Molecular mobility of crude oils via electron paramagnetic resonance of organic free radicals

• Autor(a) principal: Alamzeb Khan
• Data de Publicação: 2019
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UEL
• Texto Completo: http://www.bibliotecadigital.uel.br/document/?code=vtls000231093

t: Electron Paramagnetic Resonance (EPR) spectroscopy technique was applied to investigate the molecular mobility properties in different Pakistani origin crude oil samples. All the samples used in the present study, were of paraffinic and aromatic in nature. EPR experiments at X-band with variation in temperature (298-553K) were performed to predict the molecular mobility in both crude oil samples, by analysing the line-width of the organic free radical signal. The viscosity of the samples was measured by using MCR Serie 301 Rheometer, inorder to study the mobility of the oil samples. A change in the values of the viscosities has been observed, due to the different nature and composition of the oils. The line-width studies in the EPR spectrum of the organic free radical exhibited significant changes with the variations in temperature condition, which is an important parameter to detect changes in molecular mobility of the samples, leading us to determine the different regimes of the mobility of the oils at the different temperatures. The linewidths of the crude oil samples were also affected by temperature, although g-value was constant, revealing the changing in the chemical structure and the surrounding environment of free radicals during the studies. The concentrations of the free radical follow the trends in the whole temperature range, first increasing and then decreasing. This may be attributed to the competing mechanism of the generations and decomposition of the free radicals. The present study proposes a new method to predict molecular mobility of oils by EPR of free radicals.