Electrochemical characterization of an oil/water alternately wetted rotating cylinder electrode

To characterize the corrosion at oil/water interfaces, a vertically adjustable rotating cylinder electrode (VA-RCE) was developed based on the concept of “alternate wetting cell”, in which the electrochemical current reflecting the wet state of the RCE surface can be continuously monitored. Under a sinusoidal moving mode, the current waveform varied with the rotation rate and the longitudinal displacement speed or amplitude of the VA-RCE, implying that the dynamic wetting behavior of the VA-RCE surface in the oil/water interface region was influenced by the flow conditions; the replacement of oil phase by water phase became easier with increasing flow rate and alternating frequency of change between water wet and oil wet. The results also indicated that the wettability of the VA-RCE surface could be modified by the formation of corrosion products. All the results suggested that the VA-RCE could be used to quantitatively characterize the dynamic water/oil wetting state and the corrosion at an oil/water interface in a multiphase flow.