Ozone compatibility with polymer nanofiltration membranes

Ozone is a strong oxidant applied in water treatment for disinfection and organic inorganic pollutants removal. It can be coupled with membrane processes as pre-treatment or post-treatment well hybrid configuration. In this study, we investigated the resistance of three commercial polymer nanofiltration membranes (NP10, NF90 NF270) contact ozone (10 ppm 1 h) at pH 3 7 to assess influence hydroxyl radical concentrations balance. The surface properties were characterized before after ozonation by means various techniques, i.e. Fourier transform infrared spectroscopy attenuated total reflectance mode (ATR-FTIR), zeta potential, angle, X-ray photoelectron (XPS), atomic force microscopy (AFM) scanning electron (SEM). For all membranes, impact on pure permeability was greater than due faster decomposition leading formation more free radicals. A decrease NP10 (up 25%) obtained ozonation. ATR-FTIR, potential SEM revealed fairly good polyethersulfone (PES) matrix (thanks protective effect electron-withdrawing sulfone groups) under exposure conditions study but polyvinylpyrrolidone (PVP) additive substantially oxidized. XPS indicated that degraded PVP not released from PES matrix. suggested might result cross-linking process between macroradicals chains. contrast what observed membrane, thin-film composite polyamide (PA) dramatically increased fully aromatic appeared even sensitive semi NF270. different resistances NF270 attributed amine monomers used synthesis their active layer. Indeed, m-phenylenediamine interfacial polymerization layer an (aromatic rings are ozonation) less basic non-aromatic piperazine develop (protonation amines contributes protect them electrophilic attacks). both PA ATR-FTIR severely damaged layers. very sharp increase permeabilities removal fragments, which found compatible angle measurements.