• Title/Summary/Keyword: 황산

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${SO_4}^{2-}$ ion Removal from Solution by Crystal Precipitation on Surface Active Glasses (표면활성유리에의 결정석출을 이용한 용액중 황산염 이온 제거)

  • 남명식;김철영
    • Journal of the Korean Ceramic Society
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    • v.35 no.12
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    • pp.1286-1293
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    • 1998
  • ${SO_4}^{2-}$ ions present in industrial waste water if combined with other metal ions in the water can cause serious scale problem in a transporting pipe. In this study therefore ${SO_4}^{2-}$ ions in an acidic solution have been removed by using surface active glasses. Glasses with various compositions of $SiO_2-Na_2O-B_2O_3-RO$ (R=Mg, Ca, Sr, Ba) system were reacted in a ${SO_4}^{2-}$ ion-containing solution with various pHs ranging from 1 to 4 for various time the reacted glass surfaces were analyzed by XRD and SEM and all ions in the reacted solution were also measured ${SO_4}^{2-}$ ions in the solution were combined with divalent ions leached out of glass and precipitated on the glass surface as sulfate crystals. In this was the surface ion could be removed from the acidic solution. The sulfate ion removal capacity is closely related to the solubility product con-stants of the newly formed sulfate crystals. Almost no sulfate crystal was formed on the MgO-containing glass while sulfate crystals were easily formed on the glass containing either SrO or BaO This indicates that those glasses have strong removal efficiency of ${SO_4}^{2-}$ ions from the solution.

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Sulfate reduction and sulfur isotopic fractionation in marine sediments (해양퇴적물내에서의 황산염 환원과 황의 안정동위원소 분화)

  • 한명우
    • Journal of Environmental Science International
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    • v.2 no.1
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    • pp.43-49
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    • 1993
  • Concentrations of sulfate and 6-values of sulfate, $({\delta}^{34}SO_4_){pw}$, dissolved In pore waters were measured from the sediment cores of the two different marine environments : deep northeast Pacific (57-1) and coastal Kyunggi Bay of Yellow Sea (57-2) . Sulfate concentration in pore waters decreases with depth at both cores, reflecting sulfate reduction in the sediment columns. However, much higher gradient of pore water sulfate at 57-2 than 57-1 indicates more rapid sulfate reduction at 57-2, because of high sedimentation rate at the coastal area compared to the deep-sea. The measured 6-values, $({\delta}^{34}SO_4_){pw}$, follow extremely well the predicted trend of the Rayleigh fractionation equation. The range of 26.756 to 61.35% at the coastal core 57-2 is not so great as that of 32.4$\textperthousand$ to 97.8$\textperthousand$ at the deep-sea core 57-1. Despite greater graclient of pore water sulfate at 57-2, the 6-values become lower than those of the deep- sea core 57-1. This inverse relation between the 6-values and the gradients of pore water sulfate could be explained by the combination of the two subsequent factors : the kinetic effect by which the residual pore water sulfate becomes progressively enriched with respect to the heavy isotope of $^{34}S$ as sulfate reduction proceeds, and the intrinsic formulation effect of the Rayleigh fractionation equation in which the greater becomes the fractionation factor, the more diminished values of $({\delta}^{34}SO_4_){pw}$ are predicted.

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In-situ Precipitation of Arsenic and Copper in Soil by Microbiological Sulfate Reduction (미생물학적 황산염 환원에 의한 토양 내 비소와 구리의 원위치 침전)

  • Jang, Hae-Young;Chon, Hyo-Taek;Lee, Jong-Un
    • Economic and Environmental Geology
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    • v.42 no.5
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    • pp.445-455
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    • 2009
  • Microbiological sulfate reduction is the transformation of sulfate to sulfide catalyzed by the activity of sulfate-reducing bacteria using sulfate as an electron acceptor. Low solubility of metal sulfides leads to precipitation of the sulfides in solution. The effects of microbiological sulfate reduction on in-situ precipitation of arsenic and copper were investigated for the heavy metal-contaminated soil around the Songcheon Au-Ag mine site. Total concentrations of As, Cu, and Pb were 1,311 mg/kg, 146 mg/kg, and 294 mg/kg, respectively, after aqua regia digestion. In batch-type experiments, indigenous sulfate-reducing bacteria rapidly decreased sulfate concentration and redox potential and led to substantial removal of dissolved As and Cu from solution. Optimal concentrations of carbon source and sulfate for effective microbial sulfate reduction were 0.2~0.5% (w/v) and 100~200 mg/L, respectively. More than 98% of injected As and Cu were removed in the effluents from both microbial and chemical columns designed for metal sulfides to be precipitated. However, after the injection of oxygen-rich solution, the microbial column showed the enhanced long-term stability of in-situ precipitated metals when compared with the chemical column which showed immediate increase in dissolved As and Cu due to oxidative dissolution of the sulfides. Black precipitates formed in the microbial column during the experiments and were identified as iron sulfide and copper sulfide. Arsenic was observed to be adsorbed on surface of iron sulfide precipitate.

Magnesium Sulfate Resistance of Geopolymer Incorporating Evaporated Rice Husk Powder (증해추출 왕겨분말을 혼입한 지오폴리머의 황산마그네슘 저항성에 관한 연구)

  • Cho, Seung-Bi;Kim, Young-Su
    • Journal of the Korea Institute of Building Construction
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    • v.22 no.6
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    • pp.663-672
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    • 2022
  • The purpose of this study is to evaluate the magnesium sulfate resistance of a geopolymer mixed with rice husk powder. General concrete, silica fume mixed concrete, and binary blended geopolymer were selected as comparison targets to confirm the magnesium sulfate resistance, and sulfate deterioration was calculated using the compressive strengths with ages. In addition, the weight change rate and the relative dynamic coefficient of the geopolymer were comparatively analyzed, and the degree of etteringite formation was confirmed using X-ray diffraction analysis. the experiment, the geopolymer mixed with 10% rice husk powder showed 10.8% higher compressive strength than concrete with silica fume when submerged for 56 days. Also, the geopolymer mixed with rice husk powder showed a small weight change rate of 0.9 to 1.45%. composition after immersion in magnesium sulfate through X-ray diffraction analysis, it was observed that a small amount of ettringite was dispersed in the geopolymer containing rice husk powder. Thus, there is a high correlation with the corrosion resistance of magnesium sulfate

A New Methodology of Measuring Water Toxicity using Sulfur Oxidizing Bacteria (황산화미생물을 이용한 새로운 수(水)중 생태독성탐지 방법)

  • Oh, Sang-Eun
    • Journal of Korean Society of Environmental Engineers
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    • v.32 no.6
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    • pp.555-562
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    • 2010
  • For the rapid and reliable detection of toxic compounds in water, a novel toxicity detection methodology based on sulfur-oxidizing bacteria (SOB) has been developed. The methodology exploits the ability of SOB to oxidize elemental sulfur to sulfuric acid in the presence of oxygen. The reaction results in an increase in electrical conductivity (EC) and a decrease in pH. Using a synthetic stream water (EC=0.12 mS/cm and pH=7.2), the baseline steady-state EC and pH values were 0.5~1.2 mS/cm and ~2.5 over 7 days of testing at HRT 30 minutes. When nitrite compounds were added to the system, the effluent EC decreased and the pH increased due to the inhibition of the SOB. Optimum HRT was 30 min and this HRT could be decresed by using smaller sulfur particles.

Effect of Sulfate Reduction on the Hydrogen Competition among Dechlorination, Methane Production, and Sulfate Reduction (황산염 환원반응이 탈염소화, 메탄생성 및 황산염 환원 간 수소경쟁에 미치는 영향)

  • Lee, Il-Su;Bae, Jae-Ho
    • 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.

Sulphate Effects on Lime and Chemical Additives Stabilized Soils (생석회와 화학 첨가제 혼합토에 대한 황산염의 영향)

  • 민덕기;황광모;정진형
    • Journal of the Korean Geotechnical Society
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    • v.19 no.6
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    • pp.31-38
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    • 2003
  • It has been recently reported that the presence of sulphate causes abnormal volume changes in lime-stabilized soils. Volume changes in lime-stabilized soils can take place due to sulphate compounds such as ettringite. Sulphate compounds caused a variety of serious geotechnical hazards such as swelling pressure and damages to light structures and pavements. This paper discusses the influence of sulphate on the soil specimens treated with quicklime and chemical additives. The physical and mechanical characteristics were studied by means of laboratory tests. The results showed that the presence of sulphate treated soil reduced the shear strength of the lime treated soils and increased the swelling properties. SEM and XRD results indicated that the presence of sulphate producted needle-like crystals such as ettringite. Moreover, the role of needle-like crystals in specimen was probably related to the swelling properties.

Sulfate Attack Resistance and Microstructural Observations of Cement Matrix Exposed to a Low Temperature Condition (저온환경에 노출된 시멘트 경화체의 황산염침식 저항성 및 미세구조적 조사)

  • Lee, Seung-Tae
    • Journal of the Korea Concrete Institute
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    • v.21 no.5
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    • pp.611-617
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    • 2009
  • This paper reports an experimental study on the damage mechanism and resistance of Type I portland cement mortar and paste samples exposed to 5% sodium sulfate solution with different solution temperatures; namely, $4^{\circ}C$, $10^{\circ}C$ and $20^{\circ}C$. The resistance of mortar samples was evaluated using expansion, compressive strength and flexural strength measurements. Some microstructural observations such as x-ray diffraction, differential scanning calorimetry and scanning electron microscopy were also introduced to elucidate reactants formed by sulfate attack, especially in a low temperature condition. From the results, it was found that the degree of damage in the mortar samples was significantly associated with the temperature of sulfate solution. Low temperature of the sulfate solution led to the formation of thaumasite in mortar and paste samples, and subsequently a poor resistance to sulfate attack. Thus, it is noted that when concrete structures are exposed to sulfate media in the condition of a cold region or whether, special care should be taken.

A Study on Degradation Rate of Carbofuran in Sterilized Soil and Sulfate-added Paddy Soil (Carbofuran의 담수토양중(湛水土壤中) 분해(分解)에 대한 토양(土壤)의 멸균(滅菌)과 황산염(黃酸鹽) 첨가(添加)의 영향(影響)에 관(關)한 연구(硏究))

  • Tu, Ock-Ju
    • Korean Journal of Environmental Agriculture
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    • v.17 no.1
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    • pp.11-15
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    • 1998
  • Carbofuran was incubated for four weeks in five types of paddy soil samples at $25^{\circ}C$. The soil samples prepared in the study were as follows : control soil, sterilized soil, 10% cellulose added soil, 10% cellulose and 1% ferrous sulfate added soil, and 10% cellulose and 1% magnesium sulfate added soil. The degradation rate of carbofuran was significantly decreased(p<0.05) in sterilized soil.The degradation rate of carbofuran was significantly decreased by addition of cellulose(p<0.05) in femous sulfate added soil and magnesium sulfate added soil(p<0.01).

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Deactivation of V2O5/TiO2 catalytic system on the sulfuric oxides (V2O5/TiO2 촉매시스템의 황산화물에 대한 비활성화 특성)

  • Jang, Hyun Tae;Cha, Wang Seog
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.11
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    • pp.7433-7438
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    • 2015
  • Deactivation characteristics of $V_2O_5/TiO_2$ catalysts were studied for selective catalytic reduction(SCR) of NOx with ammonia in the presence of $SO_2$. Performance of catalyst was investigated for $deNO_x$ activity while changing temperature, $SO_2$ concentration. The activity of catalyst was decreased with the increase of $SO_2$ concentration and reaction time. Also, degree of activity drop was largely decreased with the increase of reaction temperature in the range of $250{\sim}300^{\circ}C$. Physicochemical properties of deactivated catalysts were characterized by BET, XRD, SEM, TPD analysis. According to the analysis results, deactivation phenomena occur due to the relatively high formation of ammonium sulfate salts, which created by unreacted ammonia and water in the presence of $SO_2$. It was revealed that ammonium sulfate cause the pore plogging of support and deposition of active matter.