Carbon Dots Combined with Zwitterionic/Nonionic Surfactants for Stabilizing Carbon Dioxide Micronanobubbles under...

Area of Science:

• Materials Science and Engineering
• Chemical Engineering
• Environmental Science

Background:

• Carbon dioxide micronanobubbles (CO2 MNBs) are crucial for carbon capture, utilization, and storage (CCUS) but destabilize in high-salinity conditions.
• Coalescence and aging limit the efficiency of CO2 MNBs in saline environments, hindering their practical application.

Purpose of the Study:

• To develop a strategy for stabilizing CO2 MNBs in high-salinity fluids.
• To investigate the synergistic effects of carbon dots (CDs) and surfactants on CO2 MNB interfacial properties and stability.

Main Methods:

• A composite system of carbon dots (CDs) and zwitterionic/nonionic surfactants was employed to stabilize CO2 MNBs.
• Interfacial tension measurements and a semiquantitative adsorption model were used to characterize the gas-liquid interface.
• Bubble size stability was assessed in high-salinity solutions, including those enriched with Ca2+.

Main Results:

• Synergistic adsorption at the gas-liquid interface significantly reduced minimum surface tension from 21.54 to 10.71 mN·m−1.
• The composite interfacial layer effectively suppressed gas diffusion and Ostwald ripening, enhancing CO2 MNB size stability.
• In high-salinity conditions with Ca2+, CDs provided interfacial charge buffering, maintaining bubble diameters below 600 nm for 24 hours.

Conclusions:

• Carbon dots play a key role in stabilizing CO2 MNBs through interfacial regulation, particularly in saline environments.
• The developed strategy offers a mechanism for creating low-cost, salt-tolerant CO2 microbubble fluid systems for enhanced oil recovery and CCUS.