Critical Roles of Surface-Enhanced Heterogeneous Oxidation of SO2 in Haze Chemistry: Review of Extended Pathways for Complex Air Pollution
Critical Roles of Surface-Enhanced Heterogeneous Oxidation of SO2 in Haze Chemistry: Review of Extended Pathways for Complex Air Pollution
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DOI：
10.1007/s40726-023-00287-2
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发表时间：
2024-01
影响因子：
7.3
通讯作者：
Zihao Zhang;Haiwei Li;Wingkei Ho;Long Cui;Qihui Men;Li Cao;Yunjiang Zhang;Junfeng Wang;Cheng Huang;Shun-cheng Lee;Yu Huang;Mindong Chen;Xinlei Ge
中科院分区：
文献类型：
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作者：
Zihao Zhang;Haiwei Li;Wingkei Ho;Long Cui;Qihui Men;Li Cao;Yunjiang Zhang;Junfeng Wang;Cheng Huang;Shun-cheng Lee;Yu Huang;Mindong Chen;Xinlei Ge
审查目的随着化学复杂的空气污染过程，复杂的空气污染已在中国大城市地区蔓延。目前公认的化学机制尚未完全理解高浓度细颗粒物 (PM2.5) 和臭氧 (O3) 的经典二次污染物形成过程。燃烧产生的细颗粒含有丰富的纳米级黑碳（BC），其内部与过渡金属离子（TMI）混合，并极大地促进了复杂的氧化途径和产物。基于目前对多相硫酸盐形成的认识，我们提出表面增强的非均相反应过程在“雾霾化学烟雾”污染的快速形成中发挥着关键作用。最新发现BC和TMI增强硫酸盐的途径已被确定，以解释缺失的硫酸盐来源的形成机制。多相化学负责额外产生二次气体分子和气溶胶，通过表面光敏催化引发。此外，未知的大气氧化能力被认为是非均相过程的一部分。 BC和TMI颗粒具有独特的表面特异性特征和电子激发歧化反应，可以稳定地产生羟基自由基（OH）等活性氧（ROS）并促进SO2的氧化。这种现象提供了对大气自由基化学的深入了解。因此，气溶胶表面SO2的非均相催化氧化占雾霾事件中硫酸盐形成的高达69.2%。总结与云内水氧化不同，代表性的非均相反应途径（即TMI水催化途径和表面催化途径）在冬季和夏季都通过表面自由基反应增强硫酸盐的形成。异质过程被认为可以减少模型预测和测量的硫酸盐水平之间的差距。 BC和TMI具有物理和化学活性，在大气老化过程中可以改变PM的组成、形态、吸湿性和光学性质。因此，异质途径促进了雾霾污染的颗粒快速生长，并有助于了解和开发中国和其他发展中国家的新型空气污染化学（即“雾霾化学”过程）。
Purpose of ReviewComplex air pollution has spread in the conurbation areas of China along with chemically complicated air pollution processes. Classic secondary-pollutant formation toward high concentrations of fine particulate matter (PM2.5) and ozone (O3) is imperfectly understood in the currently accepted chemical mechanisms. The combustion-produced fine particles contain abundant nanosized black carbon (BC) internally mixed with transition metal ions (TMI) and contribute to the complicated oxidation pathways and products substantially. Based on current understandings of multiphase sulfate formation, we propose that the surface-enhanced heterogeneous reaction processes can play critical roles in the fast formation of “haze chemistry smog” pollution.Recent FindingsPathways of sulfate enhancement by BC and TMI have been identified to explain the formation mechanisms of the missing sulfate sources. Responsible for additional production of secondary gas molecules and aerosols, the heterogeneous chemistry is initiated with surface photosensitive catalysis. In addition, unidentified atmospheric oxidizing capacity is recognized as part of the heterogeneous processes. Given unique surface-specific profiles and electronically excited dismutation reactions, BC and TMI particles can steadily generate reactive oxygen species (ROS) such as hydroxyl radicals (OH) and promote the oxidation of SO2. This phenomenon provides an extended insight into atmospheric free-radical chemistry. As such, the heterogeneous catalytic oxidation of SO2on aerosol surfaces accounts for up to 69.2% of sulfate formation in haze episodes.SummaryUnlike in-cloud aqueous oxidation, representative heterogeneous reaction pathways (i.e., TMI aqueous catalysis pathway and surface catalysis pathway) enhance sulfate formation via surface radical reactions in both winter and summer. The heterogeneous processes are thought to reduce gaps between model-predicted and measured sulfate levels. The physically and chemically active BC and TMI can change the composition, morphology, hygroscopicity, and optical properties of PM in their atmospheric aging processes. Therefore, the heterogeneous pathways facilitate rapid particle growth for haze pollution and help to understand and develop a new type of air pollution chemistry (i.e., “haze chemistry” processes) in China and other developing countries.