Acoustic Cavitation-Assisted Ag/Fe Bimetallic Nanoparticle-Based Integrated Heterocatalytic System Synergistically Promotes Rapid Degradation of Polybrominated Diphenyl Ethers
Bibliographic record
Abstract
Polybrominated diphenyl ethers (PBDEs), widely used brominated flame retardants, have been classified as a new persistent organic pollutant by the Stockholm Convention. Among them, decabrominated diphenyl ether (BDE-209) exhibits strong oxidative resistance due to its symmetrical structure, making its oxidative degradation challenging. An acoustic cavitation (AC)-assisted bimetallic nanoparticle (BMNP)-based integrated heterocatalytic system (AC/BMNP) was explored for achieving the rapid degradation of BDE-209, the highest congener of PBDEs, a group of persistent organic pollutants. The BMNP catalyst comprises Ag–Fe nanoparticles uniformly dispersed and stabilized within a ferroso-ferric oxide framework (Fe 0 @Ag 0 /FeFe 2 O 4 ), exhibiting an urchin-like structure. The AC/BMNP system facilitated rapid degradation of BDE-209 within 15 min, significantly outperforming only AC (∼14%) or BMNP catalyst (∼34% in 6 h) alone. Supported by the experimental and computational analyses, this breakthrough degradation efficiency was attributed to the synergistic interactions between AC and BMNP that promoted in situ generation of H 2 O 2 in the mM range through a dual-catalytic pathway involving the recombination of *OH and hydrogenation of *OOH species on the catalyst surface, thereby eliminating the need for any external oxidants. To the best of our knowledge, this represents the first instance of achieving such rapid degradation of BDE-209 without adding any oxidant, which is at least ∼2 × 10 2 -fold faster than previously reported methods (48 h). A three-phase degradation mechanism of PBDEs is proposed based on (1) reductive debromination by metallic nanoparticles, (2) hydrodynamic effect and transient cavitation hot-spot model, and (3) sono-oscillation of the Fe 2+ /Fe 3+ system, and the charging–discharging of Ag nanoparticles. Identified degradation byproducts indicated that BDE-209 degradation involved both sequential reductive debromination of higher congeners and oxidative degradation of lower congeners, ultimately leading to the ring-opening of PBDEs. The in situ oxidant generation ability of the integrated system makes it a promising tool for the effective removal of emerging pollutants and advancement of next-generation remediation technologies.
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How this classification was reachedexpand
Full frame distilled prediction
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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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) | 0.000 | 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 teacher head, 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".