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 distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.003 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.000 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".