Application of ion imprinted polymers (IIPs) for rare earth elements recovery from secondary aqueous sources—A data-based review

Rare earth elements (REE) are of significant importance due to their irreplaceable roles played in various industries and military applications. The current REE supply mainly comes from primary ore-deposits and is under control by very few countries, leading to a significant risk of supply-chain disruption. To minimize such risk, there is an increased interest in extracting REEs from secondary sources, such as Acid Mine Drainage (AMD) and natural Acid Rock Drainage (ARD). However, compared to the primary sources, the dramatically lower concentration of REEs and higher levels of competing species (e.g., H⁺, Fe³⁺, Ca²⁺, Mg²⁺, Al³⁺) makes REE extraction extremely challenging. One approach to overcome this challenge is to use highly selective adsorbents, such as ion imprinted polymers (IIPs) that have been increasingly explored in recent years. Our main objectives of this data-based review are to: (1) clarify the application scenarios of two types of selectivity factors and evaluate the related methods via data analysis and modeling, (2) compare the performance of synthetic versus natural polymer-based IIPs through statistical analysis, and (3) provide perspectives for IIP development and testing to facilitate future advances.