A mesoporous cationic thorium-organic framework that rapidly traps anionic persistent organic pollutants

Area of Science:

• Materials Science
• Environmental Chemistry
• Nanotechnology

Background:

• Anionic environmental pollutants are mobile in water systems.
• Cationic framework materials for capturing these pollutants are scarce.
• Persistent organic pollutants like perfluorooctane sulfonate (PFOS) pose significant environmental challenges.

Purpose of the Study:

• To synthesize and characterize a novel mesoporous cationic thorium-based metal-organic framework (MOF).
• To investigate the anion-exchange properties and pollutant sorption capabilities of the MOF.
• To explore the sorption mechanism of pollutants using computational methods.

Main Methods:

• Synthesis and characterization of a mesoporous cationic thorium-based MOF (SCU-8).
• Experimental evaluation of anion-exchange properties with various anions, including ReO4-, Cr2O72-, methyl blue, and PFOS.
• Application of quantum mechanical and molecular dynamics simulations to probe the sorption mechanism.

Main Results:

• SCU-8 exhibits a high surface area (1360 m2 g-1) and large channel diameters (2.2 nm).
• SCU-8 demonstrates fast uptake kinetics and high selectivity for perfluorooctane sulfonate (PFOS).
• Simulations reveal that PFOS anions are immobilized via electrostatic, hydrogen bonding, hydrophobic, and van der Waals interactions.

Conclusions:

• The developed mesoporous cationic MOF (SCU-8) is effective for capturing anionic pollutants.
• SCU-8 shows promising potential for the selective removal of persistent organic pollutants like PFOS from water.
• Understanding the multi-force interaction mechanism aids in designing advanced materials for environmental remediation.