Optical properties investigation of the reactions between methylglyoxal and glycine/ammonium sulfate

https://doi.org/10.1016/j.saa.2019.02.087Get rights and content
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Highlights

  • We used a wide range of measurement techniques to understand the brown carbon properties between methylglyoxal and glycine/ammonium sulfate and share some important conclusions from this study.

  • The deeper understanding of carbonaceous particulate aging through wet chemical reaction in ambient and its consequences on its spectral responses is an actual and adequate issue in environmental science.

  • The measurements contained within the paper are important to the current aqueous-phase chemical model.

Abstract

In recent years, “brown carbon” (BrC), as an important contributor to light absorption and climate forcing as aerosols, has been one of the forefronts in the field of atmospheric research. Aqueous BrC aerosols can be formed through aqueous reactions of methylglyoxal (MG) with nitrogen compounds, such as glycine (Gly) and ammonium sulfate (AS). When exposed to nitrogen compounds for several days, aqueous carbonyl compound MG became absorbent and fluorescent in the ultraviolet and near visible regions, according to UV/Vis and fluorescence spectroscopies. Experiment results showed that optical absorption of two aqueous BrC solutions in the spectral range of 250–480 nm significantly increased with increasing reaction time. After the reactions of MG with Gly and AS, the product absorbance followed the order of MG-Gly>MG-AS. For H2O2 oxidation photolysis, the atmospheric aqueous BrC showed the dynamic nature. Reaction kinetic, effective quantum yields and size distribution studies were conducted in the paper. Fluorescence lifetime values of the two BrC solutions were calculated. LC/MS analysis results clearly indicated that complicated organic compounds were formed in the reactions of MG with Gly and AS.

Keywords

Brown carbon
Methylglyoxal
Ammonium sulfate
Glycine

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