Banca de DEFESA: GEICY KELLY PIRES BARBOZA BADARÓ

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : GEICY KELLY PIRES BARBOZA BADARÓ
DATE: 25/10/2022
TIME: 09:00
LOCAL: Defesa em condição Remota
TITLE:

Extract of Justicia brandegeeana as eco-friendly corrosion inhibitor of carbon steel AISI 1020 in sulfuric acid.

KEY WORDS:

Justicia brandegeeana, red shrimp, corrosion inhibitor, eco-friendly, chelating effect, carbon steel.

PAGES: 77
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Orgânica
SPECIALTY: Química dos Produtos Naturais
SUMMARY:

The search for new organic eco-friendly corrosion inhibitors is increasingly necessary, given the high cost caused by corrosion and the existence of highly contaminant conventional inhibitors. Thus, in this dissertation was investigated the anticorrosive effect of the extract in ethanol of the aerial parts of the species Justicia brandegeeana (Acanthaceae), popularly known as red shrimp for carbon steel AISI 1020 in acid medium. Two samples were collected, the first in June 2021 and the second in October 2021 with high moisture content (70% and 69%, respectively) and low yields (4% and 3%, respectively). The extracts of both were analyzed by infrared, where it was noted that seasonality interfered only in the intensity of the bands, preserving the nature of the extracted classes of substances. Polar groups were identified, with the ability to present good corrosion inhibition, such as alcohols, carbonylas of carboxylic esters, and 1H and 13C NMR allowed the identification of the carbohydrate class. For all techniques the concentration of the extract varied in 250, 450, 750, 1000 and 1500 ppm. The electrochemical techniques of electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PP) and linear polarization resistance (LPR) were performed in an OCP of 5400 s and were consistent with each other, showing good corrosion inhibition efficiency for all concentrations studied, also showing that the inhibition efficiency is dependent on the inhibitor concentration. The PP curves also allowed to analyze that the extract is characterized as a mixed inhibitor, with a tendency to the cathodic region. Gravimetric analysis of mass loss allowed an evaluation in greater immersion times of carbon steel in the corrosive medium, which are: 3, 6, 24 and 48 hours. The results showed good corrosion inhibition efficiency for all concentrations evaluated, being more expressive at 1500 ppm with 94% inhibition at 6 h of immersion. All concentrations obtained their maximum efficiency at 6 h, stabilizing at 24 h, with decay at 48 h of immersion. When evaluating the effect of temperature variation, the extract showed good thermal stability, with 82% inhibition at 70 ºC, indicating a physisorption, and the efficiency was corroborated by the physicochemical parameters of Ea, ΔH ǂ e ΔS ǂ . The chelating activity of the extract in ethanol was also investigated against Fe+2 ions, and the extract showed 52% chelating effect, being thus in line with the results obtained by the techniques of evaluation of anticorrosive activity. In addition, the images of the morphology of the metallic surface, generated by scanning electron microscopy (SEM) indicated a surface protection with the presence of the plant extract, thus minimizing the roughness. These results make it possible to consider the ethanol extract of Justicida brandegeeana as an eco-friendly agent efficient in preventing corrosion of carbon steel AISI 1020 in H2SO4 1,0 mol L-1 medium.

COMMITTEE MEMBERS:
Presidente - 387189 - AUREA ECHEVARRIA AZNAR NEVES LIMA
Interno - 1221906 - LUCIANO RAMOS SUZART
Externa à Instituição - JANAINA CARDOZO DA ROCHA