Antifouling Performance Research Articles

Construction of Co-Modified MXene/PES Catalytic Membrane for Effective Separation and Degradation of Tetracycline Antibiotics in Aqueous Solutions

The application of antibiotics has advanced modern medicine significantly. However, the abuse and discharge of antibiotics have led to substantial antibiotic residues in water, posing great harm to natural organisms and humans. To address the problem of antibiotic degradation, this study developed a novel catalytic membrane by depositing Co catalysts onto MXene nanosheets and fabricating the polyethersulfone composite (Co@MXene/PES) using vacuum-assisted self-assembly. The dual role of MXene as both a carrier for Co atoms and an enhancer of interlayer spacing led to improved flux and catalytic degradation capabilities of the membrane. Experimental results confirmed that the Co@MXene/PES membrane effectively degraded antibiotics through peroxymonosulfate activation, achieving up to 95.51% degradation at a cobalt concentration of 0.01 mg/mL. The membrane demonstrated excellent antibacterial properties, minimal flux loss after repeated use, and robust anti-fouling performance, making it a promising solution for efficient antibiotic removal and stable water treatment.

A novel multifunctional photocatalytic membrane based on β-FeOOH for oily wastewater purification

In order to deal with the environmental pollution caused by complex oily wastewater, it is necessary to develop filtration membrane materials. However, significant challenges such as poor effect of emulsion separation, limited functionality, and susceptibility to membrane fouling require urgent resolution. Here, we successfully prepared a β-hydroxyl iron oxide/polydopamine-polyethylenimine/polyacrylonitrile (β-FeOOH/PDA-PEI/PAN) nanofiber membrane for treatment of complex wastewater by growing PDA-PEI on a blow-spinning PAN nanofiber membrane and decorating the membrane with β-FeOOH. The porous structure and the large number of hydrophilic groups greatly increase the hydrophilicity of the membrane and give the membrane high permeation fluxes (11531.26 L m−2 h−1) for surfactant-free kerosene-in-water emulsion. The loaded β-FeOOH nanorods increase the roughness of the membrane surface, which enhances the underwater superoleophobic ability of the membrane, and promotes the demulsification of the emulsion and makes it have high separation efficiency of 99.48 % for surfactant-stabilized kerosene-in-water emulsion. In addition, the β-FeOOH/PDA-PEI/PAN also exhibited high organic dye removal efficiency (99.38 %) due to the presence of β-FeOOH. The synergistic effect of low oil adhesion and photocatalysis enhances the antifouling and self-cleaning performances of the material. Significantly, the multifunctional membrane also shows exceptional oil/water separation ability and good stability. The presented synergistic strategy of β-FeOOH/PDA-PEI/PAN membrane materials represents a prospective candidate for the treatment of complex wastewater.

Glass catfish inspired subaquatic abrasion-resistant anti-fouling window fabricated by femtosecond laser electrodeposition

Abstract Transparent materials utilized as underwater optical windows are highly vulnerable to various forms of pollution or abrasion due to their intrinsic hydrophilic properties. This susceptibility is particularly pronounced in underwater environments where pollutants can impede the operation of these optical devices, significantly degrading or even compromising their optical properties. The glass catfish, known for its remarkable transparency in water, maintains surface cleanliness and clarity despite exposure to contaminants, impurities abrasion, and hydraulic pressure. Inspired by the glass catfish's natural attributes, this study introduces a new solution named subaquatic abrasion-resistant and anti-fouling window (SAAW). Utilizing femtosecond laser ablation and electrodeposition, the SAAW is engineered by embedding fine metal bones structures into a transparent substrate and anti-fouling sliding layer, akin to the sturdy bones among catfish’s body. This approach significantly bolsters the window's abrasion resistance and anti-fouling performance while maintaining high light transmittance. The sliding layer on the SAAW’s surface remarkably reduce the friction of various liquid, which is the reason that SAAW owns great anti-fouling property. The SAAW demonstrates outstanding optical clarity even after enduring hundreds of sandpaper abrasion, attributed to the fine metal bone structures bearing all external forces and protect the sliding layer of SAAW. Furthermore, it exhibits exceptional resistance to biological adhesion and underwater pressure. In a green algae environment, the window remains clean with minimal change in transmittance over one month. Moreover, it retains its wettability and anti-fouling properties when subjected to a depth of 30 meters of underwater pressure for 30 days. Hence, the SAAW prepared by femtosecond laser ablation and electrodeposition presents a promising strategy for developing stable optical windows in liquid environments.

Active-type piezoelectric smart textiles with antifouling performance for pathogenic control

Recently, an investigation into preventive measures for coronavirus disease 2019 (COVID-19) has garnered considerable attention. Consequently, strategies for the proactive prevention of viral pathogens have also attracted significant interest in the field of wearable devices and electronic textiles research, particularly due to their potential applications in personal protective equipment. In this study, we introduce smart textiles designed with optimized piezoelectric devices that exhibit antifouling performance against microorganisms and actively inactivate viruses. These active-type smart textiles, which incorporate advanced lead zirconate titanate (PZT) ceramics, a stretchable interconnector array, and polymeric fabric, demonstrate effective antifouling capabilities, detaching approximately 90% of Escherichia coli and 75% of SARS-CoV-2. Furthermore, they inactivate viruses, releasing ~26.8 ng of N protein from ruptured SARS-CoV-2, using ultrasonic waves within the wearable platform. Experimental results show that piezoelectric smart textiles significantly reduce the spread of COVID-19 by leveraging the electrical and acoustic properties of PZT ceramics.

Incorporation of Graphene Oxide Quantum Dots in Gradient Layers of Polyethersulphone Nanofiltration Membranes for Nitrate Rejection from Aqueous Solution.

Graphene oxide quantum dots (GOQDs) have been widely used to prepare nanofiltration membranes due to the merits of excellent dispersity, ultrasmall size, and unique properties related to graphene. In this study, we first prepared the polyethersulphone-based nanofiltration (PES-NF) membrane via an interfacial polymerization process using a piperazine and m-phenylenediamine mixed solution as the aqueous phase. Then GOQDs were incorporated into the top-down gradient structured layers (i.e., ultrathin layer, interlayer, and substrate membrane layer) of the nanofiltration membrane, and subsequently the effect of GOQD addition on the nitrate rejection was evaluated. Compared with the pristine PES-NF membrane without the incorporation of GOQDs, the fabricated NF membrane (GOQD/PES-NF-2) incorporating GOQDs at both the ultrathin layer and interlayer exhibits more remarkable performances (an acceptable permeation flux of 52.2 L m-1 h-1 and excellent nitrate rejection of 96.3% at 0.6 MPa), the permeation flux of this membrane increases by nearly 2.4 times, and its nitrate rejection also shows a slight enhancement (∼7.6%) compared with those of PES-NF. Remarkably, at the operating pressure much lower than that required by reverse osmosis membranes, the GOQD/PES-NF-2 membrane possesses an equivalent monovalent ion rejection to reverse osmosis membranes but a higher permeation flux. Furthermore, the result of a 7 day continuous stability test validates the excellent durability of the GOQD/PES-NF-2 membrane, and its antifouling and chlorine resistance performances also outperform those of the PES-NF membrane.

Bactericidal and Antifouling Coatings with the "Killing-Repelling-Killing" Triple Function Based on Cationic Copolymers with Structure Conversion and Capsaicin Analogue Release.

The capsaicin analogue N-(4-hydroxy-3-methoxybenzyl) acrylamide (HMBA) was linked with polylauryl methacrylate-b-poly(2-(N,N-dimethylamino)ethyl methacrylate) (PLMA-b-PDMAEMA) via a quaternization reaction with 4-(acrylamidomethyl)-2-methoxyphenyl 2-chloroacetate (AAMPCA). The amphiphilic copolymers were capable of transforming its structure in response to the solvent change from aprotic to protic, which was verified by the 1H NMR spectrum. The resulting cationic copolymers underwent a hydrolysis process in water, yielding zwitterionic groups on surfaces. Meanwhile, the bactericidal reagent HMBA was released. It was proved that the hydrolysis rate of the copolymers accelerated with higher temperature, higher pH value, and higher hydrophilic block units. And the controllable, sustainable release of HMBA was achieved with copolymer-mediated hydrolysis. Protein-repellent and bactericidal tests on the surface of the coating proved that antifouling and bactericidal performances of the coating correlated to the structure conversion abilities of the corresponding copolymer. The dynamic monitoring of Escherichia coli adhesion in 3 h evidenced the antifouling and bactericidal process of copolymers with different block ratios and concentrations. The coating incorporated with 3% PLMA120-b-(PDMAEMA-AAMPCA)120 in polylactic acid base materials showed an adhesion ratio of E. coli less than 1% within 1 h, and the survival ratio of the adhered bacteria is <1%, suggesting its rapid speed and high efficiency in "bacterial repelling and killing". Also, the PLMA120-b-(PDMAEMA-AAMPCA)120 copolymer demonstrated enhanced bactericidal ability compared with the mixture of cationic poly(laruyl methacrylate)120-b-poly(carboxybetaine methacrylate ester)120 (PLMA120-b-PCBMAE120) and free HMBA. The lowest minimal inhibitory concentration was 0.078 mg/mL against Staphylococcus aureus and 0.312 mg/mL against E. coli, respectively.

Engineering dual-reinforced antibacterial and anti-fouling ultrafiltration membrane by in-situ synthesising super-dispersion and high-activity silver nanoparticles (AgNPs)

Membrane fouling, especially biofouling, would result in frequent cleaning and shorten membrane lifespan. Fabricating Ag nanoparticle (AgNP)-modified ultrafiltration (UF) membranes provided an innovative solution for in-situ membrane biofouling control. Inspired by the tongue’s taste generation mechanism, this study adopted sodium citrate and AgNO3 to in-situ synthesize AgNP-modified UF (i-Ag-UF) membrane with the characteristics of ‘super-dispersion and high-activity’ AgNPs, enhancing the antimicrobial and anti-fouling properties. Compared to the control, a perpendicular and rich macroporous finger-type structure was engineered in the i-Ag-UF membrane, which contributed to a 59 % permeability improvement (421.7 L m-2h−1 bar−1), thereby improving filtration efficiency and reducing operational costs. This enhancement was attributed to the in-situ synthesis of small-sized, super-dispersed AgNPs, improving compatibility and stability with membrane matrix, and enhancing resistance to interlayer shear stress during phase inversion. Furthermore, the i-Ag-UF membrane surface exhibited the highest hydrophilicity and surface polarity, which formed a hydration layer and increased pollutant repulsion, thereby greatly enhancing its anti-fouling performance and achieving a higher flux recovery rate of 98.64 %. Such enhancement could significantly improve the economic benefits and sustainability of the UF process. The i-Ag-UF membrane demonstrated exceptionally high antibacterial efficiency (>99.99 %), attributed to the widely dispersed, high-activity AgNPs with numerous exposure points. In addition, the i-Ag-UF membrane, with only 2.5 wt% Ag release after 50 days owing to the entanglement between AgNPs and polymer chains. These findings provide new insights into the fabrication of highly antibacterial and anti-fouling dual-enhanced UF membranes.

Synergistic coating of Laponite swollen-layer and heparin composite for enhanced antifouling and antithrombotic performance

When implantable medical devices come into contact with blood, acute thrombosis and inflammation often occur due to the adhesion and denaturation of plasma proteins, ultimately degrading device performance. To address this issue, we developed a gel-like coating with superhydrophilic properties, incorporating a heparin based outer layer designed to minimize foreign body reactions and enhance hemocompatibility. The coating was engineered using a layer-by-layer (LbL) assembly of poly-l-lysine (PLL), laponite (Lap), and heparin (Hep), utilizing electrostatic interactions. The successful formation of stable layers was confirmed by QCM-D analysis. The inner layer, composed of PLL/Lap multilayers, formed a gel-like structure that maintained superhydrophilicity and effectively prevented cell adhesion. The outermost PLL/Hep multilayers significantly suppressed thrombus formation by inhibiting plasma protein and red blood cell adsorption as well as platelet activation. The coating exhibited excellent stability, retaining its superhydrophilic properties and heparin functionality even after 7 days of immersion in DPBS. Additionally, in vitro hemocompatibility and cytocompatibility tests confirmed its non-toxicity and overall biocompatibility. These results highlight the potential application of this coating to various implantable medical devices, providing a robust solution for improving device performance and safety.

MOF-based photothermal Janus membrane with robust anti-fouling performance for enhanced membrane distillation

As a promising desalination technology, photothermal membrane distillation (PMD) is confronted with challenges such as low freshwater yield and membrane fouling. Herein, we have introduced a copper-based metal-organic framework (Cu-CAT) into a hydrophilic/superhydrophobic polyvinylidene fluoride (PVDF) Janus tree-like nanofiber membrane (TLNMs) to construct photothermal Janus TLNMs (P-Janus TLNMs) for enhanced PMD. Given the exceptional photothermal properties of the hydrophilic Cu-CAT layer, coupled with the fine pore structure and elevated porosity characteristics of the superhydrophobic PVDF TLNMs, P-Janus TLNMs have demonstrated outstanding performance when integrated into a PMD system. Upon exposure to solar illumination of 1 kW·m−2, the P-Janus TLNMs achieved a remarkable surface temperature of 88 °C, yielding a permeation flux of 1.46 L m−2 h−1, a salt rejection rate exceeding 99.99 %, and an energy utilization rate of 81 %. Furthermore, after 20 days of continuous operation with simulated seawater containing oil and surfactant, the P-Janus TLNMs presented a salt rejection of 99.9 % and a stable permeation flux of 1.71 L m−2 h−1 at the feed/permeate temperatures of 24/20 °C. This work introduces a novel membrane with immense potential for boosting permeation flux and enhancing anti-fouling properties in PMD, thereby advancing the frontier of sustainable seawater desalination.

MXene and cellulose nanofibers reinforced hydrogel with high strength and photothermal self-healing performances for marine antifouling

Biological fouling is a considerable threat to the marine industry because attached microcontaminants and microorganisms inflict serious damage on marine installations and aquacultures. Although there has been tremendous effort in researching marine antifouling, it is yet challenging to develop a long-term and consistent antifouling strategy and materials. Here, polyhexamethylene-biguanide (PHMB) and MXene are introduced into the carboxylated cellulose nanofibers (CNF) reinforced polyvinyl alcohol (PVA) hydrogel to obtain a self-healing and ultra-high toughness antifouling hydrogel. The as-prepared double network (DN) hydrogels have extremely high toughness (16,050 kJ/m3), superior anti-protein adhesion (100 %) and anti-algal adhesion (100 %), exceptional antibacterial activity (99.97 %), and remarkable photothermal self-healing capability. Furthermore, the DN hydrogel provide outstanding antifouling performance for at least six months in the actual marine field. This work provides an effective and feasible strategy to prevent marine biofouling and also initiates new approaches to the application of hydrogel.

Fabrication of POSS-centered polyester network as high anti-chlorine and anti-fouling separation layer of membrane via successive Photo-ATRP and interfacial polymerization for molecular separation

The incorporation of polyhedral oligomeric sesquisiloxane (POSS), a distinctive nanoparticle, into the membrane separation layer represents an effective strategy for enhancing the chlorine resistance of membranes. This modification contributes to both the durability of the membrane and its separation efficiency. However, POSS is easy to agglomerate, which affects the separation performance of the membrane. In this paper, POSS-centered polyhydroxy polymer (OMEPOSS-P(GMA-NMDG)) was synthesized via photo-induced atom transfer radical polymerization and used as water-soluble monomer to prepare polyester separation layer on porous substrates through interfacial polymerization with trimelanoyl chloride. The obtained POSS-centered polyester membrane exhibits a high dye removal rate exceeding 99 %, and it can realize the screening of dye molecules with different molecular weight and different charge. Notably, the membrane demonstrates excellent chlorine resistance, maintaining effective separation efficiency after exposure to sodium hypochlorite solutions at concentrations of 10 000 ppm for 96 h and 1000 ppm for 7 days. It is worth noting that the membrane showed high anti-fouling performance. This method provides a useful guideline for the development of chlorine-resistant and anti-fouling separation membranes.

The synergistic actions of copper/l-glutamine co-grafting in improving anti-biofouling and desalination performances of reverse osmosis thin film composite membrane

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.

High-strength, super-hydrophilic alginate electrospun nanofibrous membranes for rapid oil-water emulsion separation

Ultrafiltration membrane separation technology is considered an effective method for separating oil-water emulsions. However, oil droplets can easily deposit on the surface of the membranes, leading to severe fouling and a decrease in flux. In this study, poly (ethylene oxide)/acrylamide/sodium alginate (PEO/AM/NaAlg) hydrogel nanofibers were deposited on a poly (hydroxybutyric acid) (PHB) electrospun nanofibrous membrane. Subsequently, superhydrophilic (ethylene oxide)-poly(acrylamide)/calcium alginate hydrogel nanofiber composite filtration membranes (PEO/PAM/CaAlg-PHB) were prepared by polymerization and Ca2+ cross-linking using a PHB electrospun nanofibrous membrane as the matrix. The morphology, tensile strength, water contact angle, and oil–water emulsion separation properties of the PEO/PAM/CaAlg-PHB hydrogel filtration membrane were investigated. The results showed that the PEO/PAM/CaAlg-PHB membrane had good anti-fouling performance, with a tensile strength of 1.95 MPa. After 3 h of the filtration operation, the stable flux and oil–water emulsion rejection of the membrane reached 2925.2 L m−2 h−1 bar−1 and 98.66 %, respectively. The preparation method was simple, cost effective, and environmentally friendly, without introducing any organic pollutants. The PEO/PAM/CaAlg-PHB hydrogel filtration membrane shows promise for separating oil–water emulsions.

Ultraviolet-cured polyurea-polyurethane acrylate/polysiloxane hybrid anti-fouling coatings with superior mechanical properties, transparency, and durability

The demand for rapidly preparing omniphobic liquid-like anti-fouling coatings has become increasingly important across a wide range of applications. However, achieving a rapid fabrication process that results in coatings with effective anti-fouling properties, alongside the comprehensive performance of the coatings such as hardness, flexibility, transparency, and abrasion resistance, remains a significant challenge. Herein, this paper proposes a synergistic strategy combining ultraviolet (UV) curing and organic/inorganic hybridization, which involves the rapid cross-linking of hyperbranched methacryloxypropyl polysiloxanes (HMO), polyurea-polyurethanes acrylate (SPUA) and bis-vinyl terminated polydimethylsiloxanes (PDMS-bvt) containing multiple double bonds under UV curing for just 60 s. Notably, HMO imparts excellent hardness (7H) and abrasion resistance, while SPUA enhances the coating's flexibility (2 mm bending diameter) and adhesion (5B). The anti-fouling properties of the coating are attributed to PDMS-bvt, which provides self-cleaning, anti-graffiti, and anti-fingerprint capabilities. Additionally, the coating's hydrophobicity and smooth surface significantly reduce ice adhesion strength (21.13 ± 6.9 kPa), offering a passive anti-icing effect. Furthermore, the coating exhibits excellent transparency, with a transmittance of >92 % in the visible region. The coating exhibits remarkable durability, maintaining its anti-fouling performance after exposure to mechanical abrasion (500 abrasion cycles and 1000 bending/release cycles), chemical corrosion (24 h of immersion in organic solutions), and UV aging (168 h). This strategy presents a fast and effective method for preparing multifunctional anti-fouling coatings, with potential applications on foldable screens, high-rise building glazing, and curved surfaces.

Enhanced anti-fouling and selective performance of GO-modified nanofiltration membranes for lithium extraction from salt lake brine

Nanofiltration (NF) is a promising method in lithium extraction from salt lake brine with a high Mg2+/Li+ mass ratio. However, membrane fouling challenges its applicability and productivity. This study incorporated graphene oxide (GO) into the polyamide (PA) selective layer of NF membranes to enhance anti-fouling properties and improve lithium extraction from brine. Membrane structure analyses revealed that 0.002 wt% and 0.01 wt% GO facilitated the interfacial polymerization reaction. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) results indicated that the PA selective layers in the GO-0.002 % and GO-0.01 % membranes were denser, smoother, and thinner. In contrast, the addition of 0.05 wt% GO resulted in the Turing structures on the membrane surface. Adsorption kinetics indicated pollutant adhesion in the following order: GO-0.05 % > GO-0 % > GO-0.002 % > GO-0.01 %, which was attributed to calcium-carboxyl complexation, as directly measured by AFM and consistent with carboxyl density. The GO-0.002 % and GO-0.01 % NF membranes demonstrated excellent anti-fouling properties in brines, with lower initial fouling rates and higher flux recovery after cleaning, underscoring the significant role of calcium-carboxyl complexation in membrane fouling. The retention of Mg2+ increased to 95 %, while that of Li+ decreased to below −28 % for GO-0.002 % and GO-0.01 % membranes, indicating promising potential for Mg and Li separation. This study provides valuable insights into developing NF membranes with high Mg/Li selectivity and anti-fouling capabilities for lithium extraction from salt lake brine.

Modified PVDF ultrafiltration membrane with host–guest supramolecular trapping for efficient separation of multiple organic contaminants

In our modern lifestyle, the cocktail of organic pollutants from everyday items, such as hair dyes, cloth dyes, food colours, hair oils, cooking oils, and agricultural proteins, enters water streams through household pipelines. This unnoticed contamination, growing alarmingly, poses a serious challenge beyond the scope of conventional separation techniques, calling for a comprehensive solution. While membrane technology offers a promising solution, it grapples with persistent surface fouling issues. This study introduces a novel approach through the development of extraordinary Polyvinylidene fluoride-Montmorillonite-Cucurbit[6]uril (PVDF-M-CB[6]) mixed matrix membranes, presenting a potential breakthrough in overcoming surface fouling challenges and offering a versatile solution for the separation of an array of organic contaminants. Powered by the synergistic host–guest supramolecular complexation of CB[6] onto montmorillonite (M) clay support, these membranes demonstrate swift and selective encapsulation, leading to superior cationic dye rejection. Adding to the allure, CB[6]’s structure encourages favorable carbonyl interactions with bovine serum albumin (BSA), effectively repelling the protein away from the membrane, while also promoting seamless oil–water emulsion separation with an underwater oil contact angle of 150 ± 3°, displaying its superoleophobic nature and enhancing remarkable antifouling properties. The PV-M-CB[6] membranes showcased 2x removal of cationic dyes, 1.3x removal of anionic dyes, 1.4x oil–water emulsion separation, and 2x BSA separation compared to the pristine polyvinylidene fluoride (PVDF) membrane. These membranes displayed 98.3 % efficiency in oil–water emulsion separation and sustained a flux recovery ratio of over >75% after seven cycles. Overall, PV-M-CB[6] membranes represent an innovative solution with heightened hydrophilicity, remarkable antifouling performance, and exceptional proficiency in delivering one-stop organic foulant separation.

High-permeance nanocellulose/ZnO hybrid membranes with photo-induced anti-fouling performance for wastewater purification

A hybrid ultrafiltration membrane based on nanocellulose and zinc oxide nanoparticles (ZnO NPs) was prepared by simple layered filtration without any chemical modification. Microscopic morphology analysis showed that the loading ZnO NPs significantly increased the membrane roughness, and wettability test demonstrated that the membrane surface possessed underwater superoleophobicity. Due to the “puncture effect” of the embedded ZnO NPs, abundant nanochannels were formed in the nanocellulose membrane and the highest water permeance of 5439.7 L·m−2·h−1·bar−1 was achieved. The hybrid membranes exhibited high rejection of nanoparticles larger than 20 nm and macromolecules with molecular weights higher than 100 kDa. Furthermore, ZnO NPs significantly improved the wet tensile strength of membrane. The hybrid membranes achieved high separation efficiency of nano-sized emulsions via size exclusion and demulsification effect, as well as the efficient removal of organic dyes and antibiotics via filtration-adsorption. The combination of underwater superoleophobicity and photocatalytic self-cleaning performance effectively solved the problem of a sharp decrease in permeance caused by oil contamination. This type of nanocellulose/ZnO hybrid membrane, which integrates high permeance, high filtration accuracy, and photocatalytic anti-fouling performance in one design, offers an innovative approach to the preparation of nanocellulose membranes for the treatment of organic wastewater.

Research Progress of Marine Anti-Fouling Coatings

The extended immersion of ships in seawater frequently results in biofouling, a condition characterized by the accumulation of marine organisms such as barnacles and algae. To combat this issue, the application of anti-fouling coatings to the hull surfaces of vessels has emerged as one of the most effective strategies. In response to the increasing global emphasis on environmental sustainability, there is a growing demand for anti-fouling coatings that not only demonstrate superior anti-fouling efficacy but also adhere to stringent environmental standards. The traditional use of organotin-based self-polishing anti-fouling coatings, known for their high toxicity, has been prohibited due to environmental concerns. Consequently, there is a progressive shift toward the development and application of environmentally friendly anti-fouling coatings. This paper reviews the toxicity and application limitations associated with conventional anti-fouling coatings. It provides a comprehensive overview of recent advancements in the field, including the development of novel self-polishing anti-fouling coatings, low surface energy coatings, biomimetic coatings, and nanostructured coatings, each leveraging distinct anti-fouling mechanisms. The paper evaluates the composition and performance of these emerging coatings and identifies key technical challenges that remain unresolved. It also proposes a multi-faceted approach to addressing these challenges, suggesting potential solutions for enhancing the effectiveness and environmental compatibility of anti-fouling technologies. The paper forecasts future research directions and development trajectories for marine anti-fouling coatings, emphasizing the need for continued innovation to achieve both environmental sustainability and superior anti-fouling performance.

Design of multiple anti-fouling and honeycomb-like NH2-AgBiS2 @g-C3N4 hydrogel layer onto PAN fiber membrane for multicomponent pollutant-oil-water emulsion treatment

Nano-structured hydrogel with unique anti-oil fouling property exhibits big advantage in oil/water separation, but its application in complex oily wastewater (contain oils, organic matter, bacteria, etc.) cleanup is hampered by the insufficient capabilities in multi-antifouling and synergistic treatment. Herein, we constructed the amino-rich NH2-AgBiS2/PANI (polyaniline)-g-C3N4 based multi-functional hydrogel functional layer onto the polyacrylonitrile (PAN) fiber membrane via polyphenol-mediated chitosan gelation and vacuum-assisted self-assembly techniques. The unique honeycomb-like structure and super-wetting feature synergistically contributed to the powerful oil resistance and flux breakthrough of composite membrane. Such membrane achieved superior permeability (up to 3558 L−1 m−2 h−1) for various SDS-stabilized oil-in-water emulsions and remarkable synergistic treatment efficiency of multicomponent pollutant-oil-water emulsion. The rational design of hydrogel layer on membrane surface intensified the photo-response ability and multiple electron transport channels, which offered the favorable photocatalytic self-cleaning performance towards degradation of organic dyes. According to the free radical quenching and EPR experiments, the photocatalytic mechanism was proposed. In addition, the inhibition rate of E. coli could reach 100 % under illumination of 24 h. Therefore, the integration of ultra-low oil adhesion, photocatalytic self-cleaning, and antibacterial features endows membrane with exceptional multiple anti-fouling performance, exhibiting unique advantages over traditional membranes in handling complex membrane fouling issues.

Facile and controlled dual-step modification with enhanced anti-fouling performance in polyvinylidene fluoride membranes

Water scarcity and pollution pose significant challenges, necessitating advancements in water treatment technologies. Among various solutions, ultrafiltration membranes, especially those crafted from polyvinylidene fluoride (PVDF), are favored for their mechanical robustness and chemical stability. However, their practical application is often limited by severe membrane fouling due to the inherent hydrophobicity of PVDF. This project introduces a straightforward, controlled method to enhance the anti-fouling properties of PVDF membranes, utilizing a blend of cellulose acetate (CA). The process involves a two-step modification of hydrolysis followed by quaternization, effectively increasing hydroxyl group presence and facilitating subsequent chemical reactions. The optimized membranes achieve a dynamic water contact angle of 0° within 30 s and maintain an electroneutral surface at pH 7.1. With a mean pore size reduction from 28.6 nm to 23.9 nm and an impressive drop in the irreversible fouling ratio from 36.9 % to 0.3 %, these modifications markedly improve the anti-fouling performance. This research demonstrates significant potential for enhancing the functionality of PVDF ultrafiltration membranes through post-fabrication modifications, offering significant benefits for water treatment applications.