• Title/Summary/Keyword: siliceous

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Preparation of Supported CTAB/MCM-41 and CTAB-Nafion/MCM-41 Mesoporous Molecular Sieve and Their Use in the Brominating Reaction (담지된 CTAB/MCM-41 and CTAB-Nafion/MCM-41 메조다공성 분자체의 제조 및 브롬화 반응에 사용)

  • Hu, Guoqin;Li, Hua;Liu, Juan;Zhu, Jiang
    • Journal of the Korean Chemical Society
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    • v.55 no.4
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    • pp.691-696
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    • 2011
  • CTAB or CTAB-Nafion catalyst were successfully supported on siliceous hollow tubular MCM-41 which synthesized by hydrothermal method using CTAB as a single template or CTAB and Nafion-Na as mixed templates. The properties of two kinds of catalysts were characterized with XRD, SEM and adsorption and desorption isotherms of nitrogen and pore diameter distribution, respectively. Then they were applied to catalyze brominating reaction of 1,7-heptanediol, moreover the rate of brominating reaction with different catalysts was compared. The results showed that catalytic activities of CTAB/MCM-41 and CTAB-Nafion/MCM-41 are better than CTAB, and that of CTAB-Nafion/MCM-41 is the best because of its phase-transfer and strong acidity function. The two kinds of catalysts can be separated from the reactive products and recycled.

Computation of Plug Capacity for Open -Ended Piles Driven into Sands (모래지반에 타입된 개단말뚝의 관내토지지력 산정)

  • 백규호;이승래
    • Geotechnical Engineering
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    • v.9 no.4
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    • pp.7-16
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    • 1993
  • Calibration chamber tests were conducted on open -ended model piles driven into dried siliceous sands with different soil conditions in order to clarify the effect of soil conditions on plug capacity, The model pile used in the test series was devised so that the bearing capacity of an open -ended pile could be measured out into three components , outside shaft resistance. plug resistance and tip resistance. Under several assumption, the value of earth pressure coefficient in the soil plug is calculated. It is gradually reduced with increase in the longitudinal distance from the pile tip. At the bottom of soil plug, it tends to decrease with increase in the penetration depth and relative density, and to increase with the increase of ambient pressure. In comparison of measured and calculated plug capacities using the one -dimensional analysis, we note that API code and one -dimensional analysis combined with P suggested by Randolph et al. and O'Neill et al. result in great underestimation of the plug capacity. Therefore, based on the test results, an empirical equation was suggested to compute the earth pressured coefficient to be used in the calculation of plug capacity using the one -dimensional analysis. and it produces proper plug capacities for all soil conditions.

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A Feasibility Study on the Application of Ferrosilicon By-Product in Concrete to Replace Silica Fume (콘크리트 내 실리카퓸을 대체하기 위한 페로실리콘 산업부산물의 활용 적절성에 대한 연구)

  • Kim, Hansol;Cho, Won Jung;Ann, Ki Yong
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.7 no.4
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    • pp.413-422
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    • 2019
  • A ferrosilicon (FS) by-product was applied into a cementitious binder in concrete substituting the ordinary Portland cement (OPC). The original material characteristic of FS is very identical to silica fume (SF) regarding chemical composition and physical properties such as specific surface area and specific gravity. Therefore, the FS and SF concrete or mortal of which 10% of the material was replaced to total binder weight were fabricated to evaluate the feasibility of using F S as a binder, and the comparative information of OPC, FS and SF concrete was given. The hydration characteristic of FS concrete was analyzed using X-ray diffraction analysis. The FS concrete was beneficial in compressive strength, resistivity against chloride ingress and reducing porosity considering performance of OPC concrete but the advantage was less than using SF. A possibility of alkali-silica expansion was found out from the FS concrete due to the agglomerated size of the silica particles.

The Origin and Mineralogy of the Dongyang Talc Deposit (동양활석광상(東洋滑石鑛床)에서 산출(産出)되는 활석(滑石)에 대한 광물화학적(鑛物化學的) 및 성인적(成因的) 연구(硏究))

  • Moon, Hi-soo;Kim, Seong Tae
    • Economic and Environmental Geology
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    • v.21 no.3
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    • pp.235-255
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    • 1988
  • Talc deposit of pipe-like form occurrs in the lower part of the Hyangsanri Dolomite with a strike of N40 -50 E and a dip of 40 -50 NW which is one formation of the Ogcheon Super Croup. The pipi-like ore body plunge at about $40^{\circ}$ to the west and are parallel to the lineation developed in the area. Structural formulae of tales occurred in this deposit are close to the ieal composition $Mg_6Si_8O_{20}(OH)_4$ showing limited deviation from ideal one. Substitution of Al for Si in tetrahedral site is of little or nothing ranging 0-0.04 and octahedral occupancy is close to six ranging 5.88-5.98 atoms per unit cell. Predominant octahedaral cation is Mg and proportion of divalent cations is generally over 97percent. Calcite -dolomite thermometry is obtained by determining the mol % $MgCO_3$using of EPMA and XRD methods. The peak metamorphic temperature can be estimated at $470{\pm}30^{\circ}C$ in the area whereas carbonates occurred at near talc ore show lower temperature than $400^{\circ}C$ that the calcite solvus limit is not well established. It indicates that the talc deposit was formed at the lower temperature that the metamorphic temperature. Cosequently, the formation of talc by metamorphism is questionable and the alteratin zone developed around the talc ore is very limited. The occurrence of talc ore in the dolomite as well as mineralogy, calcite-dolomite geothermometry, chlorite geothermometry, field and microscopic evidence suggest that siliceous ascending hydrothermal solution along the fracture is responsible for the formation of talc. It was considered that the slight fracturing of dolomite was formed by deformation prior to the mineralization.

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Effects of Simulated Acid Rain on Chemical Properties of the Experimental Soil of pinus densiflora S. et Z. and Forsythia Koreana Nak. Seedlings (人工酸性雨가 소나무 및 개나리 盆植苗土壤의 化學的 性質에 미치는 影響)

  • Cheong, Yong-Moon
    • Journal of Korean Society for Atmospheric Environment
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    • v.4 no.1
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    • pp.33-44
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    • 1988
  • For the purpose of examining the effects of simulated acid rain on the chemical properties of the experimental soil in Pinus densiflora seedlings and Forsythia koreana rooted cuttings, the experimental design of randomized block arrangement with three replications was implemented in the experimental field of Yesan National Agricultural Junior College. One-year-old Pinus densiflora seedlings and Forsythia koreana cuttings were planted in the pots filled the mixed soils (nursery soil: forest soil of siliceous sandy loam = 1 : V/V)in the early spring of 1985. The regime of artificil acid rain, in terms of spray frequency per monthly and spray amount at single treatment per plot, was simulated on the basis of climatological data averaged from 30 years records. Simulated acid rain (pH 2.0, pH4.0, and pH 5.5 as control) containing sulfuric and nitric acid in the ratio of 3:2 (chemical equivalant basis) diluted ground water, were treated on the experimental plants under condition of cutting off the natural precipitation with vinyl tunnel, during the growing season (May 1 to August 31) in 1985. THe results obtained in this study were as follows; 1. Soil acidity was dropped, and exchangeable aluminum contents in the soil was dramatically increased in both species, with decreasing pH levels of acid rain. 2. Exchangeable potassium, clacium, magnesium contents, and base saturation degree of the soil were highly drcreased in two species as the pH levels of acid rain decreased. 3. In two species, sulfate concentrations in the soil were decreased of pH 4.0 treatment, and remarkably increased at pH 2.0 treatment of acid rain in comparison with control. 4. Total nitrogen and available phosphate contents of the soil were not affected by acid rain treatment in the both species, and Fe contents at pH 2.0 treatment were highest among three acid rain treatments.

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Influence of the Filler's Particle Size on the Mechanical Properties of Ultra High Performance Concrete(UHPC) (충전재의 입경 크기가 초고성능 콘크리트의 역학적 특성에 미치는 영향)

  • Kang, Su Tae;Park, Jung Jun;Ryu, Gum Sung;Kim, Sung Wook
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.4A
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    • pp.573-580
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    • 2008
  • In this paper, we estimated the effect of the siliceous filler's particle size on the performance of Ultra High Performance Concrete (UHPC). Filler's particle diameters considered in this paper were about 2, 4, 8, 14, $26{\mu}m$ and the performance was evaluated by testing fluidity in fresh concrete, compressive strength, ultimate strain, elastic modulus and flexural strength in hardened concrete. We also carried out XRD and MIP tests to analyze the relationship between the mechanical properties and microstructure. Test results showed that the smaller filler's particle size improves flowability and strength properties. MIP results revealed that the smaller size of filler decreased the porosity and thus increased the strength of UHPC. From XRD analysis, we could find out there were little influence of filler's particle size on chemical reactivity in UHPC.

Exploiting Natural Diatom Shells as an Affordable Polar Host for Sulfur in Li-S Batteries

  • Hyean-Yeol Park;Sun Hyu Kim;Jeong-Hoon Yu;Ji Eun Kwon;Ji Yang Lim;Si Won Choi;Jong-Sung Yu;Yongju Jung
    • Journal of Electrochemical Science and Technology
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    • v.15 no.1
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    • pp.198-206
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    • 2024
  • Given the high theoretical capacity (1,675 mAh g-1) and the inherent affordability and ubiquity of elemental sulfur, it stands out as a prominent cathode material for advanced lithium metal batteries. Traditionally, sulfur was sequestered within conductive porous carbons, rooted in the understanding that their inherent conductivity could offset sulfur's non-conductive nature. This study, however, pivots toward a transformative approach by utilizing diatom shell (DS, diatomite)-a naturally abundant and economically viable siliceous mineral-as a sulfur host. This approach enabled the development of a sulfurlayered diatomite/S composite (DS/S) for cathodic applications. Even in the face of the insulating nature of both diatomite and sulfur, the DS/S composite displayed vigorous participation in the electrochemical conversion process. Furthermore, this composite substantially curbed the loss of soluble polysulfides and minimized structural wear during cycling. As a testament to its efficacy, our Li-S battery, integrating this composite, exhibited an excellent cycling performance: a specific capacity of 732 mAh g-1 after 100 cycles and a robust 77% capacity retention. These findings challenge the erstwhile conviction of requiring a conductive host for sulfur. Owing to diatomite's hierarchical porous architecture, eco-friendliness, and accessibility, the DS/S electrode boasts optimal sulfur utilization, elevated specific capacity, enhanced rate capabilities at intensified C rates, and steadfast cycling stability that underscore its vast commercial promise.

A Study on Geotechnical Properties of Deep-Sea Sediments, NE Equatorial Paciflc of KODOS Area (북동태평양 KODOS 지역 심해저 퇴적물의 지질공학적 특성)

  • Kim, Ki-Hyun;Moon, Jai-Woon;Lee, Kyeong-Yong;Son, Seung-Kyu;Oh, Jae-Kyung;Chi, Sang-Bum
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.5 no.4
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    • pp.320-334
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    • 2000
  • Deep-sea surface sediment were analyzed for their geotechnical properties, and the sediment samples were collected with a multiple-corer from 31 stations along the track line (131$^{\circ}$30'W, 5-12$^{\circ}$N) in the northeast equatorial Paciflc. Most of the sediments from the northern part (8-12$^{\circ}$N) showed typical properties of siliceous sediments, whereas the southern part (5-6$^{\circ}$N) showed calcareous characteristics due to high biogenic carbonate productivity in the surface waters, where its water depth was shallower than the carbonate compensation depth (CCD: 4,400 m). Geotechnical properties changed sharply at the boundary of 7$^{\circ}$N. Calcareous sediments from the southern part had low water contents, low porosity, low shear strength, high bulk density and high specific grain density, whereas siliceous sediments from the northern part attained high water content, high porosity, high shear strength, low bulk density and low specific grain density. Higher sediment activities were observed in the northern sediment samples than the southern sediment samples. The core samples of the northern sediments were divided into a semi-liquid upper layer and a consolidated lower layer with a boundary at 5-8 cm. These sediment samples showed a rapid increasing pattern along the downcore in original shear strength when an opposite trend was observed in the southern samples. The results showed that sediment variabilities in geotechnical properties between the northern and southern parts such as productivities of surface water, grain solubility due to water depth variation, sedimentation rate, erosion and redistribution of sediment, and combined sedimentary processes were distinctly different along the latitude.

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Studies on the Absorption Capacity of Phosphorus of Korean Top-soils (우리나라 표층토(表層土)의 인산흡수력(燐酸吸收力)에 관(關)한 연구(硏究))

  • Park, C.S.;Han, K.H.;Lim, S.K.;Lee, J.H.
    • Korean Journal of Soil Science and Fertilizer
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    • v.2 no.1
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    • pp.1-13
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    • 1969
  • A total of 129 surface(upto 30 cm depth) soil samples were selected from the profile samples collected during reconnaissance soil survey in 1967, for the determination of phosphorus absorption co-efficient. The distribution range for each soil association has been established. The physicochemical factors affecting the phosphorus absorption coefficient have also been examined. The following general conclusions can be drown: 1. In general, the phosphorus absorption coefficient of the soil association of presently arable land are lower than the soils which are not in cultivation. 2. The higher the cation exchange capacity of soils, the higher is the phosphorus absorption coefficient. The factors governing phosphorus absorption coefficient in various soil associations are as follows: Parent Material Soil Association Governing Factor Fluvio marine Low Humic Gley Fluvio marine Alluvial Complex Narrow valley Siliceo mafic materials Red-yellow podzolic Redish Siliceo mafic materials Brown Lateritic Clay content Siliceous crystalline materials Lithosols C.E.C. & Clay content Alluvium Low Humic Alluvium Gley Alluvial Organic matter Siliceous crystalline materials Red-Yellow Podzolic Organic matter and clay content 4. The relation between phosphorus absorption coefficient determined by $(NH_4)_2HPO_4(y)$ and by the P 700 ppm $NaH_2PO_4(x)$ is $Y=2.716X+37(r=0.96^{**})$ which shows highly significant positive correlation and linear regression.

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Effect of Fineness of Siliceous Materials on Correction of Soil Acidity under Submerged Condition (담수시(湛水時) 규산물질(珪酸物質)들의 입도별(粒度別) 토양산도교정능력(土壤酸度矯正能力))

  • Lee, Yun Hwan;Han, Ki Hak;Kim, Bok Jin
    • Korean Journal of Soil Science and Fertilizer
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    • v.5 no.2
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    • pp.59-64
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    • 1972
  • The liming effect of the four different siliceous materials with six grades of fineness were investigated in comparison with limestone under the submerged condition for three months, and the alkalinity extracted by 0.07N-EDTA and N-NaOAc solutions were determined to evaluate the neutralizing power of these materials. 1. Fused phosphate took 20 days with finer particles than 60 mesh (Tyler), 34 days with -40+48 mesh particles and 84 days with -20+25 mesh particles to reach the pH 5.5 from pH 4.0 of initial soil pH. These adjusted soil acidities were less 1.0-0.5 unit of pH compared with the pH of particles of limestone. 2. The basic reduction furnace slag increased the pH value to 5.5 in the finer particles than 100 mesh, but the other coarse particles appeared to have slow changes of the soil acidity to pH 4.5-4.7 for the three months. Wollastonite didn't affect the increase of soil pH in coarser particles than 25 mesh whereas other finer particles increased upto pH 4.5-5.0. Blast furnace slag is definitely slower through all sizes of particles. 3. In the relationship between the adjusted soil acidities and alkalinities dissolved in EDTA and NaOAc solution, NaOAc-alkalinity agreed quite closely to the activity of neutralizing value of silicates and limestone containing fineness of particles. The correlation coefficients between the amended soil acidities and NaOAc-alkalinities were stabilized with high significance at the 8 days after water logging and 16 days with the EDTA-alkalinities.

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