Surface hydrophilicity modification of thin-film composite membranes with metal−organic frameworks (MOFs) Ti-UiO-66 for simultaneous enhancement of anti-fouling property and desalination performance

• A new type of hydrophilic Ti-UiO-66 MOFs for FO membranes application is developed; • The optimized membrane shows 92.6% increase water flux than the benchmark; • The Ti-UiO-66 modified FO membranes show good desalination performance; • The Ti-UiO-66 modified FO membranes exhibit satisfactory anti-fouling abilities. State-of-the-art desalination membranes are highly-related to the thin-film composite (TFC) type design, which usually based on a thin polyamide (PA) separation layer obtained by interfacial polymerization (IP) reaction on a thick support layer. However, the development of PA-TFC desalination membranes were limited by the well-known trade-off between water permeability and NaCl rejection as well as fouling issue. Traditional hydrophilic inorganic nano-modifiers would mitigate these two issues while deteriorating membrane selectivity even triggering second-pollution to environment due to their low compatibility between inorganic materials and organic membrane bulk. Herein a bifunctional PA-TFC membrane modified by metal−organic frameworks (MOFs) Ti-UiO-66 was developed for simultaneous enhancement of anti-fouling property and desalination performance. Compared to the control PA-TFC membrane and the traditional MOF (UiO-66) modified TFC membrane, the optimised Ti-UiO-66 modified TFC membranes showed not only improved water permeability without sacrificing NaCl rejection after long-term chemical stability tests, but also obviously enhanced anti-fouling properties in forward osmosis process. Moreover, the introduction of Ti-UiO-66 into the PA separation layer of TFC membranes led to a less branched structure and reduced structural parameter ( S value). The membrane performance was supported by ATR-FTIR, XRD, XPS, SEM and water contact angle (WCA) measurements. These results shed lights on a potential route of selecting advanced additives for TFC membranes to achieve enhanced desalination performance and anti-fouling property.