多孔Fe-Si电极电催化还原硝酸根离子

水体硝酸盐污染已成为一个日益严重的问题。以多孔Fe和Fe-Si合金为阴极，Ti/IrO2为阳极构建电解系统，对模拟废水(100 mg·L-1NO3--N + 500 mg·L-1 NaCl + 500 mg·L-1 Na2SO4)进行电解以去除其中的硝酸根离子，并研究了多孔Fe-Si合金在电解过程中的稳定性。实验结果表明，增大电流密度有利于提高NO3--N和总氮的去除效率。当电流密度为40 mA·cm-2时，以多孔Fe为阴极，几乎无副产物产生，NO3--N和总氮去除率均为94.3%，但电解完成之后Fe电极腐蚀严重，溶液中铁离子浓度达1 418 mg·L-1。而以多孔Fe-Si为阴极时，随合金中硅含量增加，NO3--N和总氮去除率均呈下降趋势，但电极稳定性显著提高，电解完成之后溶液中Fe离子浓度显著下降。当Fe-Si合金中硅原子百分比为50%时，NO3--N和总氮去除率均为78.8%，此时溶液中Fe离子浓度仅为41 mg·L-1。多孔Fe-Si合金作为阴极还原硝酸根离子时，具有较高的硝酸根去除率和良好的稳定性，应用前景较好。

Electrocatalytic reduction of nitrate ions by porous Fe-Si electrode

Nitrate pollution in water hacorresponding author:s become a more and more serious problem. An electrolysis system with porous Fe and Fe-Si alloy cathodes and Ti/IrO2 anode was built to remove nitrate from a synthetic wastewater containing 100 mg·L-1NO3--N, 500 mg·L-1 NaCl and 500 mg·L-1 Na2SO4. The stability of the porous electrode was also studied. Results showed that the increase of current density favored the increase of the NO3--N and total nitrogen (TN) removal efficiencies. When porous Fe was used as the cathode, the NO3--N and TN removal efficiencies were 94.3% and no by-products were produced at electric current density of 40 mA·cm-2. However, a serious corrosion happened on the porous Fe after electrolysis, and the concentration of Fe ions in the solution reached 1 418 mg·L-1. When porous Fe-Si alloy was used as the cathode, the NO3--N and TN removal efficiencies decreased with the increase of silicon content in the porous Fe-Si alloy. However, the stability of the electrode was dramatically enhanced, and the concentration of Fe ions in the solution significantly decreased after electrolysis. Specifically, the NO3--N and TN removal efficiencies were 78.8% when silicon content in the porous Fe-Si alloy was 50%. At the same time, the concentration of Fe ions in the solution was only 41 mg·L-1. The high nitrate removal efficiency and good stability for porous Fe-Si alloy cathode show a promising prospect for its use in nitrate reduction.