Polyethylene-Supported Thin-Film Nanocomposite Reverse Osmosis Membranes via Oxygen Plasma Pretreatment Modification and Nanotitanium Dioxide Incorporation for Efficient As(V) Removal

In this study, the combination of two surface modification approaches, including oxygen plasma pretreatment plus nanotitanium dioxide (TiO₂) incorporation, was investigated in the preparation of the a PE-supported thin-film nanocomposite (TFN) RO membrane through interfacial polymerization between 1,3-phenylenediamine (MPD) and trimesoyl chloride (TMC) monomers for efficient As(V) removal. Analyzation of the fabricated membrane was conducted via atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), attenuated total reflection-flourier transform infrared (ATR-FTIR) analyses, surface ζ-potential, and water contact angle measurement. Water permeation, desalination performance, As(V) removal efficiency, and antifouling properties of the membranes were examined in the cross-flow filtration setup. The obtained results showed that oxygen plasma pretreatment of the PE support tailored the inherent hydrophobicity of the PE support via inducing oxygen-containing surface groups, which facilitate the PA active layer formation. Furthermore, the incorporation of various concentrations (0.0025-0.02 wt %) of TiO₂ as the hydrophilic additive in the matrix of the PA active layer resulted in an increase of membrane hydrophilicity and negative surface charge. The p-PE/TiO₂ 0.01 optimum membrane indicated the maximum pure water flux of 75.0 L m^-2 h^-1 at 15 bar, and superior desalination performance of 98.8, 99.5, and 99.8% rejection for NaCl, MgSO₄, and Na₂SO₄ salt solutions, respectively, along with incredible As(V) removal efficiency of 100%, which confirmed a remarkable betterment of optimum membrane performance compared with the p-PE membrane. The assessment results of the antifouling ability of the prepared membranes demonstrated that the p- PE/TiO₂ 0.01 TFN-RO membrane indicated the highest fouling resistance with a flux loss of 10% after 48 h of filtration of the BSA/NaCl solution.