Coupled interfacial and bulk kinetics govern the timescales of multiphase ozonolysis reactions
Bibliographic record
Abstract
Chemical transformations in aerosol impact the lifetime of particle-phase species, the fate of atmospheric pollutants, and both climate and health-relevant aerosol properties. Timescales for multiphase reactions of ozone in atmospheric aqueous phases are governed by coupled kinetic processes between the gas-phase, the particle interface and its bulk, which respond dynamically to reactive consumption of O3. However, models of atmospheric aerosol reactivity often do not account for the coupled nature of multiphase processes. To examine these dynamics, we use new and prior experimental observations of aqueous droplet reaction kinetics, including three systems with a range of surface affinities and ozonolysis rate coefficients (trans-aconitic acid (C6H6O6), maleic acid (C4H4O4) and sodium nitrite (NaNO2)). Using literature rate coefficients and thermodynamic properties, we constrain a simple two-compartment stochastic kinetic model, which resolves the interface from the particle bulk and represents O3 partitioning, diffusion and reaction as a coupled kinetic system. Our kinetic model accurately predicts decay kinetics across all three systems, demonstrating that both the thermodynamic properties of O3 and the coupled kinetic and diffusion processes are key to making accurate predictions. An enhanced concentration of adsorbed O3, compared to gas and bulk phases, is rapidly maintained and remains constant even as O3 is consumed by reaction. Multiphase systems dynamically seek to achieve equilibrium in response to reactive O3 loss, but this is hampered at solute concentrations relevant to aqueous aerosol by the rate of O3 arrival in the bulk by diffusion. As a result, bulk-phase O3 becomes depleted from its Henry’s Law solubility. This bulk-phase O3 depletion limits reaction timescales for relatively slow-reacting organic solutes with low interfacial affinity (i.e., trans-aconitic and maleic acids, with krxn ~ 10^3 - 104 M-1 s-1), which is in contrast to fast-reacting solutes with higher surface affinity (i.e., nitrite, with krxn ~ 10^5 M-1 s-1) where surface reactions strongly impact observed decay kinetics.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".