Study On Preparation Of Co-Ti Electrode By Electrodeposition And Its Electrochemical Denitrification Properties

NO₃^-in water will affect the environment and mankind’s health seriously,so the removal of NO₃^--N becomes the main problem of wastewater treatment in our country.Electrochemical methods,due to its environmental-friendly feature,no extra chemicals,and simple operation,is regarded as a hopeful denitrification method.On the other hand,ion exchange can remove NO₃^--N effectively,but due to numerous waste brine with high concentration of salt,it can’t be widely used.Based on the treatise which shows that the Co₃O₄-Ti electrode has great ability to remove NO₃^--N,this essay aims at developing an electrode with high electrochemical activity,high stability and safety by changing the method of preparation,which can be used on the treatment of waste brine to solve the problem of ion exchange resin denitrification research of my research group and provide data support for NO₃^--N removal.The main contents and conclusions of this research are listed as followed:（1）Co-Ti electrode with high electrochemical activity,low loss and low release is developed by electrodeposition with optimized kind and amount of addictive.The amount of Co electrodeposition and the surface appearance are controlled by the electrodeposition time and the use of additives.The denitrification performance and stability of the electrode are evaluated by denitrification experiment for 60 min,ultrasound for 15 min and the amount of Co dissolution.The results show that when the Co electrodeposition is 3.36 mg cm^-2,the denitrification effect of Co-Ti electrode is the best.With the use of 0.15 mg L^-1 SDS,the mass loss after ultrasound is reduced from 0.21 mg to 0.055 mg best.The use of saccharin sodium salt and BYD will change the morphology of electrode surface into vesicle and smooth plane.It can induce the Co dissolution and the mechanical strength.Under the ultrasonic interference,the loss of electrode mass rises to 0.37 and 0.29 mg.In addition,the use of BYD induces the denitrification performance.Co-Ti is evaluated by using Co-Ti and Co₃O₄-Ti electrodes to test the denitrification performance and stability in the same condition.The results show that Co-Ti electrode achieves the best NO₃^--N and TN removal of 94.5%and31.7%,respectively,similar to Co₃O₄-Ti electrode.But the mass loss and Co dissolution are 0.55 mg and 0.024 mg L^-1,which are far less than 0.294 mg and 0.094 mg L^-1 of Co₃O₄-Ti electrodes.（2）The impact of Cl^-,inorganic carbon,Ca²⁺and coexistence of Ca²⁺and inorganic phosphorus to NO₃^--N removal by using Co-Ti electrode are explored that Cl^-can improve the removal of TN while the Ca²⁺and inorganic phosphorus decrease the removal of NO₃^--N.The results show that,Cl^-can improve the removal of TN,when the initial concentration of NO₃^--N is 15,25,50 and 100 mg L^-1,the removal rate of TN can get 100%to NO₃^--N of the Cl^-concentration at 75,110,230,400 and 1000 mg L^-1.The relation diagram of NO₃^--N concentration,Cl^-concentration,time and TN removal drawn in this paper can provide a judgment basis for the removal of TN by using the electrode in practical application system.Ca²⁺and inorganic carbon can form precipitation of Ca CO₃on the surface of electrode because of the high p H area,it has potential bad effect on denitrification performance of Co-Ti electrode.Inorganic phosphorus and Ca²⁺can form precipitation like Ca₃（PO₄）₂ on the electrode,it will obviously induce the denitrification performance.When the initial concentration of P is1,2,10,20 and 50 mg L^-1,the amount of precipitation is 0.3,2.8,4.8 and 4.8 mg,the removal of NO₃^--N are reduced from 83.1%to 77.7%,57.6%,56.4%,53.2%and 45.5%.（3）The electrode is applied in simulation water of denitrification resin desorption solution and three different kind of actual resin desorption solutions for NO₃^--N removal,and it’s found that complex water quality can greatly affect the performance of electrode,the turbidity,hardness and inorganic phosphorus should be removed to maintain the NO₃^--N removal.The results show that,because of the high concentration of Cl^-,the removal of TN can occupy 95%of the removal of NO₃^--N.However,different quality of water can lead to great difference of the removal rate of NO₃^--N.The removal rates of NO₃^--N are 97%,78%,19%and 38%of simulation water,HUAIHUA1,HUAIHUA2 and DAFENG resin desorption solutions after electrochemical denitrification in the condition of 20 m A cm^-2,the difference is caused mainly by turbidity,Ca²⁺and inorganic phosphorus.The removal rate of NO₃^--N can increase to73.3%after the treatment of filtration with 0.45μm filter membrane to HUAIHUA2,and the removal rate of NO₃^--N can increase to 74.3%after the treatment of hardness removal by using cation exchange resin to DAFENG.