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  Subjects -> EARTH SCIENCES (Total: 646 journals)
    - EARTH SCIENCES (467 journals)
    - GEOLOGY (72 journals)
    - GEOPHYSICS (26 journals)
    - HYDROLOGY (21 journals)
    - OCEANOGRAPHY (60 journals)

EARTH SCIENCES (467 journals)                  1 2 3 | Last

Showing 1 - 200 of 371 Journals sorted alphabetically
Acta Geodaetica et Geophysica     Hybrid Journal   (Followers: 1)
Acta Geodaetica et Geophysica Hungarica     Full-text available via subscription   (Followers: 2)
Acta Geophysica     Open Access   (Followers: 6)
Acta Geotechnica     Hybrid Journal   (Followers: 6)
Acta Meteorologica Sinica     Hybrid Journal   (Followers: 3)
Advances in High Energy Physics     Open Access   (Followers: 14)
Advances In Physics     Hybrid Journal   (Followers: 7)
Aeolian Research     Hybrid Journal   (Followers: 5)
African Journal of Aquatic Science     Hybrid Journal   (Followers: 12)
Algological Studies     Full-text available via subscription   (Followers: 2)
Alpine Botany     Hybrid Journal   (Followers: 3)
AMBIO     Hybrid Journal   (Followers: 13)
Anadolu University Journal of Science and Technology     Open Access  
Anales del Instituto de la Patagonia     Open Access   (Followers: 1)
Andean geology     Open Access   (Followers: 3)
Annales Henri Poincaré     Hybrid Journal   (Followers: 3)
Annales UMCS, Geographia, Geologia, Mineralogia et Petrographia     Open Access  
Annals of Geophysics     Full-text available via subscription   (Followers: 10)
Annals of GIS     Hybrid Journal   (Followers: 16)
Annals of Glaciology     Full-text available via subscription   (Followers: 2)
Annual Review of Marine Science     Full-text available via subscription   (Followers: 9)
Anthropocene     Hybrid Journal   (Followers: 2)
Anthropocene Review     Hybrid Journal   (Followers: 4)
Applied Clay Science     Hybrid Journal   (Followers: 4)
Applied Geochemistry     Hybrid Journal   (Followers: 10)
Applied Geomatics     Hybrid Journal   (Followers: 3)
Applied Geophysics     Hybrid Journal   (Followers: 6)
Applied Ocean Research     Hybrid Journal   (Followers: 4)
Applied Petrochemical Research     Open Access   (Followers: 2)
Applied Remote Sensing Journal     Open Access   (Followers: 23)
Aquatic Conservation Marine and Freshwater Ecosystems     Hybrid Journal   (Followers: 32)
Arctic Science     Open Access   (Followers: 5)
Arctic, Antarctic, and Alpine Research     Full-text available via subscription   (Followers: 10)
Artificial Satellites : The Journal of Space Research Centre of Polish Academy of Sciences     Open Access   (Followers: 15)
Asia-Pacific Journal of Atmospheric Sciences     Hybrid Journal   (Followers: 7)
Asian Journal of Earth Sciences     Open Access   (Followers: 19)
Asian Review of Environmental and Earth Sciences     Open Access   (Followers: 1)
Atlantic Geology : Journal of the Atlantic Geoscience Society / Atlantic Geology : revue de la Société Géoscientifique de l'Atlantique     Full-text available via subscription   (Followers: 2)
Atmosphere-Ocean     Full-text available via subscription   (Followers: 11)
Atmospheric and Climate Sciences     Open Access   (Followers: 23)
Australian Journal of Earth Sciences: An International Geoscience Journal of the Geological Society of Australia     Hybrid Journal   (Followers: 11)
Boletim de Ciências Geodésicas     Open Access  
Boreas: An International Journal of Quaternary Research     Hybrid Journal   (Followers: 10)
Bragantia     Open Access   (Followers: 2)
Bulletin of Earthquake Engineering     Hybrid Journal   (Followers: 10)
Bulletin of Geosciences     Open Access   (Followers: 9)
Bulletin of the Lebedev Physics Institute     Hybrid Journal   (Followers: 1)
Bulletin of the Seismological Society of America     Full-text available via subscription   (Followers: 20)
Bulletin of Volcanology     Hybrid Journal   (Followers: 17)
Cadernos de Geociências     Open Access  
Canadian Journal of Plant Science     Full-text available via subscription   (Followers: 14)
Canadian Mineralogist     Full-text available via subscription   (Followers: 3)
Canadian Water Resources Journal     Hybrid Journal   (Followers: 17)
Carbonates and Evaporites     Hybrid Journal   (Followers: 3)
CATENA     Hybrid Journal   (Followers: 4)
Chemical Geology     Hybrid Journal   (Followers: 14)
Chemie der Erde - Geochemistry     Hybrid Journal   (Followers: 4)
Chinese Geographical Science     Hybrid Journal   (Followers: 5)
Chinese Journal of Geochemistry     Hybrid Journal   (Followers: 3)
Chinese Journal of Oceanology and Limnology     Hybrid Journal   (Followers: 3)
Ciencias Espaciales     Open Access  
Climate and Development     Hybrid Journal   (Followers: 12)
Coastal Management     Hybrid Journal   (Followers: 23)
Cogent Geoscience     Open Access  
Comptes Rendus Geoscience     Full-text available via subscription   (Followers: 7)
Computational Geosciences     Hybrid Journal   (Followers: 12)
Computational Mathematics and Mathematical Physics     Hybrid Journal   (Followers: 1)
Computers and Geotechnics     Hybrid Journal   (Followers: 8)
Contemporary Trends in Geoscience     Open Access   (Followers: 2)
Continental Shelf Research     Hybrid Journal   (Followers: 8)
Contributions to Mineralogy and Petrology     Hybrid Journal   (Followers: 10)
Contributions to Plasma Physics     Hybrid Journal   (Followers: 2)
Coral Reefs     Hybrid Journal   (Followers: 16)
Cretaceous Research     Hybrid Journal   (Followers: 6)
Cybergeo : European Journal of Geography     Open Access   (Followers: 4)
Depositional Record     Open Access  
Developments in Geotectonics     Full-text available via subscription   (Followers: 3)
Developments in Quaternary Science     Full-text available via subscription   (Followers: 3)
Développement durable et territoires     Open Access   (Followers: 2)
Diatom Research     Hybrid Journal  
Doklady Physics     Hybrid Journal   (Followers: 1)
Dynamics of Atmospheres and Oceans     Hybrid Journal   (Followers: 9)
E&S Engineering and Science     Open Access  
E3S Web of Conferences     Open Access  
Earth and Planetary Science Letters     Hybrid Journal   (Followers: 70)
Earth and Space Science     Open Access   (Followers: 6)
Earth Interactions     Full-text available via subscription   (Followers: 11)
Earth Science Research     Open Access   (Followers: 6)
Earth Surface Dynamics (ESurf)     Open Access   (Followers: 3)
Earth Surface Processes and Landforms     Hybrid Journal   (Followers: 19)
Earth System Dynamics     Open Access   (Followers: 5)
Earth System Dynamics Discussions     Open Access   (Followers: 4)
Earth's Future     Open Access   (Followers: 1)
Earth, Planets and Space     Open Access   (Followers: 5)
Earthquake Engineering and Engineering Vibration     Hybrid Journal   (Followers: 6)
Earthquake Science     Hybrid Journal   (Followers: 9)
Earthquake Spectra     Full-text available via subscription   (Followers: 17)
Ecohydrology     Hybrid Journal   (Followers: 9)
Ecological Questions     Open Access   (Followers: 5)
Electromagnetics     Hybrid Journal   (Followers: 2)
Energy Efficiency     Hybrid Journal   (Followers: 11)
Energy Exploration & Exploitation     Full-text available via subscription   (Followers: 4)
Environmental Earth Sciences     Hybrid Journal   (Followers: 19)
Environmental Geology     Hybrid Journal   (Followers: 9)
Environmental Geosciences     Full-text available via subscription   (Followers: 4)
Environmental Geotechnics     Open Access   (Followers: 3)
Erwerbs-Obstbau     Hybrid Journal  
Estuaries and Coasts     Hybrid Journal   (Followers: 18)
Estuarine, Coastal and Shelf Science     Hybrid Journal   (Followers: 33)
Estudios Geográficos     Open Access  
European Journal of Mineralogy     Full-text available via subscription   (Followers: 10)
Exploration Geophysics     Hybrid Journal   (Followers: 3)
Facies     Hybrid Journal   (Followers: 9)
Fieldiana Life and Earth Sciences     Full-text available via subscription   (Followers: 1)
Física de la Tierra     Open Access  
Folia Musei rerum naturalium Bohemiae occidentalis. Geologica et Paleobiologica     Open Access  
Folia Quaternaria     Open Access  
Forestry Chronicle     Full-text available via subscription   (Followers: 10)
Frontiers in Earth Science     Open Access   (Followers: 5)
Frontiers in Geotechnical Engineering     Open Access   (Followers: 2)
Frontiers of Earth Science     Hybrid Journal   (Followers: 8)
Fundamental and Applied Limnology / Archiv für Hydrobiologie     Full-text available via subscription   (Followers: 4)
GEM - International Journal on Geomathematics     Hybrid Journal   (Followers: 1)
Geo-Marine Letters     Hybrid Journal   (Followers: 7)
Geoacta     Open Access   (Followers: 4)
Geobiology     Hybrid Journal   (Followers: 7)
Geocarto International     Hybrid Journal   (Followers: 8)
Geochemistry : Exploration, Environment, Analysis     Hybrid Journal   (Followers: 7)
Geochemistry, Geophysics, Geosystems     Full-text available via subscription   (Followers: 24)
Geochimica et Cosmochimica Acta     Hybrid Journal   (Followers: 23)
Geochronometria     Hybrid Journal   (Followers: 3)
Geoderma Regional : The International Journal for Regional Soil Research     Full-text available via subscription   (Followers: 3)
Geodinamica Acta     Hybrid Journal   (Followers: 3)
Geodynamics & Tectonophysics     Open Access  
Geoenvironmental Disasters     Open Access   (Followers: 3)
Geofluids     Hybrid Journal   (Followers: 4)
Geoforum     Hybrid Journal   (Followers: 20)
Géographie physique et Quaternaire     Full-text available via subscription  
Geography and Natural Resources     Hybrid Journal   (Followers: 4)
Geoheritage     Hybrid Journal   (Followers: 1)
Geoinformatica Polonica : The Journal of Polish Academy of Arts and Sciences     Open Access  
Geoinformatics & Geostatistics     Hybrid Journal   (Followers: 5)
Geological Journal     Hybrid Journal   (Followers: 14)
Geological Magazine     Hybrid Journal   (Followers: 16)
Geology Today     Hybrid Journal   (Followers: 18)
Geomagnetism and Aeronomy     Hybrid Journal   (Followers: 2)
Geomatics, Natural Hazards and Risk     Hybrid Journal   (Followers: 7)
GEOmedia     Open Access   (Followers: 1)
Geomorphology     Hybrid Journal   (Followers: 22)
Geophysical & Astrophysical Fluid Dynamics     Hybrid Journal   (Followers: 2)
Geophysical Journal International     Hybrid Journal   (Followers: 30)
Geophysical Prospecting     Hybrid Journal   (Followers: 7)
Geophysics     Full-text available via subscription   (Followers: 18)
GeoResJ     Hybrid Journal  
Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards     Hybrid Journal   (Followers: 8)
Geoscience Canada : Journal of the Geological Association of Canada / Geoscience Canada : journal de l'Association Géologique du Canada     Full-text available via subscription   (Followers: 3)
Geoscience Data Journal     Open Access   (Followers: 2)
Geoscience Frontiers     Open Access   (Followers: 8)
Geoscience Letters     Open Access  
Geoscience Records     Open Access  
Geosciences     Open Access   (Followers: 2)
Geosciences Journal     Hybrid Journal   (Followers: 9)
Geoscientific Instrumentation, Methods and Data Systems     Open Access   (Followers: 2)
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: 6)
GISAP : Earth and Space Sciences     Open Access   (Followers: 1)
Glass Physics and Chemistry     Hybrid Journal   (Followers: 3)
Global and Planetary Change     Hybrid Journal   (Followers: 11)
Global Biogeochemical Cycles     Full-text available via subscription   (Followers: 9)
Gondwana Research     Hybrid Journal   (Followers: 6)
Grassland Science     Hybrid Journal   (Followers: 1)
Ground Water     Hybrid Journal   (Followers: 22)
Ground Water Monitoring & Remediation     Hybrid Journal   (Followers: 15)
GSA Today     Partially Free  
Helgoland Marine Research     Open Access   (Followers: 3)
History of Geo- and Space Sciences     Open Access   (Followers: 3)
Hydrobiologia     Hybrid Journal   (Followers: 17)
Hydrogeology Journal     Hybrid Journal   (Followers: 14)
Hydrological Processes     Hybrid Journal   (Followers: 21)
Hydrology and Earth System Sciences     Open Access   (Followers: 22)
ICES Journal of Marine Science: Journal du Conseil     Hybrid Journal   (Followers: 51)
IEEE Journal of Oceanic Engineering     Hybrid Journal   (Followers: 11)
Indian Geotechnical Journal     Hybrid Journal   (Followers: 2)
Indonesian Journal on Geoscience     Open Access   (Followers: 2)
Interdisciplinary Environmental Review     Hybrid Journal   (Followers: 3)
International Geology Review     Hybrid Journal   (Followers: 5)
International Journal of Advanced Geosciences     Open Access  
International Journal of Advanced Remote Sensing and GIS     Open Access   (Followers: 24)
International Journal of Advancement in Earth and Enviromental Sciences     Open Access   (Followers: 2)
International Journal of Advancement in Remote Sensing, GIS, and Geography     Open Access   (Followers: 20)
International Journal of Applied Earth Observation and Geoinformation     Hybrid Journal   (Followers: 21)
International Journal of Coal Geology     Hybrid Journal   (Followers: 2)
International Journal of Disaster Risk Reduction     Hybrid Journal   (Followers: 10)
International Journal of Earth Sciences     Hybrid Journal   (Followers: 27)
International Journal of Forest, Soil and Erosion     Open Access   (Followers: 4)
International Journal of Geo-Engineering     Open Access  
International Journal of Geographical Information Science     Hybrid Journal   (Followers: 50)

        1 2 3 | Last

Journal Cover Applied Clay Science
  [SJR: 1.17]   [H-I: 71]   [4 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0169-1317
   Published by Elsevier Homepage  [2969 journals]
  • Fibrous clay mineral authigenesis induced by fluid-rock interaction in the
           Galera fault zone (Betic Cordillera, SE Spain) and its influence on fault
           gouge frictional properties
    • Abstract: Publication date: Available online 15 July 2016
      Source:Applied Clay Science
      Author(s): Catalina Sánchez-Roa, Juan Jiménez-Millán, Isabel Abad, Daniel R. Faulkner, Fernando Nieto, Francisco J. García-Tortosa
      This study presents a mineralogical and mechanical analysis of the clay-rich materials and structures identified in the Galera Fault Zone, southern Spain that formed as a consequence of active deformation processes affecting this seismically active region. Significant differences in clay mineral assemblages and chemical composition were identified in rocks from the Galera Fault Zone, through a series of analytical techniques including XRD, SEM, TEM and XRF. Three distinct mineral assemblages were identified: 1) wall-rock assemblages including white marls and dark lutite layers, with the latter also found in injection features. Their assemblage includes dolomite, gypsum, quartz, calcite and phyllosilicates 2) smectite- and palygorskite-rich fault gouges formed on materials from the upper part of the stratigraphic sequence at the NE area of the fault (Galera Village), and 3) sepiolite-rich gouges in areas of the lower part of the stratigraphic sequence at the central SW segment of the fault (Rambla de los Pilares). Fibrous clay-rich gouges were formed by hydrothermal alteration during periods of fluid-rock interaction that was concentrated in fault planes and fractures. Their mineralogy is dominated by authigenic Mg-rich fibrous clay minerals; sepiolite, precipitated directly from an Mg-rich fluid; and palygorskite as the product of the interaction of the fluid with the Al-rich host rock. Experimental data from frictional sliding experiments on these clay-rich fault gouges reveal strong differences in their mechanical properties. Towards the north-eastern areas of the fault, the smectite- and palygorskite-rich gouge has a low friction coefficient (0.17 wet and 0.59 under vacuum) and its values of the friction stability parameter (a–b) are always positive indicating a stable regime that could be related with creeping and stable-sliding processes. In the central-south-western segment, however, the gouge is rich in authigenic sepiolite and presents complete absence of smectite. The higher friction coefficient (0.47 wet and 0.68 under vacuum) and negative values of a–b for this gouge suggest a more neutral to unstable regime that could favour earthquake nucleation.


      PubDate: 2016-07-23T03:49:44Z
       
  • Adsorption/desorption of fungicides in natural clays from Southeastern
           Spain
    • Abstract: Publication date: Available online 16 July 2016
      Source:Applied Clay Science
      Author(s): José Antonio Rodríguez-Liébana, Alberto López-Galindo, Concepción Jiménez de Cisneros, Antonia Gálvez, Marisa Rozalén, Rita Sánchez-Espejo, Emilia Caballero, Aránzazu Peña

      Graphical abstract image

      PubDate: 2016-07-23T03:49:44Z
       
  • Nature and origin of natural Zn clay minerals from the Bou Arhous Zn ore
           deposit: Evidence from electron microscopy (SEM-TEM) and stable isotope
           compositions (H and O)
    • Abstract: Publication date: Available online 16 July 2016
      Source:Applied Clay Science
      Author(s): Martine Buatier, Flavien Choulet, Sabine Petit, Rémi Chassagnon, Torsten Vennemann
      Zn-clay minerals have been found in the non-sulfide deposit of Bou Arhous (High Atlas, Morocco). They occur as white or ochre clays embedding willemite (Zn2SiO4) and are commonly associated to red detrital clays in karstic cavities. Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) with Energy Dispersive X-ray (EDX) analyses were combined in order to characterize the clay minerals and to determine the mechanism of their formation. XRD patterns on oriented and powdered clays and Fourier Transform Infrared (FTIR) spectroscopic analyses suggest that fraipontite is the major Zn clay phase (with some smectite interstratifications). SEM observation (back-scattered electron mode) shows that Zn clays are closely associated to willemite; euhedral willemite crystals show partial dissolution that preferably affects edges adjacent to newly formed fraipontite. Zn clays are also present as aggregates of about 50μm filling the porosity or pervading the detrital clays. Intimate mixtures of Zn clays with detrital micas can also be observed. TEM-EDX analyses were carried out on clay separates but also on TEM foils prepared by Focused Ion Beam (FIB) milling directly on the thin section. Low- and high-resolution transmission electron microscopy images were acquired on selected areas preserving the texture of the sample. Two types of textural sites were selected: the Zn clay aggregates filling the porosity and the detrital clays partially replaced by Zn clay minerals. STEM-EDX map and point analyses confirm the occurrence of fraipontite. Individual particles of clay minerals with about 10% of Zn were analyzed. Structural formulae support the presence of a trioctahedral TO clay mineral like fraipontite. In the analyzed aggregates, the clays are composed of crystals of about 0.5–1μm in diameter and 10 to 100nm in thickness. At high magnification, the 0.7nm layer periodicity was clearly imaged. Double layer periodicity is also common. In some fraipontite crystals, some intercalations with 1nm layer were imaged. Stable isotope measurements suggest that this Zn clay mineral formed by direct precipitation of fluids which could be meteoritic and/or hydrothermal


      PubDate: 2016-07-23T03:49:44Z
       
  • From naturally low-grade palygorskite to hybrid silicate adsorbent for
           efficient capture of Cu(II) ions
    • Abstract: Publication date: Available online 20 July 2016
      Source:Applied Clay Science
      Author(s): Wenbo Wang, Guangyan Tian, Zhifang Zhang, Aiqin Wang
      A new eco-friendly hybrid Mg, Al-silicate adsorbent with superior adsorption properties for Cu(II) was prepared by a one-step hydrothermal process using earth-abundant low-grade palygorskite (PAL) as the starting materials and non-toxic sodium carbonate as the assistant. The structural characterizations by scanning electronic microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), BET adsorption-desorption isotherms and Zeta potential analyses confirm that part of rod-like PAL crystals were in-situ transformed as smectite sheets, and the hybrid silicate adsorbents with rod/sheet transition formulation were formed. Under the action of alkaline, some inert SiOSi(or M) bonds were broken as –Si–O− groups, which not only make the adsorbent having extremely negative surface charge (−46.4mV), but also strengthen the chelating and holding capability of the adsorbent to Cu(II). The silicate adsorbent shows high adsorption capacity of 229.9mg/g for Cu(II), which can capture 98.95% of Cu(II) from 200mg/L of Cu(II) solution at the dosage of 2.6g/L (only 64.5% for raw PAL). The intensified electrostatic attraction, ion-exchange, and chemical association of Si-O− surface groups with Cu(II) primarily contribute to the improved capture capability for Cu(II).
      Graphical abstract image

      PubDate: 2016-07-23T03:49:44Z
       
  • In situ high temperature X-ray diffraction study on high strength
           aluminous porcelain insulator with the Al2O3-SiO2-K2O-Na2O system
    • Abstract: Publication date: Available online 19 July 2016
      Source:Applied Clay Science
      Author(s): Yong Meng, Guohong Gong, Dongtian Wei, Yumin Xie
      The high strength aluminous porcelain insulator with a mineral composition of kaolinite, corundum, microcline, quartz, small amounts of albite and anatase was investigated by in situ high temperature XRD (HTXRD) from 25°C to 1300°C. The amount change and reaction of minerals contained in the porcelain insulator were presented vividly. The full process occurred in successive stages: 1) kaolinite decomposed into amorphous metakaolinite in the temperature range of 500–600°C; 2) metakaolinite kept amorphous form up to about 1000°C; 3) at about 1000°C, amorphous metakaolinite generated primary mullite; 4) after bout 1200°C, microcline began to melt, forming an alkaline liquid phase which facilitated the growth of primary mullite into secondary mullite; 5) the alkaline liquid phase could etch β-quartz, resulting in the reflection intensity of β-quartz decreasing; 6) corundum was very stable in the whole heating process.


      PubDate: 2016-07-23T03:49:44Z
       
  • Flexible clay glycol lignin nanocomposite film with heat durability and
           high moisture-barrier property
    • Abstract: Publication date: Available online 19 July 2016
      Source:Applied Clay Science
      Author(s): Hiroki Kaneko, Ryo Ishii, Asami Suzuki, Takashi Nakamura, Takeo Ebina, Thi Thi Nge, Tatsuhiko Yamada
      Flexible clay polymer nanocomposite films with heat durability and high moisture-barrier property were prepared by using Li+-exchanged bentonite and polyethyleneglycol-modified lignin. Analyses revealed that the films comprised of laminated clay mineral layers and the lignin intercalated between the layers. The films retained their heat durability up to 350°C, and their moisture vapor transmission rate (MVTR) at 40°C a relative humidity (RH) of 90% was 1.64gm−2 day−1, which is lower than that of plastic films. The low MVTR originated from not only the water-resistant bentonite, owing to the migration of interlayer Li+ ions into the octahedral sheets after annealing, but also the modified lignin. Consequently, the films have potential as a flexible substrate for electronic devices.
      Graphical abstract image

      PubDate: 2016-07-23T03:49:44Z
       
  • Adsorption of polyhydroxy fullerene on polyethylenimine-modified
           montmorillonite
    • Abstract: Publication date: Available online 18 July 2016
      Source:Applied Clay Science
      Author(s): Qingze Chen, Runliang Zhu, Yanping Zhu, Jing Liu, Lifang Zhu, Lingya Ma, Meng Chen
      The environmental behaviors and potential ecotoxicity of carbon nanomaterials, such as fullerene and its derivatives, are gaining ever-increasing concerns at present. This work attempts to develop an adsorbent for the effective removal of polyhydroxy fullerene (PHF) from aqueous solution, which was synthesized by modifying montmorillonite (Mt) with a branched polymer polyethylenimine (PEI). The adsorption results showed that the obtained adsorbent (i.e., PEI-Mt) could effectively remove PHF over a wide range of solution pH; both the electrostatic attraction and hydrogen-bond interaction between PHF and PEI-Mt contributed to the strong adsorption. Decreasing solution pH and rising PEI loading amount on Mt could both increase the adsorption amounts of PHF on PEI-Mt. The adsorption isotherms could be well fitted with the Langmuir model, and the calculated maximum adsorption value of PHF on 10%PEI-Mt reached ~213mg/g, much higher than that on the original Mt (~16mg/g). The adsorbents after PHF adsorption were further characterized using Fourier transform infrared spectroscopy, X-ray diffraction, and transmission electron microscopy. The results suggested that the adsorbed PHF primarily existed on the outer surfaces of PEI-Mt. This work showed that PEI-Mt can be a potentially efficient adsorbent for the removal of PHF from aqueous solution.
      Graphical abstract image

      PubDate: 2016-07-23T03:49:44Z
       
  • Removal process of nickel(II) by using dodecyl sulfate intercalated
           calcium aluminum layered double hydroxide
    • Abstract: Publication date: Available online 16 July 2016
      Source:Applied Clay Science
      Author(s): Hua Chen, Guangren Qian, Xiuxiu Ruan, Ray L. Frost
      Calcium aluminum layered double hydroxides (LDH) modified with sodium dodecyl sulfate (SDS) (Ca/Al-DS LDH) was prepared to investigate the unique removal mechanism of metal cations by organic calcium-contained LDHs. The as-prepared sample was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), inductively coupled plasma atomic emission spectrometer (ICP-AES) and elemental analysis (EA). Ni(II) was selected as the target metal cation and its removal kinetics could be well described by the pseudo-second-order kinetic model (R 2 =0.990). The maximum removal capacity of Ni(II) reached 2.45mol/g at the LDH dosage of 0.5gL−1. The XRD and element analysis results indicate that a new Ni/Al-DS LDH phase and CaCO3 were formed as well as a portion of Ca/Al-DS LDH remained in the final products after the removal process. Therefore, the removal of Ni(II) was contributed to the surface complexation, isomorphic substitution and sorption on the CaCO3. The pillared interlayer organic anions might help to keep the layered structure of LDH. This study revealed the multi-interaction mechanism of metal ions with Ca/Al LDH and proposed a novel strategy to generate organic intercalated LDHs by isomorphic substitution.
      Graphical abstract image

      PubDate: 2016-07-23T03:49:44Z
       
  • An investigation on alkali-activated Egyptian metakaolin pastes blended
           with quartz powder subjected to elevated temperatures
    • Abstract: Publication date: Available online 20 July 2016
      Source:Applied Clay Science
      Author(s): Alaa M. Rashad, Ahmed A. Hassan, Sayieda R. Zeedan
      In this study, the possibility of using quartz powder (QP) to improve the workability as well as the compressive strength of alkali-activated metakaolin (AAMK) paste before and after exposure to elevated temperatures has been investigated. Metakaolin (MK) was partially replaced with QP at levels ranging from 0% to 30% with an increment of 5%, by weight. After curing, specimens were exposed to different elevated temperatures ranging from 400°C to 1000°C with an interval of 200°C for 2h. Weight and compressive strength of specimens before and after being exposed to different elevated temperatures were thoroughly explored. The various decomposition phases formed upon exposure to temperatures were identified using X-ray diffraction (XRD)-phase characterizations and thermogravimetric (TGA)-thermal characterizations. The microstructure of the formed hydration products was determined using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The results showed that the workability as well as compressive strength before and after being exposed to elevated temperatures increased with increasing QP content. The geopolymer formulations developed in this study appeared as promising candidates for high-temperature applications refractory and fire resistant.


      PubDate: 2016-07-23T03:49:44Z
       
  • Reprint of Effect of plant growth on the occurrence and stability of
           palygorskite, sepiolite and saponite in salt-affected soils on limestone
           in South Australia
    • Abstract: Publication date: Available online 21 July 2016
      Source:Applied Clay Science
      Author(s): Melissa B. Fraser, G. Jock Churchman, David J. Chittleborough, Pichu Rengasamy
      The Mg-rich clay minerals, palygorskite, sepiolite and also Mg-smectites are generally rare in soils. When they occur they are usually concentrated in subsurface horizons and become replaced by other minerals, e.g., dioctahedral smectites in near-surface horizons. Salt-affected soils on limestone in a flat landscape in southern Australia showed patchy pasture growth, including areas in which almost no growth occurred. Chemical and mineralogical analyses of deep profiles of the soils revealed two main types and that the extent of plant growth reflected their mineralogical composition. The soil type in which plants grow well (‘Chromosol’, an Alfisol) contains dioctahedral smectite (montmorillonite and/or beidellite) but only in substantial amounts at depth. The soil type in which little or no plants grew (‘Vertosol’, a Vertisol) has substantial concentrations of a trioctahedral Mg-smectite, saponite, in its surface horizons along with dioctahedral smectite in lower horizons. Both soil types contain sepiolite and palygorskite, largely in the lower horizons of the Chromosol, but also in near-surface horizons of the Vertosol. Both types of soil also contain illite and kaolinite, which are each concentrated in the upper horizons of the soils and are considered to be detrital. The genesis of the two main types of soils can be explained by the depositional history of the basin. On the eastern side of the basin, palustrine limestone formed when the sediments became exposed, possibly from uplift. The Chromosol formed on this material. On the western side, by contrast, lacustrine sediments on lowland adjacent to a stranded beach ridge, experienced prolonged seasonal inundation by water leading to the formation of the Vertosol. This soil is strongly sodic and strongly alkaline throughout and it is concluded that the high concentration of saponite in the surface swells and thereby ensures that the soil remains wet. Together with its high pH, this soil has very poor conditions for plant growth. The persistence of the Mg-rich clay minerals, especially saponite, at the surface of the Vertosol, suggests that the relative lack of plants has preserved these minerals throughout the profile.


      PubDate: 2016-07-23T03:49:44Z
       
  • Multi-technique investigation of metakaolin and slag blended portland
           cement pastes
    • Abstract: Publication date: Available online 22 July 2016
      Source:Applied Clay Science
      Author(s): Natallia Shanahan, Ananya Markandeya, Ahmed Elnihum, Yuri P. Stetsko, A. Zayed
      Increasing incorporation of metakaolin (MK) into field concrete mixtures necessitates careful study of the portland cement/MK hydrating systems. While a number of studies have been conducted on MK blends with cement, the current knowledge on its effect on hydration products and paste microstructure remains incomplete. This study evaluated the effect of MK on the nature of hydration products through X-ray diffraction, while the effect on microstructure was assessed by measuring porosity with nitrogen adsorption and determining nanoindentation modulus as well as volume fractions of CSH with varying packing densities. The 10MK paste hydrated for 7days was compared to the plain ordinary portland cement (OPC) paste as well as to paste containing 52% slag (52SL). No significant effect was observed on the nature of hydration products with MK or SL addition. However, nitrogen-accessible porosity increased with MK and SL addition, the increase being larger with SL. The average indentation modulus for hydration products decreased with addition of MK and SL which corresponded to increasing nitrogen accessible pores.


      PubDate: 2016-07-23T03:49:44Z
       
  • Estimating the compression behaviour of metal-rich clays via a Disturbed
           State Concept (DSC) model
    • Abstract: Publication date: Available online 15 July 2016
      Source:Applied Clay Science
      Author(s): Ri-Dong Fan, Martin Liu, Yan-Jun Du, Suksun Horpibulsuk
      Many studies have been made on the compression behaviour of clay exposed to metal-rich liquids (metal-rich clay) because metal contamination of clay is found worldwide and increasingly poses as an environmental risk. However, the study on predicting the compression behaviour of contaminated clay with various metal concentrations is very limited. In this paper, a general compression model of the metal-rich clays is proposed based on a general Disturbed State Concept (DSC) compression model. A simplified form of the general model is proposed, and validated based on the compression behaviour of metal-rich clays with various metal concentrations in the pore liquid. The following conclusions are obtained in this study: (1) the simplified DSC compression model provides a practical means to estimate the compression behaviour of metal-rich clays, and it can quantify the influence of various metals on the compression behaviour of clay; (2) in the simplified DSC compression model, the influence of metal exposure can be reliably described by one parameter b, which is very useful for geotechnical engineering practice; (3) the ratio of the bulk modulus for metal-rich clays over that of the parent clay (i.e., without metal contamination) is found to be dependent on parameter b only, and that value is usually greater than 1. The highest value for the bulk modulus ratio found in this study is 2.2 for a sea water-exposed clay; and (4) two empirical equations for estimating parameter b are established. Hence the proposed model can be used for engineering estimation.


      PubDate: 2016-07-16T19:11:48Z
       
  • Reprint of Study of spatial distribution of sepiolite in
           sepiolite/polyamide6,6 nanocomposites
    • Abstract: Publication date: Available online 13 July 2016
      Source:Applied Clay Science
      Author(s): Cristina Fernandez-Barranco, Anna E. Kozioł, Krzysztof Skrzypiec, Michał Rawski, Marek Drewniak, Africa Yebra-Rodriguez
      The enhancement of the technical properties of a Clay/Polymer Nanocomposite (CPN) is related to the homogeneity and dispersion of the filler within the polymer matrix. In this work, samples of pure polyamide 6,6 (PA66) and reinforced PA66 with 1, 3, 5, 7 and 9wt.% of sepiolite have been studied. The samples have been qualitatively analyzed with different microscopy techniques and with X-Ray diffraction and scattering techniques. The images obtained by confocal microscopy show that the sepiolite is homogeneously distributed in the PA66 matrix. The micrographs taken by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that sepiolite fibres are oriented and equidistantly distributed even in the samples with high percentages of sepiolite. TEM images reveal the absence of clusters of sepiolite and good dispersion of the reinforcement within the matrix. The quantification of the dispersion, calculated from the results of Small Angle X-Ray Scattering (SAXS), indicates that the polymer chains are expanded due to the arrangement of sepiolite within the PA66 matrix and that the fibres are properly dispersed in the polymer.


      PubDate: 2016-07-16T19:11:48Z
       
  • Clay bricks added with effluent sludge from paper industry: Technical,
           economical and environmental benefits
    • Abstract: Publication date: Available online 9 July 2016
      Source:Applied Clay Science
      Author(s): Carlos Maurício F. Vieira, Regina M. Pinheiro, Ruben J. Sanchez Rodriguez, Veronica S. Candido, Sergio N. Monteiro
      Recently, it was indicated that a feasible industrial alternative to valorize the sludge obtained from the treatment of waste water effluent of paper fabrication in Europe is its use as raw material in the production of clay bricks. The present technical note is an open report, probably first in Americas, on a Brazilian industrial-scaled solution for this kind of sludge. As a novelty, the sludge was added to a mixture of clays for improved technical properties of construction bricks. Both bricks, added with 10wt% of sludge and conventional pure clay bricks for comparison, were simultaneously fired at a relatively low temperature of 750°C according to the ceramic fabrication procedure. The technical characterization was performed by linear shrinkage, water absorption and mechanical compression tests as per Brazilian standards. The brick consolidated structure was analyzed by optical microscopy. Environmental impact was evaluated by solution test and atmospheric emission by monitoring the release of SO2, NOx, TOC, CO and particulate material, according to Brazilian standards. The results showed that, owing to its composition and firing temperature, the addition of paper sludge into clay bricks contributes to a substantial reduction in price associated with a saving of 3% of fuel similar to that reported for Spanish kilns, during the industrial firing stage. The paper sludge added clay bricks attended the technical and environmental standards.


      PubDate: 2016-07-11T19:03:22Z
       
  • Determination of liquid limit of a low swelling clay using different cone
           angles
    • Abstract: Publication date: Available online 7 July 2016
      Source:Applied Clay Science
      Author(s): Nazaneen Ahmed Nasroulla, Ahmad Safuan A. Rashid, Roohollah Kalatehjari, Khairul Anuar Kassim, Norhazilan Md Noor, Suksun Horpibulsuk
      The fall cone test is one of the most popular methods used to determine the soil liquid limit. In this study, a series of laboratory tests were conducted on kaolin soil, which is considered representative of low-swelling clays, in order to determine the penetration depths for different cone parameters (angle and weight) under a liquid limit state. The required soil undrained shear strength of kaolin at liquid limit was determined using a hand-held vane shear device. Based on the analysis of the test results, the relationship between the angle of the fall cone and the ratio of undrained shear strength and fall cone penetration depth over cone weight was obtained and represented by a power function. The established relationship was then used to determine the penetration depth at liquid limit for different cone parameter values. A difference in liquid limit of less than 15% was recorded between tests using standard and alternative cone parameter values, respectively. Furthermore, a better and more reliable result was obtained when cone angles were below 90°, with a standard deviation of less than 2.5% from the standard method. Based on critical analysis of the test data, an equation with which to determine the penetration depth under a liquid limit state, as well as a one-point test method with which to determine the liquid limit for different cone parameter values are proposed for low-swelling clays.


      PubDate: 2016-07-08T12:11:46Z
       
  • Studies on hydraulic conductivity and compressibility of backfills for
           soil-bentonite cutoff walls
    • Abstract: Publication date: Available online 4 July 2016
      Source:Applied Clay Science
      Author(s): Haoqing Xu, Wei Zhu, Xuede Qian, Shengwei Wang, Xihui Fan
      Fujian standard sand (Sand-F) was used to simulate a sandy soil layer. Hebei bentonite (Bent-H) and Jiangning clay (Clay-J) were served as additives for studying the hydraulic conductivity and compressibility of sand-bentonite/clay mixture backfills. The results indicate that there is an optimum mixing content (C opt) when Bent-H or Clay-J is mixed with the Sand-F. If the content of bentonite/clay is less than C opt, hydraulic conductivity k >1.0×10−7 cm/s and porosity and coefficient of compressibility decrease with the increase of the content of bentonite/clay. While the content of bentonite/clay are greater than C opt, hydraulic conductivity k ≤1.0×10−7 cm/s and porosity and coefficient of compressibility increase with the increase of the content of bentonite/clay. As the content of bentonite/clay is less than C opt, clay minerals only fill the sand pore space without influencing the sand skeleton and porosity decreases with the increase of the content of bentonite/clay. While the content of bentonite/clay becomes greater than C opt, sand particles become disconnected and porosity increases with the increase of the content of bentonite/clay. A porosity model of sand-bentonite/clay mixtures was derived based on a micro-geometrical principle. Another equation was also developed to calculate hydraulic conductivity values with the changes of the content of bentonite/clay.


      PubDate: 2016-07-08T12:11:46Z
       
  • Layered double hydroxides decorated with Au-Pd nanoparticles to
           photodegradate Orange II from water
    • Abstract: Publication date: Available online 4 July 2016
      Source:Applied Clay Science
      Author(s): Liji Sobhana, Mohamed Sarakha, Vanessa Prevot, Pedro Fardim
      MgZnAl-Cl layered double hydroxides were prepared by co-precipitation method and further used as support to immobilize gold-palladium (Au-Pd) bimetallic nanoparticles by colloidal sol immobilization method. These materials were characterized by XRD, FT-IR, N2 adsorption desorption, TGA to verify the structure and stability of the heterostructure. The pristine LDH and Au-Pd@LDH were investigated for an environmental purpose, where photocatalytic degradation of orange II (OII) dye was studied as model reaction. The performance of support and catalyst were determined by evaluating both degradation and adsorption phenomenon. Influence of parameters such as catalyst loading and Orange II concentration were evaluated. The current study holds importance in water treatment and similar environmental protection applications.
      Graphical abstract image

      PubDate: 2016-07-08T12:11:46Z
       
  • Multi-scale study on the deformation and fracture evolution of clay rock
           sample subjected to desiccation
    • Abstract: Publication date: Available online 4 July 2016
      Source:Applied Clay Science
      Author(s): Anne-Laure Fauchille, Stephen Hedan, Valéry Valle, Dimitri Pret, Justo Cabrera, Philippe Cosenza
      The aim of this paper is to compare and discuss the values of strains and crack apertures associated with desiccation cracks measured in Tournemire clay rock at different scales (micrometer to decimeter). Experimental investigations in the laboratory were conducted on one clay rock sample subjected to a desiccation process. Two faces with dimensions of 20×20mm2 (i.e., macroscopic scale) and 5.1×4.1mm2 (i.e., mesoscopic scale) were analyzed. The induced hydric strains and desiccation cracking were monitored by digital image correlation combined with a new algorithm (H-DIC). The results were compared with the data of Hedan et al. (2014) at the gallery scale (decimeter) and those of Wang et al. (2013) at the microscopic scale (micrometer). Our laboratory study yielded the following phenomenological results. First, the displacement fields revealed the presence of sub-horizontal cracks associated with the direction of bedding planes and sub-vertical cracks, as previously observed in a gallery front in Tournemire Station. Second, when the relative humidity (RH) decreased between 98% and 33%, the crack aperture kinematics at the macroscopic scale (centimeter) was divided into three steps: (i) a phase of opening and closure, (ii) a phase of only gradual closure, and (iii) a final phase in which the desiccation cracks closed. Only phases (ii) and (iii) were observed at the mesoscopic scale (millimeter), revealing that the kinematics of cracks depends on the scale observed. The comparison of the strains at the mesoscopic and the macroscopic scales also highlights that their values depend on the study scale: the presence of cracks at the mesoscopic scale leads to a large overestimation of the values of the strains calculated at the macroscopic scale. In contrast to the observations in the laboratory, the desiccation cracks detected in the gallery systematically open when RH decreases. This difference and the differences observed in the geometrical organization of crack networks are explained by the different boundary conditions prevailing in both cases (i.e., free swelling/shrinkage in laboratory versus constrained swelling/shrinkage in the gallery). The interpretation of the entire dataset emphasizes the need for a multi-scale approach to understand and model desiccation cracking mechanisms and the associated hydric strains in clay rocks.


      PubDate: 2016-07-08T12:11:46Z
       
  • The dissolution behavior and mechanism of kaolinite in alkali-acid
           leaching process
    • Abstract: Publication date: Available online 5 July 2016
      Source:Applied Clay Science
      Author(s): Hao Wang, Qiming Feng, Kun Liu
      Kaolinite is a typical silicate impurity in microcrystalline graphite ore. Removal of kaolinite from graphite ores is important to achieve high purity graphite product. Alkali-acid leaching is effective to remove silicate impurity in microcrystalline graphite. For in-depth understanding of phase transformation of kaolinite in microcrystalline graphite purification process, dissolution behavior and mechanism in alkali-acid leaching process were studied in this paper. As shown in alkali-acid leaching tests and analyses (FTIR, XRD, and SEM-EDS), silicon extraction of kaolinite was mainly affected by sodium hydroxide concentration, alkali-leaching temperature, and alkali-leaching time. The dissolution mechanism of kaolinite was regarded as a three-stage process: kaolinite firstly dissolved in alkaline solution in form of soluble silicate and aluminate. Dissolved silicate and aluminate in alkaline solution then reacted with each other and aluminosilicate transient phase with Si/Al≈1 precipitated when silicon ion concentration exceeded its equilibrium concentration. Finally, the aluminosilicate precipitate composed of nepheline and sodalite dissolved in hydrochloric acid solution. As a consequence, kaolinite dissolved completely in alkali-acid leaching process.


      PubDate: 2016-07-08T12:11:46Z
       
  • Correlating illite (Kübler) and chlorite (Árkai)
           “crystallinity” indices with metamorphic mineral zones of the
           South Island, New Zealand
    • Abstract: Publication date: Available online 5 July 2016
      Source:Applied Clay Science
      Author(s): Laurence N. Warr, Simon C. Cox
      Measuring clay mineral “crystallinity” by the illite “Kübler” or chlorite “Árkai” index has long been used to determine the metamorphic grade of pelitic metasedimentary rocks by recognition of the anchizone: a transitional state of regional metamorphism lying between diagenetic and low-grade metamorphic conditions. Originally defined by B. Kübler on the basis of clay mineral paragenesis, the application of the anchizone as a metamorphic tool has remained ambiguous partly due to inconsistencies in the standardization of the method and partly due to the lack of reliable correlations with well accepted metamorphic zones assemblages. In this study, 54 pelitic samples were analyzed from localities of defined mineral facies from the well-studied rocks of the South Island of New Zealand. Standardized Kübler and Árkai indices are presented for this sample suite using the widely applied standardized Crystallinity Index Scale (CIS) of measurement, and employing the new Frey-Kübler equivalent upper and lower boundary limits of the anchizone at 0.32 and 0.52°2θ. The results presented indicate that 76–78% of both Kübler index and Árkai index values correspond with the expected mineral facies when the epizone is taken to correspond to both the greenschist (chlorite-zone) and pumpellyite-actinolite facies, the anchizone to the prehnite-pumpellyite facies and the diagenetic zone to the zeolite facies. This good correspondence between Kübler and Árkai index values and metamorphic mineral zones confirms that clay “crystallinity” indices provide a useful method for mapping regional grades of low temperature metamorphism and the general state of cleavage development. Its effectiveness is, however, dependent on appropriate standardization to an internationally recognized scale of clay mineral “crystallinity” measurement, and implementation of true Kübler-equivalent anchizone boundary limits. The consistent variations between illite and chlorite “crystallinities” observed for the studied pelites of southern New Zealand, as defined on Kübler - Árkai index correlation plots, is suggested to reflect variations in the activities of K+, Fe2+ and Mg2+ in the metamorphic pore fluid.


      PubDate: 2016-07-08T12:11:46Z
       
  • Adsorption of phosphate by acid-modified fly ash and palygorskite in
           aqueous solution: Experimental and modeling
    • Abstract: Publication date: Available online 7 July 2016
      Source:Applied Clay Science
      Author(s): Feihu Li, Wenhao Wu, Renying Li, Xiaoru Fu
      In this study, a class F fly ash and palygorskite have been acid-modified and then evaluated for the adsorption of phosphate in aqueous solution via bench-scale batch experiments. XRD, XRF, SEM, and FTIR were employed to characterize the acid-modified fly ash (MFA) and palygorskite (MPal). Both MFA and MPal show enhanced phosphate adsorption after the modification treatment. The effects of pH, adsorbent dosage, and co-ions on phosphate adsorption, as well as adsorption thermodynamics and kinetics, and leaching features of spent (used) adsorbents were also investigated. The isotherms data fit well with the Langmuir model rather than the Freundlich model, giving maximum capacities (298K) of 13.3mg P g−1 for MFA and 10.5mg P g−1 for MPal, respectively. Surface complexation modeling of P adsorption data with the nonelectrostatic generalized composite (GC) approach indicates that phosphate were directly bound to the metal centers by ligand exchange to form two monodentate complexes, ≡SHPO4 − and ≡SPO4 2−. The GC model appears to be an easy and efficient tool to provide an insight into the mechanism of phosphate adsorption on complex adsorbents with limited model parameters. Leaching test results suggest that the spent adsorbents can be safely disposed or further reused.
      Graphical abstract image

      PubDate: 2016-07-08T12:11:46Z
       
  • Montmorillonite-supported with Cu2O nanoparticles for damage and removal
           of Microcystis aeruginosa under visible light
    • Abstract: Publication date: Available online 2 July 2016
      Source:Applied Clay Science
      Author(s): Na Gu, Jinlong Gao, Heng Li, Yunxia Wu, Yulin Ma, Kuitao Wang
      The montmorillonite supported with Cu2O nanoparticles was prepared by reduction of Cu2+ absorbed by montmorillonite using glucose and ethylene glycol as reductant. X-ray diffraction and IR spectrum depicted the maintenance of the host structure of montmorillonite and the presence of crystallite Cu2O nanoparticles. X-ray diffraction and transmission electron microscopy demonstrated the Cu2O nanoparticles were either intercalated into the interlayer space of montmorillonite or dispersed homogeneously on the surface of montmorillonite, and the size of Cu2O nanoparticles were varying from 5 to 10nm. Energy dispersive X-ray showed the loading amount of Cu2O in montmorillonite interlayer was around 26.31%. Cu2O-montmorillonite was used for adsorbent, flocculant and photocatalyst to remove Microcystis aeruginosa, removing 90.4% of M. aeruginosa in 3h under visible light. The synergy of adsorption-flocculation and photocatalysis of Cu2O-montmorillonite promoted the aggregation of M. aeruginosa and then the cell damage mainly associated with cell membrane attack and inclusion degradation by photocatalysis of Cu2O, leading to the inhibition of physiological activity of M. aeruginosa. Cu2O-montmorillonite was an effective algae removal material for the emergency control of cyanobacteria bloom.
      Graphical abstract image

      PubDate: 2016-07-04T11:01:22Z
       
  • Purification of greywater by a moving bed reactor followed by a filter
           including a granulated micelle-clay composite
    • Abstract: Publication date: Available online 2 July 2016
      Source:Applied Clay Science
      Author(s): Nadya Rakovitsky, Ilya Brook, Jaap Van Rijn, Mark Ryskin, Zanele Mkhweli, Hanoch Etkin, Shlomo Nir
      Reuse of grey water (GW) enables to reduce fresh water consumption, but a treatment is required to prevent potential transmission and propagation of pathogenic organisms. This study presents results on the removal of pathogenic bacteria from GW as well as reduction of turbidity, TSS COD, and BOD by a novel treatment system. Compared to previous studied methods, three new elements are presented in the current treatment of GW: (1) A granulated complex of micelles of the organic cation octadecyltrimethylammonium (ODTMA) with montmorillonite was employed in filtration of GW. This complex was efficient in purifying GW due to its large surface area, positive charge and existence of hydrophobic domains. The granulated complex enabled flow when present exclusively in the filter; (2). A moving bed reactor for decomposition of part of the organic matter in the GW. This pretreatment stage, prior to the micelle-clay filter, was also efficient in removing pathogenic bacteria; (3) A regeneration stage of the micelle-clay filter conducted by passing either dilute solutions of Na-hypochlorite or HCl through the micelle-clay complex, or by heating the complex. Incubation of GW for either two weeks or one day in the pretreatment stage yielded a 10- and 7-fold enhancement in the volume filtered, which did not contain fecal coliforms, i.e., 300 and 210L for 40g of complex, respectively. The capacity of purified volume per gram of the complex increased further several-fold (>23L/g) for filters filled exclusively with granules. Regeneration of the complex in the filter further enhanced the capacity.
      Graphical abstract image

      PubDate: 2016-07-04T11:01:22Z
       
  • Development and evaluation of halloysite nanotube-based carrier for
           biocide activity in construction materials protection
    • Abstract: Publication date: Available online 2 July 2016
      Source:Applied Clay Science
      Author(s): Paola Scarfato, Elvira Avallone, Loredana Incarnato, Luciano Di Maio
      In this study, it was developed a natural halloysite nanotube-based carrier with biocide activity for construction materials protection. The obtained active system has been characterized and tested as co-formulating agent in mortars, in order to evaluate its stability and its effect on mortar properties, in terms of antimicrobial activity, water entrance resistance and aesthetic appearance. The mortar containing the biocide-loaded nanotubes showed prolonged resistance to microbiological growth, after natural contamination by exposure to outdoor conditions, and reduced water capillary absorption. This demonstrated the potential of the formulated active nanocarrier to reduce the bioreceptivity of the mortar substrate over a period of almost two years and to improve its durability.


      PubDate: 2016-07-04T11:01:22Z
       
  • Suitability of soils and river deposits from Marrakech for the
           manufacturing of earthenware
    • Abstract: Publication date: August 2016
      Source:Applied Clay Science, Volume 129
      Author(s): Hicham El Boudour El Idrissi, Lahcen Daoudi, Meriam El Ouahabi, Achille Balo Madi, Frédéric Collin, Nathalie Fagel
      This paper investigates the suitability of clayey materials originating from semi-arid soil and river sediments, used by potters in the Agafay region for the manufacture of ceramic products. The clay samples were subjected to particle-size analysis, X-ray diffraction and X-ray fluorescence to investigate their physical, mineralogical and chemical characteristics respectively. The physical behaviour of the intermediate products was studied at the shaping and drying stages of the ceramics manufacturing process through the Atterberg limits and the plot of the Bigot curve respectively. The final product characteristics were determined through porosity tests, flexural and compressive strengths tests. Based on results obtained, the raw materials turn out to be suitable characteristics for the manufacture of earthenware products. The application of the suggested recommendations is worthy for the improvement of the products based on such raw materials.


      PubDate: 2016-06-16T18:00:57Z
       
  • Fe3+ in pottery: Distinction of the use for cooking and production
           parameters
    • Abstract: Publication date: August 2016
      Source:Applied Clay Science, Volume 129
      Author(s): G.M. Mangueira, S. Teixeira, F.A. Silva, R.W.A. Franco
      The estimated firing temperature and atmosphere in which a piece of pottery was produced can be identified by comparing the concentration of Fe3+ between the piece of pottery and clay with a similar chemical composition that were subjected to identical thermal treatments. This procedure was applied to modern pottery donated by indigenous people and to a set of archaeological pottery. The modern pottery that was used for cooking for two years exhibited higher Fe3+ concentrations than the clay that was fired at any temperature; thus, the parameters of production were not identified in this pottery. The same procedure can be used to identify the use of a piece of pottery as a pan. Of the set of 14 pieces of archaeological pottery examined in this study, 12 were able to have their production parameters identified, and 2 fragments were identified with Fe3+ concentrations that were higher than that of the fired clay, suggesting that these pieces were used as pans. The results of this study indicate that the concentration of Fe3+ can be used to determine if a piece of pottery was used for cooking; additionally, if a piece of pottery was not used for cooking, then the proposed method can identify the parameters of the piece of pottery's production.
      Graphical abstract image

      PubDate: 2016-06-16T18:00:57Z
       
  • Influence of pore fluid concentration on water retention properties of
           compacted GMZ01 bentonite
    • Abstract: Publication date: August 2016
      Source:Applied Clay Science, Volume 129
      Author(s): Y. He, W.M. Ye, Y.G. Chen, B. Chen, B. Ye, Yu-Jun Cui
      Due to its low hydraulic conductivity, high swelling capacity and good adsorption properties, the Gaomiaozi (GMZ) bentonite has been proposed as a suitable buffer/backfill material for the construction of artificial barriers in a deep geological repository for the disposal of high-level nuclear waste (HLW) in China. Compacted GMZ01 bentonite with an initial dry density of 1.70g/cm3 was hydrated with distilled water and NaCl solutions. The swelling strain was recorded. After being saturated, suction-controlled drying tests were conducted and corresponding soil water retention curves were obtained. MIP investigations were conducted on the void ratio variation of a specimen before and after experiencing wetting and drying processes. Results show that the swelling strain of compacted GMZ01 bentonite decreases as the concentration of infiltration solution increases. The shrinkage curve of saturated compacted GMZ01 bentonite specimens evolves with controlling suctions and could be divided into three stages including a normal shrinkage stage, a residual shrinkage stage and a zero shrinkage stage. For a given suction, the measured void ratio of a specimen saturated with distilled water is slightly larger than those of specimens saturated with salt solutions after the drying equilibrium is reached. For a given suction, the degree of saturation of a compacted GMZ01 bentonite specimen increases as the salt concentration increases. According to the test results, a modified SWRC equation was proposed to account for the effect of void ratio and salt solutions on drying behaviour. The verified results revealed that the proposed equation can satisfactorily describe the SWRCs of compacted GMZ01 bentonite saturated with different solutions.


      PubDate: 2016-06-16T18:00:57Z
       
  • Properties and pozzolanic reactivity of flash calcined dredging sediments
    • Abstract: Publication date: August 2016
      Source:Applied Clay Science, Volume 129
      Author(s): Ruben Snellings, Özlem Cizer, Liesbeth Horckmans, Paweł T. Durdziński, Philippe Dierckx, Peter Nielsen, Koenraad Van Balen, Lucie Vandewalle
      Dredging of ports, harbours and waterways generates vast amounts of sediments that find few applications and need to be disposed of. In the port of Antwerp, Belgium, each year 450,000t (dry matter) of dredging sediments are mechanically dewatered and stockpiled. This paper investigates flash calcination of the clay-rich dredged sediments as a sustainable solution to develop novel pozzolanic supplementary cementitious materials (SCM) for blended cement.


      PubDate: 2016-06-16T18:00:57Z
       
  • Cu-Mg-Al hydrotalcite-like materials as precursors of effective catalysts
           for selective oxidation of ammonia to dinitrogen — The influence of
           Mg/Al ratio and calcination temperature
    • Abstract: Publication date: August 2016
      Source:Applied Clay Science, Volume 129
      Author(s): Sylwia Basąg, Zofia Piwowarska, Andrzej Kowalczyk, Agnieszka Węgrzyn, Rafał Baran, Barbara Gil, Marek Michalik, Lucjan Chmielarz
      Hydrotalcite originated Cu-Mg-Al mixed metal oxides were studied as catalysts for selective oxidation of ammonia to dinitrogen. Cu-Mg-Al hydrotalcite-like materials with copper content of 5mol% and various molar Mg/Al ratios were synthetized by coprecipitation method and then calcined at 600, 700 and 800°C. It was shown that both Mg/Al ratio as well as calcination temperature are very important synthesis parameters determining selectivity of the studied catalysts in ammonia oxidation process. The catalysts with lower Mg/Al ratio, so higher Al content, were more selective to dinitrogen. Moreover, it was shown that an increase in calcination temperature also resulted in the catalysts with a significantly improved selectivity to dinitrogen. These interesting effects were related to the formation of the Cu-containing spinel phases, which possibly are responsible for high selectivity to dinitrogen in the high temperature range.
      Graphical abstract image

      PubDate: 2016-06-16T18:00:57Z
       
  • Kinetics, isotherms and multiple mechanisms of the removal for phosphate
           by Cl-hydrocalumite
    • Abstract: Publication date: August 2016
      Source:Applied Clay Science, Volume 129
      Author(s): Yunsheng Jia, Huoyan Wang, Xuesong Zhao, Xiaowei Liu, Yiliu Wang, Qunlong Fan, Jianmin Zhou
      A laboratory study was conducted to evaluate phosphate removal from aqueous solutions by a CaAl-Cl layered double hydroxide (Cl-hydrocalumite). Cl-hydrocalumite was prepared by co-precipitation and was characterized by scanning electron microscopy equipped with energy-dispersive spectrometer (SEM-EDS), powder X-ray diffraction (PXRD), and Fourier transform infrared (FTIR). SEM demonstrated that a crystalline structure was synthesized and PXRD or FTIR spectra revealed that the structure was Cl-hydrocalumite. Adsorption experiments were performed as a function of contact time and initial phosphate concentration. Phosphate adsorption reached equilibrium within 10h, followed by a pseudo-second-order kinetic model with R2 =0.999. The experimental data followed the Langmuir and Fedlich-Peterson isotherm models, and showed a maximum adsorption capacity of ~182.5mgg−1. The Freundlich constant n=3.18>1, represented a favorable phosphate adsorption process. SEM-EDS, PXRD, and FTIR analyses of P-hydrocalumite (after adsorption) were used to elucidate adsorption mechanisms. EDS results indicated that chloride was topotactic, exchanged by phosphate to generate P-hydrocalumite, and partial Cl-hydrocalumite was dissolved. The PXRD and FTIR spectra indicate that P-hydrocalumite was a mixture with a new precipitate, brushite. Phosphate adsorption by Cl-hydrocalumite was topotactic anion exchange combined with dissolution–precipitation. Cl-hydrocalumite was a cost-effective and excellent phosphate adsorbent.
      Graphical abstract image

      PubDate: 2016-06-16T18:00:57Z
       
  • Study on synthesis and characterization of ZSM-20 zeolites from
           metakaolin-based geopolymers
    • Abstract: Publication date: August 2016
      Source:Applied Clay Science, Volume 129
      Author(s): Qing Tang, Yan He, Yi-pin Wang, Kai-tuo Wang, Xue-min Cui
      This paper presents a novel method for the synthesis of ZSM-20 zeolites. This method based on in situ transformation from a metakaolin-based geopolymer gel is more effective than the traditional hydrothermal method. The crystalline phase, micromorphology and microstructure of the geopolymers and the ZSM-20 zeolite samples were investigated using SEM, XRD and an N2 adsorption apparatus. The experimental results showed that pure ZSM-20 zeolite crystals were obtained without any by-product and with a large BET surface area of 78.52m2/g under optimal conditions. Key factors of the in situ transformation process were studied, such as the alkalinity of the geopolymer gel, the curing conditions and the hydrothermal conditions. The optimum observed conditions were as follows: the modulus of sodium silicate solution (SiO2/Na2O molar ratio) was 1.1, H2O/Na2O molar ratio=7.5, the geopolymers should be cured at 40°C for 3days, and the hydrothermal conditions should be kept at 140°C for 10h.


      PubDate: 2016-06-16T18:00:57Z
       
  • Correlation between chemical and mineralogical characteristics and
           permeability of phyllite clays using multivariate statistical analysis
    • Abstract: Publication date: August 2016
      Source:Applied Clay Science, Volume 129
      Author(s): E. Garzón, E. Romero, P.J. Sánchez-Soto
      Phyllite clays are applied as a layer on a surface to be waterproofed and subsequently compacted. For this purpose, phyllite clays deposits can be grouped by their chemical and mineralogical characteristics, and these characteristics can be connected with their properties, mainly permeability, in order to select those deposits with the lowest permeability values. Several deposits of phyllite clays in the provinces of Almería and Granada (SE Spain) have been studied. The results of applying a multivariate statistical analysis (MVA) to the chemical data analysed from 52 samples determined by XRF, mineralogical analysis by XRD and permeability are reported. Permeability, a characteristic physical property of phyllite clays, was calculated using the results for experimental nitrogen gas adsorption and nitrogen adsorption-desorption permeability dependence. According to the results, permeability values differentiated two groups, i.e. group 1 and group 2, with two subgroups in the latter. The influence of chemical as well as mineralogical characteristics on the permeability values of this set of phyllite clays was demonstrated using a multiple linear regression model. Two regression equations were deduced to describe the relationship between adsorption and desorption permeability values, which support this correlation. This was an indication of the statistical significance of each chemical and mineralogical variable, as it was added to the model. The statistical tests of the residuals suggested that there was no serious autocorrelation in the residuals.


      PubDate: 2016-06-16T18:00:57Z
       
  • Kinetics and thermodynamic analysis of the adsorption of hydroxy-Al
           cations by montmorillonite
    • Abstract: Publication date: August 2016
      Source:Applied Clay Science, Volume 129
      Author(s): Guifang Wang, Xin Su, Yuyan Hua, Shaojian Ma, Jing Wang, Xiaoqiang Xue, Qi Tao, Sridhar Komarneni
      Hydroxy-Al pillaring agent was prepared and used to modify montmorillonite (Mt), and the effects of temperature, initial Al3+ concentration and contact time were investigated by using a batch technique. The results showed that the uptake of Al13 by Mt increased with increasing temperature, initial Al3+ concentration and contact time. The adsorption equilibrium was achieved in 12h as determined by kinetics. The adsorption kinetics demonstrated that the adsorption of Al13 by Mt followed the pseudo-second-order kinetic model. The adsorption isotherms at the temperatures of 40, 60, 80 and 90°C were determined and simulated using Langmuir, Freundlich and Redlich-Peterson models. The three kinds of isotherms could represent the experimental data well. The specific surface areas and pillar density increased while the total porous volumes slightly decreased with increasing Al3+ concentrations. The XRD result showed that adsorbed Al13 ions were located in the Mt interlayer spaces through monolayer adsorption. Thermodynamic analysis of adsorption process showed that the adsorption of Al13 by Mt was spontaneous, endothermic with increasing disorder during the adsorption process and mainly physical in nature.
      Graphical abstract image

      PubDate: 2016-06-16T18:00:57Z
       
  • Photocatalytic degradation of phenol using MgAlSn hydrotalcite-like
           compounds
    • Abstract: Publication date: August 2016
      Source:Applied Clay Science, Volume 129
      Author(s): Sonia Mancipe, Francisco Tzompantzi, Hugo Rojas, Ricardo Gómez
      MgAl Layered Double Hydroxides (LDH) with molar ratio Mg/Al=3 and MgAlSn containing 5, 10 and 15wt% of tin were synthesized by the co-precipitation method. The solids were characterized by X-ray diffraction (XRD), N2 sorption, infrared spectroscopy (FTIR), Scanning Electron Microscopy coupled to a detector for energy dispersive X-ray spectroscopy microanalysis (SEM/EDS), Transmission Electron Microscopy (TEM) and UV–Vis spectroscopy (UV–Vis) in order to determine the crystalline structure, textural properties, vibrational modes of the LDH, morphology and tin content, as well as the band gap of the solids. The photocatalytic behaviors of synthesized materials were tested in phenol degradation under UV irradiation. The results showed that MgAlSn 15% present the highest activity with 80% degradation of the contaminant molecule after 3hours of exposure to light.
      Graphical abstract image

      PubDate: 2016-06-16T18:00:57Z
       
  • Microbial metabolism in bentonite clay: Saturation, desiccation and
           relative humidity
    • Abstract: Publication date: August 2016
      Source:Applied Clay Science, Volume 129
      Author(s): W. Stone, O. Kroukamp, J. McKelvie, D.R. Korber, G.M. Wolfaardt
      Within a Deep Geological Repository for used nuclear fuel storage, compacted bentonite clays are the candidate buffer due to their physical and rheological properties, and their ability to suppress microorganisms. This study focused on the potential for microbial metabolism at bentonite-air interfaces, the influence of relative humidity (RH) and the consequences of metabolic activity on bentonite. Microbial activity, determined by monitoring the concentration of evolved CO2, was sustained at desiccated bentonite-air interfaces at 75% RH (0.6ppm CO2/min after 5days of dessication) but was completely suppressed at 30% RH. Conversely, microbial survival was promoted in dry bentonite, with culturable cell survival up to 3 times higher at lower RH (30%) than higher RH (75%). It was also shown that, under water-saturated conditions, microbial sulphur reduction decreased the clay swell index of uncompacted bentonite, swelling approximately 2.7cm/(g dry weight) less than controls. Notably, natural groundwater salinities were shown adequate to suppress all microbial activity under both saturated and desiccated conditions, confirming that a combination of high bentonite dry density and high salinity inhibits microbial activity, even in microenvironments like surface-air interfaces where swelling pressure limitations may be transiently compromised. Along with the applied need for this knowledge, this study also provided a fundamental opportunity to explore microbial activity in desiccated environments, and suggests that lower RH may promote rapid entry into a dormant cell state and thus more effective long-term adaptation.


      PubDate: 2016-06-16T18:00:57Z
       
  • Effects of imperfect interfacial adhesion between polymer and
           nanoparticles on the tensile modulus of clay/polymer nanocomposites
    • Abstract: Publication date: August 2016
      Source:Applied Clay Science, Volume 129
      Author(s): Yasser Zare
      This work investigates the effects of incomplete interfacial adhesion between polymer and nanoparticles on the predicted tensile modulus of clay/polymer nanocomposites (CPNs). The Halpin-Tsai and Hui-Shia models which assume the perfect interfacial adhesion commonly overpredict the modulus in CPN. Accordingly, the samples include imperfect interfacial bonding at polymer-filler interface. In this condition, the effective aspect ratio and volume fraction of nanoclay are defined using “L c ” as the essential distance for the normal stress to reach the clay strength and “τ” as the interfacial shear strength. The values of “L c ” and “τ” are calculated for several samples and also, their roles in the predicted modulus are determined. It is shown that low “L c ” and high “τ” result in a significant modulus, because they indicate the great levels of interfacial properties in CPN. Also, the large and thin platelets can produce a high modulus depending to the level of Interfacial parameters.


      PubDate: 2016-06-16T18:00:57Z
       
  • Gas permeability evolution mechanism during creep of a low permeable
           claystone
    • Abstract: Publication date: August 2016
      Source:Applied Clay Science, Volume 129
      Author(s): Z.B. Liu, J.F. Shao, T.G. Liu, S.Y. Xie, N. Conil
      Clayey rocks, due to its low permeability and self-sealing ability, have been selected as a privilege candidate host rock for underground radioactive waste repository in many countries. The gas permeability evolution is very sensitive to the deformation process in such rocks and can be used as a good indicator of microstructure changes such as the growth of micro-cracks. In this work, the mechanism of gas permeability evolution in the Callovo-Oxfordian (Cox) claystone during a creep deformation is investigated. Firstly, multi-step creep tests with different confining pressures are carried out to characterize gas permeability evolutions under different levels of the deviatoric stress. Secondly, in order to minimize effects of multiple deviatoric loading steps, one-step creep tests are also realized. Throughout all creep tests, the gas permeability is measured by a transient pulse decay method in together with the axial and radial strains. It is first found that the gas permeability of the claystone significantly decreases with the confining pressure or hydrostatic stress. The gas permeability in multi-step creep tests can exhibit a four-stage evolution with the progressive increase of deviatoric stress level, composed of a rapid decrease, a gentle decrease, a gentle increase and a rapid increase. However, the gas permeability is continuously decreasing during one-step creep tests. The permeability change in a one-step creep test can be well correlated with the volumetric strain variation by a logarithmic function. Effects of loading orientation with respect to claystone bedding planes are also investigated.


      PubDate: 2016-06-16T18:00:57Z
       
  • Mechanism of intercalation of polycarboxylate superplasticizer into
           montmorillonite
    • Abstract: Publication date: August 2016
      Source:Applied Clay Science, Volume 129
      Author(s): Hongbo Tan, Benqing Gu, Baoguo Ma, Xin Li, Chaoliang Lin, Xiangguo Li
      It is well known that polycarboxylate superplasticizer (PC) has a poor clay tolerance, due to huge adsorption amount caused by clay minerals, especially by montmorillonite (Mt). The aim of the paper is to study the mechanism of the interaction of Mt and PC. AA-MA was synthetized by acrylic acid (AA) and methyl acrylate (MA), and PC was synthetized by AA and isopentenol polyoxyethylene ether (TPEG). X-ray Diffractometry (XRD), Transmission Electron Microscopy (TEM), Fourier-transform Infrared Spectroscopy (FTIR), Thermo Gravimetric Analysis (TGA), X-ray Photoelectron Spectroscopy (XPS) and Nuclear Magnetic Resonance (NMR) were used to discuss the structure of the Mt intercalated by polymers including TPEG, AA-MA and PC. The results show that: AA-MA, which is the main chain of PC without long side chain of polyethylene oxide (PEO), only adsorbs on the surface of Mt particles, and it cannot be intercalated into interlayer space of Mt. TPEG containing PEO, the long side chain of PC, can be easily inserted into the interlayer space. Furthermore, it is proved that not the whole molecular but only the long side chain PEO of PC is intercalated into interlayer space, which is the main reason for its huge adsorption amount and less efficient dispersing ability in cement-Mt paste. The results suggest a possibility that those salts or polymers that can preferentially insert into interlayer space of Mt can be utilized to impede the intercalation of the long side chain of PC and improve the clay tolerance of PC.


      PubDate: 2016-06-16T18:00:57Z
       
  • BiVO4/Fe/Mt composite for visible-light-driven degradation of acid red 18
    • Abstract: Publication date: August 2016
      Source:Applied Clay Science, Volume 129
      Author(s): Tianyuan Xu, Runliang Zhu, Jianxi Zhu, Xiaoliang Liang, Yun Liu, Yin Xu, Hongping He
      This work described a strategy for loading bismuth vanadate (BiVO4) on hydroxy-iron pillared montmorillonite (Fe/Mt), in which vanadate and bismuth were successively loaded on Fe/Mt to synthesize a BiVO4/Fe/Mt composite with high photo-Fenton catalytic activity. The structural characteristics of the resulting materials were studied using X-ray diffraction, inductively coupled plasma mass spectrometry, nitrogen adsorption–desorption isotherms, and UV–vis diffuse reflectance spectra. Then, the photo-Fenton catalytic activity of the obtained catalysts was tested using acid red 18 (AR18) as a model contaminant under visible light irradiation. Furthermore, the concentration of hydroxyl radical (OH) was studied by high performance liquid chromatography. The results indicated that BiVO4 loaded not only on the outer surface but also into the interlayers of Fe/Mt. The 8%BiVO4/Fe/Mt composite exhibited high photocatalytic activity, and the decolorization efficiency, TOC removal efficiency of AR18, and the production of OH by BiVO4/Fe/Mt were higher than those by Fe/Mt. The high removal efficiency of AR18 and remarkable OH generation performance by BiVO4/Fe/Mt should be attributed to the presence of BiVO4, which can accelerate the reduction of Fe3+ to Fe2+ by providing photo-induced electrons from BiVO4. In addition, the leached amount of Fe from BiVO4/Fe/Mt was 0.32mg/L after 180min reaction, much smaller than that from Fe/Mt (0.66mg/L). The results of this work suggest that the introduction of semiconductor materials may be a feasible way for enhancing the photo-Fenton catalytic activity of heterogeneous photo-Fenton catalysts.
      Graphical abstract image

      PubDate: 2016-06-16T18:00:57Z
       
  • Montmorillonite modified with lactim methyl ethers having different ring
           sizes
    • Abstract: Publication date: August 2016
      Source:Applied Clay Science, Volume 129
      Author(s): Lenka Malinová, Daniel Jaksch, Jiří Brožek
      A series of organically modified montmorillonites (organo-montmorillonites) was prepared by the method of cation exchange using hydrochlorides of lactim methyl ethers derived from cyclic amides (lactams) with varying ring size (five- to thirteen-membered). The content of the organic modifier was determined from the carbon content (elemental analysis) and using the thermogravimetric analysis. The intercalation of lactim methyl ethers into the interlayer space of the aluminosilicate was confirmed by the FTIR spectroscopy. The interlayer distance determined by the X-ray diffraction increased with increasing ring size and was correlated to the values obtained for montmorillonite intercalated by ω-aminoacids derived from lactams. Suitability of montmorillonites organophilized in this way for a preparation of nanocomposites of polyamide6 by in situ intercalation was tested by their swelling in the ε-caprolactam melt. Due to the penetration of the monomer into the interlayer space of the organophilized montmorillonite, the interlayer distance further increased.
      Graphical abstract image

      PubDate: 2016-06-16T18:00:57Z
       
  • Enhanced visible-light photocatalytic activity of kaolinite/g-C3N4
           composite synthesized via mechanochemical treatment
    • Abstract: Publication date: August 2016
      Source:Applied Clay Science, Volume 129
      Author(s): Zhiming Sun, Guangyuan Yao, Xueyui Zhang, Shuilin Zheng, Ray L. Frost
      A novel kaolinite/g-C3N4 (KA/CN) composite with enhanced visible light-driven photocatalytic activity was prepared through a simple mechanochemical method. The microstructure and interface properties of the obtained nanocomposites were characterized by X-ray diffraction (XRD), surface area measurement (BET), Fourier transform infrared spectroscopy (FTIR), high resolution scanning electron microscope (HR-SEM), energy dispersive X-ray spectroscopy (EDS), UV–visible diffused reflectance spectroscopy (UV–vis DRS) and photoluminescence spectroscopy (PL). It is indicated that g-C3N4 and kaolinite coexisted in the composite photocatalysts. Compared with the single g-C3N4 or kaolinite and kaolinite/g-C3N4 physical mixtures, the as-synthesized KA/CN composites exhibited significantly enhanced photocatalytic activity after mechanochemical treatment under visible-light irradiation, which was almost 4.0 times that of the pure g-C3N4. The enhanced photocatalytic activity of the kaolinite/g-C3N4 composite could be attributed not only to its high adsorption capacity but also to the synergistic effects between g-C3N4 and kaolinite, effectively reducing the recombination probability of photogenerated electron-hole pairs.


      PubDate: 2016-06-16T18:00:57Z
       
  • Effect of plasma treatment on structure and surface properties of
           montmorillonite
    • Abstract: Publication date: August 2016
      Source:Applied Clay Science, Volume 129
      Author(s): P. Čapková, J. Matoušek, J. Rejnek, N. Bendlová, J. Pavlík, M. Kormunda, L. Šplíchalová, V. Pilařová
      Plasma treatment of montmorillonite has been investigated as a prerequisite for design of functional nanostructures, based on clay minerals. The effect of short-term (20s) plasma treatment on structure and bonding of montmorillonite has been analyzed using combination of X-ray powder diffraction and infrared spectroscopy. Results showed that dehydration starts at low discharge power 10W and at 50W is completed. The effect of the plasma treatment was compared to the effect of the heat treatment (8h at 450°C). Both treatments can be considered as similar when dehydration takes place. However, the dehydroxylation does not seem to be triggered by the plasma treatment. Therefore for dehydration only, the plasma treatment can be used instead of much more energy consuming thermal treatment.


      PubDate: 2016-06-16T18:00:57Z
       
  • Editorial Board
    • Abstract: Publication date: August 2016
      Source:Applied Clay Science, Volume 129




      PubDate: 2016-06-16T18:00:57Z
       
  • An evaluation of palygorskite inclusion on the growth performance and
           digestive function of broilers
    • Abstract: Publication date: August 2016
      Source:Applied Clay Science, Volume 129
      Author(s): Yueping Chen, Yefei Cheng, Weili Yang, Xiaohan Li, Chao Wen, Wenbo Wang, Aiqin Wang, Yanmin Zhou
      Palygorskite (Pal), a natural non-toxic silicate clay mineral with abundant resource reserve on the Earth, has received increasing attention in animal nutrition either as an efficient and safe feed additive or ingredient to promote the growth of animals. The current study was conducted to evaluate the effects of Pal supplementation on the growth performance and digestive function of broilers. 144 one-day-old Arbor Acres broiler chicks were allocated into 3 dietary treatments consisting of 6 replicates with 8 chicks each. Birds in the 3 treatments were given a basal diet supplemented with 0, 0.5mass% and 1.0mass% of Pal for 42days, respectively. The broilers fed diets containing either 0.5mass% or 1.0mass% Pal showed similar growth performance to those given the basal diet. Compared with the control group, the relative weight of the pancreas was increased by Pal inclusion at 42days. 1.0mass% Pal supplementation increased nitrogen retention and organic matter digestibility of broilers during 32 to 34days. Similarly, 0.5mass% Pal inclusion significantly enhanced pancreatic and jejunal lipase activity at 21days. In addition, birds fed diet supplemented with 1.0mass% Pal showed a higher level of jejunal trypsin activity at 42days compared with the control group. The results indicated that dietary Pal supplementation could enhance relative weight of pancreas, nitrogen retention and organic matter digestibility (1.0mass% Pal only), and the activities of digestive enzymes of broilers, which may account for the similar growth performance.


      PubDate: 2016-06-16T18:00:57Z
       
  • Editorial Board
    • Abstract: Publication date: July 2016
      Source:Applied Clay Science, Volumes 127–128




      PubDate: 2016-05-13T04:33:24Z
       
  • Functional magnetic nanoparticle/clay mineral nanocomposites: preparation,
           magnetism and versatile applications
    • Abstract: Publication date: July 2016
      Source:Applied Clay Science, Volumes 127–128
      Author(s): Liang Chen, Chun Hui Zhou, Saverio Fiore, Dong Shen Tong, Hao Zhang, Chun Sheng Li, Sheng Fu Ji, Wei Hua Yu
      Clay minerals and magnetic nanoparticles (MNP) combine to form a class of advanced nanocomposites that would possess exceptional magnetism, stability, adsorption, catalysis, and biocompatibility. This review summarizes and examines recent preparation strategies, properties and applications of magnetic nanoparticle/clay mineral (MNP/CM) nanocomposites. It is organized into five sections. The first section introduces the characteristics of magnetic nanoparticles, clay minerals and the scientific and technological necessity and significance of MNP/CM nanocomposites. The second section is concerned with the preparation of MNP/CM nanocomposites which involve the introduction of MNP into clay minerals via the coprecipitation of MNP and clay minerals, the combination of MNP and pillared clay minerals, the MNP-pillared clay minerals, the combination of surfactants coated MNP and clay minerals, and the intercalation of molecular magnetic compounds into clay minerals. In particular, great strides have been made in the integration of MNP with organo-clay minerals and the resultant nanocomposites can be assembled into the films of MNP/CM nanocomposite. The third focuses on discussion on the distinct magnetism, reactivity and stability of MNP/CM naanocomposites. The superparamagnetic MNP in MNP/CM nanocomposites show a fast response to external magnetic fields and allow MNP/CM nanocomposites to be readily manipulated, well functionalized and easily separated. The fourth section deals with the uses and potentials of MNP/CM nanocomposites in electromagnetic devices, magnetorheological fluids/ferrofluids, magnetic adsorbents, catalysts and biomaterials. The last section presents the view on the existing problems and challenges. Accordingly, it is suggested that future studies need place emphasis on narrowing the size distribution of the MNP/CM nanocomposites, endowing the MNP/CM nanocomposites with more functionalities, uncovering the preparation-modification-structure-magnetism-activity relationships of the MNP/CM nanocomposites, and advancing the practical applications.
      Graphical abstract image

      PubDate: 2016-05-13T04:33:24Z
       
  • Preparation and characterization of soy lecithin-modified bentonites
    • Abstract: Publication date: July 2016
      Source:Applied Clay Science, Volumes 127–128
      Author(s): Danila Merino, Romina Ollier, Matias Lanfranconi, Vera Alvarez
      In this work, a study of exchange of soy lecithin, a natural product, in bentonite was performed in order to synthesize bio-organoclays. The effects of initial amount of modifier and reaction time were studied at a fixed reaction temperature. Organoclays thus obtained were characterized by means of X-ray diffraction (XRD) analysis, X-ray fluorescence spectrometry (XRF), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR) and water absorption tests. An effective intercalation of soy lecithin between the clay layers was obtained. The ionic exchange reaction was completed at short times whereas variations in the initial amount of modifier produced organoclays with different final properties. At low ratios of soy lecithin to bentonite, a slight increment in basal spacing of organoclays was observed due to intercalation of the organic modifier between the clay layers and a significant diminution on water absorption was achieved. When the organic content increased, the interlayer spacing increased but thermal stability of organoclays decreased compared to the samples with low organic content, whereas the water absorption was not affected. The obtained bio-organoclays are potential environmental-friendly fillers for the development of clay/biopolymer nanocomposites.


      PubDate: 2016-04-15T07:57:49Z
       
  • A novel bio-based deflocculant for bentonite drilling mud
    • Abstract: Publication date: July 2016
      Source:Applied Clay Science, Volumes 127–128
      Author(s): Karim Samadzadeh Hafshejani, Aghil Moslemizadeh, Khalil Shahbazi
      The physical and chemical properties of bentonite, a widely utilized drilling fluid additive, in the aqueous phase could potentially change when encountering drilling fluids contaminants. Therefore, prior to encountering an excepted contaminant, it is mandatory that one treat the bentonite mud by an appropriate deflocculant. This study assesses for the first time the performance of Oak seed extract (OSE) as a novel bio-based deflocculant in bentonite drilling mud through some extensive experiments. After being exposed to high temperatures and contaminants, the value of rheological parameters and fluid loss of bentonite mud free from any additives changed remarkably. The OSE kept the stability of bentonite in aqueous phase by restraining the capacity of bentonite to form a flocculated structure, decreasing rheological parameters and fluid loss value. From bentonite inhibition tests, the incapacity of OSE to reduce the magnitude of plastic viscosity was fairly clear. Based on particle size measurements, OSE had a significant impact in reducing particle size of contaminated bentonite muds. According to SEM observations, no remarkable difference was seen between the morphological features of modified bentonite with and without OSE, indicating particle delamination in both cases and no inhibitive property of OSE. The findings verify that OSE can act as a superior deflocculant. The deflocculating performance of OSE was more drastic in the case of cement-contaminated mud owing to its acidic nature (pH=4.58 at 1mass%). Therefore, this study proposes the pre-treat of the bentonite mud with OSE for encountering ultra-high pH condition generated by cement. The deflocculation mechanism is believed to be a neutralization of the positive edges of montmorillonite (Mt, dominant mineral in bentonite) by tannins (dominant constituent in OSE), destroying the ability of Mt layers to link one another. In addition to high performance, environmentally friendliness and cost effectiveness are characteristics which can be considered as other fascinating aspects of OSE.


      PubDate: 2016-04-15T07:57:49Z
       
  • Re(VII) diffusion in bentonite: Effect of organic compounds, pH and
           temperature
    • Abstract: Publication date: July 2016
      Source:Applied Clay Science, Volumes 127–128
      Author(s): Tao Wu, Zhifen Wang, Qingmei Li, Guoxiang Pan, Jinying Li, Luc R. Van Loon
      In order to understand the diffusion properties of anionic radionuclides (RN) in bentonite in the presence of organic compounds with chelating and reducing properties, the effect of humic acid (HA), citrate, oxalate and formate on Re(VII) diffusion was investigated by a through-diffusion method under different pH (pH7.0 and 10.0) and temperature conditions (10–65°C). When the molar ratio of oxalate to Re(VII) was higher than 1:1, the accumulated mass and flux were observed to decrease drastically as a function of time. It can be explained by photocatalytic impact of Fe(III) on the reduction of Re(VII) to insoluble Re(IV) by oxalate. Thus, the diffusion of Re(VII) was also observed to decrease in the presence of minor citrate, oxalate and formate. Effective diffusion coefficient (De) values decreased from 8.7×10−11 m2/s to (5.1–5.9)×10−11 m2/s. In contrast, HA had no significant impact on Re(VII) diffusion. The De values of 1.54×10−11 and 6.5×10−12 m2/s were obtained at pH7.0 and 10.0, respectively. HA thus neither has an effect on the speciation of Re(VII) nor does it change the charge of the surface. The latter is probably due to the fact that HA preferentially interacts with the aluminol sites of the montmorillonite edges without changing the zeta potential of the surface. The dependence of De of Re(VII) on temperature in the absence and presence of citrate or formate was described by the Arrhenius equation. The activation energy, Ea, was in the range of (20.7–25.1) kJ/mol, demonstrating that Re(VII) diffusion followed a pore water diffusion model.
      Graphical abstract image

      PubDate: 2016-04-15T07:57:49Z
       
  • Characterization and antibacterial activity of chlorhexidine loaded
           silver-kaolinite
    • Abstract: Publication date: July 2016
      Source:Applied Clay Science, Volumes 127–128
      Author(s): Seow Khai Jou, Nik Ahmad Nizam Nik Malek
      Chlorhexidine acetate-loaded silver-kaolinite (CA-Ag-Kaol) was prepared and characterised, and its application as an antibacterial agent was studied. CA-Ag-Kaol was prepared by the adsorption of chlorhexidine acetate (CA) (0.5mmol/L) on Ag (50% of the Cation Exchange Capacity (CEC) of kaolinite) on kaolinite. Kaolinite (Kaol), silver-kaolinite (Ag-Kaol), CA-modified kaolinite (CA-Kaol) and CA-Ag-Kaol were characterised by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field-emission scanning-electron microscopy (FESEM), energy dispersive X-ray (EDX) spectroscopy, zeta potential analysis and dispersion behavior measurements. The modification of kaolinite with cationic silver and chlorhexidine ions did not change the structure of kaolinite, and the characterization of the kaolinite samples revealed the successful loading of cationic silver and chlorhexidine ions on the kaolinite. The antibacterial assay of the samples was carried out against Escherichia coli ATCC 11229, Pseudomonas aeruginosa ATCC 15442, Staphylococcus aureus ATCC 6538 and Enterococcus faecalis ATCC 29212 using the disc diffusion technique (DDT) and the minimum inhibition concentration (MIC) technique. Based on the antibacterial assay, CA-Ag-Kaol showed better antibacterial activity than Ag-Kaol and CA-Kaol, and it performed well in both distilled water and a 0.9% saline solution. Gram-positive bacteria were more susceptible to the antibacterial behavior of Ca-Ag-Kaol than Gram-negative bacteria. In conclusion, silver-kaolinite that has been loaded with chlorhexidine acetate can be used as an effective antibacterial agent because of its high antibacterial activity against wide spectrum of bacteria in solutions containing electrolytes (saline solution).
      Graphical abstract image

      PubDate: 2016-04-09T09:45:51Z
       
 
 
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