Halogenated contaminants such as pesticides and disinfection byproducts (DBPs) have been widely detected in surface water and drinking water. Due to their acute and chronic toxicity, treatment of these halogenated compounds is of great importance. Activated carbon (AC) has been widely used for passive treatment of halogenated contaminants in water due to its high affinity and adsorptive capacity. However, the accumulation of contaminants on AC surface will saturate the treatment system and thus require periodic replacement of AC adsorbents, which brings high cost of AC material and maintenance. In this study we introduce a novel, semi-passive activated carbon-based electrochemical system for the destruction of fipronil, a pesticide that is widely reported in surface water in California. The electrode was prepared by coating Micro- and nano-scale activated carbon particles on a piece of highly conductive carbon cloth (25 mm X 75 mm X 1mm) or carbon felt (15 mm X 75 mm X 5mm). Such electrodes demonstrated high conductivity and adsorptive capacity. When placed into a 200 mL chamber containing water with 1 ppm fipronil, both electrodes could adsorb &gt; 90% aqueous fipronil within 2 h. After a voltage of -1.0 V vs. Standard Hydrogen Electrode was applied on AC-coated electrode, &gt; 90% of adsorbed fipronil was removed with chloride as major product in 6 h. Both electrodes maintained steady performance over multiple cycles of electrolysis in water without losing its adsorptive capacity and catalytic activity. These results lay the foundation for an activated carbon-based electrolysis system for treatment of pesticides and other halogenated compounds in surface and drinking water due to the low cost, easy preparation and long lifetime of the electrode.

Electrolytic dedegradation of halogenated contaminants in water using activated carbon-based electrode

251st National Meeting (2016)

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