Phase Transition of FeSO<sub>4</sub>·7H<sub>2</sub>O to FeSO<sub>4</sub>·H<sub>2</sub>O in the H<sub>2</sub>SO<sub>4</sub>–HCl–H<sub>2</sub>O System by Modeling Solubility
Bibliographic record
Abstract
A new sustainable process was developed to recycle FeSO 4 ·7H 2 O produced from the sulfate process for titanium dioxide production. In this process, FeSO 4 ·H 2 O was crystallized out from a subsequent cooling crystallization operation rather than FeSO 4 ·7H 2 O. In order to better develop the new process and provide a theoretical basis for ferrous sulfate dehydration, the study of the phase equilibrium of the FeSO 4 –H 2 SO 4 –HCl–H 2 O system is necessary. For this purpose, the solubility of FeSO 4 ·7H 2 O in the H 2 SO 4 –HCl–H 2 O system was determined at a temperature range from 278.15 to 313.15 K using a dynamic method. By raising temperature and the concentration of HCl, more FeSO 4 ·7H 2 O can be dissolved in this system. However, with the addition of H 2 SO 4, the solubility of FeSO 4 ·7H 2 O is found to decrease due to common-ion effect. A speciation-based model equipped with middle-range parameters was established by regressing the experimental and reported solubility of FeSO 4 ·7H 2 O under varying conditions. The phase transition temperature of FeSO 4 ·7H 2 O to FeSO 4 ·H 2 O was successfully predicted by the new model, which was found to decrease with increasing concentration of both H 2 SO 4 and HCl.
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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) | 0.000 | 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 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".