Surface Charge at the Bitumen/Water Interface Investigated by Phase-Sensitive Sum Frequency Generation Vibrational Spectroscopy: Effects of pH, Ions, and Surfactants
Bibliographic record
Abstract
The structure of water at bitumen/water interfaces was studied using phase-sensitive sum frequency generation (SFG) vibrational spectroscopy. The sign of the SFG spectra indicated that the surface of bitumen has a negative net charge. An ordered water structure was observed on the bitumen surface, and the ordering was enhanced at the industry-relevant pH value of 9. The presence of salt in the water neutralized the surface charge of bitumen and nearly destroyed the ordered water structure with a concentration of ∼100 mM. It was found that Ca 2+ was more effective than Na + in screening the surface charge of bitumen. Both the anionic surfactant sodium dodecyl sulfate (SDS) and the cationic surfactant dodecyl trimethylammonium chloride (DTAC) interacted with the bitumen. While the anionic surfactant slightly increased the negative charge of the bitumen surface, the cationic surfactant produced a surface charge reversal, indicated by the sign change of the SFG spectrum.
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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 | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".