Investigation of Performance of Commercially Available Nanofilter Membranes in Selective Separation of Uranium (VI) Ions from Iron (III)

Performance of Three commercially available nanofilter membranes (PES-2 , NF-1 and NF-2) in terms of rejection, permeate flux, and membrane selectivity under a variety of operational conditions was evaluated for selective separation of uranium (VI) ions from iron (III). The membranes permeate fluxes were  decreased with an increase in the pH range of 3-6, while the rejection of ions was increased. Uranium rejection with these membranes was lower than iron rejection and the PES-2 and NF-1 membranes had the maximum membrane selectivity of iron over uranium at pH 4. The maximum membrane selectivity of NF-2, however, was 2.97 at pH 3. The PES-2 membrane had the maximum iron rejection of 72.25% at the pressure 10 bar. For NF-1 the rejection of iron and uranium was found to be relatively constant (about 97% and 84%, respectively) against increasing the pressure. As the pressure increased from 5 to 20 bar, iron rejection by NF-2 was remained constant (about 97%) but uranium rejection by this membrane was decreased from 84.06% to 70.46%. It was found that the effect of increasing the iron concentration from 0.12 to 1mM on the behavior of these membranes is  different. The maximum membrane selectivity of uranium over iron by the NF-1 and NF-2 membranes was 43.71 and 13.59, respectively, which showed that NF-1 has a very desirable performance. It seams that the relatively new process of nanofiltration has a good potential for selective separation of uranium from iron.