The Synthesis of Fiber Membranes from High-Impact Polystyrene (HIPS) Waste using Needleless Electrospinning as Air Filtration Media

Multifactorial evaluation of an ultra-fast process for electrospinning of recycled expanded polystyrene to manufacture high-efficiency membranes for nanoparticle air filtration

The increased production of polystyrene waste has led to the need to find efficient ways to dispose of it. One possibility is the use of solid waste to produce filter media by the electrospinning technique. The aim of this work was to develop an ultra-fast electrospinning process applied to recycled polystyrene, with statistical evaluation of the influence of polymeric solution parameters (polymer concentration and percentage of DL-limonene) and process variables (flow rate, voltage, and type of support) on nanoparticle collection efficiency, air permeability, and fiber diameter. An extensive characterization of the materials and evaluation of the morphology of the fibers was also carried out. It was found that recycled expanded polystyrene could be used in electrospinning to produce polymeric membranes. The optimized condition that resulted in the highest nanoparticle collection efficiency was a polymer concentration of 13.5%, percentage of DL-limonene of 50%, voltage of 25 kV, and flow rate of 1.2 mL/h, resulting in values of 99.97 ± 0.01%, 2.6 ± 0.5 × 10-13 m2, 0.19 Pa-1, and 708 ± 176 nm for the collection efficiency of nanoparticles in the range from 6.38 to 232.9 nm, permeability, quality factor, and mean fiber diameter, respectively. All the parameters were found to influence collection efficiency and fiber diameter. The use of DL-limonene, a natural solvent, provided benefits including increased collection efficiency and decreased fiber size. In addition, the electrostatic filtration mechanism was evaluated using the presence of a copper grid as a support for the nanofibers. The findings demonstrated that an electrospinning time of only 5 min was sufficient to obtain filters with high collection efficiencies and low pressure drops, opening perspectives for the application of polystyrene waste in the development of materials with excellent characteristics for application in the area of atmospheric pollution mitigation.

Electrospun Nanofibers from Waste Polyvinyl Chloride Loaded Silver and Titanium Dioxide for Water Treatment Applications

The electrospun nanofiber membrane from polyvinyl chloride (PVC) waste for water treatment applications has been successfully produced. The PVC precursor solution was prepared by dissolving the PVC waste in DMAc solvent, and a centrifuge was used to separate undissolved materials from the precursor solution. Ag and TiO₂ were added to the precursor solution before the electrospinning process. We studied the fabricated PVC membranes using SEM, EDS, XRF, XRD, and FTIR to study the fiber and membrane properties. The SEM images depicted that Ag and TiO₂ addition has changed the morphology and size of fibers. The EDS images and XRF spectra confirmed the presence of Ag and TiO₂ on the nanofiber membrane. The XRD spectra showed the amorphous structure of all membranes. The FTIR result indicated that the solvent completely evaporated throughout the spinning process. The fabricated PVC@Ag/TiO₂ nanofiber membrane showed the photocatalytic degradation of dyes under visible light. The filtration test on the membrane PVC and PVC@Ag/TiO₂ depicted that the presence of Ag and TiO₂ affected the flux and separation factor of the membrane.

Nude and Modified Electrospun Nanofibers, Application to Air Purification

Air transports several pollutants, including particulate matter (PM), which can produce cardiovascular and respiratory diseases. Thus, it is a challenge to control pollutant emissions before releasing them to the environment. Until now, filtration has been the most efficient processes for removing PM. Therefore, the electrospinning procedure has been applied to obtain membranes with a high filtration efficiency and low pressure drop. This review addressed the synthesis of polymers that are used for fabricating high-performance membranes by electrospinning to remove air pollutants. Then, the most influential parameters to produce electrospun membranes are indicated. The main results show that electrospun membranes are an excellent alternative to having air filters due to the versatility of the process, the capacity for controlling the fiber diameter, porosity, high filtration efficiency and low-pressure drop.

Smoke filtration performances of membranes produced from commercial PVA and recycled PET by electrospinning method and ANN modeling

Plastic waste and air pollution are becoming a great concern due to their adverse effect on human health and the environment. There is increasing number of evidence showing that recycling plastic and filtering harmful air pollutants are one of the most effective and promising way to eliminate their hazard on the environment. In this purpose, we developed eco-friendly filtration materials from recycled PET by electrospinning method to be used in air filtration and compared them with conventional PVA membranes. Filtration efficiency of prepared membranes were tested homemade membrane system using cigarette smoke source. Characterization results and smoke filtration performance of recycled PET and PVA membranes before and after smoke filtration were examined. The results demonstrated that the removal efficiencies of PVA-5 wt.%, PVA-10 wt.%, and PVA-15 wt.% were 4.11%, 11.32%, and 12.14%, respectively. A similar trend was also observed in recycled PET-5 wt.%, PET-10 wt.%, and PET-15 wt.% membranes with 4.32%, 10.79%, and 11.68% of filtration efficiency, respectively. Based on this result, using recycled PET can be an alternative way to produce a higher value product compared to traditional polymer membranes used commercially. This result is also supported by the neural network model of this study.

Fly Ash-Incorporated Polystyrene Nanofiber Membrane as a Fire-Retardant Material: Valorization of Discarded Materials

Reusing or recycling waste into new useful materials is essential for environmental protection. Herein, we used discarded polystyrene (PS) and fly-ash (FA) particles and a fabricated fly-ash incorporated polystyrene fiber (FA/PS fiber) composite. The electrospinning process produced continuous PS fibers with a good distribution of FA particles. The prepared nanofibers were characterized by state-of-the-art techniques. The performances of the composite nanofibers were tested for fire-retardant applications. We observed that the incorporation of FA particles into the PS fibers led to an improvement in the performance of the composite as compared to the pristine PS fibers. This study showed an important strategy in using waste materials to produce functional nanofibers through an economical procedure. We believe that the strategy presented in this paper can be extended to other waste materials for obtaining nanofiber membranes for various environmental applications.

Advances in Electrospun Hybrid Nanofibers for Biomedical Applications

Electrospun hybrid nanofibers, based on functional agents immobilized in polymeric matrix, possess a unique combination of collective properties. These are beneficial for a wide range of applications, which include theranostics, filtration, catalysis, and tissue engineering, among others. The combination of functional agents in a nanofiber matrix offer accessibility to multifunctional nanocompartments with significantly improved mechanical, electrical, and chemical properties, along with better biocompatibility and biodegradability. This review summarizes recent work performed for the fabrication, characterization, and optimization of different hybrid nanofibers containing varieties of functional agents, such as laser ablated inorganic nanoparticles (NPs), which include, for instance, gold nanoparticles (Au NPs) and titanium nitride nanoparticles (TiNPs), perovskites, drugs, growth factors, and smart, inorganic polymers. Biocompatible and biodegradable polymers such as chitosan, cellulose, and polycaprolactone are very promising macromolecules as a nanofiber matrix for immobilizing such functional agents. The assimilation of such polymeric matrices with functional agents that possess wide varieties of characteristics require a modified approach towards electrospinning techniques such as coelectrospinning and template spinning. Additional focus within this review is devoted to the state of the art for the implementations of these approaches as viable options for the achievement of multifunctional hybrid nanofibers. Finally, recent advances and challenges, in particular, mass fabrication and prospects of hybrid nanofibers for tissue engineering and biomedical applications have been summarized.

Synthesis of Electrospun PAN/TiO2/Ag Nanofibers Membrane As Potential Air Filtration Media with Photocatalytic Activity

The PAN/TiO2/Ag nanofibers membrane for air filtration media was successfully synthesized with electrospinning method. The morphology, size, and element percentage of the nanofiber were characterized by a scanning electron microscopy-energy dispersive spectroscopy, while X-ray fluorescence and FTIR were used to observe the chemical composition. The water contact angle and UV-vis absorption were measured for physical properties. Performance for air filtration media was measured by pressure drop, efficiency, and quality factor test. TiO2 and Ag have been successfully deposited in nonuniform 570 nm PAN/TiO2/Ag nanofibers. The nanofiber membrane had hydrophilic surface after TiO2 and Ag addition with a water contact angle of 34.58°. UV-vis data showed the shifting of absorbance and band gap energy of nanofibers membrane to visible light from 3.8 to 1.8 eV. The 60 min spun PAN/TiO2/Ag nanofibers membrane had a 96.9% efficiency of PM2.5, comparable to results reported in previous studies. These properties were suitable to be applied on air filtration media with photocatalytic activity for self-cleaning performance.

Electrospun Wrinkled Porous Polyimide Nanofiber-Based Filter via Thermally Induced Phase Separation for Efficient High-Temperature PMs Capture

Benefiting from its superior thermal stability, polyimide (PI) fiber-based composites have attracted wide attention in the field of high-temperature filtration and separation. However, the trade-off between filtration efficiency and pressure drop of traditional PI filters with single morphology and structure still remains challenging. Herein, the electrospun PI high-temperature-resistant air filter was fabricated via thermal-induced phase separation (TIPS), employing polyacrylonitrile (PAN) as a template. The PI nanofibers exhibited special wrinkled porous structure, and the filter possessed a high specific surface area of 304.77 m²/g. The removal of PAN changed the chemical composition of the fiber and induced PI molecules to form complex folds on the surface of the fiber, thus forming the wrinkled porous structure. Additionally, the wrinkled porous PI nanofiber filter displayed a high PM0.3 removal efficiency of 99.99% with a low pressure drop of 43.35 Pa at room temperature, and the filtration efficiency was still over 97% after being used for long time. Moreover, the efficiency of the filter could even reach 95.55% at a high temperature of 280 °C. The excellent filtration performance was attributed to the special wrinkled porous surface, which could limit the Brownian motion of PMs and reinforce the mechanical interception effect to capture the particulate matters (PMs) on the surface of the filter. Therefore, this work provided a novel strategy for the fabrication of filters with special morphology to cope with increasingly serious air pollution in the industrial field.