Durable and chemical resistant ultra-permeable nanofiltration membrane for the separation of textile wastewater

Unlocking the potential of plant polyphenols: advances in extraction, antibacterial mechanisms, and future applications

Plant polyphenols are widely distributed in most higher plants, garnering significant attention from researchers due to their remarkable antioxidative, antibacterial, anticancer, and anti-radiation properties. They also offer multiple health benefits for various lifestyle-related diseases and oxidative stress. While there has been considerable research on the extraction and antibacterial application of plant polyphenols, developing a rapid and efficient extraction method remains a persistent challenge. Furthermore, the introduction of novel technologies is imperative to enhance the bioavailability of polyphenolic compounds. This comprehensive review synthesizes recent research findings pertaining to the extraction, antibacterial mechanisms, and applications of plant polyphenols. This research highlights the prevalent issues of low extraction rates of plant polyphenols and the ambiguous antibacterial mechanisms in current research. To address these challenges, this research proposes innovative directions for improving extraction technology and expanding antibacterial applications. Additionally, this review outlines promising future research avenues within the realm of plant polyphenols.

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N-Oxide Zwitterionic-Based Antifouling Loose Nanofiltration Membranes with Superior Water Permeance and Effective Dye/Salt Separation

Loose nanofiltration (LNF) membranes with high permeance and separation selectivity are highly desired for the effective separation of organic dyes and inorganic salts. Herein, a novel polyamide LNF membrane was fabricated using zwitterionic amine reactant trimethylamine N-oxide-based polyethylenimine (TPEI) and trimesoyl chloride (TMC) via interfacial polymerization (IP). A thin, loose, and smooth polyamide layer was formed due to the low diffusion rate and modified chemical structure of TPEI. The optimized membrane (NF-TPEI) exhibited an extremely high water permeance of 213.0 L m-2 h-1 bar-1, accompanied by outstanding dye rejections of Congo Red (99.8%), Coomassie Brilliant Blue R250 (99.5%), and Evans Blue (99.9%). Meanwhile, the membrane possessed low rejections (<7.0%) of inorganic salts (Na2SO4, MgSO4, MgCl2, and NaCl). Additionally, the NF-TPEI membrane exhibited outstanding antifouling performance, achieving a superior recovery ratio of 96.0 and 98.1% after the filtration of humic acid and sodium alginate solution, respectively. Compared to the commercial NF270 membrane, the NF-TPEI membrane exhibited significantly improved separation performance in terms of permeance and fouling resistance, which provided more possibilities for high-performance LNF membranes toward the treatment of wastewater with organic contaminants.

Mix-Charged Nanofiltration Membrane for Efficient Organic Removal from High-Salinity Wastewater: The Role of Charge Spatial Distribution

The efficient removal of organic contaminants from high-salinity wastewater is crucial for resource recovery and achieving zero discharge. Nanofiltration (NF) membranes are effective in separating organic compounds and monovalent salts, but they typically exhibit an excessive rejection of divalent salts. Modifying the charge characteristics of NF membranes can improve salt permeation; however, the role of charge spatial distribution in governing salt transport behavior is not fully understood. In this study, we developed a mix-charged NF membrane with a horizontal charge distribution by employing interfacial polymerization combined with a polyester template etching and solvent-induced polyamine intercalation strategy. The ratio of positive to negative charge domains in the membrane can be precisely controlled by adjusting the aqueous monomer ratio and polyamine modifier type. X-ray photoelectron spectroscopy (XPS) depth profiling and separation layer thickness analysis confirmed the complete penetration of polyamines into the separation layer, providing direct evidence of the formation of horizontally distributed charge domains. This unique charge distribution results in a high charge density and a near-electroneutral surface, which facilitates the permeation of the divalent salts. The size-dependent "plug-in" modification and covalent cross-linking further reduce pore size, enhancing rejection of small organic molecules. Additionally, the membrane demonstrated exceptional antifouling performance against both negatively and positively charged pollutants, attributed to its unique charge distribution and smooth surface. Molecular dynamics (MD) simulations further revealed that weak electrostatic interactions and a tightly bound hydration layer contribute to the membrane's superior antifouling properties. This work provides valuable insights into the design of NF membranes with tailored microstructures and charge distributions for improved water treatment performance.

Poly(arylene ether)s-Based Polymeric Membranes Applied for Water Purification in Harsh Environment Conditions: A Mini-Review

Confronting the pressing challenge of freshwater scarcity, polymeric membrane-based water treatment technology has emerged as an essential and effective approach. Poly(arylene ether)s (PAEs) polymers, a class of high-performance engineering thermoplastics, have garnered attention in recent decades as promising membrane materials for advanced water treatment approaches. The PAE-Based membranes are employed to resist the shortages of most common polymeric membranes, such as chemical instability, structural damage, membrane fouling, and shortened lifespan when deployed in harsh environments, owing to their excellent comprehensive performance. This article presents the advancements in the research of several typical PAEs, including poly(ether ether ketone) (PEEK), polyethersulfone (PES), and poly(arylene ether nitrile) (PEN). Techniques for membrane formation, modification strategies, and applications in water treatment have been reviewed. The applications encompass processes for oil/water separation, desalination, and wastewater treatment, which involve the removal of heavy metal ions, dyes, oils, and other organic pollutants. The commendable performance of these membranes has been summarized in terms of corrosion resistance, high-temperature resistance, anti-fouling properties, and durability in challenging environments. In addition, several recommendations for further research aimed at developing efficient and robust PAE-based membranes are proposed.

InSitu Integrated Fabrication for Multi-Interface Stabilized and Highly Durable Polyaniline@Graphene Oxide/Polyether Ether Ketone Special Separation Membranes

Special separation membranes are widely employed for separation and purification purposes under challenging operating conditions due to their low energy consumption, excellent solvent, and corrosion resistance. However, the development of membranes is limited by corrosion-resistant polymer substrates and precise interfacial separation layers. Herein, polyaniline (PANI) is employed to achieve insitu anchoring of multiple interfaces, resulting in the fabrication of polyaniline@graphene oxide/polyether ether ketone (PANI@GO/PEEK) membranes. Insitu growth of PANI achieves the adequate bonding of the PEEK substrate and GO separation interface, which solves the problem of solution processing of PEEK and the instability of GO layers. By bottom-up confined polymerization of aniline, it could control the pore size of the separation layer, correct defects, and anchor among polymer, nano-separation layer, and nano-sheet. The mechanism of membrane construction within the confined domain and micro-nano structure modulation is further explored. The membranes demonstrate exceptional stability realizing over 90% rejection in 2 m HCl, NaOH, and high temperatures. Additionally, -membranes exhibit remarkable durability after 240 days immersion and 100 h long-term operation, which display the methanol flux of 50.2 L m-2 h-1 and 92% rejection of AF (585 g mol-1 ). This method substantially contributes to special separation membranes by offering a novel strategy.

Fabrication of Naturally Derived Chitosan and Ilmenite Sand-Based TiO2/Fe2O3/Fe-N-Doped Graphitic Carbon Composite for Photocatalytic Degradation of Methylene Blue under Sunlight

Fabrication of chitosan and ilmenite sand-based novel photocatalysts through the catalytic graphitization of chitosan is reported. Nanocomposites consisted of TiO2, Fe2O3 and Fe nanoparticles dispersed on a nitrogen-doped graphitic carbon framework. The surface area, pore volume and macropore structure of the carbon matrix is disturbed by the heterogeneously distributed nanoparticles. The extent of graphitization expanded with increasing metal loading as indicated by variation in the ID/IG ratio. The nanomaterial’s surface consists of Fe3+ and Ti4+, and graphitic, pyridinic and pyrrolic nitrogen were found in the carbon matrix. The band gap values of the composites varied in the 2.06–2.26 eV range. The photocatalytic activity of the synthesized nanomaterials was determined, and the highest rate constant for the photodegradation of methylene blue under sunlight was 4.4 × 10−3 min−1, which resulted with 10 mg/L MB and 25 mg of the best-performing catalyst. The rate constant rose with increasing concentrations of persulfate added to the medium. The rate constant greatly diminished with the addition of isopropyl alcohol as it scavenged hydroxyl radicals. The presence of co-pollutants including Pb2+, rhodamine B, PO43− and Cl− curtailed the rate of reaction. The activity reduced with an increasing number of uses of the catalyst.

Positively charged membranes for dye/salt separation based on a crossover combination of Mannich reaction and prebiotic chemistry

With the advent of increasingly loose nanofiltration membranes for dye desalination, synthesis methods based on interfacial polymerization and bio-inspired materials such as polydopamine (pDA) have been investigated. However, the long polymerization time of pDA greatly limits the synthesis and application of fast dye/salt separation membranes. In this work, prebiotic chemistry-inspired aminomalononitrile (AMN) was used as a binder to co-deposit the Mannich reaction of tetrakis(hydroxymethyl)phosphonium chloride (THPC) and polyethyleneimine (PEI) to form the positively charged selective layer rapidly. The optimum membrane had a water permeance of 30.7 LMH bar^-1 and a rejection of positively charged Victoria blue B (VBB, 200 ppm) and Na₂SO₄ (1 g/L) of 99.5 % and 9.9 %, respectively. Moreover, the results of a practical application test showed that it had excellent separation performance towards various positively charged dyes and salts. In addition, the actual application test results show that the membrane has good long-term stability during application. In terms of antifouling and antibacterial, the membrane has excellent antibacterial and antifouling properties., Further antibacterial tests were carried out, and the inactivation effect of the membrane on E. coli was also confirmed. The preparation method proposed in this work provides technical support for developing new dye/salt separation membranes.

Polyphenol modified natural collagen fibrous network towards sustainable and antibacterial microfiltration membrane for efficient water disinfection

Because of their low-cost and high bacterial interception efficiency, large-scale membrane separation technologies like microfiltration (MF) have been widely implemented for water disinfection. However, lack of antibacterial ability and low sustainability are two major drawbacks of most petroleum-based MF membranes, which are normally associated with hazardous issues including biofouling and nonbiodegradable waste. In this work, abundant animal hides, which are by-products of the meat processing industry, were proposed as raw materials to fabricate a sustainable MF membrane due to their natural, hierarchical, and renewable collagen fibrous network (CFN) with inherent biodegradability. After the removal of non-collagen compositions from animal hides, such as hair and fat, through a facile pretreating process base on green chemistry principles, a thin CFN based membrane (CFN-M) with a similar micropore size to that of commercial MF membranes could be produced. Furthermore, inspired by conventional leather tanning technology, tannic acids (TA) were selected as plant polyphenol tanning agent to modify collagen fibers based on tanning chemistry to improve the thermal stability of CFN-M. Moreover, the TA cross-linked CFN-M (TA@CFN-M) exhibited excellent antibacterial properties due to the production of reactive oxygen species (ROS) by the catechol functional group. The resulting TA@CFN-M achieved >99.9% water disinfection efficiency with a flux of ∼150 L m^-2 h^-1 via gravity-driven operation, while simultaneously showing admirable anti-biofouling ability. Different from the commercial MF membrane, based on the green chemistry principle, this work may shed light on designing new sustainable and antibacterial membranes for anti-biofouling water disinfection.

D-spacing controllable GO membrane intercalated by sodium tetraborate pentahydrate for dye contamination wastewater treatment

Sodium tetraborate pentahydrate (STB) was intercalated into graphene oxide (GO) nanosheets to form a nanocomposite (STB@GO). Subsequently, it was self-assembled on a substrate membrane to prepare STB@GO nanofiltration membrane. The properties of the STB@GO powder samples and the nanofiltration membrane were studied using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), contact angle (CA), and zeta potential. When the STB concentration was 1.0 g/L in the cross-linking reaction, the membrane was described as the STB₂@GO membrane and exhibited a large interlayer space (d-spacing = 1.347 nm), high hydrophilicity (CA = 22.2°), and high negative potential (zeta = -18.0 mV). Meanwhile, the pure water flux of the membrane was significantly increased by 56.60% than that of the GO membrane. In addition, the STB₂@GO membrane exhibited a favorable capability for dye rejection,98.52% for Evans blue (EB), 99.26% for Victoria blue B (VB), 91.94% for Alizarin yellow (AY), and 93.21% for Neutral red (NR). Furthermore, the STB₂@GO membrane performed better in dye separation under various types and concentrations of dye, pH values, and ions in solution. Thus, this study provides a promising method for preparing laminated GO nanofiltration membranes for dye wastewater treatment.

Based On Confined Polymerization: In Situ Synthesis of PANI/PEEK Composite Film in One-Step

Confined polymerization is an effective method for precise synthesis, which can further control the micro-nano structure inside the composite material. Polyaniline (PANI)-based composites are usually prepared by blending and original growth methods. However, due to the strong rigidity and hydrogen bonding of PANI, the content of PANI composites is low and easy to agglomerate. Here, based on confined polymerization, it is reported that polyaniline /polyether ether ketone (PANI/PEEK) film with high PANI content is synthesized in situ by a one-step method. The micro-nano structure of the two polymers in the confined space is further explored and it is found that PANI grows in the free volume of the PEEK chain, making the arrangement of the PEEK chain more orderly. Under the best experimental conditions, the prepared 16 µm-PANI/PEEK film has a dielectric constant of 205.4 (dielectric loss 0.401), the 75 µm-PANI/PEEK film has a conductivity of 3.01×10-4 S m-1 . The prepared PANI/PEEK composite film can be further used as electronic packaging materials, conductive materials, and other fields, which has potential application prospects in anti-static, electromagnetic shielding materials, corrosion resistance, and other fields.

A nanofiltration membrane fabricated on a surfactant activated substrate with improved separation performance and acid resistance

Uniformly dispersed and enhanced amounts of PEI molecules attract drag by SDS exhibit a high crosslinking degree and smooth surface morphology.