• New & Renewable Energy
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• v.5 no.4
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• pp.80-85
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• 2009

The effects of various organic wastes on anaerobic fermentative hydrogen production were studied using enriched mixed microflora in batch tests. Rotten fruit, corn powder and organic wastewater enriched with sulfate (up to 1,000 mg/L) were used for experiments. Maximum hydrogen production (547.1 mL) was observed from rotten apple with initial substrate concentration of 132.2 g COD/L. The experimental result on sulfate enriched organic wastewater indicated that hydrogen production is not adversely influenced by relatively high sulfate concentration. Residual sulfate content remained at 96-98 % after 75 hours of reaction, which showed that no major sulfate reduction was occurred at pH 5.3-5.5 in the reactor. The volatile fatty acid (VFA) fractions produced during the reaction was in the order of butyrate > acetate > propionate in all experiments. The results of this study would be useful for controlling the conditions on fermentative hydrogen production using different feedstocks.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.6
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• pp.635-641
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• 2005

Batch experiments were performed to evaluate the effect of sulfate reduction on methane production and reductive dechlorination, both compete for hydrogen with sulfate reduction. Dechlorination was inhibited by sulfate reduction at lower hydrogen concentration because their threshold values for hydrogen are similar (2 nM). Unlike methane production mainly inhibited transformation of cDCE to ethene, sulfate reduction inhibited the initial dechlorination step, PCE reduction into cDCE as well as cDCE dechlorination. The presence of sulfate eliminated methanogens as hydrogen competitor because of its high threshold value of 10 nM. When sulfate coexisted with PCE, dechlorination efficiency was not affected by the increase of seed concentration as both dechlorination and sulfate reduction were stimulated simultaneously by the increased seeding culture.

• Journal of the Korean Ceramic Society
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• v.22 no.6
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• pp.5-8
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• 1985

Graphite has been oxidized to graphite hydrogen sulfate in concentrated $H_2SO_4$. Anodic oxidation and chemical oxidation of graphite in $H_2SO_4$ generally leads to the formation of intercalation compounds of the ionic salt type through incorporation of $H_2SO_4^-$ions and $H_2SO_4$ molecules into the graphite. Several other reactions also accur at various points of the charging cycle. But there is no satisfactory kinetics and mechanism of intercalationin graphite. We have studied them with anodic oxidation and chemical oxidation. We found six distinct phenomena between 2nd stage and 1st stage in chemical oxidation. We examined them in detail by the following in the measurements electrical oxidation. X-ray diffractions UV-Vis spectroscopy density measurements. We could obtained a equation for kinetic according to the reaction rate from this results and mechanism of intercalation between 2nd stage and 1st stage with hydrogen sulfate in graphite. Three thesis were written for the mechanism of intercalation compounds in graphite with hydrogen sulfate ; first thesis is anodic oxidation second thesis is chemical oxidation and definition of transit phase between 2nd etc the third thesis is the kinetic mechanism of intercalation compounds in graphite with Hydrogen sulfate. This thesis is the first paper among three thesis as anodic oxidation.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.6
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• pp.434-441
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• 2009

The effect of varying sulfate concentration on continuous fermentative hydrogen production was studied using enriched mixed microflora in continuously fed reactor. Glucose was used as a model substrate for carbohydrates, and hydraulic retention time (HRT) was maintained at 1, 0.5, 0.25 day, respectively. Sulfate concentration was 0${\sim}$20,000 mg/L and the operating pH was maintained at 5.5. The experimental results indicate that hydrogen production is not affected by high sulfate concentration and shorter HRT of 0.25 day enhance hydrogen production. At HRT 1, 0.5, 0.25 day, the hydrogen production rate and hydrogen yield were 2.6, 4.6, 9.4 L/day, and 2.0, 1.8, 1.6 mol $H_2$/mol glucose, respectively. Residual sulfate content was 96${\sim}$98, 95${\sim}$97, and 94${\sim}$97% at HRT 1, 0.5, 0.25 day which show that no sulfate reduction occurred in the reactor during the experiments. Results of Fluorescence In Situ Hybridization (FISH) may indicate the presence of HPB (hydrogen producing bacteria) under all experimental conditions. However, SRB (sulfate reducing bacteria) were not found.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.506-510
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• 2009

The effects of various organic wastes on anaerobic fermentative hydrogen production were studied using enriched mixed microflora in batch tests. Rotten fruit, corn powder and organic wastewater enriched with sulfate (up to 1,000 mg/L) were used for experiments. Maximum hydrogen production (547.1 mL) was observed from rotten apple with initial substrate concentration of 132.2 g COD/L. The experimental result on sulfate enriched organic wastewater indicated that hydrogen production is not adversely influenced by relatively high sulfate concentration. Residual sulfate content remained at 96-98 % after 75 hours of reaction, which showed that no major sulfate reduction was occurred at pH 5.3-5.5 in the reactor. The volatile fatty acid (VFA) fractions produced during the reaction was in the order of butyrate > acetate > propionate in all experiments. The results of this study would be useful for controlling the conditions on fermentative hydrogen production using different feedstocks.

• KSBB Journal
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• v.20 no.6
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• pp.453-457
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• 2005

We investigated the effect of sulfate re-addition on hydrogen production under sulfur-deprived condition. When the final concentration of sulfate to cell suspensions($0{\sim}120{\mu}M$) was increased, chlorophyll concentration, culture density, and total amount of $H_2$ produced, increased up to an optimal concentration of $30{\mu}M\;MgSO_4$. Maximum hydrogen volume was 236 mL $H_2/L$ culture at $30{\mu}M\;MgSO_4$. However, the addition of excess sulfate(above $MgSO_4\;60{\mu}M$) delayed the start of hydrogen production and the induction of hydrogenase. Accordingly, the final yield of hydrogen production was reduced. Using these results, we attempted the continuous and sustained hydrogen production by sulfate re-addition($30{\mu}M\;MgSO_4$) using a single C. reinhardtii culture for up to 4 cycles. In total, hydrogen production volume was 625 mL $H_2/L$ culture.

• Journal of Soil and Groundwater Environment
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• v.13 no.1
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• pp.24-31
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• 2008

Sulfate reducing bacteria (SRB) is universally distributed in the sediment, especially in marine environment. SRB reduce sulfate as electron acceptor to hydrogen sulfide in anaerobic condition. Hydrogen sulfide is reducing agent enhancing the reduction of the organic and inorganic compounds. With SRB, therefore, the degradability of organic contaminants is expected to be enhanced. Ferrous iron reduced from the ferric iron which is mainly present in sediment also renders chlorinated organic compounds to be reduced state. The objectives of this study are: 1) to investigate the reduction of TCE by hydrogen sulfide generated by tht growth of SRB, 2) to estimate the reduction of TCE by ferrous iron generated due to oxidation of hydrogen sulfide, and 3) to illuminate the interaction between SRB and ferrous iron. Mixed bacteria was cultivated from the sludge of the sewage treatment plant. Increasing hydrogen sulfide and decreasing sulfate confirmed the existence of SRB in mixed culture. Although hydrogen sulfide lonely could reduce TCE, the concentration of hydrogen sulfide produced by SRB was not sufficient to reduce TCE directly. With hematite as ferric iron, hydrogen sulfide produced by SRB was consumed to reduce ferric ion to ferrous ion and ferrous iron produced by hydrogen sulfide oxidation decreased the concentration of TCE. Tests with seawater confirmed that the activity of SRB was dependent on the carbon source concentration.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.1
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• pp.21-28
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• 2011

Fe, Ni and Co, typical active components, were dispersed on $Al_2O_3$ and $TiO_2$ for $SO_3$ decomposition. $SO_3$ decomposition was conducted at the temperature ranges from $750^{\circ}C$ to $950^{\circ}C$ using the prepared catalysts. Alumina based catalysts showed the surface areas higher than Titania based catalysts, which resulted from spinel structure formation of alumina based catalysts. Catalytic $SO_3$ decomposition reaction rates were in the order of Fe>Co${\gg}$Ni. The metal sulfate decomposition temperature were in the order of Ni>Co>Fe from TGA/DTA analysis of metal sulfate. During $SO_3$ decomposition, metal sulfate can form on the catalysts. $SO_2$ and $O_2$ can be produced from the decomposition of metal sulfate. In that point of view, the less is the metal sulfate deomposition temperature, the higher can be the $SO_3$ decomposition activity of the metal component. Therefore, it can be concluded that metal component with the low metal sulfate decomposition temperature is the pre-requisite condition of the catalysts for $SO_3$ decomposition reaction.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.339-342
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• 2000

A three phase fluidized bed bioreactor including Thiobacillus sp.IW was used to remove hydrogen sulfide and ammonia simultaneously. In this study, hydrogen sulfide was oxidized to sulfate by the microorganism and ammonia was reacted with the sulfate to form ammonium sulfate. Removal efficiency of hydrogen sulfide was almost perfect up to 45 mg/l h of inlet loading rate, whereas that of ammonia was reduced as inlet loading rate increased from 10 mg/1 h.

• Journal of the Korean Ceramic Society
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• v.25 no.4
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• pp.408-414
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• 1988

This thesis is 2nd thesis from "Mechanism of Intercalation Compounds in Graphite with Hydrogen sulfate(J. Korea Cer. Soc. Vol. 22. No.6, 1985). We have oxidized natural Graphite flakes(0.1~0.2mm., Kropfm hl passau in Deutchland. S40) with a solution of CrO3 in H2SO4. Whilst persulfate ions were intercalated, too, below 7$^{\circ}C$, no evidence for intercalation of a peroxo compound was found at 22$^{\circ}C$. The reaction was interrupted after various times by filtering and washing with concentrated H2SO4. X-ray diffraction showed that the 2nd stage compound had already been formed after 2 minutes. We could only follow further oxidation to the blue stage compound which was completed after 35 minutes. We have found six distinct intermediate stage between 2nd stage and 1 stage. Experiments are described on the formation of intermediate stage color and X-ray diffraction analysis.ysis.