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Reverse osmosis (RO) is a well-established and reliable desalination method that has been widely implemented on a commercial scale to resolve water scarcity issues. Constant efforts have been made to develop thin film composite membranes that can strike a balance between selectivity and permeability, while maintaining high durability towards fouling and chlorine attack. In this work, the surface of thin film composite RO membrane was modified by complexing tannic acid (TA) and silver nanoparticles (Ag NPs). TA was used for enhancing the chlorine resistance while Ag NPs act as a biocide to mitigate biofouling. Upon the formation of PA layer through interfacial polymerization, TA was chemically grafted, proceeded by in-situ reduction of Ag NPs. Transmission electron microscopy (TEM) image revealed that Ag NPs were deposited on top of the TA-PA interlayer and reduced as discrete spherical Ag NPs with diameter <15 nm. The greatest flux of 20.57 L/m2·h was produced by TFC-TA/Ag1, representing a 60 % improvement as compared to neat TFC membrane. The NaCl rejection of TFC-TA membrane was 97.83 %, which was slightly increased compared to neat TFC membrane with rejection of 95.14 %. Improved chlorine resistance and improved antibacterial properties against Gram-positive bacteria (S. aureus) and Gram-negative bacteria (E. coli) were witnessed for the TFC-TA/Ag1 membranes. This study demonstrates a facile chemical grafting and deposition to introduce multiple functionalities for improving the physical and separation properties of TFC RO membrane. [Display omitted] • Complexation was made by directly grafting TA followed by in-situ formation of Ag NPs on PA layer. • The surface modified TFN membrane exhibited enhanced flux and salt rejection. • The chlorine resistance and anti-biofouling properties of the TFN membrane were significantly improved. [ABSTRACT FROM AUTHOR]

The tailoring of the physico-chemical properties of thin film composite (TFC) membranes is essential to augment their separation performances. Maintaining a good balance between water productivity and rejection is one of the important criteria for efficient water treatment. This work reports a nanomaterial-enabled templating strategy used for the construction of a TFC substrate layer. Beta ferric oxy-hydroxides (β-FeOOH) nanorods were used as a pore forming template for polysulfone (PSf) substrate. The templating strategy using β-FeOOH nanorods increased the porosity and pore space connectivity of the PSf substrate, hence facilitating the formation of homogenous and defect-free polyamide selective layers through interfacial polymerization (IP) on top of the PSf substrate. The best membrane, a-TFC β2 which was fabricated using etched PSf substrate preloaded with 1 wt% β-FeOOH exhibited an increase in water permeance by 3-fold compared to the neat TFC membrane while maintaining NaCl rejection of 97.5%. Furthermore, the templating strategy endowed the membrane with better 72 h operational stability, where the water permeance and selectivity were not much deteriorated compared to that of neat membrane. This study demonstrates the feasibility of using substrate templating technique to finetune the porosity and surface pore properties for an optimized IP reaction and hence, enhancing the desalination performance. [Display omitted] • FeOOH nanorods as templating agent were synthesized via hydrothermal route. • Correlation between the substrate's properties and PA properties was investigated. • Porosity and surface features of substrates influenced the formation of PA layer. • a-TFC β1 displays better desalination performance with a stable long-term testing. [ABSTRACT FROM AUTHOR]

• Zeolitic imidazolate framework 8 (ZIF-8)–graphene oxide modified with amine groups via post modification. • The fabricated membranes have a good antibacterial and antifouling properties. • The membranes an exhibits strong antibacterial activity against E. coli and S. aureus bacteria. • Antibacterial mechanism of the membrane was proposed. Biofouling is an inevitable obstacle that impairs the overall performance of polymeric membranes used in water and wastewater treatment. This research focuses on the development of a novel nanocomposite membrane incorporating an antibacterial agent which has the potential to diminish membrane biofouling. An antibacterial agent, zeolitic imidazole framework-8 decorated with graphene oxide (ZGO), was functionalised with amino groups via direct post-modification method using ammonium hydroxide solution. The modified sample was then incorporated into polyethersulfone (PES) matrix at different weight loadings to produce ultrafiltration hollow fibre membranes by phase inversion method. The surface hydrophilicity and roughness of the membrane were improved with additional incorporation of ZGO–NH. The filtration results indicate that the permeation properties of the composite membranes were significantly improved compared to unmodified PES membranes. The water flux of the composite membranes increased with increasing ZGO–NH amount. The optimum value of ZGO–NH content is 1.0 wt%, in which the water flux reached the maximum value at 95.49 L/m2 h, 64.0% higher than that of neat PES membrane while maintaining BSA rejection of >95.0%. Moreover, the modified membranes also exhibited impressive antifouling properties with a flux recovery ratio (FRR) of 84.4% which is significantly higher than that of unmodified PES membranes (57.1%). The composite membrane possessed antibacterial capability against Escherichia coli and Staphylococcus aureus , having an antibacterial rate of 81.1% and 85.7%, respectively. Our proposed approaches show an excellent antibacterial ultrafiltration membrane to overcome biofouling issues via membrane modification. [ABSTRACT FROM AUTHOR]