Metal Salt Solutions Research Articles

Synthesis and Serviceability of New Symmetric Bis-pyrazolone Metal Complex Acid Dyes

Synthesis of new symmetric bis-pyrazolone acid dye and its 3d transition metal complexes is studied. Bis-pyrazolone is synthesized from (E)-6,6’-(ethene-1,2-diyl)bis(3-hydrazinylbenzenesulfonic acid) and ethyl ace-toacetate. The synthesized bis-pyrazolone is coupled with diazonium salt of 4-sulpho-2-aminophenol in alkaline medium targeting bis-pyrazolone ligand acid dye. Various metal complexes are obtained by treating a methanolic solution of metal salts with ligand acid dye in basic media. Structures of the synthesized ligand dye and its metal complexes are confirmed by UV-Vis, FTIR, and NMR spectra. The ligand acid dye and metal complex dyes demonstrate absorption in UV-Vis in the range of 400–600 nm. Ligand acid dye and its metal complexes demonstrate good to high value of light speed, washing fastness and rubbing fastness on leather.

Robust Synthesis of Gold‐Based Multishell Structures as Plasmonic Catalysts for Selective Hydrogenation of 4‐Nitrostyrene

AbstractA robust self‐template strategy is used for facile and large‐scale synthesis of porous multishell gold with controllable shell number, sphere size, and in situ surface modification. The process involved the rapid reduction of novel Au‐melamine colloidal templates with a great amount of NaBH4 in presence of poly(sodium‐p‐styrenesulfonate) (PSS). After soaking the templates in other metal salt solution, the obtained bimetallic templates could also be generally converted into bimetallic multishell structures by same reduction process. In the hydrogenation of 4‐nitrostyrene using NH3BH3 as a reducing agent, the porous triple‐shell Au with surface modification (S‐PTSAu) exhibited excellent selectivity (97 %) for 4‐aminostyrene in contrast with unmodified triple‐shell Au. Furthermore, it also showed higher enhancement of catalytic activity under irradiation of visible light as compared to similar catalysts with fewer shells.

Robust Synthesis of Gold-Based Multishell Structures as Plasmonic Catalysts for Selective Hydrogenation of 4-Nitrostyrene.

A robust self-template strategy is used for facile and large-scale synthesis of porous multishell gold with controllable shell number, sphere size, and in situ surface modification. The process involved the rapid reduction of novel Au-melamine colloidal templates with a great amount of NaBH4 in presence of poly(sodium-p-styrenesulfonate) (PSS). After soaking the templates in other metal salt solution, the obtained bimetallic templates could also be generally converted into bimetallic multishell structures by same reduction process. In the hydrogenation of 4-nitrostyrene using NH3 BH3 as a reducing agent, the porous triple-shell Au with surface modification (S-PTSAu) exhibited excellent selectivity (97 %) for 4-aminostyrene in contrast with unmodified triple-shell Au. Furthermore, it also showed higher enhancement of catalytic activity under irradiation of visible light as compared to similar catalysts with fewer shells.

Biomimetic Green Synthesis and Characterization of Nanoparticles from Leave Extract of Lavatera cretica and Their Improving Glucose Bigotry

This study aims to examine the biosynthesis and characterization of silver nanoparticles using Lavatera cretica (LCAgNPs) leaf extract mixed with silver nitrate and improving their glucose bigotry. The biosynthesis was first confirmed by the color change from colorless (metal salt solution) to brown (nanoparticle colloidal dispersion). The occurrence of the nanoparticles was further ascertained by several physicochemical studies including UV–Vis spectroscopy, transmission electron microscopy (TEM), energy dispersive X-ray (EDX) tomography, Fourier transform-infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The UV–Vis spectroscopy of LCAgNPs indicated the surface plasmon resonance signature of Ag NPs at around 440 nm. The TEM analysis revealed a well-dispersed sphere that varied in size from 5 to 24 nm. The EDX results established that Ag was the major element and others such as C, O and Cl were also present, which specified that the biomolecules coincided the AgNPs. The FT-IR spectroscopic study exhibited that the functional groups such as O–H, C–O, N–H, C–H and C=O were accountable for the synthesis of AgNPs. The XRD pattern represented the crystalline nature of metallic Ag. In this results, it could be clinched that the silver nitrate was reduced to silver nanoparticles of small size and high stability, which were devoid of impurities. Hence, this study has proved that L. cretica leaf is a good source for the synthesis of AgNPs and their improved glucose bigotry.

Structure and Catalytic Behavior of Alumina Supported Bimetallic Au-Rh Nanoparticles in the Reduction of NO by CO

Alumina-supported bimetallic AuRh catalysts, as well as monometallic reference catalysts, were examined with regard to their structural and catalytic properties in the reduction of NO by CO. Depending on the molar ratio of Au:Rh, the nanoparticles prepared by borohydride co-reduction of corresponding metal salt solutions had a size of 3.5–6.7 nm. The particles consisted of well-dispersed noble metal atoms with some enrichment of Rh in their surface region. NO conversion of AuRh/Al2O3 shifted to lower temperatures with increasing Rh content, reaching highest activity and highest N2 selectivity for the monometallic Rh/Al2O3 catalyst. This behavior is attributed to the enhanced adsorption of CO on the bimetallic catalyst resulting in unfavorable cationic Rh clusters Rh+-(CO)2. Doping with ceria of AuRh/Al2O3 and Rh/Al2O3 catalysts increased the surface population of metallic Rh sites, which are considered most active for the reduction of NO by CO and enhancement of the formation of intermediate isocyanate (-NCO) surface species and their reaction with NO to form N2 and CO2.

About changes in the physicochemical properties of aqueous solutions used as a liquid electrolyte cathode

The gas discharge between liquid electrolyte cathode and metal anode was experimentally investigated. Aqueous solutions of sodium chloride, potassium chloride, sodium sulfate, sodium hydroxide, and potassium hydroxide were used as the electrolyte cathode. Decrease aqueous solution was compensated by adding distilled water (solvent) in a continuous mode in the discharge burning process. It was found that, despite the significant dilution with a solvent, the specific electrical conductivity of aqueous solutions of alkali metal salts and alkalis varies slightly.

Biotechnological Method of Obtaining Nanoparticles of Silver, Cadmium, and Zinc Sulfides. Physico-chemical Characteristics. Creation of Polymeric Nanocomposites

A simple and environmentally safe method for obtaining stable nanoparticles of metal sulfides nanoparticles—NpAg2S, NpCdS, and NpZnS—was developed using different strains of microorganisms in an aqueous solution of metal salts and sulfur sources at the National Research Center Kurchatov Institute—GosNIIgenetika. The concentration of nanoparticles is 1‒4 mg/mL in aqueous suspensions. Using the methods of electron microscopy, spectrofluorimetry, and dynamic light scattering, the main characteristics of biogenic nanoparticles were determined: shape, size distribution, crystal structure, effective diameter, luminescent spectrum, and zeta potential. According to their characteristics, these nanoparticles are referred to quantum dots. It is established that the stability of nanoparticles in aqueous suspensions is due to protein molecules adsorbed on the surface of nanoparticles, which are supplied by cells of microorganisms. Effective immobilization of biogenic nanoparticles on the surface of various polymer supports was carried out. Biogenic nanoparticles along with nanoparticles obtained by physico-chemical methods can be used as fluorophores for imaging of biological processes, also as photocatalysts, solar cells, and for new nanocomposite materials.

Modified activated carbon catalytic reduction of dissolved oxygen in reclaimed water

ABSTRACT Dissolved oxygen (DO) is the main corrosive substance in the transport process of urban reclaimed water by pipelines, and it can be removed by catalytic reduction. Activated carbon (AC) has been conventionally used as a carrier for catalysts. This paper focuses on the effect of modification conditions of AC on the catalytic performance for DO removal by hydrazine. The catalytic performance of modified AC (MAC) samples by single and combinatory methods has been investigated. The results showed that the combinatory method was better than the single method, and the MAC by combinatory method of high-pressure hydrothermal method followed by metal salt solution impregnation method could remarkably promote the catalytic activity for DO removal. The prepared catalyst GS270-5-Ni-60-3 had the optimal catalytic activity at the conditions of reaction temperature of 30°C, pH 10 and the initial DO concentration of 5.31 mg/L, and the DO removal rate could reach 98.74%. Meanwhile, the samples of AC and MAC were characterized using BET, SEM and FTIR technologies. The experimental results showed that the high-pressure hydrothermal method could significantly improve the pore structure of AC, and the clogging of AC was not obvious by impregnation modification. Furthermore, the surface group of MAC also has a certain influence on the DO removal in reclaimed water.

Metal accumulation in the acrocarp moss Atrichum undulatum under controlled conditions

Mosses are frequently used to monitor atmospheric metal contamination but few studies on metal adsorption under controlled conditions are available. Here, the accumulation of the heavy metals copper and zinc was studied in the acrocarp moss Atrichum undulatum. An in vitro culture of A. undulatum was established and the same line, size and equally old remets were exposed to six different treatments representing various metal exposure times and washing scenarios as rain simulation. The metal treatments were done in copper and zinc salts (Cu-acetate, CuSO4, ZnSO4 and ZnCl2, respectively). Energy-Dispersive X-ray microanalysis (EDX) was employed to detect bound heavy metals on the moss plantlets. Element distribution in stems and leaves was measured separately. The aqueous solution of metal salts facilitated an adsorption of both elements in the moss tissue as compared to solid medium. Furthermore, A. undulatum can tolerate pollution of zinc and copper in a distinctive extent; our data point towards a higher zinc tolerance whereas copper is rather harmful. However, semi-quantitatively, less zinc was detected within the moss tissue compared to copper. Interestingly, a strong positive correlation between the accumulation of copper/zinc and iron, and a strong negative correlation between copper/zinc and magnesium, respectively, was documented.

Study of the possibility of obtaining metal nanoparticles under the action of a non-equilibrium plasma on aqueous solutions of salts

Dispersions of metal nanoparticles were obtained at the gas discharge treatment of aqueous solutions of CuCl2, CuSO4 and AgNO3. Direct current discharge was excited between a metal cathode located in the air and metal salt solution being used as an anode at a current of 5–25 mA. The average sizes of obtained nanoparticles were estimated using dynamic light scattering method. The sizes have been shown to depend on the solution concentration, discharge current and processing time. The obtained nanoparticles were applied from dispersions to medical dressings and their bactericidal activity was tasted. Samples treated with silver-containing particles showed bactericidal activity against bacteria Escherichia coli, Staphylococcus albus, Bacillus subtilis and microscopic fungus Candida albicans. Copper-containing samples did not show biological activity.

Effect of Zinc on the Oxidative Stress Biomarkers in the Brain of Nickel-Treated Mice.

The overexposure to nickel due to the extensive use of it in modern technology remains a major public health concern. The mechanisms of pathological effects of this metal remain elusive. The present study was devoted to evaluate the effect of nickel on the oxidative state of the brain cells of mice and to assess whether zinc as redox state modulator could efficiently protect cells against nickel's neurotoxicity. As oxidative stress biomarkers in the present study, we have measured the concentrations of reduced glutathione, metallothioneins, and malondialdehyde and the activity of the enzyme δ-aminolevulinate dehydratase. For the single metal exposure, mice were i.p. injected once with solutions of NiCl2 and/or ZnSO4; repeated exposure was performed i.p. injecting metal salt solutions for 14 days (once a day). The control mice received i.p. injections of saline. Results of our study demonstrate that single and 14 days of Ni2+ exposure decreased reduced glutathione and increased malondialdehyde contents in the brain of mice. Repeated Ni2+ administration significantly inhibited δ-aminolevulinate dehydratase while increasing brain metallothionein concentration at both exposure periods. Zinc exhibited a protective effect against nickel-induced glutathione and lipid peroxidation in brain cells of mice at both intervals of time, while repeated exposure to this metal significantly raised the brain metallothionein content. Repeated Zn2+ pretreatment protected δ-aminolevulinate dehydratase from Ni2+-induced inhibition and significantly increased metallothionein concentration at both investigated time intervals.

Analysis of Cellular Activity Short-Term Exposure to Cobalt and Chromium Ions in Mature Human Osteoblasts.

In aseptic loosening of endoprosthetic implants, metal particles, as well as their corrosion products, have been shown to elicit a biological response. Due to different metal alloy components, the response may vary depending on the nature of the released corrosion product. Our study aimed to compare the biological effects of different ions released from metal alloys. In order to mimic the corrosion products, different metal salts (CoCl2, NiCl2 and CrCl3 × 6H2O) were dissolved and allowed to equilibrate. Human osteoblasts were incubated with concentrations of 10 µM to 500 µM metal salt solutions under cell culture conditions, whereas untreated cells served as negative controls. Cells exposed to CoCr28Mo6 particles served as positive controls. The cell activity and expression of osteogenic differentiation and pro-osteolytic mediators were determined. Osteoblastic activity revealed concentration- and material-dependent influences. Collagen 1 synthesis was reduced after treatment with Co(2+) and Ni(2+). Additionally, exposure to these ions (500 µM) resulted in significantly reduced OPG protein synthesis, whereas RANKL as well as IL-6 and IL-8 secretion were increased. TLR4 mRNA was significantly induced by Co(2+) and CoCr28Mo6 particles. The results demonstrate the pro-osteolytic capacity of metal ions in osteoblasts. Compared to CoCr28Mo6 particles, the results indicated that metal ions intervene much earlier in inflammatory processes.

Analysis of nickel distribution by synchrotron radiation X-ray fluorescence in nickel-induced early- and late-phase allergic contact dermatitis in Hartley guinea pigs.

Background:Nickel-induced allergic contact dermatitis (Ni-ACD) is a global health problem. More detailed knowledge on the skin uptake of haptens is required. This study aimed to investigate the penetration process and distribution of nickel in skin tissues with late phase and early phase of Ni-ACD to understand the mechanisms of metal allergy.Methods:Forty Hartley guinea pigs were divided into four groups according to the NiSO4 sensitizing concentration and the NiSO4 challenged concentration: the 5% NiSO4-group, 5% to 10% (sensitization-challenge; late phase group); 10% NiSO4-group, 10% to 10% (sensitization-challenge; early-phase group); and the positive and negative controls. Pathological biopsies were performed on each group. The depth profile of nickel element concentration in the skin of guinea pigs was detected by synchrotron radiation micro X-ray fluorescence spectroscopy (SR-μ-XRF) and micro X-ray absorption near-edge spectroscopy (μ-XANES).Results:In each section, the nickel element concentration in both the 5% NiSO4-group and 10% NiSO4-group was significantly higher than that in the negative control group. In the upper 300-μm section of skin for the early phase group, the nickel element concentration was significantly higher than that in the lower section of skin. In deeper sections (>200 μm) of skin, the concentration of nickel in the early phase group was approximately equal to that in the late phase group. The curve of the late phase group was flat, which means that the nickel element concentration was distributed uniformly by SR-μ-XRF. According to the XANES data for the 10% NiSO4 metal salt solution, structural changes occurred in the skin model sample, indicating that nickel was not present in the Ni2+ aqueous ionic state but in the nickel-binding protein.Conclusions:This study showed that the distribution of the nickel element concentration in ACD skin tissue was different between the early phase and late phase groups. The nickel element was not present in the Ni2+ aqueous ionic state but bound with certain proteins to form a complex in the stratum corneum in ACD model tissue.

Biotechnological method of obtaining nanoparticles of silver, cadmium and zinc sulfides. Physico-chemical characteristics. Creation of polymeric nanocomposites

A simple and environmentally safe method for obtaining stable nanoparticles of metal sulfides nanoparticles – NpAg2S, NpCdS and NpZnS was developed using different strains of microorganisms in an aqueous solution of metal salts and sulfur sources at the Research Center "Kurchatov Institute" – GosNIIgenetika. The concentration of nanoparticles is 1–4 mg/ml in aqueous suspensions. Using of the methods of electron microscopy, spectrofluorimetry, dynamic light scattering determined the main characteristics of biogenic nanoparticles: shape, size distribution, crystal structure, effective diameter, luminescent spectrum, zeta potential. According to its characteristics, these nanoparticles are referred to quantum dots. It is established that the stability of nanoparticles in aqueous suspensions is due to protein molecules adsorbed on the surface of nanoparticles, which are supplied by cells of microorganisms. Effective immobilization of biogenic nanoparticles on the surface of various polymer supports has been carried out. Biogenic nanoparticles along with nanoparticles obtained by physico-chemical methods can be used as fluorophores for imaging of biological processes, also as photocatalysts, solar cells and for new nanocomposite materials.

Homogeneous Metal Salt Solutions for Biomass Upgrading and Other Select Organic Reactions

The growing interest in biomass as a renewable feedstock drives research toward innovative processes and performance-advantaged bioproducts. Homogeneous metal salt solutions are promising media owi...

S-layer protein-AuNP systems for the colorimetric detection of metal and metalloid ions in water

Bacterial surface layer proteins (S-layer) possess unique binding properties for metal ions. By combining the binding capability of S-layer proteins with the optical properties of gold nanoparticles (AuNP), namely plasmonic resonance, a colorimetric detection system for metal and metalloid ions in water was developed. Eight S-layer proteins from different bacteria species were used for the functionalization of AuNP. The thus developed biohybrid systems, AuNP functionalized with S-layer proteins, were tested with different metal salt solutions, e.g. Indium(III)-chloride, Yttrium(III)-chloride or Nickel(II)-chloride, to determine their selective and sensitive binding to ionic analytes. All tested S-layer proteins displayed unique binding affinities for the different metal ions. For each S-layer and metal ion combination markedly different reaction patterns and differences in concentration range and absorption spectra were detected by UV/vis spectroscopy. In this way, the selective detection of tested metal ions was achieved by differentiated analysis of a colorimetric screening assay of these biohybrid systems. A highly selective and sensitive detection of yttrium ions down to a concentration of 1.67 × 10−5 mol/l was achieved with S-layer protein SslA functionalized AuNP. The presented biohybrid systems can thus be used as a sensitive and fast sensor system for metal and metalloid ions in aqueous systems.

Facile Synthesis of UiO-66(Zr) Using a Microwave-Assisted Continuous Tubular Reactor and Its Application for Toluene Adsorption

UiO-66(Zr) has been widely used for many applications due to its high surface area and excellent chemical and thermal stabilities. Conventionally, UiO-66(Zr) has been prepared in an autoclave by solvothermal synthesis, which requires a lengthy reaction time (typically 24 h) while only producing a small amount of product. In this work, a larger quantity of UiO-66(Zr) was rapidly produced in a continuous tubular reactor under microwave irradiation. The metal salt and organic linker precursor solutions were continuously introduced into the tubular reactor by a microfluidic syringe pump system. The results showed that UiO-66(Zr) was produced with a high yield, porosity, and crystallinity within a short reaction time of 10 min. The characteristics of UiO-66(Zr) were affected by the reaction temperature, residence time, and modulator concentration. The UiO-66(Zr) prepared under the optimum conditions was evaluated for gaseous toluene adsorption at various temperatures.

Highly Active Monolith Catalysts of LaKCoO3 Perovskite-type Complex Oxide on Alumina-washcoated Diesel Particulate Filter and the Catalytic Performances for the Combustion of Soot

The LaKCoO3/ɤ-Al2O3/cordierite and LaCoO3/ɤ-Al2O3/cordierite monolithic catalysts were successfully prepared by impregnating the as-pretreated monolith with aqueous solution of metal salts on monolithic cordierite substrate with a dip-coating two-step method. For comparison, one-step method without the alumina sol coating was also investigated. The monolithic catalysts were characterized by means of XRD, FT-IR, BET, ICP, TG–DSC, XPS and SEM-EDS. The characterization results demonstrate the formation of a small amount of Co3O4 when a large amount of K+ was introduced into LaCoO3 for the substitution of La3+. The coating of porous hollow aluminum oxide nano-particles could enhance the surface area of monolithic cordierite by about 100 times. The active components of LaKCoO3/ɤ-Al2O3 supported catalysts can disperse on the surface of the catalysts as monolayer and be the uniform distributions of La, Co and K. The ultrasonic vibration treating results indicated that the Al2O3 washcoat and catalyst components were adhered to the substrate strongly, the average weight loss is limited to about 1.0 % of the washcoat weight after 30 min in ultrasonic bath. The TG–DSC results show the good thermal stability of the LaKCoO3 and LaCoO3 coatings on alumina-coated monolithic cordierite. The LaKCoO3/ɤ-Al2O3/cordierite catalyst gave the highest catalytic activity for soot combustion among the studied catalysts. The T10, T50, T90 over the LaKCoO3/ɤ-Al2O3/cordierite catalyst were 186.3 °C, 314.6 °C, 390.0 °C, respectively, and Sco2mwas 99.8%.

Numerical simulation of mixed lubrication considering surface forces

Abstract Mixed lubrication describes a lubrication regime where elastohydrodynamic lubrication and asperity contact coexist. Surface spacing is expected to be small during the interaction between nano-scale smooth surfaces. When alkali metal salt solution is applied as lubricant, short-range surface forces are incorporated into an existing model to simulate mixed lubricated non-conformal sliding contact. The new model is examined in a wide range of sliding velocities to demonstrate the effect of surface forces at different lubrication regime, from boundary lubrication to full film hydrodynamic lubrication. It is revealed that surface forces reduce friction coefficient particularly at mixed lubrication regime. Reduction of surface roughness improves contribution of surface forces and makes it easier to achieve superlubricity at low speed.

Design of a novel membrane-integrated waste acid recovery process from pickling solution

Abstract Hydrochloric acid pickling is a common practice in steel manufacturing industry. During the process, acid is consumed to dissolve surface oxides and metals ions are accumulated in the solution, which becomes less effective with time. In addition, the costly and risky waste acid disposal is another issue affecting the hot-dip galvanizing industry. In this work, a novel sustainable waste acid recovery process from pickling solutions based on circular approach is proposed to tackle these issues. The innovative system allows (i) the continuous regeneration of pickling solutions to enhance process rate and performance and (ii) minimise the highly expensive and environmentally risky wastewater disposal. In this way, refilling pickling baths with fresh acid, as done in conventional operation, can be avoided and can be carried out continuously under optimal working conditions. Moreover, the recovery of valuable substances (e.g. metal hydroxide or salts solution) can be obtained as an additional benefit. Continuous treatment and regeneration of pickling solution can be accomplished by coupling diffusion dialysis (DD) and membrane distillation (MD) technologies with a reactive precipitation unit where iron ions can be separated from the zinc-rich solution, in order to recover valuable products. To this purpose, a steady state process simulator was developed to predict the operation of the proposed integrated process.