Trace Nickel Research Articles

New insights into the accelerated sintering of tungsten with trace nickel addition

In Ni-doped W alloys, 1–4 wt% of Ni was often employed to accelerate densification in conventional sintering process but at the expense of restricted service temperatures because of formation of liquid phase. To break the dilemma, in this work 0.1 wt% Ni was alloyed into W matrix and achieved 98% relative density. The densification and grain growth behaviors of both pure and nickel doped tungsten compacts were investigated, in which a potential new accelerated sintering mechanism by solid-solution alloying was explored. First-principles calculations demonstrated the transition barrier for vacancies in W system was lowered by 34% upon Ni doping. This alloying process therefore was beneficial for lattice diffusion of tungsten that, in turn, improved the sintering performance and service abilities of tungsten-nickel alloy.

Bryophytes as a bioindicator for atmospheric deposition in different coastal habitats (a case study in the Russian sector of the Curonian Spit, South-Eastern Baltic)

ABSTRACTThe paper describes the characteristics of accumulation of trace elements (iron (Fe), manganese (Mn), nickel, zinc (Zn), strontium (Sr), rubidium (Rb), bromine (Br) and calcium (Ca)) in moss of the natural systems of the Curonian Spit. These coastal marine ecosystems are highly susceptible to transformation by both natural and anthropogenic factors affecting the element concentration in bryophytes. The method employed to determine elemental composition of moss is X-ray fluorescence spectrometry. To explain the variations in the experimental data, the primary results were processed using descriptive statistics, correlation analysis and principal component analysis. The contamination factor was calculated. The correlation and principal component analysis revealed three factors. This may be owing to the effects of wind transport, atmospheric deposition, marine aerosol and leaching from plant residues.

NMR Spectroscopy as a Tool for Studying Asphaltene Composition

Asphaltenes are the most polar oil components with molecular weights between 500 and 1000 Da, which primarily consist of carbons and hydrogens, some heteroatoms, such as nitrogen, sulphur, oxygen and traces of nickel, vanadium and iron. Owing to their extreme complexity, it is almost impossible to completely identify all the compounds present in asphaltene samples. Various analytical techniques and approaches were used to characterize asphaltenes but their structure and composition are still a matter of thorough investigations. NMR spectroscopy can reveal useful information on asphaltene molecular architecture and aggregation process. In that respect, one- and two-dimensional NMR techniques have widely been employed. Although NMR spectra of these complex mixtures are difficult to interpret, they still can provide valuable data, especially in combination with statistical methods. Some distinctive examples of using NMR spectroscopy to study asphaltenes are given in this review.

Determination of Trace Nickel in Water Samples by Graphite Furnace Atomic Absorption Spectrometry after Mixed Micelle-Mediated Cloud Point Extraction

A simple and sensitive cloud point extraction method for the preconcentration of ultra-trace amounts of nickel as a prior step to its determination by graphite furnace atomic absorption spectrometry was proposed. It is based on the reaction of nickel with 2-(5-bromo-2-pyridylazo)-5-dimethylaminoaniline (5-Br-PADMA) in HAc–NaAc buffer media and mixed micelle-mediated extraction of the complex using the anionic surfactant sodium dodecyl sulfate sodium (SDS) and non-ionic surfactant (1,1,3,3-Tetramethylbutyl)phenyl-polyethylene (Triton X-114). The optimal reaction and extraction conditions such as pH, concentration of 5-Br-PADMA, SDS and Triton X-114, equilibrium temperature, incubation, and centrifuge time were evaluated and optimized. Under the optimal conditions, the calibration graph was linear over the range 0.1–5.5 ng/mL of nickel with a correlation coefficient of 0.9942. The detection limit obtained was 0.031 ng/mL, and the relative standard deviation was 2.1% for nickel (c = 2 ng/mL, n = 6). The proposed method was successfully applied to the determination of nickel in water samples.

Separation/enrichment of Trace Nickel(II) by Potassium Bromide—8-Hydroxyquinoline—Phenolphthalein System

A novel method for the separation/enrichment of trace Ni2+ by potassium bromide—8-hydroxyquinoline—phenolphthalein system was studied. The effects of different parameters on the enrichment yield of Ni2+ have been investigated. The possible enrichment mechanism of Ni2+ was discussed. The results showed that under the optimum conditions, the chelate precipitate of Ni(HQ)2 which produced by Ni2+ and HQ was quantificationally absorbed on the surface of microcrystalline phenolphthalein, while Zn2+, Cd2+, Co2+, Mn2+ and Bi3+ could not be adsorbed. A new method for the separation/enrichment of trace Ni2+ was established. The proposed method has been successfully applied to the separation/enrichment of Ni2+ in the samles of synthetic water, and the enrichment yield was 95.2%∼99.2%.

Fabrication of electrospun trace NiO-doped hierarchical porous carbon nanofiber electrode for capacitive deionization

Trace nickel oxide-embedded hierarchical porous carbon nanofibers (CNF-NiO) were fabricated by electrospinning polyacrylonitrile-Ni(NO3)2 (PAN-Ni) followed by stabilization, carbonization and acid treatment. The resultant CNF-NiO was characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, thermo gravimetric analysis and nitrogen adsorption-desorption isotherm. The NiO amount and porous structure can be tuned by varying the PAN/Ni ratio and acid treatment time. The electrochemical properties of the electrospun CNF-NiO nanofibers were analyzed by cyclic voltammetry and impedance method. The specific capacity of 157.9 F/g was obtained at the PAN/Ni mass ratio of 90:3 with 3 h HCl wash. This porous CNF-NiO composite has been applied as a self-supporting cathode for capacitive deionization. The desalination amount arrived at 6.2 mg/g, which is 3 times as high as that of the electrospun pure carbon fibers. Longer wash time leads to decreased capacitance and desalination performance.

Preconcentration and Determination of Trace Nickel and Cobalt in Milk-Based Samples by Ultrasound-Assisted Cloud Point Extraction Coupled with Flame Atomic Absorption Spectrometry.

In this study, ultrasound-assisted cloud point extraction (UA-CPE) method was developed for the determination of Ni(II) and Co(II) in milk-based products. After extraction and preconcentration, the Ni(II) and Co(II) contents of samples were determined by flame atomic absorption spectrometry (FAAS). After their complexation with hydroxy naphthol blue (HNB) in the presence of cationic surfactant, CTAB at pH 4.0, the Ni(II) and Co(II) were taken within the micellar phase of nonionic surfactant, TX-114. The micellar phase containing the analytes were diluted to a volume of 0.7mL with 1.0-mol/L HNO3 in ethanol to reduce its viscosity and to facilitate sample treatment and then was analyzed by FAAS. The various analytical parameters affecting UA-CPE efficiency were investigated. The analytical features obtained after optimization are as follows: limits of detection are 0.56 and 0.78μg/L; sensitivity enhancement factors are 48.6 and 53.9; the calibration curves were linear 3-180 and 2-160μg/L for Co(II) and Ni(II), respectively, after preconcentration of 50-fold. The precision (as RSD%) between 1.8-3.6% and 2.2-3.8% (25 and 100μg/L, n = 5) for Ni(II) and Co(II), respectively. The accuracy was statistically verified by analysis of two certified reference material samples (CRMs), including recovery studies after spiking. The method was applied to the analysis of milk-based samples with satisfied results.

Development and Validation of a Sensitive Method for Trace Nickel Determination by Slotted Quartz Tube Flame Atomic Absorption Spectrometry After Dispersive Liquid-Liquid Microextraction.

In this study, dispersive liquid-liquid microextraction was systematically optimized for the preconcentration of nickel after forming a complex with diphenylcarbazone. The measurement output of the flame atomic absorption spectrometer was further enhanced by fitting a custom-cut slotted quartz tube to the flame burner head. The extraction method increased the amount of nickel reaching the flame and the slotted quartz tube increased the residence time of nickel atoms in the flame to record higher absorbance. Two methods combined to give about 90 fold enhancement in sensitivity over the conventional flame atomic absorption spectrometry. The optimized method was applicable over a wide linear concentration range, and it gave a detection limit of 2.1µgL-1. Low relative standard deviations at the lowest concentration in the linear calibration plot indicated high precision for both extraction process and instrumental measurements. A coal fly ash standard reference material (SRM 1633c) was used to determine the accuracy of the method, and experimented results were compatible with the certified value. Spiked recovery tests were also used to validate the applicability of the method.

An Investigation into the Nature of the Oxide Layer Formed on Kovar (Fe\u201329Ni\u201317Co) Wires Following Oxidation in Air at 700 and 800\xa0\xb0C

This work provides new insight and evidence that challenges and extends the accepted view of the oxidation behaviour of Kovar (ASTM-15). Specimens of 2 mm diameter Kovar wire were oxidised in air at 700 or 800 °C for 10 min. The resulting oxide layers were analysed by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy, scanning transmission electron microscopy and Raman spectroscopy. Oxide layers of approximately 2 and 4 µm thickness were formed at 700 and 800 °C, respectively. These were found to contain iron, cobalt and traces of nickel. The combination of analysis techniques revealed that the oxide contains Fe2O3 in addition to (Fe, Co, Ni)3O4, a spinel oxide, in contrast to the combinations of Fe3O4, Fe2O3 and FeO that are typically reported. The oxide layer was found to be complex, consisting of multiple layers with different compositions, which is overlooked in the existing literature.

The influence of Ni(II) on brushite structure stabilization

Brushite samples doped with Ni(II) in different concentrations, from 5% to 20%, were prepared in aqueous solution at pH = 7 and at two temperatures: 25 and 37 °C. The solid samples were characterized by chemical analysis, infrared spectroscopy (FTIR) and x-ray powder diffraction (XRPD). Chemical analysis has shown Ni(II) almost complete incorporation to the solid phase up to 15%. X-ray diffraction patterns have allowed to identify brushite phase with almost no modification of the line breadth and only small shifts of lines positions with increasing Ni(II) incorporation up to 15%. For larger Ni(II) concentration, in solution, a mixture of phases has been detected. Infrared spectra have supported diffraction results. For Ni(II) 20% and over the characteristic bands of HPO42- anions tend to vanish, and the typical shaped PO43− bands are observed. These results have allowed to establish that the presence of low levels of Ni in the synthetic process not only helps brushite formation; but, also prevents brushite from apatite conversion and, in addition, preserves brushite crystallinity. According to these findings, it is possible to propose that nickel traces present in the urinary system might be a trigger to brushite stone formation and/or growth, rather than the expected brushite conversion to hydroxyapatite. This outcome would explain the recurrent detection of difficult to treat brushite stones, observed in the last three decades.

Crystallization of amorphous silicon beyond the crystallized polycrystalline silicon region induced by metal nickel**Project supported by the National Natural Science Foundation of China (Grant Nos. 61301077 and 61574096), the Natural Science Foundation of Jiangsu Province, China (Grant No. BK20130319), and the Science and Technology Program of Suzhou City, China (Grant No. SYG201538).

Crystallization of amorphous silicon (a-Si) which starts from the middle of the a-Si region separating two adjacent metal-induced crystallization (MIC) polycrystalline silicon (poly-Si) regions is observed. The crystallization is found to be related to the distance between the neighboring nickel-introducing MIC windows. Trace nickel that diffuses from the MIC window into the a-Si matrix during the MIC heat-treatment is experimentally discovered, which is responsible for the crystallization of the a-Si beyond the MIC front. A minimum diffusion coefficient of cm2/s at 550 °C is estimated for the trace nickel diffusion in a-Si.

Detection of trace nickel ions with a colorimetric sensor based on indicator displacement mechanism

A facile and reliable colorimetric sensor in both solution and paper-based membrane was presented for the determination of nickel ions. Commercial organometallic reagent zincon had been incorporated within hollow ZnSiO3 nanospheres to serve as hybrid ionophore, the blue color of which faded after successive addition of Ni2+ due to competition and displacement of Zn2+ in the ionophore. The selectivity was very good and can be further improved using Na2-EDTA as a masking agents which eventually becomes a co-ionophore. The detection solutions were further used to coat cellulose membrane modified with TiO2 and silylating reagent to fabricate paper-based sensors for naked-eye detection of Ni2+. With optimum conditions selected, the assays in solution obtained a detection limit of 35.6nM with linear range from 32nM to 9.2mM, while for the paper-based assays, the detection limit goes to 83nM with linear range between 78nM and 76μΜ. Besides, the assay enable naked-eye differentiation of nickel ions down to 0.1μΜ. Testing the present paper sensor on real river turbulent water shows a maximum 5% relative error, demonstrating the feasibility of present assays for real applications.

Analysis of trace nickel by square wave stripping voltammetry using chloropalladium(II) complex-modified MWCNTs paste electrode

The application of multiwalled carbon nanotubes (MWCNTs) paste electrode modified with chloropalladium(II) complex in the analysis of trace nickel is presented in this work. The chloropalladium(II) complex was characterized by fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and transmission electron microscope (TEM). Several operational parameters influencing the electroanalytical response of the modified electrode were optimized, such as the different composition of modifier, pH of the solution, accumulation potential, and accumulation time. At optimal condition a linear plot for nickel concentration between 10nM to 1.0μM with a limit of detection 7.4nM were obtained. The relative standard deviation for the 1.0μM of Ni(II) was 4.0% (n=5). This study shows that with the exception of Co2+, excess concentration (in 10 and 100-fold concentration) of other metal ions such as Zn2+, Cu2+, Cd2+, Mg2+, Ca2+, Ce3+, and Ba2+ did not influence the nickel response. The viability of the proposed electrodes for the determination of nickel in vegetables and different water samples was evaluated. Results were compared with those from inductively coupled plasma-optical emission spectrometry (ICP-OES).

Metal implant sensitivity: clinical and histological presentation

Metal implant sensitivity (intolerance) can cause pain, reduced mobility, loosening of the implant and skin rashes. Knowledge of differential diagnoses, histology and appropriate diagnostics are essential for proper diagnosis. To outline typical clinical signs and histology in metal-implant-associated skin lesions we present three exemplary patients from our implant allergy outpatient department and give an overview of the current literature regarding metal implant sensitivity. In patients with a negative patch test the lymphocyte transformation test may reveal metal sensitization. Even "pure" titanium alloys may contain traces of nickel. The histology of implant-associated skin reactions goes from teleangiectatic postimplantation erythema to eczema and vasculitis. Based on the synopsis of history, clinical picture, allergological testing and histology, metal implant sensitivity can be diagnosed more precisely.

An Accurate Methodology to detect Leaching of Nickel and Chromium Ions in the Initial Phase of Orthodontic Treatment: An in vivo Study.

The aim of this study was to evaluate the release of nickel and chromium ions in human saliva during fixed orthodontic therapy. Ten patients with Angle's Class-I malocclusion with bimaxillary protrusion without any metal restorations or crowns and with all the permanent teeth were selected. Five male patients and five female patients in the age group range of 14 to 23 years were scheduled for orthodontic treatment with first premolar extraction. Saliva samples were collected in three stages: sample 1, before orthodontic treatment; sample 2, after 10 days of bonding sample; and sample 3, after 1 month of bonding. The samples were analyzed for the following metals nickel and chromium using inductively coupled plasma optical emission spectrometry (ICP-OES). The levels of nickel and chromium were statistically significant, while nickel showed a gradual increase in the first 10 days and a decline thereafter. Chromium showed a gradual increase and was statistically significant on the 30th day. There was greatest release of ions during the first 10 days and a gradual decline thereafter. Control group had traces of nickel and chromium. While comparing levels of nickel in saliva, there was a significant rise from baseline to 10th and 30th-day sample, which was statistically significant. While comparing 10th day to that of 30th day, there was no statistical significance. The levels of chromium ion in the saliva were more in 30th day, and when comparing 10th-day sample with 30th day, there was statistical significance. Nickel and chromium levels were well within the permissible levels. However, some hypersensitive individuals may be allergic to this minimal permissible level.

Modified surface-active ionic liquid-coated magnetic graphene oxide as a new magnetic solid phase extraction sorbent for preconcentration of trace nickel

General procedure for preconcentration/recovery of nickel ions using modified surface-active ionic liquid-coated magnetic graphene oxide nanocomposite.

Use of a new magnetic ion–imprinted nanocomposite adsorbent for selective and rapid preconcentration and determination of trace nickel by flame atomic absorption spectrometry

Selective and rapid preconcentration of trace Ni(ii) in environmental water by solid-phase extraction using a magnetic Ni(ii)–imprinted nanocomposite as the adsorbent.

Determination of Trace Nickel in Natural Water by Flow Injection Analysis with Cetrimonium Bromide as Sensitizer

2-(5-Bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) is a highly sensitive chromogenic reagent that can react with most of the transition and alkaline earth metals. The Ni(II)-5-Br-PADAP complex is more stable than other metal–5-Br-PADAP complexes. In the presence of seignette salt, ethylenediaminetetraacetic acid (EDTA) can decompose most of the 5-Br-PADAP complexes with metals except for iron, cobalt, and nickel. Cetrimonium bromide (CTMAB) as a sensitizer for the color reaction forms a ternary complex with nickel and 5-Br-PADAP with maximum absorption wavelength at 561 nm. CTMAB can significantly improve the sensitivity and selectivity of nickel determination, as well as the stability and solubility of compounds. In this study, the determination of trace nickel in natural water samples was performed by flow injection analysis. The calibration lines were established in the range of 0–200 μg/l of nickel (n ≥ 3), and the limit of detection was 0.093 μg/l. The relative standard deviation was 2.55% for the determination of 25 μg/l nickel (n ≥ 20). The recoveries of this method ranged from 91.0 to 101% for environmental water samples. A large amount of aluminum, calcium, cadmium, copper, bicarbonate, magnesium, zinc, and iron, except for cobalt, did not interfere with the determination of nickel.

Safety evaluation of traces of nickel and chrome in cosmetics: The case of Dead Sea mud

BackgroundMetal impurities such as nickel and chrome are present in natural ingredients-containing cosmetic products. These traces are unavoidable due to the ubiquitous nature of these elements. Dead Sea mud is a popular natural ingredient of cosmetic products in which nickel and chrome residues are likely to occur. ObjectiveTo analyze the potential systemic and local toxicity of Dead Sea mud taking into consideration Dead Sea muds' natural content of nickel and chrome. MethodsThe following endpoints were evaluated: (Regulation No. 1223/20, 21/12/2009) systemic and (SCCS's Notes of Guidance) local toxicity of topical application of Dead Sea mud; health reports during the last five years of commercial marketing of Dead Sea mud. Results and conclusionsFollowing exposure to Dead Sea mud, MoS (margin of safety) calculations for nickel and chrome indicate no toxicological concern for systemic toxicity. Skin sensitization is also not to be expected by exposure of normal healthy skin to Dead Sea mud. Topical application, however, is not recommended for already nickel-or chrome-sensitized persons. As risk assessment of impurities present in cosmetics may be a difficult exercise, the case of Dead Sea mud is taken here as an example of a natural material that may contain traces of unavoidable metals.

Cloud point-TiO2/sepiolite composites extraction for simultaneous preconcentration and determination of nickel in green tea and coconut water

In this work, cloud point-TiO2/sepiolite composites–octyl alcohol extraction combined with UV–vis spectrometry was applied to analyze nickel in real samples. Trace nickel was separated and preconcentrated with PAN as chelating agent, and TiO2/sepiolite composites—octylphenoxypolyethoxyethanol (TX-114)—octyl alcohol as extraction agent. Factors influencing extraction efficiency, such as concentrations of TX-114 and octanol, type of the desorption on the extraction system, concentration of chelating agent, pH, incubation temperature, incubation time and conditions of phase separation were investigated and optimized systematically. The results showed that TiO2/sepiolite composites exert significant effects on the extraction efficiency; especially nickel concentration is very low. Under the optimal conditions, the absorbance signal is linear with nickel concentration in the range of 0.02–3 mg L−1 and the detection limit was 5 μg L−1. The developed method was successfully applied to the determination of nickel in natural products of Baisha green tea and coconut water in Hainan.