Electroreduction of nitrate in water: Role of cathode and cell configuration

• GF cathode exhibited the best in nitrate removal (70%) and corrosion resistance.
• Much higher nitrate removal was obtained in DCC than in SCC.
• The optimal value of applied cathodic potential of −1.8 V was recommended.
• The presence of chloride ion enhanced nitrate removal in DCC.

The performance of direct electroreduction of nitrate was studied to investigate the role of different cathodes (graphite felt, GF; Cu–Ni alloy, Cu90Ni10; titanium, Ti) and cell configurations (single-chamber cell, SCC; dual-chamber cell, DCC). Experimental results indicated the performances of these electrodes for nitrate removal rate and cathodic current in linear sweep voltammograms were in the order of GF > Cu90Ni10 > Ti. The GF cathode, with the highest nitrate removal of 70%, also exhibited higher corrosion resistance than the Cu90Ni10 cathode. Nitrate removal in DCC was much higher than in SCC with GF as cathode. The cation membrane equipped in the reactor significantly improved the nitrate electroreduction. The nitrate reduction efficiency was the highest at an applied cathodic potential of −1.8 V, over which it decreased because of the impediment of hydrogen evolution at higher potential. The nitrate removal rate increased slightly with the presence of chloride ion, however, decreased with sulfate ion in the solution. Nitrate removal in DCC with GF as cathode showed broad application prospect.

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