Probing Surface Interactions of Electrochemically Active Galena Mineral Surface Using Atomic Force Microscopy
Bibliographic record
Abstract
Colloidal stability governed by various surface interactions finds wide application in many engineering processes, such as mineral froth flotation. In this work, electrochemical atomic force microscopy (EC-AFM) was employed to modulate the interfacial chemical reaction and simultaneously probe the evolution of surface characteristics (i.e., morphological changes and surface interactions) of electrochemically active galena mineral surface at the nanoscale. Successive potentials (i.e., −0.7, −0.3, 0, 0.1, 0.2, 0.3, and 0.45 V), referred to the Ag/AgCl/3.4 M KCl reference electrode (0.206 V vs standard hydrogen electrode), were respectively held for 20 s on the galena surface. The in-situ topographic imaging demonstrates homogeneous electrochemical oxidation across the mineral surface, leading to slight surface roughening at the potential of 0 V and more pronounced surface roughening at higher potentials (e.g., 0.3 and 0.45 V). The direct force measurements with an octadecyltrichlorosilane (OTS)-functionalized AFM tip show that the magnitude of attractive hydrophobic interaction increased with increasing the applied potential from −0.7 to 0.45 V due to the enhanced surface hydrophobicity, which agrees well with contact angle measurements. Fitted with the extended Derjaguin–Landau–Verwey–Overbeek (DLVO) theory by including the effect of hydrophobic interaction, the decay length of hydrophobic interaction was found to rise from 0.8 to 1.3 nm with increasing the applied potential from −0.7 to 0.45 V. The electrochemical oxidation at 0 V is believed to be the formation of metal-deficient lead sulfide, while the oxidation at 0.45 V arises from the formation of elemental sulfur that is further confirmed by cryo-XPS. The results provide insights into the basic understanding of the interfacial properties and surface interaction mechanisms on electrochemically polarized mineral surface at nanoscale, and the methodology can be extended to many other interfacial electrochemical processes.
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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".