Extended x-ray adsorption fine structure studies of Cs dibenzo-18-crown-6-ether complexes

Development of effective and contaminant specific waste isolation and stabilization technologies requires molecular level information on contaminant sorbent/chelator interactions. 137Cs is a common component of nuclear waste streams that must be isolated to reduce waste volume. We have used the extended X-ray absorption fine structure (EXAFS) technique to investigate the local structure of 133Cs+-dibenzo-18-crown-6 ether complexes in non-aqueous solution and powder forms. Analyses of solution complexes indicates contact pairing as e compared to non-contact (i.e. solvent separated) pairing of the Cs-crown ether complexes with the halide anion to form ternary complexes. Recrystallization of the complexes to the solid form resulted in the redistribution of Cs-halide salt as a distinct phase from the crown ether. These data illustrate the importance of direct measurement of solution phase chemical speciation without sample modification