纳米TiO_2催化臭氧化对松花江水中氨氮的影响

Influence of Nanosized TiO_2 Catalyzed Ozonation on the Ammonia Concentration in Songhua River Water

研究了以负载于陶粒、硅胶、沸石表面的纳米TiO2作为催化剂时,催化臭氧化松花江水过程中氨氮浓度的变化.结果表明,在单独臭氧化过程中,氨氮浓度先升高后下降,反应30 min后的氨氮浓度与初始浓度相近.在以TiO2/陶粒、TiO2/硅胶为催化剂的催化臭氧化过程中,氨氮浓度也是先升高后下降,但反应过程中氨氮的平均浓度要高于单独臭氧化过程.以TiO2/沸石为催化剂时,催化臭氧化过程中氨氮浓度先下降,然后略有升高,继而又下降,30 min时对氨氮的去除率接近80%.单独臭氧化和催化臭氧化过程中,增大臭氧投量,氨氮浓度最大值出现的时间提前,并且反应过程中氨氮浓度平均值降低.增大催化剂TiO2/陶粒、TiO2/硅胶的投量,催化臭氧化过程中氨氮浓度平均值升高.增大TiO2/沸石投量,有利于氨氮的去除,但投量增大到50g以上时,对氨氮的去除效果影响很小.温度从10℃升高到30℃,对TiO2/陶粒、TiO2/硅胶催化臭氧化过程中氨氮浓度的变化影响不大.而以TiO2/沸石为催化剂时,温度升高有利于催化臭氧化过程中氨氮的去除.

Changes of the ammonia concentration in Songhua River water treatment using catalyzed ozonation were investigated. Nanosized TiO2 loaded on haydite, silica-gel and zeolite was prepared as the catalyst. The ammonia concentration increased in the first stage, then decreased. After 30 min reaction, the ultimate concentration was close to the initial concentration in ozonation. In catalyzed ozonation which used TiO2 / haydite or TiO2/silica-gel as the catalyst, the ammonia concentration also increased primarily and then decreased, but the average concentration was higher than that in ozonation alone. In catalyzed ozonation which used TiO2/zeolite as the catalyst, the ammonia concentration decreased primarily, then increased to a peak value, and decreased again. The removal efficiency was close to 80% after 30 min reaction. Effect of ozone dosage, catalyst dosage and temperature were investigated respectively. Increasing the ozone dosage, the maximum of the ammonia concentration appeared ahead and the average concentration of ammonia decreased either in ozonation or in catalyzed ozonation. Increasing the dosage of TiO2/haydite or TiO2/silica-gel, the average concentration of ammonia increased. The removal efficiency of ammonia benefited from the increase of TiOJzeolite dosage, but it was affected little when TiO2/zeolite dosage was above 50 g. When the temperature increased from 10℃ to 30℃, the changes of ammonia concentration were not affected in catalyzed ozonation using TiO2/haydite or TiO2/silica-gel as the catalyst. While the increase of temperature yielded an increase of ammonia removal efficiency when using TiO2/zeolite as the catalyst.