Treatment of radionuclide-containing wastewater using thin film composite reverse osmosis membrane with spray coating-assembled titania nanosheets

Reverse osmosis (RO) process is a promising technology for treating radionuclide-containing wastewater owing to its reliability and effectiveness in ion separation. The long-term stability of RO membranes in terms of water flux and radionuclide rejection is a crucial factor for their practical application. In this study, thin film composite (TFC) RO membrane with high long-term stability and antifouling properties for radionuclide-containing wastewater treatment was developed by spray coating the surface of polyamide (PA) layer with oppositely charged titania nanosheets (TNS). Caesium ion (Cs⁺) as model radionuclide was used to assess the RO performance of the manufactured membranes, including permeability and radionuclide rejection The highest permeability of 1.53 L·m⁻²·h⁻¹·bar⁻¹, which was 45.8 % higher than that of neat TFC membrane, was achieved by thin film nanocomposite (TFN) membrane sprayed-coated with 15 ppm TNS bilayer. Compared to TFC membrane which exhibited CsCl rejection of 99.32 %, the rejection of all TNS spray-coated TFN membranes was improved to almost complete rejection. During the long-term testing, the optimum TFN/TNS(15) membrane demonstrated well-retained water flux and ion rejection. The roles of the TNS bilayer in improving the long-term stability and antifouling properties are discussed. The findings of this study highlight the potential of a tailored TFC RO membrane in treating radioanuclide-containing wastewater.