جستجوی مقالات مرتبط با کلیدواژه « zno nanoparticles » در نشریات گروه « شیمی »

The evaluation of the Aluminum alloy 1050 as an anode in an Al/AgO battery in an aerated 6.0 M KOH solution involves studying its corrosion behavior and battery performance. Various techniques, including potentiodynamic polarization, electrochemical impedance spectroscopy, electrochemical noise analysis, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and galvanostatic discharge, are employed to assess these aspects. The polarization results reveal that the addition of various concentrations of thiourea to ZnO as the best-mixed inhibitor reduces the corrosion rate of aluminum during the initial stages from 4638.9 mpy to 1634.6 mpy. Also, this type of inhibitor leads to an increase in polarization resistance from 3.10 Ω.cm2 to 8.36 Ω.cm2, which are in good agreement with the results of impedance spectroscopy studies. Furthermore, based on the findings of EIS studies this type of inhibitor with an inhibition efficiency of more than 90.47%, facilitates the formation of a protective layer on the surface, effectively controlling the initiation and propagation of pits. As the immersion time increases, the inhibitor creates conditions where the aluminum anode corrodes uniformly, providing the necessary electrons and capacity for the battery to perform better. The SEM results also demonstrate that the corrosion of aluminum becomes more uniform, resulting in an impressive anode efficiency of 90.19% in the galvanostatic discharge test.

In this work, CuO nanoparticles (NPs), ZnO NPs, and CuO-ZnO nanocomposites (NCs) were synthesized using Citrus sinensis fruit peel extract. Then, carbon paste electrodes modified with each nanomaterial (CuO-CPE, ZnO-CPE, and CuO-ZnO-CPE) was fabricated for the electrochemical detection of hydrogen peroxide (H2O2). The prepared metal oxide nanomaterials were characterized using Ultraviolet-Visible (UV-Vis) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The average crystallite sizes for nanomaterials composed of CuO and ZnO NPs and CuO-ZnO NCs were 32.2 nm, 31.7 nm, and 35.38 nm, respectively. A carbon paste electrode modified with CuO-ZnO NCs (CuO-ZnO-CPE) was used to detect H2O2. At CuO-ZnO-CPE, a cathodic peak for H2O2 was seen at about 0.0 V. Under optimum experimental conditions, the developed electrode showed a wide linear range from 0.5 μM to 200.0 μM with a limit of detection (LOD) of about 0.32 μM. The synthesized electrode also showed increased stability, adequate selectivity, and repeatability.

In this work, a facile and fast phytosynthesis of zinc oxide nanoparticles (ZnO NPs) were reported employing an aqueous extracts of flowering shoot tips of Hypericum perforatum L. (H. perforatum). UV-Vis Diffuse reflectance spectroscopy (UV-Vis DRS), X-ray Diffraaction (XRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), Energy dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FT-IR) were applied to characterize the fabrication of ZnO NPs. TEM results show a semi-spherical shape and a size range of 14 nm for synthesized ZnO Nps and also represented UV-Vis absorption at 365 nm. The antibacterial activity of phytosynthesized ZnO NPs and the aqueous extract of H. perforatum were also measured including: zone of inhibition, Minimum inhibitory concentration (MIC) and Minimum bactericidal concentration (MBC). The bacteria examined in this study are Methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa (both of which are the most common causes of nosocomial infections), and Bacillus subtilis. Regarding the antibacterial properties of the synthetic samples, the best results were obtained with H.perforatum/ZnO NPs against B. subtilis. as follows: inhibition zone diameter at 1000 μg mL-1, 18 mm, MIC and MBC values of 39.06 μg mL-1 and 78.12 μg mL-1. Considering the favorable antibacterial activity of synthesized ZnO NPs using H. perforatum extract, they can be applied in bio-medicinal applications, particularly as nanobiotics.

A lactate biosensor has been designed for the detection of lactate in a real sample. A combination of composite material comprising of multi-walled carbon nanotubes (MWCNTs) and zinc oxide nanoparticles has been used as working electrode, which were deposited on gold (Au) wire. This was treated as working electrode for the preparation of a LDH-based amperometric biosensor along with acetyl coenzyme, which acts as the mediator to enhance electron transportation. The biosensor showed excellent results in terms of stability, response time, and sensitivity. The sensitivity of the biosensor is 4.487 mA/µM and its linearity is between 10 µM and 100 µM. The biosensor has a 0.67 µM limit of detection with a response time of 8 sec. The optimal temperature is 35°C, and the optimal pH is 8. All the results confirmed that the ZnO/MWCNTs/Au electrode, along with acetyl coenzyme, acts as a suitable matrix for the purpose of immobilizing LDH enzymes for the formation of lactate biosensors.

Nanofluids are stable suspensions of nanoparticles in a conventional fluid. They have shown superior potential in heat transfer enhancement. In this research, ZnO/water nanofluids were prepared at various concentrations from 0.2 to 1.5vol%, and their thermal conductivity was measured. The results showed that the thermal conductivity of ZnO/water nanofluids depends on particle concentration and increases non-linearly with the volume fraction of nanoparticles. The effects of particle size and temperature on the thermal conductivity were also investigated at 1.5vol%. The results indicated that thermal conductivity enhanced with decreasing particle size and increasing with temperature. For nanofluids containing 10-15 nm and 45-50 nm particle sizes, the enhancements were 26.3 and 22.8% at 40oC, respectively. In this research, the convective heat transfer coefficient of ZnO/water nanofluids with the above particle sizes was also measured under laminar flow in a horizontal tube heat exchanger. It was observed that both nanofluids showed higher heat transfer coefficients compared to the base fluid at a constant concentration (1.5 vol%). For nanofluids with 10-15 nm and 45-50 nm particle sizes, the average heat transfer coefficient enhancement was 18.1 and 14.9% at Re=1115, respectively.

Zinc oxide nanoparticles are one of the known safe compounds, and their low toxicity makes them suitable for waste water remediation. An environment-friendly approach of synthesizing nanoparticles is the use of plant extracts which are rich sources of phytochemicals as reducing agents. In this research, aqueous extracts of four different plants’ leaves were analyzed and found to contain anthocyanins, steroids, phenolics, saponins, flavonoids, and terpenoids. Optimization study prepared the precursors (zinc salt and plant extracts) in varying volume-ratios of 1:1, 1:2 and 2:1; a higher yield was observed for the ratio 1:1 having calculated percentage yields of 50.0 %, 64.1 %, 21.8 %, and 68.0 % for leaves of guava, tropical almond, lemon, and Mexican a, respectively. The TEM characterization of these biosynthesised nanoparticles have sizes in the range 0.22 nm and 5.80 nm, while the EDS spectra presented these nanoparticles as highly pure having major elements of zinc and oxygen. The small sizes and very high purity of the biosynthesised nanoparticles make them fit for adsorption applications such as waste water remediation.

Recently, with the increase in diseases caused by bacterial and viral infections, the need for antibacterial agents has widely increased. On the other hand, with the development of drug resistance to organic groups of antibiotics, new antibiotics have attracted the attention of researchers because new methods are needed to reduce the activity of bacteria. Nanotechnology is increasingly being used for medical applications and is useful as an approach to kill or reduce the activity of various microorganisms. Metal oxides are considered for medical applications, especially as antibacterial agents, due to their potential advantages and suitable nanoscale properties. In this study, the electric discharge method was employed for the preparation of the iron oxide nanoparticles (IONPs) and iron-zinc oxide nanoparticles (IZONPs). As the IONPs and zinc oxide nanoparticles (ZONPs) attack various gram-positive and gram-negative bacteria by different mechanisms, it seems that the simultaneous use of these oxides can effectively kill various bacteria in outdoor and indoor media. The synthesized nanoparticles were characterized via XRD, UV-Visible, FE-SEM, EDS, HR-TEM, and TEM techniques. The obtained results showed that the IZONPs with mean particles size between 11 and 33 nanometers have successfully been synthesized in various experimental conditions. Also, the antibacterial properties of these nanoparticles were evaluated and the particles showed antibacterial properties against both gram-positive and gram-negative bacteria.

Synthesis of widespread types of nanoparticles including metal oxides by plant extract is considered as alternative chemical synthesis methods. ZnO nanoparticles are synthesized by a biological process using flaxseeds (Linum usitatissimum L.) extract. The biosynthesized ZnO NPs were characterized by XRD and SEM, EDX, DLS spectroscopy. According to the SEM images, the synthesized nanoparticles are spherical shape with agglomeration and based on XRD, average crystallite size of the ZnO NPs is 15.45 nm.

In this work, Zinc oxide nanoparticles (ZnONPs) were utilized as a potential adsorbent for the adsorption of Reactive Blue 25 (RB25) and Reactive Blue 49 (RB49) dyes from aqueous solutions. ZnONPs adsorbent was synthesized by precipitation method and characterized using XRD, TEM, SEM, and N2 adsorption /desorption techniques. The effect of various parameters including solution pH, shaking time, adsorbent amount and initial concentration of the dyes on the adsorption efficiency was studied. The experimental adsorption data analyzed with various kinetic and isothermal methods. The adsorption kinetic study revealed that the adsorption process followed pseudo-second-order kinetic model. Additionally, adsorption isotherm studies indicated that adsorption equilibrium data were well fitted to Langmuir model and accordingly, the maximum adsorption capacity of the adsorbent for RB25 and RB49 found to be 34.36 and 34.60 (mg/g), respectively. From this study, ZnONPs is suggested as an effectual adsorbent for the removal of dyes from aqueous samples.

Cu(II) complex derived from Synthesis of N-((1H-pyrrol-2-yl)methylene)-4- methoxyaniline Schiff base(PMMA) was studied by UV-Vis, IR spectra, and EDAX. Zinc oxide was synthesized using a simple homogeneous precipitation method with zinc acetate as a starting material. The thin layer of the studied Cu(II) complex was deposited on ZnO/Si(111) substrates by a spin coating method and characterized with scanning electron microscopy (SEM), atomic force microscopy (AFM), and photoluminescence spectroscopy. The SEM images revealed that silicon surfaces are uniformly covered by the Cu(II) complex. AFM micrographs reveal that films are closely packed and granular in nature; the signature of agglomeration of grains is almost absent. For Cu(II) complex/ZnO/Si layer the most intensive fluorescence bands due to intra-ligand transitions were observed between 498 and 520 nm, the quenching of the emission band from ZnO at 360 nm (λex =320 nm) associated with various intrinsic or extrinsic lattice defects was noted.

Zinc oxide (ZnO) nanoparticles with an average size of 60 nm have been successfully prepared by microwave irradiation. Carbon paste electrode (CPE) was modified with ZnO nanoparticles and used for the electrochemical oxidation of chlorpheniramine maleate (CPM). Cyclic voltammetry (CV) study of the modified electrode indicated that the oxidation potential shifted towards a lower potential by approximately 106 mV and the peak current was enhanced by 2 fold in comparison to the bare CPE (ZnO/CPE-CV). The electrochemical behaviour was further described by characterization studies of scan rate, pH and concentration of CPM. Under the optimal conditions, the peak current was proportional to CPM concentration in the range of 8.0 ×10-7 to 1.0 × 10-3 mol L-1 with a detection limit of 5.0 × 10-7 mol L-1 by differential pulse voltammetry (DPV). The peak current of CPM is linear in the concentration range of 0.8 - 1000 µM (R2=0.998). The ZnO/CPE has good reproducibility and high stability for the determination of CPM using this electrode. The proposed method was successfully applied to the determination of CPM in pharmaceutical samples. In addition, the important analytical parameters were compared with other methods which show that ZnO/CPE-CV procedure is comparable to recently reported methods.

A streamlined and efficient method for the synthesis of 2-amino-4H-chromenes is achieved by one-pot three-component reaction of aldehydes, 2-naphthol and malononitrile in the presence of ZnO nanoparticles loaded on zeolite-Y (ZnO@zeolite-Y) as a highly active catalyst under solvent-free conditions. ZnO@zeolite-Y has been successfully prepared via hydrothermal technique and its structure was confirmed using nanoscale-like identification techniques included FT-IR, XRD, FE-SEM, EDX analyses and BET surface area measurements. The higher environmental compatibility and sustainability factors such as reusability of the catalyst as an important principle in green chemistry, use of solvent-less technique as a green synthetic approach and easy isolation of the product along with good yields, make the present protocol a true green process for the synthesis of chromenes compared to conventional methods.

Zinc oxide (ZnO) is the most common and widely utilized nanomaterial for biological applications due to their unique characteristics, such as biocompatibility, biosafety and antimicrobial along with thermal stability and mechanical strength. Magnesium (Cu) is considered as a significant dopant for ZnO due to their almost similar ionic radii and their role in biological activities which enhances the biological properties of ZnO. Thus, pure and magnesium doped nanocrystalline ZnO particles were synthesized through sol-gel approach in the current study. The concentration of the dopant is varied from (0.1% - 0.3%) and the composition, structural and optical characterizations were performed by using X-Ray Diffraction (XRD), Transmission Electron Microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy, UV-Vis optical absorption and photoluminescence (PL) spectrometer. The structural analysis confirmed that magnesium ions substitute Zn ions without altering their wurtzite structure with a high degree of crystallization. Morphological analysis confirmed that the magnesium doping process strongly influences the morphology of ZnO nanoparticles. PL measurement had been carried out at room temperature in which high intensity broad emission peaks were observed in the visible region around 450 - 700 nm that indicates the superposition of green emission bands. Thus, green photo luminescent magnesium doped ZnO nanoparticles from the current study are proposed to be highly beneficial as biosensors, photocatalysts and light-driven antibacterial agents.

The infection of Aspergillus flavus and its aflatoxin production pose a severe threat to humans, animals as well as plants life. Their inhibition using green techniques are considered as one of the important challenges. The present study outlines the antifungal activity of the ZnO nanoparticles (NPs) synthesized from lemongrass leaf extract and their effect on the mycelial growth of Aspergillus flavus and its aflatoxins production. The qualitative and quantitative analyses of aflatoxins were determined, respectively using thin-layer chromatography and spectrophotometric methods. The X-ray diffraction as well as scanning and transmission electron microscopy studies indicated the formations of hexagonal ZnO NPs having the sizes ranged between 7 and 14 nm. FTIR spectrum confirmed the formation of ZnO NPs. The ZnO NPs displayed 92.25% inhibition of the growth of A. flavus and 100% inhibition of the aflatoxins production at the concentrations of 200 µl/mL and 150 µl/mL respectively. The present biosynthetic method is a simple, cost-effective, eco-friendly, high yield, green and handy protocol capable of synthesizing ZnO NPs, which might have accomplished due to the activities of plant metabolites and phytochemicals available in the lemongrass leaves parenchyma. This study revealed that ZnO NPs have the potential to forbid the growth of A. flavus and its aflatoxins production. Hence, ZnO NPs could be used in the plant protection and as a preservative for safe storage of food commodities to prevent A. flavus contamination and aflatoxins poisoning in coming future.

In this research, a new effective photocatalyst was prepared by supporting ZnO on a Todorokite (TD). This catalyst was characterized by employing scanning electron microscopy (SEM-EDX) and X-Ray Diffraction (XRD) patterns. The optical properties of the samples were measured by diffuse reflectance spectroscopy (DRS). The purpose of using the ZnO/TD as a photocatalyst was to reduction Cr(VI), which is a pollutant in water. Experiments were carried out under different operating conditions including an initial concentration of Cr(VI), photocatalyst amounts and pH values. To optimize processes and obtain a mathematical model, the researcher used a full factorial design (with three factors at three levels). The optimal conditions were determined where the amount of photocatalyst= 200 mg L-1, pH= 2 and concentration of Cr(VI)= 15 ppm. The reduction efficiency in an optimal condition was 97.73%. The experimental results showed that kinetic was the first order and k= 0.1489 min–1.

In this paper, we report the synthesis of ZnO nanoparticles using Moringa Oleifera (Drumstick) leaves as natural precursor via precipitation method. Formation and characterization of ZnO nanoparticles was established by UV-VIS spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction. The synthesized nanoparticles have hexagonal wurtzite structure of an average grain size of 52 nm confirmed from X-ray diffraction analysis. The synthesized ZnO nanoparticles have been employed as photocatalytic agent to degrade the organic dye viz. Titan yellow under visible light by exposing the visible light for one hour. ZnO nanoparticles degraded almost 96% of titan yellow dye. We also studied the antibacterial activity and it was found that the synthesized ZnO nanoparticles have potential applications in antibacterial activity. For antibacterial studies we used Bacillus subtilis as a gram positive and Escherichia coli as gram negative bacteria.

Present study has comparatively investigated the effect of zinc oxide nanoparticles (ZnO NPs), ZnO bulk particles (BPs), and relevant metal ions (Zn2) on the tissue culture of rapeseed (Brassica napus L.) to properly evaluate the impact of ZnO NPs on callus induction. For finding the best hormonal combination for inducing callus, hypocotyl explants were cultured on Murashige and Skoog (MS) media containing different combinations of plant growth regulators. After that, hypocotyl explants were cultured in MS media containing the best hormonal combination, supplemented with four different concentrations (10, 25, 50, 100 mg L-1) of ZnO NPs, ZnO BPs, or equivalent concentrations of Zn2. Results showed that 10 mg L-1 ZnO NPs can induce callus and shoot regeneration, while the same concentrations of other treatments cannot. Callus growth was significantly retarded by 25, 50 and 100 mg L-1 of all three types of treatment in a dose-dependent manner. Under highest concentration of ZnO NPs, callus was not induced. It can be concluded that optimum concentration of ZnO NPs can be beneficial for inducing callus and/or shoot regeneration in the plant tissue culture.