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EARTH SCIENCES (471 journals)                  1 2 3 | Last

Showing 1 - 200 of 371 Journals sorted alphabetically
Acta Geochimica     Hybrid Journal   (Followers: 3)
Acta Geodaetica et Geophysica     Hybrid Journal   (Followers: 1)
Acta Geodaetica et Geophysica Hungarica     Full-text available via subscription   (Followers: 2)
Acta Geophysica     Open Access   (Followers: 6)
Acta Geotechnica     Hybrid Journal   (Followers: 6)
Acta Meteorologica Sinica     Hybrid Journal   (Followers: 3)
Advances in High Energy Physics     Open Access   (Followers: 20)
Advances In Physics     Hybrid Journal   (Followers: 18)
Aeolian Research     Hybrid Journal   (Followers: 5)
African Journal of Aquatic Science     Hybrid Journal   (Followers: 13)
Algological Studies     Full-text available via subscription   (Followers: 2)
Alpine Botany     Hybrid Journal   (Followers: 4)
AMBIO     Hybrid Journal   (Followers: 14)
Anales del Instituto de la Patagonia     Open Access   (Followers: 1)
Andean geology     Open Access   (Followers: 13)
Annales Henri Poincaré     Hybrid Journal   (Followers: 3)
Annales UMCS, Geographia, Geologia, Mineralogia et Petrographia     Open Access  
Annals of Geophysics     Open Access   (Followers: 13)
Annals of GIS     Hybrid Journal   (Followers: 21)
Annals of Glaciology     Full-text available via subscription   (Followers: 3)
Annual Review of Marine Science     Full-text available via subscription   (Followers: 11)
Anthropocene     Hybrid Journal   (Followers: 3)
Anthropocene Review     Hybrid Journal   (Followers: 6)
Applied Clay Science     Hybrid Journal   (Followers: 4)
Applied Geochemistry     Hybrid Journal   (Followers: 11)
Applied Geomatics     Hybrid Journal   (Followers: 3)
Applied Geophysics     Hybrid Journal   (Followers: 7)
Applied Ocean Research     Hybrid Journal   (Followers: 5)
Applied Petrochemical Research     Open Access   (Followers: 2)
Applied Remote Sensing Journal     Open Access   (Followers: 34)
Aquatic Conservation Marine and Freshwater Ecosystems     Hybrid Journal   (Followers: 34)
Arctic Science     Open Access   (Followers: 6)
Arctic, Antarctic, and Alpine Research     Full-text available via subscription   (Followers: 9)
Artificial Satellites : The Journal of Space Research Centre of Polish Academy of Sciences     Open Access   (Followers: 17)
Asia-Pacific Journal of Atmospheric Sciences     Hybrid Journal   (Followers: 20)
Asian Journal of Earth Sciences     Open Access   (Followers: 20)
Asian Review of Environmental and Earth Sciences     Open Access   (Followers: 1)
Atlantic Geology : Journal of the Atlantic Geoscience Society / Atlantic Geology : revue de la Société Géoscientifique de l'Atlantique     Full-text available via subscription   (Followers: 10)
Atmosphere-Ocean     Full-text available via subscription   (Followers: 12)
Atmospheric and Climate Sciences     Open Access   (Followers: 28)
Australian Journal of Earth Sciences: An International Geoscience Journal of the Geological Society of Australia     Hybrid Journal   (Followers: 11)
Boletim de Ciências Geodésicas     Open Access  
Boreas: An International Journal of Quaternary Research     Hybrid Journal   (Followers: 10)
Bragantia     Open Access   (Followers: 2)
Bulletin of Earthquake Engineering     Hybrid Journal   (Followers: 11)
Bulletin of Geosciences     Open Access   (Followers: 8)
Bulletin of the Lebedev Physics Institute     Hybrid Journal   (Followers: 1)
Bulletin of the Seismological Society of America     Full-text available via subscription   (Followers: 21)
Bulletin of Volcanology     Hybrid Journal   (Followers: 17)
Cadernos de Geociências     Open Access  
Canadian Journal of Plant Science     Full-text available via subscription   (Followers: 14)
Canadian Mineralogist     Full-text available via subscription   (Followers: 3)
Canadian Water Resources Journal     Hybrid Journal   (Followers: 21)
Carbonates and Evaporites     Hybrid Journal   (Followers: 3)
CATENA     Hybrid Journal   (Followers: 5)
Chemical Geology     Hybrid Journal   (Followers: 18)
Chemie der Erde - Geochemistry     Hybrid Journal   (Followers: 4)
Chinese Geographical Science     Hybrid Journal   (Followers: 5)
Chinese Journal of Oceanology and Limnology     Hybrid Journal   (Followers: 4)
Ciencia del suelo     Open Access   (Followers: 2)
Ciencias Espaciales     Open Access  
Climate and Development     Hybrid Journal   (Followers: 12)
Coastal Management     Hybrid Journal   (Followers: 25)
Cogent Geoscience     Open Access  
Comptes Rendus Geoscience     Full-text available via subscription   (Followers: 8)
Computational Geosciences     Hybrid Journal   (Followers: 12)
Computational Mathematics and Mathematical Physics     Hybrid Journal   (Followers: 1)
Computers and Geotechnics     Hybrid Journal   (Followers: 8)
Contemporary Trends in Geoscience     Open Access   (Followers: 3)
Continental Shelf Research     Hybrid Journal   (Followers: 9)
Contributions to Mineralogy and Petrology     Hybrid Journal   (Followers: 10)
Contributions to Plasma Physics     Hybrid Journal   (Followers: 3)
Coral Reefs     Hybrid Journal   (Followers: 16)
Cretaceous Research     Hybrid Journal   (Followers: 6)
Cybergeo : European Journal of Geography     Open Access   (Followers: 5)
Depositional Record     Open Access  
Developments in Geotectonics     Full-text available via subscription   (Followers: 3)
Developments in Quaternary Science     Full-text available via subscription   (Followers: 3)
Développement durable et territoires     Open Access   (Followers: 3)
Diatom Research     Hybrid Journal   (Followers: 2)
Doklady Physics     Hybrid Journal   (Followers: 1)
Dynamics of Atmospheres and Oceans     Hybrid Journal   (Followers: 11)
E&S Engineering and Science     Open Access  
E3S Web of Conferences     Open Access  
Earth and Planetary Science Letters     Hybrid Journal   (Followers: 108)
Earth and Space Science     Open Access   (Followers: 11)
Earth Interactions     Full-text available via subscription   (Followers: 11)
Earth Science Research     Open Access   (Followers: 5)
Earth Surface Dynamics (ESurf)     Open Access   (Followers: 4)
Earth Surface Processes and Landforms     Hybrid Journal   (Followers: 19)
Earth System Dynamics     Open Access   (Followers: 6)
Earth System Dynamics Discussions     Open Access   (Followers: 4)
Earth's Future     Open Access   (Followers: 1)
Earth, Planets and Space     Open Access   (Followers: 66)
Earthquake Engineering and Engineering Vibration     Hybrid Journal   (Followers: 7)
Earthquake Science     Hybrid Journal   (Followers: 10)
Earthquake Spectra     Full-text available via subscription   (Followers: 18)
Ecohydrology     Hybrid Journal   (Followers: 11)
Ecological Questions     Open Access   (Followers: 7)
Electromagnetics     Hybrid Journal   (Followers: 5)
Energy Efficiency     Hybrid Journal   (Followers: 11)
Energy Exploration & Exploitation     Hybrid Journal   (Followers: 4)
Environmental Earth Sciences     Hybrid Journal   (Followers: 24)
Environmental Geology     Hybrid Journal   (Followers: 20)
Environmental Geosciences     Full-text available via subscription   (Followers: 4)
Environmental Geotechnics     Hybrid Journal   (Followers: 5)
Erwerbs-Obstbau     Hybrid Journal  
Estuaries and Coasts     Hybrid Journal   (Followers: 18)
Estuarine, Coastal and Shelf Science     Hybrid Journal   (Followers: 33)
Estudios Geográficos     Open Access  
European Journal of Mineralogy     Full-text available via subscription   (Followers: 13)
European Journal of Remote Sensing     Open Access  
Exploration Geophysics     Hybrid Journal   (Followers: 4)
Facies     Hybrid Journal   (Followers: 9)
Fieldiana Life and Earth Sciences     Full-text available via subscription   (Followers: 1)
Física de la Tierra     Open Access  
Folia Musei rerum naturalium Bohemiae occidentalis. Geologica et Paleobiologica     Open Access  
Folia Quaternaria     Open Access  
Forestry Chronicle     Full-text available via subscription   (Followers: 10)
Frontiers in Earth Science     Open Access   (Followers: 5)
Frontiers in Geotechnical Engineering     Open Access   (Followers: 2)
Frontiers of Earth Science     Hybrid Journal   (Followers: 8)
Fundamental and Applied Limnology / Archiv für Hydrobiologie     Full-text available via subscription   (Followers: 4)
GEM - International Journal on Geomathematics     Hybrid Journal   (Followers: 1)
Geo-Marine Letters     Hybrid Journal   (Followers: 7)
Geoacta     Open Access   (Followers: 4)
Geobiology     Hybrid Journal   (Followers: 8)
Geocarto International     Hybrid Journal   (Followers: 22)
Geochemical Perspectives     Hybrid Journal  
Geochemistry : Exploration, Environment, Analysis     Hybrid Journal   (Followers: 7)
Geochemistry, Geophysics, Geosystems     Full-text available via subscription   (Followers: 26)
Geochimica et Cosmochimica Acta     Hybrid Journal   (Followers: 47)
Geochronometria     Hybrid Journal   (Followers: 3)
Geoderma Regional : The International Journal for Regional Soil Research     Full-text available via subscription   (Followers: 3)
Geodinamica Acta     Hybrid Journal   (Followers: 3)
Geodynamics & Tectonophysics     Open Access   (Followers: 1)
Geoenvironmental Disasters     Open Access   (Followers: 3)
Geofluids     Open Access   (Followers: 4)
Geoforum     Hybrid Journal   (Followers: 21)
Géographie physique et Quaternaire     Full-text available via subscription   (Followers: 1)
Geography and Natural Resources     Hybrid Journal   (Followers: 7)
Geoheritage     Hybrid Journal   (Followers: 1)
Geoinformatica Polonica : The Journal of Polish Academy of Arts and Sciences     Open Access  
Geoinformatics & Geostatistics     Hybrid Journal   (Followers: 8)
Geological Journal     Hybrid Journal   (Followers: 14)
Geology Today     Hybrid Journal   (Followers: 25)
Geology, Geophysics and Environment     Open Access   (Followers: 1)
Geomagnetism and Aeronomy     Hybrid Journal   (Followers: 3)
Geomatics, Natural Hazards and Risk     Hybrid Journal   (Followers: 9)
Geomechanics for Energy and the Environment     Full-text available via subscription   (Followers: 1)
GEOmedia     Open Access   (Followers: 1)
Geomorphology     Hybrid Journal   (Followers: 27)
Geophysical & Astrophysical Fluid Dynamics     Hybrid Journal   (Followers: 2)
Geophysical Journal International     Hybrid Journal   (Followers: 31)
Geophysical Prospecting     Hybrid Journal   (Followers: 7)
Geophysics     Full-text available via subscription   (Followers: 18)
GeoResJ     Hybrid Journal  
Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards     Hybrid Journal   (Followers: 8)
Geoscience Canada : Journal of the Geological Association of Canada / Geoscience Canada : journal de l'Association Géologique du Canada     Full-text available via subscription   (Followers: 3)
Geoscience Data Journal     Open Access   (Followers: 2)
Geoscience Frontiers     Open Access   (Followers: 9)
Geoscience Letters     Open Access   (Followers: 1)
Geoscience Records     Open Access  
Geosciences     Open Access   (Followers: 2)
Geosciences Journal     Hybrid Journal   (Followers: 10)
Geoscientific Instrumentation, Methods and Data Systems     Open Access   (Followers: 4)
Geoscientific Model Development     Open Access   (Followers: 2)
Geostandards and Geoanalytical Research     Hybrid Journal   (Followers: 2)
Geosystem Engineering     Hybrid Journal   (Followers: 1)
Geotectonic Research     Full-text available via subscription   (Followers: 4)
Geotectonics     Hybrid Journal   (Followers: 7)
GISAP : Earth and Space Sciences     Open Access   (Followers: 2)
Glass Physics and Chemistry     Hybrid Journal   (Followers: 4)
Global and Planetary Change     Hybrid Journal   (Followers: 17)
Global Biogeochemical Cycles     Full-text available via subscription   (Followers: 15)
Gondwana Research     Hybrid Journal   (Followers: 7)
GPS Solutions     Hybrid Journal   (Followers: 17)
Grassland Science     Hybrid Journal  
Ground Water     Hybrid Journal   (Followers: 31)
Ground Water Monitoring & Remediation     Hybrid Journal   (Followers: 18)
Groundwater for Sustainable Development     Full-text available via subscription   (Followers: 1)
Helgoland Marine Research     Open Access   (Followers: 3)
History of Geo- and Space Sciences     Open Access   (Followers: 4)
Hydrobiologia     Hybrid Journal   (Followers: 18)
Hydrogeology Journal     Hybrid Journal   (Followers: 17)
Hydrological Processes     Hybrid Journal   (Followers: 27)
Hydrology and Earth System Sciences     Open Access   (Followers: 28)
ICES Journal of Marine Science: Journal du Conseil     Hybrid Journal   (Followers: 54)
IEEE Journal of Oceanic Engineering     Hybrid Journal   (Followers: 11)
Indian Geotechnical Journal     Hybrid Journal   (Followers: 3)
Indonesian Journal on Geoscience     Open Access   (Followers: 2)
Interdisciplinary Environmental Review     Hybrid Journal   (Followers: 3)
International Geology Review     Hybrid Journal   (Followers: 14)
International Journal of Advanced Geosciences     Open Access  
International Journal of Advanced Remote Sensing and GIS     Open Access   (Followers: 34)
International Journal of Advancement in Earth and Enviromental Sciences     Open Access   (Followers: 3)
International Journal of Advancement in Remote Sensing, GIS, and Geography     Open Access   (Followers: 27)
International Journal of Applied Earth Observation and Geoinformation     Hybrid Journal   (Followers: 35)
International Journal of Coal Geology     Hybrid Journal   (Followers: 2)
International Journal of Disaster Risk Reduction     Hybrid Journal   (Followers: 15)

        1 2 3 | Last

Journal Cover Applied Clay Science
  [SJR: 0.826]   [H-I: 83]   [4 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0169-1317
   Published by Elsevier Homepage  [3031 journals]
  • Facile and controllable synthesis of iron nanoparticles directed by
           montmorillonite and polyvinylpyrrolidone
    • Authors: Mingde Fan; Lijie Zhang; Ruizhe Wang; Haozhe Guo; Shiyu Jia
      Pages: 1 - 8
      Abstract: Publication date: August 2017
      Source:Applied Clay Science, Volume 144
      Author(s): Mingde Fan, Lijie Zhang, Ruizhe Wang, Haozhe Guo, Shiyu Jia
      Porous host-hybridized metal nanoparticles are of great potential in sorption and catalysis related processes. The objective of this study was to synthesize property-controllable iron nanoparticles in montmorillonite and polyvinylpyrrolidone involved borohydride reduction system. In this system, mixed primary and secondary iron nanoparticles were readily generated. These resulting nanoparticles displayed an α-Fe@iron-oxide@polyvinylpyrrolidone core-double-shell architecture, in which the oxide shells protect the α-Fe cores from thorough oxidation in essential. In hybridization process, a polymer barrier was developed on the clay mineral surfaces. Due to the barrier-related steric hindrances and/or the alkaline pH-derived electrostatic repulsions, the clay mineral particles built a card-house flocculation structure, which can be converted to a semi-card-house form in dry products by suitable washing and drying treatments. The binding of the polymer to the iron and clay mineral surfaces would be mainly through hydrogen bonding. In general, the card-house pores and polymer layers made the hybridized iron nanoparticles much smaller and more dispersed than their bare counterparts. Specifically, by adjusting the molar mass and concentration of the polymer and the reductant amount, the hybridized iron nanoparticles could be further optimized. This synthesis route is carried out in situ under ambient temperature and atmosphere, greatly simplifying the process for iron nanoparticles preparation.
      Graphical abstract image

      PubDate: 2017-05-07T18:25:22Z
      DOI: 10.1016/j.clay.2017.04.022
      Issue No: Vol. 144 (2017)
  • Fluid flow and effective conductivity calculations on numerical images of
           bentonite microstructure
    • Authors: F. Bouchelaghem; R. Pusch
      Pages: 9 - 18
      Abstract: Publication date: August 2017
      Source:Applied Clay Science, Volume 144
      Author(s): F. Bouchelaghem, R. Pusch
      Hydraulic conductivities of compacted water-saturated bentonite were computed based on the real microstructure. The Homogenization of Periodic Media approach employed fully acknowledges the heterogeneous and multiscale microstructure of clay, as well as locally varying physical flow properties. Consequently, three levels of description were considered : the microscopic level of clay particles, the mesoscopic level of clay aggregates, mineral grains and inter-aggregate porosity, and the macroscopic level of the sample subjected to fluid pressure gradients in the laboratory. Starting from the local description of fluid flow, the expression of the effective hydraulic conductivity tensor was derived. The soft and dense gels and the open voids may form a connected flow path or remain occluded. The local problems were solved on the microstructure obtained from a digitalized micrograph by image analysis. The contribution to macroscopic flow by the soft and dense gels was investigated in various configurations, and comparisons were made with hydraulic conductivity data for MX-80 bentonite.

      PubDate: 2017-05-07T18:25:22Z
      DOI: 10.1016/j.clay.2017.04.023
      Issue No: Vol. 144 (2017)
  • X-ray crystallinity of different soil nanoclays in relation to phosphatase
    • Authors: Ranjan Paul; S.C. Datta; K.M. Manjaiah; Ranjan Bhattacharyya
      Pages: 19 - 25
      Abstract: Publication date: August 2017
      Source:Applied Clay Science, Volume 144
      Author(s): Ranjan Paul, S.C. Datta, K.M. Manjaiah, Ranjan Bhattacharyya
      Nanoclays, which are active component of soils, play a very important role for enzyme adsorption. To study the effect of nanoclays on enzyme adsorption, these were isolated from three genetically different Indian soils, i.e. black soil (Vertisols), red soil (Alfisols) and recent alluvial soil (Inceptisols). Then X-ray coherent particle sizes of different nanoclays (with and without amorphous aluminosilicates) before and after acid phosphatase adsorption were studied. Result showed that basal spacing of smectite present in nanoclays increased due to intercalation of enzyme molecules, whereas ‘d’ spacing in kaolinite did not change due to enzyme immobilization. Average particle size, calculated by Scherrer equation, increased due to enzyme immobilization for all nanoclays. In case of kaolinite, enzyme molecules acted as linkers and bind more than one particle together, which resulted in increased apparent particle size. Crystallite size of kaolinite was also more than that of mica or smectite. Increased average particle size after enzyme immobilization was confirmed from transmission electron microscopy (TEM) images.

      PubDate: 2017-05-12T19:02:06Z
      DOI: 10.1016/j.clay.2017.05.002
      Issue No: Vol. 144 (2017)
  • Water-based synthesis of TiO2/CeO2 composites supported on plasma-treated
           montmorillonite for parathion methyl degradation
    • Authors: Jiří Henych; Martin Kormunda; Martin Šťastný; Pavel Janoš; Petr Vomáčka; Jindřich Matoušek; Václav Štengl
      Pages: 26 - 35
      Abstract: Publication date: August 2017
      Source:Applied Clay Science, Volume 144
      Author(s): Jiří Henych, Martin Kormunda, Martin Šťastný, Pavel Janoš, Petr Vomáčka, Jindřich Matoušek, Václav Štengl
      The undemanding water-based synthesis was employed for the preparation of TiO2/CeO2 composites supported on Montmorillonite (MT). The prior plasma treatment of Montmorillonite led to significantly faster dispergation in water during the synthesis. The composites were used as reactive adsorbents against toxic organophosphorus pesticide parathion methyl. Efficient pillaring of the Montmorillonite layers by surface deposition of TiO2/CeO2 composites reflected in a substantially improved degradation activity towards parathion methyl in non-polar (heptane) and polar solvents (acetonitrile) investigated by HPLC/DAD. Moreover, the use of plasma treated Montmorillonite in the composites resulted in a higher degradation rate than with use of pristine MT. The formation of composites and their physicochemical properties were studied by XRD, XPS, FTIR, nitrogen physisorption, SEM and HRTEM/EDS mapping. Prior plasma treatment of the MT in a simple arrangement led to an easier formation of the composites and caused further improvement of the samples activity.
      Graphical abstract image

      PubDate: 2017-05-12T19:02:06Z
      DOI: 10.1016/j.clay.2017.05.001
      Issue No: Vol. 144 (2017)
  • Protein interference on aflatoxin B1 adsorption by smectites in corn
           fermentation solution
    • Authors: Sabrina Sharmeen Alam; Youjun Deng
      Pages: 36 - 44
      Abstract: Publication date: August 2017
      Source:Applied Clay Science, Volume 144
      Author(s): Sabrina Sharmeen Alam, Youjun Deng
      Corn is the main feedstock used for ethanol production in the United States. To reduce wastage and toxicity to human and animal, using aflatoxin contaminated corn in biofuel industry is thought to be rational. Yet up to three-fold of increment of the mycotoxins in the co-product have detrimental impact on animal health. It would be desirable to inactivate or to remove aflatoxins during fermentation of corn. Smectites were previously found to be highly efficient for aflatoxin B1 adsorption in ethanol and glucose solution, two major compounds in corn fermentation solution. The primary objective of the present study was to evaluate the aflatoxin B1 adsorption efficiency by smectites in real corn fermentation solution. The secondary objective was to identify any interfering compound that might hinder aflatoxin B1 adsorption. Aflatoxin B1 adsorption by smectites in fermentation solution was found to be low. A calcium smectite (3MS) had aflatoxin B1 adsorption capacity (Qmax) of 0.22molkg−1in the fermentation solution but 0.54molkg−1 in the aqueous solution. The Fourier transform infrared (FTIR) analyses indicated that some compounds from fermentation solution were adsorbed on the smectites and had irreversible bonding with the clay minerals. Those compounds competed with aflatoxin B1 for the adsorbing sites of smectites. The major infrared bands due to interfering compounds were at ~1653, 1532, 1451, and 1235cm−1. These bands appeared when smectites were added to either clean or aflatoxin B1 spiked fermentation solutions. Similar spectral bands were obtained after treating the smectites with zein, a major protein in corn. Thus, the major interfering compounds in fermentation solution were believed to be proteins. The XRD results proved the adsorption of the proteins in the interlayer of smectites. After heating at 300°C, smectites reacted with fermentation solution had d-spacing of at least 15Å, whereas the pure smectites collapsed to ~10Å. This reflected great interferences of the compounds, most possibly proteins on aflatoxin B1 adsorption by the smectites. However, despite of strong interferences, adsorption experiments suggested that smectites were still able to adsorb aflatoxin B1 to some extent. Presence of characteristic aflatoxin B1 bands at ~1595, 1383, 1362, 1304, 1272, and 1205cm−1 on smectite complexes treated in fermentation solution revealed the existence of the mycotoxins on the clay minerals. Strategies should be taken to enhance the selectivity of smectites for the aflatoxins in corn fermentation solution.

      PubDate: 2017-05-12T19:02:06Z
      DOI: 10.1016/j.clay.2017.04.024
      Issue No: Vol. 144 (2017)
  • One-dimensional compression behaviour of reconstituted clays with and
           without humic acid
    • Authors: Ling-Ling Zeng; Zhen-Shun Hong; Yu-Feng Gao
      Pages: 45 - 53
      Abstract: Publication date: August 2017
      Source:Applied Clay Science, Volume 144
      Author(s): Ling-Ling Zeng, Zhen-Shun Hong, Yu-Feng Gao
      It is often recognized that organic matter contained in natural clays and dredged clays is detriment to the engineering properties by increasing their compressibility. This study takes humic acid as an example to illustrate that organic matter may decrease the compressibility of reconstituted clays with a wide spectrum of predominant clay minerals: kaolinite, illite and smectite, based on experimental results from thirty types of one dimensional incremental load consolidation tests. It is found that the main factors of influencing the compression behaviour of reconstituted clays with humic acid are initial void ratio and void ratio at liquid limit. The difference in compression curves between reconstituted clays with and without humic acid can be attributed to humic acid effects on particle density and liquid limit of clays. The humic acid effect on the compressibility of smectite-dominant reconstituted clays is found to be much more sensitive than that for kaolinite- and illite-dominant reconstituted clays. A quantitative approach is also suggested to assess the compression behaviour of kaolinite- and illite-dominant reconstituted clays with humic acid using intrinsic compression concept.

      PubDate: 2017-05-12T19:02:06Z
      DOI: 10.1016/j.clay.2017.04.025
      Issue No: Vol. 144 (2017)
  • The effect of the negative charge density on switchable properties of
           pseudoisocyanine dye
    • Authors: Marián Matejdes; Daisuke Himeno; Yasutaka Suzuki; Jun Kawamata
      Pages: 54 - 59
      Abstract: Publication date: August 2017
      Source:Applied Clay Science, Volume 144
      Author(s): Marián Matejdes, Daisuke Himeno, Yasutaka Suzuki, Jun Kawamata
      The effect of Na-montmorillonite (Mt) and synthetic stevensite (Ste) on the switchable properties of intercalated cationic cyanine dye, 1,1′-diethyl-2,2′-cyanine (pseudoisocyanine, PIC) was investigated. The switching between non-aggregated and J-type aggregated states of PIC was performed by adding and removing of dimethyl sulfoxide (DMSO) from the interlayer space. It was found that the photophysical properties of PIC after addition of DMSO are significantly influenced by the negative charge density of layered silicate. Due to this effect the J-type aggregates were after swelling with DMSO formed only in the PIC/Mt hybrid films. Photophysical response and the stability of PIC species in PIC/Mt hybrid film was tested within 20cycles of adding and removing of DMSO from the interlayer space. During these cycles the stability of PIC species was proved to be sufficient, indicating that presented experimental approach is able to enhance the use and scope of materials consisting of J-type dye molecular assemblies.
      Graphical abstract image

      PubDate: 2017-05-17T19:32:21Z
      DOI: 10.1016/j.clay.2017.05.005
      Issue No: Vol. 144 (2017)
  • Exfoliation of layered double hydroxide solids into functional nanosheets
    • Authors: Ning Mao; Chun Hui Zhou; Dong Shen Tong; Wei Hua Yu; C.X. Cynthia Lin
      Pages: 60 - 78
      Abstract: Publication date: August 2017
      Source:Applied Clay Science, Volume 144
      Author(s): Ning Mao, Chun Hui Zhou, Dong Shen Tong, Wei Hua Yu, C.X. Cynthia Lin
      Exfoliated layered double hydroxide (LDH) nanosheets are a class of positively charged 2D nanoparticles. These LDH nanosheets can be used for a wide range of functional polymer nanocomposites and hierarchically structured materials. In this review we summarize and evaluate latest scientific advances in exfoliating LDH compounds, including exfoliation methods, mechanisms, properties and applications of exfoliated LDH nanosheets. Then identify the prevailing challenges and the directions of future work. In the first section of this review we dicuss the liquid exfoliation of LDH compounds, free of intercalation of organic species, in formamide, saturated aqueous L-asparagine or aqueous NaOH/urea solution with the help of ultrasonic treatment, mechanical shaking or stirring. We then examine the liquid exfoliation of LDH compounds with preceding organic species-intercalation. Such organic species include carboxylate, sulfonate, dodecyl sulfate, and amphoteric biomolecular amino acids. Next, we dicuss the exfoliation of LDH in monomer or polymer to form LDH/polymer nanocomposites. The polymer nanocomposites include LDH/polyethylene, LDH/polyethylene-graft-maleic anhydride, LDH/poly (vinyl alcohol), LDH/polystyrene, LDH/poly (ethylene terephthalate), LDH/poly (butylene adipate-co-terephtalate), LDH/poly ((butylene succinate)-co-adipate), LDH/poly caprolactone, LDH/poly (l-lactic) acid, LDH/acrylic polymer, LDH/polyacrylamide, LDH/poly(amide-imide) and LDH/poly (methyl methacrylate). The properties of these LDH/polymer nanocomposites are also discussed. In addition to polymer nanocomposites, recent studies indicate that the exfoliated LDH nanosheets can be used in electrorheological media, magnetic materials, low infrared emissivity materials, catalysts, and biosensors. The literature survey and analysis suggests that future work should place emphasis on the innovation of green and cost-effective exfoliation methods, and deepen understanding of the interfacial interactions between the LDH nanosheets and organic species/polymers, and the new assembly tactics of exfoliated LDH nanosheets with functional molecules or nanomaterials to expand applications.
      Graphical abstract image

      PubDate: 2017-05-17T19:32:21Z
      DOI: 10.1016/j.clay.2017.04.021
      Issue No: Vol. 144 (2017)
  • Kaolinite-alunite association in late Gothic white grounds from Slovakia:
           A local peculiarity in painting technology
    • Authors: David Hradil; Janka Hradilová; Petr Bezdička; Irena Matulková
      Pages: 79 - 87
      Abstract: Publication date: August 2017
      Source:Applied Clay Science, Volume 144
      Author(s): David Hradil, Janka Hradilová, Petr Bezdička, Irena Matulková
      In European Gothic paintings, the use of materials other than calcium carbonates (chalk) or calcium sulphates (gypsum) in painting preparations was rare. Therefore, alternatively used materials, such as, e.g., white clays, can be seen as peculiarities, which correspond to the local availability or artist's preference. In this study white chalk-based grounds from masterpieces attributed to the workshop of Master Paul from Levoča, Slovakia, were investigated. It was motivated by the assumption of restorers that Master Paul complemented the chalk ground by more malleable white clay to achieve a very fine modelling of his polychrome statues. The results were compared with other artworks, where the use of white clays in grounds was previously indicated, and with reference samples of kaolin from Central-European sources. It was found that detailed microanalysis of the white earths in paintings leads to distinguishing of regional provenances. While in Czech paintings, either from Gothic or Baroque periods, residual kaolins from West-Bohemian deposits were identified, in the late Gothic Slovak paintings white earths came from hydrothermal kaolin deposits situated, most probably, in Tokaj Mountains, Hungary. Here presented finding is probably the first ever evidence of natural alunite and hydrothermal kaolinite in painted artworks, where they were applied as white pigments.
      Graphical abstract image

      PubDate: 2017-05-17T19:32:21Z
      DOI: 10.1016/j.clay.2017.05.004
      Issue No: Vol. 144 (2017)
  • Textural-chemical changes and deformation conditions registered by
           phyllosilicates in a fault zone (Pic de Port Vieux thrust, Pyrenees)
    • Authors: Ahmed Abd Elmola; Delphine Charpentier; Martine Buatier; Pierre Lanari; Patrick Monié
      Pages: 88 - 103
      Abstract: Publication date: August 2017
      Source:Applied Clay Science, Volume 144
      Author(s): Ahmed Abd Elmola, Delphine Charpentier, Martine Buatier, Pierre Lanari, Patrick Monié
      Synkinematic phyllosilicates in fault zones can be used to deduce the deformation mechanisms and the conditions of fault activity, as their chemical composition, crystal structure and texture can record the different stages of deformation and fluid-rock interactions. The Pic de Port Vieux, a second-order thrust related to the major Gavarnie thrust in the southern central part of the Pyrenees Axial Zone, juxtaposes Triassic pelites of the hanging wall and Cretaceous limestones of the footwall. In order to investigate the mineralogical and geochemical changes and constrain the deformation conditions of thrusting, characterization of phyllosilicates was performed along a transect in the fault hanging wall pelites. The Triassic pelites are mainly composed of quartz, calcite, phyllosilicates (chlorite and K-white mica) and ±hematite. The core fault zone thickness is estimated to be about one meter of intensively foliated green pelites, whereas the damage zone is composed of several meters of red pelites. XRD data demonstrated that the difference in color is related to hematite which is only present in the damage zone. Phyllosilicates of the damage zone are mainly inherited/diagenetic K-white mica and chlorite. In the core zone, newly formed chlorite is abundant and preferentially located in veins. It is enriched in Fe compared to the chlorite of the red pelites. The well-defined foliation in the core zone is overlaid by preferentially oriented muscovite grains which have homogeneous compositions, with less Na and relatively more Fe than mica from the red pelites. Newly formed chlorite and muscovite in the core zone are synkinematic to the fault activity. They are both related to deformation processes and fluid rock interactions. Kübler index measurements and chlorite thermometry show that synkinematic phyllosilicates have registered a temperature of 270°C±23°C for the damage zone and 285°C±28°C for the core zone which are corresponding to lower-anchizone/epizone grade conditions. Numerical modelling with the geochemical modelling program PhreeqC was performed to determine the favorable conditions for the mineralogical change between red and green pelites. It suggests that the main critical parameter favoring hematite dissolution and chlorite precipitation in the core zone, is the redox conditions. According to the model, the chemical changes in the core zone occurred due to interactions with highly reductive fluids. In addition, the hematite dissolution maybe the source of iron for newly formed phyllosilicates in the core zone that are more iron rich compared to those from the red pelites.

      PubDate: 2017-05-17T19:32:21Z
      DOI: 10.1016/j.clay.2017.05.008
      Issue No: Vol. 144 (2017)
  • Effect of propanol and butanol and subsequent microwave irradiation on the
           structure of commercial vermiculites
    • Authors: C. Marcos; I. Rodriguez
      Pages: 104 - 114
      Abstract: Publication date: August 2017
      Source:Applied Clay Science, Volume 144
      Author(s): C. Marcos, I. Rodriguez
      As a continuation of our previous study, in this work, we investigated the effects of propanol and butanol treatments and subsequent irradiation with microwave on commercial vermiculites. No expansibility was observed after propanol or butanol treatments (k=1.0). Samples treated with propanol or butanol and subsequently irradiated with microwaves expanded in a similar manner as they did with methanol and ethanol. The results of X-ray diffraction (XRD), thermogravimetric analysis (TG and DTA), scanning electron microscopy (SEM) and infrared spectroscopy indicated structural changes as: 1) The appearance of extra interstratified phases during the transformation from 2- to 1-WLHS (Water Layer Hydration States). 2) The improvement of the crystallinity and order of the most phases, which are the same phases of the untreated vermiculites or even some more, due to migration of potassium.

      PubDate: 2017-05-17T19:32:21Z
      DOI: 10.1016/j.clay.2017.05.014
      Issue No: Vol. 144 (2017)
  • Mechanochemical synthesis of ultrafine ZnS/Zn-Al layered double hydroxide
           heterojunction and their photocatalytic activities in dye degradation
    • Authors: Zhao Li; Min Chen; Qiwu Zhang; Jun Qu; Ziqiang Ai; Yujie Li
      Pages: 115 - 120
      Abstract: Publication date: August 2017
      Source:Applied Clay Science, Volume 144
      Author(s): Zhao Li, Min Chen, Qiwu Zhang, Jun Qu, Ziqiang Ai, Yujie Li
      ZnS/Zn-Al layered double hydroxide (LDH) heterostructures were synthesized by a mechanochemical method and characterized by a set of analytical methods: X-ray diffraction, Raman spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy and scanning electron microscopy. The photocatalytic degradation activity for Rhodamine B (RHB) under ultraviolet light irradiation exhibited a large enhancement with the increasing ZnS content, with 94% RHB degraded in 180min by using 2ZnS/Zn-Al LDH heterostructured composite, but only 75% by the LDH sample without ZnS. A detailed discussion was performed to understand the reason for the enhanced photocatalytic activity based on the efficient separation of photoinduced electrons and holes. This work provides an effective way to fabricate a series of LDH-based and transition metal sulfide-containing heterostructured photocatalysts.

      PubDate: 2017-05-17T19:32:21Z
      DOI: 10.1016/j.clay.2017.05.015
      Issue No: Vol. 144 (2017)
  • Challenges in Life Cycle Assessment (LCA) of stabilised clay-based
           construction materials
    • Authors: Sara Marcelino-Sadaba; John Kinuthia; Jonathan Oti; Andres Seco Meneses
      Pages: 121 - 130
      Abstract: Publication date: August 2017
      Source:Applied Clay Science, Volume 144
      Author(s): Sara Marcelino-Sadaba, John Kinuthia, Jonathan Oti, Andres Seco Meneses
      The preference of clay-based materials for sustainable construction is well-established. The establishment of sustainability credentials of emergent construction materials is very subjective, and most available tools are not fully equipped to deal with individual material systems, such as composite cement- or lime-based cementitious systems, including clay-based blocks and bricks. The main problem emanates from the challenges of the audit of each aspect of the material processing, and especially the quantification of the most relevant inputs into the composite product. The variability in material ingredients, and lack of data for each aspect of the manufacturing processes involved creates major challenges. Incorporation of materials with long and complex recycling processes further exacerbate the challenge. These incorporations create problems in terms of accurate material trails and data for input in a robust Life Cycle Assessment (LCA) of individual products. This paper reports on a simplified approach towards full LCA of seven clay-based brick products developed in UK (4) and Spain (3), based on known material data and estimated energy inputs in the manufacturing processes. The UK-based bricks comprise of Lower Oxford Clay (LOC), stabilised using combinations of hydrated lime, Ground Granulated Blast-furnace Slag (GGBS) and Portland cement (PC). In order to test the robustness of the proposed approach, results on UK-based bricks are compared with a parallel LCA on clay-based product developed in Spain. Finally, the clay-based products are compared with a typical Portland cement-based concrete block and fired clay brick. In the LCA, boundary conditions include fixed transport, thus attempting to factor only the material ingredients, their known atmospheric emissions, and estimated energy inputs during processing. Results suggest that the most challenging aspect in the undertaking of LCA is the availability of reliable input data. Results also show that there are numerous parameters that can reliably and corroboratively facilitate the comparison of performance, besides carbon dioxide emissions.

      PubDate: 2017-05-17T19:32:21Z
      DOI: 10.1016/j.clay.2017.05.012
      Issue No: Vol. 144 (2017)
  • Development and characterization of porous membranes based on
           kaolin/chitosan composite
    • Authors: Sonia Bouzid Rekik; Sana Gassara; Jamel Bouaziz; André Deratani; Semia Baklouti
      Pages: 1 - 9
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Sonia Bouzid Rekik, Sana Gassara, Jamel Bouaziz, André Deratani, Semia Baklouti
      Chitosan/kaolin composite porous membranes were successfully prepared by solvent casting and evaporation process. The suspensions with different concentration of kaolin and chitosan showed a Newtonian behaviour. Strong interaction between chitosan and kaolin was revealed by FTIR and thermogravimetric analysis. The effect of kaolin content on the morphology and properties of the obtained membranes was studied. It was found by SEM observation that the kaolin particles were well dispersed in the chitosan matrix generating a porous microstructure. Incorporation of kaolin particles also improved the mechanical and thermal properties of the membranes and reduced drastically the water washout of chitosan in moderate acidic medium. Owing to their porous structure, the water permeability of the composite chitosan/kaolin membrane was significantly enhanced. The better formulation of the dope suspension in the range studied was 4% chitosan and 5% kaolin in acetic acid. These membranes made from naturally occurring materials might play an important role in advanced research in water treatment and environmental science.

      PubDate: 2017-03-16T09:26:35Z
      DOI: 10.1016/j.clay.2017.03.008
      Issue No: Vol. 143 (2017)
  • Clay mineralogy of altered tephra beds and facies correlation between the
           Permian-Triassic boundary stratigraphic sets, Guizhou, south China
    • Authors: Hanlie Hong; Qian Fang; Chaowen Wang; Gordon Jock Churchman; Lulu Zhao; Nina Gong; Ke Yin
      Pages: 10 - 21
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Hanlie Hong, Qian Fang, Chaowen Wang, Gordon Jock Churchman, Lulu Zhao, Nina Gong, Ke Yin
      The Permian-Triassic boundary (PTB) successions in south China contain numerous altered volcanic ash (tephra) beds (K-bentonites), which presents the opportunity to correlate the PTB position in both marine and non-marine sections, especially when no feasible biostratigraphic markers are available in the profiles. Clay mineralogical and geochemical studies of two altered ash beds in the Zhongzai (ZZ) and Tucheng (TC) sections, in Guizhou Province, south China, deposited in littoral and interactive marine-terrestrial environments, respectively, permit an investigation of the alteration of ash and correlation of ash beds between disparate facies. The results show that the two ZZ altered ashes consist of mainly R1 I/Sm and minor R0 I/Sm. Sample ZZ-1 has slightly more R1 I/Sm but less R0 I/Sm relative to sample ZZ-2. The TC ash samples contain mainly kaolinite and mixed-layer kaolinite/smectite (K/Sm). The poorly-crystallized kaolinite is present in pseudo-hexagonal plates, and the well-crystallized kaolinite occurs in book-like aggregates in veins or cavities. K/Sm minerals are derived from the transformation of smectite to kaolinite. Obviously, the TC ashes experienced terrestrial weathering and resedimentation prior to final burial and preservation, and local microenvironmental conditions control the formation of clay minerals. The ZZ ash samples have markedly higher 87Sr/86Sr values than those of the TC samples. The notable difference in 87Sr/86Sr value of ash beds between the sections is attributed to variations in RbSr partitioning during the chemical weathering process in different environments. The ZZ ash samples have notably higher 143Nd/144Nd ratios than those of the TC samples, suggesting that the ZZ ashes are likely derived from eruptions involving continental crust and the TC ashes originate from eruptions involving new continental island arcs, in agreement with the REE distributions and the Ti vs. Zr, TiO2 vs. Al2O3, and Zr/TiO2 vs. Nb/Y discrimination plots. The occurrence of tephras from such markedly different volcanic source materials different in PTB stratigraphic sets previously believed to be synchronous, Guizhou, south China, suggests that correlation between disparate facies by an ash marker requires geochemical fingerprinting of the materials to confirm correlations or otherwise.

      PubDate: 2017-03-16T09:26:35Z
      DOI: 10.1016/j.clay.2017.03.014
      Issue No: Vol. 143 (2017)
  • Mechanochemically activated saponite as materials for Cu2+ and Ni2+
           removal from aqueous solutions
    • Authors: L. Petra; P. Billik; Z. Melichová; P. Komadel
      Pages: 22 - 28
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): L. Petra, P. Billik, Z. Melichová, P. Komadel
      Saponites are nanosized layered aluminosilicates from the smectite group of clay minerals, which can be further functionalized to prepare low-cost materials for water purification. Mechanochemical activation of saponite was achieved by high-energy grinding in a planetary ball mill. X-ray diffraction, infrared spectroscopy, scanning electron microscopy, thermal analysis, and the determination of cation-exchange capacity and specific surface area were used to characterize parent and functionalized solids. Prepared adsorbents were used for Cu2+ and Ni2+ removal from aqueous solutions. Compared to the untreated sample, activated saponites had significantly increased capacity to take away metal cations. The equilibrium data showed the maximum of Cu2+ and Ni2+ uptake of 295 and 129mg/g, respectively. In comparison with the pristine material, the measured values increased by 764% and 170% for Cu2+ and Ni2+ respectively. The formation of reactive Mg(OH)2 as the saponite decomposition product was also discussed.
      Graphical abstract image

      PubDate: 2017-03-16T09:26:35Z
      DOI: 10.1016/j.clay.2017.03.012
      Issue No: Vol. 143 (2017)
  • Properties and application of Nigerian bentonite clay deposits for
           drilling mud formulation: Recent advances and future prospects
    • Authors: Richard O. Afolabi; Oyinkepreye D. Orodu; Vincent E. Efeovbokhan
      Pages: 39 - 49
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Richard O. Afolabi, Oyinkepreye D. Orodu, Vincent E. Efeovbokhan
      The vast deposits of Nigerian bentonite clay have many significant uses in different aspects of industrial fields of which the oil and gas industry is a potential consumer of this clay mineral. In this review article, the key mineralogical characteristics and rheological properties of these clay deposits in various locations and their related application for drilling mud formulation were comprehensively reviewed. Various research efforts on these bentonite clay deposits over the past couple of years were summarized with some critical comments and analysis. Attention was given to the clay reserve estimates, mineralogy of the clay deposits, chemical modification of the clays, rheological properties of drilling mud formulated from these clays and its suitability for drilling operations. Moreover, future prospects and key problems to be solved regarding the use of Nigerian bentonite deposits for drilling mud formulation were discussed. This review shed new light on both fundamental and practical studies that are concentrated on the use of Nigerian bentonite for drilling mud formulation.

      PubDate: 2017-03-20T21:52:04Z
      DOI: 10.1016/j.clay.2017.03.009
      Issue No: Vol. 143 (2017)
  • Physical and chemical characterization and recovery of potash fertilizer
           from glauconitic clay for agricultural application
    • Authors: Saurabh Shekhar; D. Mishra; A. Agrawal; K. K Sahu
      Pages: 50 - 56
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Saurabh Shekhar, D. Mishra, A. Agrawal, K. K Sahu
      Glauconite is a natural occurring iron-rich, heterogeneous, phyllosilicate rock containing around 4–8% of potash (K2O) locked in the alumino-silicate matrix. An attempt has been made to develop a complete flow-sheet for the recovery of potash from a typical glauconite sample containing 3.93% K2O, 10.75% Fe2O3, 4.41% Al2O3 and 70.35% SiO2. Initially, the detail physico-chemical characterization and beneficiation study was performed to enrich the potash content from 3.93% to 5.52% by removing free silica. The enriched fraction of glauconite was further processed to recover locked potash through chemical treatment. Potassium recovery by direct acid leaching was found to be very poor and also resulted in simultaneous dissolution of iron. Therefore, a combined sulfation roasting–water leaching process was developed to break the matrix and selectively recover potash. Various parameters such as sulphuric acid concentration, roasting and leaching temperature were optimized to achieve >98% potash dissolution. The potassium from the leach solution was recovered as sulfate of potash (SOP) suitable for fertilizer application.
      Graphical abstract image

      PubDate: 2017-03-20T21:52:04Z
      DOI: 10.1016/j.clay.2017.03.016
      Issue No: Vol. 143 (2017)
  • Nanohybrid sensor based on carboxyl functionalized graphene dispersed
           palygorskite for voltammetric determination of niclosamide
    • Authors: Zhouxiang Zhang; Yuanyuan Yao; Jingkun Xu; Yangping Wen; Jie Zhang; Wanchuan Ding
      Pages: 57 - 66
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Zhouxiang Zhang, Yuanyuan Yao, Jingkun Xu, Yangping Wen, Jie Zhang, Wanchuan Ding
      The stably dispersible palygorskite (Pal) nanorods onto carboxyl functionalized graphene (Gr-COOH) nanosheets were successfully employed for the facile fabrication of a novel nanohybrid sensing platform and the voltammetric determination of niclosamide (NA) in tablet and paddy water samples. A water-processable Gr-COOH can improve the dispersion and stability in water of Pal. The structure and properties of the formed Pal-Gr-COOH nanohybrid were characterized. The electrochemical behavior of NA, analytical conditions and the sensing performance of the prepared sensor were investigated. The sensor displayed the enhanced synergistically electrocatalytic ability toward NA in a linear range from 0.02–0.99μM with low limit of detection (4.6nM), good sensitivity, high reproducibility and satisfactory practicability, suggesting Pal-Gr-COOH nanohybrid will provide a promising platform for sensing application and facile preparation and potential application of other nanoclay mineral nanocomposites.
      Graphical abstract image

      PubDate: 2017-03-20T21:52:04Z
      DOI: 10.1016/j.clay.2017.03.013
      Issue No: Vol. 143 (2017)
  • Tailored montmorillonite nanoparticles and their behaviour in the alkaline
           cement environment
    • Authors: Juliana Calabria-Holley; Styliani Papatzani; Benjamin Naden; John Mitchels; Kevin Paine
      Pages: 67 - 75
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Juliana Calabria-Holley, Styliani Papatzani, Benjamin Naden, John Mitchels, Kevin Paine
      This is the first time an analytical protocol is proposed to investigate and live-monitor the behaviour of montmorillonite nanoparticles, of different natures, in alkaline cement environment (pH of 12–13). In this study inorganic and organomodified montmorillonite nanoparticles were characterised via TEM, XRD, SEM-EDX and TGA. The inorganic montmorillonite used consisted of a purified montmorillonite commercially available as HPS-clay, and an organomodified montmorillonite, namely XDB-organoclay, consisted of purified montmorillonite modified with Noramonium MB2HT salt. Both montmorillonite nanoparticles were tailored to increase their compatibility with the hydrating cement environment. This gave rise to three different slurries: (i) reference-slurry, (ii) inorganic-slurry, and (iii) organic-slurry. The slurries were characterised and investigated through UV/vis, to measure suspension quality in terms of physical stability and rheological properties, and by AFM and FTIR to determine the chemical stability. The results indicated that the organic-slurry can offer a good stability, preventing aggregation of the clay particles at the targeted pH (13). The inorganic-slurry showed a reduction in surface charge and increased double layer repulsion. At pH13 it was possible to obtain dispersion of the reference slurry although it underwent gelation and became viscous. The research findings informed that the inorganic slurry favours miscibility of the montmorillonite nanoparticles with cement particles and offers additional nucleation sites for CSH. Therefore it can be considered an alternative to organomodified montmorillonite as an addition in cement based materials.
      Graphical abstract image

      PubDate: 2017-03-20T21:52:04Z
      DOI: 10.1016/j.clay.2017.03.005
      Issue No: Vol. 143 (2017)
  • Effect of dietary palygorskite on performance of lactating ewes
    • Authors: B. Kotsampasi; V.A. Bampidis; C. Christodoulou; N. Theophilou; V. Christodoulou
      Pages: 76 - 79
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): B. Kotsampasi, V.A. Bampidis, C. Christodoulou, N. Theophilou, V. Christodoulou
      Twenty eight lactating Chios ewes were used in an experiment to determine effects of dietary activated micronized palygorskite (Pal; Sanfed® Ultra, Geohellas SA, Athens, Greece) supplementation on productivity and milk composition. In the experiment, which started on day 43 postpartum, ewes were allocated after equal distribution relative to milk yield and lactation number (i.e., 2 or 3), into 4 treatment groups being Pal0, Pal2.5, Pal5.0 and Pal7.5 of 7 ewes each and accommodated in individual pens. For a period of 60days (i.e., days 43–102 postpartum), ewes were fed one of four isonitrogenous (crude protein 175g/kg, dry matter (DM) basis) and isoenergetic (net energy for lactation (NEl) 7.69MJ/kg DM) concentrates (1.35kg DM/ewe/day) and alfalfa hay (1.02kg DM/ewe/day). The concentrate for treatment Pal0 (Control) had no Pal, while that for treatments Pal2.5, Pal5.0 and Pal7.5 contained 2.5, 5.0 and 7.5g/kg of Pal (as mixed basis), respectively. All ewes remained healthy until the end of the experiment without visually altered behavior. In the 60day experimental period, milk fat, crude protein and NEl contents were highest with the Pal5.0 treatment (P<0.01, P=0.01 and P<0.01, respectively). In contrast, milk lactose content was lowest (P<0.01) with the Pal2.5 treatment. With increased Pal feeding, milk fat and NEl yields were highest with the Pal5.0 treatment (P<0.01 and P=0.03, respectively), but milk yield and yields of other components, as well as milk somatic cell counts and colony forming units were not affected. Dietary Pal supplementation, at levels up to 5.0g/kg, in isonitrogenous and iso-NEl diets fed to lactating ewes increased milk fat and NEl yields and improved milk quality, increasing fat, crude protein and NEl contents, while, at higher level (7.5g/kg), dietary Pal supplementation did not affect milk yield and composition, with optimal Pal feeding levels identified between 3.4 and 4.0g/kg of concentrate.

      PubDate: 2017-03-20T21:52:04Z
      DOI: 10.1016/j.clay.2017.03.020
      Issue No: Vol. 143 (2017)
  • Gold nanoparticle-decorated halloysite nanotubes – Selective catalysts
           for benzyl alcohol oxidation
    • Authors: Anish Philip; Jenna Lihavainen; Markku Keinänen; Tuula T. Pakkanen
      Pages: 80 - 88
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Anish Philip, Jenna Lihavainen, Markku Keinänen, Tuula T. Pakkanen
      Preparation of gold nanoparticle-decorated halloysite nanotubes (Au-Hal) by a deposition method and evaluation of their catalytic activity in an oxidation of benzyl alcohol are reported. An electrostatic attraction between positively charged polyethylenimine (PEI)-capped gold nanoparticles and the negatively charged external surfaces of halloysite nanotubes (Hal nanotubes) was the key factor in fabrication of Au-Hal nanotubes. Au-Hal catalysts showed good conversions and surprisingly high benzaldehyde selectivities (above 90%) in the benzyl alcohol oxidation. Influence of the amount of PEI used as a capping agent, the gold content and calcination of Au-Hal catalysts on the conversion and selectivity was investigated. A notable increase in the benzaldehyde selectivity at higher PEI contents and a significant drop in the benzaldehyde selectivity on calcination clearly indicate the central role of PEI in the selective formation of benzaldehyde. The high benzaldehyde selectivity of uncalcined catalysts are probably due to PEI donor molecules coordinating to certain surface sites on Au nanoparticles and thus blocking the catalytic sites required for further oxidation of benzaldehyde to benzoic acid. The high combined selectivity of benzoic acid and benzyl benzoate obtained with the calcined catalysts indicates that naked gold nanoparticles have the catalytic sites available for the benzoic acid formation.
      Graphical abstract image

      PubDate: 2017-03-27T15:51:32Z
      DOI: 10.1016/j.clay.2017.03.015
      Issue No: Vol. 143 (2017)
  • Understanding the clay-PEG (and hydrophobic derivatives) interactions and
           their effect on clay hydration and dispersion: A comparative study
    • Authors: Santiago Villabona-Estupiñán; Jorge de Almeida Rodrigues; Regina Sandra Veiga Nascimento
      Pages: 89 - 100
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Santiago Villabona-Estupiñán, Jorge de Almeida Rodrigues, Regina Sandra Veiga Nascimento
      In oil and gas well drilling, the effective minimization of clay-water interactions is an essential function that water-based drilling fluids must meet in order to maintain the integrity of the shale formations as well as suitable rheological properties. In this work, the protective effect of poly(ethylene glycol) 2000 (PEG2000) and two hydrophobic derivatives on the hydration and dispersion of reactive clay materials was investigated. Thus, conventional inhibition tests were combined with adsorption measurements and analyses by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and thermogravimetry (TGA) in an attempt to establish structure-performance relationships. It was found that both PEG2000 and its hydrophobic derivatives can strongly adsorb, in equimolar amounts, on mineral clay following a Langmuir type behavior, in which bilayers are formed in the clay interlayer region at surface saturation. It was found that the PEG backbone rules the adsorption process, while the hydrocarbon tails of the hydrophobically modified products do not play a decisive role. However, it was verified that hydrocarbon tails play a central role in the mechanism of inhibition of clay particles hydration. Bentonite inhibition test revealed that the incorporation of two hydrocarbon tails at the PEG2000 chain ends duplicate the performance of oligomer, regarding the product with just one tail.
      Graphical abstract image

      PubDate: 2017-03-27T15:51:32Z
      DOI: 10.1016/j.clay.2017.03.021
      Issue No: Vol. 143 (2017)
  • Preparation of aggregates based on waste foundry sand: Reuse of calcined
    • Authors: Ruofei Xiang; Yuanbing Li; Keke Huang; Shujing Li
      Pages: 101 - 106
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Ruofei Xiang, Yuanbing Li, Keke Huang, Shujing Li
      Used calcined clay, waste foundry sand (WFS), was adopted to prepare aggregates with the addition of clay, alumina powder, and bran. Bulk density, porosity, cold crushing strength, phase compositions, microstructure, and thermal conductivity were investigated. Thermal calculation was adopted to assess the generation of the liquid phase during sintering. In the specimens composed of WFS and clay, the increase in clay concentration led to a decrease in cold crushing strength even if the variation in bulk density was not obvious. When WFS, clay, alumina powder, and bran were adopted in manufacturing aggregates, the addition of bran influenced the phase composition of the samples because of the formation of pores. With an increased WFS content, the cold crushing strength improved due to an increase in the amount of liquid phase during the sintering process. The thermal conductivities obtained from the samples by mechanical pressing were ideal and showed the influence of heat shielding effect from zircon.

      PubDate: 2017-03-27T15:51:32Z
      DOI: 10.1016/j.clay.2017.03.027
      Issue No: Vol. 143 (2017)
  • DFT study of the intercalation of layered double hydroxides and layered
           hydroxide salts with dodecylsulfate and dodecylbenzene sulfonate:
           Exfoliation and hydration properties
    • Authors: Sérgio R. Tavares; Fernando Wypych; Alexandre A. Leitão
      Pages: 107 - 114
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Sérgio R. Tavares, Fernando Wypych, Alexandre A. Leitão
      DFT calculations were performed for the simulation of the intercalations of Zn2Al-layered double hydroxide and Zn-layered hydroxide salts with dodecylsulfate and dodecylbenzene sulfonate. A structural and energetic analyses of the exfoliation processes were computed and compared with Perdew-Burke-Ernzerhof exchange-correlation (PBE) and Van der Waals-aware density (vdW-DF) functionals and with the semi-empirical approach DFT-D2. It could be concluded that the layers cell parameters were not affected by the applied approach. On the other hand, the basal spacing and the exfoliation energies presented variations with respect to the simulation. The influence of water molecules hydrating the polar heads of the anions intercalated in the interlayer region was also investigated. Furthermore, the interactions between the anions and the positive layers and the influence of hydration waters could be resolved by means of charge density difference plots and Bader charges. Projected density of states (PDOS) showed the possible acid and basic sites of these compounds for both dehydrated and hydrated structures.
      Graphical abstract image

      PubDate: 2017-03-27T15:51:32Z
      DOI: 10.1016/j.clay.2017.03.018
      Issue No: Vol. 143 (2017)
  • Mixed matrix hollow fibre membrane comprising polyetherimide and modified
           montmorillonite with improved filler dispersion and CO2/CH4 separation
    • Authors: Asif Jamil; Oh Pei Ching; Azmi M. Shariff
      Pages: 115 - 124
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Asif Jamil, Oh Pei Ching, Azmi M. Shariff
      Mixed matrix membrane with nano-filler embedded in polymer matrix, is receiving overwhelming attention for gas separation applications due to its attractiveness in providing an economic solution to enhance permselectivity. However, achieving uniform dispersion of nano-filler in host polymer remains a key challenge in developing membrane. In this work, mixed matrix hollow fibre membranes comprising polyetherimide (PEI) with various modified montmorillonite (f-Mt) loading, was developed via phase inversion method for CO2/CH4 separation. The Mt was modified with aminolauric acid to impart organophilicity to enhance compatibility towards organic polymer matrix. The synthesized hollow fibers were characterized using field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), and permeation test. The permeation tests were carried out with pure gases at ambient temperature with varying pressures of 2 and 4 bars. An increasing trend in ideal selectivity was observed up to 2wt% f-Mt loading. Thereafter, opposite trend was observed with increasing filler loading due to exfoliated layers that created more tortuous path for the penetrating gas molecules. The maximum ideal selectivity was found with 2wt% f-Mt loading at 2bar, which showed 39% increment as compared to neat PEI hollow fibre membrane. This increment in gas selectivity was related to the dispersion state and aspect ratio of f-Mt. Various phenomenological models were employed to calculate the aforementioned properties. Adopting to Cussler and Yang-Cussler models, the aspect ratio of the f-Mt was found to be 35 and 50, respectively with 3–4 particles per tactoid.

      PubDate: 2017-03-27T15:51:32Z
      DOI: 10.1016/j.clay.2017.03.017
      Issue No: Vol. 143 (2017)
  • Fabrication, microstructural and mechanical characterization of Luffa
           Cylindrical Fibre - Reinforced geopolymer composite
    • Authors: Mazen Alshaaer; Saida Abu Mallouh; Juma'a Al-Kafawein; Yasair Al-Faiyz; Tarek Fahmy; Abderrazek Kallel; Fernando Rocha
      Pages: 125 - 133
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Mazen Alshaaer, Saida Abu Mallouh, Juma'a Al-Kafawein, Yasair Al-Faiyz, Tarek Fahmy, Abderrazek Kallel, Fernando Rocha
      This study reports on the preparation, microstructure, density and mechanical properties of new geopolymer composites (LG-composite) that are unidirectionally and randomly reinforced with 10vol% natural Luffa Cylindical fibres (LCF). The geopolymer matrix was synthesized from metakaolin activated with sodium silicate and sodium hydroxide solutions. A greater amount of geopolymer gel was formed after introducing the LCF into the geopolymer matrix. As a result of the strong alkali setting reactions (geopolymerization), the hemicelluloses and lignin present in the LCF were extracted, leaving a rough LCF surface. In this way the hydrophobicity of the rough LCF increased and helped strengthen the bonding between fibre and geopolymer matrix. Two main morphological types of crystalline objects were observed in the LG-composite due to the incorporation of the extracted constituents of LCF: fibre-like crystals, or whiskers, and fine crystals of cubic shape. These crystals assist in crack healing while increasing the tensile strength and toughness of the composite. In terms of mechanical properties, it is found that by introducing LCF as reinforcement, the compressive and flexural strengths of the end geopolymeric products respectively increase from 13 MP and 3.4MPa up to 31MPa and 14.2MPa. The LCF-reinforced geopolymer composite exhibited ductile-like failure with a strain hardening Modulus of 72MPa, unlike the brittle matrix. In addition, the bulk density decreases from 1.5g/cm3 to 1.38g/cm3. A preliminary aging study has demonstrated that the LG-composite shows no significant deterioration in mechanical performance over a duration of 20months.

      PubDate: 2017-03-27T15:51:32Z
      DOI: 10.1016/j.clay.2017.03.030
      Issue No: Vol. 143 (2017)
  • X-ray coupled Laser Desorption Ionization assessment of layered double
           hydroxides for nitrate adsorption based on ion size, affinity and
           compromised layer height
    • Authors: Jaybalan Tamahrajah; Irina Goncharova; Ivan Pytskii; Andrey A. Shiryaev; Alexey A. Averin; Michail R. Kiselev; Alevtina Shaphigulina; Wan Jefrey Basirun; Alexey K. Buryak; Galina A. Pethukova; Frank Roessner
      Pages: 134 - 141
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Jaybalan Tamahrajah, Irina Goncharova, Ivan Pytskii, Andrey A. Shiryaev, Alexey A. Averin, Michail R. Kiselev, Alevtina Shaphigulina, Wan Jefrey Basirun, Alexey K. Buryak, Galina A. Pethukova, Frank Roessner
      The adsorption of nitrates with NO3(aq) solutions ranging from 20mg/L to 400mg/L with Layered-Double-Hydroxides (LDH) PURAL 70 (Mg70) and an Erbium containing LDH (Er40) were investigated. The X-ray Diffraction measurements (XRD) are accompanied by complemented Matrix Assisted Laser Desorption Ionization-Time of Flight (MALDI-TOF) measurements for prove of NO3- containing LDH. The shift in the XRD reflection angle for both Mg70 and Er40 corresponds to MALDI-TOF Data for presence of nitrate for all LDH except for Er40MW, as its nitrate adsorption capacity is the lowest. Both methods show the adsorption of nitrates for microwaved LDH and further calcined LDH, proving the memory effect. UV–vis spectroscopy was used to determine the nitrate concentration. The study shows substantial amount of nitrate adsorption for all LDH. Adsorption ranges from 2 to 5mg-NO3(aq)/g-LDH for initial NO3(aq) concentration from 20mg/L to 400mg/L. Leaching of element from the LDH structure is done by ICP-MS measurements to guarantee no further pollution of environmental waters with mentioned elements. Leaching for Mg ranges from170 to 1600mg/m3 and Al, Er and Fe leaching is less than 10mg/m3.
      Graphical abstract image

      PubDate: 2017-03-27T15:51:32Z
      DOI: 10.1016/j.clay.2017.03.022
      Issue No: Vol. 143 (2017)
  • A comparative study of the amaranth azo dye adsorption/desorption from
           aqueous solutions by layered double hydroxides
    • Authors: K. Abdellaoui; I. Pavlovic; M. Bouhent; A. Benhamou; C. Barriga
      Pages: 142 - 150
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): K. Abdellaoui, I. Pavlovic, M. Bouhent, A. Benhamou, C. Barriga
      Magnesium aluminum layered double hydroxides (LDH) were synthesized by the co-precipitation method with nitrate and carbonate as interlayer anion (MgAlNO3 and MgAlCO3) followed by the calcination of a carbonate containing LDH sample to obtain the mixed oxide MgAl500. The resulting materials were characterized by several physicochemical techniques. Calcined and uncalcined LDHs were used as adsorbents to remove the amaranth azo dye in an aqueous solution. Adsorption results indicated that MgAl500 had a greater adsorption capacity (1.6mmol·g−1) than non-calcined LDHs (0.8 and 0.2mmol·g−1for MgAlNO3 and MgAlCO3, respectively). Isotherms showed that the adsorption of the dye was consistent with the Langmuir model. The kinetic experiments of dye adsorption showed that the system reached the adsorption equilibrium in 3h for the three adsorbents. The kinetic data fitted well with the pseudo-second order model. Powder X ray diffraction patterns of the adsorption products suggest that adsorbed amaranth anion was intercalated in the MgAlNO3 interlayers by anion exchange and in the MgAl500 by the rehydration and reconstruction process, according to the value of the basal space d003 =17.7Å. Whereas in the case of MgAlCO3, .it was probably adsorbed on the external particle surface. The influence of common inorganic anions present in the solution was also studied and a decrease in the dye removal was observed in the following order HPO4 2−>CO3 2 – >SO4 2 − >Cl-. The dye desorption was tested with carbonate and phosphate solution and it was partial in all cases. The recyclability of the used adsorbents was performed by calcinations, and the percentage of removal decreases after the first cycle for MgAlNO3 and MgAl500. Dye removal improved after the first cycle then decreased after the second cycle for MgAlCO3.

      PubDate: 2017-04-03T16:26:09Z
      DOI: 10.1016/j.clay.2017.03.019
      Issue No: Vol. 143 (2017)
  • Electrochemically synthesized cobalt redox active layered double
           hydroxides for supercapacitors development
    • Authors: Ylea Vlamidis; Erika Scavetta; Marco Giorgetti; Nicola Sangiorgi; Domenica Tonelli
      Pages: 151 - 158
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Ylea Vlamidis, Erika Scavetta, Marco Giorgetti, Nicola Sangiorgi, Domenica Tonelli
      This paper describes the electrosynthesis and characterization in alkaline solutions of two layered double hydroxides (LDHs) containing Co as divalent cation and Al or Fe as trivalent one on Pt supports. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) experiments demonstrated a capacitive behaviour. LDHs containing Al3+ or Fe3+ displayed different responses, highlighting a key role of the trivalent metal. High specific capacitances calculated from charge-discharge experiments at a current density of 1Ag−1, were displayed by the two materials and resulted 854 and 869Fg−1 for the Al or Fe containing LDH, respectively. The long-term cycling capability was also investigated giving satisfactory results. The presence of Fe improves the performance of the LDH as pseudocapacitor, especially to achieve better performances in terms of energy and power densities. In view of the development of low cost supercapacitors preliminary tests aimed to deposit Co based LDHs on a large area graphite substrate were also successfully carried out.

      PubDate: 2017-04-11T17:14:07Z
      DOI: 10.1016/j.clay.2017.03.031
      Issue No: Vol. 143 (2017)
  • Assessment of pozzolanic activity of calcined coal-series kaolin
    • Authors: Yuanyuan Liu; Shaomin Lei; Min Lin; Yang Li; Zhao Ye; Yanming Fan
      Pages: 159 - 167
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Yuanyuan Liu, Shaomin Lei, Min Lin, Yang Li, Zhao Ye, Yanming Fan
      Coal-series kaolin (from the Yichang region of China) was tested as a potential pozzolanic material to be used in the cement and concrete industry. Thermal treatment was used to activate the raw coal-series kaolin (RCK). Phase identification before and after calcination was studied by X-ray diffraction and Fourier transform infrared spectroscopy. The pozzolanic activity of calcined coal-series kaolin (CCK) was tested by two direct methods, modified Chapelle and Frattini tests, and one indirect method, strength activity index. Aside from thermal treatment, grinding process for CCK was also used to evaluate the effect of particle size distribution on pozzolanic activity. The results showed that pozzolanic activity of CCK was greatly influenced by dehydroxylation and particle size. The modified Chapelle test overestimated pozzolanic activity in the low pozzolanic region (0–1300mg CH/gCCK), and was suitable for complete dehydroxylation samples. The Frattini test accurately assessed CH consumption by pozzolanic reaction, and the strength activity index confirmed the physical effect contribution to CS enhancement at earlier stage and pozzolanic reaction contribution to enhanced microstructure (pore and grain size refinement) and hence improved mechanical strength of cementitious material at later stage.

      PubDate: 2017-04-03T16:26:09Z
      DOI: 10.1016/j.clay.2017.03.038
      Issue No: Vol. 143 (2017)
  • Photocatalytic Cr(VI) reduction by mixed metal oxide derived from ZnAl
           layered double hydroxide
    • Authors: Xiaoya Yuan; Qiuye Jing; Jingtao Chen; Li Li
      Pages: 168 - 174
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Xiaoya Yuan, Qiuye Jing, Jingtao Chen, Li Li
      Mixed metal oxide (MMO) is one of the most important photocatalyts intensively investigated for water remediation. In this study, ZnO/ZnAl2O4 (ZnAl-MMO) nanocomposite was readily prepared via one-step calcination of ZnAl-layered double hydroxide (ZnAl-LDH) at 900°C.·The obtained MMO composite was thoroughly characterized by powder X-ray diffraction (XRD), Scanning electron microscopy (SEM), High-resolution transmission electron microscopy (HRTEM), UV–Vis diffuse reflectance spectroscopy (DRS). ZnAl-MMO was composed of nano-scaled ZnO and ZnAl2O4 crystal grains of high crystallinity and exhibited strong UV light adsorption with a well-developed interface between the two components of the composite. ZnAl-MMO showed high photocatalytic Cr(VI) reduction activity under UV light irradiation and its rate constant was as high as 0.8134h−1. The photoreduction activity of ZnAl-MMO photocatalyt was ascribed to the synergistic effect between two components of the nanocomposite.
      Graphical abstract image

      PubDate: 2017-04-03T16:26:09Z
      DOI: 10.1016/j.clay.2017.03.034
      Issue No: Vol. 143 (2017)
  • A comparative study of co-precipitation and sol-gel synthetic approaches
           to fabricate cerium-substituted MgAl layered double hydroxides with
           luminescence properties
    • Authors: A. Smalenskaite; D.E.L. Vieira; A.N. Salak; M.G.S. Ferreira; A. Katelnikovas; A. Kareiva
      Pages: 175 - 183
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): A. Smalenskaite, D.E.L. Vieira, A.N. Salak, M.G.S. Ferreira, A. Katelnikovas, A. Kareiva
      Mg/Al/Ce layered double hydroxides (LDHs) intercalated with carbonate and hydroxide anions were synthesized using co-precipitation and sol-gel method. The obtained materials were characterized by thermogravimetric (TG) analysis, X-ray diffraction (XRD) analysis, fluorescence spectroscopy (FLS) and scanning electron microscopy (SEM). The chemical composition, microstructure and luminescent properties of these LDHs were investigated and discussed. The Ce3+ substitution effects were investigated in the Mg3Al1− x Ce x LDHs by changing the Ce3+ concentration in the metal cation layers from 0.05 to 10mol%. It was demonstrated, that luminescence properties of cerium-substituted LDHs depend on the morphological features of the host lattice.

      PubDate: 2017-04-03T16:26:09Z
      DOI: 10.1016/j.clay.2017.03.036
      Issue No: Vol. 143 (2017)
  • Effects of microstructure of clay minerals, montmorillonite, kaolinite and
           halloysite, on their benzene adsorption behaviors
    • Authors: Liangliang Deng; Peng Yuan; Dong Liu; Faïza Annabi-Bergaya; Junming Zhou; Fanrong Chen; Zongwen Liu
      Pages: 184 - 191
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Liangliang Deng, Peng Yuan, Dong Liu, Faïza Annabi-Bergaya, Junming Zhou, Fanrong Chen, Zongwen Liu
      Montmorillonite (Mt), kaolinite (Kaol) and halloysite (Hal) are commonly investigated porous clay minerals, but their performance for the adsorption of volatile organic compounds (VOC) was rarely studied. In this work, the dynamic adsorption of benzene, as a model VOC, on Mt, Kaol and Hal was investigated. The effect of the microstructures of the above-mentioned clay minerals on benzene adsorption were explored by comparing the benzene adsorption of the different derivates of these clay minerals, which were obtained by adjusting the interlayer space and the porosity of the clay minerals through heating treatment. Calcium-based montmorillonite (Ca2+-Mt) heated at 120°C exhibited higher benzene adsorption capacity (141.2mg/g) than sodium-based montmorillonite (Na+-Mt) heated at 120°C (87.1mg/g), because the interlayer distance of Ca2+-Mt was sufficiently large to accommodate the adsorption of benzene. However, for calcined Ca2+-Mt and Na+-Mt, the collapse of their interlayer space resulted in that the interlayer micropores no longer existed and reduced benzene adsorption. Kaol exhibited the lowest benzene adsorption capacity (56.7mg/g) among the studied clay minerals because its interlayer space was not available for adsorption and because its specific surface area (SSA) was relatively small. As a polymorph of Kaol but with a tubular morphology, Hal showed a higher benzene adsorption capacity than Kaol owing to its larger SSA. In particular, heating at 120°C resulted in the increase of the benzene adsorption of Hal, which was ascribed to the exposure of the adsorption sites initially occupied by water molecules. These results demonstrate that the benzene adsorption capacity of the above-mentioned clay minerals was not only highly related to their SSA but also strongly affected by their porosity features.

      PubDate: 2017-04-03T16:26:09Z
      DOI: 10.1016/j.clay.2017.03.035
      Issue No: Vol. 143 (2017)
  • Functional organoclay with high thermal stability and its synergistic
           effect on intumescent flame retardant polypropylene
    • Authors: Dan Xiao; Zhi Li; Xiaomin Zhao; Uwe Gohs; Udo Wagenknecht; Brigitte Voit; De-Yi Wang
      Pages: 192 - 198
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Dan Xiao, Zhi Li, Xiaomin Zhao, Uwe Gohs, Udo Wagenknecht, Brigitte Voit, De-Yi Wang
      In this work a novel functional modifier for clay with increased thermal stability and synergistic effect on the flame retardancy of intumescent flame retardant polypropylene (IFR PP) composites was developed. First, triphenyl(undec-10-enyl)phosphonium bromide (TPB) was synthesized and characterized by FT-IR and 1H NMR spectroscopy. TPB has a high thermal stability with an initial decomposition temperature of about 270°C. Subsequently, TPB was used to prepare functional organoclay (OC) by cation exchange reaction. OC was characterized by thermogravimetric analysis (TGA) and wide-angle X-ray scattering (WAXS). The interlayer distance of novel OC increased to 1.85nm. OC was used in IFR PP nanocomposites prepared by melt mixing. The morphology, thermal stability and fire behavior of these IFR PP nanocomposites were investigated by SEM, TEM, TGA, limiting oxygen index (LOI), vertical burning test (UL94), and cone calorimeter (CC) test. In comparison to IFR (18wt%) PP composites, IFR (16wt%)+OC (2wt%) PP nanocomposites passed the UL94 V-0 rating and showed no dripping. The LOI value decreased from 30.5 to 28.8 due to the use of low molar mass TBP. It was shown by cone calorimeter tests that the additional used of 1 or 2wt% OC leads to a reduced heat release rate, smoke production rate and total smoke production. All these experimental results showed that this novel OC provided an excellent synergistic effect on the flame retardancy of IFR PP composites. Finally, electron beam treatment was used to enhance the thermal stability of flame retardant nanocomposites.

      PubDate: 2017-04-03T16:26:09Z
      DOI: 10.1016/j.clay.2017.03.039
      Issue No: Vol. 143 (2017)
  • Novel ceramics prepared from inferior clay rich in CaO and Fe2O3:
           Properties, crystalline phases evolution and densification process
    • Authors: Feng Jiang; Yu Li; Lihua Zhao; Daqiang Cang
      Pages: 199 - 204
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Feng Jiang, Yu Li, Lihua Zhao, Daqiang Cang
      Inferior clay rich in CaO and Fe2O3 is a typical clay with huge reserves in southwest of China, which cannot be used in traditional aluminosilicate system ceramics. To efficiently utilize the inferior clay, a method of preparing novel ceramics containing CaO and Fe2O3 was put forward. In this study, effects of inferior clay proportion on properties, CaO on evolution of crystalline phases and Fe2O3 on densification process were analyzed by XRF, XRD, TG-DTA and SEM-EDS combined with physical properties tests. The results showed that addition of inferior clay (from 20 to 70wt%) significantly affected sintering temperature (from 1190 to 1130°C). High activity CaO decomposed by carbonate transformed into anorthite and diopside at low temperature. Fe2O3 promoted generation of low-temperature liquid phase, which facilitated densification process. The fired ceramics (60wt% inferior clay) sintered at 1130°C exhibited excellent properties with water absorption of 0.05%, linear shrinkage of 6.8% and flexural strength of 70MPa. This batch was applied into an industrial experiment and 1160m2 qualified ceramics (ISO 10545-4:2004) were fabricated.

      PubDate: 2017-04-11T17:14:07Z
      DOI: 10.1016/j.clay.2017.03.026
      Issue No: Vol. 143 (2017)
  • Phase transformation and morphology evolution of sepiolite fibers during
           thermal treatment
    • Authors: Yuedan Zhang; Lijuan Wang; Fei Wang; Jinsheng Liang; Songsong Ran; Jianfeng Sun
      Pages: 205 - 211
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Yuedan Zhang, Lijuan Wang, Fei Wang, Jinsheng Liang, Songsong Ran, Jianfeng Sun
      In this study, the phase transformation and micromorphology evolution of sepiolite fibers were studied along with the increase of temperature from 300 to 1300°C, using raw sepiolite samples as raw materials. Through characterization by scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD), thermo-gravimetric analysis (TGA/DTG) and differential scanning calorimeter (DSC), it was found that the determined transition temperature values for the dehydrations of the hygroscopic water and the zeolitic water were 120°C and 340°C, and the values for the dehydration of the bound water and the dehydroxylation of the hydroxyls were about 500°C and 810°C. Moreover, orthoenstatite (MgSiO3) was recrystallized from dehydroxylated phase at 852°C and then transformed into protoenstatite at 970°C, and enstatite crystals grew along with c-axis of the fiber with the increase of temperature. Amorphous phase as the other phase of sepiolite dehydroxylation recrystallized into cristobalite in the temperature range of 1130–1200°C and the samples began to melt at the above temperature range. In terms of morphology, both sepiolite bundles and laths remained constant after heating up to 1000°C and sintering phenomenon appeared when the temperature was up to 1100°C. The bundles partly melted and adhered each other, which further formed a porous structure after calcination at 1200°C. When the temperature was up to 1300°C, the sample substantially melted except for a small amount of enstatite and cristobalite crystals. The present study reflects the thermal reaction of sepiolite, which could be applied in exploring the reinforcement mechanism of sepiolite reinforced ceramic body composites.

      PubDate: 2017-04-11T17:14:07Z
      DOI: 10.1016/j.clay.2017.03.042
      Issue No: Vol. 143 (2017)
  • Structural and thermodynamic investigation of the hydration-dehydration
           process of Na+-Montmorillonite using DFT calculations
    • Authors: Carla G. Fonseca; Viviane S. Vaiss; Fernando Wypych; Renata Diniz; Alexandre A. Leitão
      Pages: 212 - 219
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Carla G. Fonseca, Viviane S. Vaiss, Fernando Wypych, Renata Diniz, Alexandre A. Leitão
      This work is mainly focused on investigating the atomic structure of the interlayer water molecules inside Na+-Montmorillonite, their key interactions in the structure and the thermodynamics of the dehydration process. A theoretical study of the different degrees of hydration was performed using calculations based on DFT with several exchange-correlation functionals. The weak layer–water molecules interactions suggested the need of dispersion corrections to simulate correctly the basal spacing and the thermodynamic potentials for the dehydration process. The existence of the structures with sodium cation in planar geometry, representative of the one-water layer model and in octahedral geometry in a two-water layer model was confirmed. The stages of the dehydration of Na+–Mt were evaluated by thermodynamics calculations leading to a good description of the results from TGA/DTG studies. The thermodynamic data suggest also that the one-water layer structure as an intermediate with a metastable configuration.

      PubDate: 2017-04-11T17:14:07Z
      DOI: 10.1016/j.clay.2017.03.025
      Issue No: Vol. 143 (2017)
  • Ab initio simulations of the intercalation of iron(III) porphyrinates in
           Zn2Al-LDH: Structural analysis and evaluation of their basic and acid
    • Authors: Sérgio R. Tavares; Shirley Nakagaki; Fernando Wypych; Alexandre A. Leitão
      Pages: 220 - 226
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Sérgio R. Tavares, Shirley Nakagaki, Fernando Wypych, Alexandre A. Leitão
      Density functional theory (DFT) calculations were performed to study the interaction between three dehydrated porphyrinates anions after the intercalation between Zn2Al layered double hydroxide layers, reported experimentally. A good agreement was obtained for the unit cell parameters and an analysis of the simulation approaches was conducted for the first-generation porphyrin metallated with iron(III). Post-processing calculations were also performed in order to evaluate the stabilization of these intercalation compounds and to pinpoint the acid/basic sites. These intercalation compounds are mainly stabilized by charge transfers and, for the case of the iron(III)metallated porphyrins studied in the present work, the acidity of the iron(III) centers analyzed by PDOS was not significantly affected by the porphyrin ring phenyl substitutions.
      Graphical abstract image

      PubDate: 2017-04-11T17:14:07Z
      DOI: 10.1016/j.clay.2017.03.029
      Issue No: Vol. 143 (2017)
  • Kinetic, equilibrium and thermodynamic studies for sorption of
           2,4-dichlorophenol onto surfactant modified fuller's earth
    • Authors: Jasmin Shah; M. Rasul Jan; M. Zeeshan; M. Imran
      Pages: 227 - 233
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Jasmin Shah, M. Rasul Jan, M. Zeeshan, M. Imran
      The applicability of surfactant modified fuller's earth (SMFE) for removing 2,4-dichlorophenol (2,4-DCP) from water has been investigated through batch sorption process. Fuller's earth was treated with sodium dodecyl sulphate (SDS) for conversion of fuller's earth into surfactant modified fuller's earth. The influence of pH, agitation time, sorbent dose, temperature and initial concentration of 2,4-DCP were investigated. A strong dependence of the sorption capacity on pH was observed, the capacity increased as the pH value decreased. The sodium dodecyl sulphate increased the hydrophobicity of the sorbent and provided particular affinity for 2,4-DCP molecules. The SMFE showed high efficiency towards 2,4-DCP and >97% removal was achieved from an initial concentration of 20mg/L at 100°C using pH3. The kinetics of the sorption process was described by a pseudo-second-order kinetic model. The mechanism of sorption kinetics was investigated using intraparticle diffusion model. The sorption isotherm was consistent with the Langmuir sorption isotherm and maximum monolayer capacity of the SMFE was found to be 126.58mg/g at room temperature. The mean adsorption energy (E) value 18.25kJ/mol indicated chemical sorption and endothermic sorption process.

      PubDate: 2017-04-11T17:14:07Z
      DOI: 10.1016/j.clay.2017.03.040
      Issue No: Vol. 143 (2017)
  • A new approch to sepiolite dispersion by treatment with ionic liquids
    • Authors: Juliana A. de Lima; Fernanda F. Camilo; Roselena Faez; Sandra A. Cruz
      Pages: 234 - 240
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Juliana A. de Lima, Fernanda F. Camilo, Roselena Faez, Sandra A. Cruz
      The possibility of sepiolite disaggregation is a challenge to enhance significantly its performance and extend its application. In this direction, this work introduces the treatment of sepiolite (Sep) with three different ionic liquid (IL). The used ionic liquids were 1-methyl-3-butylimidazolium bis(trifluoromethanesulfonyl) imide (BMImTf2N), 1-methyl-3-octylimidazolium bis(trifluoromethanesulfonyl) imide (OMImTf2N) and 1-methyl-3- dodecylimidazolium bis(trifluoromethanesulfonyl) imide (DMImTf2N). The influence on structural, thermal properties and morphology in Sep treated with IL were evaluated using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TG), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), N2 sorption measurements, 29Si nuclear magnetic resonance (29Si NMR) and zeta potential. Sepiolite structure was preserved for all the samples treated with ionic liquids. FTIR and XRD results show that BMImTf2N substitutes water molecules coordinated to Mg+2 more efficiently. Thermogravimetric analysis indicated that the interaction between Sep and IL delayed the release of water. From these data, it was also possible to confirm the presence of 5 mass% of IL in all samples. FESEM and TEM images demonstrated more disaggregated Sep fibers with IL, especially the samples treated with BMImTf2N. This fact is attributed to the immobilization of ionic liquid on Sep tunnels, which is coherent with 29Si NMR analyses. The potential applications of these modified sepiolites are as reinforcing agent for polymers, template for nanostructured materials and support for catalysts.
      Graphical abstract image

      PubDate: 2017-04-18T09:08:33Z
      DOI: 10.1016/j.clay.2017.03.032
      Issue No: Vol. 143 (2017)
  • Synthesis and characterization of Zn-Al layered double hydroxide nanofluid
           and its application as a coolant in metal quenching
    • Authors: A.M. Tiara; Samarshi Chakraborty; Ishita Sarkar; Surjya K. Pal; Sudipto Chakraborty
      Pages: 241 - 249
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): A.M. Tiara, Samarshi Chakraborty, Ishita Sarkar, Surjya K. Pal, Sudipto Chakraborty
      The current study comprises of the synthesis and characterization of Zn-Al layered double hydroxide (LDH) nanofluid for use as a potential coolant in the steel industry. Coprecipitation method was used in the preparation of Zn-Al LDH nanoparticles by using the nitrate salts of Zn, Al and Na, in the ratio of 2:1:2. The nanofluids were characterized based on their particle size, stability, surface tension, thermal conductivity and viscosity. TEM analysis revealed that the nanoparticles were needle-shaped with an average particle size of 45.61nm and aspect ratio of 7.3. Different concentrations of the nanofluid, from 40ppm to 240ppm, were used to analyze the effect of particle concentration on the enhancement in thermal conductivity and viscosity. Stability analysis of the nanofluid exhibited good results, even without any stabilizer. An optimum cooling rate of 125°C/s was obtained for a nanofluid concentration of 160ppm, which is 1.29 times when compared to water.

      PubDate: 2017-04-11T17:14:07Z
      DOI: 10.1016/j.clay.2017.03.028
      Issue No: Vol. 143 (2017)
  • Acid clay minerals as eco-friendly and cheap catalysts for the synthesis
           of β-amino ketones by Mannich reaction
    • Authors: Fernando Gómez-Sanz; María Virtudes Morales-Vargas; Beatriz González-Rodríguez; María Luisa Rojas-Cervantes; Elena Pérez-Mayoral
      Pages: 250 - 257
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Fernando Gómez-Sanz, María Virtudes Morales-Vargas, Beatriz González-Rodríguez, María Luisa Rojas-Cervantes, Elena Pérez-Mayoral
      The characterization and catalytic performance of different smectites, one raw saponite and some commercial montmorillonites, exhibiting mesoporous and acid character are herein reported. The catalysts under study are able to catalyze efficiently via Mannich-type reactions the synthesis of β-amino ketones, which are important building blocks for the drugs synthesis and biologically active natural products. Montmorillonite K10 (Mt-K10) was the most efficient catalyst for the Mannich reaction between the pre-formed imine, N-benzylideneaniline, and cyclohexanone resulting in a recyclable catalyst for at least three catalytic cycles without activity loss. Almost quantitative yield to the β-amino carbonyl compound was obtained after 240min when operating under the most favorable conditions. The catalytic performance of the smectites seemed to be influenced by their porosity, but also by both Brönsted and Lewis acid site concentrations. In fact, the concentration of the Lewis acid catalytic sites would be the key in the Michael addition of cyclohexanone to the imine, although the Brönsted acid sites contribution cannot be neglected. The β-amino carbonyl compound was also synthesized in an excellent yield (86%) in only 15min of reaction time through the one-pot three component reaction, by reaction between benzaldehyde, aniline and cyclohexanone.
      Graphical abstract image

      PubDate: 2017-04-11T17:14:07Z
      DOI: 10.1016/j.clay.2017.03.033
      Issue No: Vol. 143 (2017)
  • Ceramic porcelain stoneware production with Spanish clays purified by
           means of the removal of iron compounds and organic matter using physical
    • Authors: E. Barrachina; I. Calvet; D. Fraga; J.B. Carda
      Pages: 258 - 264
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): E. Barrachina, I. Calvet, D. Fraga, J.B. Carda
      As the production of ceramic porcelain stoneware in Spain is totally conditioned by the importation of ball clays, because of the lack of adequate Spanish ball clays, this work has focused on the formulation of ceramic porcelain body from Spanish clays purified by means of physical removal processes. This method was applied to three Spanish clays containing common clay impurities of iron (hematite and siderite) and organic matter. Iron removal was carried out using the wet sieve method, the hydrocycloning method and the electromagnetic filtering method, obtaining a reduction in iron content of up to 80wt%, while the clay containing organic matter was treated thermally at 400°C for 30min so as to leave it almost completely purified. These treated clays, after being characterized (chemical and mineralogical composition, plasticity, organic carbon, thermal behaviour and colour), were used in the porcelain stoneware body composition instead of imported clays, the result being a composition capable of substituting the standard porcelain stoneware formulation in terms of sintering, morphology, colour, flexural strength and dilatometry.

      PubDate: 2017-04-11T17:14:07Z
      DOI: 10.1016/j.clay.2017.03.024
      Issue No: Vol. 143 (2017)
  • Recent progress in layered double hydroxides (LDH)-containing hybrids as
           adsorbents for water remediation
    • Authors: Mukarram Zubair; Muhammad Daud; Gordon McKay; Farrukh Shehzad; Mamdouh A. Al-Harthi
      Pages: 279 - 292
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Mukarram Zubair, Muhammad Daud, Gordon McKay, Farrukh Shehzad, Mamdouh A. Al-Harthi
      With rapidly growing industrial development worldwide, the need for a new class of nanoparticles and techniques for treating wastewater remains a major concern to protect the environment. Layered double hydroxides and particularly LDH-containing hybrids are emerging as potential nano-sized adsorbents for water treatment. Recent studies have demonstrated LDH-containing hybrids as promising multifunctional materials for potential utilization in various applications such as, photo-catalysis, energy storage, nanocomposites and water purification. This article reviews the recent applications of LDH-containing hybrids as adsorbents for water remediation. The maximum adsorption capacities of various toxic heavy metals and dyes on different LDH hybrids were reported as 483mg/g for Pb2+, 95mg/g for Cd2+, 181mg/g for Cu2+, 649mg/g for Cr6+, 180mg/g As5+, 813mg/g for Hg2+, 450 for Ag+, 277mg/g for U6+, 1062mg/g for methyl orange, 185mg/g for methylene blue, and 1250mg/g for Congo red, which is comparatively higher than other commercial adsorbents. This review discusses the adsorption performance of manifold LDH-containing hybrids for treating various pollutants such as heavy metals and dyes. The mechanisms of interaction of LDH-containing hybrids with pollutants and the influence of key adsorption parameters such as pH, contact time, adsorbent dose and temperature have been comprehensively discussed. Moreover, the regeneration potential and reuse of spent LDH-containing hybrids and its toxicity effects have also been reviewed.
      Graphical abstract image

      PubDate: 2017-04-11T17:14:07Z
      DOI: 10.1016/j.clay.2017.04.002
      Issue No: Vol. 143 (2017)
  • Experimental evaluation of the effects of pull rate on the tensile
           behavior of a clay
    • Abstract: Publication date: August 2017
      Source:Applied Clay Science, Volume 144
      Author(s): R.N. Tollenaar, L.A. van Paassen, C. Jommi
      Tensile strength is one of the main variables involved in the formation of desiccation fractures in clay. It is known that the drying rate affects the final amount of cracks in a soil, which points out to the potential influence of rate effects in soil cracking. The effects might be related to variations in the tensile strength affected by different shrinkage rates. A limited amount of investigations have looked at the impact of strain rate on the tensile strength of soil. This study examines the combined effects of pull rates and high water contents on the tensile strength of a clay. Particle Image Velocimetry analysis was also carried out on pictures taken during the tests to examine the strains generated. It was found that the effect of pull rate on the tensile strength of the clay was negligible compared to the effect of the water content. Pull rate did affect the stiffness response of the soil. The findings revealed that the influence of the evaporation rate on soil fracturing might be related more to the rate dependency of the stiffness rather than to significant changes in tensile strength.

      PubDate: 2017-05-22T16:09:03Z
  • Novel adsorptive mixed matrix membranes by embedding modified
           montmorillonite with arginine amino acid into polysulfones for As(V)
    • Abstract: Publication date: August 2017
      Source:Applied Clay Science, Volume 144
      Author(s): E. Shokri, R. Yegani, A. Akbarzadeh
      Neat and arginine modified montmorillonite, Mt and Mt-Arg, were embedded into polysulfone (PSf) to prepare adsorptive mixed matrix membranes (AMMMs) for arsenate removal from contaminated water. Prepared membranes were characterized by FE-SEM, XRD, AFM, pure water flux and contact angle measurement. Equilibrium adsorption capacity and adsorption kinetic of AMMMs were determined using batch adsorption experiments. In addition, dynamic adsorption and regeneration studies were also investigated in dead-end filtration setup. Adsorption kinetic of arsenate was found to follow pseudo-second-order kinetic model and equilibrium data showed good correlation with the Langmuir model for AMMMs. The obtained results revealed that the arsenate adsorption was favorable for PSf/Mt-Arg. Regeneration capability of the Mt-Arg embedded PSf membranes was assessed by conducting ten cycles of adsorption-desorption experiments. Arg modified Mt provides interesting properties to adsorb As(V) from water in neutral pH and desorb in alkaline condition; pH=9, due to negative side group. The obtained results confirmed the applicability of the prepared PSf/Mt-Arg in As(V) removal for multiple cycles.
      Graphical abstract image

      PubDate: 2017-05-22T16:09:03Z
  • A novel approach to synthesize in-situ crystallized zeolite/kaolin
           composites with high zeolite content
    • Abstract: Publication date: August 2017
      Source:Applied Clay Science, Volume 144
      Author(s): Ning Li, Tiesen Li, Haiyan Liu, Yuanyuan Yue, Xiaojun Bao
      We present an alkali solution aided (ASA) activation approach to activate kaolin microspheres and its application to synthesize in-situ crystallized zeolite/kaolin composite materials. Compared with conventional thermal activation methods, the ASA activation can high-effectively convert silicon and aluminum species in kaolin microspheres into active silica and alumina for synthesizing zeolite/kaolin composites, leading to a successful synthesis of zeolite/kaolin composites with high zeolite content and outstanding attrition resistance. When used as a fluid catalytic cracking catalyst, the resulting zeolite Y/kaolin composite gave high conversion efficiency of vacuum oil and high selectivity to valuable products.
      Graphical abstract image

      PubDate: 2017-05-22T16:09:03Z
  • Clay hydration mechanisms and their effect on dustiness
    • Abstract: Publication date: August 2017
      Source:Applied Clay Science, Volume 144
      Author(s): A. López-Lilao, M.P. Gómez-Tena, G. Mallol, E. Monfort
      Clays are employed in a wide variety of industries such as ceramic industry, manufacture of paper, rubber, etc. In this sense, it is well known that at industrial processes in which clayey materials are used, such as ceramic industry, in order to carry out some specific stages, the wetting of clays is commonly required. Moreover, it is also long established that wetting is an appropriated measure to reduce particulate matter emissions during clays storage and handling. The present study was undertaken to assess the influence of moisture on clay dustiness because, though the complex behaviour of the clay–water system has been known since antiquity, the mechanisms involved in clay hydration and their influence on dustiness are still not well understood. To encompass a wide range of specific surface areas, three clays and a kaolin were studied. Chemical and mineralogical analysis of these four raw materials was performed and their particle size distribution, flowability, true density, plastic limit, and specific surface area were determined. Raw materials dustiness was determined using the continuous drop method. As against what might intuitively be expected, the results showed that the relationship between moisture and dustiness was quite complex and strongly related to the hydration mechanisms. In this regard, to better understand the phenomena involved in the clay hydration process, a specific methodology was developed to estimate the critical points of the clay hydration process (regarding dustiness). This methodology can be readily applied to other clays or even to materials of different nature to predict the optimum moisture and, therefore, it could be employed to propose specific measures which could entail an improvement of outdoor and indoor air quality.
      Graphical abstract image

      PubDate: 2017-05-22T16:09:03Z
  • Vermiculite/poly(lactic acid) composites: Effect of nature of vermiculite
           on hydrolytic degradation in alkaline medium
    • Authors: Dolores
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): M. Dolores Fernández, M. Jesús Fernández
      Unmodified and different organomodified vermiculites were used for the preparation of poly(l-lactide) (PLLA) composites via melt mixing. The effect of the clay mineral surface modification, the type of organic modifier of the vermiculite and sample thickness on the degradation of PLLA in alkaline medium at 37°C was studied. The degradation was evaluated by analyzing mass loss, pH, molecular weights, and morphological changes. Alkaline hydrolysis of PLLA was accelerated by the presence of clay mineral and the degradation rate was very much dependent on type of clay mineral and state of dispersion. Morphological changes suggested that the erosion mechanism of polymer matrix occurred at the film surfaces and started at the interface of polymer and clay minerals. The results presented here show that the hydrolytic degradation of PLLA can be controlled through the preparation of nanocomposites introducing the appropriate organomodified nanoclay mineral.
      Graphical abstract image

      PubDate: 2017-03-16T09:26:35Z
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