Improvement on Electrochemical Reduction of Nitrate in Synthetic Groundwater by Reducing Anode Surface Area

Abstract

In the present study, electrochemical nitrate reduction has been studied to efficiently achieve simultaneous nitrate reduction and by-products oxidation by changing the anode surface area. Cyclic voltammetric (CV) results illustrated that both in the absence and presence of NaCl, the order of cathode ability for nitrate reduction was Cu-Zn > Cu > Fe > Ti. For the paired electrolysis using Cu-Zn and Ti/IrO2-Pt as cathode and anode, nitrate removal was improved when the A/C was decreased from 1.00 to 0.12. In the presence of 1.0 g/L NaCl, nitrate rapidly decreased from 50 to 11.88 mg/L at the A/C of 0.12, and almost no ammonia and nitrite was observed after 2 h electrolysis with the highest average current efficiency of 6.2%. CV measurements showed that decreasing A/C by reducing anode surface area decreased the peak current of anodic oxidation thus less active chloride accumulation, while varying A/Cs had no effect on cathodic nitrate reduction. Neutral pH was more favorable for nitrate reduction for both A/Cs of 1.00 and 0.12. This study provided a feasible approach for optimizing the electrochemical nitrate reduction process.