Acetamidiniumhexafluorometallate von Aluminium,Gallium, Indium,Vanadium, Chrom,Mangan, Eisen und Cobalt

Acetamidiniumhexafluorometallates of Aluminium, Gallium, Indium, Vanadium, Chromium, Manganese, Iron and Cobalt The title compounds were crystallized from F-containing aqueous solutions of their hexafluoro-metallate acids by adding acetamidine. Their unit cells were determined and the thermal decomposition was investigated thermoanalytically. The crystal structure of [CH₃C(NH₂)₂]₃AlF₆ was determined: Space group P4₁2₁2/P4₃2₁2, a = 8,987(1), c = 17,894(3) Å, R = 0,054. The unit cell parameters: .     

Synthesis,region of existence,structural characteristics,and conductivity of BI(CR,FE)VOX solid solutions

The results of our studies of solid solutions of the general composition Bi₄V_{2 − x} Fe _x/2Cr _x/2O_{11 − δ} are presented. The crystal-chemical parameters of different polymorphic modifications of BIMEVOX were determined. The particle size distribution was determined by laser diffraction and optical microscopy. The surface of sintered preforms was studied by scanning electron microscopy. The conductivity of sintered poly-crystalline samples as a function of temperature and composition was studied by impedance spectroscopy. The conductivity was depends on the procedure for the synthesis of solid solutions. The most promising compositions were revealed.     

Synthesis, structures, physicochemical properties, and crystal-chemical systematics of M 2II AIIUO6 (MII = Pb, Ba, Sr; AII = Mg, Ca, Sr, Ba, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb) compounds

Pb₂A^IIUO₆ (A^II = Mg, Ca, Sr, Ni, Zn, Cd) compounds were synthesized by high-temperature reactions in the solid phase. For the Pb₂MgUO₆, Pb₂CaUO₆, and Pb₂CdUO₆ compounds, the crystal structures (space group P2₁/n) were refined by the Rietveld method. It was demonstrated that these structures belong to the perovskite structure type. Crystal-chemical systematics was performed for all synthesized perovskites. High-temperature X-ray diffraction and differential scanning calorimetry were used to study the thermal stability and phase transitions, determine the thermal expansion coefficients, and elucidate the effect of atoms located in octahedral and cuboctahedral positions on the heating behavior of the structure. The standard enthalpies of formation of the Pb₂A^IIUO₆ compounds were determined by reaction calorimetry.     

Syntheses of MSn(OH)6 by coprecipitation and of MSnO3 by thermal decomposition (M = Mg,Co, Zn,Mn, Cd,Ca, Sr,Ba)

MSn(OH)₆ (M = Mg, Co, Zn, Mn, Cd, Ca, Sr, and Ba) and their solid solutions were synthesized by coprecipitation from aqueous solutions of Na₂Sn(OH)₆ complex and MCl₂. MSnO₃ and their solid solutions were prepared by thermal decomposition of these MSn(OH)₆ precipitates. Coprecipitation procedures were established, and structures of MSn(OH)₆ and MSnO₃ were discussed in relation to mean radius of M²⁺ ions. The morphology of particles of these hydroxides and oxides were also observed. In order to obtain a single phase precipitate MSn(OH)₆, the concentration of both solutions of Na₂Sn(OH)₆ and MCl₂ had to be as low as 0.1 mol/l. The pH-value was kept above 11, and so acidic solution of MCl₂ was added slowly to basic solution of Na₂Sn(OH)₆. The structure of MSn(OH)₆ depended strongly of mean radius of M²⁺ ions, being cubic with NaCl-type arrangement of M²⁺ and Sn⁴⁺ cations below 1.26 Å and hexagonal above 1.26 Å. Crystalline MSnO₃ was obtained by the decomposition of MSn(OH)₆ precipitates above 500–600°C. The structure of MSnO₃ was also related with mean radius of M²⁺ ions closely, ilmenite-type below 1.09 Å and pervoskite-type above 1.14 Å. In perovskite-type structure, a gradual decrease in lattice distortion and rapid increase in crystal volume were observed with the increase in radius of M²⁺ ions. An interesting morphology change was observed from CaSn(OH)₆ precipitates to CaSnO₃, the particles with either cubic or flower-like appearance in hydroxide becoming porous in oxide without appreciable change in particle appearance.     

Partitioning of the quinary reciprocal system Li,K‖F,Cl,Br,MoO4 into simplexes and the investigation of its partitioning and stable elements

The quinary reciprocal system Li,K‖F,Cl,Br,MoO₄ was partitioned into simplexes using graph theory. A tree of phases of the system was constructed, and stable elements were identified. The chemical interaction in the system Li,K‖F,Cl,Br,MoO₄ was described by the ion balance method. The stable tetrahedra LiF-KCl-KBr-K₂MoO₄, LiF-KCl-KBr-LiKMoO₄, and LiF-Li₂MoO₄-KCl-KBr and the united stable pentatope LiF-KF-KCl-KBr-K₂MoO₄ were studied by differential thermal analysis, and phase states in the studied simplexes were determined. The compositions of crystallizing phases in the bulk of the studied tetrahedra and pentatope were confirmed by X-ray powder diffraction analysis.     

Synthesis, structure, and impedance spectra of iron-containing bismuth titanates

Iron-containing bismuth titanates with a cubic pyrochlore Bi_1.6Fe _x Ti₂O_{7 ? δ} structure were synthesized by the ceramic method. The region in which iron-containing pyrochlores are formed was determined. The pycnometric specific gravity of the samples was measured. Based on XRD and pycnometric specific gravity data, it was concluded that iron atoms lie in the bismuth sublattice. The electric properties of the materials were studied by high-temperature impedance spectroscopy. A strong effect of polarization on the impedance spectra was found.     

Determination of Arsenic,Cadmium, Cobalt,Chromium, Nickel,and Lead in Cosmetic Face-Powders: Optimization of Extraction and Validation

An analytical method for the quantification of toxic metals in face-powders is presented and discussed. Acid digestion with HNO₃-H₂O₂ or HNO₃-HCl was performed and compared with total digestion by HF. The digestion with HNO₃-H₂O₂ was the most suitable for these purposes. Analyses were performed by inductively coupled plasma atomic emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS), whose performances were compared by analyzing three different certified reference materials. The analysis of five commercial face-powders revealed the presence of all the considered metals in the range 0.06–8.0 µg/g. To simulate the bioaccessibility of metals in physiological conditions, a digestion with a simulated sweat solution was performed. In this case, the analysis of the same face-powder samples provided results below the limit of quantification, suggesting low bioaccessibility of the considered trace elements.     

Synthesis,structures, and physicochemical properties of Sr<Subscript>2</Subscript>A<Superscript>II</Superscript>UO<Subscript>6</Subscript> (A<Superscript>II</Superscript> = Mg,Ca, Sr,Ba, Mn,Fe, Co,Ni, Zn,and Cd) compounds

Sr₂A^IIUO₆ (A^II = Mg, Ca, Sr, Ba, Mn, Fe, Co, Ni, Zn, and Cd) compounds were synthesized by high-temperature reactions in the solid phase. The crystal structure (space group P2₁/n) was refined by the Rietveld method for Sr₂MgUO₆, (Sr_0.5Ba_0.5)₂SrUO₄, and Sr₂CdUO₆, which were synthesized for the first time. IR spectral characteristics were studied. The standard enthalpies of formation of the compounds were determined by reaction calorimetry.     

Surfactant-free Ionic Liquid Microemulsions of N,N-dimethylformamide, 1-butyl-3-methylimidazolium hexafluorophosphate,and toluene

The phase diagram of a ternary system consisting of the hydrophobic ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF₆), N, N-dimethylformamide (DMF), and toluene was prepared at 25°C. A single-phase microemulsion and a multiphase region were demonstrated. The systems were nonaqueous IL microemulsions in the absence of traditional surfactants. The single-phase region could be divided into toluene-in-bmimPF₆, bicontinuous, and bmimPF₆-in-toluene subregions by electrical conductivity, similar to the case of surfactant-based IL microemulsions. And by the use of methyl orange as an absorption probe, the polarity of the bmimPF₆-in-toluene microemulsion was probed by UV–vis spectroscopy. The polarity of bmimPF₆ domains increased with increasing bmimPF₆ constant, and a relatively constant polarity was obtained when bmimPF₆ was increased to a certain extent.     

Thermochemistry of AII(VUO6)2 · nH2O Compounds (AII = Mn, Fe, Co, Ni, Cu, Zn, Cd)

Standard enthalpies of formation of uranovanadates of 3(4)d transition metals at 298.15 K were determined. The isobaric heat capacity of Co(VUO₆)₂ · 4H₂O was measured. The standard Gibbs functions of formation of the compounds were calculated on the basis of these data using approximate methods of absolute entropy calculation. The thermochemical characteristics of the synthesis and dehydration of uranovanadates were considered.     

The influence of oxygen pressure on phase equilibria in the Ln-Mn-O (Ln = Sm, Tb, Dy, Yb, and Lu) systems

The influence of oxygen pressure on phase equilibria during thermal dissociation in the Ln-Mn-O (Ln = Sm, Tb, Dy, Yb, and Lu) systems was studied by the static method on a vacuum circulation unit with subsequent X-ray analysis of quenched solid phases. The reduction of the double oxides was found to occur according to the reactions LnMn₂O₅ = LnMnO₃ + (1/3)Mn₃O₄ + (1/3)O₂, LnMnO₃ = (1/2)Ln₂O₃ + MnO + (1/4)O₂, for which the temperature dependences of equilibrium oxygen pressure were determined over the temperature range 973–1220 K. The Gibbs energies of dissociation of the double oxides were calculated. Interrelation between the type of lanthanides and the thermal properties of the compounds was analyzed.     

Liquid Fertilizers Based on Dolomite,Nitric Acid,and Ammonia

Solubility in the system Ca(NO₃)₂-Mg(NO₃)₂-NH₄NO₃-H₂O was studied by the visual-polythermic method. The crystallization curves and the chemical composition of the solid phase were determined. The chemical composition of solutions with crystallization temperature of 0°C was calculated. A technological scheme for production of liquid fertilizers containing nitrogen, calcium, and magnesium was proposed.     

Electron diffraction,x-ray diffraction,and CNDO/2 analysis of the conformations,molecular geometry,and internal rotation potentials of aryldichloro- and aryldibromoarsines

A structural study was carried out on o-ClC₆H₄AsCl₂ (I), o-BrC₆H₄AsBr₂ (II), C₆H₅AsBr₂ (III), and p-BrC₆H₄AsBr₂ (IV). The normal mode frequencies and shapes were calculated and gas-phase electron diffraction was used to establish the geometric parameters of III and IV. The structure of IV was determined by x-ray diffraction structural analysis. The experimental results for I–IV (I and II were studied in previous work) were interpreted on the basis of CNDO/2 calculations for I–III.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Branch, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 30, No. 5, pp. 61–69, September–October, 1989.     

Photocatalytic activity and intercalation of layered perovskite-like tantalates ANdTa2O7 (A = H,Li, Na,K, Rb,Cs)

Layered perovskite-like oxides ANdTa₂O₇ (A = H, Li, Na, K, Rb, Cs) were synthesized and characterized by means of diffuse reflection spectroscopy, thermogravimetry, and simultaneous thermal and X-ray phase analysis. Comparative analysis of the photocatalytic activity of ANdTa₂O₇ in the UV-induced hydrogen evolution from an aqueous isopropanol solution was performed. NaNdTa₂O₇ and HNdTa₂O₇ are able to intercalate water to the interlayer space. The compositions and thermal stability ranges of intercalates were determined. No explicit correlation between the photocatalytic activity of layered oxides and their ability to intercalate water to the interlayer space was found.     

DFT,AIM, and NBO study of the interaction of simple and sulfur-doped graphenes with molecular halogens,CH3OH,CH3SH,H2O,and H2S

Graphene is an important material in adsorption processes because of its high surface. In this work, the interactions between graphene (G), S-doped graphene (SG), and 2S-doped graphene (2SG) with eight small molecules including molecular halogens, CH₃OH, CH₃SH, H₂O, and H₂S were studied using density functional theory calculations. The adsorption energies showed that the SG was the best adsorbent, fluorine was the best adsorbate, and all molecular halogens were adsorbed on graphenes better than the other molecules. Most adsorption processes in the gas phase were exothermic with small positive ΔG _ads. Moreover, the solvent effect on the adsorption process was examined and all ΔH _ads and ΔG _ads values for adsorption processes tended to be more negative in all solvents. Therefore, most adsorption processes in the solvents were thermodynamically favorable. The second order perturbation energies obtained from NBO calculations confirmed that the interactions between molecular halogens and our molecules had more strength than those of other molecules. The Laplacian of ρ values obtained from the AIM calculations indicated that the type of interaction in all our complexes was one of closed shell interaction. The MO results and DOS plots also revealed that sulfur doping could increase the conductivity of graphene and this conductivity was enhanced more when they interacted with molecular halogens.     

Near-infrared spectroscopic measurements of volume expansion and composition of CO2-expanded ethyl acetate,acetone, tetrahydrofuran,acetonitrile, methanol-OD,and dimethyl sulfoxide

CO₂-expanded liquid (CXL) is a mixture of organic solvent with high-pressure CO₂ whose volume is increased by CO₂ dissolved in it. CXLs have attracted attention as tunable solvents, because the solvent properties can be widely controlled by the pressure. The volume expansion and the solubility of CO₂ were measured by near-infrared spectroscopy for 6 CXLs at various pressures up to 55 bar and 40 °C. The molarity of organic solvent was determined from the absorbance of the 3ν and 2ν + δ bands, and that of CO₂ was obtained from the area of the 3ν₃ band, whose peak shifted to higher frequency with increasing pressure due to a decrease in the molecular interaction around CO₂. The expansion coefficient was shown to be an increasing function of the pressure with larger slope at higher pressure, and the mole fraction of CO₂ in the liquid phase was an almost linearly increasing function of the pressure. The results were in quantitative agreement with the literature data measured by conventional sampling method, indicating the validity of the spectroscopic method.     

Pigmentary properties of rutile TiO2 modified with cerium, phosphorus, potassium, and aluminium

The influence of different modifiers, phosphorus, potassium, aluminium, and cerium on the pigmentary properties of TiO₂ was studied. The phase composition and distribution of modifiers in prepared TiO₂ products was investigated using XRD analysis, the selective leaching method, and ICP-AES technique. The optical properties, photoactivity, morphology, and surface area of modified TiO₂ were determined by spectrophotometric, fluorescent, SEM, and BET measurements. The research was directed towards obtaining a pigmentary TiO₂ with the highest possible photostability. It was found that the final calcination temperature, at which the anatase-rutile transformation rate was > 97 %, depended on the kind and amount of the modifiers introduced into hydrated titanium dioxide. In comparing the colour of TiO₂ products modified with Ce, it was found that the addition of K to the TiO₂ series caused an increase in all the optical properties examined. The presence of K and Al in TiO₂ modified with Ce resulted in decreased photocatalytic activity. The photostability of TiO₂ modified with Ce and K improved with an increase in P₂O₅ content. The highest photostability was measured for the TiO₂-CePKAl series. It was concluded that the differences in both the optical properties and photoactivity of TiO₂ depended on its phase composition and the distribution of modifiers in the products obtained.     

Synthesis, structure, and conductivity of BINBVOX ceramics

The preparation and the structure and transport characteristics of Bi₄V_{2 ? x} Nb _x O₁₁ (BINBVOX) were studied. A comparative analysis of the synthesis of solid solutions was performed. The sintering of ceramics and the electrical conductivity as a function of temperature, composition and partial oxygen pressure were studied.     

Extraction of Nitric,Perchloric, and Hydrochloric Acid by N,N-dibutyl Diethyl Carbamyl Phosphonate

Extraction of nitric, perchloric, and hydrochloric acid by N,N-dibutyl diethyl carbamyl phosphonate in carbon tetrachloride was investigated. The data obtained are treated in terms of stepwise neutralization of the acid with the formation of species y · HA and y · 2HA in the organic phase, where y stands for the extractant and HA for the acid. The equilibrium constants, K?₁ and K?₂ for nitric acid were found to equal 0.24 ± 0.02 and 0.017 ± 0.005, respectively. In case of HClO₄ and HCl K?₁ were found to equal 0.031 ± 0.003 and 0.0039 ± 0.0005, respectively. A third phase was observed when extraction of HClO₄ was performed using acid concentration higher than 3.5 molar. The preference for partition of different acids was discussed on the light of the competition of the proton between the acid anion, water and the basic extractant as well as the degree of the ionization of different acids.     

Assessment of the polluting effects of the Iponri-Alaka Canal,Lagos State,Nigeria

ABSTRACT

The polluting effects of Iponri-Alaka Canal in Surulere area of Lagos State on the environment have been studied using six sampling points. The study aimed at assessing the effects of exposure to pollutants on humans and other life forms. The quality of air, wastewater and sediments was assessed between March and August 2017. The concentrations of SO₂ and H₂S were measured using MSA Altair 5X. Temperature, pH and DO were measured in-situ using Thermometer, pH meter and Winkler method, respectively. TSS, TDS, TS, TA, TH, BOD, chloride Cl^?, PO₄^3-, SO₄^2- and NO₃^? were determined using appropriate standard methods in the laboratory. EC and some heavy metals (Cr, Pb, Mn, Cd and Ni) concentrations were determined using conductivity meter and Atomic Absorption Spectroscopy, respectively. The results showed that pH, TS, DO and TH were well within the WHO and FEPA maximum limits. EC, SO₄^2- and TDS were observed to be higher than guideline values only at one sampling point. The TSS, BOD, TA, NO₃^? and PO₄^3- were higher than WHO and FEPA guideline limits at all sampling points. Cr was seen to be within, while Pb and Mn were higher than WHO and FEPA guideline values. Cd was higher than guideline values only at two sampling points. Ni was below detection concentration at all the sampling points.

The concentration of SO₂ was seen to be higher than WHO and NESREA guideline values at two sampling points, while H₂S concentration was higher than WHO limit at all the six sampling points.