Electrochemical removal of nitrate in high-salt wastewater with low-cost iron electrode modified by phosphate

Nitrate (NO₃^-) is a widespread pollutant in high-salt wastewater and causes serious harm to human health. Although electrochemical removal of nitrate has been demonstrated to be a promising treatment method, the development of low-cost electro-catalysts is still challenging. In this work, a phosphate modified iron (P-Fe) cathode was prepared for electrochemical removal of nitrate in high-salt wastewater. The phosphate modification greatly improved the activity of iron, and the removal rate of nitrate on P-Fe was three times higher than that on Fe electrode. Further experiments and density functional theory (DFT) calculations demonstrated that the modification of phosphoric acid improved the stability and the activity of the zero-valent iron electrode effectively for NO₃^- removal. The nitrate was firstly electrochemically reduced to ammonium, and then reacted with the anodic generated hypochlorite to N₂. In this study, a strategy was developed to improve the activity and stability of metal electrode for NO₃^- removal, which opened up a new field for the efficient reduction of NO₃^- removal by metal electrode materials.