Effect of current density on electrolytic transformation of benzene for groundwater remediation

Electrolytic transformation of benzene in water is evaluated as a potential mechanism that can be implemented for in situ remediation of benzene in groundwater. Electrolytic transformation experiments were conducted using inert electrodes that are separated by a membrane. Electrolytes that consist of sodium chloride or sodium nitrate solutions with 40 mg/L benzene concentration were used. Electric currents of 1, 5 and 10 mA (1.8, 9.0 and 18.1 mA/L, respectively) were applied and the transformation of benzene was monitored and compared with a control. The results show that electrolytic transformation of benzene occurred under different rates that depend upon the type of electrolyte and the current density. Transformation results in formation of chlorinated benzene when sodium chloride is the electrolyte. However, processing for long enough time (up to 300 h) resulted in transformation of the chlorinated benzene byproducts. Benzene transformation occurred when the electrolyte was sodium nitrate but the rate was slower than the case with sodium chloride. The results did no show formation of byproducts in this case. The transformation rate was dependent on the current density. The results with sodium chloride showed that the rate increases with increasing the current density, but there is an optimum value, beyond which increasing the current density will not increase the transformation rate.