Simulating Biomass Burning Emissions: Organic Acid Production from Lignin Under Variable Combustion and Aging Conditions
ESTHER OLONIMOYO, Elise Aggrey, Akua Asa-Awuku, University of Maryland
Abstract Number: 87
Working Group: Combustion
Abstract
Biomass burning is a major atmospheric source of organic acids, yet the influence of specific fuel components and combustion conditions on their formation remains poorly constrained. In the atmosphere, organic acids contribute to secondary organic aerosol (SOA) formation, affect cloud condensation nuclei (CCN) activity, and influence regional air quality and climate. This study investigates the production of 13 low molecular weight organic acids from the thermal degradation and oxidative processing of lignin, a key structural biopolymer in biomass and a proxy for plant-derived fuels. Controlled experiments were conducted in a tube furnace at 200°C, 300°C, and 400°C to simulate smoldering and flaming fire conditions. Aqueous hydrogen peroxide (10%, 25%, and 50% H₂O₂) was used as an oxidant to mimic post-emission oxidative aging. Lignin mass and oxidant strength were systematically varied to determine their effect on organic acid yields.
Among the target compounds, acetic acid and malonic acid showed the highest concentrations across all conditions. Adipic acid and citric acid remained relatively constant, while heavier acids (butyric, isovaleric, valeric, and glutaric) were consistently below detection limits. Our findings suggest that combustion temperature, fuel loading, and oxidative strength each play roles in modulating organic acid production, with lower temperatures and higher oxidant concentrations favoring higher yields of lighter acids identified in the particulate phase. This work provides new insights into the mechanisms driving organic acid formation during biomass combustion and post-emission aging, with implications for air quality, aerosol formation, and climate modeling. This work also contributes to closing the knowledge gap between laboratory simulations and real-world biomass burning, offering valuable data for refining emission inventories and improving chemical transport model predictions of atmospheric organic acid burdens.