Preparation of hollow granules as micro-adsorber for uranium extraction from aqueous solutions

The improvement of the molding process of adsorbent powders is significant for practical application on uranium adsorption in aqueous solution. In this work, the phenomenon of liquid marble was harnessed to prepare silica nanoparticles & SBA-15 granule (SSG). The obtained SSGs were millimeter-sized spherical particles, which overcame the difficulty in application of powders. The maximum adsorption capacity of SSG was 123.2 mg/g under pH of 6 and 25 °C. The SBA-15 existed inside SSG and the active adsorption sites on SBA-15 were not embedded, making them play the role of adsorption as far as possible. Moreover, the porous shell of SSG offered possibility for the delivery of the adsorbate. The transmission of uranyl ions and adsorption process both happened within the millimeter-sized hollow spheres, which proved the role of micro-adsorbers. The adsorption behaviors of SSG were more consistent with the pseudo-second-order model and Langmuir model. The SSGs were packing in column to prove their great stability during dynamic adsorption process. In addition, the dynamic adsorption device achieved the dilution of adsorption solution and enrichment of uranium resources. The SSGs demonstrated their ability in uranium extraction. Moreover, the granulation process also offered a new approach for practical application of powders.