Research Center of Environmental Catalysis & Separation Process, Beijing Key Laboratory of Energy Environmental Catalysis, College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, PR China.
Research Center of Environmental Catalysis & Separation Process, Beijing Key Laboratory of Energy Environmental Catalysis, College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, PR China.
Chemosphere. 2018 Dec;212:1172-1179. doi: 10.1016/j.chemosphere.2018.08.080. Epub 2018 Aug 20.
Microwave electrodeless discharge lamp (MEDL) has been regarded as a powerful light source of photoreaction. Four kinds of chemicals, nitrogen (N), oxygen (O), water (HO) and dimethyl sulfide (DMS), were used as molecular probes to explore the generation process of reactive oxygen species (ROS) and their photo-oxidation performances on the photodegradation of organic pollutants with application of an exterior MEDL system. ROS such as O (P), O, O (D) and O were generated via irradiation of O and HO except dry N by MEDL. They were transformed to other ROS including ·OH and HO with increase of relative humidity. The ROS productivity was inhibited evidently by humidity and ·OH became the major active species at high humidity. An optimal mineralization rate of 23.6% for DMS photodegradation was reached in dry air compared with 8.74% at high humidity, which indicated that O (D) and O were more powerful oxidants than O and OH. The results showed that the higher mineralization rate of organic pollutants was obtained by increasing the generation efficiency of ROS of O (D) and O. Furthermore, the results provided an alternative to develop intensification technology on photodegadation of organic pollutants with MEDL system and an optimal operation process including photocatalyst and humidity.
微波无极放电灯（MEDL）已被视为一种强大的光反应光源。本研究采用氮气（N）、氧气（O）、水（HO）和二甲基硫（DMS）四种化学物质作为分子探针，应用外 MEDL 系统，探讨活性氧物质（ROS）的生成过程及其对有机污染物光降解的光氧化性能。结果表明，除干燥的 N 外，MEDL 辐照 O 和 HO 可产生 O（P）、O、O（D）和 O 等 ROS。随着相对湿度的增加，它们转化为包括·OH 和 HO 在内的其他 ROS。ROS 的生成率明显受到湿度的抑制，而在高湿度下，·OH 成为主要的活性物质。在干燥空气中，DMS 的光降解矿化率达到 23.6%，而在高湿度下仅为 8.74%，这表明 O（D）和 O 比 O 和 OH 具有更强的氧化性。研究结果表明，通过提高 O（D）和 O 的 ROS 生成效率，可以获得更高的有机污染物矿化率。此外，这些结果为利用 MEDL 系统开发有机污染物光降解强化技术以及包括光催化剂和湿度在内的最佳操作过程提供了一种替代方案。
