Rapid and selective uranium adsorption by a low-cost, eco-friendly, and in-situ prepared nano-ZnS/alkali-activated collagen fiber composite

Uranium is one of the most hazardous elements due to its long half-life and chemical toxicity to living organisms that occurs in surface, subsurface water, and radioactive wastewater normally in the soluble UO22+ form. However, it is a challenge to rapidly and highly selectively separate UO22+ from complex aqueous environments. Here, we innovatively propose a secure, environmental, and sustainable approach to proficiently capture UO2 2+. A nano-ZnS/alkali-activated collagen fiber composite (ZnS-AACF) was successfully fabricated via the facile insitu growth method, in which collagen fibers derived from leather waste act as the substrate. Notably, the composite ZnS-AACF presents good radiation resistance and wide pH durability (pH = 2-11). Moreover, ZnSAACF has the high maximum adsorption capacity (qmU = 359.72 mg/g), fast kinetics, and excellent selectivity for UO22+. ZnS-AACF can selectively capture UO22+ in the presence of a variety of excess competitive ions such as Fe3+, Ni2+, Cu2+, VO3- , and UO22+. Even in highly saline environments with ultra-high concentrations of K+, Ca2+, Na+, Mg2+, Cl-, HCO3-, SOa -, and Br- ions, ZnS-AACF can still achieve the selective removal for UO22+. Furthermore, ZnS-AACF can serve as a stationary phase in columns facilitating the dynamic and efficient separation of UO22+ with qmU up to 243.69 mg/g. The adsorption mechanism of ZnS-AACF for UO22+ is revealed to be the synergistic action between functional groups on the collagen fibers and nano-ZnS.