• Applied Chemistry for Engineering
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• v.9 no.6
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• pp.864-869
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• 1998

In this work, the solid-liquid equilibria (SLE) of some aromatic organic mixtures including benzene, widely used as an industrial solvent, were measured by static method using our own made experimental apparatus. The accuracy and reproducibility of apparatus were tested by comparing experimental results with literature values for 1-dodecanol+cyclohxane and benzene + p-xylene systems. The SLE for new binary systems of benzene+aniline, benzene+nitrobenzene, p-xylene+cyclohexane were measured afterwards and compared with the calculated values by modified UNIFAC(Dortmund) equation.

• Journal of Soil and Groundwater Environment
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• v.6 no.2
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• pp.49-56
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• 2001

Benzene, one of the aromatic hydrocarbons, can be degraded by physical, chemical and biological processes in aquifers. This study aimed at analyzing separately the three different forms of degradation by performing column tests. Column tests using KCl and benzene as tracers were conducted for four different cases: 1) no hydrogen peroxide and no microorganism, 2) hydrogen peroxide only; 3) microorganism only; 4) hydrogen peroxide and microorganism to investigate the sorption and degradation of benzene. The observed BTCs of KCl and benzene in all cases showed that the arrival times of the peaks of both tracers coincided well but the peak concentration of benzene was much lower than that of KCl. This reveals that a predominant process affecting the transport of benzene in a sandy soil is an irreversible sorption and/or degradation rather than retardation. Decay of benzene through sorption and degradation increased with the addition of hydrogen peroxide and/or microorganism. Dissolved oxygen decreased with the increase of benzene in all cases indicating that degradation of benzene was also influenced by dissolved oxygen. For BTCs with the addition of microorganisms (case 3 and case 4), microorganism showed much lower concentrations compared to the initial levels and an increasing tendency with time although concentrations of benzene returned to zero, indicating a possible retardation of microorganism due to reversible and irreversible sorption to the particle surfaces.

• Journal of Environmental Health Sciences
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• v.28 no.5
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• pp.65-70
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• 2002

Recently, surfactants were frequently used in order to desorb the hydrophobic organic compounds (HOCs) from soil and to enhance the bioavailability. Among them, -cyclodextrin ($\beta$-CD) is one of those. This study was performed to investigate the binding characteristics between benzene and $\beta$-CD and to examine the bioavailability of benzene. First, we investigated binding characteristics between benzene and $\beta$-CD in water and water/soil system. Then, we examined the effect of $\beta$-CD on the biodegradation of benzene in water and water/soil system. Experimental results on the binding characteristics showed that $\beta$-CD resulted in an efficient complex formation with benzene. As -CD concentration increased, the benzene concentration complexed with $\beta$-CD rapidly increased to 30-40% initial benzene added, and reached the equilibrium. We also investigated the effect of $\beta$-CD on the desorption of benzene from soil in the water/soil system. As $\beta$-CD concentration increased, benzene concentration desorbed into water increased up to 90%. How-ever, in its application to biodegradation of benzene in water and water/soil system, the biodegradation rate of benzene did not improved in the presence of $\beta$-CD compared with in the absense of $\beta$-CD. This result indicated that $\beta$-CD was more preferentially used as a carbon source than benzene. Therefore, for remediation of benzene contaminated soils, $\beta$-CD can be used as a surfactant to desert benzene from soil, and then ex-situ chemical treatment can be applied for the remediation.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2000.05a
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• pp.101-107
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• 2000

Column tests using KCl and Benzene as tracers were conducted for four different cases: 1) no hydrogen peroxide and no microorganism; 2) hydrogen peroxide only; 3) microorganism only; 4) hydrogen and microorganism to investigate the sorption and degradation characteristics of Benzene. The observed BTCs of KCl and Benzene in all cases showed that the arrival times of the peaks of both tracers coincided well but the peak concentration of Benzene was much lower than that of KCl. This result reveals that a predominant process affecting the transport of Benzene in a sandy soil is an irreversible sorption and/or degradation rather than retardation. Decay of Benzene through sorption and degradation increased with the addition of hydrogen peroxide and/or microorganism. Dissolved oxygen decreased with the increase of Benzene in all cases indicating that Benzene was degraded by dissolved oxygen. For BTCs with the addition of microorganisms (case 3 and case 4), microorganism showed much lower concentrations compared to the initial levels and an increasing tendency with time although concentrations of Benzene returned to zero, indicating a possible retardation of microorganism due to reversible and irreversible sorption to the particle surfaces.

• Journal of Soil and Groundwater Environment
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• v.18 no.1
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• pp.46-56
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• 2013

Laboratory scale experiments to remove benzene in solution by using the bio-carrier composed of dead biomass have been performed. The immobilized bio-carrier with dead Bacillus drentensis sp. and polysulfone was manufactured as the biosorbent. Batch sorption experiments were performed with bio-carriers having various quantities of biomass and then, their removal efficiencies and uptake capacities were calculated. From results of batch experiments, 98.0% of the initial benzene (1 mg/L) in 1 liter of solution was removed by using 40 g of immobilized bio-carrier containing 5% biomass within 1 hour and the biosorption reaction reached in equilibrium within 2 hours. Benzene removal efficiency slightly increased (99.0 to $99.4%{\pm}0.05$) as the temperature increased from 15 to $35^{\circ}C$, suggesting that the temperature rarely affects on the removal efficiency of the bio-carrier. The removal efficiency changed under the different initial benzene concentration in solution and benzene removal efficiency of the bio-carrier increased with the increase of the initial benzene concentration (0.001 to 10 mg/L). More than 99.0% of benzene was removed from solution when the initial benzene concentration ranged from 1 to 10 mg/L. From results of fitting process for batch experimental data to Langmuir and Freundlich isotherms, the removal isotherms of benzene were more well fitted to Freundlich model ($r^2$=0.9242) rather than Langmuir model ($r^2$=0.7453). From the column experiment, the benzene removal efficiency maintained over 99.0% until 420 pore volumes of benzene solution (initial benzene concentration: 1 mg/L) were injected in the column packed with bio-carriers, investigating that the immobilized carrier containing Bacillus drentensis sp. and polysulfone is the outstanding biosorbent to remove benzene in solution.

• Journal of the Korean Society of Groundwater Environment
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• v.6 no.2
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• pp.95-100
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• 1999

Hydrocarbon compounds in vadose zone soils caused by adsorption onto the surfaces of solid particles are generally considered to show retardation effect. In this study, we investigated the retardation effect on the transport of Benzene in a sandy soil by conducting batch and column tests. The batch test was conducted by equilibrating dry soil mass with Benzene solutions of various initial concentrations. and by analyzing the concentrations of Benzene in initial and equilibrated solutions using HPLC. The column test consisted of monitoring the concentrations of effluent versus time known as a breakthrough curve (BTC). We used KCl and Benzene solutions with the concentration of 10 g/L and 0.88 g/L as a tracer, and injected them into the inlet boundary of the soil sample as a square pulse type respectively, and monitored the effluent concentrations at the exit boundary under a steady state condition using an EC-meter and HPLC. From the batch test, we obtained a distribution coefficient assuming that a linear adsorption isotherm exists and calculated the retardation factor based on the bulk density and porosity of the column sample. We also predicted the column BTC curve using the retardation factor obtained from the distribution coefficient and compared with the measured BTC of Benzene. The results of the column test showed that i) the peak concentration of Benzene was much smaller than that of KCl and ⅱ) the travel times of peak concentrations for the two tracers were more or less identical. These results indicate that adsorption of Benzene onto the sand panicles occurred during the pulse propagation but the retardation of Benzene caused by adsorption was not present in the studied soil. Comparison of the predicted with the measured BTC of Benzene resulted in a poor agreement due to the absence of the retardation phenomenon. The only way to describe the absolute decrease of Benzene concentration in the column leaching experiment was to introduce a decay or sink coefficient in the convection-dispersion equation (CDE) model to account for an irreversible sorption of Benzene in the aqueous phase.

• Journal of Environmental Science International
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• v.15 no.4
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• pp.341-347
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• 2006

Adsorption characteristics of benzene by zeolite were investigated using irradiating microwave. Experimental apparatus was applied to a U-type fix-bed column equipped with microwave system. Zeolite, itself, seems to be inappropriated to remove benzene because of a hygroscopic property, Microwave irradiation to zeolite, however, brings about decreasing $H_{2}O$ adsorption and increasing benzene adsorption. This causes that the dipole material such as $H_{2}O$ was vibrated and heated by irradiation of microwave and desorbed from zeolite. And then, benzene starts to be absorbed by zeolite. In this study, the results showed that the selective adsorption of benzene was occurred by the microwave irradiation and the adsorption capacity of benzene was increased by increasing microwave energy. As a results, it was found that the zeolite could be used to adsorb benzene with microwave and this method make it feasible simultaneously to adsorb and desorb benzene.

• Journal of Urban Science
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• v.8 no.2
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• pp.29-34
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• 2019

Benzene pollution is becoming increasingly serious, and the treatment technology of benzene has attracted much attention. In this paper, a self-made photocatalytic reactor was used to explore the removal rate of benzene under the ultraviolet light with the wavelength of 253.7nm. The results showed that the degradation rate of benzene decreased from 64.29% to 16.26% when the concentration increased from 43mg/㎥ to 256mg/㎥ under the condition of 28W UV light intensity and 50s residence time. Under the condition of 28W UV light intensity and 103mg/㎥ concentration, the residence time increased from 16.5s to 50s, and the benzene removal rate increased from 13.23% to 42.72%.Under the condition of benzene concentration 103mg/㎥ and residence time of 50s, the removal rate of benzene increased from 29.34% to 52.58% in the process of UV light intensity rising from 28W to 48W.It is concluded that decreasing the concentration and increasing the residence time of gas were beneficial to the removal of benzene and increasing the light intensity can improve the removal rate of benzene.

• Microbiology and Biotechnology Letters
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• v.17 no.3
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• pp.224-230
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• 1989

For the production of catechol from benzene, bacteria capable of assimilating benzene as a sole carbon and energy source were isolated from soils. Among them, newly isolated strain, KY-114 hay-ing the best ability of producing catechol from benzene was selected and a mutant Pseudomonas sp. HW-103 was developed from Pseudomonas sp. KY-114 by using mutagenesis induced by N-methyl - N'- nitro - N -nitrobo guanidine. The catechol reduction from benzone by Pseudomonas sp. HW-103 was investigated under various conditions. The highest catechol concentration (0.61 g/$\ell$) was obtained in the growth medium (pH 6.5) containing 1% sodium citrate, 0.75% (NH$_4$)$_2$SO$_4$, 0.15% benzene and other minerals at 3$0^{\circ}C$ after incubating of 15hrs. In the catechol production through the reaction with resting rolls, 2.5 g/1 of catechol was produced from 4 g/$\ell$ of benzene after incubation of 10 hrs under the optium conditions, which correponds to 45% of theoretical catechol yield.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.2
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• pp.375-383
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• 2000

A mixed culture isolated from petroleum-contaminated soil was enriched on toluene as a sole carbon and energy source, and degradation characteristics of BTEX(Benzene, Toluene, Ethylbenzene, Xylenes) was observed. In the single-substrate experiments, all the BTEX compounds were degraded, and it was degraded as following orders; toluene, benzene, ethylbenzene, and p-xylene. In the degradation experiments of BTEX mixtures, the degradation rate was decreased compared to that in the single substrate experiment and ethylbenzene was degraded faster than benzene. In the experiments of binary-mixtures, various substrate interactions such as inhibition, stimulation, and non-interaction were observed, and ethylbenzene was shown to be most potent inhibitor of BTEX degradation. In the degradation characteristic studies of xylene isomers, m-xylene and p-xylene were degraded as carbon sources, and it was stimulated in the presence of either benzene or toluene. However, degradation of o-xylene was enhanced only in the presence of benzene.