Temperature-dependent aqueous OH kinetics of C2-C10 linear and terpenoid alcohols and diols: new rate coefficients, structure-activity relationship and atmospheric lifetimes

• DOI: 10.5194/egusphere-2023-1381
• Publication Date: 2023-08-14T06:14:46Z
• Authors: Bartłomiej Witkowski; Priyanka Jain; Beata Wileńska; Tomasz Gierczak
• Keywords: Reaction rate; Carboxylate; Atmospheric temperature range

Abstract. Aliphatic alcohols (AAs), including terpenoic (TAs), are ubiquitous in the atmosphere due to their widespread emissions from natural and man-made sources. Hydroxyl radical (OH) is most important atmospheric oxidant both aqueous gas phases. Consequently, oxidation of TAs by OH inside clouds fogs a potential source secondary organic aerosols (aqSOAs). However, kinetic data, necessary estimate time scales such reactions limited. Here, bimolecular rate coefficients (kOHaq) for twenty-nine, C2-C10 AAs hydroxyl radicals were measured with relative method temperature range 278–328 K. kOHaq values fifteen first after validating experimental approach. The at 298 K between 1.80×109 6.5×109 M-1s-1. activation parameters (activation energy (7–17 kJ/mol) average Gibbs free activation=20 strongly indicated predominance H-atom abstraction mechanism. estimated rates complete diffusion-limited revealed up 44 % diffusion contribution C8-C10 AAs. data acquired here, literature AAs, carboxylic acids, carboxylate ions used develop modified structure-activity relationship (SAR). new SAR developed this work predicted temperature-dependent all compounds under investigation higher accuracy as compared previous models. In model, an additional neighboring parameter was introduced (F≥(CH2)6, using homolog (C2-C10) linear diols. Good (slope=1.05, R2=0.75) achieved acids investigation. database compiled data) also further enhance ability predict calculated lifetimes indicate that diols will react aerosol, cloud, fog water (LWC≥0.1 g/m3) (LWC≥10-4 g/m3), respectively. preference undergo realistic conditions comparable which makes them potentially effective precursors aqSOAs. clouds, decrease favor reaction OH, primarily increased partitioning into phase following Henry’s law equilibrium.