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Poly(N-isopropylacrylamide) (PNIPAAm) was introduced into a polyethylene terephthalate (PET) nonwoven fabric to develop novel support for polyamide (PA) thin-film composite (TFC) membranes without using a microporous support layer. First, temperature-responsive PNIPAAm hydrogel was prepared by reactive pore-filling to adjust the pore size of non-woven fabric, creating hydrophilic support. The developed PET-based support was then used to fabricate PA TFC membranes via interfacial polymerization. SEM–EDX and AFM results confirmed the successful fabrication of hydrogel-integrated non-woven fabric and PA TFC membranes. The newly developed PA TFC membrane demonstrated an average water permeability of 1 L/m2 h bar, and an NaCl rejection of 47.0% at a low operating pressure of 1 bar. The thermo-responsive property of the prepared membrane was studied by measuring the water contact angle (WCA) below and above the lower critical solution temperature (LCST) of the PNIPAAm hydrogel. Results proved the thermo-responsive behavior of the prepared hydrogel-filled PET-supported PA TFC membrane and the ability to tune the membrane flux by changing the operating temperature was confirmed. Overall, this study provides a novel method to fabricate TFC membranes and helps to better understand the influence of the support layer on the separation performance of TFC membranes. [ABSTRACT FROM AUTHOR]

Incorporation of functional nanoparticles in polymer membranes is a promising approach for the development of advanced thin film nanocomposite (TFN) membranes with improved desalination performance. This study was aimed to fabricate TFN membranes incorporated with functionalized silica nanoparticles (SNs), which were synthesized with different sizes (~50 and ~100 nm) and surface functionalities (hydroxyl, epoxy and amine). Research focused on getting a better understanding of the interfacial interactions between SNs and polymer matrix and structure-property correlation of the TFN membranes. The physicochemical properties of the functionalized SNs and the TFN membranes were characterized using ATR-FTIR, TGA, DLS, SEM, TEM, XPS, tensiometer and streaming potential analysis. The results confirm successful incorporation of the surface functionalized SNs into the polymer membranes. The concentration, size and surface functionality of SNs were found to have strong impact on the surface hydrophilicity, morphology and chemistry of the TFN membranes. The SNs hybridized TFN members showed increased permeate flux and insignificant change in salt rejection. The surface functionalization of SNs with amine and epoxy moieties could facilitate the chemical interaction between SNs and polymer monomers, resulting in stabilizing the TFN membranes. Our research outcomes have provided new insight into the structure-performance correlation of TFN membranes and can be beneficial for fabrication of a wide range of nanoparticle incorporated membranes. [ABSTRACT FROM AUTHOR]

Thin film composite (TFC) membranes are the most commonly used polymeric membranes in desalination process. The membrane properties and performance are dominated by many fabrication parameters, including chemistry of polymers and synthesis conditions. This study was aimed to develop an integrated statistic-systematic approach to study the correlation between fabrication condition and desalination performance of the TFC membranes. Three key fabrication factors: polysulfone concentration, aqueous phase soaking time and heat curing time were statistically analysed to determine their optimal values and interactional influence on desalination performance. The desalination performance was systematically evaluated based on permeate flux and salt rejection. It is expected that statistic results can facilitate the understanding of synthesis-performance correlations of TFC membranes. Two mathematical models for correlating fabrication factors with permeate flux and salt rejection were developed. The most influential correlations were identified as the polysulfone concentration - permeate flux and soaking time - salt rejection. Interaction of soaking time with polysulfone concentration and curing time was determined to have significant impact on the salt rejection. Our findings highlighted the importance of considering interactions between the fabrication conditions and desalination performance when devising a strategy to fabricate TFC membranes for maximising desalination performance. [ABSTRACT FROM AUTHOR]

Thin film composite (TFC) membranes incorporated with inorganic nanoparticles into the polyamide layer have recently gained great research interests. However, the incompatibility of introduced nanoparticles and their instability in the TFC membranes are the main challenges. It has been questioned that how the hybridized nanoparticles could sustainably enhance the overall desalination performance within the complex filtration mechanisms in terms of water permeability and salt rejection, as well as mechanical strength of the membranes. Herein, hydrophilic polyethylenimine (PEI) modified silica nanoparticles (SN), noted as SN-PEI, are synthesized with the aim to fabricate SN-PEI hybridized thin film nanocomposite (TFN) membranes for desalination. The successful incorporation of SN-PEI into the TFC membranes is confirmed through characterization techniques. The functional SN-PEI showed promising chemical characteristics to enhance interfacial molecular interactions between the SN and polymer matrix which improve the compatibility of SN with the polymer structure and the mechanical properties of the TFN membranes. Higher hydrophilicity of the TFN membranes due to the SN-PEI incorporation is beneficial for enhancing water molecular transfer through the membrane. Our experimental and statistic data revealed that the SN-PEI hybridized TFN membranes demonstrated up to 46% improvement in water flux, higher salt rejection, and improved mechanical strength compared to the control TFC membranes. Higher hydrophilicity of the TFN membranes due to the SN incorporation is beneficial for enhancing water molecular transfer and antifouling resistance for cost reduced desalination. [ABSTRACT FROM AUTHOR]

Thin film composite (TFC) polyamide membranes have been predominantly utilized in water treatment and desalination and play a significant role in the separation processes. However, the occurrence of fouling, especially biofouling, has a detrimental effect on the efficiency of the membrane. The introduction of nanostructures and other surface modification strategies has paved the way for developing antibacterial TFC membranes, aiming to control and mitigate biofouling to achieve a rational design for practical applications. This comprehensive review introduces and discusses novel antibacterial TFC membranes, including their structure, composition, and performance. Additionally, particular attention is given to understanding the antibacterial mechanism of nanomaterials. To this end, various emerging and prevalent antibacterial nanomaterials are introduced, and their role in the fabrication of TFC membranes is overviewed. Moreover, versatile modification strategies are outlined to impart antibacterial activity into TFC membranes. Finally, the review proposes current challenges and prospects of antibacterial TFC membranes, aiming to provide valuable insights for developing advanced TFC membranes with optimal resistance against biofouling and improved separation performance. This critical review serves as a fundamental guide for designing strategies that surpass the current limitations of TFC membranes' antibacterial agents and nanomaterials, thereby mitigating the tendency of biofouling through tailored membrane surface properties. [Display omitted] • Explores biofouling complexities; implications discussed • Strategies for antimicrobial activity; enhance antibiofouling • Summarizes antibacterial agents; focusing on control mechanisms • Explores TFC membrane modification for antibacterial activity • Versatile applications of antibacterial TFC membranes and elaborates on challenges and future prospects [ABSTRACT FROM AUTHOR]

The recent advancements in fabricating forward osmosis (FO) membranes have shown promising results in desalination and water treatment. Different methods have been applied to improve FO performance, such as using mixed or new draw solutions, enhancing the recovery of draw solutions, membrane modification, and developing FO-hybrid systems. However, reliable methods to address the current issues, including reverse salt flux, fouling, and antibacterial activities, are still in progress. In recent decades, surface modification has been applied to different membrane processes, including FO membranes. Introducing nanochannels, bioparticles, new monomers, and hydrophilic-based materials to the surface layer of FO membranes has significantly impacted their performance and efficiency and resulted in better control over fouling and concentration polarization (CP) in these membranes. This review critically investigates the recent developments in FO membrane processes and fabrication techniques for FO surface-layer modification. In addition, this study focuses on the latest materials and structures used for the surface modification of FO membranes. Finally, the current challenges, gaps, and suggestions for future studies in this field have been discussed in detail. [Display omitted] • The existing challenges in traditional forward osmosis (FO) membranes are discussed. • Surface modification of FO membranes (e.g., surface grafting and coating) are evaluated. • Remarkable flux improvements (ranging from 17% to 80%) have been reported for surface modified FO membranes. • Novel additives and biomimetic membranes are evaluated for FO membranes' surface tailoring. • The influence of nanochannels on the performance of FO membranes is investigated. [ABSTRACT FROM AUTHOR]

Thin film composite (TFC) membranes have been experiencing significant modifications recently aiming to improve their structure, properties and separation efficiency. One of the promising modifications to tailor the membranes more efficient is changing the materials used. m -phenylene diamine (MPD), piperazine (PIP), and trimesoyl chloride (TMC) are the most common monomers used to fabricate TFC membranes. Recent studies have introduced several alternatives to these traditional monomers showing significant contribution of these monomers to the physicochemical properties of the membranes (e.g., surface roughness, hydrophilicity, cross-linking density, chemical structure) as well as membranes' separation efficiency. Emergence of more favorable functional groups such as carboxylic and amine groups due to the new materials integration facilitates the polymerization process and is beneficial to the membrane properties. Here, a critical review on the new interfacial polymerization monomers applied for reverse osmosis (RO) and nanofiltration (NF) membranes fabrication is presented. The membrane molecular structure and fabrication mechanism are investigated in details. This is followed by a review of the recent surface modification methods including grafting, coating and additive incorporating into the thin layer of membranes. The application of alternative monomers to MPD, PIP and TMC are investigated and the benefits of using these monomers or co-monomers are discussed. [Display omitted] • Review of new monomers used for RO and NF membranes fabrication. • Review of alternative monomers to MPD, PIP and TMC. • Review of benefits of using new monomers as co-monomers of MPD, PIP and TMC. [ABSTRACT FROM AUTHOR]