Pb²⁺ removal based on the confinement effect in polygonal carbon nanotubes: a molecular dynamics simulation

Area of Science:

• Environmental Science
• Materials Science
• Computational Chemistry

Background:

• Heavy metal lead (Pb²⁺) pollution poses a significant global threat to public health and ecosystems.
• Effective treatment methods for trace Pb²⁺ in water are crucial for environmental protection.

Purpose of the Study:

• To investigate the transport behavior of Pb²⁺ using polygonal carbon nanotubes (PCNTs)/graphene composites.
• To explore the mechanisms of Pb²⁺ transportation influenced by PCNT structure and chemical modification.

Main Methods:

• Employed molecular dynamics simulations combined with Density Functional Theory (DFT) calculations.
• Studied Pb²⁺ transport through various PCNT/graphene composite channels (PCNT: P = 4, 5, 6, 8).
• Analyzed the role of hydrogen-bonding networks and fluorine modification on ion transport.

Main Results:

• PCNTs facilitate H₂O and H₃O⁺ transport via proton exchange, forming hydrogen-bonding networks.
• The 8-channel (8N) showed enhanced Pb²⁺ passage probability due to the hydrogen-bonding network.
• Fluorine modification of PCNTs (8F) further influenced Pb²⁺ transport through combined hydrogen bonding and electrophilic attraction.
• 8CNT/G composites were less effective for Pb²⁺ interception compared to smaller PCNTs.
• Affinity from hydrogen bonding and PCNT walls significantly impacts particle transport, as indicated by RDF and HOMO-LUMO analyses.

Conclusions:

• This study provides insights into Pb²⁺ diffusion mechanisms within PCNTs.
• Findings can guide the development of strategies for mitigating Pb²⁺ pollution in aquatic environments.
• PCNTs and their modifications offer a promising avenue for heavy metal remediation technologies.