Banca de DEFESA: LEONARDO BRITO GUIMARÃES

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : LEONARDO BRITO GUIMARÃES
DATE: 28/03/2024
TIME: 13:30
LOCAL: Remoto - RNP
TITLE:

DEVELOPMENT OF A ANALYTICAL METHOD BASED ON EXTRACTION INDUCED BY EMULSION BREAKING FOR MULTIELEMENTAL DETERMINATION IN LUBRICANT OIL BY OPTICAL EMISSION SPECTROMETRY WITH MICROWAVE INDUCED PLASMA (MIP OES)

KEY WORDS:

EIEB; MIP OES; lubricating oil; tribology

PAGES: 129
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Analítica
SPECIALTY: Métodos Óticos de Análise
SUMMARY:

The determination of trace chemical elements in lubricating oil contained in engine compartments is a relevant area of tribology and, it is an indication of wear, oxidation of mechanical components and the quality of additives used for better engine performance. The complexity of the lubricating oil matrix is the subject of study for the search for less aggressive and interference-free strategies for sample preparation, such as extraction induced by emulsion breaking (EIEB) which has stood out in the last decade for oils and fats. This work aimed to develop an analytical procedure from extraction induced by emulsion breaking (EIEB) for multielement determination in lubricating oil samples by microwave-induced plasma optical emission spectrometry (MIP OES), foregoing high-cost mechanical devices. The time required for cleavage and extraction of the analytes was evaluated, achieving global sensitivity in 40 minutes. The Doehlert Matrix response surface methodology was used to study the effects and interactions between the concentration of nitric acid and surfactant in EIEB, obtaining the optimum conditions for 3.0 g of sample: 2.80 mol L^-1 of nitric acid and 3.0 % (m/v) of the surfactant Triton X-114. The plasma condition and interferences of the extract introduced into the N₂ plasma were evaluated by monitoring molecular species (CN, CH and C2), atomic and ionic emission lines of the analytes to select the most sensitive and interference-free one and the flow rate of the nebulizer gas (0.3 – 0.8 L min^-1) for each analyte in the matrix. The limits of quantification of the developed method obtained for Al, Cr, Cu, Fe, Mg, Mn, Mo, Ni and Pb were 2.9, 43, 4.0, 17, 4.0, 3.7, 7.0, 9.2 and 45 µg kg^-1, respectively. The accuracy of the method was assessed using the addition and recovery test for three different samples and by comparing the EIEB with another established method, with the percentage of recovery and agreement varying between 84 and 120%. The method developed based on EIEB showed multielement capacity with precision and accuracy, and was therefore explored in other lubricating oil samples for the determination of trace elements with the following concentration ranges (mg kg^-1): 2.49 – 106, 1.78 – 24.8, 0.25 – 21.6, 16.4 – 378, 7.78 – 76.5, 0.33 – 9.65, 4.65 – 43.2, 1.58 – 11.1 and 4.6 – 12.6 for Al, Cr, Cu, Fe, Mg, Mn, Mo, Ni and Pb respectively. The principal component analysis and the self-organization map of Kohonen were effective for exploratory analysis to correlate the concentrations of trace elements with the samples of lubricating,

COMMITTEE MEMBERS:
Interno - 1551430 - FABIO DE SOUZA DIAS
Interna - 2721446 - DANIELE CRISTINA MUNIZ BATISTA DOS SANTOS
Interna - 3354459 - LICIA PASSOS DOS SANTOS CRUZ
Interno - 1698441 - RENNAN GEOVANNY OLIVEIRA ARAUJO
Interno - 1649202 - LEONARDO SENA GOMES TEIXEIRA
Externo ao Programa - ***.749.625-** - ERIK GALVÃO PARANHOS DA SILVA - UESC-BA
Externo à Instituição - MARIANELA SAVIO