Tannin-modified down keratin fibers to construct an all-biomass-based adsorbent for efficient uranium extraction from seawater

As a biomass regeneration fiber, down keratin fibers (DF) have received wide attention in the field of adsorbents due to its physicochemical properties such as abundant hydroxyl groups, amino groups and other functional groups, light weight and high specific surface area. In this study, tannin-modified down keratin fibers (DF-CT) were prepared by covalent cross-linking of bayberry extract and DF. The phenolic hydroxyl groups in DF-CT can form a multifunctional supramolecular self-assembled metal-phenolic network (MPN) structure with uranium, endowing DF-CT with excellent adsorption performance. The static and dynamic adsorption experiments show that DF-CT has a fast adsorption rate and a high adsorption capacity (219 ± 20 mg/g) at 8 ppm uranium solution. In natural seawater, DF-CT also represents high adsorption capacity (4.43 mg/g) within 30 days. In addition, DF-CT has a high adsorption selectivity, recyclability and antibacterial properties. DF-CT has a degradation rate of 86.3 % in the natural environment, showcasing good biodegradability. Therefore, the all-biomass based DF-CT adsorbent cannot cause secondary pollution to the environment after disposal. This study provides a new idea for the development of new and efficient multifunctional adsorbents for sustainable uranium extraction from seawater.