Electrochemically-induced reduction of nitrate in aqueous solution.

Area of Science:

• Environmental Science
• Electrochemistry
• Water Treatment

Background:

• Nitrate contamination in groundwater poses significant environmental and health risks.
• Conventional water treatment methods for nitrate removal can be costly and generate secondary waste.
• Electrochemical methods offer a promising alternative for in-situ contaminant remediation.

Purpose of the Study:

• To evaluate the efficacy of an electrochemical flow-through reactor for nitrate removal from synthetic groundwater.
• To investigate the use of a cathode-anode electrode sequence to minimize ammonia production during nitrate reduction.
• To optimize operational parameters such as electrode material, current intensity, and flow rate.

Main Methods:

• Testing of monometallic cathodes (Fe, Cu, Ni, carbon foam) with and without Pd/Ag catalyst coatings.
• Evaluation of different current intensities (60-120 mA) and flow rates (3 mL min⁻¹).
• Analysis of nitrate removal efficiency and ammonia production using a flow-through, undivided electrochemical system.

Main Results:

• Monometallic Fe foam cathodes achieved the highest nitrate removal rates, significantly enhanced by Pd catalyst (25.0% to 39.8%).
• Optimized conditions (Fe cathode, Pd catalyst, 3 mL min⁻¹ flow) reduced nitrate concentration below 10 mg L⁻¹ NO₃-N.
• Ammonia production was reduced from 92±4% after the cathode to 50% after the anode.

Conclusions:

• Flow-through, undivided electrochemical systems are effective for nitrate removal from groundwater.
• The chosen electrode sequence successfully minimizes ammonia generation during nitrate reduction.
• This technology presents a viable solution for groundwater remediation with controlled byproduct formation.