Statics and Kinetics of Sorption of La(III), Ce(III), U(VI) Ions by a Nanostructured Composite Al 2 O 3 ||C

The sorption properties of the new Al 2 O 3 ||C composite were studied. A feature of its macroscopic morphology and structure is the amorphous state of alumina generated in an inert atmosphere in chemical contact with the graphene-like carbon surface. This feature is shown to determine the high chemical activity of the alumina-based composite (AC) in an aqueous medium, which is comparable with the activity of α-Al 2 O 3 or gibbsite Al(OH) 3 . The sorption properties of the obtained composite towards La(III), Ce(III), U(VI) ions are described within the surface complexation model. The agreement between the values of the first hydrolysis constant of La(III), Ce(III), and U(VI) cations calculated from the sorption experiment and published data proves the adequacy of the chosen sorption model. It follows from simulation that the sorption activity of the composite is caused by a higher constant ( K 1a ) of the acid dissociation of –ОН 2 + surf groups (p K 1a = 3.9) of the amorphous AC surface and the partial distribution coefficients of individual hydroxo complexes of the studied cations. Sorption of ions by the composite in a solution of humic acids (HA) is completely determined by the parallel reaction of competitive sorption of protonated HA anions by the amorphous AC surface in the HA concentration range of 10–200 mg/L. Al 2 O 3 ||C is an effective sorbent for trace amounts of La(III), Ce(III), U(VI), their chemical analogs, and humic acid in natural and working solutions with a low salt background.