Visible-NIR absorption spectroscopy study of the formation of ternary plutonyl(<scp>vi</scp>) carbonate complexes
Bibliographic record
Abstract
We present the first experimental evidence for the ternary complexation of calcium and magnesium ions with plutonyl(vi)tricarbonate species in carbonate-containing aqueous solutions using visible-NIR spectrophotometric titration. Prior to studying the ternary plutonyl(vi) carbonate complexation, visible-NIR absorption spectral information of PuO2(CO3)22- and PuO2(CO3)34- was successfully obtained. PuO2(CO3)22- has a prominent peak at 853 nm and its molar absorptivity was determined to be ε853, PuO2(CO3)22- = 49.0 ± 4.2 M-1·cm-1. The spectrophotometric titration results by adding calcium or magnesium to the plutonyl(vi) carbonate system consisting of PuO2(CO3)22- and PuO2(CO3)34- indicate the formation of CaPuO2(CO3)32- and MgPuO2(CO3)32- complexes and provide the formation constants at 0.1 M H/NaClO4 for MPuO2(CO3)32- from PuO2(CO3)34-, log K = 4.33 ± 0.50 and 2.58 ± 0.18 for M = Ca2+ and Mg2+, respectively. In addition, the formation constants of CaPuO2(CO3)32- and MgPuO2(CO3)32- from PuO2(CO3)34- at infinite dilution (log K°) were proposed to be 6.05 ± 0.50 and 4.29 ± 0.18, respectively, based on the correction of ionic strength using the Davies equation. The absorption spectrum of the ternary plutonyl(vi) complexes of CaPuO2(CO3)32- is similar to that of PuO2(CO3)34- with the exception of a characteristic absorption peak at 808 nm (ε808, CaPuO2(CO3)32- = 42.9 ± 1.6 M-1·cm-1). According to the calculated aqueous plutonyl(vi) speciation including the ternary plutonyl(vi) complexes, CaPuO2(CO3)32- is considered the dominant Pu(vi) species under environmental conditions, and plutonyl(vi) may be more mobile than expected in previous assessments.
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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 | 0.000 |
| 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".