Accelerated carbon dioxide mineralization and polymorphic control facilitated by nonthermal plasma bubbles

Area of Science:

• Plasma Science and Engineering
• Materials Science
• Environmental Engineering

Background:

• Carbon dioxide (CO2) mineralization is crucial for net-negative carbon technologies, mimicking natural carbon cycles for atmospheric CO2 removal and sequestration.
• Plasma-liquid interactions (PLI) offer a novel approach to influence chemical processes, including CO2 capture and conversion.
• Controlling the nucleation and growth kinetics of calcium carbonate (CaCO3) is key to efficient CO2 sequestration.

Purpose of the Study:

• To investigate the impact of electron temperature in nonthermal CO2 plasmas on plasma-liquid interactions.
• To understand how modifying plasma discharge parameters influences the formation of calcium carbonate (CaCO3) phases.
• To explore the potential of PLI for engineering net-negative carbon sequestration technologies.

Main Methods:

• Utilized nonthermal CO2 plasmas with varying electron temperatures by adjusting the Ar mole fraction.
• Investigated plasma-liquid interactions to study the nucleation and growth kinetics of CaCO3.
• Analyzed CO2 capture, mineralization yields, and phase selectivity (vaterite vs. calcite).

Main Results:

• Optimized plasma discharge parameters enabled the formation of pure vaterite CaCO3, bypassing the more stable calcite phase.
• Increasing electron temperature significantly enhanced CO2 capture, nucleation rate, and CaCO3 yields, with nearly tenfold increase in CO2 conversion.
• Optimal selectivity toward CaCO3 was observed at electron energies of approximately 1 eV, despite increased CO formation at higher energies.

Conclusions:

• Plasma-liquid interactions, driven by gas-phase vibrational excitation and plasma-activated water splitting, accelerate CO2 mineralization.
• The rate-determining step involves the formation of bicarbonate ions (HCO3-) from plasma-generated reactive species.
• This research demonstrates accelerated mineralization kinetics and polymorphic control, relevant for developing solid-form carbon sequestration technologies.