Diffusive phosphate transport in Al-rich acidic porous cation exchange system
Bibliographic record
Abstract
One-dimensional diffusive phosphate transport in a porous cation-exchange resin model system was investigated to examine the effect of exchangeable Al on the movement of phosphate. This study presumes that Al interacts with phosphate and H + is produced as a result of deprotonation of H 2 PO 4 − . The production of H + due to interactions between positively charged Al ions and phosphate ions was confirmed by measuring the pH change during the titration of phosphate by aluminum or aluminum by phosphate ions. A set of cylindrical wax columns packed with: (A) a mixture of sand and solid Al 2 O 3 , (B) a mixture of sand and Al 3+ -saturated cation-exchange resin, (C) a mixture of sand, solid Al 2 O 3 , and Al 3+ -saturated cation-exchange resin, and (D) sand as a control was used. A 0.2-g sample of 32 P-KH 2 PO 4 was applied on the surface of the mixture in each column simulating one-dimensional diffusion from an instantaneous planar source into a semi-finite system. Retardation of phosphate transport by exchangeable Al 3+ was characterized by lowering of pH. Phosphate transport was not retarded in the presence of solid Al 2 O 3 alone. Phosphate movement was further retarded in the presence of exchangeable Al 3+ with solid Al 2 O 3 . Under this situation, H + ion produced from precipitation reactions dissolved solid Al 2 O 3 , giving rise to more Al 3+ in solution. Aluminum ion in the solution phase moved towards the site where phosphate was precipitated. From a mass balance of P, a slight amount of P was not recovered in the system whose pH was kept around 2.0 or below, indicating a probable formation of K-taranakite. Either K-taranakite or K 2 Al 5 H 7 (PO 4 ) 8 −14 H 2 O was identified as a final precipitation product from a series of titration experiments. However, at least two unidentified morphologically different amorphous aluminum phosphates were observed. Key words: Aluminum, cation-exchange, phosphate, precipitation, retardation, transport
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 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".