气相正己烷的光催化及臭氧/光催化降解动力学

初步研究了气相中低浓度的正己烷在较大流量(5L/min～17L/min)臭氧/紫外(O₃/UV),光催化(TiO₂/UV)及臭氧/光催化(O₃/TiO₂/UV)3种方法的降解的动力学,考察了正己烷的初始浓度、流量、水蒸气浓度、臭氧投加量等因素的影响.研究表明:正己O₃/TiO₂/UV降解效率远高于O₃/UV的降解效率,明显高于TiO₂/UV降解效率;相对于初始浓度,正己烷的TiO₂/UV及O₃/TiO₂/UV反应符合L-H模型,对于O₃/UV过程用L-H模型不能得到较好的拟合;随着流量的增加正己烷在TiO₂/UV与O₃/TiO₂/UV降解过程中的反应速率先增加后保持不变,但是在O₃/UV过程中其反应速率变化不大;湿度对正己烷的降解有一定的影响;随着臭氧投加量的增加,正己烷O₃/UV和O₃/TiO₂/UV的降解速率呈直线增加,在O₃/UV过程中正己烷的反应速率增加更快.

Kinetics of Degradation of Hexane in the Gas Phase by Photocatalysis and Combined Photocatalysis and Ozone

The degradations of trace hexane under high flow rate (5 L/min-17 L/min) in the gas phase by TiO2/UV, O3/UV and O3/TiO2/UV were studied. The kinetic effects of the inlet concentration of hexane, flow rate, water concentration and ozone dosage on the conversion of hexane in the three processes were examined respectively. The experimental results showed that the addition of ozone to the photocatalysis process increased the conversion of hexane significantly. The O3/TiO2/UV process was more efficient than the TiO2/UV in decomposing hexane. The degradation rate increased with increasing the initial concentration of hexane in the processes of TiO2/UV and O3/TiO2/UV. They matched well with the Langmuir-Hinshelwood (L-H) kinetic model. In the range of flow rate studied, the degradation rate increased with an increasing flow rate in both processes of TiO2/UV and O3/TiO2/UV, while was not affected in the process of O3/UV. The degradation rate in the three processes was affected by water concentration. The degradation rate of the two processes O3/UV and O3/TiO2/UV increased almost linearly with the increase of ozone dosage.