【作者】 唐艳；

【导师】 呼世斌；

【作者基本信息】 西北农林科技大学 ， 环境工程， 2007， 硕士

【摘要】 随着工农业生产的发展,含氮化合物排放量急剧增加。氨氮已成为环境的主要污染物,并引起了社会各界的关注。开发经济、高效的除氮技术成为水污染治理的重点和热点。TiO₂光催化技术作为一种新的水处理方法,具有能耗低、操作方便、反应条件温和、无二次污染等突出优点。本文应用TiO₂光催化技术对氨氮的降解进行了研究。实验以氨氮为处理对象,从TiO₂光催化剂的制备条件、TiO₂掺杂贵金属Pt的改性和应用负载改性后的光催化剂降解实际氨氮废水三个方面对氨氮的光催化降解作了研究。探讨了溶胶-凝胶法制备TiO₂过程中原料的配比和制备工艺条件对TiO₂光催化降解氨氮的催化活性的影响;贵金属Pt的掺杂对TiO₂降解氨氮的光催化活性影响;负载型Pt/TiO₂光催化剂对氮肥厂氨氮废水的降解工艺等。得出以下结论:（1）分别采用单因素实验和正交实验设计,以氨氮为降解对象进行光催化活性实验,讨论溶胶-凝胶制备过程中各因素对TiO₂光催化降解氨氮活性的影响,确定TiO₂光催化剂应用于氨氮降解的最佳制备工艺。本试验确定的最优制备条件为:水解反应温度30℃,催化剂焙烧温度为500℃,n（H2O）/n[Ti（OC4H9）4]=5;n（C2H5OH）/ n[Ti（OC4H9）4]=20;n（HNO3）/ n[Ti（OC4H9）4]=0.3;（2）为提高TiO₂的光催化活性和更有效的将氨氮转化为目标产物N2,实现氮的彻底去除,本文对TiO₂进行了Pt掺杂改性,制备了光催化剂Pt/TiO₂。并用光催化法使水中的氨氮,经由光催化氧化氨氮、还原亚硝态氮形成气态产物N2,实现水体彻底脱氮。实验考察了负载Pt的含量、pH值、Fe2+的添加对光催化剂催化氨氮活性的影响以及在太阳光照射下自制Pt/TiO₂对氨氮的降解效果。实验表明在碱性条件下光催化剂对氨氮有较好的去除效果,载铂量（质量分数）为0.5%的Pt/TiO₂光催化剂对氨氮的降解率最大,此时降解率为87.60%。且在Fe2+的存在下,没有硝态氮等副产物的产生,对氨氮的降解率为86.92%。体现了该催化剂具有将氨氮转化为N2的良好光催化氧化选择性。在太阳光照射下该催化剂对氨氮有一定的降解效果,试验自制的Pt/TiO₂光催化剂在太阳光照射下,当氨氮初始浓度为100mg/L时,对氨氮的降解率为60.39%。（3）采用自制的负载型Pt/TiO₂光催化剂处理初始氨氮浓度为342.56mg/L的某氮肥厂氨氮废水。研究表明催化剂的负载次数、催化剂的投加量、光照强度、pH值、反应时间等工艺条件都对光催化降解氨氮有一定的影响:负载两次的光催化剂Ⅱ- Pt/ TiO₂对氨氮的处理效果最好,此时载体负载Pt/TiO₂的量（质量分数）为10.30%;催化剂的最佳投加量（以Pt/TiO₂计）为2.5g/L;pH值对氨氮的降解效果有较大影响,本试验中,pH=8时反应效果最好;实验证明用Ⅱ- Pt/ TiO₂去除氨氮的最佳反应时间定为5h,反应5h后,氨氮的降解率为85.16%,此时废水氨氮浓度为50.84mg/L,硝态氮和亚硝态氮浓度分别为6.89mg/L和2.72mg/L,可以达到废水排放标准。所制负载型光催化剂经过多次连续使用,试验证明,负载型光催化剂Ⅱ- Pt/ TiO₂具有一定的寿命和较好的负载牢固性。更多还原

【Abstract】 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.TheⅡ- 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.更多还原