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 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 | 0.006 | 0.002 |
| Meta-epidemiology (narrow) | 0.005 | 0.005 |
| Meta-epidemiology (broad) | 0.005 | 0.002 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.003 | 0.001 |
| Scholarly communication | 0.002 | 0.004 |
| Open science | 0.004 | 0.001 |
| Research integrity | 0.003 | 0.006 |
| 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; both teacher heads agree on what is shown here.
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".