Electrochemical Reduction of High-Concentrated Nitrate Using Ti/TiO2 Nanotube Array Anode and Fe Cathode in Dual-Chamber Cell

Abstract

Electrochemical reduction of nitrate using Fe cathode and Ti/TiO2 nanotube array anode in dual-chamber cell was investigated. The performance of different cathodes for nitrate removal were in the order of Fe>Al>Cu>Ni. The nitrate removal in dual-chamber cell (99.8%) was much higher than that in single-chamber cell (84.3%) with Fe cathode in 2.5 h. In dual-chamber cell, the highest nitrate removal was obtained at the current density of 15 mA/cm2. The nitrate reduction followed first-order kinetics. With increasing initial nitrate concentration, the reduction rate constant slightly decreased from 2.2 h−1 (100.0 mg/L) to 0.9 h−1 (1000.0 mg/L), of which a remarkable nitrate removal of 88.3% could still be achieved with 1000.0 mg/L nitrate. In the presence of 0.5 g/L NaCl, simultaneous reduction of nitrate and oxidation of by-products of ammonia and nitrite were achieved in dual-chamber cell with Fe cathode, of which the nitrate removal rate was 94.3% and no by-products were detected in the solution.