Phase-Inversion Engineering of Covalent Organic Framework Microspheres for Advanced Water Purification.

Abstract

Covalent organic frameworks (COFs) are porous, crystalline polymers with broad application prospects. However, their microcrystalline powder morphology severely limits their practical implementation. Herein, a general phase-inversion spherical shaping strategy is reported, enabling the conversion of powdered COFs into robust microspheres with a radially hierarchical pore structure. This method is mild and scalable and has been validated across eight COFs with distinct topologies. The resulting microspheres retain approximately 90% of the intrinsic adsorption capacity of the pristine materials. As a representative demonstration, TAPB-DMTP-COF microspheres were employed in a fixed-bed continuous-flow water treatment system, where 1 g of the material effectively purified over 18 L of real water containing a mixture of bisphenols, with each concentration at 200 ppb, while maintaining high performance over 20 regeneration cycles. More notably, the TAPB-DMTP-COF microspheres themselves possess intrinsic catalytic activity for peroxymonosulfate activation, enabling sequential adsorption enrichment and catalytic degradation within the same fixed-bed column without metal modification. This work establishes a versatile COF shaping platform that extends the application scope of COFs from adsorption to advanced oxidation, offering a viable pathway to overcome a critical bottleneck in their industrial implementation.