A proton-exchange poly(acrylic acid) supramolecular hydrogel for ultrahigh uranium adsorption

Abstract

The development of high-efficiency absorbents is an ongoing demand to purify uranium-containing wastewater. This study reports a poly(acrylic acid) (PAA) supramolecular hydrogel with hydrogen bonding interactions via physical cross-linking in acidic solutions. The protons in the carboxyl groups of the PAA hydrogel can exchange with uranyl ions in aqueous solution during adsorption, and vice versa upon desorption/regeneration. It enables easy uranyl coordination with the PAA hydrogel, responsible for an ultrahigh uranium uptake of 1362 mg g⁻¹ in 20 mg L⁻¹ uranium-spiked water (pH = 7). In addition, the PAA hydrogel can tolerate high-concentration metal cations to a large extent, beneficial for high-efficiency uranium removal under realistic conditions. The findings give deep insights into the development of high-efficiency adsorbents for uranium removal from wastewater via supramolecular tailoring.