Caracterização e aplicação de sistemas micelares e microemulsionados como inibidores de corrosão
Corrosion is an important phenomenon that frequently occurs in the oil industry, causing surface ablation, such as it happens on the internal surfaces of oil pipes. This work aims to obtain new systems to reduce this specific problem. The surfactants SDS, CTAB, and UNITOL L90 (in micellar and microe...
Guardado en:
| Autor principal: | |
|---|---|
| Otros Autores: | |
| Formato: | Dissertação |
| Lenguaje: | por |
| Publicado: |
Universidade Federal do Rio Grande do Norte
|
| Materias: | |
| Acceso en línea: | https://repositorio.ufrn.br/jspui/handle/123456789/17629 |
| Etiquetas: |
Agregar Etiqueta
Sin Etiquetas, Sea el primero en etiquetar este registro!
|
| Sumario: | Corrosion is an important phenomenon that frequently occurs in the oil industry,
causing surface ablation, such as it happens on the internal surfaces of oil pipes. This work
aims to obtain new systems to reduce this specific problem. The surfactants SDS, CTAB, and
UNITOL L90 (in micellar and microemulsionated systems) were used as corrosion inhibitors.
The systems were obtained using a C/S ratio of 2, butanol as cosorfactant, kerosene as oil
phase and, as water phase, NaCl solutions of 0.5M with pH = 2, 4, and 7. Microemulsion
regions were found both for direct and inverse micelles. SDS had the higher microemulsion
region and the area was not dependent of pH. The study of micellization of these surfactans in
the liquid-gas interface was carried out via the determination of CMC from surface tension
measurements. Regarding microemulsionated systems, in the case of CTAB, CMC increased
when pH was increased, being constant for SDS and UNITOL L90. Concerning micellar
systems, increase in pH caused decrease and increase in CMC for SDC and CTAB,
respectively. In the case of UNITOL L90, CMC was practically constant, but increased for pH
= 4. The microemulsionated systems presented higher CMC values, except for UNITOL L90
L90. The negative values of free energy of micellization indicated that the process of
adsorption was spontaneous. The results also indicated that, comparing microemulsionated to
systems, adsorption was less spontaneous in the case of SDS and CTAB, while it did not
change for UNITOL L90. SAXS experiments indicated that micelle geometry was spherical,
existing also as halter and flat micelles, resuting in a better inght on the adsorption at the
liquid-solid interface. Efficiency of corrosion inhibition as determined by electrochemical
measurements, from corrosion currents calculated from Tafel extrapolation indicuting heat
showed surfactants to be efficient even at low concentrations. Equilibrium isotherm data were
fitted to the Freundlich model, indicating that surfactant adsorption occurs in the form of
multilayers |
|---|