Preparation of defective and stable MOF membrane for enhanced uranium extraction from seawater

Abstract

Herein, a defect-rich UiO-66-NH₂ hybrid membrane (DUUM) was successfully synthesized via in-situ growth of defective UiO-66-NH₂ onto irradiation-treated ultra-high molecular weight polyethylene fabrics to enhance the uranium extraction from seawater. The concentration of lattice defects within the framework is regulated by simply adjusting the ratio of ligand to metal (L/M), and DUUM with the L/M ratio of 1 exhibits the best uranium adsorption capacity. The adsorption kinetics investigation shows that DUUM has a higher adsorption rate than UiO-66-NH₂ powders, and the adsorption isotherms investigation shows DUUM has a saturated uranium adsorption capacity of 460 mg·g⁻¹ which is about 5 times that of the defective UiO-66-NH₂ powders. DUUM exhibits a flux of 1440 LMH and a uranium removal efficiency of 65.5 % from natural seawater through single-pass filtration. More importantly, DUUM demonstrates excellent stability in real seawater environments (40-day) and under high doses of gamma-ray irradiation (300 kGy). The enhanced adsorption capacity is attributed to the membrane structure of DUUM which enhances exchange efficiency at the interface between uranium and DUUM via filtration, and the lattice defects which increase the specific surface area and expose more adsorption sites. The high stability results from the inherent hydrophobicity and radiation crosslinking features of the UP substrates. This study about DUUM will promote the practical application of efficient MOF membrane in fast uranium extraction from real seawater, as well as nuclear wastewater.