Selective removal of uranyl from aqueous solutions containing mix of toxic metal ions using core/shell MFe2O4-TiO2 nanoparticles of montmorillonite edge sites

Usually, uranyl (UO22+) is competitively adsorbed by coexisting potentially toxic metal ions (Xn+: Rb+, Sr2+, Cr3+, Mn2+, Ni2+, Zn2+, Cd2+) that limit the adsorbent application. Here, the core-shell MFe2O4-TiO2 (M=Mn, Fe, Zn, Co, or Ni) nanoparticles were synthesised on K-montmorillonite (MMT) edge sites and assessed as new selective adsorbents. The results revealed that UO22+ and Xn+ were simultaneously adsorbed on the TiO2(101) surfaces, MFe2O4(111)-TiO2(101)/MMT(100)-MFe2O4(111) interfaces and MMT inner layers. Specifically, the Xn+ were mainly adsorbed on the TiO2(101) surfaces. We note that according to Freundlich models, UO22+ and Cr3+ were selectively adsorbed on the MFe2O4(111)-TiO2(101) interface. High adsorption capacity was up to 109.11 mg·g-1 on the MMT-Fe3O4(111)-TiO2(101) interface. The interface electron gases transferred from MMT(100)-MFe2O4(111) to MFe2O4(111)-TiO2(101) prevent the Cr3+ oxidation-reduction reaction and further adsorption. Our results suggested that MMT-MFe2O4-TiO2 is a su...