Presence Of NiO Nanoparticles Research Articles

Green synthesis of NiO from watermelon seed shell extract for the evaluation of H2 production from NaBH4 hydrolysis and photocatalytic reduction of methylene blue

In the study, NiO nanoparticles were successfully prepared from watermelon seed shell extract as a reducing agent by the green synthesis method. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and ultraviolet–visible (UV–vis) were used for the characterization of NiO nanoparticles to evaluate the structural and morphological identifications. The NiO nanoparticles were applied for the first time as a photocatalyst in the photocatalytic reduction of methylene blue and as a catalyst in H2 production from NaBH4 hydrolysis. In the photocatalytic reduction of methylene blue with NaBH4 as a reducing agent, it was observed that there was no colour change for 24 h without catalyst, and 98 % of methylene blue was reduced in 13 min in the presence of NiO nanoparticles. The photocatalytic reduction kinetics of methylene blue was investigated using the pseudo-first-order model, and the rate constant was found to be 0.382 min−1. H2 production from NaBH4 hydrolysis using the NiO nanoparticles was investigated in terms of the effect of microwave radiation ambient and temperature. The kinetics of H2 production from NaBH4 hydrolysis was studied by applying the nth-order kinetic model. The H2 production rate (rH2), activation energy (Ea) and reaction order (n-value) were found to be 660 mLH2 min−1 gcat−1 (at 70 °C), 39.8 kJ mol−1 and 0.59, respectively. This study revealed that NiO nanoparticles prepared by an eco-friendly green synthesis method can be used as an alternative potential catalyst for the photocatalytic reduction of methylene blue and H2 production from NaBH4 hydrolysis.

Effect of nickel oxide nanoparticles on protease activity in brewing industry

Intensive use of nanoparticles on an industrial scale leads to an increase in their content in the environment. This increases the risks of nano-sized objects entering the technological chains of the processing industries of the agro-industrial complex, in particular, brewing. The paper presents the results of the studies of the effect of nickel oxide nanoparticles used in various industries on the activity of the proteolytic type of enzyme preparation Neutrase 1.5MG, as well as on the results of laboratory mashing of light barley malt. The effect of different concentrations of NiO nanoparticles on the accumulation of low molecular weight nitrogenous substances during gelatin hydrolysis in model media was determined. It was found that if the content of nanoparticles exceeds 0.25 mg/cm3, the proteolytic capacity of the enzyme preparation is reduced up to 70% compared to the control at the concentration of nickel oxide nanopreparation of 2.0 mg/cm3. The experiments showed that an increase in the duration of contact between nanoparticles and proteases of the enzyme preparation in the reaction medium did not lead to an increase in the inhibitory effect of the nano-sized NiO. The laboratory mashing revealed more pronounced negative effect of nickel oxide nanoparticles on the accumulation of low-molecular nitrogen compounds. It is determined that in the presence of NiO nanopreparation, the hydrolysis efficiency of the starchy components of light barley malt is reduced. As a result, according to a number of indicators (concentration of amine nitrogen, reducing substances), the first wort obtained by mashing in the presence of nickel oxide nanoparticles at both lower (0.25 mg/cm3) and higher (2.0 mg/cm3) concentrations is inferior to samples obtained in the absence of nano-sized particles. Based on the above data, it is concluded that the presence of NiO nanoparticles in brewing environments is undesirable.

The modifier action of NiO nanoparticles on the activity, structure, and stability of proteinase K

In the present study, multi-spectroscopic methods were applied to investigate the effect of NiO nanoparticles on the structure, activity, and stability of proteinase K. To this aim, UV–Vis spectroscopy, circular dichroism photometry, and spectrofluorometry were conducted. UV absorption spectroscopy results revealed that with the addition of NiO nanoparticles, the maximum absorption of the enzyme showed hyperchromism. The regular decrement in the intrinsic fluorescence intensity of the enzyme was obtained with the increase in NiO nanoparticles concentrations. Far-circular dichroism also demonstrated a reduction in the β-sheet and β-turn and an increase in the α-helix content. Furthermore, the results obtained from this investigation revealed that the catalytic activity and thermal unfolding of the enzyme were improved in the presence of NiO nanoparticles in a concentration-dependent manner. Thus, NiO nanoparticles acted as an activator and stabilizer of proteinase K. Finally, the thermodynamic parameters showed that the enzyme–NiO nanoparticles combination was spontaneous and that the hydrophobic interactions and electrostatic forces played a key role in the interaction of the nanoparticles with the enzyme.

A comparative study on the influence of the addition of different nano-oxide particles on the thermopower of (Bi,Pb)-2223 superconductor

Solid-state reaction technique was used to prepare superconductor samples with nominal composition of (SnO2)x(Bi,Pb)-2223 and (NiO)x(Bi,Pb)-2223, where 0.0 ≤ x ≤ 0.2 wt%. The prepared samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The impact of SnO2 and NiO nanoparticles addition on the thermopower of (Bi,Pb)-2223 was measured using a standard differential technique. The Seebeck coefficient values in the presence of NiO nanoparticles were about 5–37.9% higher than those obtained with the addition of SnO2 nanoparticles. Higher values of Seebeck coefficients result in a wide variety of applications of these superconductors such as electronics and thermoelectric devices. The obtained results were analyzed according to the two-band model (Fermi-liquid model) and the two-band model with an extra linear term. The Fermi velocity (υF), Fermi energy, Fermi temperature (TF), Fermi wavenumber (KF), Fermi wavelength (λF) as well as the carrier concentration (N/V) values were calculated and discussed as a function of the nanoparticles content.

Facile microwave-assisted synthesis of NiO nanoparticles and its effect on soybean (Glycine max).

NiO nanoparticles in high purity, 15 ± 0.5 nm in size, were prepared via solid-state microwave irradiation. The [Ni(NH3)6](NO3)2 complex as a novel source was decomposed in the presence of microwave irradiation for a short time (10 min). The present method is facile, safe, and low-cost. This method exhibits other advantages; there is no need of a solvent, fuel, surfactant, expensive material, or complex instrument. Synthesised NiO nanoparticles were determined by various analyses. Also, for the first time, NiO nanoparticle effects on biochemical factors in soybean were investigated. Seeds of soybean were grown in the Murashige and Skoog agar medium containing different concentrations of NiO nanoparticles (0, 200, and 400 mg/L) for 21 days under growth chamber conditions. Estimates of malondialdehyde, hydrogen peroxide contents, and antioxidant enzymes (catalase and ascorbate peroxidase) under treatment of NiO nanoparticles were assayed. The result showed that by significantly increasing the concentration of NiO nanoparticles, the activity of catalase and ascorbate peroxidase enzymes was enhanced. Malondialdehyde and hydrogen peroxide contents significantly increased in the presence of NiO nanoparticles. In this study, the increasing activity of catalase and ascorbate peroxidase was not enough for radical oxygen species detoxification.

Synthesis and Humidity Sensing Properties of NiO Intercalated Polyaniline Nanocomposite

ABSTRACTThe exercising cooperative and interfacial properties of metal oxide and conducting polymer as a sensing material for humidity detection was the focal point of this study. In this piece of work nano sized NiO and its composite with polyaniline has been prepared. The cooperative effects of NiO on stuructural, morphology, humidity sensing behaviour of PANI has been investigated. Prepared materials were characterized by infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM),UV–VIS spectroscopy and Four probe techniques. The result reveals that the NiO strongly influences on polymer chain, crystallinity, stability, electrical and optical properties of PANI, which improves its viability in technology development. Finally, PANI/NiO was used for electrochemical humidity sensing of a closed atmosphere. The result reveals that 100 times increase in sensitivity of PANI due to the presence of NiO nano particles. Finally, the results indicate that the impact of NiO on PANI makes it promising perspective materials for humidity monitoring of closed chamber with improved sensing parameters over several method and materials.

Magnetorheological and Volumetric Properties of Starch and Polyethylene Glycol Solutions in the Presence of NiO Nanoparticles

The effect of NiO nanoparticles on the rheological and volumetric properties of dilute solutions of starch-NaOH-H2O, PEG400-PEG2000 and PEG400-PEG6000 were investigated. Achieve this aim requires to prepare the stable nanofluids. Therefore, nanoparticles of NiO were added to these solutions and dispersed by a shaker and an ultrasonic bath for making the homogeneous nanofluids. The UV-Vis spectroscopy, zeta potential and dynamic light scattering have been used to specify the stability and particle size distribution of colloidal solutions studied. Fluid flow and suspense structure of NiO nanoparticles in the solutions of starch-NaOH-H2O, PEG400-PEG2000 and PEG400-PEG6000 were studied by measuring the magnetorheological properties at T=298.15 K. Bingham plastic, Herschel-Bulkley and Carreau-Yasuda models have been applied for modeling the magnetorheological properties of nanofluids. Density values of NiO-starch-NaOH-H2O, NiO-PEG400-PEG2000 and NiO-PEG400-PEG6000 nanofluids have also been measured at T = (298.15, 308.15 and 318.15) K. The excess molar volumes were calculated from the density data for highlighting the interparticle interactions occurred in nanofluids. Singh et al. equation was used for fitting the excess molar volume values.

An interface-analyzing technique to evaluate the heavy oil swelling in presence of nickel oxide nanoparticles

Metal oxide nanoparticles, with their unique adsorption capacity, are able to reduce the asphaltene aggregation and precipitation onto the rock surface or tubing wall. The oil phase and the gas phase, which might be from the gas injection for Enhanced-Oil-Recovery (EOR) purposes or solution gas, would have different interface properties in the presence of metal oxide nanoparticles. In this investigation, the effect of NiO nanoparticles would be studied on the liquid–gas system interface of methane gas and different heavy oil samples. In details, Fluid behavior such as Surface to Volume Ratio (SVR) of the oil drop or the amount of swelled gas into the oil drop would be attended at a wide range of reservoir pressures and oil asphaltene content at the reservoir temperature. The results show that the presence of NiO nanoparticles can decrease the asphaltene aggregation and accumulation at the interface; in other words, it would increase the drop swelling and reduce the SVR increasing rate as pressure or asphaltene content increases. The key role of NiO nanoparticles, which resulted in the above-mentioned phenomena, is its high adsorption capacity. It means that in the presence of NiO nanoparticles, asphaltene molecules tend to be adsorbed by these nanomaterials instead of aggregating around each other or at the interface of gas and liquid.

Nanocomposite of Au Nanoparticles/Helical Carbon Nanofibers and Application in Hydrogen Peroxide Biosensor.

A combined sol-gel/hydrogen reduction method has been developed for the mass production of helical carbon nanofibers (HCNFs) by the pyrolysis of acetylene at 425 degrees C in the presence of NiO nanoparticles. The synthesized HCNFs were characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). The helical-structured carbon nanofibers have a large specific surface area and excellent biocompatibility. A novel enzymatic hydrogen peroxide sensor was then successfully fabricated based on the nanocomposites containing HCNFs and gold nanoparticles (AuNPs). The results indicated that the Au/HCNFs nanocomposites exhibited excellent electrocatalytic activity to the reduction of H2O2, offering a wide linear range from 1.0 μM to 3157 μM with a detection limit as low as 0.46 μM. The apparent Michaelis-Menten constant of the biosensor was 0.61 mM. The as-fabricated biosensor showed a rapid and sensitive amperometric response to hydrogen peroxide with acceptable preparation reproducibility and excellent stability. Because of their low cost and high stability, these novel HCNFs represent seem to be a kind of promising biomaterial and may find wide new applications in scopes such as biocatalysis, immunoassay, environmental monitoring and so on.

Facile and Rapid Synthesis of 5-Substituted 1H-Tetrazoles VIA a Multicomponent Domino Reaction Using Nickel(II) Oxide Nanoparticles as Catalyst

2-(1H-Tetrazol-5-yl)acrylonitrile derivatives were synthesized through multicomponent domino Knoevenagel condensation/1,3-dipolar cycloaddition reaction of carbonyl compounds, malononitrile, and sodium azide in the presence of NiO nanoparticles as a highly efficient catalyst. This method has the advantage of very short reaction times, high yields, simple methodology, and easy work-up. The catalyst can be recovered and reused while maintaining good yields.

Metal Oxide Nanoparticles for Asphaltene Adsorption and Oxidation

This study investigates the adsorption and oxidation of asphaltenes onto nanoparticles. Six different metal oxide nanoparticles were employed, namely, Fe3O4, Co3O4, TiO2, MgO, CaO, and NiO. Batch adsorption experiments were carried out at different initial asphaltene concentrations. Asphaltene adsorption was evaluated by measuring the asphaltene concentration using thermogravimetric analysis, and adsorption kinetics and isotherms were obtained. For all the six nanoparticles, the isotherm data fitted well to the Langmuir model. Results showed that asphaltene adsorption is metal-oxide-specific and the adsorption capacities of asphaltenes onto the oxides followed the order CaO > Co3O4 > Fe3O4 > MgO > NiO > TiO2. Furthermore, oxidation of asphaltene was investigated after adsorption onto NiO nanoparticles. The oxidation temperature of asphaltene decreased by ∼140 °C in the presence of nanoparticles, showing their catalytic effect. The activation energies calculated by the Coats−Redfern method for asphaltene oxidation processes in the absence and presence of NiO nanoparticles were found to be approximately 100 and 57 kJ/mol, respectively. This study is a first step in showing the feasibility of using nanoparticles for asphaltene adsorption, followed by catalytic oxidation for heavy oil upgrading.