Structural Effects of Amines in Enhancing Methanesulfonic Acid-Driven New Particle Formation

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  • Jiewen Shen, Dalian University of Technology
  • ,
  • Jonas Elm
  • Hong Bin Xie, Dalian University of Technology
  • ,
  • Jingwen Chen, Dalian University of Technology
  • ,
  • Junfeng Niu, Dongguan University of Technology
  • ,
  • Hanna Vehkamäki, University of Helsinki

Atmospheric amines can enhance methanesulfonic acid (MSA)-driven new particle formation (NPF), but the mechanism is fundamentally different compared to that of the extensively studied sulfuric acid (SA)-driven process. Generally, the enhancing potentials of amines in SA-driven NPF follow the basicity, while this is not the case for MSA-driven NPF, where structural effects dominate, making MSA-driven NPF more prominent for methylamine (MA) compared to dimethylamine (DMA). Therefore, probing structural factors determining the enhancing potentials of amines on MSA-driven NPF is key to fully understanding the contribution of MSA to NPF. Here, we performed a comparative study on DMA and MA enhancing MSA-driven NPF by examining cluster formation using computational methods. The results indicate that DMA-MSA clusters are more stable than the corresponding MA-MSA clusters for cluster sizes up to (DMA)2(MSA)2, indicating that the basicity of amines dominates the initial cluster formation. The methyl groups of DMA were found to present significant steric hindrance beyond the (DMA)2(MSA)2 cluster and this adds to the lower hydrogen bonding capacity of DMA, making the cluster growth less favorable compared to MA. This study implies that several amines could synergistically enhance MSA-driven NPF by maximizing the advantage of different amines in different amine-MSA cluster growth stages.

Original languageEnglish
JournalEnvironmental Science & Technology
Pages (from-to)13498-13508
Number of pages11
Publication statusPublished - Nov 2020

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