samples were optimum at 60 and 70 % RH with high limiting current density range. It was also found that the composition of the carbon slurry, specifically ALS concentration has the highest peak power density of 1300 and 500mW.cm-2 for both H2/O2 and H2/Air at 100% RH. However, SDS and MWCNTs demonstrates the lowest power density using air and oxygen as an oxidants at 100% RH.
Dissertation/Thesis
M.S. Engineering 2012

The utilization of in vitro tests with a tiered testing strategy for detection of mild ocular irritants can reduce the use of animals for testing, provide mechanistic data on toxic effects, and reduce the uncertainty associated with dose selection for clinical trials. The first section of this thesis describes how in vitro methods can be used to improve the prediction of the toxicity of chemicals and ophthalmic products. The proper utilization of in vitro methods can accurately predict toxic threshold levels and reduce animal use in product development. Sections two, three and four describe the development of new sensitive in vitro methods for predicting ocular toxicity. Maintaining the barrier function of the cornea is critical for the prevention of the penetration of infections microorganisms and irritating chemicals into the eye. Chapter 2 describes the development of a method for assessing the effects of chemicals on tight junctions using a human corneal epithelial and canine kidney epithelial cell line. In Chapter 3 a method that uses a primary organ culture for assessing single instillation and multiple instillation toxic effects is described. The ScanTox system was shown to be an ideal system to monitor the toxic effects over time as multiple readings can be taken of treated bovine lenses using the nondestructive method of assessing for the lens optical quality. Confirmations of toxic effects were made with the utilization of the viability dye alamarBlue. Chapter 4 describes the development of sensitive in vitro assays for detecting ocular toxicity by measuring the effects of chemicals on the mitochondrial integrity of bovine cornea, bovine lens epithelium and corneal epithelial cells, using fluorescent dyes. The goal of this research was to develop an in vitro test battery that can be used to accurately predict the ocular toxicity of new chemicals and ophthalmic formulations. By comparing the toxicity seen in vivo animals and humans with the toxicity response in these new in vitro methods, it was demonstrated that these in vitro methods can be utilized in a tiered testing strategy in the development of new chemicals and ophthalmic formulations.