β-Cyclodextrin and diatomite immobilized in sodium alginate biosorbent for selective uranium(VI) adsorption in aqueous solution

The separation and enrichment of uranium from various resources such as seawater is of great significance to the sustainable development of nuclear energy. Therefore, there is an urgent need to develop an adsorbent with low cost and easy availability, simple preparation process, and environment friendly. In this work, we used inexpensive natural polymer material (sodium alginate) and natural adsorbents (β-cyclodextrin and diatomite) to prepare a novel biosorbent β-cyclodextrin/sodium alginate/diatomite (CSD) hydrogel beads for uranium adsorption by a simple method. The results of FTIR, XRD, SEM, EDX and XPS characterization proved that the CSD were prepared. Static adsorption experiments showed that pH, contact time, initial concentration of U(VI) and temperature has significant impact on the adsorption capacity of CSD. Adsorption fitted the pseudo-second-order kinetic model and Langmuir model and the adsorption mechanism is chemical adsorption. In the presence of other metal ions (Cu2+, Mg2+, Ca2+, Na+, K+), CSD has obvious selectivity for uranium(VI) adsorption. In addition, the elution and reusability studies show that CSD has excellent reusability. Overall, CSD is an inexpensive, green preparation, efficient, and environment friendly biosorbent with obvious selectivity for U(VI). It has potential application in U(VI) enrichment from seawater or salt lake water.