Viscosity and dielectric constant controls on the hydraulic conductivity of clayey soils permeated with water-soluble organics

1988 ◽  
Vol 25 (3) ◽  
pp. 582-589 ◽  
Author(s):  
F. Fernandez ◽  
R. M. Quigley
Keyword(s):  
Dielectric Constant ◽  
Hydraulic Conductivity ◽  
Double Layer ◽  
Pore Space ◽  
Water Soluble ◽  
Organic Liquids ◽  
Clayey Soils ◽  
Compacted Clay ◽  
High Concentrations ◽  
Water Saturated

Water-soluble organic liquids may, under some circumstances, dramatically increase the hydraulic conductivity, k, of water-saturated clayey soils, thus destroying their effectiveness as barriers for contaminants. Double-layer contraction at constant void ratio with resultant increases in the pore space available for flow has been identified as a primary mechanism for such increases in k. This paper shows, however, that the increased viscosity of solutions of some organics in water results in significant decreases in k.Pure alcohols (ethanol and methanol) and other water solubles (dioxane) when permeated through water-compacted clay samples produce an initial decrease in k, followed by a gradual increase to equilibrium values. The "hydrocarbon" front raises the viscosity of the pore fluid and causes an initial drop in k. Tests using aqueous solutions of ethanol and dioxane show decreases in k at concentrations up to ~70%. Only at high concentrations does the dielectric constant, double-layer effect overcome the viscosity effect and produce net increases in k.Effective stresses σ′vof 160 kPa during permeation with ethanol and dioxane prevent the increases in k. Physicochemically induced consolidation and increased K0-shearing effects that close shrinkage cracks are operative. Key words: hydraulic conductivity, liquid hydrocarbons, clay, viscosity, dielectric constant.

Hydraulic conductivity of natural clays permeated with simple liquid hydrocarbons

1985 ◽  
Vol 22 (2) ◽  
pp. 205-214 ◽  
Author(s):  
Federico Fernandez ◽  
Robert M. Quigley
Keyword(s):  
Dielectric Constant ◽  
Hydraulic Conductivity ◽  
Pore Water ◽  
Void Ratio ◽  
Pore Space ◽  
Water Soluble ◽  
Low Dielectric Constant ◽  
Simple Liquid ◽  
Liquid Hydrocarbons ◽  
Low Dielectric

The hydraulic conductivity, k, of clayey soils is strongly influenced by the physicochemical properties of permeating liquid hydrocarbons. Tests on natural Sarnia soils mixed with pure liquids at a void ratio of 0.8 yielded k values that increased from 5 × 10−9 to 1 × 10−4 cm/s as the dielectric constant of the permeant decreased from 80 to 2.Sequential permeation of compacted, water-wet samples (k ≈ 10−8 cm/s) showed no changes in hydraulic conductivity when permeated with water-insoluble hydrocarbons of low dielectric constant (benzene, cyclohexane, xylene). These hydrophobic liquids were forced through microchannels or macropores and displaced less than 10% of the pore water from samples at a void ratio of unity.Permeation with water-soluble alcohols resulted in extensive removal of the pore water and up to 10-fold increases in k. Subsequent permeation with liquid aromatics of very low dielectric constant resulted in 1000-fold increases in k with only 30% of the pore space occupied by the aromatics. Association liquids such as alcohol that are mutually soluble in water and the aromatics seem to be required to initiate huge increases in k over testing periods of short duration. Key words: hydraulic conductivity, liquid hydrocarbons, clay barriers, dielectric constant.

Comparative Analysis of Soluble Phosphate Amendments for the Remediation of Heavy Metal Contaminants: Effect on Sediment Hydraulic Conductivity

2006 ◽  
Vol 3 (3) ◽  
pp. 219 ◽  
Author(s):  
Dawn M. Wellman ◽  
Jonathan P. Icenhower ◽  
Antoinette T. Owen
Keyword(s):  
United States ◽  
Hydraulic Conductivity ◽  
Pore Structure ◽  
Pore Space ◽  
The United States ◽  
Water Soluble ◽  
Department Of Energy ◽  
United States Department ◽  
Soluble Phosphate ◽  
Long Chain

Environmental Context. The contamination of surface and subsurface geologic media by heavy metals and radionuclides is a significant problem within the United States Department of Energy complex as a result of past nuclear operations. Water-soluble phosphate compounds provide a means to inject phosphorus into subsurface contaminant plumes, to precipitate metal ions from solution. However, phosphate phases can form within the sedimentary pore structure to block a fraction of the pore space and inhibit further remediation of the contaminant plume. A series of tests have been conducted to evaluate changes in sedimentary pore structure during the application of several proposed phosphate remediation amendments. Abstract. A series of conventional, saturated column experiments have been conducted to evaluate the effect of utilizing in situ, soluble, phosphate amendments for subsurface metal remediation on sediment hydraulic conductivity. Experiments have been conducted under mildly alkaline and calcareous conditions representative of conditions commonly encountered at sites across the arid western United States, which have been used in weapons and fuel production and display significant subsurface contamination. Results indicate that the displacement of a single pore volume of either sodium monophosphate or phytic acid amendments causes approximately a 30% decrease in the hydraulic conductivity of the sediment. Long-chain polyphosphate amendments afford no measurable reduction in hydraulic conductivity. These results demonstrate (1) the efficacy of long-chain polyphosphate amendments for subsurface metal sequestration; and (2) the necessity of conducting dynamic experiments to evaluate the effects of subsurface remediation.

scholarly journals Variation of the Hydraulic Conductivity of Clayey Soils in Exposure to Organic Permeants

2017 ◽  
Vol 3 (11) ◽  
pp. 1036 ◽  
Author(s):  
Hanane Mortezaei ◽  
Mehran Karimpour Fard
Keyword(s):  
Dielectric Constant ◽  
Water Content ◽  
Double Layer ◽  
Clayey Soils ◽  
Contamination Control ◽  
Clay Particles ◽  
Soil Plasticity ◽  
Low Dielectric ◽  
Constant Head ◽  
Constant Head Method

Clayey soils are the most common material used in waterproofing and play an essential role in waste and contamination control. Permeability is a key parameter in such problems and its determination is needed in ensuring the satisfactory performance of the soil. Research has shown that a permeant fluid with a low dielectric constant can shrink the double layer around the clay particles which will, in turn, increase the permeability of the soil. In this paper, the permeability of two types of clay with different plasticity, exposed to the flow of water and methanol as polar and miscible solvents and gasoline and car oil as non-polar and immiscible solvents is investigated. In addition, the effect of soil properties such as plasticity and compaction water content on permeability of the samples is examined. To this end, soil samples are prepared and compacted at various water contents. Then, permeability tests are conducted according to the modified constant head method and the effects of parameters such as the fluid dielectric constant, water content of the samples and soil plasticity are examined. The results demonstrate that the lower dielectric constant of the organic fluid decreases the thickness of the double layer, providing more space for the flow of the permeant and as a result, the permeability of the clay increases. The reduction of the permeant dielectric constant from 80.4 to 2.28 led to a remarkable increase in soil permeability.

Controlling the destructive effects of clay – organic liquid interactions, by application of effective stresses

1991 ◽  
Vol 28 (3) ◽  
pp. 388-398 ◽  
Author(s):  
Federico Fernandez ◽  
Robert M. Quigley
Keyword(s):  
Hydraulic Conductivity ◽  
Effective Stress ◽  
Organic Liquid ◽  
Critical Role ◽  
Water Soluble ◽  
Practical Significance ◽  
Organic Liquids ◽  
Effective Stresses ◽  
Chemically Induced ◽  
Clay Barrier

The magnitude of the effective stresses acting on a clay barrier appear to play a critical role in preserving low hydraulic conductivity, k, during exposure to soluble organic liquids. This paper summarizes the results of a research study on a natural clay from southwestern Ontario permeated with various mixtures of landfill leachate and water-soluble organic liquids at effective stresses ranging from 0 to ~300 kPa. Laboratory testing of "unconfined", water-compacted clays indicated that municipal solid waste leachates containing ethanol and dioxane at concentrations in excess of 70% can cause damaging increases in k of up to 1000-fold. Predamage application of vertical effective stresses can reduce or even eliminate these increases in k because of chemically induced consolidation and closure of macropores that develop as a result of double layer collapse. The levels of static effective stress required to prevent the increases in k were much higher for nonpolar dioxane (> 160 kPa) than for intermediately polar ethanol (20–40 kPa). Postdamage application of static effective stresses successfully eliminated the increases in k produced by ethanol permeation at near zero stress but could not heal the clay damaged by permeation of nonpolar dioxane. The practical significance of this work is discussed relative to clay barrier design. Key words: hydraulic conductivity, clay, organic liquids, leachate, liner, effective stress healing.

Influence of changes in methanol concentration on clay particle interactions

1989 ◽  
Vol 26 (1) ◽  
pp. 57-63 ◽  
Author(s):  
John M. E. Storey ◽  
J. Jeffrey Peirce
Keyword(s):  
Hydraulic Conductivity ◽  
Clay Particle ◽  
Methanol Concentration ◽  
Atterberg Limits ◽  
Organic Liquids ◽  
Compacted Clay ◽  
Particle Settling ◽  
Liner Material ◽  
Clay Particles ◽  
Alcohol Water

The interactions of clay particles with alcohol–water mixtures are investigated with hydraulic conductivity measurements, the electrophoretic mobilities of the suspended particles are measured, particle settling tests are carried out, and Atterberg limits are determined. Organic liquids frequently interact with clay particles in the clay liners of surface impoundments. Such fluids can cause changes in hydraulic conductivity of the liner material. This study looks at the effects of dilution of a liquid hydrocarbon with water on the properties of a clay soil. Tests with 20, 40, 60, 80, and 100% (by volume) methanol concentrations are used to investigate the changes in hydraulic conductivity of water-compacted clay samples. Particle settling tests, Atterberg limits, and electrophoretic mobility studies are used with the same concentrations to determine the effects of changing methanol concentration on clay particle behavior. The results indicate that higher concentrations of methanol cause an increase in the attraction between the clay particles, and the same concentrations also cause an increase in hydraulic conductivity. Key words: Atterberg limits, clay, electrophoresis, hydraulic conductivity, methanol, settling tests, zeta potential.

scholarly journals Hydraulic and Swell–Shrink Characteristics of Clay and Recycled Zeolite Mixtures for Liner Construction in Sustainable Waste Landfill

2021 ◽  
Vol 13 (13) ◽  
pp. 7301
Author(s):  
Marcin K. Widomski ◽  
Anna Musz-Pomorska ◽  
Wojciech Franus
Keyword(s):  
Hydraulic Conductivity ◽  
Exchange Capacity ◽  
Saturated Hydraulic Conductivity ◽  
Clay Soils ◽  
Compacted Clay ◽  
Clay Liner ◽  
Compacted Clay Liner ◽  
Drying And Rewetting ◽  
Swelling Characteristics ◽  
Shrinkage And Swelling

This paper presents research considering hydraulic as well as swelling and shrinkage characteristics of potential recycled fine particle materials for compacted clay liner for sustainable landfills. Five locally available clay soils mixed with 10% (by mass) of NaP1 recycled zeolite were tested. The performed analysis was based on determined plasticity, cation exchange capacity, coefficient of saturated hydraulic conductivity after compaction, several shrinkage and swelling characteristics as well as, finally, saturated hydraulic conductivity after three cycles of drying and rewetting of tested specimens and the reference samples. The obtained results showed that addition of zeolite to clay soils allowed reduction in their saturated hydraulic conductivity to meet the required threshold (≤1 × 10−9 m/s) of sealing capabilities for compacted clay liner. On the other hand, an increase in plasticity, swelling, and in several cases in shrinkage, of the clay–zeolite mixture was observed. Finally, none of the tested mixtures was able to sustain its sealing capabilities after three cycles of drying and rewetting. Thus, the studied clayey soils mixed with sustainable recycled zeolite were assessed as promising materials for compacted liner construction. However, the liner should be operated carefully to avoid extensive dissication and cracking.

scholarly journals NMR Structure and Action on Nicotinic Acetylcholine Receptors of Water-soluble Domain of Human LYNX1

2011 ◽  
Vol 286 (12) ◽  
pp. 10618-10627 ◽  
Author(s):  
Ekaterina N. Lyukmanova ◽  
Zakhar O. Shenkarev ◽  
Mikhail A. Shulepko ◽  
Konstantin S. Mineev ◽  
Dieter D'Hoedt ◽  
...  
Keyword(s):  
Nicotinic Acetylcholine Receptors ◽  
Acetylcholine Receptors ◽  
Nmr Structure ◽  
Water Soluble ◽  
Gpi Anchor ◽  
Nicotinic Acetylcholine ◽  
Brain Functions ◽  
The Central Nervous System ◽  
High Concentrations

Discovery of proteins expressed in the central nervous system sharing the three-finger structure with snake α-neurotoxins provoked much interest to their role in brain functions. Prototoxin LYNX1, having homology both to Ly6 proteins and three-finger neurotoxins, is the first identified member of this family membrane-tethered by a GPI anchor, which considerably complicates in vitro studies. We report for the first time the NMR spatial structure for the water-soluble domain of human LYNX1 lacking a GPI anchor (ws-LYNX1) and its concentration-dependent activity on nicotinic acetylcholine receptors (nAChRs). At 5–30 μm, ws-LYNX1 competed with 125I-α-bungarotoxin for binding to the acetylcholine-binding proteins (AChBPs) and to Torpedo nAChR. Exposure of Xenopus oocytes expressing α7 nAChRs to 1 μm ws-LYNX1 enhanced the response to acetylcholine, but no effect was detected on α4β2 and α3β2 nAChRs. Increasing ws-LYNX1 concentration to 10 μm caused a modest inhibition of these three nAChR subtypes. A common feature for ws-LYNX1 and LYNX1 is a decrease of nAChR sensitivity to high concentrations of acetylcholine. NMR and functional analysis both demonstrate that ws-LYNX1 is an appropriate model to shed light on the mechanism of LYNX1 action. Computer modeling, based on ws-LYNX1 NMR structure and AChBP x-ray structure, revealed a possible mode of ws-LYNX1 binding.

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