Comparison of polyethersulfone and polyamide nanofiltration membranes for uranium removal from aqueous solution

Dead-end filtration equipment was operated to evaluate the performance of polyethersulfone (PES-2) and polyamide (NF-1 and NF-2) membranes in terms of rejection and permeate flux for treatment of high-concentration uranium solutions under a variety of operational conditions. The optimum pH for uranium rejection using PES-2 was determined 6 while the rejection increased significantly in polyamide membranes with increase of pH. The permeate flux of all membranes increased as the pressure increased from 5 to 20 bar while the uranium rejection by these membranes changed differently. As the feed concentration increased from 75 to 238 mg/l, the uranium rejection by PES-2 decreased. On the contrary, the rejection by NF-1 and NF-2 increased from 57 to 79% and 62 to 98%, respectively. Also, the permeate flux of PES-2 was relatively constant whereas the permeate flux of polyamide membranes declined due to a decrease in the effective membrane pore size and an increase in osmotic pressure. The results showed that the nanofiltration process can be effectively employed for uranium removal from aqueous solutions. (C) 2016 Elsevier Ltd. All rights reserved.