Fate of persulfate in uncontaminated aquifer materials
Bibliographic record
Abstract
Well-characterized materials from seven sites across North America were used in a series of bench-scale studies to estimate persulfate decomposition kinetic parameters and to quantify the impact on aquifer material properties. The batch experiments were conducted in an experimental system containing 100 g of solids and 100 mL of persulfate solution at 1 g/L or 20 g/L. Column experiments, more representative of in situ conditions with respect to oxidant to aquifer solids mass ratio, were performed in a stop-flow-mode using a 1 g/L persulfate solution. Results from the bench-scale experiments indicated that the decomposition of persulfate followed a first-order rate law for all the aquifer materials we investigated. An order of magnitude decrease in decomposition rate coefficients were observed for systems that used a persulfate concentration of 20 g/L, compared to those that used 1 g/L. As expected, the column experiments yielded higher reaction rate coefficients than batch tests for the same persulfate concentration, due to the higher oxidant to solids mass ratio and increased contact area. At the pilot-scale, a series of push-pull tests was performed to quantify persulfate stability. The push-pull tests involved the injection of persulfate (1 or 20 g/L) and a conservative tracer into a hydraulically isolated portion of the sandy aquifer at CFB Borden, Canada, followed by the slow extraction of groundwater for ∼20 days. Analyses of the conservative tracer and persulfate concentrations yielded in situ persulfate decomposition rates which were ∼40 times higher than those estimated from the bench-scale tests. Overall, the estimated rate coefficients indicate that persulfate is persistent and hence a suitable oxidant for the range of aquifer materials explored in this study. The findings from this multi-scale investigation were used to develop persulfate decomposition rate scale-up factors so that robust and cost-effective bench-scale techniques can be used to estimate in situ persulfate degradation rates.
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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 | 0.000 | 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 | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".