• Bulletin of the Korean Chemical Society
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• v.27 no.4
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• pp.563-567
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• 2006

The application of a synergistic solvent extraction by the formation of ternary complex with pyrocatechol violet (PV) and benzalkonium chloride (BC) was studied for determination of trace Zn(II) in water samples. The pH of sample solution and the amount of PV and BC added were optimized for the formation of the stable complex, a proper solvent was selected for the effective extraction, and the concentration of nitric acid was fixed for the back extraction of the complex from the solvent. After the ionic strength of 100 mL sample solution was adjusted to 0.1 M by adding NaCl and the pH was fixed at 9 with a carbonate buffer, 1.0 mL of 2% PV solution was added to form Zn(II)-PV complex then the Zn(II)-PV/BC ternary complex was made by adding 1.0 mL of 10% BC solution. The ternary complex was extracted into 10 mL of MIBK. And the ternary complex was back-extracted with 10 mL of 1.0 mol/L nitric acid to determine Zn(II) by a flame atomic absorption spectrophotometer (flame-AAS). The interference of concomitant ions on the extraction of Zn(II) was investigated. This procedure was applied to the analysis of three real samples such as Dalbang-dam water, laboratory tap water and Jungnajin seawater. The recoveries of Zn(II) in spiked samples were 86.58-104.1%.

• Clean Technology
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• v.22 no.4
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• pp.250-257
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• 2016

As an attempt to replacing petroleum-based chemicals with bio-based ones, synthesis of furfural from biomass-derived xylose attracts much attention in recent days. Conventionally, furfural from xylose has been produced via the utilization of highly corrosive, toxic, and environmentally unfriendly mineral acids such as sulfuric acid or hydrochloric acid. In this study, microwave-assisted biphasic reaction process in the presence of novel bio-based heterogeneous acid catalysts was developed for the eco-benign and effective synthesis of furfural from xylose. The microwave was irradiated for reaction acceleration and a biphasic system consisting of $H_2O$ : MIBK (1 : 2) was designed for continuous extraction of furfural into the organic phase in order to reduce the undesired side products formed by decomposition/condensation/oligomerization in the acidic aqueous phase. Moreover, sulfonated amorphous carbonaceous materials were prepared from wood powder, the most abundant lignocellulosic biomass. The prepared catalysts were characterized by FT-IR, XPS, BET, elemental analysis and they were used as bio-based heterogeneous acid catalysts for the dehydration of xylose into furfural more effectively. For further optimization, the effect of temperature, reaction time, water/organic solvent ratio, and substrate/catalyst ratio on the xylose conversion and furfural yield were investigated and 100% conversion of xylose and 74% yield of furfural was achieved within 5 h at $180^{\circ}C$. The bio-based heterogeneous acid catalysts could be used three times without any significant loss of activity. This greener protocol provides highly selective conversion of xylose to furfural as well as facile isolation of product and bio-based heterogeneous acid catalysts can alternate the environmentally-burdened mineral acids.

• Journal of Environmental Science International
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• v.12 no.9
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• pp.967-976
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• 2003

Volatile organic compounds (VOCs) are present in essentially all natural and synthetic materials from petrol to flowers. In this study, indoor and outdoor VOCs concentrations of houses, offices and internet-cafes were measured and compared simultaneously with personal exposures of each 50 participants in Asan and Seoul, respectively. Also, factors that influence personal VOCs exposure were statistically analyzed using questionnaires in relation to house characteristics, time activities, and health effects. All VOCs concentrations were measured by OVM passive samplers (3M) and analyzed with GC/MS. Target pollutants among VOCs were Toluene, o-Xylene, m/p-Xylene, Ethylbenzene, MIBK, n-Octane, Styrene, Trichloroethylene, and 1,2-Dichlorobenzene. Indoor and outdoor VOCs concentrations measured in Seoul were significantly higher than those in Asan except Ethylbenzene. Residential indoor/outdoor (I/O) ratios for all target compounds ranged from 0.94 to 1.51 and I/O ratios of Asan were a little higher than those of Seoul. Relationship between personal VOCs exposure, and indoor and outdoor VOCs concentrations suggested that time-activity pattern could affect the high exposure to air pollutant. Factors that influence indoor VOCs level and personal exposure with regard to house characteristics in houses were building age, inside smoking and house type. In addition insecticide and cosmetics interestingly affected the VOCs personal exposure. Higher exposure to VOCs might be caused to be exciting increase and memory reduction, considering the relationship between measured VOCs concentrations and questionnaire (p<0.05).

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.5 no.1
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• pp.87-103
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• 1995

Since being granted permission for self-assessment of the work environment by the Department of Labor in 1992, POSCO's Industrial Hygiene Laboratory has participated in domestic and Foreign Quality Control Programs 8 times and has obtained remarkable results. It has made a lot of effort to be a proficient laboratory with the ability to observe and analyse environmental monitoring data. The summary of results is as follows: 1. POSCO's Industrial Hygiene Laboratory has received a "P(Proficient)" grade from the round 115 to round 119 of AIHA/NIOSH PAT Program for analysis of such metals as lead, cadmium, zinc, and chromium, and also has received a "P(Proficient)" grade from its round 119 of for organic solvent analysis, i,e,. Trichloroethylene(TCE), Carbon Tetr-achloride(CTC), 1,2-Dichloroethane(DCE), 1,1,1-Trichloroethane(MCM), Tetrachloroethylene (PCE), Chloroform(CFM), Benzene(BNZ), toluene(TOL), and O-xylene(OXY). 2. In the Quality Control Evaluation Program performed by the Industrial Health Research Institute,Korea Industrial Safety Corporation, POSCO has passed impressively in the3-metal analysis test for lead, cadmium, cupper, and in the 6 organic solvent analysis test for Benzene(BNZ), toluene(TOL), O-xylene(OXY), Trichloroethylene(TCE) and Methyl isobutyl keton(MIBK), n-Hexane with 2 standard deviations. These analytic techniques should be practically applied to various fields, and reliable results of environmental monitoring should be considered to improve the work environment and to keep workers from occupation related diseases.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.3 no.2
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• pp.177-187
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• 1993

The exposure levels of mixed organic solvents for 66 exposed workers in six paint manufacturing plants were evaluated. In 66 exposed workers and 30 control subjects, we also determined the concentrations of toluene and xylene metabolites, hippuric acid, ($o^-$, $m^-$, and $p^-$)methylhippuric acid. The results were as follow ; 1. Seven organic compounds, which on averge accounted for approximately 90% of the identified mass in each painting plants air samples, were selected for quantification : methyl ethyl ketone, ethyl acetate, methyl isobutyl ketone, toluene, butyl acetate, ethyl benzene, ($o^-$, $m^-$, $p^-$)xylene. 2. The average mixed organic solvent exposure levels in 66 points with workplce were 3.8ppm of MEK, 12.2ppm of ethyl acetate, 4.0ppm of MIBK, 28.7ppm of toluene, 3.8ppm of butyl acetate, 10.2ppm of ethyl benzene, 14.6ppm of xylene, respectively. 3. For the total 66 points with workplace, the rate of them of which mixed solvents in air was exceeded th TLV of 1.0 were obtained for 23%(15/66 point). 4. The concentrations of hippuric acid in urine of exposed group and control were $0.94{\pm}0.65g/g$ of creatinine, $0.16{\pm}0.11g/g$ of creatinine, respectively. 5. There was a linear correlation between the end shift hippuric acid acid levels in urine and exposed toluene in air : y=0.02079X+494.2, r=0.6488, n=55 y:hippuric acid in urine(mg/g of creatinine), x:toluene levels in air(ppb) Toluene levels of 100ppm in air have been caculated to hippuric acid of 2.57g/g of creatinine in urine. 6. There was a linear correlation between the end shift methylhippuric acid acid levels in urine and exposed xylene in air : y=0.01664X+31.6, r=0.7264, n=55 y:methylhippuric acid in urine(mg/g of crea.), x:xylene levels in air(ppb) Xylene levels of 100ppm in air have been caculated to methylhippuric acid of 1.69g/g of creatinine in urine.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.5 no.1
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• pp.104-118
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• 1995

This study was performed to evaluate factors affecting desorption of organic solvents collected on charcoal tube and to find out the optimum condition. Desorption efficiency for polar analytes was improved when several polar desorption solvents such as methanol, dimethylformamide(DMF), 2-(2-butoxyethoxy)ethanol were added to carbon disulfide($CS_2$). The best improvement was achieved when 10% dimethylformamide(DMF) in $CS_2$ was used as desorption solvent. During storage of polar analytes, recovery was greatly reduced. Especially, the recovery of cyclohexanone was decreased to 18.1 % after a month storage at $34^{\circ}C$. After two weeks storage, recovery of polar analytes was sharply decreased. Water adsorbed on charcoal interfered the recovery of polar analytes but didn't interfere that one of nonpolar solvent, toluene. When 10% DMF in $CS_2$ was used as desorption solvent, the effect of water on recovery was decreased, comparing with Desorption efficiency increased when analyte loading increased, and usage of 10% DMF in $CS_2$ decreased the loading effect. Increasing volume of desorption solvent was not effective to improve desorption efficiency of analytes when 10% DMF was used. Continuous shaking and sonication is not helpful to increase the desorption efficiency of analytes except cyclohexanone using 10% DMF. When silica gel used as adsorbent, methanol was better desorbent than dimethylsulfoxide. Analytes adsorbed on silica gel showed high recovery in low concentration and less affected by humidity. On the basis of this study, the following conclusions have been drawn. To improve the recovery of polar organic materials in air samples, it is necessary to analyze samples as soon as possible after they were collected. Otherwise, samples must be stored at low temperature. Using two components of desorption solvents, such as 10% DMF in $CS_2$, the effects of loading and humidity decreased for polar analytes such as methyl ethyl ketone and methyl isobutyl ketone. When work place has high humidity with low concentration of polar organic solvents, silica gel can be used as adsorbent, because it produces quantitative recovery for polar analytes at this condition. But it should be noted that high humidity makes breakthrough easy in silica gel samples.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.16 no.4
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• pp.314-323
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• 2006

This study was conducted to identify ingredients of thinners and to confirm reliability of material safety data sheets (MSDS) of thinners for public and workers' health. The 41 thinner products were collected from paint shops located in Busan and Gyeongnam province. The 12 thinner products among them were identified using product MSDS. GC-MSD was used to analyze 41 kinds of thinners qualitatively and quantitatively. The 12 products MSDS were compared with thinner's component through qualitative analysis to confirm MSDS. Chemical ingredients, such as Benzene, Toluene, and Xylene etc., of thinners were analysed in quantity. The 41 thinner products contained 17 disclosed specific, trade name, or generically described chemical solvent ingredients. These 17 ingredients came under 6 classes: alcohols, aromatic hydrocarbons, esters, glycol ethers, ketones, and mixtures. These 17 ingredients were important in the view of industrial hygiene and had occupational exposure limit in the ambient, such as toluene, xylene, acetone, nonane, EGEE, heptane, cumene, MIBK, indene, tri-methyl benzene, etc, were found in 41 kinds of thinners. Aromatic hydrocarbons were the most identified ingredient in thinners. Especially, the benzene, which induces leukemia, was found in 4 kinds of thinners. The content rates of benzene in thinners were 0.25~1.18%. The benzene in enamel thinner, which were 0.39~0.72%, was highest from chemical classification. The contents of toluene, which was found from 27 kinds of thinners, were 5.35~64.16%, which were highest in sobu thinner as 58.80%. Xylene was found from 22 kinds of thinners and contents of xylene were 4.61~72.42%. Acrylic thinner's contents of xylene were 12.06~51.05%, which was most high. It was found that contents of benzene were increased and frequency of detection was decreased through comparison with other study. The MSDS possession rate of paint shops was low as 29.27%. So it did not provide information with public or workers. Mean of agreement rate between MSDS and components of thinners through qualitative analysis was 42.01% and it has wide range from 8.3% to 75%. There are many deficiencies in MSDS about component of thinners. In some case of sample, expecially, despite containing benzene, information was not written it on MSDS.