Ultrafiltration removal of U(VI) from contaminated water

Characteristic features of ultrafiltration water treatment and water treatment using ultrafiltration in combination with complexation for water polluted with U(VI) were investigated. Polyethylenimine (PEI) was used as the complexing agent. The relationship of U(VI) removal as a function of pH and the concentration ratio of CPEI/CU(VI) were also studied. It was shown that if no polyelectrolytes were present, the retention coefficient of U(VI) reached 0.91–0.95 at pH 9.0. If polyethylenimine were used in the concentration ratio of CPEI/CU(VI) = 4:1, the retention coefficient using a UPM-20 membrane reached 0.999 at the pH range 5–9. The above values were obtained while using branched structure polyethyleneimine with a molecular mass of 60,000. It was shown that the volume flux drops from 24 to 15 µm/s with increasing pH. The addition of the polyelectrolyte insignificantly changed the volume flux.

Optimal parameters required for UF removal of U(VI): concentration ratio CPEI/CU(VI) and pH were determined, which ensure the retention coefficient of U(VI) removed by a UPM-20 membrane in the range 0.91–0.999. The influence of carbon dioxide on the process of U(VI) removal from a uraniumcontaining solution in the pH range 3–9 was also determined. It was found that the essential influence of carbon dioxide on the process of U(VI) removal was observed at a low pH (3–5). It was shown that an increase in the U(VI) retention coefficient by the UPM-20 membrane resulted from the formation of a layer from uranium complexes on the membrane surface. It was demonstrated that the UF method, both without applying any additional processes and in combination with complexation, is effective for the removal of uranium from contaminated water.