One-step fabrication of multifunctional composite polyurethane spider-web-like nanofibrous membrane for water purification

Spectroscopic monitoring of polyurethane-based nanocomposite as a potential catalyst for the reduction of dyes

In this study, AgNPs-loaded polyurethane-sodium alginate (PU-S/Alg) composite polymers were prepared by precipitation polymerization and in-situ reduction method. Their catalytic potential was evaluated for the reduction of methyl orange (MO), brilliant blue (BB), Rhodamine B (RhB), 4-nitroaniline (4-NA), and 4-nitrophenol (4-NP). Successful preparation of samples was confirmed by UV-Visible spectrophotometry (UV-Visible), Fourier transform infrared (FTIR), and Scanning electron microscopy (SEM) analysis. During the catalytic study, the value of kapp for the reduction of MO in the presence of NaBH4 and catalyst was found 0.488 min-1 while, in the presence of NaBH4 and catalyst alone, were found as 0.9 × 10-4 and 0.8 × 10-5 min-1, respectively which indicates the role of catalyst in making the reaction speedy. The value of kapp for the reduction of BB, RhB, 4-NA, and 4-NP was found as 0.764, 0.475, 0.212 and 0.757 min-1, respectively. Simultaneous reduction of dyes induced a decreased reaction completion time under the same reaction conditions. A slight increase in the value of kapp for the catalytic reduction of MO was also observed when reactions were performed in the presence of ionic media of different salts such as NaCl, KCl, CaCl2, and MnCl2. The rate of reduction of MO was increased with the increase in ionic strength of the medium. However, the presence of SDS (surfactant) in the reaction mixture induced the decreased activity of the catalyst and increased reaction completion time. The same value of kapp for the reduction of MO was observed in the case of freshly prepared and several days old nanocomposite catalyst. These results illustrate the stability and maintained catalytic potential of metal NPs for a prolonged time. Our reported catalyst also showed good potential for the treatment of dyes-polluted textile industry wastewater.

Nanomembranes-Affiliated Water Remediation: Chronology, Properties, Classification, Challenges and Future Prospects

Water contamination has become a global crisis, affecting millions of people worldwide and causing diseases and illnesses, including cholera, typhoid, and hepatitis A. Conventional water remediation methods have several challenges, including their inability to remove emerging contaminants and their high cost and environmental impact. Nanomembranes offer a promising solution to these challenges. Nanomembranes are thin, selectively permeable membranes that can remove contaminants from water based on size, charge, and other properties. They offer several advantages over conventional methods, including their ability to remove evolving pollutants, low functioning price, and reduced ecological influence. However, there are numerous limitations linked with the applications of nanomembranes in water remediation, including fouling and scaling, cost-effectiveness, and potential environmental impact. Researchers are working to reduce the cost of nanomembranes through the development of more cost-effective manufacturing methods and the use of alternative materials such as graphene. Additionally, there are concerns about the release of nanomaterials into the environment during the manufacturing and disposal of the membranes, and further research is needed to understand their potential impact. Despite these challenges, nanomembranes offer a promising solution for the global water crisis and could have a significant impact on public health and the environment. The current article delivers an overview on the exploitation of various engineered nanoscale substances, encompassing the carbonaceous nanomaterials, metallic, metal oxide and metal-organic frameworks, polymeric nano-adsorbents and nanomembranes, for water remediation. The article emphasizes the mechanisms involved in adsorption and nanomembrane filtration. Additionally, the authors aim to deliver an all-inclusive review on the chronology, technical execution, challenges, restrictions, reusability, and future prospects of these nanomaterials.

Polymerization and Applications of Poly(methyl methacrylate)-Graphene Oxide Nanocomposites: A Review

Graphene oxide (GO)-incorporated poly(methyl methacrylate) (PMMA) nanocomposites (PMMA-GO) have demonstrated a wide range of outstanding mechanical, electrical, and physical characteristics. It is of interest to review the synthesis of PMMA-GO nanocomposites and their applications as multifunctional structural materials. The attention of this review is to focus on the radical polymerization techniques, mainly bulk and emulsion polymerization, to prepare PMMA-GO polymeric nanocomposite materials. This review also discusses the effect of solvent polarity on the polymerization process and the types of surfactants (anionic, cationic, nonionic) and initiator used in the polymerization. PMMA-GO nanocomposite synthesis using radical polymerization-based techniques is an active topic of study with several prospects for considerable future improvement and a variety of possible emerging applications. The concentration and dispersity of GO used in the polymerization play critical roles to ensure the functionality and performance of the PMMA-GO nanocomposites.

Efficacy of Electrospun Nanofiber Membranes on Fouling Mitigation: A Review

Despite the advantages of high contaminant removal, operational flexibility, and technical advancements offered, the undesirable fouling property of membranes limits their durability, thus posing restrictions on their usage. An enormous struggle is underway to conquer this major challenge. Most of the earlier reviews include the basic concepts of fouling and antifouling, with respect to particular separation processes such as ultrafiltration, nanofiltration, reverse osmosis and membrane bioreactors, graphene-based membranes, zwitterionic membranes, and so on. As per our knowledge, the importance of nanofiber membranes in challenging the fouling process has not been included in any record to date. Nanofibers with the ability to be embedded in any medium with a high surface to volume ratio play a key role in mitigating the fouling of membranes, and it is important for these studies to be critically analyzed and reported. Our Review hence intends to focus on nanofiber membranes developed with enhanced antifouling and biofouling properties with a brief introduction on fabrication processes and surface and chemical modifications. A summary on surface modifications of preformed nanofibers is given along with different nanofiller combinations used and blend fabrication with efficacy in wastewater treatment and antifouling abilities. In addition, future prospects and advancements are discussed.

Fly Ash-Incorporated Polystyrene Nanofiber Membrane as a Fire-Retardant Material: Valorization of Discarded Materials

Reusing or recycling waste into new useful materials is essential for environmental protection. Herein, we used discarded polystyrene (PS) and fly-ash (FA) particles and a fabricated fly-ash incorporated polystyrene fiber (FA/PS fiber) composite. The electrospinning process produced continuous PS fibers with a good distribution of FA particles. The prepared nanofibers were characterized by state-of-the-art techniques. The performances of the composite nanofibers were tested for fire-retardant applications. We observed that the incorporation of FA particles into the PS fibers led to an improvement in the performance of the composite as compared to the pristine PS fibers. This study showed an important strategy in using waste materials to produce functional nanofibers through an economical procedure. We believe that the strategy presented in this paper can be extended to other waste materials for obtaining nanofiber membranes for various environmental applications.

Electrospun Nanofiber-Based Membranes for Water Treatment

Water purification and water desalination via membrane technology are generally deemed as reliable supplementaries for abundant potable water. Electrospun nanofiber-based membranes (ENMs), benefitting from characteristics such as a higher specific surface area, higher porosity, lower thickness, and possession of attracted broad attention, has allowed it to evolve into a promising candidate rapidly. Here, great attention is placed on the current status of ENMs with two categories according to the roles of electrospun nanofiber layers: (i) nanofiber layer serving as a selective layer, (ii) nanofiber layer serving as supporting substrate. For the nanofiber layer's role as a selective layer, this work presents the structures and properties of conventional ENMs and mixed matrix ENMs. Fabricating parameters and adjusting approaches such as polymer and cosolvent, inorganic and organic incorporation and surface modification are demonstrated in detail. It is crucial to have a matched selective layer for nanofiber layers acting as a supporting layer. The various selective layers fabricated on the nanofiber layer are put forward in this paper. The fabrication approaches include inorganic deposition, polymer coating, and interfacial polymerization. Lastly, future perspectives and the main challenges in the field concerning the use of ENMs for water treatment are discussed. It is expected that the progress of ENMs will promote the prosperity and utilization of various industries such as water treatment, environmental protection, healthcare, and energy storage.

2D Polymer Nanonets: Controllable Constructions and Functional Applications

Two-dimensional (2D) polymer nanonets have demonstrated great potential in various application fields due to their integrated advantages of ultrafine diameter, small pore size, high porosity, excellent interconnectivity, and large specific surface area. Here, a comprehensive overview of the controlled constructions of the polymer nanonets derived from electrospinning/netting, direct electronetting, self-assembly of cellulose nanofibers, and nonsolvent-induced phase separation is provided. Then, the widely researched multifunctional applications of polymer nanonets in filtration, sensor, tissue engineering, and electricity are also given. Finally, the challenges and possible directions for further developing the polymer nanonets are also intensively highlighted. This article is protected by copyright. All rights reserved.

Nanomagnetite- and Nanotitania-Incorporated Polyacrylonitrile Nanofibers for Simultaneous Cd(II)- and As(V)-Ion Removal Applications

This work reports the fabrication of nanomagnetite- and nanotitania-incorporated polyacrylonitrile nanofibers (MTPANs) by an electrospinning process, which has the potential to be used as a membrane material for the selective removal of Cd(II) and As(V) in water. The fiber morphology was characterized by scanning electron microscopy (SEM). The incorporation of nanomagnetite and nanotitania in the composite fiber matrix was confirmed by energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy. The fibers doped with nanomagnetite and nanotitania (MPAN and TPAN fibers, respectively), as well as MTPAN and neat polycrylonitrile (PAN) fibers, after thermally stabilizing at 275 °C in air, were assessed for their comparative As(V)- and Cd(II)-ion removal capacities. The isotherm studies indicated that the highest adsorption of Cd(II) was shown by MTPAN, following the Langmuir model with a q m of 51.5 mg/m2. On the other hand, MPAN showed the highest As(V)adsorption capacity, following the Freundlich model with a K F of 0.49. The mechanism of adsorption of both Cd(II) and As(V) by fibers was found to be electrostatically driven, which was confirmed by correlating the point of zero charges (PZC) exhibited by fibers with the pH of maximum ion adsorptions. The As(V) adsorption on MPAN occurs by an inner-sphere mechanism, whereas Cd(II) adsorption on MTPAN is via both surface complexation and an As(V)-assisted inner-sphere mechanism. Even though the presence of coexistent cations, Ca(II) and Mg(II), has been shown to affect the Cd(II) removal by MTPAN, the MTPAN structure shows >50% removal efficiency even for minute concentrations (0.5 ppm) of Cd(II) in the presence of high common ion concentrations (10 ppm). Therefore, the novel polyacrylonitrile-based nanofiber material has the potential to be used in polymeric filter materials used in water purification to remove As(V) and Cd(II) simultaneously.

Nanotechnological approaches as a promising way for heavy metal mitigation in an aqueous system

The ever-rising environmental problems because of heavy metals emerging from anthropogenic activities pose an impending threat to all biota globally. Considering their persistence and possibility in biomagnification, they are prominent among pollutants. There has been an apparent shift of research interest in advancing cost-effective and competent technologies to mitigate environmental contaminants, specifically heavy metals. In the recent two decades, tailored nanomaterials (NMs), nanoparticles, and NM-based adsorbents have been emerging for removing heavy metal pollution on a sustainable scale, especially the green synthesis of these nanoproducts effective and nonhazardous means. Hence, this review explores the various avenues in nanotechnology, an attempt to gauge nanotechnological approaches to mitigate heavy metals in the aqueous system, especially emphasizing the recent trends and advancements. Inputs on remediating heavy metal in sustainable and environmentally benign aspects recommended future directions to compensate for the voids in this domain have been addressed.

Study on the Preparation and Lipophilic Properties of Polyvinyl Alcohol (PVA) Nanofiber Membranes via Green Electrospinning

As an environmentally friendly water-soluble polymer, polyvinyl alcohol (PVA) has attracted extensive attention because of its non-toxic, degradable, low cost, and good biocompatibility. Electrospinning is a kind of nanotechnology, and the nanofiber membrane prepared by it has the advantages of large surface area-to-volume ratios, nano- to micron-sized fibers, etc. Herein, a simple and facile one-step green electrospinning method was developed to fabricate various environmentally friendly PVA nanofiber membranes. The lipophilic properties of PVA membranes were investigated and optimized according different PVA concentrations. The PVA electrospun fiber prepared from the solution at a concentration of 10 wt% had the highest adsorption capacity for the adsorption of new and waste engine oils, and the waste engine oil adsorption capacity (12.70 g/g) was higher than that of new engine oil (11.67 g/g). It also has a relatively large BET surface area (12.05 m2/g), a pore volume (0.04 cm3/g), and an appropriate pore diameter (13.69 nm) and fiber diameter (174.21 nm). All electrospun PVA membranes showed excellent lipophilic properties due to their oil contact angles of much less than 30°. Therefore, PVA electrospun fibrous membranes have great application potential in the field of purifying engine oil due to the excellent lipophilic properties and oil absorption capacity.

Modified Nanofibrous Filters with Durable Antibacterial Properties

The main aims of the research were to produce efficient nanofibrous filters with long-term antibacterial properties and to confirm the functionality of samples under real filtration conditions. A polyurethane solution was modified by micro- or nanoparticles of copper oxide in order to juxtapose the aggregation tendency of particles depending on their size. Modified solutions were electrospun by the Nanospider technique. The roller spinning electrode with a needle surface and static wire electrode were used for the production of functionalized nanofibers. The antibacterial properties of the modified nanofibrous layers were studied under simulated conditions of water and air filtration. Particular attention was paid to the fixation mechanism of modifiers in the structure of filters. It was determined that the rotating electrode with the needle surface is more efficient for the spinning of composite solutions due to the continuous mixing and the avoidance of particle precipitation at the bottom of the bath with modified polyurethane. Moreover, it was possible to state that microparticles of copper oxide are more appropriate antimicrobial additives due to their weaker aggregation tendency but stronger fixation in the fibrous structure than nanoparticles. From the results, it is possible to conclude that nanofibers with well-studied durable antibacterial properties may be recommended as excellent materials for water and air filtration applications.

Strategies to Improve Nanofibrous Scaffolds for Vascular Tissue Engineering

The biofabrication of biomimetic scaffolds for tissue engineering applications is a field in continuous expansion. Of particular interest, nanofibrous scaffolds can mimic the mechanical and structural properties (e.g., collagen fibers) of the natural extracellular matrix (ECM) and have shown high potential in tissue engineering and regenerative medicine. This review presents a general overview on nanofiber fabrication, with a specific focus on the design and application of electrospun nanofibrous scaffolds for vascular regeneration. The main nanofiber fabrication approaches, including self-assembly, thermally induced phase separation, and electrospinning are described. We also address nanofibrous scaffold design, including nanofiber structuring and surface functionalization, to improve scaffolds' properties. Scaffolds for vascular regeneration with enhanced functional properties, given by providing cells with structural or bioactive cues, are discussed. Finally, current in vivo evaluation strategies of these nanofibrous scaffolds are introduced as the final step, before their potential application in clinical vascular tissue engineering can be further assessed.

Single- and double-walled boron nitride nanotubes: Controlled synthesis and application for water purification

Research interest in boron nitride nanotubes (BNNTs) has increased after the recent success of large-scale BNNT syntheses using high-temperature-pressure laser ablation or high-temperature plasma methods. Nonetheless, there are limits to the application and commercialization of these materials because of the difficulties associated with their fine structural control. Herein, the growth kinetics of BNNTs were systemically studied for this purpose. The growth pressure of the nitrogen feed gas was varied while the growth temperature remained constant, which was confirmed by black body radiation measurements and calculations based on a heat loss model. Changing from the diffusion-limited regime to the supply-limited regime of growth kinetics based on the optimized BNNT synthesis condition afforded the control of the number of BNNT walls. The total amount of BNNTs possessing single and double walls was over 70%, and the BNNT surface area increased to 278.2 m²/g corresponding to small wall numbers and diameters. Taking advantage of the large surface area and high-temperature durability of the material, BNNTs utilized as a recyclable adsorbent for water purification. The efficiency of the BNNTs for capturing methylene blue particles in water was approximately 94%, even after three repetition cycles, showing the potential of the material for application in the filter industry.

One-Step Synthesis of Silver Nanoparticles Embedded Polyurethane Nano-Fiber/Net Structured Membrane as an Effective Antibacterial Medium

A new and straightforward route was proposed to incorporate silver nanoparticles (Ag NPs) into the surface of polyurethane nanofibers (PU NFs). Uniform distribution of in situ formed Ag NPs on the surface of PU NFs was achieved by adding AgNO3 and tannic acid in a PU solution prior to the electrospinning process. The synthesized nanofiber mats were characterized with state-of-the-art techniques and antibacterial performances were tested against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacteria. The cytocompatibility and cell behavior were studied by using fibroblast cells. Following this preparation route, Ag/PU NFs can be obtained with excellent antibacterial performance, thus making them appropriate for various applications such as water filtration, wound dressings, etc.

Drug Delivery Applications of Core-Sheath Nanofibers Prepared by Coaxial Electrospinning: A Review

Electrospinning has emerged as one of the potential techniques for producing nanofibers. The use of electrospun nanofibers in drug delivery has increased rapidly over recent years due to their valuable properties, which include a large surface area, high porosity, small pore size, superior mechanical properties, and ease of surface modification. A drug loaded nanofiber membrane can be prepared via electrospinning using a model drug and polymer solution; however, the release of the drug from the nanofiber membrane in a safe and controlled way is challenging as a result of the initial burst release. Employing a core-sheath design provides a promising solution for controlling the initial burst release. Numerous studies have reported on the preparation of core-sheath nanofibers by coaxial electrospinning for drug delivery applications. This paper summarizes the physical phenomena, the effects of various parameters in coaxial electrospinning, and the usefulness of core-sheath nanofibers in drug delivery. Furthermore, this report also highlights the future challenges involved in utilizing core-sheath nanofibers for drug delivery applications.

Fly-ash-incorporated electrospun zinc oxide nanofibers: Potential material for environmental remediation

Fly ash (FA), a solid waste generated in thermal power plants, is considered an environmental pollutant. Therefore, measures must be taken to dispose of FA in an environmentally friendly manner. In this paper, an electrospinning technique was employed to incorporate FA particles onto zinc oxide nanofibers (ZnO NFs), and the product (FA/ZnO composite) was used for the removal of methylene blue (MB) from the water. Herein, ZnO NFs may serve as effective semiconductor photocatalysts and provide sufficient surface area for FA, while the FA particles serve as an effective adsorbent. The adsorption capacity and photocatalytic efficiency of the as-synthesized nanocomposite fibers were enhanced compared to those of the pristine ZnO NFs, and this result is attributed to the uniform distribution of FA on the surface of the ZnO NFs. The as-synthesized nanocomposite could have great significance in wastewater treatment.

The current application of nanotechnology in food and agriculture

The rapid development of nanotechnology has been facilitating the transformations of traditional food and agriculture sectors, particularly the invention of smart and active packaging, nanosensors, nanopesticides and nanofertilizers. Numerous novel nanomaterials have been developed for improving food quality and safety, crop growth, and monitoring environmental conditions. In this review the most recent trends in nanotechnology are discussed and the most challenging tasks and promising opportunities in the food and agriculture sectors from selected recent studies are addressed. The toxicological fundamentals and risk assessment of nanomaterials in these new food and agriculture products are also discussed. We highlighted the potential application of bio-synthesized and bio-inspired nanomaterial for sustainable development. However, fundamental questions with regard to high performance, low toxic nanomaterials need to be addressed to fuel active development and application of nanotechnology. Regulation and legislation are also paramount to regulating the manufacturing, processing, application, as well as disposal of nanomaterials. Efforts are still needed to strengthen public awareness and acceptance of the novel nano-enabled food and agriculture products. We conclude that nanotechnology offers a plethora of opportunities, by providing a novel and sustainable alternative in the food and agriculture sectors.

Preparation of an electrospun tubular PU/GE nanofiber membrane for high flux oil/water separation

A simple, tubular structure polyurethane/graphene (PU/GE) nanofiber membrane for continuous oil/water separation has been prepared.

Adsorption removal of anionic dyes from aqueous solutions by chitosan nanoparticles deposited on the fibrous carrier

The synthesis, characterization and environmental application of chitosan based material stable in acidic media for adsorption of anionic dyes were investigated. The adsorption material is chitosan nanoparticles immobilized on a fibrous carrier (CPF). The choice of optimal conditions for the preparation of chitosan particles and their immobilization on a chemically activated polyethylene terephthalate (PET) fiber is justified. Immobilized nanoparticles showed high adsorption rates and dye binding capacity (300-1050 mg g^-1) depending on the dye type. Anionic phthalocyanine dyes having different molecular sizes, different nature and number of anionic groups were used as model adsorbates. The experimental isotherm data and a linear correlation coefficients (r_L² > 0.99) have shown that the dyes adsorption on CPF is best predicted by the Langmuir isotherm. The adsorption rate has been found to conform to pseudo-second-order kinetics with a good correlation (R² > 0.99) with intra-particle diffusion as one of the rate determining steps. It has been is established that the sorption rate and the limiting sorption capacity decrease with the increment in the dye molecule size. The process of adsorption of the dyes on the CPF is pH-insensitive in the pH range of 2-8. The adsorption saturated CPF could be effectively regenerated by a simple alkaline washing.

Polymeric nanocomposites for the removal of Acid red 52 dye from aqueous solutions: Synthesis, characterization, kinetic and isotherm studies

Polymeric nanocomposites polyaniline-polyvinylpyrrolidone (PAPV) and polyaniline-polyvinylpyrrolidone-neodymium/zinc oxide (PAPV-NZO) were synthesized for the effective dye removal through adsorption process. Neodymium doped zinc oxide (NZO) with various proportions of neodymium were prepared by chemical co-precipitation method and incorporated into the copolymer matrix via oxidative polymerization technique. NZO nanoparticles were characterized by X-ray diffraction (XRD) and the morphological features, and functional group linkages of the PAPV-NZO were confirmed by scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) analyses. Acid red 52 dye was chosen as a synthetic toxic effluent to study the removal efficiency of the nanocomposites with different parameters viz. time, concentration, adsorbent dosage and pH. The studies were performed under visible light irradiation and the residual dye concentration was analyzed by UV-visible spectrophotometer. PAPV-NZO exhibited greater dye removal rate than PAPV due to the incorporation of NZO that enhanced the conducting nature, stability and surface area of PAPV-NZO. The optimum concentration of the dye and the adsorbent dosage of the PAPV-NZO were determined to be 80 ppm and 50 mg, respectively. At acidic condition of pH 2, the removal capacity of PAPV-NZO was found 99.6%. Kinetic and isotherm models have been studied on the optimum parameters to investigate the nature of the adsorption process. The process followed pseudo second order kinetics and was best suited to the Langmuir model. The maximum dye adsorption capacity of PAPV-NZO was estimated to be 159.36 mg g^-1. From the results, it can be assured that the PAPV-NZO can be effectively used for the removal of dye pollutants in water.

Recent Advances in Nanoporous Membranes for Water Purification

Nanoporous materials exhibit wide applications in the fields of electrocatalysis, nanodevice fabrication, energy, and environmental science, as well as analytical science. In this review, we present a summary of recent studies on nanoporous membranes for water purification application. The types and fabrication strategies of various nanoporous membranes are first introduced, and then the fabricated nanoporous membranes for removing various water pollutants, such as salt, metallic ions, anions, nanoparticles, organic chemicals, and biological substrates, are demonstrated and discussed. This work will be valuable for readers to understand the design and fabrication of various nanoporous membranes, and their potential purification mechanisms towards different water pollutants. In addition, it will be helpful for developing new nanoporous materials for quick, economic, and high-performance water purification.

Inorganic Membranes: Preparation and Application for Water Treatment and Desalination

Inorganic membrane science and technology is an attractive field of membrane separation technology, which has been dominated by polymer membranes. Recently, the inorganic membrane has been undergoing rapid development and innovation. Inorganic membranes have the advantage of resisting harsh chemical cleaning, high temperature and wear resistance, high chemical stability, long lifetime, and autoclavable. All of these outstanding properties made inorganic membranes good candidates to be used for water treatment and desalination applications. This paper is a state of the art review on the synthesis, development, and application of different inorganic membranes for water and wastewater treatment. The inorganic membranes reviewed in this paper include liquid membranes, dynamic membranes, various ceramic membranes, carbon based membranes, silica membranes, and zeolite membranes. A brief description of the different synthesis routes for the development of inorganic membranes for application in water industry is given and each synthesis rout is critically reviewed and compared. Thereafter, the recent studies on different application of inorganic membrane and their properties for water treatment and desalination in literature are critically summarized. It was reported that inorganic membranes despite their high synthesis cost, showed very promising results with high flux, full salt rejection, and very low or no fouling.

R. R, A. S. Tailored design of polyurethane based fouling-tolerant nanofibrous membrane for water treatment

Polyurethane (PU) nanofibers have gained attention due to their good mechanical properties and water resistance.

Nanofabrication of mechano-bactericidal surfaces

The search for alternatives to the standard methods of preventing bacterial adhesion and biofilm formation on biotic and abiotic surfaces alike has led to the use of biomimetics to reinvent through nanofabrication methods, surfaces, whereby the nanostructured topography is directly responsible for bacterial inactivation through physico-mechanical means. Plant leaves, insect wings, and animal skin have been used to inspire the fabrication of synthetic high-aspect-ratio nanopillared surfaces, which can resist bacterial colonisation. The adaptation of bacteria to survive in the presence of antibiotics and their ability to form biofilms on conventional antibacterial surfaces has led to an increase in persistent infections caused by resistant strains of bacteria. This presents a worldwide health epidemic that can only be mitigated through the search for a new generation of biomaterials.

Processable graphene oxide-embedded titanate nanofiber membranes with improved filtration performance

Graphene oxide (GO)-embedded titanate nanofiber (TNF) membranes with improved filtration performance are prepared successfully by a two-step method including electrostatic assembly of GO and TNFs into hybrids and subsequent processing of them into membranes by vacuum filtration. The embedded contents of GO sheets in films and thickness of as-assembled films can be adjusted facilely, endowing such composite films with good processability. Owing to the skilful introduction of GO sheets, the pore and/or channel structures in these hybrid membranes are modified. By treating different dye solutions (Direct Yellow and Direct Red), the filtration properties of these membranes show that the introduction of certain amount of GO sheets efficiently improve the separation performance of the membranes. Interestingly, these GO-embedded TNF membranes also display superior selective separation performance on filtrating the mixture solutions of such two dyes, making these hierarchical membranes more flexible and versatile in water treatment areas.

Antimicrobial filtration with electrospun poly(vinyl alcohol) nanofibers containing benzyl triethylammonium chloride: Immersion, leaching, toxicity, and filtration tests

Antimicrobial electrospun poly(vinyl alcohol) (PVA) nanofibers were synthesized by impregnating benzyl triethylammonium chloride (BTEAC) as an antimicrobial agent into PVA nanofibers. The BTEAC-PVA nanofibers were heat-methanol treated during the preparation for various tests. The BTEAC-PVA nanofibers became more hydrophilic than the PVA nanofibers due to incorporation of BTEAC. Through heat-methanol treatment, thermal property, crystallinity, and water stability of BTEAC-PVA nanofibers were improved considerably. The immersion test shows that heat-methanol treatment has an advantage over heat treatment to maintain BTEAC content in BTEAC-PVA nanofibers. The acute toxicity test demonstrates that the 24-h EC₅₀ and 48-h EC₅₀ values (EC₅₀ = median effective concentration) of BTEAC to Daphnia magna were 113 and 90 mg/L, respectively. The leaching test indicates that the BTEAC concentration leached from BTEAC-PVA nanofibers was far below the concentration affecting the immobilization of D. magna. For antimicrobial filtration tests, the BTEAC-PVA nanofibers were deposited onto glass fiber filter. The antimicrobial filtration test was conducted against bacteria (Escherichia coli, Staphylococcus aureus) and bacteriophages (MS2, PhiX174), demonstrating that the BTEAC-PVA nanofibers could enhance the removal of E. coli and S. aureus considerably but not the removal of MS2 and PhiX174 under dynamic flow conditions.

Investigation of Industrial Polyurethane Foams Modified with Antimicrobial Copper Nanoparticles

Antimicrobial copper nanoparticles (CuNPs) were electrosynthetized and applied to the controlled impregnation of industrial polyurethane foams used as padding in the textile production or as filters for air conditioning systems. CuNP-modified materials were investigated and characterized morphologically and spectroscopically, by means of Transmission Electron Microscopy (TEM), and X-ray Photoelectron Spectroscopy (XPS). The release of copper ions in solution was studied by Electro-Thermal Atomic Absorption Spectroscopy (ETAAS). Finally, the antimicrobial activity of freshly prepared, as well as aged samples—stored for two months—was demonstrated towards different target microorganisms.

Molecular entrapment of volatile organic compounds (VOCs) by electrospun cyclodextrin nanofibers

In this paper, we reported the molecular entrapment performance of hydroxypropyl-beta-cyclodextrin (HPβCD) and hydroxypropyl-gamma-cyclodextrin (HPγCD) electrospun nanofibers (NF) for two common volatile organic compounds (VOCs); aniline and benzene. The encapsulation efficiency of CD samples were investigated depending on the various factors such as; CD form (NF and powder), electrospinning solvent (DMF and water), CD (HPβCD and HPγCD) and VOCs (aniline and benzene) types. BET analysis indicated that, electrospun CD NF have higher surface area compared to their powder form. In addition DMA measurement provided information about the mechanical properties of CD NF. The encapsulation capability of CD NF and CD powder was investigated by (1)H-NMR and HPLC techniques. The observed results suggested that, CD NF can entrap higher amount of VOCs from surroundings compared to their powder forms. Besides, molecular entrapment efficiency of CD NF also depends on CD, solvent and VOCs types. The inclusion complexation between CD and VOCs was determined by using TGA technique, from the higher decomposition temperature of VOCs. Finally, our results were fortified by the modeling studies which indicated the complexation efficiency variations between CD and VOC types. Here, the inclusion complexation ability of CD molecules was combined with very high surface area and versatile features of CD NF. So these findings revealed that, electrospun CD NF can serve as useful filtering material for air filtration purposes due to their molecular entrapment capability of VOCs.

Highly efficient As(v)/Sb(v) removal by magnetic sludge composite: synthesis, characterization, equilibrium, and mechanism studies

Magnetic sludge with the unique flexibility, low thermal conductance and plentiful adsorption sites was fabricated for highly efficient As/Sb removal.

A new functionalized magnetic nanocomposite of poly(methylacrylate) for the efficient removal of anionic dyes from aqueous media

A magnetic nano-adsorbent was synthesized via the radical polymerization of methyl acrylate on modified Fe₃O₄ MNPs, followed by amidation of the methyl ester groups using pentaethylenehexamine, to create active sites for adsorption of anionic dyes.

Preparation, characterization and antifouling properties of polyacrylonitrile/polyurethane blend membranes for water purification

70% PAN and 30% PU blend membrane shows the maximum antifowling characteristics during filtration of turbed surface water.