Ligand field effect for Dysprosium(III) and Lutetium(III) adsorption and EXAFS coordination with novel composite nanomaterials

The separation of lanthanide (Ln(III)) elements from various waste materials is a significant issue facing developed countries. However, the chemical behaviour of Ln(III) are very similar and complex, and it is an important to understand clearly to optimize the separation processes under various conditions based on the ion-selective ligands and ligand field effect for specific Ln(III) separation with semi-cavity and high flexibility for competitiveness of industries and continuous economic growth. The study developed the hybrid Lewis base ligand functionalized alumina-silica based composite nanomaterials for heavier Ln (III) of Dy(III) and Ly(III) separation and recovery. The alumina-silica fabrication, intra-series separation, solution acidity, ion-selective and coordination mechanism by EXAFS were carried out systematically. The Dy(III) and Lu(III) adsorption was high in acidic region as the high pH area is avoided due to the hydroxyl precipitation. The adsorption data were fitted well with the Langmuir adsorption model for the both elements and the calculated maximum adsorption capacity was 125.44 and 129.77 mg/g for Dy(III) and Lu(III) ions, respectively. The ion selectivity was also performed in the presence of divers ions and Dy(III) or Lu(IIII) ions was preferentially adsorbed in a competitive environment. In the coordination mechanism by EXAFS, the Dy(III) and Lu(III) ions were strongly coordinated with the O and N atoms of the hybrid Lewis base ligand in the composite nanomaterial. Moreover, adsorption-elution cyclic results demonstrated that Dy(III) and Lu(III) ions adsorbed composite nanomaterial could be effectively desorbed HNO3 acid, and the regenerated nanomaterial was able to repeated use without significant deterioration in its original performances. All these characteristics make the nanomaterial an ideal solid-phase materials for effective Dy(III) and Lu(III) ions adsorption in complicated matrix samples. (C) 2017 Elsevier B.V. All rights reserved.