• Korean Chemical Engineering Research
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• v.43 no.5
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• pp.588-594
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• 2005

We have investigated Y zeolite and activated carbon for an adsorptive desulfurization of diesel. In batch experiments, cation ($Cu^{2+}$, $Ni^{2+}$) exchanged Y zeolites showed high equilibrium adsorption capacity for sulfur compounds in model diesel, which contained BT, DBT and 4,6-DMDBT of each 50 ppmw in n-octane. But the cation exchanged Y zeolites lost its capacity in commercial diesel (186 ppmw). On the other hand, activated carbon showed reasonable adsorption capacity for sulfur compounds in both model and commercial diesel. The adsorption capacity of sulfur on Ni-Y zeolite was decreased with the increase of benzene concentration in model diesel but the sorption capacity on activated carbon was insensitive to aromatic concentration. In breakthrough test, activated carbon of 1 g could treat 15 ml of commercial diesel with 186 ppmw sulfur. Toluene showed good solvent for regenerating activated carbon among several solvents.

• Korean Chemical Engineering Research
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• v.46 no.5
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• pp.845-851
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• 2008

Oxidative desulfurizaton of model sulfur compounds and Industrial diesel fuel(LCO; Light Cycle Oil) over Ti-grafted SBA-15 catalyst was studied in a batch reactor with tert-Butyl Hydroperoxide(TBHP) as oxidant. Effects of Ti loading, TBHP/Sulfur mole ratio, reaction temperature on ODS activity and kinetic parameters were investigated. Ti-grafted SBA-15 catalyst showed higher sulfur removal activity in the oxidative desulfurization reaction of refractory sulfur compounds(DBT and 4, 6-DMDBT) and LCO, suggesting that Ti-grafted SBA-15 catalyst could be a good candidate for ODS catalyst.

• Journal of Life Science
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• v.18 no.12
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• pp.1712-1717
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• 2008

Volatile flavor compounds of onions were analyzed and compared during storage at $0.5^{\circ}C$, which harvested in 6 regions, such as Muan, Buan, Andong and 3 regions of Changnyeong (Yueo, Jangma and Seongsan). A total of 45 compounds were detected in samples by solid phase microextraction (SPME)/GC/MSD, consisting mainly of sulfur-containing compounds (21), aldehydes (13), ketones (2) and miscellaneous compounds (9). The sulfur-containing compounds were major compounds with ranges of $66.9{\sim}86.9%$ of total volatiles in 0 day of storage as regardless of harvested regions. Three regions (Yueo, Seongsan and Muan) had high amounts of over 4,043 ng/g in 0 day of storage, whereas 2 regions (Muan and Yueo) only had amounts of over 2,400 ng/g after 60 days of storage. Five sulfur-containing compounds known as having antioxidant activity (2,4-, 2,5-dimetylthiophene, 2-vinyl-1,3-dithiane, 5-methoxy thiazole and 3,5-diethyl-1,2,4-trithiolane and isomer) were the high levels in 3 regions (Yueo, Seongsan and Muan) during 60 day of storage. These 3 regions had also the highest amounts in 5 sulfur-containing compounds known as having anticarcinogenic activity ((Z)-, (E)-methyl propenyl disulfide, (Z)-, (E)-propenyl propyl disulfide, and di-2-propenyl disulfide) and kept same trend after 60 days of storage.

• Korean Journal of Food Science and Technology
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• v.39 no.6
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• pp.600-607
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• 2007

In this study, attempts were made to develop a method for controlling the volatile sulfur compounds in garlic. Crude alliinase extracted from fresh garlic was applied to garlic pulp blanched far 5 min at $100^{\circ}C$, and the changes in the thiosulfinates and volatile compounds of the blanched garlic pulp reacted with the enzyme were investigated. Eight kinds of thiosulfinates from garlic were separated by HPLC, and identified by LC/MS/MS. When the alliinase was added to the blanched garlic pulp at 100, 200, 300, or 400 units, and reacted for 15 min, respectively, thiosulfinates were generated in the amounts of 37, 68, 77, and 80% of the fresh garlic content (control). Under the same conditions, we analyzed the volatile compounds, where 28 peaks were identified by GC/MSD. Of the 28 peaks, 23 were volatile sulfur compounds. The results of the analysis showed that all the volatile compounds were generated at amounts of 25, 36, 66, and 76% of the content of the control, respectively. These results indicate that the sulfur compound content of garlic can be regulated, depending upon the reaction conditions of allinase.

• Journal of Oral Medicine and Pain
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• v.23 no.3
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• pp.263-270
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• 1998

Considering various factors contributing oral malodor, the accurate prediction of prognosis is very important to both clinician and patients. The present study has been performed to invetigate the relationship between treatment effeicacy and pre-treatment volatile sulfur compounds (VSC) level. Ninety patients were divided into three groups, A(<150ppb), B(150< <200ppb), and C(>200ppb) groups, according to pre-treatment VSC level detected by Halimeter, and each group included 30 patients. Routine therapeutic measures for oral were provided to each patient which consisted of oral prophylaxis, tooth brushing and flossing instruction, tongue scraping by proper device, and gargling of 0.25% ZnCl2 Solution. The group with high pre-treatment VSC level (>150ppb) showed significant reduction of VSC level at 1 and 3 weeks after. However, the group with low pre-treatment VSC level (<150ppb) did not show any significant reduction during the experimental periods. Collectively, the results suggested that patients with high pre-treatment VSC level show better prognosis.

• Korean Chemical Engineering Research
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• v.57 no.2
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• pp.283-288
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• 2019

Catalytic removal of sulfur compounds from heavy naphtha (HN) was investigated using a combination of an oxidation process using hydrogen peroxide and an adsorption process using granulated activated carbon (GAC) and white eggshell (WES). This study investigated the impact of changing several operating parameters on the desulfurization efficiency. Specifically, the volume ratio of $H_2O_2$ to HN (0.01~0.05), agitation speed ($U_{speed}$) of the water bath shaker ($100-500{\pm}1rpm$), pH of sulfur solution (1~5), amount of adsorbent (0.1~2.5 g), desulfurization temperature ($25{\sim}85{\pm}1^{\circ}C$) and contact time (10~180 minutes) were examined. The results indicate that the desulfurization efficiency resulting from catalytic and adsorption processes of GAC is better than that of WES for oxidation and removing sulfur compounds from HN due to its high surface area. The desulfurization efficiency depends strongly on all investigated operating parameters. The maximum removal efficiency of GAC and WES achieved by this study was 86 and 65, respectively.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.4
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• pp.417-428
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• 1999

The measurement of VOSCs(volatile organic sulfur compounds) in the air is nowadays a very important environmental research field. It is, however, very difficult because the concentration of the VOSC in ambient air is usually very low and the high reactivity makes it difficult to keep in container without loss of recovery. In this study, sampling method with cryogenic preconcentration is evaluated for analysis of atmospheric VOSC such as $CH_3SH,\;CH_3CH_2SH,\;CH_3SCH_3,\;CS_2,\;CH_3SSCH_3,\;CH_3SCH_2SCHA_3,\;and\;C_2H_5SSC_2H_5$ analyzed by GC-MS or GC-FID. Repeatabilities of measurement accompanied with preconcentration for 3-successive runs were in the range of 0.2~1.0% as a relative standard deviation. Stabilities up to 13 days were measured in 6 L canister and 10 L tedlar bag filled with VOSCs in ppb level. Higher stability was observed in tedlar bag as compared to canister with glass coated inner walls, and thiol compounds show dramatic losses in canister within 2~3 days. It is found that recovery over 70% was obtained in a week for all tested VOSCs when the compounds from ambient air matrix were stored in tedlar bag. It is also found that the stabilities of VOSCs are depending on humidity and coexisting compounds in matrix gas due to sample adsorption onto inner surface and reactivity. The results indicate the possibility and limitations of VOSC analysis in ambient air using container sampling method with cryogenic preconcentration.

• Journal of Microbiology and Biotechnology
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• v.21 no.7
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• pp.753-756
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• 2011

A methane-oxidizing bacterium was isolated from the enriched culture of a landfill cover soil. The closest relative of the isolate, designated M6, is Methylocystis sp. Based on a kinetic analysis, the maximum specific methane oxidation rate and saturation constant were 4.93 mmol gdry cell $weight^{-1}{\cdot}h^{-1}$ and 23${\mu}M$, respectively. This was the first time a kinetic analysis was performed using pure methanotrophic culture. The methane oxidation by M6 was investigated in the presence of aromatic (m- and pxylene and ethylbenzene) or sulfur (hydrogen sulfide, dimethyl sulfide, methanthiol) compounds. The methane oxidation was inhibited by the presence of aromatic or sulfur compounds.

• Journal of Sensor Science and Technology
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• v.33 no.3
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• pp.125-133
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• 2024

Gas chromatography (GC) separation technology and metal oxide semiconductor (MOS) gas sensors have been integrated for the effective analysis of volatile sulfur compounds (VSCs) such as H₂S, CH₃SH, (CH₃)₂S, and (CH₃)₂S₂. The separation and detection characteristics of the GC/MOS system using diluted standard gases were investigated for the qualitative and quantitative analysis of VSCs. The typical concentrations of the standard gases were 0.1, 0.5, 1.0, 5.0, and 10.0 ppm. The GC/MOS system successfully separated H₂S, CH₃SH, (CH₃)₂S, and (CH₃)₂S₂ using a celite-filled column. The reproducibility of the retention time measurements was at a 3% relative standard deviation level, and the correlation coefficient (R²) for the VSC concentration was greater than 0.99. In addition, the chromatograms of single and mixed gases were almost identical.

• The Korean Journal of Food And Nutrition
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• v.30 no.4
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• pp.788-795
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• 2017

This research has attempted to investigate the volatile flavor compounds of onion products through acetic fermentation, and to create a natural beverage with beneficial biological properties which can also fulfill customer quality standards. Onion products (OAF (M): Onion extracts at five days of acetic fermentation, OAF (F): Onion extracts at ten days of acetic fermentation) were produced by acetic fermentation. Volatile flavor compounds from onion extracts, OAF (M) and OAF (F) were used by Mixxor liquid extractions and analyzed by GC/MSD. Compounds of 49, 75 and 69 were identified in onion extracts, OAF(M) and OAF(F) respectively. Among the major volatile flavor compounds classes, sulfur containing compounds (36.7%), acids (31.2%) and aldehydes (13.5%) in onion extracts were changed into acids (69.6%) and alcohols (24.6%) in OAF (M) and acids (80.6%) and alcohols (15.5%) in OAF (F). During acetic fermentation acetic acid, 1,3-butanediol (odorless) and 2,3-butanediol (onion flavor) increased remarkably, sulfur-containing compound such as 2,5-dimethylthiophene having anti-oxidant activities was detected by fermentation.