Superparamagnetic graphene oxide-magnetite nanoparticle composites for uptake of actinide ions from mildly acidic feeds

- GO-Fe3O4 nanocomposites were synthesized and characterized by conventional techniques.
- Trivalent actinide/lanthanide ions were efficiently removed from low pH feeds.
- Tetra and hexavalent actinide ions were also taken up from mildly acidic feeds.
- Sorption isotherm data fitted to the Langmuir and Timken models.
- Tracer spiked actual ground water was used for a test study with encouraging results.

Super paramagnetic graphene oxide (GO) − Fe3O4 nanoparticle composites were prepared and characterized by conventional techniques such as XRD, SEM, EDX, FT-IR, Raman, XPS, DLS and zeta potential, etc. TEM studies have confirmed nanoparticle nature of the composites. The GO-magnetic nanoparticle composites can be dispersed in mildly acidic aqueous solutions and get concentrated in a small volume under application of an external magnetic field. The composites were evaluated for the uptake of actinide ions such as Am3+, UO22+, Th4+ and Pu4+ from mildly acidic aqueous solutions. Am3+ sorption sharply increased with pH as the Kd values increased from about 10 at pH 1 to 105 at pH 3 beyond which a plateau in the Kd values was seen. Eu3+ displayed nearly comparable uptake behaviour to that of Am3+ while the uptake of other metal ions followed the trend: Pu(IV) > Th(IV) >> UO22+. The adsorption behaviour of Am3+ onto the graphene oxide − Fe3O4 nanoparticle composites fitted very well to the Langmuir as well as Temkin isotherm models. The desorption rate (using 1 M HNO3) was fast and reusability study results were highly encouraging. The very high uptake values suggest possible application of the magnetic nanoparticles in radioactive waste remediation in natural ground water.