Wrinkled Layered Sulfide With Tunable Channels Unlocks Precision in Rare Earth Extraction From Radioactive Wastewater.

Abstract

Dimensionally adjustable channels are incorporated into a crystalline lattice via strategic stacking of wrinkled layers, boosting rare earth element (REE) ion exchange performance due to the eliminated energy-intensive dehydration and channel rigidity. In [(CH3)2NH2]2Ga2Sb2S7 (GaSbS-1), the lone electron pair (LEP) on Sb3+ in the trigonal pyramidal {SbS3} influences Ga─S bond orientations, creating wrinkled [Ga2Sb2S7]n 2 n - layers. Staggered stacking forms parallel channels occupied by [(CH3)2NH2]+ cations, facilitating outstanding exchange for REE3+ ions (Y3+, La3+-Lu3+). Dynamic interlamellar expansion endows GaSbS-1 with remarkable kinetics (R = 97.14%-99.40% within 5 min; k2 = 2.592-3.462 g mg-1 min-1) and capacities (63, 125, 143, and 138 mg g-1) for Y3+, Ce3+, Eu3+, and Tm3+. It exhibits structural stability across pH = 2-12, with Kd values > 104-105 mL g-1 at pH = 4-9, and superior selectivity for REE3+ over competing ions. Performance remains robust in real aqueous environments, including sea water, with maximum REE3+ removal rates >90%. Rapid kinetics enable efficient column filtration (R = 93.10%-98.51%) and recycling capability. The GaSbS-1/PTFE membrane achieves 99.71%-99.95% removal of trace REE3+ at 1.38 mL min‒1 cm‒2 (0.17 s contact time). With high yield, irradiation resistance, and facile elution, GaSbS-1 is a proof-of-concept exchanger for purifying REE-contaminated radioactive wastewater.