Excess Properties for the Binary System Diethylene Glycol Dibutyl Ether � Ethanol

This paper reports propertiesdata at 20, 25 and 30 0C and 1 atmosphere pressure for diethylene glycol dibutyl ether - ethanol system depending on concentration. The experimental values of density and viscosities of pure components and mixtures were correlated with temperature. The excess properties were determined from experimental data of densities and viscosities. These excess values were correlated to Hwang and Redlich-Kister equations. The value of excess molar volume for equimolar solution was compared with the values calculated from the Flory and Prigogine-Flory-Patterson theories.

Column Separation of Am(III) and Eu(III) by α-Zirconium Phosphate Ion Exchanger in Nitric Acid

The trivalent lanthanide-actinide separations are a major challenge in reprocessing of nuclear fuels. To achieve this, commonly organic extractants and solvents are utilized in elaborate processes. Here we report a simple new method that can perform a supportive or alternative role. A nanocrystalline α-zirconium phosphate ion exchanger was utilized for Eu(III)/Am(III) column separation. Comprehensive preliminary studies were done using batch experiments to optimize the final separation conditions. The distribution coefficients for Eu were determined as a function of pH (from 0 to 3) and salinity (Na, Sr). The distribution coefficients for Am were determined as a function of pH, and Eu concentration, from 1:40 to 10,000:1 Eu:Am molar ratio. The exchanger always preferred Eu over Am in our experimental conditions. Separation factors (Eu:Am) of up to 400 were achieved in binary Eu-Am solution in pH 1. The breakthrough capacity was determined in dynamic column conditions using Eu: 0.3 meq∙g−1, which is approximately 4% of the theoretical maximum capacity. Two types of hot column separation tests were conducted: (i) binary load (selective Am elution), and (ii) continuous equimolar binary feed. In both cases separation was achieved. In (i), the majority (82% of the recovered 93%) of Am could be purified from Eu with extremely high 99.999% molar purity, while alternatively even more (95% of the recovered 93%) at a lower purity of 99.7 mol %. In (ii), up to 330 L∙kg−1 of the equimolar solution per mass of the exchanger could be treated with Am purity above 99.5 mol % in the total eluate. Alternatively, up to 630 L∙kg−1 above 95 mol %, or up to 800 L∙kg−1 above 90 mol % purities.

Effect of the soil type on the biocementation process by enzymatic way

The effect of the enzymatic CaCO3 precipitation on the behaviour of four soils (from a poorly graded sand to a fine and organic soil) is studied in this work. The analysis is based on the results of UCS tests, where the results from the non-stabilised specimens are compared with specimens stabilised with a urease concentration of 8 kU/L and an equimolar solution of urea-CaCl2 of 0.5 mol/L. Additionally, pH and scanning electron microscopy (SEM) tests with energy dispersive X-ray (EDX) analyses are performed to analyse the microstructure and the local chemical composition. The results of the UCS tests show that, in the case of the sandy and silty soils, the process of enzymatic CaCO3 precipitation potentiates the strengthening of the soils while, in the organic soil, a detrimental effect is observed. The SEM tests show the existence of vestiges of calcium in the biostabilised soils studied.

Zinc-quercetin complex: From determination to bioactivity

Flavonoids are a group of polyphenolic compounds widely present in the herbal world and playing an important role in the human diet. The flavanol quercetin makes up 70% of the total daily intake of flavonoids. Quercetin is able to complex with many metal ions, and it exhibits potent antioxidative ability. Using the equimolar solution variation method, it was confirmed that quercetin makes a complex with the zinc(II) ion at pH 5.25, in a stoichiometric ratio quercetin:zinc(II) ion = 2:1, with the absorption maximum l=363 nm. This fact was used to develop a simple, precise and accurate assay to determine the content of quercetin in various samples of heterogeneous composition. The proposed indirect spectrophotometric method can selectively determine quercetin in concentrations ranging from 0.1 to 6.0 mgL-1, with LOD and LOQ estimated as 0.03 mgL-1 and 0.1 mgL-1, respectively. The reliability of the proposed method was confirmed by a previously developed RP-HPLC/UV method. The proposed method was successfully used to determine the quercetin content in dietary supplement tablets, capsules and two onion extracts, with high reproducibility. The antioxidative ability of quercetin and the zinc(II)-quercetin complex was determined using DPPH and FRAP methods. The same samples were tested for antimicrobial activity against seven laboratory control strains of bacteria and one strain of yeast. As a result of those tests, there are no obstacles to combine quercetin and zinc in the same supplement formulation.

The formation of the salt and neutral molecule cocrystal from equimolar solution of heliamine and bicyclo[2.2.1]hept-5-ene-endo-2,3-dicarboxylic acid

The possible interaction of 6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline (heliamine) with bicyclo[2.2.1]hept-5-ene-endo-2,3-dicarboxylic acid anhydride has been studied. Instead of the reaction with heliamine, the acid anhydride was hydrolyzed into the appropriate dicarboxylic acid. An equimolar mixture of unreacted heliamine and in-situ-generated dicarboxylic acid crystallized in space group P21/c. The comprehensive study of the obtained crystals shows that the peculiarities of the crystallization process lead to the formation of the salt-cocrystal structure where the dianion interacts simultaneously with two cations forming a chain as the primary structural motif. The neutral molecules of dicarboxylic acid link the dianions of the neighbouring chains, forming a layer as the secondary structural motif. As a result, the stronger hydrogen bonds formed by the neutral molecules play a secondary role in the crystal structure formation.

Removal of radiocobalt from EDTA-complexes using oxidation and selective ion exchange

Methods for the removal of radiocobalt from an ethylenediaminetetraacetic acid (EDTA) complex of Co(II) (aqueous solution containing 10 μM Co(II) and 10 μM or 50 μM EDTA traced with 57Co) are presented. The studies examined a combination of different oxidation methods and the sorption of 57Co on a selective inorganic ion exchange material, CoTreat. The oxidation methods used were ultraviolet (UV) irradiation with and without hydrogen peroxide (H2O2), as well as ozonation alone or in combination with UV irradiation. Also, the possible contribution of Degussa P25 TiO2 photocatalyst to degradation of EDTA was studied. The best results for the equimolar solution of Co(II) and EDTA were achieved by combining ozonation, UV irradiation, Degussa P25 TiO2 and CoTreat, with approximately 94% sorption of 57Co. High values for the 57Co sorption were also achieved by ozonation (∼88%) and UV irradiation (∼90%) in the presence of CoTreat and Degussa P25 TiO2. A surplus of EDTA over Co(II) was also tested using 10 μM Co(II) and 50 μM EDTA. Only a slight decrease, to ∼88% sorption of 57Co, was detected compared to the value (∼90%) obtained with 10 μM EDTA.

Natrium-tetraethylammonium-tetrasulfid, Na+NEt4+S42−. Synthese und Kristallstruktur / Sodium Tetraethylammonium Tetrasulfide, Na+NEt4+S42−. Synthesis and Crystal Structure

NaNEt4S4 was obtained from an equimolar solution of Na2S4 and NEt4Cl in ethanol. Its crystal structure was determined by X-ray diffraction with 4175 observed unique reflexions, R = 0.044. Crystal data: a = 713.4(4), b = 1744.5(9), c = 1204.0(5) pm, β = 105.8(3)°, space group P21/n, Ζ = 4. In the structure, chains consisting of Na+ and S42− ions run in the a direction, every Na+ being coordinated by four terminal S atoms of S42− ions (two terminal, one chelating). The chains are separated by the NEt4+ ions.

Dicyclohexanecarbonylsulphate: a precursor of cyclohexyloxocarbenium ions

Dicyclohexanecarbonyl sulphate (1) is the prevailing species in the equimolar solution of cyclohexanecarboxylic anhydride and sulphur trioxide in liquid sulphur dioxide. The ionization of 1 to cyclohexyloxocarbenium ions occurs only in the presence of excess sulphur trioxide. Both 1 and C6H11CO+ are stable only in solution and at low temperature.

REACTIONS OF AMIDES AND RELATED COMPOUNDS: III. N.M.R. INVESTIGATION OF THE PROTONATION OF N,N-DIMETHYLNITROSOAMINE, N,N-DIETHYLNITROSOAMINE, AND N-NITROSOPIPERIDINE

Protonation of N,N-dimethylnitrosoamine has been investigated by dissolving the nitrosoamine in different acids and recording the proton magnetic resonance spectra of these solutions. Concentrated sulfuric acid, sulfuric acid monohydrate, perchloric acid (72%), trifluoroacetic acid, and fluorosulfuric acid have been used in this study. Only in fluorosulfuric acid near 0 °C and lower was a new signal observed for the protonated nitrosoamine molecule. Integration of the peaks has shown that only one proton is captured by the nitrosoamine. The following structure is suggested for the protonated nitrosoamine.[Formula: see text]The n.m.r. spectra of fluorosulfuric acid solutions of N,N-diethylnitrosoamine and N-nitrosopiperidine also show separate signals for the captured proton.The n.m.r. spectrum of an equimolar solution of N,N-dimethylnitrosoamine, N,N-dimethylformamide, and trifluoroacetic acid in 2-nitropropane indicates that N,N-dimethylnitrosoamine is a weaker base.