Probing the In Situ Redox Behavior of Selenium on a Pyrite Surface by Scanning Electrochemical Microscopy
Bibliographic record
Abstract
The migration of released selenium because of human activities can cause many environmental issues. The immobilization of soluble selenium (i.e., selenite and selenate) on natural pyrite mineral is believed to be effective for selenium management. In this work, the redox behavior of immobilized selenium on pyrite has been investigated using in situ scanning electrochemical microscopy (SECM). The immobilization of selenium on pyrite (Se-pyrite) was realized through both electrodeposition and adsorption in selenite solution. The released species from Se-pyrite surfaces at various potentials were probed using the SECM tip. The electrodeposited Se-pyrite releases Fe2+ and selenite, suggesting selenium immobilized on pyrite through electrodeposition was in the form of both Se0 and FeSe2; while Se0 was the major form on the adsorbed Se-pyrite, and was associated with the sulfur sites instead of iron sites. The maximum amount of released selenium from Se-pyrite was found to be ca. 0.6 V, although the initial potential for selenium release was as low as around the open circuit potential. The selenium reduction current distribution was achieved by SECM imaging suggesting an inhomogeneous adsorption of selenium on pyrite. Because of the change of surface species, the immobilization of selenium resulted in a decrease of surface conductivity of pyrite, which was analyzed using SECM tip approach curves and conductive atomic force microscopy. The surface conductivity followed the trend of pyrite > electrodeposited Se-pyrite > adsorbed Se-pyrite. This work provides a new approach for the in situ investigation of selenium immobilization on and release from mineral surfaces (e.g., pyrite), which can be readily applied to similar systems regarding various environmental issues.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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".