Converting Nanoflower-like Layered Double Hydroxides into Solvent-Free Nanofluids for CO₂ Capture

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Layered double hydroxides (LDHs) offer versatility but suffer from nanosheet agglomeration, hindering applications.
• Existing LDHs have stacked structures limiting hydroxyl group exposure, crucial for conversion to solvent-free nanofluids (SFNs).

Purpose of the Study:

• To prepare nanoflower-like LDHs (NFLs) with exposed hydroxyl groups for solid-to-liquid transition into SFNs.
• To investigate the formation mechanisms of NFLs and organic oligomer grafting.
• To evaluate the CO2 capture, separation, and stability performance of the resulting NFL-based SFNs.

Main Methods:

• Synthesis of nanoflower-like layered double hydroxides (NFLs).
• Grafting of organic oligomers (OS-PEA) onto NFL surfaces.
• Characterization of NFL formation and grafting mechanisms.
• Evaluation of fluid dispersion stability, viscosity, CO2 sorption, and CO2/N2 separation.

Main Results:

• Successfully prepared NFLs with abundant exposed hydroxyl groups, enabling solid-to-liquid transition.
• Demonstrated good fluidity and dispersion stability of the NFL-based SFN (NFL-F3) in various solvents for over 100 days.
• Achieved significantly improved CO2 sorption capacity attributed to physical sorption, voids, and good fluidity from high grafting density.
• Confirmed dominant physical effect in CO2 sorption, facilitating energy-efficient sorption-desorption.
• Showcased good CO2/N2 separation performance and cycle stability.

Conclusions:

• A novel strategy for creating low-viscosity, LDH-based SFNs with high CO2 capacity and selectivity was developed.
• The NFL-SFNs offer a promising, energy-efficient solution for CO2 capture and separation.
• This approach opens new avenues for LDH utilization in advanced material applications.