Aqueous solutions of water-structuring, kosmotropic salts (e.g., salts of PO43-, HPO42-, CO32-) will salt-out water-destructuring chaotropic ionic liquids (ILs) (e.g., 1-butyl-3-methylimidazolium chloride, ([C(4)mim]Cl)) forming salt/salt aqueous biphasic systems (ABS). The chaotropic pertechnetate (TcO4-) anion will partition without the use of an extractant into the IL-rich phase. These complex salt/salt ABS are not unlike the complex and salt-rich Hanford tank waste, and thus have been used here as a simple model to show effectiveness in the partitioning of TcO4- from such tank waste into an IL-rich phase.