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 K_d 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.