The influence of membrane surface properties on the radionuclide mass transfer process in reverse osmosis

Abstract

Reverse osmosis (RO) technology has been playing an increasingly important role in radioactive wastewater treatment. In this study, the influence of membrane surface properties on the trace radionuclide (Cs+) mass transfer process in polyamide RO membrane was investigated. The Cs+ mass transfer process was described using the solute permeability coefficient (B) with the solution-diffusion with defects (SDWD) model. Several modified RO membranes grafted by different polymers were fabricated to provide different properties, including surface charge, surface roughness and hydrophilicity. The results of correlation analyses demonstrated that BCs+ was independent of both the membrane hydrophilicity and surface roughness. In contrast, there was a significant correlation between BCs+ and the membrane surface charge. The zeta potential exhibited a strong correlation with BCs+. BCs+ decreased from (7.78 ± 0.70) × 10−7 to (7.19 ± 2.95) × 10−9 m/s as the zeta potential increased from −43.57 to 21.2 mV. The results of this study indicated that the membrane surface charge of RO membrane played a key role in the radionuclide mass transfer process. Fabricating positively charged RO membranes could significantly obstruct the radionuclide mass transfer process. The results provided fundamental insights into the mechanisms of the radionuclide mass transfer process in the RO membrane, which emphasized the application prospects of membrane surface modification as a method for the treatment of radioactive wastewater.