Overcoming Permanganate Stalling during Electromigration

Electrokinetic experiments were undertaken to transport permanganate (MnO4-) through a low permeability porous media. The experiments employed a one-dimensional apparatus in which MnO4- was electromigrated through a central porous media core. Two outer porous media cores separated the electrode reservoirs from the inner permanganate source and permanganate target reservoirs. By utilizing a pH-isolation technique, whereby electrolysis reactions occurring at electrodes were isolated, uniform and repeatable MnO4- electromigration was achieved. This result was compared with non-pH-isolated experiments (normal mode), which resulted in a stalled MnO4- electromigration front. The research also investigated potential stalling mechanisms, including voltage gradient nonlinearity through the central porous media core and the reduction of MnO4- to Mn2+. It was observed that the voltage gradient decreased as a result of MnO4- stalling; however, it was not considered a stalling mechanism. Results from Mn2+ analysis determined that the Mn2+ distribution for normal modde experiments extended partially beyond the extent of MnO4- electromigration; however, competing ions interfered with the analysis and definitive conclusions could not be made. pH-isolated experiments described in this research provide a simple method for implementing electrokinetic in situ chemical oxidation as a groundwater remediation technique where low permeability porous media exists. DOI: 10.1061/(ASCE)EE.1943-7870.0000660. (C) 2013 American Society of Civil Engineers.