Interfacial Behavior and Water Solubility of Various Asphaltenes at High Temperature

Colloids and Surfaces A: Physicochemical and Engineering Aspects, Available online 27 September 2013, In Press, Accepted Manuscript
Interfacial Behavior and Water Solubility of Various Asphaltenes at High Temperature
Guangzhe Yua, Kyle Karinshak (a), Jeff H. Harwell (a), Brian P. Grady (a), Andrew Woodside (b), Moniraj Ghosh (c)
a School of Chemical, Biological, and Materials Engineering and Institute for Applied Surfactant Research, University of Oklahoma, Norman, OK 73019
b ConocoPhillips Company, Phillips 66 Research Center, Bartlesville, OK 74003
c Phillips 66 Company, Phillips 66 Research Center, Bartlesville, OK 74004
Abstract
Researchers isolated and tested asphaltenes from six distinct crude oils with respect to their water solubility and interfacial behavior at temperatures as high as 190 °C and 125 °C respectively in (1) water with 18 MΩ*cm resistance, (2) a 8 wt.% NaCl-2 wt.% CaCl2 salt solution, and (3) artificial seawater.
None of the asphaltenes exhibited any water solubility, with the possible exception of very slight solubility in two cases. They observed a higher interfacial activity to be loosely correlated with asphaltene molecular weight as measured by freezing point depression measurements. A lower molecular weight asphaltene had a higher interfacial activity. Results of chemical measurements of the asphaltenes suggest that only hydrogen content may correlate with interfacial activity. The interfacial activity decreased as the hydrogen content increased. The interfacial activity was highest for artificial seawater, and lowest for pure water and brine. Interfacial tensions (IFTs) were also measured from room temperature to 125 °C at a fixed concentration of 5 g/l in toluene for the artificial seawater and pure water. With a couple of exceptions, decreases of IFT with temperature were quite similar for all asphaltenes and smaller than that of the pure water/toluene system.
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