乙二醛在沙尘颗粒物表面吸附与转化的红外光谱研究

摘要

Glyoxal is one of the most important volatile organic compounds in the atmosphere. The reactions of glyoxal in the gaseous and aqueous phases and on the surfaces of secondary inorganic acidic aerosols can lead to atmospheric secondary organic aerosol (SOA) formation. However, up to now, there is no report on the heterogeneous reaction of glyoxal on dust particles. The present work investigated the heterogeneous absorption and transformation mechanisms of glyoxal on SiO2 and Α-A12O3 par-ticles. The progress of heterogeneous reaction conducted in the flow tube reactor was in situ monitored by transmission Fourier transform Infrared (T-FTIR). The reaction products were analyzed by combining T-FTIR with HPLC, IC, and HPLC-MS. It was found that oligomers form after the glyoxal is absorbed onto the particles (S1O2 and α-Al2O3); and for arAl2O3, organic acids form on the particle surface in absence of illumination and oxidants. Moreover, it was revealed that water vapor favors the formation of oligomers, but suppresses the production of organic acids. These findings help further understand the SOA formation from the heterogeneous reaction of glyoxal on dust in the atmosphere.%乙二醛是大气中一种重要挥发性有机物.它在大气中气相、水相及二次无机酸性颗粒物表面反应均可生成二次有机气溶胶(SOA).然而乙二醛与沙尘非均相反应研究却未见报道.本研究选取二氧化硅(SiO2)和三氧化二铝(α-Al2O3)颗粒作为实际沙尘模型,探讨了乙二醛与沙尘颗粒非均相吸附与转化机理.利用透射傅里叶变换红外光谱(T-FTIR)原位跟踪反应进程,再结合色谱和质谱分析了反应产物.结果发现,在无光照和无氧化剂参与条件下,乙二醛在以上两种沙尘组分颗粒表面吸附后均生成了低聚物,在α-Al2O3上还能生成有机酸；水汽能促进颗粒对乙二醛摄取,并有利于低聚物生成,但会抑制有机酸生成.这些发现对于认识大气乙二醛与沙尘非均相反应生成SOA具有重要意义.