Mechanisms of separation between tetrahydrofuran and water using hydroxystearic acid
Bibliographic record
Abstract
Tetrahydrofuran (THF) is fully miscible in water, and it interacts with it via hydrogen (H) bonds. We discover that the fatty acid hydroxystearic acid (HSA) separates THF from water because it preferentially H-bonds water and increases the proportion of single H-bond donors (SD) relative to double H-bond donors (DD). This change in the coordination of water molecules from DD to SD leads to phase separation between THF and water. We previously established this separation mechanism using sugars and surfactants and other water miscible solvents. Here, we use attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) to prove that this mechanism is also responsible for THF–water separation using HSA, thereby demonstrating the universality of the proposed separation mechanism. Using synchrotron small-angle x-ray scattering, we show how HSA self-assembles into reverse micelles in THF–water mixtures and determine their persistence length and periodicity using a modified Landau model. Reverse micelles host water in their interior and swell upon increasing the water content, as shown by light scattering. They then turn into droplets detectable using optical or confocal microscopy. When THF–water emulsions separate, they yield water-rich and THF-rich free phases. ATR-FTIR reveals that the top phase of THF–water mixtures separated by HSA is THF-rich. Moreover, when Cu2+ ions are in solution, HSA causes their migration into the THF-rich phase, enabling the simultaneous separation of THF and Cu2+ cations from water. This study demonstrates the potential for engineering the water structure to aid in the separation of water-miscible solvents from water with important implications for water treatment.
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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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".