Zinc Oxide Powder Research Articles

Surface coated ZnO powder as flame retardant for wood: A short communication

In the present study, the ability of a coating of zinc oxide (ZnO) powder to improve the fire-safety of wood exposed to radiative heat flux was examined, focusing on the ignition time of the wood. To test ZnO's efficiency on the wood substrate, two different amounts of ZnO (0.5 and 1 g ZnO per dm2) were applied to the wood surface and exposed to radiative heat from a cone calorimeter wherein a pristine piece of wood with no ZnO treatment was taken as control. The experiments were conducted at three different irradiation levels i.e., 20, 35, and 50 kWm−2. The results showed that applying ZnO on the surface of the wood significantly increased the ignition time (TTI). For the three different heat fluxes, using 0.5 g ZnO per dm2 coating on the wood surface increased the TTI by 26–33 %. Furthermore, the application of 1 g of ZnO per dm2 generated a TTI increment of 37–40 %. All three irradiation levels showed similar trends in TTI. The micrographs taken before and after combustion showed no significant disparity in the morphology of ZnO. The agglomerated ZnO particles on the wood surface remained intact after combustion. This study demonstrates a facile method of using ZnO to delay the ignition of wood. This could potentially impart fire-safety to wooden structures/façades in wildland-urban interfaces and elsewhere by reducing flame spread.

<i>In Situ</i> Synchrotron High-Pressure X-ray Analysis for ZnO with Rocksalt Structure

Zinc oxide (ZnO) with a rocksalt crystal structure is attractive because of the bandgap which lies in the range of visible light absorption (1.2-2.6 eV). However, the rocksalt structure is not stable at ambient pressure and temperature according to an equilibrium phase diagram. Nevertheless, this study demonstrates, for the first time, that it is possible to realize a 100% fraction of the rocksalt structure at ambient pressure and temperature. ZnO powder is initially processed by severe plastic deformation under high pressure through a technique of high-pressure torsion (HPT). The HPT-processed ZnO is then examined using a high-pressure application system available at BL04B1 of SPring-8 and in situ X-ray diffraction (XRD) analysis is conducted under high pressures at elevated temperatures. It is shown that the initial presence of the rocksalt structure produced by the HPT process is effective to attain a 100% fraction of the rocksalt structure.

PVA Nanofibers Embedded with Different Concentration of ZnO Prepared by Electrospinning Method

Polyvinyl alcohol (PVA) nanofibers were fabricated using the electrospinning method. The nanofibers were embedded with zinc oxide (ZnO) particles by mixing PVA liquid with the ZnO powders during the solution preparation stage. The FESEM images showed an increase in the amount of ZnO particles embedded in the PVA nanofibers as the powder content was increased. Other than that, there are no significant changes in other physical properties of the nanofibers caused by the increasing number of ZnO particle content. This means that ZnO nanopowders (with concentration in the range of 1.63 wt% - 8.14 wt%) can be effectively integrated and embedded into PVA nanofibers without negative consequences on the fibers formation and structure. This will facilitate the fabrication of ZnO embedded PVA nanofibers in some applications that may require it such as drug delivery, filtration, and biomedical application.

Influence of non-magnetic ions doping on structural, morphological, optical, and magnetic properties of nanocrystalline zinc oxide powders

In this research study, nanocrystalline non-magnetic ion-doped zinc oxide powders are synthesized through sol-gel auto combustion with a variety of different ions (Mg, Al, and Ca) at a range of concentrations (0, 5%, 10%, 20% mol). X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), filed-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray photoelectron spectrometer (XPS), UV–visible diffuse reflectance spectroscopy (UV-DRS), photoluminescence spectroscopy (PL), and vibrating sample magnetometry (VSM) were then used to investigate the calcined products, whereupon the structures, chemical bonds, surface texture, chemical composition, morphologies, particle size, surface elemental composition, electronic state, optical and fluorescence properties including magnetism were reported for each of the samples. From XRD it could be determined that the introduction of minuscule quantities of magnesium and calcium ions to the zinc oxide powder produced solutions of hexagonal solid MgZnO and CaZnO, while composites of Mg/ZnO, CaO/ZnO, Al2O3/ZnO could also be observed, without impurity phases. Textural properties of these modified samples observed from SEM, FE-SEM, and TEM were superior to that of the pure ZnO. XPS studies confirmed the substitution of Zn2+ by Mg2+ and Ca2+ for the samples of low doping concentration. UV-DRS analysis showed that samples which had been optimally modified exhibited improved levels of absorption when compared to visible spectral observations of the pure sample. In comparison to the pure sample, the modified samples also showed higher bandgap energy (Eg). In the pure sample, violet and blue emission bands were seen in the PL spectra ranging from 350 to 430 nm, but these emissions showed significant changes in intensity as the concentration of non-magnetic ions was increased. Furthermore, VSM results revealed that diamagnetism of zinc oxide can be adjusted through the introduction of non-magnetic ions to paramagnetism and ferromagnetism.

Sunlight-Driven Degradation of Alprazolam and Amitriptyline by Application of Binary Zinc Oxide and Tin Oxide Powders

In recent years, much attention has been paid to pharmaceuticals as potential toxic bioactive substances in the worldwide environment. These compounds are continuously introduced into the surroundings in small concentrations, which certainly affects the quality of water, ecosystem, and the general health of living organisms. Photocatalysis is a promising technique for treating pharmaceutically active compounds as organic pollutants over traditional technologies. This study proposes the application of photocatalysts composed of zinc oxide (ZnO) and tin oxide (SnO2), synthesized using a solid-state method, for the photocatalytic degradation of two selected psychoactive drugs, amitriptyline (AMI) and alprazolam (ALP), under simulated solar and UV irradiation in an aqueous system. The newly synthesized photocatalysts were characterized using the following techniques: SEM/EDS, XRD, DLS, and UV/Vis spectroscopy. The obtained data confirmed the successful synthesis and the possible photocatalytic application of the new materials. Concerning the photocatalytic evaluation, the main results indicate that the highest removal efficiency of AMI and ALP was reached in the presence of ZnO/SnO2 synthesized in a molar ratio of 2:1 and calcined at 700 °C, under 1.0 mg/mL catalyst loading. Based on the reutilization findings, it can be concluded that the mentioned photocatalyst had not lost its efficiency after three successive runs for the photodegradation of ALP. Additionally, pure ZnO powders showed the highest activity after calcination at 500 °C, in the case of both examined pollutants. The experiments with tert-butanol, sodium fluoride, and ethylenediaminetetraacetic acid suggested that the relative contribution of various reactive species changed in the following order: positively charged holes > OHfree• > OHads•.

Photocatalytic Bleaching of Fast Green in Presence of Zinc Oxide as Photocatalyst

Abstract: The photocatalytic bleaching of Fast Green on zinc oxide powder has been carried out in presence of light. The photocatalytic bleaching of dye was observed spectrophotometrically. The effect of variation of different parameters like concentration of Fast Green, pH, amount of zinc oxide, and light intensity on the rate of photocatalytic bleaching was observed. A tentative mechanism for the photocatalytic bleaching of Fast Green has been proposed.

Effect of feedstock solution concentration on the spectroscopic and electrical transport properties of thermal plasma synthesized ZnO nanoparticles

The structural, optical, spectroscopic, and electrical transport properties of zinc oxide (ZnO) nanoparticles prepared using the solution precursor plasma spray (SPPS) technique were investigated for different feedstock solution concentrations such as 1-mol and 4-mol. Rietveld refined powder X-ray diffraction and Raman spectra reveal that the prepared ZnO crystallizes in a hexagonal wurtzite structure with no secondary phase. The crystallite sizes for 1-mol and 4-mol samples are 27.5 nm and 31.3 nm, respectively. Analysis of UV–vis spectra shows that ZnO's band gap has increased from 3.19 eV to 3.23 eV as the mole concentration has increased. The spherical nature and nano size of the ZnO are confirmed by the pictures obtained using field emission scanning electron microscopy (FE-SEM) and transmission electron microscope (TEM). The presence of elements zinc and oxygen in the Zn2+ and O2− ionic states are revealed by X-ray photoelectron spectroscopy (XPS). Electrical study demonstrates that the initial mole concentration of ZnO powder affected both its electrical conductivity and dielectric constant. The activation energy value of electrical conductivity for 1-mol and 4-mol is 0.661 eV and 0.552 eV, respectively. The impedance analysis shows the electrode effect for the 1-mol sample whereas it is not observed for the 4-mol sample, which is further confirmed by modulus analysis. The presence of defect in the 1-mol sample results in a lower conductivity (3.68 × 10−12 S/cm at 1 Hz) than the 4-mol sample. The comprehensive analysis confirms that the structural, spectroscopic and electrical properties of the ZnO nanoparticle can be tunable to meet demand by changing the feedstock mole concentration in the SPPS process.

Synthesis of crossed twin disks of ZnO and its growth mechanism

Crossed twin disks of zinc oxide were fabricated by the vapor-phase transport method using a mixture of zinc oxide, indium oxide, and graphite powders as the source materials. The obtained nanostructure consisted of two crossed hexagonal disks, where the size of the disks was about 2.5 μm in diagonal and 300 nm in thickness. XRD result indicated that the as-obtained samples were well-crystallized wurtzite hexagonal ZnO nanostructures. Photoluminescence (PL) properties of the ZnO microdisks was characterized by fluorescent spectroscope with 250 nm picosecond LED. In the proposed growth mechanism, indium played the role of the doping element in the formation of special nucleation habits, which led to the crossed growth of the nanodisks. It is anticipated that this type of ZnO nanodisks would have application potentials in various types of nanodevices, such as light emitters and sensors, information storage devices, transducers, etc.

Poly(acrylic acid-co-2-acrylamido-2-methyl-1-propanesulfonic acid)-grafted chitosan hydrogels for effective adsorption and photocatalytic degradation of dyes.

As a result of the growth of industrialization and urbanization, the water ecosystem is contaminated by various pollutants, including heavy metal ions and dyes. The use of low-cost and environmentally friendly dye adsorbents has been investigated. A hydrogel was fabricated via graft polymerization of acrylic acid (AA) and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) onto chitosan. The hydrogel was used as a dye adsorbent and support for a zinc oxide (ZnO) powder photocatalyst. The adsorption capacity of the bare hydrogel was greater towards cationic dyes than anionic dyes. Grafting P(AA-co-AMPS) exhibited a 23-time increase in adsorption capacity towards crystal violet (CV) compared to pristine chitosan. The effect of the AA-AMPS molar ratio on CV adsorption was studied. A hydrogel with an AA-AMPS ratio of 10 : 1 had the highest adsorption capacity towards CV in water, removing 91% of the dye in 12 h. The maximum adsorption capacity was 2023 mg g-1. The adsorption kinetics and isotherm were described by the pseudo-second-order model and the Langmuir model, respectively. ZnO particles were in situ synthesized within the 10 : 1 hydrogel to facilitate the recovery of the photocatalyst. The ZnO hydrogel composite could remove 95% and 92% of CV from solutions on the 1st and 2nd cycle, respectively. In addition, the hydrogel composite containing only 8.7 wt% of ZnO particles effectively degraded adsorbed CV under sunlight and could be reused without requiring a chemical regeneration or photocatalyst recovery procedure. This hydrogel composite is an effective dual-functional material for the adsorption and photodegradation of dye pollutants in wastewater.

Получение высокодисперсного порошка оксида цинка путем сжигания смеси нитрата цинка с глицином и его применение для фотокаталитического разложения фенола

The paper presents the results of a detailed study of the process and products of combustion during self-propagating high-temperature synthesis (SHS) of ZnO zinc oxide powder from mixtures of such common reagents as oxidizer zinc nitrate and reducing agent (fuel) glycine, as well as the application of synthesized highly dispersed submicron and nanosized ZnO powder for the phenol photocatalytic decomposition under the action of ultraviolet irradiation. An aqueous solution of a mixture of reagents (the SHS-S process or Solution Combustion Synthesis – SCS) and the gel from a mixture of initial dry reagents formed when they were moistened due to hygroscopicity (the SHS-G process or Gel Combustion Synthesis – GCS) were combusted. The authors studied the phase and chemical compositions, the structure of the combustion product, and the effect of calcination in an oxidizing air medium and grinding in drum ball and planetary-centrifugal mills, as well as in mortar, on them and their photocatalythic activity. The study showed that calcination considerably increases the photocatalytic activity of combustion products due to a significant decrease in carbon impurity in the unburned fuel remains, and grinding in mills reduces the photocatalytic activity due to iron contamination and coarsening of ZnO particle agglomerates. The difference between the photocatalytic activity of the SHS-G and SHS-S products in the phenol decomposition is evident only at the initial stage of ultraviolet irradiation, after which this difference disappears. The authors discuss the direction of further research to increase significantly the photocatalytic activity of zinc oxide synthesized during combustion to use it effectively for the phenol decomposition under the action of visible light.

Synthesis, Characterization, Optical and Thermal Properties of P(NVC-co-BZMA) Copolymer and Its ZnO Composites

Recent studies have paid particular attention to polymer-nanoparticle composite materials considering they have a number of interesting properties, which include optical, thermal, electrical, and others (Reyna-Gonzalez et al., 2009; Yakuphanoglu et al., 2010). In this study, a free radical polymerization process was used to create a copolymer of N-vinylcarbazole (NVC) and benzyl methacrylate (BZMA) at 25–75 mol% each. The procedure was conducted at 70°C with azobisisobutyronitrile (AIBN) acting as the initiator. Nano zinc oxide powders were then added to composites at three different ratios of 5%, 10%, and 15% weight of the copolymer. In order to better understand the structures of the P(NVC-co-BZMA) and its composites, FT-IR, 1H NMR, and UV spectroscopic techniques were also implemented. The optical characteristics of both the pure copolymer and its composites were examined. In the visible region, the composite containing 15% nano ZnO had the highest optical absorbance value. Additionally, the thermal behaviours of the composites and copolymers were analysed.

Influence of the Sintering Temperature of Zinc Oxide Powder on the Varistor Properties of Structures Based on It

The manufacture of varistors by chemical synthesis is a promising scientific direction. Among the methods of chemical synthesis, the sol-gel method stands out especially, it has an advantage over the classical method due to a more homogenous distribution of ZnO grains and does not require high sintering temperature, moreover, unlike most chemical synthesis methods, it is much cheaper and environmentally friendly. The main purpose of this work is the synthesis of ZnO powder by the sol-gel method, followed by the manufacture of varistor structures and the study of the dependence of their parameters on the sintering temperature and operating temperature. During the work, ZnO powder was synthesized by the sol-gel method, with further fabrication of varistor structures, at sintering temperatures of 1000 °C and 1100 °C. The structure of instrumental samples was studied by scanning electron microscopy, and the current-voltage characteristics were also measured in the temperature range of 20—200 °C. The non-linearity coefficients of the current-voltage characteristic at 20 °C and the temperature coefficient of resistance were calculated. Thus, for the sample sintered at 1000 °C, the coefficient of non-linearity was 1.973 and the temperature coefficient of resistance was 0.649, and for the sample which was sintered at 1100 °C, the coefficient of non-linearity was 1.142 and the temperature coefficient of resistance was 1.0428. These results which were obtained during the work allow us to speak about an increasing in the degree of development of interfaces with the increase in the sintering temperature in turn.

A New Approach for the Synthesis of Powder Zinc Oxide and Zinc Borates with Desired Properties

Zinc borates are widely used in industry due to their thermal stability as a flame retardant in the production of plastics, rubber, and other polymer compositions. We have developed a simple and effective approach for the synthesis of zinc borate powders with desired properties, including desired particle size, low bulk density, high reactivity, etc. Zinc borates were prepared by the thermal treatment of a concentrated water–carbohydrate solution of a zinc salt until finely dispersed ZnO was formed, followed by its hydrothermal treatment at 90–300 °C as part of a suspension based on a hot aqueous solution of H3BO3. According to X-ray powder diffraction, IR spectroscopy, and TG–DSC data, depending on the temperature of hydrothermal treatment, a decrease in the water content in the structure of synthesized zinc borate particles is observed. TEM and SEM data indicate the formation of isometrically shaped zinc borate particles in the nanometer range during hydrothermal treatment above 250 °C. Varying the temperature of the hydrothermal treatment affects the average size and fineness of the structure of the zinc borate particles.

Performance optimization of CuO-ZnO ceramic electrode on the electrocoagulation of wastewater

Copper oxide (CuO) and zinc oxide (ZnO) were used as a matrix and reinforcement in the compression molding technique to produce conductive ceramic electrodes. CuO-ZnO-based ceramic composites were fabricated through conventional pressing with CuO:ZnO ratios of 75 %:25 %, 80 %:20 %, 85 %:15 %, 90 %:10 %, and 95 %:5 %. CuO and ZnO powders were sieved, dried, mixed, and thencompressed at 300 MPa for 10 min to form a pellet before being burned for 3 h at 800, 900, and 1000 °C in a furnace. The sample's density, porosity, and electrical conductivity were measured. In addition, SEM, XRD analysis, and palm oil wastewater electrocoagulation were carried out. The optimal density value of CuO-ZnO-based ceramic composites ranged from 8.564 × 103 to 9.205 × 103 kg m−3. The optimal composition of the CuO:ZnO in the synthesized composites, namely 95 %:5 %, yielded the lowest porosity values (12.1 %-35.4 %), while the 75 %:25 % composition produced the highest porosity values (20.8 %–88.3 %). The optimum porosity value (12.1 %) was obtained by CuO:ZnO composite composition of 95 %:5 % with a sintering temperature of 1000 °C. This composite also generates a conductivity value of 1.019–16.897 S/m. The interaction of Zn2+ ions from ZnO crystals with CuO crystals increases the size of CuO and ZnO crystals, as determined by XRD analysis. Based on the findings of this study, CuO-ZnO ceramic electrodes could be utilized in industrial wastewater treatment as the water quality test result met the requirements of Minister of Environment Decree No. 51/MENLH/10/1995.

Cold Sintering Process of Zinc Oxide Ceramics: Powder Preparation and Sintering Conditions Effects on Final Microstructure

Although the activating effect of an acetate medium in the cold sintering process of zinc oxide ceramics is well known, some problems need to be solved on the effect of process conditions and the initial powder’s preparation methods on the ceramic’s density and microstructure. This article describes an effect of the zinc acetate introduction method, its concentration in zinc oxide powder as well as that of the die sealing configuration on the density and microstructure of zinc oxide ceramics obtained by the cold sintering process at 244 °C. The activating additive of zinc acetate was applied in two ways: (1) impregnation in aqueous solution and (2) impregnation with subsequent treatment in water vapor. Zinc oxide powders and ceramics were analyzed using SEM, TGA/DSC/MS and XRD to reveal the effect of powder pre-treatment and sintering conditions on the material microstructure. Cold sintered ZnO ceramics samples with a relative density up to 0.99 and with average grain sizes from 0.28 to 1.71 μm were obtained. The die sealing by two Teflon sealing rings appeared to be the most effective.

The Solution Combustion Synthesis of ZnO Powder for the Photodegradation of Phenol

Nanoscale and submicron powder of zinc oxide (ZnO) is known as a highly efficient photocatalyst that is promising for solving the problem of wastewater treatment from toxic organic pollutants including phenol and its derivatives. The results of laboratory studies of ZnO preparation by a simple, energy-saving, and highly productive method of solution–combustion synthesis from a mixture of solutions of zinc nitrate and glycine, as well as the use of the ZnO powder synthesized by combustion for the photocatalytic decomposition of phenol, are presented. The modes and characteristics of combustion, phase composition, chemical composition, and structure of the combustion product at different ratios of glycine with zinc nitrate were determined. It is shown that calcination at 650 °C reduces the content of carbon impurity in the combustion product to ~1 wt.% and leads to obtaining ZnO powder in the form of porous agglomerates up to 100 μm in size sintered from crystalline nanoscale and submicron ZnO particles with an average crystallite size of 44 nm. The ZnO powder exhibits high photocatalytic activity, leading to the almost complete degradation of phenol in an aqueous solution under the action of ultraviolet irradiation in less than 4 h.

Precursor mediated and defect engineered ZnO nanostructures using thermal chemical vapor deposition for green light emission

We used thermal chemical vapour deposition to synthesize zinc oxide nanostructured thin films on n-type silicon substrate using zinc oxide (ZnO) and zinc chloride (ZnCl2) powder precursors in conjunction with bulk graphite powder. The synthesized ZnO nanostructured thin films structures are polycrystalline with a relatively enhanced c-axis orientation for ZnO powder precursor with respect to that of ZnCl2 precursor. The scanning electron microscopic analysis substantiate the higher c-axis orientation of ZnO nanostructures, grown using ZnO powder precursor. The photoluminescence (PL) and UV–Vis measurements suggest the presence of zinc vacancies, causing the green emission from both nanostructured thin films. The measured bandgap of ZnO nanostructured thin film using ZnO powder precursor is slightly higher than that of ZnCl2 powder precursor. The capacitance-voltage and Mott-Schottky measurements showed the n-type characteristics with 6.3 × 1016 cm−3 and 2.7 × 1015 cm−3 carrier densities for ZnO nanostructured thin films prepared using ZnO and ZnCl2 precursors, respectively. The current-voltage measurements showed relatively lower current for ZnO nanostructured thin films, synthesized using ZnCl2 precursor, signifying the presence of zinc vacancies trap sites and is also consistent with Mott-Schottky measurements, showing lower carrier concentrations with respect to that of ZnO precursor derived ZnO nanostructured thin films. Thus, controlled Zn vacancies in ZnO nanostructured thin films may lead to the efficient green light emitters, useful for green light colour emission applications.

Investigation of mechanical properties and antibacterial behavior of WE43 magnesium-based nanocomposite

The aim of this study is to develop a biodegradable magnesium-based nanocomposite with enhanced mechanical and antibacterial properties. To achieve this goal, nano- and micro-scale zinc oxide (ZnO) and copper-zinc oxide (Cu/ZnO) reinforcements were incorporated into WE43 magnesium alloy, as the matrix of the nanocomposite. High purity ZnO and Cu/ZnO were synthesized by solution combustion with citric acid fuel using conventional and microwave heating, resulting in nanometer and micrometer particles, respectively. Friction stir processing (FSP) was employed to develope the magnesium-based composites. ZnO and Cu/ZnO powders were implemented into the WE43 base plate with either drilling holes or machining grooves. Hole-inserted additives resulted in more uniform particle distribution than groove-inserted ones. In addition, nanoscale ZnO and Cu/ZnO particles showed more uniform distribution compared to microscale ZnO. The addition of Cu/ZnO particles yielded the highest level of antibacterial activity, compressive strength and micro hardness of the composite. The antibacterial performance of the composite was in line with the fact that Cu/ZnO powder showed more pronounced antibacterial properties than ZnO powders. In addition, groove-inserted Cu/ZnO composite showed compressive strength of 527 MPa and hardness of 90.7 Hv, which were significantly higher than the values of 300 MPa and 78.7 Hv obtained for groove-inserted ZnO composites. It should be noted that the un-processed monolithic WE43 alloy had a compressive strength of 138 MPa and hardness of 66.8 Hv.

Producing high-purity zinc oxide for photonics technologies

The authors developed a procedure for synthetizing high-purity zinc oxide by precipitation from a solution with the subsequent high-temperature treatment in oxygen. Metallic zinc additionally purified by vacuum distillation, nitric acid and aqua ammonia with total impurities not exceeding 10–4 % wt. were used as incoming substances for the synthesis. It is found that to produce a single-phase product as zinc oxide powder containing no nitrate and amine complexes, the precipitation should be conducted at a zinc concentration in solution of 2 mol/l and pH = 7.5. Impurities of iron, chromium, aluminum, barium, molybdenum and sodium are removed at the stage of forming the intermediate precipitate at pH = 5. The yield of the final high-purity product is 59%. A scanning electron microscopy method was used to study precipitate morphology before high-temperature annealing and after it. It is shown that the final product is powder formed from well-faceted crystallites represented by hexagonal prisms, 0.5–0.7 μm in diameter and 1.7–2.1 μm in length. The analysis of luminescence spectra indicated that synthetized and purified ZnO after high-temperature annealing showed low luminescence with a maximum value of 678 nm, while commercial ZnO powder was characterized by intensive luminescence with a maximum value of 522 nm, attributed to defects of non-stoichiometry and/or yttrium impurities. Chemical purity of zinc oxide synthetized and purified according to the developed procedure, as shown by inductively coupled plasma mass spectrometry, was 99.9993 % wt. by 67 impurity elements.The authors acknowledge K. I. Runina, an employee of the Department of Chemistry and Technology of Crystals, for her help with spectral studies.The research was conducted as part of funding applied research project of Mendeleev University of Chemical Technology of Russia No. ВИГ 2022-081.

Unchanged pulmonary toxicity of ZnO nanoparticles formulated in a liquid matrix for glass coating

The inclusion of nanoparticles can increase the quality of certain products. One application is the inclusion of Zinc oxide (ZnO) nanoparticles in a glass coating matrix to produce a UV-absorbing coating for glass sheets. Yet, the question is whether the inclusion of ZnO in the matrix induces toxicity at low exposure levels. To test this, mice were given single intratracheal instillation of 1) ZnO powder (ZnO), 2) ZnO in a glass matrix coating in its liquid phase (ZnO-Matrix), and 3) the matrix with no ZnO (Matrix). Doses of ZnO were 0.23, 0.67, and 2 µg ZnO/mouse. ZnO Matrix doses had equal amounts of ZnO, while Matrix was adjusted to have an equal volume of matrix as ZnO Matrix. Post-exposure periods were 1, 3, or 28 d. Endpoints were pulmonary inflammation as bronchoalveolar lavage (BAL) fluid cellularity, genotoxicity in lung and liver, measured by comet assay, histopathology of lung and liver, and global gene expression in lung using microarrays. Neutrophil numbers were increased to a similar extent with ZnO and ZnO-Matrix at 1 and 3 d. Only weak genotoxicity without dose-response effects was observed in the lung. Lung histology showed an earlier onset of inflammation in material-exposed groups as compared to controls. Microarray analysis showed a stronger response in terms of the number of differentially regulated genes in ZnO-Matrix exposed mice as compared to Matrix only. Activated canonical pathways included inflammatory and cardiovascular ones. In conclusion, the pulmonary toxicity of ZnO was not changed by formulation in a liquid matrix for glass coating.