Surfactants belong to the surface active agents with the ability to reduce surface tension, which is used mainly in detergents and cleaners. The diploma thesis is focused on the determination of surfactants in waste and waste waters. The theoretical part describes the basic properties of surfactants, their distribution, valid legislation in the EU and SR in the field of working with these materials and a variety of analytical methods for the determination of these substances. The conclusion of the thesis is to evaluate the results of measuring the concentration of anionic surfactants, which were determined in samples of waste water and sludge.

Made available in DSpace on 2014-12-17T15:01:58Z (GMT). No. of bitstreams: 1 DamilsonFS_TESE.pdf: 10674685 bytes, checksum: 7f06df7e27225da9012b623997ac7e3b (MD5) Previous issue date: 2014-09-02 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The growing utilization of surfactants in several different areas of industry has led to an increase on the studies involving solutions containing this type of molecules. Due to its amphiphilic nature, its molecule presents one polar part and one nonpolar end, which easily interacts with other molecules, being able to modify the media properties. When the concentration in which its monomers are saturated, the airliquid system interface is reached, causing a decrease in interfacial tension. The surfactants from pure fatty acids containing C8, C12 and C16 carbonic chains were synthesized in an alcoholic media using sodium hydroxide. They were characterized via thermal analysis (DTA and DTG) and via infrared spectroscopy, with the intention of observing their purity. Physical and chemical properties such as superficial tension, critical micelle concentration (c.m.c), surfactant excess on surface and Gibbs free energy of micellization were determined in order to understand the behaviour of these molecules with an aqueous media. Pseudo-ternary phase diagrams were obtained aiming to limit the Windsor equilibria conditions so it could be possible to understand how the surfactants carbonic chain size contributes to the microemulsion region. Solutions with known concentrations were prepared to study how the surfactants can influence the dynamic light scattering spectroscopy (DLS) and how the diffusion coefficient is influenced when the media concentration is altered. The results showed the variation on the chain size of the studied surfactant lipophilic part allows the conception of surfactants with similar interfacial properties, but dependent on the size of the lipophilic part of the surfactant. This variation causes the surfactant to have less tendency of microemulsionate oil in water. Another observed result is that the n-alcanes molecule size promoted a decrease on the microemulsion region on the obtained phase diagrams / O crescente uso de tensoativos nas mais diferentes ?reas da ind?stria tem levado a um aumento nos estudos envolvendo solu??es contendo este tipo de mol?cula. Devido a sua natureza anfif?lica, sua mol?cula apresenta uma parte polar e outra apolar, que facilmente interage com outros tipos de mol?culas, podendo modificar as propriedades do meio. Quando a concentra??o, na qual seus mon?meros saturam, a interface do sistema ar-l?quido, ? atingida promovendo a redu??o da tens?o interfacial. Os tensoativos dos ?cidos graxos puros com cadeias carb?nicas C8, C12 e C16 foram sintetizados em meio alco?lico, utilizando hidr?xido de s?dio. Eles foram caracterizados por an?lise t?rmica (DTA e DTG) e espectroscopia de infravermelho com o objetivo de se observar a pureza dos mesmos. Foram determinadas algumas propriedades f?sicoqu?micas como: tens?o superficial, c.m.c. , excesso de tensoativo na interface e energia livre de Gibbs de miceliza??o a fim de se entender o comportamento das intera??es dessas mol?culas com meio aquoso. Foram elaborados diagramas de fase pseudotern?rios com o intuito de realizar as delimita??es do equil?brio de Winsor para compreender como o tamanho da cadeia carb?nica dos tensoativos contribui com a regi?o de microemuls?o. Preparou-se solu??es com concentra??es conhecidas para se estudar como os tensoativos podem influenciar a espectroscopia de espalhamento din?mico de luz (Dynamic Ligth Scattering - DLS) e como o coeficiente de difus?o ? influenciado quando a concentra??o do meio ? alterada. Os resultados mostraram que o aumento ou diminui??o do tamanho da cadeia da parte lipof?lica dos tensoativos estudados permite conceber tensoativos com propriedades interfaciais similares, mas tamb?m dependente do tamanho da parte lipof?lica do tensoativo. Esta varia??o deixa o tensoativo com menor tend?ncia a microemulsionar ?leo em ?gua. Outro resultado observado ? que o tamanho das mol?culas de n-alcanos promoveu uma redu??o da regi?o de microemuls?o dos diagramas de fases obtidos

The diploma thesis is focused on surfactants as compounds of fire fighting foams. Fire fighting foams have several characteristics including foaming, aquatic toxicity and biodegradability, which cause the environmental impact. This diploma thesis deals with the contamination of the soil by the large amount of the extinguishing water. The experimental part of the diploma thesis describes the determination of surfactants by the mobile analysis and the measurement of the methylene blue index.