Experimental measurements and thermodynamic modeling of dissociation pressure of CO2 hydrate in sulfate solutions
Bibliographic record
Abstract
• We report new data on dissociation pressure of CO 2 hydrate in sulfate solutions. • Sulfate solutions exhibit thermodynamic inhibition effects on CO 2 hydrate. • CuSO 4 solutions show slight inhibition effects on CO 2 hydrate. • The predicted dissociation pressure agrees reasonably well with the measured data. • The dissociation enthalpies depend on temperature and sulfate salt concentration. Carbon capture and storage (CCS) has been a popular strategy to mitigate climate change and has attracted significant attention from both industry and academia. CO 2 can be stored in the form of CO 2 hydrate in deeper locations in an ocean, which makes it a potential option for CO 2 sequestration. Dissolved salts in the ocean brine can significantly affect the dissociation pressure of CO 2 hydrate. Sulfate salts are one of the most common salt species in the oceanic brine. Although various experimental studies have been conducted to investigate the phase behavior of CO 2 hydrate in brine, few studies focus on the effect of sulfate salts on the dissociation pressure of CO 2 hydrate. In this study, we build an in-house experimental setup to investigate the effect of monovalent and divalent sulfate salts on the dissociation pressure of CO 2 hydrate. The dissociation pressure of CO 2 hydrate in Na 2 SO 4 , K 2 SO 4 , MgSO 4 , and CuSO 4 aqueous solutions is measured using the isochoric pressure search method at different concentrations over the temperature range of 274.36 – 282.15 K and the pressure range of 1.50 – 4.03 MPa. A hybrid methodology incorporating the Soave-Redlich-Kwong Equation of State (SRK EOS), the van der Waals-Platteeuw (vdW-P) model, and the Pitzer model is applied to predict the dissociation pressure of CO 2 in sulfate solutions. In addition, the dissociation enthalpies of CO 2 hydrate in these sulfate solutions are calculated using the Clausius-Clapeyron equation based on the measured dissociation points. The experimental results show that the dissociation pressure of CO 2 hydrate in Na 2 SO 4 , K 2 SO 4 , and MgSO 4 solutions is higher than that in pure water, and the dissociation pressure of CO 2 hydrate in sulfate solutions increases with an increasing salt concentration. Conversely, CuSO 4 barely affects the dissociation pressure of CO 2 hydrate, which is mainly attributed to the lower molar concentration of the ions compared with the other salt solutions and the ion specificity of Cu 2+ . The prediction results are in alignment with the experimental data measured in this study, which proves the feasibility of the thermodynamic model in predicting the dissociation pressure of CO 2 hydrate in sulfate solutions. Additionally, the calculated dissociation enthalpies of CO 2 hydrate show a dependence on both temperature and salt concentration. It is also revealed that Cu 2+ exhibits ion specificity in affecting the dissociation enthalpy of CO 2 hydrate, likely due to its more distinct ability to impact the cage occupancy of CO 2 hydrate than the other ions. These findings enhance our understanding of the impact of sulfate salts on the dissociation behavior of CO 2 hydrate and offer valuable insights for CO 2 sequestration.
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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) | 0.000 | 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 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".