Insertion of acetone molecules in the nanostructured tunnels of palygorskite
Bibliographic record
Abstract
The insertion of acetone molecules in the nanostructured tunnels of palygorskite (PFl-1) was studied by thermal gravimetric analysis connected with mass spectrometry and 29Si and 13C solid-state NMR techniques. In comparison with palygorskite, new weight losses appear at 130 and 340 °C for palygorskite previously heated at 150 °C for 20 h then exposed to acetone for a week. Two types of water molecules occupy the palygorskite tunnels: weakly bound zeolitic water and structural water molecules coordinated to Mg(II) cations at the edge of the octahedral sheets. Acetone molecules that intercalate in the nanostructured tunnels replace the zeolitic water and are H-bonded to structural water. The mass loss at 130 °C is accounted for by the release of structural water and acetone. The loss at 340 °C is due to the release of acetone molecules that coordinate directly to terminal cations in the nanostructured tunnels and to residual structural water. A nanostructured hybrid material, with a structure similar to the parent palygorskite, can be formed through the direct coordination of acetone molecules to the terminal cationic coordination sites in the nanostructured tunnels of palygorskite. There is evidence for the fixation of two different types of acetone on palygorskite: mobile acetone molecules on the external surface and acetone molecules more rigidly fixed inside the nanotunnels. The former ones are detected by the 13C magic-angle spinning NMR experiment and can be easily removed by gentle heating at 60 °C, while the latter ones are detected by 13C cross-polarization magic-angle spinning NMR. It is also demonstrated that nearly complete recovery of the original structure is achieved by exposing palygorskite previously dehydrated at 150 or 300 °C to acetone vapor at room temperature. Key words: insertion, intercalation, nanostructured tunnels, palygorskite, acetone, nanocomposite materials, nanohybrid.
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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".