• Analytical Science and Technology
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• v.16 no.4
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• pp.333-338
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• 2003

Inclusion selectivity of a three-dimensional piperazine-ligated cyanocadmate host complex, $[Cd_x(CN)_{2x}\{HN(CH_2CH_2)_2NH\}_y]{\cdot}zG$, has been investigated for benzene (B), toluene (T), ethylbenzene (E), o- (O), m- (M), and p-xylene (P) isomers as the aromatic guest molecules. From the binary, ternary and quarternary guest mixtures of E and xylene isomer (X), the order of inclusion selectivity in the host complex is O>E>P>M. From the binary to quinary BTX mixtures, the order of preference in the complex is seen to be B>T>O${\gg}$P>M.

• Fire Science and Engineering
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• v.23 no.5
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• pp.161-166
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• 2009

The lower flash points for the tert-pentanol + propionic acid and p-xylene + propionic acid systems were measured by Tag open-cup apparatus. The experimental data were compared with the values calculated by the Raoult's law, the van Laar equation and the NRTL equation. The calculated values based on the van Laar and NRTL equations were found to be better than those based on the Raoult's law. It was concluded that the van Laar and NRTL equations were more effective than the Raoult' law at describing the activity coefficients for non-ideal solution such as the tert-pentanol + propionic acid and p-xylene + propionic acid systems. The predictive curve of the flash point prediction model based on the NRTL equation described the experimentally-derived data more effectively than was the case when the prediction model was based upon the van Laar equation.

• Applied Chemistry for Engineering
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• v.21 no.4
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• pp.417-423
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• 2010

In this study, an effective method to prepare granular binderless ZSM-5 which is as efficient p-xylene separatory adsorbent was explored. Colloidal silica sol 30 wt% solution as an inorganic binder and microcrystalline cellulose as an organic additive were added to ZSM-5 powder ($SiO_2/Al_2O_3$ = 50). Adsorbent with enough strength (0.721 kgf), high crystallinity (94.6%) and high BET specific surface area ($379.2m^2$/g) was obtained by calcination, binderless treatment, ${NH_4}^+$ ion exchange, and activation after spherical granulation process. A batch type adsorption experiment was proceeded with solutions comprising 3 xylene isomers by 1 : 1 : 1 weight ratio to evaluate adsorption characteristics of prepared absorbent. As a result, the obtained binderless ZSM-5 granule showed a higher selective adsorption performance for para-xylene than that of commercial adsorbent.

• Asian Journal of Atmospheric Environment
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• v.2 no.1
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• pp.14-25
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• 2008

Benzene, toluene, ethyl benzene and m-, p-, and o-xylene, the most influential aromatic volatile organic compounds (VOCs), were measured in Bangkok, Thailand, one of the most rapidly developing urban areas in Southern East Asia. The purpose of this study is to characterize the ambient air quality with respect to above mentioned aromatic compounds. The data were monitored in ten sites which cover roadside area, residential area and background area. Canister technique was used to obtain air sample at 24 hour interval per a month during April-August in 2007. GC/MS with three stage preconcentrator was used to analyze these samples. The average concentrations of benzene, toluene, ethyl benzene m-, p-xylene and o-xylene are 5.8, 36.1, 4.1, 11.0 and $3.7{\mu}g/m^3$, respectively. They were observed to be distributed in a log-normal form. Moreover, o-xylene and m, p-xylene exhibited a very good correlation (r=0.976). The slope of the regression equation between them was 3.07 which consisted with a previous reported value. The average ratio of toluene to benzene was 6.4 in April, May June and August. This value was comparable to the ones measured in other Asian cities. Two types of statistical analyses, cluster and factor analyses, were applied to the data in this study. Well characterization was made to understand the air quality of Bangkok area.

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2553-2559
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• 2012

The adsorption properties of benzene, toluene, p-xylene in MCM-41 with heterogeneous and cylindrical pore were studied using grand canonical ensemble Monte Carlo simulation. The simulated isotherms were compared with experimental ones, and the different adsorption behaviors in MCM-41 with pore diameters of 2.2 and 3.2 nm were investigated. The simulated adsorption amounts above the capillary-condensation pressure agreed with the experimental ones. The simulation results showed that most molecular planes were nearly parallel to the pore axis. This orientation was not affected by the molecular position in the pore. The molecular planes were nearly parallel to the pore surface for the adsorbate molecules close to the pore wall, and the molecules in the MCM-41 with the pore diameter of 3.2 nm were ordered along the pore axis.

• Bulletin of the Korean Chemical Society
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• v.23 no.3
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• pp.441-446
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• 2002

We have presented the results of thermodynamic, structural and dynamic properties of liquid benzene, toluene, and p-xylene in canonical (NVT) ensemble at 293.15 K by molecular dynamics (MD) simulations. The molecular model adopted for these molecules is a combination of the rigid body treatment for the benzene ring and an atomistically detailed model for the methyl hydrogen atoms. The calculated pressures are too low in the NVT ensemble MD simulations. The various thermodynamic properties reflect that the intermolecular interactions become stronger as the number of methyl group attached into the benzene ring increases. The pronounced nearest neighbor peak in the center of mass g(r) of liquid benzene at 293.15 K, provides the interpretation that nearest neighbors tend to be perpendicular. Two self-diffusion coefficients of liquid benzene at 293.15 K calculated from MSD and VAC function are in excellent agreement with the experimental measures. The self-diffusion coefficients of liquid toluene also agree well with the experimental ones for toluene in benzene and for toluene in cyclohexane.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2000.11a
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• pp.163-166
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• 2000

The purpose of this study is to evaluate substrate interactions of BTEX for multicomponent. Although BTEX compounds have similar chemical structures, biodegradation of individual BTEX is different with the present of certain BTEX compounds. The biodegradation rate is order to Benzene=Toluene>Ethylbenzene> m, p-Xylene>o-Xylene. Xylenes is stimulated when benzene or toluene is present. Especially o-xylene Inhibit other BTEX compounds.

• Applied Chemistry for Engineering
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• v.7 no.6
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• pp.1204-1208
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• 1996

The organic impurities are formed in the p-xylene oxidation process to terephthalic acid(TPA) and they are present in the filtrate(mother liquor) solution or the TPA particles. The organic impurities present in the p-xylene oxidation are formed through side reactions or incomplete reaction. In this study, the main organic impurities, such as benzoic acid, p-toluic acid, p-tolualdehyde, 4-carboxybenzaldehyde, phthalic acid, isophthalic acid, trimellitic acid, and 4-hydroxymethyl benzoic acid were identified simultaneously by gas chromatograghy. The above impurities were reacted with bis(trimethylsilyl)trifluoroacetamide in the mixture of internal standard solution and pyridine solution by trimethylsilylation, where the internal standard solution was made by 99% bis (trimethylsilyl)trifluoroacetamide and 1% trimethylchlorosilane. The main organic impurities above mentioned can be analyzed quantitatively within 50 min.

• Journal of the Korean Chemical Society
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• v.20 no.5
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• pp.351-357
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• 1976

Adsorption isotherms of benzene and p-xylene on both of Spheron 6 (a graphitized carbon black) and Alucer (Alumina) are obtained at various temperatures using a sensitive quartz beam microbalance. From these isotherms BET plots are made to obtain the molecular areas of these adsorbates. On the Spheron 6, the molecular area of p-xylene remains constant until the temperature is increased up to $19^{circ}C$, increases abruptly at $19^{circ}C$ through $19.2^{circ}C$, and then again remains constant thereafter. On the other hand, adsorbed benzene molecules give a quite temperature-independent molecular area. The results are interpreted as the adsorbed p-xylene molecules and benzene molecules are localized on the adsorbents with compact packing, while it gains a hindered-rotational degree of freedom at the expense of vibrational one at the higher temperatures. This peculiar behavior of adsorption is considered as due to the interactions between benzene rings of adsorbents and graphite surface. Molecular areas of these adsorbates on Alucer M. A. increase gradually with temperature, indicating that the adsorbed molecules are unlocalized.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.2
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• pp.147-152
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• 2009

In this study, the applicability of alginate-immobilized Pseudomonas putida mt-2 KG1206 on the environments, contaminated with toluene analogs was conducted. Genetically engineered strain KG1206 produces light by direct (m-toluate, benzoate) and indirect (toluene, xylenes) inducers. The protocol for the alginate-immobilization was determined in terms of the cell to alginate ratio, solution, proper number of alginate beads, and other conditions. Maximum bioluminescences of five chemicals by immobilized strain were generally observed in following orders: m-toluate > p-xylene > toluene > o-xylene > m-xylene. In relationship between bioluminescence activity and inducer reduction, initial m-toluate (5 mM) in solution was removed approximately 48% of initial at 5 h exposure, showing continuous decrease of inducer chemical in solution. These results of study with alginate-immobilized beads would be useful, especially, for biomonitoring of contaminated environments with specific compounds, such as petroleum hydrocarbon compounds including toluene analogs.