A 3D porous KCuFC/collagen fibers/gelatin adsorbent for ultra-fast cesium capture from radioactive wastewater.

The effective removal of radioactive cesium (137Cs) from contaminated water remains a critical challenge. Although metal hexacyanoferrates (MHCFs) exhibit exceptional selectivity for Cs+, their practical application is hindered by their powdery nature, poor mechanical strength, and difficult recovery. Herein, we report a novel three-dimensional bulk adsorbent, KCuFC/CFs/GA, fabricated via an in-situ growth strategy using collagen fibers (CFs) and gelatin (GA) as a dual-network support matrix. Cu2+ serves as a dual-functional crosslinker, simultaneously coordinating with carboxyl groups from the matrix to form a stable network and anchoring the crystallization of potassium copper ferrocyanide (KCuFC) nanoparticles. Sodium carboxymethyl cellulose is employed as an additional binder to enhance structural integrity. The resulting material exhibits a highly porous structure (porosity of 95%, average pore diameter of 14 μm) and robust mechanical properties, withstanding 0.54 MPa compressive stress. Notably, the adsorbent demonstrates exceptionally rapid adsorption kinetics, achieving equilibrium within 30 min. It also shows a high maximum adsorption capacity (230.70 mg g-1 at 45 °C) and outstanding selectivity for Cs+ even in the presence of high-concentration competing ions (Kd = 3.02 × 105 mL g-1). The material also exhibits excellent reusability (91.2% retention after five cycles), broad pH stability (2-11), and outstanding gamma irradiation resistance. Comprehensive characterization confirms the adsorption mechanism is primarily K+-Cs+ ion exchange within the KCuFC lattice, complemented by electrostatic interactions with surface functional groups. This work provides a promising strategy for designing high-performance, mechanically robust adsorbents for cesium-contaminated water remediation.