Effect of gamma-ray irradiation at low doses on the performance of PES ultrafiltration membrane

• The fouling properties of PES UF membranes changed after low dose irradiation.
• Membrane surface was hydrophilic modified at even 10 kGy irradiation.
• The flux decreased more at higher dose irradiation due to more pore blocking.
• The depositions on the 75 kGy irradiated membrane were less than the others.

The influence of gamma irradiation on the performance of polyether sulfone (PES) ultrafiltration (UF) membrane was investigated at low absorbed doses (0–75 kGy) using a cobalt source. The performance of the UF membranes was tested using low level radioactive wastewater (LLRW) containing three types of surfactants (anionic, cationic and nonionic surfactants). The physical and chemical properties of membrane surface were analyzed, and relationships between these properties and separation performance and fouling characteristics were determined. At 10–75 kGy irradiation, there were no significant changes observed in the membrane surface roughness or polymer functional groups, however the contact angle decreased sharply from 92° to ca. 70° at irradiation levels as low as 10 kGy. When membranes were exposed to the surfactant-containing LLRW, the flux decreased more sharply for higher dosed irradiated membranes, while flux in virgin membranes increased during the filtration processes. The study highlights that fouling properties of membrane may be changed due to the changes of surface hydrophilicity at low dose irradiation, while other surface properties and retentions remain stable. Therefore, a membrane fouling test with real or simulated wastewater is recommended to fully evaluate the membrane irradiation resistance.