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The printing and dyeing wastewater has high chromaticity, biorefractory properties, and significant toxicity. In this study, PVDF-PVA/GO was synthesized for dyes' adsorption with various chemical properties. Incorporating graphene oxide (GO) into the composite substantially enhanced the hydrophilicity and electronegativity of the PVDF membrane. Results indicated that the adsorption efficiencies for rhodamine B (RhB) and methylene blue (MB) are higher than those of methyl orange (MO) and bromocresol green (BCG). At an initial pH of 8, the maximum adsorption capacities for RhB and MB were 11.81 and 9.25 mg/g, respectively, while MO and BCG indicated considerably lower capacities of 0.59 and 0.63 mg/g, respectively. The cyclic utilization of the PVDF-PVA/GO revealed minimal degradation in adsorption efficiency. The adsorption kinetics of the four dyes primarily follow intra-particle diffusion mechanisms, resulting in the binding of dye molecules to the PVDF-PVA/GO membrane through electrostatic interactions. Notably, competitive adsorption phenomena were observed in mixed dye systems, especially between RhB and MB. Comparative analyses indicated an increased adsorption capacity for MB in the mixed dye system, accompanied by a notable reduction in the adsorption capacity of RhB. This study provides a theoretical foundation for the remediation of printing and dyeing wastewater. Highlights: PVDF-PVA/GO membrane was prepared for the printing and dyeing wastewater treatment. The loading of GO significantly improved the hydrophilicity of PVDF membranes. Anionic, cationic, and non-ionic dyes exhibited opposite adsorption. There are differences in adsorption between single-dye and mixed-dye systems. [ABSTRACT FROM AUTHOR]

With an emphasis on improving the membrane’s long-term durability and filtering efficiency, this study examines how well nanoparticle-modified polyvinylidene fluoride (PVDF) membranes perform in postponing membrane aging. The functionalization of PVDF membranes with mesoporous silica nanoparticles (MSNs) to increase their resistance to fouling and degradation makes this study novel. Sol–gel synthesis was used to create MSNs, which were then included in the PVDF membrane matrix. Brunauer–Emmett–Teller surface area analysis, X-ray diffraction, and scanning electron microscopy were used to analyze the structural characteristics of the modified membranes. The findings showed that adding MSNs improved the mechanical strength and permeability of the membrane by increasing its surface area and pore volume. Comparing the modified PVDF membranes to the unmodified membranes, aging tests revealed a slower drop in filtering performance and increased resilience to fouling and chemical degradation. According to these results, MSN-modified PVDF membranes are a promising material for water treatment and other filtering applications since they have a great deal of potential to increase the longevity and effectiveness of filtration systems.

This study examines the polyvinylidene fluoride (PVDF) ultrafiltration membrane impregnated with the copper acetate monohydrate/nickel chloride/thiourea (CuNit) nanoparticle through its physical properties, chemical properties, water flux, humic rejection, and antifouling properties against peat water. The ultrafiltration membrane was fabricated via phase inversion by blending CuNit nanoparticles (1, 3, and 5 wt/wt PVDF %) and PVDF (16 wt %) in N‐Methyl‐2‐pyrrolidone (NMP, 42 wt %) as the solvent. The humic rejection and fouling test are conducted using peat water collected from the Beladin water treatment plant. As a result, M03, which has 1 wt/wt PVDF % of CuNit nanoparticle, gives a better result of pure water flux, humic rejection, and fouling recovery rate with a value of 82 L/m2 h, 93 %, and 40 % compared to pristine PVDF membrane. The fouling of M03 recorded a low total rate of fouling (76 %) that is caused by high reversible fouling and low irreversible fouling with a value of 0.16 and 0.59, respectively, compared to the pristine PVDF membrane. In conclusion, due to the agglomeration that occurs in the further addition of CuNit nanoparticles, coating or encapsulation must be done to improve the stability of nanoparticles and reduce the leach‐out problem as well as provide a good distribution between the nanoparticle and casting solution during the membrane fabrication. [ABSTRACT FROM AUTHOR]

With the rapid industrial development worldwide, the volume of oily wastewater, including petroleum spills and industrial effluents, has increased dramatically, posing a threat to ecosystems and human health. Membrane separation technology, known for its advantages of phase-transition-free operation, low energy consumption, and simplicity, has gained rapid popularity in wastewater treatment. This study focused on modifying PVDF membranes using PVA-TA hydrogels with two distinct coordination strategies: TA-Fe3+ coordination and APTMS covalent cross-linking. The resulting composite membranes exhibited superhydrophilic/underwater superoleophobic properties with high emulsion flux (3800–6900 and 4200–12,000 Lm− 2h− 1bar− 1) and separation efficiency (> 98.9% and > 99.3%) for various oil-water emulsions. Notably, the stability of the hydrogel network allowed the composite membranes to maintain elevated fluxes (6847.2 and 10266.7 Lm− 2h− 1bar− 1) and separation efficiencies (97.8% and 99.3%) even after 10 cycles for dichloroethylene-water emulsion. The addition of Fe3+ and APTMS enhances hydrogel stability and roughness, with APTMS contributing to superior wetting and separation performance. This work provides valuable insights into the impact of different coordination mechanisms on hydrogel-coated membranes, offering a foundation for the development of advanced materials in efficient oil-water separation. [ABSTRACT FROM AUTHOR]

Abstract Photocatalytic membranes are effective in removing organic dyes, but their low UV resistance poses a challenge. To address this, self-protected photocatalytic PVDF membranes were developed using polyaniline (PANI) and polydopamine (PDA), whaich are anti-oxidation polymers, as interlayers between the membrane and TiO2. PVDF membranes were first modified by a self-polymerization layer of either PANI or PDA and then coated with titanium dioxide (TiO2). The TiO2 remained firmly attached to the PANI and PDA layer, regardless of sonication and prolonged usage. The PANI and PDA layers enhanced the durability of PVDF membrane under UV/TiO2 activation. After 72 h of irradiation, PVDF–PDA–TiO2 and PVDF–PANI–TiO2 membranes exhibited no significant change. This process improved both separation and photocatalytic activity in dye wastewater treatment. The PVDF–PDA–TiO2 and PVDF–PANI–TiO2 membranes showed enhanced membrane hydrophilicity, aiding in the rejection of organic pollutants and reducing fouling. The modified membranes exhibited a significant improvement in the flux recovery rate, attributed to the synergistic effects of high hydrophilicity and photocatalytic activity. Specially, the flux recovery rate increased from 17.7% (original PVDF) to 56.3% and 37.1% for the PVDF–PDA–TiO2 membrane and PVDF–PANI–TiO2 membrane. In dye rejection tests, the PVDF‒PDA‒TiO2 membrane achieved 88% efficiency, while the PVDF‒PANI‒TiO2 reached 95.7%. Additionally, the photodegradation of Reactive Red 239 (RR239) by these membranes further improved dye removal. Despite an 11% reduction in flux, the PVDF–PDA–TiO2 membrane demonstrated greater durability and longevity. The assistance of PANI and PDA in TiO2 coating also improved COD removal (from 33 to 58–68%) and provided self-protection for photocatalytic membranes, indicating that these photocatalytic membranes can contribute to more sustainable wastewater treatment processes.

This study explores the development of a thermostable and bio-inert PVDF membrane by grafting poly(acrylamide-r-N-vinylpyrrolidone) (P(AA-r-NVP)) onto a styrene-co-maleic anhydride (SMA)-functionalized PVDF substrate. The fabrication process involved blending SMA into the PVDF matrix followed by vapor-induced phase separation process to form the porous membrane. P(AA-r-NVP) was then grafted onto the membrane through the ring-opening of maleic anhydride groups. Characterization through ATR-FTIR and XPS confirmed successful surface modification. Antifouling performance of the membranes were assessed through bacterial adhesion tests before and after steam sterilization. Before sterilization, SMA3_A3V7 effectively resisted up to 97 % of E. coli adhesion. After steam sterilization, SMA3_A3V7 demonstrated excellent thermal stability, with a minimal 1.25 % increase in bacterial adhesion, compared to a 250 % increase in the unmodified PVDF membrane. These findings feature the effectiveness of utilizing SMA in simplifying the grafting process and the contribution of the thermostable and bio-inert polymer in imparting high-temperature resistance and antifouling resistance to the membrane, enabling versatile applications.

Photocatalytic membranes are crucial in addressing membrane fouling issues. However, the grafting amount of the catalyst on the membrane often becomes a key factor in restricting the membrane's self-cleaning capability. To address the challenge, this manuscript proposes a method for solving membrane fouling, featuring high grafting rates of bismuth oxide (Bi2O3) and acrylic acid (AA), significant contaminant degradation capability, and reusability. A highly photocatalytic self-cleaning microfiltration membrane made of polyvinylidene fluoride bismuth oxide and acrylic acid (PVDF-g-BA) was prepared by attaching nano Bi2O3 and acrylic acid onto the polyvinylidene fluoride membrane through adsorption/deposition and UV grafting polymerization. Compared with pure membranes and pure acrylic grafted membranes (PVDF-g-AA), the modified membrane grafted with 0.5% bismuth oxide not only improves the grafting rate and filtration performance, but also has higher self-cleaning ability. Furthermore, the degradation effect of this membrane on the organic dye methyl violet 2B under visible light irradiation is very significant, with a degradation rate reaching 90% and almost complete degradation after 12 h. Finally, after repeated filtration and photocatalysis, the membrane can still significantly degrade contaminants and can be reused. [ABSTRACT FROM AUTHOR]

This study investigated the development of poly(vinylidene fluoride) (PVDF) hybrid ultrafiltration membranes, where ZIF-8 nanocrystals are synthesized in situ within the membrane pores. These ZIF-8 embedded membranes are specifically designed for the treatment of emerging pollutants, such as ibuprofen. The optimized membrane, characterized by a higher concentration of ZIF-8 and greater surface coverage, exhibited significantly enhanced performance and improved properties, including increased hydrophobicity and mechanical strength. By increasing the zinc concentration from 0.2 to 0.3 M during the preparation of the ZIF-8 coated membrane, hydrophobicity was enhanced, as indicated by an increase in the contact angle from 60.3° to 87.2°, along with improved porosity from 41.3% to 60.5%. Further performance enhancements were achieved by encapsulating enzymes, specifically laccase and peroxidase, within the ZIF-8 coated membrane. A comparison of ibuprofen removal by these enzymes showed that peroxidase was slightly more effective, reaching a maximum removal efficiency of approximately 45% within 2 h. The biocatalytic membranes demonstrated a high stability and reusability, underscoring their potential for efficient ibuprofen removal. These findings highlight the efficacy of ZIF-8-coated PVDF membranes as advanced tools for water purification, offering significant improvements in both purification efficiency and membrane stability.

17α-methyltestosterone (MT) hormone is a synthetic androgenic steroid hormone utilized to induce Nile tilapia transitioning for enhanced production yield. This study specifically focuses on the removal of MT through the utilization of photocatalytic membrane reactor (PMR), which employs an in-house polyvinylidene fluoride (PVDF) ultrafiltration membrane modified with 1% nanomaterials (either TiO2 or α-Fe2O3). The molecular weight cut-off (MWCO) of the in-house membrane falls within the ultrafiltration range. Under UV95W radiation, the PMR with PVDF/TiO2 and PVDF/α-Fe2O3 membranes achieved 100% MT removal at 140 and 160 min, respectively. The MT removal by the commercial NF03 membrane was only at 50%. In contrast, without light irradiation, the MT removal by all the membranes remained unchanged after 180 min, exhibiting lower performance. The incorporation of TiO2 and α-Fe2O3 enhanced water flux and MT removal of the membrane. Notably, the catalytic activity was limited by the distribution and concentration of the catalyst at the membrane surface. The water contact angle did not correlate with the water flux for the composited membrane. The degradation of MT aligned well with Pseudo-first-order kinetic models. Thus, the in-house ultrafiltration PMR demonstrated superior removal efficiency and lower operational costs than the commercial nanofiltration membrane, attributable to its photocatalytic activities. HIGHLIGHTS TiO2 and α-Fe2O3 were incorporated as catalysts in the photocatalytic membrane reactor (PMR).; Under UV radiation, the PMR achieved high 17α-methyltestosterone removal.; Low-energy intensive PMR could achieve high flux and low fouling.; The efficiency of the PMR under UV radiation was greater than the NF03 membrane.;

Polyvinylidene fluoride (PVDF) membrane has shown potential for CO2 capture due to their chemical stability and mechanical strength. The coating process using polypropylene (PP) influenced the CO2 flux. This study optimises the coating parameters on the PVDF membrane using Box-Behnken Design (BBD). Key factors examined were methyl ethyl ketone (MEK) concentration, operating time and coating cycles. The investigated PVDF membrane was employed in the membrane gas adsorption (MGA) to examine the CO2 flux. Experimental data were fitted to a second-order polynomial quadratic model, yielding an R² value of 0.9028, indicating a strong fit. The optimisation revealed that 25% MEK concentration, 30 min of operating time and single coating cycle obtained the highest desirability score of 0.945. Significant factors include the MEK concentration (p-value of 0.0228), operating time (p-value of 0.0018) and coating cycles (p-value of 0.0164). This model effectively captures the linear and interaction effects of the variable on the CO2 flux. The optimised parameters significantly enhance the CO2 flux, contributing to the development of a high-performance membrane for CO2 capture. The application of the optimised PVDF membrane in MGA system demonstrates its efficiency in CO2 separation. This study advances membrane technology, providing a robust framework for future research in CO2 separation. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF) membranes are extensively utilized in membrane distillation (MD) for water treatment. However, traditional methods easily form asymmetrical membranes with dense skin layers that are detrimental to membrane flux. Herein, an eco-friendly PVDF membrane was fabricated by utilizing a delayed phase separation process without using any pore-forming agents. In addition, methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate (PolarClean) was used as a green solvent without posing risks to humans and the environment. It was demonstrated that the PVDF concentration is crucial in influencing the microstructures and performance of the resulting membranes. As the PVDF concentration increased, the morphology changed significantly, resulting in a reduction of pore size. When feeding the device with NaCl solution at a concentration of 35 g/L, the MD water vapor flux reached 18.49 kg·m−2·h−1, while maintaining a salt rejection of over 99.97% during the continuous operation for 24 h. This work presented a method for producing green PVDF membranes via delayed phase inversion with satisfactory water vapor flux and salt rejection, highlighting their prospect for effective applications in MD for water treatment.

Nannochloropsis sp., which is abundant in the ocean and has a high carbohydrate content, has great potential if used as a raw material for bioethanol. However, the low concentration of microalgae in the culture medium (0.5-2 µg/L) and the small size of the microalgae Nannochloropsis sp. (2-8 µm) become problems in the harvesting process. This study aims to increase the concentration of Nannochloropsis sp. during the harvesting process using a LiCl-modified polyvinylidene fluoride (PVDF) membrane. In addition, a computational approach was used to select the best solvent for PVDF and explain the conformational changes of PVDF. The results showed that N-Methyl-2-pyrrolidone is the best solvent for PVDF polymer (the lowest solvation energy is -86.25 Kjmol−1, and the highest binding energy is 1.8 Kjmol−1). The membrane, with the addition of 2% LiCl, had the best performance, increased the microalgae concentration ten times (from 596.4 to 5098 ppm), flux (150 Lm−2h−1bar−1), and rejection (100%). Adding LiCl to the dope solution increased the water flux (from 516 to 614 Lm−2h−1bar−1), changed the PVDF conformation from alpha to beta, and decreased the hydrophobicity of the membrane (from 94.89 to 81.68 °). Layer pore fouling is the fouling that plays a role in reducing microalgae flux during microalgae filtration by Nannochloropsis sp. Meanwhile, the type of washing recommended to overcome layer pore fouling is rinsing by increasing the speed of the filtration flow and immersion in chemical compounds.

l-Noradrenaline (l-NE) is a neurotransmitter released by postganglionic neurons in the sympathetic nerve branch and stimulates the secretion of l-NE in human blood. Accurate monitoring of the l-NE concentration in serum is crucial for detecting stimulants and preventing fraud in competitive events. In this study, we introduce an approach for the detection of l-NE using a zeolite-like lanthanide metal–organic framework (Ln-MOF) named Eu0.479Tb0.521-ZMOF, constructed with a H2bpdc ligand (where H2bpdc stands for 2,2′-bipyridine-6,6′-dicarboxylate acid), and forming a nanorod. Notably, the ratiometric luminescent probe Eu0.479Tb0.521-ZMOF showcases superior sensing performance compared to single emission based on Ln-MOF, enabling highly efficient detection of l-NE among various antidepressant hormones. The limit of detection (LOD) for l-NE was 129 μM. Additionally, Eu0.479Tb0.521-ZMOF has been synthesized into nanorods, which promote effective detection of l-NE in human serum solutions, exhibiting an impressive recovery rate ranging from 97.5 to 100%. Additionally, a luminescent membrane, derived from Eu0.479Tb0.521-ZMOF, was successfully developed and utilized for visual detection of l-NE. In conclusion, our study comprehensively elucidates the detailed detection mechanism for l-NE based on zeolite-Like Ln-MOFs Eu0.479Tb0.521-ZMOF. [ABSTRACT FROM AUTHOR]

Methyl orange (MO) is a colored dye and hazardous organic pollutant, which poses threats to human health and the environment. Photocatalytic degradation is widely used to remove MO in water because of its high efficiency and no harmful pollution products. The photocatalytic degradation efficiency of titanium dioxide (TiO2) catalysts has been limited by photogenerated electron/hole recombination. Multi-walled carbon nanotubes (MWCNT) can improve the separation and migration rate of photogenerated electrons. The poly(vinylidene fluoride) (PVDF) membrane with good flexibility, good connectivity and easy recovery, can be selected as carrier material for the photodegradation of MO in water. Here, the hydrophilic TiO2@MWCNT/PVDF membrane was synthesized to photodegrade MO in water and showed excellent pollutant removal efficiency (80%). The novel TiO2@MWCNT/PVDF membrane is a promising photocatalyst for degrading organic pollutants in water. [ABSTRACT FROM AUTHOR]

In this investigation, CoFe2O4-PVDF and CoFe2O4-ZnO-PVDF hybrid membranes were prepared using a modified phase inversion method in which a magnetic field was applied during the casting process to ensure a uniform distribution of nanomaterials on the membrane surface. Thus, better absorption of light and increased participation of nanoparticles in the photodegradation process is ensured. The influence of nanomaterials on the crystalline structure, surface morphology, and hydrophilicity properties of the PVDF membrane was investigated. The obtained results indicated that the hybrid membrane exhibited significant differences in its intrinsic properties due to the nanomaterials addition. The hydrophilicity properties of the PVDF membrane were improved by the presence of nanoparticles. The photocatalytic decomposition of aqueous Rhodamine B solution in the presence of the prepared membrane and under visible light irradiation was tested. The hybrid membrane containing CoFe2O4-ZnO on its surface exhibited a high removal rate. [ABSTRACT FROM AUTHOR]

In this paper, electret treatment was used to enhance the electrostatic repulsion between the membrane and bovine serum albumin, so as to improve the anti‐fouling ability and recycling rate of the membrane. The polarization charge is provided by the dipole orientation of polyvinylidene fluoride (PVDF) materials, and the space charge is composed of the interfacial charge between the filler and the matrix and the bulk charge of the hollow structure of the multi‐walled carbon nanotubes. The results showed that after electret treatment, the surface potential of the membrane increased, the PVDF crystal type changed from α to β, and the crystallinity increased. Grafting of N‐vinylpyrrolidone onto multi‐walled carbon nanotubes (MWCNTs‐g‐PVP), which contain a large number of hydrophilic groups after modification, reduces the contact angle of the composite film from 86.9° to 62.7°. The pure water flux and flux recovery rate of MWCNTs‐g‐PVP/PVDF composite membranes after electret treatment was increased from 189.31 L·m−2·h−1 and 90% to 233.55 L·m−2·h−1 and 94.7%, respectively, and the rejection rate increased about 30%. Through the circulation experiment, it can be seen that the anti‐fouling performance and recycling rate of the membrane is improved, which is caused by electrostatic repulsion. [ABSTRACT FROM AUTHOR]

Membranes combined with nanoparticles are an excellent combination capable of successfully removing various contaminants, such as dyes from wastewater while using very little energy and decreasing pollution. The present study reports an efficient approach for Remazol Black 5 (RB5) dye removal using composite graphitic carbon nitride nanosheets (g‐C3N4), polysulfone (PSF), and polyvinylidene fluoride (PVDF) membranes. The membranes were prepared using the phase inversion method, with varying quantities of g‐C3N4 nanosheets ranging from 0.1%, 0.2% to 0.3%. The prepared g‐C3N4 nanosheets were characterized by FTIR, SEM analyses, and zeta potential measurements. FTIR and SEM studies, contact angle, water permeability, COD, and dye rejection measurements were used to characterize the g‐C3N4 nanosheets embedded in PSF and PVDF membranes. After the addition of 0.3 wt% g‐C3N4, the water flux of the 0.3 wt% g‐C3N4 embedded PSF membrane was the highest, whereas the water flux of the 0.3 wt% g‐C3N4 embedded PVDF membrane was the lowest. The ultrafiltration (UF) membrane's performance with g‐C3N4 embedded showed an RB5 rejection rate of more than 80% and a COD removal efficiency of more than 45%. The results of the experimental filtration showed that RB5 rejection reached maximum values of 91.3% for 0.1 wt% g‐C3N4/PSF, and 85.6% for 0.3 wt% g‐C3N4/PVDF. [ABSTRACT FROM AUTHOR]

Oil‐fouling of the membranes limits further application in the separation and purification of oil‐in‐water emulsions. Here, anti‐oil fouling membranes are engineered by the method of non‐solvent induced phase separation (NIPS) which enriches the polysulfonated dopamine (PSDA) and polyethyleneimine (PEI) (PSDA‐PEI) to the top surface from mixed casting solution. The obtained membrane achieves excellent anti‐oil fouling property as high as 98.2% oil rejection, yet it still possesses good flux of 2362.5 ± 110.9 and 1252.3 ± 71.8 L m−2 h−1 for the separation of 1,2‐dichloroethane‐in‐water and toluene‐in‐water emulsions. This can be attributed to outstanding hydrophilicity and super underwater superoleophobicity for mussel‐inspired PSDA‐PEI layer. In addition, the membrane also has excellent stability in acid (pH 1, 3, and 5) or alkali (pH 10 and 12) solutions. This work provides a facile method to engineer underwater superoleophobic membranes with excellent anti‐oil fouling by mussel‐inspired chemistry for oily water treatment. [ABSTRACT FROM AUTHOR]

Conventional oily wastewater treatment can remove slick oil and dispersed oil well, but it is difficult for it to remove emulsified oil. Nonetheless, the development of super wetting materials provides a key role in treating the emulsified oil, but there are some problems, such as expensive raw materials, complicated processes, as well as secondary pollution. In order to treat these problems, a brand-new oil/water separation membrane (TEA/PVDF membrane) was developed by combining the viscosity of sodium alginate (SA) and the filter tea powder (TEA) onto the surface of the polyvinylidene fluoride (PVDF) membrane by a vacuum pump. Furthermore, the underwater oleophobic angle reached 135o. Moreover, the oil-water separation experiments of oil-in-water emulsion utilizing TEA/PVDF membrane demonstrated excellent separation efficiency (99.6%) and good flux (254 L m−2 h−1 bar−1). Notably, upon ten cycles, the oil removal rate was still as high as 99.2%. Moreover, the TEA/PVDF membrane was able to separate oil-in-water emulsions in environments with strong acids, strong bases, and high salt concentrations, with a separation efficiency of over 95.9%. Such a novel oil/water separation membrane is economic, environmentally protective, and simple production process, which exhibits overwhelming potential in practical life for treating oily wastewater. [ABSTRACT FROM AUTHOR]

This study highlights a comprehensive investigation into the fabrication and characterization of sustainable membranes for antifouling applications. It utilizes γ-valerolactone as a green solvent to obtain microfiltration polyvinylidene difluoride (PVDF) membranes, and leverages spray-coating technique to modify these membranes. This research aims to enhance the surface and bulk properties of PVDF membranes while promoting sustainable practices. Chemical analyses of the membranes reveal that the surface and bulk of the membranes were successfully modified. Dynamic water contact angle measurements indicated that a 10 mg/mL coating solution (PVDF_10) resulted in the highest hydrophilicity. Different biofouling tests were conducted using proteins and bacteria. In adhesion tests with BSA, and E. coli , the PVDF_10 membrane demonstrated the highest resistance, reducing adhesion by approximately 83 % and 94 %, respectively. Additionally, cyclical water/bacterial filtration tests demonstrated that PVDF_10 membrane achieved a higher flux recovery ratio compared to commercial hydrophilic PVDF membranes. The modification remained stable even after 6 weeks of immersion in water. This study highlights the potential of γ-GVL and the spray-coating technique as environmentally friendly solvents and modification techniques for producing green antifouling PVDF membranes, aligning with sustainable practices and significantly enhancing membrane performance. [Display omitted] • γ-Valerolactone is utilized to fabricate environmentally friendly antifouling PVDF membranes. • Surface and bulk of the membranes are effectively modified using a spray-coating technique. • Coating stability is maintained even after 6 weeks of immersion in water. • Strong resistance to protein and bacterial adhesion is demonstrated by the spray-coated PVDF membrane. [ABSTRACT FROM AUTHOR]

Ammonia is a toxic and hazardous substance, as well as a valuable chemical. The gaseous ammonia are soluble in water, rendering some industrial wastewater contains high concentration of ammonia. These wastewater can be a direct source for the production of commercially concentrated ammonia solution via sweep gas membrane distillation (SGMD). Taking advantage of vapor-liquid equilibrium of ammonia-water binary system, ammonia can be recovered from these wastewater, and concentrated to several times higher concentration under optimized conditions. In this work, we have demonstrated the ammonia recovery by SGMD process, and comprehensively investigated the effect of different operation conditions on the SGMD performance. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF) membrane was prepared by a two-step method of surface gelation-immersion precipitation. The surface of the scraping solution film was sprayed with polyvinyl alcohol (PVA) aqueous solution to gel the film surface first, and then the liquid film was immersed in a coagulation bath for phase transformation to obtain the surface modified PVDF membrane. The effects of PVA solution with different mass fraction on the structure and properties of PVDF membrane were studied. The results showed that with the increase of spraying PVA mass fraction, the contact angle of the upper surface of PVDF membranes gradually decreased, the porosity and mean pore size of PVDF membranes gradually increased, and the crystallinity of PVDF membranes gradually decreased. The pores on upper surface of the membranes first increased and then decreased, and the finger-like macropore structure appeared inside the membranes, the water flux first increased and then decreased, and the rejection rate increased. Dynamic cycle filtration experiment of bovine serum protein (BSA) solution showed an increase in membrane flux recovery from 68.31 to 95.08% and a decrease in the irreversible fouling rate from 31.69 to 4.92%, indicating an improvement in the hydrophilicity and antifouling properties of the modified PVDF membrane. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF) membranes blended with various amounts of MWCNT-ZnO (0.1%–3%) nanocomposites were prepared by the phase inversion method. The effect of nanocomposites blending on the membrane structural and morphological properties was investigated by XRD, FT-IR and SEM techniques. Contact angle measurement reveals that the hydrophilicity of the membrane increases with the increase of nanocomposite content; a reduction of the contact angle from 103° for PVDF to 49° for hybrid membrane was obtained. An optimum amount of 0.5% of MWCNT-ZnO blended in a PVDF hybrid membrane assured 85% removal rate of RbB under UV light irradiation. It was observed that the pollutant removal occurs through the simultaneous action of two processes: adsorption and photocatalysis. By blending with MWCNT-ZnO nanoparticles, the PVDF membrane acquires photocatalytic properties which assure a self-cleaning property in the membrane, increasing its lifetime. [ABSTRACT FROM AUTHOR]

Hydrogel coatings that can endow various substrates with superior properties (e.g., biocompatibility, hydrophilicity, and lubricity) have wide applications in the fields of oil/water separation, antifouling, anti-bioadhesion, etc. Currently, the engineering of multifunctional hydrogel-coated materials with superwettability and water purification property using a simple and sustainable strategy is still largely uninvestigated but has a beneficial effect on the world. Herein, we successfully prepared poly(2-acrylamido-2-methyl-1-propanesulfonic acid) hydrogel/β-FeOOH-coated poly(vinylidene fluoride) (PVDF/PAMPS/β-FeOOH) membrane through free-radical polymerization and the in situ mineralization process. In this work, owing to the combination of hydrophilic PAMPS hydrogel coating and β-FeOOH nanorods anchored onto PVDF membrane, the resultant PVDF/PAMPS/β-FeOOH membrane achieved outstanding superhydrophilicity/underwater superoleophobicity. Moreover, the membrane not only effectively separated surfactant-stabilized oil/water emulsions, but also possessed a long-term use capacity. In addition, excellent photocatalytic activity against organic pollutants was demonstrated so that the PVDF/PAMPS/β-FeOOH membrane could be utilized to deal with wastewater. It is envisioned that these hydrogel/β-FeOOH-coated PVDF membranes have versatile applications in the fields of oil/water separation and wastewater purification. [ABSTRACT FROM AUTHOR]

The membrane fouling issue has aroused great concern. To improve their antifouling properties, surface grafting with oxidative deposition were employed to amend a polyvinylidene fluoride (PVDF) membrane. The modifiers were amino-modified graphene oxide (AMGO), dopamine (DPA) and 1,3-diaminoguanidine hydrochloride (DAGH). To take bovine serum albumin (BSA, 1 g/l) as an example of organic materials, BSA interception rate and pure water flux recovery rate increased to 93.65% and 66.74%, respectively, while the corresponding values for the original membrane were much lower (72.82% and 31.72%). The optimum synthesis conditions were found to be 1.5 mg/ml of DPA, 1 wt% of DAGH, 2 mg/ml of AMGO, 4 h of DPA oxidation deposition time and 1 h of AMGO grafting time. Many functional groups like C = N, -NH2, C = O and -OH improved the membrane surface hydrophilicity leading to a higher resistance to organic pollution. Dopamine and guanidyl facilitated the antimicrobial performance of the modified membrane, whose antimicrobial rate was up to 96%, while the raw membrane had no antimicrobial activity. The amended membrane possessed 40% higher mechanical strength than the initial one. It could withstand a high pumping suction force. The noteworthy property was that the irreversible fouling rate decreased by 55%. Therefore, the amended membrane could restore its flux much more easily. HIGHLIGHTS The graphene oxide, dopamine and guanidine-based composite modification offered high hydrophilic and antibacterial radicals.; The irreversible pollution rate of the modified membrane decreased by 55%, its pure water flux recovery rate increased by twice and BSA interception rate was around 94%.; The antimicrobial rate of the modified membrane reached 96%, while the original one did not display any antimicrobial behaviors.;

Abstract In this paper, ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate was the first time successfully utilized as single solvent in preparing the PVDF membrane with a good performance by N-TIPs method. The effects of quenching temperature and hydrophilic additive content on the morphology, permeability, and strength of the membranes were studied. All the prepared PVDF membranes were proved to be a pure β phase by FTIR and XRD, possessing a narrow pore size distribution. By adjusting quenching temperature and additive content, membranes with a flux of 383.2 L/m2 h and concentrated pore diameter of 26 nm obtained.

This study reports the investigation of human serum albumin (HSA) adsorption on a poy-styrene-block–poly(acrylic acid) (PS-b-PAA)-coated PVDF membrane, which is a potential smart material for biomedical applications. First, copolymer coating on the membrane surface was successfully performed, due to the hydrophobic interaction of the PS anchoring group with the PVDF membrane. This was confirmed by Fourier transform infrared spectroscopy (FTIR) characterization of the membrane. Then, HSA adsorption onto the coated membrane was assessed and was proved to be strongly dependent on the pH of the protein solution. Indeed, both FTIR mapping and mass balance calculation using UV–visible spectroscopy displayed a greater HSA adsorption on the membrane at pH 5, even though it still took place at higher pH, but to a lower extent. Afterwards, an ionic strength influence study evinced the role of electrostatic interactions between HSA and the PAA layer on HSA adsorption. Dead-end filtration of HSA through the coated membrane confirmed the pH dependence of HSA adsorption on the coated membrane.

Landfill leachates (LFLs) pose a severe environmental threat given their high strength and the slow degradation nature of their organic and inorganic pollutants constituents. Hence, they are challenging to treat by conventional wastewater treatment methods. Although membrane distillation (MD) is promising for wastewater treatment, membrane wetting and scaling that lead to membrane fouling are the bottlenecks in applying this technology to LFLs. In this work, a commercial Teflon emulsion was used to modify the PVDF membrane via a simple dip-coating method, followed by depositing the PTFE particles onto the membrane surface via thermal curing crosslinking reaction. Hence, a Teflon/PVDF composite membrane was successfully prepared with resistance to sodium dodecyl sulfate wetting, CaSO 4 scaling, and humic acid fouling. Effects of the Teflon emulsion concentration and dipping time on the composite membrane's chemical composition, surface characteristics, porosity, mechanical properties, liquid entry pressure (LEP W), and direct contact membrane distillation (DCMD) performance were systematically investigated. The results showed that Teflon emulsion modification could improve the membrane surface's hydrophobicity, reduce pore size, and increase mechanical strength. The Teflon/PVDF composite membrane with 100% Teflon emulsion and 10 min dipping time exhibited the highest hydrophobicity and 144.3º water contact angle. The M 100 -10 membrane also exhibited stable performance for treating nanofiltration (NF) brine collected from the LFL. When concentrating the NF brine, the M 100 -10 membrane achieved only a 7.1% flux decay rate. Hence, the Teflon/PVDF composite membrane demonstrated excellent wetting, scaling, and fouling resistance. This dip-coating method is simple, low cost, easy to scale up, and has potential in the large-scale production of hydrophobic porous membranes. [Display omitted] [ABSTRACT FROM AUTHOR]

Poly (vinylidene fluoride) membranes were prepared by freeze-casting. The effects of PVDF concentration, and freezing temperature on the morphology, crystallization, and performance of prepared membranes were examined. Polymer concentration was varied from 10 to 25 wt%. The freezing temperature was varied from −5 to −25 °C. Dimethyl sulfoxide (DMSO) and distilled water were used as solvents and non-solvents, respectively. The first step of this study was devoted to estimating the optimal concentration of PVDF solution in DMSO. Membranes prepared at different ratios were characterized using physical and mechanical characteristics and porosity. The second step was to optimize the time required for the production of the membranes. In the third step, it was shown that the freezing temperature had a remarkable effect on the morphology of the membranes: as the temperature decreases, there is a transition from spherulite structures to interconnected pores. It was shown that the diversity in the pore pattern for PVDF affects remarkably the water permeability through the polymer membrane. During the monitoring of the spread of crystallized areas during the formation of the membrane, it was found that the crystallization of the solvent begins at localized points of the microscale, further crystallized areas spread radially or unevenly along the surface of the solution, forming contact borders, which can lead to changes in the properties of the membrane in its area. [ABSTRACT FROM AUTHOR]

[Display omitted] • PAA network polymer was used for the modification of PVDF membranes. • The fabrication process includes simple operation and low cost. • The modified membrane with Sac-100/PAA had stronger hydrophilicity. • The stable permeance to oil/water emulsion had increased for four times. • The modification effect had good ultrasonic stability. Dip coating technology is often used for hydrophilic modification of PVDF membrane surfaces due to its significant modification effect, simple process and low cost. Nevertheless, the relatively feeble binding forces between coating molecules and between the coating and the substrate membrane often raise concerns about the stability of modified membranes. This study utilized PAA and Sac-100 to develop a hydrophilic and negatively charged coating to improve the anti-fouling characteristics of PVDF membranes in the process of oil/water separation. Two modification reagents underwent ring opening crosslinking reaction and ultimately deposited on the surface of PVDF membranes in the form of a network polymer, thereby solving the stability problem of the modification coating. After the modification, the surface microstructure of the membranes remained unchanged, while the average pore size fell from 0.37 μm to 0.32 μm. The water contact angle of the modified membrane decreased to 39° suggesting an excellent hydrophilic property. The modified PVDF membrane exhibited exceptional resistance to fouling in the oil/water separation experiment, demonstrating a consistent permeance value of 212 L m−2 h−1 bar−1 that was four times higher than that of the original membrane. Following the cleaning process, the permeance of the modified membrane could be restored to a level of 74.5 %. [ABSTRACT FROM AUTHOR]

Modified polyvinylidene fluoride (PVDF) membranes were prepared by the phase inversion method via blending in situ formed nanosilver (Ag) and nanozirconium dioxide (ZrO2). Scanning electron microscopy of the membranes revealed that the surface pore size of the membranes was increased and distributed widely with the addition of modified nanosilver (Ag) and nanozirconium dioxide (ZrO2). The pores of the membrane were reduced due to excessive modification of the material when the content of zirconium dioxide was increased to 0.4%. XRD characterization showed that in situ synthesis of nanosilver (Ag) and nanozirconium dioxide (ZrO2) had been successfully blended in the membranes. The contact angle of the modified membrane ranged from 82.72° to 67.37°, which showed that the hydrophilic properties of the membrane were improved. The pure water flux of the modified membrane increased from 28.43 to 143.2 L/m2 h, indicating that the hydrophilicity of the modified membrane was enhanced significantly. The flux recovery rate of the modified membrane was obviously increased in the fouling experiment with BSA as the source of organic pollutants. The antimicrobial contamination of the membrane was greatly enhanced with the E. coli microbial contamination experiment.