Low Environmental Impact Magnetic Chitosan and Chitin Cryogels for PFAS Remediation

Abstract Polymers derived from renewable carbon feedstock are destined to play a pivotal role in the transition to a sustainable circular economy, displacing conventional fossil‐carbon materials. Chitin (CT) and chitosan (CS) are well‐suited to develop multifunctional materials that are mechanically resilient and easy to process. Their abundance of hydroxyl and amine groups facilitates hydrogen bonding and electrostatic interactions, making them suitable for persistent pollutant removal from drinking water. Therefore, porous CS cryogels are fabricated by dissolution in acetic acid, coagulation, and subsequent freeze‐drying. To enhance durability in harsh environments, CT cryogels are obtained through acetylation. Furthermore, Fe₃O₄ nanoparticles are incorporated to enable removal by external magnetic fields. The rapid removal of per‐ and polyfluoroalkyl substances (PFASs) with capacities reaching 451 mg g⁻¹ offers competitive performance against state‐of‐the‐art materials. The shear‐thinning properties of CS enable rapid additive manufacturing in predetermined free‐standing shapes, useful for accessing sites with complex geometries. Life cycle assessment (LCA) confirms the suitability of chitosan and CT cryogels for low environmental impact water remediation applications. Furthermore, the cryogels can be recycled, closing the material loops back into the economic cycle. Altogether, this work demonstrates the potential of chitosan and CT as competitive alternatives to fossil‐carbon derived systems for sustainable environmental remediation.