Eco-friendly synthesized zeolitic imidazolate framework-8 enables one-step cerium recovery from water

Abstract

The rapid pace of technology advancement has quickly depleted valuable rare earth elements (REEs), which are critical for the function and performance of electric and electronic components, and there is thus a need for REE extraction from secondary sources rather than from virgin mines. This study presents an approach involving the ball-milling-induced construction of zeolitic imidazolate framework-8 (ZIF-8) that integrates REE extraction and recovery processes. ZIF-8 demonstrates remarkable extraction capacities for various REEs, and notably promotes nanoscaled CeO2 formation. Ball-milling-prepared ZIF-8 (ZIF-8-BM) effectively concentrates cerium (III) ions (CeIII), and a purity of 99.34% is achieved by controlling the processing parameters, offering a comprehensive solution for efficient Ce retrieval from water. The superior Ce extraction performance is attributed to the greater numbers of structural defects and surface hydroxyl (–OH) groups and the enhanced phase transformation efficiency. Moreover, Ce extraction by ZIF-8-BM is found to be efficient in both low and high Ce concentration ranges. ZIF-8-BM nanoparticles spontaneously oxidize CeIII in solution to insoluble CeO2, thereby facilitating the efficient extraction and subsequent recovery of cerium from complex matrices. The findings of this study provide an environmentally benign approach for the safe and efficient recovery of REEs from waste streams, supported by a scientifically sound and economically feasible processing strategy.