Triplet-Excited Benzoates Significantly Enhance HO<sup>•</sup> Formation and Free Chlorine Decay in a UV<sub>222</sub>/Chlorine Advanced Oxidation Process
Bibliographic record
Abstract
Far UV light (UV 222 ) is a promising alternative to traditional 254 nm UV light (UV 254 ) in water treatment, raising great interest in UV 222 -based advanced oxidation processes, particularly UV 222 /chlorine. This study uncovers a novel mechanism for radical generation in UV 222 /chlorine mediated by benzoate (BA), a model compound for benzoate pollutants and moieties of natural organic matter. 10 μM BA significantly enhanced HO • formation and free chlorine decay by 77% and 530% in UV 222 /chlorine, respectively, but showed less effect on UV 254 /chlorine. This enhancement was attributable to an excited-state transformation pathway of BA in UV 222 /chlorine, contributing 64% to BA degradation due to the strong absorption of BA at 222 nm and the high photon energy of UV 222 . The triplet excited state ( 3 BA*) was a key intermediate from BA photoexcitation, followed by the generation of hydrated electrons (e aq – ) via 3 BA* photoionization. Both 3 BA* and e aq – reacted with free chlorine to form HOCl •– at determined rate constants of 1.33 × 10 9 M –1 s –1 and 1.50 × 10 10 M –1 s –1 at pH 7, respectively, and then HOCl •– rapidly decomposed to HO • . Finally, monohydroxylated and dihydroxylated benzoates were produced via the hydrolysis of BA intermediates. This study highlights the critical role of excited benzoates in radical formation and discloses a new abatement mechanism of benzoates in UV 222 /chlorine.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".