• Title, Summary, Keyword: Hydrothermal

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Comparison of CTD Cast and CTD Tow-yo Methods for Detecting Hydrothermal Plume (열수 플룸 검출을 위한 CTD Cast와 CTD Tow-yo 방법 비교)

  • Son, Juwon;Joo, Jongmin;Ham, Dong Jin;Yang, Seungjin;Kim, Jonguk
    • Ocean and Polar Research
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    • v.36 no.2
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    • pp.179-187
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    • 2014
  • Directly searching for undiscovered hydrothermal vent sites is inefficient due to the practical difficulty of comprehensively imaging vent fields. Thus, most searches for hydrothermal vent sites rely on the detection of hydrothermal plumes from water column observation. Detecting and measuring the hydrothermal plumes are the most efficient way to infer the presence and distribution of hydrothermal vents. Both the array of vertical casting and lateral towing are the most common methods to discover hydrothermal plumes. In this study, we compared results of cast and tow-yo operations along the same section of a spreading center with a distance of 20.5 km in the North Fiji Basin for mapping hydrothermal plumes. Operation of CTD tow-yo provides a detailed pattern of plumes which enable us to locate the hydrothermal vents. On the other hand, identification of hydrothermal activity can be determined effectively by CTD cast with additional analysis of geochemical tracers. Reduction in the operating time is another advantage of CTD cast operation, especially for regional-scale survey. Our results show that the combination of CTD cast and tow-yo would improve the efficiency of the hydrothermal plume survey to locate new hydrothermal vent sites.

Effect of Hydrothermal Treatment on the Antioxidant Activity of Rice Hull Extracts

  • Park, Sun-Min;Lee, Seung-Cheol
    • Food Science and Biotechnology
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    • v.18 no.6
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    • pp.1435-1438
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    • 2009
  • Hydrothermal treatment of rice hull was hydrothermal carried out at 105, 110, $121^{\circ}C$ for 15, 30, 60 min, respectively, using a conventional autoclave. Antioxidant activity of the hydrothermal treated rice hull extract was evaluated by determining total phenol contents (TPC), 1,1-diphenyl-2-picylhydrazyl (DPPH) radical scavenging activity (RSA), reducing power, and ABTS RSA. TPC, DPPH RSA, reducing power, and 2,2-azinobis(3-ethylenebenzothiozoline-6-sulfonic acid) (ABTS) RSA of the extract were significantly increased with increasing treated temperature and time. For example, hydrothermal extracts at $121^{\circ}C$ for 60 min increased the TPC, DPPH RSA, reducing power, and ABTS RSA to 0.840 mg/mL, 64.77%, 1.437, and 92.11%, respectively, while those of the extracts treated at $105^{\circ}C$ for 60 min were 0.508 mg/mL, 51.23%, 0.819, and 45.22%, respectively. The results indicated that hydrothermal treatment of rice hull was very effective to increase phenolic compounds and antioxidant activity of rice hull extract.

Sulfur Isotope Composition of Seafloor Hydrothermal Vents in the Convergent Plate Boundaries of the Western Pacific: A Role of Magma on Generation of Hydrothermal Fluid (서태평양 지판소멸대의 해저열수분출구에서 관찰되는 황동위원소 조성변화: 열수 생성의 다양성과 마그마의 역할)

  • Kim, Jong-Uk;Moon, Jai-Woon;Lee, Kyeong-Yong;Lee, In-Sung
    • Economic and Environmental Geology
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    • v.45 no.2
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    • pp.145-156
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    • 2012
  • Seafloor hydrothermal system occurs along the volcanic mid-ocean ridge, back-arc spreading center, and other submarine volcanic regions. The hydrothermal system is one of the fundamental processes controlling the transfer of energy and matter between crust/mantle and ocean; it forms hydrothermal vents where various deepsea biological communities are inhabited and precipitates metal sulfide deposits. Hydrothermal systems at convergence plate boundaries show diverse geochemical properties due to recycle of subducted material compared to simple systems at mid-ocean ridges. Sulfur isotopes can be used to evaluate such diversity in generation and evolution of hydrothermal system. In this paper, we review the sulfur isotope composition and geochemistry of hydrothermal precipitates sampled from several hydrothermal vents in the divergent plate boundaries in the western Pacific region. Both sulfide and sulfate minerals of the hydrothermal vents in the arc and backarc tectonic settings commonly show low sulfur isotope compositions, which can be attributed to input of magmatic $SO_2$ gas. Diversity in geochemistry of hydrothermal system suggests an active role of magma in the formation of seafloor hydrothermal system.

Hydrothermal Solution-Rhyolite Reaction and Origin of Sericitite in the Yukwang Mine (유문암-열수 반응과 유광 견운모 광상의 성인)

  • Park, Maeng-Eon;Choi, In-Sik;Kim, Jin-Sup
    • Economic and Environmental Geology
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    • v.25 no.3
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    • pp.225-232
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    • 1992
  • The hydrothermal alteration is evaluated using multicomponent equilibrium calculations with the program CHILLER for the reactions between hydrothermal water and rhyolite at the temperature of $300^{\circ}C$ and pressure of 500 bars. The chemical-reaction model on the depositional processes of the sericitite confirms that the hydrothermal water-rock interaction(hydrothermal alteration) is the main mechanism of the sericitite formation. The principal change in the aqueous phase during the reaction is the pH increase. Overall trends for the major species are the increase in total molalities of K, Ca, $SiO_2$, Al, Mg, Fe, Na, and sulfide in solid phase with hydrothermal water-rhyolite reaction and the decrease of them in aqeous solution by precipitation of hydrothermal products. Quartz and sericite are the first minerals to form. The sequence of minerals to precipitate following them is chlorite, epidote, pyrite and microcline as water/rock ratio decreases. Although calculated results cannot duplicate the complexities of natural hydrothermal alteration, the calculation provides thermodynamic constraints on the natural process. The calculation results resemble those of experimental studies. Sericitite forms where pH decreases and water/rock ratio increases.

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Hydrothermal Reactivity of Various Classified Fly Ashes by Electrostatic Precipitator (전기집진장치로부터 단별채취한 플라이 애쉬의 수열반응성)

  • ;Estuo Sakai;Masaki Daimon
    • Journal of the Korean Ceramic Society
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    • v.37 no.8
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    • pp.811-816
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    • 2000
  • This paper discussed hydrothermal reactivity of Ca(OH)2 and classified bituminous fly ashes which were collected at an electrostatic precipitator in coal fired power plant at 181$^{\circ}C$. The major products of hydrothermal reaction were tobermorite and hydrogrossularite because bituminous fly ashes contained Al2O3 content greater than 20 wt%. As increasing amount of Al2O3 content greater than 20 wt%. As increasing amount of Al2O3 in glass phases, formation of hydrogrossularite increased. Formation rate of crystalline tobermorite increased with content of finer particles, higher glass content and more Al2O3 in glass phases. There was a positive correlation between residue on 45${\mu}{\textrm}{m}$ sieve and hydrothermal reactivity of fly ash up to 3 hours. The hydrothermal reactivity of fly ash at 181$^{\circ}C$ for 12 hours was more affected by fineness than by glass content of fly ash.

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Hydrothermal Carbonization and Characterization of Glucose in the Presence of a Copper Catalyst (구리촉매를 이용한 글루코스의 열수탄화 및 특성 분석)

  • Song, Younghan;Kim, Changhyun;Kim, Hyungsup
    • Textile Science and Engineering
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    • v.54 no.1
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    • pp.17-21
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    • 2017
  • Recently, carbonaceous structures have drawn considerable attention owing to their electrochemical, mechanical, and thermal properties. Compared to conventional carbonization processes, hydrothermal carbonization has many merits, such as its relatively low processing temperature (below $400^{\circ}C$) and simple apparatus. In this study, hydrothermal carbonized structures were fabricated using a glucose solution of varying concentrations in the presence of a copper catalyst. The copper catalyst decreased the diameter of the hydrothermal-carbonized sphere. When the glucose concentration was low, the shape of the hydrothermal-carbonized material changed from spherical to planar.

Characterization and hydrothermal surface modification of non-swelling property mica using nano silver (은나노를 이용한 비팽윤성 운모의 수열적인 표면개질 및 특성평가)

  • Seok, Jeong-Won;Park, Ra-Young;Kim, Pan-Chae
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.17 no.4
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    • pp.172-178
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    • 2007
  • Mica (muscovite) powders were synthesized by hydrothermal method (horizontal turning method). The hydrothermal conditions for the synthesis of mica were prepared by the ratio of $K_2O : Al(OH)_3 : SiO_2$ = 1 : 3 : 3 mol% as the starting materials with KOH (8 mol%) solution as the hydrothermal solvent and reaction temperature at $260^{\circ}C$ for 72hrs. The synthetic powder used for preparation of nano silver coated mica by vertical hydrothermal treatment. The hydrothermal conditions for the treated as nano silver coating were prepared by the synthetic powder as raw materials, triple distilled water ($0.5{\ell}$) solution as the hydrothermal solvent with nano silver sol (1,000 ppm) as the material of nano silver coating and reaction temperature at $160{\sim}260^{\circ}C$ for 72 hrs. After hydrothermal treatment, structural, judgment of nano silver coating and character of nano silver coated mica were examined by XRD, SEM, TEM-EDX and shake plask method.

Provenance of Sediments and Evidence of Hydrothermal Venting Adjacent to the Fonualei Rift and Spreading Center, Lau Basin, Southwest Pacific (남서태평양 라우분지 푸누아레이 열곡확장대 인근 퇴적물의 기원과 열수 분출의 증거)

  • Kim, Mun Gi;Hyeong, Kiseong;Seo, Inah;Yoo, Chan Min
    • Ocean and Polar Research
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    • v.42 no.1
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    • pp.33-47
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    • 2020
  • The bulk and partition geochemistry was studied in two sediment cores collected from the axial valley of the north-central Fonualei Rift and Spreading Center (FRSC), Lau back-arc Basin, southwest Pacific. The sediments consist of mostly volcanic ash, although minor amounts of biogenic and other components were present in some intervals. The major element composition of bulk sediments recalculated to a carbonate-free basis was in good agreement with the magma compositions of the adjacent Tofua Arc and the FRSC, with only significant difference in Mn content. The enrichment of Mn and other associated elements (e.g. Cu, Co, Ni, and P) is attributed to hydrothermal input to the sediments, as evidenced by their significant partitioning in the non-detrital phases according to the partition geochemistry. Hydrogenetic and diagenetic inputs were assessed to be relatively insignificant. Estimated hydrothermal Mn fluxes during the Holocene ranged between 5.0 and 37.1 mg cm-2 kyr-1, with the higher values in younger sediments, suggesting enhanced hydrothermal activity. The hydrothermal Mn fluxes comparable to or higher than those reported from other spreading centers with strong hydrothermal activities may indicate the presence of unknown hydrothermal vent sites and/or topographic restriction on the dispersal of hydrothermal plumes in the northern part of the FRSC.

Conversion of organic residue from solid-state anaerobic digestion of livestock waste to produce the solid fuel through hydrothermal carbonization

  • Yang, Seung Kyu;Kim, Daegi;Han, Seong Kuk;Kim, Ho;Park, Seyong
    • Environmental Engineering Research
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    • v.23 no.4
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    • pp.456-461
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    • 2018
  • The solid-state anaerobic digestion (SS-AD) has promoted the development and application for biogas production from biomass which operate a high solid content feedstock, as higher than 15% of total solids. However, the digested byproduct of SS-AD can be used as a fertilizer or as solid fuel, but it has serious problems: high moisture content and poor dewaterability. The organic residue from SS-AD has to be improved to address these problems and to make it a useful alternative energy source. Hydrothermal carbonization was investigated for conversion of the organic residue from the SS-AD of livestock waste to solid fuels. The effects of hydrothermal carbonization were evaluated by varying the reaction temperatures within the range of $180-240^{\circ}C$. Hydrothermal carbonization increased the calorific value through the reduction of the hydrogen and oxygen contents of the solid fuel, in addition to its drying performance. Therefore, after the hydrothermal carbonization, the H/C and O/C atomic ratios decreased through the chemical conversion. Thermogravimatric analysis provided the changed combustion characteristics due to the improvement of the fuel properties. As a result, the hydrothermal carbonization process can be said to be an advantageous technology in terms of improving the properties of organic waste as a solid-recovered fuel product.

Hydrothermal carbonization of sewage sludge for solid recovered fuel and energy recovery (수열탄화를 이용한 하수 슬러지의 고형연료화 및 에너지 회수 효율)

  • Kim, Daegi;Lee, Kwanyong;Park, Kiyoung
    • Journal of Korean Society of Water and Wastewater
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    • v.29 no.1
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    • pp.57-63
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    • 2015
  • Recently, Korea's municipal wastewater treatment plants generated amount of wastewater sludge per day. However, ocean dumping of sewage sludge has been prohibited since 2012 by the London dumping convention and protocol and thus removal or treatment of wastewater sludge from field sites is an important issue on the ground site. The hydrothermal carbonization is one of attractive thermo-chemical method to upgrade sewage sludge to produce solid fuel with benefit method from the use of no chemical catalytic. Hydrothermal carbonization improved that the upgrading fuel properties and increased materials and energy recovery, which is conducted at temperatures ranging from 200 to $350^{\circ}C$ with a reaction time of 30 min. Hydrothermal carbonization increased the heating value though the increase of the carbon and fixed carbon content of solid fuel due to dehydration and decarboxylation reaction. Therefore, after the hydrothermal carbonization, the H/C and O/C ratios decreased because of the chemical conversion. Energy retention efficiency suggest that the optimum temperature of hydrothermal carbonization to produce more energy-rich solid fuel is approximately $200^{\circ}C$.