Electrochemical degradation of methyl tert-butyl ether (MTBE) using alternating and direct currents

Electrochemical degradation of methyl tert-butyl ether (MTBE) was investigated to evaluate the effect of current type and density, electrode material, deionized (DI) water and tap water as electrolytes and initial concentration of MTBE. MTBE is an organic compound, which is highly soluble in water and is common ground water (GW) contaminant that is typically released to the GW from gasoline spills. MTBE dissolved in DI water at initial concentrations equal to 25, 250 and 2,500 mg/L was subjected to alternating and direct currents (AC and DC) at current density ranging from 0.5 to 2 mA/cm2. The volume of the electrochemical cell was 1 L and titanium, graphite, and boron doped diamond electrodes were tested. Sodium sulfate (Na2SO 4) was used as the supporting electrolyte during tests at a concentration of 300 mg/L. The key results are: (1) both AC and DC resulted in electrochemical degradation of MTBE but the rate of degradation for DC was greater than that for AC at an equivalent current density; (2) rate of degradation increased as the current density increased for DC as well as for AC; (3) rate of degradation defined as change in normalized concentration decreased as the initial concentration of MTBE was increased; (4) rate of degradation for the graphite electrode was the least among the three materials tested; and (5) Nernst-Planck equation was able to accurately model the decrease in the MTBE concentration for low initial concentrations. At higher initial concentrations, the model results were not consistent.