Asphaltenes Adsorption onto Metal Oxide Nanoparticles: A Critical Evaluation of Measurement Techniques
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Bibliographic record
Abstract
The adsorption of asphaltenes onto nanoparticles (NPs) has received a lot of attention in recent years. However, the effect of the measurement technique on the adsorption isotherms has never been addressed. In this paper, the adsorption of n -heptane-precipitated asphaltenes, C7-asphaltenes, from toluene model solutions onto three metal oxide NPs, namely Fe 2 O 3, Fe 3 O 4, and Al 2 O 3, was studied. Asphaltenes uptake calculated from UV–vis spectroscopy at three different wavelengths were compared with thermogravimetric analysis (TGA) results. Although the adsorption trends followed Langmuir isotherms, instrument as well as wavelength-dependent coefficients were obtained. We believe TGA results are more reliable, provided complete oxidation and account of mass loss due to NPs is attained. UV–vis measurements may be impacted by the chemical structure of the asphaltenes sub fractions as well as their state of association. Al 2 O 3 showed the highest adsorption capacity of 385 ± 5 mg/g, followed by Fe 3 O 4 and Fe 2 O 3 . However, based on mg/m 2, Fe 2 O 3 displayed the highest adsorption capacity. TGA analysis revealed that the NPs promoted the oxidation of adsorbed asphaltenes in a reverse order to their adsorption capacity, q max (mg/g) (Al 2 O 3 > Fe 2 O 3 ≈ Fe 3 O 4 ). This trend is in line with our previous observation of mass-dependent thermo-oxidative profile and surface exposure role, rather than a catalyst role, of the NPs. Lastly, the C7-asphaltenes from this study were characterized, and their structural parameters were compared to 45 asphaltenes from the literature. The size and structural parameters of the asphaltenes clusters are in good agreement with the literature values.
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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 | 0.000 |
| 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 it