Design and Technical Evaluation of a Conceptual Process for Transferring Solvent Precipitated Asphaltenes into Water Utilising Surfactant Phase Behaviour

Experiments are described which demonstrate that asphaltenes precipitated from a refinery tar using an excess of n-heptane spontaneously partition into a contacting water phase in the presence of an ethoxylated nonionic surfactant by effecting a temperature change. The process appears to be related to the temperature-dependent phase behaviour of the particular surfactant. Hot (ca. 80-90°C) aqueous octa(ethyleneoxy) nonylphenylether (NPE8) and the heptane-diluted tar, were thoroughly and vigorously mixed for a short time and then allowed to stand and cool under quiescent conditions. A distinct oil/water interface rapidly appeared after the mixing had stopped and, at a specific temperature, asphaltene particles were observed to begin to “rain” into the lower aqueous phase, producing an