Dynamic light scattering study on the aggregation behaviour of N,N,N′,N′-tetraoctyl diglycolamide (TODGA) and its correlation with the extraction behaviour of metal ions

Dynamic light scattering (DLS) studies were carried out to investigate the aggregation behaviour of N,N,N ',N '-tetraoctyl diglycolamide (TODGA) in n-dodecane and 1-octanol. The effect of the nature and concentration of different acids such as HCl, HNO3 and HClO4 on aggregation behaviour was investigated. The aggregation tendency of TODGA in different acids followed the order: HClO4 > HNO3 > HCl, which is similar to the extraction pattern of trivalent actinides/lanthanides in these acids. A direct correlation was observed between the extraction behaviour of Am(III) and the aggregation behaviour of TODGA in the presence of these acids. The aggregation of TODGA increased with increasing concentration of HNO3, HCl and HClO4. However, the aggregation tendency of TODGA was independent of its concentration at fixed acidity. The presence of Eu(III) ions facilitated the aggregation of TODGA. The aggregation studies revealed that about 2 nm aggregate size of ligand was the critical size required for efficient extraction of trivalent actinide and lanthanide ions. (C) 2009 Elsevier Inc. All rights reserved.