Dissolved Metal Salts Research Articles

The uptake and elimination of ZnO and CuO nanoparticles in Daphnia magna under chronic exposure scenarios

In this study, the uptake and elimination of ZnO and CuO nanoparticles in Daphnia magna was tested. Daphnids were exposed during 10 days to sublethal concentrations of ZnO and CuO nanoparticles and corresponding metal salts (ZnCl2 and CuCl2.2H2O), after which they were transferred to unexposed medium for another 10 days. At different times during the exposure and none-exposure, the total and internal zinc or copper concentration of the daphnids was determined and the nanoparticles were localized in the organism using electron microscopy. The exposure concentrations were characterized by measuring the dissolved, nanoparticle and aggregated fraction in the medium. The results showed that the ZnO nanoparticles quickly dissolved after addition to the medium. Contrarily, only a small fraction (corresponding to the dissolved metal salt) of the CuO nanoparticles dissolved, while most of these nanoparticles formed large aggregates. Despite an initial increase in zinc and copper concentration during the first 48 h to 5 day exposure, the body concentration reached a plateau level that was comparable for the ZnO nanoparticles and ZnCl2, but much higher for the CuO nanoparticles (with visible aggregates accumulating in the gut) than CuCl2.2H2O. During the remaining exposure and subsequent none-exposure phase, the zinc and copper concentration decreased fast to concentrations comparable with the unexposed daphnids. The results indicate that D. magna can regulate its internal zinc and copper concentration after exposure to ZnO and CuO nanoparticles, similar as after exposure to metal salts. The combined dissolution, accumulation and toxicity results confirm that the toxicity of ZnO and CuO nanoparticles is caused by the dissolved fraction.

A study on treatment methods of spent pickling liquor generated by pickling process of steel

Metals to be coated require pre-treatment to remove rust or scale, impurities and inorganic contaminants. In steel industries, pickling process generates a considerable quantity of Spent Pickle Liquor (SPL) containing the dissolved metal salts of iron, chromium, copper, nickel and zinc as well as residual free acid. The waste generated by metal pickling and electroplating industries is identified as hazardous solid waste as per Indian Standards and United State Environmental Protection Agency (US EPA). This paper discusses the advantages and disadvantages of treatment methods of spent pickling liquor generated by pickling line of steel. The discussion shows that treatment method depends upon the quantity, quality and composition of SPL. Experimental modelling helps in better understanding of treatment process and also craft process more technically and economically feasible.

4,4-Bipyridinium ionic liquids exhibiting excellent solubility for metal salts: Potential solvents for electrodeposition

Abstract Newly synthesised 4,4-bipyridinium based ionic liquids exhibit good metal coordinating abilities and are able to dissolve metal salts at high concentrations. The ability to capture metal salts into the ionic liquid media facilitates the application of ionic liquids in many areas such as metal extraction or electrochemistry. The ionic liquid n-butyl-4,4-bipyridinium bis(trifluoromethyl)sulfonylamide ([C4Bipyr][Tf2N]) exhibits a large liquidus range and a wide electrochemical window. The successful electrodeposition of Cu (II) to Cu (0) from a solution of Cu(NO3)2 in [C4Bipyr][Tf2N] shows the potential of this new type of ionic liquids for electrodeposition.

The study of palladium ions incorporation into the mesoporous ordered silicates

In this work mesoporous ordered silica materials containing palladium species were prepared using of tetraammine palladium chloride ([Pd(NH3)4]Cl2) complex as a palladium source during synthesis and by wetness impregnation of pure support by solution containing dissolved metal salt. The ammonia ligands from tetraammine palladium chloride were removed during calcination or during thermal treatment at 300°C in oxygen atmosphere. For reduction of palladium ions to metallic state as prepared materials were treated by hydrogen at high temperature. In this work the locations of palladium atoms in silica lattice were considered by study of binding energy changes of cardinal atoms of mesoporous ordered silica.Ordered mesoporous silicates (MCM-41 and SBA-15) are very promising materials for a wide range of industrial applications due to their unique properties as well-defined ordered structure and excellent textural properties. They exhibit high surface area with high pore volume. Such supports ensure a high dispersion of the metal nanoparticles or other active phases providing the high activity of solid catalysts.The obtained materials were characterized primarily by X-ray diffraction (XRD) technique, X-ray photoelectron spectroscopy (XPS), nitrogen adsorption–desorption isotherms, and infrared spectroscopy. The proportional content of palladium was controlled by X-ray fluorescence technique.

Electroless synthesis of 3 nm wide alloy nanowires inside Tobacco mosaic virus

We show that 3 nm wide cobalt–iron alloy nanowires can be synthesized by simple wet chemical electroless deposition inside tubular Tobacco mosaic virus particles. The method is based on adsorption of Pd(II) ions, formation of a Pd catalyst, and autocatalytic deposition of the alloy from dissolved metal salts, reduced by a borane compound. Extensive energy-filtering TEM investigations at the nanoscale revealed that the synthesized wires are alloys of Co, Fe, and Ni. We confirmed by high-resolution TEM that our alloy nanowires are at least partially crystalline, which is compatible with typical Co-rich alloys. Ni traces bestow higher stability, presumably against corrosion, as also known from bulk CoFe. Alloy nanowires, as small as the ones presented here, might be used for a variety of applications including high density data storage, imaging, sensing, and even drug delivery.

Direct synthesis and coating of advanced nanocomposite negative electrodes for Li-ion batteries via electrospraying

A direct approach for the synthesis and coating of advanced nanocomposite negative electrodes via a single-step process at low temperature is presented. Metal-oxide/PVdF nanocomposites are obtained in one step by electrospray pyrolysis of precursor solutions containing dissolved metal salts together with polyvinylidene fluoride (PVdF) as binder. In this way, small oxide nanoparticles are generated and dispersed in situ in the binder creating nanocomposite structures, while being coated at once as thin electrode layers on stainless steel coin cell cans. The intimate contact between the nanoparticles and the binder favours enhanced adhesion of the materials in the overall electrode structure and adequate electrochemical performances are obtained without any conductive additive. Three nanocomposite oxide/PVdF materials (i.e. SnO 2, CoO and Fe 2O 3) are reported here as preliminary examples of negative electrodes. The results show that this approach is suitable, not only for the fabrication of nanocomposite electrodes for Li-ion batteries, but also for other novel applications.

Preparation of nanodispersed titania using stabilized ammonium nitrate melts

An expedite one-step approach using simple precursors has been proposed to obtain metallic oxide compounds and exemplified by preparation of highly dispersed TiO 2. The technique consists in heating to 400–500 °C of molten ammonium nitrate stabilized with an organic nitrogen-containing compound (urea, melamine, ammonium oxalate) and containing dissolved metal salt precursor (TiOCl 2). The crystallites of the resulting TiO 2 demonstrated variable size and shape as a function of stabilizer used. Their activity in photocatalytic oxidation of formic acid also depends on the nature of the stabilizer. The catalysts as-prepared showed high photocatalytic performance, superior to that of the Degussa P25 reference. Nitrogen containing stabilizers play a double role of increasing the process safety and modifying the properties of the solid products.

Technical Description of Parameters Influencing the pH Value of Suspension Absorbent Used in Flue Gas Desulfurization Systems

As a result of the large limestone deposits available in Poland, the low cost of reagent acquisition for the large-scale technological use and relatively well-documented processes of flue gas desulfurization (FGD) technologies based on limestone sorbent slurry, wet scrubbing desulfurization is a method of choice in Poland for flue gas treatment in energy production facilities, including power plants and industrial systems. The efficiency of FGD using the above method depends on several technological and kinetic parameters, particularly on the pH value of the sorbent (i.e., ground limestone suspended in water). Consequently, many studies in Poland and abroad address the impact of various parameters on the pH value of the sorbent suspension, such as the average diameter of sorbent particles (related to the limestone pulverization degree), sorbent quality (in terms of pure calcium carbonate [CaCO3] content of the sorbent material), stoichiometric surfeit of CaCO3 in relation to sulfur dioxide (SO2) absorbed from flue gas circulating in the absorption node, time of absorption slurry retention in the absorber tank, chlorine ion concentration in sorbent slurry, and concentration of dissolved metal salts (Na, K, Mg, Fe, Al, and others). This study discusses the results of laboratory-scale tests conducted to establish the effect of the above parameters on the pH value of limestone slurry circulating in the SO2 absorption node. On the basis of the test results, a correlation equation was postulated to help maintain the desirable pH value at the design phase of the wet FGD process. The postulated equation displays good coincidence between calculated pH values and those obtained using laboratory measurements.

An unusual common ion effect promotes dissolution of metal salts in room-temperature ionic liquids: a strategy to obtain ionic liquids having organic–inorganic mixed cations

A simple strategy has been reported to prepare new ionic liquids with binary systems of organic–inorganic cations exploiting the common ion effect, i.e. dissolving metal salts with organic or inorganic anions (bistriflylimide or nitrate) in ionic liquids bearing the same anions. The resulting concentrated solutions of metal cations in ionic environments, which may have great potential for electrochemical processes, have been characterized by X-Ray photoelectron spectroscopy (XPS) and electrospray ionization mass spectrometry (ESI-MS)

Synthesis of multi-walled carbon nanotubes and nano-fibres using the aerosol method with metal-ions as the catalyst precursors

We report on MWNTs synthesised using the aerosol method. The catalyst particles are formed by dissolving metal salts in organic solvents. This solution is sprayed as aerosols into a furnace. The active catalyst is formed in-situ, using H 2 as carrier gas and as reducing agent of the metal ions. This synthesis route gives possibilities for using a uniquely wide range of metal catalyst precursors and carbon sources. Using this approach, the size of the active catalyst particles can be calculated. MWNTs, prepared using Co(NO 3) 2 · 6H 2O as precursor and tetrahydrofuran, serving as solvent and carbon source demonstrate the reliability of these predictions.

Solution Activators of Aluminum Electrochemistry in Organic Media

The use of solution activators (dissolved metal salts) to enhance aluminum electrochemical activity in organic media is reported. Aluminum is electrochemically passive in most organic electrolytes and unlike lithium, has not been developed as a battery anode in organic media. We demonstrate significant Al activity in two electrolytes, in γ‐butyrolactone or in acetonitrile. These improve the anodic potential by up to 1 V in comparison to other electrolytes and increase from microampere to milliampere per square centimeter, the sustainable Al oxidation current. Electrolytic metal acetate, chloride, or other salts can further enhance these favorable anodic characteristics. Unlike Sn(II), Sn(IV), or Ga(III), both Hg(II) and In(III) significantly activate Al redox behavior. In , the Al oxidative polarization is 100, 65, 36, or only 28 Ω in electrolytes containing, respectively, 0, 1, 10, 100 mM Hg(II). Hg(II) also shifts negatively the observed by 150 to 250 mV, an enhancement sustained during extended anodic galvanostatic discharge. Similarly, as little as 1 mM In(III) diminishes polarization to 40 Ω Addition of 10 mM In(II) to in acetonitrile, improves by 0.4 to −1.57 V vs. . © 2000 The Electrochemical Society. All rights reserved.

Synthesis and properties of aromatic polyamides derived from 2,6-bis(4-aminophenoxy)naphthalene and various aromatic dicarboxylic acids

2,6-Bis(4-aminophenoxy)naphthalene (2,6-BAPON) was synthesized in two steps from the condensation of 2,6-dihydroxynaphthalene with p-chloronitrobenzene in the presence of potassium carbonate, giving 2,6-bis(4-nitrophenoxy)naphthalene, followed by hydrazine hydrate/Pd—C reduction. A series of new polyamides were synthesized by the direct polycondensation of 2,6-BAPON with various aromatic dicarboxylic acids in the N-methyl-2-pyrrolidone (NMP) solution containing dissolved metal salts such as CaCl2 or LiCl using triphenyl phosphite and pyridine as condensing agents. The polymers were obtained in quantitative yields with inherent viscosities of 0.62–2.50 dL/g. Most of the polymers were soluble in aprotic dipolar solvents such as N,N-dimethylacetamide (DMAc) and NMP, and they could be solution cast into transparent, flexible, and tough films. The casting films had yield strengths of 84–105 MPa, tensile strengths of 68–95 MPa, elongations at break of 8–36%, and tensile moduli of 1.4–2.1 GPa. The glass transition temperatures of the polyamides were in the range 155–225°C, and their 10% weight loss temperatures were above 505°C in nitrogen and above 474°C in air. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 2147–2156, 1997

Synthesis and properties of aromatic polyamides based on 4,4′‐[1,4(1,3 or 1,2)‐phenylenedioxy]dibenzoic acid

AbstractThree isomeric bis(ether carboxylic acid)s, 4,4′‐[1,2(1,3 or 1,4)‐phenylenedioxy]dibenzoic acid (o‐, m‐, or p‐3) were prepared by nucleophilic substitution reaction of the potassium phenolate of catechol, resorcinol, and hydroquinone, respectively, with p‐fluorobenzonitrile, giving the corresponding bis(ether nitrile)s, followed by alkaline hydrolysis. There series of isomeric polyamides were synthesized by direct polycondensation of the bis(ether carboxylic acid)s with various aromatic diamines in N‐methyl‐2‐pyrrolidone (NMP) solution containing dissolved metal salts such as CaCl2 or LiCl using triphenyl phosphite and pyridine as condensing agents. The resultant polyamides had inherent viscosities of 0,52–1,63 dL/g. Most of the polymers were soluble in polar aprotic solvents such as N,N‐dimethylacetamide (DMAc), N,N‐dimethylformamide (DMF), NMP, and dimethyl sulfoxide. The catechol‐based polyamides revealed markedly higher solubility than those based on hydroquinone or resorcinol. Transparent, flexible and tough films could be cast from the DMAc or NMP solutions of most of the polyamides. All the casting films were characterized by tensile tests. The glass transition temperatures (Tg's) of most polyamides could be determined with the help of differential scanning calorimetry (DSC) traces, which were recorded in the range of 183–232°C. In general, the polyamides based on catechol had Tg's comparable with the ones of the hydroquinone‐based polyamides and higher Tg's than the corresponding resorcinol‐based ones. Thermogravimetric analysis data of these polymers indicated that all the polyamides were stable up to 400°C in both air and nitrogen atmospheres.

Synthesis and properties of aromatic polyamides derived from 1,6‐bis(4‐aminophenoxy)naphthalene and aromatic dicarboxylic acids

AbstractA new bis(phenoxy)naphthalene‐containing diamine, 1,6‐bis(4‐aminophenoxy)naphthalene, was synthesized in two steps from the condensation of 1,6‐dihydroxynaphthalene with p‐chloronitrobenzene in the presence of potassium carbonate, giving 1,6‐bis(4‐nitrophenoxv)naphthalene, followed by hydrazine hydrate/Pd—C reduction. A series of polyamides were synthesized by the direct polycondensation of the diamine with various aromatic dicarboxylic acids in the N‐methyl‐2‐pyrrolidone (NMP) solution containing dissolved metal salts such as CaCl2 or LiBr using triphenyl phosphite and pyridine as condensing agents. The polymers were obtained in quantitative yield with inherent viscosities of 0.78–3.72 dL/g. Most of the polymers were soluble in aprotic solvents such as N,N‐dimethylacetamide (DMAc), N,N‐dimethylformamide (DMF), NMP, and they could be solution‐cast into transparent, flexible and tough films. The casting films had tensile strength of 102–175 MPa, elongation at break of 8–42%, and tensile modulus of 2.4–3.8 GPa. The polymers derived from rigid dicarboxylic acids such as terephthalic acid and 4,4′‐biphenyldicarboxylic acid exhibited some crystalline characteristics. The glass transition temperatures of the polyamides were in the range of 238–337°C, and their 10% weight loss temperatures were above 487°C in nitrogen and above 438°C in air. © 1995 John Wiley & Sons, Inc.

The Preparation of Per-Deuterated Aromatic Hydrocarbons Using Organosulfur Compounds

Abstract Per-deuteration of benzothiophene (1), benzenethiol (2) and p-methylbenzenethiol (3) has been accomplished by reaction with D2O containing dissolved metal salts at 250° – 315°C. Desulfurization of the products gave per-deutero ethylbenzene, benzene and toluene in high overall yield (> 95%).

Generation and characterization of supported films of transition metal and rare earth metal oxide catalysts

The generation of catalytically relevant metal and/or metal oxide compounds supported on silica fibres is described. The systems investigated are Nio, Cuo, Cuo/ZnO, as well as perovskite-type La/Fe, La/Ni and La/Mn oxide phases. Ultrasound-aided generated vapours containing dissolved metal salt precursors are transferred onto preheated quartz fibres and transformed into the catalytically relevant phases by subsequent calcination. Analytical SEM and X-ray diffraction reveals the presence of differently crystalline, rough surfaces. The influence of the precursor salt and the conditions of calcination on the formation of the supported catalysts is discussed.

Formation of Salt Films during Anodic Metal Dissolution in the Presence of Fluid Flow

Anodic dissolution of a metal in the presence of flowing electrolytic solution was studied by both experimental and theoretical methods. A mathematical model was developed which included emphasis on the potential field distribution near the dissolving electrode, and on convective diffusion effects in both laminar and turbulent flow. Critical conditions were identified for saturation, by dissolved metal salt, of the solution adjacent to the anodic surface. Theoretical results were compared to measurements obtained in a channel flow system of the critical flow velocities above which pure iron would not repassivate in .

Incorporation of Metal Related Materials into Electrically Neutral Polymers

Developments in the field of metal-containing polymers are reviewed with emphasis on neutral polymers incorporating dissolved metal salts, metal complexes, organometallic compounds, and metals. Polymer systems discussed include: polyamides, polyimides, polyalcohols, polyesters, polyacetylene, polyethylene, and polysiloxane. Most of the studies focus on the modification of polymer properties such as adhesive properties, thermal behavior, electrical conductivity, polymer flammability, and mechanical properties.

Environmental Contamination Through Residual Trace Metal Dispersal from a Derelict Lead‐Zinc Mine

AbstractStudies of historical and current environmental problems in the vicinity of a derelict Pb‐Zn mine at Parc, near Llanwrst in North Wales, have shown that heavy metal dispersal occurs through contaminated mine drainage waters and episodal erosion of an unstable tailings dam.Since the discontinuation of mining operations an estimated 13,000 metric tons of metalliferous spoil, equivalent to 43 metric tons Pb, 104 metric tons Zn, and 1 metric ton Cd, have been eroded from the main tailings dam. Dispersal by a tributary of the River Conwy and redeposition during flooding events has caused extensive contamination of lowland agricultural pastures. Streamwater pollution by tailings and dissolved metal salts in mine effluent continues to have a pronounced adverse effect on the flora and fauna of the tributary.Under normal discharge conditions mean net transfer of metals into the main Conwy River approximates to 0.27 kg Pb, 15 kg Zn, and 0.1 kg Cd over 24 hours. However, because of the increased particulate load during surface drainage and flooding episodes, net dispersal increases unequally for the different metals, to a rate above that anticipated from discharge‐concentration relationships.With a remaining deposit of 250,000 metric tons of mine tailings, tip stabilization measures have been initiated as a safeguard against further degradation of natural resources in the locality.