Thorium could replace uranium as a fuel for the production of nuclear energy. It has the potential to provide more energy while producing much less long-lived nuclear waste. The extraction of thorium from its mineral monazite and the separation of Th from other actinides and lanthanides usually requires large amounts of acids and solvents. Solid-state absorbents could solve this problem.

Kenneth J. Balkus, Jr. and colleagues, University of Texas at Dallas, Richardson, USA, have found that surface-oxidized wrinkled mesoporous carbon (WMC-O) can be used to selectively extract and separate thorium ions from rare earth ions. WMC has conical pores that radiate from the center of each particle to the outside.

The desired WMC-O was prepared using wrinkled mesoporous silica (WMS) as a template. WMS was dispersed in an aqueous solution of sucrose and sulfuric acid, which was dried and heated to 160 °C. This process was repeated and the product carbonized at 900 °C to give WMC. Concentrated nitric acid was then used to oxidize the surface and obtain WMC-O.

WMC-O can be used as a solid-state absorbent for thorium with high selectivity. The researchers attribute the good absorbent performance to the high surface area, the unique pore structure, and the large number of oxygen functional groups at the surface of the material.

• Selective Extraction of Thorium from Rare Earth Elements Using Wrinkled Mesoporous Carbon,
  Zijie Wang, Alexander T. Brown, Kui Tan, Yves J. Chabal, Kenneth J. Balkus,
  J. Am. Chem. Soc. 2018.
  https://doi.org/10.1021/jacs.8b07610