Surface Modification of Cotton Fabric Using TiO2 Nanoparticles for Self-Cleaning, Oil-Water Separation, Antistain, Anti-Water Absorption, and Antibacterial Properties

Innovative textiles treated with TiO2-AgNPs with succinic acid as a cross-linking agent for medical uses

Silver and titanium-silver nanoparticles have unique properties that make the textile industry progress through the high quality of textiles. Preparation of AgNPs and TiO2-Ag core-shell nanoparticles in different concentrations (0.01% and 0.1% OWF) and applying it to cotton fabrics (Giza 88 and Giza 94) by using succinic acid 5%/SHP as a cross-linking agent. Ultra-violet visible spectroscopy (UV-Vis), X-ray diffraction (XRD), dynamic light scattering (DLS), zeta potential, transmission electron microscopy (TEM), scanning electron microscopy/energy-dispersive X-ray (SEM-EDX) are tools for AgNPs and TiO2-AgNPs characterization and the treated cotton. The resulting AgNPs and TiO2-AgNPs were added to cotton fabrics at different concentrations. The antimicrobial activities, UV protection, self-cleaning, and the treated fabrics' mechanical characteristics were investigated. Silver nanoparticles and titanium dioxide-silver nanoparticles core-shell were prepared to be used in the treatment of cotton fabrics to improve their UV protection properties, self-cleaning, elongation and strength, as well as the antimicrobial activities to use the produced textiles for medical and laboratory uses and to increase protection for medical workers taking into account the spread of infection. The results demonstrated that a suitable distribution of prepared AgNPs supported the spherical form. Additionally, AgNPs and TiO2-AgNPs have both achieved stability, with values of (- 20.8 mV and - 30 mV, respectively). The synthesized nanoparticles spread and penetrated textiles' surfaces with efficiency. The findings demonstrated the superior UV protection value (UPF 50+) and self-cleaning capabilities of AgNPs and TiO2-AgNPs. In the treatment with 0.01% AgNPs and TiO2-AgNPs, the tensile strength dropped, but the mechanical characteristics were enhanced by raising the concentration to 0.1%. The results of this investigation demonstrated that the cotton fabric treated with TiO2-AgNPs exhibited superior general characteristics when compared to the sample treated only with AgNPs.

Silica-Based Superhydrophobic and Superoleophilic Cotton Fabric with Enhanced Self-Cleaning Properties for Oil-Water Separation and Methylene Blue Degradation

Superhydrophobic textiles with multifunctional characteristics are highly desired and have attracted tremendous research attention. This research employs a simple dip-coating method to obtain a fluorine-free silica-based superhydrophobic and superoleophilic cotton fabric. Pristine cotton fabric is coated with SiO2 nanoparticles and octadecylamine. SiO2 nanoparticles are anchored on the cotton fabric to increase surface roughness, and octadecyl amine lowers the surface energy, turning the hydrophilic cotton fabric into superhydrophobic. The designed cotton fabric exhibits a water contact angle of 159° and a sliding angle of 7°. The prepared cotton fabric is characterized by attenuated total reflectance-fourier transform infrared spectroscopy, X-ray diffraction, atomic force microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. In addition, the coated fabric reveals excellent features, including mechanical and chemical stability, superhydrophobicity, superoleophilicity, and the self-cleaning ability. SiO2 nanoparticles and octadecylamine-coated cotton fabric demonstrate exceptional oil-water separation and wastewater remediation performance by degrading the methylene blue solution up to 89% under visible light. The oil-water separation ability is tested against five different oils with more than 90% separation efficiency. This strategy has the advantages of low-cost precursors, a simple and scalable coating method, enhanced superhydrophobicity and superoleophilicity, self-cleaning ability, efficient oil-water separation, and exceptional wastewater remediation performance.

In-situ assessment of the performance of oil-water separation by superhydrophobic coated cotton under extreme conditions

The present study aims to address the issue of oil in water pollution by application of a superhydrophobic cotton fabric. The superhydrophobic cotton fabric with a water contact angle of 158 ± 2°, is developed by a solution immersion technique using zirconium dioxide (ZrO2) nanoparticles and hexadecyltrimethoxysilane. The synthesis parameters such as concentration, curing temperature, and immersion time were optimized using Box-Behnken design method. With mechanical durability, chemical resilience and thermal stability, the coated fabric can separate different oil-water mixtures with an efficiency of 99.9 %. The coated fabric can also be reused for 50 separation cycles in acidic and neutral medium. Besides, droplet dynamic behavior of oil-water mixture has also been studied to ascertain the effect of mixture impact velocities on separation performance. Additionally, coated fabric possesses self-cleaning feature, which makes it viable for muddy oil-water separation. Prepared coated fabric holds tremendous potential for industrial use and oil-water separation in extreme conditions.

A One-Step Approach for a Durable and Highly Hydrophobic Coating for Flax Fabrics for Self-Cleaning Application

Highly hydrophobic flax fabrics with durable properties were prepared using the "dip-coating" method for self-cleaning application. Flax fabrics were coated with a polysiloxane coating via a hydrosilylation reaction with a Karstedt catalyst at room temperature. The coated fabrics displayed highly and durable hydrophobic properties (contact angle and sliding angle of about 145° and 23°, respectively) with good self-cleaning ability for certain pollutants and excellent durability. Moreover, the influence of the coating process on the mechanical properties of fabrics was investigated. A decrease in E modulus and an increase in tensile stress at maximum force and elongation at maximum force has been observed. Furthermore, this influence of the coating process can be easily controlled by adjusting the proportion of curing agent in the treatment solution.

Enhancing the multifunctional properties of cellulose fabrics through in situ hydrothermal deposition of TiO2 nanoparticles at low temperature for antibacterial self-cleaning under UV-Vis illumination

This study aimed to improve the multifunctional properties (including photocatalysis, stability reusability, self-cleaning, antibacterial effects, and thermal radiation shielding) of cellulose fabrics through incorporation of TiO2 nanoparticles. To achieve this, anatase TiO2 nanoparticles were synthesized in situ and deposited onto cotton fabrics through hydrothermal method. The presence of TiO2 nanoparticles in cellulose fabrics greatly enhanced the photocatalytic efficiency and adsorption range and did not damage the fabric fibers. The TiO2-coated cotton exhibited an outstanding photocatalytic efficiency, with dye removal rates of 92.20 % ± 0.015 % and 99.68 % ± 0.002 % under UV-A and visible illumination, respectively. In addition, the material exhibited thermal radiation shielding properties, in which no heat absorption was observed within 60 min at 40 °C-70 °C. To further enhance the hydrophobicity, the TiO2-coated cotton was surface-modified with 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTS). The resulting PFDTS/TiO2-coated cotton was superhydrophobic with a water contact angle of 156.50° ± 0.05° with a sliding angle of 4.33° ± 0.47° and roughness of 67.35 nm. The superhydrophobicity of the PFDTS/TiO2-coated cotton also facilitated self-cleaning through water injection to remove soil impurities. Furthermore, the PFDTS/TiO2-coated cotton exerted antibacterial effects against gram-negative (Escherichia coli) and gram-positive (Staphylococcus aureus) bacteria under UV-A or visible illumination. These nanocomposite fabrics with multifunctional properties have potential for industrial, military, and medical applications.

Sustainable approach to oil recovery from oil spills through superhydrophobic jute fabric

Ecosystems suffer from increased oil exploitation and frequent oil spills, which calls for effective, environment-friendly, and economically viable solutions. To address this, abandoned gunny sacks as the concerned jute fabric were superhydrophobically (water contact angle ∼159°) modified, incorporating titanium dioxide (TiO2) nanoparticles and hexadecyltrimethoxysilane (HDTMS), rendering a facile drop casting procedure. The modified superhydrophobic-superoleophilic jute fabric has been identified as a high-performance filter with superior reusability that can separate oil-water mixtures in challenging environmental conditions (including potent acidic, alkaline, highly saline, aqueous, frigid, and blistering water environments) while maintaining high separation efficiency. In continuation, static conditions indulging a batch and continuous oil separation performance and dynamic conditions stimulating turbulence in the oil-water mixture were proficiently carried out, mimicking real-world circumstances. As a result, the modified jute fabric has the advantages of high separation efficiency, stable recyclable properties, and outstanding durability, highlighting its enormous potential for use in practical applications.

Asphaltene-Derived Graphene Quantum Dots for Controllable Coatings on Glass, Fabrics, and Aerogels

Graphene quantum dots (GQDs) derived from natural asphaltene byproducts can produce controlled hydrophobic or hydrophilic interfaces on glass, fabrics, and aerogels. A set of facile solvent extraction methods were used to isolate and chemically prepare materials with different surface functionalities from a commercially derived asphaltene precursor. The organic-soluble fraction was used to create hydrophobic and water-repellent surfaces on glass and cotton fabrics. The GQD solutions could also penetrate the pores of a silica aerogel, rendering it hydrophobic. Alternatively, by extracting the more polar fraction of the GQDs and oxidizing their surfaces, we also demonstrate strongly hydrophilic coatings. This work shows that naturally abundant GQD-containing materials can produce interfaces with the desired wettability properties through a straightforward tuning of the solvent extraction procedure. Owing to their natural abundance, low toxicity, and strong fluorescence, asphaltene-derived GQDs could thus be applied, in bulk, toward a wide range of tunable surface coatings. This approach, moreover, uses an important large-scale hydrocarbon waste material, thereby offering a sustainable alternative to the disposal of asphaltene wastes.

Stearic Acid and CeO2 Nanoparticles Co-functionalized Cotton Fabric with Enhanced UV-Block, Self-Cleaning, Water-Repellent, and Antibacterial Properties

Superhydrophobic cotton fabrics with multifunctional features are highly desired in domestic and outdoor applications. However, the short coating longevity and hazardous reagents significantly reduce their commercial-scale applications. Herein, we introduce CeO2 nanoparticles and stearic acid (SA) to develop a fluorine-free, durable superhydrophobic cotton fabric that mimics the lotus effect. The pristine cotton fabric is treated with APTES-functionalized CeO2 nanoparticles by immersion followed by a dip and drying treatment with a 2% myristic acid solution. This sequential process creates a stable superhydrophobic cotton fabric (SA/CeO2-cotton fabric) with a water contact angle of 158° and a water sliding angle of 5°. The results are attributed to the combined effect of CeO2 nanoparticles and stearic acid that enhances surface roughness and reduces surface sorption energy. APTES facilitates the durable attachment of CeO2 nanoparticles and stearic acid to the cotton fabric. The modified cotton fabric is characterized by advanced analytical tools, demonstrating enhanced superhydrophobicity, self-cleaning, and antiwater absorption properties. Additionally, it exhibits remarkable UV-blocking (UPF 542) and antibacterial properties. The designed superhydrophobic cotton fabric unveils good mechanical, thermal, and chemical durability. The proposed strategy is simple, green, and economical and can be used commercially for functional fabric preparation.

Design of hydrophobic polyurethane-magnetite iron oxide-titanium dioxide nanocomposites for oil-water separation

Efficacious oil-water separation has become a global challenge owing to regular oil spillage accidents and escalating industrial oily wastewater. In this study, we synthesized titanium dioxide and magnetite iron oxide nanoparticles to use as a precursor for the production of the nanocomposites. Hydrophobic nanocomposites were fabricated using polyurethane, hematite and magnetite iron oxide nanoparticles, and titanium dioxide nanoparticles through a sol-gel process. The formation of the obtained nanocomposites was confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) analyses. In addition, the thermogravimetric and differential thermogravimetric (TGA/DTG) and BET surface area results exhibited enhanced thermal stability of the optimized nanocomposite which displayed mesoporous type materials feature with high porosity. Furthermore, the obtained outcomes demonstrated that the distribution of nanoparticles into a polymer matrix had a significant impact on enhancing superhydrophobicity and the separation efficiency against sunflower oil. Seeing the water contact angle of the nanocomposite-coated filter paper was about 157° compared to 0° for the uncoated filter paper and endowed separation efficiency of almost 90% for 5 consecutive cycles. Thereby, these nanocomposites could be an ideal candidate for self-cleaning surfaces and oil-polluted water purification.

Advanced Polymeric Nanocomposite Membranes for Water and Wastewater Treatment: A Comprehensive Review

Nanomaterials have been extensively used in polymer nanocomposite membranes due to the inclusion of unique features that enhance water and wastewater treatment performance. Compared to the pristine membranes, the incorporation of nanomodifiers not only improves membrane performance (water permeability, salt rejection, contaminant removal, selectivity), but also the intrinsic properties (hydrophilicity, porosity, antifouling properties, antimicrobial properties, mechanical, thermal, and chemical stability) of these membranes. This review focuses on applications of different types of nanomaterials: zero-dimensional (metal/metal oxide nanoparticles), one-dimensional (carbon nanotubes), two-dimensional (graphene and associated structures), and three-dimensional (zeolites and associated frameworks) nanomaterials combined with polymers towards novel polymeric nanocomposites for water and wastewater treatment applications. This review will show that combinations of nanomaterials and polymers impart enhanced features into the pristine membrane; however, the underlying issues associated with the modification processes and environmental impact of these membranes are less obvious. This review also highlights the utility of computational methods toward understanding the structural and functional properties of the membranes. Here, we highlight the fabrication methods, advantages, challenges, environmental impact, and future scope of these advanced polymeric nanocomposite membrane based systems for water and wastewater treatment applications.

Hydroxyapatite-binding Silver/Titanium Dioxide as a Potential Control Compound Against Mosquito Vectors, Aedes aegypti (Diptera: Culicidae) and Anopheles dirus (Diptera: Culicidae)

Controlling mosquitoes is vital for counteracting the rising number of mosquito-borne illnesses. Vector control requires the implementation of various measures; however, current methods lack complete effectiveness, and new control agents or substances are urgently needed. Therefore, this study developed a nonwoven fabric sheet coated with hydroxyapatite-binding silver/titanium dioxide compound (hydroxyapatite-binding silver/titanium dioxide sheet [HATS])and evaluated its effectiveness on all stages of laboratory Aedes aegypti (Linnaeus); Diptera: Culicidae and Anopheles dirus (Peyton & Harrison); Diptera: Culicidae. We reared larvae with HATS and control sheets and assessed their mortality, emergence, and hatching rates. The submersion rates of engorged female mosquitoes in submerged HATS and control sheets were also compared. The HATS strongly affected mosquito development, resulting in high mortality rates (mean ± SE) of 99.66 ± 0.58% (L1-L2) and 91.11 ± 9.20% (L3-L4) for Ae. aegypti and 100% of both stages for An. dirus. In contrast, mosquitoes raised in the control sheet showed relatively high survival rates of 92.33 ± 3.21% (L1-L2) and 95.67 ± 0.58% (L3-L4) for Ae. aegypti and 86.07 ± 3.53% (L1-L2) and 92.01 ± 8.67% (L3-L4) for An. dirus. Submersion of engorged females was found in the HATS oviposition cup, leading to a decreased number of eggs and a low hatching rate compared to that of the control. Overall, HATS may be a useful new control method for Ae. aegypti and An. dirus.

Construction of hydrophobic fire retardant coating on cotton fabric using a layer-by-layer spray coating method

Multifunctional cotton fabric was prepared through a two-step layer-by-layer spray coating method, where the first layer of the coating comprising chitosan and ammonium phytate provided fire retardancy, and the second one with PDMS-ZnO composite imparted hydrophobicity to the fabric. A molecular dynamics (MD) simulation study was carried out to calculate interfacial adhesion of different components of the coating, based on which the sequencing of the coating layers was determined and used to prepare coated samples. The coated fabric demonstrated a significant improvement in fire retardancy through an increase in LOI from 18 % in control to 30 %, a reduction in char length from 30 cm to 7 cm, and a decrease in peak and total heat release rate values by 75 % and 33 %, respectively. The hydrophobicity of coated fabric was tested via water drop test where coated sample maintained a contact angle of 148° for up to 120 s, while the control sample showed 0°.

Recent advances in eco-friendly fabrics with special wettability for oil/water separation

Considering the serious damage to aquatic ecosystems and marine life caused by oil spills and oily wastewater discharge, efficient, environment-friendly and sustainable oil/water separation technology has become an inevitable trend for current development. Herein, fabrics are recognized as eco-friendly materials for water treatment due to their good degradability and low cost. Particularly, fabrics with rough structures and natural hydrophilicity/oleophilicity enable the construction of superwetting surfaces for the selective separation of oil/water mixtures and even complex emulsions. Therefore, superwetting fabrics for efficiently solving oil spills and purifying oily wastewater have received extensive attention. Especially, Janus and smart fabrics are highly anticipated to enable the on-demand and sustainable treatment of oil spills and oily wastewater due to their changeable wettability. Moreover, the fabrication of superwetting fabrics with multifunctional performances for oily wastewater purification can further promote their practical industrial applications, such as photocatalytic, self-cleaning, and self-healing characteristics. However, some potential challenges still exist, which urgently need to be systematically summarized to guide the future development of this research field. In this review, firstly, the fundamental theories of wettability and the separation mechanisms based on special wettability are discussed. Then, superwetting fabrics for efficient oil/water separation are systematically reviewed, such as superhydrophobic/superoleophilic (SHB/SOL), superhydrophilic/superoleophobic (SHL/SOB), SHL/underwater superoleophobic (SHL/UWSOB), and UWSOB/underoil superoleophobic (UWSOB/UOSHB) fabrics. Most importantly, we highlight Janus, smart, and multifunctional fabrics based on their superwetting property. Correspondingly, the advantages and disadvantages of each superwetting fabric are comprehensively analyzed. Besides, super-antiwetting fabrics with superhydrophobic/superoleophobic (SHB/SOB) property are also introduced. Finally, the challenges and future research directions are explained.

Fabrication of Carbon Aerogels Derived from Metal-Organic Frameworks/Carbon Nanotubes/Cotton Composites as an Efficient Sorbent for Sustainable Oil–Water Separation

Due to the continuous occurrence of water pollution problems, practical separation methods for oil–water mixtures have attracted more and more attention. To date, different kinds of materials have been developed with good hydrophobic properties and strong separation ability. Carbon aerogels, as a promising ideal adsorbent for dealing with oil-spill accidents, have received extensive attention. In this work, zeolitic imidazolate frameworks (ZIFs), nanoparticles, and carbon nanotubes (CNTs) in the three-dimensional (3D) interconnected network structure of cotton balls (CBs) were successfully prepared by a simple and scalable process. The as-prepared carbonized CBs with carbonized ZIF-8 and CNTs (CZIF-8/CNTs/CCBs) were characterized. The oil–water separation performance of the composite was also measured. The results show that the ZIF-8 clusters intercalated with abundant CNTs are fully loaded into the porous structure of the CBs after the in situ synthesis process. Additionally, ZIF-8/CNTs/CBs was carbonized in nitrogen, leading to the formation of CZIF-8/CNTs/CCBs. The prepared material possesses excellent hydrophobicity with a water contact angle of 152.7°, showing good absorption capacities Q1 in the range of 48 to 84 times its original weight for oil and organic liquids. In addition, CZIF-8/CNTs/CCBs exhibits good recyclability in the absorption–distillation test. In summary, this study proposes a novel and simple method for the preparation of a superhydrophobic material that could have wide application in the separation of oil–water mixtures.

Hydrophobic cellulose-based and non-woven fabrics coated with mesoporous TiO2 and their virucidal properties under indoor light

Antiviral hydrophobic cellulose-based cotton or non-woven fabrics containing mesoporous TiO₂ particles were developed for potential use in healthcare and in other contaminated environments. Hydrosols made with the sol-gel method using two different amounts of the Ti precursor were applied to cotton and non-woven fabrics and their virucidal effect on Murine Coronavirus (MHV-3) and Human Adenovirus (HAdV-5) was evaluated under indoor light irradiation. The results show 90% reduction of HAdV-5 and up to 99% of MHV-3 in non-woven fabric, and 90% reduction of MHV-3 and no reduction of HAdV-5 in cotton fabric. The antiviral activity was related to the properties of the TiO₂ powders and coatings characterized by BET surface area, DRX, DLS, FTIR, DRS, SEM, TEM and water contact angle. The hydrophobic characteristic of the treated fabrics and the high surface area of the TiO₂ particles favor interaction with the virus, especially MHV-3. These results demonstrate that non-woven fabric and cotton, coated with TiO₂, can be highly effective in preventing contamination with MHV-3 and HAdV-5 viruses, particularly for applications in healthcare indoor environments.

Facile Construction and Fabrication of a Superhydrophobic and Super Oleophilic Stainless Steel Mesh for Separation of Water and Oil

The fluoride-free fabrication of superhydrophobic materials for the separation of oil/water mixtures has received widespread attention because of frequent offshore oil exploration and chemical leakage. In recent years, oil/water separation materials, based on metal meshes, have drawn much attention, with significant advantages in terms of their high mechanical strength, easy availability, and long durability. However, it is still challenging to prepare superhydrophobic metal meshes with high-separation capacity, low costs, and high recyclability for dealing with oil–water separation. In this work, a superhydrophobic and super oleophilic stainless steel mesh (SSM) was successfully prepared by anchoring Fe₂O₃ nanoclusters (Fe₂O₃-NCs) on SSM via the in-situ flame synthesis method and followed by further modification with octadecyltrimethoxysilane (OTS). The as-prepared SSM with Fe₂O₃-NCs and OTS (OTS@Fe₂O₃-NCs@SSM) was confirmed by a field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectrometer (XPS), and X-ray diffractometer (XRD). The oil–water separation capacity of the sample was also measured. The results show that the interlaced and dense Fe₂O₃-NCs, composed of Fe₂O₃ nanoparticles, were uniformly coated on the surface of the SSM after the immerging-burning process. Additionally, a compact self-assembled OTS layer with low surface energy is coated on the surface of Fe₂O₃-NCs@SSM, leading to the formation of OTS@Fe₂O₃-NCs@SSM. The prepared OTS@Fe₂O₃-NCs@SSM shows excellent superhydrophobicity, with a water static contact angle of 151.3°. The separation efficiencies of OTS@Fe₂O₃-NCs@SSM for the mixtures of oil/water are all above 98.5%, except for corn oil/water (97.5%) because of its high viscosity. Moreover, the modified SSM exhibits excellent stability and recyclability. This work provides a facile approach for the preparation of superhydrophobic and super oleophilic metal meshes, which will lead to advancements in their large-scale applications on separating oil/water mixtures.

Cross-Linking of Centrifugally Spun Starch/Polyvinyl Alcohol (ST/PVA) Composite Ultrafine Fibers and Antibacterial Activity Loaded with Ag Nanoparticles

In this research, centrifugally spun ultrafine composite starch/polyvinyl alcohol (ST/PVA) fibers with high water stability were prepared by cross-linking with a mixture of glutaraldehyde and formic acid in the form of vapor phase. The effect of cross-linking temperature combined with time on the water stability, crystal structure, and thermal properties of fibers was investigated to obtain the optimum parameters. On this basis, we further prepared Ag-loaded ST/PVA fibers with different contents of nano silver. The structure and properties of Ag-loaded fibers, which cross-linked under the optimum parameters, were analyzed. As a result, the Ag-loaded fibers exhibited excellent water stability and mechanical properties and possessed inhibition zone diameters of 3 and 2 mm to Escherichia coli and Staphylococcus. aureus, respectively. The antibacterial property of the Ag-loaded ST/PVA fibers provided a new route for developing less costly antibacterial fiber materials in the future.

Cost-effective fabrication, antibacterial application and cell viability studies of modified nonwoven cotton fabric

In the present work, nonwoven cotton fabric was modified for antibacterial applications using low-cost and eco-friendly precursors. The treatment of fabric with alkali leads to the formation of active sites for surface modification, followed by dip coating with silver nanoparticles and chitosan. The surface was chlorinated in the next step to transform amide (N-H) groups in chitosan into N-halamine (N-Cl). The modified and unmodified surfaces of the nonwoven cotton fabric have been characterized by FTIR, SEM, and XRD. The active chlorine loading is measured with iodine/sodium thiosulphate. The antimicrobial activity and cell toxicity assay were carried out with and without modifications of nonwoven cotton fabric. The antimicrobial efficacies of loaded fabric were evaluated against four bacterial species (Micrococcus luteus, Staphylococcus aureus, Enterobacter aerogenes, and E.coli). It was found that modified fabric exhibited superior efficiency against gram-positive and gram-negative bacterial strains as compared to their bulk counterparts upon exposure without affecting strength and integrity of fabric. The overall process is economical for commercial purposes. The modified fabric can be used for antimicrobial, health, and food packaging industries, and in other biomedical applications.

Alkyl Silica Hybrid Nanowire Assembly in Improved Superhydrophobic Membranes for RO Filtration

Alkyl silica membranes and wires were synthesized by a sol-gel method, which has the capacity to control the size of the particles or membranes by controlling the reactions. Trimethoxyoctylsilane (C₈TMOS) was used as a chemical surfactant; poly(vinylpyrrolidone) (PVP) as an emulsifier, dissolved in butanol for emulsion; and tetraethylorthosilicate (TEOS) as a precursor and a source of silica. An assembly of silica wires was fabricated on glass and cotton substrates by the dip-coating technique. Porous membranes and silica wires were observed using scanning electron microscopy (SEM) images. The contact angles of all of the samples were in the range of 140-154° as measured by ImageJ software, which confirmed the hydrophobic nature of the samples. The contact angle was increased by increasing the amount of the surfactant. Phase changes of silica wires and membranes were investigated by thermogravimetric analysis. Chemical bonds of the sample were studied using Fourier transform infrared (FTIR) spectroscopy. The band gap of silica nanowires was measured to be 3.8-3.4 eV using the UV-visible spectrum and decreased as compared to that of bulk silica. These silica-based porous membranes with enhanced transport properties can be used in filtration and separation techniques. This fabricated hybrid silica membrane showed ∼96% salt rejection within a permeation flux of 3.04 L/m² h.

Functionalization of cellulose fibers alongside growth of 2D LDH platelets through urea hydrolysis inspired Taro wettability

Here, Cotton fabric was functionalized via hybrid coating including 2D MgAl LDH (layered double hydroxide) and SA (stearic acid). The urea hydrolysis was employed for construction of vertically aligned LDH on surface of cellulose fibers under hydrothermal condition. The in situ formation mechanism of LDH on cotton surface was nucleation, growth, and interaction with activated cellulose chains. The partial cellulose ionization in the alkaline solution led to nucleophilic behavior towards electron deficient atom. The effect of different ageing, synthesis temperature, and amount of SA were investigated and optimized at 100 °C for 24 h with 0.05 M. The superhydrophobic surface architecture of treated cotton with hierarchical micro/nanostructure was inspired from the Taro leaf structure with continuous contact line presented WCA of 154 ° and CAH of 9 °. The Cotton@LDH@SA exhibited efficient oil/water separation after several washes (>90%) with good stain resistant. Also, the physico-mechanical properties were studied.

Preparation of BiOCl/Bi2WO6 Photocatalyst for Efficient Fixation on Cotton Fabric: Applications in UV Shielding and Self-Cleaning Performances

In this work, a visible-light-driven BiOCl/Bi2WO6 photocatalyst was obtained via a facile hydrothermal method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), ultraviolet/visible light diffuse reflection spectroscopy (UV/Vis), and photocurrent (PC). BiOCl/Bi2WO6 was modified with (3-chloro-2-hydroxypropyl) trimethyl ammonium chloride to obtain the cationized BiOCl/Bi2WO6. Cotton fabric was pretreated with sodium hydroxide (NaOH) and sodium chloroacetate solution to obtain carboxymethylated cotton fabric, which was further reacted with cationized BiOCl/Bi2WO6 to achieve finished cotton fabric. The cotton fabrics were characterized by Fourier-transform infrared spectroscopy (FT-IR), XRD, SEM, and EDS. The photocatalytic activity of the BiOCl/Bi2WO6 photocatalyst and cotton fabrics was assessed by photocatalytic degradation of MB (methylene blue) solution under simulated visible light. The self-cleaning property of cotton fabrics was evaluated by removing MB solution and red-wine stains. Results revealed that the coated cotton fabrics exhibited appreciable photocatalytic and self-cleaning performance. In addition, anti-UV studies showed that the finished cotton fabrics had remarkable UV blocking properties in the UVA and UVB regions. Therefore, the finished cotton fabric with BiOCl/Bi2WO6 can provide a framework for the development of multifunctional textiles.

Colorful and facile in situ nanosilver coating on sisal/cotton interwoven fabrics mediated from European larch heartwood

This study reports on a novel coloration approach for sisal/cotton interwoven fabric via in situ synthesis of European larch (Larix decidua) heartwood-anchored sustainable nanosilver. The heartwood extracts functioned as the reducing and stabilizing agent in reaction systems. The deposited silver nanoparticles (AgNPs) over the fabric surfaces displayed brilliant coloration effects with improved fastness ratings and color strengths (K/S). The successful depositions of nanosilvers were quantified and increasing trends in K/S values with the increase in silver precursor loading were discovered. The concentrations of AgNPs deposited on fabric surfaces were found to be 16 mg/L, 323 mg/L, and 697 mg/L, which were measured through an iCP OES (atomic absorption spectroscopy) test. The K/S values obtained for different loadings of silver precursors (0.5, 1.5, and 2.5 mM (w/v)) are 2.74, 6.76, and 8.96. Morphological studies of the control and AgNP-treated fabrics also displayed a uniform and homogeneous distribution of AgNPs over the fabric surfaces. FTIR (Fourier transform infrared spectroscopy) studies of the sustainably developed materials further confirms the successful bonding between the fabrics and AgNPs. Furthermore, stability against temperature was also noticed as per TGA (thermogravimetric analysis) and DTG (derivative TG) analysis although there was a slight decline from the control sisal/cotton interwoven fabrics observed. Statistically, regression analysis and ANOVA tests were conducted to understand the significance of increased nanosilver loading on sisal/cotton interwoven fabrics. In summary, the perceived results demonstrated successful coloration and functionalization of sisal/cotton interwoven fabrics through green AgNPs, which could indicate a new milestone for industrial production units.

Air superhydrophilic-superoleophobic SiO2-based coatings for recoverable oil/water separation mesh with high flux and mechanical stability

Due to the inherent differences in surface tension between water and oil, it is a challenge to fabricate air superhydrophilic-superoleophobic materials despite their promising potential in the field of oil/water separation. Herein, a facile approach is developed to fabricate air superhydrophilic-superoleophobic SiO₂ coating by combination of controllable modifying SiO₂ nanoparticle surface by both hydrophilic groups (i.e., -OH groups) and oleophobic groups (i.e., fluorinated groups) with constructing porous and hierarchical structures. Hydroxyl-modified SiO₂ nanoparticles (NPs) are synthesized using a base-catalysed procedure in the presence of ammonia or NaOH. Chitosan quaternary ammonium salt (HACC) is introduced to bind SiO₂ by forming a unique hydrogen bond between HACC and -OH, followed by adding pentadecafluorooctanoic acid (PFOA) to complex with HACC to form fluorinated groups. The SiO₂ coatings are fabricated on various substrates (e.g., glass, foam and Cu mesh) by spraying procedure and characterized using SEM, FTIR, XPS, etc. The contact angles of oils (e.g., pump oil, castor oil, corn oil, hexadecane and bean oil) and water on the coatings are over 150° and close to 0°, respectively. By optimization, the representative SiO₂-coated Cu mesh displayed high-efficiency of 99.2% in separating water from mixture of water/pump oil, and high penetration flux of 1.41 × 10⁴ L·m^-2 ·h^-1. Besides, the coating maintains its superhydrophilic-superoleophobic properties even after 110 cycles of sandpaper abrasion or after being immersed in water for 3 h. After 20 cycles of oil/water separation, the coating retains separation efficiency up to 97.93%. This study provides a new and universal protocol to fabricate unique superwetting surfaces with effective oil/water separation performance, long-term durability and outstanding reusability.

Fluorinated Carbon Nanotube Superamphiphobic Coating for High-Efficiency and Long-Lasting Underwater Antibiofouling Surfaces

Biofilm formation on the surface of materials has brought great troubles to various industries. Designing surfaces with long-lasting antibiofouling properties can help restrain primary bacterial and protein attachment and subsequent biofilm formation for a long time, which is also of great significance for industrial applications. In this work, we successfully prepared fluorinated carbon nanotubes through a one-step fluorination method using fluorosilane and fabricated a superamphiphobic coating using a simple spray method. This coating with ultralow surface free energy and stable micro/nano structures achieved highly efficient and long-term underwater antibiofouling properties. Tea, milk, BSA, and bacterial solution can bounce highly on this surface without wetting the surface in air. The long-term existence of the underwater air-bubble layer on the surface of the superamphiphobic coating was observed. Thus, this surface can effectively resist BSA and bacterial attachment (E. coli), and the efficiency, respectively, reaches 97.5 and 98.2%. Even if it is fully soaked in BSA and BS solution for 120 h, the whole surface is still able to repel water, BSA, and BS solution very well. In addition, the coating possessed excellent wear resistance, the CAs of BSA and BS solution just decreased slightly (higher than 158°), and the sliding angles increased slightly (lower than 4°) after 50 tape abrasion cycles. Therefore, this superamphiphobic coating may have promising applications for marine devices, biomedical materials, protective clothing, and chemical shielding.

Facile deposition of biogenic silver nanoparticles on porous alumina discs, an efficient antimicrobial, antibiofilm, and antifouling strategy for functional contact surfaces

Surface modification is an emerging strategy for the design of contact materials. Fabricated alumina discs were functionalized by deposition of biogenic silver nanoparticles. The surfaces were characterized for physico-chemical, antibacterial and antibiofilm properties against microbial pathogens. The surface demonstrated improved hydrophobicity and a surface silver nanoparticle content of 6.4 w%. A reduction of more than 99.9% in CFU mL^-i was observed against the Gram-positive and Gram-negative bacteria tested, with >90% reduction of the fungal isolate. After 4 h, microbial adhesion was reduced by >99.9 and 90% for Escherichia coli and Staphylococcus aureus, respectively. Scanning electron micrographs further revealed a biofilm reduction. Cell viability tests indicated a bioincompatibility higher than 80% with Caco-2 and HaCaT cell lines after 48 h contact. The results suggest that deposition of biogenic silver nanoparticles on the surface of contact materials could be employed as a strategy to prevent biofilm formation.

A facile preparation of superhydrophobic L-CNC-coated meshes for oil-water separation

A superhydrophobic stainless steel mesh (called "mesh" in short) is an ideal device to solve oil pollution accidents by oil-water separation. However, its widespread application is prevented by complicated preparation, weak durability, and particularly poor mechanical strength. It is well known that the used adhesives play a key role in the mechanical strength of superhydrophobic coatings. In this study, polyvinylidene fluoride (PVDF) and polydimethylsiloxanes (PDMSs) were respectively used as adhesives and lignin-nanocellulose crystal (L-CNC) particles as main structure materials to prepare L-CNC coated superhydrophobic meshes. Moreover, the meshes coated with L-CNC/PVDF and L-CNC/PDMS were compared with respect to the properties of wettability, sandpaper abrasion, oil-water separation, etc. The results showed that the L-CNC/PVDF-coated mesh had a higher water contact angle (WCA = 154.2°) than the L-CNC/PDMS-coated one (WCA = 152.6°), but worse abrasion resistance. Both of them showed high-efficiency oil/water separation with collection rates above 94.5% and stable reusable ability as the oil collection rates for toluene was still above 93.8% after reusing thirty times, meanwhile showing good heat, UV, acid and alkaline resistance properties.

Multifunctional superhydrophobic surfaces

Surface wetting has a significant influence on the performance and applications of the materials. The superhydrophobic surfaces have water repellency due to low surface energy chemistry and micro/nanostructure roughness. The amazing applications of superhydrophobic surfaces (SHSs) lead to increase attention to superhydrophobicity in recent decades. The SHSs have been fabricated through chemical and physical methods. The further properties of SHSs as functions such as self-healing, anti-bacterial, anti-fouling, and stimuli-responsiveness are considered as the functions of the SHSs. The Multifunctional SHSs (MSHSs) that contained superhydrophobicity and at least two other properties as the next generation of the SHSs are swiftly developed in recent years. The multiple applications of the MSHSs are originated from specific morphology and functional groups of the MSHSs. The functions (properties) of the MSHSs are categorized into three groups including self-cleaning properties, restrictive properties, and smart properties. Designing and keeping surface structure plays a significant role in fabricating durable MSHSs. However, there is a big challenge to design and also scale up mechanochemical durable MSHSs. Based on state-of-the-art investigations, establishing a self-healing function can improve the durability of SHSs. The durable self-healing MSHSs can enhance the performance of the other functions and lifespan of the surface. In this review, all surface structures and superhydrophobic agents in MSHSs are investigated. The perspective of the MSHSs determined the next generation of the MSHSs have several significant parameters including durability, stability, more functions, more responsiveness, and environmentally friendly features for fabricating the large-scale MSHSs and enhancing their applications.

Multi-Hollow Surface Dielectric Barrier Discharge for Bacterial Biofilm Decontamination

The plasma-activated gas is capable of decontaminating surfaces of different materials in remote distances. The effect of plasma-activated water vapor on Staphylococcus epidermidis, methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli biofilm contamination was investigated on the polypropylene nonwoven textile surface. The robust and technically simple multi-hollow surface dielectric barrier discharge was used as a low-temperature atmospheric plasma source to activate the water-based medium. The germicidal efficiency of short and long-time exposure to plasma-activated water vapor was evaluated by standard microbiological cultivation and fluorescence analysis using a fluorescence multiwell plate reader. The test was repeated in different distances of the contaminated polypropylene nonwoven sample from the surface of the plasma source. The detection of reactive species in plasma-activated gas flow and condensed activated vapor, and thermal and electrical properties of the used plasma source, were measured. The bacterial biofilm decontamination efficiency increased with the exposure time and the plasma source power input. The log reduction of viable biofilm units decreased with the increasing distance from the dielectric surface.

Reversible Wettability between Underwater Superoleophobicity and Superhydrophobicity of Stainless Steel Mesh for Efficient Oil-Water Separation

Design and fabrication of smart materials with reversible wettability for oil-water separation have attracted worldwide attention due to the increasingly serious water pollution problem. In this study, a rough oxide coating with micro/nanoscale structures is developed on the 304 stainless steel mesh (SSM) by laser ablation. The smart surface with ethanol immersion and natural drying treatments shows the wetting conversion between underwater superoleophobicity and superhydrophobicity. Based on the wettability transition behavior, both light and heavy oil-water mixtures can be separated with the high separation efficiency. Moreover, after being exposed to various corrosive solutions and high temperatures, the smart surface still shows prominent environmental stability. Switchable surface with excellent properties should be an optimal choice to solve the environmental conditions that need to be addressed urgently.

Cellulose acetate/fiber paper composite membrane for separation of an oil-in-water emulsion

The cellulose composite membrane combines the advantages of cellulose acetate and cellulose filter paper with good antifouling performance and excellent mechanical properties.

Development of a microbial coating for cellulosic surface using aloe vera and silane

The highly contagious nature of SARS-CoV-2 (COVID-19) virus has created a havoc effect all over the world in a very short period. The most effective method for precaution of this virus as suggested by WHO is use of PPEs (triple layered face mask, body suits) and social distancing. However, the frontline doctors and medical staff have high risk of exposure to the virus during treatments and removal and discarding of the PPEs. Also the PPEs are of the onetime use and wearing these PPEs in hot and humid seasons is very uncomfortable. A possible solution of this problem is if clothes are anti-bacterial and anti-viral in nature, one single-layered will be sufficient and the spread of virus will also be minimized. Considering this, we have designed a facile and durable anti-wash antimicrobial coating on cloth by aloe vera and hexadecyltrimethoxysilane (HDTMS). In lab scale study, present coating shows good chemical and thermal stability making it reusable multiple times even after repeated washing. The coated cloth reveals the excellent anti-dirt and stain resistance properties leading to complete non-adherence of dirt and stain (e.g. Color, food, ink) on it. Anti-bacterial and anti-fungi properties of the coated cloth were confirmed by doing E. coli (bacteria) and A. Niger (fungus) culture studies, respectively. This coating is imbibed with well-known anti-viral agent aloe vera which inhibits the attachment of the virus on the surface. The water-repellent nature of the coating combined with the use anti-viral agent, aloe vera makes it a potential anti-COVID-19 coating.