One-pot fabrication of fiber-CAMHC for sustainable rubidium recovery from salt lake brines: towards circular resource management

Abstract

With the global exploitation of salt lake resources, rubidium in brines represents both a valuable asset and an ecological risk. Developing a green and efficient process to extract low-grade rubidium from highly mineralized brines is of paramount importance for the advancement of salt lake science. This study innovatively proposes a new method that combines the preparation of powdered adsorbents and the molding of composite materials into one process. A copper-based Prussian blue analogue (CAMHC) is synthesized through a one-pot method in a non-aqueous system and subsequently introduced into a wet spinning machine, resulting in the production of a novel fiber-like adsorbent (Fiber-CAMHC). Fiber-CAMHC achieves adsorption equilibrium for Rb+ within 8 minutes, with a maximum theoretical adsorption capacity of 247.06 mg g⁻¹. Calculations of charge density distribution and density of states using Density Functional Theory (DFT) further corroborate the excellent adsorption performance of Fiber-CAMHC. Dynamic fixed-bed adsorption tests demonstrate an efficiency of 95.77%, and the adsorption process can be accurately modeled using the Thomas and BDST models, providing critical guidance for future industrial-scale design. XPS and XRD analyses of three adsorption/desorption cycles confirm the remarkable stability of Fiber-CAMHC. In conclusion, Fiber-CAMHC shows outstanding performance in rubidium extraction from brines, thus providing valuable data for its industrial application.