Interface Modulation of 2D Superlattice Heterostructures with Oxygen-enriched Sites and Dissolution Restraint for Effective Rare-earth Elements Extraction

Abstract

Effective recovery of rare earth elements from wastewater is crucial for the modern industry, as well as for protecting the human health and ecosystem. Nevertheless, it is still challenging to realize efficient and selective low-concentration rare earth extraction in systems containing high levels competing metal ions. Here, we report on the fabrication of two-dimensional superlattice heterostructures (VOGO-x) through the alternating restacking of VOPO4 nanosheets and GO-PDDA nanosheets via electrostatic self-assembly. The meticulously organized molecular scale of superlattice heterostructures enable the full exposure of accessible adsorption sites and facilitate the transport of rare earth ions, meanwhile the abundant oxygen-containing phosphate groups within the interlayer can realize selective rare earth ions extraction. Furthermore, the tunable interlayer interaction can promote structure stability to prevent dissolution. Consequently, VOGO-11 possesses excellent rare earth adsorption performance, with a saturated adsorption capacity (Nd(III) 631.52 mg/g, Dy(III) 689.48 mg/g, Lu(III) 716.06 mg/g), high utilization rate of adsorption sites and short adsorption equilibrium time of simply 10 min in the REE aqueous solution. Furthermore, VOGO-11 exhibits outstanding selective rare earth adsorption ability over a wide range of metal ions in the low-concentration simulated wastewater and actual leaching tailings. These results demonstrate the material’s promising potential in capturing rare earth ions and pave the way to the development of two-dimensional superlattice heterostructures through interface modulation for effective rare earth extraction.