A Macroporous Cyclodextrin Monolith for Continuous Removal of Per- and Polyfluoroalkyl Substances from Water

Per- and polyfluoroalkyl substances (PFASs) are environmentally persistent, bioaccumulative, and toxic chemicals that contaminate global drinking water resources. Their ubiquity and potential impact on human health motivate large-scale remediation. Conventional materials used to remove PFASs during drinking water production are functionally inefficient or energetically expensive, motivating the discovery of new materials and technologies. Here, we introduce cyclodextrin-based monoliths, featuring a highly permeable, mechanically robust porous architecture that enables rapid and continuous PFAS removal from water. The monolith was directly polymerized into flow-through columns and showed water permeability similar to packed sand due to its interconnected macroporous structure. Compared to leading benchmarks under equivalent sorbent mass or contact time, the monolith demonstrated superior PFAS sorption with later breakthroughs for most PFASs. We show the hierarchical morphology of a monolith is more efficient use of sorbent mass than particle-based sorbents, as its macropores enable facile diffusion of PFAS to meso- and microporous sorption sites. The significance of hierarchical pore design was demonstrated by instant PFAS breakthrough passing through the pulverized monolith, where the water primarily flows through interparticle pathways with limited access to sorption sites. After treating 150 L of water spiked with 25 PFAS for 37 days, 47 mg of monolith was regenerated through alcohol wash, with near-complete mass balance of adsorbed PFASs. The regenerated monolithic sorbent treated another 170 L of water for 39 days with comparable removal. The monolith offers a novel morphology with simple and direct synthesis in columns for water treatment and provides superior PFAS removal, regeneration and reuse.