scholarly journals Probing Antimicrobial Halloysite/Biopolymer Composites with Electron Microscopy: Advantages and Limitations

Polymers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 3510
Author(s):  
Kirill Cherednichenko ◽  
Dmitry Kopitsyn ◽  
Svetlana Batasheva ◽  
Rawil Fakhrullin
Keyword(s):  
Electron Microscopy ◽  
Food Packaging ◽  
Thermo Gravimetric Analysis ◽  
Bulk Sample ◽  
General Information ◽  
Gravimetric Analysis ◽  
Microbial Biofilms ◽  
Abiotic Surfaces ◽  
Biopolymer Composites ◽  
Oppositely Charged

Halloysite is a tubular clay nanomaterial of the kaolin group with a characteristic feature of oppositely charged outer and inner surfaces, allowing its selective spatial modification. The natural origin and specific properties of halloysite make it a potent material for inclusion in biopolymer composites with polysaccharides, nucleic acids and proteins. The applications of halloysite/biopolymer composites range from drug delivery and tissue engineering to food packaging and the creation of stable enzyme-based catalysts. Another important application field for the halloysite complexes with biopolymers is surface coatings resistant to formation of microbial biofilms (elaborated communities of various microorganisms attached to biotic or abiotic surfaces and embedded in an extracellular polymeric matrix). Within biofilms, the microorganisms are protected from the action of antibiotics, engendering the problem of hard-to-treat recurrent infectious diseases. The clay/biopolymer composites can be characterized by a number of methods, including dynamic light scattering, thermo gravimetric analysis, Fourier-transform infrared spectroscopy as well as a range of microscopic techniques. However, most of the above methods provide general information about a bulk sample. In contrast, the combination of electron microscopy with energy-dispersive X-ray spectroscopy allows assessment of the appearance and composition of biopolymeric coatings on individual nanotubes or the distribution of the nanotubes in biopolymeric matrices. In this review, recent contributions of electron microscopy to the studies of halloysite/biopolymer composites are reviewed along with the challenges and perspectives in the field.

scholarly journals Development of Nervilia fordii Extract-Loaded Electrospun PVA/PVP Nanocomposite for Antioxidant Packaging

Foods ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1728
Author(s):  
Peng Wen ◽  
Teng-Gen Hu ◽  
Yan Wen ◽  
Ke-Er Li ◽  
Wei-Peng Qiu ◽  
...  
Keyword(s):  
Food Packaging ◽  
Thermo Gravimetric Analysis ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
Poly Vinyl Alcohol ◽  
Total Phenolic ◽  
Gravimetric Analysis ◽  
Thermo Gravimetric ◽  
Phenolic And Flavonoid ◽  
Thermal Stability Of

An ethyl acetate extract from of Nervilia fordii (NFE) with considerable suppression activity on lipid peroxidation (LPO) was first obtained with total phenolic and flavonoid contents and anti-LPO activity (IC50) of 86.67 ± 2.5 mg GAE/g sample, 334.56 ± 4.7 mg RE/g extract and 0.307 mg/mL, respectively. In order to improve its stability and expand its application in antioxidant packaging, the nano-encapsulation of NFE within poly(vinyl alcohol) (PVA) and polyvinyl(pyrrolidone) (PVP) bio-composite film was then successfully developed using electrospinning. SEM analysis revealed that the NFE-loaded fibers exhibited similar morphology to the neat PVA/PVP fibers with a bead-free and smooth morphology. The encapsulation efficiency of NFE was higher than 90% and the encapsulated NFE still retained its antioxidant capacity. Fourier transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD) analysis confirmed the successful encapsulation of NFE into fibers and their compatibility, and the thermal stability of which was also improved due to the intermolecular interaction demonstrated by thermo gravimetric analysis (TGA). The ability to preserve the fish oil’s oxidation and extend its shelf-life was also demonstrated, suggesting the obtained PVA/PVP/NFE fiber mat has the potential as a promising antioxidant food packaging material.

scholarly journals Enhanced Photocatalytic Activity of Cu2O Cabbage/RGO Nanocomposites under Visible Light Irradiation

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1712
Author(s):  
Appusamy Muthukrishnaraj ◽  
Salma Ahmed Al-Zahrani ◽  
Ahmed Al Otaibi ◽  
Semmedu Selvaraj Kalaivani ◽  
Ayyar Manikandan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermo Gravimetric Analysis ◽  
Visible Region ◽  
Catalytic Performance ◽  
Precipitation Method ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dye Pollutants ◽  
Transmission Electron

Towards the utilization of Cu2O nanomaterial for the degradation of industrial dye pollutants such as methylene blue and methyl orange, the graphene-incorporated Cu2O nanocomposites (GCC) were developed via a precipitation method. Using Hummers method, the grapheme oxide (GO) was initially synthesized. The varying weight percentages (1–4 wt %) of GO was incorporated along with the precipitation of Cu2O catalyst. Various characterization techniques such as Fourier-transform infra-red (FT-IR), X-ray diffraction (XRD), UV–visible diffused reflectance (UV-DRS), Raman spectroscopy, thermo gravimetric analysis (TGA), energy-dispersive X-ray analysis (EDX), and electro chemical impedance (EIS) were followed for characterization. The cabbage-like morphology of the developed Cu2O and its composites were ascertained from field-emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HR-TEM). In addition, the growth mechanism was also proposed. The results infer that 2 wt % GO-incorporated Cu2O composites shows the highest value of degradation efficiency (97.9% and 96.1%) for MB and MO at 160 and 220 min, respectively. Further, its catalytic performance over visible region (red shift) was also enhanced to an appreciable extent, when compared with that of other samples.

Effect of Synthesis Temperature on Particles Size and Morphology of Zirconium Oxide Nanoparticle

2017 ◽  
Vol 50 ◽  
pp. 18-31 ◽  
Author(s):  
Rudzani Sigwadi ◽  
Simon Dhlamini ◽  
Touhami Mokrani ◽  
Patrick Nonjola
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Zirconium Oxide ◽  
Thermo Gravimetric Analysis ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Crystallite Sizes ◽  
Ft Ir

The paper presents the synthesis and investigation of zirconium oxide (ZrO2) nanoparticles that were synthesised by precipitation method with the effects of the temperatures of reaction on the particles size, morphology, crystallite sizes and stability at high temperature. The reaction temperature effect on the particle size, morphology, crystallite sizes and stabilized a higher temperature (tetragonal and cubic) phases was studied. Thermal decomposition, band structure and functional groups were analyzed by Brunauer-Emmett-Teller (BET), Scanning Electron Microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Thermo-gravimetric analysis (TGA) and Fourier transform infrared (FT-IR). The crystal structure was determined using X-ray diffraction. The morphology and the particle size were studied using (SEM) and (TEM). The shaped particles were confirmed through the SEM analysis. The transmission electron microscopic analysis confirmed the formation of the nanoparticles with the particle size. The FT-IR spectra showed the strong presence of ZrO2 nanoparticles.

scholarly journals Structuration and Fabrication of Sensors Based on LTCC (Low Temperature Co-Fired Ceramic) Technology

2007 ◽  
Vol 336-338 ◽  
pp. 1849-1852 ◽  
Author(s):  
Hansu Birol ◽  
Thomas Maeder ◽  
Caroline Jacq ◽  
Giancarlo Corradini ◽  
Marc Boers ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Considerable Increase ◽  
Thermo Gravimetric Analysis ◽  
Ceramic Technology ◽  
Gravimetric Analysis ◽  
Thermo Gravimetric ◽  
Sensor Performance ◽  
Measuring Sensor ◽  
Selection Of ◽  
Scanning Electron

The purpose of this paper is to demonstrate sensors and structures fabricated using the LTCC technology, which has been addressed and employed increasingly as a smart packaging approach for several applications. The focus will be on inclination and cantilever force sensors and micro-fluidic structures. Motivation for selection of LTCC for these applications in addition to fabrication and structuring of the devices will be explained in details. TGA (thermo-gravimetric analysis), dilatometer analysis, SEM (scanning electron microscopy), electronic equipment for measuring sensor performance will be extensively used for explanation of the results. It will also be shown that, compared to classical thick-film technology on alumina, LTCC allows a considerable increase in sensitivity, and is therefore better suited for the sensing of minute forces and pressures.

Biosynthesis and Characterization of Copper Nanoparticles Using a Bioflocculant Extracted from Alcaligenis faecalis HCB2

2019 ◽  
Vol 11 (11) ◽  
pp. 1064-1070 ◽  
Author(s):  
Nkosinathi G. Dlamini ◽  
Albertus K. Basson ◽  
V. S. R. Rajasekhar Pullabhotla
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Copper Nanoparticles ◽  
Average Particle Size ◽  
Thermo Gravimetric Analysis ◽  
Average Particle ◽  
Gravimetric Analysis ◽  
X Ray ◽  
Transmission Electron ◽  
Ft Ir

Bioflocculant from Alcaligenis faecalis HCB2 was used in the eco-friendly synthesis of the copper nanoparticles. Nanoparticles were characterized using a scanning electron microscope (SEM), transmission electron microscopy (TEM), UV-visible spectroscopy, thermo gravimetric analysis (TGA) and Fourier Transform Infrared Spectroscopy (FT-IR). The transmission electron microscopy images showed close to spherical shapes with an average particle size of ∼53 nm. Energy-dispersive X-ray spectroscopy analysis confirmed the presence of the Cu nanopartilces and also the other elements such as O, C, P, Ca, Cl, Na, K, Mg, and S originated from the bioflocculant. FT-IR results showed the presence of the –OH and –NH2 groups, aliphatic bonds, amide and Cu–O bonds. Powder X-ray diffraction peaks confirmed the presence of (111) and (220) planes of fcc structure at 2 of 33° and 47° respectively with no other impurity peaks.

scholarly journals Synthesis of zirconia-based solid acid nanoparticles for fuel cell application

2016 ◽  
Vol 27 (2) ◽  
pp. 60 ◽  
Author(s):  
Rudzani A Sigwadi ◽  
Sipho E Mavundla ◽  
Nosipho Moloto ◽  
Touhami Mokrani
Keyword(s):  
Electron Microscopy ◽  
Thermo Gravimetric Analysis ◽  
Acid Sites ◽  
Precipitation Method ◽  
Zro2 Nanoparticles ◽  
Gravimetric Analysis ◽  
Ambient Temperatures ◽  
Fuel Cell Application ◽  
Transmission Electron ◽  
Zirconia Nanoparticles

Zirconia nanoparticles were prepared by the precipitation and ageing methods. The precipitation method was performed by adding ammonium solution to the aqueous solution of zirconium chloride at room temperature. The ageing method was performed by leaving the precipitate formed in the mother liquor in the glass beaker for 48 hours at ambient temperatures. The nanoparticles from both methods were further sulphated and phosphated to increase their acid sites. The materials prepared were characterised by X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), Brunauer-EmmettTeller (BET), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) methods. The XRD results showed that the nanoparticles prepared by the precipitation method contained mixed phases of tetragonal and monoclinic phases, whereas the nanoparticles prepared by ageing method had only tetragonal phase. The TEM results showed that phosphated and sulphated zirconia nanoparticles obtained from the ageing method had a smaller particle size (10–12 nm) than the nanoparticles of approximately 25–30 nm prepared by precipitation only. The BET results showed that the ZrO2 nanoparticles surface area increased from 32 to 72 m2/g when aged.

scholarly journals Study of Electrical and Thermal Properties of PVA-Nanosilica as A Candidate for Supercapacitor Separators

2021 ◽  
Vol 2110 (1) ◽  
pp. 012012
Author(s):  
N Hidayati ◽  
Munasir
Keyword(s):  
Electron Microscopy ◽  
Thermo Gravimetric Analysis ◽  
Glass Plate ◽  
Gravimetric Analysis ◽  
Thermo Gravimetric ◽  
Two Samples ◽  
Lcr Meter ◽  
Silica Dioxide ◽  
Pva Gel ◽  
Scanning Electron

Abstract Separator in the supercapacitor that separates the cathode from the anode has an important role in a supercapacitor circuit. Polyvinyl Alcohol (PVA) is a substitute for polyolefin which is commonly used as a supercapacitor separator and PVA has more environmentally friendly properties. The addition of silica dioxide nanocomposites is useful for adding thermal stability and electrical insulators. The method used to make the separator is quite simple, namely by casting a PVA gel membrane with nanosilica on a glass plate and drying it at low temperature. PVA membrane with nanosilica variations different precursors are from sand by coprecipitation method and from TEOS. The properties of the two samples were characterized by scanning electron microscopy (SEM), thermo gravimetric analysis (TGA), and LCR meter. Nanosilica derived from sand and from TEOS have no much different characteristic.

Synthesis of Carbon Nanostructures and CaCO3 Nanoparticles by Arc Discharge in Mineral Water

2011 ◽  
Vol 15 ◽  
pp. 57-67 ◽  
Author(s):  
V. Eskizeybek ◽  
E.S. Karabulut ◽  
A. Avci
Keyword(s):  
Electron Microscopy ◽  
Production Rate ◽  
Carbon Nanostructures ◽  
Mineral Water ◽  
Arc Discharge ◽  
Thermo Gravimetric Analysis ◽  
Gravimetric Analysis ◽  
Caco3 Nanoparticles ◽  
Multi Walled Carbon Nanotubes ◽  
Arc Current

The synthesis of multi-walled carbon nanotubes MWCNTs, carbon nanoshells, carbon nanoonions (CNOs), different types of carbon nanostructures and CaCO3 nanoparticles were performed using an arc-discharge method in mineral water. The structures of the synthesized nanostructures were visualized by scanning electron microscopy and transmission electron microscopy (TEM). Furthermore, ultraviolet-visible spectroscopy and thermo-gravimetric analysis (TGA) were used to determine the optical and thermal properties of the synthesized nanostructures. The TEM observations revealed that as-synthesized MWCNTs and CNOs have nominal diameters in the range of 10-20 nm and 30-50 nm, respectively. The CaCO3 nanoparticles were directly synthesized using arc discharge due to the presence of Ca minerals in the mineral water. The production rate of synthesized MWCNTs decreased when the arc current increased above 50 A, and the production rate of different nanoparticles increased with increasing arc current. The thermal-oxidative stability of the carbon nanostructures using TGA was explored separately under argon and oxygen atmospheres.

scholarly journals Preparation, characterization of fish scales biochar and their applications in the removal of anionic indigo carmine dye from aqueous solutions

2019 ◽  
Vol 80 (11) ◽  
pp. 2218-2231
Author(s):  
George O. Achieng ◽  
Chrispin O. Kowenje ◽  
Joseph O. Lalah ◽  
Stephen O. Ojwach
Keyword(s):  
Electron Microscopy ◽  
Aqueous Solutions ◽  
Adsorption Process ◽  
Indigo Carmine ◽  
Thermo Gravimetric Analysis ◽  
Gravimetric Analysis ◽  
Fish Scale ◽  
Solution Ph ◽  
X Ray ◽  
Indigo Carmine Dye

Abstract The preparation and applications of Tilapia (Oreochromis niloticus) fish scale biochars (FSB) as an adsorbent in the removal of indigo carmine dye (ICD) from aqueous solutions is described. The biochars were prepared through pyrolysis over a temperature range of 200 °C–800 °C and characterized for surface charge, functional groups, thermal stability, particle size and morphology, elemental composition, crystallinity, and surface area by using pHpzc, Fourier transform infrared (FTIR) spectroscopy, thermo-gravimetric analysis (TGA), transmission electron microscopy/scanning electron microscopy (TEM/SEM), energy dispersive X-ray (EDX) spectroscopy, powder X-ray diffraction (PXRD) and Brunauer-Emmett-Teller (BET) techniques, respectively. Batch experiments were carried out to determine the variation of adsorption process with initial dye concentration, contact time, initial solution pH, adsorbent load, temperature and adsorbent pyrolysis temperature on the removal of the dye. The percentage removal increased with increase in initial dye concentration and adsorbent dosage. A pH of 2 was the most appropriate for the adsorption experiments. The equilibrium data fitted pseudo-first-order kinetics and Freundlich models, while the thermodynamic parameters confirmed that the adsorption process was endothermic.

scholarly journals PEGylated MoS2 Nanosheets: A Dual Functional Photocatalyst for Photodegradation of Organic Dyes and Photoreduction of Chromium from Aqueous Solution

2019 ◽  
Vol 14 (1) ◽  
pp. 142 ◽  
Author(s):  
Madima Ntakadzeni ◽  
William Wilson Anku ◽  
Neeraj Kumar ◽  
Penny Poomani Govender ◽  
Leelakrishna Reddy
Keyword(s):  
Electron Microscopy ◽  
Aqueous Solution ◽  
Visible Light ◽  
Organic Dyes ◽  
Hexagonal Phase ◽  
Thermo Gravimetric Analysis ◽  
Gravimetric Analysis ◽  
Mos2 Nanosheets ◽  
X Ray ◽  
Dual Functional

This article reports the synthesis of PEGylated microspheres of MoS2 nanosheets through the hydrothermal method and its application in rhodamine B and methylene blue dyes photodegradation, and photoreduction of chromium(VI) to chromium(III) in water under illumination with visible light. The catalyst was characterized using X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray Spectroscopy (EDS), Fourier Transform Infra Red (FTIR), Thermo-gravimetric Analysis (TGA), and UV-Vis spectroscopies. XRD result reveals the MoS2 nanosheets to be present in the hexagonal phase of MoS2. SEM, TEM, and HRTEM images show that the synthesised sample has spherical shapes made up of several thin sheets of MoS2. The catalyst showed visible light responsivity with a calculated band gap of 1.92 eV. The MoS2 nanosheets exhibited high degradation efficiency against both dyes. The RhB and MB dyes experienced degradation efficiencies of 97.30 % (RhB) and 98.05 % (MB) in 75 min 90 min, respectively.  The MoS2 photocatalyst is also observed to be effective in photocatalytic reduction of Cr(VI) and displayed 91.05% reduction of Cr(VI) to Cr(III) in 75 min. The results reveal that the synthesised MoS2 nanosheet is a good photocatalytic material for degradation of dyes and reduction of Cr(VI) to Cr(III) in water. Copyright © 2019 BCREC Group. All rights reservedReceived: 22nd February 2018; Revised: 24th October 2018; Accepted: 30th October 2018; Available online: 25th January 2019; Published regularly: April 2019How to Cite: Ntakadzeni, M., Anku, W.W., Kumar, N., Govender, P.P., Reddy, L. (2019). PEGylated MoS2 Nanosheets: A Dual Functional Photocatalyst for Photodegradation of Organic Dyes and Photoreduction of Chromium from Aqueous Solution. Bulletin of Chemical Reaction Engineering & Catalysis, 14 (1): 142-152 (doi:10.9767/bcrec.14.1.2258.142-152)Permalink/DOI: https://doi.org/10.9767/bcrec.14.1.2258.142-152 

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