| Groundwater is always one of the main sources of drinking water. Due to using of nitrogenous fertilizer, polluting of domestic wastewater, leaching of solid waste, nitrate pollution of the groundwater is serious in many countries. Generally nitrate pollution of the groundwater can lead to endangerment of human health directly or indirectly, so the World Health Organization considers an upper limit of 10mg/L as a standard in drinking water. The drinking water nitrate pollution results from many reasons, and it is difficult to control the nitrate pollution. So scientists regard the problem as a focal point. The approaches for nitrate removal have a lot of categories: physical methods, chemical methods, biological denitrification and electrocatalysis methods. Among the techniques available for the nitrate removal from water, biological methods, as a kind of standing-out technologies, have some shortcoming, such as, complex technics, low running speed. Chemical methods mostly reduce nitrate nitrogen by catalysis reaction with metal ions, which easily lead to a secondary pollution. Physical methods has a high running cost. As alternative approaches, the electrocatalysis methods, as environmental friendly and green technologies, are gradually concerned by investigators of late years.The research of nitrate reducing in drinking water by electrocatalysis methods was carried out in this paper. Then a new denitrated electrocatalysis electrode was obtained, a kind of simple and effective electrocatalysis reactors were also designed. Electrocatalysis electrode was prepared by electrodeposition process, electrodeposit solution allocationed as follows: Ti4+:Ce4+:Cu2+ =7:3:5, with 10mm×45mm basis of stainless steel. After pretreated via acid and alkaline solution, the optimum electrodeposit conditions as follows: ampere density 5mA/cm2, electrodeposit 30min, roasting temperature 500℃, roasting time 30min, and one time metallic-membrane plating. The ESM images presented that, the prepared electrodes had many merits, such as compacted surface, homogeneous thickness, tiny granule, no crazing. Besides, a kind of electrocatalysis reactors were also designed. Under the best conditions(voltage is 10V, current density is 25mA/cm2, electrode spacing is 10mm, the reaction time is 120min, NaCl is electrolyte), the removal ratio of NO3--N can reach 95%.In the modification procedure of electrodes, preparing electrocatalysis electrode, electrodeposition process is superior to pyrolytic process and immersion method, at same time, composite materials are material is superior to homogenous material. In this condition, the electrode film is well-distributed, its intensity is high and and with a high inensity and with perfect catalytic performance. Ordinarily, drinking water is supplied from different sources, which may cause the complicated water contents. Drinking water has many sources and complicated components. So we can prepare matching electrocatalysis electrodes and reactors according to different situations to reduce the concentration of by-product and to improve the performance of nitrate removal.The electrocatalysis methods are a new and practical technics in the removal of nitrate from water efficiently. Removing percentage is as high as 95% in short time. In economy, stainless steel is chosen as basis material, coated with Cu,Ti,Ce in this electrocatalysis methods. So it costs much less than many precious metals. Besides, low voltage, low electric current and low energy consumption make the whole process flows economical and practical. In spreading, the whole process is easy to operate and apply to practice, and need little area, moreover, produce nothing of pollution. Anyhow, it is an economy and practical technology worth of spread. |
