One-minute mechanistical synthesis of bimetallic Cu/Zn-MOF-74 for rapid and high-capacity Sr2+ removal from radioactive wastewater

Radioactive strontium ( 90 Sr) contamination in water bodies poses one of the most persistent and serious threats to both ecological safety and public health, owing to its long half-life, high environmental mobility, and strong propensity for biological accumulation. However, a rapid and sustainable synthetic route for bimetallic MOF-74 with high Sr 2+ adsorption capacity remains lacking. This study reports a solvent‑free mechanochemical strategy for the synthesis of a bimetallic Cu/Zn-MOF-74 (CZ-M74-11) using a spiral gas-solid flow (S-GSF) method in just 1 min. The material achieves 98.26% Sr 2+ removal within 15 min and exhibits a maximum Langmuir adsorption capacity of 295.13 mg·g −1 at 303.15 K. Kinetic and thermodynamic analyses indicate that the adsorption is spontaneous and exothermic. XPS and FT-IR analyses, together with cyclic desorption data, reveal that Sr 2+ uptake proceeds primarily through outer-sphere complexation, with a minor contribution from inner‑sphere coordination involving carboxylate groups. This work addresses the gap in rapid and sustainable routes for bimetallic MOF-74 synthesis by introducing an S-GSF method that achieves excellent adsorption capacity and ultrafast kinetics for Sr 2+ removal. Graphical abstract