A Real‐Time Electrochemical Impedance Analysis for Water‐In‐Oil Emulsions of Bitumen Diluted with Naphtha

Abstract

In this paper, water-in-oil (W/O) emulsions of bitumen diluted with naphtha were characterized by a novel impedance technique in real time. Nyquist diagrams of electrochemical impedance spectra obtained for different systems present different spectra. For the system of bitumen in naphtha, only one semi-circle is observed, and the resistance (R O ) and capacitor (C O ) are connected in parallel. Impedance measurement shows that the conductivity of bitumen results from the conductive components, asphaltenes. For the system containing W/O emulsions, Nyquist diagram is presented in two semicircles with different diameter, indicating different relaxation times corresponding to bitumen in naphtha and W/O emulsions respectively. The R O and C O are in parallel combina-tion and then connect in series with the resistance (R W/O ) and capacitor (C W/O ) of W/O emulsions. The value of R W/O reduces with the decrease of volume fraction of W/O emulsions, which can be used to characterize the stability of emulsions. At the same time, the impedance spectra analysis plays an important role in the study of demulsification of W/O emulsions by comparing the R W/O after adding demulsifier ethylcellulose (EC).With the increase of EC concentration, the R W/O reduces and eventually disappears due to the decrease of volume fraction of emulsions. Further work needs to be studied to establish the relationship between dielectric constant and volume fraction of emulsions.

Propiedades dieléctricas de asfaltos

“…De acuerdo con Jiang et al [54], la pérdida dieléctrica ε′′ del asfalto es muy pequeña a temperatura ambiente y puede ser negligida. Sin embargo, a altas temperaturas, la conductividad puede aumentar significativamente, lo que podría aumentar notablemente la ε′′ (especialmente a bajas frecuencias).…”