• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.151-152
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• 2019

This study is aimed at comparing the effect of cement mortar made of sulfuric acid treated ISO standard sand with that of cement mortar made of normal ISO standard sand. In the water absorption test, water absorption of standard sand increases with the increase of immersion time in sulfuric acid solution. The results show that at the water cement ratio of 0.5, the longer the standard sand is immersed in sulfuric acid, the greater the compressive strength of the cement mortar sample.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.421-426
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• 2001

The pneumatic classification and acidic leaching behaviors of phosphor sludge have been examined to establish the recycling system of rare earth components contained in waste fluorescent lamp. At first, separation characteristic of rare earth components and calcium phosphate in phosphor sludge was investigated by pneumatic classification. After pneumatic classification of phosphor sludge, rare earth components were leached in various acidic solutions and sodium hydroxide solution. For recovery of soluble component in leaching solution, rare earth components were separated as hydroxide and oxalate precipitations. The experimental results obtained are summarized as follows: (1) In classification process, rare earth components in phosphor sludge were concentrated to 29.3% from 13.3%, and its yield was 32.9%. (2) In leaching process, sulfuric acid solution was more effective one as a leaching solvent of rare earth component than other solutions. Y and Eu components in phosphor sludge were dissolved in sulfuric acid solution of 1.5 k㏖/㎥, and other rare earth components were rarely dissolved in leaching solution. Leaching degrees of Y and Eu were respectively 92% and 98% in the following optimum leaching conditions; sulfuric acid concentration is 1.5 k㏖/㎥ , leaching temperature 343 K, leaching time 3.6 ks and pulp concentration 30 kg/㎥. (3) Y and Eu components of phosphor sludge contained in waste fluorescent lamp were, effectively recovered by three processes of pneumatic classification, sulfuric acid leaching and oxalate precipitation methods. Their recovery was finally about 65 %, and its purity was 98.2%.

• Journal of Microbiology and Biotechnology
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• v.14 no.2
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• pp.243-249
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• 2004

The toxicity of inorganic sulfuric acid as a stressor was characterized in Saccharomyces cerevisiae KNU5377. In this work, we examined physiological responses to low extracellular pH $(pH_{ex})$ caused by inorganic $H_2SO_4$, which could not affect cell growth after pH was adjusted to an optimum with Trizma base. The major toxicity of sulfuric and was found to be reduction of environmental pH, resulting in stimulation of plasma membrane ${H^+}-ATPase$, which in turn contributed to intracellular alkalinization. Using a pH-dependent fluorescence probe, 5-(and-6)-carboxy SNARF-1, acetoxymethyl ester, acetate (carboxy SNARF-1 AM acetate), to determine $pH_{in}$, we found that color was dependent on the changes of intracellular pH which coincided with calculated $pH_{in}$ of alkalinization up to approximately pH 7.3. This alkalinization did not seem to affect survival of these cells exposed to 30 mM sulfuric acid, which lowered the $pH_{ex}$ of the glucose containing growth media up to approximately pH 3.0; however, the cells could grow only up to 70% of the maximum growth in the same media, when 30 mM sulfuric acid was added.

• Resources Recycling
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• v.29 no.3
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• pp.61-74
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• 2020

This study was conducted to improve the recycling process of waste fluorescent lamp, and investigate the possibility of using the waste fluorescent lamp glass as a raw material for glass beads, the leaching method of rare earth from the waste phosphor powder, and the possibility of solvent extraction of rare earth from the rare earth leaching solution. The waste phosphor contained 28.9% yttrium oxide, 3.46% cerium oxide, 1.95% europium oxide, 1.76% terbium oxide, and 1.43% lanthanum oxide. As a result of the trial production of glass beads using waste fluorescent lamp glass, it was judged that the production yield and quality were excellent, so that waste fluorescent lamp glass could be used as a raw material for glass beads. The soda roasted waste phosphor was leached in water and thereby the aqueous solution was blown with CO₂ to drop the pH to about 7, Then, Al, Si and residual N₂CO₃ were dissolved, and NaAlCO₃(OH)₂ and SiO₂ were precipitated in the aqueous solution. In the solvent extraction of cyanex272-hydrochloric acid, cyanex272-sulfuric acid, D2EHPA-hydrochloric acid, D2EHPA-sulfuric acid, Ionquest290-hydrochloric acid, Ionquest290-sulfuric acid, p507-hydrochloric acid using xylene as a diluent, the extraction yield of Y, Eu, Ce, La, and Tb are close to 100%. However, in this conditions, the difference in extraction yield for each element, that is, selectivity is 16% or less.

• Journal of the Korean Wood Science and Technology
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• v.40 no.6
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• pp.389-396
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• 2012

In this study, we investigated the kinetics of acid-catalyzed hydrolysis of xylan over a 60 min at $120^{\circ}C$. Sulfuric, oxalic and maleic acids were used as acid catalyst for hydrolysis. The calculated degradation rate constants ($k_1$) showed a correlation with the acid concentration, meaning that the stronger the acid, the higher the xylan degradation rate. Among sulfuric, oxalic and maleic acid catalyzed hydrolysis, the xylan degradation rate to xylose was highest with sulfuric acid. At equivalent solution pH, acid catalyzed hydrolysis was proportional to $H^+$ concentration. The $k_1$ of dicarboxylic acid such as oxalic and maleic acid was higher than that of sulfuric acid at same pH values during hydrolysis.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.4
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• pp.37-43
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• 2014

The crystallinity and molecular weight of cotton linter need to be controlled to be more easily dissolved in NMMO during manufacture of clothing fabrics. Electron beam irradiation and sulfuric acid treatment were used as pre-treatment to reduce molecular weight of cotton linter more efficiently, and after the pre-treatment, peroxide bleaching was followed in alkaline condition. After those processes, the crystalline indices of the cotton linters were measured by XRD method, and other properties such as their alpha cellulose contents and degree of polymerization were measured. It was found that the crystallinity index of cotton linter was decreased as the irradiation of electron beam increased while increased as the dose of sulfuric acid increased. These results strongly suggested that electron beam damaged the crystalline structure of the cellulose directly while sulfuric acid dissolved mostly non-crystalline area of the cellulose structure.

• Journal of the Korean Wood Science and Technology
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• v.17 no.3
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• pp.1-7
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• 1989

This study was performed to obtain the optimal condition that hydrolyzed exploded pine(Pinus densiflora), oak(Quercus serrata) and birch wood(Betula platyphylla var. japonica) by using sulfuric acid. The results obtained were summarized as follows: In hydrolysis of wood meal with sulfuric acid. maximum yield of sugar appeared that pine was 12 hours. oak and birch were 24 hours with 65% sulfuric acid. Futhermore, when wood meal and exploded woods were hydrolyzed with 65% sulfuric acid at $23^{\circ}C$ for 6 hours(primary hydrolysis), diluted to 3% and hydrolyzed again at $100^{\circ}C$ for 2 hours(secondary hydrolysis), the maximum sugar yield of wood meals were 6 hours. those of higher steam exploded pine wood was 3 hours. of lower steam exploded oak and birch woods were 6 hours. The sugar analyses of exploded wood showed that the amount of arabinose and xylose residue rapidly decreased. content of nemicelluose decreased with increase of steaming time and pressure.

• Journal of The Korean Society of Grassland and Forage Science
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• v.11 no.1
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• pp.43-52
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• 1991

The overall objective of this research was to evaluate the effects of spraying sulfuric acid solution, and adding corn meal or molasses to reed canarygrass silage on digestibility of dry matter (DM) and fibrous components in ruminant. DM content of molasses or corn meal treated silages were higher than control. Whereas, sulfuric acid treated silage showed lower DM content compared with untreated control. Acid detergent fiber content was similar among treatments, but neutral detergent fiber (NDF) and hemicellulose concentration were higher in treated silages than those of control. Organic acids content were also increased in treated silages. In contrast, silage pH were lower in treated silages. Treated silages increased both rate and extent of DM and NDF in situ digestibility compared to control at all incubation times. Especially, 7 % molasses and 0.4 % sulfuric acid treated silages increased DM and NDF digestibility significantly after 12 hours of incubation compared with control. In nitro DM and NDF digestibility showed similar trend to in situ incubation. Also treated silages(mo1asses or sulfuric acid treated) incubated in situ had higher particle-associated carboxymethylcellulase activity throughout the incubation except 72 hours.

• Resources Recycling
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• v.30 no.3
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• pp.41-46
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• 2021

Methanesulfonic acid (MSA) can be considered effective in the leaching of metals because of its advantageous physical and chemical properties. The chemical reactivities of MSA and sulfuric acid were compared based on their structures and the dissolution data of Co and Ni metal. The inductive and resonance effects play a vital role in the chemical reactivities of these two acids. The dissolution percentages of Co and Ni in the sulfuric acid solution were higher than those in the MSA solution under the same experimental conditions. Considering the strong acidity of MSA and the high solubility of its metal salts, MSA can be employed as a leaching agent for the recovery of metals.

• Journal of Marine Bioscience and Biotechnology
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• v.7 no.2
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• pp.71-78
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• 2015

Sulfated polysaccharides from plants or seaweed are well known for antioxidant, anticoagulant activity or other biological activities. The aim of the present study is to optimize the condition for the isolation of water soluble polysaccharides (WSP) and evaluate the biological activity. WSP was isolated from defatted microalgae B. braunii using chlorosulfonic acid or sulfuric acid. Among WSP isolated using sulfuric acid showed the lowest the content of total carbohydrates (g/L), whereas showed the highest antioxidant activity. Also the preliminary structural analysis of WSP was performed by FT-IR spectroscopy analysis.