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BIT Makes Important Progress in the Research of the New Particle Formation

release date :2019-12-30 02:00:00  |   [ close window ]ViewCount:

  

  Beijing Institute of Technology, December 20th, 2019: Recently, Professor Zhang Xiuhui and his collaborators in the School of Chemical Engineering and Environment of Beijing Institute of Technology(BIT)/ Key Laboratory of Cluster Science of Ministry of Education have made important progress in the field of new particle formation. The research results were titled "Unexpected quenching effect on new particle formation from the atmospheric reaction of methanol with SO3", which was published online on November 25th in Proc Natl Acad. Sci. USA (Proceedings of the National Academy of Sciences of the United States of America), link to the paper: https://www.pnas.org/content/116/50/24966. Liu Ling, PhD candidate, School of Chemical Engineering and Environment of BIT, and Zhong Jie, PhD candidate, University of Nebraska Lincoln, USA are both Co-first authors. Professor Zhang Xiuhui, School of Chemical Engineering and Environment of BIT, Professor Zeng Xiaocheng, University of Nebraska-Lincoln, USA and Professor Joseph S. Francisco of the University of Pennsylvania are co-corresponding authors. BIT is the first communication unit.

  

  New aerosol particles are an important source of atmospheric particulate matter and cloud-condensed nodules, which have a significant impact on regional environmental quality, climate and human health. The stage nucleation is the key to the formation of new particles, but the physical-chemical mechanism at the molecular level, especially the mechanism of aerosol nucleation in contaminated areas, remains a mystery. Alcohols are widely present in the atmosphere, with high concentrations and wide sources. Due to the weak hydrogen bonds formed between alcohols and common nucleating precursors in the atmosphere, alcohols are generally considered to have little effect on the formation of new particles in the atmosphere. Under the condition of atmospheric composite pollution, the presence of multiple pollutants leads to the coexistence of multiple chemical processes. Whether alcohols with a certain chemical activity will affect the aerosol nucleation through chemical conversion or not and the nucleation mechanism that affects it is not yet known clear.

  

  Figure 1 The competitive generation process of nucleation precursors (sulfuric acid (SA) and methyl sulfate (MHS)) and the subsequent formation of clusters. Methanol: MO, dimethylamine: DMA.

  

  Professor Zhang Xiuhui and his collaborators combined quantum chemical calculations and atmospheric cluster dynamics simulations to creatively add the conversion reaction of alcohols in the atmosphere and the factors that affect the formation of other nucleating precursors into aerosols nucleation simulation study (Figure 1). It was found that methanol can be converted into dimethyl sulfate by reaction with SO3 under the catalysis of common nucleation precursors (water, sulfuric acid and dimethylamine) and the conditions of composite atmospheric pollution, which could promote aerosol nucleation. and the occurrence of this process will inhibit the production of sulfuric acid, a key nucleating precursor, through competitive SO3 in dry and polluted areas with high methanol concentration (SO3 reacts with water, Figure 2, a). Based on the study of the above factors, it was found that methanol inhibited the sulfuric acid-dimethylamine nucleation process in the end and showed an unexpected inhibitory effect (Figure 2, b).

  

  Figure 2 (a) Changes in the concentration of methyl sulfate (MHS) and sulfuric acid (SA) (cm-3) produced by SO3 with the concentration of methanol (MO) at different water concentrations. (B) At different water concentrations, the particle formation rate J (cm-3 s-1) varies with MO concentration.

  

  On the one hand, this study puts forward a new mechanism for methanol to participate in the formation of new aerosol particles through chemical conversion in dry and highly polluted areas, and provides new research ideas and theoretical clues for the study of new particle formation mechanisms in China under composite atmospheric pollution conditions. On the other hand, it also reveals the key chemical processes that affect atmospheric sulfuric acid creation in dry polluted areas, and provides an important theoretical basis for accurately predicting the sulfuric acid concentration in the atmosphere. At the same time, the research also shows the necessity of considering the competitive process of nucleation precursor formation in the study of new particle formation mechanism, and provides an important new strategy for studying the model improvement of new particle formation mechanism.

  

Attached personal profile:

  Zhang Xiuhui, Professor, is a member of the research team of Professor Li Zesheng, School of Chemical Engineering and Environment, BIT. He has long been engaged in research in theoretical computational chemistry. In the past 3 years, he has made a series of research results in the field of atmospheric particle. In addition to the above-mentioned articles published in Proc Natl Acad. Sci. USA, they have also published papers in J. Am. Chem. Soc., Angew. Chem. Int. Ed., Atmos Environ., Chemosphere, J. Chem. Phys and other international top journals. The above research work was supported by general program (21976015, 21373025) of the National Natural Science Foundation of China.

  

News Source: School of Chemical Engineering and Environment, Zhang Xiuhui

Editor: News Agency of BIT

Translation: News Agency of BIT, Han Yu

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