Inspired by the surface geometry and composition of the lotus leaf with its self-cleaning behavior, in this work, a TiO2@fabric composite was prepared via a facile strategy for preparing marigold flower-like hierarchical TiO2 particles through a one-pot hydrothermal reaction on a cotton fabric surface. In addition, a robust superhydrophobic TiO2@fabric was further constructed by fluoroalkylsilane modification as a versatile platform for UV shielding, self-cleaning and oil–water separation. The results showed TiO2 particles were uniformly distributed on the fibre surface with a high coating density. In comparison with hydrophobic cotton fabric, the TiO2@fabric exhibited a high superhydrophobic activity with a contact angle of ∼160° and a sliding angle lower than 10°. The robust superhydrophobic fabric had high stability against repeated abrasion without an apparent reduction in contact angle. The as-prepared composite TiO2@fabric demonstrated good anti-UV ability. Moreover, the composite fabric demonstrated highly efficient oil–water separation due to its extreme wettability contrast (superhydrophobicity/superoleophilicity). We expect that this facile process can be readily and widely adopted for the design of multifunctional fabrics for excellent anti-UV, effective self-cleaning, efficient oil–water separation, and microfluidic management applications.

Robust superhydrophobic TiO2@fabrics for UV shielding, self-cleaning and oil–water separation

In modern society, traffic and transportation and the manufacturing industry and construction industries continuously release large amounts of dust and particles into the atmosphere, which can cause heavy air pollution, leading to health hazards. The haze disaster, a serious problem in developing countries such as China and India, has become one of the main issues of global environmental pollution in recent decades. Many air filtration technologies have been developed. Air filtration using electrospun fibers that intercept fine particles/volatile organic gases/bacterium is a relatively new, but highly promising, technique. Due to their interconnected nanoscale pore structures, highly specific surface areas, fine diameters, and porous structure as well as their ability to incorporate active chemistry on a nanoscale surface, electrospun fibers are becoming a promising versatile platform for air filtration. In this review, following a short introduction concerning the need for air filtration and filtration theory and mechanism, electrospun nanofibers membranes for air filtration have been highlighted, including the preparation (electrospinning process) and the parameters relevant to filtration efficacy. Additionally, various types (function) of the electrospun air filtration membranes have been classified in detail. Furthermore, their potential in the filtration of fine particles and chemical pollutants has been discussed. Finally, the challenges of their practical application and the future prospects have been summarized. Given that some advanced electrospun air filtration nanofibrous membranes exist for treating different contaminants from various types of polluted atmosphere, it is believed that they should make a significant contribution in protection against air pollution.

Electrospun Nanofibers Membranes for Effective Air Filtration

TiO2 nanocomposite based polymeric membranes: A review on performance improvement for various applications in chemical engineering processes

Ambient particulate matter pollution has posed serious threats to global environment and public health. However, highly efficient filtration of submicron particles, the so-named "secondary pollution" caused by, e.g., bacterial growth in filters and the use of nondegradable filter materials, remains a serious challenge. In this study, poly(vinyl alcohol) (PVA) and konjac glucomannan (KGM)-based nanofiber membranes, loaded with ZnO nanoparticles, were prepared through green electrospinning and ecofriendly thermal cross-linking. Thus obtained fibrous membranes not only show highly efficient air-filtration performance but also show superior photocatalytic activity and antibacterial activity. The filtration efficiency of the ZnO@PVA/KGM membranes for ultrafine particles (300 nm) was higher than 99.99%, being superior to that of commercial HEPA filters. By virtue of the high photocatalytic activity, methyl orange was efficiently decolorized with a removal efficiency of more than 98% at an initial concentration of 20 mg L-1 under 120 min of solar irradiation. A multifunctional membrane with high removal efficiency, low flow resistance, superior photocatalytic activity, and superior antibacterial activity was successfully achieved. It is conceivable that the combination of a biodegradable polymer and an active metal particle would form an unprecedented photocatalytic system, which will be quite promising for environmental remediation such as air filtration and water treatment.

https://biblio.ugent.be/publication/8614522/file/8614539.pdf

Ecofriendly Electrospun Membranes Loaded with Visible-Light-Responding Nanoparticles for Multifunctional Usages: Highly Efficient Air Filtration, Dye Scavenging, and Bactericidal Activity

Electrospun polyimide nanofibers and their applications

Hierarchically structured, superhydrophobic filter medium exhibiting robust filtration performance to airborne particulate were prepared by a facile deposition of electrospun polysulfone/titania nanoparticles (PSU/TiO2 NPs) on a conventional nonwoven substrate. The air permeability, tensile strength and abrasion resistance of pristine PSU fibrous membranes could be finely controlled by regulating the solvent composition and number ratios of jets. By employing the TiO2 NPs incorporation, the pristine PSU fibers were endowed with promising superhydrophobicity with a water contact angle of up to 152°. The quantitative hierarchical roughness analysis using N2 adsorption method has confirmed the major contribution of TiO2 NPs on enhancing the porous structure and surface fractal features with irregular rough structure. Filtration performance studies have revealed that the filtration efficiency and pressure drop of resultant hybrid membranes could be manipulated by tuning the surface composition as well as the hierarchical structures. Furthermore, the as-prepared PSU/TiO2-5 membrane exhibited improved filtration efficiency (99.997%) and pressure drop (45.3 Pa) compared with pristine PSU membrane, which would make them a promising media for fine particle filtration, and a new insight was also provided into the design and development of high performance filter medium based on hierarchical structured fibers.

Hierarchically structured polysulfone/titania fibrous membranes with enhanced air filtration performance.

Creating a sensitive and selective method that can provide simple, practical and high-throughput determination of levels of Hg2+ ions in water has proved extremely challenging. This work responds to these challenges by designing, fabricating and evaluating a polyaniline (PANI) based immobilized sensor optimized to exhibit a colorimetric response to trace amount of Hg2+ ions. The sensor design is realized using a leucoemeraldine based PANI as probe, which has a specific interaction with Hg2+ and results in both “off–on” and “color-change” signals. Hierarchical structured nanofibrous sensing membranes within well immobilized probes are fabricated by a bottom-up blending electrospinning nanofabrication method. This sensor shows a vivid colorimetric response specifically to Hg2+ ions (white–yellow/green–green–blue) over other possible interfering metal cations and achieves a low detection limit of 5 nM observed by the naked eye. Additionally, the sensing responses are visualized quantitatively by employing a colorimetric framework that translates measured spectra into numeric color values directly related to color perception. Furthermore, the as-prepared sensors exhibited good reversibility after extended regeneration cycles, which suggests a promising analytical method as an economical alternative to traditional Hg2+ sensors and also provides a new insight into the design and development of a novel colorimetric sensing system based on PANI immobilized materials.

Optimized colorimetric sensor strip for mercury(II) assay using hierarchical nanostructured conjugated polymers

Model derivation and validation for 2D polymeric nanonets: Origin, evolution, and regulation

Creating a facile and efficient method that can provide large-scale, highly aligned, and high strength nanofibers has proved extremely challenging. This work responds to these challenges by designing and evaluating poly(m-phenylene isophthalamide) (PMIA) nanofibrous materials with robust mechanical strength, which can be fabricated on a large scale via a facile combination of relative humidity (RH)-regulated electrospinning and multi-level aggregate reconstructing. The morphology and structure of the PMIA membranes can be finely controlled by regulating the solution concentration and RH during spinning, and a possible RH-regulated alignment mechanism was proposed. Additionally, PMIA nanofibrous aggregates of yarns and subsequent plaits were built up by multi-level reconstructing. During the first-level reconstructing based on twisting, the structure and mechanical properties of the yarns can be facilely optimized by tuning the twist level, and the PMIA yarns with 3000 TPM possess robust tensile strength of 262 MPa. The second-level reconstructing based on yarns braiding endows the corresponding nano-plaits with the highest tensile strength of 330 MPa. This novel method provides a new insight into the design and development of highly aligned nanomaterials for various applications.

Large-scale fabrication of highly aligned poly( m -phenylene isophthalamide) nanofibers with robust mechanical strength

The invention relates to a preparation method for a multi-component net-shaped nanofiber membrane. The preparation method includes the detailed steps that step1, mixing and beating are performed on meta-position aramid fibers, halogen salt and organic solvent by the mass ratio of 1:0.004-0.4:2.996-18.6, and a meta-position aramid fiber solution is prepared through mixing; step2, functionality high-molecular polymers and the solvent are mixed by the mass ratio of 1:5.4-98.99, then nano-particles are added, and heating and mixing are performed to prepare a functionality high-molecular solution, wherein the mass fraction of the nano-particles in the solution is 0.01-5%; step3, the meta-position aramid fiber solution obtained in the step1 and the functionality high-molecular solution obtained in the step2 are mixed by the mass ratio of 1:0.05-0.5 in a dripping mode, and then ultrasonic treatment is performed to obtain a spinning solution; step4, under the conditions of 20 DEG C-30 DEG C indoor temperature and 20-70% relative humidity, the spinning solution is used for electrostatic spinning, and finally the multi-component net-shaped nanofiber membrane with a 5nm-20nm net-shaped nanofiber diameter and reaches over 95% in net-shaped structure coverage rate is obtained. The preparation technology is simple and low in cost, tensile strength of material reaches 100MPa-2000MPa, and the functionality advantage is remarkable.

Kun Chen

Papers

Hierarchically structured polysulfone/titania fibrous membranes with enhanced air filtration performance.

Optimized colorimetric sensor strip for mercury(II) assay using hierarchical nanostructured conjugated polymers

Model derivation and validation for 2D polymeric nanonets: Origin, evolution, and regulation

Large-scale fabrication of highly aligned poly( m -phenylene isophthalamide) nanofibers with robust mechanical strength

Preparation method for multi-component net-shaped nanofiber membrane