ABSTRACT It first shows the main sources of lithium deposits, and then illustrates a forward osmosis (FO) membrane process for lithium recovery. The rapid expansion of the lithium economy, driven by increasing demand for batteries and renewable energy storage, has established lithium as a critical resource in modern technologies. This growing reliance highlights the urgent need for sustainable separation systems to meet future supply demands. This study presents the advantages of forward osmosis (FO) membranes for lithium extraction, examining key factors influencing their performance and recent advances in membrane design, material development, and operational strategies. The performance of FO membranes is critically evaluated, with emphasis on the mechanisms governing selective Li+ separation from competing ions in complex feed solutions. Various membrane modification approaches, including functional polymers, nanomaterials, and optimized draw solutions, are discussed in relation to their influence on water flux, ion selectivity, and overall separation efficiency. These strategies have demonstrated improvements in FO membrane performance for lithium recovery, although their effectiveness depends strongly on membrane structure, material properties, and operating conditions. Compared with nanofiltration, FO membranes can achieve comparable Li+/Mg2+; selectivity under significantly lower hydraulic pressures, offering notable energy-saving potential. This work also outlines current challenges and proposes future research directions toward achieving efficient, scalable, and environmentally sustainable FO-based lithium recovery systems.

There have been ongoing efforts to improve membrane surfaces by adding specific functional groups through physical or chemical approaches to minimize fouling propensity. This study introduces a facile grafting and deposition approach to enhance the performance of thin film composite polyamide reverse osmosis (TFC PA RO) membrane. The synergistic effects of L-glutamine and Cu nanoparticles in altering the physico-chemical properties and improving desalination performances were investigated. The L-glutamine improved the hydrophilicity of membrane, while Cu NPs offered significant antibacterial characteristics to improve the functionality of membrane. The findings revealed that TFC-L-glutamine/Cu3 showed optimum performance with water flux of 16.5 L.m- 2 h- 1 and salt rejection of 96.8 % at an operating pressure of 1.5 MPa. The TFC-L-glutamine/Cu3 membrane exhibited an absence of dense colonies against both S. aureus and E. coli, on account of the antibacterial effectiveness of Cu NPs. The S. aureus- and E. coli-fouled TFC-L-glutamine/Cu3 membrane showed the lowest flux decline of 20 % and 25 % for, respectively. The TFC-L-glutamine/Cu3 membrane exhibited promising antifouling performance, with a flux recovery ratio (FRR) of 95.2 % for bovine serum albumin (BSA) foulants. The TFC-L-glutamine/Cu3 membrane exhibited a low copper leaching of <= 3 %, suggesting its high stability. The modification strategy demonstrated in this study provides a feasible solution to simultaneously address multiple issues of TFC RO membranes, which potentially leading to more efficient desalination.

Biofouling, a prevalent issue in membrane technology, compromises the effectiveness and efficiency of membrane-based separation processes. The bottleneck prompts significant research into improving the antibacterial and antibiofouling characteristics of membrane. This review seeks to offer a thorough analysis and discussion on the utilization of biomolecules such as polysaccharides, fatty acids and enzymes for developing antibacterial and antibiofouling membranes. This review discusses the properties, advantages, and limitations of employing antibacterial biomolecules, along with their development and performance in membrane applications. A comprehensive elaboration is crucial to grasp the potential of these antibacterial biomolecules in enhancing membrane performance. This review is expected to offer insights into how these antibacterial biomolecules can optimize membrane performance by reducing biofouling, enhancing operational efficiency, ensuring water quality, and lowering costs. This review concludes that antibacterial polysaccharides and enzymes can serve as promising candidate to enhance the antibacterial properties of membranes. The review also addresses challenges and outlines future research directions concerning antibacterial biomolecules. The future directions outlined in the review focus on striking a balance between achieving strong antibacterial action and preserving essential membrane surface properties, thereby encouraging the creation of eco-friendly environment.

Contemporary high-efficiency polyamide (PA) membranes are constructed using aliphatic or aromatic amines combined with acyl chlorides. Nevertheless, the aromatic rings attached to the N–H group within the amide linkages are vulnerable to degradation by chlorine. The surface of a PA reverse osmosis (RO) membrane was altered in this work through the dual functionalization of tannic acid (TA) and silver nanoparticles (Ag NPs) to improve separation performance, chlorine resistance, and anti-bacterial capabilities of membranes. This study provides an insight in the role and synergistic effects of TA and Ag NPs for enhancing the chlorine resistance of the modified TFC membranes. The outcome indicated that the RO-TA/Ag modified membrane exhibited the maximum rejection of 98.31%, slightly surpassing the pristine RO membrane, which had a rejection rate of 96.52%. The RO-TA/Ag modified membrane also shown improved chlorine tolerance against 500 ppm sodium hypochlorite solution (NaClO), as evidenced by X-ray photoelectron spectroscopy (XPS) measurement which revealed reduced chlorine content in contrast to pristine RO and RO-TA membrane. The RO-TA/Ag membrane exhibited the largest inhibitory zone for both Gram-positive, S. aureus and Gram-negative, E. coli bacteria. The synergistic effects of the dual functionalization of TA and Ag NPs which render the modified membrane with high anti-chlorine and anti-bacterial capabilities are discussed.

The study on the state-of-art desalination membranes related to their fundamental structure, property and performance has been sparked by the demand for commercially attractive high-performance membranes. In this study, the surface of polyamide (PA) reverse osmosis (RO) membrane was modified by integrating tannic acid (TA) and silver nanoparticles (Ag NPs) to increase the water flux, anti-biofouling and antifouling properties of the membrane. The anti-biofouling properties was optimized by varying the duration required for the in-situ formation of Ag NPs on the surface grafted TA. The findings revealed that the PES/PA-TA-Ag(20 min) membrane prepared from the in-situ reduction of Ag precursor for 20 min exhibited the maximum flux of 20.56 L/ m(2)center dot h. The PES/PA-TA-Ag(40 min) membrane also demonstrated increased antibacterial ability as proven by an increase in the number of dead bacteria (48 +/- 1.71 mu m(3)/mu m(2)) and a reduction in biofilm thickness (1.6 +/- 0.12 mu m) for E. coli. The antifouling performance of the SA-fouled PES/PA-TA-Ag(40 min) membrane is appealing, with higher FRR of 98.05 % observed. The PES/PA-TA-Ag(40 min) membrane showed minimal silver leaching of <= 2.5 % and reduced flux loss of 25 % upon filtration. The facile surface modification through complexation of TA

Biofouling is a critical concern in reverse osmosis as it significantly deteriorates the efficacy of the treatment processes. A biofouling assessment technique offers an insight into the mechanisms and severity of biofouling in the reverse osmosis membrane. This review provides an in-depth overview and discussion on both conventional and advanced biofouling evaluation techniques employed in reverse osmosis membranes. An overview of the fundamental principles, biofouling mechanisms, impacts, and prevention strategies for reverse osmosis biofouling are first briefly discussed. Conventional and advanced biofouling assessment techniques are compared and contrasted in terms of their features, benefits and shortcomings. The conventional biofouling technique is a widely utilized biofouling approach due to its versatility and ease of use. On the other hand, advanced biofouling approaches provide a comprehensive, real time and accurate biofouling monitoring. Specifically, by detecting the early onset of biofouling and assessing its severity, advanced biofouling assessment methods allow timely cleaning to mitigate further fouling and improve the overall performance. The challenges and future research directions in this area are also highlighted.

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.

Surface modification of membranes is an effective approach for imparting unique characteristics and additional functionalities to the membranes. Chemical grafting is a commonly used membrane modification technique due to its versatility in tailoring and optimizing the membrane surface with desired functionalities. Various types of polymers can be precisely grafted onto the membrane surface and the operating conditions of grafting can be tailored to further fine-tune the membrane surface properties. This review focuses on the recent strategies in improving the surface design of liquid separation membranes through grafting-from technique, also known as graft polymerization, to improve membrane performance in wastewater treatment and desalination applications. An overview on membrane technology processes such as pressure-driven and osmotically driven membrane processes are first briefly presented. Grafting-from surface chemical modification approaches including chemical initiated, plasma initiated and UV initiated approaches are discussed in terms of their features, advantages and limitations. The innovations in membrane surface modification techniques based on grafting-from techniques are comprehensively reviewed followed by some highlights on the current challenges in this field. It is concluded that grafting-from is a versatile and effective technique to introduce various functional groups to enhance the surface properties and separation performances of liquid separation membranes.