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Controlling the physical properties of interfacial polymerization (IP) plays a crucial role in tailoring the structures and properties of thin-film composite (TFC) membranes. However, due to the instantaneity and complexity of the IP reaction, it is challenging to determine the mechanism of the process and establish the connection between the synthesis-structure-performance. For the first time, novel characterization techniques that researchers have employed to visualize the IP reaction in real-time and several classical theoretical models for computer simulations of the IP process are discussed to reveal the intrinsic mechanisms of the IP process from the microscopic perspective. Furthermore, this paper also illustrates the latest effective strategies of IP technology to regulate the permeability and selectivity of membranes from a macroscopic perspective. The above discussion is vital to illustrate the synthesis-structure-performance relationships of TFC membranes, and is conducive to breaking the trade-off effect between permeability and selectivity. Finally, we highlight the potential and challenges of using the IP technology to synthesize TFC membranes for targeted separation applications. This review addressed the urgent need for comprehensive research on the IP process and provides a strong foundation for the advancement and improvement of polyamide (PA) membranes. [Display omitted] • The application of visualization technologies for observation the interfacial polymerization (IP) proceess are described. • Classical computer theoretical models for the IP process simulation are summarized. • Multidimensional regulation of the IP technology is outlined for properties of thin-film composite (TFC) membranes. • The challenges and prospects in tailoring high-performance TFC membranes with the IP technology is presented. [ABSTRACT FROM AUTHOR]

Industrial production and human activities have resulted in significant oil pollution issues. The utilization of electrospinning nanofibrous membranes for the separation of oil-water mixtures and emulsions has been widely adopted. However, these membranes face challenges due to their low flux and membrane fouling. In this study, we conducted a chemical modification on a novel cross-electrospinning material, amidoximated polyacrylonitrile-regenerated cellulose acetate (AOPAN-RC), through deacetylation and ammoximation conversions. This modification led to the development of a superhydrophilic and antifouling composite membrane with excellent properties. The modified composite nanofibrous membranes exhibited remarkable hydrophilicity and strong underwater superoleophobicity, indicated by an underwater oil contact angle of 157.5° ± 1.24°, as well as a high water flux value exceeding 6000 LMH. The AOPAN-RC membranes demonstrated exceptional performance in separating highly emulsified surfactant-free and surfactant-stabilized oil-in-water emulsions, achieving separation efficiencies of over 94 ± 0.8 % and 90 ± 1.1 %, respectively. Furthermore, we discovered that higher water flux and improved emulsion separation efficiency can be achieved under low pH and ionic strength conditions with minimal addition of surfactants. Moreover, due to its superior antifouling property, the membrane enables long-term separation of high-viscosity oil-in-water emulsions and actual oily wastewater under various solution conditions. Notably, the flux of the AOPAN-RC membrane did not decrease significantly, making it significantly better than the PAN-CA and PAN-RC membranes. Additionally, the separation efficiency of the AOPAN-RC membrane also surpassed that of the other two. While the presence of surfactant-surrounded oil droplets may cause irreversible fouling over time, this innovative nanofibrous membrane exhibits great potential for practical applications in the treatment of a wider range of oil-contaminated wastewater sources. [Display omitted] • High flux, stable oil rejection efficiency and gravity-driven separation ability obtained. • Excellent membrane antifouling property and reusability under different emulsion solution conditions • Efficient separation performance in treating real oily wastewater over an extended duration. • Surfactant exacerbates the membrane fouling and facilitates the passage of oil droplets. [ABSTRACT FROM AUTHOR]

In this study, we focused on the effective disposal of radioactive wastewater through the development of nanofiltration membranes using biomass materials. We developed functionalized nanofilms using a bio-derived polymer for the decontamination of nuclear wastewater. The synthesis involved a straightforward interfacial polymerization (IP) process, followed by post-functionalization with polyethyleneimine (PEI). We investigated the impact of curdlan self-assembly on membrane separation performance, both pre- and post-IP reaction. Simultaneous self-assembly of curdlan and PEI grafting led to membranes exhibiting superior separation performance. By manipulating PEI molecular weights, we optimized the membranes' physicochemical properties, leading to superior separation efficiency. As a result, exceptional rejections of Co2+, Sr2+, and Cs+ ions were achieved, with rejection rates reaching 95.5 %, 93.7 %, and 92.54 %, respectively. Furthermore, long-term stability experiments validated the membrane's potential for purifying nuclear wastewater. These findings hold promise for the application of biomaterial-based membranes in the treatment of radioactive nuclear wastewater. [Display omitted] • Curdlan with self-assembly properties was applied as an aqueous phase to regulate the interfacial polymerization process. • Polyethyleneimine (PEI) post-functionalization were introduced to tune the surface charge and pore size of the TFC membranes. • The novel positively-charged TFC membranes exhibited excellent nuclear wastewater sieving ability. [ABSTRACT FROM AUTHOR]

Porous organic cages (POCs) have triggered significant interest in the design of molecule/ion sieving membranes owing to the high porosity, distinct window-cavity structure, and distinguished solution processability. In this study, the porous organic cage CC19 was explored as functional porous fillers to regulate the surface properties of thin film nanocomposite (TFN) membranes via interfacial polymerization (IP). The addition of CC19 was found to effectively heighten the porosity of membranes while giving rise to a decline in the crosslinking density of the polyamide film. The cage molecules present in the polyamide layer further are likely to pack in a window-to-window mode, forming interconnected 3D porous networks that serve as channels for efficient separation and rapid water molecule transport. Under the synergy effect of CC19 filler and the polyamide matrix, the composite membrane demonstrated a significantly improved permeability and efficient separation of mono−/divalent salts. As the CC19 content was 0.03 w/v%, the as-prepared CC19-TFN-0.03 membrane evinced an outstanding water permeability of 32.0 L m−2 h−1 bar−1, with comparably high rejection of Na 2 SO 4 (96.4 %). This POC-modulated IP approach offers a guidance for designing high-permeable NF membranes for ion separation. Integration of porous organic cage CC19 with polyamide membranes leads to an increased water permeability while maintain good divalent salt rejection. [Display omitted] • Porous organic cage modulated IP was proposed to construct a new TFN membrane. • The addition of CC19 reduced the crosslinking degree and increased the pore size of PA membranes. • The cage molecules in the PA layer created interconnected porous networks for rapid water transport. • The TFN membranes had an improved water permeance of 32.0 L−1m−2h−1 bar−1 with good Na 2 SO 4 rejection. [ABSTRACT FROM AUTHOR]

Ion selective separations play crucial roles in the fields of energy storage, pollution management, and industrial processes, etc. Ion exchange membranes (IEMs) offer promise for these separations but often lacking the required selectivity. In this work, we have developed a kind of IEM based on metal-organic frameworks (MOFs) to enhance membrane separation performance for electrodialysis (ED). Specifically, for poly(arylene ether sulfone)-based anion exchange membranes (AEMs), we introduced the modified MOFs through doping to create a transport pathway for target ions, leveraging their precise size-based separation effects. This approach significantly improves ion selectivity. Remarkably, at a current density of 2.5 mA·cm−2, the monovalent ion selectivity (Cl−/SO 4 2−) of PAES-UIO-66-Pyr could reach 54.26, while the monovalent ion selectivity (NO 3 −/SO 4 2−) could reach 55.90. These enhancements may stem from the incorporation of MOF particles, which facilitate the formation of fixed-size channel structures within membrane matrix. These fixed-size channels, coupled with the hydrophobic differences between the original poly(arylene ether sulfone) polymer, created a composite channel system that significantly improved the separation performance for monovalent ions, including Cl−/SO 4 2− and NO 3 −/SO 4 2−. [Display omitted] • A kind of MOF-modified cross-linked poly(arylene ether sulfone) AEM has been prepared. • The introduced cross-linked structure increases the density of AIEM. • The perm-selectivities of Cl−/SO 4 2− and NO 3 −/SO 4 2− reached 54.26 and 55.90, respectively. • The incorporation of MOFs could facilitate the formation of fixed-size channel structures. [ABSTRACT FROM AUTHOR]

Creating a gradient structure in a separation layer is an effective approach for enhancing separation performance of thin film composite membranes. Here we present the preparation of a positively charged nanofiltration membrane with a gradient structure. An inner layer consisting of a loose polyester separation layer with large pores was formed through the interfacial polymerization (IP) reaction between triethanolamine (TEA) and trimesoyl chloride (TMC). And a dense and thin top layer composed of a polyamide separation layer was obtained by secondary interfacial polymerization (SIP) reaction using polyethyleneimine (PEI) along with unreacted TMC and residual acyl chloride groups of IP reaction. The influences of TEA concentration, PEI concentration and SIP time on the physicochemical properties and separation performances of the membrane were systematically analyzed. Our results show that the presence of the gradient structure optimized mass transfer pathways and reduced mass transfer resistance, resulting in significantly improved permeability of 13.0 ± 0.5 L·m−2·h−1·bar−1 (over 3 times compared with control-PEI), high MgCl 2 rejection of 91.7 ± 0.6 %, and an excellent stability and anti-fouling performance. Our work provides valuable insights and guidance for developing high-performance positively charged NF membrane with gradient structures. • A positively charged nanofiltration membrane with gradient structure was designed and obtained. • The gradient structure significantly improves the permeability of the nanofiltration membrane (over 3 times). • The T0.2-P0.5–10 membrane exhibits excellent stability and anti-fouling performance. [ABSTRACT FROM AUTHOR]

Membrane technology presents an effective solution for treating oily wastewater, a significant environmental hazard stemming from industries such as food processing, metalworking, and oil extraction. Compared to polymeric membranes, ceramic ones exhibit superior mechanical, chemical, and thermal stability, enabling more effective oil removal and easier cleaning. Despite their advantages, membrane fouling remains a challenge, impacting the efficiency of oily wastewater treatment. This review explores oily wastewater characteristics and ceramic membrane applications in treatment processes. It examines the factors influencing ceramic membrane fouling, including wastewater properties (e.g., oil concentration, pH), membrane characteristics (e.g., surface hydrophilicity, charge), and operational parameters (e.g., cross-flow velocity, permeate flux). Strategies to mitigate fouling, such as pretreatment, backpulsing/backwashing for sustained operation, and chemical cleaning for fouling removal, are discussed. By using pretreatment, membrane fouling can be reduced. Backpulsing/backwashing is effective to maintain a long-term operation. Chemical cleaning is effective in removing irreversible fouling and restoring the performance of the ceramic membranes. Moreover, membrane modification techniques that enhance performance are highlighted. Ultimately, the review identifies that effective fouling control is crucial for optimizing ceramic membrane use in oily wastewater treatment, underscoring the need for ongoing research in this area. • Ceramic membrane technology is promising for oily wastewater treatment. • The factors affecting ceramic membrane fouling during oily wastewater separation are discussed. • The commonly used strategies for fouling control of ceramic membranes are reviewed. • Opportunities for improved fouling control are identified. [ABSTRACT FROM AUTHOR]

Laminar separation membranes stacked by graphene and its derivatives hold the merit of controlled mass transfer behaviors. However, precise ion separation is challenged by the disordered assembly of nanosheets on macroporous substrates with complicated surface properties. Herein, we prepare ultrathin ordered graphene membranes by an intermediate layer assisted stacking method. Nanoporous covalent organic framework (COF) nanosheets are first vacuum-filtered on macroporous substrates, followed by deposition and thermal reduction of graphene oxide nanosheets to deliver ultrathin reduced graphene oxide (rGO) layers. The COF-decorated substrates provide a hydrophilic surface with reduced pores and roughness, facilitating the formation of ultrathin rGO layers with ordered stacking patterns and reduced microporous defects. Consequently, the obtained rGO/COF composite membranes can reject ∼90% of Na 2 SO 4 , ∼50% of NaCl, and >98% of various organic dyes, which are higher than pure rGO membranes. Meanwhile, the rGO/COF composite membranes can maintain good stability in solutions with different pH values and salt concentrations, and can be long-term operated for at least 10 days. This work is expected to deepen the understanding of the structure of laminar membranes and provides new perspectives to design ordered laminar membranes. [Display omitted] • Graphene/COF composite membranes are prepared using COF as intermediate layer. • COF layer with reduced pores and roughness leads to ordered stacking of graphene. • Microporous defects are eliminated due to ordered stacking of graphene. • Promoted desalination performances are achieved. [ABSTRACT FROM AUTHOR]

Worldwide, a considerable amount of oily wastewater is generated, with oil droplets from 2 to 200 nm that are difficult to separate because of their size and colloidal stability. This study presents a novel approach for effectively separating microemulsions via cubic silicon carbide (3C-SiC)-coated alumina (Al 2 O 3) membranes fabricated based on low pressure chemical vapor deposition (LPCVD). SiC was deposited at a relatively low temperature at 860 °C on 100 nm Al 2 O 3 membranes using two precursors: SiH 2 Cl 2 and C 2 H 2. With the increase in deposition time, up to 25 min, the pore size decreased from 41 nm to 33 nm, which is a smaller pore size of a SiC membrane than previously used for oil/water separation. The polycrystalline 3C-SiC-coated membranes showed improved hydrophilicity (water contact angle of 15°) and highly negatively charged surfaces (−65 mV). Microemulsion filtration experiments were carried out at a constant permeate flux (80 Lm−2 h−1) for six cycles with varying deposition time, pH, surfactant types, and pore sizes. The fouling of the SiC-coated membrane was, compared to the Al 2 O 3 membrane, effectively mitigated due to the enhanced electrostatic repulsion and hydrophilicity. Surfactant adsorption mainly occurred when the surface charge of the microemulsion and the membranes were opposite. Therefore, the surface charge of the alumina membrane changed from positive to negative when soaked in negatively charged microemulsions, whereas SiC-coated membranes remained negatively charged regardless of surfactant type. The membrane fouling was alleviated when the membrane and oil droplets had the same charge. Lastly, the 62 nm SiC-coated membrane with 20 min coating time was the best choice for the filtration of the microemulsion, because of the high rejection of the oil droplets and low fouling tendency. [Display omitted] • Ultrathin (18 nm) polycrystalline 3C-SiC was deposited onto a Al 2 O 3 membrane. • SiC membrane with the smallest pore size (33 nm) for oil/water separation. • Highly hydrophilic membranes with a negative surface charge were produced. • Various pore sizes of 3C-SiC coated membranes were compared. • A combination of high oil rejection and low (ir)reversible fouling was achieved. [ABSTRACT FROM AUTHOR]

Positively-charged nanofiltration (NF) membranes have become popular in membrane separation for lithium extraction from salt lake. However, negatively-charged NF membranes hardly achieve a satisfying Li+/Mg2+ selectivity due to the lack of the understanding on the mechanism of the effect of the electrostatic attraction on the Li+/Mg2+ permselective permeation. To this end, classical molecular dynamics simulations were performed to explore the effect of charge density of the negatively-charged nanochannels on the structure and dynamics of the confined Li+ and Mg2+ ions. Surprisingly, an appropriate modification by negative charges could simultaneously achieve a knock-on hopping for efficient Li+ permeation and a remarkable retardation to the Mg2+ self-driven diffusion, which realized a higher preferential permeation to Li+ over Mg2+ through the nanochannels. The underlying mechanism was explored by a series of analysis, including ion occupancy, mean square displacement (MSD), loading/exiting time, and trajectory tracking, etc. It was found that a combination of the elevated ion occupancy and an appropriate attraction by the negatively-charged channel generated an efficient ionic collision between the confined Li+ ions, thus producing a transition from the self-driven diffusion to the knock-on hopping permeation. Due to the higher positive charge, the confined Mg2+ ions hardly allowed a high ion occupancy and strongly interacted with the negatively-charged channel, which significantly retarded the Mg2+ transmembrane permeation. The novel understanding of the mechanism of the Li+/Mg2+ permselective permeation in the negatively-charged nanochannels will guide an effective development of high-performance membranes for Li+/Mg2+ separation. [Display omitted] • A knock-on Li+ hopping mechanism is discovered in a negatively-charged nanochannel. • Enhancing the charge density of nanochannels continuously retards the Mg2+ self-driven diffusion. • The knock-on hopping is produced by a high ionic adsorption and an appropriate adsorption in the nanochannels. [ABSTRACT FROM AUTHOR]

Membrane modules for seawater desalination are becoming increasingly important for obtaining clean water with the rising global water scarcity. The productivity of membrane modules is compromised by biofouling on the membrane and feed spacer. Biofouling development can be mitigated by modification of the spacer or membrane surface. The purpose of the present study is to evaluate the impact of surface-modified feed spacers on the cleaning performance of spiral-wound membrane filtration systems. After cold-plasma treatment, the feed spacers were modified with various combinations of polydopamine (PDA) and silver nanoparticles (AgNP). To compare the cleaning performance of the modified and unmodified spacers, membrane fouling simulators containing nanofiltration membranes and feed spacers were tested under industrially representative conditions: two full cycles involving biofilm development followed by cleaning-in-place (CIP). The modified spacers significantly improved the CIP efficiency when compared with that of the unmodified feed spacer. The highest CIP efficiency was obtained for the PDA–AgNP-coated spacers, which removed >90 % of the biomass. The PDA layers remained undetached during the CIP process, and the amounts of AgNP decreased without affecting the CIP effectiveness during consecutive operational cycles. The results demonstrate that CIP should be included in biofouling tests to evaluate the full potential of surface modifications and suggest that hydrophilic and biocidal spacer surface coatings can significantly improve the CIP effectiveness, thereby considerably reducing the CIP frequency and operational costs. [Display omitted] • Cold-plasma treatment enables hydrophilic modification of hydrophobic feed spacers. • Hydrophilic and biocidal coatings were grafted onto cold-plasma-treated feed spacers. • Coatings were tested for biofouling control under industrial operating conditions. • Hydrophilic and biocidal coatings improved the cleaning-in-place effectiveness. • Improved cleaning effectiveness was maintained over several operational cycles. [ABSTRACT FROM AUTHOR]

We produced ZIFs-based molecular imprinted composite membranes (ZMICMs) based on polydopamine (PDA) biomimetic modified MOFs (ZIF-8) by building a polymer layer imprinted on the membrane's surface to provide specific transport and structural selectivity for nanoscale molecules. The introduction of MOFs materials and the construction of PDA biomimetic surface had been explored to enhance the membrane separation performance, and the mechanism of interaction between functional groups in the template molecular recognition process had been systematically studied to obtain the selective separation mechanism. Adsorption tests (isothermal and kinetic adsorption) and the effectiveness of the selective separation was tested and evaluated using selectivity studies of molecular imprinted membranes (MIMs) and non-imprinted membranes (NIMs). The important testing findings demonstrated that the when prepared ZMICMs had good perm selectivity performance for atrazine (ATZ) perm selectivity factor (β = 1.60, 1.53) in addition to optimum specific adsorption ability (12.12 mg g−1). The strong specific identification ability and perm selectivity of ZMICMs demonstrated tremendous promise for the remediation of ATZ contamination. • The introduction of MOFs improves the separation performance of the membrane for atrazine. • The incorporation of PDA-modified MOFs improves the antifouling performance of the membrane. • Atrazine-specific imprinting layer was created using free radical polymerization technology. • Polydopamine modification increases the hydrophilicity of the membrane. [ABSTRACT FROM AUTHOR]

Textile wastewater commonly contains various organic compounds and salt mixtures, potentially raising serious environmental and health concerns. Traditional treatment approaches are hindered by high salinity; consequently, membrane separation technologies have attracted increasing attention over the past few decades. Herein, four commercial pressure-driven membranes with molecular weight cut-off (MWCO) gradients were employed for the advanced treatment of different types of textile wastewater. Specifically, these membranes were initially subjected to a fractionation test toward the dye/salt mixtures, followed by deep concentration of the dye molecules. Using Congo red (CR), methyl blue (MB), NaCl, and Na 2 SO 4 as representative dyes and salts, the results indicated that all membranes could effectively separate dye/salt mixtures and further conduct a deep concentration process toward the separated dye solutions. However, their efficiency and effectiveness largely depend on the membrane pore size and solution characteristics. For instance, membranes with lower MWCOs experience less fouling and shorter operation durations when treating CR-related solutions. All membranes showed improved fractionation efficiency toward MB/salt mixtures, requiring only approximately 10.2–42.9 % of the operation duration compared to CR-related solutions. The loose nanofiltration membrane proved superior to tight ultrafiltration membranes in both fractionation and concentration processes. Further research on cleaning methodologies demonstrated that both alkali and ethanol cleaning were influential in restoring the membrane performance. An appropriate ethanol/water concentration can effectively regenerate severely fouled membranes, achieving a high flux recovery ratio of ∼95 %. This study evaluated state-of-the-art pressure-driven membranes for textile wastewater treatment and guided cleaning strategies for optimal performance recovery. [Display omitted] [ABSTRACT FROM AUTHOR]

Thin-film composite (TFC) membranes prepared by the interfacial polymerization (IP) of amines and trimesoyl chloride (TMC) have been widely utilized for Li+/Mg2+ separation from salt-lake brine. The relatively high lithium rejection hinders the achievement of high lithium extraction efficiency. In this study, a polyphenol-metal-assisted method was designed to regulate the structure of polyethylenimine (PEI)-based polyamide nanofiltration (NF) membranes. Tannic acid (TA) was first deposited onto the substrate, followed by the impregnation of the Cu2+ ions-incorporated aqueous PEI monomer solution to establish ternary interactions among PEI, TA, and Cu2+ ions. Based on the synergistic effect of ternary interactions, the resultant PA-TA-Cu membrane possesses ultrathin thickness (≈11 nm), high positive charge, and relatively loose structure. It exhibited a high MgCl 2 rejection (95.9 %) and a low LiCl rejection (17.1 %), with a pure water permanence of 4.87 L m−2 h−1 bar−1. Furthermore, the NF membrane exhibits a high Li+/Mg2+ separation factor (26.5) and excellent long-term stability. This study provides an efficient strategy for fabricating an excellent NF membrane for lithium extraction from salt-lake brines. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) show great potential in various separation applications. However, fast nucleation rate and crystallization of MOFs, produce non-uniform and uncontrollable sized crystals, which are not suitable for the formation of MOF-based membranes. Herein, we propose the concept of utilizing protein polyphenol nanoassemblies (PPNs) as the building blocks for the confined growth of MOFs to fabricate zeolitic imidazolate frameworks (ZIF-67)-based membranes. We first demonstrated that colloidal PPNs as modulators in solution enables the formation of ZIF-67 MOFs with uniform and controllable crystal sizes. Subsequently, we utilized the metal salt coordinated PPNs (Co2+@PPN) as the precursor layer matrix deposited on porous polymeric support to fabricate ZIF-67 membranes via in-situ growth strategy at room temperature. The resultant membrane features a robust heterogeneous and well-integrated ZIF-67-reinforced PPN (ZIF-67@PPN) microporous networks. Benefiting from the rigid and multidimensional micropores of ZIF-67, the optimized ZIF-67@PPN1 composite membrane with improved water stability exhibited good water permeance (45.68 L m−2 h−1 bar−1), excellent dye desalination performance (Na 2 SO 4 /Congo red selectivity of 1271.47), and good antibiotic desalination performance (NaCl/Erythromycin selectivity of 21.46). The findings in this work provide important engineering concepts for the development of MOF-based membranes using sustainable nature-derived building blocks for emergent environment-relevant desalination applications in the chemical process industry. Colloidal protein-polyphenol nanoassemblies were employed as building blocks for the in situ growth of ZIF-67-based nanofiltration membrane on polymeric substrates. The protein-polyphenol nanoassemblies not only modulated the size and crystal morphology of the ZIF-67 but also facilitates the fabrication of ZIF-67@PPN nanoconfined membrane with multidimensional rigid micropores, which exhibited efficient dye desalination performance. [Display omitted] • Metal ion pre-anchoring platform on polymeric substrate facilitates MOF membrane fabrication. • Protein-polyphenol nanoassemblies renders unform metal ion pre-anchoring platform on substrate. • Metal ion@PPN precursor layer promotes the modulated nucleation and confined growth of MOF crystals. • ZIF-67@PPN1 membrane achieved efficient dye desalination performance with Na 2 SO 4 /CR selectivity of 1271.47. • ZIF-67@PPN1 membrane exhibited good antibiotic desalination performance with NaCl/Erythromycin selectivity of 21.46. [ABSTRACT FROM AUTHOR]

Critical minerals will remain major active ingredients to most battery technologies for decades and innovation to improve extractive operations during spent battery effluent recycling must be carried out. Although the recovery of metal-ions in aqueous solutions has been demonstrated with membrane systems, including electrodialysis, process intensification to increase the diffusion rate at the membrane/liquid interface must be achieved to improve recovery efficiency. This manuscript presents a unique approach to increase the rate of recovery and transfer of Li+ and Co2+ ions from a membrane bulk phase to an organic liquid phase by applying deep eutectic solvent (DES) instead of an aqueous solution as the permeate stream during electrodialysis. The DES, based on choline chloride and urea at a molar ratio of 1:2, is considered green and relatively non-toxic valuable for solvent extraction purpose. Here, electrodialysis tests were conducted with this solvent on the permeate side using commercial Neosepta and laboratory-made cobalt selective membranes. The DES significantly affected cobalt transport across the membranes and separation factor which increased from 247 to 516, leading to cobalt recovery as high as 66 %. Furthermore, the use of DES on the permeate side greatly improved the energy efficiency increasing the amount of recovered cobalt per Joule of energy by over 20 %. [Display omitted] • Deep eutectic solvents (DES) enhance diffusion kinetics during electrodialysis. • Enhanced Li+ and Co2+ recovery with β Co/Li up to 516 • Assessment of the stability and properties changes of the membranes in DES • Green recovery approach utilising non-toxic DES [ABSTRACT FROM AUTHOR]

The long-term and efficient treatment of shale gas wastewater is an inevitable tendency. This study employed the SEP@Fe-Mn/RGO composite membrane series for the membrane separation treatment of shale gas wastewater. Different proportions and different function of SEP@Fe-Mn/RGO composite membranes were obtained through the method of electrostatic self-assembly. This study researched the "Trade-off" issue of membranes separation through the analysis，resulting in membranes that best meets the separation requirements for shale gas wastewater. After two membrane separation, The oil-water separation efficiency (COD 2040 mg/L and TOC 487.14 mg/L) of shale gas wastewater was >99.3 %. The removal rate of the main salt component (Na 2 SO 4) reached 83.56 %, and the removal rate of major heavy metal ions (Fe3+, Cr3+, Ba2+) was above 60 %. Because of the continuous generation of in-situ bubbles by the reaction of MnO 2 with H 2 O 2 , and Fenton reactions on the membrane, which further accelerated the separation of pollutants. In a variety of harsh water environments, this membrane series remained stable within 12 h. Simple to prepare, cost-effective, low in energy consumption, and environmentally friendly, which makes it promising for wide applications in the field of petroleum water treatment. • Composite membranes with different functions were synthesized in a simple and economical way. • Through the experiment to established the oil-water separation model, explore the best proportion of the composite membrane to solve the "Trade-off" • After two membrane separations, all kinds of water pollution in shale gas wastewater can be effectively separated. [ABSTRACT FROM AUTHOR]

Polymeric membranes have become essential in addressing various industrial challenges in water purification, gas separation, pharmaceuticals, food packaging, protein purification, and more. This comprehensive review explores the extensive world of polymeric membranes, emphasizing the critical role of chemistry in their development and deployment. Nowadays, chemistry plays a significant role in the life of polymeric membranes. In this work, we have studied the importance of chemistry in membrane applications, concentrating on industrial applications. Polymeric membranes have emerged as indispensable tools for addressing pressing environmental and energy-related issues, with their versatility enabling solutions across various sectors. Due to the multiple advantages like reasonable cost, excellent processibility, easy operation, and no side product, polymeric membranes are applied in most industrial applications. Improvement in polymeric membrane processing is critical for realizing the potential of promising polymer chemistry and structure. In this article, we highlighted the role of polymer chemistry in membrane technology applications. This review article is a valuable resource for researchers to understand the symbiotic relationship between polymer chemistry and the ever-expanding domain of industrial membrane applications. By enlightening recent progress, highlighting ongoing challenges, and offering insights into future directions, it fosters an enriched appreciation for the vital role of chemistry in shaping the membranes that underpin modern industrial processes. [Display omitted] • The role of polymeric membranes in various industrial applications has been studied. • The importance of chemistry in membrane separation and purification has been focused. • Polymeric membrane's antibacterial activity and antifouling ability have been discussed. • Highlighted ongoing challenges and development and offers insights into future directions. [ABSTRACT FROM AUTHOR]

Vertical array carbon nanotube (VACNT) membrane is considered as one of the most promising materials for seawater desalination due to its excellent porosity, strong mechanical properties and atomic smoothness of the inner wall. However, in practical applications, the synthesis of highly oriented VACNT arrays with uniform pore sizes (< 1.1 nm) needs to be strictly controlled, and achieving high permeability-retention for large pores (> 1.1 nm) is a great challenge. Here, we use molecular dynamics simulations to introduce the oscillation paradigm into VACNT filtration membranes with a heterogeneous pore network with a wide pore size distribution (ranging from 1 nm to 3.5 nm). Notably, the oscillating heterogeneous VACNT membrane achieved ultra-high permeability of 1421.8 L/cm2/day/MPa (~5 times speed increase in comparison with homogeneous VACNT and ~ 2 times over state-of-the-art CNT membranes), while maintaining a selectivity of 97.5 %. This method activates the filtration capacity of 3.5 nm ultra-large pores, eliminating the requirement for pore homogeneity in VACNT, and achieves the effect of "killing two birds with one stone". In addition, the filtration performance of specific heterogeneous VACNT membrane was successfully predicted by water permeability curve fitting, which provided valuable theoretical guidance for the design of high-performance VACNT reverse osmosis desalination system. [Display omitted] • Ultra-large pores of 3.5 nm, which inherently lack filtering capabilities, could exhibit significant filtration performance when inducing the oscillation filtration paradigm. • Heterogeneous VACNT membrane, with a wide pore size distribution (ranging from 1 nm to 3.5 nm), achieve an ultra-high permeability of 1421.8 L/cm2/day/MPa, while maintaining a selectivity of 97.5 %. • This breakthrough holds the promise of eliminating the stringent requirement for pore homogeneity in VACNT filtration membranes system in experimental. [ABSTRACT FROM AUTHOR]

Complex multi-component pollutant-oil-water emulsions have caused serious environmental problems and increased the difficulty of purification treatment in the last few decades. The membrane based on two-dimensional (2D) materials can rationally control the interlayer distance, thus improved the separation performance of the membrane for complex wastewater. We herein reported a composite membrane, in which 2D metal-organic frameworks (MOFs) Co -CAT-1 with super-hydrophilicity cross-linked by polyethylene imine (PEI) was integrated into graphene oxide (GO) and then coated on polyvinylidene fluoride (PVDF) membrane (CPG membrane). The CPG membrane exhibited highly efficient in separating oil-water (including crude oil) emulsions, achieving a flux of 219 L∙m−2∙h−1∙bar−1 and a separation efficiency of 99.2 %. Moreover, the separation efficiency for complex emulsions after several cycles was maintained >99 % for dyes and 76 % for heavy metal ions (Ni2+, Pb2+, Zn2+). The remarkable fouling resistance and reusability of CPG membrane in purifying complex oil-in-water emulsions can be attributed to their internal cross-linking, electrostatic interactions, hydrogen bonding attraction, and π-π stacking. Molecular dynamics simulations were employed for in-depth studies on the separation processes of dye- and heavy metal ions-emulsions, revealing the mechanisms of mass transfer within the membrane. This work aims to construct stable and multifunctional membranes for separating pollutant-oil-water emulsions with multi-component. [Display omitted] • CPG composite membrane was fabricated via a facile self-assembly process. • The membrane showed promising synergistic separation performance and excellent reusability for multi-component emulsions. • CPG composite membrane exhibits excellent underwater oil repellency, anti-fouling, and superior resistance to extreme conditions. • The molecular dynamics simulations were employed to reveal the separation mechanism. [ABSTRACT FROM AUTHOR]

In this study, we revisit the fundamentals of constant–flux dead–end filtration, develop an analytical solution of the interfacial concentration ϕ m τ R o as a function of dimensionless time τ and observed rejection R o , and compare the solution with previous work developed for constant intrinsic rejection, R i. The excessive concentration, ϕ m τ R o − 1 , consists of three nonlinear terms of τ and reaches 4 R o τ in an asymptotic limit of τ > 1 / 2. We apply the Robin (mixed) and Dirichlet boundary conditions on the membrane surface and at a far feed–entrance, respectively. The mathematical difficulties for the inverse Laplace transform are resolved using a linear combination of the Laplace transform of error and complementary error functions and applying the convolution theorem. We analytically obtain the unsteady variation of the interfacial concentration after the pressure release using the global mass balance and numerically calculate the required time to reduce the interfacial concentration to a specific limit. More importantly, a relationship between observed and intrinsic rejection ratios is found, such as, R o ≃ R i , and verified using experimental data from the literature. [Display omitted] [ABSTRACT FROM AUTHOR]

Reverse electrodialysis (RED) is a promising renewable energy technology for salinity gradient power generation, while its key component (i.e., ion exchange membranes) faces the challenge of the lower energy density caused by the uphill transport of divalent ions (e.g., Mg2+). In this study, we carried out a series of molecular dynamics (MD) simulations to investigate the permselective transport of Na+ and Mg2+ through a novel sandwich-stacked hybrid covalent organic framework (COF) membrane. The alternate set of TpHz and TpPa-SO 3 H constructed reduced effective pore size ranging from 5.6 to 7.5 Å, producing an offset-block effect on the ion transport. Besides, the tunable interlayer spacing of the hybrid COF membrane could manipulate the rehydration/dehydration behavior of the confined Na+ ions. A suitable set of the interlayer spacing could achieve an adorable Na+/Mg2+ permselectivity and Na+ permeance by the synergistic effect of aperture sieving and the electrostatic affinity. This work provides useful insights into the Na+/Mg2+ permselective mechanism and further helps to design COF-based membranes for realizing a high energy efficiency for the application of RED. [Display omitted] • A novel sandwich-stacked hybrid covalent organic framework membrane was proposed for reverse electrodialysis. • An offset-block effect was generated by an alternate set of TpHz and TpPa-SO 3 H. • The rehydration/dehydration behavior of the confined Na+ ions could be controlled by the interlayer spacing. [ABSTRACT FROM AUTHOR]

Molecular deposition provides a flexible and versatile platform for preparing positively charged composite nanofiltration membranes. The widely studied building units for molecular deposition are polyphenols such as catechins and tannins, which usually cause the complexity of the ultimate selective layer due to their relatively high antioxidant activity and limited positive potential originated from the large number of hydroxyl groups. In this work, a laccase-triggered one-step process has been proposed to prepare composite nanofiltration membranes. Highly positively charged phenolic acid-amine networks, which are represented by ferulic acid (FA) and polyethyleneimine (PEI), are constructed as the dense selective layer with a thickness of about 49 nm. This process is conducted in aqueous solutions under mild conditions, driven by electrostatic adsorption, catalytic oxidation, and covalent crosslinking processes. The structure of the selective layer can be finely tuned by the molecular weights of PEI, the chemical composition, and the pH values of the solutions. The prepared composite nanofiltration membranes can effectively reject MgCl 2 (94.5 %) and organic dyes such as alcian blue (AB) (>98.7 %) and methyl blue (MB) (>97.8 %). This work not only demonstrates a facile and versatile method for preparing positively charged composite nanofiltration membranes with great separation performance towards divalent cations, but also expands the membrane building blocks. [Display omitted] • Highly positively charged nanofiltration membranes are prepared by eco-friendly surface deposition. • The membrane process is conducted through a one-pot and one-step manner under mild conditions. • Laccase-triggered oxidation and crosslinking processes are confirmed during the preparation process. • The positively charged nanofiltration membranes can effectively reject divalent cations such as Mg2+ and Ca2+. [ABSTRACT FROM AUTHOR]

The integration of membrane filtration and catalytic ozonation is increasingly investigated in micro-polluted wastewater treatment, whereas membrane fouling still inhibits its practical application. In the present study, a novel MnCe-catalytic membrane integrated with ozone process (O 3 /MnCe-CM) was established and applied to remove four micropollutants from the real secondary effluent in continuous operation. Efficient removal of four representative micropollutants with the removal rate ranging from 89.33 % to 99.49 % and superior performance on conventional pollutants, with the DOC, UV 254, polysaccharide, and protein reduced by 30 %, 88 %, 32.5 %, and 24 %. The O 3 /MnCe-CM process had an improved TMP control effect, explicitly reducing the irreversible fouling resistance given a R ir /R t of 10.17 % which is 42.9 % of that of the O 3 /CM process. After filtering for 70 days, the TMP only increased by 24.51 kPa. More importantly, the antifouling mechanism was proposed as the combined effects of the decrease of the membrane isoelectric point that elevated its repulsion towards pollutants and the catalytic ozonation that reduced the organic foulants accumulated on the membrane surface and inside the pores. In addition, ozonation in the membrane tank decreased the pollutant load passing through MnCe-CM. In all, the present study provides a novel O 3 /MnCe-CM process with a promising application perspective. [Display omitted] • Efficient removal of four representative micropollutants and superior performance on conventional pollutants removal achieved by O 3 /MnCe-CM process over a period of 70 days • O 3 /MnCe-CM process is sufficient to realize a stable and effective operation in the treatment of actual micro-pollutants containing wastewater. • O 3 /MnCe-CM process had improved TMP control, specifically reducing the irreversible fouling resistance. • The antifouling mechanism of the O 3 /MnCe-CM process was proposed as the decreased isoelectric point, the catalytic ozonation on the membrane surface and inside the pores, and the ozonation in the membrane tank. [ABSTRACT FROM AUTHOR]

Highly selective and permeable nanofiltration (NF) membranes are desirable for energy-efficient desalination and water treatment. However, the preparation of NF membranes with thinner defect-free selective layers and high separation performance remains challenging. Here a new strategy is reported for designing an NF membrane with a crumpled selective layer using polydopamine-piperazine-halloysite nanotubes (PDP-HNTs) as an interlayer and fabricated through vacuum filtration assisted interfacial polymerization (VFIP) method. Specifically, the PDP-HNTs/piperazine (PIP) dispersion was loaded onto the substrate surface through vacuum filtration, achieving construction of the interlayer and loading of the aqueous phase in one step. The PDP-HNTs interlayer served as a regulator to control the selective layer morphologies by retarding the polymerization reaction, forming an NF membrane with loose and crumpled structures. The resulting membranes display a high performance with the water permeance of 45.3 L m−2 h−1 bar−1, while maintaining a Na 2 SO 4 rejection of 97.1 %. Because of the versatility and simplicity of this strategy, our work provides a new approach for fabricating NF membranes with outstanding separation performance. [Display omitted] • PDP-HNTs nanomaterials were synthesized in situ and served as the interlayer. • Constructing of the interlayer and loading of the aqueous phase in one step • The PDP-HNTs interlayer served as a regulator to control the active layer morphologies • The constructed PDP-HNTs interlayer enhanced the structural stability of membrane • NF membrane with crumpled active layer exhibited a high separation performance [ABSTRACT FROM AUTHOR]

Super-hydrophilic separation membrane has been widely used to treat oily wastewater in production and life. However, the membrane is easily contaminated by oily emulsion and metal ions, which affects the separation flux and efficiency. This study presented a novel approach to prepare super-hydrophilic membranes by intercalating hydroxyapatite with graphene oxide and utilizing vacuum filtration. The membranes were thoroughly characterized using various techniques including FT-IR, XRD, SEM, AFM, and contact angle measurements. The study revealed that the hydroxyapatite's layered petal-like structure, combined with the hydrophilicity and graphene oxide, results in a membrane that is super-hydrophilic and underwater super-hydrophobic. HG-4 membrane had an excellent ability to separate oil-water emulsions (the separation flux reached 1798 L/(m2·h)). In addition, it can maintain good shape after 168 h of exposure to acid, alkali and salt. More importantly, HG-4 can effectively remove metal ions (Fe3+ adsorption effect of 98.34 %) and salt solution (CaCl 2 desalination rate of 76.21 %). The proposed hydroxyapatite membrane presents a novel approach for separating oil and water, and holds promising potential for application in this field. [Display omitted] • A green and environmentally friendly hydroxyapatite super-hydrophilic membrane is reported. • The membrane has high flux (1798 L/(m2·h)), and high interception rate. • The membrane can remove metal ions (Fe3+ adsorption effect is 98.34%) and the desalting rate of CaCl 2 is 76.21%). [ABSTRACT FROM AUTHOR]

As a kind of pressure-driven membranes, the nanofiltration (NF) membrane and process can separate molecules and ions with different molecular weights and valences, which are well applicable in purification, concentration, recovery of resources across various industries. However, in some complex applications, an individual NF membrane often faces the problems of deficient separation efficiency and membrane instability. Researchers have developed NF based hybrid processes, which not only solve the above problems faced by single NF, but also enhance the overall efficiency of hybrid systems involving other separation processes. Currently, there is a notable surge in publications regarding the NF-based hybrid processes, but a systematic review is still lacking. The objective of this review is to provide a comprehensive analysis of the key integration approaches and application areas in which NF-based hybrid process have been utilized in recent years. The challenges awaiting the researcher in the field of NF-based hybrid process are also provided. • NF-based hybrid process is effective in eliminating NF application bottlenecks. • Systematic analysis of research related to NF-based hybrid processes are performed. • The integration forms and application of NF-based hybrid processes are introduced. • The aims, challenges, and advantages of NF-based hybrid processes are presented. [ABSTRACT FROM AUTHOR]

Membrane separation has been demonstrated to have enormous potential for alleviating the global scarcity of clean water. However, membrane fouling extremely limits its applications, and on-demand and precise molecular separation is very challenging for traditional membranes. Here, a novel smart voltage-gated membrane with an analogous zwitterion-functionalized separation layer is prepared by combining blending, surface segregation and co-deposition. Intriguingly, amphiphilic sodium styrene-maleic anhydride copolymer (SMANa) anchored on CNTs not only promotes their dispersion in the membrane but also enhances the electroconductivity through the synergistic ionic-electronic conducting effect. More importantly, positively and negatively charged molecular chains mounted on the membrane surface could form different "electric double" layers in response to the voltage stimuli. Consequently, the optimized membrane as the cathode exhibits superior permeations and separations of Congo red (99.9 %, 313.6 L/m2·h·bar) and indigo carmine (96.9 %, 420 L/m2·h·bar), and as the anode displays outstanding permeations and separations of methyl green (98 %, 381.6 L/m2·h·bar), crystal violet (95.7 %, 368.2 L/m2·h·bar) and methyl orange (94.6 %, 166.4 L/m2·h·bar) due to the effective combination of size sieving, electro-enhanced electrostatic repulsion and adsorption-induced electrostatic repulsion effects. Simultaneously, high flux recovery ratios are also achieved due to the superposition of a stable hydration layer and electrochemistry, indicating excellent antifouling properties. [Display omitted] • SMANa@CNTs exhibited a coupling ionic-electronic conducting effect. • An electric double layer was created by the orientation of surface charged chains. • Similarly sized-charged dyes were efficiently separated by tuning the electric field. • Antifouling property was raised due to the surface zwitterions and electrochemistry. [ABSTRACT FROM AUTHOR]

Recently, inkjet printing technology has received increasing interests for membrane fabrication and modification. It offers various advantages such as the facile and fast process, minimal chemical consumption and precise chemical deposition. It is essential to have a holistic understanding of the inkjet printing technique used for different kinds for membranes, not only to further accelerate its application in membrane field, but also to prepare more advanced membranes with excellent performance. This review paper introduced the basic inkjet printer types used for membrane preparation such as thermal and piezoelectric drop-on-demand (DOD) inkjet printers. It also provided a comprehensive review of the detailed inkjet printing assisted membrane fabrication and modification processes and their applications in different membrane areas including the membrane-based separation (e.g., reverse osmosis (RO), nanofiltration (NF), organic solvent nanofiltration (OSN), gas separation membranes, and oil/water separation membranes) and fuel cell applications. [Display omitted] • The fundamental mechanisms and the various types of inkjet printers are introduced. • Detailed inkjet printing assisted membrane preparation processes and the performances are summarised and discussed in terms of different membrane applications. • The challenges and perspectives of the inkjet printed membranes are proposed and discussed. [ABSTRACT FROM AUTHOR]

In order to solve the contradiction between permeability flux and selectivity in nanofiltration membrane desalination technology, a novel interfacial polymerization layer structure was designed. In this structure, the hydrophilic modified carbon nanotubes (CNT) untangled and protruded the PA layer under the electric field, resulting in the generation of microporous water channels between CNT and polyamide molecules. Thanks to this unique membrane surface structure, the permeability of the nanofiltration membrane was significantly enhanced, reaching 24.4 L·m−2·h−1·bar−1, in which the rejection of MgCl 2 and Na 2 SO 4 were also maintained at 96.1 % and 97.3 %, respectively. At the same time, the surface of the nanofiltration membrane remained intact in the chlorine resistance test, and the total fouling rate caused by lysozyme (LYZ) protein solution was only 2.89 %, demonstrating excellent chlorine resistance and pollution resistance. The design of changing surface structure through electric field-assisted nanomaterials provides a new innovative strategy for the development of separation membrane. Untangling CNT forms microporous water channels that promote the permeability of nanofiltration membranes while concurrently ensuring a high rejection rate. [Display omitted] • The SLS-CNT interface polymeric membrane has a novel cobweb-like surface structure with protruded CNT. • The SLS-CNT interface polymeric membrane contains a large number of hydrophilic groups and water transport channels. • The permeability of SLS-CNT interface polymeric membrane increased by 293.5 %. • The SLS-CNT interfacial polymeric membrane shows satisfactory chlorine resistance and fouling resistance. [ABSTRACT FROM AUTHOR]

To avoid structural changes within nanofiltration membranes during operation, pre-compaction of filtration membranes is usually performed. However, even after pre-compaction, the NF270 membrane has previously been shown to display a level of pressure susceptibility in pure water systems, particularly evident at low pressures. For the first time, this study provides experimental evidence for the effect of salinity on the pressure susceptibility of the NF270 membrane. Permeability was shown to decrease with increasing salinity up to 189 mM MgSO 4 , with the largest reduction (22 %) observed at the lowest MgSO 4 concentration (31.49 mM MgSO 4). A significant reduction (35 %) in the membrane susceptibility was also observed following the introduction of MgSO 4 to a concentration of 31.49 mM. A mathematical expression, developed for pure water systems, was modified to account for salinity effects and fitted the experimental data well for concentrations up to 0.2 M. These results are explained by compaction of the membrane polymer, due to either charge neutralisation at the membrane surface, or electric double layer compression, or both. However, further increases in salinity had no significant effect on membrane susceptibility, suggesting that salt induced membrane compaction occurs at very low concentrations. [Display omitted] • NF270 membranes were shown to have a susceptibility to pressure in pure water. • A novel pressure-flux expression was derived for elastic membranes in saline solution. • For the first time, the effect of salinity on membrane susceptibly to pressure was quantified. • Salinity caused membrane deswelling in NF270 significantly reducing permeability. • NF270 membranes susceptibility to pressure was reduced in saline solution. [ABSTRACT FROM AUTHOR]

Membrane distillation (MD) is an emerging membrane separation technology with great potential for desalination, wastewater treatment and volatile resource recovery. It becomes even more attractive as it can utilize low-grade heat or renewable energy, and treat high-salinity waste liquids towards zero liquid discharge. However, the performance of MD is often limited by the wetting of hydrophobic porous membranes during operation, leading to reduced flux and efficiency. To overcome this challenge, the development of antiwetting hydrophobic MD membranes has gained increasing attention in recent years. In this review, we examine the liquid entry pressure (LEP) and its influencing factors (e.g. the maximum pore size, surface chemistry/free energy and surface roughness/architecture) of an MD membrane, which determine the antiwetting performance of the porous MD membrane. From enhancing the LEP point of view, we propose two key strategies for engineering antiwetting surfaces: (1) reducing the membrane pore size, and (2) increasing the liquid contact angle by minimizing the surface free energy and the liquid/solid contact area through enhancing the surface roughness and/or creating hierarchical/re-entrant structures. These strategies include various specific fabrication techniques, such as surface coating, vapor deposition, layer-by-layer assembly, surface fluorination, and surface functionalization. Green surface modification materials and methods are also discussed to reduce the application of less environmentally friendly fluoride-containing compounds. Furthermore, we provide insights and future directions for the design and engineering of high-performance antiwetting hydrophobic MD membranes. Overall, this review offers a comprehensive analysis of the current state-of-the-art research in engineering antiwetting hydrophobic MD membranes, and highlights the potential for the development of next-generation MD membranes with improved performance and efficiency. [Display omitted] • We analyze the correlation between membrane properties and antiwetting performance. • Key strategies for engineering antiwetting MD membranes are evaluated. • Different methods and materials for antiwetting MD membranes are discussed. • We offer insightful perspectives on engineering antiwetting MD membranes. • This review offers comprehensive analysis and guidelines for MD membrane development. [ABSTRACT FROM AUTHOR]

Extracting lithium from salt lakes and preparing lithium hydroxide could provide important commodities for the economic development in future. In this work, a complete system was divided into two steps of selectrodialysis (SED) and selectrodialysis with bipolar membrane (BMSED) to treat salt lakes for the production of lithium hydroxide. The effects of the applied current density, the commercial monovalent selective cation-exchange membranes (CIMS and CSO), the monovalent selective anion-exchange membranes (ACS and ASV) and the voltage drop in the SED process were investigated, respectively. The experimental results indicated that under the current density of 12 mA/cm2 can effectively avoid membrane scaling. The separation performance for Mg2+ and Ca2+ by using CIMS/ACS membrane stack was demonstrated to be superior to CSO/ASV membrane stack. Additionally, the SED stack had proven to be feasible for concentrating lithium and removing divalent ions simultaneously. In BMSED process, the purpose was to combine the monovalent selective ion-exchange membrane with bipolar membrane (FBM) inside the membrane stack to remove divalent ions and simultaneously produced LiOH. The results showed that the concentration of LiOH and current efficiency were optimized at the current density of 6 mA/cm2. Furthermore, different cation-exchange membranes (CIMS, CSO and CMX) and anion-exchange membranes (ACS, ASV and AMX) were used to evaluate the BMSED process. Compared to the FBM/ASV/CSO/FBM membrane stack and FBM/AMX/CMX/FBM membrane stack, FBM/ACS/CIMS/FBM membrane stack exhibited superior current efficiency and separation performance for Mg2+ and Ca2+. • Selectrodialysis (SED) was used to extract lithium from high Mg2+/Li+ ratio salt lake. • Bipolar membrane selectrodialysis (BMSED) was used to produce LiOH and HCl from the crude product of LiCl. • The phenomenon of membrane scaling during SED process was experimentally investigated. • LiOH with high purity could be obtained by BMSED process. [ABSTRACT FROM AUTHOR]

A low-pressure high-recovery (LPHR) multistage reverse osmosis desalination process is developed in order to produce a very strong brine and freshwater at the same time. The specific energy consumption (SEC) of the process is estimated to be lower than that of a single-stage RO unit and comparable to previously proposed multistage RO configurations. An important feature of this process is that the operating pressure can be optimized to minimize the total cost of water production. The performances of the 4- and 5-stage configurations of the LPHR process are evaluated initially at the thermodynamic limit in terms of the specific energy consumption and total cost of producing water. The cost analysis suggest that the LPHR process would be economically feasible for a water recovery > 70% with an OPD between 58 and 65 bar in order to produce a freshwater product containing no more than 350 ppm TDS from a seawater feed with 35,000 ppm TDS. A process design is also proposed based on commercially available desalination membranes, predicting that 73% overall water recovery can be achieved at a maximum applied pressure of ~55 bar using the 5-stage configuration of the LPHR process. • Multi-stage membrane configuration combines RO and NF stages, increasing water recovery. • Process configuration reduces specific energy consumption and required osmotic pressure difference. • Currently available commercial membranes can be used to obtain water recoveries exceeding 65%. • Seawater with high salinity (~45,000 TDS) can be desalinated with high water recovery. [ABSTRACT FROM AUTHOR]

Scaling constitutes a major concern in seawater desalination. In thermal desalination, scaling is limiting the top brine temperature (TBT). Brine temperature limitation depends on the concentration of divalent ions. This paper reports the synthesis of graphene oxide (GO)/polyacrylamide (PAM)/polyethersulfone (PES) membrane, in which GO layer is deposited on the surface of PES substrate using PAM as an adhesive layer, to be used as a pretreatment step to filter the divalent ions in thermal seawater desalination application. GO/PAM-PES membrane is prepared via spin coating technique, then reduced to rGO/PAM-PES by subjecting the membrane to hydrogen iodide (HI). PAM is used as an adhesive layer onto PES membrane (an ultrafiltration membrane) to improve rGO layer attachment onto its surface. The results indicate that increasing pressure increases both the rejection and the permeate flux. Using seawater, rGO/PAM-PES yields a higher rejection for Mg2+ and Ca2+ ions compared with commercial nanofiltration membrane (NF270). The pretreatment step allows the increase in TBT to 148 °C using NF, 160 °C using NF-GO and 166 °C using rGO membranes. Unlabelled Image • GO/PAM-PES membrane is prepared via spin coating then reduced to 2rGO/PAM-PES • NF270 and rGO membranes are tested in a cross-flow test with MgSO 4 , CaSO 4 and seawater • 2rGO/PAM-PES (or UF membrane coated with rGO) and NF membranes yield a similar rejection rate • 2rGO/PAM-PES membrane yield the highest TBT without scaling for MS • The TBT can be increased to 148 °C using NF, 160 °C using NF-GO and 166 °C using rGO membrane [ABSTRACT FROM AUTHOR]

A new hierarchical model for the electrodialysis (ED) process is presented. The model has been implemented into gPROMs Modelbuilder (PSE) , allowing the development of a distributed-parameters simulation tool that combines the effectiveness of a semi-empirical modelling approach to the flexibility of a layered arrangement of modelling scales. Thanks to its structure, the tool makes possible the simulation of many different and complex layouts, requiring only membrane properties as input parameters (e.g. membrane resistance or salt and water permeability). The model has been validated against original experimental data obtained from a lab scale ED test rig. Simulation results concerning a 4-stage treatment of seawater and dynamic batch operations of brackish water desalination are presented, showing how the model can be effectively used for predictive purposes and for providing useful insights on design and optimisation. Unlabelled Image • A hierarchical model for electrodialysis based on semi-empirical approach • The model has been validated with original experimental data. • The possibility to simulate different layouts (multistage) has been assessed. • Dynamic simulations have been performed to simulate a batch operation. [ABSTRACT FROM AUTHOR]

Currently, it is commonly observed that ion flux decreases as the separation performance of cation exchange membranes between mono- and double-charged ions improves. Therefore, cation exchange membranes with simultaneously excellent separation performance and high ionic flux must be developed. Herein, a series of pure and organic-inorganic cross-linked membranes were synthesized using UV irradiation. The synthetic membranes showed high ion-exchange capacity (IEC) and large ion flux. The organic-inorganic membranes achieved excellent mechanical properties, thermal stability, and separation properties owing to the addition of SiO 2. When the silica content was 4 wt%, the three ionic perm-selectivity showed their highest separation performances of 1.70 ± 0.03(P K Na ), 5.84 ± 0.04(P K Mg ), and 25.67 ± 0.04 (P K Ca ), representing an increase of 70% (P K Na ), 279.22% (P K Mg ), and 1236.98% (P K Ca ) compared than those of pure membrane. In addition, the limiting current density of the prepared organic-inorganic membranes was all >8.74 mA/cm2, higher than that of commercial membrane. According to these excellent performances, the prepared membranes showed good prospects for separation performance of cation exchange membranes. The addition of a proper amount of inorganic particles can improve the ion perm-selectivity between mono- and double-charged ions. • Novel organic-inorganic cross-linked membranes were successfully synthesized by UV irradiation with various SiO 2 loadings. • The highest ionic perm-selectivity were 1.70 ± 0.03(P K Na ), 5.84 ± 0.04(P K Mg ), and 25.67 ± 0.04 (P K Ca ), respectively. • The limiting current density of the organic-inorganic membranes were all higher than 8.74 mA/cm2. [ABSTRACT FROM AUTHOR]

Driving the thermal desalination system by waste heat is typically proposed to save utilized energy and mitigate environmental impact. However, to evaluate the performance of desalination unit, it is necessary to define the exergy efficiency correctly to reveal the real source of irreversibilities. In this regard, a geothermal-based system combined with seawater desalination units to produce distillated water, cooling, power and hydrogen is developed and analyzed thermodynamically. To identify the major extent of generated entropy in multi-effect-desalination (MED) and direct-contact membrane-distillation (DCMD), in addition to exergy destructed in the system's components, the temperature disequilibrium and chemical disequilibrium are taken into account. The present results indicate that the desalination integrated system is capable of producing more than 165,600 kg freshwater per day. Also, under the specific operating conditions, the membrane evaporation efficiency, mass flux through the hydrophobic permeate in DCMD and GOR in MED can be achieved to 46.2%, 9.8 × 10−6 m/s and 5.6, respectively. As well as, the condenser in MED and membrane module in DCMD are the most exergy destructive elements. For MED condenser, it is owned to the large cooling water flow rate and for DCMD, membrane structure like thickness and pore size and also conduction loss are the main reasons of irreversibilities. • A new geothermal-based MED/DCMD integrated system proposed • Minimum heat separation concept for desalination units proposed in exergy analysis • Temperature and chemical disequilibrium are considered in exergy destruction. • Mass and heat transfer analysis are developed for DCMD. [ABSTRACT FROM AUTHOR]

Poly(vinylidene difluoride) (PVDF) membranes for direct contact membrane distillation (DCMD) are commonly modified to decrease their wettability by water. Yet, the vapor-induced phase separation (VIPS) process may be a suitable alternative to avoid complex and expensive modifications. Superhydrophobic membranes with a water contact angle >152° were prepared in one single step by adjusting the polymer concentration, dissolution temperature, relative humidity, and exposure time to vapors to 10 wt%, 40 °C, 80 % and 10 min, respectively with N-Methyl-2-pyrrolidone (NMP) as the solvent. Compared to commercial polytetrafluorethylene (PTFE) membrane, the VIPS PVDF membrane showed higher water vapor flux (38 LMH vs 36 LMH), lower flux decline ratio (22 % vs 39 %) and superior salt rejection (99.99 % vs. 99.90 %) in a 3 h-DCMD process. In wetting tests, the VIPS membrane failed for a sodium dodecyl sulfate concentration of 0.2 mM while 0.1 mM was enough to trigger wetting of the commercial membrane. The energy barrier to heterogeneous crystallization was slightly larger for the VIPS membrane, and a higher rejection was measured during scaling tests (99.8 % vs. 94.2 % for PTFE membrane). Finally, the VIPS membrane outperformed the commercial membrane in a long-term test (100 h). These results evidence the suitability of VIPS PVDF membranes for DCMD. [Display omitted] • Superhydrophobic PVDF membranes are developed by vapor-induced phase separation. • High flux and salt rejection are obtained in direct contact membrane distillation. • VIPS membrane flux/rejection performances compete with state-of-the-art membrane. • Better scaling and wetting resistance are measured against a commercial membrane. • Better long-term performances are measured compared to a commercial membrane. [ABSTRACT FROM AUTHOR]

Biological ion channels exhibit many remarkable mass-transport properties, including high selectivity and permeability, which are also highly desired in practical applications. Herein, using molecular dynamics simulations, we design a biomimetic graphene nanopore with valence selectivity for monovalent cations, by tailoring pore size and modifying the pore rim with four negatively charged carboxylate groups to mimic the selectivity filter of bacterial Na+ channels such as NavAb. The results indicate that under electric fields, the biomimetic nanopore preferentially conducts Na+ over Ca2+, as the carboxylate groups in the nanopore selectively bind Ca2+ and slow down its passage through the nanopore. In contrast, Na+ interacts with the carboxylate groups less strongly and passes across the nanopore quickly. Under strong fields, a Cl− concentration polarization layer quickly forms on one side of the nanopore and promotes the formation of stable clusters of Cl− and Ca2+ pairs bound at the carboxylate groups, which severely hinders the transport of Cl− and occasionally suspends the transport of cations across the nanopore. These molecular insights provide some design principles and implications for fabricating nanoporous graphene membranes for separation applications, such as heavy metal removal from wastewater. [Display omitted] • A biomimetic graphene nanopore is designed by mimicking the selectivity filter in a bacterial Na+ channel. • The biomimetic nanopore shows valence selectivity for monovalent cations and preferentially conducts Na+ over Ca2+. • Strong binding of carboxylate groups in the nanopore with cations dictates the valence selectivity. • Stable clusters of Cl−-Ca2+ pairs formed near the nanopore severely hinder the transport of Cl−. [ABSTRACT FROM AUTHOR]

The permeance-selectivity trade-off has been a long-standing problem in membrane separation process, which has limited the application potential of many membrane separation techniques. Here we introduce chitosan (CS) nanofibers interlayer to optimize the substrate to improve the separation performance of thin-film composite (TFC) membrane fabricated by electrospray-assisted interfacial polymerization (EIP). A series of characterizations were conducted and the results showed that the introduction of CS nanofibers prevented polyamide from invading the substrate's pores, and increased the content of interfacial amine monomer to promote interfacial polymerization (IP) reaction. At the same time, the enhanced confinement effect formed a rougher selection layer, providing more water transport paths and enhancing the hydrophilicity of the membrane. Compared with the control TFC membrane with polyethersulfone (PES) substrate, the TFC/CS/PES membrane with CS/PES composite substrate showed excellent separation performance, achieving 4.5 times increase in permeance while maintaining a high MgCl 2 rejection. Our work provides a new strategy for optimizing the substrate and improving the properties of the membranes. [Display omitted] • A CS nanofibers composite substrate was constructed. • The CS/PES composite substrate endows the TFC membrane with improved performances. • The obtained TFC membrane evades the permeance-selectivity trade-off dilemma in EIP process. • A composite substrate is extremely necessary for EIP process. [ABSTRACT FROM AUTHOR]

Currently, most nanofiltration membranes exhibit satisfactory separation performance on the anions or cations, and few membranes could concurrently separate anion and cation. Therefore, preparing nanofiltration membranes with excellent separation performance for both anionic and cationic ions remains a challenge. Herein, we have developed a series of nanofiltration membranes using conventional interfacial polymerization with different ratios of trimesoyl chloride (TMC) and piperazine (PIP) concentrations. In the interface polymerization process, the amine groups carried by PIP imparted a positive charge, while the hydrolysis of acyl chloride groups resulted in the generation of carboxylic acid groups that introduced a negative charge. The mix-charged nanofiltration membrane could be fabricated by varying PIP/TMC concentration ratios. The optimized membrane exhibited high rejection rates for bivalent ions (Na 2 SO 4 rejection of 96.6 %, MgCl 2 rejection of 93.0 %), and its selectivity for Mg2+/Li+ mixed solution was improved significantly. This work provides a novel approach for the development of nanofiltration membranes capable of effectively separating mono-/divalent ions. [Display omitted] • Fabrication of mixed-charged polyamide membranes via regulating the PIP/TMC ratio directly. • High PIP/TMC ratio leads more unreacted amine groups in the polyamide which was beneficial to MgCl 2 rejection. • Such NF membrane showed excellent separation efficiency to Mg2+/Li+ and SO 4 2−/Cl−. [ABSTRACT FROM AUTHOR]

Abstract The selectivity of nanofiltration (NF) membranes is determined by membrane parameters as well as species mobilities (solute diffusivity and solvent viscosity). Changes in temperature affect each of these quantities, thereby altering membrane selectivity. To determine whether membrane parameters or mobilities primarily account for observed changes in permeate quality upon temperature increase, values of each property are either fitted from experimental data or calculated. Model validation with data from three feed compositions and two membranes reveals clear trends in temperature-dependent property-variation: pore size, net path length through membrane selective layer and negative membrane charge increase at higher temperature. An analytical approach is taken to explain the increase or decrease in permeate concentration due to each contributive factor, revealing the opposing effects of the two mobility factors. Modeling results further show that neither membrane parameter changes nor mobilities can alone explain selectivity changes with temperature. With increasing pressure, however, the net effect of membrane parameters increasingly overshadows that of the mobilities. Highlights • Nanofiltration membrane properties show clear trends with varying temperature. • Effects of various parameters on permeate concentration are studied. • Influence of membrane properties vs. species mobilities investigated • Membrane properties increasingly dominant over mobilities with increasing pressure • Membrane structural reorientation worsens permeate quality. [ABSTRACT FROM AUTHOR]

Abstract Recent progress in reverse osmosis (RO) technology is not limited to RO membrane materials, module designs and RO process optimization. It involves prior feed treatment which directly impacts RO system performance. The ongoing challenges of membrane fouling in RO membranes can be addressed by increasing the operational efficiency through the use of correct pretreatment options which can mitigate organic and inorganic fouling by selectively rejecting contaminants prior to reaching the RO unit. Highly polluted water resources have put critical stress on the existing conventional pretreatment techniques, whereby membrane pretreatment has emerged as a promising alternative. This paper provides an overview of the development and current trends in conventional and non-conventional RO pretreatment techniques whereby the techniques are critically reviewed to inform readers of potential improvements in such areas. This paper addresses the major drawbacks of conventional pretreatment methods which have necessitated the use of membrane pretreatment techniques. Special attention is given to microfiltration, ultrafiltration and nanofiltration methods and their development in terms of advanced membrane materials based on ceramics and self-cleaning membranes. Studies from laboratory scale standalone systems, pilot scale and large scale integrated systems for performance, cost and ecological analysis have been reviewed to familiarize readers with the many factors which need to be analyzed for selection of the appropriate pretreatment method(s). The critical review in this paper will help researchers focus more on the areas which have room for further development for cost-effective and advanced RO pretreatment techniques. Highlights • Reverse osmosis (RO) pretreatment continues to be one of the most challenging aspects of RO plants. • Membrane pretreatment capital and operational cost is higher than conventional pretreatment. • Membrane pretreatment water production cost is smaller than conventional ones due to improved permeate quality. • Ultrafiltration system with minimal prior pretreatment can reduce the cost of the overall RO process. • Integrated pretreatment systems incorporating nanofiltration saved up to 25–30% energy. [ABSTRACT FROM AUTHOR]

Abstract For the proposed energy-saving "nanofiltration/electrodialysis with polarity reversal (NF/EDR)" integrated membrane process for seawater desalination, studies on the NF process and the optimization of the ED process have been previously conducted. Based on the obtained results, a multi-stage, multi-passage ED process is presented in this manuscript to realize the optimization of energy consumption. In addition, the integration between NF and EDR processes at a pilot scale was accomplished, in which actual seawater was the feed water and >1200 h of demonstrative operation was implemented. During the NF process, 15 NF90-4040 elements with high desalination capacity were applied. During the EDR process, the membrane stack consisted of three stages with six passages were utilized, in which 250 cell pairs were included with unequal pairs of membranes for each stage. From the first to the third stage, there were 100, 80, and 70 membrane pairs, respectively. In addition, the energy-saving process was achieved by thinning the thickness of the electrode chamber to 2 mm and filling the electrode chambers with mixed ion exchange resin at an appropriate volume ratio. Furthermore, the voltage and the current for each stage can be independently controlled. The results show that the total desalination rate of the integrated process can be 99.26%, the system energy consumption is <2.15 kWh/(m3 produced water), which is significantly lower than that of SWRO, suggesting that the proposed integrated membrane process is an efficient and economically feasible seawater desalination system. Highlights • An energy-saving "NF/EDR" integrated membrane process for seawater desalination is proposed. • Multi-stages with multi-passages electrodialysis process is presented. • Some special energy-saving designs are adopted. • A demonstration operation lasts for 1200 h is realized. [ABSTRACT FROM AUTHOR]

Abstract To effectively separate Mg2+ and Li+ from salt lake brine with high Mg2+/Li+ mass ratio, a positive charged nanofiltration membrane with abundant -NH 3 + and -NH 2 + was designed and fabricated via interfacial polymerization between polyethyleneimine (PEI) and trimesoyl chloride (TMC) on the polyethersulfone ultrafiltration membrane. Zeta potential test revealed that at pH below 9.3, the resulting membrane exhibited a high positive charge due to a large amount of unreacted amine groups on the PEI branch. In the separation process, Donnan exclusion effect dominated the separation performance of resulting membranes for Mg2+ and Li+. The results showed that the Mg2+/Li+ mass ratio declined from initial 20 to 1.3 and the separation factor S Mg , Li was as low as 0.05 with a pure water permeation of 5.02 L/(m2hbar) after filtration with resulting NF membrane. The difference between the rejection for Mg2+ and Li+ reached up to 76%. Compared with membrane in previous studies, the separation performance for Mg2+ and Li+ of positive charged NF membrane prepared in this work increased more than one time. This research demonstrated the potential of positive charged PEI-TMC composite NF membrane for the separation of Mg2+ and Li+ from salt lake brine with high Mg2+/Li+ mass ratio. Highlights • Positive charged NF membranes with abundant -NH 3 + and -NH 2 + were fabricated. • Interfacial polymerization parameters dominated the performance of the membrane. • The S Mg , Li and the PWP reached to 0.05 and 5.02 L/(m2hbar), respectively. • The rejection for Mg2+ and Li+ were 95% and 19%, respectively. [ABSTRACT FROM AUTHOR]

Abstract Oil and gas industry generate large quantities of oily wastewater effluents. This wastewater has a major impact on the environment and human health. Hence, a suitable separation method is applied to treat oily wastewater to not only meet the environmental regulations but also to promote water recycling and desalination. Many studies were performed in the literature to investigate the best technologies for treating oily saline water such as the traditional technique of gravity sedimentation and dewatering. Among all, membrane separation processes have been receiving extra attention in the past decades. This is due to their high separation efficiency, low energy requirements and easy operation. Additional research activities were also directed to utilize membranes in pre-treatment separation processes of oily water ahead of the desalination units. This paper presents a comprehensive review for the recent treatment processes available in the literature for oily wastewater with the concentration on the use of various membranes to accomplish this target. The paper also reviews the recent findings in membranes' development and emerging modification techniques such as interfacial polymerization, nanoparticles incorporation, and surface grafting. A special emphasis was given for ceramic membranes, their operation and their preparation techniques. Moreover, the paper compares and discusses the effect of different operating conditions such as trans-membrane pressure and cross flow velocity on membrane separation performance in oily water. Highlights • Comprehensive review on oily water/wastewater. • Techniques used for oily wastewater. • Polymeric membrane modification techniques for oily wastewater treatment. • Synthesis of ceramic membranes for oily wastewater treatment. [ABSTRACT FROM AUTHOR]

Abstract Thermal-energy-driven desalination processes such as membrane distillation (MD), humidification dehumidification (HDH), and multi-stage flash (MSF) can be used to concentrate water up to saturation, but are restricted to low per-pass recovery values. High recovery can be achieved in MD through feed recirculation. In this study, several recirculation strategies, namely batch, semibatch, continuous, and multistage, are compared and ranked based on flux and energy efficiency, which together influence overall cost. Batch has higher energy efficiency at a given flux than semibatch and continuous recirculation because it spends more operating time treating lower salinity water for the same value of overall recovery ratio. Multi-stage recirculation is a steady-state process that can approach batch-like performance, but only with a large number of stages. Feed salinity rises during the batch operating cycle, and as a result feed velocity may have to be increased to avoid operating above the critical specific area wherein both GOR and flux are low due to significant heat conduction loss through the membrane. Finally, the choice of optimal membrane thickness for batch operation is compared to that of continuous recirculation MD. Highlights • Batch MD achieves higher GOR at same flux than semibatch or continuous MD. • Multistage MD requires a large number of stages to match batch performance. • Optimal membrane thickness is a function of average flux of batch MD operation. • Feed velocity must be controlled during process cycle time to avoid low GOR, flux. • Reset time between batch cycles must be minimized to achieve good performance. [ABSTRACT FROM AUTHOR]

Abstract Direct contact membrane distillation (DCMD) is a nonisothermal technology applied for the separation of non-volatile components from aqueous solutions. Nowadays, a huge number of publications are dedicated to modeling of DCMD, however all of the presented models have at least one of the following disadvantages: oversimplification, the use of empirical heat and mass transfer coefficients and poor prediction for cases which are out of the experimental data range. To overcome these drawbacks, a multipurpose general predictive model of DCMD has been developed. The proposed model is suitable for hollow fiber and flat sheet configurations with or without spacers. For each compartment of the DCMD process, our model describes the momentum, mass and heat balances by systems of ordinary differential, partial differential and algebraic equations. The performance of the model has been analyzed in terms of the operating parameters (concentration of a feed solution, feed flow rate and feed temperature) and membrane thickness and length. The simulated results were in very good agreement with experimental and literature data. The broad parametric study demonstrates the great potential of application of the proposed model not only in the process optimization but in design of DCMD modules. Highlights • A general predictive model for DCMD was developed • A CFD approach was used for modeling • The model consists of systems of PDEs, ODEs and AEs • Temperature, concentration, pressure and velocity profiles within the DCMD module are obtained • The model was validated and the effects of the operating parameters and membrane properties were investigated [ABSTRACT FROM AUTHOR]

Membrane distillation (MD) is a thermal separation process which possesses a hydrophobic, microporous membrane as vapor space. A high potential application for MD is the concentration of hypersaline brines, such as e.g. reverse osmosis retentate or other saline effluents to be concentrated to a near saturation level with a Zero Liquid Discharge process chain. In order to further commercialize MD for these target applications, adapted MD module designs are required along with strategies for the mitigation of membrane wetting phenomena. This work presents the experimental results of pilot operation with an adapted Air Gap Membrane Distillation (AGMD) module for hypersaline brine concentration within a range of 0–240 g NaCl /kg solution. Key performance indicators such as flux, GOR and thermal efficiency are analyzed. A new strategy for wetting mitigation by active draining of the air gap channel by low pressure air blowing is tested and analyzed. Only small reductions in flux and GOR of 1.2% and 4.1% respectively, are caused by air sparging into the air gap channel. Wetting phenomena are significantly reduced by avoiding stagnant distillate in the air gap making the air blower a seemingly worth- while additional system component. [ABSTRACT FROM AUTHOR]