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

D. Lv, M. Zhu, Z. Jiang, Prof. C. Huang College of Chemical Engineering Jiangsu Provincial Key Lab for the Chemistry and Utilization of Agro-Forest Biomass Jiangsu Key Lab of Biomass-Based Green Fuels and Chemicals Nanjing Forestry University Nanjing 210037, P. R. China E-mail: huangchaobo@njfu.edu.cn Prof. R. Xiong Laboratory of General Biochemistry and Physical Pharmacy Department of Pharmaceutics Ghent University 460 9000 Belgium

Green Electrospun Nanofibers and Their Application in Air Filtration

Multilevel structured polyacrylonitrile/silica nanofibrous membranes for high-performance air filtration

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.

Novel silica nanofibrous (SNF) membranes with ultra-softness and enhanced tensile strength were prepared for the first time via an electrospinning technique with a sol–gel solution containing NaCl. By employing NaCl incorporation, the bonding structure was formed between silica nanofibers, which significantly enhanced the tensile strength of the SNF membranes from 3.2 to 5.5 MPa. Meanwhile, the morphology and mechanical properties of the SNF membranes can be finely controlled by tuning the calcination temperature and varying the NaCl content in the precursor solution. Additionally, the proposed mechanism of the softness of the SNF membranes was discussed by in situ SEM analysis during the bending and recovery process. Furthermore, the as-prepared SNF membranes with ultra-softness of 40 mN and relative high tensile strength of 5.5 MPa exhibit an ultra-low thermal conductivity of 0.0058 W m−1 K−1, even lower than air, which suggested them to be promising candidates for bunker clothing. This novel method also provides a new insight into the design and development of other soft ceramic nanofibrous membranes with high tensile strength for various applications.

Silica nanofibrous membranes with ultra-softness and enhanced tensile strength for thermal insulation

The invention relates to a flexible titanium oxide nanofiber membrane and a preparation method thereof. The preparation method includes firstly dissolving a titanium source and a non-titanium metal salt in solvent, and sequentially adding coupling agent and surfactant to be uniformly mixed and obtain stable precursor solution with interpenetrating three-dimensional network structure molecular chains; then making the precursor solution into a precursor fiber membrane through an electrospinning technique; burning the precursor fiber membrane in the air to obtain the flexible titanium oxide nanofiber membrane. The preparation method is simple and low in cost, the obtained titanium oxide nanofiber membrane is good in flexible and has promising application prospect in the fields such as air purification, water treatment, hydrogen production by photodecomposition, dye-sensitized solar cells, lithium ion batteries and self-cleaning environment protection and energy sources.

Flexible titanium oxide nanofiber membrane and preparation method thereof

The invention relates to a flexible inorganic fiber material and a preparation method thereof. The preparation method of the flexible inorganic fiber material comprises the steps as follows: firstly, at least one metal source is dissolved in a solvent, a coupling agent and a surfactant are added sequentially and uniformly mixed to prepare a homogeneous and stable precursor solution which contains interpenetrating molecular chains adopting a three-dimensional network structure, and then a precursor fiber material is prepared by the precursor solution through a spinning forming process; and the precursor fiber material is calcined in an appropriate atmosphere to obtain the flexible inorganic fiber material. According to the invention, various inorganic fiber materials can be prepared through different spinning processes, the preparation process is simple and high in yield, and the prepared inorganic fiber material has good flexibility and has broad application prospect in the fields of catalysis, energy, electronics, filtration, thermal insulation and the like.

Si Yinsong

Papers

Multilevel structured polyacrylonitrile/silica nanofibrous membranes for high-performance air filtration

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

Silica nanofibrous membranes with ultra-softness and enhanced tensile strength for thermal insulation

Flexible titanium oxide nanofiber membrane and preparation method thereof

Flexible inorganic fiber material and preparation method thereof