固载TiO_2光催化降解废水中氨氮的动力学模型

Study on kinetic model for photocatalytic degradation of NH_3-N with loaded TiO_2

采用固载TiO2光催化氧化处理模拟和实际氨氮废水,研究了反应的动力学模型和反应条件对氨氮氧化速率的影响。结果表明,在低浓度氨氮的TiO2光催化过程中,氨氮分子在催化剂表面的吸附是整个降解过程的控制步骤,过程的动力学方程遵循r=kKCA/(1+KCA)。若此时,氧浓度为常数时,氨氮在水中的降解可用拟一级反应模型来近似;催化剂投加量、曝气量、反应温度、光强等反应条件对反应的表观速率常数有着显著的的影响。

Photocatalytic degradation ot ammonia-nitrogen in both stimulated and industrial coking wastewater with loaded TiO2 was carried out in this study, in order to find out kinetic model for this process and the operating conditions＇ influences on the reaction rate. The results showed that under the low concentration NH3-N, the absorption of ammonia-nitrogen onto the surface of catalyst was the controling step in the whole step-by-step process, and that the empirical kinetic performance equation could be expressed as r = kKCA/（ 1＋ KCA ）. And when the concentration of oxygen in the liquor phase could be taken to be approximately constant, the reaction is pseudo first order with respect to ammonia. The experimental results also indicated that the quantity of catalyst, the air rate, the temperature and the light intensity are among the major factors effecting the apparent rate constant signifieantly.