Antimony(V) Retention by Lepidocrocite: Sorption, Coprecipitation, and Extractability
Bibliographic record
Abstract
We examined the mechanisms controlling sorption and coprecipitation of Sb(V) with lepidocrocite and assessed the efficacy of commonly used extraction schemes to recover sorbed and coprecipitated Sb(V) from lepidocrocite. Antimony K-edge EXAFS spectroscopy reveals coprecipitation involved Sb(V) incorporation into the lepidocrocite structure via Sb(V)-for-Fe(III) substitution, whereas sorption involved edge and double-corner sharing between SbO 6 and FeO 6 octahedra at the lepidocrocite surface (with the proportional abundance of these linkages decreasing as Sb(V) sorption increased). Sb(V) sorption to lepidocrocite enabled faster Sb dissolution relative to Fe in 1 M HCl, whereas coprecipitation facilitated congruent dissolution of Sb and Fe. The Wenzel sequential extraction scheme substantially underestimated Sb(V) adsorption to the lepidocrocite surface, yet recovered remaining sorbed Sb(V) and all coprecipitated Sb(V) in extraction steps that target hydrous oxide-bound species. In contrast, very little sorbed or coprecipitated Sb(V) was recovered by the reducible step of the BCR sequential extraction, despite lepidocrocite being a readily reducible Fe(III) oxide. Instead, the BCR scheme incorrectly implied that lepidocrocite-bound Sb(V) was mostly oxidizable or nonreactive (i.e., bound in sulfides, organic matter, or highly stable phases such as tripuhyite). This study provides new insights into Sb(V) retention by lepidocrocite while providing useful guidance on the utility of common Sb extraction schemes.
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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".