Decorative ZIF-8 covered facet-dependent Cu2O toward highly efficient adsorption by reduction U(VI) to U(IV)

Abstract

Developing high-performance materials for efficient and ultra-high capacity of U(VI) removal in radioactive wastewater remains a great challenge. Herein, we report the design and fast microwave-assisted scalable synthesis of novel facet-dependent Cu2O@ZIF-8 particles for highly effective reduction to U(IV) at the surface. and separation of the U(VI) ions from aqueous solutions. The Cu2O@ZIF-8 consists of polyhedral Cu2O crystals with dispersed ZIF-8 nanoparticles on their facets, which results in generation of a large number of highly active interfaces. The Cu2O@ZIF-8 shows strong facet-dependence towards the reduction U(VI) ions to U(IV) at the surface where octahedral Cu2O crystals performed better comparing with cubic and octahedral ones. The optimal octahedral Cu2O@ZIF-8 particles exhibit remarkable adsorption capability reaching 330.87 mg g−1, much higher than previously reported values for other adsorption materials. The involved mechanism was investigated, and the adsorption manifestation was found to be in accord with Freundlich isotherm and pseudo-second-order kinetic behaviors. This work provides a new route to improve U(VI) adsorption capability for highly efficient treatment of radioactive wastewater.