Role of alkyl chain branching on aggregation behavior of two symmetrical diglycolamides: Small angle neutron scattering studies

• Published in: Journal of colloid and interface science 2013-03, Vol.393, p.347-351
• Main Authors: Pathak, P.N., Ansari, S.A., Mohapatra, P.K., Manchanda, V.K., Patra, A.K., Aswal, V.K.
• Format: Article
• Language: English
• Subjects: Actinide partitioning; Actinides; Agglomeration; Aggregation; Alkanes - chemistry; Chemistry; Derivatives; Diglycolamides; Exact sciences and technology; Extraction; General and physical chemistry; Glycolates - chemical synthesis; Glycolates - chemistry; Glycolates - isolation & purification; Ligands; Metal ions; Molecular Structure; Neutron scattering; SANS; Scattering, Small Angle; Solvent extraction; Styrene acrylonitrile resins; X-Ray Diffraction
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2012.10.023

[Display omitted] ► SANS measurements were done to compare the aggregation behavior of diglycolamides. ► The presence of acid in the organic phase facilitates aggregation. ► The presence of metal/nitrate ions has a marginal effect on aggregation. ► N,N,N′,N′-tetraoctyl diglycolamide displays more aggregation tendency. The two long alkyl chain derivatives of diglycolamide (DGA), viz. N,N,N′,N′-tetraoctyl diglycolamide (TODGA) and N,N,N′,N′-tetra(2-ethylhexyl)-diglycolamide (T2EHDGA) have been found promising for actinide partitioning from high-level waste. The solvent extraction studies have suggested the participation of three to four DGA molecules in the extracted complex of trivalent actinides and lanthanides. However, coordination of 3–4 tridentate DGA ligands with trivalent f-elements seems to be unusual due to restricted coordination sites in these metal ions. Nonetheless, the extraction data have been explained in view of the formation of aggregates of these ligands in the organic phase. Small Angle Neutron Scattering (SANS) measurements were carried out to investigate the aggregation behavior of DGA ligands in deuterated n-dodecane. The aggregation of DGA molecules was facilitated by the presence of acid. However, the presence of nitrate ions in the aqueous phase had no significant effect on the aggregation of DGA. Similarly, the presence of metal ions such as Sr(II) or Eu(III) marginally affected the aggregation tendency of DGA molecules. TODGA displayed higher aggregation tendency than that of T2EHDGA. The extraction data of trivalent f-elements were in conformity with the aggregation tendency of the two DGA ligands.