CuO Particle Size Research Articles

Biogenic zinc oxide, copper oxide and selenium nanoparticles: preparation, characterization and their anti-bacterial activity against Vibrio parahaemolyticus

The present study investigates biogenic preparation of zinc oxide (ZnO), copper oxide (CuO) and selenium (Se) nanoparticles using the marine brown alga Sargassum swartzii. The prepared nanomaterials were characterized using X-ray diffraction pattern (XRD), scanning electron microscopy (SEM) equipped with energy dispersive X-ray analysis (EDAX), transmission electron microscopy (TEM) and UV–Vis diffuse reflectance spectroscopy (DRS-UV) analysis. The particle size of biogenic ZnO, CuO and Se nanoparticles was ca. 32, 32 and 21 nm, respectively. The isolation of bacterial pathogenic strain Vibrio parahaemolyticus (V. parahaemolyticus) from the diseased shrimp and virulent genes (toxR and tlh) confirmed by PCR technique. Further, the molecular characterized using 16S ribosomal RNA gene sequences and identified new strain V. parahaemolyticus strain (GRCORNICRA001). Anti-bacterial activity of biogenic nanomaterials (ZnO, CuO and Se) was investigated against isolated V. parahaemolyticus using well diffusion method and growth inhibitory assay. The minimum inhibitory concentration (MIC) was 25, 25 and 10 µg mL−1 of ZnO, CuO and Se nanoparticles, respectively. The results show that there is a strong bacterial inhibition in a dose-dependent manner. Further, SEM analysis revealed that the interaction of nanomaterials with V. parahaemolyticus, resulted in a surface tension change that leads to membrane depolarization, formation of abnormal textures such as membrane rupture, membrane blebs, membrane clumping, and also caused cell death. Results of this effort highlighted the way for the future that these nanomaterials incorporated with shrimp feed for the management of aquatic diseases.

Investigation of optical and thermal properties of CuO and ZnO nanoparticles prepared by Crocus Sativus (Saffron) flower extract

Among all the metal oxide nanoparticles, CuO and ZnO nanomaterials are very popular and showcase the tremendous properties. They can be prepared from various physical, mechanical, biological, and chemical methods. But, a biological method like the green synthesis of metal oxide nanoparticle by plant or flower extract has become more popular due to its simplicity, low cost, feasibility, and eco-friendly impact. In the present paper, we have prepared both CuO and ZnO nanoparticles by Crocus Sativus (Saffron) flower extract followed by calcination at 400 °C for 15 min. The prepared metal oxide nanoparticles were characterized by UV–visible spectroscopy to study the bandgap energy, and the value was found to be 3.52 eV for CuO and 3.4 eV for ZnO nanoparticles, respectively. The morphology of the prepared metal oxide nanoparticles was studied by scanning electron microscopy, and phase, strain, and crystallite size were investigated by using X-ray diffraction. The investigation of the thermal properties of the CuO and ZnO nanoparticles was performed by thermogravimetric and differential thermal analysis. We determined the percentage weight loss, enthalpy change, and activation energy at 6, 8, and 10 °C/min heating rates. The activation energy of CuO and ZnO nanoparticles was calculated by the Kissinger method and was found to be 13.34 and 8.86 kJ/moles, respectively. The particle size of CuO and ZnO nanoparticles was found to be 300 and 450 nm, respectively. The Fourier-transform infrared spectroscopy was performed to study the functional groups present in both the nanoparticles.

Development of functionalized CuO nanoparticles for enhancing the adsorption of methylene blue dye

Water pollution by dyes from industries is a serious environmental problem. The toxicity of dyes constitutes a great risk to the environment and human health. Due to the simplicity and cost-effectiveness of the remediation process, adsorption has been widely accepted in wastewater treatment. Recent advances in nanotechnology offer considerable advantages in wastewater treatment via the introduction of porous nanomaterials, namely, metal oxide nanoparticles, carbon nanomaterials, and nanocomposites as adsorbents. In this study, a comparison is done between the functionalised and bare nanoparticles in enhancing the adsorption activity of chitosan in adsorbing methylene blue dye. Functionalized CuO nanoparticles were synthesized and characterized by FTIR, Powder X-ray Diffraction (XRD), SEM, and XPS methods. The crystallite size of CuO particles was found to be ~10 nm. The CuO nanoparticle was then functionalized to produce CuO-EDTA and CuO-EDTA-Silane complexes. The development of such functionalized nanoparticles leads to multi-functional properties such as the ability as catalysts in the presence of sunlight for degradation of dyes as well as adsorption of dyes. The BET adsorption study of the functionalized nanoparticles revealed it has a higher surface area than the pure CuO nanoparticles. These bare and functionalised nanoparticles were then separately dispersed with chitosan and adsorption study was done separately. The functionalised nanoparticles with chitosan shows more adsorption activity.

Effect of additive on CuO-ZnO/SBA-15 catalytic performance of CO2 hydrogenation to methanol

AbstractThree kinds of porous catalysts CuO-ZnO/SBA-15 (CZ/SBA-15), CuO-ZnO-MnO2/SBA-15 (CZM/SBA-15) and CuO-ZnO-ZrO2/SBA-15 (CZZ/SBA-15) were synthesized by impregnation method with a siliceous framework mesoporous molecular sieve SBA-15. The performance of all catalysts for catalytic hydrogenation of CO2 to methanol was evaluated on a fixed bed reactor, combined with N2 adsorption-desorption (BET), X-ray diffraction (XRD), H2 temperature-programmed reduction (H2-TPR), temperature programmed desorption (H2-TPD, CO2-TPD), N2O titration, X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM) . The results show that the introduction of metal oxide in the catalyst changes the pore size and specific surface area of the SBA-15 molecular sieve support. The CuO-ZnO-MnO2/SBA-15 and CuO-ZnO-ZrO2/SBA-15 have high copper dispersion (DCu), large specific surface area (ACu), small surface CuO particle size, and easy to be reduced. Compared with the Mn-O cluster, the Zr-O cluster enhances the basic site and improves the methanol selectivity. In addition, CuO-ZnO-ZrO2/SBA-15 has the highest oxygen vacancy concentration and better catalytic activity among three catalysts. The methanol selectivity of CuO-ZnO-ZrO2/SBA-15 is 25.02%, which is 28% and 136.9% higher than those of CuO-ZnO/SBA-15 and CuO-ZnO-MnO2/SBA-15, respectively.

Effects of Basic Promoters on the Catalytic Performance of Cu/SiO2 in the Hydrogenation of Dimethyl Maleate

Continuous hydrogenation of dimethyl maleate (DMM) toγ-butyrolactone (GBL), 1,4-butanediol (BDO) and tetrahydrofuran (THF) is a promising process in industry. In this study, Cu-M/SiO2 catalysts modified by basic promoters (M = Mg, Ca, Sr, Ba, La) were prepared, and characterized by physical adsorption of N2, in situ XRD, H2-TPR, CO2-TPD. With the addition of basic promoters, the basicity of Cu-M/SiO2 catalysts was improved. The particle size of CuO on Cu-M/SiO2 catalyst was increased after modified by Mg, Ca, Sr, Ba. However, the CuO particle was decreased on the Cu-La/SiO2 catalyst. The series of Cu-M/SiO2 catalyst was applied to the hydrogenation of DMM. The addition of basic promoters increased the selectivity of GBL during the hydrogenation for the basic promoters improved the dehydrogenation of BDO to GBL in alkaline sites. Furthermore, Cu-La/SiO2 presented a higher activity in the hydrogenation of DMM, due to its higher dispersion of Cu.

Effect of additive particle size on the CuO-accelerated formation of LaFeO3 perovskite conversion coatings in molten carbonate baths

An original iron conversion coating process has been recently developed to enhance the functional properties of ferritic stainless steels for use as Solid Oxide Fuel Cell interconnects. The conversion process produces a dense LaFeO3 perovskite layer grown above a spinel oxide underlayer by an immersion treatment in specially-formulated molten carbonate baths at around 600 °C. Galvanic coupling with a coarse CuO powder added to the bath has been earlier proved to be an effective approach to significantly reduce conversion times and coating thicknesses onto a 18Cr Type K41 ferritic stainless steel substrate. Further investigations on the CuO acceleration effects on the K41 steel are reported in the present work focusing on the effect of CuO particle size on the conversion times and coating structure. Studies carried out with different concentrations and particle sizes of the CuO additive have indicated that conversion coating kinetics is strongly affected by the CuO particle size highlighting thus the fact that CuO did not fully dissolve in the carbonate bath and that galvanic coupling effects took place prevalently with CuO particles dispersed in the molten bath. Dramatic reduction in conversion times could be obtained through CuO nanoparticle additions to the bath. The shortest conversion time of <3 h was achieved by adding 6 mol% nano CuO, at 610 °C. As consequence, perovskite coatings with thicknesses well below 10 μm could be produced due to minimal substrate corrosion and spinel underlayer growth during the short conversion processes in the nano CuO-containing salt baths. This structural refinement could play an important role for improving dimensional stability and functional properties of perovskite coatings in SOFC interconnect applications.

The effects of CuO particle size on microstructure evolution of AgCuO compo-sites in plastic deformation process: finite element simulation and experimental study

The effects of CuO with different particle sizes on the microstructure evolution of AgCuO composite material during plastic deformation process were investigated by finite element (FE) analysis and experiment. The results are as follows: with the decrease of CuO particle size, the degree of radial compression and axial elongation of CuO particle cluster increase gradually, as well as the dispersion of CuO also increase. Meanwhile, the shape of CuO particles is constantly transformed from polygonal to fibrous, which makes the number of linear fibrous CuO increase continuously while bent fibrous CuO reduce gradually. By comparing the simulation and experiment results we find that there are four different typical microstructure regions, which caused by the interaction between monoclinic and cubic CuO during the extrusion process.

Re-Examination of CuO Reduction Steps and Understanding of the Factors Influencing the Cyclic Voltammetry Profile of CuO

Whether CuO reduction is one step or two steps reaction has been argued for several decades, and one step reaction mechanism is mainly supported by CuO CV (cyclic voltammetry) profile, where only one cathodic peak represents the direct reduction from CuO to Cu. However, some researchers support two steps reaction mechanism, because they observed Cu2O as intermediate with spectroscopy technique or two cathodic peaks in the CV profile. In this study, two colloid electrodes containing crystal CuO particles are electrolyzed in KCl electrolyte at −1.7 V and −1.65 V respectively, and both of the products are composed of Cu2O and Cu. The electrolysis voltage can change the weight ratio of Cu2O and Cu, and the electrolysis results firmly prove that CuO reduction is two steps reaction: CuO is reduced to Cu2O, then to Cu. Therefore, the rationality of the criterion for determining one step reaction is re-considered in this study. The experimental conditions and parameters, including CV scan rate, atom arrangement of CuO, particle size of CuO, and anions and pH value of electrolyte, are discussed in the present study, and all these factors can affect CuO reduction process, thus influencing the cathotic peaks, such as the number, shape and potential of the peaks in CuO CV profile. It could lead to incorrect conclusion,when CuO reduction steps is determined by the cathode peak without comprehensive consideration of the effect from all these factors. In another word, cathodic peak number in the CV profile sometimes is not a straightforward and appropriate criterion to determine the number of steps of CuO reduction. In addition, S2− ions is found to be an effective addtive to enhance the cyclic ability and discharge plateau of Cu alkaline battery in this study.

Dissolved organic matter reduces CuO nanoparticle toxicity to duckweed in simulated natural systems.

With increasing demand for recycled wastewater for irrigation purposes, there is a need to evaluate the potential for manufactured nanomaterials in waste water to impact crop production and agroecosystems. Copper oxide nanoparticles (CuO NPs) have previously been shown to negatively impact the growth of duckweed (Landoltia punctata) a model aquatic plant consumed by water fowl and widely found in agricultural runoff ditches in temperate climates. However, prior studies involving CuO NP toxicity to duckweed have focused on systems without the presence of dissolved organic matter (DOM). In the current study, duckweed growth inhibition was shown to be a function of aqueous Cu2+ concentration. Growth inhibition was greatest from aqueous CuCl2 and, for particles, increased with decreasing CuO particle size. The dissolution of CuO NPs in ½ Hoagland's solution was measured to increase with decreasing particle size and in the presence of Suwannee river humic and fulvic acids (HA; FA). However, the current results suggest that HA, and to a lesser extent, FA, decrease the toxicity of both CuO NPs and free ionized Cu to duckweed, likely by inhibiting Cu availability through Cu-DOM complex formation. Such results are consistent with changes to Cu speciation as predicted by speciation modeling software and suggest that DOM changes Cu speciation and therefore toxicity in natural systems.

Structural, optical, and catalytic properties of undoped and CdS doped CuO–ZnO nanoparticles

The structural, optical and catalytic properties of undoped (CuO–ZnO) and CdS doped CuO–ZnO (CdS/CuO–ZnO) nanoparticles were studied. The blue shifting of optical band gap in CuO–ZnO nanoparticles as compared to their respective bulk oxides (CuO: 1.21–1.5 eV, ZnO: 3.37 eV) was observed as 3.9 eV, while red shifting after doping of CdS was found from 3.9 to 3.7 eV. The angle of diffraction and FWHM values were used to observe crystallite phase and to calculate crystallite size (using Scherer and Williamson–Hall equations) and other parameters like strain, dislocation density and bond length of nanoparticles. The particle size of CuO–ZnO and CdS/CuO–ZnO nanoparticles using transmission electron microscopy (TEM) was found 12.54 and 6.93 nm, respectively. It was concluded that decrease in particle size cause red shifting which increase the catalytic efficiency of nanoparticles.

A multi-phase micro-kinetic model for simulating aluminum based thermite reactions

This paper presents a hierarchical multiscale approach based on a micro-kinetic model enabling to predict temperature, pressure and species generated during the thermite reaction of Al nanoparticles mixed with CuO nanoparticles. Overall, our phenomenological model integrates and combines series of complex atomistic mechanisms, e.g. diffusion and phase transformation, gas phase reactions and interphase exchange mechanisms, in particular molecular condensation, evaporation and decomposition. Thermodynamics considerations as well as Density Functional Theory (DFT) calculations are used to implement rate equations expressing the complex reactions at solid/liquid/gas interphases. We demonstrate that the model can predict the pressure–time dependence, the different phases and compositions with good accuracy at significantly low computational cost. The influence of Al and CuO particle size, compaction or density, alumina shell thickness and stoichiometry on the pressure and temperature versus time is theoretically predicted with fairly good agreement with available experimental data. A maximum pressure of 47MPa and adiabatic temperature of 3500K are obtained at high compaction, i.e. 50% of the TMD (Theoretical Maximum Density) for stoichiometric mixture, where AlO is shown to be the prevailing gaseous species. At low compaction, we highlight the role of ambient oxygen condition for which the model gives a maximal pressure of 4.2MPa for Al rich mixtures (stoichiometric ratio of 1.2).

Highly Efficient and Recyclable g-C3N4/CuO Hybrid Nanocomposite Towards Enhanced Visible-Light Photocatalytic Performance

A highly efficient visible-light-driven g-C3N4/CuO hybrid nanocomposite catalyst with different molar contents of CuO are successfully fabricated via a simple liquid phase synthesis process and applied to the degradation of Rhodamine B (RhB) solution. The results reveal that monodisperse CuO nanoparticles with a size of less than 10[Formula: see text]nm are uniformly distributed on the surface of g-C3N4nanosheets. Compared with the pure g-C3N4and CuO, the as-prepared nanocomposite displays significantly enhanced photocatalytic performance under visible-light irradiation. Attractively, the photocatalytic activities of the nanocomposite catalysts can be tuned by adjusting the molar ratio of g-C3N4and CuO. When the molar ratio reaches 2:1, the nanocomposite exhibits the highest photocatalytic activity, which can decompose RhB completely in 5[Formula: see text]min. The improved performance could be ascribed to the formation of heterostructure between g-C3N4and CuO as well as the decreased particle size of CuO, the presence of H2O2, large surface-exposure area and the suitable band position of g-C3N4/CuO nanocomposite. Interestingly, the nanocomposite shows excellent stability and recyclable property toward the photodegradation of RhB. Finally, a possible photocatalytic mechanism is proposed.

Dependence of CuO particle size and diameter of reaction tubing on tritium recovery for tritium safety operation

Usage of CuO and water bubbler is one of the conventional and convenient methods for tritium recovery. In present work, influence of CuO particle size and diameter of reaction tubing on the tritium recovery was evaluated. Reaction rate constant of tritium with CuO particle has been calculated by the combination of experimental results and a simulation code. Then, these results were applied for exploring the dependence of reaction tubing length on tritium conversion ratio. The results showed that the surface area of CuO has a great influence on the oxidation rate constant. The frequency factor of the reaction would be approximately doubled by reducing the CuO particle size from 1.0mm to 0.2mm. Cross section of reaction tubing mainly affected on the duration of tritium at the temperature below 600K. Reaction tubing with length of 1m at temperature of 600K would be suitable for keeping the tritium conversion ratio above 99.9%. The length of reaction tubing can be reduced by using the smaller CuO particle or increasing the CuO temperature.

Effect of copper precursors on the catalytic activity of Cu/ZSM-5 catalysts for selective catalytic reduction of NO by NH3

The Cu/ZSM-5 catalysts prepared by different copper precursors were used for the selective catalytic reduction (SCR) of NO x with NH3. The Cu/ZSM-5 catalyst prepared by the copper nitrate (Cu/ZSM-5-N) presented the best performance among the Cu/ZSM-5 catalysts and showed above 90 % NO x conversion at 225–405 °C. The average particle size of CuO was 5.82, 9.20, and 11.01 nm over Cu/ZSM-5-N, Cu/ZSM-5-S (prepared by copper sulfate), and Cu/ZSM-5-C (prepared by copper chloride), respectively. The Cu/ZSM-5-N catalyst showed the highly dispersed copper species, the strong surface acidity, and the excellent redox ability compared with the Cu/ZSM-5-C and Cu/ZSM-5-S catalysts. The Cu+ and Cu2+ existed in the Cu/ZSM-5 catalysts and the abundant Cu+ over Cu/ZSM-5-N might be responsible for the superior SCR activity.

Solar Photocatalytic Mineralization of Dye New Coccine in Aqueous Phase Using Different Photocatalysts

The objective of this study was to examine the effect of band gap of photocatalyst on the decolorization of dye new coccine (NC). The concentration of NC in the present of CuO, Fe2O3, TiO2, and ZnO reduced to 50.5, 23.3, 0.1, and 0 mg L−1, respectively, after 5 h solar light irradiation. The concentration of NC in dark condition only decreased to 48.140, 45.079, 35.269, and 31.045 mg L−1 with CuO, Fe2O3, TiO2, and ZnO as photocatalysts, respectively, after 5 h contact time. The absorbance peaks and chemical oxygen demand (COD) concentration of NC in the presence of TiO2 and ZnO decreased to baseline and zero compared to the CuO and Fe2O3. The COD concentration of NC with CuO, Fe2O3, TiO2, and ZnO as photocatalysts reduced to 21, 13, 0, and 0 mg L−1, respectively, after 12 h of solar irradiation. The surface morphology of photocatalysts was examined by scanning electron microscope (SEM), and it was found that the particle size of CuO, Fe2O3, TiO2, and ZnO ranging 250–375, 250–600, 40–100, and 60–500 nm, respectively. In summary, the higher band gap energy level indicated greater photocatalytic degradation and mineralization of NC.

Synthesis and Optical Characterization of CuO Nanoparticles on Solar Borosilicate Glass

In this communication we report on the optical property of CuO nanoparticles prepared by cost effective, simplistic and environment-friendly sol-gel technique on borosilicate glass by dip coating. The particle size was analyzed by Transmission Electron Microscope (TEM) which depicted particle size of CuO ~ 5 nm. To understand the optical behavior of nanosized CuO particles on borosilicate glass tube UV-visible spectrum has been taken. Effective mass model calculations determined the size of particles as 2.26 nm, which supports the TEM analysis. Samples were also analyzed by Fourier transform infrared spectrum (FT-IR) to understand the chemical bond in detail.

Effect of CuO Particle Size on the Microstructure Evolution of Al2O3P/Al Composites Prepared Via Displacement Reactions in the Al/CuO System

An Al2O3P/Al composite was successfully synthesized using a displacement reaction between 80 wt% Al and 20 wt% CuO powders at a heating rate of 5 °C/min. Two different sizes CuO particles were used, and all the experiments were conducted under an argon atmosphere. To analyze the microstructural evolution during synthesis, the Al–20 wt% CuO samples were heated to the temperatures selected according to the differential scanning calorimetry curve and then immediately quenched with water. The phase composites and microstructure of the water-quenching samples were investigated using X-ray diffraction, optical microscopy, scanning electron microscopy and energy-dispersive spectrometry. The results indicate that the CuO particle size has a significant effect on the microstructural evolution of the samples during the heating stage and on the microstructure of synthesized composites. Smaller CuO particles can decrease the reaction temperature, narrow the reaction temperature range at the different reaction stages during the heating stage and make the size and distribution of in situ Al2O3 particles more uniform. The reaction between Al and CuO can be complete as the temperature rises to 900 °C. The size of the in situ Al2O3 particles is approximately 5 μm when the size of the CuO particles is less than 6 μm. This sample has a relatively high Rockwell hardness of 60 HRB.

The comparative effects of nano and bulk size particles of CuO and ZnO on glycyrrhizin and phenolic compounds contents in Glycyrrhiza glabra L. seedlings

Elicitors such as heavy metals are used to stimulate secondary metabolite production in plants. In this study the effects of bulk and nano size of ZnO and CuO particles on some secondary metabolites were compared in licorice seedlings. To this aim, content of reducing sugars (as precursor of secondary metabolites), proline, glycyrrhizin, total phenolic compounds, flavonoids, anthocyanins and tannins were measured and compared in 21 days seedling of Glycyrrhiza glabra under 1 and 10 µM of each nano particles of zinc oxide, copper oxide (nZnO, nCuO), or bulk size particles of zinc oxide and copper oxide (bZnO, bCuO). Mean of data compared using one-way analysis of variance and Duncan’s test. The concentration of 10 µM bulk size particles of zinc oxide decreased the content of reducing sugars. The contents of glycyrrhizin, total phenolic compounds, flavonoids, anthocyanins and proline were increased by 1 and 10 µM of nZnO and bCuO. 10 µM bZnO treatment increased the content of tannins in G. glabra seedlings. From the results it could be concluded that bulk and nano size ZnO and CuO particles affect secondary metabolite production of licorice seedlings in different patterns.

Effect of CuO particle size on synthesis temperature and microstructure of Al2O3p–Al composites from Al–CuO system

Al2O3p–Al composites were synthesized using an in-situ reaction in the 80%Al–20%CuO (mass fraction) system. The effects of the CuO particle size on the synthesis temperature and microstructure of the composites were investigated by various methods. The results indicate that the CuO particle size has a significant effect on the temperature at which the complete reaction in the Al–CuO system occurs: the temperature is 200 °C lower in the Al–CuO system containing CuO particles with sizes less than 6 μm than that containing CuO particles with sizes less than 100 μm. The interfacial bonding between Al2O3 particles and Al is not complete when the temperature is below a critical value. The morphology of the Al2O3 particles varies from ribbon-like shape to near spherical shape when the temperature is above a critical value. These two critical temperatures are affected by the particle size of CuO, and the critical temperature of the sample containing CuO particles with sizes less than 6 μm is 100 °C lower than that of the sample containing CuO particles with sizes less than 100 μm.

Selective catalytic reduction of NO by NH3 over copper-hydroxyapatite catalysts: effect of the increase of the specific surface area of the support

The influence of the increase of the specific surface area of the support Ca-HAp on the dispersion of copper species and their activity in the NO-SCR by NH3 has been studied. The copper ion exchange does not alter the Ca-HAp structure whatever the copper concentration. The increase of the specific surface area of the support changed the dispersion and the reducibility of copper species. The high NO conversion in the whole temperature range for the catalyst with the lowest specific surface area (35 m2/g) was related to the highly dispersed CuO particles that are easily reduced. Nevertheless, the increase of the specific surface area of the support (76 m2/g), induces an increase of the size of CuO particles that become less active in NO-SCR by NH3. The addition of 2.5 % of H2O to the reaction gas feed strongly affects the NO conversion in the whole temperature range. This deactivation can be related to the change of the nature of copper species rather than to the destruction of the Ca-HAp structure.