جستجوی مقالات مرتبط با کلیدواژه « نیکل » در نشریات گروه « شیمی »

Design and synthesis of heterogeneous catalysts to reduce nitroarenes are an important and essential technique in green chemistry. In this research, C/B/Ni heterogeneous catalyst was prepared through functionalization of the chitosan and immobilization of nickel cations on the surface of the chitosan. The ammine groups of the chitosan reacted with aldehyde groups of 2-(4-chlorophenyl thio) benzaldehyde via Schiff base condensation and NS donor groups which can bind to metal, placed on the surface of the chitosan. In the end, NS donor groups coordinated to Ni2+ cations. After characterization of the prepared catalyst with various physicochemical technique, its performance was considered in reduction of nitroarenes to aminoarenes. The prepared catalyst depicted a very good efficiency in reduction of nitroarenes in aqueous media, room temperature, and relatively short time. Moreover, recovered catalyst was utilized in catalytic cycles and its efficiency is reportable after three consecutive cycles without negligible reduce.

In the last two decades, environmental pollution by heavy metals has increased, and the accumulation of these pollutants in aquatic ecosystems has brought many risks to the health of humans, animals, plants, and the environment. Cadmium and nickel can be mentioned as metals that have very toxic and carcinogenic properties. In this research, the isolation of bacteria from the steel industry factory in Sari, the effluent of the sausage factory in Golestan province, and the Lavij hot spring in Mazandaran, which have the ability to uptake heavy metals cadmium and nickel, were investigated. In the following, the optimization process of biological adsorption (the effect of parameters such as: temperature, concentration of metals, dosage of bacteria, pH...) was investigated. Based on the above results, the best isolate was used to remove these metals. Biochemical, morphological, and molecular findings have shown the closeness of the selected isolate to the genus Bacillus. According to the minimum inhibitory concentration test of the selected Bacillus bacteria, this isolate was resistant to a concentration of 1500 ppm of cadmium and 2200 ppm of nickel. The optimum pH for the removal of cadmium and nickel metals by the selected bacteria was 6.5 and 5.5, respectively, and the adsorption efficiency of cadmium and nickel metals was 0.72 and 0.63 mmol/g, respectively. The temperature for the removal of cadmium and nickel by Bacillus bacteria was about 45 degrees Celsius. The adsorption isotherm for both metals is similar to the Langmuir isotherm, which shows that the surface adsorption process is single-layer, and its kinetics is according to the second-order kinetic model, and the optimal amount of Bacillus bacteria biomass is about 1.5 g/liter. The selected isolate has suitable characteristics for use in real and industrial scale containing the mentioned metals.

One method to prevent contamination of glazed building tiles by volatile organic materials is coating their surfaces with nanophotocatalyst titanium dioxide, preferably at temperatures above 1000 °C. However, at such high temperatures titanium is subjected to phase change and cannot maintain its photocatalytic properties. In other words, the conventional coating methods encounter phase change problem. The main purpose of this experimental research is to resolve the aforementioned problem to maintain the thermal stability of titanium dioxide at temperatures more than 1000C. In order to achieve this purpose, silica and duPont two-component were used. Silica-based titanium dioxide nanostructure was doped with N and Ni ions. Then the coating materials were calcined at 1250 °C. FTIR, SEM, XRD, EDX and TGA technics were used for nanostructure analysis which indicated thermal stability of the nanostructure up to 1250 °C. The main advantage of the utilized coating method is its simplicity and economically reasonability.  Titanium has a catalytic effect only in the UV region. In order to enjoy the benefits of the visible light, the nanostructure was modified with different ions. Note that, the titanium dioxide has three phases, namely anatase, rutile and brookite, among which photocatalytic properties of anatase have received more attentions. DuPont and silica together cause a delayed phase change from anatase to rutile at high temperatures. The delay is very essential for some industrial applications such as preserving self-cleaning properties of surfaces after they have been coated. The resulting environmental impact is less consumption of chemical detergents. Results indicate that for titanium dioxide the presence of the anatase phase at 700 °C is 83%, but at 800 °C anatase completely converts to rutile phase. Furthermore, catalyst modifications by duPont two-component using silica along with calcination at higher temperatures makes anatase phase to grow. So that at 1250 °C it comprises 86% of the nanostructure.

In this paper, the possibility of using Metal-organic framework UIO-66 in the propane ODH process at low temperatures was investigated. In this process, Nickel (Ni) was used as the main catalyst with the loading of 5, 15 and 25 (wt%) on support and O2 gas as oxidant. In order to accurately examine and determine the optimal state, the experimental design during the work was assisted. The effect of three parameters such as reaction temperature, Volumetric flow rate (sccm) and Ni loading (wt%) at three levels of -1, 0 and +1 was investigated. For better dispersion of nickel catalyst on the synthesized support, the ultrasonic method was used to synthesize the catalyst. As a result, it led to the top-loading of the catalyst with the form of a monolayer on the support. The catalyst structure was evaluated using various characterization methods including XRD, BET, SEM and EDX. In this study, the synthesized Metal-organic framework UIO-66 has a surface area of 1327.42 m2/g. Ultrasonic-synthesized nickel catalysts, due to their higher specific surface area and better nickel distribution on the synthesized catalyst, 17% by weight of vanadium oxide based on UIO-66 were able to 5.98% conversion and with 55.7% selectivity of propylene at 325 oC.

This research work aims to investigate the sorption of nickel ions from an aqueous solution using Activated Carbon modified by Sodium Dodecyl Sulfate (AC-SDS). The sorption process by the batch method is carried out. The characterization of the adsorbent structure was studied by FT-IR, SEM, and BET. The effect of pH, contact time, initial concentration, and temperature were investigated. The optimum condition of nickel sorption onto AC-SDS was found to be: a sorbent dose of 1 g in 100 ml of nickel ions, contact time of 300 min, pH=8, in optimum condition removal efficiency was 95.18% for nickel. Three equations, i.e. Morris Weber, Pseudo first order, and pseudo-second-order have been tested to track the kinetics of the removal process. The Langmuir, Freundlich, and R-P are subjected to sorption data to estimate sorption capacity. It can be concluded that AC-SDS has the potential to remove nickel ions from an aqueous solution at different concentrations. In addition, the effect of temperature on the process was investigated. It was found that the temperature has a positive effect on the process and the negative ΔG values indicated the thermodynamically feasible and spontaneous nature of the sorption. The positive value of ΔS reveals the increased randomness at the solid–solution interface during the fixation of the ion on the surface of the sorbent.

Carbon dioxide photocatalytic reduction is one of the promising methods used to produce a wide range of renewable hydrocarbon fuels using sunlight in the presence of photocatalysts. In this study, a series of nickel-doped titanium dioxide samples (0.5, 1, and 1.5 wt%) Were synthesized by Sol-gel method. After performing photocatalytic carbon dioxide recovery experiments and finding the optimum percentage of nickel, titanium dioxide sample with 1 wt% nickel (TNi1) showed the highest photocatalytic activity. Then, by impregnation method, 3% by weight of Cu (1, 2 and 3 wt%) was loaded onto the TNi1 structure. Finally, the sample loaded with 1 wt% copper on titanium dioxide doped with 1 wt% Ni (1Cu/TNi1) showed the highest photocatalytic activity and methane production was 12.6 μmol/gcat that was about 4 times higher than the amount of methane produced in the presence of pure TiO2. The synthesized nanophotocatalysts were characterized using X-ray diffraction (XRD) analysis, diffuse reflectance spectroscopy (DRS) analysis and photoluminescence (PL) analysis. Also, their specific surface area was measured by BET method and morphology of the particles was investigated by field emission scanning electron microscopy.

In this paper, the effect of CTAB and Triton X-100 surfactants as nickel corrosion inhibitors in alkaline solution at three temperatures of 25, 40, and 60 0C was investigated. The Tafel polarization method was used to determine the corrosion potential, corrosion current intensity, and anodic and cathodic Tafel slopes. The inhibition performance of these two surfactants was studied separately and also in the form of a mixture of these two surfactants with different ratios. The results showed that in all three temperatures, by adding the surfactant to the medium, the nickel corrosion rate was reduced. The obtained optimum concentration for CTAB and Triton X-100 was 150 ppm and 200 ppm, respectively. The results of the adsorption isotherms showed that the adsorption of CTAB and Triton X-100 followed the Langmuir model. The synergistic effect of these two surfactants was also investigated and results showed that when the mixture of the two surfactants was used the inhibition efficiency was increased significantly which indicated the better performance of the surfactants mixture for the protection of nickel.

Environmental Protection Agency of America has classified heavy metals such as Cd, Hg, As, Ni, Pb and Cr, as the toxic pollutants of environment. These elements imported into the environmental cycle by the chemical industries and other industries, such as water, agricultural products and human body, and ultimately its harmful effects on human. In this respect, separating and removal of heavy metals is an important task in controlling environmental pollutants. In the recent years the usage of nanoparticles as an adsorbent with high adsorption efficiency has attracted a lot of attention. Nano graphene oxide used in this study is classifying in the category of high capacity adsorbents due to its high specific surface area. In this study in addition to graphene oxide, Almond shell and Carboxymethyl cellulose were also used to improve the removal efficiency of heavy metals. The aim of this research is to synthesize Graphene oxide nanoparticles modified with Almond shell and Carboxymethyl cellulose and also to evaluate its performance in the removal of nickel and cadmium from water. The Nano Graphene oxide was synthesized by the Freeze- drying method and in order for characterization of the synthesized nanoparticles, FT-IR and SEM methods were used. Various parameters such as pH solution, contact time and adsorbent amount were investigated and the optimal values of each of factors were determined. The modeling of the absorption process was carried out using two models of Langmuir and Freundlich isotherms and the results show that the adsorption rate is consistent with the Langmuir isotherm model for nickle and Freundlich isotherm for the adsorption of cadmium. The results showed that the modified nanoparticles have better absorption capacity than unmodified ones, and its effectiveness to remove the element of Cd is more than Ni.

The structure of [NiLCl]Cl•H2O (2), which synthesized by condensation reaction of 2-(3-(2-formylphenoxy)-2-hydroxypropoxy)benzaldehyde and 1,3-diamino-2-propanol in the presence of NiCl2•6H2O at methanol, has been determined by single-crystal X-ray diffraction. Distorted octahedral coordination environment around Ni(II) ion is constructed by two imine nitrogen atoms, two ether oxygen atoms, one alcohol oxygen atom, and one chloride anion. The complex (2) is pesudopolymorph for the previously reported [NiLCl]Cl•0.75H2O (1) complex [1]. There are two formula units [NiLCl]Cl per asymmetric unit of both complexes. Each asymmetric unit of (1) and (2) includes two water molecules of crystallization, although one of the two water molecules in (1) has half-site occupancy. The optimized structure of (2) and similar compounds by Cl replacement with Br and I in DFT/B3LYP level of theory using LANL2DZ (for nickel and halogen) and 6-31G(d,p) (for the other elements) basis sets illustrate good agreement with experimental ones. Based on optimized structures of three compounds, their polarizability and hyperpolarizability were calculated at the same level to predict their nonlinear optical(NLO) properties. The calculated NLO values of the compounds are much greater than the corresponding value of urea.

Sulfur nanoparticles were synthesized via W/O microemulsion method. A comparison study was performed between synthesized sulfur nanoparticles and sulfur micro particles for extraction and preconcentration of nickel ions from different water samples prior to determination by FAAS. The effects of the analytical parameters including pH of the sample solution, sample matrix, eluting solution conditions, flow rate of sample solution, sample volume and interfering ions were investigated for each adsorbent and the optimum values were obtained. The effect of the size of sulfur adsorbent on the extraction efficiency was evaluated. Under the optimum experimental conditions, preconcentration factor, analytical detection limit, adsorption capacity, reusability of the sorbent and flow rate of sample solution were obtained for sulfur microparticles as100, 0.00180 µg/mL, 15.75µg/g, maximum 10 cycles and 1 ml/min respectively. Whether, using sulfur nano particles these amounts were obtained as 166.67, 0.00108 µg/ml, 30.08 µg/g, >70 cycles and 5 ml/min, respectively. These results showed that, sulfur nano particles adsorbent will cause to higher preconcentration factor, lower detection limit, higher adsorption capacity, more reusability of the sorbent and faster extraction of the analyte.The proposed method was applied for determination of nickel ions in tap, river and spring water samples using each of these adsorbents.

In this study, an electrochemical sensor based on carbon monoxide-modified (CP) polymer modified molecule (MIP) polymer was designed and used to determination of nickel ions. The nickel benzoate complex, 2- Hydroxyethyl methacrylate, 2, 2. Azobutyl-isobutylnitrile and ethylene glycol di-methacrylate were used for polymer molecular prepared. Then, a modified carbon electrode was made using polymer prepared for determination of  nickel ions in aqueous sulotion. Some factors such as pH, temperature, percent composition of the imprinted polymer and the electrode have been studied. The electrode exhibits a Nernstian response for Ni+2 over a wide concentration range (1.00 × 10-1 – 1.00 × 10-10 M) with a slope of 30/66±0.4 mV per decade. It displays a response time of about 5 s and can be used for a period of 10 weeks with good reproducibility. The detection limit obtained in the optimal conditions was 5.00×10-9 M. It concluded that the electrode can successfully use for potentiometric determination of Ni2+ in some waste water samples.

 A new method for the separation and preconcentration of trace amounts of nickel in food and water samples by magnetic solid phase extraction (MSPE) with modified Fe3O4 magnetic nanoparticles and its determination by flame atomic absorption spectrometry has been developed. For this purpose, the modification of the nanoparticles was performed by surfactants cetyltrimethylammonium bromid. The extraction of nickel ions from the aqueous solution was performed with &alpha-Furildioxime as the chelating agent. The varius parameters affecting the extraction and preconcentration of nickel were investigated and optimized. Under the optimal conditions, the calibration curve showed an excellent linearity in the concentration range of 1-100 µg L-1 and the limit of detection was 0.3 µg L-1 of nickel. The developed method was successfully applied to the determination of nickel in food and water samples. The relative recoveries for determination of nickel in food and water samples was between 96/0-99/5% and 97/3-103/0%, respectively. The results showed that, magnetic nanoparticles can be used as a cheap and efficient adsorbent for the extraction and preconcentration of nickel from real samples.

In this study heterogeneous cation exchange membranes based on PVC were prepared by using tetrahydrofuran as solvent and cation exchange resin powders. The membranes were fabricated by solution casting technique. At first, the effect of polymer binder sulfonation and its concentration in the casting solution on electrochemical properties of membranes was studied. Then, superior membrane was modified again by using of iron-nickel oxide nanoparticles.The obtained results showed that increase of sulfonated polymer’s concentration in membrane matrix caused to increase of membrane water content (from 29.4% to 35.1%) and ion exchange capacity (from 2.7 to 3.2). Moreover, prepared membranes exhibited suitable transport number and selectivity between 91%-93% and 85%-89% respectively. Ionic flux was increased initially by increase of sulfonated polymer concentration up to 80 %wt in membrane matrix and then decreased again by more increase in S-polymer content from 80 to 100 %wt. Membrane electrical resistance also was declined up to 27.6% by increase of S-polymer’s ratio in membrane matrix. Furthermore, using of iron-nickel oxide nanoparticles in membrane matrix caused to improvement of membrane electrochemical characteristics obviously. The modified nanocomposite membranes exhibited more appropriate separation performance compared to un-modified ones.The obtained results are useful for electro-membrane processes especially electrodialysis in water recovery and treatment.

In this study, we investigate the direct electron-transfer reactivity of immobilized hemoglobin (Hb) onto the surface of a carbon paste electrodes (CPE) modified with nanocomposite consist of iron-nickel alloys and multi-walled carbon nanotubes. Fe-Ni nanocrystals were synthesized by a simple chemical method and then by various methods such as scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) have been characterized. The simultaneous presence of nanocrystals of nickel-iron (Fe@Ni) and multi-walled carbon nanotubes (MWCNT) in structure of modified electrode provides a unique structure for reliable and effective interaction of Hb whit surface of electrode. The immobilized Hb maintains its bioactivities and displays an excellent electrochemical behavior. The biosensor was used to catalyze the reduction of hydrogen peroxide. The electrochemical behavior of modified electrode by various techniques such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were evaluated. The electrocatalytic response showed a linear dependence on the H2O2 concentration ranging widely from 5.0 to 250.0 µM with a detection limit of 1.43 µM.

Biological uptake of heavy metals is a very effective process for removing these pollutants from aqueous solutions is considered.Algae cell wall composition of cellulose and other materials such as agar, alginate and the metal ions play a key role in biosorption. Algae are of particular importance due to their low cost. Mechanisms are involved in the uptake of metals by bacteria is very complex and depends on physicochemical reactions of metal ions in solution, and so are the locations of cellular uptake. Microorganisms and algae contribute to the cycle of inorganic substances in nature.In this study the biological uptake of nickel by red algae Gracilaria, brown algae Cystoseira, Fucus and Gram-positive bacteria Bacillus, was studied.Parameters such as metal concentrations, pH, amount of algae, kinetic, and isotherms were studied in this experiment. The maximum rates of metal uptake by algae Gracilaria, Cystoseira and Bacillus at pH=6 and Fucus on the pH is about 5. The maximum nickel sorption was attained about for Fucus, Gracilaria, Cystoseira, and Bacillus, 0.94, 0.68, 0.34 and 0.65 mg/L respectively. This study has shown nickel (II) uptakes, equilibrium time of about 400,350,300 and 120 minutes for, Gracilaria, Cystoseira, Fucus and Bacillus, respectively, and the adsorption equilibrium date was well described by Langmuir equation.

In recent years, nano Zero valent iron (nZVI) have been used to remediate from polluted groundwater. However the application of nZVI has limitations such as particles agglomeration and filtration of nano particles. This research has been conducted to enhance the usability of nZVI by supporting with diatomite during synthesis. The characterization for nZVI particle and dolomite supported (D-nZVI) was performed using XRD, SEM/EDAX, TEM, and BET-N2.nZVI, D-nZVI and pure diatomite are used as adsorbents and nickel solution were applied as heavy metal adsorbents to remove the aqueous Ni2 ions and varying factors including adsorbent dosage, solution pH, contact time, and initial metal concentration have been investigated. The Langmuir and Freundlich adsorption isotherm models over a wide initial concentration dosages were used in order to determine the adsorbents adsorption capacity that results showed that D-nZVI has a higher adsorption capacity, and Also fitting the data using these models showed that the adsorption of all adsorbents are in good agreement with the Langmuir model. The adsorption capacity of the above adsorbents were found, 66.67, 166.67, 13.16 mg/g, respectively .The removal kinetics were modeled by pseudo first-order and pseudo second-order models and the results showed that removal of Ni2 by all adsorbents could be better expressed by pseudo second-order kinetics.

Clays and clay minerals specially montmorillonite and bentonite are widely used for environmental pollution control. The heavy metals are important environmental pollutants. In this study the sorption of copper, zinc and nickel ions as heavy metals by bentonite samples was investigated. Sample 1 from Kheir Abad mine, sample 2 from Tange Ghoochan mine and sample 3 from the mine around the Ravari mosque were prepared. The sorption tests of copper, zinc and nickel ions by Kheir Abad Ca- bentonite sample were done. The results showed that the sorption very fast and for doing all tests the appropriate time was obtained 5 minutes. Also the results showed that the reduction of pH causes the reduction of copper, zinc & nickel ions sorption and also appropriate conditions for sorption of each ions were achieved. The sorption tests by other samples in obtained appropriate conditions for sample 1 were done. The results showed that among these samples, sample 2 has the highest percentage of sorption and sample 3 has the lowest percentage of sorption. Also the results showed that the increase of CEC causes the increase of copper, zinc & nickel ions sorption. and sorption of nickel is less than sorption of copper and zinc. Finally these samples can be an excellent and inexpensive sorbent for copper, zinc and nickel ions as heavy metal.