Beijing Innovation Center for Engineering Science and Advanced Technology, State Key Joint Laboratory for Environmental Simulation and Pollution Control, Center for Environment and Health, and College of Environmental Sciences and Engineering, Peking University, Beijing, 100871, China.
Wadsworth Center, New York State Department of Health, Albany, NY, 12201, USA.
Sci Rep. 2019 Mar 13;9(1):4351. doi: 10.1038/s41598-018-37973-x.
Photolysis rate constant of HNO on the surface (HNO) has been found to be enhanced by 1-4 orders of magnitude from that of gaseous HNO, with HONO and NO as the main products. Such Re-NOx-ification pathway extends the apparent lifetime of reactive nitrogen species and modifies the atmospheric oxidative capacity along its long-rang transport. Despite of its importance, the detailed kinetics and mechanisms of HNO photolysis are still not clear. Surface film of HNO and organic compounds is ubiquitous in the environment and imposes matrix effect on HNO photolysis. Here we studied photolysis of HNO on Pyrex glass in a photochemical flow reactor over a wide range of HNO surface density (D) with or without the presence of model organic compounds. The photolysis rate constant of HNO varied with D and surface-catalysis mechanism was proposed. Organic compounds further enhance the photolysis rate constant by up to one order of magnitude via both photosensitization and H-donating reaction. The H-donating reaction enhances as well the secondary HONO yield from reaction between the primary product NO and adjacent H-donor, and thus increases the HONO/NO production ratio. Finally, detailed mechanisms involving surface-catalyisis, photosensitization and H-donating reactions was integrated.
HNO 在表面的光解速率常数（HNO）已被发现比气态 HNO 增强了 1-4 个数量级，主要产物为 HONO 和 NO。这种 Re-NOx-ification 途径延长了活性氮物种的表观寿命，并沿其长程传输改变了大气氧化能力。尽管其重要性，但 HNO 光解的详细动力学和机制仍不清楚。HNO 和有机化合物的表面膜在环境中无处不在，并对 HNO 光解产生基质效应。在这里，我们在光化学流动反应器中研究了 HNO 在 Pyrex 玻璃上的光解，在有无模型有机化合物的情况下，HNO 的表面密度（D）范围很广。HNO 的光解速率常数随 D 而变化，并提出了表面催化机制。有机化合物通过光增感和 H 供体反应将光解速率常数进一步提高了一个数量级。H 供体反应也增强了初级产物 NO 与相邻 H 供体之间反应的次级 HONO 产率，从而增加了 HONO/NO 的生成比。最后，整合了涉及表面催化、光增感和 H 供体反应的详细机制。
