Electrochemical activation of graphite electrode for nitrate reduction: Energetic performance and application potential

Electrocatalysis is a potential technology to remove nitrate from wastewater. However, developing an efficient electrode with long-term stability is still a great challenge. Herein, we reported a facile electrochemical activation method to improve nitrate reduction ability of graphite electrodes. Results of cyclic voltammetry and electrochemical impedance spectroscopy showed that the nitrate reduction activity was enhanced and the solid-liquid interfacial resistance was decreased. The activated electrode displayed nitrate reduction rate of 0.0409 min−1, which was 10.8 times that of pristine graphite and closed to Fe and Cu electrodes. Furthermore, taking solution including 50.0 mg/L nitrate-N as target, the activated electrode performed above 90.0 % of nitrate removal during 81 days of continuous running. When activated graphite electrode was enlarged to 2500.0 cm2, its performance in nitrate reduction was maintained well. These results suggested electrochemical activated graphite electrode was a promising alternative in the real application of nitrate removal from water and wastewater.