Degradability of Iron(III)-aminopolycarboxylate Complexes in Alkaline Media: Statistical Design and X-ray Photoelectron Spectroscopy Studies
Bibliographic record
Abstract
Use of ferric-aminopolycarboxylate complexes for odor control via the oxidative scrubbing of H 2 S and CH 3 SH contained in pulp and paper noncondensable gas emissions is evoked as potentially beneficial from the standpoint of iron-sequestration and protection against precipitation in the alkaline environments characteristic of the Kraft mill sulfate-pulp processes. In this study, the degradability of two ferric-aminopolycarboxylate complexes in alkaline solutions was investigated by means of replicated four-factor three-level fixed-effects completely randomized factorial (2 × 3 4 ) designs. Expressed in terms of ferric-ethylenediaminotetraacetate (Fe 3+ EDTA 4- ) and ferric- trans -1,2-diaminocyclohexanetetraacetate (Fe 3+ CDTA 4- ) daily degradation rates, the degradability response was monitored via UV−vis spectrophotometry as a function of temperature ( T = 25, 40, 55 °C), alkalinity (pH = 8, 9, 10), ionic strength ( I = 0.025, 0.1, 0.5 M) and ferric concentration ( C Fe = 175, 280, 450 μM). Analysis-of-variance (ANOVA) of the factorial design suggests that pH and temperature are the main factors increasing Fe 3+ EDTA 4- and Fe 3+ CDTA 4- degradation rates. To a lower extent, ionic strength and ferric chelate concentration also promote degradation. At the most severe factor-level combinations ( T = 55 °C, pH = 10, and I = 0.5 M), up to 40% of Fe 3+ CDTA 4- and 54% of Fe 3+ EDTA 4- degraded after 1 day, confirming that CDTA is a superior chelating agent against iron precipitation in alkaline solutions. The brownish fresh-state Fe 3+ EDTA 4- or Fe 3+ CDTA 4- solutions evolved with degradation into turbid solutions whereof the precipitated solid was recovered and its surface probed through X-ray photoelectron spectroscopy (XPS). XPS revealed that the solid degradation product was inorganic and mostly contributed by Fe(OH) 3 . It was, however, not possible to identify which one of the organometallic complex degradation or the ferric dechelation was responsible for iron(III) hydroxide formation since both routes can contribute to its formation.
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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 | 0.001 | 0.001 |
| 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 | 0.001 |
| 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".