Search results for "Atmospheric Pressure"
showing 10 items of 105 documents
Characterization of methyl orange and its photocatalytic degradation products by HPLC/UV–VIS diode array and atmospheric pressure ionization quadrupo…
2002
Abstract HPLC/UV–VIS diode array and HPLC/MS techniques were successfully applied to the analysis of sulfonated molecules present in samples coming from the photocatalytic degradation of the azo dye indicator, methyl orange. The substrate was chosen as a simple model for the study of reactions involving the more complex commercial products used for the dyeing of textile fibers. Unexpected MS fragmentation path was observed, due to the very stable methyl orange molecular structure. The chromatographic information were combined with the obtained MS, MS/MS data and the UV–VIS diode array spectra and allowed to rationalize the molecular structures attributable to the various degradation product…
Surface tension and density of binary mixtures of monoalcohols, water and acetonitrile: equation of correlation of the surface tension
2009
Measurements of the surface tension (σ) and density (ρ) of binary mixtures of monoalcohols, water and acetonitrile at 298.15 K and at atmospheric pressure, as a function of mole fraction (x) have been made. The experimental values of the deviation of surface tension and the excess of molar volume (Δσ, V E) have been correlated by the Redlich–Kister equation. An empirical correlation equation is presented for the study of the surface tension of these mixtures, and comparisons are made of the experimental values of surface tension versus those obtained with the correlation equation and with other models of correlation. Finally, with the purpose of corroborating the validity of the correlation…
Density, Viscosity, and Sound Speed of Bis(trifluoromethylsulfonyl)imide-Based Ionic Liquids + 1-Propanol Mixtures
2015
The density, viscosity, and speed of sound of three mixtures formed by 1-propanol and an ionic liquid were measured in a temperature range of 278.15–338.15 K. All measurements were made at atmospheric pressure and covered the entire range of miscible compositions. The three ionic liquids have the same anion but differ in the cation: 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [emim][NTf2], 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [bmim][NTf2], and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [hmim][NTf2]. The experimental data allowed calculate the molar volume and isentropic compressibility of the mixture and their respective exces…
Comparison between catalytic and catalytic photo-assisted propene hydration by using supported heteropolyacid
2012
Abstract Hybrid materials have been prepared by impregnation of the heteropolyacid H 3 PW 12 O 40 on commercial TiO 2 . The polyoxometalates (POM) amount deposited was 15, 30, 50 and 70% with respect to the weight of the TiO 2 support. Moreover two samples containing a POM amount of 15, and 50% with respect to the weight of SiO 2 were also prepared for the sake of comparison. All prepared samples were efficient catalysts for the hydration of propene to 2-propanol in gas–solid regime at atmospheric pressure and at temperatures ranging between 50 and 85 °C. The study carried out on the hybrid TiO 2 based materials evidenced that, as far as the catalytic activity is concerned, exists an optimu…
Viscosity and density of binary mixtures of alcohols and polyols with three carbon atoms and water: equation for the correlation of viscosities of bi…
2009
Measurements have been made of the viscosity and density of binary mixtures of alcohols and polyols with three carbon atoms and water at 298.15 K and at atmospheric pressure, as a function of the mole fraction. Fits have been made of the experimental values corresponding to the excesses of molar volume (V E), the deviations of viscosity (Δη), and the excesses of Gibbs free energy of activation (G* E), by means of the Redlich–Kister equation. A new correlation equation is presented for studying the viscosity of such mixtures, and comparisons are made of the experimental values of viscosity versus the values obtained by means of the mentioned equation and the models of Heric and McAllister. L…
Nano photoelectron ioniser chip using LaB6 for ambient pressure trace gas detection
2012
A detector including a nanoscaled ioniser chip that surmounts the limitation of conventional photo ionisation detectors is presented. Here, ionisable gaseous substances can be detected by photoelectrons accelerated to the ionisation potential of the incoming gaseous molecules. Thin lanthanum hexaboride (LaB"6) films deposited by pulsed laser technique (PLD) serve as the air stable photocathode material representing the basis of the ioniser chip of the detector. Besides the analysis of the emission behaviour of the photocathode in vacuum and at atmospheric pressure, the detection of different volatile alcohols using the detector with a low-energy UV LED instead of a PID (VUV photon source) w…
Analysis of Organic Aerosols Using a Micro-Orifice Volatilization Impactor Coupled to an Atmospheric-Pressure Chemical Ionization Mass Spectrometer
2014
We present the development and characterization of a combination of a micro-orifice volatilization impactor (MOVI) and an ion trap mass spectrometer (IT/MS) with an atmospheric-pressure chemical ionization (APCI) source. The MOVI is a multi-jet impactor with 100 nozzles, allowing the collection of aerosol particles by inertial impaction on a deposition plate. The pressure drop behind the nozzles is approximately 5%, resulting in a pressure of 96 kPa on the collection surface for ambient pressures of 101.3 kPa. The cut-point diameter (diameter of 50% collection efficiency) is at 0.13 μm for a sampling flow rate of 10 L min–1. After the collection step, aerosol particles are evaporated by he…
Ein schnelles on-line trennsystem unter anwendung von helium-jet- und zentrifugentechnik
1975
Abstract A centrifuge for continuous liquid-liquid phase separation is described. It is designed for rapid solvent extraction of short-lived radioactive isotopes (half-lives in the order of seconds). The centrifuge is characterized by simple construction and operation principle, easy handling, low cost, and a minimum hold-up time of less than five seconds (phase purity 99.0–99.9%). The on-line connection to a helium-jet transport system is described. Problems concerning the transfer of activities into a liquid phase from the helium-jet at atmospheric pressure are discussed.
Determination of bisphenol diglycidyl ether residues in canned foods by pressurized liquid extraction and liquid chromatography–tandem mass spectrome…
2005
Abstract A new confirmatory method for simultaneous determination of bisphenol diglycidyl ether residues (BADGE, BADGE·H2O, BADGE·2H2O, BADGE·H2O·HCl, BADGE·HCl, BADGE·2HCl, BFDGE and BFDGE·2HCl) from canned food has been developed. The proposed method includes extraction by pressurized liquid extraction (PLE) followed by liquid–liquid partition and purification by solid phase extraction (SPE). Several solvent systems and different operating conditions (time, temperature) have been investigated for PLE optimization. A reversed-phase high-performance liquid chromatography (RP-HPLC) coupled to atmospheric pressure chemical ionisation tandem mass spectrometry (APCI-MS–MS) method was developed …
Identification and climatology of cut-off lows near the tropopause.
2008
Cut-off low pressure systems (COLs) are defined as closed lows in the upper troposphere that have become completely detached from the main westerly current. These slow-moving systems often affect the weather conditions at the earth's surface and also work as a mechanism of mass transfer between the stratosphere and the troposphere, playing a significant role in the net flow of tropospheric ozone. In the first part of this work we provide a comprehensive summary of results obtained in previous studies of COLs. Following this, we present three long-term climatologies of COLs. The first two climatologies are based on the conceptual model of a COL, using European Centre for Medium-range Weather…