3D flower-like δ-MnO2@TpPa-1 composites was constructed though the integration of δ-MnO2 nano-flowers with a covalent organic framework (TpPa-1) via ultrasonication process. δ-MnO2@TpPa-1 a promising adsorbent for spent-nuclear-fuel reprocessing.

The binary nanocomposites of metal/covalent–organic frameworks (NH2-MIL-125­(Ti)@TpPa-1) were constructed by solvothermal method, which was developed as a multifunctional platform with adsorption and photocatalysis for radionuclides removal. The batch experiments and physicochemical property (FT-IR, XRD, SEM, TEM, XPS, etc.) corroborated: (i) core–shell NH2-MIL-125­(Ti)@TpPa-1 had a more stable, multilayer pore structure and abundant active functional groups; (ii) NH2-MIL-125­(Ti)@TpPa-1 had fast a removal rate, as well as a high adsorption capacity of 536.73 mg (UO2 2+)/g and 593.97 mg (Eu3+)/g; (iii) the pseudo-second-order and Langmuir model provided a more reasonable description, indicating the immobilization process was endothermic, spontaneous chemisorption; (iv) the adsorption mechanism was chelation and electrostatic attraction, ascribed to the nitrogen/oxygen-containing functional groups. These results illustrated that NH2-MIL-125­(Ti)@TpPa-1 was a prospective adsorbent for the remediation polluted by radionuclides. In addition, the research provided the theoretical basis for further investigation on the UO2 2+(VI) photoreduction.

CFeS-WS was synthesized by the modified method and exhibited excellent removal performance for U(vi). The proposed reaction mechanism of U(vi) removal by CFeS-WS was elaborated in detail.

The low-cost NiAl exhibits high efficiency for U(vi) decontamination, involving surface complexation and photocatalytic reduction. The photogenerated electrons and generated ˙O2− radicals reduced the absorbed U(vi) into insoluble UO2(s) and U3O8.