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    - EARTH SCIENCES (473 journals)
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EARTH SCIENCES (473 journals)                  1 2 3 | Last

Showing 1 - 200 of 371 Journals sorted alphabetically
Acta Geochimica     Hybrid Journal   (Followers: 6)
Acta Geodaetica et Geophysica     Hybrid Journal   (Followers: 2)
Acta Geodaetica et Geophysica Hungarica     Full-text available via subscription   (Followers: 2)
Acta Geophysica     Open Access   (Followers: 10)
Acta Geotechnica     Hybrid Journal   (Followers: 7)
Acta Meteorologica Sinica     Hybrid Journal   (Followers: 3)
Advances in High Energy Physics     Open Access   (Followers: 19)
Advances In Physics     Hybrid Journal   (Followers: 20)
Aeolian Research     Hybrid Journal   (Followers: 6)
African Journal of Aquatic Science     Hybrid Journal   (Followers: 13)
Algological Studies     Full-text available via subscription   (Followers: 1)
Alpine Botany     Hybrid Journal   (Followers: 5)
AMBIO     Hybrid Journal   (Followers: 11)
Anales del Instituto de la Patagonia     Open Access  
Andean geology     Open Access   (Followers: 9)
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: 20)
Annual Review of Marine Science     Full-text available via subscription   (Followers: 10)
Anthropocene     Hybrid Journal   (Followers: 4)
Anthropocene Review     Hybrid Journal   (Followers: 6)
Applied Clay Science     Hybrid Journal   (Followers: 6)
Applied Geochemistry     Hybrid Journal   (Followers: 14)
Applied Geomatics     Hybrid Journal   (Followers: 3)
Applied Geophysics     Hybrid Journal   (Followers: 8)
Applied Ocean Research     Hybrid Journal   (Followers: 8)
Applied Petrochemical Research     Open Access   (Followers: 3)
Aquatic Conservation Marine and Freshwater Ecosystems     Hybrid Journal   (Followers: 35)
Arctic Science     Open Access   (Followers: 7)
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: 20)
Asia-Pacific Journal of Atmospheric Sciences     Hybrid Journal   (Followers: 19)
Asian Journal of Earth Sciences     Open Access   (Followers: 19)
Asian Review of Environmental and Earth Sciences     Open Access   (Followers: 2)
Atlantic Geology : Journal of the Atlantic Geoscience Society / Atlantic Geology : revue de la Société Géoscientifique de l'Atlantique     Full-text available via subscription   (Followers: 9)
Atmosphere-Ocean     Full-text available via subscription   (Followers: 12)
Atmospheric and Climate Sciences     Open Access   (Followers: 24)
Australian Journal of Earth Sciences: An International Geoscience Journal of the Geological Society of Australia     Hybrid Journal   (Followers: 10)
Boletim de Ciências Geodésicas     Open Access  
Bonorowo Wetlands     Open Access  
Boreas: An International Journal of Quaternary Research     Hybrid Journal   (Followers: 11)
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: 23)
Bulletin of Volcanology     Hybrid Journal   (Followers: 20)
Cadernos de Geociências     Open Access  
Canadian Mineralogist     Full-text available via subscription   (Followers: 6)
Canadian Water Resources Journal     Hybrid Journal   (Followers: 20)
Carbonates and Evaporites     Hybrid Journal   (Followers: 2)
CATENA     Hybrid Journal   (Followers: 8)
Chemical Geology     Hybrid Journal   (Followers: 25)
Chemie der Erde - Geochemistry     Hybrid Journal   (Followers: 5)
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: 9)
Computational Geosciences     Hybrid Journal   (Followers: 16)
Computational Mathematics and Mathematical Physics     Hybrid Journal   (Followers: 3)
Computers and Geotechnics     Hybrid Journal   (Followers: 11)
Contemporary Trends in Geoscience     Open Access   (Followers: 2)
Continental Shelf Research     Hybrid Journal   (Followers: 9)
Contributions to Mineralogy and Petrology     Hybrid Journal   (Followers: 12)
Contributions to Plasma Physics     Hybrid Journal   (Followers: 4)
Coral Reefs     Hybrid Journal   (Followers: 18)
Cretaceous Research     Hybrid Journal   (Followers: 11)
Cybergeo : European Journal of Geography     Open Access   (Followers: 5)
Depositional Record     Open Access   (Followers: 2)
Developments in Geotectonics     Full-text available via subscription   (Followers: 2)
Developments in Quaternary Science     Full-text available via subscription   (Followers: 4)
Développement durable et territoires     Open Access   (Followers: 2)
Diatom Research     Hybrid Journal   (Followers: 3)
Doklady Physics     Hybrid Journal   (Followers: 1)
Dynamics of Atmospheres and Oceans     Hybrid Journal   (Followers: 13)
E&S Engineering and Science     Open Access  
E3S Web of Conferences     Open Access   (Followers: 1)
Earth and Planetary Science Letters     Hybrid Journal   (Followers: 154)
Earth and Space Science     Open Access   (Followers: 14)
Earth Interactions     Full-text available via subscription   (Followers: 12)
Earth Science Frontiers     Full-text available via subscription   (Followers: 7)
Earth Science Malaysia     Open Access  
Earth Science Research     Open Access   (Followers: 9)
Earth Sciences Pakistan     Open Access  
Earth Surface Dynamics (ESurf)     Open Access   (Followers: 7)
Earth Surface Processes and Landforms     Hybrid Journal   (Followers: 20)
Earth System Dynamics     Open Access   (Followers: 7)
Earth System Dynamics Discussions     Open Access   (Followers: 4)
Earth's Future     Open Access   (Followers: 1)
Earth, Planets and Space     Open Access   (Followers: 67)
Earthquake Engineering and Engineering Vibration     Hybrid Journal   (Followers: 9)
Earthquake Science     Hybrid Journal   (Followers: 11)
Earthquake Spectra     Full-text available via subscription   (Followers: 21)
Ecohydrology     Hybrid Journal   (Followers: 9)
Ecological Questions     Open Access   (Followers: 3)
Electromagnetics     Hybrid Journal   (Followers: 8)
Energy Efficiency     Hybrid Journal   (Followers: 10)
Energy Exploration & Exploitation     Open Access   (Followers: 4)
Environmental Earth Sciences     Hybrid Journal   (Followers: 25)
Environmental Geology     Hybrid Journal   (Followers: 18)
Environmental Geosciences     Full-text available via subscription   (Followers: 5)
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: 35)
Estudios Geográficos     Open Access  
European Journal of Mineralogy     Full-text available via subscription   (Followers: 15)
European Journal of Remote Sensing     Open Access   (Followers: 5)
Exploration Geophysics     Hybrid Journal   (Followers: 3)
Facies     Hybrid Journal   (Followers: 10)
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: 9)
Frontiers in Earth Science     Open Access   (Followers: 5)
Frontiers in Geotechnical Engineering     Open Access   (Followers: 3)
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: 6)
Geoacta     Open Access   (Followers: 2)
Geobiology     Hybrid Journal   (Followers: 8)
Geocarto International     Hybrid Journal   (Followers: 22)
Geochemistry : Exploration, Environment, Analysis     Hybrid Journal   (Followers: 7)
Geochemistry, Geophysics, Geosystems     Full-text available via subscription   (Followers: 30)
Geochimica et Cosmochimica Acta     Hybrid Journal   (Followers: 53)
Geochronometria     Hybrid Journal   (Followers: 2)
Geoderma Regional : The International Journal for Regional Soil Research     Full-text available via subscription   (Followers: 4)
Geodinamica Acta     Open Access   (Followers: 2)
Geodynamics & Tectonophysics     Open Access   (Followers: 2)
Geoenvironmental Disasters     Open Access   (Followers: 3)
Geofluids     Open Access   (Followers: 4)
Geoforum     Hybrid Journal   (Followers: 25)
Géographie physique et Quaternaire     Full-text available via subscription   (Followers: 1)
Geography and Natural Resources     Hybrid Journal   (Followers: 7)
GeoHealth     Open Access  
Geoheritage     Hybrid Journal   (Followers: 1)
Geoinformatica Polonica : The Journal of Polish Academy of Arts and Sciences     Open Access  
Geoinformatics & Geostatistics     Hybrid Journal   (Followers: 11)
Geological Journal     Hybrid Journal   (Followers: 17)
Geological Magazine     Hybrid Journal   (Followers: 16)
Geology Today     Hybrid Journal   (Followers: 29)
Geology, Geophysics and Environment     Open Access   (Followers: 2)
Geomagnetism and Aeronomy     Hybrid Journal   (Followers: 3)
Geomatics, Natural Hazards and Risk     Open Access   (Followers: 11)
Geomechanics for Energy and the Environment     Full-text available via subscription   (Followers: 1)
GEOmedia     Open Access   (Followers: 1)
Geomorphology     Hybrid Journal   (Followers: 30)
Geophysical & Astrophysical Fluid Dynamics     Hybrid Journal   (Followers: 2)
Geophysical Journal International     Hybrid Journal   (Followers: 35)
Geophysical Prospecting     Hybrid Journal   (Followers: 8)
Geophysics     Full-text available via subscription   (Followers: 21)
GeoResJ     Hybrid Journal  
Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards     Hybrid Journal   (Followers: 10)
Geoscience Canada : Journal of the Geological Association of Canada / Geoscience Canada : journal de l'Association Géologique du Canada     Full-text available via subscription   (Followers: 6)
Geoscience Data Journal     Open Access   (Followers: 2)
Geoscience Frontiers     Open Access   (Followers: 9)
Geoscience Letters     Open Access  
Geoscience Records     Open Access  
Geosciences     Open Access   (Followers: 1)
Geosciences Journal     Hybrid Journal   (Followers: 9)
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: 1)
Glass Physics and Chemistry     Hybrid Journal   (Followers: 4)
Global and Planetary Change     Hybrid Journal   (Followers: 16)
Global Biogeochemical Cycles     Full-text available via subscription   (Followers: 18)
Gondwana Research     Hybrid Journal   (Followers: 11)
GPS Solutions     Hybrid Journal   (Followers: 24)
Grassland Science     Hybrid Journal  
Ground Water     Hybrid Journal   (Followers: 36)
Ground Water Monitoring & Remediation     Hybrid Journal   (Followers: 18)
Groundwater for Sustainable Development     Full-text available via subscription   (Followers: 3)
Helgoland Marine Research     Open Access   (Followers: 3)
History of Geo- and Space Sciences     Open Access   (Followers: 1)
Hydrobiologia     Hybrid Journal   (Followers: 18)
Hydrogeology Journal     Hybrid Journal   (Followers: 20)
Hydrological Processes     Hybrid Journal   (Followers: 30)
Hydrology and Earth System Sciences     Open Access   (Followers: 29)
ICES Journal of Marine Science: Journal du Conseil     Hybrid Journal   (Followers: 50)
IEEE Journal of Oceanic Engineering     Hybrid Journal   (Followers: 11)
Indian Geotechnical Journal     Hybrid Journal   (Followers: 4)
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   (Followers: 2)
International Journal of Advanced Remote Sensing and GIS     Open Access   (Followers: 39)
International Journal of Advancement in Earth and Enviromental Sciences     Open Access   (Followers: 4)
International Journal of Advancement in Remote Sensing, GIS, and Geography     Open Access   (Followers: 31)
International Journal of Applied Earth Observation and Geoinformation     Hybrid Journal   (Followers: 34)

        1 2 3 | Last

Journal Cover
Applied Clay Science
Journal Prestige (SJR): 0.992
Citation Impact (citeScore): 4
Number of Followers: 6  
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0169-1317
Published by Elsevier Homepage  [3163 journals]
  • Effect of structural and textural properties of a ceramic industrial
           sludge and kaolin on the hardened geopolymer properties
    • Authors: Noureddine Belmokhtar; Houda El Ayadi; Mohammed Ammari; Laïla Ben Allal
      Pages: 1 - 9
      Abstract: Publication date: 15 September 2018
      Source:Applied Clay Science, Volume 162
      Author(s): Noureddine Belmokhtar, Houda El Ayadi, Mohammed Ammari, Laïla Ben Allal
      This paper presents a comparative structural and textural study of an industrial sludge and commercial kaolin, in order to explain the transformation of the industrial sludge after calcination and to correlate the raw material properties to the hardened geopolymer products structure and compressive strength. The industrial sludge used in this study comes from a local factory manufacturing ceramic sanitary products. The amorphization and the dehydroxylation of the two materials were followed by X-ray diffraction, infrared spectroscopy and thermogravimetric method. The clay morphology was verified by scanning electron and transmission electron microscopies. The textural study of materials was carried out using two techniques, the mercury porosimetry and nitrogen adsorption. The chemical composition of the newly formed geopolymers phases was followed by FTIR spectroscopy. The XRD analysis revealed that the crystallinity of the industry sludge is lower than that of commercial Kaolin. The FTIR analysis confirmed that the dehydroxylation of the ceramic industrial sludge at the chosen temperature caused a total removal of hydroxyl groups. The N2 adsorption isotherms of the calcined industry sludge (MB) and the Metakaolin (MK) showed that the texture is formed by the agglomeration of aggregates. The maximum value of the compressive strength of MB-geopolymer is too close to that of MK-geopolymer (about 29 MPa), confirming therefore the great reactivity of the ceramic industrial sludge. We conclude that the industrial ceramic sludge appears to be a very efficient material that should find a niche in a market where kaolin clay is becoming scarce.

      PubDate: 2018-06-01T10:21:57Z
      DOI: 10.1016/j.clay.2018.05.029
      Issue No: Vol. 162 (2018)
  • Removal of silver nanoparticles with native and magnetically modified
    • Authors: Dominik Janacek; Libor Kvitek; Martina Karlikova; Kristyna Pospiskova; Ivo Safarik
      Pages: 10 - 14
      Abstract: Publication date: 15 September 2018
      Source:Applied Clay Science, Volume 162
      Author(s): Dominik Janacek, Libor Kvitek, Martina Karlikova, Kristyna Pospiskova, Ivo Safarik
      Silver nanoparticles released from a variety of consumer products represent a hazard for the environment. Their removal using appropriate low-cost adsorbents is a progressive way of economical treatment of the polluted environment, especially water sources. Magnetically responsive materials form a progressive group of adsorbents, that is why magnetically responsive composite of a clay mineral halloysite has been prepared by mechanochemical synthesis. Halloysite with the deposited iron oxide nanoparticles has been successfully applied for the removal of silver nanoparticles from water dispersion. Both native and magnetic materials exhibited high adsorption efficiency; magnetically modified halloysite had higher maximum adsorption capacity (67.9 mg g−1) than the native form (40.9 mg g−1). This low-cost, advanced composite material, that can be easily separated from water using external magnetic field, is a very promising adsorbent for future environmental technologies, especially for the treatment of water polluted with silver nanoparticles.

      PubDate: 2018-06-01T10:21:57Z
      DOI: 10.1016/j.clay.2018.05.024
      Issue No: Vol. 162 (2018)
  • Valorization of mussel and oyster shells toward metakaolin-based alkaline
           activated material
    • Authors: Matthias Monneron-Gyurits; Emmanuel Joussein; Marilyne Soubrand; Patrice Fondanèche; Sylvie Rossignol
      Pages: 15 - 26
      Abstract: Publication date: 15 September 2018
      Source:Applied Clay Science, Volume 162
      Author(s): Matthias Monneron-Gyurits, Emmanuel Joussein, Marilyne Soubrand, Patrice Fondanèche, Sylvie Rossignol
      The valorization of oyster or mussel shells toward metakaolin-based geomaterials was investigated. The aim is to better understand the feasibility and the reaction involved during the incorporation of shells (natural or calcined) into a metakaolin-based alkaline solution for potential building or contaminants sorbents applications. Mixtures are realized by (i) the substitution of metakaolin (MK) source by shells raw material (from 0 to 100% mass) or (ii) addition up to 50% mass. Substitution of MK by shells was conducted without material structure loss up to 40% and 30% addition, whether the type and treatment of shells used. In each addition or substitution, the results highlight the duality between both reactions i.e. polycondensation versus hydration. (i) using natural shells, only polycondensation reaction occurs due to the unreactivity of shells (interaction of shells with matrix by surface binding: role of aggregates or fillers); (ii) using calcined shells, coexistence of polycondensation in first followed (or stopped) by hydration reaction: presence of portlandite and C(A)SH. Then the results traduce the role of MK (Al and Si source) reactivity and calcium form (carbonate versus lime; reactivity) in MK-based alkali activated materials. The geochemical leaching approach can be used as a sensitive probe of the structural network.
      Graphical abstract image

      PubDate: 2018-06-01T10:21:57Z
      DOI: 10.1016/j.clay.2018.05.027
      Issue No: Vol. 162 (2018)
  • Soil weathering analysis using a portable X-ray fluorescence (PXRF)
           spectrometer in an Inceptisol from the Brazilian Cerrado
    • Authors: Sérgio Henrique Godinho Silva; Alfred E. Hartemink; Anita Fernanda dos Santos Teixeira; Alberto Vasconcellos Inda; Luiz Roberto Guimarães Guilherme; Nilton Curi
      Pages: 27 - 37
      Abstract: Publication date: 15 September 2018
      Source:Applied Clay Science, Volume 162
      Author(s): Sérgio Henrique Godinho Silva, Alfred E. Hartemink, Anita Fernanda dos Santos Teixeira, Alberto Vasconcellos Inda, Luiz Roberto Guimarães Guilherme, Nilton Curi
      Portable X-ray fluorescence (pXRF) spectrometers allow rapid detection of soil elements and owing to several advantages have been increasingly used in many environmental samples, soils included. This study aimed to: i) evaluate the potential of pXRF for soil profile characterization; ii) use pXRF for investigating soil weathering through elemental contents quantification in sand, silt, and clay fractions; and iii) spatially evaluate elemental composition in the soil profile to assess variation within and between horizons. An Inceptisol from the Brazilian Cerrado was morphologically described and composite samples from the A, B, C, and Cr horizons were collected for physical/chemical characterization. Additional samples were collected from a regular grid (12.5 × 12.5 cm, n = 24) in the soil profile for further analyses with pXRF in the air-dried fine earth (<2 mm), as well as in the sand, silt, and clay fractions, which were also mineralogically characterized by X-ray diffractometry (XRD). Contents of Ca, K, Al, Si, Zn, and Cu decreased with depth. Calcium, K, Ba, Cr, and Rb contents were less abundant in the sand fraction of the Cr horizon, when compared to the A horizon, whereas Si increased from the Cr to A horizon, probably due to the relative residual accumulation of quartz in this fraction in the A horizon, which was supported by XRD analyses. There was a considerable variation of elemental concentrations with depth and within horizons. Elemental composition obtained by pXRF can help in soil genesis studies indicating weathering pathways and is a powerful tool for complementing XRD data. Future studies can evaluate correlations between soil properties and contents of elements that are now easily obtained by pXRF, such as V, Sr, Rb, and Ba.

      PubDate: 2018-06-04T10:36:02Z
      DOI: 10.1016/j.clay.2018.05.028
      Issue No: Vol. 162 (2018)
  • Simultaneous electrochemical sensing of hydroquinone and catechol using
           nanocomposite based on palygorskite and nitrogen doped graphene
    • Authors: Yuting Wu; Wu Lei; Mingzhu Xia; Fengyun Wang; Caiwei Li; Cheng Zhang; Qingli Hao; Yuehua Zhang
      Pages: 38 - 45
      Abstract: Publication date: 15 September 2018
      Source:Applied Clay Science, Volume 162
      Author(s): Yuting Wu, Wu Lei, Mingzhu Xia, Fengyun Wang, Caiwei Li, Cheng Zhang, Qingli Hao, Yuehua Zhang
      A novel electrochemical sensor based on nitrogen doped graphene (NGE) and palygorskite (Pal) for the simultaneous detection of hydroquinone (HQ) and catechol (CT) has been proposed. Pal is particularly pointed out for its appreciable specific surface area and reactive-OH groups on its surface. Acid treatment Pal demonstrated better physico-chemical properties, which are propitious to electrochemical sensor construction. The introduction of NGE not only improved the poor conductivity of Pal but also served as an excellent adherent matrix. The modified electrode demonstrated the enhanced redox peak currents of HQ and CT with good discrimination. Under optimized conditions, the linear ranges for HQ and CT were 2–50 μM and 1–50 μM, with detection limit (LOD) of 0.8 μM and 0.13 μM, respectively. The result designates that the Pal/NGE composite promises to be a new eco-friendly modified material for sensor fabrication.
      Graphical abstract image

      PubDate: 2018-06-04T10:36:02Z
      DOI: 10.1016/j.clay.2018.05.026
      Issue No: Vol. 162 (2018)
  • Effects of drying on Atterberg limits of pyroclastic soils of Northern
    • Authors: Nejan Huvaj; Emre Uyeturk
      Pages: 46 - 56
      Abstract: Publication date: 15 September 2018
      Source:Applied Clay Science, Volume 162
      Author(s): Nejan Huvaj, Emre Uyeturk
      In this study, the effects of drying on Atterberg limits is investigated using 30 soil samples taken from 0.2 m to 4 m depths, from nine different landslide sites in pyroclastic deposits in Northern Turkey. Samples for Atterberg limits are prepared by (i) starting from in-situ moisture content without any drying, (ii) drying at 60 °C and (iii) drying at 110 °C. The range of liquid limit values is 35%–103% and plasticity index is 0%–37% when samples are prepared from their in-situ moisture content. Liquid limits of the samples, when they are prepared by drying at 110 °C oven, are 1%–30% lower than the liquid limits prepared from moist condition. The mineralogy of the samples is investigated via X-ray diffraction analyses and Scanning Electron Microscopy photographs, indicating existence of halloysite mineral. Organic contents of the samples, determined by loss on ignition test, is in the range of 4.3%–12.1%. It is concluded that drying significantly influences the results of Atterberg limits if the sample contains some organic material and/or halloysite mineral. Both liquid limit and plasticity index values of the soils decreased as the sample preparation method changed from moist preparation to drying at 110°C. Existing soil classification methods may fail to represent the influence of organic matter on soil behaviour for soils containing <15% organic material.
      Graphical abstract image

      PubDate: 2018-06-07T10:49:40Z
      DOI: 10.1016/j.clay.2018.05.020
      Issue No: Vol. 162 (2018)
  • The effect of mineralogy of calcined shales on the alkali activation and
           geopolymerization reactions: A case study from Abu-Tartur plateau, Western
           Desert, Egypt
    • Authors: Galal El-Habaak; Mohamed Askalany; Mahmoud Abdel-Hakeem
      Pages: 90 - 100
      Abstract: Publication date: 15 September 2018
      Source:Applied Clay Science, Volume 162
      Author(s): Galal El-Habaak, Mohamed Askalany, Mahmoud Abdel-Hakeem
      The effect of mineralogy of calcined shales on the alkali activation and geopolymerization reactions was studied. Shales under study included black and Dakhla shales, which were obtained from the Abu-Tartur plateau in the Western Desert of Egypt and characterized using optical microscope, SEM, XRF, XRD, and FTIR. The dehydroxylation of shale samples was performed at 550, 650, 750, and 850 °C for one hour. The mineral transformations on calcination were monitored using SEM, XRD and FTIR. The alkali activation process was then conducted on the calcined samples using a mixture of sodium hydroxide and sodium silicate at 1.2 solid/liquid mass ratio. The resultant pasts were molded in steel cubes (50 × 50 × 50mm in diameter) and cured at 70 °C for 48 h. The compressive strength of cured samples was measured to reveal the extent to which the dehydroxylation achieved. The maximum strength values were reported at 4.19 MPa and 2.49 MPa for the calcined black shale and Dakhla shale, respectively. By comparing with literature, the present strength is considered to be too much low. This indicates a deficiency of the dehydroxylation of clay minerals, a little amount of the active amorphous phases, and the dominance of low reactive crystalline phases through the whole range of calcination process.

      PubDate: 2018-06-10T11:22:56Z
      DOI: 10.1016/j.clay.2018.05.025
      Issue No: Vol. 162 (2018)
  • Selective removal of methyl orange and Cr anionic contaminants from mixed
           wastewater by in-situ formation of Zn-Al layered double hydroxides
    • Authors: Zilin Meng; Mi Wu; Yaoyao Yu; Fantao Meng; Aiju Liu; Sridhar Komarneni; Qian Zhang
      Pages: 1 - 5
      Abstract: Publication date: 1 September 2018
      Source:Applied Clay Science, Volume 161
      Author(s): Zilin Meng, Mi Wu, Yaoyao Yu, Fantao Meng, Aiju Liu, Sridhar Komarneni, Qian Zhang
      A one-pot method to remove methyl orange (MO, organic contaminant) and CrO4 2− (Cr, inorganic contaminant) from waste water was developed by forming Zn-Al layered double hydroxides (ZnAl-LDH). By this process, the efficiency of MO or Cr removal was nearly 100% and reached the theoretical maximum of ZnAl-LDH removal capacity. In addition, the mixed contaminants of MO and Cr in wastewater can be separated from each other by controlling the addition of Zn/Al solution using this one-pot method. The molecular arrangement of the immobilized contaminants in the interlayer of LDH and the selective removal mechanism were analyzed by calculated binding energies obtained from molecular simulation.
      Graphical abstract image

      PubDate: 2018-04-15T16:46:33Z
      DOI: 10.1016/j.clay.2018.04.008
      Issue No: Vol. 161 (2018)
  • Sustainable adsorbents formed from by-product of acid activation of
           vermiculite and leached-vermiculite-LDH hybrids for removal of industrial
           dyes and metal cations
    • Authors: Wojciech Stawiński; Agnieszka Węgrzyn; Grzegorz Mordarski; Michał Skiba; Olga Freitas; Sónia Figueiredo
      Pages: 6 - 14
      Abstract: Publication date: 1 September 2018
      Source:Applied Clay Science, Volume 161
      Author(s): Wojciech Stawiński, Agnieszka Węgrzyn, Grzegorz Mordarski, Michał Skiba, Olga Freitas, Sónia Figueiredo
      Hydrotalcite-like layered double hydroxide (LDH) materials were synthesized from liquid waste by-product produced during acid activation of vermiculite (raw (W) and expanded (Ve)), and by combining the waste with the activated mineral, novel hybrid vermiculite-hydrotalcite-like materials were obtained in one-pot synthesis. Batch system adsorption experiments were performed on fresh and calcined (at 450 °C) materials using two anionic dyes (Congo Red - CR, and Reactive Red 184 - R), a cationic dye (Astrazon Red - AR), and Cu2+. Calcination significantly increased the materials' adsorption capacities for all the pollutants. The highest adsorption capacities of the LDH derived from W were 289 ± 2, 137 ± 2, 38.2 ± 0.6 and 64 ± 2 mg g−1, while for the ones derived from Ve were 214 ± 2, 119.5 ± 0.3, 35.9 ± 0.7 and 66 ± 3 mg g−1 for CR, R, AR and Cu2+, respectively. The hybrids obtained from W attained removal levels of 238 ± 3, 111 ± 2, 44 ± 1 and 70 ± 1 mg g−1 and their counterparts derived from Ve reached 84 ± 1, 34.1 ± 0.5, 43 ± 2 and 75 ± 1 mg g−1 for CR, R, AR and Cu2+, respectively. Strong synergic effect on adsorption was observed in the hybrid materials, especially in these derived from Ve. These adsorbents had higher (up to 400%) adsorption capacities than theoretical ones prepared by mixing ex-situ appropriate amounts of activated vermiculite and LDH. All the materials were characterized by XRD, SEM-EDS, and ATR techniques. The proposed procedure is a sustainable approach to clay minerals valorization and my open new possibilities in fields such as wastewater treatment or catalysis.
      Graphical abstract image

      PubDate: 2018-04-15T16:46:33Z
      DOI: 10.1016/j.clay.2018.04.007
      Issue No: Vol. 161 (2018)
  • Bentonite-decorated calix [4] arene: A new, promising hybrid material for
           heavy-metal removal
    • Authors: Khouloud Jlassi; Rym Abidi; Memia Benna; Mohamed M. Chehimi; Peter Kasak; Igor Krupa
      Pages: 15 - 22
      Abstract: Publication date: 1 September 2018
      Source:Applied Clay Science, Volume 161
      Author(s): Khouloud Jlassi, Rym Abidi, Memia Benna, Mohamed M. Chehimi, Peter Kasak, Igor Krupa
      There is global concern about the contamination of ground, river, and tap waters as well as soil contamination with heavy metal ions; these chemical species are known to not degrade and to cause severe health problems if ingested by humans and animals. Such environmental and health concerns necessitate the development of ultrasensitive sensors and high-capacity adsorbents. This study demonstrates for the first time the potential of organophilic bentonite combined with tetra(2-pyridylmethyl)amide calix [4] arene as a high-performance hybrid material for the removal of toxic heavy metals. After consecutive synthesis steps, the modified bentonites were thoroughly characterized by FT-IR, XRD, UV spectroscopy, and TEM. In particular, the XRD analysis showed strong supporting evidence for intercalation in the clay following each modification step. The salient feature of the newly prepared hybrid material is its high extraction capacity for Cd(II) and Zn(II) metals, as determined by atomic absorption spectrometry and UV spectrometry. Different preparation methods, with respect to the quantity of the added cationic surfactant, were investigated to determine the optimal conditions for synthesis. The extraction percentage for the as-prepared hybrid material was measured to be as high as 97.4% and 94.2% for Cd(II) and Zn(II), respectively.

      PubDate: 2018-04-15T16:46:33Z
      DOI: 10.1016/j.clay.2018.04.005
      Issue No: Vol. 161 (2018)
  • Bentonite-layered double hydroxide composite for enhanced aqueous
           adsorption of Eriochrome Black T
    • Authors: Nuhu Dalhat Mu'azu; Nabeel Jarrah; Taye Saheed Kazeem; Mukarram Zubair; Mamdouh Al-Harthi
      Pages: 23 - 34
      Abstract: Publication date: 1 September 2018
      Source:Applied Clay Science, Volume 161
      Author(s): Nuhu Dalhat Mu'azu, Nabeel Jarrah, Taye Saheed Kazeem, Mukarram Zubair, Mamdouh Al-Harthi
      This work reports on layered double hydroxide (LDH) based nanocomposites synthesized via a co-precipitation method with the incorporation of bentonite. The produced bentonite-supported CoAl-LDH (B-CoAl) was employed as an adsorbent for removal of Eriochrome Black T (EBT) dye in aqueous solutions in batch mode experiments. The B-CoAl exhibited superior affinity towards EBT adsorption which yielded significant enhancement of EBT adsorption capacity of up to 675.67 mg/g from 361.01 mg/g of its parent material (i.e., CoAl). Pseudo second-order models (R2 = 0.998–0.999) describe the kinetics of adsorption of EBT while the adsorption mechanism was controlled by external mass transfer as well as intra-particle diffusion. A Freundlich isotherm model provided a better fit of the B-CoAl EBT adsorption data than a Langmuir isotherm model, indicating a multi-layered adsorption phenomenon. The thermodynamic analysis showed that EBT adsorption onto B-CoAl was spontaneous and exothermic in nature. The improved adsorption affinity of EBT removal onto the B-CoAl is attributed to multiple adsorption interaction mechanisms dominated by electrostatic, surface adsorption and chemical interaction between EBT molecules with the additional oxygen-containing functional groups on the B-CoAl composite. This study demonstrates the potentials of environmental applications of bentonite supported LDH as a promising adsorbent removal of organic contaminants from aqueous solutions.
      Graphical abstract image

      PubDate: 2018-04-15T16:46:33Z
      DOI: 10.1016/j.clay.2018.04.009
      Issue No: Vol. 161 (2018)
  • Effect of combinations of nanofillers on rheology-structure relations in
           biodegradable poly(ε-caprolactone) nanocomposites
    • Authors: Boubkeur Seddik Bouakaz; Abderrahmane Habi; Yves Grohens; Isabelle Pillin
      Pages: 35 - 47
      Abstract: Publication date: 1 September 2018
      Source:Applied Clay Science, Volume 161
      Author(s): Boubkeur Seddik Bouakaz, Abderrahmane Habi, Yves Grohens, Isabelle Pillin
      In this work, binary and ternary nanocomposites based on biodegradable polycaprolactone (PCL) reinforced with organo-modified montmorillonites (OMt), epoxy-functionalized graphene (Gr) and their mixtures (OMt/Gr) were prepared using the melt blending process. Two kinds of organoclays having different surfactants were introduced within the matrix, Cloisite® 15A (non-polar) and Cloisite® 30B (polar). In order to study the effect of nanofillers on the matrix properties, rheological tests, morphological, barrier and thermal characterizations were carried out on the hybrid materials. The viscoelastic behavior of PCL based materials was studied using time sweep, amplitude sweep, and frequency sweep tests. The storage modulus of the matrix was improved by adding OMt, and it was further enhanced when OMt is coupled with graphene, especially in the case of the C15A/Gr pair. All the rheological parameters showed that ternary OMt/Gr-PCL mixtures exhibited more pseudo-solid like behavior than binary nanocomposites, reflecting the formation of three-dimensional networks and better distribution of OMt/Gr pairs in the PCL matrix. TEM micrographs confirmed the formation of nanocomposite materials in the case of OMt-PCL and OMt/Gr-PCL. The incorporation of fillers into the biodegradable PCL matrix was significantly improved its permeability toward water vapors. This property is substantially related to the dispersion where a high barrier effect is recorded for ternary OMt/Gr-PCL nanocomposites. The thermal stability of the PCL matrix is affected in the presence of organoclays and/or epoxy-functionalized graphene, giving rise to more thermally stable materials. All the results confirmed that the combination of two nanofillers leads to interesting materials for some applications such as packaging.
      Graphical abstract image

      PubDate: 2018-04-15T16:46:33Z
      DOI: 10.1016/j.clay.2018.04.006
      Issue No: Vol. 161 (2018)
  • Gemini surfactant modified clays: Effect of surfactant loading and spacer
    • Authors: Khadidja Taleb; Isabelle Pillin; Yves Grohens; Salima Saidi-Besbes
      Pages: 48 - 56
      Abstract: Publication date: 1 September 2018
      Source:Applied Clay Science, Volume 161
      Author(s): Khadidja Taleb, Isabelle Pillin, Yves Grohens, Salima Saidi-Besbes
      Aromatic-containing gemini ammonium bromide surfactants with different spacer length and variable amounts were used to modify Na+-montmorillonite via ion exchange reaction. The resulting organoclays (OMt) were characterized in terms of composition and morphology using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The thermal stability of OMt was determined by thermogravimetric analysis (TGA). The results indicated that gemini surfactants exhibit a good efficiency to modify clay mineral. Surfactant concentration and the length of the spacer connecting the ammonium heads were found to be key parameters governing the thermal stability and the structure of the corresponding OMt. Increasing surfactant concentration and lengthening of the spacer act favorably for the achievement of higher expended interlayer clay structures with better thermal stability. Different configurations of surfactant molecules within Mt interlayers were proposed based on d(001) basal spacing.
      Graphical abstract image

      PubDate: 2018-04-15T16:46:33Z
      DOI: 10.1016/j.clay.2018.03.015
      Issue No: Vol. 161 (2018)
  • What is clay' A new definition of “clay” based on plasticity and
           its impact on the most widespread soil classification systems
    • Authors: José Manuel Moreno-Maroto; Jacinto Alonso-Azcárate
      Pages: 57 - 63
      Abstract: Publication date: 1 September 2018
      Source:Applied Clay Science, Volume 161
      Author(s): José Manuel Moreno-Maroto, Jacinto Alonso-Azcárate
      Clays are key elements not only in geological and environmental processes, but also in many human activities. To differentiate clays from other soils, AIPEA and CMS highlight plasticity as the clays' most distinctive characteristic. However, the lack of any reliable plasticity yardstick makes the particle-size-criteria to be more widespread. In a previous work, the authors found some innovative ratios between the plasticity index (PI) and the liquid limit (LL) which allowed the clays' boundary to be established according to a plasticity basis. As plasticity is directly associated with toughness, different published data containing valuable information have been processed in this study by plotting toughness values against PI/LL ratios. In this way, the soundness of the previous authors' finding has been checked. It is demonstrated that a fine-grained material can be defined as a clay when PI ≥ LL/2, while a material is moderately or slightly clayey if LL/3 < PI < LL/2, such that when PI ≤ LL/3 the influence of clay minerals is much reduced. Apart from an updated classification of soil for engineering purposes, a new textural soil classification is presented, alternative to the USDA one, which allows the real nature of a soil to be known accurately by means of plasticity tests and simple sieving instead of particle-size sedimentation methods.

      PubDate: 2018-05-29T09:57:09Z
      DOI: 10.1016/j.clay.2018.04.011
      Issue No: Vol. 161 (2018)
  • Experimental study on fluid properties of slurry and its influence on
           slurry infiltration in sand stratum
    • Authors: Fanlu Min; Hangbiao Song; Nan Zhang
      Pages: 64 - 69
      Abstract: Publication date: 1 September 2018
      Source:Applied Clay Science, Volume 161
      Author(s): Fanlu Min, Hangbiao Song, Nan Zhang
      In construction of slurry engineering, especially in sand stratum of high permeability, small size fine particles in slurry are likely to flow through the stratum and washed away. In this study, nine groups of slurry fluid property tests were performed using a NXS-11A rotary viscometer in order to investigate infiltration of slurry in sand stratum. Additionally, a series of penetration tests were also conducted by a self-designed infiltration device. Experimental results show the test slurry meet characteristics of Bingham fluid at a medium to high shear rate, while it conforms to the Herschel-Bulkley model at a low shear rate. Darcy's law is no longer applicable to infiltration of slurry in sand stratum, because of the initial hydraulic gradient. The infiltration rate (v s ) is not strictly linearly related to the hydraulic gradient at small hydraulic gradient (i). It is also indicated that the yield stress of slurry is the fundamental cause of initial hydraulic gradient during the infiltration process of slurry in sand stratum. The yield stress has a positive correlation with the initial hydraulic gradient. Ideally, initial hydraulic gradient is proportional to the dynamic shear force of slurry.

      PubDate: 2018-05-29T09:57:09Z
      DOI: 10.1016/j.clay.2018.03.028
      Issue No: Vol. 161 (2018)
  • Clay particle charging in apolar media
    • Authors: Benjamin S. Ponto; John C. Berg
      Pages: 76 - 81
      Abstract: Publication date: 1 September 2018
      Source:Applied Clay Science, Volume 161
      Author(s): Benjamin S. Ponto, John C. Berg
      Advancements in electrophoretic displays (e.g., the Amazon Kindle®) and new high-quality printing technologies (e.g., HP Indigo®) have been made possible by the ability to control and understand particle charging in apolar media. While previous work has investigated the acid-base charging mechanisms of oxides and similar particles which have only one charging mechanism in water, the purpose of this study was to determine if and how clay particles, which have two known aqueous charging mechanisms, charge in apolar media. Characterization of kaolinite and montmorillonite surface charging properties and mechanisms were conducted in apolar media utilizing different surfactants. It was found that clay particle charging behavior as a function of surfactant concentration mimicked the expected trend of previously studied oxides, which can charge only via an acid-base mechanism. Furthermore, by comparing the point of zero charge of the edge groups (edge PZC) or the point of zero net proton charge (PZNPC) of the clay particle to the empirical effective pH (pHEff) of the surfactant, the polarity of the particle charge can be predicted. In addition to particle charging, it was shown that the surfactants also improve the stability against aggregation and settling of the particles.

      PubDate: 2018-05-29T09:57:09Z
      DOI: 10.1016/j.clay.2018.04.016
      Issue No: Vol. 161 (2018)
  • Red-clay ceramic powders as geopolymer precursors: Consideration of
           amorphous portion and CaO content
    • Authors: Martin Keppert; Eva Vejmelková; Petr Bezdička; Magdaléna Doleželová; Monika Čáchová; Lenka Scheinherrová; Jaroslav Pokorný; Martin Vyšvařil; Pavla Rovnaníková; Robert Černý
      Pages: 82 - 89
      Abstract: Publication date: 1 September 2018
      Source:Applied Clay Science, Volume 161
      Author(s): Martin Keppert, Eva Vejmelková, Petr Bezdička, Magdaléna Doleželová, Monika Čáchová, Lenka Scheinherrová, Jaroslav Pokorný, Martin Vyšvařil, Pavla Rovnaníková, Robert Černý
      Geopolymers are conventionally prepared from metakaolin, fly ash, or blast furnace slag. In this paper, geopolymer synthesis using two different red-clay ceramic powders and a varying amount of Na2O/SiO2 activator is presented. Experimental results show that despite of the high content of crystalline minerals and lower concentration of amorphous matter, both tested precursors enable to prepare geopolymers with satisfactory mechanical properties. The discussion of measured values of compressive strength with respect to SiO2/Al2O3 and Al2O3/(Na2O + K2O) ratios in the prepared geopolymer mixes reveals that the consideration of only amorphous portion of ceramics is appropriate. A higher content of CaO in the precursor is found to cause a broader pore size distribution and higher porosity of resulting geopolymers, which is due to the formation of calcium silicate hydrates.

      PubDate: 2018-05-29T09:57:09Z
      DOI: 10.1016/j.clay.2018.04.019
      Issue No: Vol. 161 (2018)
  • Morphology, rheology and thermal stability of drilling fluid formulated
           from locally beneficiated clays of Pindiga Formation, Northeastern Nigeria
    • Authors: A.S. Arabi; B.B.M. Dewu; I.I. Funtua; M.O.A. Oladipo; M. Tukur; S. Bilal; E. Kurowska; S.A. Kasim; A.A. Yakasai; S.I. Babale
      Pages: 90 - 102
      Abstract: Publication date: 1 September 2018
      Source:Applied Clay Science, Volume 161
      Author(s): A.S. Arabi, B.B.M. Dewu, I.I. Funtua, M.O.A. Oladipo, M. Tukur, S. Bilal, E. Kurowska, S.A. Kasim, A.A. Yakasai, S.I. Babale
      Locally beneficiated clays from Pindiga Formation in Northeastern Nigeria have been found to attain standard rheological properties required for Oil and Gas Well drilling after addition of some percentages of poly anionic cellulose. But these properties were measured under ambient temperature (32 °C). There is the need therefore to ascertain the performance of these beneficiated clays at field/down-hole conditions (high temperature and pressure). In this study, three of these clays labeled GHZ, PNG and SGN were chosen because of their high rheological performance among others as already reported in our earlier work, formulated and subjected to different temperature (ambient (32 °C), 40 °C, 50 °C, 60 °C, 70 °C and 80 °C) together with API grade bentonite. At each temperature, their rheological properties were computed to ascertain their performance under these conditions. Physical and other properties (Loss On Ignition, Specific Gravity, Particle Size Distribution, Textural Classification and Formulated CEC) of the sample were also determined and compared with API grade sample. The results obtained indicated that formulation using samples beneficiated with 12% Na2CO3 had viscosity values (cP) that ranges from of 2.0–7.9 at temperature ranging from 30 °C to 80 °C with sample PNG recording the highest values of 7.9 cP at 50 °C. For the API grade sample, these values (cP) range from 4.5–16 with highest value recorded at 70 °C. Viscosity results for formulation using same beneficiated sample but with addition of 0.8 and 1.5 g poly anionic cellulose indicated that formulation with 0.8 g poly anionic cellulose had the most impressive improvement among other formulations. The results recorded ranged from 1.0–44 cP with sample PNG recording the highest viscosity of 44 cP at 70 °C. When the Apparent Viscosity (AV), Plastic Viscosity (PV) and Yield Points (YP) of the samples were computed, the results also indicates that sample PNG had the highest values for these parameters compared with the API grade. Other parameters (Loss On Ignition, Specific Gravity, Particle Size Distribution, Textural Classification and Formulated Cation Exchange Capacity) determined had values/behaviors comparable with standard specifications. Thermal stability results indicated that as it is with viscosities of the different formulations at ambient temperature, sample PNG could possibly give a better result (behavior at the measurement conditions) compared with the others even at down-hole conditions and can favorably compete with even the API grade. But at temperatures greater than seventy degrees (70 °C), the performance of both the API grade and the locally beneficiated and formulated drilling fluids began todeteriorate (fail) sharply.

      PubDate: 2018-05-29T09:57:09Z
      DOI: 10.1016/j.clay.2018.03.034
      Issue No: Vol. 161 (2018)
  • Improvement in phase purity and yield of hydrothermally synthesized
           smectite using Taguchi method
    • Authors: Bing-Sheng Yu; Yi-Yu Liu
      Pages: 103 - 109
      Abstract: Publication date: 1 September 2018
      Source:Applied Clay Science, Volume 161
      Author(s): Bing-Sheng Yu, Yi-Yu Liu
      Smectite is widely used in many industrial fields and material applications. Although the high phase purity and yield of synthetic smectite are paramount for advanced applications, few studies have investigated these aspects. In this work, the phase purity and yield of synthetic smectite were estimated for the first time using a quantitative phase analysis through X-ray diffraction and Rietveld method software. The Taguchi method was used to optimize the phase purity and yield of synthetic smectite, and the effects of synthesis factors are discussed. Based on the trioctahedral smectite formula Na2x(Al2(1-x)Mg2x□)Si4O10(OH)2, an Na2O-MgO-Al2O3-SiO2-H2O system was used for smectite synthesis at temperatures of 200 °C and 220 °C, for durations of 48–96 h and pH values of 7, 9, and 11. The results indicate that the duration, starting material, and type of mineralizer are the three most important factors affecting the phase purity and yield of synthetic smectite. For the synthesis conditions optimized by the Taguchi method in this study, the phase purity and yield of the synthetic smectite can reach up to 92.5% and 88.3%, respectively. These results can contribute to an improved understanding of the factors that control the phase purity and yield of synthetic smectite and provide an efficient method for the synthesis of high-quality smectite for advanced applications.

      PubDate: 2018-05-29T09:57:09Z
      DOI: 10.1016/j.clay.2018.04.001
      Issue No: Vol. 161 (2018)
  • Assessment of the suitability of gravel wash mud as raw material for the
           synthesis of an alkali-activated binder
    • Authors: Vishojit Bahadur Thapa; Danièle Waldmann; Jean-Frank Wagner; André Lecomte
      Pages: 110 - 118
      Abstract: Publication date: 1 September 2018
      Source:Applied Clay Science, Volume 161
      Author(s): Vishojit Bahadur Thapa, Danièle Waldmann, Jean-Frank Wagner, André Lecomte
      Gravel wash mud (GWM), a waste product from gravel mining was dried and processed into a fine powder to be activated by different concentrations of sodium hydroxide (NaOH) solutions for the synthesis of an alkali-activated binder. The GWM powders were thermally treated at five different calcination temperatures 550, 650, 750, 850 and 950 °C. The characterisation of the raw material comprises the particle size distribution (PSD) by laser granulometry, the chemical and mineralogical composition by X-ray fluorescence and X-ray diffraction analysis respectively, and simultaneous thermal analysis. The performance of the alkali-activated binders was examined using compression strength tests and the microstructure was observed using scanning electron microscopy (SEM). The GWM was classified as an aluminosilicate raw material with kaolinite and illite as main clay minerals. Furthermore, a mean particle size around 6.50 μm was determined for the uncalcined and calcined GWM powders. The SEM images of the developed binders showed the formation of a compact microstructure, however, relatively low strengths were achieved. This preliminary study highlights an example of an aluminosilicate prime material, which shows very promising chemical and mineralogical characteristics, but its suitability for alkaline activation without further additives was not confirmed as far as performance-based criteria are considered.

      PubDate: 2018-05-29T09:57:09Z
      DOI: 10.1016/j.clay.2018.04.025
      Issue No: Vol. 161 (2018)
  • Mineral carbonation of ceramic brick at low pressure and room temperature.
           A simulation study for a superficial CO2 store using a common clay as
           sealing material
    • Authors: Domingo Martín; Patricia Aparicio; Emilio Galán
      Pages: 119 - 126
      Abstract: Publication date: 1 September 2018
      Source:Applied Clay Science, Volume 161
      Author(s): Domingo Martín, Patricia Aparicio, Emilio Galán
      This research explores the possibilities of CO2 sequestration on ceramic bricks in a short time and at surface conditions. The experiment was carried out in a specially designed reaction chamber, filled with brick wastes and sealed with common clays. The brick used were composed of quartz, wollastonite, diopside, orthoclase and anhydrite, and the common clay was a marl composed of calcite, quartz, illite, smectite and kaolinite. Experimental condition in the reaction chamber were: reaction time 5 months, pressure of CO2 0.5 bar, 4:1 solid/water ratio. The experiment was followed by XRD, XRF, BET, physical sorption by N2 and CO2, Hg porosity, TG-DTA, SEM and ICP-EOS. After the CO2 treatment, wollastonite and anhydrite were practically destroyed and some diopside and orthoclase. Calcite precipitated as new phase (up to 48 wt%), and small amount of illite was the result of orthoclase alteration. Concerning the sealing clay, the CO2 produced an increment of calcite content (from 32 to 41 wt%) and a partial destruction of smectite, particularly close to the upper part of the brick layer. These results are hopeful in relation with the possible mineral carbonation of building ceramic waste in a short time at surface conditions, and open the opportunity to use those wastes for CO2 trapping in an appropriate system, as a quarry reclamation.

      PubDate: 2018-05-29T09:57:09Z
      DOI: 10.1016/j.clay.2018.04.021
      Issue No: Vol. 161 (2018)
  • Cathodo- and photoluminescence emission of a natural Mg-Cr carbonate
           layered double hydroxide
    • Authors: V. Correcher; J. Garcia-Guinea
      Pages: 127 - 131
      Abstract: Publication date: 1 September 2018
      Source:Applied Clay Science, Volume 161
      Author(s): V. Correcher, J. Garcia-Guinea
      Spectral emission of a natural layered double hydroxide (LDH) studied by cathodo- and photoluminescence (PL), displays complex glow curves with wavebands that could be attributable to (i) the paramagnetic Non-bridging Oxygen Hole Center defects (peaked at 330 nm), (ii) Fo centers (oxygen vacancies trapping two electrons) associated with O vacancy-hole centers and Me–O bonding defects and dehydroxylation process (in the range of 360–500 nm), (iii) presence of Mn2+ (0.15%) substituting Mg2+ ions (530–640 nm) and (iv) a red-IR band mainly associated with Cr and Fe point defects. The presence of Cr3+ ion activators induces characteristic PL emission peaks in the red-infrared region at 681, 688 and 696 nm linked to 2E → 4A2 transitions. The sample (Mg6Cr2CO3(OH)16·4H2O) previously characterized by environmental scanning electron microscope, X-ray diffraction, and X-ray fluorescence indicates that this natural hydrotalcite-like compound is associated with hydroxyl-rich silicates (nimite and clinochlore) and Mg-Fe carbonate and Ni-Fe carbonate LDH (pyroaurite and reevesite).

      PubDate: 2018-05-29T09:57:09Z
      DOI: 10.1016/j.clay.2018.04.022
      Issue No: Vol. 161 (2018)
  • Sepiolite-carbon nanocomposites doped with Pd as improving catalysts for
           hydrodechlorination processes
    • Authors: Cristina Ruiz-García; Francisco Heras; Miguel Ángel Gilarranz; Pilar Aranda; Eduardo Ruiz-Hitzky
      Pages: 132 - 138
      Abstract: Publication date: 1 September 2018
      Source:Applied Clay Science, Volume 161
      Author(s): Cristina Ruiz-García, Francisco Heras, Miguel Ángel Gilarranz, Pilar Aranda, Eduardo Ruiz-Hitzky
      The present work introduces a new type of improved catalysts based on sepiolite-carbon nanocomposites anchoring Pd nanoparticles. The nanocomposites are prepared by assembly in aqueous media of graphene nanoplatelets (GNP) and the nanofibrous sepiolite under a sonomechanical treatment. The methodology allows the co-assembly of other nanomaterials such as multiwall carbon nanotubes (MWCNT) and Pd nanoparticles, these last ones in situ generated from PdCl2 and further treatment with NaBH4. The presence of silanol groups at the external surface of sepiolite favors the growth and assembly of Pd NP which exhibit a quite narrow size distribution independently of the composition of the prepared sepiolite-carbon nanocomposite. The electrical conductivity of the prepared sepiolite-carbon/Pd materials depends of the composition, being lower in materials with higher content in sepiolite. However, the presence of the clay mineral improves textural properties of the resulting materials. The prepared sepiolite-carbon/Pd nanocomposites were tested as catalysts in the hydrodechlorination (HDC) of 4-chlorophenol (4-CPh) under H2 flux, showing all of them an exclusive selectivity towards phenol, though their catalytic activity depends on their composition. Sepiolite is able to neutralize the evolved HCl, favoring the catalytic process. In addition, the good balance between textural and electrical properties achieved in some of the prepared materials enhances the contact between the catalyst surface and the reagents and also favors the electronic transfer, making this new type of sepiolite-carbon/Pd systems very promising. In fact, the concept here reported could be extended to other catalytic applications where the supported metal acting as active center requires the presence of heat and water resistant conductive supports.
      Graphical abstract image

      PubDate: 2018-05-29T09:57:09Z
      DOI: 10.1016/j.clay.2018.04.004
      Issue No: Vol. 161 (2018)
  • Vermiculite as a potential component of the engineered barriers in low-
           and medium-level radioactive waste repositories
    • Authors: L. Fuks; I. Herdzik-Koniecko
      Pages: 139 - 150
      Abstract: Publication date: 1 September 2018
      Source:Applied Clay Science, Volume 161
      Author(s): L. Fuks, I. Herdzik-Koniecko
      Vermiculite (VMT) was tested as a low-cost, eco-friendly adsorbent for the removal of cesium(I), strontium(II), europium(III), americium(III), and technetium(VII) radionuclides from aqueous solutions. The raw material was characterized and checked as potential adsorbent. The removal efficiency (Er, %) was studied as a function of the main factors important for the management of radioactive liquid wastes. It was found that the uptake from the aqueous solutions simulating the radioactive liquid wastes was in the order: Cs(I) ̴ Sr(II) (both about 95%) > Am(III) (about 90%) > Eu(III) (about 80%). When a reducing agent is added to the solution technetium-99 may also be completely removed. The usefulness of VMT in liquid low level radioactive waste management has also been confirmed by checking its radiation stability. Vermiculite can be considered as a promising material for sorption of the radionuclides from radioactive waste solutions and as a potential additive to the engineered barriers in LLRW repositories.
      Graphical abstract image

      PubDate: 2018-05-29T09:57:09Z
      DOI: 10.1016/j.clay.2018.04.010
      Issue No: Vol. 161 (2018)
  • Potential use of the lower cretaceous clay (Kef area, Northwestern
           Tunisia) as raw material to supply ceramic industry
    • Authors: Imed Ben Salah; Ali Sdiri; Moufida Ben M'barek Jemai; Mabrouk Boughdiri
      Pages: 151 - 162
      Abstract: Publication date: 1 September 2018
      Source:Applied Clay Science, Volume 161
      Author(s): Imed Ben Salah, Ali Sdiri, Moufida Ben M'barek Jemai, Mabrouk Boughdiri
      The aim of this study is to evaluate the potential use of clay deposits from northern Tunisia (Albian system) for the manufacture of bricks and ceramic tiles. Clay samples were collected from the Slata study site to the north of the Kef district, Tunisia. Chemical composition by atomic absorption spectrometry (AAS) showed that these clays were mainly composed of silica (33%), alumina (15%), iron oxide (6%) and minor amount of potassium oxide (3%). Mineralogical analysis by X-ray diffraction (XRD) confirmed the results of AAS; it showed reflections of quartz, calcite, kaolinite (65–70%) and illite (15%) associated with low percentage of interstratified illite-smectite (5%). After firing near 900 °C, new mineralogical species such as mullite, anortite and spinel appeared due to several temperature-dependent transformations. Further analysis indicated that plasticity index (PI) ranged between 16 and 20%. Geotechnical and thermal tests have shown acceptable values of drying shrinkage (3%), firing shrinkage (10%), water absorption (8.9–15.9%) and a very high mechanical bending strength (17–20 MPa) indicating non-refractory clays. Those results further confirmed the potential application of the Albian clays from Slata site in ceramics.

      PubDate: 2018-05-29T09:57:09Z
      DOI: 10.1016/j.clay.2018.04.015
      Issue No: Vol. 161 (2018)
  • Joint synthesis of Zeolite A-LDH from mineral industry waste
    • Authors: Liliane Nogueira da Silva; Dorsan dos Santos Moraes; Suzianny Cristina Arimatéa Santos; José Augusto Martins Corrêa
      Pages: 163 - 168
      Abstract: Publication date: 1 September 2018
      Source:Applied Clay Science, Volume 161
      Author(s): Liliane Nogueira da Silva, Dorsan dos Santos Moraes, Suzianny Cristina Arimatéa Santos, José Augusto Martins Corrêa
      This study evaluated the use of waste from the copper concentration process and kaolin processing for the combined synthesis of Zeolite A and layered double hydroxide (LDH). The synthesis occurred in two stages: synthesis of LDH by coprecipitation and submersion in a hydrothermal bath and then the addition of metakaolin for the synthesis of Zeolite A. The synthesized ZA-LDH sample was characterized by X-ray diffraction (XRD), scanning electron microscopy coupled with X-ray energy dispersive spectroscopy (SEM-EDS), N2 physisorption and point of zero charge (PZC). X-ray diffraction detected phases of high structural order, quantified by the Rietveld method in 90.57 Zeolite A, 9.21 pyroaurite and 0.22 anatase (% mass). In adsorption tests, the ZA-LDH showed greater efficiency in dye removal than commercial zeolite.
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      PubDate: 2018-05-29T09:57:09Z
      DOI: 10.1016/j.clay.2018.04.018
      Issue No: Vol. 161 (2018)
  • The preferential retention of VIZn over IVZn on birnessite during
    • Authors: Zhangjie Qin; Hui Yin; Xiaoming Wang; Qin Zhang; Shuai Lan; Luuk K. Koopal; Lirong Zheng; Xionghan Feng; Fan Liu
      Pages: 169 - 175
      Abstract: Publication date: 1 September 2018
      Source:Applied Clay Science, Volume 161
      Author(s): Zhangjie Qin, Hui Yin, Xiaoming Wang, Qin Zhang, Shuai Lan, Luuk K. Koopal, Lirong Zheng, Xionghan Feng, Fan Liu
      Zn is a common heavy metal in soils and sediments. In this study, the release behaviors of octahedral (VIZn) and tetrahedral (IVZn) Zn complexes on synthesized hexagonal birnessite were explored by solution chemistry method in combination with spectroscopic analysis. In acidic dissolution processes, the release of adsorbed Zn2+ from birnessite occurred into two stages: in the first stage, ~60% of Zn2+ was desorbed rapidly, with only 8% of Mn being released, and the ratio of VIZn/IVZn increased with time; in the second stage, the residual Zn2+ was mostly VIZn and released slowly at a nearly constant rate until complete dissolution of the matrix mineral was observed. During desorption of Zn2+ by Pb2+, the ratio of VIZn/IVZn on birnessite also increased, while the residual percentage of VIZn remained nearly constant. However, it is known that IVZn-triple corner-sharing (TCS) is more stable than VIZn-TCS, suggesting that part of the remaining IVZn-TCS on birnessite might transform to VIZn-TCS immediately when VIZn-TCS is replaced by H+ or Pb2+. Additionally, the possible distribution of Mn3+ and IVZn or the partial charge compensation by protons can lead to the preferential retention of VIZn on birnessite or the preferential re-adsorption of VIZn at the new edge sites. These results can provide new insights into the geochemical behavior of Zn2+ contaminant in soil and aquatic environments.
      Graphical abstract image

      PubDate: 2018-05-29T09:57:09Z
      DOI: 10.1016/j.clay.2018.04.017
      Issue No: Vol. 161 (2018)
  • Mineralogical evolution of ceramic clays during heating. An ex/in situ
           X-ray diffraction method comparison study
    • Authors: Adolfo Miras; Emilio Galán; Isabel González; Antonio Romero-Baena; Domingo Martín
      Pages: 176 - 183
      Abstract: Publication date: 1 September 2018
      Source:Applied Clay Science, Volume 161
      Author(s): Adolfo Miras, Emilio Galán, Isabel González, Antonio Romero-Baena, Domingo Martín
      The ceramic properties of clay materials heated at high temperature are largely dependent on the mineral reactions, which usually are followed by XRD analysis on pressed pieces that are heated at different temperatures. Nevertheless, the use of “in-situ” high temperature X-ray diffraction (HTXRD) to follow the evolution of the crystalline phases under controlled temperature provides more precision. In this paper, the mineralogical changes produced during firing (RT-1000 °C) of two clay materials of very different mineralogical composition, frequently used in the manufacture of bricks in the SE Spain, have been studied by XRD classical procedure and with HTXRD, and the results obtained were compared. Although the phases identified by both X-ray analyses were the same, temperatures for the mineralogical reactions seem to be different, probably due to the experimental conditions. The patterns obtained by ex-situ XRD were at a higher speed than those by in-situ HTXRD, and probably the equilibrium was not achieved for the most reactions. Because of the expansion of the mineral structure parameters occurred during heating the mineral reflections do not match with those found in the database JPCDS, neither the position nor intensities of some stable phases at high temperature. For the optimization of the interpretation of the HTXRD patterns, and to facilitate the kinetics of the new phases, it is necessary to work at a high integration time per step and a slow heating rate. The in-situ HTXRD investigations of ceramic materials can save time respect to the classical XRD study of test-pieces heated at different temperatures, and lead immediate information of the transformation occurring on heating, which can be useful to improve the most suitable firing temperature in the industry.

      PubDate: 2018-05-29T09:57:09Z
      DOI: 10.1016/j.clay.2018.04.003
      Issue No: Vol. 161 (2018)
  • Study on the performance of metakaolin based geopolymer for Mn(II) and
           Co(II) removal
    • Authors: Ilknur Kara; Dilek Tunc; Fatih Sayin; Sibel Tunali Akar
      Pages: 184 - 193
      Abstract: Publication date: 1 September 2018
      Source:Applied Clay Science, Volume 161
      Author(s): Ilknur Kara, Dilek Tunc, Fatih Sayin, Sibel Tunali Akar
      The aim of this study is to remove heavy metals ions of Mn(II) and Co(II) from aqueous solutions by using metakaolin based geopolymer, a new potential low-cost alternative adsorbent material. The parameters of initial pH, adsorbent amount, time of contact and initial metal ion concentration on the metal removal performance were studied using a batch method at 30 °C. It was found that the Langmuir isotherm described the adsorption data very well and the maximum monolayer adsorption capacities were found to be 72.34 mg g−1 (1.32 × 10−3 mol g−1) and 69.23 mg g−1 (1.18 × 10−3 mol g−1) for Mn(II) and Co(II), respectively. The kinetic studies showed that adsorption of Mn(II) and Co(II) followed the pseudo-second-order kinetic model. Adsorption yield was found to be slightly sensitive to temperature and ionic strength and no pH adjustment was necessary to get high adsorption yield. High metal ion adsorption performance in both batch and continuous systems is an important indicative of geopolymer efficiency. Ion exchange appears to be an effective mechanism for the metal ion adsorption onto geopolymer. It is concluded that Mn(II) and Co(II) ions are efficiently removed from aqueous solutions by metakaolin based geopolymer which could be employed as a low-cost and excellent alternative for wastewater treatment.

      PubDate: 2018-05-29T09:57:09Z
      DOI: 10.1016/j.clay.2018.04.027
      Issue No: Vol. 161 (2018)
  • Fabrication of reusable temperature-controlled-released fertilizer using a
           palygorskite-based magnetic nanocomposite
    • Authors: Yu Chi; Guilong Zhang; Yubin Xiang; Dongqing Cai; Zhengyan Wu
      Pages: 194 - 202
      Abstract: Publication date: 1 September 2018
      Source:Applied Clay Science, Volume 161
      Author(s): Yu Chi, Guilong Zhang, Yubin Xiang, Dongqing Cai, Zhengyan Wu
      In this work, a temperature-controlled-release and collectable iron fertilizer (TCIF) with a core-shell structure was developed using a nanocomposite consisting of palygorskite (Pal), ferroferric oxide (Fe3O4), ferrous ammonium sulfate hexahydrate (FASH), ethylene oxide/propylene oxide block copolymer (F-127), and amino silicon oil (ASO). Therein, the core was made up of Pal-Fe3O4-FASH mixture, and the shell was composed of ASO-F-127. Pal with a porous micro/nano networks structure could bind a great many of Fe2+ through electrostatic attraction. FASH, as the iron fertilizer and a foaming agent in this system, can produce NH3 at 100 °C to make a plenty of micro/nano pores in the ASO-F-127 shell, which facilitated the release of Fe2+. F-127, a thermally sensitive polymer, can open and close the pores through the liquid-gel transition under different temperature to adjust the release of Fe2+. The hydrophobic ASO endowed TCIF a high stability in aqueous solution for at least 100 days. Fe3O4 made TCIF own a relatively high magnetism so that TCIF could be conveniently collected from water and soil. Significantly, this technology could improve the utilization efficiency of iron fertilizer and promote the absorption of Fe2+ by maize. Besides, TCIF displayed a good reuse performance, which could favor to lower the cost and decrease the residual.
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      PubDate: 2018-05-29T09:57:09Z
      DOI: 10.1016/j.clay.2018.04.024
      Issue No: Vol. 161 (2018)
  • Incorporation of waste from ferromanganese alloy manufacture and soapstone
           powder in red ceramic production
    • Authors: T.G. Cota; E.L. Reis; R.M.F. Lima; R.A.S. Cipriano
      Pages: 274 - 281
      Abstract: Publication date: 1 September 2018
      Source:Applied Clay Science, Volume 161
      Author(s): T.G. Cota, E.L. Reis, R.M.F. Lima, R.A.S. Cipriano
      The production of waste from the mining-metallurgical sector is one of the factors of environmental contamination and exploring ways to reuse this waste have attracted considerable research attention. This study proposes the use of residues generated from the manufacturing processes of ferromanganese alloy and soapstone powder for the production of red ceramic. Ceramic bricks were prepared with clay and sludge to investigate the effect of a number of variables, including the replacement of clay with sludge (5% and 10%), compaction pressure (14 and 28 MPa), and firing temperature (850 °C and 1000 °C) on the linear shrinkage, water absorption, firing specific weight, and compressive strength of the bricks. Also tests were carried out with replacement of part of the clay mass by sludge and steatite in the same brick. The best condition for ceramic production was found to be a firing temperature of 1000 °C and compaction pressure of 28 MPa with 5% of clay replaced by sludge. The best results were obtained for bricks with clay replaced by both sludge and steatite, which prompted the formation of the new crystalline phases, spinel and enstatite. After analysis, the brick residue was classified as Non Hazardous and Not Inert. The analyzed parameters were within the established limits for technological applications.

      PubDate: 2018-05-29T09:57:09Z
      DOI: 10.1016/j.clay.2018.04.034
      Issue No: Vol. 161 (2018)
  • Optimal fabrication of carbonate free kaolin based low cost ceramic
           membranes using mixture model response surface methodology
    • Abstract: Publication date: 15 September 2018
      Source:Applied Clay Science, Volume 162
      Author(s): Sushma Chakraborty, Ramagopal Uppaluri, Chandan Das
      This article aims to address the relevance of D-optimal mixture model based RSM design methodology for the optimal fabrication of carbonate free low cost ceramic membranes. The RSM design methodology was validated by targeting alterations in the composition of kaolin, feldspar and saw dust precursors during low cost ceramic membrane fabrication. Experimental findings of key dependent membrane product variables namely average pore size and porosity were regarded as biases to identify optimal kaolin, feldspar and saw dust precursor compositions. Further, a comparative study was conducted to evaluate upon the sensitivity of optimal compositions while considering flexural strength as an additional response variable. The optimal precursor compositions were 48.19 mass % kaolin, 28.62 mass % feldspar and 8.19 mass % saw dust for which optimal responses of average pore size and porosity were 1.00 ± 0.05 μm and 28.47 ± 0.29%. However, while considering flexural strength as additional response variable, the optimal compositions varied marginally (48 mass % kaolin, 27.81 mass % feldspar and 8.26 mass % saw dust) for which the optimal responses of pore size, porosity and flexural strength were evaluated as 0.93 ± 0.02 μm, 29.98 ± 1.10% and 8.75 ± 0.57 MPa. Hence, the most relevant RSM model refers to the model designed without considering flexural strength as an additional variable and with reduced model complexity.
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      PubDate: 2018-06-21T15:02:42Z
  • Ionic-liquid and cuprous sulfite containing halloysite nanoclay: An
           efficient catalyst for Click reaction as well as N- and O-arylations
    • Abstract: Publication date: 15 September 2018
      Source:Applied Clay Science, Volume 162
      Author(s): Samahe Sadjadi, Majid M. Heravi, Masoumeh Malmir, Fatemeh Ghoreyshi Kahangi
      Using halloysite nanoclay (Hal) as a support and its multi-functionalization, a novel heterogeneous catalyst, Hal-IMI-SO3Cu, containing ionic liquid, copper species and sulfur trioxide was prepared and fully characterized by applying SEM/EDS, TEM, BET, ICP-AES, TGA, XRD and FTIR spectroscopy. Hal-IMI-SO3Cu exhibited excellent catalytic activity for the synthesis of triazoles through Click reaction of sodium azide, α-haloketones, alkyl halides and terminal alkynes as well as N-arylation and O-arylation of imidazole and phenol with aryl halides under mild and eco-friendly condition. The comparison of the catalytic activities of Hal–Cu, Hal-IMI-Cu (the catalyst without sulfur), Hal-SO3HCu (the catalyst without IL), Hal-IMI-SCu (the catalyst in which –SH was not oxidized to –SO3H) and Hal-IMI-SO3H (the catalyst without copper) with that of the catalyst for the Click reaction confirmed that copper played the dominant role in the catalysis. Moreover, the contribution of IL, and sulfur species to the catalysis was confirmed. It was also proved that the presence of –SO3H was more favorable than –SH. The recyclability tests confirmed that Hal-IMI-SO3Cu was highly recyclable, up to 10 reaction runs, with slight loss of the catalytic activity and copper leaching.
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      PubDate: 2018-06-21T15:02:42Z
  • Novel multi amine-containing Gemini surfactant modified montmorillonite as
           adsorbents for removal of phenols
    • Abstract: Publication date: 15 September 2018
      Source:Applied Clay Science, Volume 162
      Author(s): Ying Xu, Muhammad Asim Khan, Fengyun Wang, Mingzhu Xia, Wu Lei
      A novel multi amine-containing Gemini surfactant (including four positively charged N) modified organo-montmorillonite (GMt) was prepared and served as adsorbents of phenol, o-chlorophenol (2-CP) and 2,4,6-trichlorophenol (2,4,6-TCP). The structure and morphology of GMt were studied by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), N2 adsorption/desorption isotherms (BET) and thermo gravimetric analysis (TGA). A batch technique was applied to investigate the influence of various factors, and the results illustrated that the saturated intercalation concentration of the modifier was 0.8 times to the cation exchange capacity (CEC) of the original Na-Mt and the adsorption was pH dependent, the optimum adsorption occurred at pH = 10, 7, 5 for phenol, 2-CP and 2,4,6-TCP, respectively. At the same conditions, the adsorption capacities of original Na-Mt were only 8.29 mg/g, 26.20 mg/g and 39.13 mg/g for three phenolic pollutants, while the maximum equilibrium adsorption amounts were 81.68 mg/g, 336.59 mg/g and 535.49 mg/g for phenol, 2-CP and 2,4,6-TCP, respectively. The adsorption kinetics of all the three phenols was in good agreement with the pseudo-second order kinetics model. The adsorption isotherm of 2,4,6-TCP was abided by Langmuir and Freundlich isotherm, however, phenol and 2-CP were better modeled by Freundlich isotherm. The negative values of ∆G° and positive values of ∆H° got from thermodynamic study confirmed that the adsorption of 2-CP and 2,4,6-TCP on GMt was a physical, spontaneous and endothermic process. The adsorption process of phenol was an exothermic process. Both adsorption and partition contributed to the adsorption of these three phenols to organo-montmorillonite.
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      PubDate: 2018-06-21T15:02:42Z
  • The influence of pulp and interfacial chemistry and mode of electrical
           power input on electroosmotic dewatering of Na-exchanged smectite
    • Abstract: Publication date: 15 September 2018
      Source:Applied Clay Science, Volume 162
      Author(s): Andrew Harris, Ataollah Nosrati, Jonas Addai-Mensah
      In this study, pulp and interfacial chemistry, gravity settling/drainage and electroosmotic (EO) dewatering behaviour of two types of fine, Na-exchanged smectite clay (high and low Na content montmorillonites) slurries were investigated as a function of background electrolyte ionic strength and time at pH 7.5 with constant voltage (0.5 vs. 1 V/cm initial field strength) or current density (12.5 vs. 25 A/m2). The two smectite variants displayed significantly different mineral chemistry and particle zeta potential, the latter dependent on Ca(II) background. Suppressed swelling and marked reduction in zeta potential magnitude occurred at 0.03–0.3 M Ca(II) ionic strength, the extent of which was greater for low than high Na-smectite pulps. Ca(II) ionic strength of ~0.1 M improved pre-EO gravity dewatering from <5% to 70–80% water recovery for both low and high Na-smectite pulps. Low Na content clay, constant voltage input (1 V/cm initial field strength), 0.1 M Ca(II) and 8 h of operation were found to be most conducive conditions to EO efficacy in terms of minimising the energy consumed per kg water recovered. EO energy consumption of ~0.04–0.1 kWh/kg water recovered observed for 27–44 wt% additional water recoveries are competitive with the performance of conventional thermal and mechanical dewatering
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      PubDate: 2018-06-21T15:02:42Z
  • Growth reduction of Microcystis aeruginosa by clay ball elution solution
    • Abstract: Publication date: 15 September 2018
      Source:Applied Clay Science, Volume 162
      Author(s): Tsukasa Ito, Katsuyuki Okabe, Masanobu Mori
      Clay is a natural material, and its transportation via rivers to estuaries is influenced by man-made structures. We hypothesized that chemicals eluted from clay affect bloom bacteria. To evaluate this hypothesis, we created an environment in which bacteria were separated from clay using clay balls. When Microcystis aeruginosa was incubated with clay balls, the growth rate at and after the late exponential phase decreased by two-thirds compared to that of Microcystis incubated without a clay ball. The clay ball adsorbed ammonia and phosphorus at neutral pH, but this was not the main reason for the growth reduction. Incubation in Microcystis aeruginosa (MA) medium made of a clay ball-soaked solution, a cement ball-soaked solution, a silicate solution, and distilled water revealed that the growth of Microcystis was significantly lower in the MA medium made of the clay ball-soaked solution, whereas there was no difference in growth among the other solutions. None of the solutions exerted a negative influence on the growth of Achnanthidium minutissimum. These results suggest that the growth reduction of Microcystis was due to a combined effect by silicate and other chemical compounds eluted from the clay ball. These findings may improve our understanding of cyanobacterial blooms and enhance water management.
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      PubDate: 2018-06-21T15:02:42Z
  • Adsorption behavior and mechanism of core–shell magnetic
           rhamnolipid–layered double hydroxide nanohybrid for phenolic compounds
           from heavy metal–phenolic pollutants
    • Abstract: Publication date: 15 September 2018
      Source:Applied Clay Science, Volume 162
      Author(s): Yan Li, Hao-Yu Bi, Xiao-Ming Mao, Ya-Qin Liang, Hui Li
      A core–shell magnetic rhamnolipid (RL)–layered double hydroxide (LDH) nanohybrid (Fe3O4@(RL–LDH)) was synthesized by the delamination of magnetic LDH (Fe3O4@LDH) initially and then assembling with RL/NaOH water solution to remove p-cresol/hydroquinone from heavy metal–phenolic pollutants in aqueous solution. The characteristics of the obtained Fe3O4@(RL–LDH) nanohybrid was analyzed by X-ray diffraction, Fourier transform infrared spectroscopy, inductively coupled plasma atomic emission spectrometry, CHN elemental analysis, transmission electron microscopy, vibrating sample magnetometer, thermogravimetry and differential scanning calorimetry, specific surface area, and zeta potential. Results confirmed that the Fe3O4@(RL–LDH) particles possessed core (Fe3O4)–shell (RL–LDH) structures and magnetic properties, and RL− anions were successfully introduced into interlayers of Fe3O4@LDH. The adsorption of p-cresol/hydroquinone by Fe3O4@(RL–LDH) from Cu2+–phenolic pollutants in aqueous solution was studied with magnetic separation in detail. The effect of factors, including the initial solution pH, contact time, initial p-cresol/hydroquinone concentration, and temperature, on the adsorption were investigated. Findings revealed that (1) the adsorption capacities of Fe3O4@(RL–LDH) for p-cresol and hydroquinone were much greater than those of Fe3O4@LDH in the presence/absence of Cu2+ and (2) the adsorption amount of p-cresol by Fe3O4@(RL–LDH) was higher than that of hydroquinones with (or without) Cu2+ ions. The efficient p-cresol/hydroquinone adsorption was mainly due to the dissolution of p-cresol/hydroquinone in the hydrophobic interlayer region formed by RL− anions, and the adsorption mechanism was confirmed by the difference between the adsorption capacities of Fe3O4@(RL–LDH) for p-cresol and hydroquinone.
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      PubDate: 2018-06-21T15:02:42Z
  • Cylindrical Couette flow of Laponite dispersions
    • Abstract: Publication date: 15 September 2018
      Source:Applied Clay Science, Volume 162
      Author(s): Marguerite Bienia, Cyril Danglade, André Lecomte, Julien Brevier, Cécile Pagnoux
      Taylor-Couette flow of aqueous dispersions of nanometric Laponite platelets was studied by dynamic light scattering and direct observation. Despite high rotation rates, gel growth was observed starting from the stator, and filling almost the whole gap after some period of time depending on the angular velocity of the rotor. SEM microscopy observations of the flowing liquid showed the presence of spheres in the micrometer range. A mechanism for gel growth is proposed, where lumps of gel are formed in the sheared liquid and form spherical aggregates which eventually adhere to the side of the gel, with a progressing gelling front.

      PubDate: 2018-06-18T18:47:31Z
  • Hydrothermal carbonization synthesis of Al-pillared montmorillonite@carbon
           composites as high performing toluene adsorbents
    • Abstract: Publication date: 15 September 2018
      Source:Applied Clay Science, Volume 162
      Author(s): Changchi Liu, Weiquan Cai, Licheng Liu
      Clay-based composites coated with carbon are highly promising for volatile organic compounds (VOC) removal because of their unique and adjustable layered structures and good stability in high temperature regeneration. To develop such kind of cost-effective clay-based adsorbents, we synthesized a series of Al-pillared Montmorillonite@Carbon (Al-Mt@C) composites by a hydrothermal carbonization method on laboratory scale. The mass ratio of Al-pillared Montmorillonite (AlMt) to carbon precursor glucose was varied from 3/3, 3/5 to 3/7. The samples were extensively characterized by XRD, SEM, FTIR, N2 adsorption/desorption and TG techniques. The adsorption/desorption performance for toluene, one of the typical VOC, was investigated by measuring the breakthrough curve under a dynamic condition. There were two forms of carbon formed in the Al-Mt@C composites: carbon microspheres and smaller carbon clusters. Both micropores and mesopores were formed by accumulation of the carbon clusters in the Mt. layers, which contributes to the enhanced adsorption capacity toward toluene in general. Among the Al-Mt@C samples, Al-Mt@C(3/5) showed the best adsorption and regeneration performance. The highest toluene adsorption capacity reached 39.9 mg/g. This research extends the possible use of the Al-Mt@C composites to the field of air pollutant control.
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      PubDate: 2018-06-18T18:47:31Z
  • Roasting-leaching experiments on glauconitic rocks of Bakchar ironstone
           deposit (Western Siberia) for evaluation their fertilizer potential
    • Abstract: Publication date: 15 September 2018
      Source:Applied Clay Science, Volume 162
      Author(s): Maxim Rudmin, Yulia Oskina, Santanu Banerjee, Aleksey Mazurov, Bulat Soktoev, Mikhail Shaldybin
      This study examines factors favouring optimal release of potassium from a glauconitic rock by moderate roasting-leaching. Sieving and electromagnetic separation of oolitic iron ore deposit increases the concentration of glauconite grains substantially. Roasting and chemical leaching of this concentrate enhances the release of potassium as interlayer structures of glauconite collapses. This study records the percentage of potassium recovered from glauconite under different experimental conditions, viz., temperature, reaction time, concentration as well as volume of HCl and stages involved in the leaching treatment. Leaching of glauconite without roasting results a low recovery (<15%) of K at room temperature. The recovery of K content from the sample increases markedly with increase in concentration of HCl, leaching time, and the ratio by mass of sample to HCl, and marginally with increased stages of leaching. Roasting at 900 °C recovers maximum K up to 62–63% for one-stage leaching treatment at 100 °C for 120 min with a 4 mol∙l−1 HCl solution for a sample: HCl ratio of 1:5. The roasting-leaching method, therefore, holds promise for converting glauconite to potash salts for agronomic applications.
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      PubDate: 2018-06-18T18:47:31Z
  • Co-assembly of exfoliated Mg/Al layered double hydroxides nanosheets with
           sulfobutyl ether-β-cyclodextrin for enantioseparation of racemic
    • Abstract: Publication date: 15 September 2018
      Source:Applied Clay Science, Volume 162
      Author(s): Fawei Zhu, Lumin Wang, Sen Liao, Yuqiu Zhu, Wen Luo, Xueqian Huang, Feipeng Jiao, Xiaoqing Chen
      Co-assembly of exfoliated Mg/Al layered double hydroxide (Mg/Al-NO3-LDH) nanosheets with sulfobutyl ether-β-cyclodextrin (SBE-β-CD) via swelling/restoration method was presented in this paper. SBE-β-CD located in the form of flat-lying intertwined bilayer arrangement in the interlayer region. The structural and characteristic features of the supramolecular products as prepared were studied by XRD, FT-IR, UV–vis DRS and TGA. The as-proposed SBE-β-CD-LDH materials were applied to recognize clinical medicine propranolol enantiomers (R,S-PPL). Series studies were carried out to address various experimental parameters including contact time, pH value and operational temperature, concentrations of R,S-PPL. The experimental results indicated that SBE-β-CD-LDH could tend to adsorb R-PPL and the e.e.% value of single separation was 17.4% under optimal experimental conditions. The special spatial structure of SBE-β-CD-LDH might play a key role to achieve the enantioseparation of racemic PPL. According to the kinetic studies, the separation of PPL enantiomers had been well described by pseudo-second-order kinetic model. The adsorption isotherms indicated that the adsorption data fitted the Freundlich isotherm equation well. The thermodynamic parameters indicated that the adsorption process was a spontaneous and endothermic chemisorption process.
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      PubDate: 2018-06-18T18:47:31Z
  • Mineralogical and thermal analyses of the Hellenistic ceramics from
           Laodicea Temple, Iran
    • Abstract: Publication date: 15 September 2018
      Source:Applied Clay Science, Volume 162
      Author(s): Maria Daghmehchi, Christina Rathossi, Hadi Omrani, Mohammadamin Emami, Mehdi Rahbar
      In this study, thermal behavior of the Hellenistic ceramics from Laodicea Temple (Seleucid period), Iran, was investigated through spectroscopic, thermogravimetric, mineralogical and chemical analyses. The results indicate the same calcareous raw material was used for the ceramic production. On the basis of X-ray diffraction (XRD), four firing temperature ranges can be established: T < 750 °C, 850–900 °C, 950–1000 °C and 1000–1050 °C. These ceramics were differentiated based on different mineralogical phases resulting from the different firing temperatures. For low temperature fired ceramics, the main crystalline phases were calcite and quartz. Gehlenite is the predominant new mineral at 850 °C. CaO reacts with gehlenite and forms anorthite at around 950 °C. Diopside grows with increasing firing temperature up to 1050 °C in the Ca and Mg-rich clayey compositions and an oxidizing atmosphere, corroborated by trace hematite. The contemporaneous presence of secondary calcite and newly formed crystalline phases (diopside, gehlenite) at high temperatures indicates fast heating rate and/or short soaking time as well as coarse-grained primary calcite. Fourier Transform-Infrared (FT-IR) spectrometry indicates a considerable change in phase structures and a progressive decrease and broadening in calcite bands as a function of firing temperature.

      PubDate: 2018-06-18T18:47:31Z
  • Influence of preparation methods on textural properties of purified
    • Abstract: Publication date: 15 September 2018
      Source:Applied Clay Science, Volume 162
      Author(s): Liaqat Ali Shah, Maria das Graça da Silva Valenzuela, Muhammad Farooq, Shaukat Ali Khattak, Francisco Rolando Valenzuela Díaz
      The aim of this work was to study the effect of three different purification methods, using chemical solution of (Na(PO3))6 (method-I), NaCl (method-II) and Na2CO3 (method-III), followed by stokes law of sedimentation, on the textural properties of a Pakistani bentonite, containing >70% Ca2+-montmorillonite. The raw and the purified samples were examined through X-ray Diffraction (XRD), N2 adsorption-desorption, and laser diffraction method (LDM). The quartz contents were found absent in all the purified samples. It was confirmed that the sample obtained by the method-I and other two methods resulted in to be,typically, Ca2+-bentonite and Na+-bentonite, respectively. In comparison with the raw sample, higher percentage volume of fine particles was detected in purified samples. The fine particles, however, exhibited significant enhancement in the samples purified by method-II and method-III. Higher pore volume and specific surface area were noticed for samples purified by the trio methods in comparison with the raw sample. Specific surface area of the sample obtained by the method-III was much higher than that of the other purified samples. Mesopores volume was increased significantly by purification, especially by the method-I and III. Considerably higher value of micropores volume/area and mesopores volume/area were detected for sample purified by method-III than for the samples purified by the other methods. A highly porous sample with the excellent surface area and small particle size was obtained by purification method-III which can be used as a good adsorbent, catalyst and catalyst support.

      PubDate: 2018-06-18T18:47:31Z
  • Mechanical and rheological properties of nitrile rubber/fluoromica
    • Abstract: Publication date: 15 September 2018
      Source:Applied Clay Science, Volume 162
      Author(s): Felipe N. Linhares, Cléverson F.S. Gabriel, Ana Maria F. de Sousa, Regina Célia Reis Nunes
      Fluoromica is a clay mineral obtained from chemical modification of talc with Na2SiF6. In this study, it was used to prepare clay mineral polymer composites (CPN) based on nitrile rubber. The composites were compounded in a roll mill and it was studied the effect of the fluoromica content as well as the shear ratio employed during the preparation. The composites were assessed based on the mechanical properties, dynamic-mechanical performances, rheological properties, and morphological aspects. The results suggested that the formation of chemical crosslinks was affected with the presence of the clay mineral, moreover, little or no reinforcement effect was achieved most likely to the lack of interaction with the matrix.

      PubDate: 2018-06-18T18:47:31Z
  • Hydrothermal synthesis of MoS2 nanosheet/palygorskite nanofiber hybrid
           nanostructures for enhanced catalytic activity
    • Abstract: Publication date: 15 September 2018
      Source:Applied Clay Science, Volume 162
      Author(s): Xiaoyu Li, Kang Peng
      MoS2 nanosheet/palygorskite nanofiber (MoS2/Pal) hybrid nanostructures were synthesized via facile hydrothermal method, and the catalytic activities of samples were assessed by reduction of 4-nitrophenol (4-NP). The structure characterizations indicate that the MoS2 nanosheets with abundant active sites are assembled on the palygorskite (Pal) nanofiber, and the Pal could prevent MoS2 nanosheets aggregation. With MoS2/Pal as catalyst, the decoloration rate of 4-NP reaches up to 99.72% after 10 min, and the apparent reaction rate constant is 0.750 min−1 at catalyst concentration of 1.0 g/L. The MoS2/Pal exhibits higher catalytic activity than hydrothermally synthesized MoS2 for the reduction reaction of 4-NP, which could be attributed to the synergistic effect of more reactive sites in hybrid nanostructures and the hydrophilicity of Pal. The as-prepared MoS2/Pal hybrid nanostructures are promising candidates for catalytic applications in the water-treatment and biomedical fields. The synthesis process and catalysis mechanism of MoS2/Pal were explored, which might provide insights for designing high activity and cost-effective catalysts.
      Graphical abstract image

      PubDate: 2018-06-18T18:47:31Z
  • Hierarchical C-doped BiPO4/ZnCoAl-LDO hybrid with enhanced photocatalytic
           activity for organic pollutants degradation
    • Abstract: Publication date: 15 September 2018
      Source:Applied Clay Science, Volume 162
      Author(s): Fei Ji, Jia Li, Xinling Cui, Jun Liu, Xingmei Bing, Peng Song
      We report here the synthesis of novel C-doped BiPO4/ZnCoAl-LDO hybrid for the first time via a facile biomass route that involved using pine pollen as template. The as-prepared samples exhibited excellent adsorption and photo-degradation performances toward methylene blue under simulated sunlight irradiation. It was found that the formation of heterojunction between BiPO4 and C-doped layered mixed metal oxide (C-doped LDO) ZnCo2O4 could effectively reduce the recombination rate of electrons and holes, and thus improve the photocatalytic activity via enlarging the response range of sunlight. The possible charge transfer mechanism for photo-degradation of methylene blue by C-doped BiPO4/LDO was proposed based on the UV–vis diffuse reflectance spectra and active species test. This work provides a new insight into removal of organic pollutant from wastewater by a novel ZnCoAl-LDO based hybrid via adsorption-photocatalysis synergetic effect.

      PubDate: 2018-06-18T18:47:31Z
  • Sepiolite as replacement of short glass fibre in polyamide composites for
           injection moulding applications
    • Abstract: Publication date: 15 September 2018
      Source:Applied Clay Science, Volume 162
      Author(s): Manuel Herrero, Karina Núñez, Raúl Gallego, Juan Carlos Merino, José María Pastor
      Sepiolite polyamide 6 nanocomposites were prepared via melt compounding and in situ polymerization. The effects of the preparation approach, the amount of the clay and the surface clay modification were evaluated in order to check their influence on morphology, thermal, mechanical and flow behaviour of the final nanocomposites. Regardless of the preparation method, all nanocomposites showed good dispersion of the sepiolite in the matrix and significant improvements in Young's modulus, tensile strength and heat-distortion temperature were achieved. However, the nanocomposites obtained in one-step by in situ polymerization presented slightly better mechanical properties, than the obtained by melt compounding, due to the greater dispersion of the nanoclay within polyamide matrix. Especially interesting were the materials reinforced with modified sepiolite, where the grafting of an aminosilane onto the sepiolite surface produced important increases in the elongation at break and impact values as consequence of the improved stress transfer between the sepiolite and polymer matrix. Furthermore, nanocomposites with 10 wt% of sepiolite have been compared with higher loaded glass fibre polyamide. The nanocomposites presented similar or even better performances than commercial composites offering an important weight reduction for final applications.

      PubDate: 2018-06-13T12:01:42Z
  • Tensile strength during drying of remoulded and compacted clay: The role
           of fabric and water retention
    • Authors: Houcem Trabelsi; Enrique Romero Mehrez Jamei
      Abstract: Publication date: 15 September 2018
      Source:Applied Clay Science, Volume 162
      Author(s): Houcem Trabelsi, Enrique Romero, Mehrez Jamei
      The paper presents an experimental investigation on the tensile strength of an unsaturated clay, both in remoulded and compacted states. To complete the experimental study, a new apparatus was designed with the purpose of determining direct tensile stress under controlled-displacement or controlled-force. The design exploits a direct shear test box, which was adapted to the scope of this investigation. Three different hydro-mechanical paths were followed before the tensile strength was determined: a) drying paths on remoulded samples; b) drying paths after compaction at different initial water contents; and c) dynamic compaction at different water contents, hence at different suctions and degrees of saturation. A microstructural investigation was also performed to better understand the experimental results and obtain the most relevant physical parameters. The preparation methods induced different initial fabrics, which dominated the water retention properties, as well as the tensile strength behaviour. A recent model for water retention, including the effects of multimodal fabric, was calibrated on available data and used to predict the suction of the samples along the drying paths, where direct information was not available. A simple model for tensile strength was proposed for its evolution, which included the role of multimodal fabric and their different water storage capabilities, the evolution of dry density and the initial water content (at the beginning of the tensile test path). For the compacted sample, typically showing a multimodal pore size distribution, the tensile strength was found to be a function of the state variables describing the macropore network. Dry density increases on drying appeared in all the cases to dominate the tensile response, Water exchange and suction increase were well correlated to the tensile response evolution.

      PubDate: 2018-06-07T10:49:40Z
  • The effect of reduced graphene oxide intercalated hybrid organoclay on the
           dielectric properties of polyvinylidene fluoride nanocomposite films
    • Authors: Gyanaranjan Sahoo; Niladri Sarkar Sarat Swain
      Abstract: Publication date: 15 September 2018
      Source:Applied Clay Science, Volume 162
      Author(s): Gyanaranjan Sahoo, Niladri Sarkar, Sarat K. Swain
      In present investigation, reduced graphene oxide sandwiched organoclay (Clay@r-GO) was introduced as conductive nanofillers to promote the electroactive β-phase as well as conducting network within polyvinylidene fluoride (PVDF) via solution casting technique. The composition of Clay@r-GO nanohybrid filler was formulated in the weight ratio of 1: 20 of graphene oxide and organoclay after observing the independent contribution of r-GO and organoclay to the dielectric property of PVDF. PVDF/Clay@r-GO nanocomposite films were designed with various wt% of Clay@r-GO filler. The fabricated PVDF/Clay@r-GO nanocomposite film was characterized with SEM, TEM, FTIR and XRD. Electron microscopic results revealed that only 5 wt% of Clay@r-GO hybrid nanostructures was effective to inhibit the formation nonpolar α crystal, whereas; FTIR analysis showed the ~ 80% transformation of β-phase in PVDF/Clay@r-GO nanocomposite film with incorporation of only 2 wt% Clay@r-GO hybrid filler. With 2 wt% of nanohybrid filler, thermal stability of PVDF/Clay@r-GO nanocomposite film was highly improved with a char residue of 41.37% at 700 °C. Dielectric study reveals that only 2 wt% hybrid nanofillers was effective to impart high dielectric permittivity (ɛ'~102 at 1 Hz) as well as low dielectric loss (<1), whereas; a optimum permittivity (ɛ'~ 433 at 1 Hz) is observed for 15 wt% loading. Therefore, the fabricated PVDF/Clay@r-GO nanocomposite film may be used as advanced dielectric materials for real life application.
      Graphical abstract image

      PubDate: 2018-06-07T10:49:40Z
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