Ni–Al layered double hydroxides modified sponge skeleton with polydopamine coating for enhanced U(VI) extraction from aqueous solution

Abstract

Uranium (VI) (U(VI)) is a major fuel for nuclear power, and the mass of it in seawater is about 4.5 billion tons. However, many current U(VI) adsorbents exist in the form of powder, which hinders the smooth recovery of U(VI) from aqueous solutions and its application in actual environments. Herein, the MP@LDH as an easy-to-recover and 3D macroscopic adsorbent for U(VI) extraction from aqueous solution was successfully prepared. The adsorbent was obtained via anchoring of LDH on the surface of melamine sponge (MS) coated with polydopamine (PDA). The maximum experimental adsorption capacity of MP@LDH sponge for U(VI) was as high as 559.8 mg g−1 (at pH = 8.0, T = 298 K). In the competitive sorption experiments against the competitions of Ba(II), Sr(II), Zn(II) and others ions, MP@LDH still exhibited a particularly excellent selectivity for U(VI) (almost 90% removal rate). Furthermore, the removal rate of MP@LDH towards U(VI) reached 88.18% under simulated seawater (C0 = 3.47 μg L−1). We believe that the MP@LDH with easy retrieval, excellent selectivity and uptake amount provides a convenient way for U(VI) extraction from seawater.