Bestimmung der Spurengehalte an Schwermetallen in anorganischen Salzen und in organischen L?sungsmitteln durch energiedispersive R?ntgenfluorescenzanalyse oder flammenlose Atomabsorptionsspektrometrie nach Anreicherung an einem Celluloseaustauscher

Zusammenfassung Die Spurengehalte an Pb, Cu, Zn, Fe und Ni in den Salzen NaCl, CaCl₂, Al(NO₃)₃, ZnCl₂, Mn(NO₃)₂ und Cr(NO₃)₃ des Reinheitsgrades p.A. wurden aus 10%igen Lösungen dieser Salze in einer mit dem Celluloseaustauscher 4-[Pyridil-(2)-azo]-resorcin (PAR) gefüllten Trennsäule quantitativ abgetrennt, mit Ausnahme von Eisen aus Al(NO₃)₃ und Cr(NO₃)₃ sowie von Nickel aus Mn(NO₃)₂. In der gleichen Weise wurden die genannten Schwermetalle aus den organischen Lösungsmitteln Methanol und Ethanol abgetrennt. Nach Elution der angereicherten Schwermetalle mit Salzsäure wurden sie an 0,1 g des Celluloseaustauschers fixiert und durch energiedispersive Röntgenfluorescenzanalyse oder direkt im Eluat durch flammenlose Atomabsorptionsspektroskopie bestimmt.

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Determination of traces of heavy metals in inorganic salts and organic solvents by energy-dispersive X-Ray fluorescence analysis or flameless atomic absorption spectrometry after enrichment on a cellulose exchanger

Summary The trace element contents of Pb, Cu, Zn, Fe and Ni in the p.a. grade salts NaCl, CaCl₂, Al(NO₃)₃, ZnCl₂, Mn(NO₃)₂ and Cr(NO₃)₃ were quantitatively separated from 10% solutions of these salts in a column filled with the cellulose exchanger 4-[pyridil-(2)-azo]-resorcinol (PAR), with the exception of Fe from Al(NO₃)₃ and Cr(NO₃)₃ and of Ni from Mn(NO₃)₂. In the same way the heavy metals were separated from the organic solvents methanol and ethanol. After elution of the heavy metals from the column by HCl they were either fixed on 0.1 g of the cellulose exchanger and measured by energy-dispersive X-ray fluorescence analysis or they were determined directly in the eluate by flameless atomic absorption spectroscopy.

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Thermodynamic properties and solution equilibria of aqueous bivalent transition metal nitrates and magnesium nitrate

Osmotic coefficients for Mn(NO₃)₂, Co(NO₃)₂, Ni(NO₃)₂, Cu(NO₃)₂, Zn(NO₃)₂, and Mg(NO₃)₂ in aqueous solution have been determined by the isopiestic method at 25°C, and activity coefficients have been derived. The results agree with the literature data for Zn(NO₃)₂, while they are significantly different for Co(NO₃)₂, Cu(NO₃)₂, and Mg(NO₃)₂, and those for Mn(NO₃)₂ and Ni(NO₃)₂ are new. The concentration dependence of the osmotic coefficients for the bivalent metal nitrates is similar to that for the trifluoroacetates, while it differs from those for the other salts of the same series of metals. The results are discussed in terms of the inner-sphere and outer-sphere association of ions, auxiliary information being derived from the concentration effects in the visible spectra of the coloured metal nitrates.     

Chemical effects of heavy metals on the hydration of calcium sulphoaluminate 4CaO·3Al2O3·SO3

The system 4CaO·3Al₂O₃·SO₃-CaSO₄·2H₂O-Ca(OH)₂ was hydrated in the presence of ten dopants, specifically soluble salts of heavy metals.When added in 10% amount, the effect of each salt is strongly evident at shorter curing times, the hydration kinetics being more favoured in the order Pb(NO₃)₂2CrO₄< Cd(NO₃)₂< Zn(NO₃)₂t~Mn(NO₃)₃=K₂MoO₄3)₂3)₂3)₃3)₃. At longer curing times the differences among the systems decrease significantly.The 28-day compressive strength is almost the same for all the systems except those containing Pb(NO₃)₂, K₂MoO₄ and K₂CrO₄.     

Influence of heavy metals on the early hydration of calcium sulfoaluminate

The hydration of calcium sulfoaluminate $ ( {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} ) $ in the presence of heavy metal is essential not only for applying the cement in solidification/stabilization (s/s) process, but also for preparing modern green cements from wastes containing heavy metals. In this study, the influence of gypsum, types, and concentrations of heavy metal nitrates (Pb(NO₃)₂, Cr(NO₃)₃·9H₂O, Cu(NO₃)₂·3H₂O, Zn(NO₃)₂·6H₂O) on the hydration of $ {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} $ during the first 24 h were investigated by isothermal conduction calorimetry, X-ray diffraction, and thermogravimetric analysis. The addition of 20 % of gypsum to $ {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} $ leads to a rapid formation of ettringite against monosulfate and acceleration of hydration. The effects of heavy metals on the hydration of $ {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} $ depend on the types of heavy metals and the addition of gypsum. Without any gypsum addition, heavy metal nitrates such as Cr, Cu, and Zn promote the hydration of $ {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} $ , whereas Pb presents a strong retardation effect at the early age of $ {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} $ hydration. When 20 % of gypsum is added to $ {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} $ , heavy metals tend to accelerate the hydration of the blended pastes except Zn. However, heavy metal containing phases were not detected in this work, which needs to be supplemented by further investigations.     

Metal nitrate driven nitro Hunsdiecker reaction with α,β-unsaturated carboxylic acids under solvent-free conditions

Hunsdiecker reactions with α,β-unsaturated carboxylic acids were conducted under solvent-free conditions in the presence of a few drops of HNO₃ together with a variety of metal nitrates [Mg(NO₃)₂, Sr(NO₃)₂], Al(NO₃)₃, Ca(NO₃)₂, Ni(NO₃)₂, Cd(NO₃)₂, Zn(NO₃)₂, Hg(NO₃)₂, AgNO₃, ZrO(NO₃)₂, UO₂(NO₃)₂, Th(NO₃)₂] or ammonium nitrate. α,β-Unsaturated aromatic carboxylic acids underwent nitro decarboxylation to afford β-nitro styrenes in moderate to good yields, while α,β-unsaturated aliphatic carboxylic acids underwent decarboxylation to yield the corresponding nitro derivatives.     

In-situ electrochemical and piezogravimetric studies on the application of macrocyclic resorcinarene tetramer in the development of chemically-modified heavy metals ions detection platform in aqueous media

The new application of C-dec-9-enylcalix[4]resorcinarene (R₁), as an ionophore to detect heavy metals (HMs) cations (Cd²⁺, Hg²⁺, Cu²⁺, and Pb²⁺) in the aqueous media has been investigated through the preparation of an effective mass-sensitive sensor via the exploitation of a flow-type QCM-I technique. By adjusting the ions’ amounts in model solutions over a wide range of concentrations, acquired changes in the oscillating frequency related to the loading of metal ions on the sensor’s surface were gained, and thus favorable metrological parameters displaying the lowest detection limit (LOD) associated with copper ions (10 ppb). Simultaneously, a novel voltammetric sensor was prepared by modifying gold screen-printed electrodes (SPEs) with R₁. Electrochemical characterization employing CV, SWV, and EIS was carried out, showing the success of the electrode modification. Then, the experimental conditions of supporting electrolyte, pH, accumulation time, and accumulation potential were optimized to achieve an enhanced detection. The R₁@SPE sensor simultaneously detected the HMs (Cd²⁺, Hg²⁺, Cu²⁺, Pb²⁺), and the lowest LOD was associated with Pb²⁺ (0.19 ppb). The selectivity evaluation of the electrochemical sensor was performed by studying the effect of interferences majorly present in water sources (Mg²⁺, Ni²⁺, Zn²⁺, Al³⁺, and K⁺) on the SWV detection signals, and it was revealed that the interfering ions did not affect the simultaneous detection of the studied HMs (RSD less than 5%), the voltammetric sensors also presented excellent repeatability and reproducibility (RSD less than 5%).     

Metal binding studies using spiroacetal thiacrown ethers

The binding ability of a series of spiroacetal thiacrown ethers with Li⁺, Na⁺, K⁺, Cs⁺, Co²⁺, Cd²⁺, Ag⁺ and Pb²⁺ is reported. The thiacrown ethers showed an affinity for the heavy metals. The interaction of the three thiacrown ethers 1-3 and [Al(acac)₃] 5, [Co(NH₃)₅NO₂](BPh₄)₂6 and [Co(en)₃](BPh₄)₃7 complexes is also investigated.     

A study of polypyrrole synthesized with oxidative transition metal ions

Polypyrrole powder and films were chemically synthesized by the reaction of AgNO₃, FeCl₃, Fe(NO₃)₃, Cu(NO₃)₂, or Cu(NO₃)₂-AlCl₃ with pyrrole in an aqueous solution or a water—toluene two-phase system. Products were characterized by elemental analysis, IR, scanning electron microscopy with energy dispersive x-ray analysis (SEM with EDAX), and conductivity measurements. The polypyrrole synthesized from pyrrole with FeCl₃ had a composition of C_4.00H_3.05N_0.99Cl_0.25. The pressed powder had a conductivity of 2.7 × 10^?2 S/cm and the film 2.8 S/cm. All the other metal salts produced films that had the same organic backbone, morphology, and conductivity as the polymer synthesized using Fe(III) salts, regardless of the considerable differences in the reduction potentials of the metal ions. The nature of the anions of the transition metal salts had no effect on the reaction. Anions, however, were retained as the counterions of the cationic polypyrrole backbone and could be easily exchanged with other anions.     

Etude thermodynamique de la décomposition thermique des hydroxynitrates de zinc

The reaction scheme of thermal decomposition for four zinc hydroxynitrates was investigated by means of differential scanning calorimetry, thermogravimetry, mass spectrometry, and radiocrystallography. The thermal transformation of Zn(OH)(NO₃) · H₂O and of Zn₃(OH)₄(NO₃)₂ involves the formation of gaseous water and nitric acid from an actual chemical reaction. This reaction is not observed for Zn₅(OH)₈(NO₃)₂ · 2H₂O and Zn₅(OH)₈(NO₃)₂. These results show that the formation of gaseous nitric acid molecules inside the solids is specific to hydroxynitrates of divalent metals M, whose lamellar crystalline structure is characterized by a stacking of hexagonal close-packed layers of formula MX_2+m, where m = 0 or 1 and X = OH^?, H₂O, or NO^?₃.     

Simultaneous light emission—differential thermal analysis of selected coordination compounds

A new apparatus which permits the simultaneous determination of both the light emission (LE) and differential thermal analysis (DTA) curves of a compound is described. LE—DTA curves are reported for a selected number of coordination compounds, each containing vigorous reducing—oxidizing ligands or ions. New LE curve peaks are reported for [Co(NH₃)₆](NO₃)₃, [Ni(en)₃](NO₃)₂, and [Rh(NH₃₅X](NO₃₂) (X = Cl, Br on NO₃) complexes. Multiple LE peaks were found for [Co dien (NO₃)₃], cis-[Co(en)₂(NO₂)₂] NO₂ and [Co dien NH₃(NO₂)₂]Cl. The presence of carbon-containing reducing ligand is not necessary in order to obtain a LE peak during the thermal dissociation process     

Synthesis,Spectral Characterization and Antimicrobial Activity of Some Transition Metal Complexes of 1,3‐Bis(1H‐benzimidazol‐2‐yl)‐2‐oxapropane

1,3‐Bis(1H‐benzimidazol‐2‐yl)‐2‐oxapropane ( L ) complexes with Fe(NO₃)₃, CoCl₂, Co(NO₃)₂, Ni(NO₃)₂, CuCl₂, Cu(ClO₄)₂, PdCl₂, CdI₂, Hg(NO₃)₂ were synthesized and characterized by elemental analysis, molar conductivity, magnetic moment, TGA, FT‐IR, NMR, ESI‐MS, fluorescence spectroscopy. Also, the crystal structure of 1,3‐bis(1H‐benzimidazol‐2‐yl)‐2‐oxapropane]dichlorocobalt(II), [Co( L )Cl₂], complex is reported that it has distorted trigonal bipyramidal geometry. Antibacterial activities of the compounds were evaluated using the disk diffusion method against six bacteria and Candida albicans. The Hg(II) complex shows superior activity toward S. epidermidis and E. coli whereas the other complexes are ineffective except the Co(NO₃)₂ complex: it showed weak activity toward all of the microorganisms.     

Synthesis, structures, and thermolysis of new heterometallic cobalt, nickel, and copper complexes with the [Ru(NO)(NO2)4(OH)]2− anion as a ligand

Heterometallic complexes with pyridine-N-oxide (PyO), Ru(NO)(NO₂)₄(OH)Ni(PyO)₂(H₂O)] · CH₃COCH₃ (I), [{Ru(NO)(NO₂)₂(μ-NO₂)₂(μ-OH)Co}₂(μ-PyO)] · H₂O · CH₃COCH (II), and [Ru(NO)(NO₂)₄(OH)Cu(PyO)₂ (III), are isolated in the reactions of Na₂[Ru(NO)(NO₂)₄(OH)] with nitrates of the corresponding metals in the presence of the organic ligand. The compounds synthesized are characterized by IR spectra, thermal analysis, and X-ray diffraction analysis. Depending on the M²⁺ cation, the ruthenium cation is coordinated through the bidentate (III, Cu²⁺) or tridentate (I, Ni²⁺ and II, CO₂₊) mode involving the bridging OH group and one or two NO₂ groups. The thermal decomposition of complex II results in the formation of a Co_0.5Ru_0.5 solid solution, which is thermodynamically stable under the decomposition conditions. The thermolysis of complexes I and III in a hydrogen atmosphere leads to the formation of metastable solid solutions.     

Extraction of heterometallic complexes of ruthenium and nonprecious metals by phosphorylmethylated calix[4]arenes from nitrate solutions

Synergetic extraction of [RuNO(NO₂)₄OH]^2? by calix[4]arene phosphine oxides (L) in the form of Ru/M heterometallic complexes was studied in the presence of nonprecious metals (M²⁺). The main extraction laws were recognized for [M(NO₃)₂L _n ] and [RuNO(NO₂)₄OH])ML _m ], where M²⁺ = Zn²⁺, Cu²⁺, Co²⁺, or Ni²⁺ and n, m = 1 or 2; extraction constants were determined for these metals. The variation row of the extraction constants with varying metal (Zn²⁺ > Cu²⁺ > Co²⁺ > Ni²⁺) coincides with the Irving-Williams row. Two or three PO groups of extractant L and the OH and NO₂ groups of the ruthenium anion are coordinated to the M²⁺ atom in Ru/M complexes. The conditions for generation of the Ru/Zn complex and its complete extraction were optimized as applied to the extraction of fission ruthenium from nitrated nitric acid and imitation solutions.     

Toxic metal complexes of macrocyclic cyclen molecule – synthesis,structure and complexing properties

Toxic metal (Cd²⁺, Hg²⁺, Pb²⁺, and Ag⁺) complexes with the tetradentate macrocyclic ligand - cyclen (1,4,7,10-tetraazacyclododecane, [12]aneN₄, L) were prepared and studied in the solid state by IR, X-ray diffraction, elemental and thermal analysis. Diffraction results have yielded three molecular structures, [Cd([12]ane-κ⁴N^1,4,7,10)(NO₃)₂)] (1), [Hg([12]ane-κ⁴N^1,4,7,10)(NO₃-κ²O,O`)]NO₃ (2), [Pb₂([12]ane-κ⁴N^1,4,7,10)₂][Pb(NO₃)₆] (3) and one polymeric structure {[Ag₂([12]ane-κ³N^1,4,7)(μ₂-[12]aneN¹⁰)](NO₃)₂?2H₂O)}_n (4) featuring a unique coordination mode not observed before with cyclen as a ligand. The monodentate (1) and chelate (with small bite angle 50.3(3)°, (2) coordination modes of nitrate ligands were confirmed. Stereochemically active 6s² lone pair was suggested in 3 and DFT results confirmed no significant metal–metal covalent bond. The stability constants of the complexes with Cd²⁺ and Pb²⁺ ions were determined by potentiometric methods in aqueous solutions. Additionally, the structures of complexes in solution were observed by ¹H NMR. Both methods confirm similar cyclen complexing properties toward Zn²⁺ biometal and Cd²⁺, Pb²⁺ toxic metals.     

Die thermische Zersetzung einiger Wismut-Doppelnitrate

Zusammenfassung Die Zersetzung von CsNO₃, Bi(NO₃)₃, Bi(NO₃)₃·5H₂O, BiONO₃, 2CsNO₃·Bi(NO₃)₃ und 3M(NO₃)₂·2Bi(NO₃)₃·24H₂O (M=Mg, Mn, Co, Ni, Zn) wurde thermogravimetrisch untersucht. Es wurde festgestellt, daß 2CsNO₃·Bi(NO₃)₃ über eine beständige Zwischenstufe 2CsNO₃+1/2Bi₂O₃, die Doppelnitrate 3M(NO₃)₂·2Bi(NO₃)₃·24H₂) über 3M(NO₃)₂+2BiONO₃ zerfallen. Eine Herabsetzung der thermischen Stabilität des CsNO₃ wegen der Anwesenheit von Bi₂O₃, und der NitrateM(NO₃)₂ wegen der Anwesenheit von BiONO₃ wurde beobachtet. Zugleich ist BiONO₃ von zweiwertigen Nitraten stabilisiert.

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The thermal decomposition of some bismuth double nitrates

The decomposition of CsNO₃, Bi(NO₃)₃, Bi(NO₃)₃·5H₂O, BiONO₃, 2CsNO₃·Bi(NO₃)₃, and 3M(NO₃)₂·2Bi(NO₃)₃·24H₂O (M=Mg, Mn, Co, Ni, Zn) has been studied by thermogravimetric analysis. It was found that 2CsNO₃·Bi(NO₃)₃ decomposesvia a stable intermediate, 2CsNO₃+1/2Bi₂O₃, and the double nitrates 3M(NO₃)₂·2Bi(NO₃)₃·24H₂)via 3M(NO₃)₂+2BiONO₃·Bi₂O₃ and BiONO₃ decrease the thermal stability of CsNO₃ andM(NO₃)₂, resp. Bivalent nitrates stabilize BiONO₃ to a certain degree.

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Auszug aus einem Teil der Magisterarbeit vonF. Lazarini.     

Preparation, characterization, and catalytic activity of rare earth metal oxide nanoparticles

In present study, a series of rare earth metal oxide (CeO₂, Pr₂O₃, and Nd₂O₃) nanoparticles have been prepared by sol–gel route using Ce(NO₃)₃·6H₂O, Pr(NO₃)₃·6H₂O and Nd(NO₃)₃·6H₂O, and citric acid as precursor materials. Powder X-ray diffraction, scanning electron microscopy, and transmission electron microscopy are employed to characterize the size and morphology of the nano oxide particles. The particles are spherical in shape and the average particle size is of the order of 11–30 nm. Their catalytic activity was measured on the thermal decomposition of ammonium perchlorate and composite solid propellants (CSPs) by thermogravimetry (TG), TG coupled with differential thermal analysis (TG–DTA), and ignition delay measurements. The ignition delays and activation energies are found to decrease when rare earth metal oxide nanoparticles were incorporated in the system. Addition of metal oxide nanoparticles to AP led to shifting of the high temperature decomposition peak toward lower temperature and the burning rate of CSPs was also found to enhance. However, E _a activation energy for decomposition was also found to decrease with each catalyst.     

Vibrational spectra and structure of trinitromethane

The vibrational spectrum of trinitromethane was interpreted in terms of the additive interatomic interaction model on the basis of experimental infrared and Raman spectra of HC(NO₂)₃, DC(NO₂)₃, HC(¹⁵NO₂)₃ and normal coordinate analysis. The frequency assignment results were used in discussing its structure. It was shown that the symmetry of trinitromethane is below C₃ in the liquid state.     

Synthesis and crystal structure of New Amminecopper(II) Nitrates: [Cu(NH3)2](NO3)2 and [Cu(NH3)](NO3)2

[Cu(NH₃)₂](NO₃)₂ ( I ) and [Cu(NH₃](NO₃)₂ ( II ) were synthesized by interaction of molten NH₄NO₃ with [Cu(NH₃)₄](NO₃)₂ and Cu(NO₃)₂ · 3 H₂O, respectively, at 180 to 195°C for 24 hr. According to X-Ray single crystal analysis, I is orthorhombic (sp. gr. Pbca) with a = 5.678(1), b = 9.765(2), c = 11.596(2) Å, Z = 4, R = 0.060; II is monoclinic (sp. gr. P2₁/c) with a = 6.670(1), b = 8.658(2), c = 9.661(2) Å, β = 101.78(2)°, Z = 4, R = 0.027. In both structures, the nearest coordination environment of Cu is a slightly distorted square formed by N (from NH₃) and O atoms (from NO₃ groups). The structure of I consists of centrosymmetrical [Cu(NH₃)₂](NO₃)₂ molecules linked by hydrogen bonds. The Cu? N and Cu? O distances are 1.98 and 2.01 Å, respectively. In II , the Cu? N distance is 1.95 Å, the Cu? O distances are 1.96, 2.02, and 2.03 Å. The [CuO₃NH₃] squares are connected by NO₃ bridges into zigzag chains, which are linked into layers by longer Cu? O interactions (2.31 Å). Obviously, the layers are additionally strengthened and held together by hydrogen bonds.     

Redox reactions between metal nitrates and polyols with the formation of nanopowders

The reduction of metal nitrates (Cu(NO₃)₂ · 6H₂O, AgNO₃, and Ni(NO₃)₂ · 6H₂O) by polyols under hydrothermal conditions at temperatures of 150–250°C was studied. The possibility of synthesizing copper, silver, and nickel powders with average particle sizes of 10 to 150 nm depending on the concentration of initial reagents, the temperature, and the nature of a reducer was established using X-ray diffraction analysis and atomic force microscopy. Lanthanide and alkali-earth nitrates were shown to form highly dispersed powders of metal carbonates with an average particle size of ～23 nm under similar conditions.