Study On Photocatalytic Degradation Of Ammonia Nitrogen Wastewater With TiO₂

With the development of the industry and agriculture,the nitrous compounds has increased rapidly.And ammonia nitrogen has made the master pollutant which draws general concern of the international community.Researching a kind of economical and efficient method become a hot and important spot in the field of water pollution treatment.As a kind of new wastewater treatment method,TiO₂ photocatalyst has many advantages,such as low-energy,flexible operations and nosecondary pollutant,etc.This paper studied on photocatalytic removal of ammonia nitrogen by Titanium dioxide.Taking ammonia nitrogen as the researching object,this thesis aim at improving the TiO₂ photocatalytic activities by optimizing technique in the Sol-gel process and depositing rare metal on TiO₂ powder and supporting Pt/TiO₂ with firebricks.The main findings are as following:(1) Using the photodegradation rate of ammonia nitrogen solution as an indicator,the effects of the dosage of water,ethanol and nitric acid on the photocatalytic activity of TiO₂ were investigated by using experimental design methods of single factor analysis and L9(34) Orthogonal Design respectively. The results show that the optimum hydrolysis temperature is 30℃; the calcinations temperature is about 500℃, n(H2O)/n[Ti(OC4H9)4]=5, n(C2H5OH)/ n[Ti(OC4H9)4]=20, n(HNO3)/ n[Ti(OC4H9)4]=0.3.(2) In order to improve the activities of TiO₂ photocatalytic and transform photocatalytic oxidation of ammonia nitrogen to N2.In this work,we have made the photocatalyst Pt/TiO₂.The experiment studied the effect of photodegradation of ammonia nitrogen on the concentration of Pt, pH, Fe2+ respectively.The result showed that in alkalescence conditions the photocatalyst plays a good photocatalytic activity.When the concentrion of Pt (mass fraction) was 0.5%,the degradation rate of ammonia nitrogen was 87.60%. With the fluence of Fe2+, there are not other products such as NO3--N,and the degradation rate of ammonia nitrogen was 86.92%.The result indicates that the photocatalyst has a good selective oxidation which turn ammonia nitrogen into N2.At the same time,under the circumstance of the sun's ray, the degradation of ammonia nitrogen was 60.93% by Pt/TiO₂.(3) Using homemade Pt/TiO₂ photocatalyst to treat the ammonia nitrogen wastewater of nitrogenous fertilizer factory which the original concentration of ammonia nitrogen was 342.56mg/L.The result showed that the photodegradation activity was effected by the Pt/TiO₂ loading times,catalyzer dosage,light intensity,pH and reaction time,etc.Theâ…¡- Pt/ TiO₂ which the concentration of Pt/TiO₂ was 10.30% has the best effct on the degradation of ammonia nitrogen;The experiment indicated that the optimum pH was 8.0, the optimum reaction time was 5 hours,and the degradation rate was 85.16%,and the concentration of ammonia nitrogen,NO3--N and NO2--N was 50.84mg/L, 6.89mg/L and 2.72mg/L respectively.In this condition,the effluent water treated by photocatalysis can reach the wasterwater emission standard.At the same time,by means of which using the supported Pt/TiO₂ continuously,we found that the photocalyst has good catalyst life and stability.