• Title, Summary, Keyword: Bentonite

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On Improvement of the Adsorption by Chemical Treatment on Yeong-Il Bentonite (영일산 Bentonite의 화학적 처리에 의한 흡착력 개선)

  • Kim Myun Sup
    • Journal of the Korean Chemical Society
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    • v.16 no.4
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    • pp.241-248
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    • 1972
  • The adsorption of Methylene Blue on Yeong-Il bentonite which was treated by aqueous NaOH, $Na_2SO_4 or NaHSO_4 solution respectively, varying concentrations, temperature and time, was studied. In case of treatment with NaHSO_4 solution, slight improvement of the adsorption of Methylene Blue on bentonite was observed. With Na_2SO_4$ solution, the best results obtained when bentonite was treated with 1 N of the solution for 2hr at $100^{\circ}C$, and the adsorption capacity of the product was 3 times better than that of original bentonite. At the higher concentration and the higher temperature than above, faujasite was formed. With NaOH solution, the best condition was in 1N solution for 1hr at $100^{\circ}C$ and the adsorption capacity of the product was 3.3 times better than that of original bentonite. At the higher concentration of the treating agent and at the higher temperature than above, hydroxysodalite was formed.

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Evaluation on Compression Wave Velocities and Moduli of Gyeongju Compacted Bentonite (경주 압축 벤토나이트의 압축파속도와 탄성계수 산정 연구)

  • Balagosa, Jebie;Yoon, Seok;Choo, Yun Wook
    • Journal of the Korean Geotechnical Society
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    • v.35 no.7
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    • pp.41-50
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    • 2019
  • Gyeongju bentonite is a buffer material primarily considered in Korea and it is highly compacted as a part of an engineered barrier system (EBS) of high-level radioactive waste repository. The compacted bentonite undergoes swelling stress by groundwater penetration and thermal stress by decay heat from a canister. Therefore, the mechanical properties of the compacted bentonite buffer material is crucial for the performance assessment of EBS. This paper aims to evaluate deformation properties of Gyeongju compacted bentonite using seismic methods. Two sets of compacted bentonite specimens were prepared having dry densities of $1.59g/cm^3$ and $1.75g/cm^3$ with water contents of 10.6% and 8.7%. Free-free resonant column tests were performed to measure constrained and unconstrained compression wave velocities. With the measured wave velocities, Young's modulus ($E_{max}$) and constrained modulus ($M_{max}$), material damping ratio ($D_{min}$), and Poisson's ratio at small strain were determined. As results, this paper evaluates the deformation properties of Gyeongju compacted bentonite and compares them with the results of previous researches.

Removal of Ammonia from Aqueous Solutions with Zeolite and Bentonite (제오라이트 및 벤토나이트에 의한 수용액중 암모니아의 제거)

  • 이화영;오종기;김성규;고현백
    • Journal of the Korean Institute of Resources Recycling
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    • v.11 no.3
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    • pp.3-9
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    • 2002
  • Relnoval of ammonia from aqueous solutions has been studied with zeolite and bentonite minerals. Zeolite and bentonite powder were supplied by a domestic company and used as delivered without further purification. The aqueous pH was found to increase by addition of zeolite or bentonite up to pH 8.5 from initial pH of 5.5∼5.7. From the C.E.C. measurement by ammonium acetate leaching method, the values of C.E.C. of zeolite and bentonite sample were observed to be 129.7 meq/100 gr and 65.1 meq/100 gr, respectively and Na+ ion accounted for the major part of total C.E.C. in both cases. In the removal of ammonia with zeolite and bentonite, physical adsorption of ammonium ion onto minerals was believed to contribute to the removal of it as well as the intrinsic cation exchange reaction. Finally, zeolite was found to be superior to bentonite in the removal of ammonia from aqueous solutions.

Short-term Sustained Release Formulation of KC-6620 with Porous Carrier (다공성 증량제를 이용한 KC-6620 단기용출지연입제의 제제)

  • Yu, Ju-Hyun;Park, Chang-Kyu;Lee, Byung-Hoi;Cho, Kwang-Yun
    • Korean Journal of Environmental Agriculture
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    • v.11 no.2
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    • pp.155-162
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    • 1992
  • In order to extend the releasing period of granular formulation to approximately 20 days, the KC-6620-adsorbed granules were formulated with carriers and polyethylene glycol as adjuvant. The releasing rates of active ingredient from the formulations were evaluated in aqueous medium. The baked bentonite was found most effective carrier to sustain the release of KC-6620. Due to, however, low releasing rate of active ingredient after 20 days, bentonite formulation appeared to be of no practical for the short-term sustained release of KC-6620. The increased pore volume of bentonite granular formulation by adding pyrophyllite increased remarkably the released amount of KC-6620 from bentonite-pyrophyllite(4 : 6) granule up to 85% of total active ingredient incorporated. Addition of polyethylene glycol to the bentonite-pyrophyllite granule further increased the releasing rate of KC-6620. With KC-6620 content in the bentonite-pyrophyllite(4 : 6) granule, the releasing rate of active ingredient was markedly reduced.

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Effect of Metal Ion on the Bentonite Modified with Cationic Surfactant (양이온성 계면활성제를 이용한 유기 벤토나이트의 합성시 금속 이온의 첨가 영향)

  • Kim, Soo-Hong;Park, Jae-Woo
    • Journal of The Korean Society of Civil Engineers
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    • v.26 no.6B
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    • pp.677-682
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    • 2006
  • Dodecyldimethylethylammonium (DDDEA), a cationic surfactant, and aluminum metal ions were used with bentonite to synthesize to synthesize an improved organo bentonite. Among three different synthesis procedure for organo bentonites, aluminium-pillared bentonite showed the highest DDDEA sorption, which indicated that aluminium-pillared organo bentonite would exhibit the highest sorption capacity for organic contaminants. Aluminium pillared organo bentonite also showed a high sorption capability for phosphorus, while it did not exhibit strong sorption for nitrate. In the meantime, more desorption was observed with aluminium-pillared organo bentonite than ordinary organo bentonites.

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Thermal-hydro-mechanical Properties of Reference Bentonite Buffer for a Korean HLW Repository (우리나라 고준위폐기물처분장 기준벤토나이트완충재의 열-수리-역학적 특성치)

  • Lee, Jae-Owan;Cho, Won-Jin;Kwon, Sang-Ki
    • Tunnel and Underground Space
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    • v.21 no.4
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    • pp.264-273
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    • 2011
  • Bentonite buffer is one of the major components of an engineered barrier for an HLW (High-Level Waste) repository. The bentonite buffer is significantly exposed to the decay heat from radioactive wastes, the inflow of groundwater from the surrounding rock of the repository, and the high swelling pressure of densely-compacted bentonite that comes in contact with the groundwater. Therefore, it is essential to understand the THM (Thermal-Hydro-Mechanical) behavior of the bentonite buffer and to acquire the input data of its related constitutive models for the performance and safety assessment of an HLW repository. This paper analyzed the THM properties which have been obtained by conducting laboratory tests with a candidate buffer material for a Korean HLW repository. Moreover the formulation recipe of the reference bentonite buffer was defined on the basis of functional criteria, thus suggesting the THM properties which correspond to the formulation recipe of the reference bentonite buffer.

Hybrid Barriers of Iron and Modified-bentonite for the Remediation of Multi-contaminated Water (복합오염물질 제거를 위한 철과 개량 벤토나이트의 복합층에 관한 연구)

  • Cho, Hyun-Hee;Park, Jae-Woo
    • Journal of Korean Society on Water Environment
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    • v.20 no.5
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    • pp.512-519
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    • 2004
  • Hybrid barriers using reduction and immobilization were tested to remediate the groundwater contaminated with multi-pollutants in this study. Iron filings and HDTMA(hexadecyltrimethylammonium)-bentonite were simulated in columns to assess the performance of hybrid barriers for remediation of trichloroethylene(TCE)-contaminated water. TCE reduction rate for the mixture of iron filings and HDTMA-bentonite was about 7 times higher than that for iron filings, only suggesting the reduction of TCE was accelerated when HDTMA-bentonite was mixed with iron filings. TCE reduction rate for the two layers of iron and HDTMA-bentonite was nearly similar to that for iron filings alone, but the partition coefficient($K_d$) for the two layers was 4.5 times higher than for that iron filings only. TCE was immobilized in the first layer with HDTMA-bentonite, and then dechlorinated in the second layer with iron filings. HDTMA-bentonite may contribute to the increase in TCE concentration on iron surface so that more TCE can be reduced. Also, TCE removal in the hybrid barriers was not affected by chromate and naphthalene while the reduction rate of TCE with the co-existing contaminants by iron filings was significantly decreased. Significant TCE removal in this research indicates that the proposed hybrid barrier system has the potential to become the effective remediation alternative during the occurrence of oil shock. Also, if subsurface environments are contaminated with multi-pollutants that contain non-reducible compounds as well as reducible compounds such as TCE, the conventional reactive barriers cannot be applied to this subsurface environment, while the proposed hybrid system can be applied successfully.

Chemical and Physical Influence Factors on Performance of Bentonite Grouts for Backfilling Ground Heat Exchanger (지중 열교환기용 벤토나이트 그라우트의 시공성에 대한 화학적, 물리적 영향 요소에 관한 연구)

  • Lee, Chul-Ho;Gil, Hu-Jeong;Lee, Kang-Ja;Choi, Hang-Seok;Choi, Hyo-Pum
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.1475-1486
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    • 2008
  • Bentonite-based grouting has been popularly used to seal a borehole installed for a closed-loop vertical ground heat exchanger in a geothermal heat pump system (GHP) because its high swelling potential. However, if the bentonite-based grouting is conducted in coastal areas, the salinity of groundwater changes in the mineral fabric of bentontie. In order words, an increase of cation concentration in groundwater leads to a reduction in the diffuse double-layer thickness in the bentonite mineral structure, and thus the volume of bentointe-based grouts will decrease proportional to the salinity of groundwater. In this paper, the effect of salinity (i.e., NaCl 0.5M, 0.25M, and 0.1M) on the change of swelling potential for bentonite-based grouts has been quantitatively evaluated for seven bentonite grouts from different product sources. In addition, in case of using addictives such as a silica sand to increase the thermal conductivity of bentonite-based grouts, the possibility of particle segregation has been studied considering the viscosity of grouts and salinity of groundwater.

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Existence and Characteristics of Microbial cells in the Bentonite to be used for a Buffer Material of High-Level Wastes (고준위폐기물 완충재로 사용되는 벤토나이트의 미생물의 존재 및 특성)

  • Lee, Ji Young;Lee, Seung Yeop;Baik, Min Hoon;Jeong, Jong Tae
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.11 no.2
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    • pp.95-102
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    • 2013
  • There was a study for biological characteristics, except for physico-chemical and mineralogical properties, on the natural bentonite that is considered as a buffer material for the high-level radioactive waste disposal site. A bentonite slurry that was prepared from a local 'Gyeongju bentonite' in Korea was incubated in a serum bottle with nutrient media over 1 week and its stepwise change was observed with time. From the activated bentonite in the nutrient media, we can find a certain change of both solid and liquid phases. Some dark and fine sulfides began to be generated from dissolved sulfate solution, and 4 species of sulfate-reducing bacteria (SRB) were identified as living cells in samples that were periodically taken and incubated. These results show that sulfate-reducing (or metal-reducing) bacteria are adhering and existing in the powder of bentonite, suggesting that there may be a potential occurrence of longterm biogeochemical effects in and around the bentonite buffer in underground anoxic environmental conditions.

Effect of slag and bentonite on shear strength parameters of sandy soil

  • Sabbar, Ayad Salih;Chegenizadeh, Amin;Nikraz, Hamid
    • Geomechanics and Engineering
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    • v.15 no.1
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    • pp.659-668
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    • 2018
  • A series of direct shear tests were implemented on three different types of specimens (i.e., clean Perth sand, sand containing 10, 20 and 30% bentonite, sand containing 1, 3 and 5% slag, and sand containing 10, 20 and 30% bentonite with increasing percentages of added slag (1%, 3% and 5%). This paper focuses on the shear stress characteristics of clean sand and sand mixtures. The samples were tested under different three normal stresses (100, 150 and 200 kPa) and three curing periods of no curing time, 7 and 14 days. It was observed that the shear stresses of clean sand and mixtures were increased with increasing normal stresses. In addition, the use of slag has improved the shear strength of the sand-slag mixtures; the shear stresses rose from 128.642 kPa in the clean sand at normal stress of 200 kPa to 146.89 kPa, 154 kPa and 161.14 kPa when sand was mixed with 1%, 3% and 5% slag respectively and tested at the same normal stress. Internal friction angle increased from $32.74^{\circ}$ in the clean sand to $34.87^{\circ}$, $37.12^{\circ}$ and $39.4^{\circ}$ when sand was mixed with 1%, 3% and 5% slag respectively and tested at 100, 150, and 200 kPa normal stresses. The cohesion of sand-bentonite mixtures increased from 3.34 kPa in 10% bentonite to 22.9 kPa, 70.6 kPa when sand was mixed with 20% and 30% bentonite respectively. All the mixtures of clean sand, different bentonite and slag contents showed different behaviour; some mixtures exhibited shear stress more than clean sand whereas others showed less than clean sand. The internal friction angle increased, and cohesion decreased with increasing curing time.