Rapid and efficient removal of Sr2+ ions by the easy-to-operate and environmentally friendly KInSnS4@collagen fiber aerogel†

It is still a challenge to capture radioactive ⁹⁰Sr²⁺ ions conveniently, quickly, and efficiently from complex aqueous solutions. Herein, a composite material, KInSnS₄@CF aerogel (CF = collagen fiber), was prepared by loading the metal sulfide ion exchanger KInSnS₄ on collagen fibers through electrostatic self-assembly. The KInSnS₄@CF aerogel is well shaped and maneuverable. It can efficiently capture Sr²⁺ with satisfactory adsorption capacity (q^Sr_max = 41.48 mg g⁻¹), fast kinetics (adsorption equilibrium within 2 min), broad pH activity (pH = 2–12), and facile elution. The aerogel shows good selectivity for the capture of Sr²⁺ under the coexistence of Na⁺, Cs⁺, Ca²⁺, and Mg²⁺, as well as in actual water samples. In addition, it can serve as the stationary phase being used in the ion exchange column for the efficient treatment of Sr²⁺ solutions in a dynamic manner. The efficient Sr²⁺ removal of the KInSnS₄@CF aerogel mainly originates from ion exchange between Sr²⁺ and K⁺ in the interlayer spaces of KInSnS₄, while the CFs mainly serve as support materials. This work not only provides a new easy-to-operate and environmentally friendly metal sulfide composite aerogel, but also paves the avenue for the application of CFs from leather industry waste.