Efficient and Simple Enrichment of Rare Earth by a Reversible Expansion‐Shrinkage Gel

ABSTRACT Previous research on rare earth recovery has primarily concentrated on enhancing adsorption capacity, while postadsorption procedures, such as effective enrichment and recovery, essential for low‐concentration metallic element recovery, have received less emphasis. Herein, a temperature‐sensitive reversible expansion‐shrinkage gel is designed. The gel absorbs solution and swells at low temperatures, facilitating adsorption. Conversely, the gel automatically shrinks at high temperatures, expelling excess water and free ions to achieve simple and efficient enrichment of rare earth ions. Take Nd(III) for example: Experimental findings demonstrated the exceptional adsorption efficiency of the gel for Nd(III), with a maximum adsorption capacity of up to 598.26 mg·g −1 . Additionally, the gel exhibited the ability to undergo a swelling‐shrinking cycle within 20 h. Even after five consecutive cycles, it retained excellent water absorption performance, while achieving an impressive 97.37% adsorption enrichment rate for Nd(III). Furthermore, the gel maintained a notable adsorption efficiency of 87.74% even after undergoing five adsorption–desorption cycles. In conclusion, this study presents an efficient and convenient adsorbent, offering a novel pathway for the development of intelligent adsorbents and facilitating the sustainable utilization of rare earth resources.