(85d) Removal of Asphaltene from Crude Oil through Electrodeposition Method

The deposition of asphaltene on interior pipe surfaces is considered a challenging flow assurance issue. To prevent this, chemical dispersants are often added, which increases transportation costs and introduces environmental concerns. By exploiting the net charge of the asphaltene molecule, they can be effectively removed from the flow stream by means of electrodeposition before transportation to prevent later deposition. To evaluate this concept, electrodeposition of asphaltene from a synthetic oil using varying electric field strength and solvent type were studied. Both native charge (positive) and induced charge (negative) of asphaltene were observed in this study, and the inducement of charge was realized with higher current density. Asphaltene solubility in the synthetic oil was increased by increasing the polar/non-polar solvent ratio revealing a higher conductivity of the synthetic oil. As a result, the synthetic oil with higher polar solvent content provided higher current density resulting in deposition onto the anode, inferring an induced negative charge of the asphaltene. In addition to electric field strength and synthetic oil composition, the asphaltene concentration and synthetic oil viscosity affected the electro-deposition. The process was also employed in multiple cycles with continuous asphaltene deposition; the recovery rate was over 90 wt.% in the first three cycles and the deposition gradually decreased as the deposited asphaltene appeared to diminish the electric field strength.