Preparation of a GO/PB-modified nanofiltration membrane for removal of radioactive cesium and strontium from water

In this study, a novel modified nanofiltration (NF) membrane was fabricated to treat radionuclide-contaminated water by incorporation of Prussian blue (PB), graphene oxide (GO) and polyethylene glycol (PEG) into polysulfone (PSf) substrate. In this work, PB provided a large number of adsorption sites for the membrane, GO improved the Donnan effect of the polyamide (PA) layer by enhancing the negative charge, and PEG promoted the uniform dispersion of PB through interparticle electrostatic interaction and steric hindrance while increasing the adsorption sites on the surface of channels in the substrate by adjusting the pore structure. A conceptual model for the role of substrate in interfacial polymerization was then proposed. The modified membrane achieved efficient rejection of cesium (Cs+, 99.5%) and strontium (Sr2+, 97.5%). Its Cs+ rejection rate still remained high (about 96%) even in the treatment of natural surface water containing various inorganic salts and organic matters. What’s more, the modified membrane exhibited excellent stability in both strong acid solutions and long-term operation. Then, potassium chloride (KCl) solution was applied to regenerate the modified membrane, which achieved high generation rate as compared to traditional acid regenerants. The excellent filtration performance inferred that the novel GO/PB-modified NF membrane holds great application potential for the application of simultaneous removal of radioactive Cs+ and Sr2+ from contaminated water.