Use of copper plate electrode and Pd catalyst to the nitrate reduction in an electrochemical dual-chamber cell

Nitrate is a chemical species usually present in water, lakes and rivers and in high concentration can be dangerous to human health. This work investigates the use of palladium-coated alumina pellets and a copper plate electrode in an electrochemical dual-chamber cell (DCC) to treat solutions with high nitrate concentrations. The study evaluates the impact of the Pd catalyst, current density, and pH on the reduction reaction and the formation of nitrite, ammonium, and gaseous compounds. Results indicate that the Pd catalyst significantly affects the product distribution, enhancing the production of gaseous compounds. Moreover, varying current density demonstrated notable effects on nitrate reduction, with 59% reduction at 1.1 mA cm−2 and 64% at 1.5 mA cm−2. Optimal conditions were identified using 2.5% wt. Pd-coated alumina pellets, a current density of 1.5 mA cm−2, and pH between 6.0 and 6.5, achieving a nitrate reduction of 49%, with selectivity of 64% to gaseous compounds, 1% to nitrite, and 35% to ammonium. The novel aspect of this work lies in the innovative reduction cell design utilizing a dual chamber and catalytic pellets, which aims for process scalability.