Interaction of neptunyl with goethite (α-FeOOH), maghemite (γ-Fe2O3), and hematite (α-Fe2O3) in water as probed by X-ray photoelectron spectroscopy

The sorption behavior is studied and the physicochemical neptunium species existing on the surface of goethite (α-FeOOH), maghemite (γ-Fe₂O₃), and hematite (α-Fe₂O₃) are determined. Solvent extraction and X-ray photoelectron spectroscopy (XPS) are used to determine the neptunium surface species. The ion and elemental composition of the surface of the minerals and surface neptunyl NpO ₂ ⁺ complexes is determined using these data. Compounds containing neptunium(IV) or neptunium(VI) ions do not appear; rather, neptunyl (Np(V)O ₂ ⁺ group is complexed with surface hydroxide groups of α-FeOOH, γ-Fe₂O₃, and α-Fe₂O₃. Presumably, the oxygen atoms of iron oxides and water and/or carbonate (CO ₃ ^2- ) or nitrate (NO ₃ ^- ) group lie in the equatorial plane of the neptunyl (NpO ₂ ⁺ ) group.     

Hydroconversion of parafine LTP56-H over nickel/Na-mordenite catalysts

Nickel catalysts supported on Na-mordenite were used for paraffin LTP56-H hydroconversion into liquid material as a possible component for engine fuels. The effects of none-catalytic thermal treatment and catalytic conditions-zeolite type and reaction conditions (solvent) on the process of liquefaction of LTP56-H paraffin and physicochemical properties of catalysts were studied. The physicochemical properties of catalytic systems were investigated using XRD, TPR, TPD-NH3 and SEM-EDS methods.      

Biodegradation of Benzo[a]Pyrene through the use of algae

In this work for disposal of the biologically hard decomposed pollutant Benzo[a]Pyrene (BaP) photooxidation Chlorella kessleri was used. The simulation model system under the different experimental conditions (varying biomass and light intensity) was evaluated. For quantitative analysis of the decrease in BaP, GC/MS technique was used. The highest degradation efficiency was achieved in the case of biomass from the culture of live algae (29%) and light intensity at level of 13.5 W m^?2. When the dry biomass was used, degradation under the same conditions was lower because of lack of enzymatic activity in the system.      

Copper-cobalt ferrites as catalysts for methanol decomposition

Copper-cobalt ferrites with composition Cu_1?xCo_xFe₂O₄, where x= 0.2 and 0.8 were prepared by thermal treatment of co-precipitated precursor. The obtained materials were characterized by TG-DSC, XRD, Transmission and Conversion Electron Mössbauer spectroscopy and temperature programmed reduction with hydrogen. The catalytic properties of ferrites were tested in methanol decomposition to CO and hydrogen.      

Extraction properties of β-aminophosphine oxides towards lanthanides and alkaline earth metals

The investigation of the extraction properties of a series of polyoligodentate β-aminophosphine oxides 1–8 bearing from one to six phosphine oxide groups in a molecule towards Ln(III) and alkaline earth metals ions from neutral media has revealed that, using common diluents, the extraction efficiency increases with an increase of a number of P=O functions in a ligand. The addition of ionic liquid, namely 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([bmim][NTf₂]), significantly increasing the extraction efficiency and application of IL concentration of 0.05 M (in 1,2-dichloroethane) providing the maximum recovery of metal ions with Lu/La separation factor reaching up to 91. Hexapodal tris[bis(2-diphenylphosphorylethyl)aminoethyl]amine 8 demonstrates the highest extraction under all conditions applied and the separation factor for U and Eu of this compound exceeded 10³.      

Reaction of barbituric acid with organic azides and phosphonium ylides

Amination by organic azides has been carried out to provide aminobarbiturates by fusion of a triazole ring to the 5,6-positions of barbituric acid followed by cleavage and thermal elimination of nitrogen, whereas aza-Wittig reaction gave phosphoranylidene barbituric acid salts.      

Preparation of selectively protected protoescigenin derivatives for synthesis of escin analogs and neoglycoconjugates

Protoescigenin, the main aglycone of horse chestnut saponin mixture known as escin, was selected as substrate for exploratory chemistry towards selective protection, followed by propargyl ether formation and subsequent condensation with azido-monosaccharides, to obtain novel triazole linked conjugates of the triterpene.      

Comparative studies of Pd, Ru, Ni, Cu/ZnAl2O4 catalysts for the water gas shift reaction

The activity of monometallic Pd, Ru, Ni and Cu catalysts supported on spinel ZnAl₂O₄ for water gas shift reaction (WGS) was investigated. The physicochemical properties of each catalyst was studied by XRD, TPR, BET and chemisorption methods. The highest activity was obtained for Cu/ZnAl₂O₄ among the catalysts tested. The activation process carried out in a reducing atmosphere 5%H₂-95%Ar in the case of Cu/ZnAl₂O₄ system lead to the catalytic activity improvement. In the case of copper catalysts, the water gas shift reaction proceeded by the redox surface mechanism between Cu⁰/Cu⁺. The PdZn alloy formation after reduction at 350°C was shown.      

The first synthesis of 3-deoxyoripavine and its utilization in the preparation of 10-deoxyaporphines and cyprodime

The synthesis of 3-deoxyoripavine (7) was realized as a novel and promising intermediate towards the synthesis of the important class of dopaminergic and/or serotonergic 10-deoxyaporphines and the special pharmacological tool µ opioid antagonist cyprodime. Generally, the preparation of these valuable biologically active compounds was achieved in remarkable yields.      

The use of ultrasonic treatment for improvement of metrological performance of sorption atomic absorption determination of lead(II) and cadmium(II) traces

The optimal parameters for ultrasonic treatment (frequency 200–300 kHz, intensity 2–4 W cm^?2) were obtained to intensify Pb(II) and Cd(II) sorption concentration by carbon sorbent from apricot pit. The combined action of ultrasonic frequency of 18 kHz and 1 MHz on concentrate slurry increases its sedimentation stability from 3 to 180 minutes and decreases S_r value up to 7% at Pb(II), Cd(II) hybrid sorption atomic absorption determination in natural waters, brines, common salt.      

Rosehip extraction: Process optimization and antioxidant capacity of extracts

This article examines the extraction of rosehip to study the recovery of a number of compounds with antioxidant properties (polyphenols, flavonoids, and β-carotene). Two varieties of rosehip, cultivated and wild are used as raw material. A detailed study of the process kinetics at different operating conditions is carried out in order to determine appropriate processing parameters, which results in extracts with higher content of target compounds and higher antioxidant capacity. Data on the concentration of active components in the different parts of the fruit (skin, seeds, and pappi) are also obtained, which gives information about their distribution within the fruit. The comparison of wild and cultivated varieties demonstrates the better quality of the cultivated one. The results are useful for production of improved and enriched rosehip extracts with higher content of antioxidant substances that have proven beneficial effects on the human health.      

The synthesis, structure and physical properties of lanthanide(III) complexes with nicotinic acid

This article reports the synthesis of novel, rare-earth coordination complexes with nicotinic acid. Three compounds with the general formula Ln₂[(C₅H₄NCOO)₆(H₂O)₄] (Ln = Yb, 1; Ln = Gd, 2; Ln = Nd, 3) were prepared from relatively cheap and readily available reactants. Their compositions and structure were characterized by IR spectroscopy and single-crystal X-ray diffraction. The magnetic and thermogravimetric properties were also studied. The complexes consist of centrosymetric, dimeric molecules having all six nicotinato ligands coordinated with the central atom in the bidentate mode. The coordination environment of the Ln³⁺ for all three compounds is 8. Here we describe the crystal structure of Yb and Gd complexes with nicotinic acid.      

Excess interfacial energy change of solid/aqueous salt solution system with increasing salt concentration at a constant charge-determining ion activity based on the Gibbs equation and ionic components of charge

A thermodynamic equation relating the change of interfacial excess (Gibbs) energy in the solid/aqueous salt solution system, caused by a variation of concentration of inorganic salt at a constant charge-determining ion activity, temperature and pressure, is derived. The equation is based on the Gibbs equation and ionic components of charge parameters. On the basis of literature experimental data for the AgI/aqueous KNO₃ and TiO₂/aqueous NaCl systems it was shown that the interfacial excess energy decreases with increasing salt concentration due to variation of the ionic components of charge of the interface.      

Biosorption of reactive dye from aqueous media using Saccharomyces cerevisiae biomass. Equilibrium and kinetic study

The biosorption Brilliant Red HE-3B reactive dye by nonliving biomass, Saccharomyces cerevisiae, in batch procedure was investigated. Equilibrium experimental data were analyzed using Freundlich, Langmuir and Dubinin — Radushkevich isotherm models and obtained capacity about 104.167 mg g^?1 at 20°C. The batch biosorption process followed the pseudo-second order kinetic model. The multi-linearity of the Weber-Morris plot suggests the presence of two main steps influencing the biosorption process: the intraparticle diffusion (pore diffusion), and the external mass transfer (film diffusion). The results obtained in batch experiments revealed that the biosorption of reactive dye by biomass is an endothermic physical-chemical process occurring mainly by electrostatic interaction between the positive charged surface of the biomass and the anionic dye molecules. The biosorption mechanism was confirmed by FT-IR spectroscopy and microscopy analysis      

Chemical and technological characterization of medieval glass bracelets from South-East Bulgaria

The present paper deals with chemical and physicochemical characterization of seven glass fragments of medieval glass bracelets from South-East Bulgaria. Samples were investigated by Fourier-transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and differential thermal analysis (DTA). Gravimetric chemical analysis was used for silica assessment. Flame photometry was applied to determine sodium and potassium content while aluminium, calcium and magnesium were determined by flame atomic absorption spectrometry after dissolution using a mixture of acids. All investigated artefacts are soda-lime-silica glasses and when produced two different recipe norms were used. Important technological parameters of glass manufacturing were determined and discussed. This investigation throws light on the technological development and production of glass during medieval times.      

Effect of size of tetraalkylammonium counterions on the temperature dependent micellization of AOT in aqueous medium

Different tetraalkylammonium, viz. N⁺(CH₃)₄, N⁺(C₂H₅)₄, N⁺(C₃H₇)₄, N⁺(C₄H₉)₄ along with simple ammonium salts of bis (2-ethylhexyl) sulfosuccinic acid have been prepared by ion-exchange technique. The critical micelle concentration of surfactants with varied counterions have been determined by measuring surface tension and conductivity within the temperature range 283–313 K. Counterion ionization constant, α, and thermodynamic parameters for micellization process viz., $\Delta G_m^{\text{0}} $ , $\Delta H_m^{\text{0}} $ , and $\Delta S_m^{\text{0}} $ and also the surface parameters, Γ_max and A_min, in aqueous solution have been determined. Large negative $\Delta G_m^{\text{0}} $ of micellization for all the above counterions supports the spontaneity of micellization. The value of standard free energy, $\Delta G_m^{\text{0}} $ , for different counterions followed the order $${\text{N}}^{\text{ + }} \left( {{\text{CH}}_{\text{3}} } \right)_4 >{\text{NH}}_{\text{4}}^{\text{ + }} >{\text{Na}}^{\text{ + }} >{\text{N}}^{\text{ + }} \left( {{\text{C}}_{\text{2}} {\text{H}}_5 } \right)_{\text{4}} {\text{ $>$ N}}^{\text{ + }} \left( {{\text{C}}_{\text{3}} {\text{H}}_{\text{7}} } \right)_4 >{\text{N}}^{\text{ + }} \left( {{\text{C}}_{\text{4}} {\text{H}}_{\text{9}} } \right)_4 $$ , at a given temperature. This result can be well explained in terms of bulkiness and nature of hydration of the counterion together with hydrophobic and electrostatic interactions.     

Polymer conjugates with potential biological activity based on new derivatives of 2-mercaptobenzoxazole-synthesis and characterization

New potentially biologically active compounds derived from 2-mercapto-benzoxazole were synthesized and coupled on polymeric support of poly (maleic anhydride-alt-vinyl acetate) for the preparation of polymer-drug conjugates with controlled drug release. All compounds were characterized by elemental and spectroscopy (FT-IR, ¹H-NMR) analysis. The toxicological tests recommend the products for further laboratory screening.      

Investigation of electrical properties of PANI/chalcogenide junctions

Pure Polyaniline (EB) and Polyaniline doped with different protonic acids (ESs) were chemically synthesized using ammonium peroxydisulphate (APS) as an oxidant. Junctions have been prepared by evaporating chalcogenide materials (ZnSe, CdSe) on conducting polyaniline (EB & ESs) pellets using a vacuum evaporation technique. I–V characteristics of junctions have been studied at room temperature using the Keithley electrometer 6517A. I–V measurements show the rectification effect. A junction of ES[PO₄ ^3?] may be preferred over the other junctions due to its low ideality factor and maximum rectification ratio.