Novel preparation of amidoxime functionalized hyper-cross-linked polymeric adsorbent on the efficient adsorption of uranium in aqueous solution

Abstract

Herein, a series of novel amidoxime-functionalized porous polymeric adsorbents using dimethoxymethane (FDA) as the external cross-linker and biphenyl and amidoxime-functionalized 1-(benzyloxy)-4-ethylbenzene (BP-AO) as the original monomers were synthesized in one-pot Friedel-Crafts alkylation reactions via a simple “knitting” synthetic strategy. The adsorbents were characterized by FT-IR, solid-state 13 C NMR/MAS spectrum, N 2 adsorption-desorption, etc. The adsorption mechanism was probed by XPS, which suggests that the η 2 complexation between uranium and amidoxime, and the polymers provide an approach to synthesize novel porous materials. The batch adsorption experiments showed that amidoxime hyper-crosslinked polymer-2 (HCPA-2) displays a uranium adsorption capacity of 27.7 mg/g at pH 6. The static adsorption action was more consistent with the Langmuir model and pseudo-second-order kinetics. Ionic competition experiments showed that K d (U(IV)) is as high as 695.94 mL/g and reusable with a removal rate up to 60% after 7 cycles when 0.1 M HNO 3 was used as a stripping agent, which verifies the practical application potential of the materials. • The HCPAs adsorbents with porous structure was synthesized via facile “knitting” strategy. • The HCPAs exhibited high selectivity and long service life. • The adsorption capacity was affected by the specific surface area and amidoxime group content. • The adsorption process was spontaneous and endothermic.