Search results for "fourier"
showing 10 items of 1345 documents
Fourier Transform Infrared Study of the Performance of Nanostructured TiO2 Particles for the Photocatalytic Oxidation of Gaseous Toluene
2001
Thermal and hydrothermal treatments have been applied to an amorphous TiO2 precursor for obtaining nanosized TiO2 particles (P11t and P11h, respectively) of different photocatalytic properties. The activity of these catalysts has been tested by performing the toluene oxidation in gas phase in a continuous photoreactor. A Fourier transform infrared (FTIR) investigation of the catalysts under conditions prevailing during the test photoreaction has also been carried out. The photoreactivity results showed that CO2 was the main oxidation product and benzaldehyde a stable intermediate. Anatase P11t photoactivity was similar to that observed for commercial photocatalysts, while anatase P11h prese…
Preparation, Characterization, and Photoactivity of Polycrystalline Nanostructured TiO2 Catalysts.
2004
Various preparations of nanostructured TiO2 starting from Ti(iso-OC3H7)4 or TiCl4 are reported. The samples were characterized by X-ray diffractometry, specific surface area and porosity determinations, scanning and transmission electron microscopy, and diffuse reflectance spectroscopy. 4-Nitrophenol photodegradation in aqueous medium was employed as a probe reaction to test the photoactivity of the catalysts. The photoactivity of some samples derived from Ti(iso-OC3H7)4 was found comparable with that of commercial powders. Calcination after the hydrolysis process was necessary to achieve crystallization of the particles before using them as photocatalysts for the reaction studied. The samp…
Preparation and characterisation of TiO2 (anatase) supported on TiO2 (rutile) catalysts employed for 4-nitrophenol photodegradation in aqueous medium…
1999
Abstract In this paper the preparation of two sets of polycrystalline photocatalysts prepared by supporting TiO2 (anatase) on TiO2 (rutile) or Al2O3 is reported. The powders were prepared by a wet impregnation method using titanium(IV) isopropylate. The impregnation was followed by thermal treatment and this procedure was repeated several times in order to obtain samples with progressively increasing amounts of TiO2 (anatase). The photocatalytic activity of all of the specimens was tested by carrying out the 4-nitrophenol photodegradation, used as a “probe” reaction, in aqueous medium and in different kinds of batch photoreactors. The solids were characterised by X-ray diffraction (XRD), sp…
Preparation characterization and photocatalytic activity of polycrystalline ZnO/TiO2 systems. 2. Surface, bulk characterization, and 4-nitrophenol ph…
2001
Electron spin resonance spectroscopy (ESR), Fourier transform infrared spectroscopy (FTIR), and monitoring of pyridine (py) and boric acid trimethyl ester (BATE) adsorption for determining surface acidity and basicity, respectively, were used to carry out further characterization of mixed ZnO/TiO2 polycrystalline solids prepared by different methods. Moreover, the powders were tested in a batch photoreactor for a probe reaction, i.e., 4-nitrophenol photodegradation in aqueous medium. ESR results indicated the presence of signals attributable to Zn+ species in ZnO/TiO2 (anatase) solids, while in ZnO/TiO2 (rutile) samples the presence of zinc induced only the formation of signals probably due…
Photocatalytic oxidation of gaseous toluene on anatase TiO2 catalyst: Mechanistic aspects and FT-IR investigation
1999
Abstract Photo-oxidation of toluene has been carried out in gas–solid regime by using polycrystalline anatase TiO2 as the catalyst. The reacting gaseous mixture was toluene, air and water in various molar ratios. A pyrex fixed-bed continuous photoreactor irradiated by a medium pressure Hg lamp was used for performing the photoreactivity experiments. The main oxidation product was benzaldehyde but benzene, benzyl alcohol and traces of benzoic acid, phenol and unidentified compounds were also detected. The molar conversion to benzaldehyde with respect to the initial amount of toluene was ca. 20% in the best experimental conditions. Benzene was produced only as a transient product during the f…
Hyperbranched Polyglycerol-Based Lipids via Oxyanionic Polymerization: Toward Multifunctional Stealth Liposomes
2010
We describe the synthesis of linear-hyperbranched lipids for liposome preparation based on linear poly(ethylene glycol) (PEG) and hyperbranched polyglycerol (PG). Molecular weights were adjusted to values around 3000 g/mol with varying degrees of polymerization of the linear and the branched segments in analogy to PEG-based stealth lipids; polydispersities were generally low and below 1.3. The hydrophobic anchors were introduced into the lipid structures as initiators for the anionic polymerization of ethylene oxide and are either based on cholesterol or on different aliphatic glyceryl ethers. Complete incorporation of the apolar initiators was evidenced by MALDI-ToF analysis at all stages …
Synthesis, characterization and the first crystal structure of the Zn(II) complex of 4,6-O-ethylidine-N-(2-hydroxybenzylidene)-β-D-glucopyranosylamine
2001
4,6-O-Ethylidine-N-(2-hydroxybenzylidene)-β-D-glucopyranosylamine (H3L1) and N-(5-bromo-2-hydroxybenzylidene-4,6-O-ethylidine-β-D-glucopyranosylamine (H3L2) molecules possessing a–C-1–N=C(H)–moiety for metal-ion binding were synthesized by condensing the 4,6–O–ethylidene–β–D–glucopyranosylamine with salicylaldehyde or 5–bromosalicylaldehyde. Complexes of these ligands with Zn(II) were isolated and characterized using elemental analysis, FTIR, UV–Vis absorption, NMR spectroscopic and FAB mass spectrometric techniques. The structure of the Zn(II) complex derived from H3L1 was established for the first time by a single-crystal X-ray diffraction study. The anomeric nature of the saccharide moie…
Synthesis and antimicrobial activity of new bromine-rich pyrrole derivatives related to monodeoxypyoluteorin
2006
The synthesis and antimicrobial activity of new pyrrole derivatives structurally related to monodeoxypyoluteorin are described. The insertion of a keto or methylene spacer between the phenol group and the pyrroloyl moiety of brominated 2-(2'-hydroxybenzoyl)pyrroles leads to a decrease of the antibacterial activity.
Impact of molecular weight on the formation of electrosprayed chitosan microcapsules as delivery vehicles for bioactive compounds.
2016
The molecular weight of chitosan is one of its most determinant characteristics, which affects its processability and its performance as a biomaterial. However, information about the effect of this parameter on the formation of electrosprayed chitosan microcapsules is scarce. In this work, the impact of chitosan molecular weight on its electrosprayability was studied and correlated with its effect on the viscosity, surface tension and electrical conductivity of solutions. A Discriminant Function Analysis revealed that the morphology of the electrosprayed chitosan materials could be correctly predicted using these three parameters for almost 85% of the samples. The suitability of using elect…
Revisiting the thiosemicarbazonecopper(II) reaction with glutathione. Activity against colorectal carcinoma cell lines.
2018
Thiosemicarbazones (TSCs), and their copper derivatives, have been extensively studied mainly due to the potential applications as antitumor compounds. A part of the biological activity of the TSC-CuII complexes rests on their reactivity against cell reductants, as glutathione (GSH). The present paper describes the structure of the [Cu(PTSC)(ONO2)]n compound (1) (HPTSC =pyridine-2-carbaldehyde thiosemicarbazone) and its spectroscopic and magnetic properties. ESI studies performed on the reaction of GSH with 1 and the analogous [{Cu (PTSC*)(ONO2)}2] derivative (2, HPTSC* =pyridine-2-carbaldehyde 4N-methylthiosemicarbazone) show the absence of peaks related with TSC-Cu-GSH species. However GS…