Characterization and hydraulic conductivity of tropical soils and bentonite mixtures for CCL purposes

Morandini, Thiago Luiz Coelho; Leite, Adilson do Lago

doi:10.1016/j.enggeo.2015.07.011

Cited by 31 publications

(30 citation statements)

References 34 publications

(32 reference statements)

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“…Mixtures using these soils and the commercial bentonite were manually composed. The sampling locations and preparation, as well as the mixing and characterization methods and results are fully reported by Morandini & Leite (2015a). Table 2 presents only the sample designations, including the bentonite proportions of the mixtures (dry weight basis), and Table 3 reprints a summary of the geotechnical and physicochemical properties as presented by Morandini & Leite (2015a).…”

Section: Summary Of the Sample Propertiesmentioning

confidence: 99%

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On the Compatibility and Theoretical Equations for Mixtures of Tropical Soils and Bentonite for Barrier Purposes

Morandini¹,

Leite²

2018

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Vast regions of the globe are covered by tropical soils, increasing the perspective of using them for barrier design at solid/liquid disposal facilities. They comprise diverse pedological taxonomies, but have common features, specially the dominant mineral composition of quartz, kaolinite clay and Fe-Al-Mn oxides/hydroxides. Despite the vast occurrence, sometimes tropical soil samples may not be suitable for barrier purposes, which can be overcome using bentonite as additive, provide that technical evaluations are adopted. An important technical issue to be addressed is the compatibility between the barrier materials and the liquids to be disposed. Compatibility studies usually involve laboratory testing using direct and indirect methods, which were involved in this research. The indirect studies involved modified Atterberg limits and the direct approach was developed using direct permeation. The tropical soil samples were selected to be in different weathering stages, considering the laterization degree. The chosen bentonite content to compose the mixtures was 3, 6, 9 and 12% on a dry weight basis. The elected chemical solutions for these studies were: calcium chloride (CaCl 2 ), nitric acid (HNO 3 ), sodium hydroxide (NaOH), ethanol (C 2 H 5 OH) and tap water. As a summary, the main research objectives were: (1) comparison between direct and indirect methods for compatibility evaluation; (2) assessment of the influence of the bentonite content on the compatibility of tropical soil samples; (3) investigation of the influence of the laterization degree on compatibility and (4) evaluation of theoretical equations to predict the compatibility of these samples through back analysis. The results indicate that: indirect and direct methods are similar from a qualitative point of view; bentonite is more sensitive to chemicals than the natural soil components; the laterization degree is not so influent on the compatibility and good compatibility predictions were obtained with the proposed theoretical equations.

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Section: Summary Of the Sample Propertiesmentioning

confidence: 99%

“…In these cases, the use of bentonite as admixture is interesting, considering the well-known ability of this clay to reduce hydraulic conductivity and increase sorption (e.g. Ebina et al, 2004;Akbulut & Saglamer, 2004;Osinubi & Nwaiwu, 2006;Osinubi et al, 2009;Morandini & Leite, 2013;Akcanca & Aytekin, 2014;Morandini & Leite, 2015a).…”

Section: Introductionmentioning

confidence: 99%

On the Compatibility and Theoretical Equations for Mixtures of Tropical Soils and Bentonite for Barrier Purposes

Morandini¹,

Leite²

2018

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“…However, often the tailings or soil with which the clay liners is in contact contains plentiful divalent (e.g., Ca 2+ and/or Mg 2+ ) and in some cases trivalent (e.g., Fe 3+ ) cations which, because the bentonite is mostly Na + bentonite, can exchange with the Na + in the bentonite. This cation exchange between di-and trivalent cations and Na + can significantly reduce the swell capacity of the bentonite and the double layer contraction can cause an increase in the hydraulic conductivity of the bentonite-sand layer (Kenney et al 1992;Kolstad et al 2004, Lee andShackelford 2005;Meer and Benson 2007;He et al 2015;Morandini and Leite 2015).…”

Section: Introductionmentioning

confidence: 97%

Performance of polymer-enhanced bentonite–sand mixture for covering arsenic-rich gold mine tailings for up to 4 years

Hosney

Rowe

2017

Can. Geotech. J.

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Experiments conducted over a 4-year period, on a polymer enhanced bentonite-sand mixture (PEBSM) used as cover for gold mine tailings are reported. The effect on PEBSM hydraulic conductivity (k) of subgrade porewater chemistry, subgrade water content, and confining stress are investigated. Results show that the reduction in the mole fraction of bound Na + (ESP) and corresponding increase in k of PEBSM with time was highly dependent on the ionic strength of the subgrade porewater. When the PEBSM was in direct contact with gold mine tailings with porewater having an ionic strength of 145 mM, ESP decreased from 59% to 2% and k increased from 4x10 -11 to 6.9x10 -9 m/s. The ESP and k values of PEBSM over tailings with 11 mM porewater were 21% and 6.9x10 -11 m/s. A 0.15-m-thick foundation layer between tailings and PEBSM layer significantly lowered the reduction in ESP and increase in k with time as did a reduction in the subgrade water content. There was no effect of changing confining stress from 15 to 7.5 kPa on k values of PEBSM. The PEBSM layer acted as a good barrier to the migration of arsenic from tailings upward towards cover soil above PEBSM layer.

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“…Natural bentonite is inexpensive material and largely available layer materials that have been widely used as a adsorbent material for many waste water pollutant due to its chemical and physical stability, high surface area, and high cation exchange capacity [7]. Natural bentonite is also available in large quantities and easily obtained in tropical country such as Indonesia [8]. Natural bentonite was largely used as effective adsorbent for several dyes such as congo red [9], methylene blue [10], procion red [2], basic red [11], reactive yellow [1], and also other acidic and basic dyes [12].…”

Section: Introductionmentioning

confidence: 99%

Adsorption of Procion Red on Natural Bentonite: Kinetic Studies

Taher¹,

Lesbani²

2016

sje

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Adsorption of procion red on natural bentonite was studied by kinetic study to know the reactivity of procion red. Kinetic adsorption was determined using batch adsorption system at various times in several concentrations of procion red. Time of adsorption was investigated at 5,10, 20, 30, 45, 60, 90, and 120 minutes in 10, 25, 50, and 75 mg/L of procion red. The data was calculated using Langmuir-Hinshelwood kinetic equation. The diffusions process of procion red into bentonite at lower concentration was faster than at higher concentration in general with fit correlation between [(ln(Co/C))/C] vs t/C from Langmuir-Hinshelwood data. The adsorption procion red on bentonite data at various times shows Langmuir monolayer adsorption process in the surface of bentonite. Keyword: adsorption, procion red, natural bentonite, kinetic Abstrak (Indonesian): Adsorpsi procion merah pada bentonit alam telah dipelajari melalui studi kinetik untuk mengetahui reaktivitas procion merah. Kinetika adsorpsi ditentukan menggunakan sistem adsorpsi simultan pada berbagai waktu dalam beberapa konsentrasi procion merah. Waktu adsorpsi dipelajari pada 5, 10, 20, 30, 45, 60, 90, dan 120 menit pada konsentrasi procion merah 10, 25, 50, dan 75 mg/L. Data dihitung menggunakan persamaan kinetika Langmuir-Hinshelwood. Proses difusi procion merah ke dalam bentonit pada konsentrasi rendah lebih cepat dibanding pada konsentrasi lebih tinggi secara umum dengan hubungan korelasi yang lurus antara [(ln(Co/C))/C] versus t/C dari data Langmuir-Hinshelwood. Adsorpsi procion merah pada bentonit dengan berbagai variasi waktu adsorpsi menunjukkan proses adsorpsi satu lapisan pada permukaan bentonit.

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Characterization and hydraulic conductivity of tropical soils and bentonite mixtures for CCL purposes

Cited by 31 publications

References 34 publications

On the Compatibility and Theoretical Equations for Mixtures of Tropical Soils and Bentonite for Barrier Purposes

On the Compatibility and Theoretical Equations for Mixtures of Tropical Soils and Bentonite for Barrier Purposes

Performance of polymer-enhanced bentonite–sand mixture for covering arsenic-rich gold mine tailings for up to 4 years

Adsorption of Procion Red on Natural Bentonite: Kinetic Studies

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