Stabilization of Carbon Dioxide Foam by a Low Concentration of Cetyltrimethylammonium Bromide-Grafted Nano-Faujasite Zeolite. Part 1: Experimental Study
Bibliographic record
Abstract
In this work, we are introducing an innovative technique to enhance the CO 2 foam stability by using a nanofoam stabilizer that reduces the surfactant concentrations below the critical micelle concentration (CMC). The core structure of our foam stabilizer consists of faujasite zeolite nanoparticles (FAU) that are grafted with cationic surfactant, cetyltrimethylammonium bromide (CTAB). The prepared nanomaterials were fully characterized by an array of characterization techniques to gain insight into their surface properties and stability. Then, the foamability and foam stabilization properties of the CTAB, compared with the physically mixed CTAB and neat FAU nanoparticles, and CTAB-grafted FAU nanoparticle systems were evaluated at various surfactant concentrations based on initial foam volume, half-life, liquid holdup, surface shear viscosity, and bubble sizes. Furthermore, the CO 2 foam stabilization mechanisms of all foaming agents were investigated by the dilational surface tension. Our results indicated that the CTAB-grafted FAU nanoparticles were able to stabilize the liquid films of CO 2 foam at low surfactant concentrations via surfactant coverage on the surface of nanoparticles, which optimized the viscoelastic and surface tension properties of CO 2 foam. In fact, below the CMC of CTAB (∼335 ppm), the initial foam volume and half-life remained constant after the addition of the FAU nanoparticles, whereas the foam properties were highly enhanced above the CMC (350–3000 ppm). Our foam stabilization results showed that the optimum stable CO 2 foam was generated by CTAB-grafted FAU nanoparticles at a concentration of 1000 ppm (∼500 ppm grafted CTAB), which had a half-life of 773 s, in contrast to the other systems that had a half-life of less than 350 s at 500 ppm CTAB concentration. The surface tension results showed that grafting 50 and 100 ppm CTAB on FAU nanoparticles resulted in 60.20 and 51.52 mN/m initial dynamic surface tension measurements, whereas the virgin CTAB solutions at the same surfactant concentrations had initial dynamic surface tensions of 69.78 and 60.44 mN/m, respectively. On the other hand, at a surfactant concentration of 50 ppm (100 ppm CTAB-FAU nanoparticles), the viscoelastic modulus was almost identical to the viscoelastic modulus measurement at the CMC of CTAB. Interestingly, the CTAB-grafted FAU nanoparticles, compared with the other systems, had almost 1.5–4 times higher liquid holdup and formed smaller and homogeneous bubble sizes during the first 360 s. Hence, the CTAB-grafted FAU nanoparticles could retard the foam destabilization mechanisms, including foam bubble coalescence and ripening effects, due to their ability to maximize the viscoelastic modulus and reduce the surface tension at these low surfactant concentrations. Our findings can provide an economical solution for implementing conventional CO 2 foams in enhanced oil recovery (EOR) applications while hindering the agglomeration of nanoparticles.
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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".