INTERFACIAL-TENSION BEHAVIOR AND ELECTRON-SPIN-RESONANCE PROPERTIES OF ASPHALTENES DERIVED FROM HEAVY OIL

Asphaltenes extracted from Lloydminster heavy oil (from Saskatchewan, Canada) were separated by sequential elution solvent chromatography (SESC) using ten different organic solvents. The fractions so obtained were dissolved in toluene and then examined for their interfacial tension (1FT) behavior against 0. 1 wt. % sodium hydroxide solution. It was found that only about 40% (by weight) of the original asphaltenes contained species which were capable of lowering IFT against the alkaline solution. Multi-functional phenolic and other polar compounds were considered to be the components most likely responsible for the observed interfacial activity. Electron spin resonance measurements showed that the individual fractions contained varying concentrations of free radicals and VO**2** plus ions. However, no direct correlation between the content of either of these two species and the interfacial tension could be detected.