The photocatalytic degradation of 17α-ethynylestradiol by pure and carbon nanotubes modified TiO<Subscript>2</Subscript> under UVC illumination

Commercial product Degussa TiO2 P25, sol-gel produced TiO₂ and TiO₂ modified by carbon nanotubes addition (5% of the TiO₂ mass) are tested as photocatalysts for the degradation of endocrine disrupting compound 17α-ethynylestradiol (1 μM aqueous solution). The molecular and crystal structure, phase composition, crystallite size, specific surface area, pore average diameter, their area and volume distribution, morphology, IR and UV/Vis spectra of the catalysts are characterized. HPLC is used for estrogen analysis. The sorption ability and photocatalytic activity (measured by degradation rate constant and percentage of the pollutant conversion) of the catalysts under UV (17 W, emission maximum at 254 nm) irradiation is determined. Full destruction of the pollutant is reached after 30 min irradiation in presence of Degussa P25. The performance of some of the catalysts is compared with literature data for their activity under 365 nm-illumination.      

Preparation and shape control of β-Ni(OH)<Subscript>2</Subscript> nano-particle

A simple and convenient method for the preparation of needle-shape nanoparticles of β-Ni(OH)₂ has been developed. Results show that a needle-shaped β-Ni(OH)₂ can be easily obtained in the presence of ethylenediamine and sodium dodecylbenzene sulfonate within a size from 100 to 200 nm. The shape and structure of the product were characterized by XRD, TEM and FT-IR. It is noteworthy that the formation of needle-shape β-Ni(OH)₂ benefits from the addition of sodium dodecylbenzene sulfonate. The optimum preparation conditions and the possible mechanism are also discussed.      

Addition of TiO2 nanowires in different polymorphs for dye-sensitized solar cells

TiO₂ (B) and TiO₂ anatase nanowires were prepared at 150 °C for 120 h by a hydrothermal method followed by calcination in air at 400 °C for 2 h and at 700 °C for 2 h for TiO₂ (B) and TiO₂ anatase, respectively. Although dye-sensitized solar cells (DSC) with fully nanowire electrodes showed a rather low light-to-electricity conversion efficiency of 1.33 % for TiO₂ (B) and 2.42% for TiO₂ anatase, 10 wt % nanowire-dispersed electrodes in a P-25 TiO₂-nanoparticle matrix demonstrated improved efficiency of 6.17 % for TiO₂ (B) and 6.53% for TiO₂ anatase, these exceeding that of pure P-25 electrodes in this work (η=5.59%). The dominant mechanisms of the improvement at 10 wt% for the two different polymorphs are thought to be different, i.e., a light-scattering and film-thickness increment for the TiO₂ (B) system, whereas there is an improved conduction path through the matrix for the TiO₂ anatase system.      

Ionic liquid promoted synthesis of bis(indolyl) methanes

1-benzyl-3-methyl imidazolium hydrogen sulphate [bnmim][HSO₄] was found to be an effective catalyst for the condensation reaction of indoles and derivatives with benzaldehydes in microwave irradiation with lower reaction time and higher yields to give bis(indolyl) methanes.      

Subsolidus area of the system CdO - V2O5 - Fe2O3

Phase diagrams in the subsolidus area of the systems FeVO₄ - CdO and FeVO₄ - Cd₂V₂O₇ have been deduced using the results of XRD and DTA analyses. On the basis of these diagrams and some additional verifying research, a projection of the subsolidus area of the CdO - V₂O₅ - Fe₂O₃ system onto the plane that comprises the components’ concentration triangle has been presented. The H-type phase is the only phase formed in this system. It co-exists at equilibrium with other phases in six subsidiary subsystems.      

Photocatalytic properties of Ru-doped titania prepared by homogeneous hydrolysis

Nanocrystalline titania particles doped with ruthenium oxide have been prepared by the homogenous hydrolysis of TiOSO₄ in aqueous solutions in the presence of urea. The synthesized particles were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HRTEM), Selected Area Electron Diffraction (SAED) and Nitrogen adsorption-desorption was used for surface area (BET) and porosity determination (BJH). The photocatalytic activity of the Ru-doped titania samples were determined by photocatalytic decomposition of Orange II dye in an aqueous slurry during irradiation at 365 nm and 400 nm wavelengths.      

Influence of ThO<Subscript>2</Subscript> on the photocatalytic activity of TiO<Subscript>2</Subscript>

Microcomposites consisting of TiO₂ (or Ce-doped TiO₂) and ThO₂ (0.5–2% of the TiO₂ mass) are produced by sol-gel synthesis of TiO₂ in presence of ThO₂. X-ray diffraction study reveals the effects of ThO₂ (compared to the ThO₂-free TiO₂, obtained by the same method) on the anatase interplanar distances, crystallites size and phase composition. The photocatalytic tests in presence of the composites under UV irradiation reveal an increase of the Malachite Green degradation rate constant. The effect depends on the Th relative content, temperature of annealing of the catalyst and addition of other doping agent. The highest photocatalytic activity is observed for TiO₂ obtained at 550°C and containing 1% ThO₂. The composite exhibits activity in dark, also. The presence of Ce⁴⁺ ions is not an obligatory requirement for the realization of the ThO₂ effect. The reported results suggest that the radioactivity of the Th and/or its decay products is one of the main factors responsible for the increased photocatalytic activity of TiO₂.      

2-pyrrolidone - capped Mn<Subscript>3</Subscript>O<Subscript>4</Subscript> nanocrystals

Water-soluble Mn₃O₄ nanocrystals have been prepared through thermal decomposition in a high temperature boiling solvent, 2-pyrrolidone. The final product was characterized with XRD, SEM, TEM, FTIR and Zeta Potential measurements. Average crystallite size was calculated as ∼15 nm using XRD peak broadening. TEM analysis revealed spherical nanoparticles with an average diameter of 14±0.4 nm. FTIR analysis indicated that 2-pyrrolidone coordinates with the Mn₃O₄ nanocrystals only via O from the carbonyl group, thus confining their growth and protecting their surfaces from interaction with neighboring particles.      

Calorimetric study of melts in the System KF - K<Subscript>2</Subscript>NbF<Subscript>7</Subscript>

The relative enthalpies of melts in the system KF - K₂NbF₇ were measured by drop-calorimetry at the temperatures 1058, 1140 and 1208 K as a function of composition. Heat capacities of melted mixtures and enthalpies of mixing were determined using the experimental data. The molar heat capacity of melts diverges slightly from additivity. The molar enthalpy of mixing of melts shows small negative deviation from ideality which decreases with decreasing temperature. The thermal effect at mixing was assigned predominantly to association reactions producing more complex fluoroniobate anions.      

Low temperature synthesis and characterization of Mn3O4 nanoparticles

Heating hydrous manganese (II) hydroxide gel at 85 °C for 12 hours produces Mn₃O₄ nanoparticles. They were characterized by X-ray powder diffraction (XRD) and infrared spectroscopy (FTIR). The particle size estimated from the SEM and X-ray peak broadening is approximately 32 nm, showing them to be nanocrystalline. EPR measurements confirm a typical Mn²⁺signal with a highly resolved hyperfine structure.      

The binary system PbO - BiVO4

Phase equilibria established in the PbO - BiVO₄ system over the whole component concentration range up to 1000°C have been investigated. A phase diagram has been constructed using DTA and XRD.      

Large cation model of dissociative reduction of electrochromic WO3−x films

Studies of dissociative reduction processes of electrochromic WO_3−x films were conducted to: (i) evaluate their utility for electroetching and (ii) determine their fundamental mechanistic features to reduce or eliminate their occurrence in normal optical switching and modulation operation of WO_3−x films. We have found that while the small intercalating cations stabilize WO_3−x structure, the large nonintercalating surfactant cations (Et₄N+, CtMe₃N+) contribute to the dissociative reduction. While these cations do not affect WO_3−x structure of anodically protected films (E > 0.2 V), they cause surface lattice polarization on electron injection to the conduction band of WO_3−x at lower electrode potentials, in the absence of intercalating cations. We have found that this process is limited to the surface and no structural damage occurs to the underlying film. The mechanistic aspects of the process have been discussed on the basis of experimental voltammetric and electrochemical quartz crystal nanogravimetric (EQCN) measurements and ab initio quantum mechanical calculations.      

Synthesis by self-assembly and structural characterization of a new co-crystal system {[Cu(NO3)2(H2O)2]L1(NO3)2} (L1 = 1,1′-dibenzyl-3,3′-butyl-diimidazolium-2,2′-diylidene) from copper nitrate and a carbene precursor

Herein, the first example of a co-crystal system formed by an imidazolium nitrate, a carbene precursor, and copper (II) nitrate, {[Cu(NO₃)₂(H₂O)₂]L1(NO₃)₂} (1) (L1 = 1,1′-dibenzyl-3,3′-butyl-diimidazolium-2,2′-diylidene) is reported. These two building blocks are connected in the solid state through hydrogen bonds to generate a three-dimensional supramolecular network.      

Transport properties of PVA/PEI/PEG composite membranes: sorption and permeation characterizations

Poly(vinylalcohol)/poly(ethyleneglycol)/poly(ethyleneimine) blend membranes were prepared by solution casting followed by solvent evaporation. The chemical structure of the prepared membranes was analyzed by FTIR and DSC. The sorption behavior as well as the permeabilities of the membranes for pure CO₂ and N₂ were investigated. The results show that the PVA/PEI/PEG membranes possess a higher permeability of CO₂ and a lower permeability of N₂. The membrane displays a CO₂ permeability of 27 Barrer, and a N₂ permeability of 3 Barrer at 25°C and 1 bar. CO₂ sorption behavior of the composite membrane, which can be classified as a dual-mode sorption model, and N₂ sorption behavior of the copolymeric membrane is in agreement with the Fickian diffusion model.      

Structure and photocatalytic activity of Ti1?X MX O2 (M = Zr, Co and Mo) synthesized by pulverized solid state technique

A set of transition metal doped nanosized TiO₂ particles with anatase structure were synthesized by the pulverization method and their ability to photocatalytically degrade the dye Alizarin Red S was investigated. Characterization of the Zr-, Co- and Mo-doped photocatalysts was conducted with the aid of XRD, SEM, EDX, TEM, BET and spectral analysis. X-ray diffraction patterns did not reflect the appearance of any peaks due to dopants, however dopants were observed in SEM-EDX analysis. Particle sizes were in the range of 25 nm as per TEM and XRD analysis. Upon doping, a prominent decrease in surface area was observed. The percentage composition of each of the dopants was confirmed by EDX analysis. Doped samples depicted many mid-bands in the Kubelka Munk plots due to d-d transition of dopants. Experiments were conducted to compare the photocatalytic activity under identical UV and solar light exposure. Zr-doped TiO₂ at the molecular scale exhibited better photocatalytic activity in degradation of Alizarin, with a lower band-gap energy that can respond to visible light. However, Co- and Mo-doped TiO₂ appeared to suppress the photoactivity. A rise in the number of mid-bands causing effective separation or recombination of charge carriers strongly influences the rate of the degradation process.      

A green chemical route for the synthesis of Mn3O4 nanoparticles

A novel environmental friendly, room temperature route using an ionic liquid 1-n-butyl-3-methylimidazolium hydroxide ([BMIM]OH) for the synthesis of Mn₃O₄ nanoparticles is presented. The product was characterized using Fourier transform infrared spectroscopy, X-ray powder diffraction, and transmission electron microscopy. Phase purity was confirmed by XRD, and X-ray line profile fitting determined a crystallite size of 42 ± 11 nm. TEM analysis revealed various morphologies. EPR measurements have indicated the existence of long-range interactions, due to the wide range of particle sizes and morphologies observed.      

Determination of active components in Chinese medicinal preparations by capillary electrophoresis

The determination of paeoniforin, paeonol, and censenoside Rg₁ in traditional Chinese medicinal preparations, Tze Po San Pien pills and Liuwen Dihuang pills has been investigated by micellar electrokinetic capillary electrophoresis with borate buffer (20 mM), sodium dodecylsulfate (30 mM) and acetonitrile (20%) as background electrolytes (pH 9.30), 20 kV applied voltage and 203 nm UV detection. The effects of SDS concentration, borate, buffer pH, and organic modifier on electrophoretic behavior and separation are discussed. Regression equations revealed linear relationships between the peak-area of each component and the content with the correlation coefficients from 0.9982 to 0.9999. In addition, the levels of the active compounds in two kinds of traditional Chinese medicinal preparations were easily determined with the recoveries from 93.1% to 108.2%.      

Stability-indicating derivative spectrophotometry method for the determination of biapenem in the presence of its degradation products

A first-derivative UV spectrophotometric method, with or without the subtraction technique, was developed for the determination of biapenem in pharmaceutical dosage form in the presence of its degradation products. The method was based on the measurement of first-derivative amplitudes at zero crossing point (λ = 312 nm) and the peak-to-zero technique and validated with regard to linearity, limits of detection and quantitation, selectivity and precision. The observed rate constants for the degradation of biapenem were comparable to those obtained in the stability-indicating HPLC method.      

Preparation of nanostructured porous SiO2-Al2O3 oxycarbonitride materials obtained by a new chemical precursor method

Nanostructured hybrid materials containing Al₂O₃ were synthesized via a sol-gel method through hydrolysis and co-condensation reactions using trimethylsilyl isocyanate (TMSI) as a new silica source in the presence of tetramethoxysilane (TMOS) and three different quantities (10, 20 and 30 wt.%) of aluminum sec-butoxide (Al(OBu^sec)₃ as a modifying agent. The xerogel nanostructured materials are pyrolyzed in nitrogen atmosphere in the temperature range from 400°C to 1100°C. The transformation of the xerogel hybrid networks into Al-Si oxycarbonitride materials has been investigated by XRD, FTIR, SEM, AFM, and ²⁹Si MAS-NMR. To the best of our knowledge, the work reported here is the first synthesis of porous di-urethanesils modified with aluminum and one of the few examples of alumosilica oxycarbonitride materials      

Synthesis,characterization, catalytic and antimicrobial studies of ruthenium(III) complexes

Ru(III) complexes of the type [RuXB(L)2] have been prepared by the reaction of 3,4-dihydropyrimidin-2(1H)-ones/thiones (HL¹–HL⁴) with the precursors of the type [RuX₃B₃] where X=Cl or Br; B=PPh₃ or AsPh₃ and L is the deprotonated ligand. The synthesized complexes were characterized by physico-chemical methods, electrochemical and magnetic moment data. The catalytic efficiency of the complexes were examined in the oxidation of alcohols and antimicrobial studies were also carried out.