Micellar-enhanced ultrafiltration (MEUF) process is an alternative separation technology that employs surfactant micelles to solubilize inorganic and organic pollutants from the effluent stream. The aim of this study was to investigate the potential of this process in the removal of free active chlorine (FAC) from synthetic wastewater using polyethersulfone/titania (PES/TiO2) nanocomposite membrane. To achieve this objective, investigation was done in terms of stable permeate flux (SPF) and hypochlorite rejection efficiency (HRE) behavior of fabricated membrane, with and without hexadecyl trimethyl ammonium bromide (CTAB) as a cationic surfactant. The effects of various parameters including TiO2 nanoparticle concentration, operating time, transmembrane pressure (TMP), CTAB concentration, pH of feed solution, and feed chlorine concentration on the MEUF process performance were investigated. The results showed that ionic strength (CATB or FAC concentrations) and solution pH play different and significant role on the performance of the process. So that, SPF decreases when ionic strength of the aqueous media increases. As the pH of the solution increased, the SPF and HRE increased and decreased, respectively. The rejection efficiency increased by increasing in both TMP and nanoparticle concentration, while it was in reverse relationship with the feed chlorine concentration. According to the results, in the case of CTAB surfactant concentration, concentration polarization phenomenon is more effective than micelle formation on MEUF performance. All in all, MEUF by PES/TiO2 nanocomposite membrane has appropriate retention of FAC especially under acidic condition (pH: 2–4), as the rejection was around 75.0%. It is also clear that using TiO2 nanoparticles and cationic surfactant are useful additives in chlorine removal from wastewater and their suitable concentration are around 1.5 wt% and 0.92 mM, respectively.

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