Three different macromolecular structures of poly(ethylene oxide-b-propylene oxide) copolymers, used in formulations of commercial demulsifiers for breaking water-in-crude oil emulsions, were investigated. The interfacial activity (), the lower interfacial tension (m), the critical micelle concentration (CMC), the interfacial concentration (Γ) and the molecular area (A) adsorbed at the interface of the surfactant solutions were evaluated. These results were correlated to surfactant performance in coalescing three different asphaltene model emulsions. The PEO-b-PPO commercial demulsifiers, that were capable to dewater asphaltene model emulsions, exhibited interfacial activity to the oil-water interface, reduced the interfacial tension to low values, reached the CMC at low concentration and presented low molecular area adsorbed at the interface.
[1] Schramm L.: Petroleum emulsion: Basic principles [in:] Schramm, L. L (ed.), Emulsions: fundamentals and applications in the petroleum industry. American Chemical Society, Washington, D. C. 1992, 1-49.
[2] McLean J. Spiecker P., Sullivan A. and Kilpatrick P.: The role of petroleum asphaltenes in the stabilization of water-in-oil emulsion [in:] Sheu E. and Mullins O. (eds.), Structure of asphaltenes. Plenum Press, New York 1998, 377-422.
[3] Taylor S.: Chem. & Ind., 1992, 20, 770.
[4] Xu Y., Wu J., Dabros T. and Hamza H.: Energy & Fuel, 2009, 19, 916.
[5] Kim Y., Wasan D. and Breen P.: Colloid Surf. A: Physicochem. Eng. Asp., 1995, 95, 235.
[6] Kim Y. and Wasan D.: Ind. Eng. Chem. Res., 1996, 35, 1141.
[7] Ese M.-E., Galet L., Causse D. and Sjoblom J.: J. Colloid Interface Sci., 1999, 220, 293.
[8] Djuve J., Yang X., Fjellanger I. J. and Sjoblom J.: Colloid Polym. Sci., 2001, 279, 232.
[9] Sun T., Zhang L., Wang Y. et al.: J. Colloid Interface Sci., 2002, 255, 241.
[10] Zhang Z., Xu G.Y., Wang F. et al..: J. Colloid Interface Sci., 2004, 277, 464.
[11] Zhang Z., Xu G., Wang F. et al.: J. Colloid Interface Sci., 2005, 282, 1.
[12] Standard test method for determination of asphaltenes (heptane insolubles) in crude petroleum and petroleum products, Institute of petroleum, IP 143/01, London 2001.
[13] Paulis J. and Sharma M.: Society of Petrol. Eng., 1997, SPE 37269.