[Influence of nanosized TiO2 catalyzed ozonation on the ammonia concentration in Songhua River water].

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 TiO2/zeolite dosage, but it was affected little when TiO2/zeolite dosage was above 50 g. When the temperature increased from 10 degrees C to 30 degrees C, 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.