masterThesis
Estudo da eficácia do tensoativo sorbitano tween 80 veiculado em nanoemulsão contendo óleo de soja, como inibidor de corrosão
Fecha
2012-08-30Registro en:
RODRIGUES, Ciro José Ferreira. Estudo da eficácia do tensoativo sorbitano tween 80 veiculado em nanoemulsão contendo óleo de soja, como inibidor de corrosão. 2012. 109 f. Dissertação (Mestrado em Físico-Química; Química) - Universidade Federal do Rio Grande do Norte, Natal, 2012.
Autor
Rodrigues, Ciro José Ferreira
Resumen
Nowadays, the use of chemicals that satisfactorily meet the needs of
different sectors of the chemical industry is linked to the consumption of
biodegradable materials. In this context, this work contemplated
biotechnological aspects with the objective of developing a more
environmentally-friendly corrosion inhibitor. In order to achieve this goal,
nanoemulsion-type systems (NE) were obtained by varying the amount of
Tween 80 (9 to 85 ppm) a sortitan surfactant named polyoxyethylene (20)
monooleate. This NE-system was analyzed using phase diagrams in which the
percentage of the oil phase (commercial soybean oil, codenamed as OS) was
kept constant. By changing the amount of Tween 80, several polar NE-OS
derived systems (O/W-type nanoemulsion) were obtained and characterized
through light scattering, conductivity and pH, and further subjected to
electrochemical studies. The interfacial behavior of these NE-OS derived
systems (codenamed NE-OS1, S2, S3, S4 and S5) as corrosion inhibitors on
carbon steel AISI 1020 in saline media (NaCl 3.5%) were evaluated by
measurement of Open Circuit Potential (OCP), Polarization Curves (Tafel
extrapolation method) and Electrochemical Impedance Spectroscopy (EIS). The
analyzed NE-OS1 and NE-OS2 systems were found to be mixed inhibitors with
quantitative efficacy (98.6% - 99.7%) for concentrations of Tween 80 ranging
between 9 and 85 ppm. According to the EIS technique, maximum corrosion
efficiency was observed for some tested NE-OS samples. Additionaly to the
electrochemical studies, Analysis of Variance (ANOVA) and Principal
Component Analysis (PCA) were used, characterization of the nanoemulsion
tested systems and adsorption studies, respectively, which confirmed the
results observed in the experimental analyses using diluted NE-OS samples in
lower concentrations of Tween 80 (0.5 1.75 ppm)