Application of Oxidation Flow Reactor in the Formation of Secondary Organic Aerosol from Biomass-Burning Emissions: A Review

Organic aerosol constitutes a major fraction of atmospheric particulate matter. Secondary organic aerosol (SOA), which is formed through the atmospheric aging of volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), and intermediate-volatility organic compounds (IVOCs), has important impacts on air quality, climate, and human health. Biomass burning emits a chemically complex mixture of gaseous and particulate organic compounds, which serve as a major source of SOA precursors. These compounds undergo coupled aging processes involving gas–particle partitioning, re-volatilization, multiphase reactions, and radical-initiated oxidation, thereby contributing to SOA formation. However, the formation pathways of SOA from biomass-burning precursors and the relative contributions of different precursor classes remain poorly understood. Oxidation flow reactors (OFRs), characterized by high oxidant exposure, short residence times, and the ability to simulate several days or even weeks of equivalent atmospheric aging within minutes, have become an important experimental platform for investigating SOA formation from biomass-burning emissions. This review systematically summarizes the structural configurations, construction materials, and oxidant systems of OFRs, with particular emphasis on their applications in studying SOA formation from the aging of VOCs, SVOCs, and IVOCs emitted from biomass burning. Briefly described the characteristics of OFRs and smog chambers in atmospheric simulation. Finally, current challenges in applying OFRs to biomass-burning SOA research are discussed, and future research priorities are proposed to improve their atmospheric representativeness and mechanistic interpretation.