Electromagnetic Stimulation of Two-Phase Transport in Water for Geoenvironmental Applications

Air sparging is a popular remediation technology for contaminated soils. However, the application is not efficient due to the limitations of airflow that result from the formation of random preferential air channels. Controlling the formation of these air channels and enhancing diffusion surrounding them can considerably improve the effectiveness of air sparging. This work is a study on how electromagnetic (EM) waves—without a measureable increase in temperature—enhance the transport of a nonreactive dye in water as a visible analogy of air sparging (i.e., airflow within groundwater). This paper explains the details of the experimental setup and procedures required to conduct the EM-stimulation experiment as well as electric-field mapping and digital imaging of dye transport for the purpose of digital visual analysis. Several antenna designs and the way they direct the transport mechanism are studied. The results of EM-stimulation tests with no measureable temperature increase show that EM waves enhance and direct the dye transport in accordance with the EM source (transmitting antenna) and its radiation pattern. The rate of transport of the dye is studied and compared for unstimulated and EM-stimulated tests. Because of the small size of the dye molecules and existence of an alternating electric field, dielectrophoresis is the most likely potential transport mechanism. However, the existence of other competing factors dominating dielectrophoresis interferes with this type of study. Future modifications in the experimental design seem to have the potential to improve the investigation of the transport phenomenon