Excellent Antifouling Performance Research Articles

A dual-functional layer modified GO@SiO2 membrane with excellent anti-fouling performance for continuous separation of oil-in-water emulsion

As the most significant target of membrane separation, the inadequacy of permeability and anti-fouling frequently constrain the application of the membrane in actual oily wastewater. Herein, a novel concept of membrane surface construction was proposed to mitigate this intractable problem, using SiO2 as the support layer and graphene oxide (GO) as the isolation layer. The best co-localization proportion of the support layer (56 mg/L) and isolation layer (3.5 mg/L) was determined by the separation performance of the modified membranes for the simulated emulsion. The thin GO layer could effectively prevent contaminants from entering the membrane pores without affecting its roughness. Based on the synergistic action of the isolation layer and support layer, the GO@SiO2 membrane could well implement emulsion purification with a stable permeability (654.11 LMHB) and high separation efficiency (99.41%). The superior anti-fouling performance of the membrane ensures its long-term cycling stability, with the permeability recovery rate of 89.75% (low-density oil) and 90.41% (high-density oil) after 10 repeated cycles. The storage stability also indirectly increases its value in practical applications. More importantly, the GO@SiO2 membrane also shows great potential for industrial emulsion treatment with excellent purification and cycling stability (permeability recovery rate of 84.01%).

An electrochemical biosensor for alpha-fetoprotein detection in human serum based on peptides containing isomer D-Amino acids with enhanced stability and antifouling property

The development of antifouling biosensors capable of detecting biomarkers at low concentrations in complex bio-fluids with many interference components is of great importance in the diagnosis and treatment of diseases. Certain zwitterionic peptides composed of natural L-amino acids have been used for the construction of low fouling biosensors and demonstrated excellent antifouling performances, but they are prone to enzymatic degradation in biological media, such as serum that contains a variety of enzymes. In this work, a novel antifouling peptide with the sequence of cppPPEKEKEkek was designed, and three unnatural D-amino acids were set at both ends of the peptide to enhance its tolerance to enzymatic degradation. An electrochemical biosensor was constructed by coupling the antifouling peptide with a conducting polymer polyaniline (PANI) to achieve accurate detection of alpha-fetoprotein (AFP) in clinical samples. Owing to the presence of the designed peptide with partial D-amino acids (pD-peptide), the biosensing interface showed significantly high antifouling performance and enhanced stability in human serum. Meanwhile, the pD-peptide based biosensor exhibited high sensitivity toward the target AFP, with the linear range from 0.1 fg mL−1 to 1.0 ng mL−1 and the limit of detection of 0.03 fg mL−1 (S/N = 3). This strategy of enhancing the stability (tolerance to enzymolysis) of antifouling peptides in biological samples provided an effective way to develop antifouling biosensors for practical applications.

Efficient removal of anionic, cationic textile dyes and salt mixture using a novel CS/MIL-100 (Fe) based nanofiltration membrane

The purification of hazardous textile dyeing wastewater has exhibited many challenges because it consists of a complex mixture, including dyestuff, additives, and salts. It is necessary to fabricate membranes with enhanced permeability, fouling resistance, stability, and superior dyes and salts removal from wastewater. Incorporating a highly water stable metal-organic framework (MOFs) into membranes would meet the requirements for the efficient purification of textile wastewater. In this study, nanofiltration (NF) membranes are fabricated by incorporating MIL-100 (Fe) into the chitosan (CS) through film casting technique. The effect of MIL-100 (Fe) loadings on chitosan characterized by FT-IR, XRD, contact angle measurement, FESEM-EDS, XPS, zeta potential, and surface roughness analysis. The membrane characterization confirmed the enhanced surface roughness, pore size, surface charge, and hydrophilicity. The CS/MIL-100 (Fe) membrane exhibited an improved pure water flux from 5 to 52 L/m2h as well as 99% rejection efficiency for cationic methylene blue (MB) and anionic methyl orange (MO). We obtained the rejection efficiency trend for the MB mixed salts in the order of MgSO4 (Mg2+ - 51.6%, SO42− - 52.5%) > Na2SO4 (Na+ - 26.3%, SO42− - 29.3%) > CaCl2 (Ca2+ - 21.4%, Cl− - 23.8%) > NaCl (Na+ - 16.8%, Cl− - 19.2%). In addition, the CS/MIL-100 (Fe) composite membrane showed excellent rejection efficiency and antifouling performances with high recycling stability. These stunning results evidenced that the CS/MIL-100 (Fe) nanofiltration membrane is a promising candidate for removing toxic pollutants in the textile dyeing wastewater.

The mussel-inspired micro-nano structure for antifouling:A flowering tree

Mussels are typical marine fouling organisms that attach to surfaces though secretions, which is generally the focus of research on mussel-related fouling. This study reveals “a flowering tree” structure on mussel shells with antifouling performance. Based on the antifouling mechanism of surface microstructure, we prepared mussel-like shells (P) using the biomimetic replication method. Mussel adhesion experiments were conducted to examine the anti-mussel performances of the mussel shells and P. The anti-diatom performances of the mussel-like shells were also evaluated using three types of diatoms. The mussels responded differently to different locations on the shells, and the flowering tree microstructure exhibited excellent antifouling performance. In addition, VP (P immersed in vinyl silicon oil) and HP (P immersed in hydroxyl silicone oil) were prepared. The anti-diatom performance of VP was better than those of P and HP, indicating that hydrophobicity has a greater influence on anti-diatom performance than electronegativity. The newly discovered antifouling micro-nano structure was parameterized, revealing that a branch of the flowering tree has an inclination of 13.3° to the surface with a height of 210.1 nm. The results of this study provide insights for further investigations of bionic micro-nano structures in the field of antifouling.

Simultaneous alkaline hydrolysis and non-solvent induced phase separation method for polyacrylonitrile (PAN) membrane with highly hydrophilic and enhanced anti-fouling performance

Microporous membranes are now favorably used as a separation tool for the purification of water and wastewater containing fine particles and macromolecular contaminants. However, organic fouling has often become one of the major problems hindering the wider applications of these membranes. In this study, a highly hydrophilic polyacrylonitrile (PAN) membrane with excellent anti-fouling performance was prepared from a method simultaneously combining alkaline hydrolysis and non-solvent induced phase separation (NIPS) processes together. The interplay of the PAN alkaline hydrolysis and NIPS was examined for its effects on both the structural and chemical properties of the prepared membranes. Morphological and porometric analyses confirmed that the new method produced PAN membranes with less macrovoids but highly ordered narrow flow channels in the cross-section structure, as well as a much denser selective surface layer with small and greatly uniform pore sizes. Characterizations in membrane surface wettability and chemical compositions revealed that the new preparation approach can endow the obtained membranes with significantly enhanced surface hydrophilicity as well as oleophobicity within a much shorter preparation time, in comparison with other conventional preparation methods, including the post alkaline hydrolysis of PAN membranes. Filtration experiments for oil (hexadecane)-in-water emulsion, NOM (humic acid) or protein (BSA) solutions have all confirmed that the developed membranes showed remarkably slow flux declining during filtration operation and high flux recovery by simple water flushing for membrane cleaning. Hence, it is anticipated that there is a great potential for the new approach to fabricate anti-fouling PAN membranes, especially for more challenging separation applications in water and wastewater treatment.

Ion-specific effect on self-cleaning performances of polyelectrolyte-functionalized membranes and the underlying nanomechanical mechanism

In chemical and environmental engineering processes, polyelectrolyte surfaces have been widely used and exploited for their antifouling and self-cleaning properties. Ions widely exist in these processes; however, the influence of ions has been conventionally over-simplified. Herein, we have investigated the ion-specific effect on the wetting behaviors on polyelectrolyte surfaces as well as the self-cleaning performance of polyelectrolyte-functionalized membranes. The underlying nanomechanical mechanisms were characterized by direct force measurements between water droplets and various polyelectrolyte surfaces in oil (i.e., toluene). Interestingly, the aqueous anions can significantly modulate the surface interactions through aligning or disordering interfacial water molecules, which subsequently facilitate or inhibit the water wetting behaviors on polyelectrolyte surfaces, respectively. The ion-specific effect of different anions coincides with the well-known Hofmeister series. In contrast, cations show negligible effect. The polyelectrolyte-functionalized membranes show excellent antifouling and self-cleaning performances to oil in KAc and KCl solutions, but relatively poor performance in KSCN solution, agreeing well with the force measurements. This work provides new insights into the ion-specific interaction mechanism between water and polyelectrolyte surfaces, with useful implications for the efficient use of the antifouling and self-cleaning properties of polyelectrolyte-based materials in various chemical and environmental engineering applications (e.g., membrane filtration, oil/water separation).

A novel mixed matrix polysulfone membrane for enhanced ultrafiltration and photocatalytic self-cleaning performance

Photocatalytic materials can be used as self-cleaning functional materials to alleviate the irreversible fouling of ultrafiltration membranes. In this work, the small size g-C3N4/Bi2MoO6 (SCB) blended polysulfone (PSF) ultrafiltration membranes was fabricated by hydrothermal and phase inversion methods. As a functional filler of ultrafiltration membranes, the small size g-C3N4 nanosheet decorated on the surface of Bi2MoO6 can enhance the photocatalytic performance for bovine serum albumin (BSA) degradation, and remove irreversible fouling under visible light irradiation. In addition, the introduction of SCB microspheres into PSF matrix obviously increased the porosity of ultrafiltration membranes. Therefore, the SCB-PSF ultrafiltration membranes displayed excellent antifouling performance (flux recovery ratio is 82.53%) and BSA rejection rates (94.77%). SCB-PSF also had high photocatalytic self-cleaning activity, indicating excellent application prospects in organic wastewater treatment.

Rapid curing and self-stratifying lacquer coating with antifouling and anticorrosive properties

Natural lacquers have long been used as environment-friendly and renewable coatings. Generally, they dry slowly and do not have fouling resistance limiting their applications. Herein, we report a rapid curing, self-stratifying amphiphilic hybrid lacquer coating with excellent antifouling and anticorrosive properties. The coating was prepared by using a natural lacquer coupled with hyperbranched polysiloxane terminated by multi-amine (HPSi) and silane-terminated amphiphilic telomer (S-FP) through a facile sol–gel process. The introduction of HPSi greatly shortened the drying time and improved the mechanical properties of the natural lacquer coating. As HPSi content increased, the drying speed and surface hardness of the coating increased. Particularly, the incorporation of a non-leaching, self-enriched amphiphilic telomer into the hybrid lacquer conferred it an excellent antifouling performance but preserved its anticorrosive and mechanical properties. The flexibility and bacteria-resistant ability of the coating were significantly improved with S-FP content. The study provides a new strategy for modification of natural lacquer, and the hybrid lacquers are expected to be used in development of coatings with both antifouling and anticorrosive performance.

Preparation and evaluation of natural rosin-based zinc resins for marine antifouling

Currently, it is highly desirable to develop a novel antifouling resin with a controllable hydrolysis rate and stable and effective antifouling performance for marine antifouling coatings. In our study, we prepared natural rosin-based zinc (RZn-x) resins by a relatively facile and green synthetic method from Zn(OH)2 and antimicrobial natural rosin, which is considered a toxicity-free raw material, thus ensuring the green and antimicrobial character of the material. In their optimal combination, the RZn-x coating surface exhibited ideal peeling behaviour upon immersion in seawater, which caused the WCA of the material surface to change from 55° before immersion to 135° after immersion for 60 days and enhanced the antifouling properties. Dynamic simulation experiments of these resins also demonstrated that the hydrolysis rate of this material immersed in dynamic seawater was related to the zinc content, and we could control the self-polishing ability of the resins by adjusting the content of Zn(OH)2 participating in the reaction. Moreover, hydrolysis led to a hydrophobic surface, which could prevent fouling organisms from adhering. Laboratory bioassays against BSA adsorption (immersed for 4 h: 1.986 μg/cm2), bacterial (over 95 % reduction) and marine algal adhesion (more than 60 % reduction) revealed outstanding anti-protein, bacteriostasis and anti-algal growth and adhesion properties compared to pure rosin and the control sample. The long-term antifouling capability in marine field tests indicated that the RZn-x resins maintained their antifouling activity for more than 6 months, especially RZn-50, which showed excellent antifouling performance.

Effect of different factors on treatment of oily wastewater by TiO2/Al2O3-PVDF ultrafiltration membrane

ABSTRACT An ultrafiltration membrane developed by our research group was applied to treat simulated emulsified oil wastewater. ATR-FTIR, SEM, TEM, and Zeta potential analyzes demonstrated that the modified ultrafiltration membrane (MM) has excellent stability and anti-fouling capacity than origin membrane (OM), which possesses a pure water flux of 260 L·m−2·h−1 and oil/water (o/w) rejection of 98.5 ± 0.33%. Inorganic salt CaCl2 has more considerable influence than MgSO4 and NaCl under the same mass concentration in the two membranes UF process. Along with concentration increasing, flux sharply reduces; meanwhile, the rejection has an opposite trend. Moreover, permeation flux has a maximum value, and the rejection also gets its optimal state under neutral conditions during the pH value of 2–12. The membrane also exhibits excellent anti-fouling performance and anti- o/w adsorption properties with an adsorption rate below 0.8% compared with OM, which has an adsorption rate of nearly 2.1%, respectively. A kind of new UF membrane developed by our research group was applied to treat simulated o/w. ATR-FTIR, SEM, TEM, and Zeta potential analyzes demonstrated that PVDF-Al2O3/TiO2 material has excellent stability and anti-fouling capacity. CaCl2 has the greatest influence than MgSO4 and NaCl under the same mass concentration. Moreover, permeation flux has maximum value and the rejection also gets its optimal state under neutral conditions during pH 2–12. The membrane also exhibits excellent anti-fouling performance and anti-O/W adsorption properties with adsorption rate below 0.8% compared with OM which has an adsorption rate nearly 2.1%, respectively.

A chitosan/dopamine-TiO2 composite nanofiltration membrane for antifouling in water purification

A major obstacle for the development of the cellulose-based nanofiltration membrane is its fouling. In this study, a novel cellulose-based composite nanofiltration membrane (CS/DA-TiO2-NFM) with excellent anti-fouling performance was prepared through casting of both chitosan (CS) and TiO2 modified by dopamine (DA-TiO2) on the cellulose substrate membrane. DA-TiO2 was successfully introduced into the surface of membrane, resulting in significant improvement in its hydrophilicity due to the formation of dense CS layers. Furthermore, both CS and DA-TiO2 were effective antimicrobial agents (against E. coli 90.6% and S. aureus 95.1%) that could minimize the accumulation of bacteria on the CS/DA-TiO2-NFM. For the antifouling test against BSA, the irreversible recovery ratio of the CS/DA-TiO2-NFM was only 23.25% of the control (no CS/DA-TiO2 modified NFM). In addition, the CS/DA-TiO2-NFM exhibited an increased rejection rate of MgSO4 (enhanced 40.93%) and water-flux (enhanced 18.10%) compared with the control. These results highlight the potential of the presented approach for designing membranes with effective separation performance and antifouling for drinking water treatment.

Preventing algae biofilm formation via designing long-term oil storage surfaces for excellent antifouling performance

Fabricating slippery lubricant-infused porous surfaces (SLIPS), typically composed of lubricant and microstructured surface, is an effective way to solve the problem of marine anti-fouling. In the present work, acetone acted as a volatile solvent, and epoxy resin acted as a linking agent were mixed with one-dimensional material with different length (300-nm carbon nanotubes, 300-μm carbon fiber, and 1-mm polyacrylonitrile fiber). After acetone volatilized, one-dimensional materials with different length could form various kind of internal or surface structures. 300-μm carbon fiber could form a hierarchical structure with both internal holes and vertical needle-shaped structures, which effectively ensured the storage stability of lubricant in the structure. And through 21 days of algae attachment experiment, compared with the bare epoxy resin, the lubricant-infused carbon fiber structure (SLIPS-EP/CF) displayed superior anti-fouling performance with the reduction rate of chlorella was 91.4% and the phaeodactylum tricornutum was 77.8%. Additionally, the TEM and SEM analysis showed the attachment of algae to the surface of lubricant, and it was interesting to observe that algae could be wrapped by silicone oil and could not produce algae biofilm, which was presented by the first time. Since the formation of algae biofilm was inhibited, a large number of algae attachment was avoided, thereby realizing effective antifouling performance.

A robust dually charged membrane prepared via catechol-amine chemistry for highly efficient dye/salt separation

Novel nanoporous membranes with superior permeability and exceptional molecular selectivity are highly desirable for wastewater treatment and reclamation. Herein, a 3D dual-charged multilayer membrane for efficient separation of dyes/salts is fabricated via catechol-amine chemistry surface engineering. Polyethyleneimine (PEI) is firstly coated on the hydrolyzed polyacrylonitrile substrate to construct a positively charged intermediate layer, followed by codeposition of tannic acid (TA) and poly-γ-glutamic acid (γ-PGA) to engineer a negatively charged top layer. During the polyphenol-induced competitive reaction processes, covalent interactions, hydrogen bonding and electrostatic adsorption among TA, γ-PGA and PEI hinder the rapid and uneven self-polymerization of TA, thus loosening the separation layer structure. In addition, the pre-reaction between TA and γ-PGA can weaken those competitive reactions, further tuning the pore size and dual charge layer thus improving the separation performance. Benefited from the novel loose dual-charged structure, the resultant membrane exhibits outstanding water permeability (36.9 Lm−2h−1bar−1) with low salt rejections (11.1% for Na2SO4 and 14.6% for NaCl) and high rejection to both positively and negatively charged dyes. It works well even for rejecting small-molecule dyes (100% congo red, 98% methyl green, 96% methyl orange and 86% methylene blue), far superior to the state-of-the-art membranes. Despite the loose structure, the membrane still possesses excellent acid resistance, and its hydrophilic surface contributes to excellent anti-fouling performance. Such thin-film composite membranes with tunable dual-charged multilayer prepared via this new strategy provides a promising candidate for separation of small charged molecules and inorganic salts, especially in textile industry.

Preparation of polyvinylidene fluoride modified membrane by tannin and halloysite nanotubes for dyes and antibiotics removal

Separation of dyes and antibiotics is particularly important in wastewater treatment. In this work, the hydrophilic modified polyvinylidene fluoride (PVDF) membranes were prepared by deposition of halloysite nanotubes (HNTs), tannic acid (TA) and ferric chloride (FeCl3). The surface morphology of the modified membranes was studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM). In addition, the Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) were used to evaluate the chemical compositions of the membrane. The measurements of water contact angle (CA) and pure water flux (Jw) show that the PVDF membrane has excellent permeability and hydrophilicity. The PVDF modified membrane has good separation performance for dyes, and the rejection ratios of methyl orange, methylene blue and rhodamine B were 98.2%, 94.6% and 96.9%, respectively. In addition, the rejection ratios of modified membrane for tetracyclines and bisphenol A were significantly improved. Most important of all, the TA-Fe(III)/HNTs/PVDF membrane has excellent antifouling performance after cycles tests. These results indicate that the TA-Fe(III)/HNTs/PVDF modified membranes have a great application prospect in dye and antibiotic wastewater treatment.

Sulfonic nanohydrogelled surface-modified microporous polyvinylidene fluoride membrane with excellent antifouling performance for treating water-oil separation of kitchen wastewater

Kitchen wastewater containing high concentration of suspended solids, salt and oil is a comprehensive wastewater that requires urgent treatment. Organic fouling limits the use of membranes for treating kitchen wastewater. Herein, we propose a novel sulfonic nanohydrogel membrane with superhydrophilicity and underwater-superoleophobicity. A 32-nm-diameter sulfonic nanohydrogel Poly(SPP-co-MA-co-FLUORAL-P), developed by the polymerization technique in an aqueous medium, was grafted onto the polyvinylidene difluoride (PVDF) microfiltration membranes. The developed PVDF-g-Poly(SPP-co-MA-co-FLUORAL-P) membrane exhibited excellent antifouling properties for treating kitchen wastewater. The influence of organics (edible oil, surfactant, protein and humic acid) and salts on the membrane filtration was thoroughly investigated. The Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy techniques were used to confirm the successful surface modification. The experimental results revealed that the pure water flux was 2161 L m−2 h−1. A high oil rejection rate was achieved when the fabricated membrane was used for treating the simulated kitchen wastewater (˃99.7%). The excellent antifouling properties of the membrane significantly improved the circulation stability of the simulated kitchen wastewater filtration. The recovery rate of permeation flux was up to 100%. The chemical oxygen demand removal rate of the real kitchen wastewater was 61% and the flux recovery rate arrived at 98%. The PVDF-g-Poly(SPP-co-MA-co-FLUORAL-P) membrane can be potentially used for treating kitchen wastewater.

Nature-mimicking fabrication of antifouling photocatalytic membrane based on Ti/BiOI and polydopamine for synergistically enhanced photocatalytic degradation of tetracycline

The photocatalytic efficiency of conventional blending photocatalytic membranes suffers a significant reduction due to effective photocatalyst embedded in membrane matrix. Therefore, in this study, inspired by the bioadhesive technology of polydopamine (pDA), a novel Ti doped bismuth oxyiodide (BiOI)-polydopamine (pDA)-coated cellulose acetate (CA) (Ti/BiOI-pDA/CA) photocatalytic nanocomposite membranes were successfully developed for effective removal of tetracycline (TC). The Ti/BiOI-pDA/CA nanocomposite membranes displayed very high photocatalytic activity toward TC (about 98% after 120 min) under visible light irradiation and superior photodegradation kinetics (k=0.03214 min−1). The removal rate of Ti/BiOI/-pDA/CA nanocomposite membranes under dynamic cyclic degradation system could be further improved, giving TC removal efficiency of 91% in 60min. Remarkably, the permeate flux, flux recovery ratio (FRR), reversible fouling (Rr), irreversible fouling (Rir) and the total fouling ratio (Rt) revealed the Ti/BiOI-pDA/CA nanocomposite membranes had excellent antifouling performance. In addition, the Ti/BiOI-pDA/CA nanocomposite membranes exhibited excellent stability and reusability. Therefore, this work gives insight into the effective removal of TC wastewater and has a great potential for new generation of high-performance photocatalytic membranes for practical wastewater treatment in the future.

One-step hydrothermal synthesis of the modified carbon cloth membrane: Towards visible light driven and self-cleaning for efficient oil-water separation

The CC@TiO2-Cu membranes with various Cu doping contents have been synthesized via a simple one-step hydrothermal method for oil-water separation application. It is found that a certain amount of Cu doping is beneficial for achieving visible light response and enhance the superhydrophilicity/underwater superoleophobic performance of CC@TiO2-Cu membranes. Importantly, the CC@TiO2-Cu2.5 membrane with cauliflower-like morphology shows excellent self-cleaning and antifouling performance under visible light driven. And its separation efficiency can still maintain up to 99.6% under gravity even after 80 cycles of oil-water separation experiments. The mechanisms of both oil-water separation and photocatalytic self-cleaning for the CC@TiO2-Cu membrane are discussed in detail. The study provides a new concept for designing self-cleaning membrane to apply in oil-water separation.

Review on carbon dioxide fixation coupled with nutrients removal from wastewater by microalgae

The application of microalgae in carbon dioxide (CO2) fixation coupled with wastewater treatment has been regarded as a promising and cutting-edge technology in recent years, but it still faces some problems. The CO2 fixation capacity and nutrients removal capacity of microalgae should be considered simultaneously under various environmental conditions. Moreover, breeding microalgae using a photobioreactor is required and critical for CO2 fixation and wastewater treatment. In addition, the related influenced factors, mechanisms and kinetics of CO2 fixation and nutrients removal by microalgae remains complex and unclear. Thus, this work provides an updated review of the literature regarding the application of microalgae in the remediation of wastewaters from different sources coupled with CO2 fixation, discusses the main interactions between biological or environmental factors and how they can influence nutrient removal and CO2 fixation efficiencies, and further focuses on their mechanisms and kinetics. It is found that blue-green algae are most suitable to fix CO2 integrating treated wastewater, but more microalgal strains with excellent anti-fouling performance, tolerance to high concentrations of CO2 and NH3–N performance need to be screened. Additionally, wastewater and gas conditions during the cultivation process should be optimized in research and applications, and development of innovative photobioreactors with low cost is also required. Furthermore, modelling mainly focuses on estimating biomass yield, nutrient removal rates and CO2 fixation rates, while laboratory modelling results deviated from the natural modelling results. Finally, this paper also provides insight into what should be done in future work to support the development of CO2 fixation coupled with wastewater treatment by microalgae.

Fabrication of omniphobic PVDF composite membrane with dual-scale hierarchical structure via chemical bonding for robust membrane distillation

In recent years, omniphobic membranes have drawn much attention due to the strong repellence to various liquids. In this study, a PVDF composite membrane with omniphobic characteristics was prepared by constructing dual-scale hierarchical structure and introducing long chemical chains with the low surface energy. The special architecture was derived from the immobilization of TiO2@PDA@Cu composite nanoparticles on the surface via chemical bonding, and the fluorosilanization treatment with 1H,1H,2H,2H-perfluorodecyltriethoxysilane for membrane surfaces. A series of characterizations were implemented to explore composite nanoparticles’ morphology and composition, as well as membrane morphology and surface analysis. In addition, anti-fouling and anti-wetting behaviors of pristine and composite membranes were investigated by successive direct contact membrane distillation (DCMD) experiments, in which different contaminations containing inorganic salts, organic matter, surfactants and mineral oil were chosen as the feed. The results displayed that composite nanoparticles were obtained through the chelating effect of polydopamine (PDA) and the dual-scale structure was realized with the assistance of trimesoyl chloride (TMC). The omniphobic membrane exhibited strong repulsive forces to various liquids, such as water, SDBS solution (0.4 mM), CTAB solution (0.4 mM), tween-20 solution (0.4 mM) and mineral oil emulsion (0.2% v/v) with the contact angles of 168.0 ± 2.0°, 157.1 ± 1.5°, 160.0 ± 1.2°, 158.3 ± 1.5° and 152.5 ± 3.0°, respectively. Furthermore, compared to pristine membrane, the omniphobic membrane presented superior stability, higher salt rejection rate and excellent anti-wetting and anti-fouling performances in the DCMD tests. Thus, the composite membrane with superhydrophobic and superoleophobic features possessed great application potential for high salinity wastewater treatment in membrane distillation.

Newly developed nanofiltration membrane blended with mesoporous silica with low transmembrane pressure and excellent anti-fouling performance

Newly developed nanofiltration membrane blended with mesoporous silica with low transmembrane pressure and excellent anti-fouling performance