Scalable Fabrication of Prussian Blue/Polyacrylonitrile Fibers toward Practical Decontamination of Cs+-Contaminated Water

The development of adsorbents that combine high efficiency, selectivity, and scalability for the removal of radioactive cesium (Cs+) from contaminated water remains a critical challenge. Although powdered Prussian blue (PB) is an excellent Cs+ scavenger, its practical application is limited by difficulties in recovery and the risk of secondary pollution. To address this, we report the mass-producible fabrication of Prussian blue/polyacrylonitrile (PB/PAN) composite fibers via a facile and scalable wet-spinning technique. Batch adsorption experiments demonstrated that the process follows the Langmuir model and pseudo-second-order kinetics, indicating monolayer chemisorption with a maximum capacity of 24.11 mg/g at 298 K. The fibers exhibited exceptional selectivity for Cs+ in a multicomponent system containing 13 competing ions. Furthermore, the adsorbent showed excellent reusability, retaining over 75% of its initial capacity after three adsorption-desorption cycles. Mechanistic studies, combining spectroscopic analyses (XPS, XRD, Mössbauer) and theoretical calculations (DFT), revealed that the high performance originates from a "lattice insertion-coordination" mechanism, where Cs+ is selectively embedded into the PB lattice vacancies and coordinates with cyanide nitrogen atoms. This work provides not only a practical and scalable adsorbent for environmental remediation but also offers profound insights into the molecular-level interaction between Cs+ and PB-based materials.