Electrospun ZnSnO3/ZnO Composite Nanofibers and Its Air-Sensitive Properties

In this work, a novel heterojunction based on ZnSnO3/ZnO nanofibers was prepared using electrospinning method. The crystal, structural and surface compositional properties of sample based on ZnSnO3 and ZnSnO3/ZnO composite nanofibers were investigated by X-ray diffractometer (XRD), Scanning electron microscope (SEM), X-ray photoelectron spectrometer (XPS) and Brunauer-Emmett-Teller (BET). Compared to pure ZnSnO3 nanofibers, the ZnSnO3/ZnO heterostructure nanofibers display high sensitivity and selectivity response with fast response towards ethanol gas at low operational temperature. The sensitivity response of sensor based on ZnSnO3/ZnO composite nanofibers were 19.6 towards 50 ppm ethanol gas at 225°C, which was about 1.5 times superior than that of pure ZnSnO3 nanofibers, which can be owed mainly to the presence of oxygen vacancies and the synergistic effect between ZnSnO3 and ZnO.

Synthesis of CuO by Electrospinning Method for Sensing of Hydrogen and Carbon Monoxide Gases

The pure CuO nanofibers were synthesized via the electrospinning method successfully. The calcinated CuO nanofibers were investigated for sensing hydrogen and carbon monoxide gases. Structural properties of the synthesized calcinated nanofibers were studied using Fourier –transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDX), and particle morphology by scanning electron microscopy (SEM). SEM images confirmed string-like structures, nanofibers. The sensor based on the calcinated CuO nanofibers exhibited excellent gas sensing performance at the low operating temperature of 175 °C and the fast response and recovery characteristics at a low concentration. Moreover, good stability, prominent reproducibility, and excellent selectivity are also observed based on the calcinated nanofibers. These results demonstrate the potential application of calcinated CuO nanofibers for sensing hydrogen (10–200 ppm) and carbon monoxide (400–700 ppm) gases.

Polyacrylonitrile Nanofibers Containing Viroblock as Promising Material for Protective Clothing

Antimicrobial viroblock/polyacrylonitrile nanofiber webs fabricated using the electrospinning method were assessed in terms of the antimicrobial activity against infectious agents as a potential material used in mask production. Viroblock (VB) is an amalgam of lipid vesicle and silver. Lipid vesicle depletes the virus outer membrane, which contains cholesterol, while silver ions penetrate the virus, interact with sulfur-bearing moieties, and possess the virus bactericidal property. VB, having anti-coronavirus and anti-influenza properties, was prepared in four different concentrations, 0.5 wt%, 1 wt%, 1.5 wt%, and 2 wt%, in regard to nanofiber weight. The resultant nanofibers were characterized by scanning electron microscope (SEM), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), water contact angle, water content, and thermogravimetric analysis (TGA). Moreover, all nanofibrous samples were evaluated for cell proliferation assay and ATCC antibacterial tests. Based on characterization results and cytotoxicity, the developed composite nanofibers-based webs showed good promise for utilization in anti-viral masks. Particularly, 2 wt% VB/PAN nanofibers have the highest antibacterial properties against negative and positive bacteria along with excellent cell viability.

Infection Prevention Mask Consisting of Nanofiber Filter and Habutae Silk Fabrics

To reduce skin irritation and allergic symptoms caused by long-term mask use, we produced a mask with a filter effect by laminating nanofibers on habutae silk fabric, a specialty of Japan’s Fukui Prefecture, using the electrospinning method. We investigated the filter characteristics of silk fabrics with different weave structures (habutae, flat crepe, and twill). We found that woven fabrics alone could not sufficiently block particles finer than 1 μm, even when the fabric layers were overlapped. Therefore, we had a nanofiber filter layer fabricated on the surface of habutae fabric by the electrospinning method at a weight of 1 g/m2. The nanofibers removed more than 94% of 0.3 μm-particles, which are similar to the size of virus particles. However, the nanofiber layer was so dense that it caused an increase in pressure drop, so we made the nanofiber layer thinner and fabricated the filter on the surface of the habutae fabric at 0.5 g/m2. A three-dimensional mask consisting of two woven fabrics, one with a nanofiber layer on the inside and the other with a normal woven fabric without a nanofiber layer on the outside, was fabricated and tested on 95 subjects. The subjects reported that the nanofiber habutae masks were more comfortable than nonwoven masks. Moreover, the silk woven masks did not cause allergic symptoms such as skin irritation.

Fabrication and Characterization of Nanofibers Membranes using Electrospinning Technology for Oil Removal

Oily wastewater is one of the most challenging streams to deal with especially if the oil exists in emulsified form. In this study, electrospinning method was used to prepare nanofiberous polyvinylidene fluoride (PVDF) membranes and study their performance in oil removal. Graphene particles were embedded in the electrospun PVDF membrane to enhance the efficiency of the membranes. The prepared membranes were characterized using a scanning electron microscopy (SEM) to verify the graphene stabilization on the surface of the membrane homogeneously; while FTIR was used to detect the functional groups on the membrane surface. The membrane wettability was assessed by measuring the contact angle. The PVDF and PVDF / Graphene membranes efficiency was tested in separation of emulsified oil from aqueous solutions. The results showed that PVDF-Graphene nanofiber membrane exhibited better performance than the plain PVDF nanofiber membrane with average water flux of 210 and 180 L.m-2.h-1, respectively. Both membranes showed high oil rejection with more than 98%.

Process Optimization of PVDF Piezoelectric Nanofiber Production via Electrospinning

The aim of this work was to investigate the effect of processing parameters of the electrospinning method on the resulting poly (vinylidene fluoride) (PVDF) fiber diameter. A three factorial Box-Behnken experimental design was employed to study the influence of applied voltage, the capillary-to-collector distance and the applied flow rate on the resulting fiber diameter. We successfully prepared bead-free PVDF nanofibers with fiber diameters ranging from 510-1300 nm. The experimental design analysis did not show significant influence of the studied process parameters under the used boundary conditions on the fiber diameter, thus indicating the robustness of the process.