A layered double hydroxide assembled on a g-C3N4-modified hollow carbon sphere as an adsorbent for the removal of uranium(VI)
In this study, a layered double hydroxide assembled on a g-C3N4-modified hollow carbon sphere with unique flower-like morphology (C3N4-HCS@LDH) was synthesized for the capture of uranium(VI) (U(VI)). The adsorption efficiency was evaluated under the effects of pH, adsorption time, temperature, U(VI) concentration and interfering ions. These results showed that the adsorption process was well fitted by the Langmuir isotherm and pseudo-second-order models. The maximum adsorption amount of C3N4-HCS@LDH was 609.7 mg g−1 at 298 K and pH = 7.0. The adsorption mechanism was mainly attributed to the coordination between O- and N-containing functional groups and U(VI) by XPS results. Moreover, the C3N4-HCS@LDH composite showed high selectivity for U(VI) in an aqueous solution (mg L−1 level) and artificial seawater (μg L−1 level). Therefore, we conclude that the C3N4-HCS@LDH composite is an encouraging material to promote U(VI) enrichment in a seawater environment.