Banca de DEFESA: DENISE PORFIRIO EMERENCIANO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : DENISE PORFIRIO EMERENCIANO
DATA : 19/04/2017
HORA: 14:00
LOCAL: auditório do NUPPRAR
TÍTULO:

PREPARATION AND CHARACTERIZATION OF NEW COLLOIDAL SYSTEMS FROM THE VEGETABLE OILS SPECIMENS Azadirachta indica AND Copaifera FOR CORROSION INHIBITOR APPLICATIONS IN SALINE MEDIUM

PALAVRAS-CHAVES:

Azadirachta indica A. Juss., Copaifera L., Microemulsion system, Green corrosion inhibitors, Antioxidant property, Electrochemical techniques of linear polarization resistance and impedance; Colloidal bioproducts and pharmacological applications

PÁGINAS: 161
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Química Analítica
ESPECIALIDADE: Eletroanalítica
RESUMO:

The corrosion inhibition efficiency of colloidal systems based on vegetable oils such as Azadirachta indica A. Juss (SMEOAI) and Copaifera L. (SMECO) were evaluated by electrochemical techniques. The colloidal formulations SMEOAI and SMECO were analyzed in different concentrations (5 ppm - 150 ppm) in the corrosion of AISI 1018 steel in corrosive saline medium (3.5% NaCl solution). The hydroalcoholic extract obtained from the leaves of A. indica (EAI) was loaded in the colloidal system SMEOAI and then applied as a green corrosion inhibitor. The SMEOAI system was prepared by using Tween® 80 as surfactant, A. indica oil (OAI) as the oil phase and bidistilled water (as a neutral aqueous phase). The SMEOAI system satisfactorily loaded the EAI extract providing a derivative formulation so called SMEOAI-EAI. Similarly, the SMECO system was prepared by using Tween® 80, copaiba oil (CO), and bidistilled water. The formation of Winsor IV microemulsion region (WIV) on both systems (SMEOAI and SMECO) was evidenced through the construction of the ternary phase diagrams. The colloidal systems characterizations were performed by using the following analyzes, determination of the refractive index, rheological behavior, surface tension and droplet diameter. The formulations SMEOAI and SMECO were analyzed by electrochemical techniques of linear polarization resistance (LPR) and impedance spectroscopy (EIS) and for the SMECO system it was only used LPR method. Comparatively, the SMECO system (100 ppm) showed the lowest corrosion inhibition efficiency (77.15%), followed by SMEOAI (25 ppm) which showed median inhibition (79.28%) and the maximum inhibition efficiency (91.79%) was found to the SMEOAI-EAI (50 ppm) system.  For all of those inhibitors systems the antioxidant effect was analyzed by using in vitro experiments. For that, it was evaluated by the analysis of total antioxidant capacity, 18.74% (SMEOAI) and 36.14% (SMEOAI-EAI); reducing power, 56.34% (SMEOAI) and 290.49% (SMEOAI-EAI); iron ion chelation, 58.97% (SMEOAI) and 51.29% (SMEOAI-EAI); sequestration of hydroxyl radicals, 60.16% (SMEOAI) and 87.33% (SMEOAI-EAI). The percentage divergences observed for the inhibitors formulations are related to the different antioxidative mechanisms of each applied model, as well as the presence of the A. indica extract (EAI) in the SMEOAI-EAI system. Comparatively, the higher antioxidant effect was observed for the formulation SMEOAI-EAI. Meanwhile, the lower effect was evidenced to the copaiba oil colloidal system which showed 47.89% in the analysis of reducing power and 72.92% for sequestration of hydroxyl radicals. The green corrosion inhibitors SMEOAI, SMEOAI-EAI and SMECO are biodegradable and due to the wide use of these plants, may arouse the interest of the industrial sector focusing some different possible applications such as, bio-insecticides, biological drug carriers, waste water purifiers, effluents, oil recovery agents, among other applications.

Meanwhile

MEMBROS DA BANCA:
Presidente - 373.201.654-49 - MARIA APARECIDA MEDEIROS MACIEL - UnP
Interno - 1803692 - FABRICIO GAVA MENEZES
Externo ao Programa - 2195251 - HUGO ALEXANDRE DE OLIVEIRA ROCHA
Externo ao Programa - 347057 - TEREZA NEUMA DE CASTRO DANTAS
Externo à Instituição - FRANCISCO HUMBERTO XAVIER JUNIOR - UFPE
Externo à Instituição - JOSEALDO TONHOLO - UFAL