Process for separation of technetium from alkaline low level waste using di-tert-butyldibenzo-18-crown-6+isodecyl alcohol/n-dodecane solvent

Di-tert-butyldibenzo-18-crown-6 ether (CE) dissolved in a mixture of isodecyl alcohol and n-dodecane has been investigated for separation of technetium from alkaline low level waste (LLW). Technetium present as TcO4- pairs with sodium ion-crown ether complex formed due to high sodium nitrate concentration in the waste solution results in extraction of TcO4- by ion-pair formation of the kind Na+.CE.TcO4-. Stoichiometry of the extracted complex as determined by slope analysis of log-log plot of technetium distribution ratio (D-Tc) vs. the CE concentration suggests a combining ratio of 1 TcO4- to 1 CE. Extraction of TcO4- was examined from aqueous phase with varying NaNO3 and NaOH concentrations. DT, was found to increase with increase in Na+ concentration having NO3- or OH- as counter ions, however, above 5 M concentrations of them, Drc remained constant for NaOH while it decreases for NaNO3 due to a strong competitive extraction of NO3- ion compared to OH-. Quantitative stripping of TcO4- was achieved in three consecutive contact of loaded organic with deionized water.