目的 验证设计改进的光催化涂层净化气态有机物能力评价系统,使所设计的光催化评价系统可以准确地表征光催化涂层对如文章中所述0.25μL/L体积浓度级别的微量苯气体的降解情况.方法 首次采用PID光离子化检测器在线监测污染物降解效率,并进行了适当的材料及工艺上的改进.实验以两种TiO2光触媒涂层样品为对象,以苯作为污染物,进行了一系列性能表征实验.结果 评价系统性能良好,可以准确地反应出在5~20 W/m2可见光辐照下,两种不同光触媒涂层样品的光催化效率分别为11.7%~57.3%以及13.4%~67.4%.在实验考察的体积浓度范围0.05~0.4μL/L内,污染物浓度的变化对降解效率影响不大,而随着污染气体流速从30 mL/min增加至90 mL/min,两种涂层对污染物的降解效率变差,分别从43.6%降低到25.9%以及从52.9%降低到29.9%.结论 研究设计的光催化涂层评价系统精密准确稳定,其较高的检出限能够很好地满足光催化材料对痕量气态有机污染物降解情况表征的需要,可广泛用于光催化领域气-固两相反应的科学研究及产品评价.
The work aims to ensure that the designed photocatalytic evaluation system can accurately characterize degrada-tion effects of photocatalytic coating on 0.25μL/L benzene hydrocarbon gas by verifying and designing advanced photocatalytic evaluation system. PID photo ionization detector was firstly used to monitor dynamic degradation rate of pollutants. Materials and technology were improved so that 0.25μL/L level of benzene gas degradation could be detected by the system. A series of properties characterization test were performed to two TiO2 photocatalysts with benzene gas as pollutant. The evaluation system could effectively detect photocatalytic difference between the two photocatalysts as 11.7%~57.3% and 13.4%~67.4% respec- tively in 5~20 W/m2visible light. The influence of flow rate and concentration of the pollutants on the degradation efficiency were investigated as well. It was found that pollutant concentration had minor effect on degradation efficiency provided with 0.05~0.4μL/L of benzene gas. Otherwise, the degradation efficiency reduced from 43.6% to 25.9% and 52.9% to 29.9% re-spectively as flow rate of pollution gas reduced from 30 mL to 90 mL.The designed system is accurate and stable enough. Its high detection limit can characterize degradation effects of photocatalytic materials on trace gaseous organic pollutants, hence it can be widely used in scientific research of gas-solid two phase reaction and product evaluation in the filed of photocatalysis.
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