Good Antifouling Performance Research Articles

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.

A novel nanofiltration membrane with a dual-charged layer to simultaneously remove anions and cations from acid mine drainage

A novel nanofiltration (NF) membrane with a positively and negatively dual-charged layer was finely designed in this study. The membrane was prepared by co-deposition of 4-tert-butylpyrocatechol (TBC) and polyethyleneimine (PEI) and electrostatic interaction to assemble positively and negatively charged functional layers on a substrate which is polyamide (PA)-based NF membrane. The NF membrane achieved excellent retention capacity through the combined effects of Donnan repulsion and electrostatic field trapping. The prepared membrane had a dense but thin surface layer with an average pore size of 0.84 nm, enabling an improved membrane flux of 8.66 L/(m2·h·bar) and high rejection to divalent inorganic salt ions (93.56 % Mg2+, 99.56 % SO42-). The membrane was used to treat acid mine drainage (AMD) and achieved an excellent retention capacity for ions in AMD (93.25 % Mg2+, 91.58 % Ca2+, 94.22 % Mn2+, 95.96 % SO42-), meeting industrial wastewater discharge standards. In addition, the NF membrane demonstrated good anti-fouling performance during the AMD treatment and significant potential for environmental remediation applications.

Low MWCO non-polyamide nanofiltration membranes synthesized in aqueous by coupling with catechol-amine chemistry and the oxidation-induced self-polymerization of m-phenylenediamine

Catechol-amine coatings offer versatile routes for surface modifications and nanofiltration (NF) membrane preparations. However, the formation of the selective layer is time-consuming and often deficient, rendering it unsuitable for large-scale applications. In this work, oxidation-induced self-polymerization and catechol-amine chemistry were combined to rapidly construct nanofiltration membranes in an aqueous medium. M-phenylenediamine (MPD) underwent oxidation and self-polymerized on a polysulfone (PSF) support. The addition of sodium periodate facilitated the subsequent tannic acid (TA) coating. The catechol-amine reaction between oxidized TA and poly-MPD forms crosslinked poly TA-MPD complexes, offering the resulting membrane a high selectivity. The role of NaIO4 in the selective layer formation and the influences of the synthesis parameters on the membrane performance were discussed. Utilizing the facile method enabled the achievement of a low molecular weight cut-off (MWCO) NF membrane (180 Da). The membrane exhibited a high water permeance (10.9 Lm−2h−1bar−1) and good salt rejections (93 % for Na2SO4). The filtration of the bovine serum acid (BSA) solution demonstrated the membrane has good antifouling performance with a flux recovery ratio (FRR) of 95.1 %. The proposed method offers a straightforward and rapid approach to fabricating low MWCO NF membranes in an aqueous medium, which has potential in large-scale applications.

Organic–Inorganic Composite Antifouling Coatings with Complementary Bioactive Effects

Traditional antifouling coatings are toxic to marine life, which makes developing new environmentally friendly marine antifouling coatings imperative. Antifouling coatings that are nonadhesive and antimicrobial may provide an effective approach to achieving this goal. In this study, an organic–inorganic composite coating consisting of fluorinated polyurethane (FPU) and carboxymethyl chitosan–zinc oxide (CMC–ZnO) was prepared to achieve antifouling. The coating took advantage of the complementary bioactive effects of the low surface energy of FPU and the antimicrobial properties of CMC–ZnO. The coating showed good antifouling performance, with a survival rate for Escherichia coli of 3.15% and that for Staphylococcus aureus of 3.97% and an anti-protein adsorption rate of more than 90%. This study provides a simple method for preparing antifouling coatings using nonpolluting raw materials with minimal adverse effects on marine environments.

Preparation of PVDF-nSiO2/PVSQ high-flux composite membrane by chemical grafting and separation of composite brine by membrane distillation

The large-scale application of membrane distillation (MD), an important method for desalting seawater, is limited due to membrane fouling. In this study, ethyl orthosilicate (TEOS) was polymerized to obtain different nSiO2 particles. Vinyl triethoxysilane (VTES) was hydrolysed and polycondensation was used to produce spherical polyethylene-sesquioxane (PVSQ) microparticles, which were modified to construct micro/nano particles. Then grafted on the surface of polyvinylidene fluoride (PVDF) composite membrane. The low-surface-energy hydrophobic groups present on the surfaces of the vinyl and ethoxy particles greatly enhanced the membrane hydrophobicity. The particle size of nSiO2 can change the properties of the membrane. The separation performance of the membrane was tested by direct contact membrane distillation (DCMD). In the separation of a constant concentration of feed solution (3.5 wt% NaCl), the membrane flux was relatively stable at 23.8 kg·m−2·h−1, and the salt interception rate reached 99.99 %. In the subsequent separation of a salt/humic acid solution, the flux remained stable and the good anti-fouling performance indicating that this system outperformed the unmodified membrane. Finally, the effect of different cations on the water diffusivity was studied using a molecular simulation method. Both Ca2+ and Mg2+ reduced the diffusion coefficient of water. However, when these two ions were present simultaneously, Ca2+ inhibited the binding of Mg2+ to water, and the diffusion coefficient of water increased. This study provides a novel approach for preparing hydrophobic membranes for the separation of complex brines.

An antifouling electrochemical aptasensor based on a Y-shaped peptide for tetracycline detection in milk

Nonspecific adsorption of non-target components (especially proteins) in food matrix on sensing surfaces deteriorates accuracy and sensitivity of electrochemical sensors, which is a key challenge for food safety sensing. Therefore, electrochemical sensors with antifouling capability of high-protein food matrices are highly desired. In this paper, an efficient and simple antifouling electrochemical aptasensor for tetracycline (TC) analysis was constructed based on a self-designed Y-shaped peptide [CPPPPEK-(RSERSERSE)2] consisting of cysteine as the anchoring segment, polyproline as the supporting segment, and -EK-(RSERSERSE)2 as antifouling branches. Hydrophilic and electrically neutral amino acid sequence and Y-shaped space structure of the peptide endow the sensing surface with good antifouling performance in protein solutions and diluted milk. Under optimized experiment conditions, the proposed aptasensor can detect TC with a wide linear range (0.01–100 ng mL−1) and a limit of detection of 5.3 pg mL−1 (S/N = 3). The spiked recovery experiments confirmed high accuracy of the aptasensor in diluted milk without other pretreatments (recoveries: 90.96%–95.86%). This strategy offers a valid way to reduce matrix interference, showing a promise to be extended to other sensing systems for different targets.

Antifouling and smart covalent organic framework composite nanofiltration membranes with light-gated molecular transport

Covalent organic framework (COF) holds great promise in affording precise and fast molecular separation. Inspired by the light-gated channels in cell membranes, we developed artificial light-gated molecular channel composite membranes by vacuum filtration COF with azobenzene (AZO) functional groups. The simple stimuli response could remotely adjust the membranes separation performance. The cis membranes with off state under ultraviolet (UV) light have higher dye rejection than trans membranes with on-state channels. The permeance of composite membranes increased from 19.56 to ∼ 42.30 L h−1 m−2 bar−1, dye (Rose Bengal (RB)) rejection increased from 94.40 % to 99.12 % after 10 min of 365 nm UV irradiation. In addition, the composite nanofiltration membranes exhibited good antifouling performance due to hydrophilic and highly smooth surface. By controlling the trans-to-cis AZO isomerization via UV /visible (Vis) light, the solvent permeance and dye rejection can be dynamically tuned due to the adjustable pore size.

Composite membranes from bio-inspired catechol-amine coatings for pervaporation desalination

Compared with reverse osmosis, pervaporation is less influenced by the osmosis pressure of the feed solution, which endows it as an attractive desalination technology. Many researches focus on developing high-performance pervaporation desalination membranes. Bio-inspired polyphenol coatings are versatile tools for engineering membrane surfaces. Here, catechol-amine chemistry was the first time applied to construct dense composite pervaporation desalination membranes via a stepwise coating method. Tannic acid (TA) and polyethyleneimine (PEI) were chosen as typical materials. Fabrication parameters, including TA and PEI concentrations in the coating solution, pH, and thermal annealing, are crucial to the desalination performance of the resulting membranes. The TA-PEI interactions were studied by the UV–Vis absorption spectroscopy method. The membrane prepared at optimal conditions exhibits excellent desalination performance. The water flux was 43 kg/(m2·h) at 50 °C for the feed of 3.5 wt% NaCl solution (95 kg/(m2·h) at 70 °C). The intrinsic hydrophilicity of the selective layer material ensures the membrane processes of good antifouling performance. This work demonstrates the possibility and potential of applying bio-inspired catechol-amine chemistry to prepare pervaporation desalination membranes.

Tannic acid etched ZIF-8 incorporated thin-film nanocomposite nanofiltration membrane with enhanced performance

Incorporating functionalized nanomaterials in the selective layer of conventional polyamide nanofiltration (NF) membrane is a promising strategy for overcoming the trade-off between permeability and selectivity. Highly hydrodispersible TA/ZIF-8 composite nanomaterials were prepared by etching ZIF-8 with tannic acid, and the thin-film nanocomposite (TFN) NF membranes were prepared by introducing TA/ZIF-8 into the interfacial polymerization aqueous phase solution. The nanomaterials and NF membranes' structure, chemical composition, and hydrophilicity were comprehensively characterized. The influence and mechanism of introducing TA/ZIF-8 into the polyamide layer on the separation performance of the TFN membranes were discussed by separating typical mono- and divalent salts. The optimal TFN membrane had a water flux of 26.59 LMH-bar−1 (increased by 86.6% than that of the TFC-blank membrane) with 94.95% rejection of Na2SO4 while having good antifouling performance and stability. Furthermore, the inverse size exclusion phenomenon of chlorine-contained salts was explored through relevant control experiments. This work is valuable for expanding the application of 3D nanomaterials in membrane separation technology and preparing high-performance TFN nanofiltration membranes.

An anionic polyethersulfone membrane modified by poly(2-acrylamide-2-methylpropanesulfonic acid sodium salt) grafted carbon nanotubes

Polyethersulfone membrane is easy to be polluted, and the negative surface would help enhance improve the permeability and the anti-pollution performance; so how to anchor polymer brushes with negative groups to polyethersulfone membrane surface is a challenge. In this paper, polymer brushes of poly(2-acrylamide-2-methylpropanesulfonic acid sodium salt) is first grafted to carbon nanotubes to form an organic-inorganic hybrid additive, which is further anchored onto the membrane surface of polyethersulfone by blending method. The graft reaction is proceeded by surface initiated electrochemical atom transfer radical polymerization, where the introduction of electrochemical part is because it could help better control the growth of polymer brushes compared with the pristine atom transfer radical polymerization process. The carbon nanotubes grafted with poly(2-acrylamide-2-methylpropanesulfonic acid sodium salt) could anchor on the membrane surface because the there is a self-assemble process of organic-inorganic hybrid additive during phase inversion method, where the inorganic part carbon nanotubes firmly embedded into the membrane and the organic part can be fixed on membrane surface. The polyethersulfone membrane exhibits enhanced surface hydrophilicity, improved the permeability of the membrane, and good anti-fouling performance due to the negative charge and electrostatic repulsion brought by anionic surface of the modified membrane. When the mass of nanotubes grafted with poly(2-acrylamide-2-methylpropanesulfonic acid sodium salt) in the casting solution is 20 mg, the water flux can reach 365.5 L m−2 h−1, and the rejection ratios of both BSA and CR are close to 100% with good flux recovery and anti-fouling effect performance.

Development of novel ionic covalent organic frameworks composite nanofiltration membranes for dye/salt separation

Covalent organic frameworks (COF) have desirable properties such as high porosity, low mass density, excellent heat resistance and regulatable structure, making them an ideal candidate for membrane material. Traditional methods for preparing covalent organic framework composite membranes, such as interfacial polymerization, vacuum filtration, and covalent organic framework abrasive coating. Stand-alone COF membranes produced by the above methods usually suffer from problems such as poor mechanical properties. Here, we fabricated high performance COF composite membranes by modified casting-precipitation-evaporation method. The designed composite membranes consisted of the ionic COF (iCOF) selective layer and the support layer are applied in dye/salt separation. The high permeability (∼ 68 L h−1 m−2 bar−1), high dyes rejection (97% for Rose Bengal), and low salts rejection (∼ 2.86% for NaCl) are achieved by the iCOF functional layer. The as-prepared composite membranes have a hydrophilic and highly smooth surface, making them have good anti-fouling performance. In addition, the rigid pore structure of iCOF selective layer endows the composite membranes with excellent stability, the composite membranes maintain original structure under high pressure (6 bar) and ultrasonic treatment (16 kHz for 60 min). This work may open up a novel path to fabricate iCOF composite membranes, which exhibit great potential in dye/salt separation.

Preparation of acrylic metal salt resin containing capsaicin derivative structure and study of anti-fouling properties

Modifications of acrylic resins with environmentally friendly compounds often solve the problems of marine fouling. In this work, capsaicin derivatives-modified acrylic acid resins were successfully synthesized via free radical polymerization and condensation reactions of monomeric acrylic acid, capsaicin derivatives, metal salts and benzoic acid and structurally characterized by infrared spectroscopy and nuclear magnetism. The physicochemical properties of the synthesized resin coatings were tested with a rotary viscometer, gel permeation chromatography, video optical contact angle measurements and a laser confocal tester. The self-polishing and antifouling properties of the resins were investigated with dynamic simulation experiments, algae inhibitions, bacterial inhibition experiments and real sea antifouling experiments. By comparing with the acrylic resin without capsaicin derivatives, the acrylic resin with added capsaicin derivatives had good antifouling performance, and the optimal content was 2.5 %. In summary, the capsaicin derivative-modified acrylic metal salt resins have good self-polishing properties and antifouling properties.

Structure and performance of polyvinylchloride microfiltration membranes improved by green silicon oxide nanoparticles for oil-in-water emulsion separation

Oil-in-water (O/W) emulsion separation has received wide attention in the field of industrial water treatment. Mixed matrix polyvinylchloride (PVC) membranes containing 0.1–1.5 wt% silicon oxide (SiO2) as an inorganic additive obtained from two different sources were fabricated via the phase inversion method. The impact of embedding SiO2 in the PVC texture was studied by making a comparison between SiO2 nanoparticles prepared from common water reeds as a bio-source (namely bio SiO2) and commercial SiO2. The fabricated membranes were characterized via Fourier-transform infrared spectroscopy, field emission scanning electron microscope, and atomic force microscopy. Also, the water contact angle and water flux were measured. The results of the water contact angle revealed that modification of the PVC membrane by 0.5 wt% bio SiO2 reduced the contact angle from 82.3° for the neat PVC membrane to 29.7° showing that high enhancement in the membrane's hydrophilicity. The effect of oil feed concentrations (100–1000 mg/L) and temperature (25, 35, and 45 °C) on the treatment efficiency and permeate flux was investigated at trans-membrane pressures (1.5, 2.5, and 3.5 bar). The results showed that the permeation flux of the modified membranes was higher than that of the neat membrane due to enhancing the membrane's properties. Finally, the membranes were evaluated in a crossflow system with simulated O/W emulsion as a feed. The bio SiO2/PVC membranes have applicable potential in the oily wastewater treatment for their low price, good antifouling performance, and high removal efficiencies of NTU (over 98.15 %), COD (up to 99.19 %) for a membrane containing 0.5 wt% bio SiO2 used for 100 mg/L O/W emulsion.

Regulating water flux of loose nanofiltration membrane by dopamine and cellulose nanocrystals for enhanced dye/salt separation

Nanofiltration (NF) membranes are widely used for dye and salt separation, however, a dense NF membrane is generally formed during interfacial polymerization, inducing low permeability of the membrane. Herein, a loose structure of the NF was prepared and regulated by additional other components, such as dopamine (DA) and carboxylated cellulose nanocrystal (C-CNC) through changing the interactions between water and oil phases. The results show that C-CNC not only improves hydrophilicity of the separation layer, but also controls the layer smooth and loose. The obtained membrane with suitable loose structure exhibits high water permeance (37.5 L m−2 h−1 bar−1) and rejection (above 99 %) for dyes including methyl blue (MB), congo red (CR) and direct red 80 (DR80). Additionally, it exhibits low rejection towards NaCl (∼10 %) and Na2SO4 (∼14 %), but good dye/salt separation factor of 451. The as-fabricated membrane is proved to have long-term stability, chlorine resistance and tolerance towards complex conditions (such as wide pH range, high temperature and composite separation system). The membrane shows good antifouling performance as well. Over all, the prepared membrane is promising for practical applications in textile effluent treatment, resources recycle and molecular separation.

Construction and performance of waterborne organosilicon anti-fouling coating based on hydrosilylation

Under the background of “Dual Carbon” strategy, the coating technology of silicon-based materials replacing carbon-based materials has become a research hotspot. Owing to high-viscosity characteristic of raw materials involving divinyl-terminated polydimethylsiloxane (ViPDMSVi) and reinforcing components, existing approaches for the preparation of organosilicon coatings by hydrosilylation still consume a large amount of organic solvents, causing environmental pollution and inconsistent with the low-carbon strategy. Herein, a robust strategy to prepare hydrosilylation waterborne organosilicon coatings via rational design of the emulsification system to obtain two-component aqueous emulsions is reported. In this strategy, two reactive organosilicon surfactants were synthesized and compounded with corresponding anionic surfactants for emulsification of vinyl organosilicon components and polymethylhydrosiloxane (PMHS), respectively. The resultant two emulsions were cured via hydrosilylation to obtain the desired coating. Additionally, vinyl MQ resin was selected as reinforcing component to increase the density of the coating. The facts that water, ethanol, mud water and other common liquids can slide off cleanly, and oily markers on the coating surface can be easily wiped off, indicate the outstanding anti-fouling properties of the coating. Furthermore, even under various harsh environments such as high temperature, ultraviolet radiation and chemical corrosion, the coating still shows good anti-fouling performance. This work opens up a viable avenue for the preparation of waterborne organosilicon anti-fouling coatings.

Ultrahigh-flux two-dimensional metal organic frameworks membrane for fast antibiotics removal

Two-dimensional metal organic frameworks (2D-MOFs) membrane was constructed by in-situ deriving from CoFe-Layered double hydroxides (CoFe-LDH) on substrate membrane using hydrothermal strategy and LDH is fully converted to the 2D-MOFs based on X-ray diffraction (XRD) patterns. Compared to LDH membrane, 2D-MOFs formed a defect-free layer with higher hydrophilicity (water droplet quickly filtrated through membrane), interlayer space (1.03 nm), more negative charge (zeta potential = −18.4 mV at pH = 7.0) and lower molecular weight cut-off (436.1 Da). As a result, 2D-MOFs membrane presented superior water permeability (flux = 622.9 L m−2 h−1 bar−1) and tetracycline (TC) rejection (98.5%) at wide range of pH (5–9) and concentration (0.002–0.02 mM) of TC solution, superior to most state-of-the-art 2D membranes due to the synergy of fast water transport, molecular sieving and electrostatic repulsion. In addition, it also efficiently rejected other negatively charged antibiotics (e.g., norfloxacin and sulfamethoxazole) with high removal efficiency (>87%), which can break the trade-off between permeability and rejection. What's more, after filtration of simulated pharmaceutical wastewater for 2 days, flux loss and irreversible fouling resistance for 2D-MOFs membrane significantly reduced by 31.6% and 89.9% in comparison to the pristine membrane without the addition of MOFs, respectively; moreover, negligible leaching of 2D-MOFs demonstrated its good anti-fouling performance and stability, which was promising to remediate antibiotics contaminated water.

High performance forward osmosis membrane with ultrathin hydrophobic nanofibrous interlayer

The novel thin film composite (TFC) forward osmosis (FO) membrane with electrospinning nanofibers as support layer can alleviate internal concentration polarization (ICP). While the macropores of the nanofiber support layer cause defects in the polyamide (PA) layer. Therefore, hydrophobic polyvinylidene fluoride (PVDF) fine nanofibers were used as an interlayer to modulate the process of interfacial polymerization (IP) in this study. The results showed that the introduction of the interlayer improved the hydrophobicity of the support layer for achieving uniform, thin and defect-free selective polyamide (PA) layer. The water flux of TFC-PVDF was 58.26 LMH in the FO mode of 2 M NaCl, which was two times higher than that of the unmodified FO membrane. Lower reverse salt flux (4.91 gMH) and structural parameter (179.43 μm) alleviated the ICP. In addition, TFC-PVDF membrane showed good anti-fouling performance for SA (flux recovery ratio of 93.97%) due to high hydrophilicity, low zeta potential and low roughness. This study provides an easy and promising method to prepare defect-free PA selective layer on the macropores nanofiber support layer. The novel FO membrane shows high desalination performance and anti-fouling properties.

Mussel- and nacre-inspired dual-bionic alginate-based hydrogel coating with multi-matrix applicability, high separation stability and antifouling performance for oil/water separation

Natural hydrogel-modified porous matrices with superwetting interfaces are ideal for oil/water separation. In this study, inspired by two marine organisms, a novel hydrogel coating with multi-matrix suitability, high oil/water separation capability and antifouling properties was developed. Specifically, inspired by mussel byssus, hydrogel coating was successfully deposited on porous matrix surface based on the introduction of tannic acid (TA). Moreover, inspired by the “brick and mortar” microstructure of Pinctada nacre, silica particles were in-situ synthesized in the sodium alginate (SA)/Ca2+ hydrogel to provide the filling effect and to increase strength. Furthermore, Sodium alginate-tannic acid-tetraethyl orthosilicate (SA-TA-TEOS) hydrogel coating-modified membrane exhibited super-hydrophilic and underwater super-oleophobic performance (underwater oil contact angle >150°), and achieved efficient oil/water separation for four oil/water emulsions (flux = 493–584 L·m−2·h−1 and rejection = 97.3–99.5 %). The modified membrane also demonstrated good anti-fouling performance and flux recovery. Notably, hydrogel coating-modified non-woven fabric also had high oil/water separation capacity (rejection >98 %) and cyclic stability, which proved the universal applicability of this hydrogel coating. In short, this work provides new insights into the fabrication of hydrogel coating-modified porous materials based upon a marine organism biomimetic strategy, which has potential applications in separating oil/water emulsions in industrial scenarios.

Assessment of marine antifouling property of fluoropolymer nanocomposite coating on steel substrate ‐ A preliminary assay in laboratory

AbstractThis paper presents the results of immersion assay on antifouling performance of a fluoropolymer nanocomposite coating on the steel substrate using natural seawater medium in laboratory. The fluoropolymer nanocomposite coating was composed in the presence of reinforcement additives, including organically modified titanium dioxide (m‐TiO2), organically modified zirconium dioxide nanoparticles (m‐ZrO2) and antifouling agent of Cu2O nanoparticles and fluoropolymer. The ratio of m‐TiO2/m‐ZrO2/Cu2O was fixed at 2/2/5 wt.% in comparison with the fluoropolymer weight. The immersion test was applied to evaluating the antifouling performance of the nanocomposite coating in the natural seawater and has been carried out in dynamic condition at the room temperature of 30 ± 0.1 oC during 60 days of testing. The change in characteristics of the nanocomposite coating was observed and recorded weekly including contact angle, color of coating and the released Cu ions content. Other characteristics such as infrared spectroscopy, surface morphology, abrasion resistance and adhesion of the nanocomposite coating were analyzed before and after testing. The obtained results showed that Cu ions could release with a low rate from the nanocomposite coating when rising immersion time and the release of Cu ions followed a linear equation. The contact angle and gloss of the coating were slightly reduced during testing period, indicating that the smoothness of the coating surface did not change significantly when immersed in natural seawater. The adhesion and abrasion resistance of the coating were almost unchanged after 60‐day testing. In summary, the nanocomposite coating has good antifouling performance when immersion under natural seawater in the laboratory, considering the above specific characteristics, including the synergistic effect of reinforcement fillers (m‐TiO2, m‐ZrO2 nanoparticles) and antifouling agent (Cu2O nanoparticles) in the polymer matrix. This in‐lab experiment in natural seawater medium has confirmed the nanocomposite coating's antifouling performance and facilitated practical deployment.

Construction of tannic acid-Fe complex coated PVDF membrane via simple spraying method for oil/water emulsion separation

Here, a polyvinylidene difluoride composite membrane (PVDF@TA–Fe membrane) was prepared via the repeated spraying of tannic acid (TA) and Fe3+ to form a TA–Fe complex on the hydrophobic PVDF membrane, which endows the membrane surface superhydrophilicity. The effects of the number of sprays on the surface wettability and emulsion separation capacity of membrane were systematically investigated. It was found that the TA-Fe(III)-complex network formed on the membrane significantly increased the hydrophilicity of the membrane, and the PVDF@TA–Fe membrane was found to exhibit superhydrophilicity/underwater superoleophobicity. The PVDF@TA–Fe membrane was found to exhibit good separation efficiencies (above 99%) and high fluxes (1189.1–2310.0 L m−2 h −1 bar−1) when used to separate oil and water in various oil/water emulsions. The repeated separation experiments show that the membrane has a good antifouling performance and maintains a good oil/water separation performance after more than 10 cycles. The present work is of great importance to the large-scale preparation of superhydrophilic membranes and treatment of oily wastewater.