Construction of Ion-Imprinted Graphene Oxide Mixed-Matrix Membranes for Selective Adsorption and Separation of Tm³⁺

Efficient adsorption and separation of rare earth from other similar rare earth wastewater has become an urgent demand for resource utilization of ion-type rare earth minerals in China. Herein, thulium (Tm) ion-imprinted graphene oxide (GO)-doped polyether sulfone (PES) membranes (GO-TII/PES-2 membranes) were prepared, in which ion-imprinted graphene oxide was applied as an efficient Tm³⁺ ionic ligand in the imprinted layer and polyether sulfone was applied as a carrier in the membrane matrix to achieve the selective adsorption and separation of Tm³⁺ and neighboring rare earth ions. Combined with an ion rectifier, the separation and purification performances of Tm³⁺ were explored. The separation factors β_(Tm³⁺_/Tb³⁺₎, β(_Tm³⁺/Sm³⁺₎, β_(Tm³⁺/Nd³⁺_), and β_(Tm³⁺/Ce³⁺₎ in the dynamic adsorption process increased significantly from 1.22, 1.04, 1.04, and 1.02 for nonimprinting to 3.07, 3.91, 3.91, and 3.33 for imprinted membranes. The GO-TII/PES-2 membrane adsorbed about three times more Tm³⁺ than the nonionic-imprinted (GO-NII/PES) membrane by adding a color developer and quantifying Tm³⁺ based on a fast and easy UV-photometric method. After eight dynamic permeations, the adsorption of Tm³⁺ by the GO-TII/PES-2 membrane decreased by only 13%, indicating that the membrane has good reuse performance. Additionally, the investigation examined the influence of Tm³⁺ on wheat seed germination, underscoring its potential application in agriculture and the importance of adsorbing and separating rare earth ions.