Search results for "Xylene"

Adsorption of gaseous p-xylene and m-xylene on NaY, KY, and BaY zeolites. Part 2: Modeling. Enthalpies and entropies of adsorption

1995

Abstract The adsorption isotherms of xylenes are described by Henry's law and Langmuir's model on NaY and KY and the Dubinin-Radushkevich model on BaY. The isoteric enthalpies of adsorption show on each zeolite that the adsorbate-adsorbent interactions are nearly the same with both isomers. They are stronger on BaY than on NaY and KY. The adsorbate-adsorbate interactions are stronger with m-xylene than with p-xylene and especially outstanding on KY. The entropies of adsorption show that the mobility of the adsorbate is lower with m-xylene than with p-xylene. The isosteric free enthalpies of adsorption are related to the acidity of each zeolite. BaY has a stronger acidity and a greater abili…

A fatal case of a paint thinner ingestion: Comparison between toxicological and histological findings

2010

Toluene and xylene are aromatic hydrocarbons commonly used as an industrial solvent for the manufacturing of pharmaceuticals, paints, and chemicals. The Occupational Safety and Health Administration has determined that toluene levels of 2000 parts per million (ppm) are considered dangerous to life and health. Several studies have examined the absorption of toluene and xylene following inhalation and oral ingestion in humans. Volatile organic compounds that are absorbed into the blood are distributed throughout the body; in particular, distribution of absorbed toluene and xylene in humans and rodents is characterized by preferential uptake in well-perfused and lipophil tissues such as the br…

Self-assembly of C60 fullerene molecules in the hexane–xylene solvent system

2021

The behavior of self-assembly of C60 molecules in solutions of C60/hexane/xylene were studied by the methods of refractometry, ultraviolet–visible spectroscopy and dynamic light scattering (DLS). I...

Functionalized planar Bragg grating sensor for the detection of BTX in solvent vapor

2012

We report on an optical planar Bragg grating evanescent wave refractive index sensor functionalized by a simple method against aromatic hydrocarbons such as benzene, toluene and xylene (BTX) in solvent vapor. To functionalize the sensor against BTX, substituted cyclodextrins are applied to the sensor surface using dip coating. Cyclodextrins have a hydrophobic cavity, which favors the accommodation of an organic molecule of appropriate dimensions leading to a non-covalent inclusion complex. The temporal sensor response reveals a multi-exponential rise towards an equilibrium state, whose level is found to be linearly related to the exposed analyte concentration. Taking into account the spectr…

Diversity-Oriented Synthesis of Polycyclic Scaffolds by Modification of an Anodic Product Derived from 2,4-Dimethylphenol

2010

Location of Water and Xylene Molecules Adsorbed on Prehydrated Zeolite BaX. A Low-Temperature Neutron Powder Diffraction Study

1999

The Seasonality Impact of the BTEX Pollution on the Atmosphere of Arad City, Romania

2021

Benzene, toluene, and total BTEX (benzene, toluene, ethylbenzene, and xylene) concentrations registered for one year (2016) have been determined every month for one high-density traffic area. The assessment was performed in Arad City, Romania, to evaluate these pollutants and their influence on the inhabitants’ health. The contaminants were sampled using a static sampling method and analyzed by gas chromatography coupled with mass spectrometry. Benzene was the most dominant among the BTEX compounds—the average concentrations ranged from 18.00 ± 1.32 µg m−3 in December to 2.47 ± 0.74 µg m−3 in August. The average toluene concentration over the year was 4.36 ± 2.42 µg m−3 (with a maximum of 9…

Determining exhaust fumes exposure in chainsaw operations

2016

Abstract The objective of this study was to investigate the inhalation exposure of forest operators to polycyclic aromatic hydrocarbons (PAHs) and BTEX (benzene, toluene, ethylbenzene and total xylenes) contained in the exhaust fumes released from chainsaws and to suggest possible countermeasures. The study was carried out in four silvicultural treatments (coppice clearcut, conifer thinning, conifer pruning, and sanitary cut), using three types of chainsaw fuel (normal two-stroke petrol mix and two alkylate fuels). Eighty personal air samples were collected; IOM samplers combined with Amberlite XAD-2 sorbent tubes were used for collecting PAHs and Radiello® samplers were used for BTEX. Resu…

Molecular orbital studies on the mechanism of catalytic isomerization of xylenes III. Protonation channels

1981

Abstract The isoenergetic lines of the interaction energy between a bare proton and ortho-, meta- , and para -xylene have been calculated in order to detect both the best approaching channel and the preferred protonation positions. The channels found direct the protonation to the following ring positions: 4 and 5 for o -xylene, 4 and 6 for m -xylene, and 2 equivalents for p -xylene. The overall interaction energy determines the protonation positions on each isomer and the most important contributions to it are the electrostatic term in o -xylene, the polarization term in p -xylene, and both terms equally in m -xylene. These results are in agreement with the experimental findings and appear …

A study of the behaviour of 2,4-substituted thiosemicarbazides toward orthoesters: Formation of mesoionic compounds

1997

The reactions beetwen 2,4-disubstituted thiosemicarbazides and orthoesters in refluxing xylene led to the formation of the 1,2,4-triazoline-5-thione ring and to the 1,2,4-triazolium-5-thiolate ring. The formation of the mesoionic componds is due to rearrangement of the easily available 2,4-disubstituted thiosemicarbazides to 1,4-disubstituted thiosemicarbazides under the reaction conditions adopted. This method can be usefully used for the synthesis of mesoionic compounds, especially in the case of the 2-methyl-4-phenylthiosemicarbazide.