text: DEHPA is used in the solvent extraction of uranium salts from solutions containing the sulfate, chloride, or perchlorate anions.  This extraction is known as the “Dapex procedure” (dialkyl phosphoric extraction).  Reminiscent of the behaviours of carboxylic acids, DEHPA generally exists as a hydrogen-bonded dimer in the non-polar organic solvents.  For practical applications, the solvent, often called a diluent, is typically kerosene.  A complex is formed from two equivalents of the conjugate base of DEHPA and one uranyl ion. Complexes of the formula (UO)[(OP(OR)] also form, and at high concentrations of uranium, polymeric complexes may form.
  The extractability of Fe is similar to that of uranium, so it must be reduced to Fe before the extraction.