Study Of Non-Noble Metal On Electrochemical Reduction Of Nitrate In Water

Nitrate concentration in ground and drinking water is increasing with the human activity related to the usage of nitrogen. High concentration nitrate is easily converted into nitrite in organisms, which is an established cause of methemoglobin and a suspected carcinogen. In this paper, electrochemical method was used to remove nitrate from raw water, by some cheap metal material such as Al, Fe, Cu, AlFe alloy as its cathode. The aim is to remove nitrate fast and obtain the reduction mechanical, what’s more, to find a suitable electrode material for nitrate reduction.In neutral Na2SO4supporting electrolyte solution, Linear Sweep Voltammetry was held to study the reducing potential of nitrate on Al, Fe, Cu as electrochemical cathode. The emphasis of the work was nitrate reduction mechanism on Cu electrode. The electronic number was calculated as2and6for relevant reduction peak, indicating that the current at-0.8V vs. SCE was nitrate convert into nitrite and at-1.3V vs. SCE may be nitrite to ammonia. Some reterences obtain similar result in alkaline solution. The current for Cu electrode as cathode to electrolyze nitrate was low in electrolysis experiments at positive potential, even though it shows high transient reducing current in LSVs. However, Cu could be used as a modifier, for the reason that the selectivity of nitrite and ammonia on Cu is so good.A new material AlFe alloy, which has advantages over Al and Fe, performed in solution containing70±2mg·L-1NO3--N and97%and71%of denitrification efficiency was obtained at-1.2V and-1.05V vs. SCE in2h electrolysis, respectively. In these two conditions, ammonia/ammonium became the main products for nitrate reduction. It is possible that nitrogen gas run off from the solution, while the total nitrogen decreased for29mg·L-1in solution at-1.05V. On the basis of AlFe10alloy and Cu, the trimetallic Cu/AlFe10are designed to use Cu as electro-catalytic and protective surface and AlFe10alloy as the electronegative component in the core. The AlFe10core can enhance the electro-catalytic of Cu surface at low potential. The Cu surface can prevent the dissolution of AlFe and increase the selectivity of reduction products.The performance toward the reduction of nitrate was compared between Cu, AlFe and Cu/AlFe10electrode by constant potential electrolysis. The electrolysis experiments at different potential indicate that the products ratio of nitrite and ammonia is easy to controll on Cu/AlFe10compared with Cu and -The prepared electrode was characterized by SEM and XRD, what’s more, the dissolved metal element from Cu/AlFe10electrode is negligible as compared with AlFei0. The Tafel curves and electrochemical impedance spectroscopy shows the corrosion resistance of Cu/AlFe10just lower than Cu and different initial nitrate concentration electrolysis shows high activity even for removal of high concentration of nitrate, which means Cu/AlFe10is a promising material for electrochemical treatment of nitrate contamination. The synergistic effects on Cu/AlFe10are responsible for the enhanced activity and stability.