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WO2009020594A1 - Stabilisation de l'eau au moyen de microparticules - Google Patents

Stabilisation de l'eau au moyen de microparticules Download PDF

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Publication number
WO2009020594A1
WO2009020594A1 PCT/US2008/009398 US2008009398W WO2009020594A1 WO 2009020594 A1 WO2009020594 A1 WO 2009020594A1 US 2008009398 W US2008009398 W US 2008009398W WO 2009020594 A1 WO2009020594 A1 WO 2009020594A1
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WO
WIPO (PCT)
Prior art keywords
hydrophilic core
water
hydrophobic shell
hydrophilic
water stabilization
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US2008/009398
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English (en)
Inventor
David J. Elton
Ram B. Gupta
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Auburn University
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Auburn University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Auburn University filed Critical Auburn University
Publication of WO2009020594A1 publication Critical patent/WO2009020594A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
    • B09C—RECLAMATION OF CONTAMINATED SOIL
    • B09C1/00—Reclamation of contaminated soil
    • B09C1/002—Reclamation of contaminated soil involving in-situ ground water treatment
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K17/00—Soil-conditioning materials or soil-stabilising materials
    • C09K17/14—Soil-conditioning materials or soil-stabilising materials containing organic compounds only
    • C09K17/18—Prepolymers; Macromolecular compounds
    • C09K17/20—Vinyl polymers
    • C09K17/22—Polyacrylates; Polymethacrylates

Definitions

  • the present invention relates to the avoidance of soil liquefaction. More specifically, the present invention relates to a new, useful and non-obvious water stabilization particle and its use in preventing soil liquefaction, and other uses.
  • Maps of liquefaction susceptibility for metropolitan areas have been drawn by researchers in the U.S. and abroad (e.g., Kavazanjian et al. (1985), Liquefaction
  • hydrophilic particles such as hydrogel (a polymer), to immobilize pore water.
  • hydrogel a polymer
  • hydrophilic particles can alternatively or additionally be used.
  • Hydrogel turns pore water into an immobile, soft gel. Hydrogel doesn't flow or liquefy or break the way grout does when shaken. This solution performed very well in preliminary laboratory tests and represents a blend of high technology nanoscale chemistry, chemical engineering and civil engineering. Hydrogels absorb huge amounts of water (up to 240 times by weight), but do not dissolve in water. The absorbed water becomes immobile and acts as a very flexible solid (soft gel). Hydrogels do not change volume when hydrated and are environmentally benign, inexpensive, and readily available.
  • Hydrogels are widely used in baby diapers, contact lenses, and wound dressings for this purpose. Existing soil applications are waterproofing and water retention for agricultural purposes. However, current hydrogels have not addressed nor have they been made suitable for addressing the immobilization of porewater to avoid soil liquefaction. Installing hydrogel under the water table (e.g., under a building) will require special hydrogel microparticles. Bare hydrogels activate immediately in contact with groundwater due to their strong hydrophilic nature. This immediate activation reduces soil permeability drastically and prevents further hydrogel placement. Therefore, a special hydrogel is needed that exhibits time-delayed activation so that all the hydrogels are in place before activation (water absorption).
  • the at least one hydrophilic core comprises a plurality of hydrophilic cores.
  • each one of the hydrophilic cores is a hydrogel.
  • each one of the hydrophilic cores comprises or consists of a polyacrylamide.
  • each one of the hydrophilic cores is dry.
  • the hydrophobic shell comprises or consists of a polymer, including, but not limited to, polypropylene and polyethylene. In some embodiments, the polymer has a density of less than 997 kg/m 3 . In some embodiments, the hydrophobic shell has an outer diameter that is less than or equal to 10 micrometers. In some embodiments, the hydrophobic shell has an outer diameter that is less than or equal to 1 micrometer.
  • the water is then removed from the at least one hydrophilic particle, thereby producing the at least one hydrophilic core.
  • the monomer, the crosslinker and the initiator can comprise a variety of different compositions.
  • the monomer comprises or consists of acrylamide.
  • the crosslinker comprises or consists of N,N'-methylene-bis-acrylamide.
  • the initiator comprises or consists of ammonium persulfate.
  • the step of removing the water from the at least one hydrophilic particle can be carried out in a variety of ways. In some embodiments, the removal of the water comprises a vacuum evaporation process or a freeze-drying process.
  • the removal of the toluene can be carried out in a variety of ways.
  • the step of removing the toluene from the mixture comprises injecting the mixture into supercritical carbon dioxide and mixing the mixture with the supercritical dioxide using an ultrasonic field.
  • a method of preventing soil liquefaction comprises providing a plurality of water stabilization particles, wherein each water stabilization particle comprises at least one hydrophilic core coated with a hydrophobic shell, and depositing the plurality of water stabilization particles into a target soil.
  • the hydrophobic shells of the deposited particles degrade over a period of time, thereby delaying exposure of the at least one hydrophilic core to water in the target soil.
  • An opening forms in the hydrophobic shells of the deposited particles after the period of time, thereby exposing the at least one hydrophilic core to water in the target soil.
  • the exposed hydrophilic cores then absorb water in the target soil, thereby immobilizing the absorbed water.
  • the target soil can be located in a variety of different locations.
  • the target soil is located underneath a building.
  • the step of depositing the plurality of water stabilization particles into the target soil comprises inserting the water stabilization particles into an injection well at a location upstream from the target soil.
  • the injection well comprises a flow of groundwater.
  • the flow of groundwater then carries the inserted water stabilization particles to the target soil.
  • the target soil is blocked off from an exterior using a slurry wall, thereby forming an exterior side and a target side and the step of depositing the plurality of water stabilization particles into the target soil comprises inserting the particles into a conduit at a location on the exterior side of the slurry wall.
  • the conduit passes from the exterior side through the slurry wall to the target side and into the target soil.
  • the plurality of water stabilization particles flow through the conduit, from the exterior side of the slurry wall to the target side, where they flow out of the conduit and into the target soil.
  • FIG. 1 illustrates one embodiment of different stages of a water stabilization particle in accordance with the principles of the present invention.
  • FIG. 4 is a graph illustrating the mean lysozyme particle size versus power supply to the ultrasonic horn in the Supercritical Antisolvent with Enhanced Mass transfer process for coating hydrophilic particles in accordance with the principles of the present invention.
  • FIG. 7 illustrates another way of delivering the water stabilization particles to target soil underneath a building in accordance with the principles of the present invention.
  • FIG. 8 is a table illustrating the permeability of sand at different hydrogel treatment concentrations in accordance with the principles of the present invention.
  • FIG. 9 is a graph illustrating the effect of hydrogel on the permeability of sand at different concentrations in accordance with the principles of the present invention.
  • FIG. 10 illustrates the reaction of sand at different hydrogel concentrations to shaking in accordance with the principles of the present invention.
  • FIG. 11 is a graph illustrating static triaxial test results for treated and untreated soil in accordance with the principles of the present invention.
  • FIG. 12 is a graph illustrating 0% hydrogel cyclic triaxial test results in accordance with the principles of the present invention.
  • FIG. 13 is a graph illustrating 0.16% hydrogel cyclic triaxial test results in accordance in accordance with the principles of the present invention.
  • FIG. 14 is a graph illustrating 0.33% hydrogel cyclic triaxial test results in accordance in accordance with the principles of the present invention.
  • the present invention provides a special, coated particle having a hydrophilic core and a degradable, waterproof (e.g., hydrophobic) shell.
  • the particle is a microparticle and the core is a hydrogel.
  • the shell allows placement of the hydrogel underwater without hydrogel hydration. First, the special particles are placed in the ground. Then, the shell degrades slowly in a time-release fashion.
  • the hydrogel core hydrates, immobilizing the water (e.g., making it a gel).
  • Shell thickness and polymer type are controlled so that the shell remains intact only for a predetermined time in groundwater, hence providing the "time-release" nature of the particle.
  • the shell opens due to its degradation in the groundwater.
  • hydrogel hydration takes place and the gel forms, immobilizing the water in the soil pores.
  • FDA-approved biocide molecules in the shell are used to resist the microbial attack on the hydrogel.
  • FIG. 1 illustrates one embodiment of different stages of a water stabilization particle 100 in accordance with the principles of the present invention.
  • a plurality of hydrophilic (e.g., hydrogel) nanoparticles 110 each with a 100 nm diameter, with a polymeric coating or casing 120 form a 1000 nm diameter microparticle 100.
  • the casing 120 keeps hydrogel nanoparticles 110 dry until they reach the soil pores, where the casing 120 degrades and the hydrogel nanoparticles 110 will be exposed to water.
  • the water is immediately absorbed by the hydrogel nanoparticles 1 10, causing these nanoparticles 110 to expand, form soft gel particles 110', and get locked in the pores.
  • Hydrogel absorbs up to 240 times its weight in water.
  • the hydrogel-volume-increase equals the water- volume-decrease. It is contemplated that the size of the hydrophilic particles is able to vary. In some embodiments, the diameter of each hydrophilic particle is less than 10 micrometers in size in order to fit in soil pores. In some embodiments, a hydrophilic particle size of 1 micrometer will be used for ease of transport into the tortuous soil pores. It should be noted that it is not critical that all pores in the soil be filled with hydrogel since hydrogel absorbs up to 240 times its weight in water. Only a tiny percentage of pores need to contain the unhydrated particles (e.g., 0.34 wt.%).
  • a group of hydrogel molecules are surrounded by a layer of hydrophobic polymer in order to prevent premature hydrogel hydration during placement. After the particles have been transported to the voids in the soil, the coating must degrade, exposing the hydrogel to the pore water for hydration. Coating thickness and material are varied in order to adjust the degradation time.
  • Particle density is not necessarily crucial because the small particle size allows the particles to remain suspended in groundwater. They can be moved into place either by (a) existing groundwater flow, or (b) a small hydraulic gradient induced by pumping to create groundwater flow.
  • the general subsurface placement schemes are shown in FIGS. 6 and 7 discussed below. Particle settling velocity, v, is given by
  • the Brownian displacement of 1000 nanometer-size particles in water is 1,687 nm/s, which is more than the settling velocity of 430 nm/s. Therefore, these particles are too small to settle by themselves and are not likely to float merely due to Brownian motion, thereby imparting an important property to small particles: they can be easily kept suspended in groundwater at any solid density.
  • each hydrophilic core can comprise or consist of a hydrogel. It is contemplated that the hydrophilic cores can be provided in a variety of ways.
  • hydrogel nanoparticles are produced by the emulsion polymerization method already developed by W. Cai and R.B.
  • the hydrophilic cores can be coated in a variety of ways.
  • the hydrogel particles are coated with a toluene soluble polymer.
  • the hydrophilic nanoparticles are suspended in toluene, using a small amount of surfactant if needed (e.g., food grade dioctyl sodium sulfosuccinate).
  • the coating polymer, dissolved in toluene is added to the suspension.
  • the toluene is rapidly removed under supercritical conditions, precipitating the coating onto the hydrophilic cores and forming a degradable hydrophobic shell around the plurality of hydrophilic cores.
  • the toluene is removed using the Supercritical Antisolvent with
  • the liquid/solid suspension is injected, using a fine nozzle, into supercritical carbon dioxide at 4O 0 C and 100 bar.
  • the liquid/solid jet is mixed with carbon dioxide using an ultrasonic field, thereby creating microdroplets.
  • Toluene is readily soluble in supercritical carbon dioxide, whereas hydrogel and the coating polymer are not. Due to the high diffusivity in the supercritical conditions, all the toluene very rapidly leaves the droplets, precipitating the coating onto the hydrogel nanoparticles. Microparticles (hydrogel nanoparticles now enclosed into a shell) are precipitated.
  • the coating on the composite hydrogel nanoparticles must degrade in order to allow the hydrogel to access the groundwater.
  • the degradation rate depends on the temperature (T).
  • T temperature
  • Degradation rate A e ( £/ ⁇ r) , where A (molecular collision frequency), E (activation energy), and R (gas constant) are constants.
  • a coating that degrades in 4 months at 15°C is expected to take only 15 days to degrade at 45°C.
  • standard FDA-approved biocides are included in the hydrogel coating to delay biological degradation. Furthermore, in some embodiments, adjustments to the manufacturing process are needed.
  • the water stabilization particles can be deposited into the target soil in a variety of ways.
  • the water stabilization particles are suspended in water and placed into injection wells (e.g., via conduits 610) upstream from the target soil under very low head at the step 512a.
  • the inserted particles are moved under the building 620 in the direction of groundwater flow by the flow of the groundwater.
  • the particles travel under the whole building 620 before the protective coating dissolves, releasing hydrogel, which immediately hydrates and immobilizes the groundwater.
  • the coating's dissolution time is chosen based on the velocity of groundwater flow and the coating material dissolution rate.
  • the target site is blocked off with a slurry wall 715.
  • Directional drilling is used to get under the building 720 and release the particles through porous pipes.
  • a conduit 710 passes through the slurry wall 715, which blocks of the target soil.
  • the water stabilization particles are inserted into the conduit 710.
  • the inserted particles flow through the conduit 710, traveling from a location outside of the boundaries of the slurry wall 715 to a location within the boundaries of the slurry wall 715.
  • the particles flow out of the conduit 710 and into the target soil (e.g., underneath the building 720), moving upwards with a small hydraulic gradient created by mild dewatering.
  • the particles are retained laterally by the slurry wall 715.
  • the coating eventually dissolves. The first breach of the coating allows for complete hydrogel hydration, where the gel forms, thereby immobilizing the water in the target soil.
  • Hydrogel reduced permeability in all cases. A very low permeability was reached at a hydrogel concentration of only 0.34 wt.%. This is less than the volume of the soil voids. Additional hydrogel did not significantly reduce the permeability. A sufficient amount of hydrogel blocks and isolates pores and produces a minimum permeability.
  • Static triaxial tests were run with different hydrogel concentrations.
  • the static triaxial tests show hydrogel does not significantly affect the peak pore pressures, as seen in FIG. 11, which is a graph illustrating static triaxial test results for treated and untreated soil.
  • the soil ceases to dilate and pore pressures do not decrease.
  • the variation in peak pore pressures seems to be within the scatter of the data.
  • High pore pressures during shear suggest liquefaction susceptibility was not reduced. This is refuted completely by the cyclic triaxial and flow table tests discussed below. It should be noted that this is not just soil anymore. Rather, it is soil with hydrogel and does not behave like soil alone. The soil does not dilate or contract because the water is gelled.
  • FIG. 12 is a graph illustrating 0% hydrogel cyclic triaxial test results. Samples were considered liquefied when they had significant strength loss (a cyclic mobility). The 0% sample liquefied after only about 6 cycles, at ⁇ 40 pounds, as shown by the increase in pore pressure and the decrease in force needed to deform the sample. The force decreased from ⁇ 40 pounds to less than ⁇ 10 pounds.
  • FIG. 13 is a graph illustrating 0.16% hydrogel cyclic triaxial test results.
  • the 0.16% hydrogel would not fail at ⁇ 40 pounds.
  • the sample failed at ⁇ 100 pounds after about 40 cycles. It did not liquefy (fluidize), but did exhibit strength loss. 40 cycles represents an earthquake much, much stronger than any earthquake ever experienced on earth.
  • a M8.5 event suggests only 26 cycles (Seed and Idriss (1982), Ground Motions and Soil Liquefaction During Earthquakes, EERI, UCB, Berkeley, CA).
  • FIG. 14 is a graph illustrating 0.33% hydrogel cyclic triaxial test results. The
  • hydrogel soil does not liquefy and is stronger (requires larger cyclic force to fail) than untreated soil.
  • the present invention can immediately prevent liquefaction under existing buildings in extreme events. Currently, it is expensive and risky to ameliorate soils for liquefaction abatement under existing buildings.
  • the present invention makes it possible, effective, and inexpensive.
  • hydrogels of the present invention have applications in groundwater remediation, contaminant isolation, dam rehabilitation, foundation remediation, canal lining, dewatering, and landfill isolation.

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Soil Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Hydrology & Water Resources (AREA)
  • Water Supply & Treatment (AREA)
  • Environmental & Geological Engineering (AREA)
  • Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)

Abstract

Cette invention concerne une particule de stabilisation de l'eau qui comprend au moins un noyau hydrophile et une couche hydrophobe recouvrant ledit noyau hydrophile. La couche hydrophobe est conçue pour se détériorer dans le temps retardant ainsi l'exposition du noyau hydrophile à un liquide qui se trouve en dehors de la couche hydrophobe.
PCT/US2008/009398 2007-08-07 2008-08-01 Stabilisation de l'eau au moyen de microparticules Ceased WO2009020594A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US96376107P 2007-08-07 2007-08-07
US60/963,761 2007-08-07

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WO2009020594A1 true WO2009020594A1 (fr) 2009-02-12

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018022554A1 (fr) * 2016-07-26 2018-02-01 Board Of Regents, The University Of Texas System Supports de microparticules pour compositions aqueuses et procédés de fabrication

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004064997A1 (fr) * 2003-01-23 2004-08-05 Inotech Ag Nouvelles microcapsules pouvant etre utilisees comme agent d'extraction, en particulier pour l'extraction de contaminants contenus dans l'eau ou dans le sol
US7105229B2 (en) * 1997-09-09 2006-09-12 Lyotropic Therapeutics, Inc. Coated particles, methods of making and using

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7105229B2 (en) * 1997-09-09 2006-09-12 Lyotropic Therapeutics, Inc. Coated particles, methods of making and using
WO2004064997A1 (fr) * 2003-01-23 2004-08-05 Inotech Ag Nouvelles microcapsules pouvant etre utilisees comme agent d'extraction, en particulier pour l'extraction de contaminants contenus dans l'eau ou dans le sol

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018022554A1 (fr) * 2016-07-26 2018-02-01 Board Of Regents, The University Of Texas System Supports de microparticules pour compositions aqueuses et procédés de fabrication

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