ABSTRACT
A polymer made from equal masses of sulfur and canola oil was carbonised at 600 °C for 30 minutes. The resulting material exhibited improved uptake of mercury from water compared to the polymer. The carbonisation could also be done after using the polymer to clean up oil spills, which suprisingly improved mercury uptake to levels rivaling commercial carbons.
ABSTRACT
Airborne aerosol pollutants generated from combustion vehicles exhausts, industrial facilities and microorganisms represent serious health challenges. Although membrane separation has emerged as a technique of choice for airborne contaminants removal, allowing for both size exclusion and surface adsorption. Here, electrospun carbon nanofibre mats were formed from poly(acrylonitrile) by systematic stabilization and carbonization processes to generate flexible and self-standing membranes for air filtration. The great mechanical flexibility of the electrospun carbon-nanofibre membranes was achieved through extreme quenching conditions on a carbon fibre processing line, allowing for complete carbonization in just 3 min. The carbonized nanofibre membranes, with fibre diameters in the range of 218 to 565 nm exhibited modulus of elasticity around 277.5 MPa. The samples exhibited air filtration efficiencies in the range of 97.2 to 99.4% for aerosol particle in the size of 300 nm based on face velocity, higher than benchmark commercial glass fibre (GF) air filters. The carbonized electrospun nanofibre membranes also yielded excellent thermal stability withstanding temperatures up to 450 °C, thus supporting the development of autoclavable and recyclable membranes. This significant and scalable strategy provides opportunities to mass-produce reusable air filters suitable for otherwise complex airborne pollutants, including volatile organic carbons and bio-contaminants, such as viruses.
ABSTRACT
Membranes decorated with biocide materials have shown great potential for air sanitization but can suffer from biocide agent leaching by dissolution in water. In order to tackle the diffusion of biocide metal ions from the fiber matrix, composite nanofiber membranes of poly(vinyl alcohol) (PVA) cross-linked with copper (II) acetate have been successfully engineered via sol-gel electrospinning, providing a stable mean for air bactericidal microfiltration. The novelty lies in the bonding strength and homogeneous distribution of the fiber surface biocide, where biocide metals are incorporated as a sol within a polymer matrix. The electrospinning of bead-free composite nanofibers offered over 99.5% filtration efficiency for PM2.5, with a theoretical permeance above 98%. The PVA/copper nanofiber membranes also showed satisfactory anti-bacterial performance against the gram-negative Escherichia coli within 24 h, making them promising materials for the remediation of airborne bacteria. The mechanical and chemical stability of the engineered nanocomposite electrospun nanofiber webs added to the natural biodegradability of the materials, by offering ideal low-cost sanitary solutions for the application of air disinfection in both indoor and outdoor fitting a circular economy strategy where advanced materials are redesigned to be sustainable.
ABSTRACT
The development of fibrous air filters exhibiting high air filtration efficiency, low energy consumption, and self-cleaning properties is a critical challenge to generate the next generation of resilient air filtration systems. Nano-fibrous mats typically exhibit higher particle capture efficiency but may also lead to higher airflow resistance compared to macro-fibrous materials due to their tighter structure. In this paper, novel catalytic membranes mats were fabricated through a one-pot synthesis from ammonium tetrathiomolybdate (ATTM) doped poly(acrylonitrile) (PAN) nanofibers for sub-micron diameter aerosol particle removal. The presence of ATTM as a dopant in conjunction with a PAN polymeric matrix was found to not only enhance the air filtration performance by increasing aerosol particle removal down to 300â¯nm, but also increase the photocatalytic properties of the PAN material. The enhanced separation properties compared to bare polymeric PAN nanofibrous membranes were attributed to surface nanotexturation of the fibers, leading to protrusions and pores across the nano-fiber structures, thus leading to more permeable and lightweight membranes with higher particle capture capacities. The samples were benchmarked against commercial glass fiber air filters and found to offer higher filtration efficiency, lower pressure drop, and higher quality factor than the commercial filters. Specifically, the quality factors of the catalytic nano-fiber membranes were found to be up to four times higher than that of the benchmarked commercial air filters for PM2.5 particles, while two times higher for 300â¯nm sized contaminants. The presence of the ATTM across the PAN matrix was also found to enhance the photocatalytic activity of the membranes by up to 130% compared to the bare PAN reference nanofibers. This novel strategy opens avenues to engineering advanced multifunctional catalytic membranes, to capture toxic particulate matter from air while offering self-cleaning properties when exposed to sunlight.
ABSTRACT
Electrospun nanofibrous membranes were engineered for aerosol particle removal by controlling the fiber density and alignment across electrospun mats. Electrospun nanofiber membranes were deposited on both, rotatory drum and stationary collectors, to investigate the effect of fiber alignment on filtration performance. Poly(acrylonitrile)/dimethyl formamide (PAN/DMF) solutions were used to produce membranes for applications in air purification. The air filtration performance of as-produced and hot-compacted membranes were systematically evaluated with regard to penetration, pressure drop, and quality factor when subjected to potassium chloride (KCl) aerosol particles in the size-range of 300nm to 12µm. The membranes offered air filtration efficiencies in the range of 77.7% to 99.616% and quality factors between 0.0026 and 0.0204 (1/Pa). The samples were benchmarked against commercial filters and were found to exhibit similar quality factors but higher air filtration efficiencies. These results were correlated to differences in pore morphologies and fiber orientation distributions generated from the different processing techniques, which revealed that the alteration of the fiber density is an effective method for enhancing air filtration performance.
