Co-sorption of Sr2+ and SeO42− as the surrogate of radionuclide by alginate-encapsulated graphene oxide-layered double hydroxide beads

Abstract Graphene oxides (GO) and layered double hydroxides (LDHs) were applied to produce alginate beads for the remove of 90Sr2+ and 79SeO42−. The Freundlich isotherm indicated that the Sr2+ sorptions were based on the energetically heterogeneous multilayer surfaces. In contrast, the sorption behavior of SeO42− fitted to the Langmuir adsorption isotherm models, indicating that the removal of SeO42− was caused by the ion-exchange of LDHs. The synthesized LDH/GO alginates beads were also applied for setting up small-bore adsorption columns with loading synthetic SeO42− and Sr2+ contaminated wastewater. Based on the water chemistry, the adsorbed amount of Sr2+ significantly increased after using alginates beads, which was attributed to the functional groups of either GO or alginic acid. The incorporated SeO42− was highly depended on the contents of fabricated LDHs in alginate beads. Specifically, the adsorption capacity of Sr2+ (0.85–0.91 mmol/g) on GO slightly increased after alginates fabrication. Therefore, it was deduced that this layered material was partially exfoliated during the manufacture and thus increased the sorption sites. Applications of LDH/GO alginates beads in the removal of both Sr2+ and SeO42− in water and soil treatment have a significant impact on the environmental remediation.