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Sample records for kaolins bentonites palyg

  1. Kaolin

    USGS Publications Warehouse

    Virta, R.L.

    2001-01-01

    Part of the 2000 annual review of the industrial minerals sector. A general overview of the kaolin industry is provided. In 2000, production of kaolin was estimated to be 8.87 Mt, which is less than the amount produced in 1999. Domestic sales of kaolin decreased in 2000, with sales of kaolin for paper filler applications continuing to drop.

  2. Kaolin

    USGS Publications Warehouse

    Virta, Robert L.

    2014-01-01

    The article reports on the market performance of kaolin in the U.S. in 2009 and presents an outlook for its 2010 performance. There was a decline in the domestic sales of kaolin from 6.74 measurement ton (Mt) to 5.2 Mt. Companies in the country engaged in kaolin production include Advanced Primary Minerals Corp., Applied Minerals Inc., and Daleco Resources Corp. The decline in world production of kaolin from 2008 to 2009 is also noted.

  3. Kaolin

    USGS Publications Warehouse

    Virta, R.L.

    2000-01-01

    Part of the 1998 Industrial Minerals Review. Activities in the kaolin industry in 1999 are reviewed. U.S. production of kaolin in 1999 was estimated to be 10.7 million st, an increase of 0.3 million st from the previous year. The paper industry is the largest user of kaolin, accounting for 59 percent of domestic sales. Company activities, announcements, and plans of interest to the kaolin industry are outlined.

  4. Kaolin

    USGS Publications Warehouse

    Virta, R.L.

    2011-01-01

    The article discusses the latest developments in the global kaolin industry, particularly in the U.S., as of June 2011. It claims that Georgia is the top producing state in the U.S., with a 94% share in total production. The other top producers include South Carolina, North Carolina and Florida. Kaolin is used in the manufacture of such products as electrical porcelain, pottery and sanitaryware.

  5. Kaolin

    USGS Publications Warehouse

    Virta, R.L.

    2006-01-01

    In 2005, 22 companies mined kaolin in nine US states. Production in Georgia declined to 6.19 Mt down from 6.78 Mt in 2004. Despite the decline, Georgia remained the leading producer state followed by Alabama, South Carolina, Arkansas, Texas, Nevada, California, North Carolina and Florida. In the next year or two, domestic and export sales of kaolin for paper application are not expected to change significantly.

  6. Kaolin

    USGS Publications Warehouse

    Virta, R.L.

    2007-01-01

    Part of the 2006 industrial minerals review. U.S. kaolin production was an estimated 7.74 Mt in 2006, with 7.1 Mt produced by Georgia. Imports increased from 262 kt in 2005 to about 303 kt in 2006, whereas exports decreased from 3.58 Mt in 2005 to 3.54 Mt in 2006. Inexpensive Brazilian imports and a lackluster domestic paper market are expected to cause a slight reduction in kaolin sales to the U.S. paper industry.

  7. Modeling the influence of ethanol on the adsorption and desorption of selected BTEX compounds on bentonite and kaolin.

    PubMed

    Garoma, Temesgen; Skidmore, Lacy

    2011-01-01

    The influence of ethanol on the adsorption capacity and desorption kinetics of benzene and toluene on bentonite and kaolin through modeling and experimental study was investigated. The results showed that the adsorption capacity of both soils for the target compounds decreased as ethanol content increased. As ethanol content increased from 0 to 50%, the adsorption capacity for benzene and toluene on bentonite decreased from 3.6 to 0.54 microg(n+1)/(L(n) x g) (by 85%) and 1.91 to 0.01 microg(n+1)/(L(n) x g) (by 99.5%), respectively. For benzene and toluene adsorption on kaolin, the adsorption capacity decreased by 86.5% (from 0.26 to 0.04 microg(n+1)/(L(n) x g) and 98.2% (from 0.13 to 0.002 microg(n+1)/(L(n) x g)), respectively, as ethanol content increased from 0 to 50%. In addition, the desorption rate of benzene and toluene from bentonite decreased by about one order of magnitude as the ethanol increased from 0 to 25% and 0 to 50%, respectively. It can be inferred that ethanol could affect the effectiveness of natural attenuation processes that rely on adsorption to soils as a containment technique for benzene and toluene by retarding the adsorption to soils and remobilizing compounds that had already been adsorbed to soils.

  8. Kaolin

    USGS Publications Warehouse

    Virta, R.L.

    2012-01-01

    Fifteen companies mined kaolin in nine states in 2011. Production, on the basis of preliminary data, was estimated to be 5.48 Mt (6.04 million st) valued at $822 million, an increase from 5.42 Mt (5.97 million st) valued at $788 million in 2010. Production in Georgia, the top producing state, increased to an estimated 5.1 Mt (5.62 million st) valued at $790 million in 2011 from 5.05 Mt (5.57 million st) valued at $757 million in 2010. Georgia accounted for 93 percent of U.S. production tonnage and nearly the entire domestic water-washed, delaminated and pigment-grade calcined kaolin production.

  9. Kaolin

    USGS Publications Warehouse

    Virta, R.L.

    2013-01-01

    Nineteen companies mined kaolin in eight states in 2012. Production, on the basis of preliminary data, was estimated to be 5.88 Mt (6.48 million st) valued at $841 million, an increase from 5.77 Mt (6.36 million st) valued at $817 million in 2011. Production in Georgia, the top producing state, increased to an estimated 5.45 Mt (6.01 million st) valued at $804 million in 2012 from 5.34 Mt (5.89 million st) valued at $781 million in 2011. Georgia accounted for 93 percent of U.S. production tonnage and nearly the entire domestic water-washed, delaminated and pigment-grade calcined kaolin production.

  10. Rheology Modifiers Applied to Kaolin-Bentonite Slurries for SRNL WTP Pulse Jets Tank Pilot Work in Support of RPP at Hanford

    SciTech Connect

    WILLIAM, DANIEL

    2005-02-09

    Savannah River National Laboratory (SRNL) was tasked to find and characterize the impact of rheological modifiers to a clay (Kaolin-Bentonite) slurry having 23.1 total wt percent solids, 1.165 g/ml, and Bingham Plastic yield stress of 13 Pa and plastic viscosity of 24 mPa-sec. The primary objective was to find rheological modifiers when blended with this clay slurry that would provide a vane yield stress of 300 Pa when the slurry was undisturbed for 24 hours. A secondary objective was to find a modifier that after shearing would produce a Bingham Plastic yield stress of 30 Pa and plastic viscosity of 30 mPa-sec. Two parallel paths were chosen with one examining a variety of organic/inorganic modifiers and another using just the inorganic modifier Laponite (R). The addition of organic modifiers hydroxyethylcellulose, hydroxypropylmethylcellulose, and hydroxypropylcellulose at a target 0.50 wt percent dramatically increased the vane yield stress over the range 311 - 724 Pa, and also increased the Bingham plastic yield stress and plastic viscosities over the range 33-112 Pa and 27-166 mPa-sec, respectively. The organic modifiers also showed elastic behavior, yielding a very unpredictable up flow curve. The 0.50 wt percent addition of inorganic modifiers magnesium aluminum silicate and hydrate magnesium aluminum silicate only increased the vane yield stress to 36-46 Pa and had little impact on the Bingham Plastic parameters. A range of an inorganic (2-4 wt percent magnesium aluminum silicate) and combination of a range of an inorganic (2-3 wt percent magnesium aluminum silicate) and organic (0.03-0.05 wt percent sodium carboxymethylcellulose) modifiers were then tested. These results showed that the target vane yield stress could be obtained but the Bingham Plastic yield stress and plastic viscosity were 3 times too high. Reducing the organic modifier weight percent by a few hundredths, the Bingham Plastic yield stress could be obtained, but then the vane yield stress

  11. Waste behavior during horizontal extrusion: Effect of waste strength for bentonite and kaolin/ludox simulants and strength estimates for wastes from Hanford waste tanks 241-SY-103, AW-101, AN-103, and S-102

    SciTech Connect

    Gauglitz, P.A.; Aikin, J.T.

    1997-10-01

    The Hanford Site has 149 single-shell tanks (SSTs) and 28 double-shell tanks (DSTs) containing radioactive wastes that are complex mixes of radioactive and chemical products. Some of these wastes are known to generate mixtures of flammable gases, including hydrogen, nitrous oxide, and ammonia. Nineteen of these SSTs and six of the DSTs have been placed on the Flammable Gas Watch List because they are known or suspected, in all but one case, to retain these flammable gases. Because these gases are flammable, their retention and episodic release pose a number of safety concerns. Understanding the physical mechanisms and waste properties that contribute to the retention and release of these gases will help to resolve the Flammable Gas Safety Issue. The strength of the waste plays a central role in the mechanisms of both bubble retention and bubble release. While recent in-situ measurements from the ball rheometer have provided results for five of the DSTs, waste strength measurements are typically not available for any of the SSTs or for the DSTs that have not been characterized with the ball rheometer. The overall purpose of this study is to develop a method to obtain strength estimates for actual wastes from observations of the wastes` behavior during extrusion from core samplers. The first objective of the study was to quantify waste behavior during horizontal extrusion by documenting the extrusion behavior of simulants with known strengths; the second was to estimate the strength of actual waste based on these simulant standards. Results showed a reproducible extrusion behavior for bentonite clay and kaolin/Ludox{reg_sign} simulants over strengths ranging from 30 to 6,500 Pa. The extrusion behavior was documented with both video recordings and still images. Based on these visual standards, strength estimates were made for wastes from DSTs 241-SY-103, 241-AW-101, and 241-AN-103 and SST 241-S-102.

  12. Final report on the safety assessment of aluminum silicate, calcium silicate, magnesium aluminum silicate, magnesium silicate, magnesium trisilicate, sodium magnesium silicate, zirconium silicate, attapulgite, bentonite, Fuller's earth, hectorite, kaolin, lithium magnesium silicate, lithium magnesium sodium silicate, montmorillonite, pyrophyllite, and zeolite.

    PubMed

    Elmore, Amy R

    2003-01-01

    This report reviews the safety of Aluminum, Calcium, Lithium Magnesium, Lithium Magnesium Sodium, Magnesium Aluminum, Magnesium, Sodium Magnesium, and Zirconium Silicates, Magnesium Trisilicate, Attapulgite, Bentonite, Fuller's Earth, Hectorite, Kaolin, Montmorillonite, Pyrophyllite, and Zeolite as used in cosmetic formulations. The common aspect of all these claylike ingredients is that they contain silicon, oxygen, and one or more metals. Many silicates occur naturally and are mined; yet others are produced synthetically. Typical cosmetic uses of silicates include abrasive, opacifying agent, viscosity-increasing agent, anticaking agent, emulsion stabilizer, binder, and suspending agent. Clay silicates (silicates containing water in their structure) primarily function as adsorbents, opacifiers, and viscosity-increasing agents. Pyrophyllite is also used as a colorant. The International Agency for Research on Cancer has ruled Attapulgite fibers >5 microm as possibly carcinogenic to humans, but fibers <5 microm were not classified as to their carcinogenicity to humans. Likewise, Clinoptilolite, Phillipsite, Mordenite, Nonfibrous Japanese Zeolite, and synthetic Zeolites were not classified as to their carcinogenicity to humans. These ingredients are not significantly toxic in oral acute or short-term oral or parenteral toxicity studies in animals. Inhalation toxicity, however, is readily demonstrated in animals. Particle size, fibrogenicity, concentration, and mineral composition had the greatest effect on toxicity. Larger particle size and longer and wider fibers cause more adverse effects. Magnesium Aluminum Silicate was a weak primary skin irritant in rabbits and had no cumulative skin irritation in guinea pigs. No gross effects were reported in any of these studies. Sodium Magnesium Silicate had no primary skin irritation in rabbits and had no cumulative skin irritation in guinea pigs. Hectorite was nonirritating to the skin of rabbits in a Draize primary skin

  13. Organically modified low-grade kaolin as a secondary containment material for underground storage tanks.

    PubMed

    Moon, Chul-Hwan; Lee, Jai-Young; Oh, Byung-Taek; Choi, Sang-Il

    2007-08-01

    Batch scale reactions were conducted to evaluate the efficacy of modified low-grade kaolin for the treatment of petroleum contaminants. Low-grade kaolin, which has been unvalued as material in the mining process because of its low quality for commercial products, was modified with HDTMA (hexadecyl-trimethylammonium), and its efficiency was compared with that of HDTMA-modified bentonite, which is used as a secondary containment barrier for underground storage tanks. The sorption capacity and hydraulic conductivity of both the HDTMA-modified bentonite and low-grade kaolin were investigated and showed distribution coefficients in the sorption of benzene, toluene, ethylbenzene and xylene ranging between 45.7 and 583.7 and 57.0 and 525.1, respectively. The hydraulic conductivities were 2.53 x 10(-8) and 5.62 x 10(-8) cm/s for the HDTMA-modified bentonite and low-grade kaolin, respectively. These results suggest that HDTMA-modified low-grade kaolin could be used as a hydraulic barrier against advection migration of petroleum contaminants. Simulation of the one-dimensional transport of benzene through a liner made of either one of the compounds was also performed. These results also showed that HDTMA-modified kaolin more effectively retards the transport of benzene.

  14. Bentonite mat demonstration. Final report

    SciTech Connect

    Serrato, M.G.

    1994-12-30

    The Bentonite Mat Demonstration was developed to provide the Environmental Restoration Department with field performance characteristics and engineering data for an alternative closure cover system configuration. The demonstration was initiated in response to regulatory concerns regarding the use of an alternative cover system for future design configurations. These design considerations are in lieu of the US Environmental Protection Agency (EPA) Recommended Design for Closure Cover Systems and specifically a single compacted kaolin clay layer with a hydraulic conductivity of 1 {times} 10{sup {minus}7} cm/sec. This alternative configuration is a composite geosynthetic material hydraulic barrier consisting from bottom to top: 2 ft compacted sandy clay layer (typical local Savannah River Site soil type) that is covered by a bentonite mat--geosynthetic clay liner (GCL) and is overlaid by a 40 mil High Density Polyethylene (HDPE) geomembrane--flexible membrane liner. This effort was undertaken to obtain and document the necessary field performance/engineering data for future designs and meet regulatory technical requirements for an alternative cover system configuration. The composite geosynthetic materials hydraulic barrier is the recommended alternative cover system configuration for containment of hazardous and low level radiological waste layers that have a high potential of subsidence to be used at the Savannah River Site (SRS). This alternative configuration mitigates subsidence effects in providing a flexible, lightweight cover system to maintain the integrity of the closure. The composite geosynthetic materials hydraulic barrier is recommended for the Sanitary Landfill and Low Level Radiological Waste Disposal Facility (LLRWDF) Closures.

  15. Kaolin clotting time.

    PubMed

    Radhakrishnan, Kottayam

    2013-01-01

    The kaolin clotting time (KCT) is a sensitive test used in the laboratory detection of lupus anticoagulants (LA) (Derksen and de Groot, Thromb Res 114:521-526, 2004). It is essentially an activated partial thromboplastin time (APTT) test with no added phospholipid. Kaolin acts as the activator in the KCT. In the absence of additional phospholipid reagent, the quality of the test sample is extremely important since the generation of thrombin completely depends on the presence of residual cell membranes and plasma lipids (Derksen and de Groot, Thromb Res 114:521-526, 2004). Since the test contains no exogenous phospholipid, a confirmatory test using excess phospholipid is required to confirm the presence of lupus anticoagulant in the sample (Court, Br J Biomed Sci 54:287-298, 1997).

  16. Zeolite membranes from kaolin

    SciTech Connect

    Karle, B.G.; Brinker, C.J. |; Phillips, M.L.F.

    1996-07-01

    Zeolite films are sought as components of molecular sieve membranes. Different routes used to prepare zeolite composite membranes include growing zeolite layers from gels on porous supports, depositing oriented zeolites on supports, and dispersing zeolites in polymeric membranes. In most cases, it is very difficult to control and avoid the formation of cracks and/or pinholes. The approach to membrane synthesis is based on hydrothermally converting films of layered aluminosilicates into zeolite films. The authors have demonstrated this concept by preparing zeolite A membranes on alumina supports from kaolin films. The authors have optimized the process parameters not only for desired bulk properties, but also for preparing thin (ca. 5 {micro}m), continuous zeolite A films. Scanning electron microscopy shows highly intergrown zeolite A crystals over most of the surface area of the membrane, but gas permeation experiments indicate existence of mesoporous defects and/or intercrystalline gaps. It has been demonstrated that the thickness of the final zeolite A membrane can be controlled by limiting the amount of precursor kaolin present in the membrane.

  17. Energetics of kaolin polymorphs

    SciTech Connect

    Ligny, D. de; Navrotsky, A.

    1999-04-01

    The enthalpy of formation of kaolin polymorphs at 298 K has been determined by drop-solution calorimetry into molten lead borate at 975 K. Corrections have been made for impurities in the samples. The standard enthalpy of formation from the elements is: kaolinite {minus}4120.2 {+-} 6.6 kJ/mol, dickite {minus}4107.6 {+-} 5.7 kJ/mol, nacrite {minus}4104.0 {+-} 7.6 kJ/mol, and halloysite {minus}4097.5 {+-} 5.6 kJ/mol. Using entropy data from the literature, the standard free energy of formation from the elements at 298 K is /{minus}3799.4 {+-} 6.4 kJ/mol for kaolinite, {minus}3785.1 {+-} 5.6 kJ/mol for dickite, and {minus}3776.8 {+-} 5.8 kJ/mol for halloysite. The effect of crystallinity (Hinckley index ranging from 1.6 to 0.4) on the enthalpy of formation of kaolinite is smaller than 5 kJ/mol, the experimental error. The relative stability of the polymorphs probably does not change significantly with pressure and temperature over their range of occurrence. Thus the geological occurrence of halloysite, nacrite, and dickite, which are metastable phases, must be interpreted in terms of kinetics or as the result of a specific synthesis path, rather than as resulting from changes in the thermodynamically stable phase assemblage.

  18. Kaolin dust concentrations and pneumoconiosis at a kaolin mine.

    PubMed Central

    Altekruse, E B; Chaudhary, B A; Pearson, M G; Morgan, W K

    1984-01-01

    Kaolin is removed from underground seams in the mining area to a processing area, where it is sliced, dried, and pulverised to make the finished product. A study was undertaken to determine the dust concentrations in various work areas and to assess the prevalence of radiographic and pulmonary function abnormalities in 65 workers at a Georgia kaolin mine. Respirable dust concentrations were higher in the processing area than in the mine or maintenance areas for all determinations from 1977 to 1981. The mean respirable dust level in the processing area in 1981 was 1.74 mg/m3 and 0.14 mg/m3 in the mine area. Five workers, all of whom had worked at the processing area, had radiographic evidence of kaolin pneumoconiosis. The mean values of forced vital capacity (FVC) and FEV1 of the entire group were within the normal range. When the spirometric values were expressed as a percentage of the predicted values, the FVC and FEV1 were significantly lower in the workers with kaolinosis than in other workers in the processing area. The FVC and FEV1 also declined significantly with increasing years of work in the processing area. The FEV1/FVC%, however, was not significantly altered either by the presence of kaolinosis or by an increasing number of years of work, indicating that the impairment was restrictive and hence likely to be a consequence of dust inhalation rather than smoking. In this study the highest dust concentrations occurred in the processing area, and kaolin pneumoconiosis was limited to those who had worked there. Kaolin exposure appeared to have a small but significant effect on ventilatory capacity in those with kaolin pneumoconiosis and in workers with a longer exposure. There was no association between the radiographic appearances of kaolinosis and cigarette smoking or between the presence of radiographic abnormalities and reduced arterial blood gas tensions. Images PMID:6463912

  19. 21 CFR 186.1256 - Clay (kaolin).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Clay (kaolin). 186.1256 Section 186.1256 Food and... Substances Affirmed as GRAS § 186.1256 Clay (kaolin). (a) Clay (kaolin) Al2O3.2SiO2.nH2O, Cas Reg. No. 1332-58-7) consists of hydrated aluminum silicate. The commercial products of clay (kaolin)...

  20. 21 CFR 186.1256 - Clay (kaolin).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Clay (kaolin). 186.1256 Section 186.1256 Food and... Substances Affirmed as GRAS § 186.1256 Clay (kaolin). (a) Clay (kaolin) Al2O3.2SiO2.nH2O, Cas Reg. No. 1332-58-7) consists of hydrated aluminum silicate. The commercial products of clay (kaolin)...

  1. 21 CFR 186.1256 - Clay (kaolin).

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Clay (kaolin). 186.1256 Section 186.1256 Food and... Substances Affirmed as GRAS § 186.1256 Clay (kaolin). (a) Clay (kaolin) Al2O3.2SiO2.nH2O, Cas Reg. No. 1332-58-7) consists of hydrated aluminum silicate. The commercial products of clay (kaolin)...

  2. 21 CFR 186.1256 - Clay (kaolin).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Clay (kaolin). 186.1256 Section 186.1256 Food and....1256 Clay (kaolin). (a) Clay (kaolin) Al2O3.2SiO2.nH2O, Cas Reg. No. 1332-58-7) consists of hydrated aluminum silicate. The commercial products of clay (kaolin) contain varying quantities of alkalies...

  3. 21 CFR 186.1256 - Clay (kaolin).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Clay (kaolin). 186.1256 Section 186.1256 Food and... Substances Affirmed as GRAS § 186.1256 Clay (kaolin). (a) Clay (kaolin) Al2O3.2SiO2.nH2O, Cas Reg. No. 1332-58-7) consists of hydrated aluminum silicate. The commercial products of clay (kaolin)...

  4. Kaolin pneumoconiosis. A case report

    SciTech Connect

    Lapenas, D.J.; Gale, P.N.

    1983-12-01

    A 35-year-old man who had been occupationally exposed to aerosolized kaolin for 17 years in a Georgia processing plant had diffuse reticulonodular pulmonary infiltrates and an upper lobe mass. Exploratory thoracotomy, performed to evaluate the nature of the mass, revealed an 8 X 12 X 10-cm conglomerate pneumoconiotic lesion containing large amounts of kaolinite. Coincident deposition of silica in the tissue was not demonstrable by either analytic scanning electron microscopy or x-ray diffraction. The case illustrates the effect of chronic kaolin exposure on the human lung and emphasizes the need for periodic evaluation of exposed workers.

  5. Comparative tests for evaluating permeability changes of a compacted bentonite/sand mixture during shear

    SciTech Connect

    Esaki, T.; Zhang, M.; Mitani, Y.

    1997-12-31

    A compacted mixture of Kunigeru VI bentonite and D-sand is being considered for use as an engineered barrier in low-level radioactive waste disposal facilities in Japan. An important issue is the maintenance of the retardation property of the mixture during shear that might be induced in such barriers by earthquakes and/or gradual tectonic deformations occurring over the design life of the facility. Comparative tests on a bentonite-sand mixture and kaolin-sand mixture were conducted by means of a recently-developed coupled shear and permeability testing apparatus under temperature controlled condition. The specific storage of bentonite-sand specimen during shear is also systematically evaluated with the new analytical theory for the constant flow permeability test. The present study reveals that (1) temperature control is preferred for measuring the permeability of extremely-low permeability materials with the constant-flow pump method; (2) both the permeability and specific storage of the mixture of Kunigeru VI bentonite and D-sand were not significantly influenced by shear strains up to 3% whereas the permeability of the kaolin-sand mixture increased almost linearly with the increment of shear strain; (3) the swelling of bentonite in the mixture under low confining stress decreases both the permeability and specific storage of bentonite-sand mixture; and (4) the constant flow permeability test method, with the newly derived theoretical analysis, promises to become a very effective means of investigating, rapidly and systematically, the permeability and specific storage of extremely-low permeability materials with relatively-low hydraulic gradients.

  6. Bentonite, Bandaids, and Borborygmi

    PubMed Central

    Williams, Lynda B.; Haydel, Shelley E.; Ferrell, Ray E.

    2010-01-01

    The practice of eating clay for gastrointestinal ailments and applying clay topically as bandaids for skin infections is as old as mankind. Bentonites in particular have been used in traditional medicines, where their function has been established empirically. With modern techniques for nanoscale investigations, we are now exploring the interactions of clay minerals and human pathogens to learn the lessons that Mother Nature has used for healing. The vast surface area and chemical variability of hydrothermally altered bentonites may provide a natural pharmacy of antibacterial agents. PMID:20607126

  7. Compatibility of bentonite and DNAPLs

    SciTech Connect

    McCaulou, D.R.; Huling, S.G.

    1999-10-01

    The compatibility of dense nonaqueous phase liquids (DNAPLs), trichloroethylene (TCE), methylene chloride (MC), and creosote with commercially available sodium bentonite pellets was evaluated using stainless steel, double ring, falling head permeameters. The hydraulic conductivity (K) of the bentonite clay was measured under three experimental conditions: (1) water soluble constituents of the DNAPLs were used to hydrate and permeate the bentonite; (2) bentonite pellets were submersed in DNAPL prior to hydration and permeation with water; and (3) DNAPLs were pooled on water-hydrated bentonite. Further, the effect of hydraulic head on water-hydrated bentonite permeated with TCE and the effects of TCE exposure time to mixtures of bentonite grout and sand were measured.

  8. Refractories from kaolins of the Angrenskoe deposit

    SciTech Connect

    Khodzhaev, T.K.; Valishev, R.S.; Karklit, A.K.

    1995-09-01

    Samples of kaolin from the Angrenskoe deposit have been investigated by specialists from the Tashkent Stromproekt Research Institute and the St. Petersburg Institute of Refractories. Semiindustrial batches of articles from Angrenskoe kaolin were produced by the experimental technological department of the St. Petersburg Institute of Refractories. It was established that the experimental articles meet the requirements of GOST 390 - 83 for chamotte articles of grades ShA and ShB. Angrenskoe kaolins can be a raw material for the production of chamotte and semiacid refractories for various purposes.

  9. Interrelationship of Kaolin, Alkaline Liquid Ratio and Strength of Kaolin Geopolymer

    NASA Astrophysics Data System (ADS)

    Ramasamy, Shamala; Hussin, Kamarudin; Bakri Abdullah, Mohd Mustafa Al; Mohd Ruzaidi Ghazali, Che; Binhussain, Mohammed; Sandu, Andrei Victor

    2016-06-01

    Geopolymer is an incredible alternative green cementitious material which has ceramic-like properties, but does not require calcining that leads to reduction in processing energy usage. The purpose of this research is to study the correlation between kaolin: liquid ratio with the performance of kaolin geopolymer. Kaolin, a prominent raw geopolymer material was used to prepare enhanced geopolymer paste by mixing with alkaline activator solution. Interrelationship of kaolin to alkaline liquid ratio with hardness and flexural strength was the focus of this work. Therefore kaolin geopolymer paste with varying solid to liquid ratio ranging from 0.7 to 1.1 was prepared. Geopolymer paste was coated on low grade wood substrate prior to Vickers hardness and flexural strength. X-ray diffraction was conducted on geopolymer paste itself after 7 days to analyze the change in phase identification at early age. Kaolin geopolymer coating on wood with solid/liquid(S/L) ratio of 0.7 shows the most promising hardness and flexural strength of 15.3 Hv and 94.73MPa. X-ray diffraction test showed high existence of kaolinite on higher S/L ratio where as sodalite was observed in S/L ratio of 0.7. Microstructural studies also compliments our finding which further proves the positive dependency of S/L ratio and kaolin geopolymer strength.

  10. COMPATIBILITY OF BENTONITE AND DNAPLS

    EPA Science Inventory

    The compatibility of dense non-aqueous phase liquids (DNAPLs), trichloroethylene (TCE), methylene chloride (MC), and creosote with commercially available sodium bentonite pellets was evaluated using stainless steel, double-ring, falling-head permeameters. The Hydraulic conductiv...

  11. Immobilization of horseradish peroxidase onto kaolin.

    PubMed

    Šekuljica, Nataša Ž; Prlainović, Nevena Ž; Jovanović, Jelena R; Stefanović, Andrea B; Djokić, Veljko R; Mijin, Dušan Ž; Knežević-Jugović, Zorica D

    2016-03-01

    Kaolin showed as a very perspective carrier for the enzyme immobilization and it was used for the adsorption of horseradish peroxidase (HRP). The effects of the enzyme concentration and pH on the immobilization efficiency were studied in the reaction with pyrogallol and anthraquinone dye C.I. Acid Violet 109 (AV 109). In addition, Fourier transform infrared spectroscopy, scanning electron microscopy and analysis by Brunauer-Emmett-Teller were performed for kaolin, thermally activated kaolin and the immobilized enzyme. It has been shown that 0.1 IU of HRP-kaolin decolorized 87 % of dye solution, under the optimal conditions (pH 5.0, temperature 24 °C, dye concentration 40 mg/L and 0.2 mM of H2O2) within 40 min. The immobilized HRP decolorization follows the Ping Pong Bi-Bi mechanism with dead-end inhibition by the dye. The biocatalyst retained 35 ± 0.9 % of the initial activity after seven cycles of reuse in the decolorization reaction of AV 109 under optimal conditions in a batch reactor. The obtained kinetic parameters and reusability study confirmed improvement in performances of k-HRP compared to free, indicating that k-HRP has a great potential for environmental purposes.

  12. Electrokinetic removal of caesium from kaolin.

    PubMed

    Al-Shahrani, S S; Roberts, E P L

    2005-06-30

    Soil, in the form of kaolin and a sample of natural soil from an industrial site, was artificially contaminated with caesium and subjected to electrokinetic treatment. The effect of catholyte pH control on the process was investigated using different acids to control the catholyte pH. During treatment the in situ pH distribution, the current flow, and the potential distribution were monitored. At the end of the treatment the pore fluid conductivity and the caesium concentration distribution was measured. The results of these experiments showed that for caesium contamination, catholyte pH control is essential in order to create a suitable environment throughout the soil to enable contaminant removal. It was found that the type of acid used to control the catholyte pH affected the rate of caesium removal (nitric, sulphuric, acetic and citric acids were tested). All of the acids tested were effective, but the highest caesium extraction was achieved when nitric acid was used to control the catholyte pH. The relatively high adsorption capacity of the soil for caesium was found to significantly reduce the rate of removal. After 240 h of treatment at 1 Vcm(-1) (using sulphuric acid to control the catholyte pH), less than 80% of the caesium was removed from a 30 cm long sample of kaolin. Electrokinetic treatment of the industrial soil sample was slower than for the kaolin, but a significant extraction rate for caesium was achieved.

  13. Synthesis of New Kaolin Molecular Sieves from Kaolin and Its Adsorption of NH4+

    NASA Astrophysics Data System (ADS)

    Fang, Jin; Sun, Peide; Zhang, Yi; Wang, Qi; Ma, Wanggang

    2010-11-01

    New kaolin molecular sieves are hydrothermally synthesized from kaolin (for simplicity, hereafter denoted as KMS). The as-prepared KMS can be applied in the treatment of ammonia-containing wastewater by efficient adsorption of NH4+. The time of activation, the temperatures of calcination, the times of centrifugation and other experimental conditions which would affect the activity of the KMS were studied in depth. Experiments results indicate that when the the kaolin was activated at 90° C for 4 h, followed by calcination at 250° C, the maximum activity of NH4+ adsorption can be achieved. When the initial NH4+ concentration is 100 mg/L, 50% NH4+ can be removed via adsorption by 0.5 g/L KMS which is analogous to the commercial Nanochem zeolites obtained from Austria Nanochem Pty Ltd.

  14. Calcium and sodium bentonite for hydraulic containment applications

    SciTech Connect

    Gleason, M.H.; Daniel, D.E.; Eykholt, G.R.

    1997-05-01

    The hydraulic conductivity of calcium and sodium bentonites was investigated for sand-bentonite mixtures, a thin bentonite layer simulating a geosynthetic clay liner (GCL), and bentonite-cement mixtures simulating backfill for a vertical cutoff wall. The permeant liquids were tap water and distilled water containing 0.25 M calcium chloride. In general, the hydraulic performance of calcium bentonite was not significantly better than the performance of sodium bentonite for either the clay-amended sand or the GCL application, and was substantially worse than the performance of sodium bentonite in the bentonite-cement mixture. A drained angle of internal friction of 21{degree} was measured for calcium bentonite, compared to 10{degree} for sodium bentonite. Except for a larger drained shear strength, no advantage of calcium bentonite over sodium bentonite could be identified from the results of this study.

  15. [Removal of red tide organisms by organo-modified bentonite].

    PubMed

    Deng, Yuesong; Xu, Zirong; Xia, Meisheng; Ye, Ying; Hu, Caihong

    2004-01-01

    A series of organo-bentonites were synthesized by exchanging cation surfactants such as cyltrimethylammonium bromide and cetyltrimethylammonium to remove red tide organisms Skeletonema costatum. The results showed that the removal rate of Skeletonema costatum by the bentonites was in the order of cyltrimethylammonium surfactant modified iron pillared bentonite > cetyltrimethylammoium surfactant modified iron pillared bentonite > iron pillared bentonite > cyltrimethylammonium surfactant modified sodium bentonite > cetyltrimethylammoium surfactant modified > sodium bentonite. The removal rate of Skeletonema costatum was related to the length of alkyl chains and the amount of cation surfactants exchanged on bentonites.

  16. Kaolin-based geopolymers with various NaOH concentrations

    NASA Astrophysics Data System (ADS)

    Heah, C. Y.; Kamarudin, H.; Mustafa Al Bakri, A. M.; Bnhussain, M.; Luqman, M.; Khairul Nizar, I.; Ruzaidi, C. M.; Liew, Y. M.

    2013-03-01

    Kaolin geopolymers were produced by the alkali-activation of kaolin with an activator solution (a mixture of NaOH and sodium silicate solutions). The NaOH solution was prepared at a concentration of 6-14 mol/L and was mixed with the sodium silicate solution at a Na2SiO3/NaOH mass ratio of 0.24 to prepare an activator solution. The kaolin-to-activator solution mass ratio used was 0.80. This paper aimed to analyze the effect of NaOH concentration on the compressive strength of kaolin geopolymers at 80°C for 1, 2, and 3 d. Kaolin geopolymers were stable in water, and strength results showed that the kaolin binder had adequate compressive strength with 12 mol/L of NaOH concentration. When the NaOH concentration increased, the SiO2/Na2O decreased. The increased Na2O content enhanced the dissolution of kaolin as shown in X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses. However, excess in this content was not beneficial for the strength development of kaolin geopolymers. In addition, there was the formation of more geopolymeric gel in 12 mol/L samples. The XRD pattern of the samples showed a higher amorphous content and a more geopolymer bonding existed as proved by FTIR analysis.

  17. 21 CFR 184.1155 - Bentonite.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Bentonite. 184.1155 Section 184.1155 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DIRECT FOOD... hydrated aluminum silicate. Bentonite contains varying quantities of iron, alkalies, and alkaline earths...

  18. Determination of porewater chemistry in compacted bentonite

    SciTech Connect

    Lehikoinen, J.; Muurinen, A.; Melamed, A.; Pitkaenen, P.

    1997-12-31

    Laboratory experiments were performed to study the interaction between groundwater and compacted sodium bentonite (Volclay MX-80). The solutions used were the fresh and saline groundwater simulants. The experiments were carried out in aerobic and anaerobic conditions at elevated temperature. Of main interest in the present study were the chemical changes in the reacting solution, bentonite porewater, and bentonite itself. The results for major cations display a principal difference between the interactions with fresh and saline solutions, while the differences between aerobic and anaerobic conditions within each solution case seem to be minor. The experimental results for the bentonite-water equilibria were interpreted in terms of a multi-site surface complexation model and the computer program HYDRAQL. The apparent diffusivities for sodium and sulfate in bentonite samples sandwiched between two filter plates were also determined.

  19. Heteroaggregation of engineered nanoparticles and kaolin clays in aqueous environments.

    PubMed

    Wang, Hongtao; Dong, Ya-nan; Zhu, Miao; Li, Xiang; Keller, Arturo A; Wang, Tao; Li, Fengting

    2015-09-01

    The increasing and wide use of nanoparticles (NPs), including TiO2 and Ag NPs, have raised concerns due to their potential toxicity and environmental impacts. Kaolin is a very common mineral in aquatic systems, and there is a very high probability that nanoparticles (NPs) will interact with these clay minerals. We studied the effect of kaolin particles on the aggregation of NPs under different conditions, including the role of pH, ionic strength (IS), and humic acid (HA). We show that kaolin reduces the energy barrier and the Critical Coagulation Concentration (CCC) at pH 4. At pH 8, even though the energy barrier of the system without kaolin increases, kaolin promotes NP aggregation via heteroaggregation. When IS is equal to or greater than the CCC, on the one hand HA promotes aggregation of TiO2 NPs, but on the other hand HA decreases the rate of Ag NP aggregation because the existence of a surface coating may limit the adsorption of HA on these Ag NPs. In addition, the presence of HA increases the energy barrier and the CCC of the binary system (kaolin + NPs). Thus, the complex interactions of clay, NPs, IS, pH, and HA concentration determine the colloidal stability of the NPs. We find that kaolin is a potential coagulant for removal of NPs that behave like Ag and TiO2.

  20. Refractory Behaviors of Magnetite-Kaolin Bricks

    NASA Astrophysics Data System (ADS)

    Adeosun, S. O.; Akpan, E. I.; Gbenebor, O. P.; Taiwo, O. O.; Eke, I. J.

    2016-11-01

    In this work, the suitability of using kaolin-magnetite-plastic clay to produce refractory bricks has been experimentally explored. Thirty bricks of different compositions were produced and fired at 1200°C. The density, shrinkage moisture content, loss on ignition, porosity and permeability of the bricks were examined. Results show that the bricks remained stable during firing and thus possess good insulating characteristics. The highest (2.23 g/cm3) and lowest (2.00 g/cm3) bulk densities obtained in this study are higher than the highest bulk density reported for Al dross-filled refractories (1.23 g/cm3). The bricks also possessed very low effective moisture content (10-23%) and very high compression modulus (16-100 MPa) desirable in insulating refractory bricks with high resistance to abrasion.

  1. Rheological Behavior of Bentonite-Polyester Dispersions

    NASA Astrophysics Data System (ADS)

    Abu-Jdayil, Basim; Al-Omari, Salah Addin

    2013-07-01

    The rheological behavior of a bentonite clay dispersed in unsaturated polyester was investigated. The effects of the solid content and particle size on the steady and transient rheological properties of the dispersions were studied. In addition, two types of bentonite with different Na+/Ca+2 ratio were used in this study. The Herschel-Bulkley and the Weltman models were used to describe the apparent viscosity of the bentonite-polyester composite in relation to the shear rate and shearing time. The bentonite-polyester dispersions were found to exhibit both Newtonian and non-Newtonian behavior. The transition from a Newtonian to a Bingham plastic and then to a shear-thinning material with a yield stress was found to depend on the solid concentration, the particle size, and the type of bentonite. At a low solid content, the apparent viscosity of the bentonite dispersion increased linearly with solid concentration. But a dramatic increase in the apparent viscosity beyond a solid content of 20 wt.% was observed. On the other hand, a thixotropic behavior was detected in bentonite-polyester dispersions with a high solid content and a low particle size. However, this behavior was more pronounced in dispersions with a high Na+/Ca+2 ratio.

  2. Flocculation of kaolin and lignin by bovine blood and hemoglobin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Polymeric flocculants are used extensively for water purification, inhibition of soil erosion, and reduction in water leakage from unlined canals. Production of highly active, renewable polymeric flocculants to replace synthetic flocculants is a priority. Using suspensions of kaolin, flocculation ...

  3. Kaolin calciner waste heat and feed recovery system and method

    SciTech Connect

    Cummings, C.S.; Hudson, J.R.

    1988-01-05

    In the method for producing a calcined kaolin pigment product, by feeding an aqueous slurry of kaolin to a spray drier which is provided with heated gases from a combustor, feeding the dried kaolin product from the spray drier to a calciner; and recovering the calcined product; the improvement is described enabling recovery of heat energy and calciner dust from the calciner, comprising: cycling the hot exhaust gases and entrained calciner dust from the calciner back to the spray drier by joining the exhaust gases and calciner dust with the heated combustor gases being provided to the calciner; and collecting the calciner dust from the drier and providing same together with the dried kaolin product as feed to the calciner.

  4. On the asymmetric adsorption of phenylalanine enantiomers by kaolin.

    NASA Technical Reports Server (NTRS)

    Bonner, W. A.; Flores, J.

    1973-01-01

    The attempt is described to verify a recent report that kaolin adsorbs D- and L-phenylalanine enantiomers to different extents from aqueous solutions at both pH 5.8 and pH 2. No evidence whatsoever could be found for the differential adsorption of D- versus L-phenylalanine by kaolin from either pH 6 or pH 2 solutions.

  5. Rheological properties of kaolin and chemically simulated waste

    SciTech Connect

    Selby, C.L.

    1981-12-01

    The Savannah River Laboratory is conducting tests to determine the best operating conditions of pumps used to transfer insoluble radioactive sludges from old to new waste tanks. Because it is not feasible to conduct these tests with real or chemically simulated sludges, kaolin clay is being used as a stand-in for the solid waste. The rheology tests described herein were conducted to determine whether the properties of kaolin were sufficiently similar to those of real sludge to permit meaningful pump tests. The rheology study showed that kaolin can be substituted for real waste to accurately determine pump performance. Once adequately sheared, kaolin properties were found to remain constant. Test results determined that kaolin should not be allowed to settle more than two weeks between pump tests. Water or supernate from the waste tanks can be used to dilute sludge on an equal volume basis because they identically affect the rheological properties of sludge. It was further found that the fluid properties of kaolin and waste are insensitive to temperature.

  6. Enhanced oil-mineral aggregation with modified bentonite.

    PubMed

    Chen, Li; Zhou, Yanbo; Wang, Xiaoqian; Zwicker, Thomas; Lu, Jun

    2013-01-01

    The application of modified-bentonite-enhanced oil dispersion in water and oil-mineral aggregate (OMA) formation was studied in the laboratory. The effect of modification on the surface properties of bentonite was characterized. The hydrophobicity and surface electric properties of bentonite were significantly improved by attaching cetyltrimethyl ammonium bromide to its surface. The results showed that surface properties of bentonite played an important role in OMA formation. Spherical droplets of OMAs were formed with natural bentonite and elongated solid OMAs and flake OMAs were formed with modified bentonite as observed by fluorescence microscopy. The effects of shaking time, oil concentration and mineral content were also studied. It was suggested that oil concentration and mineral content were critical factors and OMA formed rapidly with both types of bentonite. Modified bentonite had better performance on OMA formation than hydrophilic natural bentonite.

  7. Saltwater and hard water bentonite mud

    SciTech Connect

    Pabley, A. S.

    1985-02-19

    A seawater/saltwater or hard water bentonite mud for use in drilling, and process for preparing same, comprising sequentially adding to seawater, to saltwater of a chloride concentration up to saturation, or hard water: a caustic agent; a filtration control agent; and bentonite. The resultant drilling mud meets API standards for viscosity and water loss, and is stable after aging and at tempertures in excess of 100/sup 0/ c. In another embodiment, the additives are premixed as dry ingredients and hydrated with seawater, saltwater or hard water. Unlike other bentonite drilling muds, the muds of this invention require no fresh water in their preparation, which makes them particularly useful at off-shore and remote on-shore drilling locations. The muds of this invention using bentonite further require less clay than known saltwater muds made with attapulgite, and provides superior filtration control, viscosity and stability.

  8. Effect of bentonites on fluorometric selenium determination

    SciTech Connect

    Olson, O.E.; Herr, A.A.; Palmer, I.S.

    1981-01-01

    Bentonites in feeds cause error in the analysis for Se by the AOAC (3.097-3.101) fluorometric method for Se in plants. The error apparently results from the binding of the piazselenol by insoluble residue from the bentonite. This effect is avoided by diluting digests to volume after reduction with HCl, centrifuging or allowing to stand, and analyzing a portion of the clear supernatant liquid. Insoluble residues present after digestion of plant materials do not appear to cause a similar error.

  9. HYDRAULIC CONDUCTIVITY OF SOME BENTONITES IN ARTIFICIAL SEAWATER

    NASA Astrophysics Data System (ADS)

    Komine, Hideo; Yasuhara, Kazuya; Murakami, Satoshi

    A high-level radioactive waste disposal facility might be built in a coastal area in Japan from the viewpoint of feasible transportation of waste. Therefore, it is important to investigate the effects of seawater on a bentonite-based buffer. This study investigated the influence of seawater on hydraulic conductivity of three common sodium-types of bentonite and one calcium-type bentonite by the laboratory experiments. From the results of laboratory experiment, this study discussed the influence of seawater on hydraulic conductivity of bentonites from the viewpoints of kinds of bentonite such as exchangeable-cation type and montmorillonite content and dry density of bentonite-based buffer.

  10. Preparation and Characterization of Ceramizable Kaolin/VMQ and Kaolin/ZB/VMQ Composites

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Qin, Y.; Pei, Y.; Huang, Z. X.

    Ceramizable silicone-based composite was prepared by using methyl vinyl silicone rubber (VMQ) as matrix, calcined Kaolin and zinc borate (ZB) as additives. This composition can form interpenetrating network structures after crosslinking, and then improve heat-resistant properties by firing in air. The results of different formulations were investigated by FTIR. TG-DTG SEM and XRD. It showed that when the temperature above 600°C. the fillers and silicon rubber started to transform from organic to inorganic and internal microstructure became denser.

  11. Role of bentonite clays on cell growth.

    PubMed

    Cervini-Silva, Javiera; Ramírez-Apan, María Teresa; Kaufhold, Stephan; Ufer, Kristian; Palacios, Eduardo; Montoya, Ascención

    2016-04-01

    Bentonites, naturally occurring clays, are produced industrially because of their adsorbent capacity but little is known about their effects on human health. This manuscript reports on the effect of bentonites on cell growth behaviour. Bentonites collected from India (Bent-India), Hungary (Bent-Hungary), Argentina (Bent-Argentina), and Indonesia (Bent-Indonesia) were studied. All four bentonites were screened in-vitro against two human cancer cell lines [U251 (central nervous system, glioblastoma) and SKLU-1 (lung adenocarcinoma)] supplied by the National Cancer Institute (USA). Bentonites induced growth inhibition in the presence of U251 cells, and growth increment in the presence of SKLU-1 cells, showing that interactions between bentonite and cell surfaces were highly specific. The proliferation response for U251 cells was explained because clay surfaces controlled the levels of metabolic growth components, thereby inhibiting the development of high-grade gliomas, particularly primary glioblastomas. On the other hand, the proliferation response for SKLU-1 was explained by an exacerbated growth favoured by swelling, and concomitant accumulation of solutes, and their hydration and transformation via clay-surface mediated reactions.

  12. Isothermal Dilatometric Study of Sintering in Kaolin

    NASA Astrophysics Data System (ADS)

    Ondruška, Ján; Trník, Anton; Keppert, Martin; Medved', Igor; Vozár, Libor

    2014-10-01

    Solid-state sintering for kaolin samples was studied by dilatometric measurements in the isothermal regime in the temperature range from 600 °C to 1100 °C. The relative expansion was measured for a period of 10h. For the temperatures up to 850 °C, we observed only a small shrinkage (less than 0.5 %), most of which took place within the first 3h of the measurements. For the temperatures above 850 °C, a significant shrinkage occurred for the whole measured time interval and reached up to 2.7 %. Anomalous behavior—a decrease in the shrinkage with the temperature—was observed in the range from 700 °C to 850 °C. The dilatometric measurements are supplemented by porosity distribution measurements. The standard spherical-grains microscopic model was applied to determine that for the initial stages of the sintering process, grain boundary diffusion was the dominant mechanism at lower temperatures (600 °C to 850 °C), whereas lattice diffusion was dominant at higher temperatures (900 °C, 1050 °C, and 1100 °C).

  13. Shear modulus of kaolin containing methane bubbles

    SciTech Connect

    Duffy, S.M. ); Wheeler, S.J. . Dept. of Engineering Science); Bennell, J.D. )

    1994-05-01

    Measurements of undrained shear moduli are reported from a program of laboratory tests on reconstituted kaolin samples containing relatively large bubbles of methane gas. The experimental program included low-frequency torsional stress-strain loops and torsional resonant column tests, providing values of shear moduli for shear-strain similitudes from 0.0004% to 0.1%. At all values of strain amplitude, the reduction of shear moduli caused by the presence of gas bubbles was greater than predicted by a theoretical elastic expression. This pattern of behavior was attributed to te formation of local yield zones around the gas-bubble cavities during consolidation prior to shear testing (a phenomenon that would also occur in-situ within offshore sediments). The results of the research program suggest that reductions in shear moduli of up to 50% could be caused by relatively small volumes of gas bubbles, occupying just a few percent of the total soil volume. This would have considerable significance for the displacements of offshore foundations constructed on sediments containing undissolved gas.

  14. Experimental study of colloid filtration by compacted bentonite

    SciTech Connect

    Kurosawa, Susumu; Yui, Mikazu; Yoshikawa, Hideki

    1997-12-31

    In this study, the transport behavior of colloids through compacted bentonite and sand-bentonite mixtures was investigated. Colloidal gold was used to simulate mobile colloids because it was well characterized and its dispersivity was controlled. The bentonite used was a sodium bentonite. The sand-bentonite mixtures were prepared by mixing up to 50 wt.% silica sand with the bentonite. The bentonite and the sand-bentonite mixtures were compacted to dry densities of 1,000 and 1,800 kg/m{sup 3} and then saturated with distilled water. The sand-bentonite mixture was also saturated with synthetic sea-water. Column experiments were performed to investigate colloidal transport. Further, colloidal particles stabilities in high ionic strength water such as bentonite porewater or saline groundwater were interpreted based on the repulsion potential from the double layer force and the attraction potential from the van der Waals force. The results indicated that the colloidal particles were effectively filtered by both the compacted bentonite and the sand-bentonite mixtures. This study indicated that the effect of colloids on radionuclide transport in compacted bentonite is negligible for the safety assessment of high level radioactive waste (HLW) disposal.

  15. Hydrocephalus induced via intraventricular kaolin injection in adult rats.

    PubMed

    Shaolin, Z; Zhanxiang, W; Hao, X; Feifei, Z; Caiquan, H; Donghan, C; Jianfeng, B; Feng, L; Shanghang, S

    2015-01-01

    Hydrocephalus is a common neurological disease in humans, but a uniform and particularly effective hydrocephalic animal model amenable to proper appraisal and deep study has not yet been established. In this study, we attempted to construct a high-efficiency model of hydrocephalus via intraventricular kaolin injection. Adult male Sprague-Dawley rats were randomly divided into 2 groups: the control group (n = 15) and the experimental group (n = 30). Kaolin was injected into the lateral ventricle of experimental animals. Control rats underwent the same procedure but received sterile saline injection instead of kaolin. All animals with kaolin injection into the lateral ventricle developed hydrocephalus according to magnetic resonance imaging (MRI) results (success rate up to 100%). Also, the Morris water maze (MWM) test demonstrated disturbed spatial learning and memory. Furthermore, there were significant differences between groups with respect to the histological changes in the periventricular tissue. Our results indicate that experimental hydrocephalus induced by lateral ventricle injection of kaolin in adult rats is feasible and may be widely used.

  16. Using Kaolin in Reduction of Arsenic in Rice Grains: Effect of Different Types of Kaolin, pH and Arsenic Complex.

    PubMed

    Arnamwong, Suteera; Suksabye, Parinda; Thiravetyan, Paitip

    2016-04-01

    Kaolin was used as a soil amendment to study the effect of different types of kaolin, pH and arsenic complex on arsenic accumulation in rice grains from arsenic (As) contaminated soil. It was found that kaolin released soluble aluminium (Al) and silicon at a pH value of 3. As adsorption by crude kaolin was higher than by washed kaolin and treated kaolin due to the higher Al content found in crude kaolin. Furthermore, the addition of 5 % (w/w) crude kaolin in the solution of As-contaminated soil was able to reduce water-soluble As in the solution. In mesocosm experiments, As accumulation in rice grain was not found under the addition of kaolin conditions. Scanning electron microscopy with energy dispersive X-ray spectroscopy study found the crystallinity of Al-As complex in plant roots. This implies that while kaolin adsorbs As from As-contaminated soil, rice plants also simultaneously take up As and Al into their cells. This caused the decrease in As accumulation in rice grain.

  17. 40 CFR 180.1180 - Kaolin; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Kaolin; exemption from the requirement... From Tolerances § 180.1180 Kaolin; exemption from the requirement of a tolerance. (a) The biochemical pesticide kaolin is temporarily exempted from the requirement of a tolerance for residues of the...

  18. 40 CFR 180.1180 - Kaolin; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Kaolin; exemption from the requirement... From Tolerances § 180.1180 Kaolin; exemption from the requirement of a tolerance. (a) The biochemical pesticide kaolin is temporarily exempted from the requirement of a tolerance for residues of the...

  19. 40 CFR 180.1180 - Kaolin; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Kaolin; exemption from the requirement... From Tolerances § 180.1180 Kaolin; exemption from the requirement of a tolerance. (a) The biochemical pesticide kaolin is temporarily exempted from the requirement of a tolerance for residues of the...

  20. 40 CFR 180.1180 - Kaolin; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Kaolin; exemption from the requirement... From Tolerances § 180.1180 Kaolin; exemption from the requirement of a tolerance. (a) The biochemical pesticide kaolin is temporarily exempted from the requirement of a tolerance for residues of the...

  1. Apatite formation on calcined kaolin-white Portland cement geopolymer.

    PubMed

    Pangdaeng, S; Sata, V; Aguiar, J B; Pacheco-Torgal, F; Chindaprasirt, P

    2015-06-01

    In this study, calcined kaolin-white Portland cement geopolymer was investigated for use as biomaterial. Sodium hydroxide and sodium silicate were used as activators. In vitro test was performed with simulated body fluid (SBF) for bioactivity characterization. The formation of hydroxyapatite bio-layer on the 28-day soaked samples surface was tested using SEM, EDS and XRD analyses. The results showed that the morphology of hydroxyapatite was affected by the source material composition, alkali concentration and curing temperature. The calcined kaolin-white Portland cement geopolymer with relatively high compressive strength could be fabricated for use as biomaterial. The mix with 50% white Portland cement and 50% calcined kaolin had 28-day compressive strength of 59.0MPa and the hydroxyapatite bio-layer on the 28-day soaked sample surface was clearly evident.

  2. Use of airborne gamma-ray spectrometry for kaolin exploration

    NASA Astrophysics Data System (ADS)

    Tourlière, B.; Perrin, J.; Le Berre, P.; Pasquet, J. F.

    2003-08-01

    Airborne gamma-ray spectrometry was used to define targets with kaolin potential in the Armorican Massif of Brittany, France. This exploration method is based on the principle that kaolinite, an aluminosilicate clay mineral constituting kaolin, is formed by the hydrolysis of potash feldspar with the elimination of potassium. Therefore, potassium contrast between favourable host-rock such as a leucogranite and kaolin occurrence is likely a significant pathfinder. As the relationship between the potassium-40 recorded by an airborne gamma-ray spectrometer and total potassium is constant, such data provide us a direct measurement of the potassium content of the ground flown over. Our study tested this by calculating, for each geological unit, the difference between the measured and average potassium content calculated for a given geological formation. The study was based on (i) a recent (1998) high-definition airborne geophysical survey over the Armorican Massif undertaken on behalf of the French Government, and (ii) new geological compilation maps covering the same region. Depleted zones, where the measured potassium is less than the average potassium content calculated target areas with high potential of containing kaolin, provided that the unit was originally rich in potash feldspar. By applying this method to the entire Armorican Massif, it was possible to identify 150 potassium-depleted zones, including 115 that were subjected to rapid field checks and 36 that contained kaolin (21 new discoveries). This method, which is both safe for the environment and easy to use, is therefore a good tool for rapidly defining targets with kaolin potential at a regional scale. The method may also have possibilities in exploring for other types of deposit characterised by an enrichment or depletion in U, K and/or Th.

  3. Unsaturated hydraulic conductivity of compacted sand-kaolin mixtures

    SciTech Connect

    Chiu, T.F.; Shackelford, C.D.

    1998-02-01

    The unsaturated hydraulic conductivity of compacted sand-kaolin mixtures containing 0, 5, 10, and 30% kaolin (by dry weight) is measured for matric suctions, {psi}{sub m} < {approximately} 6.0 m. The measured unsaturated hydraulic conductivity (k{sub m}) values are compared with predicted unsaturated hydraulic conductivity (k{sub p}) values using the Brooks-Corey-Burdine and van Genuchten-Mualem relative hydraulic conductivity functions. In general, the accuracy of k{sub p} decreases with an increase in kaolin content or an increase in {psi}{sub m}. In addition, k{sub m} tends to be underpredicted for kaolin contents of 10 and 30% at relatively high suctions (1.0 m {le} {psi}{sub m} {le} 6.0 m) and overpredicted for kaolin contents of 0 and 5% at relatively low suctions (0.1 m {le} {psi}{sub m} < 1.0 m). For a given kaolin content and {psi}{sub m}, k{sub p} based on the Brooks-Corey-Burdine function tends to be more accurate than k{sub m} based on the van Genuchten-Mualem function. Finally, for 1.0 m {le} {psi}{sub m} {le} 6.0 m, k{sub p} based on analysis using the maximum volumetric water content ({theta}{sub m}) attained under steady-state flow conditions typically is more accurate than k{sub p} based on analysis using the saturated volumetric water content, {theta}{sub s}, where {theta}{sub m} {approximately} 84--90% of {theta}{sub s} in this study.

  4. Pemirolast reduces cisplatin-induced kaolin intake in rats.

    PubMed

    Tatsushima, Yoko; Egashira, Nobuaki; Matsushita, Naohiro; Kurobe, Kentaro; Kawashiri, Takehiro; Yano, Takahisa; Oishi, Ryozo

    2011-07-01

    Emesis is the most feared side effect in patients who are undergoing cancer chemotherapy. In particular, cisplatin causes severe acute and delayed emesis. Although early vomiting is well controlled by 5-hydroxytryptamine 3 (5-HT(3)) receptor antagonists, delayed-phase vomiting is not sufficiently controlled. Substance P is thought to be involved in the development of emesis, and tachykinin NK(1) receptor antagonists can inhibit delayed vomiting. We previously have reported that substance P is involved in the paclitaxel-induced hypersensitivity reaction in rats, and anti-allergic agent pemirolast reduces these reactions via inhibition of substance P release. In the present study, we investigated the effect of pemirolast on cisplatin-induced kaolin intake, which is an index of nausea/vomiting in the rat. Cisplatin (5 mg/kg, i.p.) induced kaolin intake and reduced normal feed intake from days 1 to 5 after injection. Cisplatin-induced kaolin intake was significantly reduced by co-administration of ondansetron (2 mg/kg, i.p.), a 5-HT(3) receptor antagonist, and dexamethasone (2 mg/kg, i.p.) from days 1 to 5. Similarly, pemirolast (10 mg/kg, p.o.) and the tachykinin NK(1) receptor antagonist aprepitant (10 and 30 mg/kg, p.o.) significantly reduced cisplatin-induced kaolin intake on days 3 and 4. Moreover, pemirolast at the same dose significantly reversed the cisplatin-induced increase in the cerebrospinal fluid level of substance P in rats. These results suggest that substance P is involved in cisplatin-induced kaolin intake in rats, and pemirolast reduces kaolin intake by inhibition of substance P release.

  5. Comparison of kaolin and tissue factor activated thromboelastography in haemophilia.

    PubMed

    Young, G; Zhang, R; Miller, R; Yassin, D; Nugent, D J

    2010-05-01

    A limitation of bypassing agent therapy for haemophilia patients with inhibitors is the absence of a laboratory assay, which predicts the clinical response to treatment. Recent investigations have demonstrated the potential for thromboelastography to assess the effects of bypassing agent therapy in this patient population. While tissue factor activation has been used in several prior studies, a recent multicentre study failed to demonstrate an expected concentration-response effect of rFVIIa and called into question the tissue factor activation methods that have been employed. A comparison of kaolin to two concentrations of tissue factor as the activation method for thromboelastography was investigated in patients with haemophilia. We performed kaolin and tissue factor activated thromboelastography on blood from inhibitor and non-inhibitor patients with and without addition of rFVIIa and rFVIII. The results demonstrate that kaolin leads to a longer R, K and angle than the higher dilution of tissue factor (1:17 000) at baseline (no factor) and after addition of rFVIIa for both the inhibitor and non-inhibitor patients. Kaolin led to a longer R and K in comparison to a low dilution of tissue factor (1:42 000) following the addition of rFVIIa in the inhibitor patients. The longer R and K allows for better discrimination of the effects of rFVIIa thus making kaolin the most sensitive activation method in this setting. Thus kaolin activated thromboelastography should be considered an effective, perhaps the most effective, activator when utilizing thromboelastography to assess the effects of rFVIIa in haemophilia patients with inhibitors.

  6. Kaolin Quality Prediction from Samples: A Bayesian Network Approach

    SciTech Connect

    Rivas, T.; Taboada, J.; Ordonez, C.; Matias, J. M.

    2009-08-13

    We describe the results of an expert system applied to the evaluation of samples of kaolin for industrial use in paper or ceramic manufacture. Different machine learning techniques - classification trees, support vector machines and Bayesian networks - were applied with the aim of evaluating and comparing their interpretability and prediction capacities. The predictive capacity of these models for the samples analyzed was highly satisfactory, both for ceramic quality and paper quality. However, Bayesian networks generally proved to be the most useful technique for our study, as this approach combines good predictive capacity with excellent interpretability of the kaolin quality structure, as it graphically represents relationships between variables and facilitates what-if analyses.

  7. Bauxite and Kaolin Deposits of the Irwinton district, Georgia

    USGS Publications Warehouse

    Lang, Walter B.; Warren, Walter C.; Thompson, Raymond M.; Overstreet, Elizabeth F.

    1965-01-01

    The Irwinton district is in the central part of Georgia at the inner margin of the Coastal Plain province. The oldest rocks exposed in the district are crystalline rocks of the Piedmont province. They are unconformably overlain by nonmarine sedimentary strata of Late Cretaceous age, including gravel, micaceous sand, and lenses of kaolin. Bauxite has been found in a few of the kaolin lenses near the top of the sequence of these strata. During a long period prior to deposition of the over- lying marine beds of the Claiborne and Jackson Groups (middle and upper Eocene), the Upper Cretaceous strata were subjected to subaerial erosion. The bauxite deposits are considered to have formed during this period. They range in thickness from a few inches to more than 10 feet and occupy areas ranging from a few square feet to more than 5 acres. Most of the known bauxite deposits lie along the valleys of Commissioners Creek and Big Sandy Creek in Wilkinson County. The kaolin lenses are much larger than the bauxite deposits; some of the lenses underlie more than 200 acres and are more than 20 feet thick. Bauxite was discovered in the district in 1907 and was mined from 1910 to 1928. A few additional carloads of ore were shipped in 1941 and 1942, but no ore has been mined since that time. Reserves of high-grade bauxite are very small. Reserves of all grades of bauxite plus bauxitic clay may be about 400,000 long tons. The Irwinton district is the principal source of high-grade kaolin in the United States. The presence of kaolin here has been known since early colo- nial time, and it has been mined continuously since 1897. Production in 1959 was 1,940,279 short tons. The reserves of kaolin are very large but have never been adequately measured. Reserves of first and second grade kaolin may be 67 to 84 million short tons. Kaolin of lower grade is present in larger quantity.

  8. Evaluation of geothermal drilling fluids using a commercial bentonite and a bentonite/saponite mixture

    SciTech Connect

    Guven, N.; Carney, L.L.; Ridpath, B.E.

    1987-02-01

    High temperature properties of two clay fluids, based on commercially available bentonite and a bentonite-saponite mixture, are evaluated at the temperature range 300-600/sup 0/F under appropriate confining pressures up to 16,000 psi. Bentonite fluids exhibit an anomolous viscosity increase in the temperature range 250-400/sup 0/F. This anomolous viscosity is further enhanced by the salts and hydroxide of sodium leading to the gelation of the fluid. Salts and hydroxide of calcium at 1% concentrations are very detrimental to the viscosity, gel strength, and wall-building (filtration) properties of the fluids at all temperatures. Salts of potassium provide a good control over the high temperature gelation of the bentonite fluids but they result in high fluid losses. High and low molecular weight polymers (sodium polyacrylates), and lignite and lignosulfonates at neutral pH range are proved to be valuable mud additives for the high temperature behavior of the bentonite fluids. They maintain the pH of the fluid close to the neutral and thus inhibit the mineral reactions of the smectites in bentonites at high temperatures. These mineral reactions predominate in the alkaline conditions of the fluids in the presence of hydroxides of Na, Ca, and K. Consequently, a large portion of smectites dissolves and new silicate phases precipitate at and above 400/sup 0/F in these fluids. The fluids based on a (1:1) mixture of bentonite and saponite display a high initial viscosity (up to 250/sup 0/F) instead of the viscosity maxima between 150-400/sup 0/F of the bentonite fluids. Therefore, the addition of saponite to the bentonite fluid can provide a balanced viscosity at all the temperatures.

  9. Sealing performance of bentonite and bentonite/crushed rock borehole plugs

    SciTech Connect

    Ouyang, S.; Daemen, J.J.K.

    1992-07-01

    This study includes a systematic investigation of the sealing performance of bentonite and bentonite/crushed rock plugs. American Colloid C/S granular bentonite and crushed Apache Leap tuff have been mixed to prepare samples for laboratory flow testing. Bentonite weight percent and crushed tuff gradation are the major variables studied. The sealing performance assessments include high injection pressure flow tests, polyaxial flow tests, high temperature flow tests, and piping tests. The results indicate that a composition to yield a permeability lower than 5 {times} 10{sup {minus}8} cm/s would have at least 25% bentonite by weight mixed with well-graded crushed rock. Hydraulic properties of the mixture plugs may be highly anisotropic if significant particle segregation occurs during sample installation and compaction. Temperature has no significant effect on the sealing performance within the test range from room temperature to 600{degree}C. Piping damage to the sealing performance is small if the maximum hydraulic gradient does not exceed 120 and 280 for samples with a bentonite content of 25 and 35%, respectively. The hydraulic gradients above which flow of bentonite may take place are deemed critical. Analytical work includes the introduction of bentonite occupancy percentage and water content at saturation as two major parameters for plug design. A permeability model is developed for the prediction of permeability in clays, especially in view of the difficulties in obtaining this property experimentally. A piping model is derived based on plastic flow theory. This piping model permits the estimation of critical hydraulic gradients at which flow of bentonite takes place. The model can also be used to define the maximum allowable pore diameter of a protective filter layer.

  10. Diffusion of uranium in compacted sodium bentonite

    SciTech Connect

    Muurinen, A.; Ollila, K.; Lehikoinen, J.

    1993-12-31

    In this study the diffusion of uranium dissolved from uranium oxide fuel was studied experimentally in compacted sodium bentonite (Wyoming bentonite MX-80). The parameters varied in the study were the density of bentonite, the salt content of the solution and the redox conditions. In the studies with non-saline water of total dissolved solids about 300 ppm, uranium was both in aerobic and anaerobic experiments as anionic complexes and followed the anionic diffusion mechanism. Anion exclusion decreased effective diffusion coefficients, especially in more dense samples. In the studies with saline water of total dissolves solids about 35000 ppm, uranium appeared in the aerobic experiments probably as cationic complexes and followed the cationic diffusion mechanism. Uranium in the saline, anaerobic experiment was probably U(OH){sub 4} and followed the diffusion mechanism of neutral species.

  11. Bentonite debris flows in northern alaska.

    PubMed

    Anderson, D M; Reynolds, R C; Brown, J

    1969-04-11

    Seasonal freezing and thawing and the extreme cold of the arctic lead to the development of a variety of characteristic geomorphic features. A new one, bentonite debris flow channels, has been identified near Umiat, Alaska. These flows form when bentonite-rich Cretaceous Shales are exposed to Surface water on slopes of 5 to 30 degrees. The characteristic landform developed is a U-shaped channel 1 to 2 meters deep and from 8 to 10 meters in width. The channel shows a fluted floor and walls and is commonly flanked by a levee. The flow material is appa rently derived from the entire surface of the head portions of associated gullies. When this surface layer hydrates during snowmelt and runoff or during prolonged rain, the bentonite imbibes water and swells to a point at which its viscosity is lowered sufficiently to initiate creep or viscous flow.

  12. Intercalation of Europium (III) species into bentonite

    SciTech Connect

    Sanchez, A.; Echeverria, Y.; Torres, C.M. Sotomayor; Gonzalez, G.; Benavente, E. . E-mail: ebenaven@uchile.cl

    2006-06-15

    It is shown that the intercalation of [Europium(bipyridine){sub 2}]{sup 3+} into bentonite results in a new nanocomposite which preserves the emission properties of Europium (III). The exchange of sodium by europium in bentonite is correlated with the cation exchange capacity and molecular size. The intercalated complex exhibits luminescence where both the 2,2-bipyridine 'antenna' effect and the intensity maxima are comparable to the free complex suggesting that clay intercalated with rare earths may results in novel optical materials.

  13. Acid-base properties of bentonite rocks with different origins.

    PubMed

    Nagy, Noémi M; Kónya, József

    2006-03-01

    Five bentonite samples (35-47% montmorillonite) from a Sarmatian sediment series with bentonite sites around Sajóbábony (Hungary) is studied. Some of these samples were tuffogenic bentonite (sedimentary), the others were bentonitized tuff with volcano sedimentary origin. The acid-base properties of the edge sites were studied by potentiometric titrations and surface complexation modeling. It was found that the number and the ratio of silanol and aluminol sites as well as the intrinsic stability constants are different for the sedimentary bentonite and bentonitized tuff. The characteristic properties of the edges sites depend on the origins. The acid-base properties are compared to other commercial and standard bentonites.

  14. Bentonite as a waste isolation pilot plant shaft sealing material

    SciTech Connect

    Daemen, J.; Ran, Chongwei

    1996-12-01

    Current designs of the shaft sealing system for the Waste Isolation Pilot Plant (WIPP) propose using bentonite as a primary sealing component. The shaft sealing designs anticipate that compacted bentonite sealing components can perform through the 10,000-year regulatory period and beyond. To evaluate the acceptability of bentonite as a sealing material for the WIPP, this report identifies references that deal with the properties and characteristics of bentonite that may affect its behavior in the WIPP environment. This report reviews published studies that discuss using bentonite as sealing material for nuclear waste disposal, environmental restoration, toxic and chemical waste disposal, landfill liners, and applications in the petroleum industry. This report identifies the physical and chemical properties, stability and seal construction technologies of bentonite seals in shafts, especially in a saline brine environment. This report focuses on permeability, swelling pressure, strength, stiffness, longevity, and densification properties of bentonites.

  15. FT-IR and XRD analysis of natural Na-bentonite and Cu(II)-loaded Na-bentonite.

    PubMed

    Zhirong, Liu; Azhar Uddin, Md; Zhanxue, Sun

    2011-09-01

    Na-bentonite has been studied extensively because of its strong adsorption capacity and complexation ability. In this work, surface area, total pore volume, mean pore diameter, TG, DTA, FT-IR and XRD were carried out in order to reveal the characteristics of natural Na-bentonite. XRD and FT-IR of natural Na-bentonite (China) and Cu-loaded Na-bentonite as a function of Na-bentonite dosage and temperature using batch technique were characterized in detail, respectively.

  16. FT-IR and XRD analysis of natural Na-bentonite and Cu(II)-loaded Na-bentonite

    NASA Astrophysics Data System (ADS)

    Zhirong, Liu; Azhar Uddin, Md.; Zhanxue, Sun

    2011-09-01

    Na-bentonite has been studied extensively because of its strong adsorption capacity and complexation ability. In this work, surface area, total pore volume, mean pore diameter, TG, DTA, FT-IR and XRD were carried out in order to reveal the characteristics of natural Na-bentonite. XRD and FT-IR of natural Na-bentonite (China) and Cu-loaded Na-bentonite as a function of Na-bentonite dosage and temperature using batch technique were characterized in detail, respectively.

  17. Fabrication of facing tiles for floors from kaolin ash composites

    SciTech Connect

    Sirazhiddinov, N.A.; Irkakhodzhaeva, A.P.; Kasimova, G.A.

    1994-09-01

    Many enterprises in the ceramics industry are increasingly widely using different production wastes, fuel slag in particular, due to the limited ability to ensure standardized raw materials. We attempted to investigate the use of ash slag from the Angrensk Thermoelectric Power Plant (TEPP) in composites with kaolin - waste from coal concentration for the Angrensk coal pit.

  18. Dioxins in primary kaolin and secondary kaolinitic clays.

    PubMed

    Schmitz, Martin; Scheeder, Georg; Bernau, Sarah; Dohrmann, Reiner; Germann, Klaus

    2011-01-15

    Since 1996 dioxins have been repeatedly detected worldwide in Tertiary ball clays used as anticaking agent in the production of animal feed and a variety of other applications. The dioxins of these natural clays are very unlikely of anthropogenic source, but no model of dioxin enrichment has been established. A hypothetical model is presented which explains the highly variable dioxin loadings of the Tertiary kaolinitic clays by natural addition during clay-sedimentation. To prove this hypothesis, Tertiary primary nonsedimentary kaolin and sedimentary kaolinitic clays were collected at three profiles in Europe and analyzed for mineralogy, chemistry, organic carbon, and polychlorinated dibenzo-p-dioxins/-furans (PCDD/F). Primary kaolin, kaolinitic, and lignitic clays contained almost no PCDFs. PCDD concentration differed markedly between primary kaolin (3-91 pg/g) and secondary kaolinitic clay (711-45935 pg/g), respectively, lignitic clays (13513-1191120 pg/g). The dioxin loading of secondary kaolinitic and lignitic clays is approximately 10 to a few thousand times higher than in the primary kaolin or recent environmental settings. The dioxin concentrations decrease from octachlorodibenzo-p-dioxin to the tetrachlorodibenzo-p-dioxins and exhibit the "natural formation pattern". No correlation between PCDD/F concentration and bulk composition of clays was found. These findings support the hypothesis of the enrichment of dioxin in clays during sedimentation.

  19. Adsorption characteristics of brilliant green dye on kaolin.

    PubMed

    Nandi, B K; Goswami, A; Purkait, M K

    2009-01-15

    Experimental investigations were carried out to adsorb toxic brilliant green dye from aqueous medium using kaolin as an adsorbent. Characterization of kaolin is done by measuring: (i) particle size distribution using particle size analyzer, (ii) BET surface area using BET surface analyzer, and (iii) structural analysis using X-ray diffractometer. The effects of initial dye concentration, contact time, kaolin dose, stirring speed, pH and temperature were studied for the adsorption of brilliant green in batch mode. Adsorption experiments indicate that the extent of adsorption is strongly dependent on pH of solution. Free energy of adsorption (DeltaG0), enthalpy (DeltaH0) and entropy (DeltaS0) changes are calculated to know the nature of adsorption. The calculated values of DeltaG0 at 299K and 323K indicate that the adsorption process is spontaneous. The estimated values of DeltaH0 and DeltaS0 both show the negative sign, which indicate that the adsorption process is exothermic and the dye molecules are organized on the kaolin surface in less randomly fashion than in solution. The adsorption kinetic has been described by first-order, pseudo-second-order and intra-particle-diffusion models. It was observed that the rate of dye adsorption follows pseudo-second-order model for the dye concentration range studied in the present case. Standard adsorption isotherms were used to fit the experimental equilibrium data. It was found that the adsorption of brilliant green on kaolin follows the Langmuir adsorption isotherm.

  20. [Flocculation of kaolin suspensions by chitosan grafted ternary polymerization flocculant].

    PubMed

    Hu, Yong-you; Li, Si-qing; Guo, Yan-ping; Cheng, Jian-hua

    2008-04-01

    Flocculation of kaolin suspensions using ternary polymerization flocculant (CAS) synthesized by chitosan (CTS), acrylamide and ethyl acrylate quaternary ammonium salt was investigated in lab-scale. It was found that CAS had more advantages such as higher flocculation efficiency, lesser dosage and wider pH flocculation range than CTS. CAS was insignificantly exposed to the properties of suspended particles, so preferable flocculation efficiency by it could be obtained both with distilled water and tap water kaolin suspensions. The optimal dosage for CAS was only one-tenth of that of CTS in neutral condition. Good flocculation performance was observed in the pH range of 2.0-11.0 at the dosage of 0.5 mg x L(-1) CAS, and the turbidity removal rates were about 95%. It was also shown that flocculation efficiency was very sensitive to the raw turbidity of kaolin suspensions. At less than 0.5 mg x L(-1) of CAS dose, the higher raw turbidity of the suspension contrarily yielded a lower removing rate. However, when the dosage of CAS was more than 0.5 mg x L(-1), the flocculation efficiency increased with increasing the raw turbidity of kaolin. When the dosage was more than 1.0 mg x L(-1), turbidity removal efficiencies exceeding 85% could be achieved in overall experimental turbidities from 10 to 160 NTU. iPDA-100 device was used to follow the particle aggregation process. And also zeta potential values of particles,floc sizes, shape analyses were presented. It is presumed that the flocculation induced by CAS is dominated by charge patch mechanism and bond bridging. The flocculation reactivity of kaolin suspensions exhibits a dynamic changing, which is simultaneously responsible for several kinds of driving forces.

  1. 21 CFR 184.1155 - Bentonite.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Bentonite. 184.1155 Section 184.1155 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN..., and alkaline earths in the commercial products. Depending on the cations present, natural deposits...

  2. 21 CFR 184.1155 - Bentonite.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of Specific... ingredient as generally recognized as safe (GRAS) as a direct human food ingredient is based upon the... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Bentonite. 184.1155 Section 184.1155 Food and...

  3. Effect of kaolin on fitness and behavior of Choristoneura rosaceana (Lepidoptera: Tortricidae) larvae.

    PubMed

    Sackett, T E; Buddle, C M; Vincent, C

    2005-10-01

    The mechanisms by which kaolin, a clay particle film formulation, affects the fitness and behavior of larvae of obliquebanded leafroller, Choristoneura rosaceana (Harris), were investigated. Feeding experiments tested kaolin as a physical barrier versus a physiological toxin for larvae that consumed kaolin applied either to apple (Malus spp.) leaves or mixed in artificial diet. Behavioral experiments tested the effects of kaolin applied to apple leaves on neonate dispersal and leaf rolling by third and fourth instars. When larvae fed on apple leaves sprayed with kaolin, mortality and time to pupation of larvae increased significantly, whereas pupal mass significantly decreased. When larvae consumed kaolin mixed into an artificial diet, however, the effects on mortality, pupation time, and pupal mass were negligible. There may be minor physiological effects from consumption because male time to pupation was delayed for larvae fed diets containing the highest concentration of kaolin. In behavioral experiments, neonate larvae dispersed more quickly off plants covered with kaolin than control plants, and kaolin delayed the construction of leaf shelters by third and fourth instars. We showed that the effects of kaolin on C. rosaceana larvae are primarily physical, causing changes in dispersal and rolling behaviors and as a physical barrier to feeding.

  4. Evaluation of factors affecting diffusion in compacted bentonite

    SciTech Connect

    Lehikoinen, J.; Carlsson, T.; Muurinen, A.; Olin, M.; Salonen, P.

    1996-08-01

    The information available from the open literature and studies on exclusion, sorption and diffusion mechanisms of ionic and neutral species in bentonite has been compiled and re-examined in relation to the microstructure of bentonite. The emphasis is placed on a more thorough understanding of the diffusion processes taking place in compacted bentonite. Despite the scarcity of experiments performed with neutral diffusants, these imply that virtually all the pores in compacted bentonite are accessible to neutral species. Anion exclusion, induced by the overlap of electrical double layers, may render the accessible porosity for anions considerably less than the porosity obtained from the water content of the clay. On the basis of the compiled data, it is highly probable that surface diffusion plays a significant role in the transport of cations in bentonite clays. Moreover, easily soluble compounds in bentonite can affect the ionic strength of porewater and, consequently, exclusion, equilibrium between cations, and surface diffusion.

  5. Large-scale superconducting separator for Kaolin processing

    SciTech Connect

    Winters, A.J, Jr. ); Selvaggi, J.A. )

    1990-01-01

    Currently, high gradient magnetic separators (HGMSs) are used almost exclusively by the clay processing industry, particularly in producing an extremely white kaolin for the paper, coatings and rubber industries where a bright additive is desirable. As mined, the clay is a light cream color-not white. Many of these impurities can be removed chemically using a reducing agent such as sodium hydrosulfite in low pH, sulfuric acid, and alum. High purity, however, can be obtained by removing trace amounts of paramagnetic particles (100% finer than 2 {mu}m). This is accomplished by separating these particles from 28 wt% kaolin in a water slurry retaining them on magnetic wool, which is then periodically regenerated.

  6. Refractory Characteristics of Aluminum Dross-Kaolin Composite

    NASA Astrophysics Data System (ADS)

    Adeosun, S. O.; Akpan, E. I.; Dada, M. O.

    2014-11-01

    The suitability of using aluminum dross waste and kaolin to produce refractory bricks is experimentally studied. Thirty brick samples of different blends are produced, dried at 30°C, dried further at 110°C, and fired at 1200°C. The firing temperature point, bulk density, apparent porosity, thermal conductivity, thermal shock, loss on ignition, permeability, shatter index, and shrinkage of the bricks blends are determined. The results show that some blend samples have good refractory characteristics with mixing ratio 4:1:2 (representing weight in grams of aluminum dross, plastic clay, and kaolin, respectively). The evaluations of studied properties reveal the possibility for aluminum dross waste to be used as matrix in refractory bricks.

  7. Bentonite Clay Adsorption Procedure for Concentrating Enteroviruses from Water.

    DTIC Science & Technology

    1992-07-01

    AD-A255 305 _ TECHNICAL REPORT 9203 BENTONITE CLAY ADSORPTION PROCEDURE FOR CONCENTRATING ENTEROVIRUSES FROM WATER STEPHEN A. SCHAUB D T IC GORDON W...Bentonite Clay Adsorption Procedure for Concentrating Enteroviruses from Water 12. PERSONAL AUTHOR(S) S.A. Schaub, G.W. Taylor, C.A. Sorber, and W.E...number) L/ A method of adsorbing enteroviruses to bentonite clay was developed for use as a concentration technique designed to sample low levels of

  8. PCR-DGGE analysis of the bacterial composition of a kaolin slurry showing altered rheology.

    PubMed

    Papp, Ildikó; Balázs, Margit; Tombácz, Etelka; Babcsán, Norbert; Kesserű, Péter; Kiss, István; Szvetnik, Attila

    2012-04-01

    Kaolin is an important industrial raw material and a basis of a range of different products. Microbial spoilage is a detrimental process observed especially in kaolin slurries, leading to low quality products and economic loss. Although the alteration of kaolin slurries in ceramic industry was observed, the process and the microbial background have not been analyzed in details. This study provides the first data using a cultivation independent molecular biological approach (PCR-DGGE) regarding the bacterial composition of an altered kaolin slurry. The results show that potential exopolymer (EPS) producer bacteria (e.g. Acinetobacter, Pseudomonas) appear in the altered kaolin slurry, which may have an important role in the modification of kaolin slurries.

  9. Removal of copper ions from aqueous solution by calcium alginate immobilized kaolin.

    PubMed

    Li, Yanhui; Xia, Bing; Zhao, Quansheng; Liu, Fuqiang; Zhang, Pan; Du, Qiuju; Wang, Dechang; Li, Da; Wang, Zonghua; Xia, Yanzhi

    2011-01-01

    Kaolin has been widely used as an adsorbent to remove heavy metal ions from aqueous solutions. However, the lower heavy metal adsorption capacity of kaolin limits its practical application. A novel environmental friendly material, calcium alginate immobilized kaolin (kaolin/CA), was prepared using a sol-gel method. The effects of contact time, pH, adsorbent dose, and temperature on Cu2+ adsorption by kaolin/CA were investigated. The Langmuir isotherm was used to describe the experimental adsorption, the maximum Cu2+ adsorption capacity of the kaolin/CA reached up to 53.63 mg/g. The thermodynamic studies showed that the adsorption reaction was a spontaneous and endothermic process.

  10. Suction characteristics of compacted zeolite-bentonite and sand-bentonite mixtures.

    PubMed

    Durukan, Seda; Pulat, Hasan Firat; Yukselen-Aksoy, Yeliz

    2014-02-01

    Soil suction is one of the most important parameters describing soil moisture conditions for unsaturated soils used in landfill liners. However, few studies have been conducted on the suction characteristics of compacted zeolite-bentonite mixtures (ZBMs) and sand-bentonite mixtures (SBMs), which are proposed for use as liner materials. Nevertheless, zeolite is known for its microporous skeleton containing cages and tunnels and it has a great physical affiliation to water uptake. Zeolite and bentonite, in a mixture, are thought to be in competition for water uptake and this may alter the distribution of water content for each soil in the mixture. The present study investigated the suction properties of compacted ZBMs and SBMs for varying mixing ratios and compaction water contents. The soil suction measurement technique chosen was the filter-paper method. The suction characteristics of powdered, granular, and block zeolites, as well as 0, 10, and 20% bentonite in ZBMs and SBMs were measured and compared with each other. Contaminated compacted ZBMs are compared with those of uncontaminated compacted ones at the optimum water content for the 10% and 20% mixtures. The results show that suction capacity of zeolite increases with grain size. As bentonite content increases, both matric and total suction increase for both mixtures. ZBMs have higher matric suction values than SBMs, but not total suction values. Contaminated total suction values are found to be higher than those of uncontaminated samples due to an increase in dissolved ion concentration.

  11. Rheological study of clay-kaolin aqueous suspensions

    NASA Technical Reports Server (NTRS)

    Lapasin, R.; Lucchini, F.

    1984-01-01

    Rheological characteristics of clay-kaolin aqueous suspensions were studied by a rotational viscometer to correlate their behavior with the properties of ceramic slips for casting containing quartz, feldspars, and other nonplastic materials. In particular, the effects of the different amounts of dry materials and deflocculant (mixture 1:1 of Na2CO3 and Na2SiO3) and of temperatures on the shear-time-dependent properties of suspensions were examined.

  12. Interaction between tylosin and bentonite clay from a pharmacokinetic perspective.

    PubMed

    Devreese, Mathias; Osselaere, Ann; Goossens, Joline; Vandenbroucke, Virginie; De Baere, Siegrid; De Backer, Patrick; Croubels, Siska

    2012-12-01

    The interaction between bentonite and tylosin was investigated in broiler chickens, based on pharmacokinetic characteristics obtained in vivo. Simultaneous oral administration of bentonite and tylosin significantly lowered plasma levels of tylosin and reduced the area under the plasma concentration-time curve (AUC(0-inf)), maximal plasma concentration (C(max)), time to maximal plasma concentration (T(max)) and relative oral bioavailability. The results prove unambiguously the binding of tylosin by bentonite. Simultaneous administration of tylosin (in the drinking water or feed) and bentonite (mixed in the feed as a mycotoxin binder) should therefore be avoided.

  13. Effect of Na+ on surface fractal dimension of compacted bentonite

    NASA Astrophysics Data System (ADS)

    Xiang, G. S.; Xu, Y. F.; Jiang, H.

    2015-05-01

    Compacted Tsukinuno bentonite was immersed into NaCl solutions of different concentrations in oedometers, and the surface fractal dimension of bentonite-saline association was measured by nitrogen adsorption isotherms. The application of the Frenkel-Halsey-Hill equation and the Neimark thermodynamic method to nitrogen adsorption isotherms indicated that the surface roughness was greater for the bentonite-saline association. The surface fractal dimension of bentonite increased in the NaCl solution with low Na+ concentration, but decreased at high Na+ concentration. This process was accompanied by the same tendency in specific surface area and microporosity with the presence of Na+ coating in the clay particles.

  14. Synthesis of PDLLA/PLLA-bentonite nanocomposite through sonication

    NASA Astrophysics Data System (ADS)

    Sitompul, Johnner; Setyawan, Daru; Kim, Daniel Young Joon; Lee, Hyung Woo

    2016-04-01

    This paper concerns the synthesis of poly(D,L-lactic acid)/poly(L-lactic acid) bentonite nanocomposites. Poly (D,L-lactic acid) (PDLLA) was synthesized using lactic acid through the ZnO-catalyzed direct polycondensation method at vacuum pressure and poly(L-lactic acid) (PLLA) was synthesized with L-lactide by ring-opening polymerization method. The PDLLA/PLLA-bentonite nanocomposite films were synthesized using the solvent casting method. The nanoclay, bentonite, was prepared using the solution-intercalation method by dissolving the nanoparticles into chloroform before sonication. In this study, PDLLA/PLLA-bentonite nanocomposite films were produced using variable amounts of nanoclay and sonication times during the mixing of PDLLA/PLLA and bentonite. The properties of the PDLLA/PLLA nanocomposites were then characterized using the X-ray Diffraction (XRD), Universal Testing Machine (UTM), Water Vapor Permeability (WVP) tests, and the enzymatic biodegradability test. The XRD test was used to measure the intercalation of nanoclay layers in the PDLLA/PLLA matrix and the PDLLA/PLLA-bentonite intercalated nanocomposite films. It was found through these various tests that adding bentonite to the PDLLA/PLLA increases tensile strength to 56.76 MP. Furthermore, the biodegradability increases as well as the barrier properties of the polymers The different sonication time used during the mixing of the polymer solution with bentonite also affected the properties of the PDLLA/PLLA-bentonite nanocomposite films.

  15. High piezoelectric properties of cement piezoelectric composites containing kaolin

    NASA Astrophysics Data System (ADS)

    Pan, Huang Hsing; Yang, Ruei-Hao; Cheng, Yu-Chieh

    2015-04-01

    To obtain high piezoelectric properties, PZT/cement composites with kaolin were fabricated and polarized by 1.5kV/mm electric field for 40 min, where lead zirconate titanate (PZT) inclusion with 50% by volume was used. After the polarization, piezoelectric properties of the composite were measured daily till 100 days. Results indicated that relative dielectric constant (ɛr) and piezoelectric strain constant (d33) increase with aging day, and approach to asymptotic values after 70 days. Temperature treatment to the composite is a dominate factor to enhance piezoelectric properties. The d33 and ɛr values of PZT/cement composites treated at the ambient temperature (23℃) were 57pC/N and 275 at the 70th aging day respectively, and then reached 106pC/N and 455 in turn with 150℃ treatment. The composite contains 4% kaolin having the highest value of d33=111pC/N and ɛr=500 at 90 days because the porosity is the less than the others. Cement piezoelectric composites containing kaolin own the higher d33 and ɛr value, compared with the other reported composites with 50% PZT. The porosity, the electromechanical coupling factor and impedance-frequency spectra of the cement piezoelectric composites were also discussed.

  16. Thermally reduced kaolin-graphene oxide nanocomposites for gas sensing

    NASA Astrophysics Data System (ADS)

    Zhang, Renyun; Alecrim, Viviane; Hummelgård, Magnus; Andres, Britta; Forsberg, Sven; Andersson, Mattias; Olin, Håkan

    2015-01-01

    Highly sensitive graphene-based gas sensors can be made using large-area single layer graphene, but the cost of large-area pure graphene is high, making the simpler reduced graphene oxide (rGO) an attractive alternative. To use rGO for gas sensing, however, require a high active surface area and slightly different approach is needed. Here, we report on a simple method to produce kaolin-graphene oxide (GO) nanocomposites and an application of this nanocomposite as a gas sensor. The nanocomposite was made by binding the GO flakes to kaolin with the help of 3-Aminopropyltriethoxysilane (APTES). The GO flakes in the nanocomposite were contacting neighboring GO flakes as observed by electron microscopy. After thermal annealing, the nanocomposite become conductive as showed by sheet resistance measurements. Based on the conductance changes of the nanocomposite films, electrical gas sensing devices were made for detecting NH3 and HNO3. These devices had a higher sensitivity than thermally annealed multilayer GO films. This kaolin-GO nanocomposite might be useful in applications that require a low-cost material with large conductive surface area including the demonstrated gas sensors.

  17. Room-temperature luminescence from kaolin induced by organic amines

    NASA Technical Reports Server (NTRS)

    Coyne, L. M.; Kloepping, R.; Pollack, G.

    1984-01-01

    Several new, room-temperature luminescent phenomena, resulting from the interaction of kaolin and various amino compounds, have been observed. The emission of light from kaolin pastes (treated with quinoline, pyridine, hydrazine, monoethanolamine, n-butylamine, and piperidine) was shown to decay monotonically over a period of hours to days. More light was released by a given amino compound after it was dried and purified. Hydrazine, in addition to the monotonically decaying photon release, produces delayed pulses of light with peak emission wavelength of 365 nm which last between several hours and several days. These photon bursts are acutely sensitive to the initial dryness of the hydrazine, both in the number of bursts and the integrated photon output. The amount of light and the capacity of the kaolin to produce the delayed burst appeared to be strongly dependent on preliminary heating and on gamma-irradiation, analogous to the dehydration-induced light pulse previously reported from the Ames Research Center. A small, delayed burst of photons occurred when piperidine and n-butylamine were removed by evaporation into an H2SO4 reservoir.

  18. Bromate adsorption using Fe-pillared bentonite.

    PubMed

    He, Shilong; Zhang, Dandan; Gu, Li; Zhang, Shenghua; Yu, Xin

    2012-01-01

    Bromate is an emerging hazardous substance in drinking water. In this study, the removal ofbromate by Fe-pillared bentonite was investigated using various experimental parameters: contact time, initial concentration (Co), temperature, initial pH and competing anions. The adsorption ofbromate followed the pseudo-second-order kinetic better than it followed other kinetic models, and the pseudo-second-order kinetic study showed that equilibrium could be achieved within 60 min. Equilibrium isotherms were analyzed by Freundlich, Langmuir, Redlich-Peterson and Toth isotherm models. The Toth and Redlich-Peterson models better represented the bromate adsorption. Results also indicated that, other than the competing anions and solution pH, temperature was a key parameter affecting adsorption. It was ultimately concluded that Fe-pillared bentonite was effective at removing bromate from water.

  19. Bacterial cellulose-kaolin nanocomposites for application as biomedical wound healing materials

    NASA Astrophysics Data System (ADS)

    Wanna, Dwi; Alam, Catharina; Toivola, Diana M.; Alam, Parvez

    2013-12-01

    This short communication provides preliminary experimental details on the structure-property relationships of novel biomedical kaolin-bacterial cellulose nanocomposites. Bacterial cellulose is an effective binding agent for kaolin particles forming reticulated structures at kaolin-cellulose interfaces and entanglements when the cellulose fraction is sufficiently high. The mechanical performance of these materials hence improves with an increased fraction of bacterial cellulose, though this also causes the rate of blood clotting to decrease. These composites have combined potential as both short-term (kaolin) and long-term (bacterial cellulose) wound healing materials.

  20. Plutonium sorption and desorption behavior on bentonite.

    PubMed

    Begg, James D; Zavarin, Mavrik; Tumey, Scott J; Kersting, Annie B

    2015-03-01

    Understanding plutonium (Pu) sorption to, and desorption from, mineral phases is key to understanding its subsurface transport. In this work we study Pu(IV) sorption to industrial grade FEBEX bentonite over the concentration range 10(-7)-10(-16) M to determine if sorption at typical environmental concentrations (≤10(-12) M) is the same as sorption at Pu concentrations used in most laboratory experiments (10(-7)-10(-11) M). Pu(IV) sorption was broadly linear over the 10(-7)-10(-16) M concentration range during the 120 d experimental period; however, it took up to 100 d to reach sorption equilibrium. At concentrations ≥10(-8) M, sorption was likely affected by additional Pu(IV) precipitation/polymerization reactions. The extent of sorption was similar to that previously reported for Pu(IV) sorption to SWy-1 Na-montmorillonite over a narrower range of Pu concentrations (10(-11)-10(-7) M). Sorption experiments with FEBEX bentonite and Pu(V) were also performed across a concentration range of 10(-11)-10(-7) M and over a 10 month period which allowed us to estimate the slow apparent rates of Pu(V) reduction on a smectite-rich clay. Finally, a flow cell experiment with Pu(IV) loaded on FEBEX bentonite demonstrated continued desorption of Pu over a 12 day flow period. Comparison with a desorption experiment performed with SWy-1 montmorillonite showed a strong similarity and suggested the importance of montorillonite phases in controlling Pu sorption/desorption reactions on FEBEX bentonite.

  1. Mechanical properties of crushed salt/bentonite blocks

    SciTech Connect

    Gerstle, W.H.; Jones, A.K.

    1986-08-01

    A preliminary mechanical testing program has been conducted on crushed salt/bentonite blocks. These blocks are pototypes of blocks that may eventually be used to build engineered seals in drifts at the WIPP site. Three types of blocks were tested: pure crushed salt, crushed salt with bentonite binder, and pure bentonite. Simple uniaxial compression tests were performed. Axial displacement and lateral displacements were measured as a function of applied axial load. The ultimate strength, initial elastic moduli, and mode of failure were determined from these tests. The ultimate uniaxial strength of the pure bentonite blocks were found to be about 6.8 MPa. The ultimate uniaxial strength of pure salt blocks were found to be about 3.2 MPa. The blocks composed of both salt and bentonite had a strength somewhere between these two values. Surprisingly, the bentonite blocks, while stronger than the pure salt blocks, were less stiff. The mode of failure in all cases was through longitudinal splitting cracking. Also, ultrasonic velocities in the blocks were measured. The results of these tests indicate a high degree of anisotropy in the bentonite and salt/bentonite blocks, while the pure salt blocks appear to be isotropic.

  2. [Sorption and mechanism of surfactants on bentonite in combined pollution].

    PubMed

    Sun, Xiao-Hui; Lu, Ying-Ying; Chen, Shu-Guang; Li, Ling-Jian; Shen, Xue-You

    2007-04-01

    Sorption of cationic surfactant cetyl pyridinium chloride (CPC), anionic surfactant sodium dodecylbenzene sulfonate (SDBS) and nonionic surfactant Triton X-100 (TX-100) on bentonite was studied. The influences of cation-exchange capacity (CEC), temperature and salinity on the sorption of CPC were also discussed. The results indicate that the sorption of CPC on Na-bentonite is greater than that of TX-100 and SDBS, and SDBS hardly shows any sorption. CPC is adsorbed to Na-bentonite through a combination of hydrophobic bonding and cation-exchange. While TX-100 is adsorbed to Na-bentonite via the formation of an adsorption layer of twain surfactant molecule and hydrogenolysis of silicon-oxygen surface of bentonite and TX-100. The amount of SDBS adsorbed on Ca-bentonite increases with increasing surfactant concentration, reaching a maximum at 1.5 critical micelle concentration (CMC), and then decreases with increasing surfactant loading. The mechanism of the retention appears to be formation of a sparingly soluble Ca-SDBS species, and dissolution in the micelle. The amount of CPC adsorbed on bentonite decreases with increasing temperature, and increases with increasing CEC. NaCl can enhance the sorption of CPC on bentonite.

  3. Uranium sorption on bentonite modified by octadecyltrimethylammonium bromide.

    PubMed

    Majdan, Marek; Pikus, Stanisław; Gajowiak, Agnieszka; Sternik, Dariusz; Zięba, Emil

    2010-12-15

    The sorption of U(VI) on octadecyltrimethyl-bentonite was investigated at the pH values of the aqueous phase ranging from 3 to 10 and the concentrations of U(VI): 0.1-1 mmol/dm(3). The concentrations of alkylammonium cation in bentonite were increased from 21% to 150% of CEC (cation exchange capacity). It was determined that the sorption of U(VI) on modified bentonite, i.e. the distribution constant -K(d) decreases with the percent of mineral modification until it attains a minimum at 76% of CEC and then increases again. The effective sorption of U(VI) was found to be in the pH range: 6-10 for the modified bentonite and was explained as the consequence of U(VI) anionic hydroxy complexes sorption. Both FT-IR and XRD spectra of the modified bentonite were analyzed and provided arguments for the existence of surfactant cations in the form of monolayer and bilayer in the interlamellar space of bentonite. In turn the luminescence spectra of bentonite suspensions, i.e. their character at different values of pH, proved the existence of hydroxide-like planar polymeric U(VI) species in the bentonite phase at pH 9.

  4. IgG purification by bentonite-acrylamide-histidine microcomposite.

    PubMed

    Akkaya, Birnur

    2012-04-01

    In this work, a new microcomposite composed of bentonite, acrylamide and histidine, as a pseudospecific ligand, was synthesized by bulk polymerization. The aim of this study was to improve IgG adsorption capacity of bentonite by incorporating histidine. The surface areas of the bentonite and bentonite-acrylamide-histidine microcomposites were 33.4 and 1.42 m(2)/g, respectively. The amount of histidine was found to be 50 μmol/g bentonite via elemental analysis. Adsorption capacity was at the value of 100mg/g from aqueous solution while adsorption capacity was 108 mg/g from human plasma with a purity of 90%. IgG biomolecules were able to be adsorbed and desorbed five times by using the same microcomposites without significant loss in their adsorption capacity.

  5. Reduction of ochratoxin a levels in red wine by bentonite, modified bentonites, and chitosan.

    PubMed

    Kurtbay, Hayriye Mine; Bekçi, Zehra; Merdivan, Melek; Yurdakoç, Kadir

    2008-04-09

    Adsorption method may play an important role to remove ochratoxin A (OTA) from wine by bentonite (B), nonylammonium bentonite (NB), dodecylammonium bentonite (DB), KSF-montmorillonite (KSF), and chitosan bead (CB). The optimum conditions of OTA adsorption from synthetic solutions were revealed at room temperature and pH 3.5. The adsorption equilibria of B and NB were almost established within 120 and 240 min, respectively. DB, KSF, and CB had about 90 min of equilibration time. The adsorption efficiency carried out in the synthetic OTA solution did not change remarkably when the amounts of adsorbents were 25 mg for bentonite, DB, and KSF and 100 mg for NB and CB. Furthermore, 25 mg of adsorbents was used at all adsorption studies in synthetic solution. The adsorption isotherm was fitted with mostly a Freundlich equation with respect to the correlation coefficients. The adsorption data were evaluated using Langmuir and Freundlich equations having Kf values ranging from 0.011 to 9.5 with respect to correlation coefficients (R2 = 0.900-0.977). DB and KSF have the highest adsorption capacity for OTA in synthetic solutions. In wine, the removal of OTA was succeeded at a percentage of 60-100 by KSF and CB. Furthermore, the highest adsorption capacity of OTA for red wine was obtained by using 250 mg of KSF, which caused less damage to the nature of wine and also low adsorption of polyphenols and anthcyans.

  6. Remediation of distilleries wastewater using chitosan immobilized Bentonite and Bentonite based organoclays.

    PubMed

    El-Dib, F I; Tawfik, F M; Eshaq, Gh; Hefni, H H H; ElMetwally, A E

    2016-05-01

    Organic-inorganic nanocomposite, namely chitosan immobilized Bentonite (CIB) with chitosan content of 5% was synthesized in an acetic acid solution (2%). Organically modified CIB and Bentonite (mbent.) were prepared by intercalating cetyl trimethylammonium bromide (CTAB) as a cationic surfactant at doses equivalent to 1.5 and 3 times the cation exchange capacity (CEC) of clay. The prepared samples were characterized using FTIR, XRD and SEM to explore the interlayer structure and morphology of the resultant nanocomposites. The remediation of distilleries (vinasse) wastewater process was carried out using different adsorbents including CIB, modified CIB (mCIB), Bentonite (bent.), modified Bentonite (mbent.) and chitosan at different contact time. The results showed that the packing density of surfactant used in the synthesis of organoclays strongly affects the sorption capacity of the clay mineral and also showed that (mCIB)3 was found to be the most effective sorbent in the purification of distilleries wastewater with 83% chemical oxygen demand (COD) reduction and 78% color removal.

  7. Effect of sulfuric acid concentration of bentonite and calcination time of pillared bentonite

    NASA Astrophysics Data System (ADS)

    Mara, Ady; Wijaya, Karna; Trisunaryati, Wega; Mudasir

    2016-04-01

    An activation of natural clay has been developed. Activation was applied by refluxing the natural bentonite in variation of the sulfuric acid concentration and calcination time of pillared bentonite (PLC). Calcination was applied using oven in microwave 2,45 GHz. Determination of acidity was applied by measuring the amount of adsorbed ammonia and pyridine. Morphological, functional groups and chrystanility characterizations were analyzed using SEM, TEM, FTIR and XRD. Porosity was analyzed using SSA. The results showed that the greater of the concentration of sulfuric acid and calcination time was, the greater the acidity of bentonite as well as the pore diameter were. FTIR spectra showed no fundamental changes in the structure of the natural bentonite, SEM, and TEM images were showing an increase in space or field due to pillarization while the XRD patterns showed a shift to a lower peak. Optimization was obtained at a concentration of 2 M of sulfuric acid and calcination time of 20 minutes, keggin ion of 2.2 and suspension of 10 mmol, respectively each amounted to 11.7490 mmol/gram of ammonia and 2.4437 mmol/gram of pyridine with 154.6391 m2/gram for surface area, 0.130470 m3/gram of pore volume and 3.37484 nm of pore diameter.

  8. Effect of multivalent salts -- calcium and aluminum -- on the flocculation of kaolin suspension with anionic polyacrylamide

    SciTech Connect

    Peng, F.F.; Di, P. . Dept. of Mineral Processing Engineering)

    1994-04-01

    The effects of calcium and aluminum ions on the interaction behavior of anionic polyacrylamide (anionic PAM or HPAM) and kaolin are important in determining the efficient flocculation of kaolin. While kaolin surfaces are negatively charged in media such as water, they exhibit the positive surface charge characteristic at pH below 3.2 in the solution of calcium cation, and at pH below 9.2 in the solution of aluminum cation. The. experimental results show that both calcium and aluminum ions suppress the kaolin flocculation process. The results are analyzed and explained by molecular orbital theory, solution chemistry, infrared spectra, and electronic probe examination of kaolin treated with and without anionic PAM. Analysis results indicate that the specific adsorption of Ca[sup 2+], Al[sup 3+] and their hydroxo complexes on anionic PAM causes the loss of anionic character in the low pH range and leads to a low flocculation efficiency. In the high pH range, the poor kaolin flocculation can be attributed to precipitation of calcium and aluminum hydroxides on active functional groups, which inhibits the hydrogen bonding between anionic PAM and kaolin surfaces. At neutral pH values, the trivalent aluminum ion has more significant adverse effect on the kaolin flocculation than the divalent calcium ion.

  9. Effects of kaolin particle film on Myzus persicae (Hemiptera: Aphididae) behaviour and performance.

    PubMed

    Barker, J E; Holaschke, M; Fulton, A; Evans, K A; Powell, G

    2007-10-01

    The emergence of resistance mechanisms to, and revocation of, many insecticides used in the control of the polyphagus aphid pest, Myzus persicae (Sulzer), has increased the pressure to develop novel approaches for the control of the pest in many crops. Kaolin-based particle films provide a physical barrier against insect pests and show considerable potential for controlling M. persicae. We conducted a series of laboratory experiments to investigate the mode of action of kaolin against aphids. The material appeared to have no direct effect on M. persicae; spraying adult aphids with aqueous kaolin suspension had no significant impact on their subsequent survival or reproduction on untreated plants. Similarly, when aphids were placed on kaolin-treated host-plants (Brassica oleracea), their performance (survival, growth rate and reproduction) was not significantly different from aphids on untreated plants. However, when M. persicae were given a choice between kaolin-treated and untreated (or water solvent-treated) leaf areas, both adults and nymphs exhibited a significant preference for non-kaolin-treated host-plant material. Rejection of kaolin-treated plant material occurred very rapidly (within 20 min) and this behavioural effect may be related to the efficacy of kaolin in controlling aphids under field conditions.

  10. High residue amounts of kaolin further increase photosynthesis and fruit color in 'Empire' apple

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Kaolin (Surround WP, NovaSource, Phoenix, AZ, USA) is commonly used to reduce sunburn damage in fruit crops and to reduce heat stress on foliage. It is typically applied at rates of 3% to 6%, resulting in leaf and fruit residue levels of 1-3 g/m2. Crop modeling of the effect of kaolin on leaf/cano...

  11. Enhanced shear strength of sodium bentonite using frictional additives

    SciTech Connect

    Schmitt, K.E.; Bowders, J.J.; Gilbert, R.B.; Daniel, D.E.

    1997-12-31

    One of the most important obstacles to using geosynthetic clay liners (GCLs) in landfill cover systems is the low shear strength provided by the bentonitic portion of the GCL. In this study, the authors propose that granular, frictional materials might be added to the bentonite to form an admixture that would have greater shear strength than the bentonite alone while still raining low hydraulic conductivity. Bentonite was mixed with two separate granular additives, expanded shale and recycled to form mixtures consisting of 20-70% bentonite by weight. In direct shear tests at normal stresses of 34.5-103.5 kPa, effective friction angles were measured as 45{degrees} for the expanded 36{degrees} for the recycled glass, and 7{degrees} for the hydrated granular bentonite. The strength of the expanded shale mixtures increased nearly linearly as the percentage shale in the mixture increased, to 44{degrees} for a bentonite mixture with 80% shale. The addition of recycled glass showed little effect on the shear strength of the mixtures of glass and bentonite. Hydraulic conductivity measurements for both types of mixtures indicated a linear increase with log(k) as the amount of granular additive increased. For applications involving geosynthetic clay liners for cover systems, a mixture of 40% expanded shale and 60% bentonite is recommended, although further testing must be done. The 40/60 mixture satisfies the hydraulic equivalency requirement, with k = 5.1X10{sup -9} cm/sec, while increasing the shear strength parameters of the bentonitic mixture to {phi}{prime} = 17{degrees} and c{prime} = 0.

  12. A general framework for ion equilibrium calculations in compacted bentonite

    NASA Astrophysics Data System (ADS)

    Birgersson, Martin

    2017-03-01

    An approach for treating chemical equilibrium between compacted bentonite and aqueous solutions is presented. The treatment is based on conceptualizing bentonite as a homogeneous mixture of water and montmorillonite, and assumes Gibbs-Donnan membrane equilibrium across interfaces to external solutions. An equation for calculating the electrostatic potential difference between bentonite and external solution (Donnan potential) is derived and solved analytically for some simple systems. The solutions are furthermore analyzed in order to illuminate the general mechanisms of ion equilibrium and their relation to measurable quantities. A method is suggested for estimating interlayer activity coefficients based on the notion of an interlayer ionic strength. Using this method, several applications of the framework are presented, giving a set of quantitative predictions which may be relatively simply tested experimentally, e.g.: (1) the relative amount of anions entering the bentonite depends approximately on the square-root of the external concentration for a 1:2 salt (e.g. CaCl2). For a 1:1 salt (e.g. NaCl) the dependence is approximately linear, and for a 1:2 salt (e.g. Na2SO4) the dependence is approximately quadratic. (2) Bentonite contains substantially more nitrate as compared to chloride if equilibrated with the two salt solutions at equal external concentration. (3) Potassium bentonite generally contains more anions as compared to sodium bentonite if equilibrated at the same external concentration. (4) The anion concentration ratio in two bentonite samples of different cations (but with the same density and cation exchange capacity) resembles the ion exchange selectivity coefficient for that specific cation pair. The results show that an adequate treatment of chemical equilibrium between interlayers and bulk solutions are essential when modeling compacted bentonite, and that activity corrections generally are required for relevant ion equilibrium calculations. It

  13. Adsorption of aniline, phenol, and chlorophenols on pure and modified bentonite

    NASA Astrophysics Data System (ADS)

    Yildiz, A.; Gür, A.; Ceylan, H.

    2006-11-01

    In the present study, pure bentonite and bentonite modified by HNO3, EDTA, and HDTMA are adsorbents. The changes on the surfaces of bentonite samples are studied by IR spectroscopy. The adsorption of aniline, phenol, and phenol derivatives on these adsorbents is examined by means of gas chromatography. As the result of these examinations, it is seen that the adsorption capacities of clay-organic complexes (bentonite-EDTA and bentonite-HDTMA) are higher than those of bentonite-HNO3 and pure bentonite.

  14. Landing and Oviposition Responses of Rhagoletis indifferens (Dipt., Tephritidae) on Sweet Cherry Treated with Kaolin- and Limestone-Based Products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Kaolin- and limestone-based products were compared for their effects on landing and oviposition on sweet cherry by Rhagoletis indifferens Curran (Dipt., Tephritidae). Surround (95% calcined kaolin), Cocoon (100% hydrous kaolin), Eclipse (>97% limestone), and Purshade (62.5% limestone) were studied....

  15. Defining an exposure-response relationship for suspended kaolin clay particulates and aquatic organisms: work toward defining a water quality guideline for suspended solids.

    PubMed

    Gordon, Andrew K; Palmer, Carolyn G

    2015-04-01

    Water quality guidelines for suspended solids generally rely on the percentage departure from reference condition, an approach that has been criticized. Attempts to develop a biological effects-base guideline have, however, been confounded by low data availability. Furthermore, the high biological response variability to suspended solids exposure suggests that organisms are responding not only to exposure concentration and duration but also to other mechanisms of effect associated with suspended particles (e.g., size, shape, and geochemical composition). An alternative option is to develop more situation and site specific guidelines by generating biological effects data to suspended particles of a particular geochemistry and restricted size range. With this in mind, aquatic organism responses to kaolin clay particle exposure were collated from the literature and incorporated into 2 exposure-response relationship approaches. The species sensitivity distribution approach produced a hazardous concentration affecting 5% of species estimate of 58 mg/L for mortality responses, and 36 mg/L for sublethal data. The severity-of-ill-effect approach produced similar estimates for lethal and sublethal data. These results suggest that aquatic organisms are slightly more tolerant of kaolin clay particles than particles from barite or bentonite clays, based on results from previous studies on these clay types. This type of information can enable better estimates of the risk faced by aquatic organisms exposed to suspended solids. For example, when the sediments of a particular water body are dominated by a particular type of clay particle, then the most appropriate exposure-response relationship can be applied.

  16. Experimental investigation of sodium bentonite stability in Hanford basalt

    SciTech Connect

    Wood, M.I.

    1983-02-01

    Sodium bentonite is a candidate material for the waste package backfill component in a repository in basalt at the Hanford Site. Preliminary hydrothermal experiments have been conducted under near-field geochemical conditions expected to occur in the reference repository location in Grande Ronde Basalt. Experiments have been conducted in the basalt/groundwater, bentonite/groundwater, and basalt/bentonite/groundwater systems. The experiments have been conducted at 300/sup 0/C using a simulated Grande Ronde groundwater, reference Umtanum basalt, and sodium bentonite. Key data generated by the experiments include experimental solution analyses as a function of time and preliminary solids analysis by scanning transmission electron microscopy and x-ray diffraction. Solution trends of the major aqueous species were similar in the three systems and are characterized by: (1) the gradual reduction of the pH value from approx.9.75 to a steady-state value of approx.6, (2) an initial rapid increase followed by a gradual decreasein silica concentration, and (3) a slight or negligible increase in sodium, sulfate, and chloride concentrations. In the bentonite/groundwater experiment, small amounts (<1%) of an albite reaction product were observed. Conserversely, the formation of illite, a common bentonite alteration product, was not observed. These results indicate tjhat sodium bentonite will remain sufficiently stablee at 300/sup 0/C under hydrothermal conditions in basalt to permit its use as a backfill material.

  17. Experimental studies on the interaction of groundwater with bentonite

    SciTech Connect

    Sasaki, Y.; Shibata, M.; Yui, M.; Ishikawa, H.

    1995-12-31

    Interactions of sodium bentonite with distilled water and two types of synthetic groundwater were studied by batch experiments. In the experiments, clay and pure minerals were reacted at room temperature under aerobic and anaerobic condition as a function of time and liquid/solid ratio. The clay and pure minerals used in the experiments were Kunigel-V1 (crude Na-bentonite), Kunipia F (purified Na-bentonite), purified Na-smectite (purified from Kunipia F), calcite and pyrite as accessory minerals. The chemical composition in the liquid phase was analyzed through centrifugation and ultrafiltration. Alteration of the distribution of exchangeable cation in the bentonite was analyzed by NH{sub 4}Ac and XRD. The results indicated that the interaction between bentonite (Kunigel-V1) and groundwater under aerobic condition was described by ion exchange reaction of smectite, dissolution of calcite and oxidation of pyrite. From these experimental studies, the model of the interaction of groundwater with bentonite proposed by Wanner was modified. The comparison between calculation and experimental results showed good agreement and indicated that this model could be adopted to predict porewater chemistry of bentonite for performance assessment of geological isolation system of high level waste.

  18. Engineering Properties of Bentonite Stabilized with Lime and Phosphogypsum

    NASA Astrophysics Data System (ADS)

    Kumar, Sujeet; Dutta, Rakesh Kumar; Mohanty, Bijayananda

    2014-12-01

    Engineering properties such as compaction, unconfined compressive strength, consistency limits, percentage swell, free swell index, the California bearing ratio and the consolidation of bentonite stabilized with lime and phosphogypsum are presented in this paper. The content of the lime and phosphogypsum varied from 0 to 10 %. The results reveal that the dry unit weight and optimum moisture content of bentonite + 8 % lime increased with the addition of 8 % phosphogypsum. The percentage of swell increased and the free swell index decreased with the addition of 8 % phosphogypsum to the bentonite + 8 % lime mix. The unconfined compressive strength of the bentonite + 8 % lime increased with the addition of 8 % phosphogypsum as well as an increase in the curing period up to 14 days. The liquid limit and plastic limit of the bentonite + 8 % lime increased, whereas the plasticity index remained constant with the addition of 8 % phosphogypsum. The California bearing ratio, modulus of subgrade reaction, and secant modulus increased for the bentonite stabilized with lime and phosphogypsum. The coefficient of the consolidation of the bentonite increased with the addition of 8 % lime and no change with the addition of 8 % phosphogypsum.

  19. Fracture behavior of kaolin-reinforced high density polyethylene

    SciTech Connect

    Wetherhold, R.C.; Mouzakis, D.E.

    1999-10-01

    The addition of the low-cost mineral filler kaolin to high-density polyethylene (HDPE) creates a composite with both improved stiffness and toughness properties. This study focuses on two aspects of the toughness of these composites: the fracture toughness increment produced by work at the fracture surface and the directionality induced by the injection molding fabrication process. The Essential Work of Fracture (EWF) method gives results which show that a higher volume fraction of kaolin produces more surface work, consistent with earlier work using Compact Tension (CT) tests. The EWF method also demonstrates that a lower volume fraction can produce a higher overall plastic work and apparent toughness. A heat treatment that removes the orientation of the matrix but not that of the particles was applied to study the effect of matrix crystallinity. The results indicate that the matrix supramolecular structure (crystallinity and skin-core effect) is responsible for the directionality of toughness, and that a heat treatment can be used to produce high toughness behavior in both major directions.

  20. Evaluation of the Dustiness of Different Kaolin Samples.

    PubMed

    López-Lilao, Ana; Bruzi, Marine; Sanfélix, Vicenta; Gozalbo, Ana; Mallol, Gustavo; Monfort, Eliseo

    2015-01-01

    Several samples of kaolin with different mean particle size were prepared and tested using the continuous drop method, one of the reference test methods according to standard EN 15051:2006 "Workplace atmospheres - Measurement of the dustiness of bulk materials - Requirements and reference test methods." On the other hand, with a view to relating the dustiness of the materials to their properties, particle size distribution, specific surface area, and Hausner ratio of these samples were determined. This article presents a characterization of these samples and an assessment of the influence of some material parameters on dustiness. The results show that dustiness may significantly be affected by mean particle size, specific surface area, and Hausner ratio. Moreover, it is highlighted that a detailed study of the influence of fine particles content on the dustiness was carried out. This information is deemed essential for establishing the most efficient preventive and/or corrective measures to reduce the generation of fugitive emissions of particulate matter during kaolin processing, both into the outside atmosphere (air pollution) and inside the facilities (occupational health).

  1. Preparation and characterization of bionanocomposite films reinforced with nano kaolin.

    PubMed

    Jafarzadeh, Shima; Alias, Abd Karim; Ariffin, Fazilah; Mahmud, Shahrom; Najafi, Ali

    2016-02-01

    Effects of nano-kaolin incorporation into semolina films on the physical, mechanical, thermal, barrier and antimicrobial properties of the resulting bio-nanocomposite films were investigated. The properties included crystal structure (by X-ray diffraction), mechanical resistance, color, Fourier transform infrared spectra, decomposition temperature, water-vapor permeability (WVP), oxygen permeability (OP), and antimicrobial activity against Staphylococcus aureus and Escherichia coli. Kaolin was incorporated into biofilms at various amounts (1, 2, 3, 4, and 5 %, w/w total solid). All films were plasticized with 50 % (w/w total solid) combination of sorbitol/glycerol at 3:1 ratio. The incorporation of nanokaolin into semolina films decreased OP and WVP. The moisture content and water solubility of the films were found to decrease by nanokaolin reinforcement, and mechanical properties of films were improved by increasing nanokaolin concentration. Tensile strength and Young's modulus increased from 3.41 to 5.44 MPa and from 63.12 to 136.18, respectively, and elongation-at-break decreased. The films did not exhibit UV absorption. In conclusion, nanokaolin incorporation enhanced the barrier and mechanical properties of semolina films, indicating the potential application of these bio-nanocomposites in food-product packaging.

  2. Kaolin-correctable prolongation of the activated partial thromboplastin time.

    PubMed

    Briselli, M F; Ellman, L

    1980-11-01

    Seven patients who had normal prothrombin times but prolonged activated partial thromboplastin times (aPTT) are described. The prolonged aPTT, obtained with micronized silica as the contact activating agent in a semi-automated optical end-point system, a nonautomated optical end-point system, and a conductivity end-point system, corrected to normal when kaolin was used as the contact activating agent. Abnormal results were also obtained with celite and ellagic acid as contact activating agents. The activities of various clotting factors were within normal limits in all cases where they were assayed. The thromboplastin dilution test was uniformly negative, and mixtures of one patient's plasma with that of another patient failed to correct the abnormal aPTT. No patients had a personal or family history of bleeding, and all underwent surgery without bleeding difficulties. This pattern of a prolonged aPTT that corrects to normal when kaolin is used as the contact activator appears to represent a previously unrecognized laboratory phenomenon.

  3. Effect of Curing Profile on Kaolin-based Geopolymers

    NASA Astrophysics Data System (ADS)

    Heah, C. Y.; Kamarudin, H.; Bakri, A. M. Mustafa Al; Binhussain, M.; Luqman, M.; Nizar, I. Khairul; Ruzaidi, C. M.; Liew, Y. M.

    Depending on the processing conditions, geopolymers can exhibit a wide variety of properties and characteristics. Curing profile serves as a crucial parameter in synthesis of geopolymers. In this paper, the influence of curing temperature and curing time on the properties of kaolin-based geopolymer was studied. The samples were separated into several curing conditions; including curing at ambient temperature, 40 °C, 60 °C, 80 °C and 100 °C for 1 day, and up to 3 days. The compressive strength and SEM analysis of geopolymer products were evaluated. Results showed that curing condition has a significant effect on the mechanical properties of kaolin-based geopolymer. Generally, curing at ambient temperature was not feasible, while increase in temperature favored the strength development. In addition, prolonged curing time improved the geopolymerization process, and led to higher strength gain. However, curing at high temperature for a long period of time caused failure of the sample at a later age.

  4. A comparison of kaolin-activated versus nonkaolin-activated thromboelastography in native and citrated blood.

    PubMed

    Thalheimer, Ulrich; Triantos, Christos K; Samonakis, Dimitrios N; Zambruni, Andrea; Senzolo, Marco; Leandro, Gioacchino; Patch, David; Burroughs, Andrew K

    2008-09-01

    Thromboelastography can be performed with native or citrated blood (a surrogate to native blood in healthy controls, surgical and cirrhotic patients). Activators such as kaolin are increasingly used to reduce the time to trace generation. To compare kaolin-activated thromboelastography with nonkaolin-activated thromboelastography of native and citrated blood in patients with liver disease, patients undergoing treatment with warfarin or low-molecular weight heparin and healthy volunteers. We studied thromboelastography parameters in 21 healthy volunteers (group 1) and 50 patients, including 20 patients with liver cirrhosis with a nonbiliary aetiology (group 2), 10 patients with primary biliary cirrhosis or primary sclerosing cholangitis (group 3), 10 patients on warfarin treatment (group 4) and 10 patients with enoxaparin prophylaxis (group 5). Thromboelastography was performed using four methods: native blood (kaolin-activated and nonkaolin-activated) and citrated blood (kaolin-activated and nonkaolin-activated). For all thromboelastography parameters, correlation was poor (Spearman correlation coefficient < 0.70) between nonkaolin-activated and kaolin-activated thromboelastography, for both citrated and native blood. In healthy volunteers, in patients with liver disease and in those receiving anticoagulant treatment, there was a poor correlation between nonkaolin-activated and kaolin-activated thromboelastography. Kaolin-activated thromboelastography needs further validation before routine clinical use in these settings, and the specific methodology must be considered in comparing published studies.

  5. Formation of physically stable amorphous phase of ibuprofen by solid state milling with kaolin.

    PubMed

    Mallick, Subrata; Pattnaik, Satyanarayan; Swain, Kalpana; De, Pintu K; Saha, Arindam; Ghoshal, Gaurisankar; Mondal, Arijit

    2008-02-01

    Ibuprofen was milled in the solid state with kaolin (hydrated aluminium silicate) in different ratio to examine the extent of transformation from crystalline to amorphous state. The physical stability of the resultant drug was also investigated. X-ray powder diffractometry (XRD) and birefringence by Scanning Electron Microscopy (SEM) studies indicated almost complete amorphization of the drug on ball milling with kaolin at 1:2 ratio. Fourier transform infrared spectroscopy (FTIR) data showed a reduction in the absorbance of the free and the hydrogen-bonded acid carbonyl peak of carboxylic acid group accompanied by a corresponding increase in the absorbance of the carboxylate peak, indicating an acid-base reaction between the carboxylic acid containing ibuprofen and kaolin on milling. The extent of amorphization and reduction in the carbonyl peak and increase in carboxylate peak was a function of kaolin concentration in the milled powder. On storage of milled powder (at 40 degrees C and 75% RH for 10 weeks), XRD and birefringence of SEM study showed the absence of reversion to the crystalline state and FTIR data revealed continued reduction of carbonyl peak, whereas, ibuprofen converted from its crystalline acid form to amorphous salt form on milling with kaolin. Kaolin-bound state of ibuprofen was physically stable during storage. In-vitro dissolution studies revealed that percent release of ibuprofen from the kaolin co-milled powder is in the order: 1:2>1:1>1:0.5>1:0.1>milled alone ibuprofen>crystalline ibuprofen.

  6. Effects of kaolin on Ophelimus maskelli (Hymenoptera: Eulophidae) in laboratory and nursery experiments.

    PubMed

    Lo Verde, G; Rizzo, R; Barraco, G; Lombardo, A

    2011-02-01

    Although recent research has demonstrated that clays provide satisfactory control of some agricultural insect pests, the effect of clays on gall wasps that damage forest trees has not been previously reported. The aim of the current study is to evaluate the effectiveness of the clay kaolin in the laboratory and in the field in reducing the damage caused by the eulophid Ophelimus maskelli (Ashmead) on seedlings of eucalyptus (Eucalyptus L'Hér.) species. In the laboratory, kaolin + wetting agent significantly reduced the percentage of infested leaves and the number of galls per leaf. In the nursery, gall number per leaf was not correlated with leaf area with kaolin + wetting agent but was related to leaf area for all other treatments (wetting agent alone, imidacloprid, and untreated control). In the nursery, gall number per leaf was lower with kaolin + wetting agent and with imidacloprid than with the other two treatments. Overall, kaolin effectively reduced eulophid infestations, and its effect was more persistent than that of imidacloprid. Although application of kaolin might not be feasible on large forested areas, kaolin could represent a valuable control method in nurseries, where the repeated application with more toxic chemicals can result in high concentrations of residual pesticides in the soil.

  7. The use of trace elements to determine provenance relations among different types of Georgia kaolins

    SciTech Connect

    Dombrowski, T.

    1992-01-01

    This study evaluates the proposition that different types of commercial kaolin district were derived from different source rocks. This analysis was made by comparing the cobalt, lanthanum, scandium and thorium concentrations of commercial kaolins to in situ kaolins derived from igneous and metamorphic rocks of the southeastern Piedmont provence. These elements are effective provenance indicators of fine grained sedimentary rocks because acidic (i.e., felsic) source rocks contain high levels of thorium and lanthanum; whereas, basic (i.e., basic) source rocks contain high levels of scandium and cobalt. Also, these elements are relatively immobile under surface weathering conditions. The -2 micrometer fraction of in situ kaolins derived from granite and gneiss adjacent to the kaolin belt contains relatively high concentrations of thorium (25.5-86.6 ppm) and lanthanum (46.0-256 ppm) and low concentrations of cobalt (7.5-25.2 ppm) and scandium (13.8-28.3 ppm). In contrast, in situ kaolins derived from intermediate metavolcanic rocks contain relatively low abundances of thorium (5.6-20.7 ppm) and lanthanum (17.5-122 ppm) and high concentrations of cobalt (18.6-55.5 ppm) and scandium (13.8-48.9 ppm). After consideration of factors that cause chemical fractionation of trace elements in low temperature environments the following provenance relationships are indicated: (1) the Cretaceous (soft) kaolins of Middle Georgia and South Carolina are derived from granite and gneiss, (2) the east Georgia and South Carolina Tertiary (hard) kaolins are derived from a mixture of approximately 70% metavolcanic rocks and 30% granite/gneiss source rocks, and (3) the Middle Georgia tertiary (hard) kaolins are derived from predominantly metavolcanic source rocks with distinct zones dominated by detritus from granite/gneiss sources. The differences in source material are controlled by the availability of source material exposed to alteration and erosion during the different time periods.

  8. Geology and resources of the Andersonville, Georgia, kaolin and bauxite district

    USGS Publications Warehouse

    Cofer, Harland E.; Manker, John Phillip

    1983-01-01

    The kaolin and kaolin-rich sediments of the Andersonville district were deposited in an estuary environment with restricted circulation and little tidal or longshore current influence. Micaceous kaolinitic clays were deposited during late Paleocene time on broad, shallow water flats between deeper water distributary channels in the estuarine system. During the cycle of deposition, kaolinitic sediments were temporarily exposed to weathering leading to bauxitization and further kaolinization. Subsequently, subaerial and/or subaqueous erosion planed off and redeposited some of the weathering products as organic-rich clays and silts, berthierine-bearing clays, and rarely as colluvial bauxite and sedimentary bauxitic clays. Upon resubmergence, gibbsite-rich, porous bauxite, and bauxitic clays were exposed to silica-saturated water of the estuary. Gibbsite reacted with silica to form kaolinite and resulted in the formation of the transitional (bauxitic) clays overlying the bauxite. Kaolinitic sediments transported by streams again spread over the altered and redeposited material. At the close of the kaolin depositional period movement along the Andersonville Fault Zone and related faults changed the basinal configuration, and the area of the uplifted (southern) block of the fault was exposed to weathering and bauxitization for a limited period of time. General submergence again occurred and much of the district was covered by marine and brackish water, ending the period of commercial kaolin deposition. The kaolin and bauxite deposits in the Andersonville district form a broad belt 15 kilometers wide and 22 kilometers long trending in a northwest-southeastward direction. Most of the kaolin and bauxite of commercial value occur within a narrow 10-kilometer-wide zone in the belt. The reserves of kaolin suitable for refractory and chemical use are approximately 290 million tonnes. Paramarginal resources of sandy kaolin suitable for refractory, chemical, or aluminum

  9. Evaluation of hydrophobic and hydrophilic kaolin particle films for peach crop, arthropod and disease management.

    PubMed

    Lalancette, Norman; Belding, Robert D; Shearer, Peter W; Frecon, Jerome L; Tietjen, William H

    2005-01-01

    Hydrophobic and/or hydrophilic kaolin particle film treatments to peach (Prunus persica (L) Batsch) trees were evaluated for crop and pest management capabilities in six studies from 1997 to 2000. Unsprayed control and standard treatments, the latter consisting of a commercial pesticide program, were included for comparison. Treatments in initial studies were applied via handgun, which resulted in a uniform and heavy deposit of kaolin after the first application. In contrast, treatments in subsequent studies used airblast equipment, which provided a uniform but less dense coverage, even after multiple applications. Results showed that both formulations of kaolin provided control of oriental fruit moth (Grapholita molesta (Busck)), plum curculio (Conotrachelus nenuphar (Herbst)) and Japanese beetle (Popillia japonica Newman) that was comparable with or better than the standard pesticide program. Effective management of late season catfacing insects (tarnished plant bugs Lygus lineolaris (Palisot de Beauvois) and stinkbugs Acrosternum hilare (Say), Euschistus servus (Say), and E tristigmus (Say)) and leafrollers (undetermined species) was also observed, although kaolin applications significantly increased phytophagous mite (Panonychus ulmi (Koch)) levels. In contrast to arthropod management, kaolin failed to control either peach scab (Cladosporium carpophilum (Von Thumen)) or rusty spot (Podosphaera leucotricha (Ell and Ev) ES Salmon) in any of the 4 years of the study. However, hydrophobic kaolin provided effective brown rot (Monilinia fructicola (G Winter) Honey) control when applied via handgun, and partial control when applied via airblast; hydrophilic kaolin failed to provide any control. These results suggest that hydrophobicity and deposit density may be important factors for effective disease management. The application of kaolin significantly delayed fruit maturation, increased fruit size and increased soluble solids relative to the standard. This effect

  10. [THE COMPARATIVE CHARACTERISTIC OF KAOLIN-ACTIVATED THROMBOELASTOGRAPHY IN HEALTHY NEWBORNS AND NEWBORNS WITH HEART AILMENTS].

    PubMed

    Leonov, N P; Karas'kov, A M; Litasova, E E; Strunin, O V; Karmadonova, N A; Akopov, G D; Vishegorodtseva, L I

    2016-02-01

    The study was carried out to diferentiate reference values for kaolin-activated thromboelastography in newborns with congenital heart disease. The study included two groups ofpatients. The first one consisted of 62 newborns with congenital heart disease and the second one consisted of 35 healthy newborns. The results of kaolin-activated thromboelastography implemented in groups are evaluated as condition of normal coagulation. The valuable diferences of homeostasis system in healthy newborns and newborns with congenital heart disease (without severe concomitant pathology) are not established. They have similar indicators of kaolin-activated thromboelastography. The derived results can be applied as standards in full-term newborns with congenital heart disease.

  11. Synthesis and swelling behavior of Protein-g-poly Methacrylic acid/kaolin superabsorbent hydrogel composites

    NASA Astrophysics Data System (ADS)

    Sadeghi, Mohammad

    2008-08-01

    A novel superabsorbent hydrogel composite based on Collagen have been prepared via graft copolymerization of Methacrylic acid (MAA) in the presence of kaolin powder using methylenebisacrylamide (MBA) as a crosslinking agent and ammonium persulfate (APS) as an initiator. The composite structure was confirmed using FTIR spectroscopy. A new absorption band at 1728 cm-1 in the composite spectrum confirmed kaolin-organic polymer linkage. The effect of kaolin amount and MBA concentration showed that with increasing of these parameters, the water absorbency of the superabsorbent composite was decreased. The swelling measurements of the hydrogels were conducted in aqueous salt solutions.

  12. On the non-linear attachment characteristics of blood to bacterial cellulose/kaolin biomaterials.

    PubMed

    Véliz, Diosángeles Soto; Alam, Catharina; Toivola, Diana M; Toivakka, Martti; Alam, Parvez

    2014-04-01

    In this communication, we report a non-linear variation in the strength of blood attachment to bacterial cellulose/kaolin biomaterials as the fractions of bacterial cellulose to kaolin are increased. The changes observed for attachment strength are elucidated following both experimental and numerical investigations on both the biomaterial and the blood-biomaterial interface. Our research reveals that the non-linear strength of attachment of blood is related to topographical characteristics on the surface of the biomaterial, the maleability of the biomaterial and the intermolecular strength of attraction between clotted blood proteins (fibrinogen) with the cellulose/kaolin components of the biomaterial.

  13. Bentonite borehole plug flow testing with five water types

    SciTech Connect

    Gaudette, M.V.; Daemen, J.J.K.

    1988-04-01

    The hydraulic conductivity has been determined of plugs constructed with commercial precompressed bentonite pellets. Bentonite has been hydrated and tested with waters of five different chemical compositions, including one groundwater (Ogallala aquifer, Texas). The groundwater contained a significant amount of solids: waters prepared in the laboratory did not. Prepared waters used for testing included distilled water, a high (1000 ppM) and a low (45 ppM) calcium solution, and a 39 ppM sodium water. Uncompacted plugs were constructed by dropping bentonite tablets into waterfilled cylinders, or by mixing powdered bentonite with preselected water volumes in order to obtain controlled initial water contents. The hydraulic conductivity of all plugs tested with all waters would result in a classification of practically impervious, by conventional soil mechanics standards. Variations of several orders of magnitude of the hydraulic conductivity are observed.

  14. Temperature influence on structural changes of foundry bentonites

    NASA Astrophysics Data System (ADS)

    Holtzer, Mariusz; Bobrowski, Artur; Żymankowska-Kumon, Sylwia

    2011-10-01

    The results of investigations of three calcium bentonites, activated by sodium carbonate, applied in the foundry industry as binding material for moulding sands, subjected to the influence of high temperatures - are presented in the paper. Investigations were performed by the thermal analysis (TG) method, the infrared spectroscopy (FTIR) method and the modern Cu(II)-TET complex method (used for the determination of the montmorillonite content in bentonite samples). The occurrence of the dehydration process and two-stage dehydroxylation process was confirmed only for bentonite no. 2. This probably indicates that cis- and trans-isomers are present in the octahedric bentonite structure. Tests were performed at temperatures: 500, 550, 700, 900, 1000, 1100, 1200 °C.

  15. Modified Ponorogo bentonite for the removal of ampicillin from wastewater.

    PubMed

    Rahardjo, Andi Kurniawan; Susanto, Maria Josephine Jeannette; Kurniawan, Alfin; Indraswati, Nani; Ismadji, Suryadi

    2011-06-15

    The adsorption of ampicillin onto natural and organo-bentonite was studied. Organo-bentonite was obtained by modifying the natural bentonite obtained from Ponorogo, Indonesia, using CTAB surfactant by microwave heating. The temperature dependent form of the Langmuir, Freundlich, Sips and Toth equations was employed to correlate equilibrium data. Based on the evaluation of the physical meaning of fitted isotherm parameters of each model, it is clear that Toth equation can represent the equilibrium data better than other models. The adsorption performance of natural and organo-bentonite for the removal of ampicillin from pharmaceutical company wastewater was also studied. In real wastewater, both adsorbents could not completely remove the ampicillin due to the sorption competition with other substances which also present in the wastewater.

  16. Microstructure of bentonite in iron ore green pellets.

    PubMed

    Bhuiyan, Iftekhar U; Mouzon, Johanne; Schröppel, Birgit; Kaech, Andres; Dobryden, Illia; Forsmo, Seija P E; Hedlund, Jonas

    2014-02-01

    Sodium-activated calcium bentonite is used as a binder in iron ore pellets and is known to increase strength of both wet and dry iron ore green pellets. In this article, the microstructure of bentonite in magnetite pellets is revealed for the first time using scanning electron microscopy. The microstructure of bentonite in wet and dry iron ore pellets, as well as in distilled water, was imaged by various imaging techniques (e.g., imaging at low voltage with monochromatic and decelerated beam or low loss backscattered electrons) and cryogenic methods (i.e., high pressure freezing and plunge freezing in liquid ethane). In wet iron ore green pellets, clay tactoids (stacks of parallel primary clay platelets) were very well dispersed and formed a voluminous network occupying the space available between mineral particles. When the pellet was dried, bentonite was drawn to the contact points between the particles and formed solid bridges, which impart strength to the solid compact.

  17. Diffusion behavior for Se and Zr in sodium-bentonite

    SciTech Connect

    Sato, Haruo; Yui, Mikazu; Yoshikawa, Hideki

    1995-12-31

    Apparent diffusion coefficients for Se and Zr in bentonite were measured by in-diffusion method at room temperature using water-saturated sodium-bentonite, Kunigel V1{reg_sign} containing 50wt% Na-smectite as a major mineral was used as the bentonite material. The experiments were carried out in the dry density range of 400--1,800 kg/m{sup 3}. Bentonite samples were immersed with distilled water and saturated before the experiments. The experiments for Se were carried out under N{sub 2} atmospheric condition (O{sub 2}: 2.5ppm). Those for Zr were carried out under aerobic condition. The apparent diffusion coefficients decrease with increasing density of the bentonite. Since dominant species of Se in the pore water is predicted to be SeO{sub 3}{sup 2{minus}}, Se may be retarded by anion-exclusion because of negative charge on the surface of the bentonite and little sorption. The dominant species of Zr in the porewater is predicted to be Zr(OH){sub 5}{sup {minus}} or HZrO{sub 3}{sup {minus}}. Distribution coefficient measured for Zr on the bentonite was about 1.0 m{sup 3}/kg from batch experiments. Therefore, the retardation may be caused by combination of the sorption and the anion-exclusion. A modeling for the diffusion mechanisms in the bentonite were discussed based on an electric double layer theory. Comparison between the apparent diffusion coefficients predicted by the model and the measured ones shows a good agreement.

  18. Physical and Permeability Characteristic of Recycle Glass-Kaolin Ceramic

    SciTech Connect

    Sahar, M. R.; Safwan, A. P; Noorhidayah, C. M.

    2010-07-07

    A series of Recycle Glass-Kaolin ceramic has successful been made by solid state reaction and their physical and permeability characteristic has been studied. Infrared spectroscopy has been used to characterize the effect of OH group in the sample. It is found that the bulk density is in the range of 1.785gcm{sup -3} to 2.2817gcm{sup -3} while the impact energy is 1.785gcm{sup -3} to 2.2817gcm{sup -3} depending on the cullet content. Meanwhile, the permeability coefficient is found to be 5.208x10{sup -4}cms{sup -1} to 1.812x10{sup -4}cms{sup -1} which is in the reducing trend. The IR Spectroscopy shows that the OH group decrease, the permeability decreases.

  19. Evaluation of reclaimed abandoned bentonite mine lands

    SciTech Connect

    Edinger, K.D.; Schuman, G.E.; Vance, G.F.

    1999-07-01

    In 1985, the Abandoned Mined Land Division of the Wyoming Department of Environmental Quality began reclamation of 4,148 ha of abandoned bentonite mined lands. Calcium amendments and sawmill wood wastes were applied to the regraded spoils to enhance water infiltration, displacement of Na on the clay spoil, and leaching of the displaced Na and other soluble salts. Revegetation of these lands was generally successful, but after several years small areas (0.1--0.2 ha) began to show signs of vegetation die-back and to prescribe corrective treatment options. A randomized block design was imposed on study areas near Upton, Colony, and Greybull, Wyoming to characterize spoil chemical properties of good, moderate, and dead vegetation zones, which were subjectively delineated by visual vegetation cover and density differences. Spoil analyses indicated exchangeable-sodium (Na) concentrations were high and the dead vegetation zones exhibited exchangeable-sodium-percentages (ESP) above 50%, while surrounding good vegetation zones exhibited ESP values <10%. This coupled with low soluble-Na concentrations (<2 cmol/kg) suggests insufficient calcium (Ca) amendments were initially applied to ameliorate the sodic conditions of the spoil. The sampling design used to determine Ca amendment rates, which consisted of a composite of 5 spoil cores taken from each 0.8 ha area, was apparently insufficient to account for the highly heterogeneous spoil material that occurred throughout these abandoned bentonite reclamation sites. To revegetate these small degraded sites, additional Ca amendment would be necessary and reseeding would be required. However, the authors recommend further monitoring of the affected sites to determine if unfavorable conditions continue to degrade the reclaimed landscape before any attempt is made to rehabilitate the affected sites. If the degraded sites are stable, further Remediation efforts are not warranted because small areas of little or no vegetation are

  20. The study of aluminum loss and consequent phase transformation in heat-treated acid-leached kaolin

    SciTech Connect

    Foo, Choo Thye; Mahmood, Che Seman; Mohd Salleh, Mohamad Amran

    2011-04-15

    This study investigates the effect of Al leaching during Fe removal from kaolin to mullite. Heat-treated kaolin was obtained by heating natural kaolin at 400, 500, 600, 700, 800 and 900 deg. C. The heat-treated kaolin was then leached at 100 deg. C with 4 M, 3 M, 2 M, 1 M, 0.2 M solution of H{sub 2}SO{sub 4} and 0.2 M solution of oxalic acid. The dried samples were sintered to 1300 deg. C for 4 h at a heating rate of 10 deg. C min{sup -1}. X-ray diffractometry and differential thermal analysis were used to study the phase transformation of kaolin to mullite. It was found that 700 deg. C is the optimum preheat-treatment temperature to leach out Fe and also Al for both types of the acids used. The majority of the 4 M sulfuric acid-treated kaolins formed the cristobalite phase when sintered. On the other hand, 1 M, 0.2 M sulfuric acid and 0.2 M oxalic acid leached heat-treated kaolin formed mullite and quartz phase after sintering. - Research Highlights: {yields} Preheat-treatment of kaolin improves the leachability of unwanted iron. {yields} The optimum preheat-treatment temperature is 700 deg. C. {yields} Sintered 4 M sulfuric acid-treated kaolin majorly formed the cristobalite phase. {yields} Sintered 0.2 M oxalic acid-treated kaolin formed lesser amorphous silicate phase.

  1. A novel electrochemical alkylation of aniline with methanol over Zn/Cu salts modified kaolin.

    PubMed

    Ma, Hongzhu; Wang, Bo; Zhao, Jun

    2008-04-01

    A novel liquid phase alkylation of aniline with methanol over Zn/Cu salts modified kaolin assisted with a pair of porous carbon electrode in slurry-bed reactor under constant current intensity, room temperature and atmospheric pressure was reported. The Zn/Cu salts modified kaolin catalysts were synthesized and characterized by infrared spectrometer (IR), powder X-ray diffraction (XRD) and scanning electron microscopy (SEM), which showed that the transition metals were completely supported on kaolin's structure and formed a pored one. The effect parameters, such as initial pH, electrolysis time, metal ratio with kaolin and salts composition in this electrochemical catalytic system, were studied. The procedure was inspected by ultraviolet-visible spectrum (UV-vis), and the product distribution was detected by gas chromatography/mass spectrometry (GC/MS). In addition, a possible reaction mechanism was also proposed.

  2. Facile Selective and Diverse Fabrication of Superhydrophobic, Superoleophobic-Superhydrophilic and Superamphiphobic Materials from Kaolin.

    PubMed

    Qu, Mengnan; Ma, Xuerui; He, Jinmei; Feng, Juan; Liu, Shanshan; Yao, Yali; Hou, Lingang; Liu, Xiangrong

    2017-01-11

    As the starting material, kaolin is selectively and diversely fabricated to the superhydrophobic, superoleophobic-superhydrophilic, and superamphiphobic materials, respectively. The wettability of the kaolin surface can be selectively controlled and regulated to different superwetting states by choosing the corresponding modification reagent. The procedure is facile to operate, and no special technique or equipment is required. In addition, the procedure is cost-effective and time-saving and the obtained super-repellent properties are very stable. The X-ray photoelectron spectroscopy analysis demonstrates different changes of kaolin particles surfaces which are responsible for the different super-repellency. The scanning electron microscopy displays geometric micro- and nanometer structures of the obtained three kinds of super-repellent materials. The results show that kaolin has good applications in many kinds of superwetting materials. The method demonstrated in this paper provides a new strategy for regulating and controlling the wettability of solid surfaces selectively, diversely, and comprehensively.

  3. Adsorption of 2-mercaptobenzothiazole from aqueous solution by organo-bentonite.

    PubMed

    Jing, Ping; Hou, Meifang; Zhao, Ping; Tang, Xiaoyan; Wan, Hongfu

    2013-06-01

    The adsorption behavior of 2-mercaptobenzothiazole onto organo-bentonite was investigated. Natural bentonite from Gaozhou in Guangdong Province, China was collected. Organo-bentonite was prepared by intercalation of cetyltrimethyl ammonium bromide into the natural bentonite. The physicochemical properties of the prepared organo-bentonite were characterized by X-ray diffraction, N2 adsorption-desorption isotherm and Fourier transform infrared spectroscopy. The results showed that montmorillonite is the main component of the natural bentonite. The basal spacing of the natural bentonite is 1.47 nm, which increased to 1.98 nm on intercalation with cetyltrimethyl ammonium bromide. Moreover, both the surface area and pore volume increased with intercalation. Clear CH2 stretching (3000-2800 cm(-1)) and scissoring (1480-1450 cm(-1)) modes of the intercalated surfactants were observed for organo-bentonite. Compared with the pseudo first-order kinetic model, the pseudo second-order kinetic model is more suitable to describe the adsorption kinetics of 2-mercaptobenzothiazole onto organo-bentonite. The adsorption capacity of 2-mercaptobenzothiazole onto organo-bentonite increased with increasing initial concentration of 2-mercaptobenzothiazole, but decreased with increasing adsorbent dosage. The adsorption isotherm of 2-mercaptobenzothiazole onto organo-bentonite fits well with the Langmuir model. The maximum adsorption capacity of organo-bentonite for 2-mercaptobenzothiazole was 33.61 mg/g, indicating that organo-bentonite is a promising adsorbent for 2-mercaptobenzothiazole.

  4. Modification of bentonite with cationic surfactant for the enhanced retention of bisphenol A from landfill leachate.

    PubMed

    Li, Yi; Jin, Fenglai; Wang, Chao; Chen, Yunxiao; Wang, Qing; Zhang, Wenlong; Wang, Dawei

    2015-06-01

    Bentonite was modified with cationic surfactant hexadecyl trimethyl ammonium bromide (HTAB) as landfill liner to retard the transportation of bisphenol A (BPA) for the first time. The modification was confirmed to form a lateral bi-layer in the interlayer space of bentonite by scanning electron microscope, X-ray diffraction, and Fourier transform infrared spectroscopy. The introduction of HTAB into the internal position of bentonite led to an increased interlayer space of bentonite from 15.0 to 20.9 Å and a higher sorption affinity for BPA (10.449 mg/g of HTAB-bentonite and 3.413 mg/g of raw bentonite). According to the Freundlich model, the maximum adsorption capacity of the HTAB-bentonite was found to be 0.410 mg/g. The sorption capacity of raw bentonite and HTAB-bentonite both decreased at alkaline conditions. Although the hydraulic conductivity of HTAB-bentonite was higher than that of raw bentonite, results of laboratory permeability and column tests indicated that HTAB-bentonite obviously extended the BPA breakthrough time by 43.4 %. The properties of the HTAB-bentonite revealed its notable advantages as components of landfill liners material to retain BPA in leachate.

  5. Distribution, characteristics, and worldwide inventory of dioxins in kaolin ball clays.

    PubMed

    Horii, Yuichi; Ohtsuka, Nobutoshi; Minomo, Kotaro; Nojiri, Kiyoshi; Kannan, Kurunthachalam; Lam, Paul K S; Yamashita, Nobuyoshi

    2011-09-01

    Distribution, characteristics, and global inventory of dioxins (polychlorinated dibenzo-p-dioxins [PCDDs] and dibenzofurans [PCDFs] and dioxin like polychlorinated biphenyls) in kaolin clays collected from 10 countries were investigated. Dioxins were found in all kaolin clay samples analyzed, at total concentrations ranging from 1.2 pg/g (Brazil) to 520,000 pg/g (USA). Dioxin concentrations in kaolin clays from a few countries (e.g., Brazil and UK) were lower than those reported for background soils in Japan. Dioxin profiles in kaolin clays were characterized by the domination of the congener octachlorodibenzo-p-dioxin (OCDD), and the concentrations of other congeners decreased in the order of reduction in the levels of chlorination. Furthermore, specific distribution of congeners, with predominant proportions of 1,4,6,9-substituted PCDDs within each homologue group, was found in most clay samples. The ratios of concentrations of PCDD to PCDF and 1,2,3,7,8,9-HxCDD to 1,2,3,6,7,8-HxCDD indicated differences in the profiles found for anthropogenic sources (including pentachlorophenol) and kaolin clays. Concentrations of PCDD/Fs in kaolin clays, except for American ball clays, did not exceed the environmental criteria set by the Law Concerning Special Measures against Dioxins in Japan. Based on the average concentrations measured in our study, inventories of PCDD/Fs from the production/usage of ball clays on a global scale were estimated to be 650 kg/yr; the corresponding value on a TEQ basis is 2400 g-TEQ/yr. More than 480 kg of OCDD is estimated to be released annually from the production of kaolin clays worldwide, suggesting that kaolin clays can be a major contributor for additional source of dioxins, especially OCDD, in the environment.

  6. The effect of activated dimethicone, other antacid constituents, and kaolin on the absorption of propranolol.

    PubMed

    McElnay, J C; D'Arcy, P F; Leonard, J K

    1982-05-15

    A study was made of the effect of 6 commonly used gastrointestinal preparations on the absorption of propranolol using an in vitro experimental model. The constituents examined were activated dimethicone, aluminium hydroxide gel, bismuth carbonate, kaolin, magnesium carbonate, and magnesium trisilicate. A slight decreased propranolol absorption was given by kaolin (-13.0%), the other components showed smaller effects ranging from -6.8% to +6.6%. None of the results were statistically significantly different from control absorption values.

  7. Assembling strategy to synthesize palladium modified kaolin nanocomposites with different morphologies

    NASA Astrophysics Data System (ADS)

    Li, Xiaoyu; Ouyang, Jing; Zhou, Yonghua; Yang, Huaming

    2015-09-01

    Nanocomposites of aluminosilicate minerals, kaolins (kaolinite and halloysite) with natural different morphologies assembling with palladium (Pd) nanoparticles have been successfully synthesized through strong electrostatic adsorption and chemical bonding after surface modification with 3-aminopropyl triethoxysilane (APTES). Meanwhile, the influence of different morphologies supports on catalytic hydrogenation properties was explored. The surface concentration of amino groups on the kaolins was related to the morphology and surface nature. Electronmicroscopy revealed that the monodisperse Pd nanoparticles were uniformly deposited onto the surface of kaolins, ranging in diameter from 0.5 nm to 5.5 nm. The functional groups could not only improve the dispersion of kaolins with different morphologies in solution, but also enhance the interaction between Pd precursors and kaolins, thus preventing small Pd nanoparticles from agglomerating and leading to high activity for the catalytic hydrogenation of styrene. Pd-FK@APTES was more active compared to other samples. Selecting the kaolin morphology with a different surface nature allows the selective surface modification of a larger fraction of the reactive facets on which the active sites can be enriched and tuned. This desirable surface coordination of catalytically active atoms could substantially improve catalytic activity.

  8. Study on the origin of kaolin tonsteins in North China and its processing technology

    SciTech Connect

    Yang, Xiaojie; Liu Qinfu; Li Qijun

    1998-12-31

    Kaolin Tonstein, occurring in Permo-Carboniferous Coal measures in North China, is a kind of kaolinitic clay material, which is different from that in Germany, France, Russia, US. and other European-American Countries, featuring thick-bedded, wide-spread and good quality coal. The thickness of kaolin tonsteins in North China is 70 cm or so, but that in the above-mentioned countries only 3 cm. From Hunjiang County, Jilin Province to Handan County, Gansu Province, from Huainan and Huaibei coal field to Inner Mongolia coalfield, kaolin tonstein deposits are scattered over vast areas on the North China Platform with great proved reserves of 1.6 billion tons. It is of great interest and high significance to study the mineralization mechanism of kaolin tonsteins for its processing and utilization. By means of mineralogy, petrology, geochemistry and organic chemistry, the origin of kaolin tonsteins has been systematically deliberated and the origin model of it has been proposed. On the basis of this, the processing technology of kaolin tonsteins has been put forward, which has been successfully employed in China.

  9. Conversion of waste polypropylene to liquid fuel using acid-activated kaolin.

    PubMed

    Panda, Achyut K; Singh, R K

    2014-10-01

    Waste polypropylene was subjected to thermal degradation in the presence of kaolin and acid-treated kaolin, with different catalyst-to-plastics ratios, in a semi-batch reactor at a temperature range of 400-550°C to obtain optimized process conditions for the production of liquid fuels. The effects of process temperature, catalyst and feed composition on yield and quality of the oil were determined. For a thermal decomposition reaction at up to 450°C, the major product is volatile oil; and the major products at a higher temperature (475-550°C) are either viscous liquid or wax. The highest yield of condensed fraction in the thermal reaction is 82.85% by weight at 500°C. Use of kaolin and acid-treated kaolin as a catalyst decreased the reaction time and increased the yield of liquid fraction. The major product of catalysed degradation at all temperatures is highly volatile liquid oil. The maximum oil yield using kaolin and acid-treated kaolin is 87.5% and 92%, respectively, at 500°C. The oil obtained was characterized using GC-MS for its composition and different fuel properties by IS methods.

  10. Modeling interaction of deep groundwaters with bentonite and radionuclide speciation

    SciTech Connect

    Wanner, H.

    1987-12-01

    Based on available experimental data on the interaction of sodium bentonite and groundwater, a model has been developed that represents a means of extrapolation from laboratory data to the conditions in compacted bentonite. The basic reactions between sodium bentonite and groundwater are described by an ion exchange model for sodium, potassium, magnesium, and calcium. The model also assumes equilibrium with calcite and quartz. The calculations are carried out for two types of granitic groundwater: the Swiss reference groundwater (ionic strength I = 0.24 M) and the standard Swedish groundwater (I = 0.0044 M). It is calculated that the pore water of compacted sodium bentonite will have a pH of 9.7 and a carbonate activity of 8 x 10/sup -4/ M if the dry bentonite is saturated with Swiss reference groundwater; it will have a pH near 10.2 and )CO/sub 3//sup 2-/) = 8 x 10/sup -3/ M for standard Swedish groundwater. The long-term situation, which is important for nuclear waste disposal, is modeled by the assumption that the near field of a radioactive waste repository behaves like a mixing tank. It is calculated that sodium bentonite will be slowly converted to calcium bentonite over a long period. The model is used to calculate short- and long-term maximum solubilities of thorium, uranium, neptunium, plutonium, americium, and technetium in the near-field pore water of a potential Swiss nuclear waste repository. The redox potential in the near field is assumed to be controlled by the corrosion products of the iron canister.

  11. Chitosan-kaolin coprecipitate as disintegrant in microcrystalline cellulose-based pellets elaborated by extrusion-spheronization.

    PubMed

    Goyanes, Alvaro; Souto, Consuelo; Martínez-Pacheco, Ramón

    2013-02-01

    The usefulness of a coprecipitate of chitosan and kaolin as disintegrant in the pellets of microcrystalline cellulose (MCC) and hydrochlorothiazide (HCT) (as a model of poorly water-soluble drug) produced by extrusion-spheronization was evaluated in this study. The effectiveness of chitosan-kaolin coprecipitate to increase the dissolution rate was compared with that of kaolin and chitosan. A possible synergy effect was also evaluated between the coprecipitate, kaolin or chitosan and sorbitol, added to the pellets as a very water-soluble diluent. The chitosan-kaolin coprecipitate, the kaolin or the chitosan allowed pellets to be obtained of adequate size, roundness, mechanical strength and flow properties. Furthermore, the incorporation of chitosan-kaolin coprecipitate or chitosan significantly increased the dissolution rate of HCT independently of the sorbitol content. The effects on the dissolution of HCT derived from the incorporation of coprecipitate to the pellets can be attributed to its content of chitosan. However, the addition of kaolin into the pellets did not significantly affect the HCT dissolution process. The pellets incorporating coprecipitated chitosan-kaolin or chitosan and the maximum proportion of sorbitol (50%) led to the highest HCT dissolution rate and experienced a rapid and complete disintegration in the dissolution medium.

  12. Porosity investigation of compacted bentonite using XRD profile modeling

    NASA Astrophysics Data System (ADS)

    Holmboe, Michael; Wold, Susanna; Jonsson, Mats

    2012-02-01

    Many countries intend to use compacted bentonite as a barrier in their deep geological repositories for nuclear waste. In order to describe and predict hydraulic conductivity or radionuclide transport through the bentonite barrier, fundamental understanding of the microstructure of compacted bentonite is needed. This study examined the interlayer swelling and overall microstructure of Wyoming Bentonite MX-80 and the corresponding homo-ionic Na + and Ca 2 + forms, using XRD with samples saturated under confined swelling conditions and free swelling conditions. For the samples saturated under confined conditions, the interparticle, or so-called free or external porosity was estimated by comparing the experimental interlayer distances obtained from one-dimensional XRD profile fitting against the maximum interlayer distances possible for the corresponding water content. The results showed that interlayer porosity dominated total porosity, irrespective of water content, and that the interparticle porosity was lower than previously reported in the literature. At compactions relevant for the saturated bentonite barrier (1.4-1.8 g/cm 3), the interparticle porosity was estimated to ≤ 3%.

  13. [Sorption characteristics of surfactant onto bentonite using microwave irradiation].

    PubMed

    Li, Ji-Wu; Zhu, Li-Zhong; Cai, Wei-Jian

    2007-11-01

    The sorption curve of cetylpyridinium chloride (CPC) onto bentonite by microwave irradiation was studied. The effects of microwave reaction time and CPC concentration on interlayer spacing and organic carbon content of organobentonite were tested, respectively. Thermodynamics and kinetics of sorption of CPC onto bentonite by microwave irradiation were studied. The saturated adsorption amount of CPC to bentonite with microwave irradiation time from 90 s to 120 s was equal to that of conventional sorption, up to 0.001 63 mol x g(-1). On the condition of microwave irradiation time with 2 min and concentration of CPC with 1.20 mmol x L(-1), the interlayer spacing was attained to 2.44 nm at the best, and organic carbon content was 23.45%. The atomic force microscopy (AFM) showed that the typical layer morphological structure of bentonite was not devastated by microwave. Contrast to conventional sorption, sorption of CPC onto bentonite was greatly influenced by microwave, velocity constant of sorption reaction was increased 107.6 times, and free energy of sorption reaction system was decreased.

  14. Bentonite-amended soil special study. Phase 1 evaluation report

    SciTech Connect

    Not Available

    1989-12-01

    This special study was conducted to assess the viability of soil with a high percentage of bentonite added as an infiltration barrier in the cover of Uranium Mill Tailings Remedial Action (UMTRA) Project disposal cells. To achieve maximum concentration limits (MCLs) at several UMTRA Project sites, covers with a very low permeability are needed. If alternate concentration limits (ACLs) are the appropriate site groundwater compliance strategy, the US Department of Energy (DOE) is required to demonstrate, among other things, that the infiltration to the disposal cell is as low as reasonably achievable, and hence that the cover has a very low permeability. When the study discussed here was begun, the lowest permeability element available was CLAYMAX{sub R}, a manufactured liner material constructed of natural material (bentonite clay) between two geosynthetics.The strength of soil-bentonite mixes was measured to see if they could be placed on sideslopes and not pose stability problems. Also evaluated were the hydraulic conductivities of soil-bentonite mixes. If the strengths and permeabilities of soils with a high percentage of bentonite are favorable, the soils may be used as infiltration barriers in current cover designs without changing pile geometries. The scope of work for this study called for a literature review and a two-phased laboratory testing program. This report presents the results of the literature review and the first phase of the testing program.

  15. Porewater chemistry in compacted re-saturated MX-80 bentonite

    NASA Astrophysics Data System (ADS)

    Bradbury, Michael H.; Baeyens, Bart

    2003-03-01

    Bentonites of various types are being investigated in many countries as backfill materials in high-level radioactive waste disposal concepts. Being able to understand the chemistry of the porewater in compacted bentonite is very important since it is critical to predicting radionuclide solubilities and to the synthesis of sorption data bases, and hence to repository safety studies. In this paper, porewater compositions in compacted bentonites are calculated, taking into consideration such factors as montmorillonite swelling, semi-permeable membrane effects, very low "free water" volumes, and the highly effective buffering characteristics of the exchangeable cations and the amphoteric edge sites. The former buffer the cation concentrations and the latter fix the pH in the porewater of a re-saturated bentonite. The above considerations are used in conjunction with previously measured physico-chemical characterisation data on MX-80 powder to calculate porewater compositions in compacted bentonites. For the MX-80 material specified, the porewaters calculated for initial dry densities between 1200 and 1600 kg m -3 had relatively high ionic strengths (I ˜0.3 M), similar cation concentrations and a pH equal to 8.0. The porewaters changed from being Na 2SO 4-rich at 1200 kg m -3 to a NaCl/Na 2SO 4 type water at 1600 kg m -3.

  16. Contact activation of blood coagulation on a defined kaolin/collagen surface in a microfluidic assay.

    PubMed

    Zhu, Shu; Diamond, Scott L

    2014-12-01

    Generation of active Factor XII (FXIIa) triggers blood clotting on artificial surfaces and may also enhance intravascular thrombosis. We developed a patterned kaolin (0 to 0.3 pg/μm(2))/type 1 collagen fibril surface for controlled microfluidic clotting assays. Perfusion of whole blood (treated only with a low level of 4 μg/mL of the XIIa inhibitor, corn trypsin inhibitor) drove platelet deposition followed by fibrin formation. At venous wall shear rate (100 s(-1)), kaolin accelerated onset of fibrin formation by ~100 sec when compared to collagen alone (250 sec vs. 350 sec), with little effect on platelet deposition. Even with kaolin present, arterial wall shear rate (1000 s(-1)) delayed and suppressed fibrin formation compared to venous wall shear rate. A comparison of surfaces for extrinsic activation (tissue factor TF/collagen) versus contact activation (kaolin/collagen) that each generated equal platelet deposition at 100 s(-1) revealed: (1) TF surfaces promoted much faster fibrin onset (at 100 sec) and more endpoint fibrin at 600 sec at either 100 s(-1) or 1000 s(-1), and (2) kaolin and TF surfaces had a similar sensitivity for reduced fibrin deposition at 1000 s(-1) (compared to fibrin formed at 100 s(-1)) despite differing coagulation triggers. Anti-platelet drugs inhibiting P2Y1, P2Y12, cyclooxygenase-1 or activating IP-receptor or guanylate cyclase reduced platelet and fibrin deposition on kaolin/collagen. Since FXIIa or FXIa inhibition may offer safe antithrombotic therapy, especially for biomaterial thrombosis, these defined collagen/kaolin surfaces may prove useful in drug screening tests or in clinical diagnostic assays of blood under flow conditions.

  17. Tranexamic acid induces kaolin intake stimulating a pathway involving tachykinin neurokinin 1 receptors in rats.

    PubMed

    Kakiuchi, Hitoshi; Kawarai-Shimamura, Asako; Kuwagata, Makiko; Orito, Kensuke

    2014-01-15

    Tranexamic acid suppresses post-partum haemorrhage and idiopathic menorrhagia through its anti-fibrinolytic action. Although it is clinically useful, it is associated with high risks of side effects such as emesis. Understanding the mechanisms underlying tranexamic acid-induced emesis is very important to explore appropriate anti-emetic drugs for the prevention and/or suppression of emesis. In this study, we examined the receptors involved in tranexamic acid-induced kaolin intake in rats, which reflects the drug's clinical emetogenic potential in humans. Further, we examined the brain regions activated by administration of tranexamic acid and elucidated pivotal pathways of tranexamic acid-induced kaolin intake. We examined the effects of ondansetron, a 5-hydroxytryptamine 3 receptor antagonist, domperidone, a dopamine 2 receptor antagonist, and aprepitant, a tachykinin neurokinin 1 (NK1) receptor antagonist, on tranexamic acid-induced kaolin intake in rats. Then, we determined the brain regions that showed increased numbers of c-Fos immunoreactive cells. Finally, we examined the effects of an antagonist(s) that reduced tranexamic acid-induced kaolin intake on the increase in c-Fos immunoreactive cells. Aprepitant significantly decreased tranexamic acid-induced kaolin intake. However, neither ondansetron nor domperidone decreased kaolin intake. Tranexamic acid significantly increased c-Fos immunoreactive cells by approximately 5.5-fold and 22-fold in the area postrema and nucleus of solitary tract, respectively. Aprepitant decreased the number of c-Fos immunoreactive cells in both areas. Tranexamic acid induced kaolin intake possibly via stimulation of tachykinin NK1 receptors in rats. The tachykinin NK1 receptor could be targeted to prevent and/or suppress emesis in patients receiving tranexamic acid.

  18. [Forming mechanism of humic acid-kaolin complexes and the adsorption of trichloroethylene].

    PubMed

    Zhu, Xiao-jing; He, Jiang-tao; Su, Si-hui

    2015-01-01

    The interaction between soil organic components and mineral components was explored in this study. Humic acid and kaolin were used for the preparation of organic-mineral complexes with different contents of organic matter, for experimental study of the adsorption of trichloroethylene. The results showed that the adsorption of trichlorethylene fitted the Freundlich isotherm model. The existence of interaction between humic acid and kaolin was indicated by the significant difference between the actual value and the theoretically overlaid value of the adsorption capacity. With various characterizations, such as FTIR and surface area & pore analysis, the mechanism of interaction between humic acid and kaolin was suggested as follows. When their contents were low, humic acid molecules firstly loaded on the surface binding sites of kaolin. Then with the content increased, as O/M( organic-mineral mass ratio) was 0.02-0.04, some surface pores of kaolin were filled by part of the molecules. After reaching a relatively stable stage, as O/M was 0.04-0.08, humic molecules continued to load on the surface of kaolin and formed the first humic molecule-layer. With humic acid content continued increasing, as O/M was 0.08-0.10, more humic molecules attached to kaolin surface through the interaction with the first layer of molecules and then formed the second layer. O/M was 0.10-0.16 as the whole second layer stage, meanwhile the first layer was compressed. Then when O/M was 0.16-0.4, there were still some humic loadings onto the second layer as the third layer, and further compressed the inner humic acid layers. Besides, some humic acid molecules or aggregates might go on attaching to form as further outer layer.

  19. Diffusion, sorption, and retardation processes of anions in bentonite and organo-bentonites for multibarrier systems

    NASA Astrophysics Data System (ADS)

    Schampera, Birgit; Dultz, Stefan

    2013-04-01

    The low permeability, high cation exchange capacity (CEC) and plasticity of bentonites favor their use in multibarrier systems of waste deposits [1]. Bentonites have a high CEC but their ability to sorb anions is very low. There is, however, need for retardation of anions and organic pollutants in many applications. Bentonites, modified with certain organic cations, have the capacity to sorb anions and non-polar organic compounds in addition to cations. Investigations on organically modified clays address a wide variety of applications including immobilization of pollutants in contaminated soils, waste water treatment and in situ placement for the protection of ground water [2]. Many experiments on anion and cation sorption of organo-clays were conducted in the batch mode which does not reflect solid-liquid ratios and material densities in barrier systems. Diffusion experiments on compacted clays allow the evaluation of transport processes and sorption of pollutants at conditions relevant for repositories. For organo-clays only few diffusion studies are published e.g. [3] measured the diffusion of tritium and [4] the diffusion of H2O in bentonite and organo-bentonites. The organic cation hexadecylpyridinium (HDPy) was added to Wyoming bentonite (MX-80) in amounts corresponding to 2-400 % of the CEC. The uptake of organic cations was determined by the C-content, XRD and IR-spectroscopy. Wettability was analyzed by the contact angle. Physical, chemical and mineralogical properties of clays were characterized. Diffusion experiments were carried out in situ in a cell attached to the ATR-unit of a FTIR-spectrometer. For H2O-diffusion the compacted organo-clays are saturated first with D2O, afterwards H2O is supplied to the surface at the top of the clay platelet. Anion-diffusion was conducted with NO3--solution instead of H2O only having characteristic IR band positions at 1350 cm-1. Three different concentrations (0.25M, 0.5M and 1M) were used. Additional batch

  20. Synthesis of glass ceramics from kaolin and dolomite mixture

    NASA Astrophysics Data System (ADS)

    Boudchicha, Mohamed Reda; Rubio, Fausto; Achour, Slimane

    2017-02-01

    Cordierite- and anorthite-based binary glass ceramics of the CaO-MgO-Al2O3-SiO2 (CMAS) system were synthesized by mixing local and abundant raw minerals (kaolin and doloma by mass ratio of 82/18). A kinetics study reveals that the activation energy of crystallization ( E a) calculated by the methods of Kissinger and Marotta are 438 kJ·mol-1 and 459 kJ·mol-1, respectively. The Avrami parameter ( n) is estimated to be approximately equal to 1, corresponding to the surface crystallization mechanism. X-ray diffraction (XRD) analysis shows that the anorthite and cordierite crystals are precipitated from the parent glass as major phases. Anorthite crystals first form at 850°C, whereas the μ-cordierite phase appears after heat treatment at 950°C. Thereafter, the cordierite allotropically transforms to α-cordierite at 1000°C. Complete densification is achieved at 950°C; however, the density slightly decreases at higher temperatures, reaching a stable value of 2.63 kg·m-3 between 1000°C and 1100°C. The highest Vickers hardness of 6 GPa is also obtained at 950°C. However, a substantial decrease in hardness is recorded at 1000°C; at higher sintering temperatures, it slightly increases with increasing temperature as the α-cordierite crystallizes.

  1. Silurian K-bentonites of the Dnestr Basin, Podolia, Ukraine

    USGS Publications Warehouse

    Huff, W.D.; Bergstrom, Stig M.; Kolata, Dennis R.

    2000-01-01

    The Dnestr Basin of Podolia, Ukraine, is an epicratonic basin consisting of neritic carbonate and calcareous mudstone facies including a nearly complete Silurian sequence ranging from late Llandovery to late Pridoli in age. The Silurian section has served as a standard for regional and interregional studies as a consequence of its well-documented macro- and microfaunal assemblages. Approximately 24 mid- to Late Silurian K-bentonites are present in this succession, and their lateral persistence has aided in establishing regional correlations. The K-bentonites range from 1 to 40 cm in thickness and occur in the Bagovitsa (late Wenlock), Malinovtsy (Ludlow) and Skala (Pridoli) Formations. Discrimination diagrams based on immobile trace elements together with rare earth element data suggest the K-bentonites had a volcanic origin in a collision margin setting related to subduction. Thickness and stratigraphic distribution considerations are consistent with a source area in the Rheic Ocean.

  2. Coupled Hydro-Mechanical Model of Bentonite Hydration and Swelling

    NASA Astrophysics Data System (ADS)

    Hancilova, Ilona; Hokr, Milan

    2016-10-01

    This paper deals with the modelling of coupled hydro-mechanical processes at the buffer and host rock interface (bentonite and granite) in the context of the safe disposal of spent nuclear fuel. Granite, as one of the barriers, includes fractures which are the source for hydration of bentonite and its subsequent swelling. It affects the mechanical behaviour and possibly the stability of the whole system. A non-linear solution for the stress-deformation problem with swelling was developed. This solution is coupled with the non-linear diffusion problem (for unsaturated flow). The swelling is defined using a coefficient dependent on water content according to literature data, with the effective Young's modulus decreasing close to zero corresponding to the plastic state. Results confirm the expected non-uniform saturation, swelling, and stresses in bentonite and small contribution to a fracture displacement.

  3. Provenance of sedimentary kaolin deposits in Egypt: Evidences from the Pb, Sr and Nd isotopes

    NASA Astrophysics Data System (ADS)

    Baioumy, Hassan

    2014-12-01

    This work reports, for the first time, the Pb, Sr and Nd isotopes of the clay fractions (<2 μm) from sedimentary kaolin deposits in Egypt of different ages (Carboniferous and lower Cretaceous), localities (Sinai, Red Sea and Aswan), lithologies (flint and plastic) and clay minerals composition (pure kaolinite and mixture of kaolinite, illite and chlorite) to determine their source area compositions and examine the effect of provenance on their isotopic compositions. Measured (present day) and age-corrected Pb isotopes data (100 and 300 My for the Cretaceous and Carboniferous deposits, respectively) are more or less homogeneous in all deposits regardless of their ages, localities, and compositions. This, therefore, suggests that the Pb isotopes cannot be used as a tracer for source area compositions of these kaolin deposits. On the other hand, the studied kaolin deposits show variations in their measured and age-corrected Sr and Nd isotopes regarding to their ages and compositions. The Carboniferous illite-rich kaolin deposits in the Khaboba and Hasbar areas, Sinai have higher measured and age-corrected 87Sr/86Sr ratios (average of 0.715742 and 0.711156 for measured and age-corrected, respectively) compared to the non-illitic Carboniferous deposit at Abu Natash area (average of 0.70772 and 0.70769 for measured and age-corrected, respectively) and the lower Cretaceous deposits in all areas (average of 0.70827 and 0.70821 for measured and age-corrected, respectively). The Carboniferous kaolin deposits in the Khaboba and Hasbar areas also have lower 143Nd/144Nd ratios (average of 0.51206 and 0.51180 for measured and age-corrected, respectively) compared to the Carboniferous Abu Natash deposit (average of 0.51253 and 0.51231 for measured and age-corrected, respectively) as well as the lower Cretaceous deposits in all areas (average of 0.51248 and 0.51239 for measured and age-corrected, respectively). Initial εNd values are negative in the Carboniferous kaolin deposits

  4. The effect of kaolin on the combustion of demolition wood under well-controlled conditions.

    PubMed

    Khalil, Roger A; Todorovic, Dusan; Skreiberg, Oyvind; Becidan, Michael; Backman, Rainer; Goile, Franziska; Skreiberg, Alexandra; Sørum, Lars

    2012-07-01

    In an attempt to look at means for reduction of corrosion in boilers, combustion experiments are performed on demolition wood with kaolin as additive. The experiments were performed in a multi-fuel reactor with continuous feed of pellets and by applying staged air combustion. A total characterization of the elemental composition of the fuel, the bottom ash and some particle size stages of fly ash was performed. This was done in order to follow the fate of some of the problematic compounds in demolition wood as a function of kaolin addition and other combustion-related parameters. In particular chlorine and potassium distribution between the gas phase, the bottom ash and the fly ash is reported as a function of increased kaolin addition, reactor temperature and air staging. Kaolin addition of 5 and 10% were found to give the least aerosol load in the fly ash. In addition, the chlorine concentration in aerosol particles was at its lowest levels for the same addition of kaolin, although the difference between 5 and 10% addition was minimal. The reactor temperature was found to have a minimal effect on both the fly ash and bottom ash properties.

  5. Effects of humic acid on physical and hydrodynamic properties of kaolin flocs by particle image velocimetry.

    PubMed

    Zhong, Runsheng; Zhang, Xihui; Xiao, Feng; Li, Xiaoyan; Cai, Zhonghua

    2011-07-01

    The physical and hydrodynamic properties of kaolin flocs including floc size, strength, regrowth, fractal structure and settling velocity were investigated by in situ particle image velocimetry technique at different humic acid concentration. Jar-test experimental results showed that the adsorbed humic acid had a significant influence on the coagulation process for alum and ferric chloride. Kaolin flocs formed with the ferric chloride were larger and stronger than those for alum at same humic acid concentration. Floc strength and regrowth were estimated by strength factor and recovery factor at different humic acid concentration. It was found that the increased humic acid concentration had a slight influence on the strength of kaolin flocs and resulted in much worse floc regrowth. In addition, the floc regrowth after breakage depended on the shear history and coagulants under investigation. The changes in fractal structure recorded continuously by in situ particle image velocimetry technique during the growth-breakage-regrowth processes provided a supporting information that the kaolin flocs exhibited a multilevel structure. It was proved that the increased humic acid concentration resulted in decrease in mass fractal dimension of kaolin flocs and consequently worse sedimentation performance through free-settling and microbalance techniques.

  6. Kaolin and copper-based products applications: ecotoxicology on four natural enemies.

    PubMed

    Bengochea, P; Amor, F; Saelices, R; Hernando, S; Budia, F; Adán, A; Medina, P

    2013-05-01

    Lethal and sublethal effects of kaolin clays and two copper-based products on four natural enemies found in olive orchards Anthocoris nemoralis (F.) (Hem. Anthocoridae), Chelonus inanitus (L.) (Hym. Braconidae), Chilocorus nigritus (F.) (Col. Coccinellidae) and Scutellysta cyanea Motschulsky (Hym. Pteromalidae) are described. Both kaolin and copper can be applied for controlling the olive fruit fly and the olive moth, two important pests of this crop. The products did not increase the mortality of any of the insects studied, with the exception of A. nemoralis. The sublethal effects, however, differed depending on the parameter evaluated and the insect studied. Both kaolin and coppers slightly, but significantly, reduced the life span of C. inanitus and S. cyanea. Number of eggs laid by A. nemoralis females were reduced, but not significantly compared to the controls. In the behavioural experiments, clear preference for remaining on kaolin-untreated surfaces when insects were able to choose was observed. Despite having some negative effects, the negative impact on natural enemies was lower than the impact caused by products commonly applied in this crop against the pests stated above. Therefore, both kaolin and copper can be considered as alternative products to be applied in olive orchards if an effective resistance management programme is to be developed. Furthermore, both of them are allowed in organic farming, in which the number of products that can be applied is more restricted.

  7. Effects of kaolin particle films on the life span of an orb-weaver spider.

    PubMed

    Benhadi-Marín, Jacinto; Pereira, José Alberto; Santos, Sónia A P

    2016-02-01

    Araniella cucurbitina (Araneae: Araneidae) is a widespread orb-weaver spider commonly found in agroecosystems. Mineral particle films such as kaolin, due to their protective or anti-feeding action, can represent an alternative to pesticides, especially in organic farming systems, but little is known about its effects on A. cucurbitina. Therefore, we tested the effect of kaolin sprays on the life span of A. cucurbitina under laboratory conditions. Four treatments were tested encompassing different exposure routes. Thus, kaolin sprays were applied on (i) the surface, (ii) the prey (fly), (iii) the spider and (iv) both spider & prey. A control group was tested with water in each treatment. Results showed that sprays of kaolin significantly affected the survival of A. curcubitina when applications were done on the surface and on both spider & prey registering a reduction of 48% and 56%, respectively. Spiders in control obtained higher probability of reaching alive at the end of the assay than those treated with kaolin. Differences observed can be explained by the feeding behavior of the species and may depend on the consumption of the web by the spider and the ratio spider/fly for body size.

  8. Acid activation of bentonites and polymer-clay nanocomposites.

    SciTech Connect

    Carrado, K. A.; Komadel, P.; Center for Nanoscale Materials; Slovak Academy of Sciences

    2009-04-01

    Modified bentonites are of widespread technological importance. Common modifications include acid activation and organic treatment. Acid activation has been used for decades to prepare bleaching earths for adsorbing impurities from edible and industrial oils. Organic treatment has sparked an explosive interest in a class of materials called polymer-clay nanocomposites (PCNs). The most commonly used clay mineral in PCNs is montmorillonite, which is the main constituent of bentonite. PCN materials are used for structural reinforcement and mechanical strength, for gas permeability barriers, as flame retardants, and to minimize surface erosion (ablation). Other specialty applications include use as conducting nanocomposites and bionanocomposites.

  9. Numerical simulation of alteration of sodium bentonite by diffusion of ionic groundwater components

    SciTech Connect

    Jacobsen, J.S.; Carnahan, C.L.

    1987-12-01

    Experiments measuring the movement of trace amounts of radionuclides through compacted bentonite have typically used unaltered bentonite. Models based on experiments such as these may not lead to accurate predictions of the migration through altered or partially altered bentonite of radionuclides that undergo ion exchange. To address this problem, we have modified an existing transport code to include ion exchange and aqueous complexation reactions. The code is thus able to simulate the diffusion of major ionic groundwater components through bentonite and reactions between the bentonite and groundwater. Numerical simulations have been made to investigate the conversion of sodium bentonite to calcium bentonite for a reference groundwater characteristic of deep granitic formations. 20 refs., 2 figs., 2 tabs.

  10. Evolving efficiency of restraining bends within wet kaolin analog experiments

    NASA Astrophysics Data System (ADS)

    Hatem, Alexandra E.; Cooke, Michele L.; Madden, Elizabeth H.

    2015-03-01

    Restraining bends along strike-slip fault systems evolve by both propagation of new faults and abandonment of fault segments. Scaled analog modeling using wet kaolin allows for qualitative and quantitative observations of this evolution. To explore how bend geometry affects evolution, we model bends with a variety of initial angles, θ, from θ = 0° for a straight fault to θ = 30°. High-angle restraining bends (θ ≥ 20°) overcome initial inefficiencies by abandoning unfavorably oriented restraining segments and propagating multiple new, inwardly dipping, oblique-slip faults that are well oriented to accommodate convergence within the bend. Restraining bends with 0° < θ ≤ 15° maintain activity along the restraining bend segment and grow a single new oblique slip fault on one side of the bend. In all restraining bends, the first new fault propagates at ~5 mm of accumulated convergence. Particle Image Velocimetry analysis provides a complete velocity field throughout the experiments. From these data, we quantify the strike-slip efficiency of the system as the percentage of applied plate-parallel velocity accommodated as slip in the direction of plate motion along faults within the restraining bend. Bends with small θ initially have higher strike-slip efficiency compared to bends with large θ. Although they have different fault geometries, all systems with a 5 cm bend width reach a steady strike-slip efficiency of 80% after 50 mm of applied plate displacement. These experimental restraining bends resemble crustal faults in their asymmetric fault growth, asymmetric topographic gradient, and strike-slip efficiency.

  11. Impact factors and thermodynamic characteristics of aquatic humic acid loaded onto kaolin.

    PubMed

    Qinyan, Yue; Ying, Li; Baoyu, Gao

    2009-09-01

    The adsorption of humic acid (HA) on kaolin particles was studied at various conditions of initial solution pH, ionic strength and solid-to-liquid ratio. The resulting affinity of interactions between humic acid and kaolin was attributed to the surface coordination of HA in ambient suspensions of mineral particles and the strong electrostatic force at low pH. Addition of inorganic salt can also influence the adsorption behavior by affecting the HA molecular structure, the clay particle zeta potential and so on. Equilibrium data were well fitted by the Freundlich model and implied the occurrence of multilayer adsorption in the process. In addition, the enthalpy dependent of system temperature was 79.17 kJ/mol, which proved that the mechanism of HA adsorption onto kaolin was comprehensive, including electrostatic attraction, ligand complexation and hydrogen bonding.

  12. Pharmacokinetics and pharmacodynamic effects of meloxicam in piglets subjected to a kaolin inflammation model.

    PubMed

    Fosse, T K; Spadavecchia, C; Horsberg, T E; Haga, H A; Ranheim, B

    2011-08-01

    The pharmacokinetics and the analgesic, anti-inflammatory and antipyretic effects of meloxicam were investigated in a placebo controlled study in 2-week-old piglets. Inflammation was induced by a subcutaneous injection of kaolin in the left metacarpus, and 16 h later, meloxicam (0.6 mg/kg) or saline was administered intramuscularly. The absorption half-life was relatively short (0.19 h) and the elimination half-life was 2.6 h. Mechanical nociceptive threshold testing was used to evaluate the analgesic effect, but no significant effect of the meloxicam treatment was found. The skin temperature of the inflamed area increased after the kaolin injection, but no significant decrease in temperature was found after administration of meloxicam. Only limited pyresis was observed after the kaolin injection, and no significant antipyretic effect of meloxicam was found. The results indicated that this dose of meloxicam had very limited anti-inflammatory and analgesic effects in piglets.

  13. An inhibitor to rubella hemagglutination present in bovine albumin preparations: its removal by treatment with kaolin.

    PubMed

    Campbell, J B; Ellins, M L; Tasios, C

    1977-07-18

    Certain commercial preparations of bovine albumin, fraction V, show inhibitory activity in the rubella hemagglutination (HA) and hemagglutination-inhibition (HI) tests. This does not appear to be due to albumin per se, but instead to a contaminant (or contaminants) with the properties of a lipoprotein. All inhibitory activity can be removed from albumin preparations by treatment with kaolin, gel filtration, or flotation ultracentrifugation. We have found that, even when there was no inhibition of HA titers, kaolin treatment of the albumins prior to their incorporation into the test diluent resulted in more clearly defined agglutination patterns. Reasons for and against including albumin in the test diluent are discussed. It is concluded that, although not essential, it is a worthwhile additive. Our data suggest, however, that each batch of albumin used for this purpose should be checked for the presence of inhibitor, and that treatment with kaolin might be considered as a routine step prior to its incorporation into the test diluent.

  14. Influence of Illite and Kaolin on Chromium(VI) Reduction by Sulfide

    SciTech Connect

    Lan, Yeqing; Kim, Chulsung; Deng, Baolin; Thorton, Edward C.

    2004-03-29

    Use of hydrogen sulfide for reductive chromate immobilization requires us to understand how the minerals in the subsurface environment will affect the reaction. In this study, we examined the effects of illite and kaolin on the reduction of Cr(VI) by hydrogen sulfide under the anaerobic condition at pH ranging from 7.67 to 9.07. The results showed that extremely low concentration of iron dissolved from illite could greatly accelerate the rate of Cr(VI) reduction. An electron cycling process between Fe(II)/Fe(III) was believed to be responsible for the catalysis. The effect of iron could be completely blocked by phenanthroline that formed a strong complex with Fe(II). Elemental sulfur produced as a reaction product was also able to catalyze the reaction in the heterogeneous system. In the kaolin suspension, however, the effect of elemental sulfur could be completely eliminated because of the adsorption of elemental sulfur by kaolin.

  15. SO2 gas adsorption by modified kaolin clays: influence of previous heating and time acid treatments.

    PubMed

    Volzone, Cristina; Ortiga, Jose

    2011-10-01

    Modified kaolin clays were used as adsorbents for SO(2) gas adsorptions. The clays were heated up to 900 °C previous to acid treatments with 0.5 N sulfuric acid solutions at boiling temperature during different times up to 1440 min. Equilibrium adsorption at 25 °C and 0.1 MPa was carried out by using a volumetric apparatus. The samples were characterized by chemical analysis, X-ray diffraction and infrared analysis. The heating of the clays followed by acid treatment improved the adsorption capacity of the kaolin clays. The presence of amorphous silica and hydroxyl in the final products improved SO(2) adsorption capacity. Better properties for SO(2) adsorption were found in kaolin rich in not well ordered kaolinite clay mineral.

  16. The role of kaolin particles in the performance of a carbamate-based biocide for water bacterial control.

    PubMed

    Pereira, Maria Olivia; Vieira, Maria João; Melo, Luis F

    2002-01-01

    The influence of kaolin particles on the activity of Pseudomonas fluorescens and on the efficacy of a carbamate-based biocide was investigated. The results indicated that kaolin particles stimulated the activity of the bacteria for all buffered pH values studied (5, 7, and 9); this effect being more evident for the tests carried out at pH 5 and 9. The presence of the clay in P. fluorescens suspensions decreased the efficiency of disinfection of the carbamate. The results also showed that kaolin was very effective in removing carbamate from the culture media. Therefore, the biocide concentration in the solution decreased, and consequently its availability to the bacteria was reduced. The results could be explained by the interaction between kaolin particles and carbamate and by the changes in the configuration of kaolin aggregates, depending on the pH value.

  17. Correlation Between Chromophore Impurity Content and Fired Colour Data of Kaolin Clay

    NASA Astrophysics Data System (ADS)

    Agrawal, Parvesh; Misra, S. N.; Sharma, T.

    Different kaolin clay specimen exhibit varying colours after firing depending upon the relative presence of different mineral impurities, physical state of mineral constituents etc. Spectrophotometers used for determining colour values generate many sets of colour data. Interpretation of such colour values is a subjective matter. Increase in darkness, yellowness etc as a consequence of increase in chromophore impurity content in kaolin clay have been shown. However, the inverse of above ie; gradual change in colour values along with gradual change in chromophore impurity content over a realistic range has not been studied. Whether the colour data of kaolin clay after firing can be taken up as a function of impurity content needs to be investigated. Thus, to identify the correlation between kaolin clay impurity content and it's fired colour data the present investigation examined the hypotheses i) The colour development after firing of kaolin clay is an indicator of chromophore impurity content present therein and ii) All the colour variables (L, a, b, ISO2470, redness) constituting a colour data set of pressed kaolin clay specimen after firing will vary in similar manner such that to represent variation in impurity content. The study indicated that the colour values obtained by spectrophotometry of clay specimens after firing represent the chromophore impurity present therein in a less reliable manner. To relatively estimate the quantity of chromophore impurity present in a clay sample from its fired colour, the sample should be mixed with 50% by weight of potash feldspar, pressed in to tablet suitable for colour measurement and fired at or above 1220°C to vitrify. After that the ‘L’, ‘a’ and ‘ISO2470’ values obtained truly represent the chromophore present therein.

  18. Effect of bentonite on the fertility of an ordinary chernozem

    NASA Astrophysics Data System (ADS)

    Agafonov, E. V.; Khovanskii, M. V.

    2014-05-01

    The effect of bentonite clay on the main fertility parameters of an ordinary chernozem has been revealed. The maximum contents of nutrients in the soil have been obtained after the application of bentonite at rates of 7.5 t/ha for nitrate nitrogen and mobile potassium and 10.0 t/ha for available phosphorus. At the application of bentonite at rates of 10.0-15.0 t/ha, the content of agronomically valuable soil aggregates resistant to mechanical impact has increased by 2.7%, while that of water-stable aggregates has increased by 6.8%. The portion of water-stable microaggregates has increased, which has decreased the degree of dispersion. Because of the increased content of fine-silt and clay particles, the portion of physical clay in the soil has increased by 3.13%, and the portion of physical sand has decreased. The optimum application rate of bentonite (7.5 t/ha) has been found, which ensures an increase in the yield of sorghum by 16.3%. Its effect was insignificantly lower than that of mineral fertilizers.

  19. Sorption of 226Ra from waste effluents using Syrian bentonite.

    PubMed

    Al Attar, L; Al Masri, M S; Budeir, Y; Al Chayah, O

    2010-12-14

    In view of environmental concern, sorption of radium on natural bentonite mineral (Aleppo, Syria) was investigated using a batch-type method. Data were expressed in terms of distribution coefficients. An attempt to increase the selectivity of bentonite for radium was made by preparing M-derivatives. Loss of mineral crystallinity in acidic media and the formation of a new phase, such as BaCO3, in Ba-derivative were evidenced by XRD characterizations. Of the cationic forms, Na-bentonite showed the highest affinity. Mechanisms of radium uptake were studied using M-derivatives and simulated radium solutions. The obtained results indicated that surface sorption/surface ion exchange were the predominant processes. The distinct sorption behaviour observed with the Ba-form was, possibly, a reflection of radium coprecipitation with barium carbonate. The competing order of macro components, likely present in waste streams, was investigated by studying different concentrations of the corresponding salt media. Sodium was found to be the weakest inhibitor. The performance of natural bentonite and the most selective forms, i.e. Ba- and Na-derivatives, to sorb radium from actual oil co-produced waters, collected form Der Ezzor Petroleum Company (DEZPC), was studied. This showed the influential effect ofpH compared with other parameters.

  20. Magnesium incorporated bentonite clay for defluoridation of drinking water.

    PubMed

    Thakre, Dilip; Rayalu, Sadhana; Kawade, Raju; Meshram, Siddharth; Subrt, J; Labhsetwar, Nitin

    2010-08-15

    Low cost bentonite clay was chemically modified using magnesium chloride in order to enhance its fluoride removal capacity. The magnesium incorporated bentonite (MB) was characterized by using XRD and SEM techniques. Batch adsorption experiments were conducted to study and optimize various operational parameters such as adsorbent dose, contact time, pH, effect of co-ions and initial fluoride concentration. It was observed that the MB works effectively over wide range of pH and showed a maximum fluoride removal capacity of 2.26 mgg(-1) at an initial fluoride concentration of 5 mg L(-1), which is much better than the unmodified bentonite. The experimental data fitted well into Langmuir adsorption isotherm and follows pseudo-first-order kinetics. Thermodynamic study suggests that fluoride adsorption on MB is reasonably spontaneous and an endothermic process. MB showed significantly high fluoride removal in synthetic water as compared to field water. Desorption study of MB suggest that almost all the loaded fluoride was desorbed ( approximately 97%) using 1M NaOH solution however maximum fluoride removal decreases from 95.47 to 73 (%) after regeneration. From the experimental results, it may be inferred that chemical modification enhances the fluoride removal efficiency of bentonite and it works as an effective adsorbent for defluoridation of water.

  1. Sodium Bentonite-Based Fire Retardant Coatings Containing Starch

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sodium bentonite (SB) gel and foam coatings were tested for their ability to suppress the rate of heat increase at the surface of commercial lap siding. Starch was added to some treatments to determine whether it stabilized the coating and prevented vertical slumping. A commercial fire protection ge...

  2. Pisolitic flint kaolin from Kalabsha, Egypt: A laterite-derived facies

    NASA Astrophysics Data System (ADS)

    Baioumy, Hassan; Gilg, H. Albert

    2011-05-01

    Nodular, pisolitic, and plastic kaolins from Kalabsha area, Egypt were investigated for their textural, mineralogical, and geochemical compositions to examine their source and origin. The three kaolins are composed of kaolinite, quartz, anatase, and traces of hematite and rutile. Clay fractions have relatively high Nb (56-189 ppm) and Zr (480-1260 ppm) contents. Heavy minerals from the sand fractions are composed of zircon, high Cr rutile, and leucoxene. Detrital quartz occurs as either monocrystalline or polycrystalline grains with worm-like corrosion features. Two types of quartz were distinguished based on their cathodoluminescence (CL) analysis; bright and dark luminescence quartz. Rare earth elements (REEs) patterns show enrichment of light REEs relative to heavy REEs ((La/Yb) N = 1.6-10) and negative Eu anomaly (Eu*/Eu = 0.6-0.7). Nodular and pisolitic kaolins show distinct positive Ce anomaly (Ce*/Ce = 1.2-3.4) and a variable LREE depletion. The pisolitic kaolin is considered here as flint kaolin based on its unique characteristics such as hardness, massiveness, conchoidal fracture, high density, very fine-grained nature, resistance to slacking in water, high crystallinity, and homogeneous compositions. Abundance of high Cr rutile, polycrystalline, and dark luminescent quartz suggest a contribution of medium to high grade metamorphic mafic rocks to the source of Kalabsha kaolins, while presence of zircon, bright luminescence monocrystalline quartz, and REEs pattern indicate a contribution of granitic rocks. The unusual high Nb contents attest to a contribution of alkaline rocks in the source area of the deposits. Lithostratigraphic succession, pisolitic texture, corroded quartz, depletion of many trace elements including LREE, distinct positive Ce anomaly, unusual grain size distribution, and compositional homogeneity suggest a lateritic precursor of the pisolitic flint kaolin. The lateritic precursor sediments have been deferrated and resilicified in the

  3. Alteration of bentonite when contacted with supercritical CO2

    NASA Astrophysics Data System (ADS)

    Jinseok, K.; Jo, H. Y.; Yun, S. T.

    2014-12-01

    Deep saline formations overlaid by impermeable caprocks with a high sealing capacity are attractive CO2 storage reservoirs. Shales, which consist of mainly clay minerals, are potential caprocks for the CO2 storage reservoirs. The properties of clay minerals in shales may affect the sealing capacity of shales. In this study, changes in clay minerals' properties when contacted with supercritical (SC) CO2 at various conditions were investigated. Bentonite, whichis composed of primarily montmorillonite, was used as the clay material in this study. Batch reactor tests on wet bentonite samples in the presence of SC CO2 with or without aqueous phases were conducted at high pressure (12 MPa) and moderate temperature (50 oC) conditions for a week. Results show that the bentonite samples obtained from the tests with SC CO2 had less change in porosity than those obtained from the tests without SC CO2 (vacuum-drying) at a given reaction time, indicating that the bentonite samples dried in the presence of SC CO2 maintained their structure. These results suggest that CO2 molecules can diffuse into interlayer of montmorillonite, which is a primary mineral of bentonite, and form a single CO2 molecule layer or double CO2 molecule layers. The CO2 molecules can displace water molecules in the interlayer, resulting in maintaining the interlayer spacing when dehydration occurs. Noticeable changes in reacted bentonite samples obtained from the tests with an aqueous phase (NaCl, CaCl2, or sea water) are decreases in the fraction of plagioclase and pyrite and formation of carbonate minerals (i.e., calcite and dolomite) and halite. In addition, no significant exchanges of Na or Ca on the exchangeable complex of the montmorillonite in the presence of SC CO2 occurred, resulting in no significant changes in the swelling capacity of bentonite samples after reacting with SC CO2 in the presence of aqueous phases. These results might be attributed by the CO2 molecule layer, which prevents

  4. Effects of the injection grout Silica sol on bentonite

    NASA Astrophysics Data System (ADS)

    Holmboe, Michael; Wold, Susanna; Petterson, Torbjörn

    Silica sol, i.e., colloidal SiO 2, may be used as a low-pH injection grout for very fine fractures in the construction of deep geological repositories for radioactive waste in Sweden and in Finland. If the bentonite barrier encounters SiO 2-colloid particles under conditions favorable for aggregation, there is concern that it will modify the bentonite barrier at the bentonite/bedrock interface. In this study qualitative experiments were performed with mixed dispersions of SiO 2-colloids and bentonite or homo-ionic Na/Ca-montmorillonite. Samples were prepared at different colloid concentrations and treated under various conditions such as low and high ionic strength (0.3 M NaCl), as well as dehydration and redispersing. Free swelling and settling experiments were performed in order to qualitatively compare the conditions in which SiO 2-colloids affect the bulk/macro properties of bentonite. In order to study specific SiO 2-colloid/montmorillonite interactions and preferred type of initial aggregation, dilute dispersions of homo-ionic montmorillonite dispersions mixed with varying concentrations of SiO 2-colloids were prepared and selected samples were characterized by PCS, SEM/EDS, AFM and PXRD. The results from this study show that bentonite and montmorillonite particles can be modified by SiO 2-colloids when mixed in comparable amounts, due to dehydration or high ionic strength. Some indications for increased colloidal stability for the SiO 2-colloid modified clay particles were also found. From the AFM investigation it was found that initial attachment of the SiO 2-colloids in Na + dominated samples seemed to occur on the edges of the montmorillonite layers. In Ca 2+ dominated samples not subjected to excess NaCl, SiO 2-colloid sorption onto the faces of the montmorillonite layers was also found. In all, contact between the bentonite barrier and ungelled Silica sol should preferably be avoided.

  5. Activation of a Ca-bentonite as buffer material

    NASA Astrophysics Data System (ADS)

    Huang, Wei-Hsing; Chen, Wen-Chuan

    2016-04-01

    Swelling behavior is an important criterion in achieving the low-permeability sealing function of buffer material. A potential buffer material may be used for radioactive waste repository in Taiwan is a locally available clayey material known as Zhisin clay, which has been identified as a Ca-bentonite. Due to its Ca-based origin, Zhisin was found to exhibit swelling capacity much lower than that of Na-bentonite. To enhance the swelling potential of Zhisin clay, a cation exchange process by addition of Na2CO3 powder was introduced in this paper. The addition of Na2CO3 reagent to Zhisin clay, in a liquid phase, caused the precipitation of CaCO3 and thereby induced a replacement of Ca2+ ions by Na+ ions on the surface of bentonite. Characterization test conducted on Zhisin clay includes chemical analysis, cation exchange capacity, X-ray diffraction, and thermogravimetry (TG). Free-swelling test apparatus was developed according to International Society of Rock Mechanics recommendations. A series of free-swelling tests were conducted on untreated and activated specimens to characterize the effect of activation on the swelling capacity of Zhisin clay. Efforts were made to determine an optimum dosage for the activation, and to evaluate the aging effect. Also, the activated material was evaluated for its stability in various hydrothermal conditions for potential applications as buffer material in a repository. Experimental results show that Na2CO3-activated Zhisin clay is superior in swelling potential to untreated Zhisin clay. Also, there exists an optimum amount of activator in terms of improvements in the swelling capacity. A distinct time-swell relationship was discovered for activated Zhisin clay. The corresponding mechanism refers to exchange of cations and breakdown of quasi-crystal, which results in ion exchange hysteresis of Ca-bentonite. Due to the ion exchange hysteresis, activated bentonite shows a post-rise time-swell relationship different than the sigmoid

  6. Sequential use of bentonites and solar photocatalysis to treat winery wastewater.

    PubMed

    Rodríguez, Eva; Márquez, Gracia; Carpintero, Juan Carlos; Beltrán, Fernando J; Alvarez, Pedro

    2008-12-24

    The sequential use of low-cost adsorbent bentonites and solar photocatalysis to treat winery wastewater has been studied. Three commercial sodium-bentonites (MB-M, MB-G, and MB-P) and one calcium-bentonite (Bengel) were characterized and used in this study. These clay materials were useful to totally remove turbidity (90-100%) and, to a lesser extent, color, polyphenols (PPh), and soluble chemical oxygen demand (CODS) from winery wastewater. Both surface area and cation exchange capacity (CEC) of bentonite had a positive impact on treatment efficiency. The effect of pH on turbidity removal by bentonites was studied in the 3.5-12 pH range. The bentonites were capable of greatly removing turbidity from winery wastewater at pH 3.5-5.5, but removal efficiency decreased with pH increase beyond this range. Settling characteristics (i.e., sludge volume index (SVI) and settling rate) of bentonites were also studied. Best settling properties were observed for bentonite doses around 0.5 g/L. The reuse of bentonite for winery wastewater treatment was found not to be advisable as the turbidity and PPh removal efficiencies decreased with successive uses. The resulting wastewater after bentonite treatment was exposed to solar radiation at oxic conditions in the presence of Fe(III) and Fe(III)/H2O2 catalysts. Significant reductions of COD, total organic carbon (TOC), and PPh were achieved by these solar photocatalytic processes.

  7. Surfactant-modified bentonite clays: preparation, characterization, and atrazine removal.

    PubMed

    Dutta, Anirban; Singh, Neera

    2015-03-01

    Bentonite clay was modified using quaternary ammonium cations, viz. phenyltrimethylammonium (PTMA), hexadecyltrimethylammonium (HDTMA), trioctylmethylammonium (TOMA) [100 % of cation exchange capacity of clay], and stearylkonium (SK) [100 % (SK-I) and 250 % (SK-II) of cation exchange capacity of clay]. The organoclays were characterized using X-ray diffraction (XRD), infrared (IR) spectroscopy, and scanning electron microscopy (SEM). Atrazine adsorption on modified clays was studied using a batch method. Bentonite clay was a poor adsorbent of atrazine as 9.4 % adsorption was observed at 1 μg mL(-1) atrazine concentration. Modification of clay by PTMA cation did not improve atrazine adsorption capacity. However, atrazine adsorption in HDTMA-, TOMA-, and SK-bentonites varied between 49 and 72.4 % and data fitted well to the Freundlich adsorption isotherm (R > 0.96). Adsorption of atrazine in organoclays was nonlinear and slope (1/n) values were <1. The product of Freundlich adsorption constants, K f(1/n) in HDTMA-, TOMA-, and SK-I-bentonites was 239.2, 302.4, and 256.6, respectively, while increasing the SK cation loading in the clay (SK-II) decreased atrazine adsorption [K f(1/n) - 196.4]. Desorption of atrazine from organoclays showed hysteresis and TOMA- and SK-I-bentonites were the best organoclays to retain the adsorbed atrazine. Organoclays showed better atrazine removal from wastewater than an aqueous solution. The synthesized organoclays may find application in soil and water decontamination and as a carrier for atrazine-controlled released formulations.

  8. Pre- and post-shunting observations in adult sheep with kaolin-induced hydrocephalus

    PubMed Central

    2013-01-01

    Background The objective of this study was to examine host-shunt interactions in sheep with kaolin-induced hydrocephalus. Methods Forty-two sheep (29–40 kg) were utilized for this study. In 20 animals, various kaolin doses were injected into the cisterna magna including 10 and 50 mg/kg as well as 2–4 ml of a 25% kaolin suspension. Based on animal health and hydrocephalus development, 3 ml of a 25% kaolin suspension was chosen. In 16 animals, kaolin was administered and 6–8 days later, the animals received a custom made ventriculo-peritoneal shunt. In 8 animals ventricular CSF pressures were measured with a water manometer before kaolin administration and 7–8 days later. The sheep were allowed to survive for up to 9–12 weeks post-kaolin or until clinical status required euthanasia. Brains were assessed for morphological and histological changes. Ventricle/cerebrum cross sectional area ratios (V/C) were calculated from photographs of the sliced coronal planes immediately anterior to the interventricular foramina. Results Intraventricular pressures increased from 12.4±1.1 cm H2O to 41.3±3.5 cm H2O following kaolin injection (p < 0.0001, n = 8). In all animals, we observed kaolin on the basal surface of the brain and mild (V/C 0.03-0.10) to moderate (V/C >0.10) ventricular expansion. The animals lost weight between kaolin administration and shunting (33.7±1.2 kg versus 31.0±1.7 kg) with weights after shunting remaining stable up to sacrifice (31.6±2.2 kg). Of 16 shunted animals, 5 did well and were sacrificed 9–12 weeks post-kaolin. In the remainder, the study was terminated at various times due to deteriorating health. Hydrocephalus was associated with thinning of the corpus callosum, but no obvious loss of myelin staining, along with reactive astroglial (glial fibrillary acidic immunoreactive) and microglial (Iba1 immunoreactive) changes in the white matter. Ventricular shunts revealed choroid plexus ingrowth in 5/16, brain

  9. Coupled thermo-hydro-chemical models of swelling bentonites

    NASA Astrophysics Data System (ADS)

    Samper, Javier; Mon, Alba; Zheng, Liange; Montenegro, Luis; Naves, Acacia; Pisani, Bruno

    2014-05-01

    The disposal of radioactive waste in deep geological repositories is based on the multibarrier concept of retention of the waste by a combination of engineered and geological barriers. The engineered barrier system (EBS) includes the solid conditioned waste-form, the waste container, the buffer made of materials such as clay, grout or crushed rock that separate the waste package from the host rock and the tunnel linings and supports. The geological barrier supports the engineered system and provides stability over the long term during which time radioactive decay reduces the levels of radioactivity. The strong interplays among thermal (T), hydrodynamic (H), mechanical (M) and chemical (C) processes during the hydration, thermal and solute transport stages of the engineered barrier system (EBS) of a radioactive waste repository call for coupled THMC models for the metallic overpack, the unsaturated compacted bentonite and the concrete liner. Conceptual and numerical coupled THMC models of the EBS have been developed, which have been implemented in INVERSE-FADES-CORE. Chemical reactions are coupled to the hydrodynamic processes through chemical osmosis (C-H coupling) while bentonite swelling affects solute transport via changes in bentonite porosity changes (M-H coupling). Here we present THMC models of heating and hydration laboratory experiments performed by CIEMAT (Madrid, Spain) on compacted FEBEX bentonite and numerical models for the long-term evolution of the EBS for 1 Ma. The changes in porosity caused by swelling are more important than those produced by the chemical reactions during the early evolution of the EBS (t < 100 years). For longer times, however, the changes in porosity induced by the dissolution/precipitation reactions are more relevant due to: 1) The effect of iron mineral phases (corrosion products) released by the corrosion of the carbon steel canister; and 2) The hyper alkaline plume produced by the concrete liner. Numerical results show that

  10. Kaolin-based foliar reflectant alleviates heat stress in deficit-irrigated Malbec

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We evaluated the interaction effects of a kaolin-based particle film and water deficit on leaf and berry surface temperature, light reflectance, gas exchange characteristics, berry composition and yield of Malbec vines under field conditions over three growing seasons to test the hypothesis that the...

  11. Characterization of juvenile and young adult mice following induction of hydrocephalus with kaolin.

    PubMed

    Lopes, Luiza da Silva; Slobodian, Ili; Del Bigio, Marc R

    2009-09-01

    Hydrocephalus is a common neurological problem in humans, usually caused by an impairment of cerebrospinal fluid (CSF) flow or absorption. A reliable induced model of chronic hydrocephalus in mice would be useful to test hypotheses using genetic mutants. Our goal was to characterize behavioral and histological changes in juvenile and young adult mice with kaolin (aluminum silicate)-induced hydrocephalus. Seven-day old and 7-8 week old mice received injection of kaolin into the cisterna magna. Behavior was assessed repeatedly. Seven or 14 days following kaolin, magnetic resonance (MR) imaging was used to assess ventricle size. In hydrocephalic mice, body weight was significantly lower than in age-matched saline-injected sham controls and the gait and posture score were impaired. Juvenile mice developed severe ventriculomegaly and had reduced corpus callosum thickness with gross white matter destruction by 14 days. Reactive astroglial change in white matter and cortex and reduced cellular proliferation in the subependymal zone were also apparent. Young adult mice developed only moderate ventricular enlargement without overt white matter destruction, although there was corpus callosum atrophy and mild astroglial reaction in white matter. Glial fibrillary acidic protein content was significantly higher in juvenile and young adult hydrocephalic mice at 7 and 14 days, but myelin basic protein content was not significantly altered. In conclusion, hydrocephalus induced by percutaneous injection of kaolin in juvenile and young adult mice is feasible. The associated periventricular alterations are essentially the same as those reported in rats of comparable ages.

  12. Wine Grape Response to Foliar Kaolin Particle Film under Differential Deficit Irrigation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Deficit irrigation improves grape quality for wine production. However, under arid production regions with high solar radiation, water stress may render the vine more susceptible to solar injury and inhibit fruit ripening. This is the first year of a multiyear study to examine the impact of kaolin...

  13. Properties and characterization of porous material prepared by hydrothermal treatment of kaolin

    SciTech Connect

    Malla, P.B.; Arrington-Webb, L.A.

    1994-12-31

    A kaolin was hydrothermally treated with various amounts of NAOH and KOH at 150 C for 15 min to chemically aggregate the kaolin plates in a structured configuration. X-ray powder diffraction analysis indicated that kaolin was the only crystalline phase present. Chemical analyses showed that about 0.25--1.1% Na{sub 2}O and 1.2--5.0% K{sub 2}O were trapped in the solid phase depending on the reaction conditions. Mercury porosimetry indicated a highly porous nature with pore volumes of 0.3--1.4 ml/g and median pore sizes of 0.06--0.3 {mu}m. Scanning electron micrographs showed that the aggregation was achieved by surface modification and random association (edge to edge and face to edge, face to face) of the particles. Measurement of light scattering coefficient of the coating showed an increase of {approximately}350% in scattering compared to that of the precursor kaolin. These materials are useful in imparting highly pacifying properties to paper and paint. They are also potentially useful as catalysts, catalyst supports, and in other applications which demand a high light scattering ability and macroporous nature.

  14. Geology and industrial mineral resources of the Macon-Gordon Kaolin District, Georgia

    USGS Publications Warehouse

    Buie, Bennett Frank; Hetrick, J.H.; Patterson, S.H.; Neeley, C.L.

    1979-01-01

    The Macon-Gordon kaolin district is about 80 miles (130 km) southeast of Atlanta, Georgia. It extends across the boundary between, and includes parts of, the Piedmont and Atlantic Coastal Plain physiographic provinces. The rocks in the Piedmont are mainly intensely folded sericite schist and granite gneiss containing irregular masses of amphibolite and feldspathic biotite gneiss and scattered igneous intrusive rocks. Most of the crystalline rocks are thought to be of Paleozoic age, but some of the intrusive rocks may be younger. The crystalline rocks are cut by a major unconformity and are overlain by sedimentary formations ranging in age from Cretaceous to Miocene. The valuable kaolin deposits occur in the Cretaceous beds, undivided, and in the Huber Formation which is of Paleocene to middle Eocene age. The resources of kaolin in the district are estimated in millions of metric tons as follows: reserves, 100; subeconomic resources, 700 to 900; undiscovered resources, probably 700 to 1,000. In addition to kaolin, the leading mineral commodity mined in the district, crushed stone and sand are now being produced, and fuller's earth and a minor amount of limestone were formerly produced. The crushed stone is quarried from igneous rocks in the Piedmont province. The sand is washed from the Cretaceous beds, undivided. The fuller's earth was mined from the Twiggs Clay Member of the Barnwell Formation, and limestone was dug from the Tivola Limestone.

  15. Potential of Kaolin-based Particle Film Barriers for Formosan Subterranean Termite (Isoptera: Rhinotermitidae) Control

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Effects of three particle film products on Formosan subterranean termites, Coptotermes formosanus Shiraki, were evaluated in feeding, tunneling, and contact assays. The particle films, hydrophobic M96-018 and hydrophilic Surround and Surround WP are based on the inert clay mineral kaolin. In 2-week ...

  16. 40 CFR 180.1180 - Kaolin; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Kaolin; exemption from the requirement of a tolerance. 180.1180 Section 180.1180 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... permit the marketing of the food commodities in this paragraph when treated in accordance with...

  17. Properties and Microstructural Characteristic of Kaolin Geopolymer Ceramics with Addition of Ultra High Molecular Weight Polyethylene

    NASA Astrophysics Data System (ADS)

    Ahmad, Romisuhani; Bakri Abdullah, Mohd Mustafa Al; Hussin, Kamarudin; Sandu, Andrei Victor; Binhussain, Mohammed; Ain Jaya, Nur

    2016-06-01

    In this paper, the mechanical properties and microstructure of kaolin geopolymer ceramics with addition of Ultra High Molecular Weight Polyethylene were studied. Inorganic polymers based on alumina and silica polysialate units were synthesized at room temperature from kaolin and sodium silicate in a highly alkaline medium, followed by curing and drying at 80 °C. Alkaline activator was formed by mixing the 12 M NaOH solution with sodium silicate at a ratio of 0.24. Addition of Ultra High Molecular Weight Polyethylene to the kaolin geopolymer are fabricated with Ultra High Molecular Weight Polyethylene content of 2, 4, 6 and 8 (wt. %) by using powder metallurgy method. The samples were heated at 1200 °C and the strength and morphological were tested. It was found that the flexural strength for the kaolin geopolymer ceramics with addition of UHMWPE were improved and generally increased with the increasing of UHMWPE loading. The result revealed that the optimum flexural strength was obtained at UHMWPE loading of 4 wt. % (92.1 MPa) and the flexural strength started to decrease. Microstructural analysis showed the samples appeared to have more number of pores and connected of pores increased with the increasing of UHMWPE content.

  18. The use of bentonite to remove dark colour in repeatingly used palm oil.

    PubMed

    Meesuk, Ladda; Vorasith, Niramon

    2006-01-01

    Acid-activated bentonite was used as a bleaching agent to remove the dark color in repeatingly used palm oil. Two bentonite samples with different colors were used. It was found that the paler one gave better bleaching results. The optimum condition needed 5 h to reflux bentonite with sulfuric acid; pH of the bentonite suspension was 3, bleaching temperature was 80-85 degrees C and bleaching time was 30 min. The experiments also showed that bentonite could adsorb impurities and toxic compounds such as benzo(a)pyrene in palm oil. Chemical and physical properties of the bentonite samples were analyzed by X-ray fluorescence spectrometer (XRF), X-ray diffraction spectrometer (XRD) and scanning electron microscope (SEM). Particle size and specific surface area were also studied.

  19. Influence of Bentonite Particles on the Transport and Deposition Behavior of Bacteria in Porous Media

    NASA Astrophysics Data System (ADS)

    Yang, Haiyan; Tong, Meiping; Kim, Hyunjung

    2013-04-01

    The influence of clay particles on the transport and deposition behavior of bacteria in irregular quartz sand was examined by direct comparison of both breakthrough curves and retained profiles with clay particles in bacteria suspension versus those without clay particles. Two representative cell types, Gram-negative strain E.coli DH5α and Gram-positive strain Bacillus subtilis were utilized to systematically determine the influence of clay particles (bentonite) on cell transport behavior. Packed column experiments for both cell types were conducted in both NaCl (5 and 25 mM ionic strengths) and CaCl2 (5 mM ionic strength) solutions at pH 6.0. The breakthrough plateaus with bentonite in solutions (30 mg L-1 and 50 mg L-1) were lower than those without bentonite for both cell types under all examined conditions, indicating that bentonite in solutions decreased cell transport in porous media regardless of cell types (Gram-negative or Gram-positive) and solution chemistry (ionic strength and ion valence). The enhanced cell deposition with bentonite particles was mainly observed at segments near to column inlet, retained profiles for both cell types with bentonite particles therefore were steeper relative to those without bentonite. The increased cell deposition with bentonite observed in NaCl solutions was mainly attributed to the co-deposition of bacteria with bentonite particles whereas, in addition to co-deposition of bacteria with bentonite, the bacteria-bentonite-bacteria cluster formed in suspensions also contributed to the increased deposition of bacteria with bentonite in CaCl2 solution.

  20. Evidence of ammonium ion-exchange properties of natural bentonite and application to ammonium detection.

    PubMed

    Zazoua, A; Kazane, I; Khedimallah, N; Dernane, C; Errachid, A; Jaffrezic-Renault, N

    2013-12-01

    Ammonium exchange with hybrid PVC-bentonite (mineral montmorillonite clay) thin film was revealed using FTIR spectroscopy, EDX, cyclic voltammetry and electrochemical impedance spectroscopy. The effect of ammonium exchange on the charge transfer resistance of PVC-bentonite hybrid thin film was attributed to a modification of the intersheet distance and hydration of bentonite crystals. The obtained impedimetric ammonium sensor shows a linear range of detection from 10(-4)M to 1M and a detection limit around 10(-6)M.

  1. Influence of bentonite particles on representative gram negative and gram positive bacterial deposition in porous media.

    PubMed

    Yang, Haiyan; Tong, Meiping; Kim, Hyunjung

    2012-11-06

    The significance of clay particles on the transport and deposition kinetics of bacteria in irregular quartz sand was examined by direct comparison of both breakthrough curves and retained profiles with clay particles in bacteria suspension versus those without clay particles. Two representative cell types, Gram-negative strain E. coli DH5α and Gram-positive strain Bacillus subtilis were utilized to systematically determine the influence of clay particles (bentonite) on cell transport behavior. Packed column experiments for both cell types were conducted in both NaCl (5 and 25 mM ionic strengths) and CaCl(2) (5 mM ionic strength) solutions at pH 6.0. The breakthrough plateaus with bentonite in solutions (30 mg L(-1) and 50 mg L(-1)) were lower than those without bentonite for both cell types under all examined conditions, indicating that bentonite in solutions decreased cell transport in porous media regardless of cell types (Gram-negative or Gram-positive) and solution chemistry (ionic strength and ion valence). The enhanced cell deposition with bentonite particles was mainly observed at segments near to column inlet, retained profiles for both cell types with bentonite particles were therefore steeper relative to those without bentonite. The increased cell deposition with bentonite observed in NaCl solutions was attributed to the codeposition of bacteria with bentonite particles whereas, in addition to codeposition of bacteria with bentonite, the bacteria-bentonite-bacteria cluster formed in suspensions also contributed to the increased deposition of bacteria with bentonite in CaCl(2) solution.

  2. Impaired lymphatic cerebrospinal fluid absorption in a rat model of kaolin-induced communicating hydrocephalus.

    PubMed

    Nagra, G; Li, J; McAllister, J P; Miller, J; Wagshul, M; Johnston, M

    2008-05-01

    It has been assumed that the pathogenesis of hydrocephalus includes a cerebrospinal fluid (CSF) absorption deficit. Because a significant portion of CSF absorption occurs into extracranial lymphatics located in the olfactory turbinates, the purpose of this study was to determine whether CSF transport was compromised at this location in a kaolin-induced communicating (extraventricular) hydrocephalus model in rats. Under 1-3% halothane anesthesia, kaolin (n = 10) or saline (n = 9) was introduced into the basal cisterns of Sprague-Dawley rats, and the development of hydrocephalus was assessed 1 wk later using MRI. After injection of human serum albumin ((125)I-HSA) into a lateral ventricle, the tracer enrichment in the olfactory turbinates 30 min postinjection provided an estimate of CSF transport through the cribriform plate into nasal lymphatics. Lateral ventricular volumes in the kaolin group (0.073 +/- 0.014 ml) were significantly greater than those in the saline-injected animals (0.016 +/- 0.001 ml; P = 0.0014). The CSF tracer enrichment in the olfactory turbinates (expressed as percent injected/g tissue) in the kaolin rats averaged 0.99 +/- 0.39 and was significantly lower than that measured in the saline controls (5.86 +/- 0.32; P < 0.00001). The largest degree of ventriculomegaly was associated with the lowest levels of lymphatic CSF uptake with lateral ventricular expansion occurring only when almost all of the lymphatic CSF transport capacity had been compromised. We conclude that lymphatic CSF absorption is impaired in a kaolin-communicating hydrocephalus model and that the degree of this impediment may contribute to the severity of the induced disease.

  3. The rare earth element potential of kaolin deposits in the Bohemian Massif (Czech Republic, Austria)

    NASA Astrophysics Data System (ADS)

    Höhn, S.; Frimmel, H. E.; Pašava, J.

    2014-12-01

    Four kaolin deposits in the Bohemian Massif were studied in order to assess the potential for the recovery of rare earth elements (REE) as by-products from the residue after extraction and refining of the raw kaolin. The behaviour of REE + Y during kaolinitization was found to be largely a function of pre-alteration mineralogy. In the examples studied, i.e. granite-derived deposits of Kriechbaum (Austria) and Božičany, and arkose-derived deposits of Kaznějov and Podbořany (all Czech Republic), the REE + Y are predominantly hosted by monazite which has remained unaffected by kaolinitization. The overall REE + Y content of the variably kaolinitized rocks is strongly dependent on their genesis. While ion adsorption plays only a minor role in the concentration of REE + Y in the studied kaolinitized rocks, the processing and refining of the raw kaolin leads to residues that are enriched in REE + Y by a factor of up to 40. The use of a magnetic separator and a hydrocyclone in the processing of the raw material can yield REE + Y contents of as much as 0.77 wt%. Although this value compares well with the REE + Y concentration in some potentially economic REE + Y projects elsewhere, the overall tonnage of the (REE + Y)-enriched residue is by far not sufficient to consider economic extraction of REE + Y as by-product. Our results are most probably applicable also to other kaolin deposits derived from the weathering of Hercynian basement granites elsewhere (e.g. in Saxonia and Bavaria, Germany). Overall, the potential for REE + Y production as by-product from kaolin mining has to be regarded as minimal.

  4. Spectral characteristics of the bentonite loaded with benzyldimethyloctadecylammonium chloride, hexadecyltrimethylammonium bromide and dimethyldioctadecylammonium bromide

    NASA Astrophysics Data System (ADS)

    Majdan, Marek; Maryuk, Oksana; Gładysz-Płaska, Agnieszka; Pikus, Stanisław; Kwiatkowski, Ryszard

    2008-02-01

    The spectral characterization, including the FTIR, DRIFT (diffusive reflectance), SWAXS (small and wide angle X-ray scattering) spectra comparison of the sodium bentonite modified by BDMODA-Cl (benzyldimethyloctadecylammonium chloride), HDTMA-Br (hexadecyltrimethylammonium bromide), DDA-Br (dimethyldioctadecylammonium bromide) is presented in the paper. The FTIR spectra show the shift of C-H stretching vibrations: νsym(CH2), νasym(CH2) of surfactants methylene chains toward lower frequencies (from 2855 to 2851 cm -1 for νsym(CH2) and from 2927 to 2918 cm -1 for νansym(CH2) with the surfactant concentration in bentonite phase. The bending vibrations δH-O-H in water molecules change their positions in the direction of higher frequencies (from 1634 to 1647 cm -1) with the surfactant concentration for bentonite-BDMODA and bentonite-DDA contrary to bentonite-HDTMA, where the constant position δH-O-H is explained as the consequence of the lower concentration of the hydrogen bonded water in bentonite-HDTMA phase when compared with the remaining forms of bentonite. The DRIFT spectra reveal dramatic shift of the νSi-O stretching vibration toward higher frequencies upon intercalation of the sodium bentonite with the surfactant cations. The SWAXS spectra and SEM images of the bentonite are the evidence of somewhat different sorption mechanism of DDA-Br when compared with the BDMODA-Cl and HDTMA-Br, including remarkable external surface sorption contribution in the overall sorption.

  5. Water migration through compacted bentonite backfills for containment of high-level nuclear waste

    SciTech Connect

    Westsik, J.H.; Hodges, F.N.; Kuhn, W.L.; Myers, T.R.

    1983-01-01

    Tests carried out with compacted sodium and calcium bentonites at room temperature indicate that bentonite backfills will effectively control water movement near a high-level nuclear waste package. Saturation tests indicate that water will rapidly diffuse into a dry bentonite backfill, reaching saturation in times on the order of tens of years. The apparent diffusion coefficient for sodium bentonite (about5 wt% initial water content) compacted to 2.1 g/cm/sup 3/ is 1.7 x 10/sup -6/ cm/sup 2//sec. However, the hydraulic conductivities of saturated bentonites are low, ranging from approximately 10/sup -11/ cm/sec to 10/sup -13/ cm/sec over a density range of 1.5 g/cm/sup 3/ to 2.2 g/cm/sup 3/. The hydraulic conductivities of compacted bentonites are at least several orders of magnitude lower than those of candidate-host silicate rocks, indicating that most flowing groundwater contacting a bentonite backfill would be diverted around the backfill rather than flowing through it. In addition, because of the very low hydraulic conductivities of bentonite backfills, the rate of chemical transport between the containerized waste and the surrounding host rock will be effectively controlled by diffusion through the backfill. The formation of a diffusion barrier by the backfill will significantly reduce the long-term rate of radionuclide release from the waste package, an advantage distinct from the delay in release resulting from the sorptive properties of a bentonite backfill.

  6. Characterization of organo-modified bentonite sorbents: The effect of modification conditions on adsorption performance

    NASA Astrophysics Data System (ADS)

    Parolo, María E.; Pettinari, Gisela R.; Musso, Telma B.; Sánchez-Izquierdo, María P.; Fernández, Laura G.

    2014-11-01

    The organic modification of a natural bentonite was evaluated using two methods: exchanging the interlayer cations by hexadecyltrimethylammonium (HDTMA) and grafting with vinyltrimethoxysilane (VTMS) and γ-methacryloyloxy propyl trimethoxysilane (TMSPMA) on montmorillonite surface. The physicochemical characterization of all materials was made by X-ray diffraction (XRD), IR spectroscopy, thermogravimetric analysis (TGA) and Brunauer-Emmett-Teller (BET) surface area techniques. HDTMA cations and organosilanes were intercalated into the interlayer space of montmorillonite, as deduced from the increase of the basal spacing. IR spectroscopy, TGA and BET area give evidence of successful organic modification. The studies show a decrease in the IR absorption band intensity at 3465 cm-1 with surfactant modification, and also a decrease of mass loss due to adsorbed water observed in two samples: the organoclay and functionalized bentonites, which are evidences of a lower interlayer hydrophilicity. The efficiency of aniline removal onto natural bentonite, organobentonite and functionalized bentonites from aqueous solutions was evaluated. Aniline sorption on natural bentonite was studied using batch experiments, XRD and IR spectroscopy. The hydrophobic surface of organobentonite and functionalized bentonites increased the retention capacity for nonionic organic substances such as aniline on bentonites. The sorption properties of modified bentonite, through different modification methods, enhanced the potential industrial applications of bentonites in water decontamination.

  7. Diffusion of water in bentonite clay: Neutron scattering study

    NASA Astrophysics Data System (ADS)

    Sharma, V. K.; Prabhudesai, S. A.; Dessai, R. Raut; Erwin Desa, J. A.; Mitra, S.; Mukhopadhyay, R.

    2013-02-01

    Diffusion of water confined in natural bentonite clay is studied using the quasi-elastic neutron scattering (QENS) technique. X-ray diffraction shows a well-defined crystalline structure of the clay with an interlayer spacing of 13 Å. The QENS experiment has been carried out on hydrated as well as dehydrated clay at 300 K. Significant quasi-elastic broadening was observed in case of hydrated bentonite clay whereas dehydrated clay did not show any broadening over the instrument resolution. Analysis of QENS data reveals that diffusion of water occurs through jump diffusion characterized by random distribution of jump lengths. Diffusion of water in clay is found to be hindered vis a vis bulk water.

  8. HMSPP nanocomposite and Brazilian bentonite properties after gamma radiation exposure

    NASA Astrophysics Data System (ADS)

    Fermino, D. M.; Parra, D. F.; Oliani, W. L.; Lugao, A. B.; Díaz, F. R. V.

    2013-03-01

    This work concerns the study of the mechanical and thermal behavior of the nanocomposite high melt strength polypropylene (HMSPP) (obtained at a dose of 12.5 kGy) and a bentonite clay Brazilian Paraiba (PB), which is known as "chocolate" and is used in concentrations of 5% and 10% by weight, in comparison to the American Cloisite 20A clay nanocomposites. An agent compatibilizer polypropylene-graft (PP-g-AM) was added at a 3% concentration, and the clay was dispersed using the melt intercalation technique using a twin-screw extruder. The specimens were prepared by the injection process. The mechanical behavior was evaluated by strength, flexural strength and impact tests. The thermal behavior was evaluated by the techniques of differential scanning calorimetry (DSC) and thermogravimetry (TGA). The morphology of the nanocomposites was studied with scanning electron microscopy (SEM), while the organophilic bentonite and nanocomposites were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR).

  9. Hydraulic conductivity of landfill liners containing benzyltriethylammonium-bentonite

    USGS Publications Warehouse

    Smith, James A.; Franklin, Pamela M.; Jaffe, Peter R.

    1992-01-01

    Varying weight percentages of an Ottawa sand, benzyltriethylammonium-bentonite (BTEA-clay), Wyoming bentonite (Na-clay), and water were mixed uniformly and compacted to simulate sand-and-clay liners for waste-disposal facilities. The hydraulic conductivities of the compacted soil cores were measured in triplicate. The hydraulic conductivities of cores containing 92 percent sand and 8 percent BTEA-clay were about of 10-4 cm/s. The hydraulic conductivities of cores containing 92 percent sand and 8 percent Na-clay and of cores containing 88 percent sand, 8 percent Na-clay, and 4 percent BTEA-clay were about 10-8 cm/s.

  10. [Adsorption Properties of Fluorine onto Fulvic Acid-Bentonite Complex].

    PubMed

    Fang, Dun; Tian, Hua-jing; Ye, Xin; He, Ci-li; Dan, You-meng; Wei, Shi-yong

    2016-03-15

    Fulvic Acid-Bentonite (FA-BENT) complex was prepared using coprecipitation method, and basic properties of the complex and sorption properties of fluorine at different environmental conditions were studied. XRD results showed that the d₀₀₁ spacing of FA- BENT complex had no obvious change compared with the raw bentonite, although the diffraction peak intensity of smectite in FA-BENT complex reduced, and indicated that FA mainly existed as a coating on the external surface of bentonite. Some functional groups (such as C==O, −OH, etc. ) of FA were observed in FA-BENT FTIR spectra, thus suggesting ligand exchange-surface complexation between FA and bentonite. Higher initial pH values of the reaction system were in favor of the adsorption of fluorine onto FA-BENT, while the equilibrium capacity decreased with the increase of pH at initial pH ≥ 4.50. The adsorption of fluorine onto FA-BENT was also affected by ionic strength, and the main reason might be the "polarity" effect. The adsorption of fluorine onto FA-BENT followed pseudo-second-order kinetic model and was controlled by chemical process ( R² = 0.999 2). Compared with the Freundlich model, Langmuir model was apparently of a higher goodness of fit (R² > 0.994 9) for absorption of fluorine onto FA-BENT. Thermodynamic parameters indicated that the adsorption process of fluorine was an spontaneously endothermic reaction, and was an entropy-driven process (ΔH 32.57 kJ · mol⁻¹, ΔS 112.31 J · (mol · K)⁻¹, ΔG −0.65- −1.76 kJ · mol⁻¹).

  11. Retardation capacity of organophilic bentonite for anionic fission products.

    PubMed

    Riebe, B; Bors, J; Dultz, S

    2001-02-01

    Sorption and diffusivity of iodide and pertechnetate (I- and TcO4-) on MX-80 bentonite with different hexadecylpyridinium (HDPy+) loadings were studied using equilibrium solutions of different ionic strengths. In HDPy(+)-modified bentonite, iodide and pertechnetate ions exhibited increasing sorption (characterized by the distribution ratio, Rd), while Cs+ and Sr2+ showed decreasing sorption with increasing organophilicity. In case of medium-loading levels, the simultaneous sorption of anions (I- and TcO4-) and cations (Cs+ and Sr2+) was observed. Sorption of ions was influenced by the composition of the electrolytes employed. It decreased gradually with increasing ionic strength of the electrolyte solutions. The experiments revealed the general tendency that the diffusivity (Da [cm2.s-1]) for iodide and pertechnetate decreases with increasing organophilicity and increases with increasing ionic strength of the equilibrium solutions, confirming the results of the sorption experiments. Additionally, some mineralogical and chemical investigations, like IR spectral analysis of the organo-bentonite samples and exchange behavior of HDPy+, were performed. On the basis of these analyses, it was concluded that the alkylammonium ions are sorbed as (1) HDPy+ cations, (2) HDPyCl molecules and (3) micelles with decreasing binding intensities in this order.

  12. Removal of rhodamine B using iron-pillared bentonite.

    PubMed

    Hou, Mei-Fang; Ma, Cai-Xia; Zhang, Wei-De; Tang, Xiao-Yan; Fan, Yan-Ning; Wan, Hong-Fu

    2011-02-28

    The iron-pillared bentonite (Fe-Ben) was prepared by ion-exchange using the natural bentonite (GZ-Ben) from Gaozhou, China, at room temperature without calcination. Both Fe-Ben and GZ-Ben were characterized by X-ray diffraction, N(2) adsorption and Fourier transform infrared spectroscopy. The results show that the d(001) value and surface area of the bentonite material increased after iron pillaring. Fe-Ben adsorbed much more Rhodamine B (RhB) than GZ-Ben, which can be ascribed to the special surface properties and large surface area of Fe-Ben. The optimum pH value for the adsorption of RhB on Fe-Ben is 5.0. The adsorption of RhB onto Fe-Ben can be well described by the pseudo-second-order kinetic model and the intraparticle diffusion kinetic model. The adsorption isotherm of RhB onto Fe-Ben matches well with the Langmuir model.

  13. Sorption kinetics and isotherm modelling of imidacloprid on bentonite and organobentonites.

    PubMed

    Jain, Shailesh K; Shakil, Najam A; Dutta, Anirban; Kumar, Jitendra; Saini, Mukesh K

    2017-02-22

    Bentonite was modified by quaternary ammonium cations viz. cetytrimethylammonium (CTA), cetylpyridinium (CP), rioctylmethylammonium (TOM) and pcholine (PTC) at 100% cation exchange capacity of bentonite and was characterized by X-ray diffraction, CHNS elemental analyser and Fourier transform infrared spectroscopy. The sorption of imidacloprid on organobentonites/bentonite was studied by batch method. Normal bentonite could adsorb imidacloprid only upto 19.31-22.18% while all organobentonites except PTC bentonite (PTCB), enhanced its adsorption by three to four times. Highest adsorption was observed in case of TOM bentonite (TOMB) (76.94-83.16%). Adsorption kinetic data were fitted to pseudo-first-order, pseudo-second-order and intraparticle diffusion models. For normal bentonite data were best fitted to pseudo-first-order kinetic, while for organobentonites fitted to pseudo-second-order kinetics. Sorption data were analysed using Freundlich, Langmuir, Temkin and Dubinin-Radushkevich isotherm models. Data were well fitted to Freundlich adsorption isotherm. Product of Freundlich adsorption constant and heterogeneity parameter (Kf.1/n) was in following order: TOMB (301.87) > CTA bentonite (CTAB) (152.12) > CP bentonite (CPB) (92.58) > bentonite (27.25). Desorption study confirmed hysteresis and concentration dependence. The present study showed that the organobentonite could be a good sorbent for removal of imidacloprid from natural water sample also. Percentage adsorption and Distribution coefficient (mL g(-1)) value of different adsorbent was in following order: TOMB (74.85% and 297.54) > CTAB (55.78% and 126.15) > CPB (45.81% and 84.55) > bentonite (10.65% and 11.92).

  14. Kaolin Foliar Application Has a Stimulatory Effect on Phenylpropanoid and Flavonoid Pathways in Grape Berries

    PubMed Central

    Conde, Artur; Pimentel, Diana; Neves, Andreia; Dinis, Lia-Tânia; Bernardo, Sara; Correia, Carlos M.; Gerós, Hernâni; Moutinho-Pereira, José

    2016-01-01

    Drought, elevated air temperature, and high evaporative demand are increasingly frequent during summer in grape growing areas like the Mediterranean basin, limiting grapevine productivity and berry quality. The foliar exogenous application of kaolin, a radiation-reflecting inert mineral, has proven effective in mitigating the negative impacts of these abiotic stresses in grapevine and other fruit crops, however, little is known about its influence on the composition of the grape berry and on key molecular mechanisms and metabolic pathways notably important for grape berry quality parameters. Here, we performed a thorough molecular and biochemical analysis to assess how foliar application of kaolin influences major secondary metabolism pathways associated with berry quality-traits, leading to biosynthesis of phenolics and anthocyanins, with a focus on the phenylpropanoid, flavonoid (both flavonol- and anthocyanin-biosynthetic) and stilbenoid pathways. In grape berries from different ripening stages, targeted transcriptional analysis by qPCR revealed that several genes involved in these pathways—VvPAL1, VvC4H1, VvSTSs, VvCHS1, VvFLS1, VvDFR, and VvUFGT—were more expressed in response to the foliar kaolin treatment, particularly in the latter maturation phases. In agreement, enzymatic activities of phenylalanine ammonia lyase (PAL), flavonol synthase (FLS), and UDP-glucose:flavonoid 3-O-glucosyltransferase (UFGT) were about two-fold higher in mature or fully mature berries from kaolin-treated plants, suggesting regulation also at a transcriptional level. The expression of the glutathione S-transferase VvGST4, and of the tonoplast anthocyanin transporters VvMATE1 and VvABCC1 were also all significantly increased at véraison and in mature berries, thus, when anthocyanins start to accumulate in the vacuole, in agreement with previously observed higher total concentrations of phenolics and anthocyanins in berries from kaolin-treated plants, especially at full

  15. Concept model of the formation process of humic acid-kaolin complexes deduced by trichloroethylene sorption experiments and various characterizations.

    PubMed

    Zhu, Xiaojing; He, Jiangtao; Su, Sihui; Zhang, Xiaoliang; Wang, Fei

    2016-05-01

    To explore the interactions between soil organic matter and minerals, humic acid (HA, as organic matter), kaolin (as a mineral component) and Ca(2+) (as metal ions) were used to prepare HA-kaolin and Ca-HA-kaolin complexes. These complexes were used in trichloroethylene (TCE) sorption experiments and various characterizations. Interactions between HA and kaolin during the formation of their complexes were confirmed by the obvious differences between the Qe (experimental sorbed TCE) and Qe_p (predicted sorbed TCE) values of all detected samples. The partition coefficient kd obtained for the different samples indicated that both the organic content (fom) and Ca(2+) could significantly impact the interactions. Based on experimental results and various characterizations, a concept model was developed. In the absence of Ca(2+), HA molecules first patched onto charged sites of kaolin surfaces, filling the pores. Subsequently, as the HA content increased and the first HA layer reached saturation, an outer layer of HA began to form, compressing the inner HA layer. As HA loading continued, the second layer reached saturation, such that an outer-third layer began to form, compressing the inner layers. In the presence of Ca(2+), which not only can promote kaolin self-aggregation but can also boost HA attachment to kaolin, HA molecules were first surrounded by kaolin. Subsequently, first and second layers formed (with inner layer compression) via the same process as described above in the absence of Ca(2+), except that the second layer continued to load rather than reach saturation, within the investigated conditions, because of enhanced HA aggregation caused by Ca(2+).

  16. Generation and stability of bentonite colloids at the bentonite/granite interface of a deep geological radioactive waste repository.

    PubMed

    Missana, Tiziana; Alonso, Ursula; Turrero, Maria Jesús

    2003-03-01

    The possible mechanisms of colloid generation at the near field/far field interface of a radioactive repository have been investigated by means of novel column experiments simulating the granite/bentonite boundary, both in dynamic and in quasi-static water flow conditions. It has been shown that solid particles and colloids can be detached from the bulk and mobilised by the water flow. The higher the flow rate, the higher the concentration of particles found in the water, according to an erosion process. However, the gel formation and the intrinsic tactoid structure of the clay play an important role in the submicron particle generation even in the compacted clay and in a confined system. In fact, once a bentonite gel is formed, in the regions where the clay is contacted with water, clay colloids can be formed even in quasi-static flow conditions. The potential relevance of these colloids in radionuclide transport has been studied by evaluating their stability in different chemical environments. The coagulation kinetics of natural bentonite colloids was experimentally studied as a function of the ionic strength and pH, by means of time-resolved light scattering techniques. It has been shown that these colloids are very stable in low saline (approximately 1 x 10(-3) M) and alkaline (pH > or = 8) waters.

  17. Characterization of AlFe-pillared Unye bentonite: A study of the surface acidity and catalytic property

    NASA Astrophysics Data System (ADS)

    Caglar, Bulent; Cubuk, Osman; Demir, Ersin; Coldur, Fatih; Catir, Mustafa; Topcu, Cihan; Tabak, Ahmet

    2015-06-01

    Aluminium-iron-pillared bentonite has been prepared by incorporation of the iron mixed aluminium-polyoxocation into bentonite layers and characterized by the powder X-ray diffraction, Fourier transform infrared, thermal analysis and surface area measurement techniques. The characteristic d001 basal spacing of raw bentonite increased with the pillaring process and reached to 18.05 Å. The siloxane layers of bentonite were perturbed and the positions of Si-O stretching vibrations were altered by pillaring process. However, these pillars in the interlayer gallery spacing enhanced the thermal stability of bentonite. The new micropores were formed by the pillaring process and the specific surface area of raw bentonite increased by ca. 2-fold for aluminium-iron-pillared bentonite. FTIR spectra and thermal analysis curves of pyridine adsorbed samples clearly show that the surface Lewis acidity of aluminium-iron-pillared bentonite is greater than that of raw bentonite. Raw and aluminium-iron-pillared bentonites have been utilized as solid catalysts for benzoylation of benzene with benzoyl chloride. The aluminium-iron-pillared bentonite catalyst showed promising catalytic activity whereas raw bentonite showed no catalytic activity in benzoylation of benzene with benzoyl chloride.

  18. Biodegradation of crystal violet using Burkholderia vietnamiensis C09V immobilized on PVA-sodium alginate-kaolin gel beads.

    PubMed

    Cheng, Ying; Lin, HongYan; Chen, Zuliang; Megharaj, Mallavarapu; Naidu, Ravi

    2012-09-01

    The strain, Burkholderia vietnamiensis C09V was immobilized on PVA-alginate-kaolin gel beads as a biomaterial to improve the degradation of crystal violet from aqueous solution. The results show that 98.6% (30 mg L(-1)) crystal violet was removed from aqueous solution using immobilized cells on PVA-alginate-kaolin gel beads, while 94.0% crystal violet was removed by free cells after degradation at the pH 5 and 30°C for 30 h. Kinetics studies show that the pseudo-second-order kinetics well described the adsorption of crystal violet on the PVA-alginate-kaolin beads. Biodegradation of crystal violet on immobilized cells was fitted well by first-order reaction kinetics, indicating that CV was adsorbed onto kaolin and followed their degradation by immobilized cells onto the the PVA-alginate-kaolin beads. Characterization with SEM shows that cells attached well to the surface of PVA-alginate-kaolin beads, leading to improved crystal violet transfer from aqueous solution to immobilized cells. In addition, UV-vis show that the absorption peak at 588 nm was reduced by the degraded N-bond linkages, as well as the formation of degrading products were observed by Fourier transform infrared (FTIR). These results suggest that crystal violet was biodegraded to N,N-dimethylaminophenol and Michler's Ketone prior to these intermediates being further degraded.

  19. Use of Kaolin-impregnated Gauze for Improvement of Intraoperative Hemostasis and Postoperative Wound Healing in Blepharoplasty

    PubMed Central

    Czyz, Craig N.; Stacey, Andrew W.; Cahill, Kenneth V.; Foster, Jill A.

    2016-01-01

    Purpose: Kaolin is a mineral shown to be effective in controlling hemorrhage when combined with standard gauze and applied to wounds. This study investigates the application of kaolin to control intraoperative bleeding and promote wound healing in eyelid surgery. Methods: This prospective, randomized, double-blind study recruited patients who underwent eyelid surgery. Following skin incision, kaolin-impregnated gauzewas placed in one eyelid wound bed and cotton gauze in the other, then removed. Distinct, individual areas of bleeding were recorded. Standardized photographs were obtained postoperatively on Day 1, 4, and 7. Photographs were graded for edema and ecchymosis by four blinded observers. Patients also completed a survey inquiring which side had more bruising, swelling, and pain at each return visit. Results: A total of 46 patients completed the study. The number of intraoperative bleeding sites for kaolin versus plain gauze was not significantly different (p=0.96). Photographic grading by blinded observers did not identify any statistically significant differences in postoperative edema at any time point between lids. There was a statistically significant difference for ecchymosis at postoperative Day 4 (p=0.009) and Day 7 (p=0.016). Patient surveys did not show any difference in perceived edema, ecchymosis, or pain between lids. Conclusion: Intraoperative hemostasis was not affected by the use of kaolin-impregnated gauze. The effectiveness of kaolin in wound healing showed improved ecchymosis at Days 4 and 7 when assessed by blinded observers. Patients did not notice any improvement in postoperative edema, ecchymosis, or pain. PMID:27386052

  20. Effects of kaolin-based particle film on spruce budworm (Choristoneura fumiferana (Lepidoptera: Tortricidae)) oviposition in the laboratory.

    PubMed

    Cadogan, Beresford L; Scharbach, Roger D

    2005-12-01

    A laboratory study conducted in 2003 determined the influence of a kaolin-based particle film (Surround WP Crop Protectant) on spruce budworm (Choristoneura fumiferana (Clem)) oviposition. Three concentrations (15, 30 and 60 g litre(-1) spray carrier) were applied to white spruce (Picea glauca (Moench) Voss). When presented with different paired choices of oviposition surfaces, spruce budworms laid very few egg masses overall and showed no significant (P < 0.05) preference between kaolin-coated and untreated foliage. During no-choice tests, spruce budworms were significantly (P < 0.05) less inclined to oviposit on the 60 g kaolin litre(-1) treated foliage than on the controls, but no kaolin treatment completely inhibited spruce budworm oviposition. Egg mass size and percentage hatch were unaffected by the kaolin treatments, and overall the percentage of egg masses laid on foliage was inversely proportional to treatment concentration. It is unlikely that kaolin-based particle film would be practical for wide use in natural forests without significant adaptations to current pesticide application equipment and methods. However, the technique might be feasible in selected urban settings.

  1. Effect of pH on the flocculation behaviors of kaolin using a pH-sensitive copolymer.

    PubMed

    Li, Shulei; Gao, Lihui; Cao, Yijun; Gui, Xiahui; Li, Zhen

    pH-sensitive copolymers have been widely introduced to achieve rapid dewatering and consolidation of solids in mining and oil sands processing wastes. But no more attention has been given to the flocculation efficiency of solid suspensions as a function of pH using pH-sensitive copolymer. In this study, a pH-sensitive copolymer was synthesized and employed to investigate the flocculation behaviors of kaolin by focused beam reflectance measurement (FBRM). A titration test was introduced to characterize the copolymer conformation transition. The results demonstrated that at pH ranging from 3 to 6, with the pH increase, the zeta potential magnitude of kaolin particles increased, resulting in the repulsive forces between particles increasing. However, the hydrophobicity of kaolin increased as the pH increased. Thus, the hydrophobic forces could neutralize a part of the repulsive forces between particles and result in good and similar flocculation performances. At the pH greater than 6, the zeta potential magnitude of kaolin particles and copolymer molecules increased significantly, and the repulsive force between kaolin particles increased after copolymer addition due to the kaolin particles being more negatively charged, which resulted in poor flocculation efficiency and cloudy supernatant. It was concluded that the pH-sensitive copolymer could achieve both perfect flocculation efficiency and low moisture of filter cake at the isoelectric point of copolymer.

  2. Effects of Kaolin on Lobesia botrana (Lepidoptera: Tortricidae) and Its Compatibility With the Natural Enemy, Trichogramma cacoeciae (Hymenoptera: Trichogrammatidae).

    PubMed

    Pease, Christina E; López-Olguín, Jesús F; Pérez-Moreno, Ignacio; Marco-Mancebón, Vicente

    2016-04-01

    Lobesia botrana (Denis and Schiffermüller) (Lepidoptera: Tortricidae) is an important grapevine pest in Europe recently encountered in America. Trichogramma cacoeciae Marchal (Hymenoptera: Trichogrammatidae) is amongst the most effective parasitoids for Lepidopteran species. Studies to evaluate the effect of kaolin, an inert, nontoxic mineral, on oviposition, egg hatch, and neonate mortality of these species were carried out. Efficacy on L. botrana neonate larvae, oviposition, and egg hatch was evaluated. Effects of kaolin on parasitism and emergence of T. cacoeciae from L. botrana and Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) eggs were also evaluated. Lobesia botrana egg hatch and oviposition rates were reduced, and neonate larvae mortality was significantly greater in kaolin-treated arenas and when included in synthetic neonate larvae diet. Kaolin had no effect on T. cacoeciae parasitism in both hosts. There was only a slight but statistically insignificant effect on T. cacoeciae progeny emergence from L. botrana eggs and no effect from E. kuehniella. The results involving reductions in L. botrana oviposition and egg hatch and increase in larval mortality with kaolin suggest this compound may contribute to reduction in population densities and can be considered in rational integrated pest management strategies for L. botrana. Due to the laboratory results presented on parasitoid emergence, even though field bioassays would give a more exhaustive evaluation, it appears kaolin can be compatible with T. cacoeciae in L. botrana management.

  3. Synthesis and characterization of poly(sodium acrylate)/ bentonite superabsorbent composite

    NASA Astrophysics Data System (ADS)

    Xie, Yiming; Wei, Yuelin; Huang, Yunfang; Lin, Jianming; Wu, Jihuai

    2012-01-01

    Poly(sodium acrylate)/bentonite superabsorbent composite with water absorbency 1562 g·g-1 was synthesized by inverse suspension polymerization. The introduction of bentonite improves the water absorbency and facilitates the particle size even distribution of the composite. The network structure in the superabsorbent hydrogel is confirmed.

  4. Theory and calculation of water distribution in bentonite in a thermal field

    SciTech Connect

    Carnahan, C.L.

    1988-09-01

    Highly compacted bentonite is under consideration for use as a buffer material in geological repositories for high-level radioactive wastes. To assess the suitability of bentonite for this use, it is necessary to be able to predict the rate and spatial extent of water uptake and water distribution in highly compacted bentonite in the presence of thermal gradients. The ''Buffer Mass Test'' (BMT) was conducted by workers in Sweden as part of the Stripa Project. The BMT measured uptake and spatial distributions of water infiltrating annuli of compacted MX-80 sodium bentonite heated from within and surrounded by granite rock; the measurements provided a body of data very valuable for comparison to results of theoretical calculations. Results of experiments on adsorption of water by highly compacted MX-80 bentonite have been reported by workers in Switzerland. The experiments included measurements of heats of immersion and adsorption-desorption isotherms. These measurements provide the basis for prediction of water vapor pressures in equilibrium with bentonite having specified adsorbed water contents at various temperatures. The present work offers a phenomenological description of the processes influencing movement of water in compacted bentonite in the presence of a variable thermal field. The theory is applied to the bentonite buffer-water system in an assumed steady state of heat and mass transport, using critical data derived from the experimental work done in Switzerland. Results of the theory are compared to distributions of absorbed water in buffers observed in the Swedish BMT experiments. 9 refs., 2 figs.

  5. Removal of nitrate by zero-valent iron and pillared bentonite.

    PubMed

    Li, Jianfa; Li, Yimin; Meng, Qingling

    2010-02-15

    The pillared bentonite prepared by intercalating poly(hydroxo Al(III)) cations into bentonite interlayers was used together with Fe(0) for removing nitrate in column experiments. The obvious synergetic effect on nitrate removal was exhibited through uniformly mixing the pillared bentonite with Fe(0). In such a mixing manner, the nitrate was 100% removed, and the removal efficiency was much higher than the simple summation of adsorption by the pillared bentonite and reduction by Fe(0). The influencing factors such as bentonite type, amount of the pillared bentonite and initial pH of nitrate solutions were investigated. In this uniform mixture, the pillared bentonite could adsorb nitrate ions, and facilitated the mass transfer of nitrate onto Fe(0) surface, then accelerated the nitrate reduction. The pillared bentonite could also act as the proton-donor, and helped to keep the complete nitrate removal for at least 10h even when the nitrate solution was fed at nearly neutral pH.

  6. Bentonite modification with hexadecylpyridinium and aluminum polyoxy cations and its effectiveness in Se(IV) removal.

    PubMed

    Orucoglu, Esra; Haciyakupoglu, Sevilay

    2015-09-01

    Usage of bentonite as a buffer material is suggested in radioactive waste repositories. Although bentonites have higher sorption ability to cations, they cannot adsorp anions due to negative surface charge. Nowadays, ongoing researches focus on increasing anion adsorption ability of the bentonites with modification. Organic-pillared bentonite (OPBent) was produced by modification of sodium bentonite with aluminum polyoxy and hexadecylpyridinium cations in this study. Variation in structure after modification was demonstrated by using different characterization techniques. Se removal efficiency of OPBent is investigated by using (75)Se, since selenium (Se) is one of the important long lived fission products found in radioactive waste and has toxic anionic species in an aqueous environment. The effect of reaction time, solid/liquid ratio, pH and concentration on the adsorption performance were examined. Se speciation and its effect onto adsorption were also investigated by measuring Eh-pH values under certain experimental conditions. Additionally, importance of the amount of Al-polyoxy cations used in modification was investigated by comparing these results with the results of other organic-pillared bentonite produced in our previous research. Experimental results confirmed that both cations were successfully placed into the bentonite interlayer and significant change in the host structure leads to increase Se adsorption. Consequently, bentonite modification improves its Se adsorption ability and further investigations are needed related to the usage of this adsorbent in other remediation studies especially in sorption of other anionic pollutants.

  7. Use of modified hydroxy-aluminum bentonites for chromium(III) removal from solutions.

    PubMed

    Volzone, Cristina; Beatriz Garrido, Liliana

    2008-09-01

    The retention of chromium(III) from a 2,000 ppm chromium basic sulfate and tannery waste solution at pH 4.5 using modified hydroxy-aluminum bentonites (OH-Al bentonites) as adsorbents was studied. OH-Al bentonite was prepared by mixing clay with a hydrolyzed commercial chlorohydroxy Al solution. The modified Al bentonites were obtained by (a) a treatment with 0.5M sodium chloride and (b) a treatment with a Na-hexametaphosphate solution (HMP) after adding sodium chloride. The effect of heating the adsorbents at 100, 500, 700 and 800 degrees C on Cr retention as a function of time was also analyzed. Cr retention by modified OH-Al bentonite with HMP increased with time (up to 100 mg Cr/g) where modified OH-Al bentonite was twice that of untreated bentonite. The relatively high uptake of metal from the salt solution by modified OH-Al bentonite treated at 800 degrees C, in which a complete interlayer collapse occurred, indicated the importance of the contribution of external surface sites to the retention capacity. The maximum Cr uptake from a water waste was 24 mg/g, due to interferences and different chromium species in the industrial solution.

  8. Corrosion of high-level radioactive waste iron-canisters in contact with bentonite.

    PubMed

    Kaufhold, Stephan; Hassel, Achim Walter; Sanders, Daniel; Dohrmann, Reiner

    2015-03-21

    Several countries favor the encapsulation of high-level radioactive waste (HLRW) in iron or steel canisters surrounded by highly compacted bentonite. In the present study the corrosion of iron in contact with different bentonites was investigated. The corrosion product was a 1:1 Fe layer silicate already described in literature (sometimes referred to as berthierine). Seven exposition test series (60 °C, 5 months) showed slightly less corrosion for the Na-bentonites compared to the Ca-bentonites. Two independent exposition tests with iron pellets and 38 different bentonites clearly proved the role of the layer charge density of the swelling clay minerals (smectites). Bentonites with high charged smectites are less corrosive than bentonites dominated by low charged ones. The type of counterion is additionally important because it determines the density of the gel and hence the solid/liquid ratio at the contact to the canister. The present study proves that the integrity of the multibarrier-system is seriously affected by the choice of the bentonite buffer encasing the metal canisters in most of the concepts. In some tests the formation of a patina was observed consisting of Fe-silicate. Up to now it is not clear why and how the patina formed. It, however, may be relevant as a corrosion inhibitor.

  9. In vitro biologic toxicity of native and surface-modified silica and kaolin

    SciTech Connect

    Wallace, W.E. Jr.; Vallyathan, V.; Keane, M.J.; Robinson, V.

    1985-01-01

    An in vitro study of the biologic responses of surface-modified and native silica and kaolin was made to provide comparative information on the suppression of cytotoxicity by pulmonary surfactant. The release of alveolar macrophage cytoplasmic enzyme, lactate dehydrogenase (LDH), and lysosomal enzymes ..beta..-N-acetylglucosaminidase (..beta..-NAG) and ..beta..-glucuronidase (..beta..-GLUC) and sheep blood-cell hemolysis were monitored as indicators of cell membrane damage and cytotoxicity. Surface modification of silica and kaolin with dipalmitoyl lecithin (DPL) resulted in complete abrogation of cytotoxicity of both minerals. These findings indicate that surface modification of minerals with different adsorption properties by pulmonary surfactant generally lessens their prompt adverse effects.

  10. Adsorption of sodium dodecyl sulfate on kaolin from different alcohol-water mixtures

    SciTech Connect

    Blokhus, A.M.; Hoeiland, H.; Gjerde, M.I.; Ersland, E.K.

    1996-05-10

    The adsorption of surfactants on solid/liquid interfaces is a subject of great interest especially for enhanced oil recovery processes. The adsorption of sodium dodecyl sulfate (SDS) onto kaolin from different alcohol-water mixtures has been studied. The alcohols used were 1-propanol, 1-butanol, 1-pentanol, and 1-decanol containing 3.5 or 7 wt% water. In all cases the adsorption isotherms show a rather steep rise at low surfactant concentrations. Thereafter, there is a more or less continuous leveling off. The plateau adsorption of SDS on kaolin is found to increase with increasing chain length of the alcohol in the alcohol-water solvent. The adsorption properties are discussed in relation to the dielectric constant of the solvents; the aggregation properties of the surfactant in the bulk phase and the molecular packing of the surfactant in the adsorbed state are also considered.

  11. Concentrations of (226)Ra, (232)Th and (4)(0)K in industrial kaolinized granite.

    PubMed

    Todorović, Nataša; Hansman, Jan; Mrđa, Dušan; Nikolov, Jovana; Kardos, Richárd; Krmar, Miodrag

    2017-03-01

    Activity concentrations of (226)Ra, (232)Th and (4)(0)K in 120 kaolinized granite samples imported in Serbia from the Motajica mine, Bosnia and Herzegovina, were measured. The (226)Ra concentration ranged from 61 to 319 Bq kg(-1), the (232)Th from 44 to 272 Bq kg(-1), and the (4)(0)K from 590 to 1470 Bq kg(-1). The frequency distribution of (4)(0)K concentrations was near-Gaussian, where those of (226)Ra and (232)Th were right-skewed. In 6 samples, the gamma index, I, was higher than 2, which exceeds the exemption dose criterion (0.3 mSv y(-1)). The absorbed dose rate and annual effective doses for workers in the ceramic industries in Serbia who worked with kaolinized granite were below levels of concern.

  12. Surface properties of kaolin and illite suspensions in concentrated calcium hydroxide medium.

    PubMed

    Konan, Koffi Léon; Peyratout, Claire; Bonnet, Jean-Pierre; Smith, Agnès; Jacquet, Alain; Magnoux, Patrick; Ayrault, Philippe

    2007-03-01

    The adsorption behaviour of calcium hydroxide onto illite and kaolin clay minerals was investigated by monitoring with atomic emission spectroscopy and pH measurements the amounts of ions left in solution after exposing clay minerals to calcium hydroxide solutions of various concentrations. Both clay minerals can adsorb calcium and hydroxyl ions. Rather than just considering proton exchanges at the clay mineral surfaces, the adsorption is explained by an approach based on Lewis description of molecules. With this approach, a mechanism for calcium hydroxide adsorption not only at the edges of the clay particles but also onto the faces is proposed. In order to gain a better insight onto the active groups at the surface of the studied clay minerals, adsorption of pyridine and ammonia on illite and kaolin was followed by FTIR spectroscopy. These measurements gave the signature of edges, which are marginally involved in interactions with calcium ions.

  13. Utilization of kaolin processing waste for the production of porous ceramic bodies.

    PubMed

    Menezes, Romualdo R; Brasileiro, Maria I; Santana, Lisiane N L; Neves, Gelmires A; Lira, Helio L; Ferreira, Heber C

    2008-08-01

    The kaolin processing industry generates large amounts of waste in producing countries such as Brazil. The aim of this study was to characterize kaolin processing waste and evaluate its suitability as an alternative ceramic raw material for the production of porous technical ceramic bodies. The waste material was physically and chemically characterized and its thermal behaviour is described. Several formulations were prepared and sintered at different temperatures. The sintered samples were characterized to determine their porosity, water absorption, firing shrinkage and mechanical strength. Fired samples were microstructurally analysed by X-ray diffraction and scanning electron microscopy. The results indicated that the waste consisted of quartz, kaolinite, and mica, and that ceramic formulations containing up to 66% of waste can be used for the production of ceramics with porosities higher than 40% and strength of about 70 MPa.

  14. Biodegradability and swelling capacity of kaolin based chitosan-g-PHEMA nanocomposite hydrogel.

    PubMed

    Pradhan, Arun Kumar; Rana, Pradeep Kumar; Sahoo, Prafulla Kumar

    2015-03-01

    Chitosan, a natural biopolymer, obtained by alkaline deacetylation of chitin, exhibits excellent biological properties such as biodegradability, immunological and antibacterial activity. Recently, there has been a growing interest in the chemical modification of chitosan in order to widen its applications. The chemical modification of chitosan has been achieved via grafting of monomer, 2-hydroxyethyl methacrylate (HEMA) in the presence of the initiator, ammonium persulfate (APS) and kaolin was added to improve the mechanical strength of the newly developed nanocomposites hydrogel. The so prepared grafted nanocomposites hydrogel was characterized by FTIR, XRD, SEM, TEM and TGA. The equilibrium water content (EWC) of the samples were measured at different pH ranges 6.5-8.0 and found optimum at pH 7.5 for biomedical applications. Further, the biodegradability of the samples was studied at different time intervals from 15 days to 1 year but, the kaolin based nanohydrogels exhibited good biodegradability.

  15. New organophilic kaolin clays based on single-point grafted 3-aminopropyl dimethylethoxysilane.

    PubMed

    Zaharia, A; Perrin, F-X; Teodorescu, M; Radu, A-L; Iordache, T-V; Florea, A-M; Donescu, D; Sarbu, A

    2015-10-14

    In this study, the organophilization procedure of kaolin rocks with a monofunctional ethoxysilane- 3 aminopropyl dimethyl ethoxysilane (APMS) is depicted for the first time. The two-step organophilization procedure, including dimethyl sulfoxide intercalation and APMS grafting onto the inner hydroxyl surface of kaolinite (the mineral) layers was tested for three sources of kaolin rocks (KR, KC and KD) with various morphologies and kaolinite compositions. The load of APMS in the kaolinite interlayer space was higher than that of 3-aminopropyl triethoxysilane (APTS) due to the single-point grafting nature of the organophilization reaction. A higher long-distance order of kaolinite layers with low staking was obtained for the APMS, due to a more controllable organiphilization reaction. Last but not least, the solid state (29)Si-NMR tests confirmed the single-point grafting mechanism of APMS, corroborating monodentate fixation on the kaolinite hydroxyl facets, with no contribution to the bidentate or tridentate fixation as observed for APTS.

  16. Cytotoxicity and mechanical behavior of chitin-bentonite clay based polyurethane bio-nanocomposites.

    PubMed

    Zia, Khalid Mahmood; Zuber, Mohammad; Barikani, Mehdi; Hussain, Rizwan; Jamil, Tahir; Anjum, Sohail

    2011-12-01

    Chitin based polyurethane bio-nanocomposites (PUBNC) were prepared using chitin, Delite HPS bentonite nanoclay enriched in montmorillonite (MMT), 4,4'-diphenylmethane diisocyanate (MDI) and polycaprolactone polyol CAPA 231 (3000 g/mol(-1)). The prepolymers having different concentration of Delite HPS bentonite nanoclay were extended with 2 moles of chitin. The structures of the resulted polymers were determined by FT-IR technique. The effect of nanoclay contents on mechanical properties and in vitro biocompatibility was investigated. The mechanical properties of the synthesized materials were improved with increase in the Delite HPS bentonite nanoclay contents. Optimum mechanical properties were obtained from the PU bio-nanocomposite samples having 4% Delite HPS bentonite nanoclay. The results revealed that the final PU bio-nanocomposite having 2% Delite HPS bentonite nanoclay contents is ideal contenders for surgical threads with on going investigations into their in vitro biocompatibility, non-toxicity, and mechanical properties.

  17. Adsorption and hydraulic conductivity of landfill-leachate perfluorinated compounds in bentonite barrier mixtures.

    PubMed

    Li, Belinda; Li, Loretta Y; Grace, John R

    2015-06-01

    Perfluorinated compounds (PFCs) are leached in landfills from a wide range of domestic and industrial products. Sodium bentonite, a common barrier material, was contacted with water and landfill leachate spiked with PFCs in batch adsorption tests to measure PFC adsorption. Leaching cell tests were also conducted in which water, landfill leachate and PFC-spiked leachate permeated through compacted sand-bentonite mixtures. It was found that the PFCs did not bind substantially to the bentonite. Hydraulic conductivities were not appreciably affected by the PFCs, showing that bentonite liners are not affected for the range of concentrations tested. The sand-bentonite mixture partially retained the PFCs, indicating limited effectiveness in containing PFC within landfills.

  18. Microcapillary flow behavior of magnetic nanofluids in the presence of plate shaped bentonite particles

    NASA Astrophysics Data System (ADS)

    Parmar, Mayur; Virpura, Hiral; Patel, Rajesh

    2013-04-01

    Plate shaped bentonite particles of size ˜600 nm and thickness ˜2 nm are dispersed in a magnetic nanofluid. Magnetic field dependent flow behavior of this composite suspension is studied using a horizontal microcapillary placed between the poles of an electromagnet. The plate shaped bentonite particle produces extra hindrance to the flow under the application of moderate magnetic field and produces an enhanced magnetoviscous effect. 75% volume concentration of bentonite produces eight times larger change in magnetic field dependent viscosity than does the pure magnetic nanofluid. Hindrance to the flow is due to the chain like structure of magnetic nanoparticles, tumbling and rotational motion of bentonite particles and interaction between magnetic and bentonite particles. The field-induced structures are also observed using an optical microscope. Results offer several advantages over the inverse MR effect as well as to study the motion of biological cells and tissues under the effect of magnetic field.

  19. Effects of humic acid on recoverability and fractal structure of alum-kaolin flocs.

    PubMed

    Zhong, Runsheng; Zhang, Xihui; Xiao, Feng; Li, Xiaoyan

    2011-01-01

    Particle surface characteristics, floc recoverability and fractal structure of alum-kaolin flocs were investigated using in situ particle image velocimetry (PIV) and microbalance with or without humic acid. Experimental results indicated that the zeta potential of kaolin particle surface after adsorption of humic acid was related with humic acid concentration and its acid-base buffering capacity. Adsorption of humic acid resulted in more negative electrophoresis on the particle surface. Coagulant dosages for particles to form flocs would increase with increasing humic concentration. PIV was used to evaluate floc structural fragmentation, floc surface erosion as well as recoverability after high shear. It was found that the floc size during the steady phase of growth was small, while the regrowing capability decreased in the presence of humic acid. The recoverability was closely related with floc breakage modes including floc structural fragmentation and floc surface erosion. The fractal dimensions of alum-kaolin flocs by mass-size method based on microbalance would decrease with increasing humic concentration. This study proved that humic acid had adverse influences on the performance of coagulation process.

  20. Effects of cyclophosphamide on the kaolin consumption (pica behavior) in five strains of adult male rats.

    PubMed

    Tohei, Atsushi; Kojima, Shu-ichi; Ikeda, Masashi; Hokao, Ryoji; Shinoda, Motoo

    2011-07-01

    It is known that pica, the consumption of non-nutritive substances such as kaolin, can be induced by administration of toxins or emetic agents in rats. In the present study, we examined the effects of intraperitoneal (i.p.) administration of cyclophosphamide on pica behavior and on the concentration of 5-hydroxyindoleacetic acids (5HIAA) in cerebrospinal fluid (CSF) in the following five strains of adult male rats: Sprague Dawley (SD), Wistar, Fischer 344 (F344), Wistar-Imamichi (WI) and Long Evans (LE). Cyclophosphamide (25 mg or 50 mg/kg) was injected (i.p.) into the rats and kaolin and food intake were measured at 24 hr after injection. The animals were anesthetized with urethane (1 g/kg) at 3 hr after injection of cyclophosphamide, and CSF was collected from the cisterna magna. WI and LE rats clearly showed pica behavior as compared with the other strains. In LE rats, the concentration of 5HIAA in CSF also increased in a dose-dependent manner of cyclophosphamide. The pretreatment with ondansetron (5-HT(3) antagonist) restored both changes (kaolin consumption and 5HIAA levels) induced by cyclophosphamide. These results suggest that the LE rat is sensitive to cyclophosphamide, that pica induced by cyclophosphamide mimics many aspects of emesis including the serotonergic response in the central nervous system and that use of the pica model would be a practical method for evaluating the effects of antiemetic drugs in addition to the mechanism of emesis.

  1. Arthritic disease is more severe in older rats in a kaolin/carrageenan-induced arthritis model.

    PubMed

    Kim, Kyoung Soo; Kim, Myung-Hwan; Yeom, Mijung; Choi, Hyun Mi; Yang, Hyung-In; Yoo, Myung Chul; Hahm, Dae-Hyun

    2012-12-01

    This study examined in an arthritis animal model whether elderly onset rheumatoid arthritis (EORA) is a more severe disease than younger onset rheumatoid arthritis. Arthritis was induced by injecting 5% kaolin/carrageenan into the left tibiotarsal ankles of 18-month-old and 4-week-old rats. Various parameters were measured to evaluate the arthritic progression of kaolin/carrageenan-induced arthritis in the rats. Immunohistochemical staining of arthritic joints was performed to determine the degree of inflammation in old and young rats. Measurements of ankle volume and thickness, arthritic index, number of squeaks, and the paw pressure test showed the 18-month-old rats had more severe disease than the young rats in a kaolin/carrageenan-induced arthritis model. The degree of inflammation and MMP-1 expression of arthritic joints in old rats was significantly higher than that of young rats based on histological evaluation with hematoxylin and eosin (H&E) staining and immunochemistry. More severe disease symptoms were found in old rats with EORA, but the molecular mechanisms still remain to be elucidated. Understanding the molecular mechanisms will be helpful to develop clinical protocols to efficiently treat patients with EORA, which is difficult to control with current protocols.

  2. Kaolin processing waste applied in the manufacturing of ceramic tiles and mullite bodies.

    PubMed

    Menezes, Romualdo R; Farias, Felipe F; Oliveira, Maurício F; Santana, Lisiane N L; Neves, Gelmires A; Lira, Helio L; Ferreira, Heber C

    2009-02-01

    In the last few years, mineral extraction and processing industries have been identified as sources of environmental contamination and pollution. The kaolin processing industry around the world generates large amounts of waste materials. The present study evaluated the suitability of kaolin processing waste as an alternative source of ceramic raw material for the production of ceramic tiles and dense mullite bodies. Several formulations were prepared and sintered at different temperatures. The sintered samples were characterized to determine their porosity, water absorption, firing shrinkage and mechanical strength. The fired samples were microstructurally analysed by X-ray diffraction. The results indicated that ceramic tile formulations containing up to 60% of waste could be used for the production of tiles with low water absorption (approximately 0.5%) and low sintering temperature (1150 degrees C). Mullite formulations with more than 40% of kaolin waste could be used in the production of bodies with high strength, of about 75 MPa, which can be used as refractory materials.

  3. Experimental study on mechanical properties of gas hydrate-bearing sediments using kaolin clay

    NASA Astrophysics Data System (ADS)

    Li, Yang-Hui; Song, Yong-Chen; Yu, Feng; Liu, Wei-Guo; Zhao, Jia-Fei

    2011-03-01

    A triaxial system is designed with a temperature range from -20 °C to 25 °C and a pressure range from 0 MPa to 30 MPa in order to improve the understanding of the mechanical properties of gas hydrate-bearing sediments. The mechanical properties of synthetic gas hydrate-bearing sediments (gas hydrate-kaolin clay mixture) were measured by using current experimental apparatus. The results indicate that: (1) the failure strength of gas hydrate-bearing sediments strongly depends on the temperature. The sediment's strength increases with the decreases of temperature. (2) The maximum deviator stress increases linearly with the confining pressure at a low-pressure stage. However, it fluctuates at a high-pressure stage. (3) Maximum deviator stress increases with increasing strain rate, whereas the strain-stress curve has no tremendous change until the axial strain reaches approximately 0.5%. (4) The internal friction angles of gas hydrate-bearing sediments are not sensitive to kaolin volume ratio. The cohesion shows a high kaolin volume ratio dependency.

  4. Transport of Iodide Ion in Compacted Bentonite Containing Ag{sub 2}O - 12111

    SciTech Connect

    Yim, Sung Paal; Lee, Ji-Hyun; Choi, Heui-Joo; Choi, Jong-Won; Lee, Cheo Kyung

    2012-07-01

    Observations of the transport of iodide through compacted bentonite containing Ag{sub 2}O as additive and that without additive were made. Compacted bentonite samples with densities of 1.41 g/cm{sup 3} and 1.60 g/cm{sup 3} were used in the experiment. The amount of Ag{sub 2}O added to the compacted bentonite was in the range of 0.0064 ∼ 0.0468 wt/wt%. Two diffusion solutions were used: one in which iodide ion was dissolved in demineralized water (pure iodide solution), and one in which iodide ion was dissolved in 0.1 M NaCl solution (0.1 M NaCl-iodide solution). Experimental results confirmed that iodide ion was transported by the diffusion process in the compacted bentonite containing Ag{sub 2}O as well as in the compacted bentonite without Ag{sub 2}O. The time-lag of diffusion of iodide ion in the compacted bentonite containing Ag{sub 2}O is larger than that in the compacted bentonite without Ag{sub 2}O. The increase of the time-lag of diffusion was observed in pure iodide ion solution as well as in 0.1 M NaCl-iodide solution. The apparent diffusion coefficient of iodide ion in the compacted bentonite containing Ag{sub 2}O was smaller than in the compacted bentonite without Ag{sub 2}O. The effective diffusion coefficient decreased as the amount of Ag{sub 2}O in the compacted bentonite increased. (authors)

  5. The advantages of a salt/bentonite backfill for Waste Isolation Pilot Plant disposal rooms

    SciTech Connect

    Butcher, B.M.; Novak, C.F. ); Jercinovic, M. )

    1991-04-01

    A 70/30 wt% salt/bentonite mixture is shown to be preferable to pure crushed salt as backfill for disposal rooms in the Waste Isolation Pilot Plant (WIPP). This report discusses several selection criteria used to arrive at this conclusion: the need for low permeability and porosity after closure, chemical stability with the surroundings, adequate strength to avoid shear erosion from human intrusion, ease of emplacement, and sorption potential for brine and radionuclides. Both salt and salt/bentonite are expected to consolidate to a final state of impermeability (i.e., {le} 10{sup {minus}18}m{sup 2}) adequate for satisfying federal nuclear regulations. Any advantage of the salt/bentonite mixture is dependent upon bentonite's potential for sorbing brine and radionuclides. Estimates suggest that bentonite's sorption potential for water in brine is much less than for pure water. While no credit is presently taken for brine sorption in salt/bentonite backfill, the possibility that some amount of inflowing brine would be chemically bound is considered likely. Bentonite may also sorb much of the plutonium, americium, and neptunium within the disposal room inventory. Sorption would be effective only if a major portion of the backfill is in contact with radioactive brine. Brine flow from the waste out through highly localized channels in the backfill would negate sorption effectiveness. Although the sorption potentials of bentonite for both brine and radionuclides are not ideal, they are distinctly beneficial. Furthermore, no detrimental aspects of adding bentonite to the salt as a backfill have been identified. These two observations are the major reasons for selecting salt/bentonite as a backfill within the WIPP. 39 refs., 16 figs., 6 tabs.

  6. Bentonite supplementation can improve performance and fermentation parameters of chronic lead-exposed lambs.

    PubMed

    Azadbakht, S; Khadem, A A; Norouzian, M A

    2017-02-01

    Two experiments were conducted to investigate the effect of supplemental bentonite on performance, blood, and fermentation characteristics in Zandi lambs. In experiment 1, 20 Zandi male lambs (initial BW, 17.5 ± 1.6 kg and 110 ± 5 days old) were randomly assigned into four groups of five animals in each. The experimental treatments were (1) control (no Pb and bentonite), (2) 15 mg/kg DM Pb as Pb acetate and no bentonite, (3) 15 mg/kg DM Pb as Pb acetate and 1.5% bentonite, and (4) 15 mg/kg DM Pb as Pb acetate and 3% bentonite. The dietary treatments had no significant effect on dry matter intake of experimental lambs. Feed required per unit of weight gain was more (P < 0.05) in lead-exposed lambs in group 2 compared to the control and bentonite supplemented groups. Serum glucose, urea nitrogen, cholesterol, HDL, and LDL concentrations was similar among the treatments. In experiment 2, an in vitro gas production technique was used to evaluate the effects of bentonite supplementation on the gas production parameters of lead-polluted diets. The rate and amount of gas production was higher for bentonite supplemented groups (P < 0.01). Asymptotic gas production (b), metabolizable energy, and concentration of short chain fatty acids were lower (P < 0.05) for lead-polluted non-supplemented diet (group 2) as compared to the bentonite supplemented and control groups. It was concluded that bentonite supplementation favorably modified ruminal fermentation pattern and improved feed conversion ratio in growing lead-exposed lambs.

  7. Influence of mixtures of kaolin particle film and synthetic insecticides on mortality of larval obliquebanded leafrollers (Lepidoptera: Tortricidae) from resistant and susceptible populations.

    PubMed

    Smirle, Michael J; Lowery, D Thomas; Zurowski, Cheryl L

    2007-12-01

    Experiments were conducted to determine potential interactions between kaolin particle film and three insecticides on neonate larvae of the obliquebanded leafroller, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae). Kaolin did not significantly affect the toxicity of azinphosmethyl or indoxacarb to an insecticide-susceptible population when applied simultaneously with either insecticide in a 7-d leaf disk bioassay. Methoxyfenozide was slightly more toxic to the same leafroller population when coapplied with kaolin. When these bioassays were repeated on a multiresistant laboratory strain of C. rosaceana, mixtures of kaolin with either azinphosmethyl or indoxacarb were significantly more toxic than the insecticides alone, 3.1- and 7.7-fold more toxic for azinphosmethyl:kaolin and indoxacarb:kaolin, respectively. Mixtures of kaolin and methoxyfenozide did not differ in toxicity to the resistant leafroller population from the toxicity of methoxyfenozide alone. Kaolin alone had no effect on leafroller mortality over the 7-d duration of the bioassay. Although the toxicities of mixtures of kaolin with azinphosmethyl or indoxacarb are only moderately higher than those of the insecticides alone, they may be high enough to provide control of leafroller populations that have become difficult to manage due to the development of insecticide resistance.

  8. Productivity, blood metabolites and carcass characteristics of fattening Zandi lambs fed sodium bentonite supplemented total mixed rations.

    PubMed

    Khadem, A A; Soofizadeh, M; Afzalzadeh, A

    2007-10-15

    Thirty male Zandy lambs (25 +/- 0.50 kg BW, 10 lambs in each group) were randomly allocated in three (control, 2% bentonite and 4% bentonite) treatment groups. Lambs were fed Total Mixed Rations (TMRs) containing 75% Concentrate Mixture (CM) and 25% forage. Sodium bentonite was mixed with the CM part of TMRs before being mixed with the forage. The fattening period lasted 84 days and data were collected on the performance, blood metabolites and carcass characteristics of lambs. Results showed that sheep fed bentonite added diets had relatively higher feed intake than the control group which ended to slightly higher weight change with a fairly appropriate feed conversion ratio in bentonite fed animals. Compared to the control group, a reasonably lower glucose and urea concentration and a higher total protein content was observed in the blood of sheep fed bentonite supplemented diets. The use of bentonite in diets did not affect the blood cholesterol contents of sheep. Slaughter weights, carcass dressing out percentages and carcass cuts were a bit higher in sheep of bentonite fed groups compared to those in control group. Sheep fed bentonite added diets produced carcasses with lower subcutaneous fat thicknesses and lower fat-tail percentages. Furthermore, feed cost was estimated to be lower for sheep in 2% bentonite group than that in other two groups. In conclusion, the use of two-percent sodium bentonite is suggested for diets of fattening lambs in Iranian feed markets.

  9. An evaluation of soluble cations and anions on the conductivity and rate of flocculation of kaolins

    NASA Astrophysics Data System (ADS)

    Fulton, Deborah Lee

    1998-10-01

    The focus of this project was to learn how ionic concentrations and their contributions to electric conductivity influence the flocculation behavior of kaolin/water suspensions. Sodium silicate, calcium chloride, and magnesium sulfate were used as chemical additives. The specific surface areas, particle size distributions, and methylene blue indices for two kaolins were measured. The SSA and MBI for these kaolins indicated that they possessed inherent differences in SSA and flocculation behaviors. Rheological studies were also performed. Testing included simultaneous gelation, deflocculation, and pH tests. Viscosity, pH, temperature, and chemical additive concentrations were monitored at each point. Testing was performed at 45/55 wt% solids. Effects of additions of various levels of deflocculant and flocculant to each of the kaolin/water suspensions were studied by making several suspensions from each kaolin. The concentrations of dispersant, and flocculant levels and types were varied to produce suspensions with different chemical additive "histories," but all with similar final apparent viscosities. Slurry filtrates were analyzed for conductivity, pH, temperature, and ion concentrations of (Al3+, Fe2+,3+, Ca 2+, Mg+, Na+, SO4 2--, and Cl--). Plastic properties were calculated to determine how variations in suspension histories affected conductivities, pH, and detectable ion contents of the suspensions. These analyses were performed on starting slurries which were under-, completely-, and over-deflocculated before further additions of flocculants and deflocculant were added to tune the slurries to the final, constant, target viscosity. Results showed that rates of flocculation and conductivities increased as concentrations of ions increased. By increasing conductivity correlations with increases in flocculation occurs, which yields higher rates of buildup, or RBU [1]. This is the single most important slip control property in the whitewares industry. Shear

  10. Sorption mechanism of Pu, Am and Se on sodium-bentonite

    SciTech Connect

    Shibutani, Tomoki; Yui, Mikazu; Yoshikawa, Hideki

    1994-12-31

    The distribution coefficients (Kd) were measured for Pu, Am and Se on sodium-bentonite in bentonite-equilibrated distilled water in a pH range 4 {approximately} 10. Sodium-bentonite includes sodium-montmorillonite and ferrous minerals such as pyrite. The experiments were carried out by using the batch method under aerobic conditions for Pu, Am and under anaerobic conditions for Se. The distribution coefficients for Pu and Am were in the range 10{sup 0} {approximately} 10{sup 2}m{sup 3}/kg on sodium-bentonite in the above pH range. The sorption of Pu and Am was modeled by ion exchange of these cationic aqueous species with interlayer cations of sodium-bentonite. The distribution coefficients of Se on sodium-bentonite were interpreted by using a surface complexation model. The model was based on the assumption that the sorption behavior was dominated by ferric-oxyhydroxide, goethite, coating on the surface of pyrite. Sorption behavior of Am in compacted bentonite were also discussed by using cation exchange model.

  11. Geochemical properties of bentonite pore water in high-level-waste repository condition

    SciTech Connect

    Ohe, Toshiaki; Tsukamoto, Masaki

    1997-04-01

    The chemically favorable nature of bentonite pore water is clarified by the PHREEQE geochemical simulation code. Bentonite is viewed as a candidate buffer material for a high-level-waste repository, and bentonite`s pore water chemistry is expected to result in a reduced Eh and weak alkaline pH region. Pyrite (Fe{sub 2}S), initially contained in bentonite, alters to magnetite (Fe{sub 3}O{sub 4}), and this redox couple reaction controls the oxidation reduction potential. A mild alkaline pH condition is produced mainly by an ion exchange reaction between the sodium in bentonite and the protons in the solution. A geochemical simulation of the ion exchange reactions and the pyrite-magnetite alteration suggests that a favorable chemical condition would exist during the waste glass dissolution and indicates that the Ph and the Eh values are {minus}7.5 to {minus}9.4 and {minus}450 to {minus}320 mV, respectively, when the granitic groundwater intrudes into the compacted bentonite in the repository.

  12. Modelling approaches for anion-exclusion in compacted Na-bentonite

    NASA Astrophysics Data System (ADS)

    Tournassat, C.; Appelo, C. A. J.

    2011-07-01

    The accessible porosity for Cl - in bentonite is smaller than the the total porosity due to anion repulsion (exclusion) by the surface of montmorillonite, the main mineral in bentonite. The accessible porosity is a function of the bentonite density and the salt concentration. Anion exclusion data were gathered from the literature, reprocessed in a coherent data set, and modelled using four different models. Very simple models, with or without anion access to the interlayer space, are successful in reproducing trends in anion exclusion in bentonite as a function of ionic strength in the external solution and montmorillonite bulk dry densities in the bentonite. However, a model that considers clay microstructure changes as a function of bentonite compaction and ionic strength is necessary to reproduce observed trends in the data for all experimental conditions within a single model. Our predictive model excludes anions from the interlayer space and relates the interlayer porosity to the ionic strength and the montmorillonite bulk dry density. This presentation offers a good fit for measured anion accessible porosities in bentonites over a wide range of conditions and is also in agreement with microscopic observations.

  13. Experimental study of bentonite-soil mixtures as anti-seepage materials of constructed wetlands.

    PubMed

    Chen, Jing; Li, Zifu; Zhao, Xin; Li, Haihan

    2011-01-01

    In this study, mixtures of different kinds of bentonite and soil were used and tested in order to find a cheap alternative to current anti-seepage materials for constructed wetlands. The anti-seepage layer of constructed wetlands was simulated in the experimental study and the permeability coefficient of the mixed materials was determined in order to evaluate the anti-seepage effect of mixtures. The main results are as follows: (i) The minimum mass ratio of bentonite to soil is 10%; (ii) Within a certain range, the more compact and higher the wet density is, then the better anti-seepage effect is (under the condition of certain moisture content). The permeability coefficient of the mixed materials exponentially increased with the increase of wet density; (iii) At the wet density of 1.83 g/cm(3), corresponding with the optimum compactness, the mixture of natural sodium bentonite produced in Wyoming, USA and soil from Cangzhou, Hebei province showed the best anti-seepage performance; (iv) The impermeability of the mixture with smaller particle sizes of bentonite was far better than that with the bigger particle sizes; (v) The hydration effect of bentonite changed the structure of the mixture materials into a special structure that is similar to that of pure bentonite. The particles of the mixture became expanded under SEM investigation and the mixture became more compact, which could have the same or similar effect as pure bentonite for anti-seepage.

  14. Simultaneous sorption of crystal violet and 2-naphthol to bentonite with different CECs.

    PubMed

    Wei, Jingming; Zhu, Runliang; Zhu, Jianxi; Ge, Fei; Yuan, Peng; He, Hongping; Ming, Chen

    2009-07-15

    This work was to examine the feasibility and efficiency to use bentonite for simultaneous removal of cationic dyes and hydrophobic organic carbons (HOCs) from water. The sorption capacities of crystal violet (CV) on two bentonites and one activated carbon were compared. Simultaneous sorption of CV and 2-naphthol on the two bentonites were tested, and the removal efficiencies of 2-naphthol by the simultaneous sorption method and by CV modified bentonite was also compared. The experimental results in this study showed that the bentonite is more effective in sorption of CV than the activated carbon. With the sorption of CV, bentonite surfaces were altered from hydrophilicity to hydrophobicity, and thus 2-naphthol could be simultaneously removed. The aromatic effect between CV and 2-naphthol was supposed to be the primary driving force for the sorption of 2-naphthol. The simultaneous sorption method was shown to be more effective in the sorption of 2-naphthol than the CV modified bentonite. Results of this work could provide novel information for the treatment of wastewater containing both cationic dyes and HOCs.

  15. Production of modified bentonite via adsorbing lignocelluloses from spent liquor of NSSC process.

    PubMed

    Oveissi, Farshad; Fatehi, Pedram

    2014-12-01

    In this work, the adsorption of lignocelluloses from spent liquor (SL) of neutral sulfite semi chemical (NSSC) pulping process on bentonite was investigated. It was observed that 0.26g/g of lignin and 0.27g/g of hemicelluloses from SL were adsorbed on bentonite under the conditions of 50°C, 100rpm and 40g/gSL/bentonite after 3h of treatment. The adsorptions of lignin and hemicellulose were increased to 1.8g/g and 0.45g/g, respectively, via adding 15mg/g of polydiallyldimethylammonium chloride (PDADMAC) in the system of SL/bentonite. The turbidity and COD removals were improved from 69% to 93% and from 25% to 38% by adding PDADMAC to the SL/bentonite system, respectively. The increase in the heating value of bentonite (from 0 to 15.4MJ/kg) confirmed the adsorption of lignocelluloses. The modified bentonite can be used as filler in corrugated medium paper production or as fuel.

  16. Lead retention mechanisms and hydraulic conductivity studies of various bentonites for geoenvironment applications.

    PubMed

    Nakano, A; Li, L Y; Ohtsubo, M; Mishra, A K; Higashi, T

    2008-05-01

    Four bentonites from various sources were exposed to batch adsorption testing, selective sequential extraction and consolidation tests to investigate their metal retention capacity and hydraulic conductivity for geoenvironmental application such as in clay barrier materials. The Japanese bentonites (JB1-JB3) contain approximately 2-4% of carbonate and trace amount of zeolite (JB2 and JB3), whereas the US bentonite has < 1% carbonate and no zeolite. The rank of smectite content in the bentonites are USB > JB1 > JB3 > JB2. The materials ranked as JB2 approximately JB3 > JB1 > USB, according to retention capacity, while after the removal of carbonate the retention capacity order was JB1 approximately JB2 approximately JB3 > USB. SSE results indicate that carbonate plays a major role at low Pb solution concentration and precipitate as PbCO3. Once the carbonate is exhausted, the clay composition dominates the sorption process. The hydraulic conductivity of the bentonite mixtures (basalt + 10% bentonite) using water was kUSB < kJB1 < kJB3 < kJB2, consistent with the smectite content and swelling power, with USB having the highest proportion of smectite. Among the Japanese bentonites studied, JB1 is the best candidate for barrier material, comparable to the widely used USB.

  17. Use of cetyltrimethylammonium bromide-bentonite to remove organic contaminants of varying polar character from water

    SciTech Connect

    Zhu, L.; Ren, X.; Yu, S.

    1998-11-01

    Cetyltrimethylammonium bromide (CTMAB)-bentonite was produced by the exchange of cetyltrimethylammonium (CTMA) cations for inorganic ions on the internal and external surfaces of bentonite. CTMAB-bentonite was used to remove organic contaminants of varying polar character from water. The properties and mechanisms for CTMAB-bentonite to sorb benzene, toluene, ethylbenzene, nitrobenzene, aniline, phenol, and p-nitrophenol in water were investigated in some detail. Benzene, toluene, and ethylbenzene sorption to CTMAB-bentonite was characterized by linear isotherms, indicating solute partition between water and the organic phase composed of the large alkyl functional groups of the CTMA cations. Phenol and p-nitrophenol sorption to CTMAB-bentonite was caused primarily by adsorption with relatively strong solute uptake. Their isotherms were nonlinear. Nitrobenzene and aniline sorption to CTMAB-bentonite was weak, and the isotherms were approximately linear. Their sorption was caused by both partition and solute uptake. The sorption data were also evaluated in terms of the octanol-water partition coefficients of the organic compounds.

  18. Crude clove bud oil (CBO) quality improvement by bentonite adsorption process in flow system

    NASA Astrophysics Data System (ADS)

    Rubiyanto, Dwiarso; Diaty, Dita; Allwar

    2017-03-01

    Improvement of the quality of crude clove bud oil (crude CBO) by bentonite adsorption process in flow system had been done. This research aimed to improve the quality of crude CBO based on SNI 06-4267-1996 and SNI 06-2387-2006. The parameters were colours, densities, refractives index, eugenol and trans-caryophillene contents and also the additional analysis parameter which were the analysis of Fe using bentonite and measurement of pH using universal paper. Adsorption was carried out in the optimation of bentonite. The weight variations of bentonite was 5, 10, 15 and 20 grams. From the surface area analysis, it showed that bentonite had surface area about 30,512 m2/g which was activated chemically using 0,5 M HCl and calcinated using furnace in temperature of 400 0C. The results showed that the analysis of colours, densities, recfractives index and test of pH were not different significantly. Meanwhile the adsorption of Fe metal using 20 gram bentonite be able to adsorp until 94,20%. The highest percentage of eugenol found in the variation of 5 gram which was about 13,52% and decreased trans-caryophillene in 9,64% of 15 gram bentonite.

  19. Review of Suction Water Content Relationship of Bentonite-Sand Mixtures Considering Temperature Effects

    NASA Astrophysics Data System (ADS)

    Rawat, Abhishek; Zhi Lang, Lin; Baille, Wiebke

    2015-04-01

    Bentonite-sand mixture is one of the candidate sealing/ buffer material for landfills, hazardous and high level radioactive waste repository. The long term satisfactory performance of bentonite sand mixture in terms of load bearing function, sealing function and buffer function is governed by hydro-mechanical response of material under elevated temperature conditions. The suction-water content relationship is one of the key parameter, which govern the thermo-hydro-mechanical behavior of compacted bentonite-sand mixture. This paper presents brief review of suction water content relationships of bentonite-sand mixture considering temperature effects. Numerous parametric models or equations have been developed for representing the soil water characteristics curve i.e. SWCC for isothermal conditions. The most frequently used equations for representing the SWCC are the van Genuchten (1980) and Fredlund and Xing (1994) SWCC equations. Various researchers (Romero et al. 2000; Villar and Lloret, 2004; Tang and Cui, 2005; Agus, 2005; Arifin, 2008) have reported the temperature effect on the water retention behavior of compacted bentonite-sand mixtures. The testing program, results and major conclusions made by above mentioned researchers were discussed in this paper. The changes in hydro-mechanical behavior due to elevated temperature are also discussed based on the suction components of soil which are influenced by temperature. As a general conclusion, total suction of the bentonite-sand mixtures is a function of mixture water content and mixture bentonite content or collectively a function of bentonite water content both at room temperature and at elevated temperature. At a constant temperature, different techniques for measuring suction results in different values of suction depending on accuracy of the sensor and calibration technique used as founded earlier by Agus (2005). The change in total suction due to change in temperature lower than 100 degree C is reversible

  20. Interactions of corrosion products and bentonite: An extended multicomponent reactive transport model

    NASA Astrophysics Data System (ADS)

    Lu, Chuanhe; Samper, Javier; Fritz, Bertrand; Clement, Alain; Montenegro, Luis

    Radioactive waste disposal in deep geological repositories envisages various engineered barriers such as carbon-steel canisters and compacted bentonite. Canister corrosion and the chemical interactions of corrosion products with bentonite are key reactions for the long term performance of a repository. Samper, Lu, and Montenegro (Physics and Chemistry of the Earth 2008; 33S: S306-S316) reported numerical models to simulate canister corrosion and the interactions of corrosion products with bentonite for the near field of a repository in granite. Here we present an updated version of their reactive transport model which accounts for: (1) Three types of sorption sites in the bentonite; (2) Kinetically-controlled canister corrosion, (3) Kinetically-controlled magnetite precipitation; and (4) The competition effect of Ni 2+ for sorbing sites. Accounting for kinetically-controlled canister corrosion leads to a significant reduction in the corrosion rate. Uncertainties in the surface complexation reactions play a minor role in the time evolution of the computed pH in the bentonite and the granite. Computed iron concentrations, however, are very sensitive to changes in the surface complexation reactions. The apparent distribution coefficient of Fe computed with the three-site model is 10 times larger than that obtained with a single-site model. The concentration of dissolved Fe computed with kinetic magnetite precipitation is smaller than that obtained with magnetite precipitation at local equilibrium. The largest difference in the concentration of dissolved Fe occurs after 3 × 10 4 years. The competition of Ni 2+ for sorption sites affects significantly the chemical evolution of the bentonite porewater. The sorption of Ni 2+ on bentonite releases protons and therefore the pH in the bentonite is smaller than that computed without Ni 2+ transport. The sorption of Ni 2+ leads to a decrease of the concentration of sorbed Fe and an increase of the concentration of dissolved

  1. [Effect of SDS on the adsorption of Cd2+ onto amphoteric modified bentonites].

    PubMed

    Wang, Jian-Tao; Meng, Zhao-Fu; Yang, Ya-Ti; Yang, Shu-Ying; Li, Bin; Xu, Shao-e

    2014-07-01

    Under different modified ratios, temperatures, pH and ionic strengths, the effect of sodium dodecyl sulfonate (SDS) on the adsorption of Cd2+ onto bentonites which modified with amphoteric modifier dodecyl dimethyl betaine (BS-12) was studied by batch experiments, and the adsorption mechanism was also discussed. Results showed that the adsorption of Cd2+ on amphoteric bentonites can be enhanced significantly by SDS combined modification, Cd2+ adsorption decreases in the order: BS + 150SDS (BS-12 + 150% SDS) > BS + 100SDS (BS-12 + 100% SDS) > BS +50SDS(BS-12 + 50% SDS) > BS + 25SDS (BS-12 + 25% SDS) > BS (BS-12) > CK (unmodified soil). The adsorption isotherm can be described by the Langmuir equation. The change of temperature effect from positive on CK and amphoteric bentonites to negative on BS + 150SDS bentonites is observed with an increase of SDS modified ratio. The pH has little influence on Cd2+ adsorption on bentonites. The adsorption of Cd2+ on bentonites decreases with ionic strength rise, but the effect of ionic strength can be reduced with an increase of SDS modified ratio also. The adsorption thermodynamic parameters demonstrated that the adsorption of Cd2+ on modified bentonites was spontaneously controlled by entropy increment. When the SDS modified ratio is lower than 100% CEC, the adsorption of Cd2+ on modified bentonites is a process with characteristics of both enthalpy increment and entropy increment, while the SDS modified ratio is equal to or higher than 100% CEC, the adsorption of Cd2+ on modified bentonites becomes a process of enthalpy decrement and entropy increment.

  2. Coupled chemical and diffusion model for compacted bentonite

    SciTech Connect

    Olin, M.; Lehikoinen, J.; Muurinen, A.

    1995-12-31

    A chemical equilibrium model has been developed for ion-exchange and to a limited extent for other reactions, such as precipitation or dissolution of calcite or gypsum, in compacted bentonite water systems. The model was successfully applied to some bentonite experiments, especially as far as monovalent ions were concerned. The fitted log-binding constants for the exchange of sodium for potassium, magnesium, and calcium were 0.27, 1.50, and 2.10, respectively. In addition, a coupled chemical and diffusion model has been developed to take account of diffusion in pore water, surface diffusion and ion-exchange.d the model was applied to the same experiments as the chemical equilibrium model, and its validation was found partly successful. The above values for binding constants were used also in the coupled model. The apparent (both for anions and cations) and surface diffusion (only for cations) constants yielding the best agreement between calculated and experimental data were 3.0 {times} 10{sup {minus}11} m{sup 2}/s and 6.0 {times} 10{sup {minus}12} m{sup 2}/s, respectively. These values are questionable, however, as experimental results good enough for fitting are currently not available.

  3. Stability of kaolin sand from the Vyšný Petrovec deposit (south Slovakia) in an acid environment

    NASA Astrophysics Data System (ADS)

    Martin, Pentrák; Jana, Madejová; Slávka, Andrejkovičová; Peter, Uhlík; Peter, Komadel

    2012-12-01

    Comprehensive characterization of kaolin sand from the Vyšný Petrovec (VP) deposit in Slovakia by a variety of experimental methods was performed. The quantitative XRD analysis (RockJock software) revealed that the acid-untreated sample contained mainly kaolinite (~60 wt. %), a considerable amount of dioctahedral micas (~32 wt. %) and quartz (~ 7 wt. %). The Hinckley index (HI) and Aparicio-Galán-Ferrel index (AGFI) calculated from the 02l and 11l reflections showed medium-defect kaolinite to be present in the VP kaolin. The influence of the mineral composition of VP kaolin on its stability in 6 mol · dm-3 HCl at 95 °C was investigated. The solid reaction products were examined by chemical analysis; XRD and infrared spectroscopy in both middle (MIR) and near (NIR) regions. Considerably higher dissolution rate of Fe compared to Al indicated that Fe was bounded in a readily soluble phase rather than in kaolinite. While the MIR spectra confirmed the gradual release of the central atoms from the clay minerals layers and creation of amorphous silica upon acid treatment, the NIR spectra revealed the formation of Si-OH groups in the solid reaction product. Relatively high dissolution rate of VP kaolin resulted from the presence of small-grains of mediumdefect kaolinite and clay admixtures in VP kaolin sand.

  4. Effect of bentonite on radiation induced dissolution of UO2 in an aqueous system

    NASA Astrophysics Data System (ADS)

    Barreiro Fidalgo, Alexandre; Sundin, Sara; Jonsson, Mats

    2014-04-01

    In order to elucidate the impact of bentonite on the process of radiation induced oxidative dissolution of UO2 in an aqueous system, the dissolution of U(VI) and consumption of H2O2 over time has been studied. In addition, γ-irradiation experiments were performed to study a more relevant and complex system, serving as a comparison with the previously stated system. In both cases, the experiments revealed that the presence of bentonite in water could either delay or prevent in part the release of uranium to the environment. The cause is mainly attributed to the scavenging of radiolytic oxidants rather than to the adsorption of uranium onto bentonite.

  5. Effect of the addition of bentonite on the anaerobic biodegradability of solid fatty wastes.

    PubMed

    Mouneimne, A H; Carrère, H; Bernet, N; Delgenès, J P

    2004-04-01

    The biological degradation of solid fatty residues is limited by their low bioavailability. In this work, the effect of the day mineral bentonite on the degradation of hexane extractable matter and its conversion to volatile fatty acids was investigated. Our results showed that the best performance in the elimination of hexane extractable matter (73% +/- 2.5) and the production of volatile fatty acids (39% +/- 1.5) were observed in continuous experimental assays with a bentonite/greases ratio of 0.9. Isotherm studies showed that the sorption equilibria of oleate on bentonite and sludge could be described by the LANGMUIR model.

  6. The adsorption of caesium—137 on bentonites from the Carpathian basin

    NASA Astrophysics Data System (ADS)

    Nagy, N. M.; Kónya, J.; Földvári, M.; Kovács-Pálffy, P.

    2003-01-01

    The adsorption of cesium was studied on the surface of bentonite rocks from the Carpathian basin. The adsorbed quantity at carrier-free concentration was measured using 137Cs, the adsorption capacity of bentonites for cesium ions was determined by X-ray fluorescence analysis. The relation of the cesium adsorption and mineral composition as well as the structural modifications of crystal structure was studied by X-ray diffraction spectrometry and thermoanalysis. The results show that the adsorbed quantity of cesium primarily depends on the montmorillonite content of bentonites.

  7. A "liver" antigen associated with avian erythroblastosis: binding by bentonite and precipitation with sodium dodecyl sulphate.

    PubMed Central

    Darcel, C L

    1982-01-01

    The properties of a complement fixing antigen, EbAg, extracted from erythroblastosis-affected chicken livers are described. The antigen in extracts freed of structural protein is strongly bound by bentonite, but not by barium sulphate. Strongly alkaline solutions of sodium dodecyl sulphate are required to release the antigen from bentonite. Acidification of the detergent solution precipitates the active solution precipitates the active protein. Extraction of heme from the acidified detergent precipitate by methyl-ethyl ketone further purifies the antigen. This acid detergent treatment eliminates the need to use bentonite as a purification step. PMID:6280825

  8. Comparing Kaolin and Pinolene to Improve Sustainable Grapevine Production during Drought

    PubMed Central

    Belfiore, Nicola; Gaiotti, Federica; Lovat, Lorenzo; Sansone, Luigi; Poni, Stefano; Tomasi, Diego

    2016-01-01

    Viticulture is widely practiced in dry regions, where the grapevine is greatly exposed to water stress. Optimizing plant water use efficiency (WUE) without affecting crop yield, grape and wine quality is crucial to limiting use of water for irrigation and to significantly improving viticulture sustainability. This study examines the use in vineyards of particle film technology (engineered kaolin) and compares it to a film-forming antitranspirant (pinolene), traditionally used to limit leaf water loss, and to an untreated control. The trial was carried out under field conditions over three growing seasons, during which moderate to very severe plant water stress (down to -1.9 MPa) was measured through stem water potential. Leaf stomatal conductance (gs) and photosynthesis rate (An) were measured during the seasons and used to compute intrinsic WUE (WUEi, defined as An/gs ratio). Leaf temperature was also recorded and compared between treatments. Bunch quantity, bunch and berry weight, sugar accumulation, anthocyanin and flavonoid contents were measured. Finally, microvinifications were performed and resultant wines subjected to sensory evaluation.Results showed that the use of kaolin increased grapevine intrinsic WUE (+18% on average as compared to unsprayed vines) without affecting berry and bunch weight and quantity, or sugar level. Anthocyanin content increased (+35%) in kaolin treatment, and the wine was judged more attractive (p-value <0.05) and slightly more appreciated (p-value < 0.1) than control. Pinolene did not increase WUEi, limiting An more than gs; grapes with this treatment contained lower sugar and anthocyanin content than control, and the obtained wine was the least appreciated. This study demonstrates that particle film technology can improve vine WUEi and wine quality at the same time, while traditional antitranspirants were not as effective for these purposes. This positive effect can be used in interaction with other already-demonstrated uses of

  9. Shear Strength Correlations for Kaolin/Water Slurries: A Comparison of Recent Measurements with Historical Data

    SciTech Connect

    Burns, Carolyn A.; Gauglitz, Phillip A.; Russell, Renee L.

    2010-01-20

    This report documents testing funded by CH2M Hill Plateau Remediation and performed by Pacific Northwest National Laboratory (PNNL) in collaboration with Fauske and Associates, LLC (FAI) to determine the behavior of vessel spanning bubbles. The shear strengths of four samples of kaolin/water mixtures obtained by PNNL from FAI were measured and are reported here. The measured shear strengths of these samples were then used to determine how the Rassat correlation fit these new measurements or if a new correlation was needed. These results were then compared with previously reported data.

  10. Zn(II) adsorption from synthetic solution and kaolin wastewater onto vermicompost.

    PubMed

    Jordão, Cláudio Pereira; Fernandes, Raphael Bragança Alves; de Lima Ribeiro, Kamilla; de Souza Nascimento, Bruna; de Barros, Priscila Martins

    2009-03-15

    The adsorption of Zn(II) from both synthetic solution and kaolin industry wastewater by cattle manure vermicompost was studied. The adsorption process was dependent on the various operating variables, viz., solution pH, particle size of the vermicompost, mass of vermicompost/volume of the Zn(II) solution ratio, contact time and temperature. The optimum conditions for Zn adsorption were pH 6.0, particle size of < or = 250 microm, 1 g per 10 mL adsorbent dose, contact time of 4h and temperature of 25 degrees C. Langmuir and Freundlich adsorption isotherms fit well in the experimental data and their constants were evaluated, with R(2) values from 0.95 to 0.99. In synthetic solution, the maximum adsorption capacity of the vermicompost for Zn(2+) ions was 20.48 mg g(-1) at 25 degrees C when the vermicompost dose was 1 g 10 mL(-1) and the initial adjusted pH was 2. The batch adsorption studies of Zn(II) on vermicompost using kaolin wastewater have shown the maximum adsorption capacity was 2.49 mg g(-1) at pH 2 (natural pH of the wastewater). The small values of the constant related to the energy of adsorption (from 0.07 to 0.163 L mg(-1)) indicated that Zn(2+) ions were binded strongly to vermicompost. The values of the separation factor, R(L), which has been used to predict affinity between adsorbate and adsorbent were between 0 and 1, indicating that sorption was very favorable for Zn(II) in synthetic solution and kaolin wastewater. The thermodynamic parameter, the Gibbs free energy, was calculated for each system and the negative values obtained confirm that the adsorption processes are spontaneous. The DeltaG degrees values were -19.656 kJ mol(-1) and -16.849 kJ mol(-1) for Zn(II) adsorption on vermicompost in synthetic solution at pH 6 and 2, respectively, and -13.275 kJ mol(-1) in kaolin wastewater at pH 2.

  11. Fly ash/Kaolin based geopolymer green concretes and their mechanical properties

    PubMed Central

    Okoye, F.N.; Durgaprasad, J.; Singh, N.B.

    2015-01-01

    Geopolymer concrete mixes were cast using fly ash, kaolin, sodium hydroxide, potassium hydroxide, sodium silicate and aggregates. Portland cement concrete (M30) was used as a reference sample. The effect of silica fume, temperature (40 °C, 60 °C, 80 °C, 100 °C and 120 °C), sodium and potassium hydroxides and different superplasticizers on the compressive strength are reported [1]. Maximum strength was found at 100 °C and 14 M alkali solution [1]. PMID:26693505

  12. Fly ash/Kaolin based geopolymer green concretes and their mechanical properties.

    PubMed

    Okoye, F N; Durgaprasad, J; Singh, N B

    2015-12-01

    Geopolymer concrete mixes were cast using fly ash, kaolin, sodium hydroxide, potassium hydroxide, sodium silicate and aggregates. Portland cement concrete (M30) was used as a reference sample. The effect of silica fume, temperature (40 °C, 60 °C, 80 °C, 100 °C and 120 °C), sodium and potassium hydroxides and different superplasticizers on the compressive strength are reported [1]. Maximum strength was found at 100 °C and 14 M alkali solution [1].

  13. The efficacy of kaolin particle film on oil quality indices of olive trees (Olea europaea L.) cv 'Zard' grown under warm and semi-arid region of Iran.

    PubMed

    Khaleghi, Esmaeil; Arzani, Kazem; Moallemi, Norollah; Barzegar, Mohsen

    2015-01-01

    Kaolin particle film (0%, 3% and 6%; w/v), as an antitranspirant treatment, was applied to mature 'Zard' olive trees (Olea europaea L.). Olive oil was extracted from harvested fruit and fatty acid composition and other oil quality indices of the fruit assessed over crop seasons. Kaolin increased chlorophyll and carotenoid contents, but decreased peroxide and iodine values, and UV absorbance extinction coefficients, of the oil. The highest palmitic acid was observed in the oil obtained from untreated trees (17%). Kaolin increased oleic acid up to 65% and 64% in the first and second crop seasons, respectively, but decreased linoleic and linolenic acid contents. Monounsaturated acids (65%) and oleic acid/linoleic acid ratios (4) were higher in oil obtained from kaolin treated than untreated trees. Therefore it can be expected that extracted olive oil from kaolin treated trees has a higher oxidative stability and shelf life than untreated trees.

  14. Chemotherapy-induced kaolin intake is increased by lesion of the lateral parabrachial nucleus of the rat.

    PubMed

    Horn, Charles C; De Jonghe, Bart C; Matyas, Kathleen; Norgren, Ralph

    2009-11-01

    Anticancer agents, such as cisplatin, stimulate nausea, vomiting, and behaviors indicative of malaise. Rats and mice do not possess a vomiting response, and, therefore, in these species, the ingestion of kaolin clay (a pica response) has been used as an index of malaise. In the rat, cisplatin-induced kaolin intake is inhibited by antiemetic treatments. In addition, cisplatin activates vagal afferent fibers in the gut, and kaolin intake induced by cisplatin is largely dependent on an intact vagus. Nevertheless, little is known about the brain pathways controlling pica. We investigated the role of the lateral parabrachial nucleus (lPBN), a major visceral afferent link between the hindbrain and forebrain, in cisplatin-induced c-Fos expression and pica. Injection of cisplatin (6 mg/kg ip) produced c-Fos expression in the ventrolateral (external) lPBN, a region receiving viscerosensory input. In rats with bilateral ibotenic acid lPBN lesions, cisplatin treatment substantially increased kaolin intake compared with controls ( approximately 30 g vs. approximately 5 g, respectively, over 24 h). Food intake was reduced by cisplatin treatment and by apomorphine, an emetic agent that acts centrally. Unlike cisplatin, however, apomorphine stimulated kaolin intake to a similar degree in both the lesioned and control rats, suggesting that lPBN damage neither produces nonspecific effects nor enhances malaise in general. These data suggest that lPBN-lesioned animals not only demonstrate pica after cisplatin treatment, but, in fact, show an exaggerated response that is greatly in excess of any treatment known to produce kaolin intake in rats.

  15. Interaction of human adenoviruses and coliphages with kaolinite and bentonite.

    PubMed

    Bellou, Maria I; Syngouna, Vasiliki I; Tselepi, Maria A; Kokkinos, Petros A; Paparrodopoulos, Spyros C; Vantarakis, Apostolos; Chrysikopoulos, Constantinos V

    2015-06-01

    Human adenoviruses (hAdVs) are pathogenic viruses responsible for public health problems worldwide. They have also been used as viral indicators in environmental systems. Coliphages (e.g., MS2, ΦX174) have also been studied as indicators of viral pollution in fecally contaminated water. Our objective was to evaluate the distribution of three viral fecal indicators (hAdVs, MS2, and ΦΧ174), between two different phyllosilicate clays (kaolinite and bentonite) and the aqueous phase. A series of static and dynamic experiments were conducted under two different temperatures (4, 25°C) for a time period of seven days. HAdV adsorption was examined in DNase I reaction buffer (pH=7.6, and ionic strength (IS)=1.4mM), whereas coliphage adsorption in phosphate buffered saline solution (pH=7, IS=2mM). Moreover, the effect of IS on hAdV adsorption under static conditions was evaluated. The adsorption of hAdV was assessed by real-time PCR and its infectivity was tested by cultivation methods. The coliphages MS2 and ΦΧ174 were assayed by the double-layer overlay method. The experimental results have shown that coliphage adsorption onto both kaolinite and bentonite was higher for the dynamic than the static experiments; whereas hAdV adsorption was lower under dynamic conditions. The adsorption of hAdV increased with decreasing temperature, contrary to the results obtained for the coliphages. This study examines the combined effect of temperature, agitation, clay type, and IS on hAdV adsorption onto clays. The results provide useful new information on the effective removal of viral fecal indicators (MS2, ΦX174 and hAdV) from dilute aqueous solutions by adsorption onto kaolinite and bentonite. Factors enabling enteric viruses to penetrate soils, groundwater and travel long distances within aquifers are important public health issues. Because the observed adsorption behavior of surrogate coliphages MS2 and ΦΧ174 is substantially different to that of hAdV, neither MS2 nor

  16. Geochemistry of Telichian (Silurian) K-bentonites in Estonia and Latvia

    NASA Astrophysics Data System (ADS)

    Kiipli, T.; Soesoo, A.; Kallaste, T.; Kiipli, E.

    2008-03-01

    In the Telychian section of Estonia and Latvia K-bentonites from 45 volcanic eruptions were discovered. The thickness of K-bentonite interbeds varies from a few millimetres to 20 cm. The sodium component concentration in sanidine phenocrysts measured by XRD ranges from 20 to 48 mol% and was used for establishing correlations. The Ti, Zr, Nb, Th and Sr concentrations and ratios show temporal trends indicating fractional crystallization in magma chambers. The analysis of biotite phenocrysts revealed magnesium and iron rich biotites in bentonites. Synthesis of these geochemical data enabled a classification of bentonites into seven geochemical types, which probably originate from seven different volcanic sources. Isopach schemes indicate ash transport from the west and north-west directions.

  17. Pyronin Y (basic xanthene dye)-bentonite composite: A spectroscopic study

    NASA Astrophysics Data System (ADS)

    Tabak, A.; Kaya, M.; Yilmaz, N.; Meral, K.; Onganer, Y.; Caglar, B.; Sungur, O.

    2014-02-01

    The expansion by 1.43 Angstrom of basal spacing and the shift to higher frequencies of in-plane ring vibrations of the Pyronin Y molecule at 1603 and 1527 cm-1 on the formation of Pyronin Y-bentonite composite exhibited that the dye cations might be oriented as a monolayer form in the interlamellar spacing with aromatic rings parallel to clay layers. Thermal analysis results of this composite compared to those of raw bentonite signified the different outer sphere water entities associated with the replacement of inorganic cations with organic dye cations and the gradual decomposition of the organic molecule in the interlamellar spacing. Thermo-Infrared spectra of Pyronin Y-bentonite sample up to high temperatures showed the thermal stability of the dye-clay composite as a result of the presence of π interactions. The pore structure characteristics of Pyronin Y-bentonite composite exhibited the increase in the number of mesopores during formation of the composite.

  18. Use of rubber and bentonite added fly ash as a liner material.

    PubMed

    Cokca, Erdal; Yilmaz, Zeka

    2004-01-01

    In many countries regulations require all hazardous waste disposal facilities to be lined with suitable impermeable barriers to protect against contamination. In this study, a series of laboratory tests on rubber and bentonite added fly ash were conducted. The aim of the tests was to evaluate the feasibility of utilizing fly ash, rubber and bentonite as a low hydraulic conductivity liner material. Type C fly ash was obtained from Soma thermal power plant in Turkey; rubber in pulverized form was waste from the retreading industry. To investigate the properties of rubber and bentonite added fly ash, hydraulic conductivity, leachate analysis, unconfined compression, split tensile strength, one-dimensional consolidation, swell and freeze/thaw cycle tests were performed. The overall evaluation of results have revealed that rubber and bentonite added fly ash showed good promise and a candidate for construction of a liner.

  19. Features of the concentration dependences of the surface tension of water suspensions of bentonites

    NASA Astrophysics Data System (ADS)

    Dadashev, R. Kh.; Dzhambulatov, R. S.; Elimkhanov, D. Z.

    2015-08-01

    The concentration dependence of the surface tension of water suspensions of bentonites is studied experimentally. Possible reasons for the emergence of the minima on isotherms of the surface tensions of dispersed systems are analyzed.

  20. Use of rubber and bentonite added fly ash as a liner material

    SciTech Connect

    Cokca, Erdal; Yilmaz, Zeka

    2004-07-01

    In many countries regulations require all hazardous waste disposal facilities to be lined with suitable impermeable barriers to protect against contamination. In this study, a series of laboratory tests on rubber and bentonite added fly ash were conducted. The aim of the tests was to evaluate the feasibility of utilizing fly ash, rubber and bentonite as a low hydraulic conductivity liner material. Type C fly ash was obtained from Soma thermal power plant in Turkey; rubber in pulverized form was waste from the retreading industry. To investigate the properties of rubber and bentonite added fly ash, hydraulic conductivity, leachate analysis, unconfined compression, split tensile strength, one-dimensional consolidation, swell and freeze/thaw cycle tests were performed. The overall evaluation of results have revealed that rubber and bentonite added fly ash showed good promise and a candidate for construction of a liner.

  1. Experimental studies of the interactions between anaerobically corroding iron and bentonite

    NASA Astrophysics Data System (ADS)

    Carlson, Liisa; Karnland, Ola; Oversby, Virginia M.; Rance, Andy P.; Smart, Nick R.; Snellman, Margit; Vähänen, Marjut; Werme, Lars O.

    In the horizontal emplacement concept (KBS-3H) for the disposal of radioactive waste, which is being developed in Sweden and Finland, copper canisters will be surrounded by bentonite buffer and placed in perforated steel containers in long horizontal boreholes in the crystalline bedrock, at a depth of ≈500 m. Under the chemical conditions in a deep repository, it is possible that the release of iron from the steel containers could influence the physico-chemical properties of the bentonite, for example, by exchange of the interlayer ions. In order to gain further insights into this process, an experimental study was undertaken, to investigate the mode of iron uptake into bentonite and the extent of changes induced in the basic physico-chemical properties of bentonite. The samples were taken from long-term anaerobic corrosion tests of carbon steel or cast iron in compacted bentonite (Na/Ca-bentonite: Volclay MX-80, ∼4% Fe 2O 3) in contact with a simple artificial groundwater at 30 °C or 50 °C. A range of analytical techniques was applied to samples of corrosion product on carbon steel and cast iron and to the bentonite surrounding the corroding specimens. Corrosion products and bentonite samples were analysed using scanning electron microscopy (SEM), electron microprobe analysis (EPMA), Raman spectroscopy, X-ray diffraction (XRD) and Mössbauer transmission spectroscopy. In addition, the bentonite samples were analysed using Fourier transform infra-red spectroscopy (FTIR), transmission electron microscopy (TEM) with energy dispersive spectroscopy (EDS) and selected area electron diffraction (SAED), exchangeable cation analysis and cation exchange capacity (CEC) measurements. Hydraulic conductivity and swelling pressure were also measured. From visual observation, the corrosion product formed on the carbon steel in bentonite was less voluminous than that formed on steel in artificial porewaters with no bentonite, although previous work showed that the corrosion

  2. Effect of bentonite modification on hardness and mechanical properties of natural rubber nanocomposites

    NASA Astrophysics Data System (ADS)

    Santiago, Denise Ester O.; Pajarito, Bryan B.; Mangaccat, Winna Faye F.; Tigue, Maelyn Rose M.; Tipton, Monica T.

    2016-05-01

    The effect of sodium activation, ion-exchange with tertiary amine salt, surface treatment with non-ionic surfactant, and wet grinding of bentonite on hardness and mechanical properties of natural rubber nanocomposites (NRN) was studied using full factorial design of experiment. Results of X-ray diffraction (XRD) show increase in basal spacing d of bentonite due to modification, while attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) confirm the organic modification of bentonite. Analysis of variance (ANOVA) shows that the main effect of surface treatment increases the hardness and decreases the tensile modulus of the NRN. The surface treatment and wet grinding of bentonite decrease the tensile stresses at 100, 200 and 300% strain of NRN. Sodium activation and ion-exchange negatively affect the compressive properties, while surface treatment significantly improves the compressive properties of NRN.

  3. An optimum silica flour-bentonite mixture for an engineered barrier

    SciTech Connect

    Walker, J.N.; Daffern, D.D.; Emer, D.F.

    1991-01-01

    To dispose of low-level and mixed wastes (MAR) by burial, it is necessary to design an impermeable closure, which limits water infiltration through the waste. Bentonite has very low permeability to water but can be subject to volume alterations. Over time, these alterations can lead to channeling and subsequent permeability increases. The fluid conductivity and bulk properties of silica flour and bentonite mixtures were tested to find a mixture that would retain the low conductivity of the bentonite while maintaining volumetric stability. Silica flour was chosen for its small grain size and spherical shape, and its similarity to silty soil. Test results indicate that a 90% silica flour and 10% bentonite mixture will provide the optimum properties for this application. 5 refs., 2 figs., 2 tabs.

  4. Effect of the sintering temperature on the structural and magnetic parameters of strontium ferrites doped with kaolin and barium borate

    SciTech Connect

    Pashchenko, V.P.; Kostyagina, O.A.; Lisitsyn, S.M.; Prokopenko, A.K.; Selivanova, L.Y.; Serebro, D.Y.

    1986-01-01

    This paper presents the results of studies of the effect of the sintering temperature of strontium ferrites (doped with 1.2 mass % kaolin and barium borate) on their properties. The fine crystalline structure of anisotropic and demagnetized strontium ferrites doped with kaolin was studied with the help of the Moessbauer effect. Fe-57 nuclei, occupying 4f2 and 2a octahedral positions, respectively, in the hexagonal and spinel blocks, have the highest magnetic fields and quadrupole shifts. The effect of the sintering temperature on the physical properties of the ferrites studied is linked to changes in the microstructure and porosity of the samples.

  5. KAOLIN-INDUCED VENTRICULOMEGALY AT WEANING PRODUCES LONG-TERM LEARNING, MEMORY, AND MOTOR DEFICITS IN RATS

    PubMed Central

    Williams, Michael T.; Braun, Amanda A.; Amos-Kroohs, Robyn; McAllister, James P.; Lindquist, Diana M.; Mangano, Francesco T.; Vorhees, Charles V.; Yuan, Weihong

    2014-01-01

    Ventriculomegaly occurs when there is imbalance between creation and absorption of cerebrospinal fluid (CSF); even when treated, long-term behavioral changes occur. Kaolin injection in the cisterna magna of rats produces an obstruction of CSF outflow and models one type of hydrocephalus. Previous research with this model shows that neonatal onset has mixed effects on Morris water maze (MWM) and motoric performance; we hypothesized that this might be because the severity of ventricular enlargement was not taken into consideration. In the present experiment, rats were injected with kaolin or saline on postnatal day (P)21 and analyzed in subgroups based on Evan's ratios (ER) of the severity of ventricular enlargement at the end of testing to create 4 subgroups from least to most severe: ER0.4–0.5, ER0.51-0.6, ER0.61-0.7, and ER0.71-0.82, respectively. Locomotor activity (dry land and swimming), acoustic startle with prepulse inhibition (PPI), and MWM performance were tested starting on P28 (122 cm maze) and again on P42 (244 cm maze). Kaolin-treated animals weighed significantly less than controls at all times. Differences in locomotor activity were seen at P42 but not P28. On P28 there was an increase in PPI for all but the least severe kaolin-treated group, but no difference at P42 compared with controls. In the MWM at P28, all kaolin-treated groups had longer path lengths than controls, but comparable swim speeds. With the exception of the least severe group, probe trial performance was worse in the kaolin-treated animals. On P42, only the most severely affected kaolin-treated group showed deficits compared with control animals. This group showed no MWM learning and no memory for the platform position during probe trial testing. Swim speed was unaffected, indicating motor deficits were not responsible for impaired learning and memory. These findings indicate that kaolin-induced ventriculomegaly in rats interferes with cognition regardless of the final enlargement

  6. Elevated CSF outflow resistance associated with impaired lymphatic CSF absorption in a rat model of kaolin-induced communicating hydrocephalus

    PubMed Central

    2010-01-01

    Background We recently reported a lymphatic cerebrospinal fluid (CSF) absorption deficit in a kaolin model of communicating hydrocephalus in rats with ventricular expansion correlating negatively with the magnitude of the impediment to lymphatic function. However, it is possible that CSF drainage was not significantly altered if absorption at other sites compensated for the lymphatic defect. The purpose of this study was to investigate the impact of the lymphatic absorption deficit on global CSF absorption (CSF outflow resistance). Methods Kaolin was injected into the basal cisterns of Sprague Dawley rats. The development of hydrocephalus was assessed using magnetic resonance imaging (MRI). In one group of animals at about 3 weeks after injection, the movement of intraventricularly injected iodinated human serum albumin (125I-HSA) into the olfactory turbinates provided an estimate of CSF transport through the cribriform plate into nasal lymphatics (n = 18). Control animals received saline in place of kaolin (n = 10). In a second group at about 3.5 weeks after kaolin injection, intraventricular pressure was measured continuously during infusion of saline into the spinal subarachnoid space at various flow rates (n = 9). CSF outflow resistance was calculated as the slope of the steady-state pressure versus flow rate. Control animals for this group either received no injections (intact: n = 11) or received saline in place of kaolin (n = 8). Results Compared to saline injected controls, lateral ventricular volume in the kaolin group was significantly greater (0.087 ± 0.013 ml, n = 27 versus 0.015 ± 0.001 ml, n = 17) and lymphatic function was significantly less (2.14 ± 0.72% injected/g, n = 18 versus 6.38 ± 0.60% injected/g, n = 10). Additionally, the CSF outflow resistance was significantly greater in the kaolin group (0.46 ± 0.04 cm H2O.μL-1.min, n = 9) than in saline injected (0.28 ± 0.03 cm H2O.μL-1.min, n = 8) or intact animals (0.18 ± 0.03 cm H2O.μL-1

  7. Kaolin-induced ventriculomegaly at weaning produces long-term learning, memory, and motor deficits in rats.

    PubMed

    Williams, Michael T; Braun, Amanda A; Amos-Kroohs, Robyn M; McAllister, James P; Lindquist, Diana M; Mangano, Francesco T; Vorhees, Charles V; Yuan, Weihong

    2014-06-01

    Ventriculomegaly occurs when there is imbalance between creation and absorption of cerebrospinal fluid (CSF); even when treated, long-term behavioral changes occur. Kaolin injection in the cisterna magna of rats produces an obstruction of CSF outflow and models one type of hydrocephalus. Previous research with this model shows that neonatal onset has mixed effects on Morris water maze (MWM) and motoric performance; we hypothesized that this might be because the severity of ventricular enlargement was not taken into consideration. In the present experiment, rats were injected with kaolin or saline on postnatal day (P)21 and analyzed in subgroups based on Evan's ratios (ERs) of the severity of ventricular enlargement at the end of testing to create 4 subgroups from least to most severe: ER0.4-0.5, ER0.51-0.6, ER0.61-0.7, and ER0.71-0.82, respectively. Locomotor activity (dry land and swimming), acoustic startle with prepulse inhibition (PPI), and MWM performance were tested starting on P28 (122cm maze) and again on P42 (244cm maze). Kaolin-treated animals weighed significantly less than controls at all times. Differences in locomotor activity were seen at P42 but not P28. On P28 there was an increase in PPI for all but the least severe kaolin-treated group, but no difference at P42 compared with controls. In the MWM at P28, all kaolin-treated groups had longer path lengths than controls, but comparable swim speeds. With the exception of the least severe group, probe trial performance was worse in the kaolin-treated animals. On P42, only the most severely affected kaolin-treated group showed deficits compared with control animals. This group showed no MWM learning and no memory for the platform position during probe trial testing. Swim speed was unaffected, indicating motor deficits were not responsible for impaired learning and memory. These findings indicate that kaolin-induced ventriculomegaly in rats interferes with cognition regardless of the final enlargement of

  8. Hydraulic permeability of bentonite-polymer composites for application in landfill technology

    NASA Astrophysics Data System (ADS)

    Dehn, Hanna; Haase, Hanna; Schanz, Tom

    2015-04-01

    Bentonites are often used as barrier materials in landfill technology to prevent infiltration of leachates to the natural environment. Since decades, geoenvironmental engineering aims at improving the hydro-mechanical performance of landfill liners. Various studies on the permeability performance of geosynthetic clay liners (GCLs) show effects of non-standard liquids on behaviour of Na+-bentonite regarding its sealing capacity. With increasing concentration of chemical aggressive solutions the sealing capacity decreases (Shackelford et al. 2000). An opportunity to improve the hydraulic permeability of the bentonites is the addition of polymers. The changes in hydraulic permeability performance of polymer treated and untreated bentonites while adding chemical aggressive solutions were studied by several authors. Results obtained by Scalia et al. (2014) illustrate that an increase in permeability can be prevented by adding polymer to Na+-bentonite. On the other hand, Ashmawy et al. (2002) presented results on the incapability of several commercial bentonite-polymer-products. The objective of this study is to characterize the influence of polymer addition on hydraulic performance of Na+-bentonite systematically. Therefore, the influence of 1% polymer addition of cationic and anionic polyacrylamide on the swelling pressure and hydraulic permeability of MX 80 bentonite was investigated. Preparation of bentonite-polymer composites was conducted (1) in dry conditions and (2) using solution-intercalation method. Experiments on hydraulic permeability were carried out using distilled water as well as CaCl2-solution. References Ashmawy, A. K., El-Hajji, D., Sotelo, N. & Muhammad, N. (2002), `Hydraulic Performance of Untreated and Polymer-treated Bentonite in Inorganic Landfill Leachates', Clays and Clay Minerals 50(5), 546-552. Scalia, J., Benson, C., Bohnhoff, G., Edil, T. & Shackelford, C. (2014), 'Long-Term Hydraulic Conductivity of a Bentonite-Polymer Composite Permeated

  9. Controlled release of carbofuran from an alginate-bentonite formulation: water release kinetics and soil mobility.

    PubMed

    Fernández-Pérez, M; Villafranca-Sánchez, M; González-Pradas, E; Martinez-López, F; Flores-Céspedes, F

    2000-03-01

    The insecticide-nematicide carbofuran was incorporated in alginate-based granules to obtain controlled-release (CR) properties. The basic formulation [sodium alginate (1.61%)-carbofuran (0. 59%)-water] was modified by addition of sorbents. The effect on carbofuran release rate, caused by the incorporation of natural and acid-treated bentonite (0.5 and 1.0 M H(2)SO(4)) in alginate formulation, was studied by immersion of the granules in water under shaking. The time taken for 50% of the active ingredient to be released into water, t(50), was longer for those formulations containing natural bentonite (6.1 h) or acid-treated bentonite (9.0 and 11.7 h for 0.5 and 1.0 M H(2)SO(4) treatments, respectively) than for the preparation without bentonite (4.7 h). It appears from the results that the release of carbofuran from the various formulations is controlled by a diffusion mechanism according to the n values obtained, which were close to 0.5 in all cases. The mobility of carbofuran from alginate-based CR formulations was investigated by using soil columns packed with a clay soil (53% clay and 0.08% organic matter). Two alginate-based CR formulations containing natural bentonite or acid-treated bentonite (0.5 M H(2)SO(4)) were compared to technical grade carbofuran. The use of alginate-based CR formulations resulted in a reduction of the leached amount of carbofuran compared with the total amount of pesticide leached using the technical product (50 and 75% for CR granules containing natural and acid-treated bentonite, respectively). Alginate-bentonite CR formulations might be efficient systems for reducing carbofuran leaching in clay soils, which would reduce the risk of groundwater pollution.

  10. Thermodynamic modeling and sensitivity analysis of porewater chemistry in compacted bentonite

    NASA Astrophysics Data System (ADS)

    Ochs, Michael; Lothenbach, Barbara; Shibata, Masahiro; Yui, Mikazu

    Compacted bentonite is typically foreseen as the main component of the engineered barrier system of high-level radioactive waste repositories. To derive Kd values and diffusion coefficients of radionuclides for performance assessment, it is critical to be able to describe the chemistry of the pore solution and to understand how it is influenced by different factors. The present paper presents a sensitivity analysis on the influence of important parameters on porewater chemistry in compacted bentonite. The principal parameters varied were the fractions of calcite, gypsum, and NaCl dissolving from bentonite, and pCO 2: Model calculations were done with the help of a surface chemical thermodynamic model that simultaneously treats solution/mineral equilibria as well as surface complexation and ion exchange reactions at the edge and siloxane surfaces of clay minerals. Some calculations were extended to take into account electric double layer effects in the porespace. The model results show that two powerful pH buffer systems are operative in compacted bentonite: Amphoteric edge SOH sites and the carbonate buffer system. If pCO 2 is imposed externally, the resulting porewater pH is mainly controlled by the carbonate buffer. If bentonite is treated as a closed system, the buffering action of the SOH sites becomes more important. In both cases, the dissolution of calcite and gypsum from the bentonite is important. The dissolution of impurities and the ion exchange reactions have an important influence in compacted bentonite, and porewater composition is relatively independent of groundwater composition. If the development of an electric double layer in the bentonite pores is considered, our results indicate that at higher dry densities (⩾1200 kg/m 3) the entire porespace may be occupied with (truncated) diffuse layers, leaving no space for free porewater.

  11. Co-composting of acid waste bentonites and their effects on soil properties and crop biomass.

    PubMed

    Soda, Wannipa; Noble, Andrew D; Suzuki, Shinji; Simmons, Robert; Sindhusen, La-Ait; Bhuthorndharaj, Suwannee

    2006-01-01

    Acid waste bentonite is a byproduct from vegetable oil bleaching that is acidic (pH < 3.0) and hydrophobic. These materials are currently disposed of in landfills and could potentially have a negative impact on the effective function of microbes that are intolerant of acidic conditions. A study was undertaken using three different sources of acid waste bentonites, namely soybean oil bentonite (SB), palm oil bentonite (PB), and rice bran oil bentonite (RB). These materials were co-composted with rice husk, rice husk ash, and chicken litter to eliminate their acid reactivity and hydrophobic nature. The organic carbon (OC) content, pH, exchangeable cations, and cation exchange capacity (CEC) of the acid-activated bentonites increased significantly after the co-composting phase. In addition, the hydrophobic nature of these materials as measured using the water drop penetration time (WDPT) decreased from >10 800 s to 16 to 80 s after composting. Furthermore, these composted materials showed positive impacts on soil physical attributes including specific surface area, bulk density, and available water content for crop growth. Highly significant increases in maize biomass (Zea mays L.) production over two consecutive cropping cycles was observed in treatments receiving co-composted bentonite. The study clearly demonstrates the potential for converting an environmentally hazardous material into a high-quality soil conditioner using readily available agricultural byproducts. It is envisaged that the application of these composted acid waste bentonites to degraded soils will increase productivity and on-farm income, thus contributing toward food security and poverty alleviation.

  12. Potential protective effect of HSCAS and bentonite against dietary aflatoxicosis in rat: with special reference to chromosomal aberrations.

    PubMed

    Abdel-Wahhab, M A; Nada, S A; Farag, I M; Abbas, N F; Amra, H A

    1998-01-01

    Bentonite and hydrated sodium calcium aluminsilicate (HSCAS) were added at a level of 0.5% (w/w) to the diets containing 2.5 mg aflatoxins (AF) per kg diet and fed to male mature rats for 15 successive days. Aflatoxin alone significantly decreased feed intake and altered serum biochemical parameters of liver and kidney functions. Aflatoxin caused chromosomal aberrations in bone marrow cells. Bentonite or HSCAS did not alter any of the parameters measured. The addition of bentonite or HSCAS to the AF-contaminated diet diminished most of the deleterious effects of the aflatoxin. Pathological examinations of liver and kidney proved that both bentonite and HSCAS were hepatonephroprotective agents against aflatoxicosis. The cytogenetic findings demonstrated that the addition of bentonite or HSCAS to AF-contaminated diet suppressed chromosomal aberrations. These findings indicated that bentonite and HSCAS could diminished many of the adverse effect of dietary AF in rats.

  13. Equilibrium, FTIR, scanning electron microscopy and small wide angle X-ray scattering studies of chromates adsorption on modified bentonite

    NASA Astrophysics Data System (ADS)

    Majdan, Marek; Maryuk, Oksana; Pikus, Stanisław; Olszewska, Elzbieta; Kwiatkowski, Ryszard; Skrzypek, Henryk

    2005-04-01

    The study presents a discussion about the adsorption mechanism of chromate anions on bentonite modified by hexadecyltrimethylammonium bromide (HDTMA-Br). The formation of alkylammonium chromates: HDTMAHCrO 4, (HDTMA) 2Cr 2O 7 and to the lesser extent (HDTMA) 2CrO 4 at the water-bentonite interface is examined based on the Scanning Electron Microscopy and surface tension measurements. The histograms of HDTMA/Cr(VI) molar ratio on the bentonite surface, found from Scanning Electron Microscopy (SEM) measurements, show that for the majority of points of bentonite surface the value of this ratio is in 1-2 range. FTIR spectra of modified bentonite samples show the change from gauche to trans conformation in the surfactant arrangement in the clay interlayer accompanying its concentration increase. In turn Small Wide Angle X-Ray Scattering (SWAXS) patterns evidently suggest incorporation of chromate anions into the interlamellar space of bentonite structure.

  14. CO2 capture using zeolite 13X prepared from bentonite

    NASA Astrophysics Data System (ADS)

    Chen, Chao; Park, Dong-Wha; Ahn, Wha-Seung

    2014-02-01

    Zeolite 13X was prepared using bentonite as the raw material by alkaline fusion followed by a hydrothermal treatment without adding any extra silica or alumina sources. The prepared zeolite 13X was characterized by X-ray powder diffraction, N2-adsorption-desorption measurements, and scanning electron microscopy. The CO2 capture performance of the prepared zeolite 13X was examined under both static and flow conditions. The prepared zeolite 13X showed a high BET surface area of 688 m2/g with a high micropore volume (0.30 cm3/g), and exhibited high CO2 capture capacity (211 mg/g) and selectivity to N2 (CO2/N2 = 37) at 25 °C and 1 bar. In addition, the material showed fast adsorption kinetics, and stable CO2 adsorption-desorption recycling performance at both 25 and 200 °C.

  15. Surface modification of a low cost bentonite for post-combustion CO2 capture

    NASA Astrophysics Data System (ADS)

    Chen, Chao; Park, Dong-Wha; Ahn, Wha-Seung

    2013-10-01

    A low cost bentonite was modified with PEI (polyethylenimine) through a physical impregnation method. Bentonite in its natural state and after amine modification were characterized by scanning electron microscopy-energy dispersive X-ray spectroscopy, X-ray diffraction, N2 adsorption-desorption isotherms, and investigated for CO2 capture using a thermogravimetric analysis unit connected to a flow panel. The effect of adsorption temperature, PEI loading and CO2 partial pressure on the CO2 capture performance of the PEI-modified bentonite was examined. A cyclic CO2 adsorption-desorption test was also carried out to assess the stability of PEI-modified bentonite as a CO2 adsorbent. Bentonite in its natural state showed negligible CO2 uptake. After amine modification, the CO2 uptake increased significantly due to CO2 capture by amine species introduced via chemisorption. The PEI-modified bentonites showed high CO2 capture selectivity over N2, and exhibited excellent stability in cyclic CO2 adsorption-desorption runs.

  16. [Emergent retention of organic liquid by modified bentonites: property and mechanism].

    PubMed

    Li, Yu; Liu, Xian-Jun; Zhang, Xing-Wang; Lei, Le-Cheng

    2012-03-01

    In this study, the property and mechanism of modified bentonites synthesized by long chain quaternary ammonium compounds which would be used in the emergent retention of typical organic liquid (benzene, chlorobenzene, nitrobenzene and diesel) were investigated and a pilot-scale simulation experiment was conducted. The unit retention capacity of modified bentonites for organic liquid (2.83-9.01 g x g(-1)) was much higher than that of conventional retention agents (0.28-1.17 g x g(-1)). The property and amount of the surfactants used and viscosity of organic liquid had a significant influence on the retention capacity of modified bentonites for the organic liquid, for example, the bentonites modified by cetyltrimethylammonium (CTMAB) with an adding quantity of 100% CEC showed the highest efficiency in the retention of organic liquid. In the simulation experiment, organic liquid could be retained effectively within 30 min by emergent retention device with modified bentonites and the retention efficiency might reach positively up to 90%. Results indicated that modifications using surfactants could enhance the hydrophobicity and interlayer space of the modified bentonites and make their retention capacities for organic liquid improved.

  17. Occurrence and significance of Silurian K-bentonite beds at Arisaig, Nova Scotia, eastern Canada

    USGS Publications Warehouse

    Bergstrom, Stig M.; Huff, W.D.; Kolata, Dennis R.; Melchin, Michael J.

    1997-01-01

    The most extensive succession of K-bentonite beds known in the Silurian of North America occurs at Arisaig on the northern coast of Nova Scotia. At least 40 ash beds are present in the Llandoverian Ross Brook Formation and at least four in the early Ludlovian McAdam Brook Formation. Most of the beds are thin (<5 cm), but one bed (the Smith Brook K-bentonite bed) in the late Llandoverian crenulata Zone and another (the McAdam Brook K-bentonite bed) in the early Ludlovian nilssoni Zone each reach a thickness of 20 cm. New graptolite collections provide critical information on the biostratigraphic position of the K-bentonite beds in the Ross Brook Formation. Geochemical data show that the Arisaig ash beds represent calc-alkaline magmas from plate margin, subduction-related volcanic vents. Differences in K-bentonite stratigraphie distribution, combined with paleogeographic considerations, suggest that the volcanoes were located much farther to the south in the Iapetus than the source volcanoes of the British - Baltoscandian Llandoverian K-bentonites.

  18. The Use of Modified Bentonite for Removal of Aromatic Organics from Contaminated Soil.

    PubMed

    Gitipour; Bowers; Bodocsi

    1997-12-15

    This study investigates the clay-aromatic interactions with a view to the use of bentonite clay for binding benzene, toluene, ethylbenzene, and o-xylene (BTEX compounds) in contaminated soils. BTEX compounds are the most toxic aromatic constituents of gasoline present in many underground storage tanks. Modified (organophilic) and ordinary bentonites are used to remove these organics. The organophilic bentonites are prepared by replacing the exchangeable inorganic cations present in bentonite particles with a quaternary ammonium salt. Various clay-to-soil ratios were applied to determine the efficiency of the modified bentonite in enhancing the cement-based solidification/stabilization (S/S) of BTEX contaminated soils. Toxicity characteristics leaching procedure (TCLP) tests were performed on soil samples to evaluate the leaching of the organics. In addition, X-ray diffraction analyses were conducted to assess the changes in the basal spacing of the clays as a result of their interaction with BTEX compounds. The findings of this study reveal that organophilic bentonite can act as a successful adsorbent for removing the aromatic organics from contaminated soil. Thus, this material is viable for enhancing the performance of cement-based S/S processes, as an adsorbent for petroleum spills, and for landfill liners and slurry walls. Copyright 1997 Academic Press.

  19. Study of combined effect of proteins and bentonite fining on the wine aroma loss.

    PubMed

    Vincenzi, Simone; Panighel, Annarita; Gazzola, Diana; Flamini, Riccardo; Curioni, Andrea

    2015-03-04

    The wine aroma loss as a consequence of treatments with bentonite is due to the occurrence of multiple interaction mechanisms. In addition to a direct effect of bentonite, the removal of aroma compounds bound to protein components adsorbed by the clay has been hypothesized but never demonstrated. We studied the effect of bentonite addition on total wine aroma compounds (extracted from Moscato wine) in a model solution in the absence and presence of total and purified (thaumatin-like proteins and chitinase) wine proteins. The results showed that in general bentonite alone has a low effect on the loss of terpenes but removed ethyl esters and fatty acids. The presence of wine proteins in the solution treated with bentonite tended to increase the loss of esters with the longest carbon chains (from ethyl octanoate to ethyl decanoate), and this was significant when the purified proteins were used. The results here reported suggest that hydrophobicity can be one of the driving forces involved in the interaction of aromas with both bentonite and proteins.

  20. Anti-fouling effect of bentonite suspension in ultrafiltration of oil/water emulsion.

    PubMed

    Panpanit, S; Visvanathan, C; Muttamara, S

    2002-03-01

    The effect on membrane fouling resistance during ultrafilration of oil/water emulsion with the presence of bentonite suspension is experimentally evaluated. The fouling resistance was analyzed as a function of different membrane types and bentonite concentration. The total membrane fouling was categorized into reversible and irreversible, by adopting an appropriate chemical cleaning technique. The results revealed a 40% flux augmentation with the increase of bentonite concentration up to an optimum value of 300 mg l(-1) for cellulose acetate membrane. Further increase of bentonite concentration led to particle deposition on the membrane surface and reduced the flux. The polysulfone membrane did not show a similar flux improvement. This could be due to its high hydrophobicity. The absorption of oil/water emulsion on bentonite increased TOC removal rate from 65% to 80%, and this effect was the major cause of reduction in gel layer formation on the membrane surface. The extent of irreversible fouling of the hydrophilic cellulose acetate membrane was much smaller than that of the polysulfone membrane. These experiments demonstrated that, presence of bentonite could induce transformation of irreversible fouling caused by oil emulsion to reversible fouling, which could be periodically chemically cleaned.

  1. Sodium bentonite and monensin under chronic aflatoxicosis in broiler chickens.

    PubMed

    Magnoli, A P; Texeira, M; Rosa, C A R; Miazzo, R D; Cavaglieri, L R; Magnoli, C E; Dalcero, A M; Chiacchiera, S M

    2011-02-01

    Clay feed additives have been increasingly incorporated into animal diets to prevent aflatoxicosis. Due to the nonselective nature of the binding interaction, many important components of the diets could also be made unavailable because of these feed additives. The anticoccidial monensin (MON) could also be sequestered by these clays. The use of sodium bentonite (Na-B) from a mine in the province of Mendoza, Argentina, was investigated as a sequestering agent to prevent the effects of 100 µg/kg of dietary aflatoxin B(1) (AFB(1)). In vitro studies demonstrated that the above Na-B was a good candidate to prevent aflatoxicosis. They also showed that MON competes with AFB(1) for the adsorption sites on the clay surface and effectively displaces the toxin when it is in low concentration. Even though the levels of MON in diets, approximately 55 mg/kg, are high enough to not be significantly changed as a consequence of the adsorption, they can further affect the ability of the clays to bind low levels of AFB(1). An in vivo experiment carried out with poultry showed that 100 µg/kg of AFB(1) does not significantly change productive or biochemical parameters. However, liver histopathology not only confirmed the ability of this particular Na-B to prevent aflatoxicosis but also the decrease of this capacity in the presence of 55 mg/kg of MON. This is the first report stressing this fact and further research should be performed to check if this behavior is a characteristic of the assayed Na-B or of this type of clay. On the other hand, the presence of MON should also be taken into account when assaying the potential AFB(1) binding ability of a given bentonite.

  2. Contributions of polymers to bentonite and saponite fluids

    SciTech Connect

    Guven, N.; Carney, L.L.; Panfil, D.J. . Dept. of Geosciences)

    1991-02-01

    Polymers have been used in drilling fluids for many years. However, the confusion surrounding the use of polymers in the oil field has severely limited their effectiveness. Many oilfield workers simply put all polymers in the same category without regard to the many differences that exist among them. Homopolymers and copolymers of acrylic acid and a copolymer of styrene and maleic anhydride are found to have profound effects on the rheological and filtration properties of clay-based fluids up to 300{degrees}F. These contributions of the polymers are greatly diminished when the clay/polymer fluids were autoclaved at 400{degrees}F. Thus, the effects of these polymers are expected to be negligible at and above 400{degrees}F. Homo- and co-polymers of acrylic acid with molecular weights below 5000 almost eliminate the anomalous viscosity rise of the bentonite fluids at temperatures between 250--450{degrees}F. A homopolymer of acrylic acid with a molecular weight of 60,000 and a co-polymer of styrene and maleic anhydride with very high molecular weight further enhances the anomalous viscosity rise of the bentonite fluid. The original viscosity profile of the saponite fluid is characterized with a high initial viscosity up to 200{degrees}F which is followed by a steep thinning at higher temperatures. The addition of homo- and co-polymer of acrylic acid causes a complete reversal in the fluid viscosity. They become thin at lower temperatures (up to 250{degrees}F) and experience a sudden viscosity rise at higher temperatures. All the above polymers greatly improve the filtration losses of the fluids at room temperatures as indicated by the API test. The filtration tests at high pressure and high temperatures were inconclusive due to the frequent blow-outs that occur during the tests.

  3. Numerical simulation of cesium and strontium migration through sodium bentonite altered by cation exchange with groundwater components

    SciTech Connect

    Jacobsen, J.S.; Carnahan, C.L.

    1988-10-01

    Numerical simulations have been used to investigate how spatial and temporal changes in the ion exchange properties of bentonite affect the migration of cationic fission products from high-level waste. Simulations in which fission products compete for exchange sites with ions present in groundwater diffusing into the bentonite are compared to simulations in which the exchange properties of bentonite are constant. 12 refs., 3 figs., 2 tabs.

  4. Attenuation measurements of ultrasound in a kaolin-water slurry. A linear dependence upon frequency

    SciTech Connect

    Greenwood, M.S.; Mai, J.L.; Good, M.S. )

    1993-08-01

    The attenuation of ultrasound through a kaolin-water slurry was measured for frequencies ranging from 0.5 to 3.0 MHz. The maximum concentration of the slurry was for a weight percentage of 44% (or a volume fraction of 0.24). The goal of these measurements was to assess the feasibility of using ultrasonic attenuation to determine the concentration of a slurry of known composition. The measurements were obtained by consecutively adding kaolin to the slurry and measuring the attenuation at each concentration. After reaching a maximum concentration a dilution technique was used, in which an amount of slurry was removed and water was added, to obtain the attenuation as a function of the concentration. The dilution technique was the more effective method to obtain calibration data. These measurements were carried out using two transducers, having a center frequency of 2.25 MHz, separated by 0.1016m (4.0 in.). The maximum attenuation measured in these experiments was about 100Np/m, but the experimental apparatus has the capability of measuring a larger attenuation if the distance between the two transducers is decreased. For a given frequency, the data show that ln V/V[sub 0] depends linearly upon the volume fraction (V is the received voltage for the slurry and V[sub 0] is that obtained for water). This indicated that each particle acts independently in attenuating ultrasound. 12 refs., 7 figs., 3 tabs.

  5. Application of zeolite prepared from Egyptian kaolin for the removal of heavy metals: II. Isotherm models.

    PubMed

    Ibrahim, Hanan S; Jamil, Tarek S; Hegazy, Eman Z

    2010-10-15

    In this study, the adsorption behavior of zeolites A and X, which are prepared from very cheap local Egyptian clay (kaolin), with respect to Cu(2+), Cd(+2), Cr(+2), Ni(+2) and Zn(2+) has been studied. The batch method has been employed, using metal solutions ranging from 100 to 400 mg/L. The distribution coefficients (K(d)) and adsorption percent were determined for the adsorption system as a function of sorbate concentration. In the uptake evaluation part of the study, adsorption ratios of metal cations on zeolites A and X match to Langmuir, Freundlich, and Dubinin-Kaganer-Radushkevich (DKR) adsorption isotherm data. Also, every cation exchange capacity for metals has been calculated. According to the equilibrium studies, the selectivity sequence can be given as Pb(2+)>Cd(2+)>Cu(2+)>Zn(2+)>Ni(2+). It was found that the uptake depend on hydrated ion diameter. This study may attract more interest due to the presence of large reservoirs of very cheap kaolin in Egypt from which both zeolite types were prepared.

  6. The kinetics of Al-Si spinel phase crystallization from calcined kaolin

    SciTech Connect

    Ptacek, Petr

    2010-11-15

    The crystallization of Al-Si spinel from medium ordered kaolin with high content of kaolinite was investigated using the differential thermal analysis (DTA). The apparent activation energy of the process was evaluated from the dependence of exothermic peak of crystallization on heating rate. Within the applied interval of heating rate (1-40 K min{sup -1}) the temperature of peak maximum increases from initial value of 1220.5 K in about 54.2 K. The apparent activation energy of the process 856{+-}2 kJ mol{sup -1}was calculated using the Kissinger equation. The growth morphology of Al-Si spinel crystal was evaluated from the Avrami parameter. The average value of morphology parameter determined within the observed interval of heating rate is 3.08{+-}0.03. This value indicates that crystallization mechanism of Al-Si spinel phase proceeds by bulk nucleation of the new phase with constant number of nuclei and that the three-dimensional growth of crystals is controlled by the reaction rate on the phases interface. - Graphical abstract: Kinetics of crystallization of Al-Si spinel from calcined kaolin was investigated by the DTA using the Kissinger kinetic approach. The apparent activation energy and morphology parameter of the process is 856{+-}2 kJ mol{sup -1} and 3.08{+-}0.03, respectively.

  7. The use of electrokinetics, EDTA, and flushing solutions in the removal of lead from Kaolin clay

    SciTech Connect

    Coletta, T.F.; Bruell, C.J.; Ryan, D.K.

    1995-12-31

    The use of electrokinets in conjunction with anodic and complexant-bearing cathodic flushing solutions was studied to determine its efficiency in removing lead from clay. Experiments were conducted in a horizontal soil column apparatus with Kaolin clay. Anodic flushing solutions were prepared by mixing water and clay in rations ranging from 2:1 to 40:1 by weight. To decrease the pH (and therefore lead buildup) at the cathode, the cathode was flush with an EDTA solution. A total organic carbon analysis was performed to determine if the EDTA was migrating back into the clay column. Results showed that lead removal efficiency increased with an increasing water to clay ratio to an optimum ratio of 7:1. In addition, increasing the time of cathode flushing to four days with EDTA at pH 4 increased lead removal at the cathode end. Lead removal at the cathode is higher than in columns flushed with sodium chloride and ionic solutions. Flushing the cathode for 10 days resulted in decreased overall lead removal efficiency. This is possibly due to precipitation of EDTA at the low final pH distribution. EDTA does migrate back into the column, and high concentrations are associated with significant lead removal at the cathode end. It appears that the optimization of the elemental constituents of the anodic flushing solution in conjunction with the proper conditioning of the cathode with complexants enhances lead removal from Kaolin clay.

  8. Physical Properties of Kaolin/Sand Slurry Used During Submersible Mixer Pump Tests at TNX

    SciTech Connect

    HANSEN, ERICHK.

    2004-08-18

    The purpose of this task is to characterize the physical properties of kaolin/sand slurry used to test the performance of a new submersible mixer pump which is undergoing performance testing at the TNT Waste Tank mockup facility. Three different sample locations, the SMP cooling water exit, the SMP fluid flow field, and SMP effective cleaning radius were used for sampling over the seven day test. The physical properties determinations for the kaolin/sand slurry samples include rheology, weight percent total solids (wt TS), density, and particle size distribution were requested, though not all these determinations were performed on all the samples. The physical properties determinations are described in more detail in section 1.0. Measurements were performed at Savannah River National Laboratory in accordance with the Technical Assistance Request (TAR)1. The data, average of two measurements, is shown in the table below. This data clearly shows that the SMP-CWE samples contained more so lids than those at other sample locations for a given sample day. The SMP-FFF and SMP-ECR were similar in solids content. The rheology of the samples is dependent on the wt solids concentration and are all within the bounds stated in the TAR.

  9. Synthesis and characterization of mangan oxide coated sand from Capkala kaolin

    NASA Astrophysics Data System (ADS)

    Destiarti, Lia; Wahyuni, Nelly; Prawatya, Yopa Eka; Sasri, Risya

    2017-03-01

    Synthesis and characterization of mangan oxide coated sand from quartz sand fraction of Capkala kaolin has been conducted. There were two methods on synthesis of Mangan Oxide Coated Sand (MOCS) from Capkala Kaolin compared in this research. Characterization of MOCS was done by using Scanning Electron Microscope/Energy Dispersive X-Ray Spectrometer (SEM/EDX) and X-Ray Diffraction (XRD). The MOCS was tested to reduce phosphate in laundry waste. The result showed that the natural sand had bigger agregates and a relatively uniform structural orientation while both MOCS had heterogen structural orientation and manganese oxide formed in cluster. Manganese in first and second methods were 1,93% and 2,63%, respectively. The XRD spectrum showed clear reflections at 22,80°, 36,04°, 37,60° and a broad band at 26,62° (SiO2). Based on XRD spectrum, it can be concluded that mineral constituents of MOCS was verified corresponding to pyrolusite (MnO2). The former MOCS could reduce almost 60% while the later could reduce 70% phosphate in laundry waste.

  10. Potential of kaolin-based particle film barriers for Formosan subterranean termite (Isoptera: Rhinotermitidae) control

    USGS Publications Warehouse

    Wiltz, B.A.; Woodson, W.D.; Puterka, G.J.

    2010-01-01

    Effects of three particle film products on Formosan subterranean termites, Coptotermes formosanus Shiraki, were evaluated in feeding, tunneling, and contact assays. The particle films, hydrophobic M96-018 and hydrophilic Surround and Surround WP are based on the inert clay mineral kaolin. In 2-week long no-choice feeding tests, significant mortality occurred only with M96-018-coated wood. When a choice was provided, M96-018 and Surround were consumed at higher rates than untreated wood. Surround WP did not differ from controls in either test. In the tunneling assay termites were given the option of crossing a kaolin-sand mixture to reach an alternate food source. After 3-weeks, rates of 1% and 5% M96-018 provided an effective barrier to Formosan termite tunneling, while termites were not stopped by rates as high as 20% Surround and Surround WP. Dust treatments of all three formulations caused significant increases in mortality within 24 h, with mortality rates ranging from 72.0 - 97.3% within 72 h of treatment. The particle films were most effective when moisture levels were low, suggesting that desiccation was the mechanism for mortality. All particle films showed potential for use in above ground applications while hydrophobic M06-018 has the most potential as a soil barrier to subterranean termites.

  11. Beneficiation of a commercial kaolin from Mar de Espanha, Minas Gerais, Brazil: Chemistry and mineralogy

    NASA Astrophysics Data System (ADS)

    Pinheiro, P. G.; Fabris, J. D.; Mussel, W. N.; Murad, E.; Scorzelli, R. B.; Garg, V. K.

    2005-12-01

    Raw materials used to produce a commercial kaolin from Minas Gerais, Brazil, and the intermediate and final products after processing were studied to trace the fate of iron during industrial beneficiation. X-ray diffraction shows kaolinite to be the principal phyllosilicate in all samples. Sample treatments include size fractionation and a chemical treatment with sodium bisulfate, metallic zinc, and sulfuric acid, which remove all associated goethite and most hematite but do not significantly affect structural iron in the phyllosilicates. Scanning electron micrographs show that individual kaolinite grains are approximately 0.3 μm in size and have an almost hexagonal morphology in a compact arrangement. Tubular halloysite was also occasionally observed. Mössbauer spectra measured at 298° and 100 K evince the presence of hematite and paramagnetic trivalent iron in all samples, whereas goethite, which is abundant in raw and intermediate samples, is absent in the final kaolin. The industrial processing removes almost two-thirds of the total iron content (essentially iron oxides) of the raw material during size fractionation, so the intermediate sample contains 0.42% Fe 3+. The final marketable material contains 0.12% Fe 3+ in hematite (0.07%) and phyllosilicates (0.05%), rendering it suitable as paper filler.

  12. Experimental assessment of non-treated bentonite as the buffer material of a radioactive waste repository.

    PubMed

    Choi, J; Kang, C H; Whang, J

    2001-05-01

    The bentonite-based material being evaluated in several countries as potential barriers and seals for a nuclear waste disposal system is of mostly sodium type, whereas most bentonite available in Korea is known to be of calcium type. In order to investigate whether local Korean bentonite could be useful as a buffer or sealing material in an HLW repository system, raw bentonites sampled from the south-east area of Korea were examined in terms of their physicochemical properties such as surface area, CEC, swelling rate, and distribution coefficient. The diffusion behavior of some radionuclides of interest in compacted bentonite was also investigated. Considering that HLW generates decay heat over a long time, the thermal effect on the physicochemical properties of bentonite was also included. Four local samples were identified as Ca-bentonite through XRD and chemical analysis. Of the measured values of surface area, CEC and swelling rate of the local samples, Sample-A was found to have the greatest properties as the most likely candidate barrier material. The distribution coefficients of Cs-137, Sr-85, Co-60 and Am-241 for Sample-A sample were measured by the batch method. Sorption equilibrium was reached in around 8 to 10 days, but that of Sr was found to be reached earlier. Comparing the results of this study with the reference data, domestic bentonite was found to have a relatively high sorption ability. For the effect of varying concentration on sorption, the values of Kd peaked at 10(-9)-10(-7) mol/l of radionuclide concentration. In XRD analysis, the (001) peak of Sample-A was fully collapsed above 200 degrees C. The shoulder appearing at about 150 degrees C in the DSC curve was found to be evidence that Sample-A is predominated by Ca-montmorillonite. The loss of swelling capacity and CEC of Sample-A started at about 100 degrees C. The swelling data and the (001) peak intensity of the heat-treated sample showed that they were linearly interrelated. The measured

  13. Kaolin-based foliar reflectant and water deficit influence Malbec leaf and berry temperature, pigments, and photosynthesis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effects of a kaolin-based foliar reflectant on traits of commercial interest in the red-skinned wine grape cultivar Malbec (Vitis vinifera L.) were evaluated over three growing seasons by measuring the surface temperatures of leaves and clusters, leaf-level assimilation, leaf and berry pigment c...

  14. Reduction in toxicity of arsenic(III) to Halobacillus sp. Y35 by kaolin and their related adsorption studies.

    PubMed

    Zhou, Yong; Yao, Jun; He, Minyan; Choi, Martin M F; Feng, Liang; Chen, Huilun; Wang, Fei; Chen, Ke; Zhuang, Rensheng; Maskow, Thomas; Wang, Gejiao; Zaray, Gyula

    2010-04-15

    The growth of Halobacillus sp. Y35 has been investigated in HGM hypersaline medium with different doses of As(III) and kaolin. The metabolic heat flux decreases with the increase in As(III) concentration, indicating that strain Y35 lowers their metabolic activity in order to resist the As(III) toxicity. Carbon dioxide flux, cell growth and protein synthesis rates, and total thermal effect have been, for the first time, successfully employed simultaneously to assess the effect of As(III) on strain Y35 in the absence and presence of kaolin. The relative adsorption capacity and adsorption intensity of kaolin for As(III) are higher with strain Y35 than that without strain Y35, demonstrating that it is possible to reduce the toxicity of As(III) to our environment by both using mineral adsorption and biosorption technology. Our work shows the potential application of kaolin and strain Y35 for the removal of As(III) from contaminated groundwater.

  15. Effect of kaolin addition on the performance of controlled low-strength material using industrial waste incineration bottom ash.

    PubMed

    Naganathan, Sivakumar; Razak, Hashim Abdul; Hamid, Siti Nadzriah Abdul

    2010-09-01

    Incineration of industrial waste produces large quantities of bottom ash which are normally sent to secured landfill, but is not a sustainable solution. Use of bottom ash in engineering applications will contribute to sustainability and generate revenue. One way of using the industrial waste incineration bottom ash is in controlled low-strength material (CLSM). Use of bottom ash in CLSM has problems related to bleeding and excessive strength development and so an additive has to be used to control bleeding and strength development. The main objective of this research is to study the effect of kaolin addition on the performance of CLSM made using industrial waste incineration bottom ash. CLSM mixes were made with bottom ash, cement, and refined kaolin. Various tests were performed on the CLSM in fresh and hardened states including compressive strength, water absorption, California bearing ratio (CBR) and the tests for concentration of leachable substances on the bleed and leachate. The compressive strength of CLSM tested ranged from 0.11 to 9.86 MPa. CBR values ranged from 6 to 46, and water absorption values from 12 to 36%. It was shown that the addition of kaolin delayed the initial setting time of CLSM mixtures, reduced bleeding, lowered the compressive strength, and increased the values of water absorption, sorption, and initial surface absorption. The CLSM tested did not have corrosivity. It was shown that the hardened CLSM was non hazardous, and the addition of kaolin increased the concentration of heavy metals and salts in the bleed and leachate.

  16. Effects of Several Newer Insecticides and Kaolin on Oviposition and Adult Mortality in Western Cherry Fruit Fly (Diptera: Tephritidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Effects of newer insecticides and kaolin-based particle film (Surround™ WP Crop Protectant), on oviposition and mortality in the western cherry fruit fly, Rhagoletis indifferens Curran, were determined. In a no-choice experiment, azinphos-methyl sprayed on cherries reduced oviposition by 98.5% comp...

  17. Effectiveness of kaolin clay particle film in managing Helopeltis collaris (Hemiptera: Miridae), a major pest of cacao in the Philippines

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Helopeltis collaris Stal, commonly known as cacao mirid or capsid bug is one of the major pests of cacao in Southeast Asia. Recent survey of cacao pests in the Philippines showed that cacao mirid bug is causing significant yield loss particularly in cacao growing areas in Luzon. Kaolin is a naturall...

  18. Influence of deficit irrigation and kaolin particle film on grape composition and volatile compounds in Merlot grape (Vitis vinifera L.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect on grape-derived volatile composition of a kaolin-based, foliar reflectant particle film (PF) and differing severities of vine water deficit was investigated in this study over two growing seasons on Merlot grapevines grown in a semi-arid region of southwestern Idaho. Vines were provided ...

  19. The mechanisms of plant stress mitigation by kaolin-based particle films and its applications in horticultural and agricultural crops

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Kaolin-based particle films have utility in reducing insect, heat, light, and uv stress in plants due to the reflective nature of the particles. Particle films with a residue density of 1 to 3 g/ square meter have been evaluated in a range of crops and agricultural environments. The particle film ...

  20. Repellency of a kaolin particle film to potato payllid, Bactericera cockerelli (Hemiptera: Psyllidae) on tomato under laboratory and field conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The potato psyllid, Bactericera cockerelli, is a vector of “Candidatus Liberibacter solanacearum,” the bacterium causing several diseases in solanaceous crops. Laboratory and field no-choice and choice experiments were conducted to evaluate repellency of kaolin particle film on adults of B. cockerel...

  1. Effect of Deficit Irrigation and Kaolin-based Foliar Reflectant Particle Film on Aroma of cv. Merlot (Vitis vinifera L.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Water deficit during development of red-skinned wine grape enhances berry composition for wine production but increases risk of fruit exposure to deleterious levels of heat and/or solar radiation. Foliar application of a kaolin-based particle film has been shown in many crops to alleviate stress sym...

  2. Kaolin particle film and water deficit influence red winegrape color under high solar radiation in an arid climate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Main and interactive effects of a kaolin-based particle film and water deficit severity on vine and berry attributes were evaluated in the warm, semi-arid climate of southwestern Idaho over three growing seasons in the cultivars Cabernet Sauvignon and Malbec. Berry concentrations of total anthocyan...

  3. Integrating Plant Essential Oils and Kaolin for the Sustainable Management of Thrips and Tomato Spotted Wilt on Tomato

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Thrips-vectored Tomato spotted wilt virus is one of the most devastating pest complexes affecting tomato in the southern USA and elsewhere. Field trials were conducted over two years to determine the effects of volatile plant essential oils and kaolin based particle films on the incidence of Tomato...

  4. Effects of simulated pulmonary surfactant on the cytotoxicity and DNA-damaging activity of respirable quartz and kaolin.

    PubMed

    Gao, N; Keane, M J; Ong, T; Wallace, W E

    2000-06-09

    Respirable-sized quartz and kaolin dusts were pretreated with simulated pulmonary surfactant dispersions of dipalmitoyl phosphatidylcholine (DPPC) in saline to model the conditioning of particles depositing in alveolar regions of the lung. DPPC-treated and untreated dusts were used to challenge lavaged rat pulmonary alveolar macrophages in vitro. Cytotoxicity was determined over a 5-d period using both total and viable cell counts from a fluorescence-based viability assay. DNA damage, as an indication of genotoxicity, was determined over a 7-d period by the single-cell gel electrophoresis assay. Untreated quartz and kaolin both expressed a significant and potent cytotoxicity, which increased with concentration and time. DPPC-surfactant pretreatment delayed significant expression of this cytotoxicity until 3 to 5 d after challenge. Untreated quartz also caused DNA damage, which increased with concentration and time. DPPC-surfactant treatment of quartz delayed most DNA damage expression to 5 and 7 d. Untreated kaolin expressed weaker activity for DNA damage, significant at the highest concentration through 5 d, and at the higher concentrations on d 7. Surfactant treatment delayed most kaolin activity for DNA damage to 7 d after challenge.

  5. Kaolin exogenous application boosts antioxidant capacity and phenolic content in berries and leaves of grapevine under summer stress.

    PubMed

    Dinis, L-T; Bernardo, S; Conde, A; Pimentel, D; Ferreira, H; Félix, L; Gerós, H; Correia, C M; Moutinho-Pereira, J

    2016-02-01

    Heat waves, high light intensities and water deficit are becoming important threats in many important viticultural areas worldwide, so the implementation of efficient and cost-effective mitigation strategies is crucial for the production of premium wines while maintaining productivity. In this context, the foliar application of kaolin, a chemically inert mineral with excellent reflective properties, is being developed and experimented as a strategy to reduce the impact of heat and drought in Douro vineyards (Northern Portugal), already revealing promising results. In the present study we investigated if an improved antioxidant capacity is part of the beneficial effects of kaolin, by studying changes in the enzymatic and nonenzymatic antioxidant system in leaves and berries (cv Touriga Nacional). Results showed that mature grape berries contained higher amounts of total phenols (40%), flavonoids (24%), anthocyanins (32%) and vitamin C (12%) than fruits from control vines, and important changes were also measured in leaves. In parallel, kaolin application improved the antioxidant capacity in berries, which was correlated with the observed increased content in secondary metabolites. Kaolin application also regulated secondary metabolism at the transcriptional level through the increase in the transcript abundance of genes encoding phenylalanine ammonia lyase and chalcone synthase.

  6. Communicating hydrocephalus in adult rats with kaolin obstruction of the basal cisterns or the cortical subarachnoid space.

    PubMed

    Li, Jie; McAllister, James P; Shen, Yimin; Wagshul, Mark E; Miller, Janet M; Egnor, Michael R; Johnston, Miles G; Haacke, E Mark; Walker, Marion L

    2008-06-01

    Communicating hydrocephalus (CH) occurs frequently, but clinically-relevant animal models amenable to diagnostic imaging and cerebrospinal fluid shunting are not available. In order to develop and characterize models of subarachnoid space (SAS) obstruction at the basal cisterns (BC) or cerebral convexities (CX), 25% kaolin was injected in adult female Sprague-Dawley rats following halothane anesthesia; intact- or saline-injected animals served as controls. For BC animals (n=28 hydrocephalics, n=20 controls), an anterior approach to the C1-clivus interval was employed and 30 microl of kaolin or saline was injected. For CX injections (n=13 hydrocephalics, n=3 controls), 50-60 microl of kaolin was injected bilaterally after separating the partitions in the SAS. In BC-injected rats, kaolin was observed grossly in the basal cisterns but not in the cisterna magna or at the foramina of Luschka, indicating that communicating (or extra-ventricular)--not obstructive--hydrocephalus had been induced. Following ketamine/xylazine anesthesia, magnetic resonance imaging (MRI) of gadolinium injected into the lateral ventricle also demonstrated CSF flow from the foramina of Luschka. MRI also revealed that ventriculomegaly progressed steadily in BC animals and by 2 weeks post-kaolin the mean Evan's ratio (frontal horn) increased significantly (mean 0.45 compared to 0.31 in intact- and 0.34 in saline-injected controls; p<0.001 for each). CX animals exhibited kaolin deposits covering approximately 80% of the cerebral hemispheres and developed noticeable ventriculomegaly (mean Evan's ratio 0.40), which was significant relative to intact animals (p=0.011) but not saline-injected controls. Surprisingly, ventriculomegaly following CX injections was less severe and much more protracted, requiring 3-4 months to develop compared to ventriculomegaly produced by BC obstruction. No hydrocephalic animals demonstrated obvious neurological deficits, but BC-injected animals that subsequently

  7. Carbon and nitrogen mineralization in vineyard acid soils amended with a bentonitic winery waste

    NASA Astrophysics Data System (ADS)

    Fernández-Calviño, David; Rodríguez-Salgado, Isabel; Pérez-Rodríguez, Paula; Díaz-Raviña, Montserrat; Nóvoa-Muñoz, Juan Carlos; Arias-Estévez, Manuel

    2015-04-01

    Carbon mineralization and nitrogen ammonification processes were determined in different vineyard soils. The measurements were performed in samples non-amended and amended with different bentonitic winery waste concentrations. Carbon mineralization was measured as CO2 released by the soil under laboratory conditions, whereas NH4+ was determined after its extraction with KCl 2M. The time evolution of both, carbon mineralization and nitrogen ammonification, was followed during 42 days. The released CO2 was low in the analyzed vineyard soils, and hence the metabolic activity in these soils was low. The addition of the bentonitic winery waste to the studied soils increased highly the carbon mineralization (2-5 fold), showing that the organic matter added together the bentonitic waste to the soil have low stability. In both cases, amended and non-amended samples, the maximum carbon mineralization was measured during the first days (2-4 days), decreasing as the incubation time increased. The NH4+ results showed an important effect of bentonitic winery waste on the ammonification behavior in the studied soils. In the non-amended samples the ammonification was no detected in none of the soils, whereas in the amended soils important NH4+ concentrations were detected. In these cases, the ammonification was fast, reaching the maximum values of NH4 between 7 and 14 days after the bentonitic waste additions. Also, the percentages of ammonification respect to the total nitrogen in the soil were high, showing that the nitrogen provided by the bentonitic waste to the soil is non-stable. The fast carbon mineralization found in the soils amended with bentonitic winery wastes shows low possibilities of the use of this waste for the increasing the organic carbon pools in the soil.On the other hand, the use of this waste as N-fertilizer can be possible. However, due its fast ammonification, the waste should be added to the soils during active plant growth periods.

  8. Na + and HTO diffusion in compacted bentonite: Effect of surface chemistry and related texture

    NASA Astrophysics Data System (ADS)

    Melkior, T.; Gaucher, E. C.; Brouard, C.; Yahiaoui, S.; Thoby, D.; Clinard, Ch.; Ferrage, E.; Guyonnet, D.; Tournassat, C.; Coelho, D.

    2009-05-01

    SummaryIn underground repository concepts for radioactive waste, bentonite is studied as a reference swelling material to be used as an engineered barrier. Under the changing geochemical conditions prevailing within the barrier (saturation with the fluid coming from the host formation, diffusion of various chemical plumes caused by the degradation of some constituents of the barrier-system, etc.), the surface chemistry of the clay particles could evolve. This work aims to characterize the effects of these changes on (i) the microstructure of compacted bentonite samples and (ii) the diffusion properties of HTO and Na in these samples. For this purpose, bentonite sets were equilibrated with different solutions: NaCl, CaCl 2, CsCl solutions as well as an artificial clayey porewater solution. The microstructure of the different samples was characterized by HRTEM and XRD, in a water saturated state. In parallel, effective diffusion coefficients of both HTO and 22Na were measured for the different samples. The density of the bentonite in the diffusion tests and in the HRTEM observations was set at 1.6 Mg m -3. From the microstructural observations and the results of diffusion tests, it is deduced that one key parameter is the occurrence of a gel phase in the material, which is found to depend strongly on the bentonite set: the gel phase dominates in Na-bentonite, while it is lacking in Cs-bentonite. The HTO diffusion coefficients are found to be lower in the samples with high gel phase content. Sodium diffusion does not follow the same trend: when compared with HTO, Na diffuses faster when the gel phase content is high. The latter result could indicate that the "accelerated diffusion mechanism" of cations, already mentioned in the literature, is enhanced in clayey materials that contain a gel phase.

  9. Decontamination of cesium, strontium, and cobalt from aqueous solutions by bentonite

    SciTech Connect

    Khan, M.A.; Khan, S.A.

    1996-12-31

    Sorption studies of cesium, strontium, and cobalt (Cs, Sr, and Co) on bentonite under various experimental conditions, such as contact time, pH, sorbent and sorbate concentration, and temperature, have been performed. The sorption data for all these metals have been interpreted in terms of Freundlich, Langmuir, and Dubinin-Radushkevich equations. Thermodynamics parameters, such as heat of sorption {Delta}H{degrees}, free energy change {Delta}G{degrees}, and entropy change {Delta}S{degrees}, for the sorption of these metals on bentonite have been calculated. The value of {Delta}H{degrees} shows that the sorption of Cs was exothermic, while the sorption of Sr and Co on bentonite were endothermic in nature. The value of {Delta}G{degrees} for their sorption was negative, showing the spontaneity of the process. The maximum loading capacity of Cs, Sr, and Co were 75.5, 22, and 27.5 meq, respectively, for 100 g of bentonite. The mean free energy E of Cs, Sr, and Co sorption on bentonite was 14.5, 9, and 7.7 kJ/mol, respectively. The value of E indicates that ion exchange may be the predominant mode of sorption for these radionuclides. The desorption studies with 0.01 M CaCl{sub 2} and groundwater at low-metal loading on bentonite showed that about 95% of Cs, 85-90% of Sr, and 97% of Co were irreversibly sorbed. Bentonite could be effectively used for the decontamination of wastewater effluent containing low concentrations of radioactive nuclides of Cs, Sr, and Co. 16 refs., 7 figs., 3 tabs.

  10. Permeability and expansibility of natural bentonite MX-80 in distilled water

    NASA Astrophysics Data System (ADS)

    Liu, Longcheng; Neretnieks, Ivars; Moreno, Luis

    Natural bentonite MX-80 differs from the purified and fully Na-exchanged bentonite in that it contains approximately 20.0% accessory minerals, in addition to the montmorillonite particles. Since the accessory minerals and montmorillonite particles have very different physical and chemical properties, natural bentonite MX-80 is found to expand much more slowly in distilled water, leading actually to a three-component system that has very different hydraulic properties from that of the fully Na-exchanged bentonite. To better understand and simulate the special features of expansion of natural bentonite MX-80 in distilled water, the focus is put primarily on the development of a Kozeny-Carman-like equation for its hydraulic permeability in the same way as it was done for Na-exchanged bentonite. With this permeability model, the dynamic force balance model that was originally developed for colloidal expansion of montmorillonite in a two-component system is applied to the natural MX-80 system. Without making any changes to the model, however, two strategies are used to account for both physical and chemical effects of the accessory minerals. The “lumped” strategy assumes that the accessory minerals are stuck onto the montmorillonite particles in such a way that they behave just like one solid component. The “stepwise” strategy changes the pore water chemistry gradually from initially distilled water to eventually achievement of the equilibrium condition. These strategies are simple but proved to function well. The agreement between the simulations and the experimental results indicates that the two-component dynamic force balance model works well in predicting the general features and the behavior of upward expansion of natural bentonite MX-80 in distilled water in a vertical test tube.

  11. Strontium migration in a crystalline medium: effects of the presence of bentonite colloids

    NASA Astrophysics Data System (ADS)

    Albarran, Nairoby; Missana, Tiziana; García-Gutiérrez, Miguel; Alonso, Ursula; Mingarro, Manuel

    2011-03-01

    The effects of bentonite colloids on strontium migration in fractured crystalline medium were investigated. We analyzed first the transport behaviour of bentonite colloids alone at different flow rates; then we compared the transport behaviour of strontium as solute and of strontium previously adsorbed onto stable bentonite colloids at a water velocity of approximately 7.1·10 - 6 m/s-224 m/yr. Experiments with bentonite colloids alone showed that - at the lowest water flow rate used in our experiments (7.1·10 - 6 m/s) - approximately 70% of the initially injected colloids were retained in the fracture. Nevertheless, the mobile colloidal fraction, moved through the fracture without retardation, at any flow rate. Bentonite colloids deposited over the fracture surface were identified during post-mortem analyses. The breakthrough curve of strontium as a solute, presented a retardation factor, Rf ~ 6, in agreement with its sorption onto the granite fracture surface. The breakthrough curve of strontium in the presence of bentonite colloids was much more complex, suggesting additional contributions of colloids to strontium transport. A very small fraction of strontium adsorbed on mobile colloids moved un-retarded ( Rf = 1) and this fraction was much lower than the expected, considering the quantity of strontium initially adsorbed onto colloids (90%). This behaviour suggests the hypothesis of strontium sorption reversibility from colloids. On the other hand, bentonite colloids retained within the granite fracture played a major role, contributing to a slower strontium transport in comparison with strontium as a solute. This was shown by a clear peak in the breakthrough curve corresponding to a retardation factor of approximately 20.

  12. A comparative study of tissue factor and kaolin on blood coagulation assays using rotational thromboelastometry and thromboelastography.

    PubMed

    Peng, Henry T; Grodecki, Richard; Rizoli, Sandro; Shek, Pang N

    2016-01-01

    Rotational thromboelastometry (ROTEM) and thromboelastography (TEG) have been increasingly used to diagnose acute coagulopathy and guide blood transfusion. The tests are routinely performed using different triggering activators such as tissue factor and kaolin, which activate different pathways yielding different results. To optimize the global blood coagulation assays using ROTEM and TEG, we conducted a comparative study on the activation methods employing tissue factor and kaolin at different concentrations as well as standard reagents as recommended by the manufacturer of each device. Key parameter values were obtained at various assay conditions to evaluate and compare coagulation and fibrinolysis profiles of citrated whole blood collected from healthy volunteers. It was found that tissue factor reduced ROTEM clotting time and TEG R, and increased ROTEM clot formation time and TEG K in a concentration-dependent manner. In addition, tissue factor affected ROTEM alpha angle, and maximum clot firmness, especially in the absence of kaolin activation, whereas both ROTEM and TEG clot lysis (LI30, CL30, and LY30) remained unaffected. Moreover, kaolin reduced ROTEM clotting time and TEG R and K, but to a lesser extent than tissue factor, in-tem and ex-tem. Correlations in all corresponding parameters between ROTEM and TEG were observed, when the same activators were used in the assays compared with lesser correlations between standard kaolin TEG and ROTEM (INTEM/EXTEM). The two types of viscoelastic point-of-care devices provide different results, depending on the triggering reagent used to perform the assay. Optimal assay condition was obtained to reduce assay time and improve assay accuracy.

  13. Properties of bentonite clay as buffer material in high-level waste geological disposal. Part I: Chemical species contained in bentonite

    SciTech Connect

    Takahashi, M.; Muroi, M.; Inoue, A.; Aoki, M.; Takizawa, M.; Ishigure, K.; Fujita, N.

    1987-02-01

    Bentonite clay is one of the most promising candidates for use as buffer material in the geological disposal systems of high-level waste. However, very little has been reported on the ionic species contained in bentonite clay itself, especially the anion species. Chemical analyses of bentonite clay materials were carried out. It was found that the major anion species contained in the bentonite clay materials are SO/sub 4//sup 2-/, Cl/sup -/, and CO/sub 2/ species. The amounts of these differ among the clay samples depending on the origins and the processing of the clay materials. A clay material used in a series of our experiments was also analyzed for cation species contained, and adsorption experiments were carried out for the major ions contained in the clay materials. No adsorption of the anions on the clay particles was observed, and it was found that the adsorption of Na/sup +/ can be explained as the ion exchange equilibrium between Na/sup +/ and H/sup +/.

  14. Multiple scattering wavelength dependent backscattering of kaolin dust in the IR: Measurements and theory

    NASA Technical Reports Server (NTRS)

    Ben-David, Avishai

    1992-01-01

    Knowing the optical properties of aerosol dust is important for designing electro-optical systems and for modeling the effect on propagation of light in the atmosphere. As CO2 lidar technology becomes more advanced and is used for multiwavelength measurements, information on the wavelength dependent backscattering of aerosol dust particles is required. The volume backscattering coefficient of aerosols in the IR is relatively small. Thus, only a few field measurements of backscattering, usually at only a few wavelengths, are reported in the literature. We present spectral field measurements of backscattering of kaolin dust in the 9-11 micron wavelength range. As the quantity of dust increases, multiple scattering contributes more to the measured backscattered signal. The measurements show the effect of the dust quantity of the spectral backscatter measurements. A simple analytical two stream radiative transfer model is applied to confirm the measurements and to give insight to the multiple scattering spectra of backscattering.

  15. Influence of Solids-to-liquid and Activator Ratios on Calcined Kaolin Cement Powder

    NASA Astrophysics Data System (ADS)

    Liew, Y. M.; Kamarudin, H.; Bakri, A. M. Mustafa Al; Binhussain, M.; Luqman, M.; Nizar, I. Khairul; Ruzaidi, C. M.; Heah, C. Y.

    This paper summarizes the effect of activator ratio on the processing of cement powder. Geopolymer slurry was produced via alkaline activation of calcined kaolin. Once the geopolymer slurry solidified, it was crushed and ground to obtain cement powder. Ultilizing the concept of "just adding water", hardened cement paste could be produced from cement powder. This paper concluded that solids-to-liquid and sodium silicate-to-sodium hydroxide ratios have a significant effect on compressive strength of hardened cement paste. The optimum solids-to-liquid and sodium silicate-to-sodium hydroxide ratios were 0.80 and 0.20, respectively. SEM micrographs showed that a processing route to produce cement powder by "just adding water" was possible, and the structure became denser and fewer unreacted particles were observed.

  16. Young's modulus and thermal expansion of ceramic samples made from kaolin and zeolite

    NASA Astrophysics Data System (ADS)

    Sunitrová, Ivana; Trník, Anton

    2016-07-01

    In this study we investigate the dependence of Young's modulus, mass change, and thermal expansion of ceramic samples made from a varying amount of kaolin (100 - 50 %) and zeolite (0 - 50 %) on the firing temperature. The samples are fired in a furnace at different temperatures from room temperature up to 1100 °C with a heating rate of 5°C.min-1 and 5 min soaking time at the highest temperature. Afterwards, the samples are freely cooled down and their mass, dimensions and resonant frequency are measured at room temperature. The resonant frequency (from which Young's modulus is calculated) is measured using an apparatus based on the impulse excitation technique (IET). Young's modulus of green samples is the highest for the sample containing 10 mass% of zeolite (3.2 GPa). After sintering the sample with 50 mass% of zeolite has the highest value (11.3 GPa).

  17. Electrochemical determination of cadmium(II) at platinum electrode modified with kaolin by square wave voltammetry.

    PubMed

    Mhammedi, M A El; Achak, M; Hbid, M; Bakasse, M; Hbid, T; Chtaini, A

    2009-10-30

    In this work, determination of cadmium(II) using square wave voltammetry (SWV) was described. The method is based on accumulation of these metal ions on kaolin platinum electrode (K/Pt). The K/Pt performance was optimized with respect to the surface modification and operating conditions. The optimized conditions were obtained in pH of 5.0 and accumulation time of 25 min. Under the optimal conditions, the relationship between the peak current versus concentration was linear over the range of 9 x 10(-8) to 8.3 x 10(-6) mol L(-1). The detection limit (DL, 3sigma) was 5.4 x 10(-9) mol L(-1). The analytical methodology was successfully applied to monitor the Cd(II) content in natural water. Interferences were also evaluated.

  18. Kaolins: sources of differences in cation-exchange capacities and cesium retention

    SciTech Connect

    Lim. C.H.; Jackson, M.L.; Koons, R.D.; Helmke, P.A.

    1980-01-01

    Seven kaolins from Georgia (southeastern USA), ranging from high to low commercial grade, were characterized by x-ray powder diffraction and chemical techniques to establish that the variation in quality was caused by impurities. The Ca and Cs cation-exchange capacities (CEC) varied from 2.67 to 8.17 and from 3.29 to 8.77 meq/100 g, respectively. The external surface CEC of kaolinite ranged from 0 to 1 meq/100 g. The Cs-retention capacity (0.19 to 1.14 meq/100 g) was closely related to Cs-measured vermiculite content and this content plus specific surface mica content. The Cs retention appeared to be primarily related to the presence of interlayer wedges at mica/vermiculite XY interfaces.

  19. Mechanisms of olive leaf extract-ameliorated rat arthritis caused by kaolin and carrageenan.

    PubMed

    Gong, Dezheng; Geng, Chengyan; Jiang, Liping; Wang, Lihui; Yoshimura, Hiroyuki; Zhong, Laifu

    2012-03-01

    Olive leaf extract (OLE) has antioxidant and antiinflammatory actions. However, the role of OLE in mechanical inflammatory arthritis (osteoarthritis, OA) is unclear. This study investigated the effect of OLE on the development of kaolin and carrageenan-induced arthritis, a murine model of OA. Administration of OLE significantly ameliorated paw swelling, the paw Evans blue content and the histopathological scores. In the human monocyte cell line, THP-1, the OLE reduced the LPS-induced TNF-α production and was dose dependent. Croton oil-induced ear edema in mice also revealed that treatment with OLE suppressed ear edema, myeloperoxidase (MPO) production and was dose dependent. These results indicated that OLE is an effective antiarthritis agent through an antiinflammation mechanism. Also OLE may be beneficial for the treatment of OA in humans.

  20. Selectivity coefficient for Ca/Na ion exchange in highly compacted bentonite

    NASA Astrophysics Data System (ADS)

    Karnland, Ola; Birgersson, Martin; Hedström, Magnus

    Bentonite clay is proposed as buffer material around the waste canisters and as tunnel backfill material in several concepts for disposal of radioactive waste. The distribution of charge compensating cations in the bentonite is of interest for several reasons, one being possible release of colloid particles from the bentonite to groundwater with very low ionic strength. The cation distribution at equilibrium may be calculated for various relevant groundwater compositions by use of selectivity coefficients. However, present literature data generally concerns coefficients measured in batch experiments with high water-to-solid ratios. The basic aim with the present work was therefore to determine selectivity coefficients for sodium/calcium exchange in bentonite with low water-to-solid ratios, and thereby give a reliable base for calculating the cation distribution in a confined bentonite buffer with a relatively high density. In total, six tests with homo-ionic Na- and Ca-montmorillonite, prepared to three material densities, were equilibrated with test solutions of successively increasing concentration. The distribution of cations at equilibrium was measured by use of ion selective electrodes and ICP/AES, and selectivity coefficients were calculated according to the Gaines-Thomas convention. The obtained selectivity coefficient was found to be in the range of 3.8-7.8, which is similar to those previously reported for high water-to-solid ratios.

  1. Modeling cation diffusion in compacted water-saturated sodium bentonite at low ionic strength.

    PubMed

    Bourg, Ian C; Sposito, Garrison; Bourg, Alain C M

    2007-12-01

    Sodium bentonites are used as barrier materials for the isolation of landfills and are under consideration for a similar use in the subsurface storage of high-level radioactive waste. The performance of these barriers is determined in large part by molecular diffusion in the bentonite pore space. We tested two current models of cation diffusion in bentonite against experimental data on the relative apparent diffusion coefficients of two representative cations, sodium and strontium. On the "macropore/nanopore" model, solute molecules are divided into two categories, with unequal pore-scale diffusion coefficients, based on location: in macropores or in interlayer nanopores. On the "surface diffusion" model, solute molecules are divided into categories based on chemical speciation: dissolved or adsorbed. The macropore/nanopore model agrees with all experimental data at partial montmorillonite dry densities ranging from 0.2 (a dilute bentonite gel) to 1.7 kg dm(-3) (a highly compacted bentonite with most of its pore space located in interlayer nanopores), whereas the surface diffusion model fails at partial montmorillonite dry densities greater than about 1.3 kg dm(-3).

  2. State of a Bentonite Barrier After 8 Years of Heating and Hydration in the Laboratory

    SciTech Connect

    Villar, Maria Victoria; Fernandez, Ana Maria; Gomez, Roberto; Martin, Pedro Luis; Barcala, Jose Miguel; Barrenechea, Jose F.; Luque, Javier F.

    2007-07-01

    The conditions of the bentonite in an engineered barrier for HLW disposal have been simulated in a laboratory test. Six cylindrical blocks of bentonite compacted at a dry density of 1.64 g/cm{sup 3} were piled up in a hermetic Teflon cell. The total length of the clay column inside the cell was 60 cm. The bottom surface of the bentonite was heated at 100 deg. C while the top surface was injected with granitic water. The duration of the test was 7.6 years. The water intake was measured during the test and, at the end, the cell was dismounted and the dry density, water content, mineralogy, geochemistry, and swelling capacity of the clay were measured in different sections along the column. At the end of the test no full water saturation was reached and water content and dry density gradients were found along the column. No mineralogical changes have been detected, although the pore water chemistry and the exchangeable complex of the smectite have changed along the bentonite. None of these changes affect drastically its swelling capacity, which remains high. The material used in this test is the FEBEX bentonite. (authors)

  3. Removal of toxic elements from aqueous solution using bentonite modified with L-histidine.

    PubMed

    Bakatula, E N; Cukrowska, E M; Weiersbye, I M; Mihaly-Cozmuta, L; Tutu, H

    2014-01-01

    This study proposes the use of bentonite modified with L-histidine for the removal of Cu, Co, Cr, Fe, Hg, Ni, U and Zn from aqueous solutions such as those impacted by acidic drainage. The surface areas of natural bentonite and bentonite-histidine were 73.8 and 61.2 m(2) g(-1), respectively. Elemental analysis showed an increase in the amount of carbon (0.258%) and nitrogen (0.066%) for the bentonite-histidine. At a fixed solid/solution ratio, the operating variables affecting the adsorption of metal ions from aqueous solution such as pH, initial concentration, contact time and temperature were studied in batch mode. The Freundlich isotherm model yielded a better fit than the Langmuir for the adsorption of Cu, Co, Ni and Zn, implying adsorption on a heterogeneous surface. Adsorption kinetics followed a pseudo-second-order model, suggesting chemisorption as the rate-limiting step. The apparent activation energy was greater than 40 kJ mol(-1) for Cu, Zn, Ni, Co and U, which is characteristic of a chemically controlled reaction. Thermodynamic constants ΔG and ΔH showed that the adsorption of metals was endothermic and spontaneous. Adsorption of heavy metals onto bentonite-histidine was efficient at low pH values, meaning that the adsorbent could be useful for remediating acid mine water.

  4. Kinetics of metribuzin release from bentonite-polymer composites in water.

    PubMed

    Sahoo, Sonalika; Manjaiah, K M; Datta, S C; Ahmed Shabeer, T P; Kumar, Jitendra

    2014-01-01

    A series of bentonite polymer-composites (BPCs) loaded with metribuzin were studied for their controlled release in aqueous medium. The release of active ingredient from BPCs was significantly lower as compared to commercial metribuzin formulation. The results revealed that the cumulative metribuzin release was highest (81%) from the BPCs containing 8% clay (commercial bentonite) and 2% metribuzin which correspond to the lowest (14 days) half-life values i.e., time required for 50% release of active ingredient (t1/2). The metribuzin release from the BPCs decreased with increased concentration of clays in polymer matrix and the release was further decreased with BPCs prepared with pure nano-bentonite. BPCs containing 12% clay and 2% metribuzin showed maximum t1/2 values i.e., 25 and 51 days for commercial bentonite and pure nano-bentonite as clay sources, respectively. The differential behaviour in the metribuzin release rates from BPCs was ascribed due to variations in crosslinking of metribuzin in the composites. As metribuzin release was found to be slower in BPCs compared to commercial formulation, it could be used for control of weeds tailored to different crops.

  5. [Thermodynamics adsorption and its influencing factors of chlorpyrifos and triazophos on the bentonite and humus].

    PubMed

    Zhu, Li-Jun; Zhang, Wei; Zhang, Jin-Chi; Zai, De-Xin; Zhao, Rong

    2010-11-01

    The adsorption of chlorpyrifos and triazophos on bentonite and humus was investigated by using the equilibrium oscillometry. The adsorption capacity of chlorpyrifos and triazophos on humus was great higher than bentonite at the same concentration. Equilibrium data of Langmuir, Freundlich isotherms showed significant relationship to the adsorption of chlorpyrifos and triazophos on humus (chlorpyrifos: R2 0.996 4, 0.996 3; triazophos: R2 0.998 9, 0.992 4). Langmuir isotherm was the best for chlorpyrifos and triazophos on bentonite (chlorpyrifos: R2 = 0.995 7, triazophos: R2 = 0.998 9). The pH value, adsorption equilibrium time and temperature were the main factors affecting adsorption of chlorpyrifos and triazophos on bentonite and humus. The adsorption equilibrium time on mixed adsorbent was 12h for chlorpyrifos and 6h for triazophos respectively. The mass ratio of humus and bentonite was 12% and 14% respectively, the adsorption of chlorpyrifos and triazophos was the stronglest and tended to saturation. At different temperatures by calculating the thermodynamic parameters deltaG, deltaH and deltaS, confirmed that the adsorption reaction was a spontaneous exothermic process theoretically. The adsorption was the best when the pH value was 6.0 and the temperature was 15 degrees C.

  6. Swelling pressure of a divalent-rich bentonite: Diffuse double-layer theory revisited

    NASA Astrophysics Data System (ADS)

    Schanz, Tom; Tripathy, Snehasis

    2009-05-01

    Physicochemical forces are responsible for the swelling pressure development in saturated bentonites. In this paper, the swelling pressures of several compacted bentonite specimens for a range of dry density of 1.10-1.73 Mg/m3 were measured experimentally. The clay used was a divalent-rich Ca-Mg-bentonite with 12% exchangeable Na+ ions. The theoretical swelling pressure-dry density relationship for the bentonite was determined from the Gouy-Chapman diffuse double-layer theory. A comparison of experimental and theoretical results showed that the experimental swelling pressures are either smaller or greater than their theoretical counterparts within different dry density ranges. It is shown that for dry density of the clay less than about 1.55 Mg/m3, a possible dissociation of ions from the surface of the clay platelets contributed to the diffuse double-layer repulsion. At higher dry densities, the adsorptive forces due to surface and ion hydration dominated the swelling pressures of the clay. A comparison of the modified diffuse double-layer theory equations proposed in the literature to determine the swelling pressures of compacted bentonites and the experimental results for the clay in this study showed that the agreement between the calculated and experimental swelling pressure results is very good for dry densities less than 1.55 Mg/m3, whereas at higher dry densities the use of the equations was found to be limited.

  7. Modification of bentonite with a cationic surfactant: An adsorption study of textile dye Reactive Blue 19.

    PubMed

    Ozcan, Adnan; Omeroğlu, Ciğdem; Erdoğan, Yunus; Ozcan, A Safa

    2007-02-09

    The utilization of modified bentonite with a cationic surfactant (dodecyltrimethylammonium (DTMA) bromide) as an adsorbent was successfully carried out to remove a synthetic textile dye (Reactive Blue 19 (RB19)) by adsorption, from aqueous solutions. Batch studies were carried out to address various experimental parameters such as pH, contact time and temperature. The surface modification of bentonite with a surfactant was examined using the FTIR spectroscopic technique and elemental analysis. Effective pH for the adsorption of RB19 onto DTMA-bentonite was around 1.5. The Langmuir isotherm model was found to be the best to represent the equilibrium with experimental data. The maximum adsorption capacity (q(max)) has been found to be 3.30x10(-4)molg(-1) or 206.58mgg(-1). The thermodynamic study indicated that the adsorption of RB19 onto DTMA-bentonite was favored with the negative Gibbs free energy values. The pseudo-second-order rate equation was able to provide the best description of adsorption kinetics and the intraparticle diffusion model was also applicable up to 40min for the adsorption of RB19 onto DTMA-bentonite.

  8. Adsorption of mixed cationic-nonionic surfactant and its effect on bentonite structure.

    PubMed

    Zhang, Yaxin; Zhao, Yan; Zhu, Yong; Wu, Huayong; Wang, Hongtao; Lu, Wenjing

    2012-01-01

    The adsorption of cationic-nonionic mixed surfactant onto bentonite and its effect on bentonite structure were investigated. The objective was to improve the understanding of surfactant behavior on clay mineral for its possible use in remediation technologies of soil and groundwater contaminated by toxic organic compounds. The cationic surfactant used was hexadecylpyridinium bromide (HDPB), and the nonionic surfactant was Triton X-100 (TX100). Adsorption of TX100 was enhanced significantly by the addition of HDPB, but this enhancement decreased with an increase in the fraction of the cationic surfactant. Part of HDPB was replaced by TX100 which decreased the adsorption of HDPB. However, the total adsorbed amount of the mixed surfactant was still increased substantially, indicating the synergistic effect between the cationic and nonionic surfactants. The surfactant-modified bentonite was characterized by Brunauer-Emmett-Teller specific surface area measurement, Fourier transform infrared spectroscopy, and thermogravimetric-derivative thermogravimetric/differential thermal analyses. Surfactant intercalation was found to decrease the bentonite specific surface area, pore volume, and surface roughness and irregularities, as calculated by nitrogen adsorption-desorption isotherms. The co-adsorption of the cationic and nonionic surfactants increased the ordering conformation of the adsorbed surfactants on bentonite, but decreased the thermal stability of the organobentonite system.

  9. Polypropylene Fiber Amendments to Alleviate Initiation and Evolution of Desiccation Cracks in Bentonite Liners

    NASA Astrophysics Data System (ADS)

    Tuller, M.; Gebrenegus, T. B.

    2009-12-01

    Sodium saturated bentonite is a major constituent of compacted and geosynthetic liners and covers for hydraulic isolation of hazardous waste, playing a crucial role in protecting groundwater and other environmental resources from harmful landfill leachates. Due to favorable hydraulic properties (i.e., low permeability), large surface area and associated adsorption capacity for particular contaminants, and relative abundance and low cost, bentonite is the material of choice in many modern waste containment systems. However, long-term interactions between bentonite and waste leachate and exposure of bentonite to desiccative conditions may significantly deteriorate liner or cover performance and ultimately lead to failure of containment systems. In the presented study, the potential usefulness of polypropylene fiber amendments for preventing initiation and evolution of desiccation cracks, while maintaining acceptably low permeability under saturated conditions was investigated. Well-controlled desiccation experiments were conducted using initially saturated bentonite-sand mixtures that contained varying amounts of polypropylene fibers. Initiation and evolution of surface cracks were observed by means of X-Ray Computed Tomography (CT). Advanced image analysis techniques were employed to characterize and quantify 2-D and 3-D features of the evolving crack networks. Potential negative effects of employed additives on saturated hydraulic conductivity were determined with fully-automated Flexible Wall Permeametry (FWP).

  10. Equilibrium, kinetics and thermodynamic studies for sorption of chlorobenzenes on CTMAB modified bentonite and kaolinite.

    PubMed

    Shu, Yuehong; Li, Laisheng; Zhang, Qiuyun; Wu, Honghai

    2010-01-15

    The sorption of chlorobenzenes (CBs) by cetyltrimethylammonium bromide (CTMAB) modified bentonite and kaolinite was investigated. The sorption isotherms for CBs were nearly linear, suggesting that sorption could be described by a distribution process. The distribution coefficient (K(d)) was primarily affected by the amount of sorbed surfactant. The organic carbon normalized sorption coefficient (K(oc)), however, was particularly dependent on arrangement of the surfactant cations. The K(d) of CBs was larger for CTMAB-bentonites than that for CTMAB-kaolinites, while the case for K(oc) was opposite. Thus, the clay mineral structure and morphology had a considerable influence on the surfactant arrangement, which was responsible for the partitioning of CBs. The sorption of CBs onto both CTMAB-bentonites and CTMAB-kaolinites followed pseudo-second-order kinetics. The intra-particle diffusion model for sorption was also investigated and compared to identify sorption mechanism. The sorption of CBs both on CTMAB-bentonites and CTMAB-kaolinites was exothermic in nature and accompanied by an increase in entropy and a decrease in Gibbs energy in the temperature range of 15-35 degrees C. The results indicated that CBs strongly interacted with CTMAB modified bentonite and kaolinite.

  11. Bentonite-amended soil special study. [Uranium Mill Tailings Remedial Action (UMTRA) Project

    SciTech Connect

    Not Available

    1989-12-01

    This special study was conducted to assess the viability of soil with a high percentage of bentonite added as an infiltration barrier in the cover of Uranium Mill Tailings Remedial Action (UMTRA) Project disposal cells. To achieve maximum concentration limits (MCLs) at several UMTRA Project sites, covers with a very low permeability are needed. If alternate concentration limits (ACLs) are the appropriate site groundwater compliance strategy, the US Department of Energy (DOE) is required to demonstrate, among other things, that the infiltration to the disposal cell is as low as reasonably achievable, and hence that the cover has a very low permeability. When the study discussed here was begun, the lowest permeability element available was CLAYMAX[sub R], a manufactured liner material constructed of natural material (bentonite clay) between two geosynthetics.The strength of soil-bentonite mixes was measured to see if they could be placed on sideslopes and not pose stability problems. Also evaluated were the hydraulic conductivities of soil-bentonite mixes. If the strengths and permeabilities of soils with a high percentage of bentonite are favorable, the soils may be used as infiltration barriers in current cover designs without changing pile geometries. The scope of work for this study called for a literature review and a two-phased laboratory testing program. This report presents the results of the literature review and the first phase of the testing program.

  12. Adsorption behavior of a textile dye of Reactive Blue 19 from aqueous solutions onto modified bentonite

    NASA Astrophysics Data System (ADS)

    Gök, Özer; Özcan, A. Safa; Özcan, Adnan

    2010-06-01

    The aim of this study is to evaluate adsorption kinetics, isotherms and thermodynamic parameters of Reactive Blue 19 (RB19) onto modified bentonite from aqueous solutions. The effects of pH, contact time, initial dye concentration and temperature were investigated in the experimentally. Natural bentonite was modified by using 1,6-diamino hexane (DAH) as a modifying agent. The characterization of modified bentonite (DAH-bentonite) was accomplished by using FTIR, TGA, BET and elemental analysis techniques. The optimum pH value for the adsorption experiments was found to be 1.5 and all the experiments were carried out at this pH value. The pseudo-second-order kinetic model agrees very well with the experimental results. Equilibrium data were also fitted well to the Langmuir isotherm model in the studied concentration range of RB19 at 20 °C. The results indicate that DAH-modified bentonite is a suitable adsorbent for the adsorption of textile dyes.

  13. [Hygienic evaluation of the occupational risk in working with Bulgarian bentonite raw material].

    PubMed

    Mikhaĭlova-Docheva, L; Buralkov, T; Kolev, K

    1986-01-01

    The use of bentonite in various branches of industry, and first of all, in foundry workshops, grows rapidly. The literature data on health injuries by bentonite dust are rather contradictory: due primarily, to the changeable mineralogical composition of the raw material from different deposits. That requires a specific hygienic assessment of each deposit in exploitation. The authors studied the mineral composition, quantitative ratio of the mineral components and morphology of the particles from the respirable fraction of aerosol in the extraction of Bulgarian bentonite. The microscopic mineralogical analysis in phase contrast, established a basic mass of clay minerals, confirmed by the X-ray structural analysis. The free silicic oxide is presented by low-temperature crystobalite and quartz, more rarely opal and chalcedony. Its quantity does not surpass 1-2%. The experimental studies on experimental animals confirmed fibrosis, degree I and II, according to Belt and King. The clinical studies on the workers established the presence of reticular changes in the lungs, type S and L, according to ILO-UC classification. The hygienic characteristic of the Bulgarian bentonite provided grounds for its broad application as a substitute for more dangerous raw materials, quartz sand in the foundries, in particular. Regardless of its advantages, bentonite is not harmless. The adherence to MAC for dustiness and periodic control of the quartz content in the raw material and aerosol in the working environment, are compulsory.

  14. Geochemical And Petrological Investigations Of The Representative Cretaceous Bentonite Beds, Wyoming : Tectonic Implications

    NASA Astrophysics Data System (ADS)

    Khandaker, N. I.

    2004-12-01

    Representative bentonite samples were collected from the exposed Cretaceous siliciclastics in Bighorn Basin, north-central Wyoming. Bentonite beds constitute a significant stratigraphic importance with respect to local and regional correlation tool and are associated with the Thermopolis Shale (Lower Cretaceous), Mowry Shale (Lower Cretaceous), and Frontier Formation (Upper Cretaceous). These beds range in thickness from few inches to ten feet and are interbedded with thick cross-bedded sandstone, pebbly sandstone, polymictic conglomerate, siliceous-rippled shale, and lignitic shale. Preliminary petrological and geochemical investigations were carried out to establish a distinctive geochemical signature for each bed. Emphasis was given on the overall distribution of the immobile traces, high refractory elements, and ultrastable heavy mineral components among the selective bentonite beds. The outcome of petrological, bulk, and trace element studies involving multiple bentonite beds indicated a subtle difference in terms of abundance of trace-element and detrital components among the studied samples and can be attributed to the source region characteristics, distinctive diagenetic pathways, and depositional setting. Furthermore, geochemical analyses involving multi-element plots suggest to an evolving source terrain located in close proximity to the bentonite depositional basin.

  15. The Lower Silurian Osmundsberg K-bentonite. Part I: Stratigraphic position, distribution, and palaeogeographic significance

    USGS Publications Warehouse

    Bergstrom, Stig M.; Huff, W.D.; Kolata, Dennis R.

    1998-01-01

    A large number of Lower Silurian (Llandovery) K-bentonite beds have been recorded from northwestern Europe, particularly in Baltoscandia and the British Isles, but previous attempts to trace single beds regionally have yielded inconclusive results. The present study suggests that based on its unusual thickness, stratigraphic position and trace element geochemistry, one Telychian ash bed, the Osmundsberg K-bentonite, can be recognized at many localities in Estonia, Sweden and Norway and probably also in Scotland and Northern Ireland. This bed, which is up to 115 cm thick, is in the lower-middle turriculatus Zone. The stratigraphic position, thickness variation and geographic distribution of the Osmundsberg K-bentonite are illustrated by means of 12 selected Llandovery successions in Sweden, Estonia, Norway, Denmark, Scotland and Northern Ireland. In Baltoscandia, the Osmundsberg K-bentonite shows a trend of general thickness increase in a western direction suggesting that its source area was located in the northern Iapetus region between Baltica and Laurentia. Because large-magnitude ash falls like the one that produced the Osmundsberg K-bentonite last at most a few weeks, such an ash bed may be used as a unique time-plane for a variety of regional geological and palaeontological studies.

  16. Modeling cation diffusion in compacted water-saturatedNa-bentonite at low ionic strength

    SciTech Connect

    Bourg, Ian C.; Sposito, Garrison; Bourg, Alain C.M.

    2007-08-28

    Sodium bentonites are used as barrier materials for the isolation of landfills and are under consideration for a similar use in the subsurface storage of high-level radioactive waste. The performance of these barriers is determined in large part by molecular diffusion in the bentonite pore space. We tested two current models of cation diffusion in bentonite against experimental data on the relative apparent diffusion coefficients of two representative cations, sodium and strontium. On the 'macropore/nanopore' model, solute molecules are divided into two categories, with unequal pore-scale diffusion coefficients, based on location: in macropores or in interlayer nanopores. On the 'surface diffusion' model, solute molecules are divided into categories based on chemical speciation: dissolved or adsorbed. The macropore/nanopore model agrees with all experimental data at partial montmorillonite dry densities ranging from 0.2 (a dilute bentonite gel) to 1.7 kg dm{sup -3} (a highly compacted bentonite with most of its pore space located in interlayer nanopores), whereas the surface diffusion model fails at partial montmorillonite dry densities greater than about 1.2 kg dm{sup -3}.

  17. Studies on the effect of quartz, bentonite and coal dust mixtures on macrophages in vitro.

    PubMed Central

    Adamis, Z.; Timár, M.

    1978-01-01

    The effect of quartz, bentonite and coal dusts as well as the effect of the artificial mixture of these dusts on TTC reduction and extra-and intra-cellular lactate dehydrogenase activity in peritoneal rat macrophages was determined in vitro. The cell-membrane-damaging effect of quartz caused a significant extracellular release of lactate dehydrogenase. Bentonite caused no extracellular enzyme release, which leads us to believe that the biological effect of this dust is shown by decrease in intra-cellular lactate dehydrogenase activity. TTC reduction was inhibited equally by quartz and qentonite. In mixtures of quartz (60%)-bentonite (40%) dust the specific effect of quartz was inhibited by bentonite in vitro and also in vivo. We obtained the same results with coal-quartz-bentonite dust mixtures in vitro. Our experiments show that comparison of the biological effects of artificial dust mixtures and airborne dust samples is justified, and prove that performing various examinations simultaneously give fuller particulars on the probable biological effect of mineral dusts. PMID:213094

  18. Oral antioxidant therapy for juvenile rats with kaolin-induced hydrocephalus

    PubMed Central

    2014-01-01

    Background Oxidative and nitrosylative changes have been shown to occur in conjunction with the hypoxic changes and cellular/axonal damage in hydrocephalic rodent brains. We hypothesized that antioxidant therapy would improve behavioral, neurophysiological, and/or neurobiochemical outcomes in juvenile rats following induction of hydrocephalus. Methods Three-week old rats received an injection of kaolin (aluminum silicate) into the cisterna magna. Magnetic resonance (MR) imaging was performed two weeks later to assess ventricle size and stratify rats to four treatment conditions. Rats were treated for two weeks daily with sham therapy of either oral canola oil or dextrose or experimental therapy of a low or high dose of an antioxidant mixture containing α-tocopherol, L-ascorbic acid, coenzyme Q10 (CoQ10), reduced glutathione, and reduced lipoic acid. Behavior was examined thrice weekly. Results All hydrocephalic groups lagged in weight gain in comparison to non-hydrocephalic controls, all developed significant ventriculomegaly, and all exhibited white matter destruction. Canola oil with or without the antioxidant mixture normalized antioxidant capacity in brain tissue, and the dextrose-treated rats had the greatest ventricular enlargement during the treatment period. However, there were no significant differences between the four treatment groups of hydrocephalic rats for the various behavioral tasks. Glial fibrillary acidic protein and myelin basic protein quantitation showed no differences between the treatment groups or with control rats. There was increased lipid peroxidation in the hydrocephalic rats compared to controls but no differences between treatment groups. Conclusion The antioxidant cocktail showed no therapeutic benefits for juvenile rats with kaolin-induced hydrocephalus although canola oil might have mild benefit. PMID:25324960

  19. A coupled THC model of the FEBEX in situ test with bentonite swelling and chemical and thermal osmosis

    SciTech Connect

    Zheng, L.; Samper, J.; Montenegro, L.

    2011-04-01

    The performance assessment of a geological repository for radioactive waste requires quantifying the geochemical evolution of the bentonite engineered barrier. This barrier will be exposed to coupled thermal (T), hydrodynamic (H), mechanical (M) and chemical (C) processes. This paper presents a coupled THC model of the FEBEX (Full-scale Engineered Barrier EXperiment) in situ test which accounts for bentonite swelling and chemical and thermal osmosis. Model results attest the relevance of thermal osmosis and bentonite swelling for the geochemical evolution of the bentonite barrier while chemical osmosis is found to be almost irrelevant. The model has been tested with data collected after the dismantling of heater 1 of the in situ test. The model reproduces reasonably well the measured temperature, relative humidity, water content and inferred geochemical data. However, it fails to mimic the solute concentrations at the heater-bentonite and bentonite-granite interfaces because the model does not account for the volume change of bentonite, the CO{sub 2}(g) degassing and the transport of vapor from the bentonite into the granite. The inferred HCO{sub 3}{sup -} and pH data cannot be explained solely by solute transport, calcite dissolution and protonation/deprotonation by surface complexation, suggesting that such data may be affected also by other reactions.

  20. Noncovalent immobilization of Pectinesterase (Prunus armeniaca L.) onto bentonite.

    PubMed

    Karakuş, Emine; Ozler, Aynur; Pekyardimci, Sule

    2008-01-01

    In this work, pectinesterase isolated from Malatya apricot was immobilized onto acid-treated bentonite surface by simple adsorption at pH 9.0. The properties of free and immobilized enzyme were defined. The effect of various factors such as pH, temperature, heat, and storage stability on immobilized enzyme were investigated. Optimum pH and temperature were determined to be 9.0 and 50 degrees C, respectively. Kinetic parameters of the immobilized enzyme (Km and Vmax values) were also determined as 0.51 mM of the Km and 14.6 micromol min(-1) mg(-1) of the Vmax. No drastic change was observed in the Km value after immobilization. The Vmax value of immobilized enzyme was 8.4-fold bigger than those of free enzyme. Thermal and storage stability experiments were carried out. The patterns of heat stability indicated that the immobilization process tends to stabilize the enzyme. The properties of the immobilized enzyme were compared to those of the free enzyme.

  1. The Paramagnetic Pillared Bentonites as Digestive Tract MRI Contrast Agents

    NASA Astrophysics Data System (ADS)

    Mojović, Miloš; Daković, Marko; Omerašević, Mia; Mojović, Zorica; Banković, Predrag; Milutinović-Nikolić, Aleksandra; Jovanović, Dušan

    The increased use of imaging techniques in diagnostic studies, such as MRI, has contributed to the development of the wide range of new materials which could be successfully used as image improving agents. However, there is a lack of such substances in the area of gastrointestinal tract MRI. Many of the traditionally popular relaxation altering agents show poor results and disadvantages provoking black bowel, side effects of diarrhea and the presence of artifacts arising from clumping. Paramagnetic species seem to be potentially suitable agents for these studies, but contrast opacification has been reported and less than 60% of the gastrointestinal tract magnetic resonance scans showed improved delineation of abdominal pathologies. The new solution has been proposed as zeolites or smectite clays (hectorite and montmorillonite) enclosing of paramagnetic metal ions obtained by ion-exchange methods. However, such materials have problems of leakage of paramagnetic ions causing the appearance of the various side-effects. In this study we show that Co+2 and Dy+3 paramagnetic-pillared bentonites could be successfully used as MRI digestive tract non-leaching contrast agents, altering the longitudinal and transverse relaxation times of fluids in contact with the clay minerals.

  2. Electrical resistivity characteristics of diesel oil-contaminated kaolin clay and a resistivity-based detection method.

    PubMed

    Liu, Zhibin; Liu, Songyu; Cai, Yi; Fang, Wei

    2015-06-01

    As the dielectric constant and conductivity of petroleum products are different from those of the pore water in soil, the electrical resistivity characteristics of oil-contaminated soil will be changed by the corresponding oil type and content. The contaminated soil specimens were manually prepared by static compaction method in the laboratory with commercial kaolin clay and diesel oil. The water content and dry density of the first group of soil specimens were controlled at 10 % and 1.58 g/cm(3). Corresponding electrical resistivities of the contaminated specimens were measured at the curing periods of 7, 14, and 28 and 90, 120, and 210 days on a modified oedometer cell with an LCR meter. Then, the electrical resistivity characteristics of diesel oil-contaminated kaolin clay were discussed. In order to realize a resistivity-based oil detection method, the other group of oil-contaminated kaolin clay specimens was also made and tested, but the initial water content, oil content, and dry density were controlled at 0~18 %, 0~18 %, 1.30~1.95 g/cm(3), respectively. Based on the test data, a resistivity-based artificial neural network (ANN) was developed. It was found that the electrical resistivity of kaolin clay decreased with the increase of oil content. Moreover, there was a good nonlinear relationship between electrical resistivity and corresponding oil content when the water content and dry density were kept constant. The decreasing velocity of the electrical resistivity of oil-contaminated kaolin clay was higher before the oil content of 12 % than after 12 %, which indicated a transition of the soil from pore water-controlled into oil-controlled electrical resistivity characteristics. Through microstructural analysis, the decrease of electrical resistivity could be explained by the increase of saturation degree together with the collapse of the electrical double layer. Environmental scanning electron microscopy (ESEM) photos indicated that the diesel oil

  3. Adsorption Processes of Lead Ions on the Mixture Surface of Bentonite and Bottom Sediments.

    PubMed

    Hegedűsová, Alžbeta; Hegedűs, Ondrej; Tóth, Tomáš; Vollmannová, Alena; Andrejiová, Alena; Šlosár, Miroslav; Mezeyová, Ivana; Pernyeszi, Tímea

    2016-12-01

    The adsorption of contaminants plays an important role in the process of their elimination from a polluted environment. This work describes the issue of loading environment with lead Pb(II) and the resulting negative impact it has on plants and living organisms. It also focuses on bentonite as a natural adsorbent and on the adsorption process of Pb(II) ions on the mixture of bentonite and bottom sediment from the water reservoir in Kolíňany (SR). The equilibrium and kinetic experimental data were evaluated using Langmuir isotherm kinetic pseudo-first and pseudo-second-order rate equations the intraparticle and surface diffusion models. Langmuir isotherm model was successfully used to characterize the lead ions adsorption equilibrium on the mixture of bentonite and bottom sediment. The pseudo second-order model, the intraparticle and surface (film) diffusion models could be simultaneously fitted the experimental kinetic data.

  4. Surface Fractal Dimension of Bentonite and its Application in Calculation of Swelling Deformation

    NASA Astrophysics Data System (ADS)

    Xiang, G. S.; Xu, Y. F.; Jiang, H.

    2014-09-01

    The correlation between the void ratio of swelled montmorillonite and the vertical overburden pressure can be expressed as {e}{ m} = Kp{ s}{D{ s}-3}. The surface fractal dimension Ds of five bentonites were estimated from the swelling deformation tests according to this fractal correlation. The reliability of surface fractal dimension obtained from the swelling deformation test was confirmed by nitrogen adsorption test, with identical values of surface fractal dimension obtained from both tests. The surface fractal dimension can also be used to estimate the swelling deformation of bentonite, after calculating the swelling coefficient K from the parameters of diffuse double layer (DDL) model in the osmotic swelling phase. Comparison of the model predictions with a number of experimental results on swelling deformation of both Na dominant and Ca dominant bentonites suggests that the surface fractal model works excellent in the cases tested.

  5. Cadmium removal from aqueous solutions by hydroxy-8 quinoleine intercalated bentonite.

    PubMed

    Bentouami, A; Ouali, M S

    2006-01-15

    An Algerian bentonite was purified and modified by intercalation of 8-hydroxyquinolinium ion. These materials were characterized by X-ray diffraction, infrared spectroscopy, and thermal analysis. Comparative batch experiments were performed using bentonite-oxine complex (B-oxine) and sodic bentonite (B-Na) for removing cadmium from aqueous solutions. Kinetics study results of cadmium removal with B-Na and B-oxine fit a pseudo-second-order model. The adsorption isotherm data follow the Langmuir equation in which parameters were calculated. B-oxine has a better cadmium removal capacity (61.35 mg/g) than B-Na (29.41 mg/g). Calculated thermodynamic parameters using the van't Hoff equation showed that the removal process is endothermic with B-oxine and exothermic with B-Na. A mechanism of ion exchange followed by complexation-precipitation is suggested for cadmium removal with B-oxine.

  6. Correlation of Champlainian (Middle Ordovician) K-bentonite beds in Central Pennsylvania based on chemical fingerprinting

    SciTech Connect

    Cullen-Lollis, J.; Huff, W.D.

    1986-11-01

    The lower Trenton Salona Formation in central Pennsylvania contains five widespread K-bentonite beds, distinguishable on the basis of chemical fingerprinting. Thirty-five samples, one from each K-bentonite bed with good stratigraphic control at seven localities, were analyzed for Na, K, Sc, Cr, Mn, Fe, Co, Zn, Ga, As, Rb, Sb, Cs, La, Ce, Sm, Eu, Tb, Dy, Yb, Lu, Hf, Ta, and Th by instrumental neutron activation analysis and for Zr and Ti by X-ray fluorescence. Chemical data were then treated by step-wise discriminant analysis to determine the most powerful grouping of discriminating elements and to create a discriminant model which would maximize the differences between the five beds and used to classify samples whose stratigraphic position is uncertain. Discriminant analysis revealed that differences in chemical composition are significantly greater between K-bentonite beds than within them. Yb, Sc, Ti, Th, Dy, Ta, Ga, Hf, Fe, Tb, Na, Lu, Ce, Sm, Co, Cr, K, Cs, and Eu, listed in order of their relative strength to discriminate among the five beds as a group can account for all but 0.0001% of the variance existing within each bed. Four discriminant functions were computed during the analysis. Eigenvalues and a territorial map indicate that the discriminant model is very effective for characterizing each K-bentonite bed and classifying unknown samples. The results of this study demonstrate the presence of unique and identifiable chemical fingerprints of K-bentonite beds in the Salona Formation, and provide an additional tool for correlating K-bentonite beds in central Pennsylvania and surrounding areas.

  7. Ordovidan K-bentonites in the Precordillera of San Juan and its tectomasmatic significance

    USGS Publications Warehouse

    Cingolani, C.A.; Huff, W.; Bergstrom, S.; Kolata, D.

    1997-01-01

    A succession of approximately 35 early Middle Ordovician K-bentonite beds are exposed in the Precordillera region near the town of Jachal, in San Juan Province (at Cerro Viejo and La Chilca sections). They occur in argillaceous limestone in the upper part of the San Juan Limestone and in the interbedded shales and mudstones at the base of the overlying Los Azules Formation. Total thickness of the K-bentonite-bearing interval is 23 m and individual beds range from 1 to 65 cm thick. An essentially Arenig-Llanvirn age for the K-bentonite succession is indicated by the presence of graptolites diagnostic of the Paraglossograptus tentaculatus Zone and conodonts indicating the Eoplacognathus suecicus Zone. The bentonites consist mainly of Rl ordered illite/smectite, characteristic of most of the lower Paleozoic K-bentonites, plus volcanogenic crystals. Similar to other K-bentonites, these probably represent the distal, glass-rich portion of fall-out ash beds derived from collision zone explosive volcanism. The geochemical data and preliminary plots on the magmatic discrimination diagram indicate the parental magma was of rhyolite to trachyandesite composition. Tectonic discrimination diagrams show the setting of Cerro Viejo ash layers as falling on the boundary between volcanic arc and within plate rocks, typical of collision margin felsic volcanic rocks. U-Pb isotope dating for two zircon fractions from one sample show a lower concordia intercept of 461, +7-10 Ma coincident with the biostratigraphic age. Thus, they have important implications for the origin and early history of the allochtonous Precordillera terrane and the Pacific margin of South America. Furthermore, they are potentially important in interpretations of the paleogeographic relations of Laurentia and Gondwana during Ordovician time. ?? 1997 Asociacio??n Geolo??gica Argentina.

  8. Experimental and modeling studies on sorption and diffusion of radium in bentonite

    NASA Astrophysics Data System (ADS)

    Tachi, Y.; Shibutani, T.; Sato, H.; Yui, M.

    2001-02-01

    The sorption and desorption behavior of radium on bentonite and purified smectite was investigated as a function of pH, ionic strength and liquid to solid ratio by batch experiments. The distribution coefficients ( Kd) were in the range of 10 2 to >10 4 ml g -1 and depended on ionic strength and pH. Most of sorbed Ra was desorbed by 1 M KCl. The results for purified smectite indicated that Ra sorption is dominated by ion exchange at layer sites of smectite, and surface complexation at edge sites may increase Ra sorption at higher pH region. Reaction parameters between Ra and smectite were determined based on an interaction model between smectite and groundwater. The reaction parameters were then used to explain the results of bentonite by considering dissolution and precipitation of minerals and soluble impurities. The dependencies of experimental Kd values on pH, ionic strength and liquid to solid ratio were qualitatively explained by the model. The modeling result for bentonite indicated that sorption of Ra on bentonite is dominated by ion exchange with smectite. The observed pH dependency was caused by changes of Ca concentration arising from dissolution and precipitation of calcite. Diffusion behavior of Ra in bentonite was also investigated as a function of dry density and ionic strength. The apparent diffusion coefficients ( Da) obtained in compacted bentonite were in the range of 1.1×10 -11 to 2.2×10 -12 m 2 s -1 and decreased with increasing in dry density and ionic strength. The Kd values obtained by measured effective diffusion coefficient ( De) and modeled De were consistent with those by the sorption model in a deviation within one order of magnitude.

  9. Diffusion of Tritiated Water (HTO) Through Compacted Bentonite Clay : Mechanisms and Modeling

    NASA Astrophysics Data System (ADS)

    Bourg, I. C.; Bourg, A. C.; Sposito, G.

    2002-12-01

    Diffusion through microporous materials has long been tackled with common tools of hydrogeological investigation, adapted to materials with a larger pore size. Parameters such as the porosity, tortuosity and adsorption coefficients are still usually defined as if there were a clear boundary between the free pore water and the solid phase. We suggest that a closer look at the structure of microporous materials is necessary and can yield successful mechanistic models of diffusion. Our case study is the diffusion of tritiated water (HTO) through compacted bentonite clay. In compacted bentonite, due to the high montmorillonite content of bentonite, the pore water is in intimate contact with the surface and most of the microporous water solvates the exchangeable cations. Despite this, HTO diffusion is often used as a non-reactive tracer to probe the pore geometry of compacted clay, yielding very high tortuosity coefficients (up to 40-60, far above the expected 3 for a random array of flat pores). We describe a model that accounts for the dual porosity of compacted bentonite (interlayer and inter-aggregate pores) and the higher viscosity of water in montmorillonite interlayers. This model successfully predicts HTO diffusion through bentonites with different montmorillonite contents (from 50 to 100 %) in a wide range of bulk dry densities (up to 2.0 kg/L). The model has no adjustable parameters. This is important to the diffusion of all other species through compacted bentonite clays, because models of the diffusion of reactive species are generally built on the geometric pore properties derived from the diffusion of "non-reactive" species such as HTO.

  10. Air and groundwater flow at the interface between fractured host rock and a bentonite buffer

    NASA Astrophysics Data System (ADS)

    Dessirier, B.; Jarsjo, J.; Frampton, A.

    2014-12-01

    Designs of deep geological repositories for spent nuclear fuel include several levels of confinement. The Swedish and Finnish concept KBS-3 targets for example sparsely fractured crystalline bedrock as host formation and would have the waste canisters embedded in an engineered buffer of compacted MX-80 bentonite. The host rock is a highly heterogeneous dual porosity material containing fractures and a rock matrix. Bentonite is a complex expansive porous material. Its water content and mechanical properties are interdependent. Beyond the specific physics of unsaturated flow and transport in each medium, the interface between them is critical. Detailed knowledge of the transitory two-phase flow regime, induced by the insertion of the unsaturated buffer in a saturated rock environment, is necessary to assess the performance of planned KBS-3 deposition holes. A set of numerical simulations based on the equations of two-phase flow for water and air in porous media were conducted to investigate the dynamics of air and groundwater flow near the rock/bentonite interface in the period following installation of the unsaturated bentonite buffer. We assume state of the two-phase flow parameter values for bentonite from laboratory water uptake tests and typical fracture and rock properties from the Äspö Hard rock laboratory (Sweden) gathered under several field characterization campaigns. The results point to desaturation of the rock domain as far as 10 cm away from the interface into matrix-dominated regions for up to 160 days. Similar observations were made during the Bentonite Rock Interaction Experiment (BRIE) at the Äspö HRL, with a desaturation sustained for even longer times. More than the mere time to mechanical and hydraulic equilibrium, the occurrence of sustained unsaturated conditions opens the possibility for biogeochemical processes that could be critical in the safety assessment of the planned repository.

  11. Construction of low permeability soil-bentonite barrier caps and liners for landfills

    SciTech Connect

    Webber, T.; Williams, M.

    1995-12-31

    A low permeability soil barrier layer is the usual regulatory requirement for both caps and liner systems on modern municipal, industrial, and hazardous waste landfills. This soil layer is either used as the sole barrier or as the soil component of a composite liner system. This paper presents construction experience for blending on site soils with sodium bentonite to produce a thick, low permeability soil barrier layer. The paper begins with a description of the components and construction of the barrier layer and discusses how soil-bentonite barrier layers meet or exceed the regulatory performance criteria for both State and Federal agencies.

  12. A Study on the Effect of Clay Particle Orientation on Diffusion in Compacted Bentonite

    SciTech Connect

    Sato, H.

    2002-02-26

    In this study, the effect of the orientation of clay particles on diffusion in compacted bentonite, which is regarded to be quite important as a candidate buffer material in safety assessment for a geological disposal of high-level radioactive waste, was experimentally discussed by investigating effective diffusion coefficients (De) for tritiated water (HTO), which is non-sorptive onto bentonite. The diffusion experiments were carried out for 2 kinds of smectite contents of Na-bentonites, Kunigel-V1{reg_sign} (content of Na-smectite, 46-49wt%) and Kunipia-F{reg_sign} (content of Na-smectite, > 99wt%) at dry densities of 1.0 and 1.5 Mg/m3 by a through-diffusion method. The through-diffusion experiments were carried out for the same direction as compacted direction of bentonite and perpendicular direction to compacted direction. Scanning electron microscopic (SEM) observations for the cross section of bentonite in the axial and perpendicular directions to compacted direction of bentonite were also carried out at dry densities of 1.0, 1.6, and 2.0 Mg/m3. Although De values for Kunigel-V1{reg_sign} were approximately the same for both diffusion directions to compacted direction over the densities, and no anisotropy in De was found, De values in the perpendicular direction to compacted direction for Kunipia-F{reg_sign} were clearly higher than those in the same direction as compacted direction. In the SEM observations, no significant orientation of clay particles was found for Kunigel-V1{reg_sign} over the densities, while the orientation of clay particles was clearly found for Kunipia-F{reg_sign}, and the degree of the orientation of clay particles became significant with an increase in dry density of bentonite. This tendency is in good agreement with that for De values obtained, indicating that smectite content in bentonite affects the orientation property of clay particles, and that the orientated clay particles affect diffusion pathway.

  13. Near-infrared reflectance spectra of mixtures of kaolin-group minerals: use in clay mineral studies

    USGS Publications Warehouse

    Crowley, J.K.; Vergo, N.

    1988-01-01

    Near-infrared (NIR) reflectance spectra for mixtures of ordered kaolinite and ordered dickite have been found to simulate the spectral response of disordered kaolinite. The amount of octahedral vacancy disorder in nine disordered kaolinite samples was estimated by comparing the same spectra to the spectra of reference mixtures. The resulting estimates are consistent with previously published estimates of vacancy disorder for similar kaolin minerals that were modeled from calculated X-ray diffraction patterns. -from Authors

  14. [Effect of Zirconium Modified Kaolin-Based Cap on Migration and Transformation of Phosphorus Between Sediment and Overlying Water].

    PubMed

    Zhang, Zhe; Lin, Jian-wei; Zhan, Yan-hui; Wang, Hong

    2016-04-15

    In this study, microcosm incubation experiments were conducted to investigate the effect of zirconium modified kaolin (ZrMK)-based cap on the migration and transformation of phosphorus (P) between sediments collected from a heavily polluted river and overlying waters under anaerobic conditions. The results showed that a large amount of P was released from the sediments into the overlying water column under anaerobic conditions, and the overwhelming majority of P in the overlying water existed in the form of phosphate. The flux of P from the anaerobic sediments was slightly reduced by the kaolin-based cap, while significantly reduced by the ZrMK-based cap. Sequential extraction of P from the kaolin-based cap at the end of incubation experiments suggested that 29% of P adsorbed by kaolin existed as the bicarbonate-dithionite extracted P (BD-P), and 63% of adsorbed P existed as the residual P (Res-P). Sequential extraction of P from the ZrMK-based cap at the end of incubation experiments suggested that 90% of P adsorbed by ZrMK existed as the NaOH extractable P (NaOH-P) and Res-P, which were unlikely to be released under anaerobic conditions. Compared with no capping, sediments capping with ZrMK did not promote BD-P release from the sediments under anaerobic conditions, but promoted the formation of NaOH-P in the sediments. X-ray photoelectron spectroscopy (XPS) and solid state ³¹P nuclear magnetic resonance (NMR) analyses of ZrMK-based caps before and after sediment incubation experiments indicated that the adsorption of P by the ZrMK-based caps followed the ligand exchange and inner-sphere complexing mechanism. Results of this work indicate that ZrMK is a promising active capping material for controlling P release from sediments in heavily polluted rivers.

  15. Erosion of sodium bentonite by flow and colloid diffusion

    NASA Astrophysics Data System (ADS)

    Moreno, Luis; Liu, Longcheng; Neretnieks, Ivars

    Smectite gel formed at the outer part of a bentonite buffer in granitic rock could expand into rock fractures with seeping water. Such a gel can release colloids into low ionic strength waters. In addition the gel/sol can itself slowly flow downstream when it has reached a low particle concentration sufficient to decrease the viscosity to allow flow. The erosion due to the combined effects of particle diffusion and gel/sol flow is modelled for a thin fracture into which the gel expands influenced by various forces between and on particles. Some of the forces such as the electrical double layer force and viscous force are strongly influenced by the ionic strength of the pore water. Changes in the ionic strength due to diffusion and dilution of ions in the expanding clay are modelled simultaneously with the gel expansion, flow of gel and colloid release to the seeping water. The model includes description of flow of the seeping fluid, which gradually turns from pure water to sol to more dense gel as the smectite source is approached. The model also describes expansion of the gel/sol and colloid release and flow and diffusion of ions in the system. The coupled models are solved using a numerical code. The results show that the gel will flow with a non-negligible flowrate when its volume fraction is below 1%, but that the erosion and loss of smectite is not much influenced by the concentration of sodium in the clay or in the approaching seeping water, if they are kept below the Critical Coagulation Concentration, CCC.

  16. Comparing citrated native, kaolin-activated, and tissue factor-activated samples and determining intraindividual variability for feline thromboelastography.

    PubMed

    Banerjee, Amrita; Blois, Shauna L; Wood, R Darren

    2011-11-01

    Thromboelastography (TEG) is a point-of-care whole blood test of hemostasis. While TEG is becoming more widely used in veterinary medicine, few studies describe the use of TEG in cats. The objectives of the current study were to: 1) document the range of TEG variables produced in healthy cats using 3 sample types (citrated native, kaolin-activated, and tissue factor-activated), and 2) determine if there was a significant difference between 2 separate samples obtained from individual healthy cats on the same day. Jugular venipuncture was performed in 20 cats, and citrated blood collected for TEG. TEG analysis was performed on citrated native, kaolin-activated, and tissue factor-activated blood for each sample. Two hours later, the procedure was repeated from the opposite jugular vein, yielding a total of 120 analyses. Reaction time (R), alpha angle (α), kappa value (κ), and maximum amplitude (MA) were recorded from each tracing. No significant differences were found between TEG tracings from the first and second venipuncture samples. Significant differences were found between sample types for R, α, κ, and MA. Means for citrated native/kaolin-activated/tissue factor-activated methods were R = 4.1/3.7/0.6 min; κ = 2.5/1.8/2.2 min; α = 59.9/65.1/70.4 degrees; MA = 47.4/49.9/44.7 mm. A limitation of this study was the small number of cats used. Thromboelastography analysis may be a suitable method of evaluating hemostasis in cats.

  17. Analysis of colloids erosion from the bentonite barrier of a high level radioactive waste repository and implications in safety assessment

    NASA Astrophysics Data System (ADS)

    Missana, Tiziana; Alonso, Ursula; Albarran, Nairoby; García-Gutiérrez, Miguel; Cormenzana, José-Luís

    To investigate the dominant mechanisms of colloid formation from compacted and confined bentonite innovative experiments were conducted. Chemical or physical processes that can affect the erosion of the bentonite surface were analyzed (ionic strength of the water, Ca in the water and in the exchange complex of the clay, dry density of the clay and presence of a water flow rate at the bentonite surface). Hydration, swelling and extrusion of clay into pores or fractures are primary steps for the formation of free colloidal particles in the aqueous phase, and the chemistry of the clay/water system is the most important parameter controlling the generation and stability of colloids. Ca-bentonite formed colloids quantities below the detection limit of our techniques, even in deionised water, but a percentage of Na approximately 20-30% in the clay exchange complex, as that present in the FEBEX bentonite, is enough to allow the formation of colloidal particles in quantities very similar to those produced by the Na-bentonite. The results for bentonite colloid generation obtained at a laboratory scale allowed the estimation of a range of colloid generation rates under different chemical conditions. Results were compared with in situ experimental investigations carried out at the FEBEX gallery emplaced in a granite massif at the Grimsel Test Site (Switzerland). The quantitative analysis of laboratory and in situ data can be used as input for models and performance assessment (PA) of high level radioactive waste (HLRW) repositories.

  18. Impact of environmental conditions on the sorption behavior of Pb(II) in Na-bentonite suspensions.

    PubMed

    Yang, Shitong; Zhao, Donglin; Zhang, Hui; Lu, Songsheng; Chen, Lei; Yu, Xianjin

    2010-11-15

    In this study, a local bentonite from Lin'an county (Zhejiang province, China) was converted to Na-purified form and the Na-bentonite sample was characterized by using FTIR and XRD to determine its chemical constituents and micro-structure. The removal of lead from wastewaters by Na-bentonite was studied as a function of various environmental parameters such as contact time, pH, ionic strength, foreign ions, humic substances and temperature under ambient conditions. The results indicated that the sorption of Pb(II) on Na-bentonite was strongly dependent on pH and ionic strength. The Langmuir, Freundlich and D-R models were used to simulate the sorption isotherms of Pb(II) at three different temperatures of 298, 318 and 338 K. The thermodynamic parameters (ΔH°, ΔS° and ΔG°) calculated from the temperature dependent sorption isotherms indicated that the sorption process of Pb(II) on Na-bentonite was endothermic and spontaneous. At low pH, the sorption of Pb(II) was dominated by outer-sphere surface complexation and ion exchange with Na(+)/H(+) on Na-bentonite surfaces, whereas inner-sphere surface complexation was the main sorption mechanism at high pH. From the experimental results, it is possible to conclude that Na-bentonite has good potentialities for cost-effective disposal of lead bearing wastewaters.

  19. [Mechanism and impact for microwave-enhanced integrative sorption of dye to mixture of surfactant and bentonite from water].

    PubMed

    Li, Ji-Wu; Zhu, Li-Zhong; Cai, Wei-Jian

    2006-11-01

    Microwave-enhanced integrative sorption (MEIS) of dye to mixture of surfactant and bentonite was put forward. The order of factor for integrative method was obtained by the orthogonal experiment. The optimal conditions, properties, kinetics and mechanisms for microwave-enhanced integrative sorption of Neutral Red S-BR to bentonite from water were investigated. Comparative study on decolorization rates of Neutral Red S-BR by other sorption method and MEIS from water were conducted. It is concluded that the order of factor for integrative method is amount of surfactant, bentonite and microwave time. The optimal condition for MEIS is that the ratio of amount of bentonite and water is equal to 1/1 000, the concentration of cetylpyridinium chloride (CPC) is 120 mg/L (equivalent to 28% cation exchange capacity of bentonite) and microwave time is 60s. Comparative with organobentonite, the decolorization rates of Neutral Red S-BR to bentonite are greatly increased by MEIS at higher concentration of dye, amount of surfactant is greatly decreased, and the saturated sorption capacity and the reactive rate of sorption of dye to bentonite are greatly increased by microwave.

  20. Preparation and characterization Al3+-bentonite Turen Malang for esterification fatty acid (palmitic acid, oleic acid and linoleic acid)

    NASA Astrophysics Data System (ADS)

    Abdulloh, Abdulloh; Aminah, Nanik Siti; Triyono, Mudasir, Trisunaryanti, Wega

    2016-03-01

    Catalyst preparation and characterization of Al3+-bentonite for esterification of palmitic acid, oleic acid and linoleic acid has been done. Al3+-bentonite catalyst was prepared from natural bentonite of Turen Malang through cation exchange reaction using AlCl3 solution. The catalysts obtained were characterized by XRD, XRF, pyridine-FTIR and surface area analyser using the BET method. Catalyst activity test of Al3+-bentonite for esterification reaction was done at 65°C using molar ratio of metanol-fatty acid of 30:1 and 0.25 g of Al3+-bentonite catalyst for the period of ½, 1, 2, 3, 4 and 5 hours. Based on the characterization results, the Al3+-bentonite Turen Malang catalyst has a d-spacing of 15.63 Ǻ, acid sites of Brönsted and Lewis respectively of 230.79 µmol/g and 99.39 µmol/g, surface area of 507.3 m2/g and the average of radius pore of 20.09 Å. GC-MS analysis results of the oil phase after esterification reaction showed the formation of biodiesel (FAME: Fatty acid methyl ester), namely methyl palmitate, methyl oleate and methyl linoleate. The number of conversions resulted in esterification reaction using Al3+-bentonite Turen Malang catalyst was 74.61%, 37.75%, and 20, 93% for the esterification of palmitic acid, oleic acid and linoleic acid respectively.

  1. UV curable polyester polyol acrylate/bentonite nanocomposites: synthesis, characterization, and drug release.

    PubMed

    Thatiparti, Thimma Reddy; Tammishetti, Shekharam; Nivasu, Muram V

    2010-01-01

    Polyesterpolyolacrylate/bentonite nanocomposites, capable of in situ photo polymerization, were synthesized and characterized. The organically modified bentonite clay was prepared by an ion exchange process, in which sodium ions were replaced by alkyl ammonium ions. Organo modification of bentonite was confirmed from X-ray diffraction and fourier transform-infrared data. Microstructures were characterized by XRD data and transmission electron microscopy (TEM). Both XRD data and TEM images of polyester polyol acrylate/organo modified bentonite nanocomposites indicated that most of silicate layers were intercalated into the acrylate matrix. The resulting nanocomposites were characterized by gel content, water equilibrium swell, tensile strength, and in vitro degradation. The results showed that water equilibrium swell and in vitro degradation of these nanocomposites decreased with increase in the clay content. The tensile strength of these nanocomposites also increased with increase in the clay content. Release of two model drugs namely sulfamethoxazole and diclofenac sodium (DS) from these nanocomposites was studied in phosphate buffer saline pH = 7.4 at 37 degrees C. The drug release studies showed that sulfamethoxazole released slower than DS from polyester polyol acrylate nanocomposites. Therefore, these materials may be useful for mucoadhesive drug carriers and other biomedical applications.

  2. Degradation of geocomposite clay liners due to geochemical reactions in sodium bentonite

    SciTech Connect

    Sivalingam, S. )

    1993-03-01

    Geocomposite clay liners are commonly used as permeability barriers in landfills, hazardous waste facilities, overlying caps, secondary containments for tank farms, industrial and decorative lagoons and as slurry walls. Most recent geocomposite liners are manufactured using sodium bentonite sandwiched between two polypropylene geotextile. Na-bentonite is widely used because of its high swelling capacity, its low permeability when hydrated, high cation exchange capacity and low cost. Na-bentonite used in geo-composite liners showed degradation due to numerous geochemical reactions within the clays and cover materials at the site. The clays within the liner has undergone changes in pH from pH9 to pH5, dehydration and replacement of interlayer Na by Ca and Mg ions. Cation exchange capacity (CEC) reduced from 110 meq/100 gm to 72.5 meq/100 gm. The reduction in CEC maybe attributed to transformation of clay minerals. Analytical electron microscopy data show a decrease in Na and an increase in Ca and Mg. This observation is confirmed by the results obtained from cation exchange capacity measurements and XRD. These changes in Na-bentonite increased the permeability of the liner by 2 to 4 orders of magnitude and caused the liners to leak.

  3. Geotechnical characteristics of bentonite/sandy silt mixes for use in waste disposal sites

    SciTech Connect

    Abeele, W.V.

    1984-06-01

    The coefficient of consolidation for bentonite/sandy silt ratios of 0.04 to 0.14 decreases inversely proportional with the square of that ratio, whereas the compression index, the swelling index, and the permeability change index increase with increasing bentonite ratio. A strong relationship also exists between the void ratio and the logarithm of the applied stress for any given bentonite ratio. The empirical linear relationship between the void ratio and the logarithm of the applied stress, developed by Taylor, is excellent and enables us to limit the evaluation of conductivity at any void ratio to the measurement of the initial and the desired void ratio, the initial conductivity, and the permeability change index. This allows us to read directly, for a given bentonite ratio, the void ratio (or compaction) needed so that a required hydraulic conductivity will prevail. This is crucial in the choice of materials or mixes to be used in a wick system where an established differentiation in hydraulic conductivity is desirable.

  4. Effect of aluminosilicates and bentonite on aflatoxin-induced developmental toxicity in rat.

    PubMed

    Abdel-Wahhab, M A; Nada, S A; Amra, H A

    1999-01-01

    Numerous studies have established that aflatoxin is a potent developmental toxin in animals. Previous research has demonstrated that a phyllosilicate clay, hydrated sodium calcium aluminosilicate (HSCAS or Novasil), tightly binds and immobilizes aflatoxins in the gastrointestinal tract of animals and markedly reduces the bioavailability and toxicity of aflatoxin. Our objective in this study was to utilize the pregnant rat as an in vivo model to compare the potential of HSCAS and bentonite to prevent the developmental toxicity of aflatoxin. Aluminosilicates (HSCAS) and bentonite were added to the diet at a level of 0.5% (w/w) and fed to the pregnant rat throughout pregnancy (i.e. days 0-20). Test animals were fed an aflatoxin-contaminated diet (2.5 mg kg(-1) diet) with or without sorbents during gestation days 6-15. Evaluations of toxicity were performed on day 20. These included maternal (mortality, body weights, feed intake and litter weights), developmental (embryonic resorptions and fetal body weights) and biochemical (ALT, AST and AP) evaluations. Sorbents alone were not toxic and aflatoxin alone resulted in significant maternal and developmental toxicity. Animals treated with phyllosilicate (plus aflatoxin) were comparable to controls following evaluations for resorptions, live fetuses and fetal body weights, as well as biochemical parameters. While bentonite plus aflatoxin resulted in significant reduction in fetal body weight, none of the fetuses from HSCAS or bentonite plus aflatoxin-treated groups had any gross, internal soft tissue or major skeletal malformations.

  5. Adsorption of the organic fraction of a tannery sludge by means of organophilic bentonite.

    PubMed

    Cioffi, R; Costanzo, S; Maffucci, L; Santoro, L

    2001-01-01

    Two different organophilic bentonites obtained by cationic exchange with benzyldimethyloctadecylammonium chloride and trimethyloctadecylammonium chloride have been used to adsorb the organic fraction of a tannery sludge. The exchange process was carried out to different extents to obtain bentonite samples with different organophilicities and different interlayer spacings. Before adsorption, the organic matter was extracted by contacting the sludge with a Ca(OH)2 saturated solution. The adsorption capacity was found to increase with the amount of ammonium salt exchanged for both bentonites, but the one exchanged with benzyldimethyloctadecylammonium chloride proved to be more active: up to about 80% TOC could be removed from the contacting solution. The adsorption of the organic matter caused a further increase of the bentonite interlayer spacing. In both cases, the adsorption isotherms were found to be of cooperative type, due to weak adsorbent-adsorbate interactions at low loading followed by increasing adsorbate-adsorbate interactions at increasing loading. The results may be applied to tannery sludge stabilization by cementitious systems.

  6. Biochar, Bentonite and Zeolite Supplemented Feeding of Layer Chickens Alters Intestinal Microbiota and Reduces Campylobacter Load

    PubMed Central

    Prasai, Tanka P.; Walsh, Kerry B.; Bhattarai, Surya P.; Midmore, David J.; Van, Thi T. H.; Moore, Robert J.; Stanley, Dragana

    2016-01-01

    A range of feed supplements, including antibiotics, have been commonly used in poultry production to improve health and productivity. Alternative methods are needed to suppress pathogen loads and maintain productivity. As an alternative to antibiotics use, we investigated the ability of biochar, bentonite and zeolite as separate 4% feed additives, to selectively remove pathogens without reducing microbial richness and diversity in the gut. Neither biochar, bentonite nor zeolite made any significant alterations to the overall richness and diversity of intestinal bacterial community. However, reduction of some bacterial species, including some potential pathogens was detected. The microbiota of bentonite fed animals were lacking all members of the order Campylobacterales. Specifically, the following operational taxonomic units (OTUs) were absent: an OTU 100% identical to Campylobacter jejuni; an OTU 99% identical to Helicobacter pullorum; multiple Gallibacterium anatis (>97%) related OTUs; Bacteroides dorei (99%) and Clostridium aldenense (95%) related OTUs. Biochar and zeolite treatments had similar but milder effects compared to bentonite. Zeolite amended feed was also associated with significant reduction in the phylum Proteobacteria. All three additives showed potential for the control of major poultry zoonotic pathogens. PMID:27116607

  7. Removal of polycyclic aromatic hydrocarbons (PAHs) from inorganic clay mineral: Bentonite.

    PubMed

    Karaca, Gizem; Baskaya, Hüseyin S; Tasdemir, Yücel

    2016-01-01

    There has been limited study of the removal of polycyclic aromatic hydrocarbons (PAHs) from inorganic clay minerals. Determining the amount of PAH removal is important in predicting their environmental fate. This study was carried out to the degradation and evaporation of PAHs from bentonite, which is an inorganic clay mineral. UV apparatus was designed specifically for the experiments. The impacts of temperature, UV, titanium dioxide (TiO2), and diethylamine (DEA) on PAH removal were determined. After 24 h, 75 and 44 % of ∑12 PAH in the bentonite were removed with and without UV rays, respectively. DEA was more effective as a photocatalyst than TiO2 during UV application. The ∑12 PAH removal ratio reached 88 % with the addition of DEA to the bentonite. It was concluded that PAHs were photodegraded at high ratios when the bentonite samples were exposed to UV radiation in the presence of a photocatalyst. At the end of all the PAH removal applications, higher evaporation ratios were obtained for 3-ring compounds than for heavier ones. More than 60 % of the amount of ∑12 PAH evaporated consisted of 3-ring compounds.

  8. Enhanced sorption of naphthalene and nitroaromatic compounds to bentonite by potassium and cetyltrimethylammonium cations.

    PubMed

    Chen, Baoliang; Huang, Wenhai; Mao, Jiefei; Lv, Shaofang

    2008-10-01

    Sorption of naphthalene, p-nitrotoluene, nitrobenzene and m-dinitrobenzene from water to original bentonite, original bentonite in KCl solutions, and an organobentonite (i.e., 100CTMAB) was compared. The affinities of sorbates with original bentonite were extremely weak and similar (sorption coefficient (K(d))=0.41-0.94 mL/g) regardless of their properties and structures. Sorption was dramatically enhanced by 100CTMAB due to strong retention of CTMA(+)-derived organic phase and the exposed-siloxane surfaces. The resultant K(d) increased by 5360, 780, 40 and 200 times, respectively, for naphthalene, p-nitrotoluene, nitrobenzene and m-dinitrobenzene, reversed with their aqueous solubility. The presence of K(+) promoted sorption of nitroaromatic compounds (50-400 times). The enhanced-mechanism for nitrobenzene at low concentrations and p-nitrotoluene was derived mainly from weak van der Waals interaction between aromatic rings and siloxane surfaces, while for nitrobenzene at high concentrations and m-dinitrobenzene the mechanisms were attributed to primary complexation of -NO(2) group with K(+) and then strong interactions by electron donor-acceptor. Sorption of m-dinitrobenzene enhanced linearly with K(+) concentrations of 0.005-0.20 mol/L, and overshadowed the role of 100CTMAB when K(+)>0.5 mol/L. These will eventually facilitate the application of modified-bentonite to abate pollutants in environments.

  9. Characteristics of cesium ion sorption from aqueous solution on bentonite- and carbon nanotube-based composites.

    PubMed

    Yang, Shubin; Han, Cho; Wang, Xiangke; Nagatsu, Masaaki

    2014-06-15

    The technology development of Cs(+) capture from aqueous solution is crucial for the disposal of nuclear waste and still remains a significant challenge. Previous researches have been proven that ion exchanges with the cations and hydroxyl exchange are the main sorption mechanisms for Cs(+). Therefore, how important are the cation exchange and the hydroxyl exchange mechanisms to Cs(+) sorption? And whether can we improve the sorption capacity of the material by increasing the amount of hydroxyl groups? With these in mind, we herein designed the chitosan-grafted carbon nanotubes (CS-g-CNTs) and the chitosan-grafted bentonite (CS-g-bentonite) by plasma-induced grafting method. The interactions of Cs(+) with CNTs, bentonite, CS-g-CNTs and CS-g-bentonite composites were investigated. The sorption of Cs(+) is mainly dominated by strong cation exchange in monovalent Group I and divalent Group II. And the cation-exchange mechanism is much more effective than the hydroxyl group exchange. The effect of hydroxyl groups is dependent on the property of the matrix. We cannot improve the Cs adsorption capacity of material for Cs(+) only by increasing the amount of hydroxyl groups in any case. The spatial structure and the cation-exchange capacity of the material are important factors for choosing the sorbent for Cs(+) removal from radioactive waste water.

  10. Removal of chromium (VI) from wastewater using bentonite-supported nanoscale zero-valent iron.

    PubMed

    Shi, Li-na; Zhang, Xin; Chen, Zu-liang

    2011-01-01

    Bentonite-supported nanoscale zero-valent iron (B-nZVI) was synthesized using liquid-phase reduction. The orthogonal method was used to evaluate the factors impacting Cr(VI) removal and this showed that the initial concentration of Cr(VI), pH, temperature, and B-nZVI loading were all importance factors. Characterization with scanning electron microscopy (SEM) validated the hypothesis that the presence of bentonite led to a decrease in aggregation of iron nanoparticles and a corresponding increase in the specific surface area (SSA) of the iron particles. B-nZVI with a 50% bentonite mass fraction had a SSA of 39.94 m(2)/g, while the SSA of nZVI and bentonite was 54.04 and 6.03 m(2)/g, respectively. X-ray diffraction (XRD) confirmed the existence of Fe(0) before the reaction and the presence of Fe(II), Fe(III) and Cr(III) after the reaction. Batch experiments revealed that the removal of Cr (VI) using B-nZVI was consistent with pseudo first-order reaction kinetics. Finally, B-nZVI was used to remediate electroplating wastewater with removal efficiencies for Cr, Pb and Cu > 90%. Reuse of B-nZVI after washing with ethylenediaminetetraacetic acid (EDTA) solution was possible but the capacity of B-nZVI for Cr(VI) removal decreased by approximately 70%.

  11. Sensitivity analysis of radionuclide migration in compacted bentonite: a mechanistic model approach

    NASA Astrophysics Data System (ADS)

    Ochs, Michael; Lothenbach, Barbara; Shibata, Masahiro; Sato, Haruo; Yui, Mikazu

    2003-03-01

    Mechanistic model calculations for the migration of Cs, Ra, Am and Pb in compacted bentonite have been carried out to evaluate sensitivities with respect to different parameter variations. A surface chemical speciation/electric double layer model is used to calculate: (i) porewater composition and radionuclide speciation in solution and at the bentonite surface, yielding the distribution of mobile and sorbed species and (ii) interaction of diffusing species with negatively charged pore walls to obtain diffusion parameters. The basic scenario considers the interaction of compacted bentonite with a fresh-type groundwater; variations include the presence of bentonite impurities and saline groundwater. It is shown that these scenarios result in significant variations of porewater composition that affect migration via three mechanisms that can partly compensate each other: (1) effects on sorption through radionuclide complexation in solution, and competition of major cations for surface sites; (2) changes in radionuclide solution speciation leading to different diffusing species under different conditions; (3) effects on diffusion through changes in the electric double layer properties of the clay pores as a function of ionic strength.

  12. Enhancing the sorption capacity of CTMA-bentonite by simultaneous intercalation of cationic polyacrylamide.

    PubMed

    Wang, Tong; Zhu, Jianxi; Zhu, Runliang; Ge, Fei; Yuan, Peng; He, Hongping

    2010-06-15

    The saturated level of cationic exchange capacity (CEC) of bentonite by organic cations can significantly influence the sorption capacity of the resulting organobentonites. In this work cationic polyacrylamide (CPAM) was applied to saturate part of the CEC of the cetyltrimethylammonium (CTMA) modified bentonite, with the aim to enhance their sorption capacity. XRD was applied to investigate the basal spacings of the organobentonites with and without CPAM, and the sorption characteristics of the organobentonites towards phenol and nitrobenzene to CTMA-bentonite was also studied. The XRD characterization results showed that the resulting organobentonites (C/P-Bt) had larger basal spacings than the CTMA modified bentonite (C-Bt), which indicated that both CPAM and CTMA could intercalate into the interlayer spaces of C/P-Bt. The saturated CEC of C/P-Bt increased with the intercalated amounts of CPAM. The sorption coefficients (K(d)) of phenol and nitrobenzene on C/P-Bt were shown to first increase with the saturated CEC until the maximum, and then began to decrease as the saturated CEC further increased. The maximum increase of K(d) reached 41% and 23% for phenol and nitrobenzene, respectively, which could be ascribed to the enhanced affinity of the adsorbed CTMA aggregates towards the sorbates. Results of this work showed that the simultaneous intercalation of CPAM could be a novel method to enhance the sorption capacity of the traditional organobentonites.

  13. Retention of heavy metal ions in bentonites from Grau Region (Northern Peru)

    NASA Astrophysics Data System (ADS)

    Ayala, J.; Vega, J. L.; Alvarez, R.; Loredo, J.

    2008-01-01

    Experimental studies on the retention of metals (Cu, Co, Ni, and Zn) in bentonite samples from the Grau Region (Northern Peru) have been accomplished using monometallic, bimetallic, trimetallic, and tetrametallic solutions. Parameters such as pH and concentration of dissolved metals and organic compounds have been evaluated by means of batch adsorption experiments. Adsorption rates indicate the suitability of these bentonites in the environmental industry for heavy metals retention purposes. In addition to its quality as physical barrier to avoid the dispersion through the environment of polluted leachates, bentonite, due to its high cation exchange capacity, can act also as a chemical barrier, protecting the quality of surface and groundwater systems, while limiting the migration of heavy metals in solid residues or sludge stocked in security landfills. Adsorption rates of tested bentonites were proved to decrease when concentrations of both metal and organic compounds, as well as the number of ionic species, increase in solution; additionally, lower metal removal rates from solution were obtained when extremely acidic conditions were achieved.

  14. Effects of radiation and temperature on iodide sorption by surfactant-modified bentonite.

    PubMed

    Choung, Sungwook; Kim, Minkyung; Yang, Jung-Seok; Kim, Min-Gyu; Um, Wooyong

    2014-08-19

    Bentonite, which is used as an engineered barrier in geological repositories, is ineffective for sorbing anionic radionuclides because of its negatively charged surface. This study modified raw bentonite using a cationic surfactant (i.e., hexadecyltrimethylammonium [HDTMA]-Br) to improve its sorption capability for radioactive iodide. The effects of temperature and radiation on the iodide sorption of surfactant-modified bentonite (SMB) were also evaluated under alkaline pH condition similar to that found in repository environments. Different amounts of surfactant, equivalent to the 50, 100, and 200% cation-exchange capacity of the bentonite, were used to produce the HDTMA-SMB for iodide sorption. The sorption reaction of the SMB with iodide reached equilibrium rapidly within 10 min regardless of temperature and radiation conditions. The rate of iodide sorption increased as the amount of the added surfactant was increased and nonlinear sorption behavior was exhibited. However, high temperature and γ-irradiation ((60)Co) resulted in significantly (∼2-10 times) lower iodide Kd values for the SMB. The results of FTIR, NMR, and XANES spectroscopy analysis suggested that the decrease in iodide sorption may be caused by weakened physical electrostatic force between the HDTMA and iodide, and by the surfactant becoming detached from the SMB during the heating and irradiation processes.

  15. Effects of Radiation and Temperature on Iodide Sorption by Surfactant-Modified Bentonite

    SciTech Connect

    Choung, Sungwook; Kim, Min Kyung; Yang, Jungseok; Kim, Min-Gyu; Um, Wooyong

    2014-08-04

    Bentonite, which is used as an engineered barrier in geological repositories, is ineffective for sorbing anionic radionuclides because of its negatively charged surface. This study modified raw bentonite using a cationic surfactant (i.e., hexadecyltrimethylammonium [HDTMA]-Br) to improve its sorption capability for radioactive iodide. The effects of temperature and radiation on the iodide sorption of surfactant-modified bentonite (SMB) were evaluated under alkaline pH condition similar to that found in repository environments. Different amounts of surfactant, equivalent to the 50, 100, and 200% cation-exchange capacity of the bentonite, were used to produce the HDTMA-SMB for iodide sorption. The sorption reaction of the SMB with iodide reached equilibrium rapidly within 10 min regardless of temperature and radiation conditions. The rate of iodide sorption increased as the amount of the added surfactant was increased and nonlinear sorption behavior was exhibited. However, high temperature and γ-irradiation (60Co) resulted in significantly (~2–10 times) lower iodide Kd values for the SMB. The results of Fourier transform infrared spectroscopy analysis suggested that the decrease in iodide sorption may be caused by weakened physical electrostatic force between the HDTMA and iodide, and by the surfactant becoming detached from the SMB during the heating and irradiation processes.

  16. Stabilization of chloro-organics using organophilic bentonite in a cement-blast furnace slag matrix.

    PubMed

    Cioffi, R; Maffucci, L; Santoro, L; Glasser, F P

    2001-01-01

    The application of cement-based stabilisation/solidification treatment to organic-containing wastes is made difficult by the adverse effect of organics on cement hydration. The use of organophilic clays as pre-solidification adsorbents of the organic compounds can reduce this problem because of the high adsorption power of these clays and their compatibility with the cementitious matrix. This work presents an investigation of the effect on hydration kinetics, physico-mechanical properties and leaching behaviour of cement-based solidified waste forms containing 2-chlorophenol and 1-chloronapthalene adsorbed on organophilic bentonites. These were prepared by cation exchange with benzyldimethyloctadecylammonium chloride and trimethyloctadecylammonium chloride. The binder was a 30% pozzolanic cement, 70% granulated blast furnace slag mixture. Several binder-to-bentonite ratios and different concentrations of the organics on the bentonite were used. Kinetics of hydration were studied by measurement of chemically bound water and by means of thermal and calorimetric analyses. Microstructure and other physico-mechanical properties of the solidified forms were studied by means of mercury intrusion porosimetry, scanning electron microscopy and unconfined compressive strength measurement. Leaching was checked by two different leaching tests: one dynamic, on monolithic samples, and the other static, on powdered samples. This study indicates that the incorporation of the organic-loaded bentonite in the binder matrix causes modifications in the hardened samples by altering cement hydration. The effects of the two organic contaminants are differentiated.

  17. A comparison between two hydrothermally formed extensional environment related kaolin deposits: Balikesir-Duvertepe, Turkey and Kline Mountain, Sierra County, New Mexico

    SciTech Connect

    Isik, I.; Clark, K.F. . Dept. of Geological Sciences)

    1992-01-01

    Economically important and hydrothermally formed kaolin deposits are often found within rift lithologic units, formed as a result of interaction of physical and geochemical processes in the extensional environment. The kaolin deposits of Balikesir--Duvertepe, Turkey and Kline Mountain, Sierra County, New Mexico, studied herein, are examples of this type. The Balikesir--Duvertepe district has been known as the most productive kaolin district in Turkey. Total reserves are estimated at 15 million metric tons. Located in the active Simav Graben produced by the subduction of the African Plate under the Aegean region, the kaolin deposits occur irregularly and variably in quality as a result of hydrothermal alteration of Neogene tuffs. The Kline Mountain kaolin deposit was formed as a result of advanced argillic alteration on the southeastern edge of the Mogollon--Datil volcanic field, which is related to the extensional environment of Basin and Range province and the Rio Grande rift. Its reserve is reported as 200 million metric tons of altered tuffs. The two deposits show striking similarities: extensional related rock units, intense in situ hydrothermal alteration, mineral content, seismic activity, alunite contamination, chemical composition, and intense silicification. The deposits also display some differences: regional climate, the intensity of hydrothermal alteration and the elapsed time causing relatively complete replacement in the Turkish deposit compared to that in NM. The Balikesir--Duvertepe district has been the center of kaolin marketing for use chiefly in ceramic, paper, and white cement, while the Kline Mountain kaolin had been exploited primarily for paper and ceramic tile as a coating; and in the oil industry as a filler and absorbent material.

  18. Reaction and Diffusion of Cementitious Water in Bentonite: Results of `Blind' Modelling

    NASA Astrophysics Data System (ADS)

    Watson, C.; Hane, K.; Savage, D.; Benbow, S.; Cuevas, J.; Fernandez, R.

    2009-04-01

    The potential deleterious geochemical interactions of clay with cement/concrete may provide a constraint on the use of the latter material in deep geological disposal facilities for radioactive wastes. Consequently, it is important to have a fundamental understanding of these interactions to be able to assess their likely impact over the long timescales appropriate to the isolation of radioactive wastes from the human environment. Here, a laboratory experiment investigating the effects of cementitious water diffusing through bentonite has been simulated using a coupled reactive-transport geochemical modelling code. The modelling study was carried out before the results of the experiments were available, as an exercise in ‘blind' modelling. A sensitivity study was carried out to investigate uncertainties associated with a number of input parameters, such as the precise nature of kinetic and ion-exchange reactions, diffusion coefficients, pore water composition, and montmorillonite dissolution models. The experiments used two types of fluid; one saturated with calcium hydroxide showed little mineralogical alteration, which was predicted by the computer simulations. A high pH K-Na-OH-based water however, caused alteration (pore blocking by hydrotalcite, gibbsite and brucite growth) to a depth of 2 mm in the bentonite after a period of 1 year. Experimental evidence showed that ion exchange of Mg-montmorillonite to K-montmorillonite was not confined to this thin region however, and was found to extend throughout the whole of the bentonite sample. The pore blocking by mineral precipitation and movement of ion exchange fronts through the bentonite were accurately simulated by the model. The choice of dissolution model for montmorillonite played an important role in the outcome of the simulations. Of the cases considered in the sensitivity study, that employing the so-called ‘Yamaguchi model' was clearly the best match, exhibiting all the main characteristics of the

  19. Experimental characterization of cement-bentonite interaction using core infiltration techniques and 4D computed tomography

    NASA Astrophysics Data System (ADS)

    Dolder, F.; Mäder, U.; Jenni, A.; Schwendener, N.

    Deep geological storage of radioactive waste foresees cementitious materials as reinforcement of tunnels and as backfill. Bentonite is proposed to enclose spent fuel drums, and as drift seals. The emplacement of cementitious material next to clay material generates an enormous chemical gradient in pore water composition that drives diffusive solute transport. Laboratory studies and reactive transport modeling predict significant mineral alteration at and near interfaces, mainly resulting in a decrease of porosity in bentonite. The goal of this project is to characterize and quantify the cement/bentonite skin effects spatially and temporally in laboratory experiments. A newly developed mobile X-ray transparent core infiltration device was used, which allows performing X-ray computed tomography (CT) periodically without interrupting a running experiment. A pre-saturated cylindrical MX-80 bentonite sample (1920 kg/m3 average wet density) is subjected to a confining pressure as a constant total pressure boundary condition. The infiltration of a hyperalkaline (pH 13.4), artificial OPC (ordinary Portland cement) pore water into the bentonite plug alters the mineral assemblage over time as an advancing reaction front. The related changes in X-ray attenuation values are related to changes in phase densities, porosity and local bulk density and are tracked over time periodically by non-destructive CT scans. Mineral precipitation is observed in the inflow filter. Mineral alteration in the first millimeters of the bentonite sample is clearly detected and the reaction front is presently progressing with an average linear velocity that is 8 times slower than that for anions. The reaction zone is characterized by a higher X-ray attenuation compared to the signal of the pre-existing mineralogy. Chemical analysis of the outflow fluid showed initially elevated anion and cation concentrations compared to the infiltration fluid due to anion exclusion effects related to compaction of

  20. Study on the Surface-Physicochemical-Property Changing of Bentonite by Adapting a New Soil Stabilizer

    NASA Astrophysics Data System (ADS)

    Huang, Wei; Xiang, Wei; Lang, Linzhi; Cui, Deshan

    2015-04-01

    Surface-physicochemical-property of clays has been proved to have direct influence on its mechanic behavior. Specific surface area (SSA) is one of the most important factors for surface-physicochemical-property assessment. The smaller SSA tends higher strength (shear strength, unconfined compressive strength and tensile strength) under different water contents of soil. In this paper, a new soil stabilizer (Tung oil-based sulfonated) is developed and applied to improve the properties of Ca-bentonite. The differences of specific surface area, fractal dimension and micro geometric morphology between raw Ca-bentonite samples and modified ones are investigated based on the data acquired from water vapor, nitrogen adsorption experiments and SEM experiments. Results show that the SSA including external SSA and total SSA of treated samples decrease largely and apparently when compared to that of the raw samples. Furthermore, the higher volume ratio between soil stabilizer and water, the more decrease in SSA. Compared to the ones of raw Ca-bentonite, the external SSA and total SSA of the modified Ca-bentonite samples decrease by 48.5% and 25.2%, respectively, when the volume ratio was 1:50. This result implies that the connection of montmorillonite particles becomes more tightly after the treatment by the soil stabilizer. In addition, an obvious decreasing trend is found in fractal dimension by analysis of water vapor adsorption isotherms. This finding indicates that the pore surface tends to be smoother by the chemical action among particles bonds, more condensable in aggregates and shorter space between the interlayer of montmorillonite. SEM results display that the new soil stabilizer developed a quantity of lamellar aggregates but did not change the structure of montmorillonite. Based on all mentioned above, the results of fractal dimension analysis are verified. Consequently, this study shows that the new soil stabilizer (Tung oil-based sulfonated) has obvious effects

  1. 1H NMR relaxation of water: a probe for surfactant adsorption on kaolin.

    PubMed

    Totland, Christian; Lewis, Rhiannon T; Nerdal, Willy

    2011-11-01

    In this study, (1)H NMR is used to investigate properties of sodium dodecyl sulfate (SDS), tetradecyl trimethyl ammonium bromide (TTAB), and dodecyl trimethyl ammonium bromide (DTAB) adsorbed on kaolin by NMR T(1) and T(2) measurements of the water proton resonance. The results show that adsorbed surfactants form a barrier between sample water and the paramagnetic species present on the clay surface, thus significantly increasing the proton T(1) values of water. This effect is attributed to the amount of adsorbed surfactants and the arrangement of the surfactant aggregates. The total surface area covered by the cationic (DTAB and TTAB) and anionic (SDS) surfactants could be estimated from the water T(1) data and found to correspond to the fractions of negatively and positively charged surface area, respectively. For selected samples, the amount of paramagnetic species on the clay surface was reduced by treatment with hydrofluoric (HF) acid. For these samples, T(1) and T(2) measurements were taken in the temperature range 278-338 K, revealing detailed information on molecular mobility and nuclear exchange for the sample water that is related to surfactant behavior both on the surface and in the aqueous phase.

  2. Effect of extrusion rate on morphology of Kaolin/PolyEtherSulfone (PESf) membrane precursor

    NASA Astrophysics Data System (ADS)

    Misaran, M. S.; Sarbatly, R.; Bono, A.; Rahman, M. M.

    2016-11-01

    This study aims to investigate the influence of apparent viscosity induced by spinneret geometry and extrusion rate on morphology of Kaolin/PESf hollow fiber membranes. Different extrusion rates at two different rheology properties were introduced on a straight and conical spinneret resulting in various shear rates. The hollow fiber membrane precursors were spun using the wet spinning method to decouple the effect of shear and elongation stress due to gravity stretched drawing. The morphology of the spun hollow fiber was observed under Scanning Electron Microscope (SEM) and the overall porosity were measured using mercury intrusion porosimeter. Shear rate and apparent viscosity at the tip of the spinneret annulus were simulated using a computational fluid dynamics package; solidworks floworks. Simulation data shows that extrusion rate increment increases the shear rate at the spinneret wall which in turn reduce the apparent viscosity; consistent with a non Newtonian shear thinning fluid behavior. Thus, the outer finger-like region grows as the shear rate increases. Also, overall porosity of hollow fiber membrane decreases with extrusion rate increment which is caused by better molecular orientation; resulting in denser hollow fiber membrane. Thin outer finger-like region is achieved at low shear experience of 109.55 s-1 via a straight spinneret. Increasing the extrusion rate; thus shear rate will cause outer finger-like region growth which is not desirable in a separation process.

  3. The kinetics of Al-Si spinel phase crystallization from calcined kaolin

    NASA Astrophysics Data System (ADS)

    Ptáček, Petr; Šoukal, František; Opravil, Tomáš; Nosková, Magdaléna; Havlica, Jaromír; Brandštetr, Jiří

    2010-11-01

    The crystallization of Al-Si spinel from medium ordered kaolin with high content of kaolinite was investigated using the differential thermal analysis (DTA). The apparent activation energy of the process was evaluated from the dependence of exothermic peak of crystallization on heating rate. Within the applied interval of heating rate (1-40 K min -1) the temperature of peak maximum increases from initial value of 1220.5 K in about 54.2 K. The apparent activation energy of the process 856±2 kJ mol -1was calculated using the Kissinger equation. The growth morphology of Al-Si spinel crystal was evaluated from the Avrami parameter. The average value of morphology parameter determined within the observed interval of heating rate is 3.08±0.03. This value indicates that crystallization mechanism of Al-Si spinel phase proceeds by bulk nucleation of the new phase with constant number of nuclei and that the three-dimensional growth of crystals is controlled by the reaction rate on the phases interface.

  4. Synchrotron Speciation of Silver and Zinc Oxide Nanoparticles Aged in a Kaolin Suspension

    SciTech Connect

    Scheckel, Kirk G.; Luxton, Todd P.; El Badawy, Amro M.; Impellitteri, Christopher A.; Tolaymat, Thabet M.

    2010-07-23

    Assessments of the environmental fate and mobility of nanoparticles must consider the behavior of nanoparticles in relevant environmental systems that may result in speciation changes over time. Environmental conditions may act on nanoparticles to change their size, shape, and surface chemistry. Changing these basic characteristics of nanoparticles may result in a final reaction product that is significantly different than the initial nanomaterial. As such, basing long-term risk and toxicity on the initial properties of a nanomaterial may lead to erroneous conclusions if nanoparticles change upon release to the environment. The influence of aging on the speciation and chemical stability of silver and zinc oxide nanoparticles in kaolin suspensions was examined in batch reactors for up to 18 months. Silver nanoparticles remained unchanged in sodium nitrate suspensions; however, silver chloride was identified with the metallic silver nanoparticles in sodium chloride suspensions and may be attributed to an in situ silver chloride surface coating. Zinc oxide nanoparticles were rapidly converted via destabilization/dissolution mechanisms to Zn{sup 2+} inner-sphere sorption complexes within 1 day of reaction and these sorption complexes were maintained through the 12 month aging processes. Chemical and physical alteration of nanomaterials in the environment must be examined to understand fate, mobility, and toxicology.

  5. Mechanochemically induced synthesis of anorthite in MSWI fly ash with kaolin.

    PubMed

    Wu, Ching-Wei; Sun, Chang-Jung; Gau, Sue-Huai; Hong, Cheng-Lin; Chen, Cheng-Gang

    2013-01-15

    The process of mechanical milling has been found to effectively stabilize heavy metals in municipal solid waste incinerator (MSWI) fly ash, as well as to restrain the evaporation of heavy metals during thermo-treatment. This method is adopted in this study and the composition and degree of amorphization adjusted to improve the efficiency of crystalline anorthite synthesis. Different milling times (1, 5, 10 and 20 h) and different sintering temperatures (900, 950, 1000, 1100, 1200 and 1300 °C) are utilized. The extracted fly ash and kaolin (KEFA) were mixed to simulate an anorthite composite. The experimental results indicate that the degree of amorphization of the KEFA increased as the milling time increased. Furthermore, the synthesis of crystalline anorthite increased as the degree of amorphization increased. The milling process allowed a reduction in the synthesization temperature from 1300 °C to 950 °C. The heavy metals are sealed in during the liquid sintering phase, which reduces the amount of heavy metals released from the sintered specimens.

  6. Organic matter and nutrient accumulation in reclaimed kaolin mine soils of Georgia

    SciTech Connect

    Haddock, R.B.; Morris, L.A.; Hendrick, R.L.; Ogden, E.A.

    1996-12-31

    Deficiencies in soil nutrients, particularly nitrogen, commonly result from replacement of natural soil profiles by overburden low in organic matter and essential elements. Reclamation success depends largely upon creating nutrient reserves, establishing adequate nutrient cycles, and developing a functional soil profile. Loblolly pine (Pinus taeda L.) stand productivity and soil characteristics of reclaimed kaolin mines in Georgia were evaluated along a chronosequence. Estimated site index (age 25) ranged from 11.3 m on poor sites to 24.1 m on productive sites. Projected volume at age 25 ranged from 119 m{sup 3}/ha on poor sites to 280 m{sup 3}/ha on productive sites. These values indicate that growth on many mined lands is comparable to growth on adjacent non-mined lands. Soil profile development below the surface soil was nonexistent on all sites and differences in soil texture and color did not adequately explain observed differences in site productivity. Foliar deficiencies in phosphorus, potassium and several micronutrients suggest that availability of nutrients and potential mineralization explain the observed differences in site productivity.

  7. Effect of kaolin and copper based products and of starter cultures on green table olive fermentation.

    PubMed

    Randazzo, Cinzia L; Fava, Giovanni; Tomaselli, Filippo; Romeo, Flora V; Pennino, Giuseppe; Vitello, Euplio; Caggia, Cinzia

    2011-08-01

    In the present study table olives treated in field with kaolin and copper based products against "olive-fruit fly" were fermented using two selected strains of lactic acid bacteria (LAB). The fermentation process was monitored up to 260 days from brining through physico-chemical, microbiological and sensorial analyses. Results showed a dominance of LAB and yeasts and low level of Enterobacteriaceae counts throughout the whole process both in un-treated and treated samples. When investigating the effect of the single treatments on microbial dynamics, ANOVA results highlighted that copper based products affected significantly the control sample, while the sample inoculated with LAB starters maintained high level throughout the process, guaranteeing the fermentation process. Different behavior was revealed by yeasts population, which was partially influenced by copper treatment at the beginning of the fermentation. The polyphasic approach used in the present study, which combined sensory evaluation to microbial counts and physico-chemical characteristics, let to the conclusion on the importance of starter cultures in fermentation of table olives especially those treated with "non-conventional" pesticide, which could be used to prevent olive fly damage.

  8. Mobility of atrazine from alginate-bentonite controlled release formulations in layered soil.

    PubMed

    Fernández-Pérez, M; González-Pradas, E; Villafranca-Sánchez, M; Flores-Céspedes, F

    2001-04-01

    The mobility of atrazine [6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine] from alginate-bentonite-based controlled release (CR) formulations was investigated by using soil columns. Two CR formulations based on sodium alginate (14.0 g kg(-1), atrazine (6.0 g kg(-1), natural or acid-treated bentonite (50 g kg(-1), and water (924 g kg(-1) were compared to technical grade product and commercial liquid (CL) formulation (Gesaprim 500FW). All herbicide treatments were applied to duplicate layered bed systems simulating the typical arrangement under a plastic greenhouse, which is composed of sand (10 cm), peat (2 cm), amended soil (20 cm) and native soil (20 cm). The columns were leached with 39 cm (1500 ml) and 156 cm (6000 ml) of 0.02 M CaCl2 solution to evaluate the effect of water volume applied on herbicide movement. When 39 cm of 0.02 M CaCl2 solution was applied, there was no presence of herbicide in the leachate for the alginate-bentonite CR treatments. However, 0.11% and 0.14% of atrazine appeared in the leachate when the treatment was carried out with technical grade and CL formulations, respectively. When 156 cm of 0.02 M CaCl2 solution was applied, the use of the alginate-acid treated bentonite CR formulation retards and reduces the presence of atrazine in the leachate as compared to technical product. Analysis of the soil columns showed the highest atrazine concentration in the peat layer. Alginate-bentonite CR formulations might be an efficient system for reducing atrazine leaching in layered soil and thus, it could reduce the risks of pollution of groundwater.

  9. Ordovician K-bentonites in the Argentine Precordillera: relations to Gondwana margin evolution

    USGS Publications Warehouse

    Huff, W.D.; Bergstrom, Stig M.; Kolata, Dennis R.; Cingolani, C.A.; Astini, R.A.

    1998-01-01

    This paper is included in the Special Publication entitled 'The proto- Andean margin of Gondwana', edited by R.J. Pankhurst and C.W. Rapela. Ordovician K-bentonites have now been recorded from >20 localities in the vicinity of the Argentine Precordillera. Most occur in the eastern thrust belts, in the San Juan Limestone and the overlying the Gualcamayo Formation, but a few ash beds are known also from the central thrust belts. The oldest occur in the middle Arenig I, victoriae lunatus graptolite (Oe. evae conodont) Zone, and the youngest in the middle Llanvirn P. elegans (P. suecicus) Zone. Mineralogical characteristics, typical of other Ordovician K-bentonites, include a matrix of illite/smectite mixed-layer clay and a typical felsic volcanic phenocryst assemblage: biotite, beta-form quartz, alkali and plagioclase feldspar, apatite, and zircon, with lesser amounts of hornblende, clinopyroxene, titanite and Fe-Ti oxides. The proportions of the mineral phases and variations in their crystal chemistry are commonly unique to individual (or small groups of) K-bentonite beds. Glass melt inclusions preserved in quartz are rhyolitic in composition. The sequence is unique in its abundance of K-bentonite beds, but a close association between the Precordillera and other Ordovician sedimentary basins cannot be established. The ash distribution is most consistent with palaeogeographical reconstructions in which early Ordovician drifting of the Precordillera occurred in proximity to one or more volcanic arcs, and with eventual collision along the Andean margin of Gondwana during the mid-Ordovician Ocloyic event of the Famatinian orogeny. The Puna-Famatina terrane northeast of the Precordillera might have served as the source of the K-bentonite ashes, possibly in concert with active arc magmatism on the Gondwana plate itself.

  10. A coupled THMC model of a heating and hydration laboratory experiment in unsaturated compacted FEBEX bentonite

    NASA Astrophysics Data System (ADS)

    Zheng, Liange; Samper, Javier; Montenegro, Luis; Fernández, Ana María

    2010-05-01

    SummaryUnsaturated compacted bentonite is foreseen by several countries as a backfill and sealing material in high-level radioactive waste repositories. The strong interplays between thermal (T), hydrodynamic (H), mechanical (M) and chemical (C) processes during the hydration stage of a repository call for fully coupled THMC models. Validation of such THMC models is prevented by the lack of comprehensive THMC experiments and the difficulties of experimental methods to measure accurately the chemical composition of bentonite porewater. We present here a non-isothermal multiphase flow and multicomponent reactive solute transport model for a deformable medium of a heating and hydration experiment performed on a sample of compacted FEBEX bentonite. Besides standard solute transport and geochemical processes, the model accounts for solute cross diffusion and thermal and chemical osmosis. Bentonite swelling is solved with a state-surface approach. The THM model is calibrated with transient temperature, water content and porosity data measured at the end of the experiment. The reactive transport model is calibrated with porewater chemical data derived from aqueous extract data. Model results confirm that thermal osmosis is relevant for the hydration of FEBEX bentonite while chemical osmosis can be safely neglected. Dilution and evaporation are the main processes controlling the concentration of conservative species. Dissolved cations are mostly affected by calcite dissolution-precipitation and cation exchange reactions. Dissolved sulphate is controlled by gypsum/anhydrite dissolution-precipitation. pH is mostly buffered by protonation/deprotonation via surface complexation. Computed concentrations agree well with inferred aqueous extract data at all sections except near the hydration boundary where cation data are affected by a sampling artifact. The fit of Cl - data is excellent except for the data near the heater. The largest deviations of the model from inferred

  11. A coupled THMC model of a heating and hydration laboratory experiment in unsaturated compacted FEBEX bentonite

    SciTech Connect

    Zheng, L.; Samper, J.; Montenegro, L.; Fernandez, A.M.

    2010-05-01

    Unsaturated compacted bentonite is foreseen by several countries as a backfill and sealing material in high-level radioactive waste repositories. The strong interplays between thermal (T), hydrodynamic (H), mechanical (M) and chemical (C) processes during the hydration stage of a repository call for fully coupled THMC models. Validation of such THMC models is prevented by the lack of comprehensive THMC experiments and the difficulties of experimental methods to measure accurately the chemical composition of bentonite porewater. We present here a non-isothermal multiphase flow and multicomponent reactive solute transport model for a deformable medium of a heating and hydration experiment performed on a sample of compacted FEBEX bentonite. Besides standard solute transport and geochemical processes, the model accounts for solute cross diffusion and thermal and chemical osmosis. Bentonite swelling is solved with a state-surface approach. The THM model is calibrated with transient temperature, water content and porosity data measured at the end of the experiment. The reactive transport model is calibrated with porewater chemical data derived from aqueous extract data. Model results confirm that thermal osmosis is relevant for the hydration of FEBEX bentonite while chemical osmosis can be safely neglected. Dilution and evaporation are the main processes controlling the concentration of conservative species. Dissolved cations are mostly affected by calcite dissolution-precipitation and cation exchange reactions. Dissolved sulphate is controlled by gypsum/anhydrite dissolution-precipitation. pH is mostly buffered by protonation/deprotonation via surface complexation. Computed concentrations agree well with inferred aqueous extract data at all sections except near the hydration boundary where cation data are affected by a sampling artifact. The fit of Cl{sup -} data is excellent except for the data near the heater. The largest deviations of the model from inferred aqueous

  12. Adsorption kinetics and isotherm of anionic dyes onto organo-bentonite from single and multisolute systems.

    PubMed

    Shen, Dazhong; Fan, Jianxin; Zhou, Weizhi; Gao, Baoyu; Yue, Qinyan; Kang, Qi

    2009-12-15

    The performances of polydiallydimethylammonium modified bentonite (PDADMA-bentonite) as an adsorbent to remove anionic dyes, namely Acid Scarlet GR (AS-GR), Acid Turquoise Blue 2G (ATB-2G) and Indigo Carmine (IC), were investigated in single, binary and ternary dye systems. In adsorption from single dye solutions with initial concentration of 100 micromol/L, the dosage of PDADMA-bentonite needed to remove 95% dye was 0.42, 0.68 and 0.75 g/L for AS-GR, ATB-2G and IC, respectively. The adsorption isotherms of the three dyes obeyed the Langmuir isotherm model with the equilibrium constants of 0.372, 0.629 and 4.31 L/micromol, the saturation adsorption amount of 176.3, 149.2 and 228.7 micromol/g for ATB-2G, IC and AS-GR, respectively. In adsorption from mixed dye solutions, the isotherm of each individual dye followed an expanded Langmuir isotherm model and the relationship between the total amount of dyes adsorbed and the total equilibrium dye concentration was interpreted well by Langmuir isotherm model. In the region of insufficient dosage of PDADMA-bentonite, the dye with a larger affinity was preferentially removed by adsorption. Desorption was observed in the kinetic curve of the dye with lower affinity on PDADMA-bentonite surface by the competitive adsorption. The kinetics in single dye solution and the total adsorption of dyes in binary and ternary dye systems nicely followed pseudo-second-order kinetic model.

  13. Measurements of the effective diffusion coefficient of dissolved oxygen and oxidation rate of pyrite by dissolved oxygen in compacted sodium bentonite

    SciTech Connect

    Manaka, Mitsuo; Kawasaki, Manabu; Honda, Akira

    2000-05-01

    The redox condition of the near field is expected to affect the performance of engineered barrier systems. In particular, the oxygen initially existing in the pore spaces of compacted bentonites strongly affects the redox condition of the near field. To assess the influence of the oxygen, research was done to assess its transport parameters in the compacted bentonite and consumption process. To understand the diffusion of dissolved oxygen (DO) in compacted bentonite and to predict the effect of the DO, the measurements of the effective diffusion coefficient of DO in compacted sodium bentonite were made by electro-chemistry. As a result, the following relationship between the dry density of compacted sodium bentonite and the effective diffusion coefficient of DO in compacted sodium bentonite was derived: D{sub e} = 3.0 {+-} 0.5 {times} 10{sup {minus}9} exp({minus}3.7 {+-} 0.2 {times} 10{sup -3}p), where D{sub e} is the effective diffusion coefficient (m{sup 2}s{sup -1}) of DO in compacted sodium bentonite and p is the dry density (kg m{sup -3})of compacted sodium bentonite. The oxygen concentration in the bentonite is expected to be controlled by the oxidation of pyrite as an impurity in the bentonite. To investigate this idea, the rates of pyrite oxidation by DO in compacted sodium bentonite were estimated from the experimental data in pyrite-bentonite systems using the obtained effective diffusion coefficient of DO. The results show that the average of the rate constants of pyrite oxidation by DO in compacted sodium bentonite was 1.16 {+-} 0.35 {times} 10{sup {minus}8}m s{sup {minus}1}, whereas the rate constant in a carbonate-buffered solution (pH = 9.24) was 1.46 {+-} 0.09 {times}10{sup {minus}9}m s{sup {minus}1}.

  14. The effect of Na-bearing thermal solutions on Ca-Mg-bentonite sorption of Sr and Cs

    SciTech Connect

    Mukhamet-Galeyev, A.P.; Kudrin, A.V.; Nikonov, B.S.; Shikina, N.D.

    1995-12-31

    The sorption of Sr and Cs has been investigated on Ca-Mg-bentonite preliminary treated by 0.1--1.0 m NaCl solutions at 25, 170--250 C during 0.5--7 months. The bentonite remained stable in these conditions. Moreover, hydrothermal treatment has raised the sorption activity of the bentonite. The treated bentonite has shown a strong selectivity for Sr and less pronounced one for Cs. The sorption of the elements increased with temperature and decreased with NaCl content more significant for Sr, than for Cs. The distribution ratio R{sub d} was nearly independent on ion loading for Cs and strongly increased up to 10{sup 4.5} mL/g in 10{sup {minus}2.0}--10{sup {minus}0.5} meq/g ion loading interval for Sr, dropping sharply at more concentrations.

  15. Preparation and characterization of CTAB-HACC bentonite and its ability to adsorb phenol from aqueous solution.

    PubMed

    Huang, Ruihua; Zheng, Dongsheng; Yang, Bingchao; Wang, Bo; Zhang, Zengqiang

    2011-01-01

    A novel type of adsorbent was prepared by modifying bentonite with N-2-hydroxypropyl trimethyl ammonium chloride chitosan (HACC) with cetyl trimethylammonium bromide (CTAB). The adsorbent was named CTAB-HACC bentonite. Its characteristics were investigated using thermogravimetric, Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction. The adsorption of phenol onto CTAB-HACC bentonite was evaluated by changing various parameters, such as contact time, adsorbent dosage, initial pH of the solution, and temperature. The maximum adsorption was observed at pH 12. Adsorption of phenol on CTAB-HACC bentonite favored at lower temperature and established the equilibrium in 30 min. The adsorption efficiency reached 82.1%, and the adsorption capacity was 7.12 mg/g from the phenol solution with a concentration of 500 mg/L at pH 12.0 and 20 degrees C.

  16. Time evolution of the general characteristics and Cu retention capacity in an acid soil amended with a bentonite winery waste.

    PubMed

    Fernández-Calviño, David; Rodríguez-Salgado, Isabel; Pérez-Rodríguez, Paula; Nóvoa-Muñoz, Juan Carlos; Arias-Estévez, Manuel

    2015-03-01

    The effect of bentonite waste added to a "poor" soil on its general characteristic and copper adsorption capacity was assessed. The soil was amended with different bentonite waste concentrations (0, 10, 20, 40 and 80 Mg ha(-1)) in laboratory pots, and different times of incubation of samples were tested (one day and one, four and eight months). The addition of bentonite waste increased the pH, organic matter content and phosphorus and potassium concentrations in the soil, being stable for P and K, whereas the organic matter decreased with time. Additionally, the copper sorption capacity of the soil and the energy of the Cu bonds increased with bentonite waste additions. However, the use of this type of waste in soil presented important drawbacks for waste dosages higher than 20 Mg ha(-1), such as an excessive increase of the soil pH and an increase of copper in the soil solution.

  17. Modelling of geochemical reactions and experimental cation exchange in MX 80 bentonite.

    PubMed

    Montes-H, G; Fritz, B; Clement, A; Michau, N

    2005-10-01

    Bentonites are widely used for waste repository systems because of their hydrodynamic, surface and chemical-retention properties. MX 80 bentonite (bentonite of Wyoming) contains approximately 85% Na/Ca-montmorillonite and 15% accessory minerals. The dominant presence of Na/Ca-montmorillonite in this clay mineral could cause it to perform exceptionally well as an engineered barrier for a radioactive waste repository because this buffer material is expected to fill up by swelling the void between canisters containing waste and the surrounding ground. However, the Na/Ca-montmorillonite could be transformed to other clay minerals as a function of time under repository conditions. Previous modelling studies based on the hydrolysis reactions have shown that the Na/Ca-montmorillonite-to-Ca-montmorillonite conversion is the most significant chemical transformation. In fact, this chemical process appears to be a simple cation exchange into the engineered barrier. The purpose of the present study was two-fold. Firstly, it was hoped to predict the newly formed products of bentonite-fluid reactions under repository conditions by applying a thermokinetic hydrochemical code (KIRMAT: Kinetic Reactions and Mass Transport). The system modelled herein was considered to consist of a 1-m thick zone of water-saturated engineered barrier. This non-equilibrated system was placed in contact with a geological fluid on one side, which was then allowed to diffuse into the barrier, while the other side was kept in contact with iron-charged water. Reducing initial conditions ( [P(O)2 approximately equals 0] ; Eh=-200 mV) and a constant reaction temperature (100 degrees C) were considered. Secondly, it was hoped to estimate the influence of inter-layer cations (Ca and Na) on the swelling behaviour of the MX 80 bentonite by using an isothermal system of water vapour adsorption and an environmental scanning electron microscope (ESEM) coupled with a digital image analysis (DIA) program. Here, the

  18. Experimental Study on the pH of Pore water in Compacted Bentonite under Reducing Conditions with Electromigration

    SciTech Connect

    Nessa, S.A.; Idemitsu, K.; Yamazaki, S.; Ikeuchi, H.; Inagaki, Y.; Arima, T.

    2008-07-01

    Compacted bentonite and carbon steel are considered a good buffer and over-pack materials in the repositories of high-level radioactive waste disposal. Sodium bentonite, Kunipia-F contains approximately 95 wt% of montmorillonite. Bentonites prominent properties of high swelling, sealing ability and cation exchange capacity provide retardation against the transport of radionuclides from the waste into the surrounding rocks in the repository and its properties determine the behavior of bentonite. In this regards, the pH of pore water in compacted bentonite is measured with pH test paper wrapped with semi-permeable membrane of collodion sheet under reducing conditions. On 30 days, the pH test paper in the experimental apparatus indicated that the pH of pore water in compacted bentonite is around 8.0 at saturated state. The carbon steel coupon is connected as the working electrode to the potentiostat and is held at a constant supplied potential between +300 and -300 mV vs. Ag/AgCl electrode for up to 7 days. During applying electromigration the pH of pore water in bentonite decreased and it reached 6.0{approx}6.0 on 7 days. The concentration of iron and sodium showed nearly complementary distribution in the bentonite specimen after electromigration. It is expected that iron could migrate as ferrous ion through the interlayer of montmorillonite replacing exchangeable sodium ions in the interlayer. Semi-permeable membrane of collodion sheet does not affect the color change of pH test paper during the experiment. (authors)

  19. Rapid increases in permeability and porosity of bentonite-sand mixtures due to alteration by water vapor

    SciTech Connect

    Couture, R.A.

    1984-01-01

    Packed columns of canister packing material containing 25% bentonite and 75% quartz or basalt sand, were exposed to water vapor at temperatures up t 260/sup 0/C. The permeabilities of the columns were subsequently measured after complete saturation with liquid water in a pressurized system. Exposure to water vapor caused irreversible increases in permeability by factors of up to 10/sup 5/. After saturation with liquid water, the permeability was nearly independent of temperature. The increases in permeability were due to a large decrease in the ability of the bentonite to swell in water. Calculations suggest that swelling of bentonite altered at 250/sup 0/C was not sufficient to fill the pore spaces. If the pore spaces are filled, the mixture will form an effective barrier against flow, diffusion, and transport of colloids. The results suggest that if bentonite-based canister packing material is exposed even briefly to water vapor at high temperatures in a high-level nuclear waste repository, its performance will be seriously impaired. The problem is less severe if the proportion of bentonite is high and the material is highly compacted. Previous results show significant degradation of bentonite by water vapor at temperatures as low as 150/sup 0/C. This suggests that in some repositories, backfill in tunnels and drifts may also be affected. 9 references, 5 figures, 1 table.

  20. In vitro evaluation of the capacity of zeolite and bentonite to adsorb aflatoxin B1 in simulated gastrointestinal fluids.

    PubMed

    Thieu, N Q; Pettersson, H

    2008-09-01

    Anin vitro study using single concentration and isotherm adsorption was carried out to evaluate the capacity of Vietnamese produced zeolite and bentonite to adsorb aflatoxin B1 (AFB1) in simulated gastrointestinal fluids (SGFs), and a commercial sorbent hydrated sodium calcium aluminosilicate (HSCAS) was used as reference. In this study, AFB1 solution was mixed with sorbents (0.3, 0.4 and 0.5% w/v) in SGFs at pH 3 and pH 7 and shaken for 8 h, centrifuged and the supernatant measured by Vicam fluorometer. Adsorption of AFB1 onto zeolite and bentonite varied according to the pH of SGFs and was lower than HSCAS. Linearity between the increased amount of AFB1 adsorbed on sorbents and the decrease of sorbent concentration was observed for bentonite and HSCAS, except for zeolite in SGFs at pH 7. The observed maximum amounts of AFB1 adsorbed on bentonite and HSCAS were 1.54 and 1.56 mg/g, respectively. The adsorption capacities of bentonite and HSCAS for AFB1 were 12.7 and 13.1 mg/g, respectively, from fitting the data to the Freundlich isotherm equation. Improvement in processing and purification for bentonite is needed to enhance the surface area, which would probably result in better adsorptive capacity for this sorbent.

  1. Comparing the effects of Bentonite & Calendula on the improvement of infantile diaper dermatitis: A randomized controlled trial

    PubMed Central

    Mahmoudi, Mansoreh; Adib-Hajbaghery, Mohsen; Mashaiekhi, Mahdi

    2015-01-01

    Background & objectives: Infantile diaper dermatitis is a common, acute inflammatory reaction of the skin around diaper among infants. This study was undertaken to compare the effect of topical application of Bentonite and Calendula creams on the improvement of infantile diaper dermatitis. Methods: This double blind randomized controlled trial was undertaken on 100 patients of infantile diaper dermatitis. The 100 participants were randomly assigned into two groups of 50 each, and were prescribed the coded medicine. The mothers were trained to apply the cream and level of improvement was judged by observing the affected area on the first visit and then after three days of receiving treatment. Results: The mean age of infants was 6.45±5.53 months in Calendula group and 7.35±6.28 months in Bentonite group. Overall, 88 per cent of lesions in the Bentonite group started improving in the first six hours while this rate was 54 per cent in Calendula group (P<0.001). The risk ratio for the improvement in the first six hours was 2.99 folds in the Bentonite group. Also, lesions in 86 per cent infants in the Bentonite group and 52 per cent in the Calendula group were completely improved in the first three days after treatment (P<0.001). Interpretation & conclusions: Our results showed that in comparison with Calendula, Bentonite had faster healing effect and was more effective on the improvement of infantile diaper dermatitis (IRCT ID: IRCT 2012112811593N1). PMID:26831423

  2. Cationic polyelectrolyte/bentonite prepared by ultrasonic technique and its use as adsorbent for Reactive Blue K-GL dye.

    PubMed

    Li, Qian; Yue, Qin-Yan; Su, Yuan; Gao, Bao-Yu; Fu, Lin

    2007-08-17

    In this study, the cationic polyelectrolyte polyepicholorohydrin-dimethylamine (EPI-DMA) was intercalated into bentonite using ultrasonic. The structure of EPI-DMA/bentonite and its adsorption of Reactive Blue K-GL (RB K-GL) dye were investigated. Compared with raw bentonite, the EPI-DMA/bentonite had larger interlayer spacing and was more hydrophobic, providing with better surface properties for adsorption. The adsorption of RB K-GL on EPI-DMA/bentonite was described by the adsorption models of Langmuir, Freundlich and Dubinin-Radushkevic. The adsorption kinetics was analyzed using pseudo-first- and second-order kinetic models and intraparticle diffusion model. Results showed that both the intraparticle diffusion and first-order adsorption occur in the initial period of adsorption, and that pseudo-second-order kinetic model was more suitable for describing the whole adsorption process. The reaction rates were also calculated. The changes of free energy, enthalpy and entropy of adsorption were evaluated for the adsorption of RB K-GL onto EPI-DMA/bentonite, suggesting that the adsorption process was spontaneous and exothermic.

  3. Attenuation of elastic waves in bentonite and monitoring of radioactive waste repositories

    NASA Astrophysics Data System (ADS)

    Biryukov, A.; Tisato, N.; Grasselli, G.

    2016-04-01

    Deep geological repositories, isolated from the geosphere by an engineered bentonite barrier, are currently considered the safest solution for high-level radioactive waste (HLRW) disposal. As the physical conditions and properties of the bentonite barrier are anticipated to change with time, seismic tomography was suggested as a viable technique to monitor the physical state and integrity of the barrier and to timely detect any unforeseen failure. To do so, the seismic monitoring system needs to be optimized, and this can be achieved by conducting numerical simulations of wave propagation in the repository geometry. Previous studies treated bentonite as an elastic medium, whereas recent experimental investigations indicate its pronounced viscoelastic behaviour. The aims of this contribution are (i) to numerically estimate the effective attenuation of bentonite as a function of temperature T and water content Wc, so that synthetic data can accurately reproduce experimental traces and (ii) assess the feasibility and limitation of the HLRW repository monitoring by simulating the propagation of sonic waves in a realistic repository geometry. A finite difference method was utilized to simulate the wave propagation in experimental and repository setups. First, the input of the viscoelastic model was varied to achieve a match between experimental and numerical traces. The routine was repeated for several values of Wc and T, so that quality factors Qp(Wc, T) and Qs(Wc, T) were obtained. Then, the full-scale monitoring procedure was simulated for six scenarios, representing the evolution of bentonite's physical state. The estimated Qp and Qs exhibited a minimum at Wc = 20 per cent and higher sensitivity to Wc, rather than T, suggesting that pronounced inelasticity of the clay has to be taken into account in geophysical modelling and analysis. The repository-model traces confirm that active seismic monitoring is, in principle, capable of depicting physical changes in the

  4. Laboratory investigation of the role of desorption kinetics on americium transport associated with bentonite colloids.

    PubMed

    Dittrich, Timothy Mark; Boukhalfa, Hakim; Ware, Stuart Douglas; Reimus, Paul William

    2015-10-01

    Understanding the parameters that control colloid-mediated transport of radionuclides is important for the safe disposal of used nuclear fuel. We report an experimental and reactive transport modeling examination of americium transport in a groundwater-bentonite-fracture fill material system. A series of batch sorption and column transport experiments were conducted to determine the role of desorption kinetics from bentonite colloids in the transport of americium through fracture materials. We used fracture fill material from a shear zone in altered granodiorite collected from the Grimsel Test Site (GTS) in Switzerland and colloidal suspensions generated from FEBEX bentonite, a potential repository backfill material. The colloidal suspension (100 mg L(-1)) was prepared in synthetic groundwater that matched the natural water chemistry at GTS and was spiked with 5.5 × 10(-10) M (241)Am. Batch characterizations indicated that 97% of the americium in the stock suspension was adsorbed to the colloids. Breakthrough experiments conducted by injecting the americium colloidal suspension through three identical columns in series, each with mean residence times of 6 h, show that more than 95% of the bentonite colloids were transported through each of the columns, with modeled colloid filtration rates (k(f)) of 0.01-0.02 h(-1). Am recoveries in each column were 55-60%, and Am desorption rate constants from the colloids, determined from 1-D transport modeling, were 0.96, 0.98, and 0.91 h(-1) in the three columns, respectively. The consistency in Am recoveries and desorption rate constants in each column indicates that the Am was not associated with binding sites of widely-varying strengths on the colloids, as one binding site with fast kinetics represented the system accurately for all three sequential columns. Our data suggest that colloid-mediated transport of Am in a bentonite-fracture fill material system is unlikely to result in transport over long distance scales because

  5. Control of Montmorillonite Surface Coatings on Quartz Grains in Bentonite by Precursor Volcanic Glass

    NASA Astrophysics Data System (ADS)

    Wendlandt, R. F.; Harrison, W. J.

    2008-12-01

    The pathogenic tendencies of respirable-sized quartz grains may be dependent on inherent characteristics of the quartz as well as external factors. Surface coatings on quartz are of particular interest as they modify both physical and chemical properties of quartz grain surfaces and sequester the grain from contact with reactive lung fluids. Wendlandt et al. (Appl. Geochem. 22, 2007) investigated the surface properties of respirable-sized quartz grains in bentonites and recognized pervasive montmorillonite surface coatings on the quartz that resisted removal by repeated vigorous washings and reaction with HCl. To understand the persistence of montmorillonite coatings on quartz grains of igneous origin, volcanic ash deposits of varying age and degree of alteration to montmorillonite were sampled in Utah, including the distal Lava Creek (c. 0.64 Ma) and Bishop Tuffs (c. 0.74 Ma), and SW Colorado (Conejos Fm, San Juan Volcanic Field) for comparison with commercial grade Cretaceous-age "western" and "southern" bentonites. Quartz grains, hand-picked from these samples, were analyzed using FE-SEM and HRTEM. Continuous coatings of volcanic glass occur on quartz grains from the distal volcanic ash samples. As glass alteration to montmorillonite becomes more extensive, quartz grain surfaces start to display patches of montmorillonite. These patches become continuous in extent on quartz grains from the bentonites. Late precipitation of opal- CT lepispheres is consistent with the alteration reaction for volcanic glass: Volcanic glass + H2O = montmorillonite + SiO2(am) + ions(aq). HRTEM of quartz grains reveals an amorphous surface layer, consistent with a volcanic glass coating. Our results indicate that persistent montmorillonite coatings on quartz grains in bentonites are related to precursor volcanic glass coatings on these grains. The absence of glass coatings on other mineral grains in bentonite (feldspar, biotite) may be a consequence of the presence of strong cleavage

  6. Regeneration of kaolin mined lands to maximize loblolly pine growth and wildlife habitat

    SciTech Connect

    McEvoy, K.E.; Morris, L.A.; Hendrick, R.L.; Ogden, E.A.

    1999-07-01

    Compliance with the Surface Mining Control and Reclamation Act of 1977 and Georgia Surface Mining Act of 1968 requires that land equal in area to each year's disturbance by reclaimed and a vegetative cover established. Approximately 60% of kaolin mined areas are reclaimed to pine forest. Current methods of reclamation after grading involve fertilization, seeding with a cover crop of grass and legumes, followed by planting of tree seedlings. Restrictive soil physical conditions, a lack of organic matter and nutrients, and competition by cover crop species can reduce survival and growth of loblolly pine seedlings. Also, current cover crop species have only marginal value for wildlife. In this research, the authors evaluated alternative methods of reforestation that (1) control erosion while providing greater benefits for wildlife and reduced competition with loblolly pine seedlings, (2) ameliorate adverse soil physical conditions through deeper tillage (subsoiling vs. disk harrowing), and (3) improve spoil fertility and structure by application of a composted paper mill by-product. Results from field trials indicate control of erosion by wildlife grasses is comparable to seed mixtures currently used in the industry. Subsoiling and disking both had ameliorative effects on soil physical properties with seedling survival at 92% and 88% respectively, compared to 45% of the surrounding area. Composted paper mill by-product served as an additional source of organic matter, nutrients, and protective mulch, thereby enhancing seedling growth as well as ameliorating pine seedlings mulched with the paper mill compost was greater than twice the size of seedlings grown under current reclamation practices.

  7. Reduced subventricular zone proliferation and white matter damage in juvenile ferrets with kaolin-induced hydrocephalus.

    PubMed

    Di Curzio, Domenico L; Buist, Richard J; Del Bigio, Marc R

    2013-10-01

    Hydrocephalus is a neurological condition characterized by altered cerebrospinal fluid (CSF) flow with enlargement of ventricular cavities in the brain. A reliable model of hydrocephalus in gyrencephalic mammals is necessary to test preclinical hypotheses. Our objective was to characterize the behavioral, structural, and histological changes in juvenile ferrets following induction of hydrocephalus. Fourteen-day old ferrets were given an injection of kaolin (aluminum silicate) into the cisterna magna. Two days later and repeated weekly until 56 days of age, magnetic resonance (MR) imaging was used to assess ventricle size. Behavior was examined thrice weekly. Compared to age-matched saline-injected controls, severely hydrocephalic ferrets weighed significantly less, their postures were impaired, and they were hyperactive prior to extreme debilitation. They developed significant ventriculomegaly and displayed white matter destruction. Reactive astroglia and microglia detected by glial fibrillary acidic protein (GFAP) and Iba-1 immunostaining were apparent in white matter, cortex, and hippocampus. There was a hydrocephalus-related increase in activated caspase 3 labeling of apoptotic cells (7.0 vs. 15.5%) and a reduction in Ki67 labeling of proliferating cells (23.3 vs. 5.9%) in the subventricular zone (SVZ). Reduced Olig2 immunolabeling suggests a depletion of glial precursors. GFAP content was elevated. Myelin basic protein (MBP) quantitation and myelin biochemical enzyme activity showed early maturational increases. Where white matter was not destroyed, the remaining axons developed myelin similar to the controls. In conclusion, the hydrocephalus-induced periventricular disturbances may involve developmental impairments in cell proliferation and glial precursor cell populations. The ferret should prove useful for testing hypotheses about white matter damage and protection in the immature hydrocephalic brain.

  8. Cerebral white matter oxidation and nitrosylation in young rodents with kaolin-induced hydrocephalus.

    PubMed

    Del Bigio, Marc R; Khan, Osaama H; da Silva Lopes, Luiza; Juliet, Packiasamy A R

    2012-04-01

    Hydrocephalus is associated with reduced blood flow in periventricular white matter. To investigate hypoxic and oxidative damage in the brains of rats with hydrocephalus, kaolin was injected into the cisterna magna of newborn 7- and 21-day-old Sprague-Dawley rats, and ventricle size was assessed by magnetic resonance imaging at 7, 21, and 42 days of age. In-situ evidence of hypoxia in periventricular capillaries and glial cells was shown by pimonidazole hydrochloride binding. Biochemical assay of thiobarbituric acid reaction and immunohistochemical detection of malondialdehyde and 4-hydroxy-2-nonenal indicated the presence of lipid peroxidation in white matter. Biochemical assay of nitrite indicated increased nitric oxide production. Nitrotyrosine immunohistochemistry showed nitrosylated proteins in white matter reactive microglia and astrocytes. Activities of the antioxidant enzymes catalase and glutathione peroxidase were not increased, and altered hypoxia-inducible factor 1α was not detected by quantitative reverse transcription-polymerase chain reaction. Cerebral vascular endothelial growth factor expression determined by quantitative reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay was not changed, but vascular endothelial growth factor immunoreactivity was increased in reactive astrocytes of hydrocephalic white matter. To determine if nitric oxide synthase is involved in the pathogenesis, we induced hydrocephalus in 7-day-old wild-type and neuronal nitric oxide synthase-deficient mice. At 7 days, the wild-type and mutant mice exhibited equally severe ventriculomegaly and no behavioral differences, although increased glial fibrillary acidic protein was less in the mutant mice. We conclude that hypoxia, via peroxidation and nitrosylation, contributes to brain changes in young rodents with hydrocephalus and that compensatory mechanisms are negligible.

  9. Synthesis, characterization and application of nanozeolite NaX from Vietnamese kaolin

    NASA Astrophysics Data System (ADS)

    Ngoc, Don Ta; Huyen Pham, Thanh; Nguyen, Khanh Dieu Hong

    2013-12-01

    This paper presents the results of synthesis of nanozeolite NaX from Vietnamese kaolin. Influence factors on the control of crystal sizes and application of synthesized materials as adsorbent for organic compound are discussed. The results show that there are several factors that influence the synthesis. When water content in gel increases, crystal size of NaX increases sharply. The increase of alkaline and silica contents increases the crystallinity and decreases the particle size of nano NaX, and the particle size reaches the minimum at Na2O/Al2O3 = 5.0 and SiO2/Al2O3 = 4.0. Crystal sizes formed at low crystallizing temperature are smaller than those formed at higher temperature. Ageing time and crystallizing time strongly influence the crystallinity and crystal size, which is related to the number of crystal seeds formed during ageing period, the growth of seed and the partial solubility of crystal at maximum formation. Nano NaX was characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) adsorption, Fourier transform infrared (FTIR) and simultaneous thermogravimetry-differential scanning calorimetry (TG/DSC). At optimized synthesis conditions, nano NaX has surface area of 573 m2 g-1with external surface area of 92 m2 g-1, pore size distribution at 0.81 and 10.8 nm, average crystal size of 25 nm and thermal stability up to 789 °C. This material can adsorb cumene rapidly with high adsorption capacity and stability.

  10. Can Thromboelastography performed on kaolin-activated citrated samples from critically ill patients provide stable and consistent parameters?

    PubMed

    White, H; Zollinger, C; Jones, M; Bird, R

    2010-04-01

    Thromboelastography (TEG) is a potentially useful tool but analysis within 4-6 min of collection imposes limitations on its use and access. The use of citrate blood tubes potentially increases the time frame for processing specimens. There is, however, limited research on the stability of citrate specimens, timing of processing and the accuracy of TEG results. The purpose of this study was to examine the effects of early and delayed processing on TEG parameters using kaolin-activated citrated blood samples in the intensive care population. TEG analysis was performed on 61 patients. Blood was collected into two 3.2% sodium citrate (0.105 m) tubes. Kaolin-activated samples were analysed at 15, 30 and 120 min postcollection. TEG parameters analysed included reaction time (R), clot formation time (K), alpha angle (alpha), maximum amplitude, LY30, the coagulation index, time to maximum rate of thrombus generation, maximum rate of thrombus generation and total thrombus generation. Sixty-one critically ill patients were included. The results of the anova showed that time from collection was significantly associated with the TEG((R)) results (P < 0.05). On comparison of individual outcome variables, this difference in most cases was due to changes over time from 30 to 120 min. Furthermore, progressive changes in TEG parameters such as decreasing R were suggestive of a trend toward hypercoagulability of the specimens. Processing of kaolin-activated citrate TEG specimens can begin as early as 15 min postvenipuncture. However, delaying processing by more than 30 min leads to a significant change in results.

  11. Particle morphology and mineral structure of heavy metal-contaminated kaolin soil before and after electrokinetic remediation.

    PubMed

    Roach, Nicole; Reddy, Krishna R; Al-Hamdan, Ashraf Z

    2009-06-15

    This study aims to characterize the physical distribution of heavy metals in kaolin soil and the chemical and structural changes in kaolinite minerals that result from electrokinetic remediation. Three bench-scale electrokinetic experiments were conducted on kaolin that was spiked with Cr(VI) alone, Ni (II) alone, and a combination of Cr(VI), Ni(II) and Cd(II) under a constant electric potential of 1VDC/cm for a total duration of 4 days. Transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) analyses were performed on the soil samples before and after electrokinetic remediation. Results showed that the heavy metal contaminant distribution in the soil samples was not observable using TEM and EDX. EDX detected nickel and chromium on some kaolinite particles and titanium-rich, high-contrast particles, but no separate phases containing the metal contaminants were detected. Small amounts of heavy metal contaminants that were detected by EDX in the absence of a visible phase suggest that ions are adsorbed to kaolinite particle surfaces as a thin coating. There was also no clear correlation between semiquantitative analysis of EDX spectra and measured total metal concentrations, which may be attributed to low heavy metal concentrations and small size of samples used. X-ray diffraction analyses were aimed to detect any structural changes in kaolinite minerals resulting from EK. The diffraction patterns showed a decrease in peak height with decreasing soil pH value, which indicates possible dissolution of kaolinite minerals during electrokinetic remediation. Overall this study showed that the changes in particle morphology were found to be insignificant, but a relationship was found between the crystallinity of kaolin and the pH changes induced by the applied electric potential.

  12. Synthesis of kaolin supported nanoscale zero-valent iron and its degradation mechanism of Direct Fast Black G in aqueous solution

    SciTech Connect

    Jin, Xiaoying; Chen, Zhengxian; Zhou, Rongbing; Chen, Zuliang

    2015-01-15

    Graphical abstract: UV–visible spectra of DFBG solution using K-nZVI (1:1) nanoparticles. (a) Before reaction; (b) during reaction; (c) after reaction. - Highlights: • Kaolin-supported Fe{sup 0} nanoparticle (K-nZVI) was synthesized. • Degradation of Direct Fast Black by K-nZVI was studied. • K-nZVI was characterized by SEM, XRD, UV and FIIR. • Degradation mechanism of Direct Fast Black was proposed. - Abstract: Calcinated kaolin supported nanoscale zero-valent iron (K-nZVI) was synthesized and used for the removal of tetrad azo-group dye-Direct Fast Black G (DFBG) from aqueous solution. The results demonstrated that after reacting for 10 min with an initial concentration of DFBG 100 mg L{sup −1} (pH 9.49), 78.60% of DFBG was removed using K-nZVI, while only 41.39% and 12.56% of DFBG were removed using nZVI and kaolin, respectively. K-nZVI with a mass ratio of nZVI nanoparticles versus kaolin at 1:1 was found to have a high degree of reactivity. Furthermore, scanning electron microscopy (SEM) confirmed that nZVI was better dispersed when kaolin was present. XRD patterns indicated that iron oxides were formed after reaction. Fourier transforms infrared spectra (FTIR) and UV–visible demonstrated that the peak in the visible light region of DFBG was degraded and new bands were observed. Kinetics studies showed that the degradation of DFBG fitted well to the pseudo first-order model. The degradation of DFBG by K-nZVI was based on its adsorption onto kaolin and iron oxides, and subsequently reduction using nZVI was proposed. A significant outcome emerged in that 99.84% of DFBG in wastewater was removed using K-nZVI after reacting for 60 min.

  13. Studies on incorporation of exfoliated bentonitic clays in polyurethane foams for increasing flame retardancy

    NASA Astrophysics Data System (ADS)

    Quagliano, J.; Gavilán García, Irma

    2012-09-01

    In this contribution we report the results of studying the incorporation of exfoliated bentonitic clays into polyurethane foams. A suspension in water of a sodium bentonite from Argentine Patagonia was interchanged with cetyl trimethyl ammonium bromide (CTAB) for 4 h at 80°C, rendering an exfoliated clay, which is nanometric in only one dimension. This nanoclay, when dispersed in the polyurethane, resulted in the same fire retardancy rating (UL-94) than when polyurethane was treated with a commercial nanoclay. Scanning electron microscopy (SEM) at low augmentations of polyurethane samples treated with the synthethized nanoclay (2,5% w/w) showed no differences respect to untreated polyurethane, except for the irregularity of void edges.

  14. Comparative Study of Laterite and Bentonite Based Organoclays: Implications of Hydrophobic Compounds Remediation from Aqueous Solutions

    PubMed Central

    Nafees, Muhammad; Waseem, Amir; Khan, Abdur Rehman

    2013-01-01

    Four cost effective organoclays were synthesized, characterized, and studied for the sorption of hydrophobic compounds (edible oil/grease and hydrocarbon oil) from aqueous solutions. Organoclays were prepared by cation exchange reaction of lattice ions (present onto the surface of laterite and bentonite clay minerals) with two surfactants, hexadecyl trimethyl ammonium chloride (HDTMA-Cl) and tetradecyl trimethyl ammonium bromide (TDTMA-Br). Fourier transform infrared spectroscopy and scanning electron microscopy were used for the characterization of synthesized organoclays. It was found that the amount of surfactant loading and the nature of the surfactant molecules used in the syntheses of organoclay strongly affect the sorption capacity of the clay mineral. Further, it was found that both the laterite and bentonite based organoclays efficiently removed the edible and hydrocarbon oil content from lab prepared emulsions; however, the adsorption capacity of clay mineral was greatly influenced by the nature of hydrophobic compounds as well. PMID:24302867

  15. Comparative study of laterite and bentonite based organoclays: implications of hydrophobic compounds remediation from aqueous solutions.

    PubMed

    Nafees, Muhammad; Waseem, Amir; Khan, Abdur Rehman

    2013-01-01

    Four cost effective organoclays were synthesized, characterized, and studied for the sorption of hydrophobic compounds (edible oil/grease and hydrocarbon oil) from aqueous solutions. Organoclays were prepared by cation exchange reaction of lattice ions (present onto the surface of laterite and bentonite clay minerals) with two surfactants, hexadecyl trimethyl ammonium chloride (HDTMA-Cl) and tetradecyl trimethyl ammonium bromide (TDTMA-Br). Fourier transform infrared spectroscopy and scanning electron microscopy were used for the characterization of synthesized organoclays. It was found that the amount of surfactant loading and the nature of the surfactant molecules used in the syntheses of organoclay strongly affect the sorption capacity of the clay mineral. Further, it was found that both the laterite and bentonite based organoclays efficiently removed the edible and hydrocarbon oil content from lab prepared emulsions; however, the adsorption capacity of clay mineral was greatly influenced by the nature of hydrophobic compounds as well.

  16. Effect of swelling pressure on local volume change in unsaturated sand-bentonite buffer material

    SciTech Connect

    Shooshpasha, I.; Mohamed, A.M.O.; Yong, R.N.; Onofrei, C.

    1996-08-01

    This study was designed to investigate the effect of swelling pressure on local volume changes in unsaturated sand-bentonite based buffer material used in a nuclear fuel waste disposal vault. A laboratory mixture of sodium bentonite and graded silica sand in equal proportion by dry weight was used in both ambient and elevated temperatures experiments. At high water content locations within the tested specimens, the density was reduced by 3.57% from its initial values due to swelling. The swelling pressure as a function of distance was calculated by 4 different models. The calculated results have indicated that the density distribution within the specimen is affected by swelling potential distribution. The calculated swelling pressure values vary as a function of water content, reaching 1 MPa at the source of water intake, i.e., at high water content zone, and 2 MPa at the heater side, i.e., at low water content zone.

  17. Adsorption of Heavy Metal Ions from Aqueous Solutions by Bentonite Nanocomposites.

    PubMed

    Ma, Jing; Su, Guojun; Zhang, Xueping; Huang, Wen

    2016-08-01

    A series of bentonite nanocomposites have been synthesized by modifying bentonite with hexadecyltrimethylammonium bromide (CTMAB) and the common complexing agents, complexone (ethylene diamine tetraacetic acid, EDTA) or mercaptocomplexant (2-Mercaptobenzothiazole, MBT). These adsorbents are used to remove heavy metal ions (Cu(2+), Zn(2+), Mn(2+),Co(2+)). The Bent-CTMAB-MBT adsorbed metal ions are higher than Bent-CTMAB-EDTA under the same ion concentration in AAS. Compared with the single ion system, the adsorption of the mixed ion system of Cu(2+), Zn(2+), Mn(2+), Co(2+) had decreased differently. In the mixed system, the adsorption of Mn(2+) is significantly lower, but the adsorption of Cu(2+) was highest. The adsorption sequence of these four metal ions was Cu(2+) > Zn(2+) > Co(2+) > Mn(2+), and the selective adsorption was closely related to the hydration energy of heavy metal ions. We could remove more metal ions in different stages with the adsorption sequence.

  18. Preparation of xanthated bentonite and its removal behavior for Pb(II) ions.

    PubMed

    He, Y F; Li, F R; Wang, R M; Li, F Y; Wang, Y; Zhang, Z H

    2010-01-01

    Xanthate was successfully grafted onto bentonite by a relatively simple solution reaction. The obtained xanthated bentonite (XBent) was characterized by FT-IR spectrophotometer, thermogravimetric analysis (TG), particle size analysis, x-ray diffraction (XRD) and scanning electron microscopy (SEM). XBent acting as a type of environmentally friendly adsorbent was applied to remove lead ions from aqueous solutions. The optimum conditions were as follows: [Pb(2+)] = 500 mg L(-1), [XBent] = 2 g L(-1), pH = 5.0; oscillating 60 min under 200 rpm at 25 degrees C. The removal rate of lead was up to 99.9%. It was found that the lead(II) ions-XBent adsorption isotherm model fitted well to the Freundlich isotherm. The adsorption mechanism was also investigated by SEM and XRD, which concluded that lead ions were complexed or chelated with XBent. XBent appears to have potential to be used later in water treatment as a type of inorganic polymer reagent.

  19. Evaluation of the application potential of bentonites in phenanthrene bioremediation by characterizing the biofilm community.

    PubMed

    Huang, Yili; Zhang, Jing; Zhu, Lizhong

    2013-04-01

    Application of clay minerals in bioremediation has emerged as a new and promising research field. In this study, the application of calcinated bentonite (CB) and calcinated organobentonite (COB) in phenanthrene (Phe) bioremediation showed high Phe removal efficiency. Clone libraries based on 16S rRNA gene and scanning electronic microscopy showed that diverse taxa of bacteria formed biofilms on both COB and CB particles. The family Sphingomonadaceae was the major group and made up 18% and 23% of the COB and CB biofilm composition, respectively. All and 80% of dioxygenase genes from COB and CB biofilms were closely related to that of Sphingomonas sp., and others matched to that of Comamonas and Mycobacterium. The selective effect of COB on bacterial community was also evident. This study characterized for the first time the bacterial diversity of biofilm community and functional Phe degrading groups on bentonites particles, and provided useful information for future applications.

  20. Removal of catechol from aqueous solutions by adsorption onto organophilic-bentonite.

    PubMed

    Shakir, K; Ghoneimy, H F; Elkafrawy, A F; Beheir, Sh G; Refaat, M

    2008-02-11

    Organophilic-bentonite, produced by exchange of cetyltrimethylammonium cation for metal cations on the bentonite, was exploited as adsorbent for removal of catechol from aqueous solutions using batch technique. The dependence of removal on various physico-chemical parameters, such as contact time (1-250 min), concentration (0.8-15.3 mmol L(-1)), temperature (30, 40, 50+/-1 degrees C) and pH (5-12) of the adsorptive solution were investigated. Obtained results show that catechol could be removed efficiently ( approximately 100%) at pH values > or =9.9. The uptake process follows first-order rate kinetics and the equilibrium data fit well into the Langmuir and Freundlich adsorption isotherms over a wide range of concentration (1-10 mmol L(-1)). The magnitude of change of free energy (DeltaG degrees ), enthalpy (DeltaH degrees ) and entropy (DeltaS degrees ) were determined.

  1. Reuse of MSWI bottom ash mixed with natural sodium bentonite as landfill cover material.

    PubMed

    Puma, Sara; Marchese, Franco; Dominijanni, Andrea; Manassero, Mario

    2013-06-01

    The research described in this study had the aim of evaluating the reuse of incinerator slag, mixed with sodium bentonite, for landfill capping system components. A characterization was performed on pure bottom ash (BA) samples from an incinerator in the north of Italy. The results show that the BA samples had appropriate properties as covers. The compacted dry unit weight of the studied BA (16.2 kN m(-3)) was lower than the average value that characterizes most conventional fill materials and this can be considered advantageous for landfill cover systems, since the fill has to be placed on low bearing capacity ground or where long-term settlement is possible. Moreover, direct shear tests showed a friction angle of 43°, corresponding to excellent mechanical characteristics that can be considered an advantage against failure. The hydraulic conductivity tests indicated a steady-state value of 8 × 10(-10) m s(-1) for a mixture characterized by a bentonite content by weight of 10%, which was a factor 10 better than required by Italian legislation on landfill covers. The results from a swell index test indicated that fine bentonite swelled, even when divalent cations were released by the BA. The leaching behaviour of the mixture did not show any contamination issues and was far better than obtained for the pure BA. Thus, the BA-bentonite mixture qualified as a suitable material for landfill cover in Italy. Moreover, owing to the low release of toxic compounds, the proposed cover system would have no effect on the leachate quality in the landfill.

  2. A bentonite-gold nanohybrid as a heterogeneous green catalyst for selective oxidation of silanes.

    PubMed

    Maya, R J; John, Jubi; Varma, R Luxmi

    2016-08-23

    A highly efficient, environmentally benign and reusable heterogeneous bentonite-gold nanohybrid catalyst was designed and synthesized. This heterogeneous catalyst could efficaciously catalyse the oxidation of organosilanes to silanols. The reaction is 98.7% atom economical and the products were obtained in excellent yield without the formation of disiloxanes as byproducts. The catalyst was also well applicable for the gram scale preparation of silanols.

  3. [Use of bentonite in production of granular bioinsecticide on the basis of Bacillus thuringiensis].

    PubMed

    Drehval', O A; Hordiienko, A S; Cherevach, N V; Kurdysh, I K; Vinnikov, A I

    2008-01-01

    Electrokinetic properties of Bacillus thuringiensis spores and peculiarities of their interaction with clayey minerals montmorillonite and paligorskite were investigated. Existence of contact interaction between montmorillonite particles and bacteria endospores was shown. Granular bioinsecticide was prepared on the basis of bentonite, montmorillonite being its main component. It was discovered that the preparation can be well preserved for 3 months. While using the preparation after the long-term preservation for 12 months, it is recommended to increase the bioinsecticide suspension concentration twice.

  4. Copper removal from sludge permeate with ultrafiltration membranes using zeolite, bentonite and vermiculite as adsorbents.

    PubMed

    Malamis, S; Katsou, E; Stylianou, M; Haralambous, K J; Loizidou, M

    2010-01-01

    The aim of this work is to examine copper removal from sludge permeate with the use of low-cost minerals of Mediterranean origin combined with ultrafiltration membranes. The minerals used were zeolite (clinoptilolite), bentonite and vermiculite. Activated sludge was enriched with 0.01 N (317.7 ppm) of Cu(II). Fixed concentrations of minerals were added to sludge and the pH value was adjusted at 5.5. The mixture was agitated for 2 hours at 800 rpm at room temperature and was then filtered through a batch ultrafiltration system for 1 hour. This experiment was repeated, for comparison purposes, with sludge enriched with 0.01 N of Cu(II) with no mineral addition. The results showed that ultrafiltration membranes with no mineral addition were able to remove a significant amount of copper with removal efficiencies ranging from 59.4-78.3%. The addition of 10 g/l and 20 g/l of bentonite combined with ultrafiltration membranes resulted in removal efficiencies of 94.9% and 99.4% respectively and that of 10 g/l and 20 g/l of vermiculite in removal efficiencies of 93.8% and 96.8%, respectively. The ion exchange capacity of minerals followed the order bentonite > vermiculite > zeolite. Furthermore, membrane fouling was investigated. The addition of zeolite and bentonite reduced membrane fouling, while the addition of vermiculite did not impact on fouling. The use of low-cost minerals in combination with ultrafiltration membranes can be employed to treat industrial wastewater, resulting in a final effluent with very low copper concentrations.

  5. Environmental Remediation and Sorption of Metal Cations Using Aluminum Pillared Nano-Bentonite

    NASA Astrophysics Data System (ADS)

    Rifai, Rifai; Abou El Safa, Magda

    2015-04-01

    The release of heavy metal cations into the environment is a potential threat to water and soil quality. Some clay minerals play an important role, as physical and chemical barriers, for the isolation of metal-rich wastes and to adsorb heavy metals as well as to avoid their environmental dispersion. In the present study, the bentonitic clay (southeast El-Hammam City, Egypt) was subjected to pillaring using hydroxyl-aluminum solution. The XRD patterns of the Aluminum Pillared Nano-Bentonite (APNB) showed severe alteration of the crystal structure after pillaring. Poly metal solutions with different metal concentrations of Cu, Co, Ni, Zn, Cd and Pb (0.001, 0.005 and 0.01 moles), and pH (1, 2.5, 5 and 6) were subjected to treatment by the APNB. The removal process is very rapid and spontaneous and the contact time may be short (several minutes) for most adsorption to occur. The criterion for environmental remediation of APNB is less stringent and a short contact time is sufficient. The rate of Cu2+, Zn2+, Co2+, Cd2+, Ni2+ and Pb2+sorption remained higher or equal to the CEC. The sorption of metal ions by APNB are complex and probably involve several mechanisms. In general, APNB can be used to immobilize Cu2+, Zn2+, Co2+, Cd2+, Ni2+ and Pb2+ to any extent. For each metal ion, the most effective immobilization occurs over a particular pH around 5. According to the experimental data obtained, the uptake amount of the studied cations by APNB increased with increasing solution pH, sorbent dose and contact time. The preference of the APNB adsorption for heavy metal ions that are through the cation exchange processes decreases in the order: Cu2+>Zn2+>Co2+>Cd2+ >Ni2+ >Pb2+. Keywords: Bentonitic clay, Egypt, Aluminum Pillared Nano-Bentonite, heavy metal, environmental remediation

  6. Modeling experimental results of diffusion of alkaline solutions through a compacted bentonite barrier

    SciTech Connect

    Fernandez, Raul; Cuevas, Jaime; Maeder, Urs K.

    2010-08-15

    The interaction between concrete/cement and swelling clay (bentonite) has been modeled in the context of engineered barrier systems for deep geological disposal of high-level radioactive waste. The geochemical transformations observed in laboratory diffusion experiments at 60 and 90 {sup o}C between bentonite and different high-pH solutions (K-Na-OH and Ca(OH){sub 2}-saturated) were reconciled with the reactive transport code CrunchFlow. For K-Na-OH solutions (pH = 13.5 at 25 {sup o}C) partial dissolution of montmorillonite and precipitation of Mg-silicates (talc-like), hydrotalcite and brucite at the interface are predicted at 60 {sup o}C, while at 90 {sup o}C the alteration is wider. Alkaline cations diffused beyond the mineralogical alteration zone by means of exchange with Mg{sup 2+} in the interlayer region of montmorillonite. Very slow reactivity and minor alteration of the clay are predicted in the Ca(OH){sub 2}-bentonite system. The model is a reasonable description of the experiments but also demonstrates the difficulties in modeling processes operating at a small scale under a diffusive regime.

  7. Nonlinear isotherm and kinetics of adsorption of copper from aqueous solutions on bentonite

    NASA Astrophysics Data System (ADS)

    Sadeghalvad, Bahareh; Khosravi, Sara; Azadmehr, Amir Reza

    2016-11-01

    Bentonite is one of the most significant of clay minerals that has been studied extensively due to its potential applications in removal of various environmental pollutants. This ability is related to its high ionic exchange capacity and high specific surface area. Copper is one of the important elements of non-ferrous metals found in industrial waste waters. In the present work, the removal of copper from aqueous solutions with Iranian bentonite (from Birjand area, southeastern Iran) used without any chemical pretreatment, was studied. The experimental results were fitted by adsorption isotherms equations with two or three parameters, which include Langmuir, Freundlich, Dubinin-Radushkevich (D-R), Redlich-Peterson, Khan, and Toth models. The best correlation coefficient ( r 2) is 0.9879 observed for Langmuir model, maximum adsorption capacity of bentonite was 55.71 mg/g. The first-order and pseudo-second-order kinetic equations were used to describe the kinetics of adsorption. The experimental data were well fitted by the pseudo-second-order kinetics.

  8. Bacterial Diversity in Bentonites, Engineered Barrier for Deep Geological Disposal of Radioactive Wastes.

    PubMed

    Lopez-Fernandez, Margarita; Cherkouk, Andrea; Vilchez-Vargas, Ramiro; Jauregui, Ruy; Pieper, Dietmar; Boon, Nico; Sanchez-Castro, Ivan; Merroun, Mohamed L

    2015-11-01

    The long-term disposal of radioactive wastes in a deep geological repository is the accepted international solution for the treatment and management of these special residues. The microbial community of the selected host rocks and engineered barriers for the deep geological repository may affect the performance and the safety of the radioactive waste disposal. In this work, the bacterial population of bentonite formations of Almeria (Spain), selected as a reference material for bentonite-engineered barriers in the disposal of radioactive wastes, was studied. 16S ribosomal RNA (rRNA) gene-based approaches were used to study the bacterial community of the bentonite samples by traditional clone libraries and Illumina sequencing. Using both techniques, the bacterial diversity analysis revealed similar results, with phylotypes belonging to 14 different bacterial phyla: Acidobacteria, Actinobacteria, Armatimonadetes, Bacteroidetes, Chloroflexi, Cyanobacteria, Deinococcus-Thermus, Firmicutes, Gemmatimonadetes, Planctomycetes, Proteobacteria, Nitrospirae, Verrucomicrobia and an unknown phylum. The dominant groups of the community were represented by Proteobacteria and Bacteroidetes. A high diversity was found in three of the studied samples. However, two samples were less diverse and dominated by Betaproteobacteria.

  9. Corrosion of copper and authigenic sulfide mineral growth in hydrothermal bentonite experiments

    NASA Astrophysics Data System (ADS)

    Caporuscio, F. A.; Palaich, S. E. M.; Cheshire, M. C.; Jové Colón, C. F.

    2017-03-01

    The focus of this experimental work is to characterize interaction of bentonite with possible used-fuel waste container materials. Experiments were performed up to 300 °C at 150-160 bars for five to six weeks. Bentonite was saturated with a 1900 ppm K-Ca-Na-Cl-bearing water with Cu-foils. Copper rapidly degrades into chalcocite (CuS2) and minor covellite (CuS) in the presence of H2S. Chalcocite growth and corrosion pit depths were measured for four different experimental runs yielding corrosion rates between 8.8 and 116 μm/yr depending on duration of experiment, brine composition, and clay type (bentonite vs. Opalinus Clay). Results of this research show that although pit-corrosion is demonstrated on Cu substrates, experiments show that the reactions that ensue, and the formation of minerals that develop, are extraordinarily slow. This supports the use of Cu in nuclide-containment systems as a possible engineered barrier system material.

  10. Mobility of isoproturon from an alginate-bentonite controlled release formulation in layered soil.

    PubMed

    Fernández-Pérez, M; González-Pradas, E; Villafranca-Sánchez, M; Flores-Céspedes, F

    2000-11-01

    The mobility of isoproturon [3-(4-isopropylphenyl)-1,1-dimethylurea] from an alginate-based controlled release (CR) formulation was investigated by using soil columns. A layered bed system simulating the typical arrangement under a plastic greenhouse, which is composed of sand, peat, amended soil and native soil was used. The CR formulation was based on sodium alginate (1.87%), isoproturon (1.19%), natural bentonite (3.28%), and water (93.66%), and was compared to technical grade isoproturon. The use of the alginate-bentonite CR formulation produced less vertical mobility of the active ingredient as compared to the technical product. There was no presence of herbicide in the leachate when the alginate-bentonite CR formulation was used. However, 0.90% of isoproturon appeared when the treatment was carried out with technical grade material. Isoproturon mobility was modelled using the programme CMLS, which showed the peat layer to retard pesticide leaching. Analysis of the soil columns showed the highest isoproturon concentration in the peat layer.

  11. Effect of gas pressure on the sealing efficiency of compacted bentonite-sand plugs.

    PubMed

    Liu, J F; Davy, C A; Talandier, J; Skoczylas, F

    2014-12-01

    This research relates to the assessment of the sealing ability of bentonite/sand plugs when swollen in presence of both water and gas pressures, in the context of deep underground radioactive waste storage. Compacted bentonite/sand plugs are placed inside a constant volume cell, and subjected to swelling in presence of both water and gas: swelling kinetics and effective swelling pressure Pswell are identified. Secondly, the gas breakthrough (GB) characteristics of swollen plugs are assessed to determine their ability for gas migration, which has to be minimal for sealing radioactive waste repositories. We show that gas pressure Pg does not affect significantly Pswell until a threshold Pg>2MPa. When swelling occurs inside a tube with a smooth (turned) inner surface, continuous GB occurs when Pg is equivalent to the effective Pswell (obtained without gas pressure, at 7.32MPa±0.11). When the plug swells inside a grooved tube, continuous GB does not occur up to Pg≥10.5MPa: smooth interfaces are a preferential gas migration pathway rather than grooved interfaces, and rather than water-saturated bentonite-sand plugs. With smooth tubes, in presence of Pg≥2MPa, although Pswell is not affected, gas passes through the sample at significantly lower values than Pswell, due to partial sample saturation. It is concluded that GB pressure is a more accurate indicator of partial sample saturation than swelling pressure Pswell alone.

  12. Sorption hysteresis of Cd(II) and Pb(II) on natural zeolite and bentonite.

    PubMed

    Hamidpour, Mohsen; Kalbasi, Mahmoud; Afyuni, Majid; Shariatmadari, Hossein; Holm, Peter E; Hansen, Hans Christian Brunn

    2010-09-15

    Sorption hysteresis in natural sorbents has important environmental implications for pollutant transport and bioavailability. We examined sorption reversibility of Cd(II) and Pb(II) on zeolite and bentonite. Sorption isotherms were derived by sorption of Cd(II) and Pb(II) from solutions containing a range of the metal concentrations corresponding to 10-100% maximum sorption capacity (SCmax) of the sorbents. The desorption experiments were performed immediately following the completion of sorption experiments. Sorption and desorption isotherms of Cd(II) and Pb(II) were well described by the Freundlich model. The results revealed that the desorption isotherms of Cd(II) and Pb(II) from zeolite significantly deviated from the sorption isotherms indicating irreversible or very slowly reversible sorption. For bentonite sorption/desorption isotherms were similar indicating reversible sorption. The extent of hysteresis was evaluated from sorption and desorption Freundlich parameters (K(f) and n) through the apparent hysteresis index (HI = n(desorb)/n(sorb); n is the exponent in the Freundlich equation) and differences in Freundlich K(f) parameters. Higher sorption irreversibility was obtained for Pb(II) as compared to Cd(II). The amounts of Cd(II) and Pb(II) desorbed from bentonite were more than from zeolite, indicating that zeolite was a more effective sorbent for water and wastewater treatment.

  13. [Reduction of chromium (VI) by nanoscale zero-valent iron supported on Al-pillared bentonite].

    PubMed

    Yin, Li-Jing; Li, Yi-Min; Zhang, Lu-Ji; Peng, Yuan-Fei; Ying, Zhe-Lan

    2009-04-15

    In the presence of Al-pillared bentonite with good sorption capacity, nanoscale zero-valent iron supported on Al-pillared bentonite (NZVI/Al-PILC) was prepared with NaBH4 and FeSO4 aqueous solution. The structure of NZVI/Al-PILC was characterized by X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET). The effects of pH values and initial chromium (VI) concentrations on its removal rate by NZVI/Al-PILC were investigated, and were compared with those of unsupported nanoscale zero-valent iron (NZVI) containing the same iron mount of NZVI/Al-PILC. The results indicate that in the same experimental condition, the chromium (VI) removal by NZVI/Al-PILC reached 100% after 120 min. The removal is not only much higher than that (63.0%) of the NZVI containing same iron mount, but also superior to the sum of removal (75.4%) by NZVI containing the same iron amount and the Al-pillared bentonite containing the same clay amount with NZVI/Al-PILC.

  14. Decolourization of Methylene Blue in Water Using Bentonite Impregnated with Ti and Ag as Photocatalyst.

    PubMed

    Wu, Edward Ming-Yang; Kuo, Shu-Lung

    2015-08-01

    This article used bentonite impregnated with titanium and silver, respectively, as photocatalyst, to degrade methylene blue (MB) under conditions of MB solutions exposed to sodium lamp and sunlight. Due to the semi-conducting properties of synthesized bentonite catalysts, when exposed to sodium lamp and sunlight, catalyst particles are excited for photocatalysis to achieve decolourization. After an FT-IR analysis, this study finds that smectite catalysts have significant and complicated wave crests between the fingerprint area with wave numbers 415~600 cm⁻¹ and 750~1170 cm⁻¹. The bentonite impregnated with Ti(4+) (Sm-Ti) and with Ag⁺ (Sm-Ag) removes MB through the mechanisms of adsorption and degradation, while the commercial product of titanium dioxide (TiO₂) only exhibits the capability of MB degradation. At present, a heterogeneous photocatalytic system has been fully applied for use in daily life, with its efficiency determined by the free radical action of electrons and holes, the generation efficiency of ·OH.

  15. Removal of lead from aqueous solutions by a poly(acrylic acid)/bentonite nanocomposite

    NASA Astrophysics Data System (ADS)

    Rafiei, H. R.; Shirvani, M.; Ogunseitan, O. A.

    2016-11-01

    We synthesized a novel poly acrylic acid-organobentonite (PAA-Bent) nanocomposite by successive intercalation of cetyltrimethylammonium (CTA) surfactant and polyacrylic acid (PAA) into the bentonite (Bent) interlayer spaces. The surfactant-modified clay (CTA-Bent) and PAA-Bent nanocomposite were characterized by XRD and FT-IR techniques and used for removal of Pb(II) from aqueous solution. The XRD results confirmed the intercalation of CTA and PAA into the interlayer spaces of the bentonite increasing the d 001 spacing of the clay from 12.2 up to 38.9 Å. FT-IR analysis of the modified clay samples revealed the functional groups of CTA and PAA constituents alighted on the bentonite surfaces. Maximum Pb sorption capacity of the Bent and PAA-Bent predicted by Langmuir model were 52.3 and 93.0 mg g-1, respectively, showing that the synthesized nanocomposite superiorly adsorbed Pb from the solution as compared to the Bent. The maximum Pb removal efficiency of 99.6 % was achieved by the nanocomposite at 25 °C with <30 min contact time for a 7.5 g L-1 solid-to-liquid ratio and an initial metal concentration of 400 mg L-1. The results indicated that PAA-Bent nanocomposite can be efficiently used as a superadsorbent for the removal of Pb(II) from aqueous solution.

  16. Potential performance of pillared inorgano- organo bentonite for soil mix technology permeable reactive barrier (Invited)

    NASA Astrophysics Data System (ADS)

    Abunada, Z. M.; Al-Tabbaa, A.

    2013-12-01

    Modified bentonite has gained more interest for their effect in contaminant removal and environmental protection. This study is investigating the use of three different modified inorgano-organo bentonite (IOB) in soil mixing permeable reactive barrier. IOB were prepared using pillaring agents and quaternary ammonium cations (QAC) with different loading ratios. The permeabilities of compacted specimens containing IOB with two different soil types (sandy and gravelly soil) were measured for site contaminated groundwater, pure water and TEX compounds to study the potential of soil mix permeable reactive barrier (PRB). The soil permeability decreased by 1-2 order of magnitude once mixed with IOB. It also decreased by about 100 in case of TEX compound and site groundwater. The IOB was tested to remove Toluene, Ethyl-benzene, and o-Xylene (TEX) compound from model contaminated water in both batch and column test. Physical characteristics such as pore volume, porosity and specific structure in addition to level of surfactant loading were determined. Materials removal efficiency varied due to the surfactant loading, soil type and contaminant molecular weight. Sorption isotherm showed that the adsorbates preference increased in the order of T>E>X in all IOB types. Maximum TEX compound sorptive capacity varied also due to soil type with the highest was 86.89% 93.19% and 90.2% for T,E,X respectively on sandy soil. Key words: Inorgano-organo bentonite, permeability, reactive barrier, soil mix, sorption

  17. The removal of phenol from aqueous solutions by adsorption using surfactant-modified bentonite and kaolinite.

    PubMed

    Alkaram, Uday F; Mukhlis, Abduljabar A; Al-Dujaili, Ammar H

    2009-09-30

    The natural bentonite (BC) and kaolinite (KC) were modified with two surfactant of hexadecyltrimethylammonium bromide (HDTMA) and phenyltrimethylammonium bromide (PTMA) to form four kinds of organic-modified clays, i.e., HDTMA-bentonite (BHM), HDTMA-kaolinite (KHM), PTMA-bentonite (KPM) and PTMA-kaolinite (KPM). The modified minerals were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD) and FT-IR spectroscopy. The surface areas were determined using methylene blue adsorption method. Cation-exchange capacity (CEC) was estimated using an ethylenediamine complex of copper method and the modifier loading was calculated from the total carbon analysis. The ability of raw and organo-modified clays to remove phenol from aqueous solutions has been carried out as a function of contact time, pH and temperatures using a batch technique. The removal of phenol from aqueous solutions by modified clays seems to be more effective than unmodified samples. The adsorption capacity was found to increase with increasing temperature indication that the adsorptions were endothermic. The adsorption of phenol onto these clays was found to be increased by increasing of pH value and the adsorption patterns data are correlated well by Langmuir and Freundlich isotherm models and that the adsorption is physical in nature. The experimental data fitted very well with the pseudo-second-order kinetic model. The thermodynamic study of adsorption process showed that the adsorption of phenol with these six adsorbents was carried out spontaneously, and the process was endothermic in nature.

  18. Organo-modified bentonites as new flame retardant fillers in epoxy resin nanocomposites

    NASA Astrophysics Data System (ADS)

    Benelli, Tiziana; D'Angelo, Emanuele; Mazzocchetti, Laura; Saraga, Federico; Sambri, Letizia; Franchini, Mauro Comes; Giorgini, Loris

    2016-05-01

    The present work deals with two organophilic bentonites, based on nitrogen-containing compounds: these organoclays were synthesized via an ion exchange process starting from pristine bentonite with 6-(4-butylphenyl)-1,3,5-triazine-2,4-diamine (BFTDA) and 11-amino-N-(pyridine-2yl)undecanamide (APUA) and then used for the production of epoxy-based flame retardant nanocomposites. The amount of organic modifier in the organoclays Bento-BFTDA and Bento-APUA was determined with a TGA analysis and is around 0.4mmol/g for both samples. The effect of the organoclays on a commercial epoxy resin nanocomposite's thermo-mechanical and flammability properties was investigated. Composites containing 3wt% and 5wt% of the nanofillers were prepared by solventless addition of each organoclay to the epoxy resin, followed by further addition of the hardener component. For the sake of comparison a similar nanocomposite with the plain unmodified bentonite was produced in similar condition. The nanocomposites's thermo-mechanical properties of all the produced samples were measured and they resulted slightly improved or practically unaffected. On the contrary, when the flame behaviour was assessed in the cone-calorimeter, an encouraging decrease of 17% in the peak heat released rate (pHRR) was obtained at 3wt% loading level with Bento-APUA. This is a promising result, assessing that the APUA modified organoclay might act as flame retardant.

  19. Photocatalytic Degradation of Safranine by ZnO-Bentonite: Photodegradation versus Adsorbability

    NASA Astrophysics Data System (ADS)

    Sonawane, Gunvant H.; Patil, Sandip P.; Shrivastava, V. S.

    2016-11-01

    ZnO-bentonite nanocomposite was obtained by incorporation of bentonite clay with ZnO. The effects of pH, contact time, initial dye concentration and photocatalyst dose on the rate of degradation of dye solution were studied. It was observed that working conditions strongly influence the dye removal process. Contact time 70 min and pH 4 was optimized for photocatalytic degradation of Safranine. Adsorption kinetics for 20-80 mg/l dye concentration was found to follow pseudo-second-order kinetics. Adsorption of dye was described by Langmuir and Freundlich isotherm. In adsorption isotherm, Langmuir isotherm was found to fit well with experimental data than Freundlich isotherm. The monolayer adsorption capacity was found to be 50 mg/g. The amount of dye adsorbed (q t ) increases from 17.31 to 159.62 mg/g as dye concentration increases from 20 to 80 mg/l for 0.4 g/l photocatalyst dose. The photocatalytic degradation of Safranine by ZnO-bentonite takes place by advanced oxidation process.

  20. Modeling early in situ wetting of a compacted bentonite buffer installed in low permeable crystalline bedrock

    NASA Astrophysics Data System (ADS)

    Dessirier, B.; Frampton, A.; Fransson, Å.; Jarsjö, J.

    2016-08-01

    The repository concept for geological disposal of spent nuclear fuel in Sweden and Finland is planned to be constructed in sparsely fractured crystalline bedrock and with an engineered bentonite buffer to embed the waste canisters. An important stage in such a deep repository is the postclosure phase following the deposition and the backfilling operations when the initially unsaturated buffer material gets hydrated by the groundwater delivered by the natural bedrock. We use numerical simulations to interpret observations on buffer wetting gathered during an in situ campaign, the Bentonite Rock Interaction Experiment, in which unsaturated bentonite columns were introduced into deposition holes in the floor of a 417 m deep tunnel at the Äspö Hard Rock Laboratory in Sweden. Our objectives are to assess the performance of state-of-the-art flow models in reproducing the buffer wetting process and to investigate to which extent dependable predictions of buffer wetting times and saturation patterns can be made based on information collected prior to buffer insertion. This would be important for preventing insertion into unsuitable bedrock environments. Field data and modeling results indicate the development of a de-saturated zone in the rock and show that in most cases, the presence or absence of fractures and flow heterogeneity are more important factors for correct wetting predictions than the total inflow. For instance, for an equal open-hole inflow value, homogeneous inflow yields much more rapid buffer wetting than cases where fractures are represented explicitly thus creating heterogeneous inflow distributions.

  1. Simultaneous sorption of phosphate and phenanthrene to inorgano-organo-bentonite from water.

    PubMed

    Ma, Jianfeng; Zhu, Lizhong

    2006-08-25

    The nonbiodegradable organic pollutants and excess phosphate can not be effectively removed from municipal wastewater by the widely used bioprocess, thus they are harmful to aquatic environment. In this investigation, the feasibility of utilizing inorgano-organo-bentonite (IOB), which was bentonite mineral modified with both Fe polycations and cetyltrimethylammonium bromide (CTMAB), was explored to simultaneously remove phosphate and phenanthrene from water. The results showed that the IOB had strong affinity for both phosphate and polycyclic aromatic hydrocarbons (PAHs) such as phenanthrene in water. It was found that more than 95% phosphate and 99% phenanthrene were removed from water within 30 min. The sorption of phosphate on IOB proved to be an anion/OH(-) exchange reaction. Compared with organobentonite and bentonite mineral, the settlement separation of IOB from aquatic phase was greatly improved. The residual turbidity reached a minimum value of 10 nephelometric turbidity units (NTU) in 60 min. It was indicated that IOB is a favorable sorbent and can simultaneously remove nonbiodegradable organic pollutants such as phenanthrene and phosphate after the bioprocess in wastewater treatment.

  2. Stability and thermal transformation studies of Zn2+- and Fe2+- loaded zeolite Y prepared from Egyptian kaolin

    NASA Astrophysics Data System (ADS)

    EL-Mekkawi, Doaa M.; Ibrahim, Fatma A.; Selim, Mohamed M.

    2015-10-01

    The stability and thermal transformation of Zn2+ and Fe2+- zeolites based kaolin were studied with respect to their loading experimental conditions. Zeolite Y prepared from Egyptian kaolin was used in our investigations. Zeolite shows different degrees of framework stability according to the type of cation and the loading experimental conditions. The obtained data indicate the predominance of adsorption and ion exchange mechanisms during Fe2+ and Zn2+ loading, respectively. The loading experimental conditions also greatly affect the solid-solid interactions of transition metal-zeolites at elevated temperatures. ZnAl2O4 and silica phases were formed upon thermal treatment of Zn-Y zeolites. The ratio of ZnAl2O4 to silica phases increases as the amount of loaded Zn2+ increases in the corresponding unheated zeolites. However, nepheline phase was obtained upon heating Fe-Y zeolites loaded at low initial Fe2+ concentrations. Upon increasing of loaded Fe2+, iron oxide beside other amorphous phases from silica, alumina and/or aluminosilicates were obtained.

  3. Heterogeneous Fenton oxidation of Direct Black G in dye effluent using functional kaolin-supported nanoscale zero iron.

    PubMed

    Liu, Xinwen; Wang, Feifeng; Chen, Zuliang; Megharaj, Mallavarapu; Naidu, Ravendra

    2014-02-01

    This study investigated kaolin-supported nanoscale zero-valent iron (nZVI/K) as a heterogeneous Fenton-like catalyst for the adsorption and oxidation of an azo dye, Direct Black G (DBG). New findings suggest that kaolin as a support material not only reduced the aggregation of nanoscale zero-valent iron (nZVI) but also improved the adsorption of DBG. It consequently improved Fenton oxidation by increasing the local concentration of DBG in the vicinity of nZVI. This was confirmed by scanning electron microscopy and X-ray diffraction for the surface morphology of nZVI/K before and after the Fenton-like reaction. Furthermore, nZVI/K proved to be a catalyst for the heterogeneous Fenton-like oxidation of the DBG process in the neutral pH range. More than 87.22 % of DBG was degraded, and 54.60 % of total organic carbon was removed in the optimal conditions: 0.6 g/L dosage of nZVI/K, 33 mM H2O2, 100 mg/L initial DBG concentration, temperature of 303 K and pH of 7.06. Finally, it was demonstrated that nZVI/K removed DBG from dye wastewater through the processes of adsorption and oxidation.

  4. Adsorption of polyoxyethylenic surfactants on quartz, kaolin, and dolomite: A correlation between surfactant structure and solid surface nature

    SciTech Connect

    Nevskaia, D.M.; Guerrero-Ruiz, A.; Lopez-Gonzalez, J.deD.

    1996-08-10

    Adsorption of a surfactant at a liquid-solid interface makes up the basis of many technological processes such as detergency, flotation, water treatment, and enhanced oil recovery. The influence of variables such as adsorption temperature, polar chain length, and nature of functional groups on the adsorption, from aqueous solutions, of various surfactants (TX-114, TX-100, TX-165, TX-305, NP1P4E, NP4P1E, NP4S, NP10S, and NP25S) has been investigated. Several nonporous solids, including various samples of quartz, kaolin, and dolomite, were studied. Conformational changes of adsorbed surfactant molecules on one quartz, when the oxyethylenic length of Tritons increases, have been detected. For all the other solid samples the surface is not completely covered by Tritons. On quartz, the surfactants are adsorbed by hydrogen bonds between the surfactant`s ether groups and the silanol groups of the solid surface. These hydroxyl groups must be free and sufficiently separated from other hydroxyls of the solid surface. When the number of propoxy groups increases (from NP1P4E to NP4P1E) the adsorbed amount of surfactant on the solid studied decreases. Anionic surfactants are adsorbed on quartz in lower amounts than the corresponding nonionic surfactants. However, the adsorbed amounts of Tritons and sulfated Tritons on kaolin are similar, probably due to the positive charges on the edges of this material.

  5. Dead-end flow filtration of solid suspension in polymer fluid through an active kaolin dynamic membrane

    SciTech Connect

    Wang, J.Y.; Chou, K.S.; Lee, C.J.

    1998-12-01

    In this study an active kaolin dynamic membrane formed on a SS-316 porous support was used to investigate the microfiltration of a solid suspension in polymer fluid. It was found that a homogeneous sodium acetate suspension in polymer can be completely removed by the active kaolin dynamic membrane to yield a very clear polymer product. The filtration rate as a function of operating temperature and pressure were experimentally determined. When the operating temperature was increased, the decreasing polymer viscosity resulted in an increase of filtration rate but was counteracted by the swelling effect of the membrane layer. Similarly, when the pressure was increased, the increase in driving force for filtration was counteracted by a simultaneous increase in particle packing. The filtration behavior of this dynamic membrane system was also simulated by the general blocking model d{sup 2}t/dV{sup 2} = k(dt/dV){sup q}, where q was found to have negative values. Negative q values mean that the system reached a maximum blocking rate during the initial period of filtration and then decreased gradually. When the blocking rate became small enough, the system behaved like cake filtration. A satisfactory fit between experimental data and theoretical calculations was demonstrated.

  6. The geological distribution of mixed-layered kaolinite/expandables (K/E) and its importance within the kaolin group

    SciTech Connect

    Hughes, R.E.; Moore, D.M. )

    1993-03-01

    Kaolin-group minerals form in soils by at least three alteration pathways: (1) halloysite forms under pH and ionic extremes, and continues to increase in crystallinity and crystallite sizes along its alteration pathway; (2) mixed-layered kaolinite/smectite or kaolinite/expandables (K/S or K/E) forms from 2:1 layer silicates and contains true expandable layers and inherited Fe[sup VI] and Al[sup IV] within its 7[angstrom] layers. Minor increases in crystallinity and crystallite size accompany further alteration along the K/E pathway; and (3) well-crystallized kaolinites, dickites, and nacrites precipitate from solution, mostly in reducing environments where Fe[sup 2+] is removed from solution by crystallization of sulfides or carbonates. Kaolinite formed along pathways 1 and 2 retains attributes of parent material, whereas kaolinite from pathway 3 retains little. K/E occurs in Recent loessal soils of the Midwest and in related glacigenic paleosols, Quaternary-Pliocene paleosols, Eocene ball clays and their source paleosols on the Porters Creek Clay, Jurassic paleosols in Ireland, and Pennsylvanian underclays. The characteristic properties of K/E imprint kaolinite formed along this pathway. The frequency with which this imprint is being found suggests that K/E is spatially and chronologically more widespread than previously reported and that wider recognition of this imprint will increase the understanding of many kaolin occurrences.

  7. Application of kaolin-based catalysts in biodiesel production via transesterification of vegetable oils in excess methanol.

    PubMed

    Dang, Tan Hiep; Chen, Bing-Hung; Lee, Duu-Jong

    2013-10-01

    Biodiesel production from transesterification of vegetable oils in excess methanol was performed by using as-prepared catalyst from low-cost kaolin clay. This effective heterogeneous catalyst was successfully prepared from natural kaolin firstly by dehydroxylation at 800°C for 10h and, subsequently, by NaOH-activation hydrothermally at 90°C for 24h and calcined again at 500°C for 6h. The as-obtained catalytic material was characterized with instruments, including FT-IR, XRD, SEM, and porosimeter (BET/BJH analysis). The as-prepared catalyst was advantageous not only for its easy preparation, but also for its cost-efficiency and superior catalysis in transesterification of vegetable oils in excess methanol to produce fatty acid methyl esters (FAMEs). Conversion efficiencies of soybean and palm oils to biodiesel over the as-prepared catalysts reached 97.0±3.0% and 95.4±3.7%, respectively, under optimal conditions. Activation energies of transesterification reactions of soybean and palm oils in excess methanol using these catalysts are 14.09 kJ/mol and 48.87 kJ/mol, respectively.

  8. Influence of (calcium-)uranyl-carbonate complexation on U(VI) sorption on Ca- and Na-bentonites.

    PubMed

    Meleshyn, A; Azeroual, M; Reeck, T; Houben, G; Riebe, B; Bunnenberg, C

    2009-07-01

    The influence of uranyl-carbonate and calcium-uranyl-carbonate complexations on the kinetics of U(VI) (approximately 3.4 x 10(-3) mol L(-1)) sorption from NaNO3 and Ca(NO3)2 solutions on Na- and Ca-bentonites at circumneutral ambient conditions was investigated. Complexation of U(VI) in Ca2UO2(CO3)3(aq) aqueous species, dominating the U(VI) speciation in Ca(NO3)2 solution, reduces its adsorption on bentonite by a factor of 2-3 in comparison with that in (UO2)2CO3(OH)3- species, dominating in NaNO3 solution, within the studied period of time (21 days). As a result of the dissolution of accessory calcite, Ca2UO2(CO3)3(aq) can be formed in the initially Ca-free solution in contact with either Na- or Ca-bentonite. U(VI) adsorption on Na-bentonite is a factor of approximately 2 higher than that on Ca-bentonite for solutions with the Ca2UO2(CO3)3(aq) complex dominating aqueous U(VI) speciation. This favors use of Na-bentonite over that of Ca-bentonite in final disposal of radioactive waste. Furthermore, the observed strong correlation between U(VI) adsorption and Mg release as a result of montmorillonite dissolution indicates in agreement with previous findings that under the applied conditions U(VI) is adsorbed on the edge surface of montmorillonite, which is a major mineral phase of the studied clays.

  9. Organophilic treatments of bentonite increase the adsorption of aflatoxin B1 and protect stem cells against cellular damage.

    PubMed

    Nones, Janaína; Nones, Jader; Poli, Anicleto; Trentin, Andrea Gonçalves; Riella, Humberto Gracher; Kuhnen, Nivaldo Cabral

    2016-09-01

    Bentonite clays exhibit high adsorptive capacity for contaminants, including aflatoxin B1 (AFB1), a mycotoxin responsible for causing severe toxicity in several species including pigs, poultry and man. Organophilic treatments is known to increase the adsorption capacity of bentonites, and the primary aim of this study was to evaluate the ability of Brazilian bentonite and two organic salts - benzalkonium chloride (BAC) and cetyltrimethylammonium bromide (CTAB) to adsorb AFB1. For this end, 2(2) factorial designs were used in order to analyze if BAC or CTAB was able to increase AFB1 adsorption when submitted in different temperature and concentration. Both BAC and CTAB treatment (at 30°C and 2% of salt concentration) were found to increase the adsorption of AFB1 significantly compared with untreated bentonite. After organophilic bentonite treatments with BAC or CTAB, a vibration of CH stretch (2850 and 2920cm(-1)) were detected. A frequency of the SiO stretch (1020 and 1090cm(-1)) was changed by intercalation of organic cation. Furthermore, the interlayer spacing of bentonite increases to 1.23nm (d001 reflection at 2θ=7.16) and 1.22 (d001 reflection at 2θ=7.22) after the addition of BAC and CTAB, respectively. Another aim of the study was to observe the effects of these two bentonite salts in neural crest stem cell cultures. The two materials that were created by organophilic treatments were not found to be toxic to stem cells. Furthermore the results indicate that the two materials tested may protect the neural crest stem cells against damage caused by AFB1.

  10. 137Cs sorption into bentonite from Cidadap-Tasikmalaya as buffer material for disposal demonstration plant facility at Serpong

    NASA Astrophysics Data System (ADS)

    Setiawan, B.; Sriwahyuni, H.; Ekaningrum, NE.; Sumantry, T.

    2014-03-01

    According to co-location principle, near surface disposal type the disposal demonstration plant facility will be build at Serpong nuclear area. The facility also for anticipation of future needs to provide national facility for the servicing of radwaste management of non-nuclear power plant activity in Serpong Nuclear Area. It is needs to study the material of buffer and backfill for the safety of demonstration plant facility. A local bentonite rock from Cidadap-Tasikmalaya was used as the buffer materials. Objective of experiment is to find out the specific data of sorption characteristic of Cidadap bentonite as buffer material in a radwaste disposal system. Experiments were performed in batch method, where bentonite samples were contacted with CsCl solution labeled with Cs-137 in 100 ml/g liquid:solid ratio. Initial Cs concentration was 10-8 M and to study the effects of ionic strength and Cs concentration in solution, 0.1 and 1.0 M NaCl also CsCl concentration ranging 10-8 - 10-4 M were added in solution. As the indicator of Cs saturated in bentonite samples, Kd value was applied. Affected parameters in the experiment were contact time, effects of ionic strength and concentration of CsCl. Results showed that sorption of Cs by bentonite reached constantly after 16 days contacted, and Kd value was 10.600 ml/g. Effect of CsCl concentration on Kd value may decreased in increased in CsCl concentration. Effect of ionic strength increased according to increased in concentration of background and would effect to Kd value due to competition of Na ions and Cs in solution interacts with bentonite. By obtaining the bentonite character data as buffer material, the results could be used as the basis for making of design and the basic of performance assessment the near surface disposal facility in terms of isolation capacity of radwaste later.

  11. {sup 137}Cs sorption into bentonite from Cidadap-Tasikmalaya as buffer material for disposal demonstration plant facility at Serpong

    SciTech Connect

    Setiawan, B. Sriwahyuni, H. Ekaningrum, NE. Sumantry, T.

    2014-03-24

    According to co-location principle, near surface disposal type the disposal demonstration plant facility will be build at Serpong nuclear area. The facility also for anticipation of future needs to provide national facility for the servicing of radwaste management of non-nuclear power plant activity in Serpong Nuclear Area. It is needs to study the material of buffer and backfill for the safety of demonstration plant facility. A local bentonite rock from Cidadap-Tasikmalaya was used as the buffer materials. Objective of experiment is to find out the specific data of sorption characteristic of Cidadap bentonite as buffer material in a radwaste disposal system. Experiments were performed in batch method, where bentonite samples were contacted with CsCl solution labeled with Cs-137 in 100 ml/g liquid:solid ratio. Initial Cs concentration was 10{sup −8} M and to study the effects of ionic strength and Cs concentration in solution, 0.1 and 1.0 M NaCl also CsCl concentration ranging 10{sup −8} - 10{sup −4} M were added in solution. As the indicator of Cs saturated in bentonite samples, Kd value was applied. Affected parameters in the experiment were contact time, effects of ionic strength and concentration of CsCl. Results showed that sorption of Cs by bentonite reached constantly after 16 days contacted, and Kd value was 10.600 ml/g. Effect of CsCl concentration on Kd value may decreased in increased in CsCl concentration. Effect of ionic strength increased according to increased in concentration of background and would effect to Kd value due to competition of Na ions and Cs in solution interacts with bentonite. By obtaining the bentonite character data as buffer material, the results could be used as the basis for making of design and the basic of performance assessment the near surface disposal facility in terms of isolation capacity of radwaste later.

  12. Migration Behavior of Plutonium in Compacted Bentonite Under Reducing Condition Using Electromigration

    SciTech Connect

    Kazuya Idemitsu; Yosuke Yamasaki; Syeda Afsarun Nessa; Yaohiro Inagaki; Tatsumi Arima; Toshiaki Mitsugashira; Mitsuo Hara; Yoshimitsu Suzuki

    2007-07-01

    Carbon steel is one of the candidate overpack materials for high-level waste disposal and is expected to assure complete containment of vitrified waste glass during an initial period of 1000 years in Japan. Carbon steel overpack will be corroded by consuming oxygen introduced by repository construction after closure of repository and then will keep the reducing environment in the vicinity of repository. The migration of iron corrosion products through the buffer material will affect migration of redox-sensitive radionuclides. Therefore the authors have carried out electromigration experiments with source of iron ions supplied by anode corrosion of iron coupons attached to compacted bentonite. Authors tried to use plutonium in this experimental configuration to obtain the knowledge of migration behavior of actinides. Authors also used cesium as reference. The concentrations of iron and sodium showed nearly complementary distributions. It is expected that iron ion could migrate as ferrous ion through the interlayer of montmorillonite replacing exchangeable sodium ions in the interlayer. Concentration profiles of plutonium in bentonite grew as time supplying electric potential as long as 168 h. Plutonium migrated from the iron anode toward cathode as deeper than 1 mm of the interior of bentonite even in 48 h, though plutonium could not diffuse 1 mm for 2 years. On the other hand, profiles of cesium were reported to be controlled by ordinary diffusion because of large diffusion coefficient of cesium in bentonite as large as 10{sup -12} m{sup 2}/s. Drift of the cesium profile by electric potential gradient could be observed clearly after 240 h at individual experiment for cesium. Apparent dispersion coefficients of plutonium were calculated from the profiles and were as large as 10{sup -13} m{sup 2}/s. Since plutonium migration was accelerated by electric potential, plutonium chemical species would have positive charge and were estimated as PuOH{sup 2+} or PuCl{sup 2

  13. Geochemical modelling of bentonite porewater in high-level waste repositories

    NASA Astrophysics Data System (ADS)

    Wersin, Paul

    2003-03-01

    The description of the geochemical properties of the bentonite backfill that serves as engineered barrier for nuclear repositories is a central issue for perfomance assessment since these play a large role in determining the fate of contaminants released from the waste. In this study the porewater chemistry of bentonite was assessed with a thermodynamic modelling approach that includes ion exchange, surface complexation and mineral equilibrium reactions. The focus was to identify the geochemical reactions controlling the major ion chemistry and acid-base properties and to explore parameter uncertainties specifically at high compaction degrees. First, the adequacy of the approach was tested with two distinct surface complexation models by describing recent experimental data performed at highly varying solid/liquid ratios and ionic strengths. The results indicate adequate prediction of the entire experimental data set. Second, the modelling was extended to repository conditions, taking as an example the current Swiss concept for high-level waste where the compacted bentonite backfill is surrounded by argillaceous rock. The main reactions controlling major ion chemistry were found to be calcite equilibrium and concurrent Na-Ca exchange reactions and de-protonation of functional surface groups. Third, a sensitivity analysis of the main model parameters was performed. The results thereof indicate a remarkable robustness of the model with regard to parameter uncertainties. The bentonite system is characterised by a large acid-base buffering capacity which leads to stable pH-conditions. The uncertainty in pH was found to be mainly induced by the pCO 2 of the surrounding host rock. The results of a simple diffusion-reaction model indicate only minor changes of porewater composition with time, which is primarily due to the geochemical similarities of the bentonite and the argillaceous host rock. Overall, the results show the usefulness of simple thermodynamic models to

  14. Laboratory investigation of the role of desorption kinetics on americium transport associated with bentonite colloids

    SciTech Connect

    Dittrich, Timothy Mark; Boukhalfa, Hakim; Ware, Stuart Douglas; Reimus, Paul William

    2015-07-13

    Understanding the parameters that control colloid-mediated transport of radionuclides is important for the safe disposal of used nuclear fuel. We report an experimental and reactive transport modeling examination of americium transport in a groundwater–bentonite–fracture fill material system. A series of batch sorption and column transport experiments were conducted to determine the role of desorption kinetics from bentonite colloids in the transport of americium through fracture materials. We used fracture fill material from a shear zone in altered granodiorite collected from the Grimsel Test Site (GTS) in Switzerland and colloidal suspensions generated from FEBEX bentonite, a potential repository backfill material. The colloidal suspension (100 mg L–1) was prepared in synthetic groundwater that matched the natural water chemistry at GTS and was spiked with 5.5 × 10–10 M241Am. Batch characterizations indicated that 97% of the americium in the stock suspension was adsorbed to the colloids. Breakthrough experiments conducted by injecting the americium colloidal suspension through three identical columns in series, each with mean residence times of 6 h, show that more than 95% of the bentonite colloids were transported through each of the columns, with modeled colloid filtration rates (kf) of 0.01–0.02 h–1. Am recoveries in each column were 55–60%, and Am desorption rate constants from the colloids, determined from 1-D transport modeling, were 0.96, 0.98, and 0.91 h–1 in the three columns, respectively. The consistency in Am recoveries and desorption rate constants in each column indicates that the Am was not associated with binding sites of widely-varying strengths on the colloids, as one binding site with fast kinetics represented the system accurately for all three sequential columns. As a result, our data suggest that colloid-mediated transport of Am in a bentonite-fracture fill

  15. Laboratory investigation of the role of desorption kinetics on americium transport associated with bentonite colloids

    DOE PAGES

    Dittrich, Timothy Mark; Boukhalfa, Hakim; Ware, Stuart Douglas; ...

    2015-07-13

    Understanding the parameters that control colloid-mediated transport of radionuclides is important for the safe disposal of used nuclear fuel. We report an experimental and reactive transport modeling examination of americium transport in a groundwater–bentonite–fracture fill material system. A series of batch sorption and column transport experiments were conducted to determine the role of desorption kinetics from bentonite colloids in the transport of americium through fracture materials. We used fracture fill material from a shear zone in altered granodiorite collected from the Grimsel Test Site (GTS) in Switzerland and colloidal suspensions generated from FEBEX bentonite, a potential repository backfill material. Themore » colloidal suspension (100 mg L–1) was prepared in synthetic groundwater that matched the natural water chemistry at GTS and was spiked with 5.5 × 10–10 M241Am. Batch characterizations indicated that 97% of the americium in the stock suspension was adsorbed to the colloids. Breakthrough experiments conducted by injecting the americium colloidal suspension through three identical columns in series, each with mean residence times of 6 h, show that more than 95% of the bentonite colloids were transported through each of the columns, with modeled colloid filtration rates (kf) of 0.01–0.02 h–1. Am recoveries in each column were 55–60%, and Am desorption rate constants from the colloids, determined from 1-D transport modeling, were 0.96, 0.98, and 0.91 h–1 in the three columns, respectively. The consistency in Am recoveries and desorption rate constants in each column indicates that the Am was not associated with binding sites of widely-varying strengths on the colloids, as one binding site with fast kinetics represented the system accurately for all three sequential columns. As a result, our data suggest that colloid-mediated transport of Am in a bentonite-fracture fill material system is unlikely to result in transport over long

  16. The kinetics of the smectite to illite transformation in Cretaceous bentonites, Cerro Negro, New Mexico

    SciTech Connect

    Elliot, W C.; Edenfield, N M.; Wampler, J M.; Matisoff, G; Long, Philip E. )

    1998-12-01

    The thermal effects, as well as the survivability and origins of microorganisms in Cretaceous rocks, are evaluated from the timing and extent of the smectite to illite transformation in Cretaceous bentonites collected from cores outside the thermal aureole of the Pliocene Cerro Negro volcanic neck. Overall, randomly ordered mixed-layered illite-smectite (I-S) is the predominant clay mineral in these bentonites, and the K-Ar ages of I-S range from 36 to 48 Ma (21 analyses, two additional analyses were outside this range). Increased temperature from burial is thought to be the primary factor forming I-S in these bentonites. Kinetic model calculations of the smectite to illite transformation are also consistent with T-S formed by burial without any appreciable thermal effects due to the emplacement of Cerro Negro. In a core angled toward Cerro Negro, the percentages of illite layers in I-S from the bentonite closest to Cerro Negro are slightly higher (32-37%) than in most other bentonites in this study. The K-Ar ages of the closest I-S are slightly younger as a group (38-43 Ma; Average= 41 Ma; N= 4) than those of I-S further from Cerro Negro in the same core (41-48 Ma; Average= 44 Ma; N= 6). A small amount of illite in this I-S may have formed by heat from the emplacement of Gene Negro, but most illite formed from burial. Vitrinite reflectance, however, appears to record the effects of heating from Cerro Negro better than I-S. Tentatively, the temperature of this heat pulse, based on vitrinite data alone, ranged from 100 to 125 degrees C and this is most evident in the CNAR core. The upper temperature, 125 degrees C, approximates the sterilization temperatures for most microorganisms, and these temperatures probably reduced a significant portion of the microbial population. Thermophiles may have survived the increased temperatures from the combined effects of burial and the intrusion of Cerro Negro.

  17. Chemical-looping combustion of simulated synthesis gas using nickel oxide oxygen carrier supported on bentonite

    SciTech Connect

    Siriwardane, R.V.; Chaudhari, K.; Poston, J.A.; Zinn, A.; Simonyi, T.; Robinson, C.

    2007-05-01

    Chemical-looping combustion (CLC) is a combustion technology for clean and efficient utilization of fossil fuels for energy production. This process which produces sequestration ready CO2 systems is a promising technology to be utilized with coal gasification systems. In the present work, chemical-looping combustion has been studied with an oxygen carrier, NiO/bentonite (60 wt % NiO) for the gasification systems utilizing simulated synthesis gas. Global reaction rates of reduction and oxidation as a function of conversion were calculated for oxidation-reduction cycles utilizing the thermogravimetric analysis (TGA) data on multicycle tests conducted with NiO/bentonite at atmospheric pressure between 700 and 900 °C. The rate of reduction increased slightly with an increase in temperature, while the rate of oxidation decreased at 900 °C. The effect of particle size of the oxygen carrier on CLC was studied for the particle size between 20 and 200 mesh. The rates of reactions depended on the particle size of the oxygen carrier. The smaller the particle size, the higher the reaction rates. The multicycle CLC tests conducted in a high-pressure flow reactor showed stable reactivity for the production of CO2 from fuel gas at 800 and 900 °C and full consumption of hydrogen during the reaction. The data from a one cycle test on the effect of the pressure on the performance with NiO/bentonite utilizing the tapered element oscillating microbalance (TEOM) showed a positive effect of the pressure on the global rates of reduction-oxidation reactions at higher fractional conversions. The X-ray diffraction (XRD) analysis confirmed the presence of the NiO phase in NiO/bentonite with the oxidized sample in the highpressure reactor and Ni phase with the reduced sample. The presence of a small amount of NiO in the reduced sample detected by X-ray photoelectron spectroscopy (XPS) may be due to its exposure to air during sample transfer from the reactor to XPS. Scanning electron

  18. Microstructural investigation of MX-80 bentonite and Na/Ca-montmorillonite using basal spacing determination

    NASA Astrophysics Data System (ADS)

    Holmboe, M.; Wold, S.

    2010-12-01

    Knowledge about the microstructure of saturated compacted bentonite is of fundamental importance in order to describe and predict diffusive transport through the bentonite barrier in a deep geological repository. If the mineral composition is well characterized, microstructural models of compacted bentonite on the nanoscale can be based on accurate information of the basal spacings and corresponding interlayer distances within the montmorillonite particles. From the average basal spacing, the interlayer and the so-called interparticle or free porosity can be calculated [1]. The basal spacings of the montmorillonite particles can be measured by neutron and X-ray small-angle scattering or diffraction. However, due to microstructural heterogeneity and interstratification of different hydration states, profile fitting through mixed layered modeling is necessary although challenging [2,3]. In this study, we have used low-angle XRD in reflection mode together with one-dimensional analysis of mixed layered clays [2] in order to compare both the relative layer distribution and average basal spacing of MX-80 bentonite and Na/Ca-montmorillonite samples. Two different methods for water saturation commonly used in the literature were compared, saturation by constant relative humidity (adsorption and desorption) and saturation under constant volume conditions, forming compacted clay with dry densities of 0.5-1.8 g/cm3. No significant difference in basal spacings was observed between highly compacted (< 4 H2O layers) homoionic montmorillonite and MX-80 bentonite samples saturated under volume constricted conditions, if the accessory minerals and lower smectite content was accounted for. This was however not the case for the samples saturated at constant RH%, which indicates mixing of the exchangeable cations in the interlayers. Interestingly, even if the total water content was the same water uptake restricted by water activity did not always result in the same magnitude of

  19. Alginate-immobilized bentonite clay: adsorption efficacy and reusability for Cu(II) removal from aqueous solution.

    PubMed

    Tan, Wei Shang; Ting, Adeline Su Yien

    2014-05-01

    This study evaluated the use of alginate-immobilized bentonite to remove Cu(II) as an alternative to mitigate clogging problems. The adsorption efficacy (under the influence of time, pH and initial Cu(II) concentration) and reusability of immobilized-bentonite (1% w/v bentonite) was tested against plain alginate beads. Results revealed that immobilized bentonite demonstrated significantly higher sorption efficacy compared to plain alginate beads with 114.70 and 94.04 mg Cu(II) adsorbed g(-1) adsorbent, respectively. Both sorbents were comparable in other aspects where sorption equilibrium was achieved within 6 h, with optimum pH between pH 4 and 5 for adsorption, displayed maximum adsorption capacity at initial Cu(II) concentrations of 400 mg l(-1), and demonstrated excellent reusability potential with desorption greater than 90% throughout three consecutive adsorption-desorption cycles. Both sorbents also conformed to Langmuir isotherm and pseudo-second order kinetic model. Immobilized bentonite is therefore recommended for use in water treatments to remove Cu(II) without clogging the system.

  20. The concentration and pH dependent diffusion of 137Cs in compacted bentonite by using capillary method

    NASA Astrophysics Data System (ADS)

    Wang, Xiangke; Tan, Xiaoli; Chen, Changlun; Chen, Lei

    2005-10-01

    The 'in-diffusion' method was used to study the diffusion behavior of radionuclide 137Cs in compacted bentonite using a capillary. The results (distribution coefficient, Kd, apparent and effective diffusion coefficients, Da and De) derived from the capillary method are in good agreement with the literature data, and fit the Fick's second law very well. The experiments were carried out at 3.3 × 10-3 and 3.3 × 10-5mol/l cesium, pH 3-12, ionic strength 0.1 M NaClO4, and at room temperature. The results suggest that the diffusion of cesium in compacted bentonite is dependent on solution concentrations and pH values. In agreement with the literatures, the Kd values derived from the capillary experiments are in most cases lower than those derived from batch experiments: the Kd values are about one-half to one-third the values of those from batch experiments. The interlaminary space plays a very important role to the sorption, diffusion and transport of Cs+ in compacted bentonite. The effective diffusion coefficient is higher than that of other nuclides in compacted bentonite, and the diffusion of cesium in compacted bentonite may be dominated by the surface diffusion.

  1. A fully coupled three-dimensional THM analysis of the FEBEX in situ test with the ROCMAS Code: Prediction of THM behavior in a bentonite barrier

    SciTech Connect

    Rutqvist, J.; Tsang, C-F.

    2003-09-01

    This paper presents a fully coupled thermal-hydrological-mechanical analysis of FEBEX--a large underground heater test conducted in a bentonite and fractured rock system. System responses predicted by the numerical analysis--including temperature, moisture content, and bentonite-swelling stress--were compared to field measurements at sensors located in the bentonite. An overall good agreement between predicted and measured system responses shows that coupled thermal-hydrological-mechanical processes in a bentonite barrier are well represented by the numerical model. The most challenging aspect of this particular analysis was modeling of the bentonite's mechanical behavior, which at FEBEX turned out to be affected by gaps between prefabricated bentonite blocks. At FEBEX, the swelling pressure did not develop until a few months into the experiment when moisture swelling of bentonite blocks had closed the gaps completely. Moreover, the wetting of the bentonite took place uniformly from the rock and was not impacted by the permeability difference between the Lamprophyres dykes and surrounding rock.

  2. Effects of water deficit stress, shade, weed competition, and kaolin particle film on selected foliar free amino acid accumulations in cotton, Gossypium hirsutum (L.).

    PubMed

    Showler, Allan T

    2002-03-01

    Leaves of cotton plants, Gossypium hirsutum L., stressed by water deficit, reduced daylight, and weed competition, or treated with a kaolin wettable powder formulation were analyzed for levels of 17 free amino acids (FAAs) using reversed-phase high-performance liquid chromatography. Water deficit stress resulted in heightened free proline levels (49.9-fold, P < 0.001) that were correlated with diffusive resistance (seconds per centimeter). Five other FAAs increased, and the amounts of total free essential (for insect growth and development) amino acids and total FAAs also increased (P < or = 0.05). Cotton grown in 50% shade accumulated significantly more free arginine than control plants. In a small-plot weed competition assay, four FAAs increased and three FAAs decreased in association with weed competition, but because free proline levels were not altered and free arginine levels increased, other stresses aside from water deficit, possibly including shading by tall weeds, appear to have caused the changes. In a small-plot kaolin particle film assay, five FAAs were lower in cotton foliage sprayed weekly with kaolin. Because free proline was unaffected and free arginine was lower, it is possible that kaolin's reflectivity heightened light reception. The responses of free proline and arginine to the treatments used in these assays demonstrate that types and degrees of some stresses to cotton can be characterized by accumulations of certain FAAs. The study also demonstrates how some FAA levels can indicate degrees of cotton stress resulting from weed competition and from kaolin particle film application. Porometry and leaf water potential measurements assisted in corroborating some findings of the study.

  3. Treatment of an acid soil with bentonite used for wine fining: effects on soil properties and the growth of Lolium multiflorum.

    PubMed

    Arias-Estévez, Manuel; López-Periago, Eugenio; Nóvoa-Muñoz, Juan C; Torrado-Agrasar, Ana; Simal-Gándara, Jesus

    2007-09-05

    When used to fine wines, bentonite acquires a protein load that makes it a potentially useful fertilizer. Other properties of bentonite are also potentially useful for soil amendment. In the work described in this paper, waste bentonite from a winery was applied to an acid soil, and its effects on soil properties and on the growth of Lolium multiflorum were evaluated. Soil N, K, and P contents all increased, as did pH and cation exchange capacity. Biomass production increased as the dose of bentonite increased up to 5 g kg(-1), decreasing at larger doses (possibly as a result of falling potassium/magnesium ratio and increasing electrical conductivity). Environmental drawbacks of waste bentonite include its high soluble copper content, although its conversion in the soil to less soluble forms reduces its potential phytotoxicity. The copper, manganese, and zinc contents of the ryegrass crop were low.

  4. 40Ar-39Ar ages of bentonite beds in the upper part of the Yazoo Formation (Upper Eocene), west-central Mississippi

    USGS Publications Warehouse

    Obradovich, J.D.; Dockery, D. T.; Swisher, C. C.

    1993-01-01

    Bentonite beds recorded from both outcrops and cores in the upper Eocene Yazoo Formation offer opportunities to date the uppermost Eocene of this region and to provide information on the age of the Eocene/Oligocene boundary. This report gives radiometric age dates for three bentonites sampled from the upper Yazoo Formation. Two bentonites are from outcrops near Satartia in western Mississippi and one is from a core hole at Society Ridge in west-central Mississippi. The upper bentonite at Satartia was studied independently at two laboratories using different techniques but with the same results, an age of 34.3 Ma (million years). Results from the Society Ridge bentonite gave the same age. -from Authors

  5. Prolonged triboluminescence in clays and other minerals

    NASA Technical Reports Server (NTRS)

    Lahav, N.; Coyne, L. M.; Lawless, J. G.

    1982-01-01

    The decay curves of various triboluminescent-excited materials were obtained, including well-crystallized and poorly crystallized kaolin, bentonite, quartz, sodium chloride, and chalk calcite. A qualitative increase in triboluminescence was observed for kaolin dipped in water or tryptophan solution compared to dry kaolin, and for frozen kaolin and montmorillonite pastes. Theoretical explanations for the tryptophan effect are discussed.

  6. Concurrent removal of humic acid and o-dichlorobenzene in drinking water by combined ozonation and bentonite coagulation process.

    PubMed

    Gu, Li; Zhang, Xingwang; Lei, Lecheng; Liu, Xianjun

    2009-01-01

    Combined ozonation and bentonite coagulation process (COBC) was investigated as a method of concurrently removing humic acid (HA) and o-dichlorobenzene (DCB) from drinking water. In this process, HA and DCB were removed by joint effect of catalytic ozonation and bentonite coagulation. HA removal was highly dependent on the coagulation process while DCB removal was dependent on the oxidation process in COBC. Iron in solution not only acted as a coagulant, but also promoted the formation of HO, which is effective in destroying aromatic chemicals. Bentonite in COBC improved the coagulation process, resulting in an enhancement in the treating efficiency. COBC is proved to be potentially advantageous on dissolved pollutants in drinking water, and appears to have great potential for a wide range of practical applications.

  7. Impact of bentonite additions during vinification on protein stability and volatile compounds of Albariño wines.

    PubMed

    Lira, Eugenio; Rodríguez-Bencomo, Juan José; Salazar, Fernando N; Orriols, Ignacio; Fornos, Daniel; López, Francisco

    2015-03-25

    Today, bentonite continues to be one of the most used products to remove proteins in white wines in order to avoid their precipitation in bottles. However, excessive use of bentonite has negative effects on the aroma of final wine, so the optimization of the dose and the time of its application are important for winemakers. This paper analyzes how applying an equal dose of bentonite at different stages (must clarification; beginning, middle, and end of fermentation) affects the macromolecular profile, protein stability, physical-chemical characteristics and aromatic profile of the wine obtained. The results showed the addition during fermentation (especially in the middle and at the end) reduced the total dose required for protein stabilization of Albariño wines and maintained the sensory characteristics of this variety.

  8. Parametric studies on confinement of radionuclides in the excavated damaged zone due to bentonite type and temperature change

    NASA Astrophysics Data System (ADS)

    Borrelli, R. A.; Thivent, Olivier; Ahn, Joonhong

    A parametric study is presented in this paper in order to examine the potential of the extruding bentonite into a fracture in the EDZ to confine radionuclides. Radionuclide migration of cesium and neptunium were studied at elevated temperatures and for a sodium- and calcium-type bentonite. Parameter values were obtained based on empirical studies for hydraulic conductivity, molecular diffusion, and sorption. Results indicate extrusion speed is affected by temperature changes. Elevated temperatures also affect radionuclide migration. For Cs, migration is enhanced due to decreasing sorption, while Np migration is inhibited due to increasing sorption. The potential to confine radionuclides is favorable, and the choice of bentonite does not seem to affect radionuclide confinement in the extruding region.

  9. Observations regarding the stability of bentonite backfill in a high-level waste (HLW) repository in rock salt

    SciTech Connect

    Krumhansl, J.L.

    1986-01-01

    Consideration of bentonite as a component of the engineered barrier system surrounding high-level nuclear waste (HLW) canisters in rock salt raised several questions regarding the stability of this clay. Dehydration studies pertinent to the period immediately following waste emplacement showed a partial loss in swelling ability, the extent of which depended on the composition of the rehydrating brine and increased with temperature from 150/sup 0/ to 320/sup 0/C. At a later date, hydrothermal reactions between brine and bentonite may occur as pressure in the repository rises and the backfill saturates with brine. In pure sodium chloride brines little change in the bentonite was observed after two months at 250/sup 0/C. In the same amount of time, brines rich in potassium formed mixed-layer, illite-smectite clays. Adding magnesium to the brine arrested mixed-layer clay formation; instead, a magnesium-enriched montmorillonite formed and the brine pH dropped. Radiation stability studies to 10/sup 10/ rads were conducted in both wet and dry environments, but caused no detectable alteration of the clay. In contrast, fluid-phase compositions changed significantly. Gamma irradiation of dry bentonite produced an oxygen-depleted atmosphere which was enriched in both hydrogen and carbon dioxide. Mixed bentonite-brine slurries produced copious amounts of both hydrogen and oxygen gas when irradiated. These irradiated slurries generally had posttest pH values between 4 and 6. Solutions made by exposing preirradiated salt and bentonite to unirradiated water, or brine, had pH values between 6 and 8.5 and, in the case of salt solutions, were highly oxidizing. Although more research is needed for a complete performance assessment, it appears that such backfills may prove useful in a variety of rock-salt environments.

  10. Hydration of bentonite in natural waters: Application of “confined volume” wet-cell X-ray diffractometry

    NASA Astrophysics Data System (ADS)

    Warr, Laurence; Berger, Julia

    The hydration behavior of compacted bentonites (Na- and Ca-montmorillonite varieties) in natural ground and sea water is studied using in situ wet-cell X-ray diffraction monitoring techniques. This approach allows us to determine the mechanism and rate of solution uptake in a confined volume, flow-through reactor and serves as an experimental analogue for predicting the performance of repository clay sealants. The pressed bentonite powders (densities of 0.94-1.14 g/cm 3) show continuous and strongly partitioned water uptake into montmorillonite interlayers, onto clay particle surfaces and within open pore spaces. During the hydration of compacted Na-bentonite in both ground and sea water, roughly equal quantities of both interlayer and non-interlayer water enter the material. In contrast, the Ca-bentonite was dominated by the intake of more loosely bound, surface and pore water, which amounted to roughly three times more than that incorporated into interlayer sites. Our experiments demonstrate how a confined reaction volume and the strength of the ionic solution both inhibit the interlayer expansion process. Based on the weakly compacted Na-bentonite analogue, a 1 m thick clay sealant is predicted to saturate within 7 years when infiltrated by typical continental ground water, and within 3 years in the case of a sea water breach. As significant volumes of solution are incorporated as loosely bound, non-interlayer water, quantification of the mechanism and rate of water storage is a necessary requirement for improved modeling of elemental transport in a hydrating bentonite medium.

  11. Long term chemo-hydro-mechanical behavior of compacted soil bentonite polymer complex submitted to synthetic leachate.

    PubMed

    Razakamanantsoa, Andry Rico; Djeran-Maigre, Irini

    2016-07-01

    An experimental program is carried out to investigate the long term hydro-mechanical behavior correlated with chemical one of compacted soils with low concentration of Ca-bentonite and Ca-bentonite polymer mixture. The effect of prehydration on the hydraulic performance is compared to the polymer adding effect. All specimens are submitted to synthetic leachate (LS) under different permeation conditions. Several issues are studied: mechanical stability, hydraulic performance, chemical exchange of cations validated with microstructure observations. Scanning Electron Microscope (SEM) observations demonstrate two distinct behaviors: dispersive for Bentonite (B) and B with Polymer P1 (BP1) and flocculated for B with Polymer P2 (BP2). Direct shear tests show that bentonite adding increases the Soil (S) cohesion and decreases the friction angle. Polymer adding behaves similarly by maintaining the soil cohesion and increasing the friction angle. Hydraulic conductivity of prehydrated soil bentonite (SB) and direct permeation of polymer added soil bentonite are studied (SBP1 and SBP2). Hydraulic test duration are in range of 45days to 556days long. Prehydration allows to delay the aggressive effect of the LS in short term but seems to increase its negative effect on the hydraulic conductivity value in long term exposure. SB and SBP1 behave similarly and seem to act in the long term as a granular filler effect. SBP2 presents positive results comparing to the other mixtures: it maintains the hydraulic conductivity and the chemical resistance. Chemical analysis confirms that all specimens are subjected to Na(+) dissolution and Ca(2+) retention which are more pronounced for prehydrated specimen. The short term effect of prehydration and the positive effect of SBP2 are also confirmed.

  12. Effect of ultrasound on the structural and textural properties of copper-impregnated cerium-modified zirconium-pillared bentonite

    NASA Astrophysics Data System (ADS)

    Tomul, Fatma

    2011-12-01

    In this study, the synthesis of zirconium-pillared bentonite modified with cerium was performed via two different methods by the application of conventional and ultrasonic treatments during the intercalation stage. To synthesise copper-impregnated pillared clays by wet impregnation, cerium-modified zirconium-pillared clays were used as supportive materials after being calcined at 300 °C. Ultrasonic treatment significantly decreased the required processing time compared with the conventional treatment of the synthesised pillared bentonites. Chemical analysis confirmed the incorporation of Zr 4+, Ce 4+ and Cu 2+ species into the pillared bentonites. X-ray diffraction (XRD) patterns of zirconium- and cerium/zirconium-pillared bentonites prepared by conventional treatment show that one large d-spacing above 3.5 nm corresponds to the mesoporous delaminated part, and another small d-spacing above 1.7 nm is indicative of the microporous pillared part. Zirconium- and cerium/zirconium-pillared bentonites prepared via ultrasonic treatment exhibited similar results, with the same high d-spacing but with a second low-intensity d-spacing above 1.9 nm. The delaminated structures of the pillared bentonites synthesised by both methods were conserved after copper impregnation. Nitrogen-adsorption isotherm analysis showed that the textural characteristics of products synthesised by ultrasonic treatment were comparable to those of products synthesised by conventional treatment. Fourier-transform infrared spectroscopy (FTIR) analyses showed the presence of Brønsted- and Lewis-acid sites, and zirconium-pillared clays synthesised by conventional treatment exhibited increased numbers of Brønsted- and Lewis-acid sites after cerium addition and copper impregnation. However, the products synthesised by ultrasonic treatment exhibited an increased number of Brønsted- and Lewis-acid sites after cerium addition, but a decreased number of acid sites after copper impregnation.

  13. Conodont and k-bentonite stratigraphy across the Blackriveran/Trentonian (Ordovician) boundary, north-central New York

    SciTech Connect

    Leslie, S.A.; Bergstroem, S.M. . Dept. of Geological Sciences)

    1993-03-01

    Integrated conodont and K-bentonite stratigraphy at City Brook and Watertown, New York reveals a pattern that is correlatable to coeval strata in the Midcontinent. The portion of the City Brook section examined consists of upper Lowville Limestone (upper Blackriveran) unconformably overlain by King Falls Limestone (lower Trentonian). The Lowville conodont fauna is a typical Blackriveran assemblage dominated by neurodontiform (hyaline) species of Curtognathus and Erismodus in association with Belodina compressa, Drepanoistodus suberectus, Panderodus and Plectodina aculeatus. The King Falls conodont fauna is dominated by Phragmodus undatus in association with Dapsilodus cf. D. mutatus, Oistodus cf. O. venustus, Panderodus, Periodon cf. P. grandis and Scandodus. Blackriveran faunal elements are also present in low abundance throughout the King Falls. The King Falls fauna is present and dominant in a packstone at the top of the upper Lowville below the unconformity. This occurrence supports the idea that these faunas are to some degree facies controlled. Four K-bentonite beds are present, 3 in the Lowville and 1 in the King Falls. A 6-cm thick K-bentonite in the King Falls has the approximate stratigraphic position of the Hounsfield K-bentonite. The Watertown section examined consists of upper Lowville Limestone overlain conformably or para conformable by the Watertown Limestone. The conodont fauna in both the Lowville and Watertown is identical to the Lowville fauna from City Brook, but lacks any Trentonian faunal elements. There is a 6-cm thick K-bentonite in the Lowville in virtually the same stratigraphic position as the lowest K-bentonite in the City Brook section. The stratigraphic positions and conodont faunal patterns observed in the City Brook and Watertown sections are similar to those in coeval sections in the Midcontinent.

  14. Temperature and frequency effects on the electric conductivity of X% Al2O3 powder extracted from Iraqi kaolin

    NASA Astrophysics Data System (ADS)

    Karim, A. S.

    2015-03-01

    Samples containing X% of Al2O3 (X =17.85, 28.05, 87.98 and 95.63) were prepared from Iraqi kaolin through calcinations process, by the method of evaporation. Electrical conductivity on as prepared and annealed samples at 1200°C were performed in the temperature range (30 - 115°C) and with applied frequencies from (10 KHz to 1MHz). The electrical conductivity increased with the increase of temperature for all investigated samples except 17.8%Al2O3. From the electrical conductivity curves, activation energies are obtained with the assumption of Arrhenius behavior over the entire temperature range from (30 to 110°C).

  15. Compound bioflocculant and polyaluminum chloride in kaolin-humic acid coagulation: factors influencing coagulation performance and floc characteristics.

    PubMed

    Li, Ruihua; Gao, Baoyu; Huang, Xin; Dong, Hongyu; Li, Xiaochen; Yue, Qinyan; Wang, Yan; Li, Qian

    2014-11-01

    The objective of this study was to investigate the influence of coagulant dosage and pH on coagulation performance and floc properties using polyaluminum chloride (PAC) and compound bioflocculant (CBF) dual-coagulant in kaolin-humic acid (HA) treatment. Results showed that as PAC dosage rose, comparatively better coagulation efficiencies and floc characteristics were achieved due to stronger charge neutralization and sweeping effect. Addition of CBF could enhance coagulation performance and floc properties, including size, strength and recoverability, except fractal dimension. Solution pH had a significant effect on coagulation efficiencies and flocs formation. Under acidic condition, flocs showed higher strength and recoverability but lower fractal dimension, where charge neutralization was the foremost mechanism. More compact flocs were generated under alkaline condition due to the sweeping effect of hydrolyzed Al species.

  16. Infrared Spectroscopic Study on Structural Change and Interfacial Interaction in Rubber Composites Filled with Silica-Kaolin Hybrid Fillers

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Guan, J.; Hu, H.; Gao, H.; Zhang, L.

    2016-07-01

    A series of natural rubber/styrene butadiene rubber/polybutadiene rubber composites was prepared with nanometer silica and micron kaolin by a dry modification process, mechanical compounding, and mold vulcanization. Fourier transform infrared spectroscopy and a scanning electron microscope were used to investigate the structural changes and interfacial interactions in composites. The results showed that the "seesaw" structure was formed particularly with the incorporation of silica particles in the preparation process, which would be beneficial to the dispersibility of fillers in the rubber matrix. The kaolinite platelets were generally arranged in directional alignment. Kaolinite with smaller particle size and low-defect structure was more stable in preparation, but kaolinite with larger particle size and high defect structure tended to change the crystal structure. The composite prepared in this research exhibited excellent mechanical and thermal properties.

  17. Removal of methylene blue by two zeolites prepared from naturally occurring Egyptian kaolin as cost effective technique

    NASA Astrophysics Data System (ADS)

    Jamil, Tarek S.; Abdel Ghafar, Hany H.; Ibrahim, Hanan S.; Abd El-Maksoud, Islam H.

    2011-10-01

    The optimum condition as well as adsorption behavior of two zeolite types prepared from Egyptian kaolin (namely, zeolite A and zeolite X) with methylene blue (MB) are demonstrated in this study. This will be a step to remove such dyes from textile as well as dying industries. MB removal was investigated using synthetic solutions at initial concentrations 15 mg/L of MB at constant temperature and pH (25 ± 0.1 °C and 7.5 ± 0.2) respectively. The removal efficiency was determined at different contact times and different zeolite doses. The optimum contact times for the removal of MB were 60 min and 75 min for zeolite X and zeolite A, respectively. 0.6 g was the optimum dose for removal of MB with both zeolite types. The batch method has been employed, using MB concentration in solution ranging from 2 to 25 mg /L. The percentage removal and distribution coefficients ( Kd) were determined for the adsorption system as a function of sorbate concentration. The isothermal models investigated in this study show that adsorption ratios of MB on both zeolites match to Langmuir and Freundlich equation adding to that every equation constant has been calculated. According to the equilibrium studies, adsorption of zeolite X in higher concentrations is much better than that of zeolite A. Dublin-Kaganer-Radushkevich (DKR) shows physisorption endothermic adsorption process for both zeolites and also linear correlation of Redlich-Peterson and Tekman isothermal models were proved. These results show that zeolites prepared from naturally abundant Egyptian kaolin hold great potential to remove dying materials such as MB from wastewater. This will encourage using such low cost technique in removal of dyes from industrial wastewater.

  18. Thermoluminescence response of calcic bentonite subjected to conditions of high nuclear waste underground storage.

    PubMed

    Dies, J; Miralles, L; Tarrasa, F; Pueyo, J J; de las Cuevas, C

    2002-01-01

    Bentonite is regarded as a backfilling material for underground storage facilities of highly radioactive nuclear waste built on granite formations. In these facilities, bentonite will be subjected to a gradient of temperature and dose rate, achieving a very high integrated dose and, therefore, changes in its structure and physical properties may take place. Two experiments to discriminate between the thermal and the irradiation effect were performed. In the first (named BIC 2A), samples were subjected to temperature while in the second (named BIC-2B) the combined effect of temperature and irradiation was studied. The experimental conditions were: a thermal gradient between 130 degrees C and 90 degrees C, a maximum dose rate of 3.5 kGy.h(-1) and a gradient of the integrated dose between 1.75 MGy and 10 MGy. Both experiments lasted a total of 124 days. An irradiation source of 60Co with an activity close to 300,000 Ci, and bentonite samples of 200 mm in length and 50 mm in diameter were used. After the experiment, the samples were ground and two fractions were obtained: a fine fraction (<2 microm) enriched in montmorillonite clay mineral and a coarse fraction (>80 microm). The results are described of thermoluminescence analyses on the two fractions obtained which showed that the coarse fraction can be 100 times more sensitive to radiation than the fine fraction. On the other hand, the heated and irradiated samples showed a thermoluminescence response around 50 times greater than the samples that were only heated. In addition to this, the temperature and dose rate conditions are relevant parameters in the generation and stabilisation of radiation induced defects. Finally, the response of samples heated and irradiated for two months was quite similar to that obtained on samples heated and irradiated for four months, indicating a saturation phenomenon.

  19. The influence of colloid formation in a granite groundwater bentonite porewater mixing zone on radionuclide speciation.

    PubMed

    Kunze, P; Seher, H; Hauser, W; Panak, P J; Geckeis, H; Fanghänel, Th; Schäfer, T

    2008-12-12

    In the context of deep geological storage of high level nuclear waste the repository will be designed as multiple barrier system including bentonite as buffer/backfill material and the host rock formation as geological barrier. The engineered barrier (bentonite) will be in contact with the host rock formation and consequently it can be expected that bentonite porewater will mix with formation groundwater. We simulate in this study the mixing of Grimsel groundwater (glacial melt water) with synthetic Febex porewater (assuming already saturated state) in a batch-type study and investigate the formation of colloids by laser-induced breakdown detection (LIBD) and SEM-EDX as well as the changes in radionuclide (U, Th, Eu) speciation via ultrafiltration or via time-resolved laser fluorescence spectroscopy (TRLFS) analysis in the case of Cm(III). Based on PHREEQC saturation index (SI) calculations a precipitation of calcite might be expected at low Febex porewater (FPW) content (<20%), fluorite precipitation at FPW contents <60% and gibbsite precipitation at FPW contents above 10%. The colloids generated in the mixing zone aggregate when the synthetic FPW content exceeds 10%. LIBD analysis of the time-dependent colloid generation/aggregation revealed a low concentration of colloids to be stable with an estimated plateau value around 100-200 ppt and an average colloid diameter around 30 nm after 140 days reaction time at FPW admixture >10%. SEM/EDX mostly identifies Al/Si containing colloidal phases and some sulfates could be found under certain admixture ratios. TRLFS studies show that the Cm speciation is strongly influenced by colloid formation in all solutions. In the Febex pore water/GGW mixing zone with high groundwater contents (>80%) colloids are newly formed and Cm is almost quantitatively associated with most likely polysilicilic acid colloids.

  20. Protective role of bentonite against aflatoxin B1- and ochratoxin A-induced immunotoxicity in broilers.

    PubMed

    Bhatti, Sheraz Ahmed; Khan, Muhammad Zargham; Saleemi, Muhammad Kashif; Saqib, Muhammad; Khan, Ahrar; Ul-Hassan, Zahoor

    2017-12-01

    The present study was designed to investigate any ameliorative effects of bentonite (BN) against immuno-pathological alterations induced by dietary aflatoxin B1 (AFB1) or ochratoxin A (OTA) in broiler chicks. In one experiment, AFB1 (0.1, 0.2 or 0.6 mg/kg feed) was fed alone and par alley with bentonite clay (3.7 or 7.5 g/kg feed) to the broilers. In the second experiment, the broilers were given feed contaminated with OTA (0.15, 0.3 or 1.0 mg/kg feed) alone and in combination with bentonite clay (3.7, 7.5, or 15 g/kg feed). Experimental feedings were continued for 42 days. At various time points along the feeding schedule, immune system organ histologic status, as well as host humoral and cellular immune responses, were evaluated in all groups. The dietary addition of AFB1 and OTA alone significantly reduced immune responses in the birds as assessed by histological changes in the bursa of Fabricius and thymus, antibody responses to SRBC, in-vivo lympho-proliferative responses to Phytohemagglutinin-P (PHA-P) and, phagocytic function in situ. The dietary addition of BN significantly ameliorated the immunotoxicity of 0.1 and 0.2 mg/kg dietary AFB1, however with a level of 0.6 mg AFB1/kg only partial amelioration was seen. The co-treatment of birds exposed to OTA with BN at all levels only partially alleviated deleterious effects on histology and immune responses. Taken together, the results here suggested to us that dietary addition of BN could help ameliorate AFB1-mediated immunotoxicities but could not afford such protection against OTA-induced immune damage.