Mn-based PBAs electrochemical ion exchange-electrodialysis coupling: A green paradigm for high-selectivity rubidium enrichment from Salt Lake brine

Rubidium (Rb), a critical rare alkali metal, is widely used in high-tech fields for its unique properties. With growing demand, liquid mineral resources (e.g., brines) require efficient green extraction. This study introduces a novel electrochemical ion exchange (EIE)-electrodialysis (ED) coupling technology for rubidium salt production. A manganese-based Prussian blue@carbon nanotube electrode enabled selective Rb + extraction via EIE, achieving 243.72 mg/g adsorption capacity and 97 % desorption efficiency. Batch tests and DFT calculations validated performance under varying conditions. In real brine, the system showed high selectivity ( α K Rb =206 and α Na Rb =521), reducing Rb + : Na + : K + from 1:258:610 to 1:0.49:2.96 via cyclic adsorption. Coupled ED concentrated a 9 L desorption solution to 450 mL in 90 min using alternating membranes, minimizing waste/emissions versus traditional evaporation. Evaporation yielded crude salts with 16.35 % Rb purity as in RbCl, achieving a brine-to-product breakthrough. This EIE-ED technology offers a selective, sustainable paradigm for rubidium enrichment from Salt Lakes, with industrial promise for rare metal extraction.