KINETICS OF PHOSPHATE-INDUCED DESORPTION OF ARSENATE ADSORBED ON CRYSTALLINE AND AMORPHOUS ALUMINUM HYDROXIDES
Bibliographic record
Abstract
Research on arsenate adsorption by Al hydroxides is common; however, relatively little is known on the kinetics of arsenate desorption from these Al hydroxides. The batch method was used to compare the phosphate-induced desorption kinetics of preadsorbed arsenate from the crystalline and amorphous Al(OH)3 at pH 5.0, background electrolyte of 0.01 M NaNO3 at 298 and 318 K. The results showed that both the amount of arsenate adsorbed by the amorphous Al(OH)3 and the mole fraction of arsenate remaining adsorbed on the amorphous Al(OH)3 after desorption were substantially greater than those in the crystalline Al(OH)3 system. The second-order rate equation was chosen to compare the rates of arsenate desorption. The rate constant of arsenate desorption from the crystalline Al(OH)3 was 3.8 to 15.5 times greater than that from the amorphous Al(OH)3 in the reaction period, suggesting that, compared with the crystalline Al(OH)3, the arsenate adsorbed on the amorphous Al(OH)3 was much more difficult to be desorbed by phosphate. The rate constant of arsenate desorption increased with the increase of phosphate concentration from 0.1 to 1.0 mM and the increasing temperature. Although the activation energy for arsenate desorption from the crystalline Al(OH)3 in the fast reaction was greater than that from the amorphous Al(OH)3, the much greater frequency factor for the desorption from the former resulted in a higher desorption rate of arsenate from the crystalline Al(OH)3. This information is of fundamental significance in understanding the dynamics of remobilization and fate of arsenate in soil and related environments.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| 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 source (direct Gemma or distilled Codex), 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".