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

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 syn-thesis 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 ki-netic behaviors. This work provides a new route to improve U(VI) adsorption capability for highly efficient treatment of radioactive wastewater.

Automated summary

In this study, a novel Cu2O@ZIF-8 particle was designed and synthesized using a fast microwave-assisted scalable synthesis method. The Cu2O@ZIF-8 particles exhibited high efficiency in reducing U(VI) ions to U(IV) and separating them from aqueous solutions for the treatment of radioactive wastewater. The particles with octahedral Cu2O crystals showed the best performance among different facet shapes. The optimized octahedral Cu2O@ZIF-8 particles demonstrated remarkable adsorption capability, reaching 330.87 mg/g, which is much higher than previously reported values for other adsorption materials. The mechanism of adsorption was investigated, and the adsorption behavior followed Freundlich isotherm and pseudo-second-order kinetic models. This work provides a new approach to improve U(VI) adsorption capability for highly efficient treatment of radioactive wastewater.