Preparation Of Ni-Cu Electrocatalytic Oxidation Electrode And Treatment On Industrial Wastewater With High Concentration Of Ammonia Nitrogen

High-concentration ammonia-nitrogen industrial wastewater is difficult to treat due to its poor biodegradability and has become an important threat to the safety of my country’s water environment.Compared with traditional ammonia nitrogen removal processes such as biological methods,the electrocatalytic oxidation technology of ammonia nitrogen is simple,efficient,and less disturbed by toxic substances in the wastewater.With the advantages of no secondary pollution,it has become a hot spot in the research of nitrogen removal from high-concentration ammonia nitrogen industrial wastewater.However,due to the disadvantages of traditional electrocatalytic oxidation electrode materials for ammonia nitrogen,such as high price,easy passivation and deactivation,and low efficiency,the further development of this technology and its practical application in ammonia nitrogen wastewater treatment are hindered.Therefore,the development of low-cost electrode materials with high catalytic activity and stability has become the key problem to be solved in the application of electrocatalytic oxidation technology of ammonia nitrogen in the treatment of industrial wastewater with high concentration of ammonia nitrogen,which has important practical significance.On the basis of previous literature investigation and preliminary experiments,Ni-Cu hydroxide catalytic electrode materials with different molar ratios of Ni（Ni）and Cu（Cu）were prepared by hydrothermal synthesis under alkaline conditions,and the optimal ratio of Ni and Cu was screened.On this basis,the optimal proportion of Ni-Cu hydroxide was transformed into Ni-Cu oxide and Ni-Cu hydroxyl oxide electrode materials by annealing and adding strong oxidant under alkaline conditions.Ni-Cu hydroxide Ni_0.8Cu_0.2OH,Ni-Cu oxide Ni_0.8Cu_0.2O and Ni-Cu hydroxyl oxide Ni_0.8Cu_0.2OOH were finally prepared.The electrocatalytic oxidation performance and removal efficiency of ammonia nitrogen of the three electrodes were compared and investigated at the molar ratio of Ni:Cu=8:2.By means of SEM,TEM,XRD,XPS and other characterization methods,the surface microstructure,phase structure and valence composition of the three electrode materials were compared to analyze the differences between the three electrode materials,speculate the reason for the difference of the electrocatalytic oxidation performance of ammonia nitrogen and analyze the possible mechanism of the electrocatalytic oxidation process of ammonia nitrogen.Further test to explore the p H and the initial concentration of ammonia nitrogen optimal electrode electric catalytic oxidation reaction,the effect of ammonia nitrogen and the electrode to the simulation of the actual industrial wastewater ammonia nitrogen removal efficiency,so as to the preparation of low cost no platinum（Pt）catalytic electrode materials,promoting electric catalytic oxidation technology in the high concentration of ammonia nitrogen application in industrial wastewater treatment to provide the reference.The main conclusions are as follows:（1）The electrocatalytic oxidation of ammonia nitrogen by electrode material Ni_xCu_yOH is the result of the synergistic action of Ni and Cu.Cyclic voltammetry（CV）was used to test Ni-Cu hydroxide Ni_xCu_yOH with different molar ratios.Under the applied voltage of 0.8V（vs.Hg/Hg O）and without Cu in the electrode material,the electrocatalytic oxidation current density of ammonia nitrogen was 0.97 m A/cm².When only Cu is present in the electrode material,the electrocatalytic oxidation current density of ammonia nitrogen is 0.76 m A/cm²,which shows almost no catalytic activity.When the electrode material contains both Ni and Cu,the electrocatalytic oxidation current density of ammonia nitrogen is significantly higher than that of the electrode material containing only Ni or Cu;（2）The electrode Ni_0.8Cu_0.2OOH has the highest electrocatalytic oxidation current density for ammonia nitrogen,and the electrochemical polarization is small and the electrochemical active area is the largest in the reaction process,and the electrocatalytic oxidation performance is the best.Further ammonia nitrogen removal experiments also obtained corresponding results.When the initial concentration of ammonia nitrogen was600 mg/L,p H was 13,and the reaction time was 15 h,the removal rate of ammonia nitrogen at the electrode Ni_0.8Cu_0.2OOH could reach 61.5%;（3）The effect of Ni_0.8Cu_0.2OOH electrode on the electrocatalytic oxidation of ammonia nitrogen is significantly affected by p H and initial concentration of ammonia nitrogen.The removal rate of ammonia nitrogen increased with the increase of p H.When the initial concentration of ammonia nitrogen was 600 mg/L,the removal rates of ammonia nitrogen in the solution of 10,11,12 and 13 were 20.5%,29%,45.5%and61.5%,respectively.However,the higher the p H was,the more nitrite was produced in the side reaction.The removal rate of ammonia nitrogen by the electrode Ni_0.8Cu_0.2OOH increases with the increase of the initial concentration of ammonia nitrogen,and the production of nitrite increases,but the conversion rate of nitrite decreases.When the p H was 13 and the initial concentration of ammonia nitrogen was 1000 mg/L,800 mg/L,600 mg/L and 400 mg/L,the yield of nitrite was 32.5 mg/L,27 mg/L,23 mg/L and 17.5mg/L,respectively.The conversion rates of nitrite were 4.7%,5.2%,6.7%and 8.1%,respectively;（4）Ni_0.8Cu_0.2OOH electrode has a good effect on the removal of high ammonia nitrogen wastewater from simulated thermal power station.When the initial ammonia nitrogen concentration is 1000 mg/L and the p H is 13,the removal rate of ammonia nitrogen can reach 71.6%.The high salinity,organic matter and TP pollutants in wastewater have no obvious effect on the catalytic oxidation of ammonia nitrogen.