Distribution Of Nickel Research Articles

Nickel Supported on Mesoporous Zirconium Oxide by Atomic Layer Deposition: Initial Fixed-Bed Reactor Study

Atomic layer deposition (ALD) is gaining attention as a catalyst preparation method able to produce metal (oxide, sulphide, etc.) nanoparticles of uniform size down to single atoms. This work reports our initial experiments to support nickel on mesoporous zirconia. Nickel (2,2,6,6-tetramethyl-3,5-heptanedionate)2 [Ni(thd)2] was reacted in a fixed-bed ALD reactor with zirconia, characterised with BET surface area of 72 m2/g and mean pore size of 14 nm. According to X-ray fluorescence measurements, the average nickel loading on the top part of the support bed was on the order of 1 wt%, corresponding to circa one nickel atom per square nanometre. Cross-sectional scanning electron microscopy combined with energy-dispersive spectroscopy confirmed that in the top part of the fixed support bed, nickel was distributed throughout the zirconia particles. X-ray photoelectron spectroscopy indicated the nickel oxidation state to be two. Organic thd ligands remained complete on the surface after the Ni(thd)2 reaction with zirconia, as followed with diffuse reflectance infrared Fourier transform spectroscopy. The ligands could be fully removed by oxidation at 400 °C. These initial results indicate that nickel catalysts on zirconia can likely be made by ALD. Before catalytic testing, in addition to increasing the nickel loading by repeated ALD cycles, optimization of the process parameters is required to ensure uniform distribution of nickel throughout the support bed and within the zirconia particles.

Visualization of the Sorption of Nickel within Exopolymer Microdomains of Bacterial Microcolonies Using Confocal and Scanning Electron Microscopy.

The sorption and distribution of nickel, a common metal contaminant in aquatic systems, were assessed in bacterial microcolonies using a combination of fluorescent staining with Newport Green and confocal laser scanning microscopy (CLSM) with confirmation by scanning electron microscopy (SEM) and X-ray microprobe analyses. CLSM with Newport Green, selected fluor-conjugated lectins, and DNA staining allowed for the discrimination of the microdomains present in the microcolony exopolymeric matrix and detection of bound nickel. This approach avoided the artefacts associated with drying and fixation required by analytical electron microscopy. The results obtained indicated that specific microcolonies within river biofilms sorbed nickel within limited microdomains present in the complex tripartite exopolymeric matrix surrounding bacterial cells. Sorption occurred such that nickel was concentrated within the exopolymeric matrix, but not directly associated with cells. These microdomains appeared to have neutral pH and be dominated by negatively charged residues favoring the sorption of nickel and other cations. These results also suggest an important role for specific community members in the sorption and concentration of metals in aquatic biofilm communities.

High-Speed Direct Laser Deposition of 51Ni-14Co-10Cr-6Al-5Mo Alloy: Microstructure and Phase composition

The heat-resistance nickel-base alloy was produced by the additive technology of high-speed direct laser deposition. Various laser power parameters were applied during production of samples. A detailed study of the microstructure showed a change of the structure of the samples due to laser power increase and cooling rate change and repeated heat-effect. The phase composition was analyzed in accordance with the results of X-ray analysis and EDS. The changes in the ratio of alloying elements at the cross-section of samples showed a relationship between the distribution of nickel and chromium.

Experimental investigations of vanadium and nickel distribution while firing petcoke in a circulating fluidised bed test facility

Petcoke was fired as independent fuel in CFB test facility and the distribution of vanadium and nickel throughout the boiler and its deposition rate was assessed. It was found out that during combustion, 7%-8% of the total vanadium is in bottom zone of furnace, 31%-33% is in circulating zone, nearly half of total V (47%-49%) is in second pass and the rest 11%-15% got deposited in the boiler or escaped through the stack. Meanwhile in the case of nickel, 26%-29% is in primary loop and rest 66%-68% is in second pass. Vanadium deposits were found as inclusions in lime based deposits. XRF and XRD analysis of loose deposits found in back pass confirms the presence of vanadium. It was noticed that although petcoke contains high amount of vanadium and nickel, most of them were absorbed in situ limestone and turned to stable solid form. [Received: February 1, 2017; Accepted: July 6, 2017]

Experimental investigations of vanadium and nickel distribution while firing petcoke in a circulating fluidised bed test facility

Experimental investigations of vanadium and nickel distribution while firing petcoke in a circulating fluidised bed test facility

Physiological response and mineral elements accumulation pattern in Sesuvium portulacastrum L. subjected in vitro to nickel

Sesuvium portulacastrum, a halophyte with high tolerance to heavy metals like Cd, Pb and Ni is considered for phytoremediation of metal contaminated saline soils. The tolerance to a selected metal ion could, by hypothesis, be stimulated through in vitro adaptation and regeneration of the plant. Seedlings obtained by in vitro micro-propagation, were exposed to 0, 25 and 50 μM Ni, as NiCl2, in agar-based medium for 30 days. Growth parameters, plant water content, the concentration of photosynthetic pigments, proline and malondialdehyde (MDA) concentrations were determined. Nickel and nutrients distribution in leaves was studied by micro-Proton-Induced-X-ray-Emission (μ-PIXE). The results showed that Ni was mainly accumulated in vascular bundles, next in water storage tissues and chlorenchyma. Ni concentrations in chlorenchyma increased with increasing Ni in culturing medium, in direct relation to decrease of photosynthetic pigments and increase of oxidative stress. As compared to control plants, Ni induced substantial increase in MDA and proline accumulation. Plants exposed to 50 μM Ni accumulated up to 650 μg g−1 of Ni in the shoots, exhibiting chlorosis and necrosis and a drastically reduced plant growth. Perturbations in uptake and distribution of nutrients were observed, inducing mineral deficiency, probably through membrane leakage. The mineral nutrient disturbances induced by Ni could be highly implicated in the restriction of S. portulacastrum development under the acute 50 μM Ni level.

Assessment of trace elements (Cd, Cu, Ni, Zn) fractionation and bioavailability in vineyard soils from the Hamedan, Iran

The use of fertilizers and fungicides causes the accumulation of trace elements in vineyard soils that may increase their bioavailability for plants. The aims of this study were to evaluate the cadmium (Cd), copper (Cu), nickel (Ni), and zinc (Zn) accumulation and distribution in three depths of 10 vineyard soils using total content, fractionation and DTPA extraction, and also to measure the content of trace elements in aerial parts of grapevines. The highest contents of Cd, Cu, Ni and Zn were observed at 0–20 cm layer and decreased with the depth. The mean total contents of the trace elements in the surface layer of row and between row soil samples were (mg kg−1) respectively, Cd 2.39, 2.43; Cu 46.63, 44.11; Ni 45.55, 44.30; Zn 100.92, 95.35. The highest percentage of the Cd was associated with carbonate (CARB) fraction, while the greatest percentage of the Cu, Ni and Zn were present in the residual (RES) fraction. Therefore, the Cd may be formed bioavailable and leachable forms in vineyard soils. The mobility factor (MF) values in row soil samples ranged from 39–51, 7–11, 6–10 and 4–10 for Cd, Cu, Ni and Zn, respectively indicating high leachability of Cd. The DTPA-extractable contents of trace elements in the surface layer were higher than those in the subsurface layers. The mean bioavailable contents of trace elements in the surface layer of row and between row soil samples were (mg kg−1) respectively, Cd 0.43, 0.43; Cu 2.19, 2.12; Ni 1.71, 1.71; Zn 2.45, 2.34. The content of trace elements in the leaves was higher than the berries. The mean contents of trace elements in leaves and berries were (mg kg−1) respectively, Cd 0.36, 0.00; Cu 5.91, 5.39; Ni 9.58, 6.27; Zn 27.04, 8.06. Trace element contents showed the following order: Zn > Ni > Cu > Cd in leaves and berries. The transfer factor (TF) values of trace elements in the leaves were higher than the berries and showed the following order: Zn > Ni > Cu > Cd in leaves and Ni > Cu > Zn > Cd in berries. There were significant and positive correlations between total and bioavailable contents of Cd, Cu, Ni and Zn in soils with correlation coefficients 0.97, 0.89, 0.66 and 0.85, respectively. The Cd and Cu contents in the aerial part of plants showed significant and positive correlations with total and bioavailable contents of these trace elements in soils, whereas the Ni and Zn contents in the aerial part of plants correlated significantly and positively only with bioavailable contents of these trace elements in soils.

Soil Contamination by a Lead Smelter in Brazil in the View of the Local Residents.

A primary lead smelter operated in Santo Amaro City in Brazil from 1960 to 1993, leaving approximately 500,000 tons of industrial dross containing 2–3% of lead and other toxic elements that contaminated the industry grounds and the urban environment. This study aimed to present the local residents’ perception towards soil contamination by the smelter. In a cross-sectional study, 208 residents from randomly selected households were interviewed about dross hazards and proposals for its management. A city map depicts the distribution and concentration of lead, cadmium, arsenic, zinc, nickel, and antimony, measured in the soil of the 39 households with visible smelter dross. Only one site complies with the soil quality reference values; 27 (69.2%) call for preventive measures, and 11 (28.2%) require intervention. The smelter dross continues widely spread over the city. Thirty (76.9%) out of the 39 residents were able to recognize the smelter dross on household surroundings. However, this ability was not associated with the concentrations of toxic elements in the soil of their residences and surroundings. The smelter and the local Prefecture were most frequently held liable for taking soil cleanup actions. The most frequently (38.0%) cited solution for managing the dross found in the households was “to provide the residents with information about health risks related to the dross”.

Preparation of Ni-based egg-shell-type catalyst on cylinder-shaped alumina pellets and its application for hydrogen production via steam methane reforming

Nickel-based ‘egg-shell-type’ catalysts were prepared using cylinder-shaped alumina pellets as supports. In the egg-shell-type catalysts, nickel was selectively located in the outer region of the alumina pellets. Ethylene glycol or 1-octanol were used as hydrophobic solvents to retard internal penetration of the alumina pellets by the nickel nitrate solution. Without hydrophobic solvent, a ‘homo-type’ catalyst with even nickel distribution inside the alumina pellets was achieved. Cross-sectional images and SEM-EDS analysis of the cylinder-shaped alumina pellets showed that nickel concentration in the egg-shell-type catalyst was higher in the outer region and decreased towards the inner region of the alumina pellets. The egg-shell-type nickel distribution was maintained after subsequent magnesium impregnation and calcination processes. X-ray diffraction patterns and temperature programmed reduction profiles showed that the only difference between homo-type and egg-shell type catalysts, when their nickel loading was the same, was the nickel distribution inside pellets; and this was shown to cause significant difference in their catalytic activity in the steam methane reforming (SMR) reaction. For the homo-type catalyst, nickel loading of 3.5 wt% was insufficient for the SMR reaction, as metallic nickel particles were evenly distributed through the entire alumina pellet. However, nickel loading of 3.5 wt% was sufficient for the egg-shell-type catalyst, because active sites with metallic nickel particles were concentrated in the outer region of the pellets. These experimental results confirmed that the egg-shell-type nickel distribution is a favorable design for an SMR reaction catalyst.

MOF-derived hollow porous Ni/CeO2 octahedron with high efficiency for N2O decomposition

A novel material of hollow porous NiO@CeO2 octahedron (HPOC) derived-from cerium-based metal-organic frameworks (MOF) was prepared as a high-performance catalyst for N2O decomposition. Octahedron-shaped cerium-based MOF was successfully synthesized with formic acid as a structure-modulating agent by rational controlling the volume ratio of N,N-dimethylformamide and formic acid at 4:1. The obtained NiO@CeO2-HPOC was systematically characterized to reveal its morphology, structure and surface properties. TEM, SEM and N2 adsorption-desorption isotherms results confirm the well-defined octahedral morphology and hollow porous structures of NiO@CeO2-HPOC. EDS mapping and XRD studies indicate that NiO@CeO2-HPOC hybrid composite exhibits relatively homogeneous Ni dispersion and small NiO size, which comes from the unique coordination bond and porosity of cerium-based MOF precursor. H2-TPR analysis shows that uniform nickel distribution enables the highly dispersed NiO species in NiO@CeO2-HPOC. Furthermore, Raman and XPS results indicate that NiO@CeO2-HPOC possesses large amount of oxygen vacancies. The hollow porous structures, homogeneous Ni dispersion, as well as large amount of oxygen vacancies facilitate the catalytic efficiency. As a result, NiO@CeO2-HPOC exhibits a high catalytic activity and enhanced O2 tolerance for N2O decomposition.

Source Determination, Contamination Level and Predicting of Some Inorganic Contaminants Concentration in the Top Soils of Sanandaj City

n Background & objective: Mineral contaminations are the most important environmental problems in the urban area. The objectives of the present study was determination of concentration, spatial distribution and source determination of Iron, Zinc, Calcium, Copper, Manganese, and Nickel by Artificial Neural Network in Sanandaj city. Materials & Methods: The study area were divided into the five classes and the total number of 105 surface soil samples (0-10 cm) were collected. Contamination factor and Nemerow index were developed for estimation of metal concentration. In addition, the correlation and principle component analysis were conducted to find the origin of the considered elements in the soil samples. Moreover, IDW interpolation technique was applied for mapping the spatial distribution of the elements and ANN (multilayer perceptron) was applied to estimate the concentration.n n Results: Copper concentration in industrial area was very high and in the other hand, green and industrial area had the lowest and highest Nemerow index, respectively. Calcium concentration especially was affected by residential and high traffic areas. On the other hand, industrial and high traffic areas have the greatest impact on the Zinc and Copper concentration and Nickel, Iron and Manganese contamination was under combination effects of natural and anthropogenic factors. Correlation coefficients derived by ANN were 0.821, 0.661, 0.711, 0.767, 0.712, and 0.701 for Copper, Nickel, Zinc, Manganese, Iron, and Calcium, respectively. Conclusion: The concentration of Zinc, Calcium and Copper are mostly affected by human activities and Nickel, Iron, Manganese concentration are controlled by both anthropogenic and natural sources. According to the results, three-layer neural network is recommended for estimating metal concentration in the soil samples.

Evaluation of health risk to humans in consumption of wheat grown in nickel-contaminated soils

In this research, accumulation and distribution of nickel in root, leaves and stem and grains of wheat were studied to assess the health of wheat grain for human consumption. A greenhouse experiment was conducted based on randomized complete block design with three replications. Wheat was grown under two nickel concentrations in soil (0.0 and 100 mg kg-1). At maturity, wheat was divided into its parts (root, leaves and stem, grain) and nickel concentrations were measured in plant parts. Results indicated that the highest nickel (132.8 mg kg-1 plant tissue) was accumulated in roots which was 12 times more than nickel accumulated in shoots, suggesting that no actual remediation was occurred by wheat. Under high concentrations of nickel, wheat grains are not suitable for human consumption, because health risk index was achieved 130.27 and 169.40 for adults and children, respectively. However, because wheat was able to grow under high concentrations of nickel, this plant can be considered as a tolerant plant to nickel stress. Further research is needed to determine the ultimate limit of nickel concentrations in soils where the accumulation of nickel in the grains is not such a high amount that it threatens human health.

Levels and distribution of cobalt and nickel in the aquatic macrophytes found in Skadar Lake, Montenegro.

Macrophytes react to changes in the quality of the environment in which they live (water/sediment), and they are good bioindicators of surface water conditions. In the present study, the content of the metals cobalt (Co) and nickel (Ni) was determined in the sediment, the water, and different organs of macrophytes from six localities around Lake Skadar, across four different seasons of year. The aquatic macrophytes that have been used as bioindicator species in this study are Phragmites australis (an emerged species), Ceratophyllum demersum (a submerged species), and Lemna minor (a floating species). The aim of this study was to determine the distribution of metals in macrophyte tissues and also to discover the degree of bioaccumulation of the investigated metals, depending both on the location and on the season. The content of Co and Ni in the examined parts of the macrophytes was in the range of 0.04-8.78 and 0.30-28.5ppm, respectively. The greatest content of the investigated metal in the organs of P. australis and C. demersum was recorded at the beginning of and during the growing season. Greater concentrations of metals in the tissue of L. minor were observed at the end of the growing season.

Flow dynamics during single- and dual-spot laser welding with one common keyhole of 321 stainless steel

The keyhole is unstable with the presence of humps at the keyhole walls during single-spot laser welding (SSLW). The keyhole stability is improved and the presence of humps is reduced during dual-spot laser welding (DSLW). The vortices present at the rear keyhole wall during SSLW disappear during DSLW. There is an upward motion of the melt flow at the rear keyhole wall and the melt flow velocity is higher along the width of the molten pool during DSLW. A sandwich specimen is constructed to investigate the effect of keyhole and melt flow dynamics on the final shape of the weld seam. The results show that DSLW produces smoother, more regular weld beads due to higher stability of the keyhole and molten pool. DSLW produces a weld seam with fewer porosities and a more homogeneous nickel distribution due to the upward motion and absence of vortices in the melt flow. DSLW produces a wider molten pool due to the higher melt flow velocity along the width of the molten pool.

Carbon Modification of Nickel Catalyst for Depolymerization of Oxidized Lignin to Aromatics

Catalytic valorization of lignin is a sustainable way to provide aromatics for the human society, which depends on the electronic structure of catalytic sites. We herein report the preparation of a carbon-modified nickel catalyst via carbothermal reduction of Ni-doped layered double hydroxides. Lignosulfonate (LS), a lignin resource from the pulp industry, was used as a renewable carbon precursor. The carbon residues in the nickel surface layer changed the 3d electron distribution of nickel, which was highly selective for the C–O bond hydrogenolysis of lignin into aromatics, and 22 wt % total mass yields of aromatics were achieved from hydrogenolysis of oxidized birch lignin.

Vanadium and Nickel Distribution in Resin Fractions of High-Sulfur Heavy Oils

The mechanisms of occurrence and distribution of vanadium and nickel in resins and their fractions are studied with reference to high-sulfur heavy oils of Tatarstan, Samara Oblast (region), and Kazakhstan deposits. For all the investigated heavy oils, the content of vanadium and nickel in resins increase in direct proportion to the increase in contents of these metals in the oils. The resins were fractionated into benzene and alcohol-benzene fractions by adsorption chromatographic separation on silica gel. The alcohol-benzene fractions are characterized as being more polar on account of a larger content of oxygen-bearing structural groups. The special features of vanadium and nickel content and distribution in resin fractions are disclosed for heavy oils of various production complexes.

Nickel in Terbium Metal and Its Characterization by Laser Induced Breakdown Spectroscopy-Original Position Statistic Distribution Analysis

The application of terbium involved in giant magnetostrictive materials, phosphors, magneto-optical storage materials, magneto-optical glass, and so on. The requirement of content of nickel is stringent for most of the materials. The distributions of nickel in terbium by Laser induced breakdown spectroscopy-original position statistic distribution analysis (LIBS-OPA) and the reason of difficult removal of nickel by vacuum distillation but easy removal by SSE had been mainly discussed in this paper. Terbium ingot prepared by electron-beam smelting after vacuum distillation was processed into rod of 0.76 cm in diameter and 15 cm in length. The solid state electrotransport (SSE) experiment was done to the rod at 1100°C and 450 A cm-2 for 100 h under UHV (10-7 Pa) conditions. LIBS-OPA was used to acquire the local distribution of nickel in terbium after SSE purification in this study. The result of this study showed that nickel particles transported by the passing current from anode to cathode. This result was consistent with the result of glow discharge mass spectrometry (GDMS) analysis to the whole rod. LIBS-OPA is a promising approach which could be used to analyze the distributions of micro and trace impurities in other metals and alloys. Highlights: Distribution of Ni in terbium after SSE had been obviously observed by LIBS-OPA. Nickel in Terbium is difficult to be removed by vacuum distillation, but after Solid State Electrotransport (SSE) for relative long time, content of Nickel can be greatly reduced. The main reason of the difficult removal of nickel by vacuum distillation and easy removal by SSE had been discussed in detail in this study.

Distribution of chromium, nickel, copper and zinc in the Al Zintan area, northwestern Libya

Global population is growing rapidly. As a result, increasingly large areas are being settled and farmed. This devastates soils and causes pollution by heavy metals and other components. Heavy metals in the environment originate from both natural and anthropogenic sources. Natural sources generally include rock weathering and the propagation of heavy metals, such as Cr and Ni, from ultrabasic rocks. These are natural processes that generally do not threaten human health. Anthropogenic sources include industry and inappropriate disposal of waste in the environment. In such cases concentrations of heavy metals can be harmful to people and other living beings. Al Zintan is a city located in northwestern Libya, on a plateau mainly built up of Cretaceous sediments. Since the 1980?s, nomadic population has rapidly been settling this area. As a result, a former part of the desert was transformed and is used for farming. Soil sampling at Al Zintan was conducted in 2017, across a 2?2 km grid. A total of 143 samples were collected from depths of about 30 cm. The samples weighed 2 to 2.5 kg and generally comprised sand with a clay component. A Niton Xl3t goldd+ instrument was used for chemical analyses, based on which GIS heavy-metal distribution maps were generated. The distribution of Cr, Ni, Cu and Zn is discussed on the paper.

GC-MS Determination of the Isotope Distribution of Nickel

A new approach to the determination of the isotopic composition of nickel by the GC-MS method is proposed. This method has been used to investigation of four Ni-containing samples. The obtained data are generally consistent with the literature, but its accuracy is lower than in the traditional techniques.

Fibrous alumina-based Ni-CeO2 catalyst: Synthesis, structure and properties in propane pre-reforming

In the present paper we report the synthesis, structural characterization and catalytic properties of alumina nanofibers supported Ni-CeO2 catalyst (Ni-CeO2/ANF) in pre-reforming of propane as a main component of liquefied petroleum gas. Ni-CeO2/ANF catalyst was prepared via template-assisted wet-combustion synthesis. High dispersion and uniform distribution of nickel and ceria species over nanofibers surface were reached. Ni-CeO2/ANF exhibited sufficient activity, stability and coking-resistance in pre-reforming of propane at low steam to carbon ratio and temperatures of 350–425 °C.