Phosphate and <i>myo</i>-Inositol Hexakisphosphate Adsorption onto Hematite as Affected by Ca<sup>2+</sup>, Mg<sup>2+</sup>, and pH
Bibliographic record
Abstract
myo -Inositol hexakisphosphate (IHP 6 ) is typically the most abundant form of organic phosphorus (P o ) in soils, and this species is highly reactive with Al and Fe (hydr)oxides because of the six phosphoryl groups in its structure. In this study, the effects of pH (4.5–6.5) and cations (Ca 2+ and Mg 2+ ) were investigated using in situ attenuated total reflectance Fourier transform infrared (ATR–FTIR) spectroscopy and Mg K -edge X-ray absorption spectroscopy (XAS). IHP 6 has more complex infrared (IR) spectra than inorganic phosphate, even though both share certain bands of absorbances. Ca and Mg influenced the IHP 6 adsorption process on the hematite surface, but this effect was less evident for phosphate. The variation in pH promoted a shift of several bands in the adsorbed IR spectra. As for adsorption kinetics, IHP 6 was sensitive to a pH change from 4.5 to 6.5, with a reduction in the adsorption rate at the highest pH. Phosphate, on the other hand, presented more rapid adsorption kinetics than IHP 6, with equilibrium reached in ∼80 min. Two adsorption mechanisms were identified for IHP 6 and phosphate kinetics, without the influence of the studied cations. However, differences in the shape of XAS spectra at the Mg K -edge revealed that there was a probable change in the atomic environment of Mg 2+ caused by its association with phosphate. In other evaluated organic molecules, such as IHP 6 and citrate, this effect was not observed as a result of the intense presence of MgCl 2 in the linear combination fitting (LCF) analysis. In general, the results enhance the molecular-level understanding of oxyanion adsorption onto hematite surfaces that can predict IHP 6 and phosphate behaviors in iron-oxide-rich soils.
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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) | 0.001 | 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 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".