Metal Organic Frameworks as Dual Functional Adsorbent/Catalysts for Plasma Air Purification Systems
Bibliographic record
Abstract
Indoor air pollution is responsible for the annual premature death of millions of people worldwide. Volatile organic compounds (VOCs) are among these pollutants with proven detrimental effects on occupants’ health. Plasma-based methods’ capabilities for VOCs degradation have motivated designers to employ these methods for purifying indoor air environment. It has been demonstrated that utilizing a dual functional adsorbent/catalyst (DFA/C) in a plasma system can significantly enhance the VOCs removal and the system’s energy efficiency. However, selecting an appropriate DFA/C has remained a challenge. \nFor the first time, this research attempted to utilize metal organic frameworks (MOFs) as DFA/Cs for a plasma-driven catalytic reactor. Accordingly, three different MOFs, MIL-101 (MIL: Material Institute Lavoisier), MIL-53, and CPM-5 (CPM: Crystalline Porous Material-5) were synthesized through microwave and solvothermal methods. Furthermore, for the first time, a mechanochemical method was developed to synthesize CPM-5. To test the performance of the developed MOFs, a non-thermal plasma dielectric barrier discharge (DBD) system was designed, set-up and calibrated. Several adsorption and oxidation experiments were performed to study the physical and chemical behaviors of these MOFs for the removal of toluene and isobutanol. Also, the effect of the presence of humidity on the adsorption/oxidation capacities of MOFs was investigated. \nFurther analyses were carried out to study the surface characteristic of the developed MOFs using X-ray diffraction (XRD), scanning electron microscopy (SEM), BET surface area analysis, and thermogravimetric analysis (TGA). The results for microwave-synthesized MIL-53 and CPM-5 and also solvothermal-synthesized MIL-101 showed a good crystallinity, very high specific surface area (SLangmuir: 1275-3747 m2/g), and acceptable thermal stability. In the case of mechanochemical-synthesized CPM-5, the TGA analysis showed a similar thermal stability compared to the microwave-synthesized CPM-5. However, the SEM micrographs showed a formation of different morphology of crystallites. Also, the surface area of the mechanochemical-synthesized CPM-5 was lower than the one synthesized by the microwave method. \nThe adsorption isotherms of toluene and isobutanol demonstrated the physisorption of these MOFs. This result was also confirmed by TGA characterization of samples before and after toluene adsorption. In addition, oxidation evaluation studies exhibited VOCs removal potential over these MOFs. MIL-101 and MIL-53 exhibited superior adsorption and oxidation ability than CPM-5 in most cases. Results also showed higher adsorption capacity of MIL-101 than MIL-53 in dry conditions but almost the same oxidation efficiency. Nevertheless, adsorption/oxidation capacities of MIL-53 surpassed MIL-101 in the presence of 30% relative humidity. Moreover, Fourier transform infrared spectroscopy (FTIR) showed the stable structure of the examined MOFs after plasma-catalytic reactions, which indicated they were easy to be regenerated. \nDuring the course of plasma-catalytic oxidation of toluene and isobutanol, different organic by-products and ozone were detected. Results showed utilization of a MOF as catalyst in the plasma system can reduce the downstream ozone concentration. Moreover, the presence of humidity suppressed the amount of ozone generation. \nIn conclusion, results demonstrated the potential capacity of MIL-53 and MIL-101 as DFA/Cs in plasma-catalyst air purification system.
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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 | 0.001 | 0.000 |
| Research integrity | 0.001 | 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".