Papers by Keyword: Nanofiber

Abstract: From food to environmental applications, the encapsulation of bio-objects in nanofibers is widely used. In particular, for improved and sustainable performance of bioremediation, the system requires the development of cost-effective nanomaterials that containing living microorganisms for textile wastewater treatment is required. Here, bacteria-encapsulated polyethylene oxide (PEO) nanofibers (Nfs) were prepared by electrospinning. According to the Scanning Electron Microscope (SEM) images, PEO-Nfs show bead-free morphology and homogeneous distribution, while random expansions are observed in the nanofibers after bacterial encapsulation. While the number of live bacteria in the polymer before electrospinning was 10¹⁰ CFU/mL, the number of live bacteria-encapsulated after spinning was 10⁸ CFU/mL. This proves that nanofibers carry a very high number of bacteria after electrospinning which is supported by Fluorescence microscope images. Furthermore, an ATR-FTIR study confirmed the molecular interactions between PEO and bacteria in the nanofibers. The removal efficiency of PEO_bacteria-Nfs was 26.6 ± 0.3% at 5 ppm and 9 ± 0.1% at 20 ppm dye concentration. Under storage conditions of +4 °C, the bacteria-encapsulated in PEO-Nfs show cell viability for more than 60 days. In order to extend the research on bacteria-encapsulated polymer Nfs, we explored the possibility of extending the life of bacteria in electrospun Nfs by cross-linking approaches using non-toxic calcium ions. The composite Nf mats were therefore reused for up to 4 repeated cycles.

Abstract: In recent years, materials with both waterproof and breathability have also been marked with the eye-catching slogan of "waterproof-breathable" on the commodity such as personal protective equipment or sportswear. Regarding the application of nanofiber non-woven fabric as waterproof and breathable materials for functional textile, although there are previous reports regarding conventional micro-fabrics, the relationship between the compositions of the fiber aggregate, waterproof and breathable properties remain unclear regarding nanofabrics. Therefore, this study shows investigation of influence of fiber diameter, bulk density and thickness of the woven nanofabric on waterproof-breathable ability with experiment and CFD (computational fluid dynamics) model. As a result, the average fiber diameters, bulk densities, and thicknesses to achieve waterproofness and air permeability were numerically obtained respectively. From the results, it can be found that, these parameters can be used as a reference for manufacturing high-performance waterproof permeable materials with both high waterproofness and high air permeability.

Abstract: In a previous study, soil substitutes, such as polyester fiber and rockwool medium, were used as solid medium for plant cultivation. However, these media are not biodegradable and aggravate environmental pollution. Furthermore, as they disintegrate into microplastics, they can damage and destroy ecosystems. Therefore, replacements with biodegradable materials are necessary. To that end, an improved melt-blowing method has been developed previously that facilitates a stable manufacturing process for the mass production of semi-microfiber nonwoven fabrics of lipophilic polypropylene. In addition, high oil adsorption was achieved based on the trial-produced nanofibers. In the present report, we focused on the hydrophilic and biodegradable features of polylactic acid (PLA) produced by the improved melt-blowing method and examined its application as a fiber-aggregate-based culture medium. Several plants were cultivated using trial-produced PLA nanofibers, and the influence of different fiber diameters and bulk densities on moisture content and matric potential was also investigated. The results show that PLA fibers can be used to successfully cultivate plants.

Abstract: One of the traditional clean-energy harvesting solutions is through transducing different mechanical stresses into electrical energy. Generally, the acoustic-to-electric energy conversion of still needs more research investigations to be applicable. In our work, we are targeting to fabricate elastic nanofibers mats via electrospinning method to be used for acoustic harvesting/sensing applications. The targeted mechanically-elastic nanocomposite includes polyvinylidene fluoride (PVDF), which is one of the most famous organic piezo materials, with blended thermoplastic polyurethane (TPU). As TPU supports higher mechanical allowed breaking strain. Then, the synthesized mat has been used as a target for mechanical stresses with resulted piezosensitivity of 667±220 mV/N. Then, the nanofibers mat has been targeted against acoustic signals with different amplitude and frequencies. It has been observed that the synthesized mats can detect or harvest acoustic signals and convert them into output electric voltage. According to acoustic sound input, the synthesized electrospun nanofibers detect output voltage up to 300 mV with increased input audible amplitude and frequency up to 6 kHz, where the harvested voltage has a saturation behaviour beyond that audible frequency. That can open the track for using such nanocomposites in energy harvesting applications from disposable facemasks, filters, and music/noise in different opened and closed areas.

Abstract: Water contamination by heavy metals is one of the most serious environmental problems and harms human life. Numerous nanotechnologies have been utilized to overcome this problem so far. Herein, we introduce lignin/polyacrylonitrile (PAN) composite nanofibers prepared via electrospinning for the removal of lead from aqueous solution. The effects of blend ratios between lignin and PAN concentration (LP) were investigated. The performance of adsorption process depends on the following parameters including contact time of adsorbent and adsorbate (equilibrium times: after 16 h. for 10 mg/L of lead concentration), types of nanofibers (LP55 at 1 g/L), and the percentage of lead removal was 72.5 % within 24 hours by LP55 nanofibers. The highest correlation coefficients were performed for the pseudo-second order kinetic model both LP55 and PAN nanofibers. This study demonstrates that the potential of the biomass-derived material with nanotechnology for environmental remediation.

Abstract: The introduction of antimicrobial nanoparticles into nanofiber coatings is significant for enhancing microbial corrosion protection. Here, electrospun polysulfone nanofiber (PSU-Nf) and PSU-Nf functionalized with biogenic silver nanoparticles (AgNPs) coatings (PSU-Nf-AgNPs) used for Cobalt (Co) corrosion resistance in a marine environment containing Aeromonas eucrenophila (A. eucrenophila). We utilized the barrier function of the PSU-Nf and the bacterial inhibition property of the AgNPs that are synthesized using bacteria. The thickness of nanofiber coatings was 233.11 ± 33.64 µm analyzed by optical microscope and beadless morphology of nanofibers was observed using scanning electron microscope (SEM). The corrosion behavior of Co coated with PSU-Nf and PSU-Nf-AgNPs in abiotic and in the presence of the bacterium environment was investigated via polarization techniques and electrochemical impedance spectroscopy (EIS). Corrosion analysis reveals that the charge transfer resistance (R_ct) increased because of the addition of the nanostructure resulting in a reduction in corrosion rate. SEM micrographs show Co surface was severely damaged by a microbial corrosive attack with severe crevices. However, the PSU-Nf and especially PSU-Nf-AgNPs coated Co surface was still covered by nanofiber coatings as the bacteria colony was not noticed. In addition, the results of the performing bacterial disk diffusion method indicated that electrospun PSU-Nf-AgNPs have good antibacterial activity against Gram-positive, Gram-negative, and model biofilm bacterium. It was found that the uncoated Co surface had severe crevices and offered poor corrosion resistance under mineral salt medium with A. eucrenophila strain. Therefore, PSU-Nf-AgNPs coated Co exhibited better corrosion resistance in mineral salt medium containing bacteria.

Abstract: The waste of palm sugar fiber from the home industry of glass noodles reaches 25 tons/day and has not been used economically regardless of the content of its cellulose about 52%. With the high content of cellulose, palm sugar fiber can be synthesized as a functional adsorbent to overcome the environmental issues that arise. The synthesis of nanofiber was carried out in several steps including washing the sample to remove dirt, synthesizing using a chemical approach (NaOH, HCl, NaClO₂, and CH₃COOH), and modifying the nanofiber surface with 3% and 5% cobalt oxide. The characterization showed that palm sugar fiber was successfully transformed into nanofiber based on XRD, FTIR, dan SEM results. The removal of dye waste was observed, showing that the adsorption capacity of nanofiber modified with 5% cobalt oxide calcined at 400 °C for 2 hours was suitable for methylene blue removal compared to congo red up to 9.162 mg/g. The adsorption followed the pseudo-second-order kinetic model with Langmuir adsorption isotherm.

Abstract: The field of nanotechnology has seen rapid advancements over the last decade. Nanofiber production through the method of electrospinning is one of the attraction points in this area. The nanofibers, prepared with nano-sized additives, particularly with polymer, have an extensive range of usages. This study utilizes silica aerogels obtained by the sol-gel method due to their low density of 700-800 gr/m². Polycaprolactone (PCL)-Silica Aerogel Nanofibers were attained by adding 0.5%,1%, 2%and 4% of previously produced aerogels to the nanofibers formed by electrospinning. This paper correspondingly examined the differences between AC-CL and MET-CL solvent groups being utilized during the preparation of the solutions. In addition to this examination, series of material tests were conducted, such as tensile test, SEM, FTIR, DTA/TG, and BET. Overall, the resultant nanofibers with a property of high surface area can be utilized in the design of materials applied to many areas, including solar devices, solar pools, sensors, and capacitors.

Abstract: In the present study, nanofibers of oxidized cellulose (OC) were prepared from dried bacterial cellulose using a mixture of nitric acid/phosphoric acid and sodium nitrite. Three types of dried bacterial cellulose were used as raw materials. The results revealed that dried sheet bacterial cellulose (DSBC) yielded 86.8% oxidized cellulose with 19.4% carboxyl content, whereas squeeze-dried bacterial cellulose (SDBC) yielded 53.3% OC with 28.6% carboxyl content, and freeze-dried bacterial cellulose (FDBC) yielded 55.6% of OC with 27.6% carboxyl content. The results revealed that OC neutralized with sodium hydroxide from SDBC showed the best swelling property among all types of OC. SDBC indicated the reduction of CFU exceeds 99.99% for gram-negative bacterium Escherichia coli ATCC 25922 and gram-positive bacterium Staphylococcus aureus ATCC 6538.

Abstract: Nanocomposites carbon nanotube (CNT)/TiO₂ nanofibers have been prepared by electrospinning. A mixed solution of titanium(IV) tetraisopropoxide (TTIP), polyvinyl pyrrolidone (PVP), and CNT were electrospun at 15 kV with 1 mL/h of flow rate and 10 cm for the distance between needle-tip and collector. The resulted fibers were calcined at 450 °C for 2 h to remove all the PVP. TiO₂ and CNT/TiO₂ nanofibers were characterized using X-ray Diffraction and SEM. The XRD analysis showed diffraction patterns for anatase TiO₂ with a diameter of ~81 nm. As combined with CNT, the fiber diameter increased to be 200-400 nm. The composite fiber of CNT/TiO₂ demonstrated enhanced photocatalytic performance for methylene blue photodegradation (~70%) under UV-light irradiation for 2 h compared to pristine TiO₂ nanofiber (~50%).