Effect Of Nickel Concentration Research Articles

Effective CO2 photoreduction to methane over Bi2MoO6/ Ni, N co-doped TiO2 nano-photocatalyst

Bi2MoO6/Ni–N co-doped TiO2 (BM/Ni–N-T) composite was prepared by a hydrothermal, and subsequently a solvothermal method and used for CO2 photocatalytic conversion under visible light irradiation. The effect of nickel concentration in TiO2 on the photocatalytic properties and the effect of nitrogen-nickel co-doping in TiO2 structure on methane production were investigated. Furthermore, the effect of constructing a heterojunction structure between modified TiO2 and Bi2MoO6 semiconductors on the photocatalytic performance was investigated. The morphological and structural properties of the samples were characterized by X-ray diffraction, nitrogen adsorption, field emission scanning electron microscopy, Raman spectroscopy, and photoluminescence spectroscopy. Doping nickel with different concentrations in TiO2 structure could result in a narrowing of the bandgap and increase the light absorption capacity in comparison to an undoped TiO2 sample. The results reveal that modification of TiO2 with both of nickel and nitrogen elements leads to higher surface area and narrower bandgap than pure TiO2. Incorporation of nickel and, or nitrogen into TiO2 structure suppresses the CO2 absorption on the catalyst surface and results in enhanced electron-hole separation efficiency compared to pure TiO2. The 3Ni-T sample with 3 wt% nickel shows the optimum methane production among single-doped TiO2 samples. The Ni–N co-doped TiO2 sample exhibits a good response in CO2 conversion, which was nine times higher than that of undoped TiO2. The BM/Ni–N-T photocatalyst exhibits excellent photocatalytic performance for CO2 conversion (67.9 μmol/g), which is several times higher than that of pure TiO2 (3.2 μmol/g). The enhanced composite photocatalytic performance is mainly attributed to nitrogen and nickel co-doping in TiO2 and heterojunction structure, which improves light absorption capacity and charge carrier separation efficiency.

Effect of Nickel Concentration on Ozone Production using Nickel-Antimony Doped Tin Oxide for Wastewater Treatment

Nickel-antimony doped tin oxide (NATO) catalyst has greatly considered its capability to treat high organic matter and eliminate colour in wastewater as palm oil mill wastewater with electrochemical ozone generation. This study presents the optimal Ni content of NATO and its properties to enhance ozone generation. The NATO anodes were fabricated by dip-coating, varying the Ni content between 0.5% and 5%. The key findings show that all anodes showed a single phase of rutile structure with the cracked mud on the surface. The binding energies of the Sb3d3/2 peak at 540.48 eV and 541.58 eV agree with Sb3+ and Sb5+, respectively. The optimal ozone current efficiency of 37% at the current density of ca. 0.22 A cm-2 in 0.5 M H2SO4 at 2.7V was obtained on the NATO anode with 2% Ni content calcined at 700 oC. The palm oil mill wastewater treatment result showed that decolourisation TOC and COD removal efficiency increased with increasing electrolysis time. The colour removal efficiency achieved was more than 85% for a reaction time of 15 min. The efficiency of TOC and COD removal was reached ca. 80% in 20 min. The overall results appeared that NATO with electrochemical ozone generation could be employed to treat palm oil mill wastewater with high efficiency due to •OH and O3.

Effect of nickel concentration on biohydrogen production: Organic solid waste vs. glucose

In recent years, alternative renewable energy generation sources have been investigated, highlighting the dark fermentation process due to it’s potential to obtain hydrogen-rich gas, which can be used as an energy source. Different trace metals intervene in this biological process. Nickel is one of the most important because it is a component of the [Ni–Fe] hydrogenase enzyme that catalyzes the oxidation of H2 in numerous bacteria. The aim of this study was to evaluate the effect of nickel on biohydrogen production from organic solid waste (OSW). The experimental setup was carried out in batch tests using OSW as the substrate, glucose as a reference compound and the valuation of Ni2+ doses on the operation in a Sequencing Batch Reactor. The results of the batch tests showed that when using glucose as a substrate, 2 mg Ni2+/g VSinoculum generated the highest hydrogen production (774 ± 7.3 mL H2/L/d) and highest yield (55.8 ± 3.4 mL H2/g of glucose), which was 34.4% higher than the control. Testing of different concentrations of nickel using OSW as a carbon source showed that the highest production was obtained without Ni2+ addition since the nickel concentration in the residue was 0.17 ± 0.06 mgNi/gVS; consequently, hydrogen production was not affected by the lack of Ni. The addition of 0.5 mg Ni2+/g VSinoculum decreased acetate and butyrate production and increased caproate production.

Nickel Doping in ZnO Nanorod Synthesis: Effects of Nickel Concentration on Physical Properties of the Nanorod

ZnO nanorods have successfully been grown on the surface of FTO. The growth of ZnO nanorods was carried out using the seed-mediated growth method, whereas the Ni doping was carried at different concentrations. The effect of nickel doping on ZnO nanorods was observed using field emission scanning electron microscope (FESEM), UV-Vis spectroscopy, and X rays diffraction (XRD). ZnO nanorods having hexagonal shape were shown by FESEM images, and overlap of ZnOnanorods forming a nanoflowers with wider rod size. UV-Vis spectra showed that strong absorption occurred at a wavelength of 390-300 nm, the highest intensity of absorption was resulted by 15mM sample. The energy gap of the sample decreased as increasing its concentration. XRD pattern of the samples showed the diffraction peaks occurred at angles of 2θ = 31.72°, 34.45°, 36.20°, 47.50°, and 56.57° that represented the crystal plane orientation of (100), (002), (101), (102), and (110).

Effect of Nickel Concentration in Natural Zeolite as Catalyst in Hydrocracking Process of Used Cooking Oil

Zeolites impregnated with Ni were successfully synthesized through wet impregnation using activated natural zeolites (ANZs) and the nickel nitrate hexahydrate (Ni(NO3)2·6H2O) precursor at different concentrations of 1%, 2% and 3% (w/w) (hereafter referred to as ANZ/Ni 1%, ANZ/Ni 2%, and ANZ/Ni 3%). The synthesized products were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), surface area analyzer (SAA), scanning electron microscopy (SEM), total acidity measurements by employing ammonia adsorption and Brunauer-Emmett-Teller (BET) theory. The obtained catalysts were employed in the hydrocracking of waste cooking oils, and the formed products were analyzed through gas chromatography-mass spectrometry (GC-MS). The FTIR results indicated that ANZs impregnated with Ni can increase zeolite acidity. The test results of total acidity revealed that 3% ANZ/Ni catalyst exhibited the maximum total acidity of 3.70 mmol/g. XRD diffractogram confirmed the successful impregnation of Ni into ANZs, which was indicated by the characteristic diffraction peaks appearing at 2θ of 9.75º, 13.41º, 19.56º, 22.25º, 25.61º, 27.66º and 31.91º. SEM analysis indicated that the particle size of zeolite catalysts was non-uniform, but these catalysts exhibited a highly uniform surface after they were activated. Moreover, the ANZ catalysts impregnated with different concentrations of Ni exhibited a highly uniform particle size. The ANZ/Ni 3% catalyst had small uniform particle. The BET results revealed that the ANZ/Ni 2% catalyst exhibited the maximum pore volume and surface area and relatively smaller radii of pores. GC-MS was employed to determine liquid products, and its results showed that the ANZ/Ni 3% catalyst had the maximum amount of liquid products of 18%.

Effect of nickel concentration and soil pH on metal accumulation and growth in tropical agromining ‘metal crops’

This study investigated the physico-geochemical properties of three types of ultramafic substrates in Sabah (Malaysia) and further characterised their influence on nickel (Ni) accumulation in two selected tropical ‘metal crops’ (Phyllanthus rufuschaneyi and Rinorea cf. bengalensis). Three experiments, consisting of a randomised block growth trial in large pots over 12 months in Sabah, were conducted: i) soil ratio experiment (Cambisol:Ferralsol:Leptosol), ii) soluble Ni dosing experiment with added 0, 60, 240, 600 mg Ni kg−1, and iii) soil pH adjustments (pH 5.2, 5.8 and 6.4) experiment. The results show that the low pH status of Ferralsol did not result in increased extractable Ni concentrations, indicating that Ni-bearing phases and mineralogy play a major role in Ni extractability in these substrates. The increasing order of extractable Ni concentrations was Ferralsol 15 g kg−1 in P. rufuschaneyi) in the Cambisol, >5-fold higher relative to that recorded in Leptosol and Ferralsol. Mixing the Cambisol with the other substrates significantly improved Ni yield in both species relative to the individual substrates. The effect of Ni addition on the selected ‘metal crops’ was species-dependent, whereas reduction of soil pH in Cambisol significantly reduced Ni yield in both species. Nickel accumulation patterns in ‘metal crops’ in response to the diverse ultramafic soils in the tropics are influenced by the physico-geochemical characteristics of the soil types. Soil Ni extractability in these soils is more dependent on the Ni-bearing phases and mineralogy rather than the pH status. This study provides useful information on plant-soil interactions required for identifying suitable substrates for implementing tropical Ni agromining.

Effect of Nickel Concentration on Radiation-Induced Diffusion of Point Defects in High-Nickel Fe–Cr–Ni Model Alloys during Neutron and Electron Irradiation

Effect of Nickel Concentration on Radiation-Induced Diffusion of Point Defects in High-Nickel Fe–Cr–Ni Model Alloys during Neutron and Electron Irradiation

Raman spectroscopic study of ZnO/NiO nanocomposites based on spatial correlation model.

The effect of nickel concentration has been investigated in ZnO/NiO nanocomposites synthesized using the co-precipitation method. The X-ray diffraction and TEM measurements confirm the distinct phase of NiO in the ZnO/NiO samples. Furthermore, the Raman study shows the sharp modes at 99 cm−1 and 438 cm−1 corresponding to E(low)2, E(high)2 of hexagonal wurtzite ZnO structure and, 1080 cm−1 associated to the two-phonon (2P) mode of NiO, respectively. We also compared the effect of Ni concentration on the formation of ZnO/NiO by analyzing Ehigh2 Raman mode of ZnO with the help of spatial correlation model. The correlation lengths, broadening and asymmetry ratio obtained from the fitting showed good agreement with the experimental results.

Tailored hydrotalcite-based Mg-Ni-Al catalyst for hydrogen production via methane decomposition: Effect of nickel concentration and spinel-like structures

Thrive for the COx-free hydrogen production via methane decomposition has gained much interest owing to its feasibility and environmental friendliness. Herein, ahydrotalcite based Nickel catalyst was synthesized via co-precipitation method by varying the amount of Nickel concentration and tested for methane decomposition reaction in a fixed bed reactor. In addition, the effect of calcination temperature in the development of the spinel-like structure of as-developed catalyst was comprehensively discussed. It was found that the hydrotalcite based Nickel catalyst prepared at 40% Nickel concentration has the highest performance of above 80% conversion for 7 h of methane decomposition which was owing to its effective diffusion of carbon particles and its spinel-like structure, evidently from the XRD and FESEM analysis. The profound performance monitored here was attributed to the formation of carbon nanofibers (CNFs) on the surface of the catalyst which levitates the active Niospecies on its tips, results in more available active sites for the chemisorptions of the methane molecules. Nevertheless, the excessive of Nickel concentration leads to the detrimental methane decomposition performance, hencepromotes the formation of large particle size and successive development of bulk NiO phases during the reduction process, consequently abnegate the overall methane decomposition reaction. The aforementionedfindingsshow that the spinel-like structure is the key factor in the growth of long uniform CNFs and elevation of active sites on the fibre tips.

Nickel-induced global gene expressions in red maple (Acer rubrum): Effect of nickel concentrations

Red maple (Acer rubrum) does not accumulate nickel in its tissues and has been classified as Ni avoider. The genetic mechanisms involved in this metal avoidance strategy is yet to be defined. Moreover, most of the studies on metal toxicity in plants are conducted in the field where the bioavailable amount of toxic metal is small. Identification of genes whose expression is specifically modified by a toxic metal such as nickel would be useful and should provide a better understanding of their mechanisms of action. The objective of the present study was to assess the effects of different nickel doses on global gene expression in red maple (Acer rubrum). To assess nickel (Ni) toxicity, A. rubrum genotypes were treated with a control (0 mg/kg) and three doses of 150 mg of Ni per 1 kg of soil, 800 mg/kg, and 1600 mg/kg. To determine gene expression, RNA-seq libraries were developed and the De Novo transcriptome was assembled. Comparative analysis revealed significant differential gene expression only when the highest dose (1600 mg/kg) was compared to the lowest dose of Ni (0 mg/kg and 150 mg/kg). In fact, 5753 genes were upregulated and 2382 downregulated when plants treated with 1600 mg of Ni/kg were compared to plants from the 150 mg/kg treatment. These values were 6263 and 3142 when this highest Ni dose was compared to water control, respectively. The threshold for induction of gene response was found to be between 800 mg/kg and 1600 mg/kg of soil nickel. We observed more upregulated than down regulated genes coding for proteins associated with transport and translation in plants exposed to the high Ni dose compared to the low dose and water control. The study suggests that the amount of bioavailable Ni in most highly contaminated mining sites in Canada cannot trigger changes in gene expression in A. rubrum.

Nickel in Compacted Graphite Iron

AbstractThe paper presents results of the research work concerning effects of nickel concentration on the crystallization process, microstructure and selected properties of the compacted graphite iron. Compacted graphite in the cast iron was obtained with use of the Inmold process. The study has comprised the cast iron containing nickel up to concentration providing obtainment of austenitic microstructure of the matrix. The effect of the nickel on temperature of the eutectic crystallization was specified. It has been presented composition of the cast iron matrix in function of nickel concentration in a casting with wall thickness of 3 mm and 24 mm. Moreover, it has been presented conditions defining the possibility of obtaining an austenitic and martensitic compacted graphite iron. Effect of the nickel on hardness of the cast iron was described.

Porosity Evaluation and the Power Spectral Densities Analyses of Carbon–Nickel Composite Films Annealed at Different Temperatures

The densification and the fractal dimensions of carbon–nickel films annealed at different temperatures 300, 500, 800, and 1000°C with emphasis on porosity evaluation are investigated. For this purpose, the refractive index of films is determined from transmittance spectra. Three different regimes are identified, T < 500°C, 500°C < T < 800°C and T > 800°C. The Rutherford backscattering spectra show that with increasing the annealing temperature, the concentration of nickel atoms into films decreases. It is shown that the effect of annealing temperatures for increasing films densification at T < 500°C and T > 800°C is greater than the effect of nickel concentrations. It is observed that the effect of decreasing nickel atoms into films at 500°C < T < 800°C strongly causes improving porosity and decreasing densification. The fractal dimensions of carbon–nickel films annealed from 300 to 500°C are increased, while from 500 to 1000°C these characteristics are decreased. It can be seen that at 800°C, films have maximum values of porosity and roughness.

Effects of nickel doping on the preferred orientation and oxidation potential of Ti/Sb[sbnd]SnO2 anodes prepared by spray pyrolysis

Nickel and antimony co-doped Ti/SnO2 (Ti/NiSbSnO2) anodes were prepared by spray pyrolysis. Effects of nickel concentration on the structure and onset potential for oxygen evolution of Ti/NiSbSnO2 anodes have been systematically investigated. XRD analyses suggest that SnO2 thin films grow in preferential orientation along (101) plane as the nickel concentration increases. The enhanced onset potential of oxygen is above 2.4 V vs NHE due to the introduction of nickel doping, and increases slightly with the nickel concentration. The calculated results show that work function of Ni/Sb co-doped SnO2 also increases with the Ni doping level, which contributes to the enhancement of onset potential for oxygen evolution.

Structural, dielectric and magnetic properties of nickel substituted cobalt ferrite nanoparticles: Effect of nickel concentration

Nickel substituted cobalt ferrite nanoparticles with composition Co1−xNixFe2O4 (0.0 ≤ x ≤ 1.0) was synthesized using simple, low temperature auto combustion method. The X-ray diffraction patterns reveal the formation of cubic phase spinel structure. The crystallite size varies from 30-44 nm with the nickel content. Porous and agglomerated morphology of the bulk sample was displayed in the scanning electron microscopy. Micro Raman spectroscopy reveals continuous shift of Eg and Eg(2) stokes line up to 0.8 Ni substitution. The dispersion behavior of the dielectric constant with frequency and the semicircle nature of the impedance spectra show the cobalt nickel ferrite to have high resistance. The ferromagnetic nature is observed in all the samples, however, the maximum saturation magnetization was achieved by the 0.4 Ni substituted cobalt ferrite, which is up to the 92.87 emu/gm at 30K.

Effect of nickel concentration on source/drain series resistance and channel resistance of Ni-metal-induced crystallization thin-film transistors

The Ni-metal-induced crystallization (MIC) of amorphous Si (α-Si) has been employed to fabricate low-temperature polycrystalline silicon (poly-Si) thin-film transistors (TFTs). Most studies have focused only on reducing Ni contamination because Ni residues cause high leakage current in MIC–TFTs. Also of concern is the source/drain (S/D) series resistance, which degrades the device performance (driving ability) that might vary with the Ni concentration in MIC–TFTs. Improving the driving ability of MIC–TFTs requires a detailed understanding of how Ni residues affect S/D series resistance. This study investigates how Ni concentration affects S/D series resistance by using the transmission line method. The results of this study provide further insight into how Ni concentration and resistance are related. The results show that the S/D series resistance and channel resistance decreased with a reduction in Ni concentration in MIC poly-Si because of better crystalline quality and lower degradation of the donor concentration. This phenomenon was caused by the Ni concentration forming less NiSi2 nucleation sites to generate a large grain size; Ni atoms serve as acceptor-like dopants in silicon, which counteract with the effects of n-type doping, subsequently reducing the donor concentration in the S/D region.

Effects of Nickel Hyperaccumulation on Physiological Characteristics of Alyssum Murale Grown on Metal Contaminated Waste Amended Soil

A pot experiment was conducted to investigate the effect of nickel concentration on physiological characteristics of Alyssum murale when grown in a soil mixed with sewage sludge (at the rate of 2.8%). Two types of sludge were used: agricultural sewage sludge (S1) and industrial sewage sludge with an increasing nickel concentration (S2, S3, and S4). Results showed that Ni in shoots was higher than Ni in roots. A. murale is able to concentrate up to 12730 mg/kg Ni in leaves. The highest dry matter yield was observed with plants grown with agricultural sewage sludge. An addition of S2 and S3 increased shoot biomass. However, application of S4 reduced 40% shoot dry weight as compared to the control. Ni treatment did not affect all chlorophyll fluorescence parameters. The Fv/Fm ratio was stable between Ni treatments. Photosynthesis rate (A) increased with agricultural sewage sludge, but remained stable with variable Ni rates from the industrial sludge. The chlorophyll content increased with S1, S2 and S3 but it remains constant with S4 when compared to the control. Therefore, high nickel concentration did not affect the function of the photosynthetic machine of A. murale.

Effect of Nickel Concentration on Bias Reliability and Thermal Stability of Thin-Film Transistors Fabricated by Ni-Metal-Induced Crystallization

Effect of Nickel Concentration on Bias Reliability and Thermal Stability of Thin-Film Transistors Fabricated by Ni-Metal-Induced Crystallization

Effect of Nickel Concentration on Bias Reliability and Thermal Stability of Thin-Film Transistors Fabricated by Ni-Metal-Induced Crystallization

Ni-metal-induced crystallization (MIC) of amorphous Si (α-Si) has been employed to fabricate low-temperature polycrystalline silicon (poly-Si) thin-film transistors (TFTs). Although the high leakage current is a major issue in the performance of conventional MIC-TFTs since Ni contamination induces deep-level state traps, it can be greatly improved by using well-known technologies to reduce Ni contamination. However, for active-matrix organic light-emitting diode (AMOLED) display applications, the bias reliability and thermal stability are major concerns especially when devices are operated under a hot carrier condition and in a high-temperature environment. It will be interesting to determine how the bias reliability and thermal stability are affected by the reduction of Ni concentration. In the study, the effect of Ni concentration on bias reliability and thermal stability was investigated. We found that a device exhibited high immunity against hot-carrier stress and elevated temperatures. These findings demonstrated that reducing the Ni concentration in MIC films was also beneficial for bias reliability and thermal stability.

In situ incorporation of nickel nanoparticles into the mesopores of MCM-41 by manipulation of solvent–solute interaction and its activity toward adsorptive desulfurization of gas oil

In this contribution, different amounts of nickel were incorporated into the mesopores of MCM-41 via an in situ approach. A hydrophobic nickel precursor was incorporated into the nanochannels of mesoporous silica by manipulation of solvent–solute interaction. The synthesized material was characterized using X-ray diffraction, nitrogen physisorption, temperature programmed reduction, and transmission electron microscopy. The results implicate the formation of MCM-41 with well-ordered hexagonal structure and establish also the presence of nickel nanoparticles inside the nanochannels of mesoporous silica. Adsorptive desulfurization of gas oil was conducted using the nickel-incorporated MCM-41 samples. The effects of nickel concentration, temperature of process and feed flow rate on the desulfurization process were examined. The MCM-41 containing 6 wt.% of nickel had both the highest breakthrough sulfur adsorption capacity and total sulfur adsorption capacity, which were 0.69 and 1.67 mg sulfur/g adsorbent, respectively. The breakthrough sulfur adsorption capacity was almost regained after reductive regeneration of spent adsorbent. The obtained results suggest that the method applied for the synthesis of Ni y/MCM resulted in formation of well-dispersed, accessible and small nickel nanoparticles incorporated into the pores of MCM-41 which might be an advantage for adsorption of refractory sulfur compounds from low sulfur gas oil.

Effects of nickel concentration on growth, photosynthetic rate in mulberry cuttings

Effects of nickel concentration on growth, photosynthetic rate in mulberry cuttings