Selective removal of uranium from aqueous streams using synergistic adsorbents

Abstract

Maintaining radioactive uranium-free aquatic environment is essential for our survival. To achieve this, efficient adsorbents have been developed to remove hazardous uranium present in aqueous streams. The recovered uranium has also its important applications in power production. In this respect, silica gels anchored with phosphate functional groups have been chosen as the adsorbents as they are economic materials and easy to apply for large scale. The development done here is the formation of solid synergistic silica gel beads (SSBs) without applying the extrusion technology which is generally used for making pellets out of the phosphate functionalized silica gel powders. These adsorbents are selective for binding with uranium(VI) even when very competitive ions including vanadium are present at high concentrations. This is a challenging task for chemists where these adsorbents execute well. Kinetics of uranium uptake using these adsorbents is fast. Extraction coefficient (Kd) as high as 7.1x103 has been obtained using the synergistic mixtures. The observations have found potential applications for efficient uranium binding from various simulated aqueous streams and also from uranium metal plant process stream. Moreover, XPS experiments have been employed to establish the binding mechanisms. These beads can be synthesized economically; they are able to extract uranium(VI) in substantial quantity and have been tested in real process streams. Therefore, they are applicable at industrial scale.