SANS study of dialkylsubstituted diphosphonic acids and their complexes with Ca, Fe, La, Th and U in toluene

摘要

The aggregation of di(2ethylhexyl) methane-, ethane- and butanediphosphonic acids and their complexes with various metal cations at different concentrations in toluene has been studied in detail using Small Angle Neutron Scattering. The diphosphonic acids are being employed as novel solvent extraction reagents in the Chemistry Division of ANL. These compounds exhibit extraordinarily strong affinity for actinide ions and for Fe(III). The growth of large metal-diphosphonate aggregates depends on the metal species, metal to extractant ratio, and the length of the carbon bridge between the two acid groups. Fe(III) complexes with the methane and butane (but not the ethane) bridged diphosphonic acid aggregate to form large polymeric rods at high metal to extractant ratios. Actinide ions likewise give large aggregates with di(2ethylhexyl) methanediphosphonic acid. Ca(sup 2+) and La(sup 3+) show only the usual formation of small 'monomeric' chelates.