The charge alteration of asphaltenes during electro-deposition

Abstract

Electro-deposition (E-D) has been proposed as a promising method for dealing with the asphaltenes deposition issue. An observed alteration of the native, positive asphaltene charge during the process has attracted wide attention since it influences the feasibility and efficiency of this method. To investigate this phenomenon, E-D of various asphaltenes with resins was studied. The results demonstrate that the charge alteration of asphaltenes is the result of net adsorption of negative charges within the fluid onto the asphaltenes under high electric field strength. The minimum electric field strength required to trigger the charge alteration of asphaltenes from coal tar and bitumen were 12000 V/cm and 4500 V/cm, respectively, exhibiting a strong influence of chemical composition of asphaltenes on the charge alteration. Moreover, the adsorption of resins on asphaltenes resulted in the repression of charge alteration behavior that varied with different resins. The resins from bitumen had the highest repression on asphaltenes from bitumen, as 2 g/L-resin can increase the minimum electric field strength required for charge alteration to 12000 V/cm. The results of the work provide an essential guide for the further development of an E-D procedure that could be used for efficient asphaltenes removal.