scholarly journals Liquid Phase Selective Hydrogenation of Phenol to Cyclohexanone over Electrospun Pd/PVDF-HFP Catalyst

Fibers ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 28 ◽  
Author(s):  
Ahmed Abutaleb ◽  
Dinesh Lolla ◽  
Abdulwahab Aljuhani ◽  
Hyeon Shin ◽  
Mohammad Ali ◽  
...  
Keyword(s):  
Polyvinylidene Fluoride ◽  
Batch Reactor ◽  
Electrospun Nanofibers ◽  
Original Research ◽  
Electrospinning Technique ◽  
Efficient Catalyst ◽  
Drop Shape ◽  
Multiphase Reactions ◽  
Transmission Electron ◽  
Phenol Conversion

Cyclohexanone is an important industrial intermediate in the synthesis of materials such as nylons, but preparing it efficiently through one-step hydrogenation of phenol is hindered by over-reduction to cyclohexanol. Using an efficient catalyst can enhance the selectivity of cyclohexanone at high phenol conversion. In this study, catalysts comprised of palladium nanoparticles supported on electrospun PVDF-HFP (polyvinylidene fluoride-co-hexafluoropropylene) nanofibers were prepared using the electrospinning technique. The catalysts were characterized using thermogravimetric analyzer (TGA), scanning electron microscopy (SEM), transmission electron microscope (TEM), and drop shape analyzer (DSA). The prepared catalysts were used to hydrogenate phenol into cyclohexanone in a batch reactor. The Pd/PVDF-HFP catalyst showed a very high product selectivity and high phenol conversion. The conversion of phenol achieved was 98% with 97% cyclohexanone selectivity in 7 h using 15 wt% of palladium (0.0021 moles) relative to phenol (0.0159 moles). The turnover number (TON) and turnover frequency (TOF) values calculated were 7.38 and 1.05 h−1, respectively. This paper presents original research in heterogeneous catalysis using novel electrospun nanofibers. Multiphase hydrogenation of phenol to cyclohexanone over electrospun Pd/PVDF-HFP catalyst has not been reported by any researcher in the literature. This work will also provide a research window for the application of electrospun polymeric nanofibers in multiphase reactions.

FABRICATION AND CHARACTERIZATION OF POLYVINYLIDENE FLUORIDE COMPOSITE NANOFIBER MEMBRANE FOR WATER FLUX PROPERTY

2015 ◽  
Vol 74 (11) ◽  
Author(s):  
Azizul Mohd Zahari ◽  
Abdull Rahim Mohd Yusoff ◽  
Nor Aziah Buang ◽  
Palanivel Satishkumar ◽  
M Jasmin Fathi Jasni ◽  
...  
Keyword(s):  
Polyvinylidene Fluoride ◽  
Pure Water ◽  
Water Flux ◽  
Electrospun Nanofibers ◽  
External Diameter ◽  
Electrospinning Technique ◽  
Water Treatment Process ◽  
Pure Water Flux ◽  
Hydrophobic Nature

This research is about the investigation of the pure water flux property of composite polyvinylidene fluoride (PVDF) nanofibers. Electrospinning technique was used to prepare the composite electrospun nanofibers. PVDF was dissolved in N,N-dimethylformamide (DMF) solvent and blended together with activated carbon (AC) and polyvinylpyrrolidone (PVP). The nanofibers were characterized to determine the morphologies, wettability property, and its tensile strength. The fabricated nanofibers diameter was found in the range between 20 to 180 nm. The presence of AC deteriorates the mechanical properties of the nanofibers as the size of AC is larger than the external diameter of the nanofibers. The results of contact angle confirmed that the fabricated nanofiber exhibit less hydrophobic in the presence of PVP and AC. The less hydrophobic nature of proposed nanofiber might be useful for the water treatment process.

scholarly journals Formation and Photoluminescence Properties of ZnO Nanoparticles on Electrospun Nanofibers Produced by Atomic Layer Deposition

Coatings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1199 ◽  
Author(s):  
Valerii Myndrul ◽  
Lucie Vysloužilová ◽  
Andrea Klápšťová ◽  
Emerson Coy ◽  
Mariusz Jancelewicz ◽  
...  
Keyword(s):  
Atomic Layer Deposition ◽  
Polyvinylidene Fluoride ◽  
Electrospun Nanofibers ◽  
Atomic Layer ◽  
Excitation Power ◽  
Electrospinning Technique ◽  
X Ray ◽  
Layer Deposition ◽  
Polymer Nanofiber ◽  
Wide Range

The unique combination of optical, chemical, and structural properties of one-dimensional zinc oxide (1D ZnO) makes it one of the most attractive materials in a wide range of research and applications. In the present study, 1D ZnO nanomaterials were fabricated using a combination of two independent methods: electrospinning and atomic layer deposition (ALD). The electrospinning technique was used to produce 1D electrospun fibers consisting of four types of polymers: polylactic acid (PLLA), polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), and polyamide 6 (PA6). The ALD technology, in turn, was selected as an excellent candidate for the synthesis of a ZnO thin layer over polymer fibers for the production of 1D ZnO/polymer nanofiber composites (PLLA/ZnO, PVDF/ZnO, PVA/ZnO, PA6/ZnO). Structural and optical properties of the produced nanofibers were studied by means of scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), diffuse reflectance, and photoluminescence (PL) spectroscopy. It was found that only PVDF/ZnO nanofibers exhibit stable room temperature PL that may be the result of a higher ZnO content in the sample. In addition, PL measurements were conducted as a function of excitation power and temperature in order to establish the main PL mechanisms and parameters for the PVDF/ZnO sample, as a most promising candidate for the biophotonic application.

scholarly journals Electrospun Nanostructured Membrane Engineering Using Reverse Osmosis Recycled Modules: Membrane Distillation Application

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1601
Author(s):  
Jorge Contreras-Martínez ◽  
Carmen García-Payo ◽  
Mohamed Khayet
Keyword(s):  
Reverse Osmosis ◽  
Polyvinylidene Fluoride ◽  
Membrane Distillation ◽  
Permeate Flux ◽  
Electrospinning Technique ◽  
Salt Rejection ◽  
Rejection Factor ◽  
Nanofibrous Membranes ◽  
Membrane Engineering ◽  
Desalination Plants

As a consequence of the increase in reverse osmosis (RO) desalination plants, the number of discarded RO modules for 2020 was estimated to be 14.8 million annually. Currently, these discarded modules are disposed of in nearby landfills generating high volumes of waste. In order to extend their useful life, in this research study, we propose recycling and reusing the internal components of the discarded RO modules, membranes and spacers, in membrane engineering for membrane distillation (MD) technology. After passive cleaning with a sodium hypochlorite aqueous solution, these recycled components were reused as support for polyvinylidene fluoride nanofibrous membranes prepared by electrospinning technique. The prepared membranes were characterized by different techniques and, finally, tested in desalination of high saline solutions (brines) by direct contact membrane distillation (DCMD). The effect of the electrospinning time, which is the same as the thickness of the nanofibrous layer, was studied in order to optimize the permeate flux together with the salt rejection factor and to obtain robust membranes with stable DCMD desalination performance. When the recycled RO membrane or the permeate spacer were used as supports with 60 min electrospinning time, good permeate fluxes were achieved, 43.2 and 18.1 kg m−2 h−1, respectively; with very high salt rejection factors, greater than 99.99%. These results are reasonably competitive compared to other supported and unsupported MD nanofibrous membranes. In contrast, when using the feed spacer as support, inhomogeneous structures were observed on the electrospun nanofibrous layer due to the special characteristics of this spacer resulting in low salt rejection factors and mechanical properties of the electrospun nanofibrous membrane.

scholarly journals Conformal Fabrication of an Electrospun Nanofiber Mat on a 3D Ear Cartilage-Shaped Hydrogel Collector Based on Hydrogel-Assisted Electrospinning

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Jin Yeong Song ◽  
Hyun Il Ryu ◽  
Jeong Myeong Lee ◽  
Seong Hwan Bae ◽  
Jae Woo Lee ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Electrospun Nanofibers ◽  
Cell Delivery ◽  
Complex Geometries ◽  
Two Dimensional ◽  
Uniform Thickness ◽  
Electrospun Nanofiber ◽  
Electrospinning Technique ◽  
Ear Cartilage ◽  
Focused Electric Field

AbstractElectrospinning is a common and versatile process to produce nanofibers and deposit them on a collector as a two-dimensional nanofiber mat or a three-dimensional (3D) macroscopic arrangement. However, 3D electroconductive collectors with complex geometries, including protruded, curved, and recessed regions, generally caused hampering of a conformal deposition and incomplete covering of electrospun nanofibers. In this study, we suggested a conformal fabrication of an electrospun nanofiber mat on a 3D ear cartilage-shaped hydrogel collector based on hydrogel-assisted electrospinning. To relieve the influence of the complex geometries, we flattened the protruded parts of the 3D ear cartilage-shaped hydrogel collector by exploiting the flexibility of the hydrogel. We found that the suggested fabrication technique could significantly decrease an unevenly focused electric field, caused by the complex geometries of the 3D collector, by alleviating the standard deviation by more than 70% through numerical simulation. Furthermore, it was experimentally confirmed that an electrospun nanofiber mat conformally covered the flattened hydrogel collector with a uniform thickness, which was not achieved with the original hydrogel collector. Given that this study established the conformal electrospinning technique on 3D electroconductive collectors, it will contribute to various studies related to electrospinning, including tissue engineering, drug/cell delivery, environmental filter, and clothing.

scholarly journals Mechanical and Dielectric Properties of Aligned Electrospun Fibers

Fibers ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 4
Author(s):  
Blesson Isaac ◽  
Robert M. Taylor ◽  
Kenneth Reifsnider
Keyword(s):  
Dielectric Properties ◽  
Dielectric Property ◽  
Electrospun Nanofibers ◽  
Cold Drawing ◽  
General Interest ◽  
Electrospun Fibers ◽  
Energy Storage Devices ◽  
Electrospinning Technique ◽  
Specific Strength ◽  
Aligned Nanofibers

This review paper examines the current state-of-the-art in fabrication of aligned fibers via electrospinning techniques and the effects of these techniques on the mechanical and dielectric properties of electrospun fibers. Molecular orientation, system configuration to align fibers, and post-drawing treatment, like hot/cold drawing process, contribute to better specific strength and specific stiffness properties of nanofibers. The authors suggest that these improved, aligned nanofibers, when applied in composites, have better mechanical and dielectric properties for many structural and multifunctional applications, including advanced aerospace applications and energy storage devices. For these applications, most fiber alignment electrospinning research has focused on either mechanical property improvement or dielectric property improvement alone, but not both simultaneously. Relative to many other nanofiber formation techniques, the electrospinning technique exhibits superior nanofiber formation when considering cost and manufacturing complexity for many situations. Even though the dielectric property of pure nanofiber mat may not be of general interest, the analysis of the combined effect of mechanical and dielectric properties is relevant to the present analysis of improved and aligned nanofibers. A plethora of nanofibers, in particular, polyacrylonitrile (PAN) electrospun nanofibers, are discussed for their mechanical and dielectric properties. In addition, other types of electrospun nanofibers are explored for their mechanical and dielectric properties. An exploratory study by the author demonstrates the relationship between mechanical and dielectric properties for specimens obtained from a rotating mandrel horizontal setup.

scholarly journals Facile preparation of α-Fe2O3 nanobulk via bubble electrospinning and thermal treatment

2016 ◽  
Vol 20 (3) ◽  
pp. 967-972 ◽  
Author(s):  
Peng Liu ◽  
Chun-Hui He ◽  
Fujuan Liu ◽  
Lan Xu ◽  
Yuqin Wan ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Photoelectron Spectroscopy ◽  
Polyvinylidene Fluoride ◽  
Iron Chloride ◽  
Electrospinning Technique ◽  
Broad Application ◽  
X Ray ◽  
Chloride Hexahydrate ◽  
Facile Preparation ◽  
Scanning Electron

In this work, ?-Fe2O3 nanobulk with high aspect ratio were successfully prepared via a facile bubble electrospinning technique using polyvinylidene fluoride and iron chloride hexahydrate (FeCl3?6H2O) as ?-Fe2O3 precursor followed by annealing in air at 600?C. The products were characterized with field emission scanning electron microscope, Fourier transform infrared, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The results showed that ?-Fe2O3 nanobulk has a hierarchical heterostructure which has an extremely broad application prospect in many areas.

scholarly journals A comparative study on the VOCs sensing behaviors of various ZnO nanostructures

2020 ◽  
Vol 9 (4) ◽  
pp. 117-122
Author(s):  
Vuong Nguyen Minh ◽  
Dung Dinh Tien ◽  
Hieu Hoang Nhat ◽  
Nghia Nguyen Van ◽  
Truong Nguyen Ngoc Khoa ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Hierarchical Structure ◽  
Hydrothermal Process ◽  
Zno Nanostructures ◽  
X Ray Diffraction ◽  
Wet Chemical Method ◽  
Electrospinning Technique ◽  
Transmission Electron ◽  
Volatile Organic ◽  
Wet Chemical

The volatile organic compounds (VOCs) sensing layers were studied using ZnO nanomaterials with different morphologies including hierarchical nanostructure (ZnO-H), nanorods (ZnO-NRs), commercial nanoparticles (ZnO-CNPs) and wet chemical synthesized nanoparticles (ZnO-HNPs). ZnO hierarchical structure was fabricated by an electrospinning technique followed by hydrothermal process. ZnO vertical nanorods structure was fabricated by hydrothermal method, while ZnO nanoparticles based sensors were prepared from commercial powder and wet chemical method. The morphology and properties of the fabricated samples were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). VOCs sensing responses toward acetone, ethanol and methanol with respect to altered ZnO nanostructureswas systematically compared at different working temperatures. The enhanced response at low working temperatures induced by theopen space hierarchical structure was observed. The VOCs sensing mechanisms of the ZnO nanostructures based sensing layer were also explained and discussed in detail. 

Synthesis of Indole Derivatives Using Biosynthesized ZnO-CaO Nanoparticles as an Efficient Catalyst

2021 ◽  
Vol 66 ◽  
pp. 61-71
Author(s):  
Tahereh Heidarzadeh ◽  
Navabeh Nami ◽  
Daryoush Zareyee
Keyword(s):  
Electron Microscopy ◽  
Indole Derivatives ◽  
X Ray Diffraction ◽  
Efficient Catalyst ◽  
X Ray ◽  
Transmission Electron ◽  
Solvent Free Conditions ◽  
Ft Ir ◽  
Eggshell Waste ◽  
Aromatic And Aliphatic Amines

The principal aim of this research is using biosynthesized ZnO-CaO nanoparticles (NPs) for preparation of indole derivatives. ZnO-CaO NPs have been prepared using Zn(CH3COO)2 and eggshell waste powder in solvent-free conditions. Morphology and structure of NPs were determined by FT-IR, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy dispersive spectra (EDS). It was used as a highly efficient catalyst for the synthesis of indole derivatives. Some indole derivatives were synthesized by the reaction of indole, formaldehyde, aromatic and aliphatic amines in the presence of ZnO-CaO NPs (5 mol%) in ethanol under reflux conditions. The assigned structure was further established by CHN analyses, NMR, and FT-IR spectra. Because of excellent capacity, the exceedingly simple workup and good yield, eco-friendly catalyst ZnO-CaO NPs were proved to be a good catalyst for this reaction.

STAND-ALONE WATER TREATMENT: PERFORMANCE OF ELECTROSPUN NANOFIBERS

2016 ◽  
Vol 78 (12) ◽  
Author(s):  
A. Mataram ◽  
A. F. Ismail ◽  
E. Yuliwati ◽  
T. Matsuura ◽  
S. Rizal ◽  
...  
Keyword(s):  
Oxygen Demand ◽  
Electrospun Nanofibers ◽  
Water Filtration ◽  
Electrospinning Technique ◽  
Treatment Performance ◽  
Flat Sheet ◽  
Electrospun Membranes ◽  
Suspend Solid ◽  
Total Suspend Solid ◽  
Microfiltration Membranes

The aim of this study was to evaluate the use of nanofiber microfiltration membranes, spun by an innovative electrospinning technique, in water filtration applications. This study bridges between developments in electrospinning techniques for the production of flat sheet membranes and the application of these membranes in water filtration. The functionalized or non-functionalized for the removal of pathogens was investigated, in term of chemical oxygen demand, total suspend solid and ammonium in the waste water. Physical properties such as clean water permeability (CWP) and strength were also examined. The results showed a very good removal of TSS (range 94.83-97.34%), COD (89.32-95.27%) and NH3­-N (64.48-72.87%). These test showed that the electrospun membranes can be used for water filtration applications. 

Biomimetic tough helicoidally structured material through novel electrospinning based additive manufacturing

MRS Advances ◽  
2019 ◽  
Vol 4 (43) ◽  
pp. 2345-2354 ◽  
Author(s):  
Komal Agarwal ◽  
Rahul Sahay ◽  
Avinash Baji ◽  
Arief S. Budiman
Keyword(s):  
Structural Design ◽  
Polyvinylidene Fluoride ◽  
Architectural Design ◽  
Mechanical Characteristics ◽  
Near Field ◽  
Structural Materials ◽  
Electrospinning Technique ◽  
Mantis Shrimp ◽  
Novel Method ◽  
Microstructural Design

ABSTRACTNatural structural materials (NSMs) such as nacre, teeth, bones and crustacean exoskeleton are usually made of weak biomaterials arranged in specific structural design imparting them remarkable mechanical characteristics. Such hierarchical structural layouts found in nature encourage designing of mechanically desirable synthetic structural materials (SSMs). Among variety of natural hierarchical layouts, this paper specifically focuses on helicoidal architectural design found in the tough dactyl club of mantis shrimp. We first decode the mechanics behind helicoidal microstructural design and document the development of impact resistant macroscale helicoidal architectured synthetic structural materials (HA-SSMs). Next, near-field electrospinning technique (NFES)- both melt (polycaprolactone) and solution (polyvinylidene fluoride) type has been discussed in detail, as a novel method for developing lab scale 3D biomimetic HA-SSMs in micro-nanoscale. Further, the effect of the helical arrangement, size of substructures and surface treatment on strength and toughness of NFES fabricated HA-SSMs samples is analysed.

Sign in / Sign up

Export Citation Format

Share Document