Concentration Of Complexing Agent Research Articles

Quantification of Se(IV) and Co(II) in Macrobrachium lamarrei, fresh water prawns and their feeding materials

Simple, sensitive and rapid methodology was developed for the separation and identification of selenium(IV) and cobalt(II) in Macrobrachium lamarrei, fresh water prawn samples and their feeding materials after pre-capillary complexation with ammonium piperidine-1-carbodithioate (APC) by using capillary electrophoresis. Microwave assisted procedure was adapted to analyze selenium(IV) and cobalt(II) in prawn samples which was eco-friendly to environment. Various parameters such as effect of pH, effect of complexing agent concentration, buffer nature, applied voltage and interferences by other metal ions were also investigated to enhance the sensitivity and detection limits of the present method. The obtained results were in good agreement and correlated with AAS method in terms of Student's “t”-test and Variance ratio “f”-test. The method was applied for the analysis of selenium(IV) and cobalt(II) in various M. lamarrei, fresh water prawn samples and their feeding materials.

Effect of lactic acid on nucleation morphology and surface roughness of electroless Ni–P deposition in nanoscale

The present work aims to study effect of lactic acid concentration as complexing agent on surface roughness and nucleation morphology of electroless N–P deposition. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) have been used to study nucleation morphology and surface roughness of deposition. Deposition process started at some initial priority growing centres independently distributed on the substrate. We found that the morphology and surface roughness of deposition strongly depends on the complexing agent concentration. Morphology of initial deposited centres with no concentration of lactic acid was in coniform structure. By increasing the complexing agent concentration, the structure of initial growing centres changed from coniform to nodular shape and the surface roughness of depositions decreased.

Determination of arsenic in chicken feed by hydride generation atomic absorption spectrometry after pre-concentration with polyurethane foam

A pre-concentration procedure with solid-phase extraction was developed for the determination of arsenic (As) in chicken feed using hydride generation atomic absorption spectrometry (HG-AAS). The procedure was based on the sorption of As(III) ions as complexes with ammonium pyrrolidine dithiocarbamate onto a mini-column packed with polyurethane foam. After pre-concentration, the As was removed from the mini-column by acid solution, and the analyte content in the eluate was measured by HG-AAS. The following main experimental conditions were established: adjustment of the As solution pH with 0.05 mol l−1 HCl, 2.88 × 10−3 mol l−1 complexing agent concentration and 6.0 mol l−1 eluting hydrochloric acid concentration. The proposed method produced an enrichment factor of 67, with 0.050 and 0.165 µg g−1 limits of detection and quantification, respectively. The procedure was applied to the determination of As content in two types of chicken feed using the proposed procedure and atomic absorption spectrometry with electrothermal atomisation (ETAAS). The t-test indicated that the results were not significantly different at a confidence level of 95%.

Characterization of AB<sub>5</sub>-Type Metal Hydride Modified by Electroless Plating Nickel

The charge/discharge properties of commercial metal hydride alloy powder (MmNi3.81Mn0.41Al0.19Co0.76) is improved and modified by electroless plating nickel. The effect of concentration of reducing agent (Cr), concentration of complex agent (Cc), reaction temperature (T), reaction time (t), and the amounts of MH powder per volume (CMH) on the utilization of the modified MH alloy used as the negative electrode of Ni/MH battery is systematically studied. The utilization of modified MH alloy is mainly affected by Cr, Cc and t. The utilizations of MH alloys modified with condtions of T = 70 oC, t = 90 min, Cr = 20 g l-1, Cc = 20 g l-1 and CMH = 20 g l-1, respectively, are obtained to be 92.3, 64.7 and 23.6% at discharging rate of 1, 4, and 10 C. The utilizations of modified MH alloy are increased by 15.5, 45.6 and 19.8% compared with the pristine MH alloy for discharging rates of 1, 4 and 10 C, respectively.

Cloud Point Extraction of Copper, Lead, Cadmium, and Iron Using 2,6-Diamino-4-Phenyl-1,3,5-Triazine and Nonionic Surfactant, and Their Flame Atomic Absorption Spectrometric Determination in Water and Canned Food Samples

A cloud point extraction procedure was optimized for the separation and preconcentration of lead(II), cadmium(II), copper(II), and iron(III) ions in various water and canned food samples. The metal ions formed complexes with 2,6-diamino-4-phenyl-1,3,5-triazine that were extracted by surfactant-rich phases in the nonionic surfactant Triton X-114. The surfactant-rich phase was diluted with 1 M HNO3 in methanol prior to its analysis by flame atomic absorption spectrometry. The parameters affecting the extraction efficiency of the proposed method, such as sample pH, complexing agent concentration, surfactant concentration, temperature, and incubation time, were optimized. LOD values based on three times the SD of the blank (3Sb) were 0.38, 0.48, 1.33, and 1.85 microg/L for cadmium(II), copper(II), lead(II), and iron(III) ions, respectively. The precision (RSD) of the method was in the 1.86-3.06% range (n=7). Validation of the procedure was carried out by analysis of National Institute of Standards and Technology Standard Reference Material (NIST-SRM) 1568a Rice Flour and GBW 07605 Tea. The method was applied to water and canned food samples for determination of metal ions.

Separation and analysis of lanthanides by isotachophoresis coupled with inductively coupled plasma mass spectrometry

This study is a large project initiated by the French Nuclear Agency, and concerns the development of a new electrolyte system for the separation of lanthanides by isotachophoresis. This new system is based on a leading electrolyte that incorporates 2-hydroxy-2-methylbutyric acid as complexing agent. The optimization of separation conditions (complexing agent concentration, pH, capillary dimensions, injection conditions, and current intensity) performed by experiments on a commercial capillary instrument with contactless conductivity detection, which allows to improve the separation of 13 lanthanides (La to Lu, except Pm and Ho). We have also directly coupled the isotachophoresis to an inductively coupled plasma mass spectrometer to visualize the mono-elementary elution bands and demonstrate the potentiality of the method for isotope ratio measurements. The application to a simulated solution representative of a fraction of fission products present in a MOX spent fuel is presented in this paper to demonstrate the possible application in future on nuclear fuel samples.

Modeling the electroless nickel deposition on aluminum nanoparticles

In this study, Ni coated aluminum nanoparticles were fabricated by electroless nickel deposition. Effect of two groups of parameters on the process plating rate were investigated: bath composition (main salt, reducing agent and complexing agent concentration) and process parameters (pH, plating time and bath temperature). Simulation of the process was performed using artificial neural network (ANN) media. Based on the presented model it is possible to design a high efficiency electroless bath, while minimum received materials are used and maximum plating rate is obtained. According to the model's results, 0.07mol/l NiSO4·2H2O, 0.245mol/l NaH2PO2·H2O and 0.098mol/l Na3C6H5O7·H2O were chosen as the optimum electroless bath composition. The optimum bath parameters also were selected as pH of 9.5, temperature of 80°C and 30min of plating. At such condition, the most efficient Ni deposition, with maximum plating rate of 45%, was acquired on the surface of aluminum particles. These samples were characterized by scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The results showed that a low phosphorus and nanocrystalline Ni layer, with about 30nm thickness, has been coated on the aluminum nanoparticles.

Properties of ZnS Thin Films Prepared by CBD under Different Concentration of Complexing Agent

ZnS thin films were deposited on glass substrates using chemical bath deposition. The zinc sulfate and thiourea were used as precursors along with a stable complexing agent of sodium citrate in ammonia/ammonium chloride (pH=10.5) buffer solution. The ratio of Zn and complexing agent was changed from 6:1 to 1:1 by varying concentrations of the complexing agent. X-ray diffraction (XRD), scanning electron microscope (SEM) and UV-vis spectrophotometer were used to investigate the structure, micrograph and optical characteristics of the ZnS thin films respectively. The concentration of sodium citrate has an effect on the crystalline size and crystallization. For the as-deposited thin films, the values of transmittances and Eg are about 85% and 3.8 eV respectively. However, they are decreased to 75% and 3.4 eV respectively after annealing. In addition, the concentration of the complexing agent has no remarkable influence on both the transmittance and the energy gap. The results show that the ZnS thin films with resistivity of 4.34×104 Ωcm are suitable for optoelectronic applications.

Selective transport of cobalt (II) from ammoniacal solutions containing cobalt (II) and nickel (II) by emulsion liquid membranes using 8-hydroxyquinoline

The selective transport of cobalt (II) from ammoniacal solutions containing nickel (II) and cobalt (II) by emulsion liquid membranes (ELMs) using 8-hydroxyquinoline (8-HQ) as extractant has been presented. Membrane solution consists of a diluent (kerosene), a surfactant (ECA 4360J), and an extractant (8-HQ). Very dilute sulphuric solution buffered at pH 5.0 has been used as a stripping solution. The ammoniacal feed solution pH was adjusted to 9.0 with hydrochloric acid. The important variables governing the permeation of cobalt (II) have been studied. These variables are membrane composition, pH of the feed solution, cobalt (II) and nickel (II) concentrations of the feed solution, stirring speed, surfactant concentration, extractant concentration, complexing agent concentration and pH of the stripping solution, and phase ratio. After the optimum conditions had been determined, it was possible to selectively transport 95.0% of cobalt (II) from ammoniacal feed solution containing Co 2+ and Ni 2+ ions. The separation factors of cobalt (II) with respect to nickel (II), based on initial feed concentration, have experimentally found to be of as high as 31 for equimolar Co(II)–Ni(II) feed solution.

Characterization of AB<sub>5</sub>-Type Metal Hydride Modified by Electroless Plating Nickel in Forming Process

Metal hydride (MH) alloy (MmNi3.81Mn0.41Al0.19Co0.76) is modified by the electroless nickel plating and used as the electroactive material of negative electrode in Ni/MH batteries. The effect of the concentrations of reductant (NaH2PO2×H2O), complex agent (Na3C6H5O7×2H2O), reaction time, and reaction temperature on the Ni loadings and the utilization of the modified MH are systematically studied. The experimental results reveal that the appropriate reaction time and temperature of electroless nickel plating are 30 min and 70 °C in this work. The loading amount of Ni-P on MH alloy is increased and decreased by increasing the concentration of reductant and complex agent, respectively. The steady utilization of unmodified MH alloy is 94.7±1.0 % in the forming process under the charge/discharge conditions of 0.2C charge to 160% SOC (state of charge) and 0.2C discharge to 0.95V. The utilization of MH alloys modified with conditions of [NaH2PO2×H2O] = 40 g L-1 and [Na3C6H5O7×2H2O] = 20 g L-1, T = 70 °C, t = 30 min and [MH] = 2g/100 ml, respectively, is improved to 101.9±0.3 %.

The Effect of Complexing Agent on the Surface of Aluminum Alloy Plating Ni-P Alloy

In this paper, the effect of different concentrations of complexing agent on the surface of aluminum alloy plating Ni-P alloys is studied. Study the influence of malic acid complexing agents on the electroless Ni-P alloy deposition rate, morphology, corrosion resistance, and determine the optimal complexing agent concentration. The results show that when the malic acid concentration is 24g /L, the deposition rate gets to maximum, and coating uniformity, structure compact and corrosion resistance is best.

Effects of the Functional Groups of Complexing Agents and Cu Oxide Formation on Cu Dissolution Behaviors in Cu CMP Process

Cu dissolution behaviors with select reagents (malonic acid, glycine, malic acid, citric acid) were investigated in terms of the functional groups of complexing agents. Based on the results of Cu dissolution rate testing at various values, as well as UV–visible analysis with the addition of cupric ions, reaction mechanisms and effects of each functional group are proposed. The effect of Cu oxide formation on the Cu dissolution rate was also investigated by monitoring Cu dissolution rates with various concentrations and complexing agent concentrations. Additionally, the effect of the addition of corrosion inhibitor (5-aminotretrazole) on Cu dissolution was investigated. By combining the experimental results, we interpreted the Cu dissolution behaviors based on a competitive contribution from Cu oxide formation and complex formation between Cu (Cu oxide) and the complexing agent.

A novel solidified floating organic drop microextraction method for preconcentration and determination of copper ions by flow injection flame atomic absorption spectrometry

A rapid, simple and cost effective solidified floating organic drop microextraction (SFODME) and flow injection flame atomic absorption spectrometric determination (FI-FAAS) method for copper was developed. In this method, a free microdrop of 1-undecanol containing 1,5-diphenyl carbazide (DPC) as the complexing agent was transferred to the surface of an aqueous sample including Cu(II) ions, while being agitated by a stirring bar in the bulk of the solution. Under the proper stirring conditions, the suspended microdrop can remain at the top-center position of the aqueous sample. After the completion of the extraction, the sample vial was cooled by placing it in a refrigerator for 10 min. The solidified microdrop was then transferred into a conical vial, where it melted immediately and diluted to 300 μL with ethanol. Finally, copper ions in 200 μL of diluted solution were determined by FI-FAAS. Several factors affecting the microextraction efficiency, such as type of extraction solvent, pH, complexing agent concentration, extraction time, stirring rate, sample volume and temperature were investigated and optimized. Under optimized conditions for 100 mL of solution, the preconcentration factor was 333 and the enrichment factor was 324. The limit of detection (3 s) was 0.4 ng mL −1, the limit of quantification (10 s) was 1.1 ng mL −1 and the relative standard deviation (RSD) for 10 replicate measurements of 10 ng mL −1 copper was 0.9%. The proposed method was successfully applied to the determination of copper in different water samples.

Characterization of Cl-doped n-type Cu 2O prepared by electrodeposition

N-type doping of cuprous oxide (Cu 2O) films by chlorine (Cl) during electrodeposition was reported by the authors recently. A more detailed study on the effects of doping conditions on electrical properties of Cl-doped Cu 2O is presented in this paper. The resistivity of Cl-doped Cu 2O is affected by doping conditions, including Cu and Cl concentrations, different Cu and Cl precursors, complexing agent concentration, solution pH, and deposition temperature. It is believed that these conditions control the amount of Cl incorporated into the Cu 2O films, thus the doping level. The lowest resistivity obtained so far is 7 Ω-cm, suitable for solar cell applications. Photocurrent-potential measurements verify the n-type conductivity of Cl-doped Cu 2O. Scanning electron microscopy indicates a small grain size of around 100 nm in Cl-doped Cu 2O. X-ray diffraction confirms Cu 2O as the only detectable phase in the film.

Effect of chelating agents on mobilization of metal from waste catalyst

DTPA and EDTA are synthetic chelating agents used in many industrial applications, because of their low biodegradability and strong complexing capacities. These chelating agents can transfer toxic heavy metals from solid to liquid phase. The mobilization of Ni from waste catalyst in the presence of two synthetic organic ligands (polycarboxylate, EDTA and DTPA) was investigated as a function of complexing agent concentration and reaction time to determine necessary equilibrium time and catalyst to liquid ratio. The concentration of chelate ranged from 0.2 M to 1 M and extraction of Ni increased dramatically with increasing chelate concentration. The precipitation of Ni was obtained as NiSO4. The recovery of Ni with EDTA and DTPA was 87% and 95%, respectively. This mobilization is the result of a competition between association with the solid phase and dissolved complexes. Coordination capacity with nickel and recovery in recycling of EDTA was observed slightly less compared to DTPA with same conditions. Extraction efficiency and reusability of both chelating agents are compared in the present study.

Direct assembly of ZnO nanostructures on glass substrates by chemical bath deposition through precipitation method

In this work, spindle/flower-like zinc oxide (ZnO) nanostructured arrays have been directly grown on glass substrates using triethanolamine (TEA) as a complexing agent by chemical bath deposition (CBD). Control over the morphology of ZnO nanocrystallites was achieved by varying the concentration of the complexing agent in the bath solution. ZnO crystallites exhibited a hexagonal wurtzite structure with preferential orientation along the c-axis. The morphology of the ZnO crystallites with star or needle-like spindles was altered to flower like nanostructures by adjusting the complexing agent concentration. Compared to as-deposited films, films sintered at 300 ∘C exhibited a sharp UV emission due to a decrease in the defect density. A possible growth mechanism for obtaining ZnO nanoflower arrays without a seed layer on glass substrates has been discussed.

Low-cost Preparation and Photoelectric Property Study of PbSe Nanocrystalline Films

PbSe nanocrystalline films were deposited on glass substrates by chemical bath using the Pb(Ac)2 solution and Na2SeSO3 solution as the reactants. Effect of the concentration of complexing agent ([OH-]) in the chemical bath on the crystal structure,morphology and electric-optical property of the film were investigated. The results indicate that crystal size of the film is about 10nm which is correlated with the complexing agent concentration. With low concentration of [OH-],the film is uniform and compact,whereas it becomes loose and discontinuous with high concentration of [OH-]. Optical transmission spectra show a blue shift of the absorption edge from 5μm to 1μm in the as-grown films,and the absorption edge moves to longer wavelength after annealing at 300℃. The as-grown film shows a huge sheet resistant (10GΩ),and the sheet resistant obviously decrease to 10kΩ～100MΩ after annealing in air and in oxygen. Electro-optical performance is studied by measuring the current vs time (i-t) curve at a signal of light pulse. The i-t curves indicate an obvious photoelectrical response in nanocrystalline films at the presence of light. The film annealed in air has a slow-electro-optical performance,whereas the film annealed in oxygen has a fast response.

Simultaneous preconcentration of copper, zinc, cadmium, and nickel in water samples by cloud point extraction using 4-(2-pyridylazo)-resorcinol and their determination by inductively coupled plasma optic emission spectrometry

A procedure for simultaneous separation/preconcentration of copper, zinc, cadmium, and nickel in water samples, based on cloud point extraction (CPE) as a prior step to their determination by inductively coupled plasma optic emission spectrometry (ICP-OES), has been developed. The analytes reacted with 4-(2-pyridylazo)-resorcinol (PAR) at pH 5 to form hydrophobic chelates, which were separated and preconcentrated in a surfactant-rich phase of octylphenoxypolyethoxyethanol (Triton X-114). The parameters affecting the extraction efficiency of the proposed method, such as sample pH, complexing agent concentration, buffer amount, surfactant concentration, temperature, kinetics of complexation reaction, and incubation time were optimized and their respective values were 5, 0.6 mmol L −1, 0.3 mL, 0.15% (w/v), 50 °C, 40 min, and 10 min for 15 mL of preconcentrated solution. The method presented precision (R.S.D.) between 1.3% and 2.6% ( n = 9). The concentration factors with and without dilution of the surfactant-rich phase for the analytes ranged from 9.4 to 10.1 and from 94.0 to 100.1, respectively. The limits of detection (L.O.D.) obtained for copper, zinc, cadmium, and nickel were 1.2, 1.1, 1.0, and 6.3 μg L −1, respectively. The accuracy of the procedure was evaluated through recovery experiments on aqueous samples.

Cloud Point Extraction of Acetic Acid from Aqueous Solution

A new acetic acid separation method was developed through a successful combination of cloud point extraction and complex extraction technology (CPE-SE), where an acetic acid complex compound formed and was solubilized in a surfactant micelle solution, instead of an organic solvent, and then concentrated into one phase by a phase separation process of the CPE technology. Since no organic solvent diluents were used, the new process was environmentally friendly and with a lower cost; meanwhile, the high selectivity of the complex extraction based on chemical complexation and high efficiency of CPE were also inherited as advantages over conventional solvent extraction process. In consideration of the compatibility and the related CPE characteristics, tributyl phosphate and PEG/PPG-18/18 Dimethicone were selected as complexing agent and surfactant of the CPE-SE system, respectively, and the extraction system was optimized by studying the effect of the main process parameters, including surfactant and complexing agent concentration, temperatures for the stirring and incubation steps, on the recovery and the distribution coefficient. A relative high recovery of 71.4% and a distribution coefficient of 1.4 were achieved simultaneously with the optimized process in the treatment of 0.1 M acetic acid solution. Based on its competitive extractability, high efficiency, low-cost, and environment friendlyness, the CPE-SE process was expected to be a potential separation method for a dilute acetic acid solution.

Selective extraction of nickel from ammoniacal solutions containing nickel and cobalt by emulsion liquid membrane using 5,7-dibromo-8-hydroxyquinoline (DBHQ) as extractant

The selective extraction and concentration of nickel from ammoniacal solutions containing nickel and cobalt by an emulsion liquid membrane (ELM) technique using 5,7-dibromo-8-hydroxyquinoline (DBHQ) as extractant has been presented. ELM consists of a diluent (kerosene), a surfactant (Span 80), an extractant (DBHQ), a modifier (tributyl phosphate), and a stripping solution (very dilute sulfuric acid solution containing EDTA as complexing agent, buffered at pH 4.25). Cobalt (II) in feed solution with 6 mol/L ammonia was oxidised to Cobalt (III) by H 2O 2 and pH of this ammoniacal solution was adjusted to 10.0 with the addition of hydrochloric acid (HCl). The important variables governing the permeation of nickel and their effect on the separation process have been studied. These variables were membrane composition, ammonia concentration in the feed solution, mixing speed, surfactant concentration, extractant concentration, pH of the feed and the stripping solutions, complexing agent concentration in the stripping solution, and phase ratio. After the optimum conditions had been determined, it was possible to selectively extract 99% of nickel from the ammoniacal solutions containing Ni and Co. The separation factors of nickel with respect to cobalt, based on initial feed concentration, have experimentally found to be of as high as 88.1 for about equimolar Co–Ni feed solutions.