采用沉淀法制备的MgO催化剂催化臭氧氧化水中氨氮,研究了pH、臭氧流量、催化剂投加量、时间和温度等因素对处理效果的影响。结果表明,500℃下煅烧得到的MgO的催化活性最高;在pH为9,MgO投加量为1 g/L,臭氧流量为12 mg/min,曝气时间为2 h,反应温度为60℃的条件下,当初始氨氮质量浓度为50 mg/L时,氨氮去除率可以达到96%,处理出水达到《地表水环境质量标准》(GB 3838—2002)的5类标准。叔丁醇抑制实验表明,MgO催化臭氧氧化氨氮的机理为MgO催化O3分解产生·OH,从而使氨氮得到降解。动力学分析显示,该反应符合准一级动力学方程,相关系数为0.994 6。
MgO catalyst has been prepared by precipitation method for the catalytic ozonation of ammonia-nitrogenin water.The influences of factors,such as pH,ozone flow,dosage of catalyst,time,temperature,etc.on thetreatment effect are investigated.The results show that the catalyzing activity of MgO obtained by calcination at500 ℃ is the highest.Under the following conditions:the pH is 9,dosage of MgO 1 g/L,ozone flow 12 mg/min,aeration time 2 h,reaction temperature 60 ℃ and initial concentration of NH4+-N 50 mg/L,the removing rate ofammonia-nitrogen is 96%.The treated effluent reaches the 5th kind of standard specified in Environmental QualityStandards for Surface Water(GB 3838—2002).Tert-butyl alcohol inhibition experiment indicates that the mechanismof MgO catalytic ozonation of ammonia-nitrogen in water is hydroxyl produced from the decomposition of MgOcatalysis O3,so as to degrade ammonia-nitrogen.Dynamics analysis show that the reaction complies with the pseudofirst-order kinetics equation,whose correlation coefficient is 0.994 6.