Physicochemical Aspects of Catalytic Decomposition of Hydrogen Peroxide by Manganese Compounds
Bibliographic record
Abstract
New insights in the mechanism of alkaline darkening of (manganese-containing) wood pulps and the brightness loss observed in prolonged hydrogen peroxide bleaching are presented. From the mass and energy balance of the reactions of hydrogen peroxide with manganese compounds, it can be concluded that black MnO 2 contributes to pulp darkening. MnO 2 is formed from Mn(OH) 2 . When the hydrogen peroxide concentration drops below about 0.016 m (the number of moles per 1 kg of water), residual manganous hydroxide is oxidized further to MnO 2 by dissolved oxygen. Bleaching experiments on pulps spiked with manganese show a brightness reversal when the hydrogen peroxide concentration drops to about 0.015−0.027 m, in excellent agreement with the prediction. No brightness reversal is observed for pulps containing a negligible amount of manganese. The same mechanism can explain the advantage of high-consistency bleaching, in which local hydrogen peroxide concentrations are higher and more likely to remain above the critical concentration, below which darkening occurs.
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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) | 0.001 | 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".