Modification Of TiO₂Nanotube Arrays And Photoelectrocatalytic Reduction Of Percholate

Perchlorate is a new emerging persistent pollutant that can diffuse rapidly inenvironment, and it is very stable and difficult to be degraded, which attracts a greatattention from scientists. Several techniques are being applied in attempting toremove ClO4-from aquesous solution, such as activated carbon adsorption,ion-exchange, membrane filtration, chemical redution. However, the way ofphotoelectrocatalytic reduction of perchlorate is few investigated and reported.Inthis work, N/Ag codoped TiO2nanotube arrays are to be prepared and servered asphotoanode to reduce perchlorate.TiO2nanotube arrays were prepared by the anodic oxidation method. Thedegradation of O₂/L RhB in2h is67%.Then N was successfully doped into TiO2nanotube arrays through electrochemical method with two kinds of nitrogen source—ammonium nitrate and urea. The results show that when1wt%NH4NO3solutionserves as N Precursor, the degradation of O₂/L RhB in visible light is24.5%, thebest doping amount is1.09at%. The Ag-TiO2nanotube arrays were prepared byphotochemical deposition method in AgNO3aqueous solution. The TiO2nanotubearrays loaded with silver of12.01wt%possessd the best photocatalytic activity, andthe degradation of RhB is98%. Combining the two methods successfully preparedN/Ag-TiO2nanotube arrays. The degradation rate of RhB under visible lightincreased by9%compared to1N-TNTs, and the degradation rate of RhB increasedby6.1%compared to Ag-TNTs. It shows that codoping can further improvephotocatalytic properties.A photoelectrocatalsis reduction system for perchlorate was built and studied:N/Ag-TiO2nanotube arrays act as photoanode, Ti mesh as photocathode, a certainamount of perchlorate with0.15mmol/L citric acid and1mmol/L NaCl aselectrolyte, and bias potential provided by DC power supply, two8W mercury lampas the UV light source. The effects of anodic potential, pH, the area of photoanodeand cathode were studyed. The results show that when the area of photoanode is20mm3100mm, Ti mesh of the same area as cathode, plus the bias potential of1.5V,and the initial pH of3.6, the removal rate of ClO4-can reach62%, which provides anew possibility for the removal of perchlorate.