• Title/Summary/Keyword: Bentonite

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HDTMA-Bentonite로부터 페놀류 화합물의 경쟁탈착

  • 신원식;김영규;송동익
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • pp.15-18
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    • 2001
  • Sorption/desorption studies were conducted to determine sorption/desorption characteristics of phenolic compounds (phenol and 4-chlorophenol) in organically modified natural bentonite. The cationic exchange capacity (CEC) of bentonite was exchanged with a cationic surfactant, hexadecyltrimethylammonium (HDTMA), to enhance the removal capacity of organic phenol contaminants dissolved in aqueous solution. This modification produces a change of the surface property of bentonite from hydrophilic to organophilic. The single-solute and bi-solute competitive adsorptions were performed In batch mode to investigate the removal of two toxic organic Phenols, chlorophenol and 4-chlorophenol on the HDTMA-bentonite. The adsorption affinity of the 4-chlorophenol was higher than phenol due to higher octanol:water partition coefficient (Kow). The single-solute and bi-solute competitive desorptions were also performed investigate the competitive desorption of the phenolic compounds from HDTMA-bentonite. Freundlich model was used to analyze the single-solute adsorption/desorption results, while the IAST model predicted the hi-solute adsorption/desorption equilibria. The IAST model well predicted hi-solute competitive adsorption/desorption behaviors.

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A Case Study on the Quality Control of Soil-Bentonite Admixed Liner (흙-벤토나이트 혼합 차수재의 품질관리 사례연구)

  • 정하익;이용수;홍승서;정길수;이회준
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.497-504
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    • 1999
  • This study presents the physical and engineering characteristics of soil-bentonite admixed liner in I landfill. Main focus was the hydraulic conductivity of compacted soil-bentonite admixed and mechanisms governing low permeable properties of the admixed liner. Laboratory and field tests such as compaction, hydraulic conductivity, density, water content for the soil-bentonite admixed liner were carried out. Quality control criteria for the best construction of the soil-bentonite admixed liner was suggested through laboratory and field test results.

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The Purification Characteristics of Reactive Soil-Bentonite Landfill Liner (혼합반응 차수재의 오염정화특성)

  • 김학문
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.4 no.4
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    • pp.398-403
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    • 2003
  • The purpose of this paper is to investigate purification characteristic of soil-bentonite landfill liner and to develop a desirable liner system. In order to clarify the purification characteristics, high pressure column tests using soil-bentonite, reactive soil-bentonite and reactive bentomat were carried out in the presence of water and leachate. The test results indicated that the significant amount of NH$_3$-N, Pb and Cu was removed through the reactive soil-bentonite liner system.

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Strength and Permeability Characteristics of Soil-Bentonite Mixture (Soil-Bentonite 혼합토의 강도 및 투수 특성)

  • Jin, Guangri;Im, Eunsang;Kim, Kiyoung;Sin, Donghoon
    • Journal of the Korean GEO-environmental Society
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    • v.11 no.4
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    • pp.5-12
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    • 2010
  • Soil mixture using bentonite as a cutoff material is used a lot for various structures such as landfills, banks and dams as cutoff materials. But seepage water is expected to seep since shear failure of filter layer occurs due to external load, embankment load when constructed. Generally, only coefficient of permeability of Soil Mixture is considered irrespective of the changes of intensity on amount of additives. This research is to study on how the changes of amount of bentonite affects permeability and strength of soil mixture. So successive experiments for measuring permeability and strength were conducted as the amount of bentonite changes from 0 to 4%, mixing with the bed material and then making specimens. Around construction site of B dam. As a result, 2.085E-07 cm/sec was shown when the amount of Soil Mixture was 4%. It is proved that unconfined compressive strength and tensile strength increase as the amount of bentonite increases, but saturation shear strength of bentonite soil mixture from the CD experiment is hardly influenced by the amount of bentonite.

A Study on Unsaturated Permeable Properties of the Soil-Bentonite Mixtures (Soil-Bentonite 혼합토의 불포화 투수특성 연구)

  • Kim Man-il
    • The Journal of Engineering Geology
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    • v.15 no.2
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    • pp.123-132
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    • 2005
  • This study presents the results of a laboratory investigation performed to study physical properties of soil-bentonite mixtures through the vertical permeation test and dielectric measurement test using Frequency Domain Reflectometry system for the liner of waste landfill. For the laboratory experiments, geotechnical testing was conducted on pre-mixed soil-bentonite which is consisted of standard sand, weathered granite soil and bentonite for estimating physical parameters such as a volumetric water content, void ratio and dielectric constant. In experiment results, initial soil-bentonite mixing rate has an effect of change of volumetric water content. Also change of volumetric water content of a soil-bentonite mixture is clearly detected to measure a response of dielectric constant. In order to estimate an unsaturated permeable property of soil-bentonite mixtures, equations between volumetric water content and dielectric constant were derived from this study.

A Study for Permeability as Mixing Ratio at Bentonite-mixed Soil (벤토나이트 혼합토의 혼합비에 따른 투수성 연구)

  • Ju Jae-Woo;Suh Kyeh-Won;Park Jong-Beom
    • Journal of the Korean Geotechnical Society
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    • v.22 no.1
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    • pp.45-52
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    • 2006
  • A theoretical equation, from which we can get a suitable ratio of bentonite at bentonite-mixed soil, was derived for desigri of the impermeable condition. Bentonite is a soil with great expansion property and it has the permeability lower than $1\times10^{-7}cm/sec$ in spite of its maximum expansion state. Accordingly if the void of soil is filled with the liquid of bentonite, water will flow only through the veid of bentonite liquid. And the permeability of bentonite-mixed soil will always satisfy the condition as impermeable zone. However, because it is very difficult to mix uniformly bentonite with soil, it is thought that the actual mixing ratio fur the impermeable zone will be grater than that by theoretical equation. Permeability tests were performed to check the equation and a modified equation was suggested from the experimental results.

Applicability of Electrical Conductivity Monitoring Technique for Soil-bentonite Barrier (흙-벤토나이트월에 대한 전기전도도 모니터링 기법의 적용성 평가)

  • Oh, Myoung-Hak;Yoo, Dong-Ju;Kim, Yong-Sung;Park, Jun-Boum
    • Journal of the Korean Geotechnical Society
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    • v.23 no.7
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    • pp.47-55
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    • 2007
  • In this study, applicability of electrical conductivity monitoring technique for containment barrier such as soil-bentonite wall was evaluated. Laboratory tests including permeability tests and column tests were performed to understand variations in electrical conductivity at different bentonite contents, hydraulic conductivities, and heavy metal concentrations. The electrical conductivity of compacted soil-bentonite mixtures was found to increase proportionally with bentonite content. Accordingly, the hydraulic conductivity of compacted soil-bentonite mixtures which decreases linearly with increasing bentonite content was found to have an inversely proportional relationship with the electrical conductivity. In column tests, electrical conductivity breakthrough curves and concentration breakthrough curves were simultaneously obtained. These results indicated that electrical conductivity measurement can be an effective means of detecting heavy metal transport at the desired locations within barriers and verifying possible contaminant leakage. Experimental results obtained from this study showed that the electrical conductivity measurement can be a promising tool for monitoring of containment barrier.

Conceptual Modeling Coupled Thermal-Hydrological-Chemical Processes in Bentonite Buffer for High-Level Nuclear Waste Repository (고준위 방사성폐기물 처분장에서 벤토나이트 완충제에 대한 열-수리-화학 작용 개념 모델링)

  • Choi, Byoung-Young;Ryu, Ji-Hun;Park, Jinyoung
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.14 no.1
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    • pp.1-9
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    • 2016
  • In this study, thermal-hydrological-chemical modeling for the alteration of a bentonite buffer is carried out using a simulation code TOUGHREACT. The modeling results show that the water saturation of bentonite steadily increases and finally the bentonite is fully saturated after 10 years. In addition, the temperature rapidly increases and stabilizes after 0.5 year, exhibiting a constant thermal gradient as a function of distance from the copper tube. The change of thermal-hydrological conditions mainly results in the alteration of anhydrite and calcite. Anhydrite and calcite are dissolved along with the inflow of groundwater. They then tend to precipitate in the vicinity of the copper tube due to its high temperature. This behavior induces a slight decrease in porosity and permeability of bentonite near the copper tube. Furthermore, this study finds that the diffusion coefficient can significantly affect the alteration of anhydrite and calcite, which causes changes in the hydrological properties of bentonite such as porosity and permeability. This study may facilitate the safety assessment of high-level radioactive waste repositories.

The Compatibility of Slurry Wall Materials with Leachate for Cut -off of Contaminated Sites (오염지역 차폐용 슬러리월 재료와 침출수의 반응 특성)

  • 이용수;정하익
    • Geotechnical Engineering
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    • v.13 no.2
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    • pp.9-16
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    • 1997
  • Cut-off methods of controlling leachate migration from waste landfills and contaminated sites are studied. Permeability and chemical compatibility tests are prrforlned on slurry wall materials including soil-bentonite, cement-bentonite, cement / fly ash-bentonite, plastic concrete. Hydraulic conductivity of soil-bentonite mixture is the lowest of these four bacuill materials. The leachate from municipal solid waste has little influence on the permeability of the backfill materials. The bentonite slurry becomes flocculated and aggregated when exposed to the leachate. The results of the permeability test showed that the hydraulic conductivities of the backfill materials are in the order soil-beiltonite, Plastic concrete, cement-bentonite. And the result c: the compatibility test showed increase in permeability due to the effects of leachate. Thus, in designing the slurry wall it is essential to check the behaviour of the bentonite slurry and backfill materials on the compatibility with the contaminants.

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