Novas abordagens em petroleômica: extração e caracterização de ácidos naftênicos de águas produzidas por espectrometria de massas de ultra-alta resolução
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2020-02-12
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Universidade Federal de Goiás
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Oil production is accompanied by water production, called produced water (PW), which is abundant in reservoirs. By being in contact with oil and in high-pressure environments, some components of oil, by equilibrium, can be transferred to water, such as naphthenic acids (NAs). NAs are associated with corrosion problems, scale formation and deposits, and high toxicity to aquatic biota. Here, we propose the use of solvent-terminated dispersive liquid-liquid microextraction (ST-DLLME) coupled with high-resolution mass spectrometry (UHR MS) in order to extract and detect PW dispersed and dissolved NAs, as well as to analyze the distribution of NAs in the oil/water balance. At first, the optimization of solvents to be used and the influence of the pH of sample AP 1 on the extraction of dispersed NAs were performed. Seven solvent systems (dispersing solvent + extracting solvent + demulsifying solvent) were used at pHs 2, 7, and 10. For analysis of dissolved NAs, sample PW 1 was subjected to a n-hexane clean-up step for removal of dispersed oil droplets. Extractions of the dispersed NAs showed that at pH 2 the solvent system that obtained the highest percentage of extracted Ox class was 7 (DCM / CH / Ace). At pH 7 and 10 in the solvent system 2 (CH / Tol / Ace) compounds above C30 were detected and a double bond equivalent (DBE) variation was found between 1 and 11. After clean-up with n-hexane a decrease of the detected carbon number range as well as the DBE range was found. The distribution of NAs in oil/water allowed for the analysis of which NAs are most likely to be transferred to water produced in both dispersed and dissolved form. In addition, ST-DLLME and miniaturized liquid-liquid extraction (LLE) were employed as extraction methodologies for samples AP 2, AP 3 and AP 4, in which it was observed that ST-DLLME reached carbon number values and DBE value higher than miniaturized LLE. In summary, ST-DLLME coupled with UHR MS can be a valuable analytical tool for the extraction of naphthenic acids in produced waters, since the use of this extraction technique minimizes the consumption of samples and solvents.
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AGUIAR, Deborah Victória Alves de. Novas abordagens em petroleômica: extração e caracterização de ácidos naftênicos de águas produzidas por espectrometria de massas de ultra-alta resolução. 2020. 76 f. Dissertação (Mestrado em Química) - Universidade Federal de Goiás, Goiânia, 2020.