Amount Of ZnO Research Articles

Quantification by Powder X-ray Diffraction of Metal Oxides Segregation During Formation of Layered Double Hydroxides

A simple, easily applicable method is proposed to quantify the amount of ZnO segregated during synthesis and post-synthesis treatments of Zn-Al layered double hydroxides with the hydrotalcite structure. The method provides a feasible, easy, fast, and reliable way to get values for ZnO content, and the method can be extended to other compounds.

Quantification by Powder X-ray Diffraction of Metal Oxides Segregation During Formation of Layered Double Hydroxides

A simple, easily applicable method is proposed to quantify the amount of ZnO segregated during synthesis and post-synthesis treatments of Zn-Al layered double hydroxides with the hydrotalcite structure. The method provides a feasible, easy, fast, and reliable way to get values for ZnO content, and the method can be extended to other compounds.

Fabrication and electrochemical properties of flexible ZnO doped PVA-Borax based solid-gel electrolytes

The flexible solid electrolytes are important for flexible batteries and supercapacitors. For that reason, we fabricated ZnO doped PVA-Borax based solid-gel electrolytes for 5%, 10% and 15% ZnO amounts in this study by chemical composition. The obtained ZnO doped PVA-Borax electrolytes were characterized by cyclic voltammetry (CV) measurements for 100, 200 and 400 mV scanning speeds and Raman spectroscopy. Furthermore, the two-electrode method was employed to determine the capacitance within the range of 0–1 V by 400 mV per second constant scan speed and then capacitance values of samples were calculated. Raman spectroscopy of the samples confirmed the ZnO doping in the PVA-Borax matrix. The obtained CV results revealed that the electrolytes exhibited rectangular shape due to its supercapacitor behavior. Also, the ZnO doping positively affected the supercapacitor behaviors. The results highlighted that the fabricated electrolytes can be improved for supercapacitor applications.

Surface Wettability of ZnO-Loaded TiO2 Nanotube Array Layers

Herein we report on the synthesis and the effects of gradual loading of TiO2 nanotube array layers with ZnO upon surface wettability. Two-step preparation was chosen, where TiO2 nanotube layers, grown in a first instance by anodization of a Ti foil, were gradually loaded with controlled amounts of ZnO using the reactive RF magnetron sputtering. After crystallization annealing, the formerly amorphous TiO2 nanotubes were converted to predominantly anatase crystalline phase, as detected by XRD measurements. The as-prepared nanotubes exhibited a well-aligned columnar structure, 1.6 μm long and 88 nm in diameter, and a small concentration of oxygen vacancies. Ti2+ and Ti3+ occur along with the Ti4+ state upon sputter-cleaning the layer surfaces from contaminants. The Ti2+ and Ti3+ signals diminish with gradual ZnO loading. As demonstrated by the VB-XPS data, the ZnO loading is accompanied by a slight narrowing of the band gap of the materials. A combined effect of material modification and surface roughness was taken into consideration to explain the evolution of surface super-hydrophilicity of the materials under UV irradiation. The loading process resulted in increasing surface wettability with approx. 33%, and in a drastic extension of activation decay, which clearly points out to the effect of ZnO-TiO2 heterojunctions.

Effect of ZnO/Ag Nanocomposites Against Anionic and Cationic Dyes as Photocatalysts and Antibacterial Agents

Engineering efficient, strong and cost-effective nanoparticles with strong inhibitory activities are the growing need at present. Using the strategies of doping, Zinc oxide/Silver nanocomposites (ZnO/Ag NCs) namely 0.9 M ZnO: 0.1 M Ag, 0.7 M ZnO: 0.3 M Ag and 0.5 M ZnO: 0.5 M Ag were synthesized hydrothermally. The average crystallite sizes for the ZnO/Ag NCs were 31 nm, 29 nm and 23 nm. The band gap energy (Eg) for the ZnO/Ag NCs was estimated to be 3.09 eV, 3.12 eV and 3.18 eV using Tauc’s plot. Grain-like morphological images was observed in the Scanning Electron Microscopy (SEM), which helps in effective promotion of degrading methyl orange (MO), methylene blue (MB) and crystal violet (CV) under visible light irradiation with a rate constant of 5 × 10–3/min, 16.6 × 10–3/min and 4 × 10–3/min respectively. This superior photocatalytic decomposition of dye are ascribed to smaller particle size, high surface area, the ability to absorb visible light and the efficient charge separation associated with the synergetic effects of appropriate amounts of ZnO and Ag in the prepared samples. In addition, the antibacterial efficacy of the NCs is observed as 90 and 100% for 75 μl. These hydrothermally synthesized synergistic NCs can be designed for large-scale fabrication of NC materials for potential applications in photocatalytic and antibacterial activity.

Electrosprayed gum tragacanth/zinc oxide nanoparticles and their application as antibacterial agent on cotton terry towel

In this study, the antibacterial properties of 100% cotton terry towels, electrosprayed with gum tragacanth/ZnO nanoparticles are investigated. Various concentrations of gum tragacanth/ZnO in water and water–ethanol (70:30) are electrosprayed and evaluated by SEM. The results show that increasing the amount of ZnO (up to 200% w/w relative to gum tragacanth) lowers the mean size of the electrosprayed nanoparticles. FTIR spectroscopy proves a decrease in hydrogen bonding of tragacanth as a result of the interaction between gum tragacanth and ZnO. XRD analysis show a hexagonal wurtzite phase for ZnO nanoparticles in the tragacanth matrix. The antibacterial analyses show that the samples electrosprayed with gum tragacanth/ZnO nanoparticles are active against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria. Briefly, in the absence of any cross-linking agent, 70% of antibacterial activity is retained after the first wash.

Fabrication and characterization of an active bionanocomposite film based on basil seed mucilage and ZnO nanoparticles

In this study, active nanofilms were developed using basil seed mucilage (BSM) containing zinc oxide nanoparticles (ZnO-NPs), according to casting method. Different amount of ZnO-NPs at the range of 0% (control), 0.1, 0.25, and 0.5% were incorporated into BSM film, then the physical, permeability, mechanical, thermal, and antimicrobial properties, as well as color index of fabricated films were examined. The results showed that moisture content, water absorption, water solubility, water vapor permeability (WVP), melting temperature (Tm), glass transition temperature (Tg) decreased with increasing the amount of ZnO, while the melting enthalpy of films increased (P < 0.05). The addition of ZnO-NPs up to 0.25% resulted in significant increase in the ultimate tensile strength, light (L*) and white indexes. Additionally, the basil seed mucilage film did not show antibacterial performance, while added of ZnO-NPs to the film, caused an increased trend in the antibacterial activity of films. The fabricated nanofilms prevented the growth of Listeria monocytogenes, Escherichia coli, Staphylococcus aureus, and Salmonella typhimurium (P < 0.05). All in all, the developed nanobiocomposite film using BSM containing 0.25% ZnO-NPs could be used as biodegradable and antibacterial film for food active packing to increase the shelf life of food.

Structure-dependence of anti-methicillin-resistant staphylococcus aureus (MRSA) activity on ZnO-containing bioglass

Drug-resistant infection control is an important concern when developing biomedical materials. In this regard, most studies have investigated the effect of metal ions incorporated in bioglass. However, the relevance of bioglass structure and antibacterial activity have received limited attention. In this study, the bioglass of mol% composition 80SiO2–15CaO–5P2O5 (80S) was synthesized by evaporation-induced self-assembly (EISA). We can suppose that the Zn substituted in the 80S glass matrix of the xZnO/80S series) would dilute the total content of Ca, thus decrease the overall antibacterial activity and mineralization of the xZnO/80Sseries. To further support our hypothesis, a series of 80S with ZnO powders (80S + xZnO) was analyzed as well. The results of X-ray diffraction (XRD), scanning electron microscopy (SEM), and nuclear magnetic resonance (NMR) indicated that tetrahedral coordinated Zn2+ was dissolved in the glass as a solid solution. Moreover, in the xZnO/80S series, because of the structure of Zn2+ substituted in the glass, the amount of ZnO being released was limited and no anti-methicillin-resistant staphylococcus aureus (MRSA) activity was detected. In conclusion, this study has confirmed and integrated that the suitable application of the textural-structure properties of ZnO substituted in bioglass for the future allocate.

The unforeseen relationship of Fe2O3 and ZnO on fibrous silica KCC-1 catalyst for fabricated Z-scheme extractive-photooxidative desulphurization

Fibrous silica KAUST Catalysis Centre (KCC-1) was prepared via a hydrothermal-microwave method, followed by incorporation of Fe2O3 and ZnO by an electrochemical technique to give ZnO-Fe2O3/KCC-1 (ZFK) catalysts. XRD, FESEM, N2 physisorption, FTIR, XPS, ESR and UV–Vis DRS were employed to characterize the catalysts. A varied amount of Fe2O3 and ZnO seems have insightful impact on the physicochemical behaviours of the KCC-1 while prominently enhanced the extractive-photooxidative desulphurization of dibenzothiophene (DBT). 5Z10FK demonstrated the best performance mainly due to a well distribution of both metal oxides on KCC-1, the highest Si-O-Fe and Si-O-Zn bonds, an appropriate amount of surface defect and suitable band gap energy. Besides, the suitable band positions of 10FK and 5ZK in 5Z10FK composite has allowed the formation of Z-scheme heterojunction for conserved strong redox potential. Kinetic studies revealed that the adsorption of DBT was the rate determining step, thus this reaction obeyed the Langmuir-Hinshelwood pseudo-first order.

Selective hydrogenolysis of biomass-derived sorbitol to propylene glycol and ethylene glycol on in-situ formed PdZn alloy catalysts

Sorbitol hydrogenolysis to industrially important propylene glycol and ethylene glycol receives increasing attention, recently. Here, we developed an efficient and stable PdZn alloy catalyst, in-situ formed from a physical mixture of Pd/ZrO2 and ZnO, for the sorbitol hydrogenolysis with Mg3AlOx as a solid base, and obtained a 54.6% yield of the two target glycols (493 K and 5.0 MPa H2). The amounts of ZnO and Mg3AlOx strongly influenced the activity and selectivity, due to their effects on the formation of the PdZn alloys and the competitive metal-catalyzed dehydrogenation/hydrogenation and base-catalyzed retro-aldol condensation steps. The kinetic isotope effects, combined with the inhibiting effects of H2 pressure on the activity in a broad range (3.0–8.0 MPa), confirm that the sorbitol dehydrogenation to hexose intermediates is the kinetically-relevant step in the sorbitol hydrogenolysis. This study provides insights into the catalytic functions and reaction parameters for the hydrogenolysis of polyols to the target glycols.

New composite of pecan nutshells biochar-ZnO for sequential removal of acid red 97 by adsorption and photocatalysis

A new composite, biochar derived from pecan nutshell with ZnO (biochar-ZnO) was prepared, in order to obtain a potential catalyst for degradation of Reactive Red 97 (RR97) from aqueous solutions. Composites with different ratio of ZnO supported in the biochar were produced using mechanical mixing and pyrolysis in a reducing atmosphere from N2 at 650 °C. The catalyst composites were characterized by XRD, FT-IR, UV–Vis, FE-SEM, EDS, and BET. The composites presented higher activity compared to ZnO pure. The composite with greater amount of ZnO supported in the biochar (N20Z) degraded 100% of RR97 in only 67 min (30 min biosorption + 37 min photocatalysis). This remarkable performance could be associated to decrease of electron-hole recombination rate, reducing the band gap energy, and increasing the surface area of the photocatalyst. The recycling of the composite N20Z indicated that it can be used for more than 9 cycle and be easily removed from solution. Radical scavenger tests indicated that •OH and h+ were the predominant active species involved on the degradation of RR97. The proposed mechanism indicated that RR97 molecule degrades into lower-mass intermediates Therefore, the composite presented intrinsic properties that become it a promising catalyst for removal of emerging contaminant in water.

Synthesis and physicochemical characterization of a ZnO-Chitosan hybrid-biocomposite used as an environmentally friendly photocatalyst under UV-A and visible light irradiations

Abstract In this investigation, hybrid-biocomposites “ZnO-Chitosan” were synthesized using a chitosan biomaterial and various amounts of ZnO particles (7 and 93 wt percent). The chitosan was obtained from the exoskeletons of shrimp shells, which were collected from the fishmongers in Meknes city (Morocco). Several techniques including X-ray diffraction, Fourier transform infrared spectroscopy, differential thermal analysis and thermogravimetric analysis, diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy coupled with energy dispersive spectroscopy were used for the characterization of the synthesized hybrid-biocomposites. The obtained experimental results showed the existence of a strong interaction between Zn2+, and the amino and hydroxyl groups of chitosan only for the hybrid-biocomposite containing 7 wt percent of ZnO. This suggests that the structure of this sample is probably formed via a complexation between Zn2+ ions which are linked to –NH2, -OH groups of chitosan, and H2O molecules. The photocatalytic activity of the as-prepared hybrid-biomaterials was then evaluated by measuring the degradation efficiency of methyl orange (MO) and paranitrophenol (pNP) under both UV-A and visible light irradiation. The obtained results indicated that the photocatalytic performance was significantly improved by adding an optimum amount of ZnO (7 wt %) to the chitosan biomaterial, and suggested that the photocatalytic activity depended closely on the ZnO weight percent. The role of the active species (electrons, holes and hydroxyl radicals) in the photocatalytic process has been studied and the probable degradation mechanisms of MO and pNP under both UV-A and visible light illuminations were proposed.

One-step synthesis of zinc-encapsulated MCM-41 as H2S adsorbent and optimization of adsorption parameters

The nano-sized structure of well-ordered Zn@MCM-41 adsorbent was synthesized through a direct hydrothermal method using CTAB as a structure-directing agent in an ammonia aqueous solution with different amounts of zinc acetylacetonate which were inserted into the structure-directing agent's loop during the synthesis. The XRD, HRTEM, and N2 adsorption-desorption isotherms were used to characterize the prepared ZnO functionalized mesoporous silica samples. As a result, the presence of ZnO in highly-ordered MCM-41's pore was proved as well as maintenance of the ordered mesostructure of MCM-41. The materials were possessed with a high specific surface area (1114-509 m2.g-1) and a large pore diameter (4.03-3.27 nm). Based on the obtained results from the adsorption of H2S gas in a lab-made setup, the Znx@MCM-41 showed the superior ability to increase of ZnO amount up to 7 hours as a breakthrough point.

Interfacial effects on ferroelectric and dielectric properties of GO reinforced free-standing and flexible PVDF/ZnO composite membranes: Bias dependent impedance spectroscopy

Flexible membranes with attractive ferroelectric and dielectric properties are promising for numerous technological devices, such as, energy storage and harvesting devices, sensors etc. Here we report the development of conducting nanofiller containing inorganic semiconductor and organic polymer based tri-phase composite membranes and demonstrate their ferroelectric and frequency dependent dielectric characteristics. The graphene oxide (GO) nanosheet reinforced free-standing, flexible and β-phase abundant PVDF/ZnO composite membranes are fabricated by simple, low-cost and scalable chemical method. The ferroelectric properties of the PVDF polymer based composite membranes are modified through incorporation of small amount of GO and ZnO without sacrificing the mechanical flexibility as evidenced by electrical polarization characteristics. The ferroelectric polarization for PVDF/ZnO and PVDF/ZnO/GO membranes are respectively 15.98 and 14.14 μC/cm2 at only 15 kV/cm electric field which are distinctly superior than PVDF-copolymer and PVDF-perovskite based composites as reported recently. Furthermore, as per our knowledge for the first time we have studied the effects of external electric field on dielectric relaxation times originating from the electrical responses from core grains and grain-boundary or interfaces by using dc bias dependent impedance spectroscopy. The modulation in dielectric permittivity of the composite membranes is attributed to the formation of complete β-crystalline phase in PVDF/ZnO/GO membranes and introduction of active interfaces facilitating induced electrical polarization. These studies provide significant insight into the interfacial effects on the electrical transport, ferroelectric and dielectric properties of tri-phase PVDF/ZnO/GO polymer membrane, an emerging energy material.

Nonlinear optical absorption properties of tellurium glasses containing different network modifiers

Linear- and nonlinear-optical absorption and carrier dynamic properties of binary tellurite glasses modified with different amount of WO3, Nb2O5, and ZnO were investigated via UV–Vis spectrophotometer, open aperture Z-scan and pump-probe techniques. Glasses were synthesized using conventional melt quenching technique. The vitreous nature of the samples were confirmed by conducting XRD measurements. The studied glasses have got absorption spectra similar to that of the semiconductor materials and it is found that the absorption edges of the samples blue-shifted with the changing amount and the type of the network modifier. Nonlinear absorption measurements of samples were carried out using a laser source with 532 nm wavelength, 10 Hz repetition rate and 4 ns pulse duration. All of the samples showed nonlinear absorption behavior. The transmission pump-probe spectroscopy experiments were carried out to investigate the ultrafast carrier dynamics of studied glasses with the help of Ti:sapphire laser amplifier optical parametric amplifier system with 100 fs pulse duration. The experiments were established by excitation of glasses with 400 nm pump and 500 nm probe lights. The results of the measurements indicated that the two-photon absorption and two-photon assisted free carrier absorption mechanisms are responsible for the nonlinear optical processes. In the light of obtained linear and nonlinear optical results, it can be easily concluded that these glasses are very useful for LED, optical amplifier, data storage, and laser host applications

Synthesis of a chiral metal-organic framework using zinc oxide as zinc source for enantioselective adsorption of 2,2'-furoin racemate

Chiral metal-organic frameworks (CMOFs),[Zn(L-mal)(H2O)2]n were prepared by using zinc oxide instead of the traditional metal inorganic salt as the zinc source, and their chiral separation performance was investigated. Equal amounts of ZnO and L-malic acid were dissolved in H2O, and[Zn(L-mal)(H2O)2]n were obtained by allowing the mixture to stand at room temperature for 24 h. Then, 100 mg[Zn(L-mal)(H2O)2]n as the adsorbent was added to 250 μL 1 g/L 2,2'-furoin racemate, and 4.5 mL isopropanol and 1 mL methanol were selected as the extraction solvent and elution solvent, respectively, for selective adsorption experiments. The final filtrate was analyzed by high performance liquid chromatography (HPLC). The results showed that[Zn(L-mal)(H2O)2]n exhibited better selective adsorption ability for R-2,2'-furoin with 20% enantiomeric excess (ee). This work provides a new method for the green preparation of CMOF and expands its application in the field of chiral separation.

Photocatalytic decolorization of mercuric picrate in the presence of zinc oxide

Objectives: This study was undertaken to examine the decolorization of mercuric picrate with ZnO as a photocatalyst. Methodology: The photo catalytic decolorization of mercuric picrate in the presence of heterogeneous semiconductor in the aqueous solution has been investigated. The progress of the reaction was checked by Shimadzu 1600 UV visible spectrophotometer at different time intervals. The effect of various operational parameters was studied such as the effect of mercuric picrate concentration, amount of photo catalyst, effect of light intensity, effect of band gap and effect of pH on the solution of mercuric picrate. The study on the effect of radial quenchers such as methanol and ethanol were used. Findings: The optimum conditions were obtained as pH =5.0, [Hg-picrate] = 6 ×10-5 M, amount of ZnO = 250 mg, light intensity =7.61 mWcm-2. The rate constent ontained was k= 7.30 × 10-3 min-1. The reaction proceeded through oxidation by hrdroxyl radial confirmed by scavenger. Zinc oxide is effective photocatalyst for decolorization of Hg-picrate. Other semiconductors like ZnS, CdS as well as PbS are not capable to carry out photoreaction. A tentative mechanism for this reaction has been proposed. Novelty: Mercuric Picrate is a probably explosive toxic substance. Hence a safe way to decompose this molecule into smaller and nonexplosive ways is of crucial importance. Photocatalysis is well established method. However, decomposition of mercuric picrate to a safe level can be achieved by this method. Keywords: Advanced oxidation processes; decolorization; Zinc oxide; mercuric picrate

Photocatalytic degradation of a typical neonicotinoid insecticide: nitenpyrum by ZnO nanoparticles under solar irradiation.

The photodegradation and mineralization of the nitenpyrum [(E)-N-(6-chloro-3-pyridylmethyl)-N-ethyl-N'-methyl-2-nitrovinylidenediamine], which is one of the most popular neonicotinoid insecticides, were conducted in the presence of ZnO photocatalyst under solar irradiation. An initial nitenpyrum concentration of 10ppm was completely degraded in the presence of ZnO after 30 min irradiation, while only 70% degradation was observed in the absence of ZnO. The effect of different parameters, for example, amount of ZnO, initial pH, light intensity, reaction temperature, and irradiation time, on the photocatalytic degradation of nitenpyrum was also evaluated. The drop of total organic carbon (TOC) as a consequence of mineralization of nitenpyrum was observed during the photocatalytic process. The kinetics of photocatalytic degradation followed a pseudo-first order law according to Langmuir-Hinshelwood model, and the rate constant is 0.140min-1. CO2, chloride, and nitrate ions were observed as the end-products after completing degradation of nitenpyrum. The four kinds of intermediate products were identified by GC-MS during the decomposition of nitenpyrum. In order to investigate the degradation pathway of nitenpyrum, the point charge and frontier electron density at each atom on the molecule were determined using molecular orbital (MO) stimulation. The degradation mechanism was proposed, based on the identified intermediates. The solar photocatalytic degradation method can become an effective technique for the treatment of nitenpyrum-polluted water.

CO2/CH4 mixed gas separation using poly(ether-b-amide)-ZnO nanocomposite membranes: Experimental and molecular dynamics study

Poly (ether-b-amide) (PEBA) mixed matrix membranes (MMMs) filled by different amounts of nano ZnO (up to 1 wt %) were synthesized and their gas separation performance was evaluated for CO2, CH4 and N2 pure gas and their binary mixtures. The ZnO-filled PEBA MMMs were characterized using ATR-FTIR, FESEM, AFM, TGA, DMTA, XRD and Mechanical tensile strength analyses. Generally, it was revealed that 0.5 wt % loading of ZnO into the polymer matrix caused a ZnO−PEO interaction; while ZnO–ZnO self-association hindered the interaction for the MMMs with other loadings of ZnO. As a result, PEBA-ZnO 0.5 wt % MMM possessed a higher glass transition temperature (Tg). Therefore, the CO2 permeability through PEBA-ZnO 0.5 wt % enhanced 27% than simple PEBA membrane. Moreover, all the fabricated MMMs were simulated by molecular simulation. Grand Canonical Monte Carlo (GCMC) and Molecular Dynamics (MD) methods were also applied to simulate the structural and gas transport properties of the membranes. The RDF, XRD, Tg, FFV and density analysis were compared with experimental results. Also, a binary mixture of CO2:CH4 (10:90) was used to determine CO2 permeability and CO2/CH4 selectivity, which were considerably reduced compared to single gas experiments. Moreover, the solubility of the binary gas mixture, the energy distribution and density distribution of both gases within the simulated cell were calculated by molecular simulation.

Heat Transfer Evolution Process in Hearth Based on Blast Furnace Dissection

The abnormal erosion of hearth refractories is widely recognized as the main limiting factor for a long blast furnace life. In this paper, the embrittlement phenomenon of the hearth lining found in the blast furnace dissection has been described. Combining the migration figure of the thermocouple temperature in the blast furnace hearth, the evolution process of the carbon brick erosion and the heat transfer were analyzed. The results show that the embrittlement layer contains a large amount of ZnO, which accounts for more than 40%, and the thermal conductivity of the embrittled carbon brick is about 4.9 W/(m K). Moreover, due to the detachment of the embrittlement layer, the erosion evolution process of the hearth carbon brick exists as a cyclically periodic rising phenomenon together with the thermocouple temperature. Thereafter, the residual thickness of the carbon bricks and the temperature of the thermocouples during the formation of the embrittlement layer and the protective layer were calculated quantitatively.