• Title, Summary, Keyword: Bentonite

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Utilization of Mineral Oxides to Attenuate Mn-EDTA and Fluoride (산화광물을 이용한 수중의 망간-EDTA, 불소 제거)

  • 현재혁;남인영
    • Journal of Korea Soil Environment Society
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    • v.1 no.2
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    • pp.51-60
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    • 1996
  • Removal of Mn-EDTA complex and fluoride by use of hematite and ferrite, which are the by-product to be disposed of as industrial wastes, was investigated. For the comparison of removal rate, Na-bentonite known as excellent absorbent of inorganic contaminants was included in the experiments. As the results of batch mode experiments, for manganese, ferrite-A revealed 48∼65% of removal capacity, ferrite-B 46∼57%, hematite 17∼26%, while Na-bentonite showed 10∼23% of removal, depending on the initial concentration. Meanwhile, in case of fluoride : hematite revealed 53 ∼63% of removal : ferrite-A 54∼63 %, while ferrite-B did 20∼38 %. From the results, it can be postulated that the capacity of hematite and ferrite to attenuate inorganic pollutants, especially when they form complex ions, is superior to that of Na-bentonite. Consequently, the mixing of such oxide minerals with Na-bentonite will reinforce the function of Na-bentonite, especially in the undergroud liner aspect.

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A Compilation and Evaluation of Thermal and Mechanical Properties of Bentonite-based Buffer Materials for a High- level Waste Repository

  • Cho, Won-Jin;Lee, Jae-Owan;Kang, Chul-Hyung
    • Nuclear Engineering and Technology
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    • v.34 no.1
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    • pp.90-103
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    • 2002
  • The thermal and mechanical properties of compacted bentonite and bentonite-sand mixture were collected from the literatures and compiled. The thermal conductivity of bentonite is found to increase almost linearly with increasing dry density and water content of the bentonite. The specific heat can also be expressed as a function of water ontent, and the coefficient of thermal expansion is almost independent on the dry density. The logarithm of unconfined compressive strength and Young’s modulus of elasticity increase linearly with increasing dry density, and in the case of constant dry density, it can be fitted to a second order polynomial of water content. Also the unconfined compressive strength and Young’s modulus of elasticity of the bentonite-sand mixture decreases with increasing sand content. The Poisson’s ratio remains constant at the dry density higher than 1.6 Mg/m$_3$, and the shear strength increases with increasing dry density.

A Study on Stress-Strain Characteristics of Compacted Bentonite for High-Level Radioactive Waste Repository (고준위폐기물 차폐용 압축벤토나이트의 응력-변형률 거동 분석)

  • Kim, Do-Hyun;Jeong, Sang-Seom
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.792-797
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    • 2009
  • The stress-strain characteristics of compacted bentonite are investigated using experimental triaxial compression test by Hoek-cell. Special attention given to various dry density and water absorption ratio. Based on the test results, it is shown that the stress-strain relationship of compacted bentonite is highly influenced by dry density and water absorption ratio. Also, characteristics of Bentonite is similar to the clay rather than sand. Strength of compressed Bentonite increases with higher dry density. It shows maximum strength value, if in a same condition with dry density and constrain pressure. So we determine that value as the optimistic moisture contents for the maximun strength of compressed Bentonite.

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A Study on Thermal Conductivity Properties of Ground Heat Exchangers for GSHP systems (지열냉난방시스템 수직형 지중열교환기 그라우트의 열적 특성에 관한 연구)

  • Baek, Sung-Kwon;Jeon, Joong-Kyu;An, Hyung-Jun
    • Proceedings of the SAREK Conference
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    • pp.429-433
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    • 2007
  • Cement mortar and concrete can be used as grouts but problems regarding shrinkage and the discord of coefficients of thermal expansion between grouts and HDPE pipes has to be solved. Thermal conductivities of wet condition two times larger than those of dry condition, except for pure cement mortar. The addition of sand into the cement grouts greatly increases the thermal conductivity. The addition of bentonite into the cement grouts reduces thermal conductivity thus reducing the density. Bentonite grouting must be used only below the groundwater table since bentonite grouts possesses high shrinkage property in dry condition. The addition of sand prevents the shrinkage of bentonite grouts. Bentonite manufactured in Korea can be used since they possess similar thermal conductivities with imported products. The addition of sand into the bentonite grouts greatly increases the thermal conductivity.

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Remediation of PCE-contaminated Groundwater Using Permeable Reactive Barrier System with M0M-Bentonite (MOM-Bentonite 투수성반응벽체를 이용한 PCE로 오염된 지하수의 정화)

  • Chung, Sung-Lae;Lee, Dal-Heui
    • Journal of Soil and Groundwater Environment
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    • v.17 no.4
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    • pp.73-80
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    • 2012
  • The objectives of this research were to study the applicability and limitations of permeable reactive barrier (PRB) for the removal of tetrachloroethylene (PCE) from the groundwater. PRB column tests were conducted using reactive material with Moringa Oleifera Mass - Bentonite (Mom-Bentonite). Most of the PCE in the groundwater was degraded and/or captured (sorpted) in the zone containing activated material (MOM-Bentonite). The removal rate of PCE from the groundwater was 90% and 75% after 30 days and 180 days, respectively. The effect of micro-organisms on the long-term permeability and reactivity of the barrier is not well understood. MOM-Bentonite PRB system in this research has the potential to be developed into an environmentally and economically acceptable technology for the in situ remediation of PCE-contaminated groundwater.

The Purification Characteristics of the Reactive Soil-Bentonite Landfill Liner (혼합반응차수재의 오염정화특성 연구)

  • 장경준;황의석;안기봉;김학문
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.585-592
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    • 2003
  • The purpose of this paper is to investigate purification characteristic of soil-bentonite landfill liner and to develop of desirable liner system. In this study, column tests for soil-bentonite, reactive soil-bentonite and existing bentomat and reactive bentomat were carried out under the high pressure with water and leachate.

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Thermal Conductivity of Compacted Bentonite and Bentonite-Sand Mixture (압축 벤토나이트 및 벤토나이트-모래 혼합물의 열전도도)

  • Cho, Won-Jin;Lee, Jae-Owan;Kwon, Sang-Ki
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.6 no.2
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    • pp.101-109
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    • 2008
  • For the Kyungju bentonite which is considered as a candidate material for the buffer and backfill in the high-level waste repository, the thermal conductivities of compacted bentonite and a bentonite-sand mixture were measured. The thermal conductivities of the compacted bentonites with a dry density of 1.2 to $1.8\;Mg/m^3$ and the bentonite-sand mixture with a dry density of 1.6 and $1.8\;Mg/m^3$ were measured within the gravimetric water content range of 10wt% to 20wt% and the sand fraction range of 10 to 30wt%. The thermal conductivity of compacted bentonite and a bentonite-sand mixture increases with increasing dry density and sand weight fraction in the case of constant water weight fraction, and increases with increasing water weight fraction and sand weight fraction in the case of constant dry density. The empirical correlations to describe the thermal conductivity of compacted bentonite and a bentonite-sand mixture as a function of water fraction at each dry density were suggested. These correlations can predict the thermal conductivities of bentonite and a bentonite-sand mixture with a difference below 10%.

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An Experimental Study on the Pozzolan Reaction of discarded Bentonite by Heat Treatment Condition - Focused on discarded Bentonite by cooling using of Water - (소성조건에 따른 폐 벤토나이트의 포졸란 반응성에 관한 실험적 연구 - 주수냉각을 중심으로 -)

  • 장진봉;정민수;김효열;강병희
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.85-90
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    • 2002
  • This study aims to propose a fundamental report for pozzolan reaction of discarded Bentonite by heat-treatment as concrete mineral admixture. As discarded bentonite is clay mineral to contain a great quantity a lot of $SiO_2$ and $Al_{2}O_{3}$, it is anticipated to reveal pozzolan reaction ability by heat-treatment. To find out pozzolan reaction ability of discarded Bentonite slurry by heat-treatment, the experiment is excuted Phenolphtalein test, setting test, pH test and the analysis by X-ray diffractor. As a result of this study, discarded Bentonite slurry can be utilized as concrete mineral admixture by heat-treatment and especially, pozzolan reaction ability of discarded Bentonite slurry is superior to the situation of 50$0^{\circ}C$~$700^{\circ}C$, 60min.

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Thermal conductivity and viscosity of graphite-added bentonite grout for backfilling ground heat exchanger (지중 열교환기용 뒤채움재로서 흑연을 첨가한 벤토나이트 그라우트재의 열전도도 및 점도 특성)

  • Lee, Chul-Ho;Lee, Kang-Ja;Choi, Hang-Seok;Choi, Hyo-Pum
    • Transactions of the Korea Society of Geothermal Energy Engineers
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    • v.5 no.1
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    • pp.19-24
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    • 2009
  • Bentonite-based grouting has been usually used for sealing a borehole installed for a closed-loop vertical ground heat exchanger in a geothermal heat pump system (GHP) because of its high swelling potential and low hydraulic conductivity. The bentonite-based grout, however, has relatively lower thermal conductivity than that of ground formation. Accordingly, it is common to add some additives such as silica sand into the bentonite-based grout for enhancing heat transfer. In this study, graphite is adapted to substitute silica sand as an addictive because graphite has very high thermal conductivity. The effect of graphite on the thermal conductivity of bentonite-based grouts has been quantitatively evaluated for seven bentonite grouts from different product sources. In addition, the viscosity of graphite-added bentonite grout was measured to evaluate the field pumpability of the grout.

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Mechanical Properties of Bentonite-Polyethylene Composites (Bentonite와 폴리에틸렌을 이용한 復合材의 機械的 性質)

  • Moon Tak Jin;Han Ki Chul
    • Journal of the Korean Chemical Society
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    • v.21 no.5
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    • pp.379-383
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    • 1977
  • Since the organophilic bentonite disperses well in polymer matrix, a composite material of polymer and bentonite was studied for its mechanical properties. To increase the degree of dispersion and the bond in forces to the polymer matrix, bentonite, encapsulated by imidazoline, was used as a filler. Polyethylene powder of particle size of 100 mesh was used, and organophilic bentonite, so-called bentone, whose particle size was 250 mesh was also used in this experiment. V-type mixer was used for mixing and Banbury mixer was used for melt-blending. The sample specimen were made by heating the mixture in the plate press, and the specimen were formed as a sheet, exactly the same as the mold on the plate. Tensile strength, bending strength and compressive strength were studied specially. Tensile strength, elongation rate, bending strength and bending rate at constant pressure were decreased as the filler content increased. Compressive strength was increased as the filler content increased.

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