Molecular dynamics simulation and in-situ MRI observation of organic exclusion during CO2 hydrate growth

Highlights: • Organic exclusions with hydrate growth were firstly simulated and in-situ observed. • Progressive organic exclusion caused substance migration and concentration gradient. • Higher driving formation force generated the precipitation of excluded organics. Inorganic substances and most organic compounds are typically excluded from crystalline hydrate structures. In this study, the phenomenon and mechanism of organic exclusions during hydrate formation were investigated using MD simulations and in-situ observations with an MRI experimental apparatus. The results showed that the organic macromolecules could not be trapped in the hydrate structure and formed a concentration gradient of dissolved organic substances from the growth front of the CO₂ hydrate into the aqueous solution. This study demonstrates the hydrate-based technology would be a promising method for organic wastewater treatment.