Density and Viscosity of a Ternary $$ x_{1} $$ 1-He xene(1) + $$ x_{2} $$ x2 1-Octene(2) + (1 − − x2) 1-Decene(3) Mi xture at High Temperatures and High Pressures

The density and viscosity of a ternary 1-hexene(1) + 1-octene(2) +1-decene(3) mixture (\( w_{1} = w_{2} = w_{3} = 0.333 \) weight fractions or \( x_{1} = 0.4257 \),\( x_{2} = 0.3190 \), \( x_{3} = 0.2553 \) mole fractions of 1-hexene, 1-octene, and 1-decene, respectively) have been simultaneously measured over the temperature range from (298 to 471) K and at pressures up to 196 MPa using a combined method of hydrostatic weighing and falling-body techniques, respectively. The combined expanded uncertainties of the density, pressure, temperature, concentration, and viscosity measurements at the 95% confidence level with a coverage factor of k = 2 are estimated to be (0.15 to 0.30)%, 0.05%, 0.02 K, 0.005 mol%, and (1.5 to 2.0)%, respectively. The measured densities and viscosities were used to calculate the excess molar volumes and viscosity differences. The excess molar properties (\( G_{\text{m}}^{\text{E}} , \, H_{\text{m}}^{\text{E}} , \, S_{\text{m}}^{\text{E}} \) and \( C_{\text{pm}}^{\text{E}} \)) and their pressure derivatives as a function of temperature and pressure have been calculated using the derived excess molar volumes. The measured viscosities were used to develop a theoretically based viscosity correlation model (Arrhenius–Andrade type equation) for the mixture.     

Compensation Between the Entropic and Enthalpic Changes Arising from Changes in Solvent–Solvent Interactions in Mixed Solvents

A theorem presented by Professor Ben-Naim (J Phys Chem 82:874–885, 1978) states that the standard state enthalpy and entropy changes arising from changes in the solvent structure that are induced by solvation of a solute cancel exactly in the standard state Gibbs energy. In this paper this is explored by consideration of the thermodynamics of transfer of electrolytes in mixed solvents, using previously developed models of the solvation process. Two cases are considered. One is random solvation, where curvatures in plots of the transfer enthalpies and entropies, which arise from changes in solvent–solvent interactions, exactly compensate in the transfer Gibbs (free) energies, which are sensibly linear with solvent composition. The second type of system are those with strong preferential solvation where it is found that the transfer Gibbs energies can be accounted for quantitatively in terms of changes in the solute–solvent interactions, with no contribution from changes in solvent–solvent interactions. The results are entirely consistent with the Ben-Naim theorem.     

Speciation and Multinuclear NMR Spectroscopic Studies of Di- and Trimethyltin(IV) Moieties with MESNA in Aqueous Medium

The interaction of Me₂Sn(IV)²⁺ and Me₃Sn(IV)⁺ with a prodrug, sodium 2-mercaptoethane sulfonate (HSCH₂CH₂SO₃Na, MESNA) abbreviated as (HL), has been studied potentiometrically in aqueous solution (I = 0.1 mol·L^?1 KNO₃, 298 K). The concentration distribution of various species formed in the solution was studied with changes in pH (~3–11). A strong coordination of MESNA with metal through the S atom of thiol group has been found. In the Me₂Sn(IV)–HL system, the species [Me₂Sn(L)]⁺ (53.1–75.6%) is predominant at acidic pH (3.73 ± 0.02) and the species [Me₂Sn(L)₂OH]^? (29.4–38.5%) is predominant at basic pH (10.32 ± 0.08). In contrast, for the Me₃Sn(IV)⁺ system, [Me₃SnL] (37.0–57.4%) is the major species at pH 7.65 ± 0.03 and [Me₃Sn(OH)] (49.9–67.2%) and [Me₃Sn(L)(OH)]^? (30.2–46.5%) are the major species at pH 11.05 ± 0.01. However, at physiological pH (7.01 ± 0.32), in both (1:1) and (1:2) Me₂Sn(IV)–HL systems, the species [Me₂Sn(L)(OH)] (67.2–89.9%) is predominant, whereas for Me₃Sn(IV)–HL (1:1) and (1:2) systems, [Me₃Sn(OH)] (53.5%) and [Me₃SnL] (56.8%) are the respective predominant species. In order to characterize the possible geometry of the proposed complex species, multinuclear (¹H, ¹³C and ¹¹⁹Sn) NMR studies were carried out at different pHs. No polymeric species were detected in the experimental pH range.     

Structural Inhomogeneity in Electrolyte Solutions: The Calcium Perchlorate–Water System

A new approach has been proposed to study the structure of aqueous electrolyte solutions. NIR, Raman and attenuated total reflectance, Fourier transform infra-red (ATR FTIR) spectra have been measured for aqueous calcium perchlorate solutions in the 0.22–4.3 mol·L^?1 (0.22–7.46 mol·kg^?1) concentration range at 25 °C. By the methods of principal component analysis (PCA) and multivariate curve resolution—alternating least squares (MCR-ALS) the number, spectra and concentration profiles have been determined for spectroscopically distinguishable forms of water and ClO ₄ ^? ion in solutions. The results have been analyzed using a phenomenological model, establishing thereby: concentration ranges for structural rearrangements of the solution, the nature of structural microirregularities and different states of the ClO ₄ ^? ion in the areas of domination of the natural water structure, and of cybotactic groups of calcium perchlorate hexa and tetra hydrates.     

Solution Chemistry of Arsenic Anions in the Presence of Metal Cations

The interaction of arsenic(V) and arsenic(III) oxyanions with metal cations was investigated by potentiometry under temperature and ionic strength conditions approaching those prevailing in natural waters. The selection includes the major metal cations and some other ions of high environmental relevance. Ionic pairs [M(As^VO₄)]^?, [M(HAs^VO₄)] and [M(H₂As^IIIO₃)]⁺ formation is suggested for all +2 metal cations, based on the potentiometric results. These ion-pairs between arsenic anions and other metal cations are hardly ever mentioned or taken into account when arsenic speciation in natural waters is considered. These results provide the basis for studying arsenic speciation in natural aquatic systems, on which environmental fate, bioavailability and toxicity of the element depend. Some extrapolations to the conditions of the natural waters are presented as well as some insights into the adsorption process onto hydrous oxides.     

Combination of atomic lines and molecular bands for uranium optical isotopic analysis in laser induced plasma spectrometry

Radionuclide concentrations in wharf roaches inhabiting coastal areas of Honshu, Japan, were investigated in October 2011 and June 2012. Relative high concentrations of ^110mAg (2.1–127 Bq kg-wet^?1), ¹³⁴Cs (2.6–61 Bq kg-wet^?1), and ¹³⁷Cs (3.5–92 Bq kg-wet^?1) were detected in specimens from the eastern Honshu areas. Significantly lower ¹³⁷Cs concentrations (0.7–1.6 Bq kg-wet^?1) were detected in specimens from western and northern Honshu. The decay-corrected ¹³⁷Cs concentration was significantly inversely correlated with the distance from the Fukushima Dai-ichi Nuclear Power Plant. Thus, wharf roach may serve as a good bioindicator for monitoring radioactive contamination of its habitats.     

Plutonium concentration and <Superscript>240</Superscript>Pu/<Superscript>239</Superscript>Pu isotopic ratio in the surface soils from the Jiuquan region in northwestern China

Surface soil samples collected in the Jiuquan region in the downwind area of the Chinese nuclear test site (CNTs) were analyzed for Pu isotopes. The ^239+240Pu activities ranged from 0.025 ± 0.009 to 0.89 ± 0.16 mBq g^?1, varying significantly with different sampling sites. The Dunhuang city that is located in the southwestern part of the Jiuquan region received the heaviest Pu deposition (^239+240Pu activities, 0.23–0.89 mBq g^?1). Most of the ²⁴⁰Pu/²³⁹Pu isotopic ratios were similar with that of the global fallout. However, the low values (0.080–0.147) observed in three sampling sites further supported the finding of Pu originated from CNTs in that region.     

Thorium(IV) and neptunium(V) uptake from carbonate containing aqueous solutions by HDTMA-modified natural zeolites

The ²³²Th-uptake ([Th(IV)]° = 9.7 × 10^?5 M) from carbonate solutions ([CO ₃ ² ]_tot = 0.25 M, 9.0 < pH_c < 10.8) by raw and HDTMA-modified HEU-type zeolitic-, chabazitic- and phillipsitic-tuffs was investigated. The strong uptake by the HDTMA-tuffs at pH_c≈9 was assigned to the Th(CO₃) ₅ ^6? and ThOH(CO₃) ₄ ^5? predominance. The sorption coefficients (R _d) decreased with increasing pH_c indicating carbonate competition. Enhanced R _d values for pH_c > 10.5 are likely due to ThO₂(am)-precipitation. The ²³⁷Np-uptake ([Np(V)]° = 2.6 × 10^?5 M) from carbonate solutions ([CO ₃ ² ]_tot = 0.25 and 3.0 × 10^?4 M) by raw and HDTMA-modified HEU-type zeolitic tuff and pulverized pure heulandite crystals was studied under Ar-atmosphere at 6 < pH_c < 11. The R _d values for both elements indicated the modified tuffs potential to remove tetravalent- and pentavalent actinides from environmental matrices.     

Substituted sulphoxide ligands in piperidinium based ionic liquid: novel solvent systems for the extraction of Pu<Superscript>4+</Superscript> and PuO<Subscript>2</Subscript><Superscript>2+</Superscript>

Sulphoxide ligands in piperidinium based ionic liquid were demonstrated as highly efficient, selective and environmentally benign systems for the extraction of plutonium from acidic aqueous solution. The extraction followed ‘cation-exchange mechanism’ via [Pu(NO₃)·L]³⁺ and [PuO₂(NO₃)·L]⁺ species. The extraction efficiency followed the trend: APSO > BPSO > BMSO. The phenyl substituted sulphoxides showed higher affinity for plutonium due to a combination of steric as well as electronic factors. Extraction process was thermodynamically spontaneous for all three solvent systems. Oxalic acid and sodium carbonate were suitable for quantitative stripping of Pu⁴⁺ and PuO₂ ²⁺, respectively. APSO in ionic liquid showed good radiolytic stability.     

Chemical investigation of three plutonium–beryllium neutron sources

Thorough physical and chemical characterization of plutonium–beryllium (PuBe) neutron sources is an important capability with applications ranging from material accountancy to nuclear forensics. Characterization of PuBe sources is not trivial owing to range of existing source designs and the need for adequate infrastructure to deal with radiation and protect the analyst. This study demonstrates a method for characterization of three PuBe sources that includes physical inspection and imaging followed by controlled disassembly and destructive analysis.