XPS study of reductive dissolution of birnessite by H <sub>2</sub> SeO <sub>3</sub> with constraints on reaction mechanism
Bibliographic record
Abstract
Reductive dissolution of 7 A bimessite [Mi 2+ 0.05 Mn 3+ 0.25 Mn 4+ 0.7 O 1.7 (OH) 0.25 ] by selenious acid (H 2 SeO 3 ) produces Mn 3+ and Mn 2+ surface reaction products (here represented as S-MnOOH and S-MnO. respectively) and Mn 2+ , 3+ -selenite surface complexes at the solution-mineral interface. Mn2p 3/2 , Se3d. and O1s X-ray photoelectron spectra of reacted surfaces reveal that Mn 4+ of birnessite is reduced simultaneously to Mn 3+ and Mn 2+ while Se 6+ is oxidized to Se 4+ according to the probable stoichiometric reactions: 2MnO 2 + H 2 SeO 3 + H 2 O → 2S-MnOOH + H 2 SeO 4 MnO 2 + H 2 SeO 3 → S-MnO + H 2 SeO 4 There is no XPS evidence for reduction of surface Mn 3+ to Mn 2+ in the presence of selenite. Whereas this reaction proceeds in the presence of arsenite. selenite apparently inhibits reduction of Mn 3+ . perhaps through formation of a strong Mn-selenite surface complex. The rate of release of Mn 2+ to dilute selenious acid (1.5 × 1O -3 M) is considerably lower than the rate of release to aerated, distilled water at similar pH. This behavior suggests that adsorbed selenite complexes impede the proton promoted dissolution of the soluble Mn 2+ component of birnessite.
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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".