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    - EARTH SCIENCES (471 journals)
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EARTH SCIENCES (471 journals)                  1 2 3 | Last

Showing 1 - 200 of 371 Journals sorted alphabetically
Acta Geochimica     Hybrid Journal   (Followers: 3)
Acta Geodaetica et Geophysica     Hybrid Journal   (Followers: 1)
Acta Geodaetica et Geophysica Hungarica     Full-text available via subscription   (Followers: 2)
Acta Geophysica     Open Access   (Followers: 6)
Acta Geotechnica     Hybrid Journal   (Followers: 6)
Acta Meteorologica Sinica     Hybrid Journal   (Followers: 3)
Advances in High Energy Physics     Open Access   (Followers: 21)
Advances In Physics     Hybrid Journal   (Followers: 18)
Aeolian Research     Hybrid Journal   (Followers: 5)
African Journal of Aquatic Science     Hybrid Journal   (Followers: 13)
Algological Studies     Full-text available via subscription   (Followers: 2)
Alpine Botany     Hybrid Journal   (Followers: 3)
AMBIO     Hybrid Journal   (Followers: 14)
Anales del Instituto de la Patagonia     Open Access   (Followers: 1)
Andean geology     Open Access   (Followers: 13)
Annales Henri Poincaré     Hybrid Journal   (Followers: 3)
Annales UMCS, Geographia, Geologia, Mineralogia et Petrographia     Open Access  
Annals of Geophysics     Open Access   (Followers: 13)
Annals of GIS     Hybrid Journal   (Followers: 20)
Annals of Glaciology     Full-text available via subscription   (Followers: 3)
Annual Review of Marine Science     Full-text available via subscription   (Followers: 11)
Anthropocene     Hybrid Journal   (Followers: 3)
Anthropocene Review     Hybrid Journal   (Followers: 4)
Applied Clay Science     Hybrid Journal   (Followers: 4)
Applied Geochemistry     Hybrid Journal   (Followers: 11)
Applied Geomatics     Hybrid Journal   (Followers: 3)
Applied Geophysics     Hybrid Journal   (Followers: 7)
Applied Ocean Research     Hybrid Journal   (Followers: 5)
Applied Petrochemical Research     Open Access   (Followers: 2)
Applied Remote Sensing Journal     Open Access   (Followers: 34)
Aquatic Conservation Marine and Freshwater Ecosystems     Hybrid Journal   (Followers: 34)
Arctic Science     Open Access   (Followers: 6)
Arctic, Antarctic, and Alpine Research     Full-text available via subscription   (Followers: 10)
Artificial Satellites : The Journal of Space Research Centre of Polish Academy of Sciences     Open Access   (Followers: 17)
Asia-Pacific Journal of Atmospheric Sciences     Hybrid Journal   (Followers: 20)
Asian Journal of Earth Sciences     Open Access   (Followers: 20)
Asian Review of Environmental and Earth Sciences     Open Access   (Followers: 1)
Atlantic Geology : Journal of the Atlantic Geoscience Society / Atlantic Geology : revue de la Société Géoscientifique de l'Atlantique     Full-text available via subscription   (Followers: 10)
Atmosphere-Ocean     Full-text available via subscription   (Followers: 12)
Atmospheric and Climate Sciences     Open Access   (Followers: 28)
Australian Journal of Earth Sciences: An International Geoscience Journal of the Geological Society of Australia     Hybrid Journal   (Followers: 11)
Boletim de Ciências Geodésicas     Open Access  
Boreas: An International Journal of Quaternary Research     Hybrid Journal   (Followers: 10)
Bragantia     Open Access   (Followers: 2)
Bulletin of Earthquake Engineering     Hybrid Journal   (Followers: 11)
Bulletin of Geosciences     Open Access   (Followers: 8)
Bulletin of the Lebedev Physics Institute     Hybrid Journal   (Followers: 1)
Bulletin of the Seismological Society of America     Full-text available via subscription   (Followers: 21)
Bulletin of Volcanology     Hybrid Journal   (Followers: 17)
Cadernos de Geociências     Open Access  
Canadian Journal of Plant Science     Full-text available via subscription   (Followers: 15)
Canadian Mineralogist     Full-text available via subscription   (Followers: 3)
Canadian Water Resources Journal     Hybrid Journal   (Followers: 21)
Carbonates and Evaporites     Hybrid Journal   (Followers: 3)
CATENA     Hybrid Journal   (Followers: 4)
Chemical Geology     Hybrid Journal   (Followers: 18)
Chemie der Erde - Geochemistry     Hybrid Journal   (Followers: 4)
Chinese Geographical Science     Hybrid Journal   (Followers: 5)
Chinese Journal of Oceanology and Limnology     Hybrid Journal   (Followers: 4)
Ciencia del suelo     Open Access   (Followers: 2)
Ciencias Espaciales     Open Access  
Climate and Development     Hybrid Journal   (Followers: 12)
Coastal Management     Hybrid Journal   (Followers: 25)
Cogent Geoscience     Open Access  
Comptes Rendus Geoscience     Full-text available via subscription   (Followers: 8)
Computational Geosciences     Hybrid Journal   (Followers: 12)
Computational Mathematics and Mathematical Physics     Hybrid Journal   (Followers: 1)
Computers and Geotechnics     Hybrid Journal   (Followers: 8)
Contemporary Trends in Geoscience     Open Access   (Followers: 3)
Continental Shelf Research     Hybrid Journal   (Followers: 9)
Contributions to Mineralogy and Petrology     Hybrid Journal   (Followers: 10)
Contributions to Plasma Physics     Hybrid Journal   (Followers: 3)
Coral Reefs     Hybrid Journal   (Followers: 16)
Cretaceous Research     Hybrid Journal   (Followers: 7)
Cybergeo : European Journal of Geography     Open Access   (Followers: 5)
Depositional Record     Open Access  
Developments in Geotectonics     Full-text available via subscription   (Followers: 3)
Developments in Quaternary Science     Full-text available via subscription   (Followers: 3)
Développement durable et territoires     Open Access   (Followers: 3)
Diatom Research     Hybrid Journal   (Followers: 2)
Doklady Physics     Hybrid Journal   (Followers: 1)
Dynamics of Atmospheres and Oceans     Hybrid Journal   (Followers: 11)
E&S Engineering and Science     Open Access  
E3S Web of Conferences     Open Access  
Earth and Planetary Science Letters     Hybrid Journal   (Followers: 109)
Earth and Space Science     Open Access   (Followers: 11)
Earth Interactions     Full-text available via subscription   (Followers: 11)
Earth Science Research     Open Access   (Followers: 6)
Earth Surface Dynamics (ESurf)     Open Access   (Followers: 4)
Earth Surface Processes and Landforms     Hybrid Journal   (Followers: 19)
Earth System Dynamics     Open Access   (Followers: 6)
Earth System Dynamics Discussions     Open Access   (Followers: 4)
Earth's Future     Open Access   (Followers: 1)
Earth, Planets and Space     Open Access   (Followers: 65)
Earthquake Engineering and Engineering Vibration     Hybrid Journal   (Followers: 7)
Earthquake Science     Hybrid Journal   (Followers: 10)
Earthquake Spectra     Full-text available via subscription   (Followers: 18)
Ecohydrology     Hybrid Journal   (Followers: 10)
Ecological Questions     Open Access   (Followers: 7)
Electromagnetics     Hybrid Journal   (Followers: 5)
Energy Efficiency     Hybrid Journal   (Followers: 11)
Energy Exploration & Exploitation     Hybrid Journal   (Followers: 4)
Environmental Earth Sciences     Hybrid Journal   (Followers: 22)
Environmental Geology     Hybrid Journal   (Followers: 20)
Environmental Geosciences     Full-text available via subscription   (Followers: 3)
Environmental Geotechnics     Hybrid Journal   (Followers: 4)
Erwerbs-Obstbau     Hybrid Journal  
Estuaries and Coasts     Hybrid Journal   (Followers: 18)
Estuarine, Coastal and Shelf Science     Hybrid Journal   (Followers: 34)
Estudios Geográficos     Open Access  
European Journal of Mineralogy     Full-text available via subscription   (Followers: 13)
European Journal of Remote Sensing     Open Access  
Exploration Geophysics     Hybrid Journal   (Followers: 4)
Facies     Hybrid Journal   (Followers: 9)
Fieldiana Life and Earth Sciences     Full-text available via subscription   (Followers: 1)
Física de la Tierra     Open Access  
Folia Musei rerum naturalium Bohemiae occidentalis. Geologica et Paleobiologica     Open Access  
Folia Quaternaria     Open Access  
Forestry Chronicle     Full-text available via subscription   (Followers: 11)
Frontiers in Earth Science     Open Access   (Followers: 5)
Frontiers in Geotechnical Engineering     Open Access   (Followers: 2)
Frontiers of Earth Science     Hybrid Journal   (Followers: 8)
Fundamental and Applied Limnology / Archiv für Hydrobiologie     Full-text available via subscription   (Followers: 4)
GEM - International Journal on Geomathematics     Hybrid Journal   (Followers: 1)
Geo-Marine Letters     Hybrid Journal   (Followers: 7)
Geoacta     Open Access   (Followers: 4)
Geobiology     Hybrid Journal   (Followers: 8)
Geocarto International     Hybrid Journal   (Followers: 22)
Geochemical Perspectives     Hybrid Journal  
Geochemistry : Exploration, Environment, Analysis     Hybrid Journal   (Followers: 7)
Geochemistry, Geophysics, Geosystems     Full-text available via subscription   (Followers: 25)
Geochimica et Cosmochimica Acta     Hybrid Journal   (Followers: 48)
Geochronometria     Hybrid Journal   (Followers: 3)
Geoderma Regional : The International Journal for Regional Soil Research     Full-text available via subscription   (Followers: 4)
Geodinamica Acta     Hybrid Journal   (Followers: 3)
Geodynamics & Tectonophysics     Open Access   (Followers: 1)
Geoenvironmental Disasters     Open Access   (Followers: 3)
Geofluids     Hybrid Journal   (Followers: 4)
Geoforum     Hybrid Journal   (Followers: 21)
Géographie physique et Quaternaire     Full-text available via subscription   (Followers: 1)
Geography and Natural Resources     Hybrid Journal   (Followers: 5)
Geoheritage     Hybrid Journal   (Followers: 1)
Geoinformatica Polonica : The Journal of Polish Academy of Arts and Sciences     Open Access  
Geoinformatics & Geostatistics     Hybrid Journal   (Followers: 8)
Geological Journal     Hybrid Journal   (Followers: 14)
Geology Today     Hybrid Journal   (Followers: 25)
Geology, Geophysics and Environment     Open Access  
Geomagnetism and Aeronomy     Hybrid Journal   (Followers: 3)
Geomatics, Natural Hazards and Risk     Hybrid Journal   (Followers: 9)
Geomechanics for Energy and the Environment     Full-text available via subscription   (Followers: 1)
GEOmedia     Open Access   (Followers: 1)
Geomorphology     Hybrid Journal   (Followers: 26)
Geophysical & Astrophysical Fluid Dynamics     Hybrid Journal   (Followers: 2)
Geophysical Journal International     Hybrid Journal   (Followers: 31)
Geophysical Prospecting     Hybrid Journal   (Followers: 7)
Geophysics     Full-text available via subscription   (Followers: 18)
GeoResJ     Hybrid Journal  
Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards     Hybrid Journal   (Followers: 8)
Geoscience Canada : Journal of the Geological Association of Canada / Geoscience Canada : journal de l'Association Géologique du Canada     Full-text available via subscription   (Followers: 4)
Geoscience Data Journal     Open Access   (Followers: 2)
Geoscience Frontiers     Open Access   (Followers: 9)
Geoscience Letters     Open Access   (Followers: 1)
Geoscience Records     Open Access  
Geosciences     Open Access   (Followers: 2)
Geosciences Journal     Hybrid Journal   (Followers: 10)
Geoscientific Instrumentation, Methods and Data Systems     Open Access   (Followers: 4)
Geoscientific Model Development     Open Access   (Followers: 2)
Geostandards and Geoanalytical Research     Hybrid Journal   (Followers: 2)
Geosystem Engineering     Hybrid Journal   (Followers: 1)
Geotectonic Research     Full-text available via subscription   (Followers: 4)
Geotectonics     Hybrid Journal   (Followers: 7)
GISAP : Earth and Space Sciences     Open Access   (Followers: 2)
Glass Physics and Chemistry     Hybrid Journal   (Followers: 4)
Global and Planetary Change     Hybrid Journal   (Followers: 17)
Global Biogeochemical Cycles     Full-text available via subscription   (Followers: 12)
Gondwana Research     Hybrid Journal   (Followers: 7)
Grassland Science     Hybrid Journal   (Followers: 1)
Ground Water     Hybrid Journal   (Followers: 30)
Ground Water Monitoring & Remediation     Hybrid Journal   (Followers: 17)
Groundwater for Sustainable Development     Full-text available via subscription  
Helgoland Marine Research     Open Access   (Followers: 3)
History of Geo- and Space Sciences     Open Access   (Followers: 4)
Hydrobiologia     Hybrid Journal   (Followers: 18)
Hydrogeology Journal     Hybrid Journal   (Followers: 16)
Hydrological Processes     Hybrid Journal   (Followers: 24)
Hydrology and Earth System Sciences     Open Access   (Followers: 28)
ICES Journal of Marine Science: Journal du Conseil     Hybrid Journal   (Followers: 53)
IEEE Journal of Oceanic Engineering     Hybrid Journal   (Followers: 11)
Indian Geotechnical Journal     Hybrid Journal   (Followers: 3)
Indonesian Journal on Geoscience     Open Access   (Followers: 2)
Interdisciplinary Environmental Review     Hybrid Journal   (Followers: 3)
International Geology Review     Hybrid Journal   (Followers: 14)
International Journal of Advanced Geosciences     Open Access  
International Journal of Advanced Remote Sensing and GIS     Open Access   (Followers: 33)
International Journal of Advancement in Earth and Enviromental Sciences     Open Access   (Followers: 3)
International Journal of Advancement in Remote Sensing, GIS, and Geography     Open Access   (Followers: 27)
International Journal of Applied Earth Observation and Geoinformation     Hybrid Journal   (Followers: 35)
International Journal of Coal Geology     Hybrid Journal   (Followers: 2)
International Journal of Disaster Risk Reduction     Hybrid Journal   (Followers: 12)
International Journal of Earth Sciences     Hybrid Journal   (Followers: 31)

        1 2 3 | Last

Journal Cover Applied Clay Science
  [SJR: 0.826]   [H-I: 83]   [4 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0169-1317
   Published by Elsevier Homepage  [3041 journals]
  • Development and characterization of porous membranes based on
           kaolin/chitosan composite
    • Authors: Sonia Bouzid Rekik; Sana Gassara; Jamel Bouaziz; André Deratani; Semia Baklouti
      Pages: 1 - 9
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Sonia Bouzid Rekik, Sana Gassara, Jamel Bouaziz, André Deratani, Semia Baklouti
      Chitosan/kaolin composite porous membranes were successfully prepared by solvent casting and evaporation process. The suspensions with different concentration of kaolin and chitosan showed a Newtonian behaviour. Strong interaction between chitosan and kaolin was revealed by FTIR and thermogravimetric analysis. The effect of kaolin content on the morphology and properties of the obtained membranes was studied. It was found by SEM observation that the kaolin particles were well dispersed in the chitosan matrix generating a porous microstructure. Incorporation of kaolin particles also improved the mechanical and thermal properties of the membranes and reduced drastically the water washout of chitosan in moderate acidic medium. Owing to their porous structure, the water permeability of the composite chitosan/kaolin membrane was significantly enhanced. The better formulation of the dope suspension in the range studied was 4% chitosan and 5% kaolin in acetic acid. These membranes made from naturally occurring materials might play an important role in advanced research in water treatment and environmental science.

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

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

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

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

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

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

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

      PubDate: 2017-03-20T21:52:04Z
      DOI: 10.1016/j.clay.2017.03.020
      Issue No: Vol. 143 (2017)
  • Green synthesis of g-C3N4/CuONP/LDH composites and derived g-C3N4/MMO and
           their photocatalytic performance for phenol reduction from aqueous
    • Authors: Mihaela Mureseanu; Teodora Radu; Radu-Dorin Andrei; Mihaela Darie; Gabriela Carja
      Pages: 1 - 12
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Mihaela Mureseanu, Teodora Radu, Radu-Dorin Andrei, Mihaela Darie, Gabriela Carja
      A facile, environmentally friendly route for the synthesis of ZnAlLDH/g-C3N4/CuONP composite was demonstrated by exploiting the specific behaviour of the freshly calcined ZnAlLDH/melamine hybrids in Cu(OAc)2 aqueous solution. ZnAlLDH was synthesised and thereafter calcined at 550°C in air, in the absence or in presence of melamine, to obtain the mixtures of metal oxides (ZnAlMMO and ZnAlMMO/g-C3N4, respectively). Furthermore, by structural reconstruction of the freshly calcined ZnAlLDH in the aqueous solution of Cu(OAc)2 we transformed ZnAlMMO and ZnAlMMO/g-C3N4 into ZnAlLDH/CuONP and ZnAlLDH/g-C3N4/CuONP, respectively. The effects of coupling g-C3N4 with ZnAlLDH, but also the effects of the formation of CuONP on the surface of g-C3N4/ZnAlLDH on the morphology, structural, optical, electrochemical and thermal properties were investigated by powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), UV–Vis spectroscopy, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). The obtained results revealed a synergic heterojunction between the semiconductor components coupled with ZnAlLDH, with a tuned position of energy bands in the g-C3N4/ZnAlLDH and a good dispersion of CuONP in the composite. Furthermore, the heterojunction between g-C3N4 and calcined LDH was proved in ZnAlMMO/g-C3N4, which was an intermediate in the green synthesis of the reconstructed hydrotalcites. When tested for phenol photodegradation under irradiation with UV and Vis light the best efficiency was obtained for the ZnAlMMO/g-C3N4 sample (100% phenol conversion after 4h irradiation under UV, though 75% conversion was reached after 24h irradiation with Vis light). The mechanism of charge separation and the electron transfer in the heterojunction of g-C3N4 with CuONP and ZnAlLDH, was also discussed.
      Graphical abstract image

      PubDate: 2017-02-16T16:59:13Z
      DOI: 10.1016/j.clay.2017.02.012
      Issue No: Vol. 141 (2017)
  • Influence of voltage and temperature on electro-osmosis experiments
           applied on marine clay
    • Authors: Zhijia Xue; Xiaowei Tang; Qing Yang
      Pages: 13 - 22
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Zhijia Xue, Xiaowei Tang, Qing Yang
      A series of electro-osmosis experiments were conducted to explore the effect of voltage and temperature on the electro-osmosis properties of marine clay, including current, average consolidation degree, horizontal shrinkage, shear strength, water content, and anode corrosion. As shown for the resistivity of marine clay, the temperature increased when the electro-osmosis phenomenon occurred. From mechanical and electro-chemical point of view, this study explained the differences in the average consolidation degree and horizontal shrinkage under various experimental conditions. Although a voltage loss appeared due to the anode corrosion, the high voltage and temperature were still found beneficial for the reduction of the soil water content and the increase of shear strength. Furthermore, the electro-osmosis effect at high voltage included the contribution of joule heating.

      PubDate: 2017-02-23T18:22:10Z
      DOI: 10.1016/j.clay.2017.01.033
      Issue No: Vol. 141 (2017)
  • Design of pH-responsive antimicrobial nanocomposite as dual drug delivery
           system for tumor therapy
    • Authors: Fatemeh Bazmi Zeynabad; Roya Salehi; Mehrdad Mahkam
      Pages: 23 - 35
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Fatemeh Bazmi Zeynabad, Roya Salehi, Mehrdad Mahkam
      A novel antibacterial clay/polymer nanocomposite with average particle size of 20–40nm and two cationic compartments in polymer was synthesized via ion exchange. The structure of the nanocomposites was characterized by XRD, FT-IR, TG-DTA, and SEM. This multifunctional nanocomposite was used for dual drug delivery of anticancer drug methotrexate (MTX) and an antibacterial agent ciprofloxacin (CIP) with encapsulation efficiency of >90% for both drugs. The in vitro antimicrobial activity of the clay/polymer nanocomposites was studied against Escherichia coli and Pseudomonas aeruginosa bacteria by a well diffusion method. The nanocomposite showed good or moderate antimicrobial activities. However, CIP loaded nanocomposites showed enhanced antimicrobial activity in comparison to free CIP. The potential antitumoral activity of this clay/polymer nanocomposite system was evaluated against MCF7 cell lines by MTT assay and cell cycle studies. The cytotoxicity studies demonstrated enhanced cytotoxicity of developed MTX loaded nanocomposite in comparison to free MTX. Cell cycle study showed that MTX-loaded nanocomposite caused S-phased arrest in MCF-7 cells compared to control non-treated cells (P <0.001). Therefore, dual drug-loaded antibacterial nanocomposite has the potential to be used for cancer therapy.

      PubDate: 2017-02-23T18:22:10Z
      DOI: 10.1016/j.clay.2017.02.015
      Issue No: Vol. 141 (2017)
  • Multi-scale analysis and time evolution of pozzolanic activity of lime
           treated clays
    • Authors: E. Vitale; D. Deneele; M. Paris; G. Russo
      Pages: 36 - 45
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): E. Vitale, D. Deneele, M. Paris, G. Russo
      A multi-scale investigation on the influence of clay mineralogy on the pozzolanic activity of lime treated clays has been presented. Two clays of different mineralogy have been considered for this study, namely kaolin and bentonite. The time dependent mineralogical and microstructural changes induced by lime addition have been monitored at increasing curing time by means of X-ray diffraction (XRD), thermogravimetric analysis, 29Si NMR spectroscopy, Scanning electron microscopy (SEM) and nitrogen adsorption/desorption measurements. Different lime contents of the treated samples have been considered in order to highlight the ongoing of pozzolanic reactions. The time scale of chemical reactions taking place after the addition of lime depends on clay mineralogy. In the short term, flocculation phenomena due to the cation exchange reactions control the microstructural features of lime treated kaolin. The low reactivity of kaolinite clay minerals to pozzolanic reactions was detected as a delay in precipitation of new hydrated phases. The chemo-physical evolution of lime treated bentonite depends on the combined effect of cation exchange and pozzolanic reactions which develop with a comparable time scale. The results of micro-scale investigations were directly linked to the experimental evidences at volume scale of the samples, allowing an interpretation of the mechanical improvement of the treated clays in the short and long term as a function of the chemo-physical evolution of the system.

      PubDate: 2017-02-23T18:22:10Z
      DOI: 10.1016/j.clay.2017.02.013
      Issue No: Vol. 141 (2017)
  • Tortuosity model to predict the combined effects of crystallinity and
           nano-sized clay mineral on the water vapour barrier properties of
           polylactic acid
    • Authors: Bowen Tan; Noreen Louise Thomas
      Pages: 46 - 54
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Bowen Tan, Noreen Louise Thomas
      The combined effects of crystallinity and nano-sized clay mineral (montmorillonite) fillers on the water vapour barrier properties of poly(lactic acid) (PLA) nanocomposites are investigated. Both amorphous and semi-crystalline PLA nanocomposites containing 0 to 5wt% montmorillonite clay are prepared by melt compounding followed by compression moulding with two different thermal treatments: quenching and annealing. Thermal properties and morphology are investigated using differential scanning calorimetry (DSC), polarised light microscopy, transmission electron microscopy (TEM) and wide-angle X-ray diffraction (WAXD). It is confirmed that the nanocomposite structures are intercalated and the montmorillonite aspect ratio is measured to be 40 in both quenched and annealed samples. Water vapour transmission rates (WVTR) through the film samples are measured. A new tortuous path model is developed that fits the WVTR data and accounts for the effects of crystallinity as well as montmorillonite aspect ratio, concentration and orientation.
      Graphical abstract image

      PubDate: 2017-02-23T18:22:10Z
      DOI: 10.1016/j.clay.2017.02.014
      Issue No: Vol. 141 (2017)
  • Swelling deformation of compacted GMZ bentonite experiencing chemical
           cycles of sodium-calcium exchange and salinization-desalinization effect
    • Authors: Yong-Gui Chen; Ling-Yan Jia; Quan Li; Wei-Min Ye; Yu-Jun Cui; Bao Chen
      Pages: 55 - 63
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Yong-Gui Chen, Ling-Yan Jia, Quan Li, Wei-Min Ye, Yu-Jun Cui, Bao Chen
      In China, GMZ bentonite has been recognized as the first choice of buffer material while Beishan area in Gansu province has been considered as the potential disposal site for high-level radioactive waste (HLW) repository. As the groundwater at the repository field is rich in Na+ and Ca2+, the swelling properties of compacted GMZ bentonite will be affected by the chemistry of groundwater. In this work, the swelling deformation behaviors of compacted GMZ bentonite were tested at a vertical stress of 0.1MPa to assess the influence of cation exchange between Na+ and Ca2+, as well as the salinization-desalinization effect by cyclical infiltrations of distilled water and saline solutions. Results show that Na-bentonite is partly transformed into Ca-bentonite once NaCl solution is replaced with CaCl2 solution. Comparing to NaCl solution, the inhibiting effect of CaCl2 solution is weak, and thus the additional swelling is observed. Along with chemical cycles, the total strain of compacted GMZ bentonite gradually increases, while the chemical sensitivity of strain behavior reduces. This tendency is also detected for GMZ bentonite experiencing the desalinization path of distilled water prior to each infiltration of salt solution. Regarding the relative strain of GMZ bentonite, the difference in osmotic suction between distilled water and salt solution is more relevant than the sodium-calcium replacement.

      PubDate: 2017-03-20T21:52:04Z
      DOI: 10.1016/j.clay.2017.02.016
      Issue No: Vol. 141 (2017)
  • Functional clay aerogel composites through hydrophobic modification and
           architecture of layered clays
    • Authors: Omar Abo Madyan; Mizi Fan; Zhaohui Huang
      Pages: 64 - 71
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Omar Abo Madyan, Mizi Fan, Zhaohui Huang
      This paper implements hydrophobic modified clay layers with ammonia salts (Organoclay) using ultra-sonication and water as a solvent to develop functional clay/Poly vinyl alcohol (PVA) aerogel composites through an environmentally friendly freeze drying process. Various compositions have been designed aiming at the high effectiveness of reducing moisture absorption while increasing the structural integrity and overall compressive modulus but reducing the thermal conductivity of the aerogel composites. The results showed significant enhancement to both physical and mechanical properties of the aerogel composites. The microstructure systems of the aerogel composites could be tailored to result in multifunctional performance for the targeted applications. The moisture absorption could be reduced five folds compared to that of normal clay aerogels depending on the exposure relative humidity. While the modulus of the aerogel composites was doubled from an initial modulus of 0.39 to 0.82MPa, the thermal conductivity was reduced by up 20% reaching values as low as 0.0315w/mk. These aerogel composites could be an effective and efficient thermal insulation material to be implemented in the construction industry.
      Graphical abstract image

      PubDate: 2017-02-23T18:22:10Z
      DOI: 10.1016/j.clay.2017.01.013
      Issue No: Vol. 141 (2017)
  • Adsorptive removal of 134Cs+, 60Co2+ and 152+154Eu3+ radionuclides from
           aqueous solutions using sepiolite: Single and multi-component systems
    • Authors: Mamdoh R. Mahmoud; Ghada M. Rashad; Essam Metwally; Ebtissam A. Saad; Ahmed M. Elewa
      Pages: 72 - 80
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Mamdoh R. Mahmoud, Ghada M. Rashad, Essam Metwally, Ebtissam A. Saad, Ahmed M. Elewa
      Single and multi-component adsorptive removal of 134Cs+, 60Co2+ and 152+154Eu3+ from aqueous solutions onto sepiolite are studied in the present study. Removal of these radionuclides in single systems is found to be strongly dependent on the initial pH on the solution. Removals >99% (for 60Co2+ and 152+154Eu3+) and of about 82% (for 134Cs+) are achieved at initial pH values higher than 4 and 5, respectively. The kinetic data and the equilibrium isotherms are modeled by two kinetic models, the pseudo-first-order and the pseudo-second-order, and two isotherm models, Langmuir and Freundlich, respectively. The effect of various coexisting cations, Na+, Ca2+ and Al3+, at different concentrations on the adsorption processes of the concerned radionuclides in single systems was evaluated. Desorption studies of radionuclide-loaded sepiolite are studied using different concentrations of organic, EDTA and HA (strong complexing agents for radionuclides), and inorganic, HCl, NaCl, CaCl2, Mg(NO3)2 and AlCl3, desorbing agents. Adsorption mechanisms of radionuclides onto sepiolite are deeply discussed. Multi-component adsorptive removal of 134Cs+, 60Co2+ and 152+154Eu3+ onto sepiolite as a function of adsorbent weight and time was also studied. The influence of the solution pH on co-removal efficiency of radionuclides was investigated in presence of EDTA. Furthermore, the present investigation evaluated the removal efficiency of radionuclides, in multi-systems, in presence of different concentrations either of NaCl or CaCl2.

      PubDate: 2017-02-23T18:22:10Z
      DOI: 10.1016/j.clay.2016.12.021
      Issue No: Vol. 141 (2017)
  • Fabrication of kaolin-based cement plug for CO2 storage wells
    • Authors: Naim M. Faqir; Salaheldin Elkatatny; Mohammd Mahmoud; Reyad Shawabkeh
      Pages: 81 - 87
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Naim M. Faqir, Salaheldin Elkatatny, Mohammd Mahmoud, Reyad Shawabkeh
      A new material from clay was developed that has a resistance to carbon dioxide flow in upstream for plugging CO2 storage wells. Thermogravimetric and thermal stability of this material showed a minimal variation in weight loss with incremental heating up to 420°C. Adsorption-desorption of CO2 at various modeled temperature showed an exothermic and spontaneous process with maximum adsorption capacity of 775mg/g obtained at 640psi (43.5bar) and 50°C. Higher pressure led to more storage capacity with physisorption hysteresis curves. Freundlich and BET models best fit the equilibrium adsorption data with average regression coefficient of 0.995. The new material can substitute the conventional cement plugs for upstream carbon sequestration and prevents the migration of the stored CO2 through the cement plug to the surface. Also the developed new cement showed no chemical interaction which confirms the economical impact of using this cement to plug the CO2 sequestrations wells.

      PubDate: 2017-03-03T14:36:19Z
      DOI: 10.1016/j.clay.2017.02.011
      Issue No: Vol. 141 (2017)
  • Preparation and characterization of Fe,Co,Si-pillared montmorillonites
           with aminosilanes as silicon pillars precursor
    • Authors: Liang Fang; Li Wang; Tao Zhou; Lihua Liu; Jian Zhou; Menglin Li
      Pages: 88 - 94
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Liang Fang, Li Wang, Tao Zhou, Lihua Liu, Jian Zhou, Menglin Li
      Fe,Co,Si-pillared montmorillonites with micro- and mesopores and high thermal stability were prepared by directly introducing transition metal ions (Fe and Co) and aminosilanes to the interlayer of calcium montmorillonite (Ca-Mt) from Inner Mongolia. The presence of Fe, Co and Si in the interlayer spaces of montmorillonite (Mt) and properties of these pillared Mt were investigated by a combination of X-ray diffraction, elemental analysis, N2 adsorption-desorption, thermal analysis, NH3 temperature-programmed desorption and H2 temperature-programmed reduction capacity tests techniques. The results indicated that the enhanced physicochemical properties of pillared Mt could be attributed to the formation of Fe, Co and Si composite pillars supporting the interlayer space. Particularly, aminosilane played an important role in improving the basal spacing and thermal stability of pillared montmorillonites.
      Graphical abstract image

      PubDate: 2017-03-03T14:36:19Z
      DOI: 10.1016/j.clay.2017.02.006
      Issue No: Vol. 141 (2017)
  • Intercalation behavior of branched polyethyleneimine into sodium bentonite
           and its effect on rheological properties
    • Authors: Gang Xie; Pingya Luo; Mingyi Deng; Junlin Su; Zheng Wang; Rui Gong; Junni Xie; Shunjie Deng; Qiang Duan
      Pages: 95 - 103
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Gang Xie, Pingya Luo, Mingyi Deng, Junlin Su, Zheng Wang, Rui Gong, Junni Xie, Shunjie Deng, Qiang Duan
      The inhibitive mechanism of low-molecular-weight branched polyethyleneimine (BPEI) with multiple primary amines and 1,6-hexamethylenediamine (HMDA) with two primary amines adsorbed on sodium bentonite (Na+Bent) has been investigated using isothermal adsorption, adsorption kinetics, scanning electron microscopy (SEM), X-ray diffraction (XRD) and elemental analysis (EA) techniques. The results indicate that as the number of primary amine groups in the inhibitor increases, the saturated adsorption amount decreases, and the adsorption rate increases. Low-molecular-weight BPEI molecules enter the interlayer space of Na+Bent and significantly reduce this space compared to that in hydrated Na+Bent. Moreover, there is no change in the clay interlayer space of Na+Bent with increasing BPEI concentration. A monolayer of BPEI intercalates into the clay interlayer and replaces the sodium ions in the interlayer. The BPEI molecules become firmly embedded in the Na+Bent interlayer between the primary amine groups and Si-O groups, resulting in the removal of water molecules. The inhibitive performance shows that BPEI inhibits clay hydration more effectively than HMDA and other inhibitors, and also indicates that as the number of primary amines increases, the inhibitive performance increases. When <1wt% BPEI was added, the rheological properties improved significantly, and the American Petroleum Institute standard (API) fluid loss could be controlled well, indicating that BPEI can effectively create a balance between swelling inhibition and the rheological properties of water-based drilling fluids. Overall, the results indicate that BPEI is promising as a commercial shale inhibitor.

      PubDate: 2017-03-03T14:36:19Z
      DOI: 10.1016/j.clay.2017.02.018
      Issue No: Vol. 141 (2017)
  • Salt effects on Re(VII) and Se(IV) diffusion in bentonite
    • Authors: Tao Wu; Zhifen Wang; Hai Wang; Zhiqiang Zhang; Luc R. Van Loon
      Pages: 104 - 110
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Tao Wu, Zhifen Wang, Hai Wang, Zhiqiang Zhang, Luc R. Van Loon
      The through-diffusion method was employed to investigate the effect of the salt concentration on the diffusion behaviour of Re(VII) and Se(IV) in compacted bentonite. The accessible porosity, εacc, of Re(VII) increased from 0.25 to 0.38 with an increase of the ionic strength from 0.1 to 1.0mol/L. The dependency of the accessible porosity εacc on the salt concentration could be described approximately by a first-order decay exponential function. The interlayer porosity of GMZ bentonite was 21% of the total porosity at a bulk dry density of 1600kg/m3 at 12°C. The De values of Re(VII) and Se(IV) increased from 2.6×10−11 to 6.1×10−11 m2/s and from 1.6×10−11 to 4.7×10−11 m2/s in GMZ bentonite with an increase of the ionic strength from 0.1 to 1.0mol/L, respectively. In the case of Se(IV), the adsorption showed a different ionic strength dependency in GMZ bentonite and montmorillonite. The ionic strength has no significant effect on the adsorption (Kd =1.8×10−4 m3/kg) on GMZ bentonite, indicating the formation of inner-sphere surface complexes. In the case of synthetic montmorillonite, the Kd values increased with increasing ionic strength. This can be explained by the fact that the electric potential of surface sites becomes less negative with increasing ionic strength resulting in an increase in the adsorption of Se(IV) at a pH above the point of zero salt effect (PZSE). The De values of both Re(VII) and Se(IV) increased with increasing salt concentration. Both anions are totally excluded from the interlayer space and partially from the diffuse double layer. Ionic strength alters the effective diffusion coefficient of anions by controlling the thickness of the diffuse double layer. Anion diffusion data from the literature (effective and apparent diffusion coefficients) were satisfactorily evaluated by Archie's relation.
      Graphical abstract image

      PubDate: 2017-03-03T14:36:19Z
      DOI: 10.1016/j.clay.2017.02.021
      Issue No: Vol. 141 (2017)
  • Effects of fly ash, blast furnace slag and metakaolin on mechanical
           properties and durability of coral sand concrete
    • Authors: Shukai Cheng; Zhonghe Shui; Tao Sun; Rui Yu; Guozhi Zhang; Sha Ding
      Pages: 111 - 117
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Shukai Cheng, Zhonghe Shui, Tao Sun, Rui Yu, Guozhi Zhang, Sha Ding
      This paper investigates the effects of fly ash (FA), blast furnace slag (BFS) and metakaolin (MK) on the mechanical properties, drying shrinkage, carbonation and chloride permeability of coral sand concretes (CSC), in which the replacement levels of supplementary cementitious materials (SCMs) below 35% by weight are compared. The control mixture contain only ordinary Portland cement (OPC) as the binder and nature aggregate concrete (NAC) while the remaining mixtures include binary and ternary blends of FA, BFS, and MK addition. Test results indicate that CSC show slightly lower compressive strength, higher drying shrinkage and carbonation depths compared to that of NAC due to high porosity of coral sand aggregate. Moreover, CSC exhibit better chloride penetration than that of NAC. The incorporating of MK has efficient pozzolanic reaction in improving the development of compressive strength and chloride permeability performance, and reducing drying shrinkage values of CSC than that of modified CSC with FA and BFS addition. Furthermore, the incorporation of MK manifests better carbonation resistance than that of control group and CSC containing FA and BFS.

      PubDate: 2017-03-20T21:52:04Z
      DOI: 10.1016/j.clay.2017.02.026
      Issue No: Vol. 141 (2017)
  • Glucose conversion to methyl levulinate catalyzed by metal ion-exchanged
    • Authors: Jie Liu; Bei-Bei Yang; Xue-Qian Wang; Chun-Ling Liu; Rong-Zhen Yang; Wen-Sheng Dong
      Pages: 118 - 124
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Jie Liu, Bei-Bei Yang, Xue-Qian Wang, Chun-Ling Liu, Rong-Zhen Yang, Wen-Sheng Dong
      Various metal ion-exchanged montmorillonite catalysts were prepared, characterized, and evaluated in the conversion of glucose to methyl levulinate in methanol. The bulk and surface features of these catalysts were investigated using X-ray fluorescence spectroscopy, inductively coupled plasma optical emission spectroscopy, powder X-ray diffraction, Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric analysis, scanning electron microscopy, N2 adsorption–desorption, temperature-programmed NH3 desorption, and pyridine adsorption FT-IR spectroscopy. Al3+-exchanged montmorillonite had the best activity and maximum methyl levulinate selectivity because of presence of a large number of acid sites and a good balance of Brønsted and Lewis acid sites on the catalyst. The montmorillonite catalyst can be easily recovered from the reaction mixture by filtration, and reused at least five times without any loss of activity and selectivity after treatment with H2O2 solution to remove carbon species deposited on the catalyst surface.
      Graphical abstract image

      PubDate: 2017-03-03T14:36:19Z
      DOI: 10.1016/j.clay.2017.02.017
      Issue No: Vol. 141 (2017)
  • Study of the effect of clay swelling on the oil recovery factor in porous
           media using a glass micromodel
    • Authors: Milad Sharifipour; Peyman Pourafshary; Ali Nakhaee
      Pages: 125 - 131
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Milad Sharifipour, Peyman Pourafshary, Ali Nakhaee
      Formation damage due to incompatibility between the formation and injected low-salinity water decreases the relative permeabilities of oil and brine, increases residual oil saturation, and decreases oil recovery. In the presence of swelling clays, the shock effect of sudden water injection results in an increase in formation damage. Clay minerals may cause formation damage due to swelling and migration during the production of oil and gas. Therefore a good understanding of the damage mechanisms of clays helps us to prevent and remedy possible damage in reservoirs. In this work, the effect of clay swelling behavior on the oil recovery factor at the pore scale by using a glass micromodel was studied. A clay-coated micromodel with sodium bentonite as the swelling clay was prepared. Using an image processing technique, the ultimate oil recovery factors after flooding with low-salinity water (LSW) and high-salinity water (HSW) were estimated and the effect of clay swelling phenomena on the oil recovery factor was studied. Final residual oil saturation was higher when LSW was used as the injection fluid compared to when HSW was used, and in fact it can be said that clay swelling somehow inhibits the film flow of injection fluid and causes more oil to be bypassed in the micromodel.

      PubDate: 2017-03-03T14:36:19Z
      DOI: 10.1016/j.clay.2017.02.020
      Issue No: Vol. 141 (2017)
  • Facile synthesis and characterization of core-shell structured Ag3PO4@Hal
           nanocomposites for enhanced photocatalytic properties
    • Authors: Hongxia Peng; Dan Zhang; Xiaohe Liu; Wei Tang; Hao Wan; Hao Xiong; Renzhi Ma
      Pages: 132 - 137
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Hongxia Peng, Dan Zhang, Xiaohe Liu, Wei Tang, Hao Wan, Hao Xiong, Renzhi Ma
      Ag3PO4 is considered to be an ideal candidate for water photo-oxidation and organic contaminant decomposition under visible light due to its appropriate band gap position, nontoxicity, and high quantum yield. However, the prominent low stability and adsorption capacity due to light corrosion hinders the performance improvement. Herein, Ag3PO4 particles coated by halloysite nanotubes (Hal) might display noticeably photocatalytic activities upon light excitation. The Ag3PO4@halloysite nanotubes (Ag3PO4@Hal) nanocomposites could be facile prepared in large quantities through a simple, green, and efficient direct precipitation method. Compared with the individually dispersed Ag3PO4 particles, the as-prepared Ag3PO4@Hal nanocomposites showed the smaller band gap energy. The Ag3PO4@Hal nanocomposites can endow Hal special performance and also improve the catalytic activity of Ag3PO4, which is proposed to have originated from narrow band gap, strong adsorption capacity and low surface recombination rate induced by a negative fixed charge in the Hal shells. The Ag3PO4@Hal nanocomposites can be used as highly efficient photocatalysts. The current study provides a new paradigm for designing new type nanocomposites with excellent collaborative performance.
      Graphical abstract image

      PubDate: 2017-03-03T14:36:19Z
      DOI: 10.1016/j.clay.2017.02.023
      Issue No: Vol. 141 (2017)
  • Parameters influencing adsorption of Paraburkholderia phytofirmans PsJN
           onto bentonite, silica and talc for microbial inoculants
    • Authors: Ana Bejarano; Ursula Sauer; Birgit Mitter; Claudia Preininger
      Pages: 138 - 145
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Ana Bejarano, Ursula Sauer, Birgit Mitter, Claudia Preininger
      The aim of this study was to evaluate the mineral carriers bentonite, silica and talc as potential supports for immobilization of the plant growth promoting bacterium Paraburkholderia phytofirmans PsJN, and determine the factors influencing bacterial adsorption to provide stable and efficient microbial inoculants for use in the field. Results reveal that adsorption of PsJN depends on pH, the number of immobilized cells decreasing from pH5.5 to 9. Zeta potential measurements indicated that the surface charge of the carrier had certain, but not major influence on bacteria immobilization. The amount of Mg2+ contained in the carrier was a key feature, determining the extent of immobilization of PsJN in buffer (talc>bentonite>silica). Moreover, we evaluated the hydrophobicity and its influence on adsorption of PsJN by measuring the contact angle and the number of adsorbed bacterial cells. Highest number of bacterial cells was found on talc, the most hydrophobic material of the three tested ones (bentonite: 3.8×109 CFUg−1; silica: 3.0×109 CFUg−1; talc: 1.4×1010 CFUg−1). By contrast, similar immobilization capacity was observed on the three materials, when bacteria culturing and bacteria adsorption were performed in a single step. This might be related to the fact that during culturing biofilm is formed as a result of clonal growth of initially attached bacteria, rather than the recruitment of planktonic cells. Altogether, the important factors for adsorption in buffer (pH5.5) appeared to be mainly the electrostatic and hydrophobic interactions.
      Graphical abstract image

      PubDate: 2017-03-03T14:36:19Z
      DOI: 10.1016/j.clay.2017.02.022
      Issue No: Vol. 141 (2017)
  • Strength behavior and microstructural characteristics of soft clay
           stabilized with cement kiln dust and fly ash residue
    • Authors: Naphol Yoobanpot; Pitthaya Jamsawang; Suksun Horpibulsuk
      Pages: 146 - 156
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Naphol Yoobanpot, Pitthaya Jamsawang, Suksun Horpibulsuk
      This study presents the use of cement kiln dust (CKD) and fly ash (FA) to improve the unconfined compressive strength (UCS) of soft Bangkok clay compared with ordinary Portland cement (OPC). The UCS tests were performed after a curing time of 3, 7, 28 and 90days. An investigation of each reaction product was conducted using an X-ray diffraction (XRD) technique, and changes in the microstructures of the stabilized clay were observed using a scanning electron microscope (SEM). The test results revealed that a 13% CKD mixture with a partial replacement of 20% FA was suggested as the optimal content ratio to produce a similar long term strength as that achieved using the 10% content of OPC. The UCS of the stabilized clay increased relative to the formation of the primary reaction product, calcium silicate hydrate (CSH), as analyzed using the XRD. The formation of this product reduced the void space in the clay structure resulting in denser and stronger of stabilized clay to correspond with the compressive strength development with time. The change on microstructure of stabilized clay due to the hydration products was evidenced by SEM.

      PubDate: 2017-03-20T21:52:04Z
      DOI: 10.1016/j.clay.2017.02.028
      Issue No: Vol. 141 (2017)
  • Electrical properties of TiO2-pillared bidimensional manganese oxides
    • Authors: O. Giraldo; N.P. Arias; M.E. Becerra
      Pages: 157 - 170
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): O. Giraldo, N.P. Arias, M.E. Becerra
      This work consists on modifying a layered manganese oxide material with a tytanyl acylate complex through an ion exchange reaction and performing a pillaring process by thermal treatment to induce the formation of titanium oxide nanoparticles in the interlayered space. Atomic absorption spectroscopy (AAS) evidenced a 6.54w% Ti in the material. The XRD patterns showed the typical basal spacing of the birnessite type structure, not significant changes occurred after pillaring. The layer structure is maintained at 175°C, and above this temperature causes the formation of pyrolusite, hausmannite and bixbyite in accordance with thermal events shown in the TGA and DSC analysis. SEM shows the plate like morphology characteristic of this type of materials. The pillared material had more compact morphology. The N2 adsorption-desorption isotherm was type II and shows variation in the hysteresis loops. The BET area increases from 28m2/g to 108m2/g, the micropore area increases from 0.88m2/g to 16.85m2/g, the mesopore size decrease (from 163Å to 136Å) and the micropore size distribution shows a bimodal behavior which indicates a successful pillaring process. The impedance spectroscopy results of the pristine material showed electron transport in bulk and grain boundaries (high frequencies) plus ionic conduction (low frequencies), after pillarization process the electric behavior of the material was mainly due to electrical conduction since the diffusion process associated with ionic conduction was no longer observed. The AC conductivity at high frequency for the pillarized material was three times the conductivity of the raw material. The DC conductivity was thermally activated and it was higher for the pillared material than for the pristine material. There was also experimental evidence of thermally activated dielectric relaxation.
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      PubDate: 2017-03-20T21:52:04Z
      DOI: 10.1016/j.clay.2017.02.019
      Issue No: Vol. 141 (2017)
  • Studies on natural rubber containing kaolin modified with
           hexamethylenediamine derivative of phosphorylated cashew nut shell liquid
    • Authors: R.V. Sreelekshmi; M. Brahmakumar; J.D. Sudha; A.R. Ravindranatha Menon
      Pages: 171 - 179
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): R.V. Sreelekshmi, M. Brahmakumar, J.D. Sudha, A.R. Ravindranatha Menon
      Kaolin was modified with a solution of phosphorylated cashew nut shell liquid prepolymer (PCNSL) containing hexamethylenediamine (HMDA). The organomodified kaolin was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and infrared spectroscopy (FTIR). Processability characteristics and physico-mechanical properties of natural rubber (NR) compositions of conventional vulcanization (CV), semi efficient vulcanization (SEV) and efficient vulcanization (EV) systems containing 6phr (parts per hundred rubber) of the HMDA-PCNSL modified kaolin and unmodified kaolin have been studied. Compositions containing the organomodified kaolin showed improved cure characteristics and vulcanizate properties such as hardness, tensile strength, tear strength, abrasion resistance and thermal stability along with lower heat build-up and compression set which could be advantageous for applications such as tire treads.
      Graphical abstract image

      PubDate: 2017-03-03T14:36:19Z
      DOI: 10.1016/j.clay.2017.02.034
      Issue No: Vol. 141 (2017)
  • Smectite-, silica- and zeolites-bearing raw materials (Hliník nad Hronom
           bentonite, Slovakia) - A new approach using integrated petrographic and
           mineralogical studies
    • Authors: Katarzyna Górniak; Tadeusz Szydłak; Adam Gaweł; Agnieszka Klimek; Anna Tomczyk; Jerzy Motyka; Krzysztof Bahranowski
      Pages: 180 - 191
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Katarzyna Górniak, Tadeusz Szydłak, Adam Gaweł, Agnieszka Klimek, Anna Tomczyk, Jerzy Motyka, Krzysztof Bahranowski
      This paper presents the results of detailed petrographic and mineralogical studies of commercial bentonite from the Hliník nad Hronom deposit in Slovakia. The X-ray diffraction, optical microscopy, field emission scanning electron microscopy (FESEM), thermal analysis, infrared spectroscopy and chemical analyses revealed that the main component of the studied commercial bentonite is montmorillonite (47%) followed by opal-C/CT (20%), clinoptilolite (15%), biotite (3%), potassium feldspar and plagioclases (12%), and quartz (3%). Both the optical microscopy and FESEM studies demonstrated that the precursor of bentonite was ignimbrite composed of compressed, strongly deformed pumice fragments, which were moulded around pyroclastic grains such as biotite, plagioclase, quartz and fragments of volcanic rocks. The pumice fragments were locally cemented by microcrystals of potassium feldspars and subsequently replaced by montmorillonite, and opal-C/CT, less commonly by clinoptilolite. The specific surface area of the studied bentonite is about 50m2/g. Although bentonite from the Hliník nad Hronom deposit is recognized as a medium-quality raw material due to relatively low content of smectite, it can be valuable as a substance which integrates the properties of smectite-, silica- and zeolite-bearing raw materials.
      Graphical abstract image

      PubDate: 2017-03-08T15:09:02Z
      DOI: 10.1016/j.clay.2017.02.032
      Issue No: Vol. 141 (2017)
  • Refinement of industrial kaolin by removal of iron-bearing impurities
           using thiourea dioxide under mechanical activation
    • Authors: Mang Lu; Guanghua Xia; Xiaolin Zhang
      Pages: 192 - 197
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Mang Lu, Guanghua Xia, Xiaolin Zhang
      This study reports a series of experiments conducted to evaluate the suitability of thiourea dioxide (TD) under mechanical activation, in bleaching iron-bearing impurities from raw kaolin. The optimum conditions for the maximum whiteness of 76.32% were determined as follows: rotation speed of ball mill, 400rpm; activation time, 1.5h; TD dosage, 0.8% of kaolin mass; solid-to-liquid ratio, 1:2; pH, 8.0; room temperature. The effect of grinding causes the partial surface amorphization of kaolin particles and a decrease in the dehydroxylation temperature. The assistance of grinding leads to a higher iron removal when compared with the conventional bleaching method using sodium hydrosulfite.

      PubDate: 2017-03-20T21:52:04Z
      DOI: 10.1016/j.clay.2017.02.033
      Issue No: Vol. 141 (2017)
  • Effect of CEC coverage of hexadecyltributylphosphonium modified
           montmorillonite on polymer compatibility
    • Authors: Rustam Hojiyev; Yusuf Ulcay; Mehmet S. Çelik; William M. Carty
      Pages: 204 - 211
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Rustam Hojiyev, Yusuf Ulcay, Mehmet S. Çelik, William M. Carty
      Graphical abstract image

      PubDate: 2017-03-08T15:09:02Z
      DOI: 10.1016/j.clay.2017.02.036
      Issue No: Vol. 141 (2017)
  • Solids surface characterization using computational algorithms: A case
           study for talc fillers
    • Authors: Zhitong Yao; Daidai Wu; Jerry Y.Y. Heng; Weihong Wu; Hongting Zhao; Jie Liu; Junhong Tang
      Pages: 212 - 218
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Zhitong Yao, Daidai Wu, Jerry Y.Y. Heng, Weihong Wu, Hongting Zhao, Jie Liu, Junhong Tang
      The solid surface characterization using contact angle measurement is complicated and time-consuming. In this work, two computational algorithms in MATLAB and C were developed and validated by the surface properties determination of talc filler (TCF) and colored talc filler (CTCF). The results indicated that, the surface free energy parameters calculated using the two algorithms for both samples were consistent. As compared to the MATLAB function, the assembly statements of C function were longer, although the unknowns can be directly obtained using this toolbox. The γ S D values determined by the Owens-Wendt-Kaelble (OWK), van Oss-Chaudhury-Good (vOCG) and Wu methods were consistent and contributed a major part of the γ S T . Compared to γ S D , the γ S SP component contributed less to γ S T , implying a lower polarity for both samples. The lower γ S D and γ S SP for CTCF added up to a lower γ S T value, which could reduce filler particle-particle interactions. The mechanical properties study of acrylonitrile-butadiene-styrene (ABS) matrix filled with the two fillers showed that the incorporation of them played mainly a reinforcing role, and a better performance for CTCF was observed.

      PubDate: 2017-03-08T15:09:02Z
      DOI: 10.1016/j.clay.2017.02.027
      Issue No: Vol. 141 (2017)
  • Perturbation induced by a nitrate plume on diffusion of solutes in a
           large-scale clay rock sample
    • Authors: R.V.H. Dagnelie; P. Arnoux; J. Enaux; J. Radwan; P. Nerfie; J. Page; D. Coelho; J.-C. Robinet
      Pages: 219 - 226
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): R.V.H. Dagnelie, P. Arnoux, J. Enaux, J. Radwan, P. Nerfie, J. Page, D. Coelho, J.-C. Robinet
      Mudstones are widely studied in the context of waste landfill leachates or as geological barriers for waste management. Some of the technological wastes undergo biogeochemical degradation, releasing sulfate or nitrate plumes. The concomitant increase of salts concentration and ionic strength may perturb the geological media and affect transport properties. The study investigated the effect of a nitrate plume on the diffusion of ions. The confinement of ionic solutes was quantified in Callovian-Oxfordian mudstone. A 0.5molL−1 NaNO3 solution was injected in a large-scale sample with a low water/rock (≪1.0Lkg−1) close to environmental conditions. The in-diffusion of HTO, 36Cl, NO3 −, 22Na, 137Cs was monitored during the perturbation. A minor impact was observed on poral water chemistry and on ions diffusion. The anion exclusion was only reduced by 19% for chloride and effective diffusion of cations reduced by 20 to 30%. Diffusion data of NO3 − was quantified and anion exclusion found to be intermediate between that of halogen anions and that of water. Values of diffusion anisotropies were adjusted to a(36Cl)=1.9 and a(22Na)=2.5, close to data in sound sample. All these results confirmed a limited perturbation by 0.5molL−1 nitrate plume on the confinement properties of the clay rock. Additional data is provided on major ions released from the rock and diffusing towards the injection solution. It may be useful for further chemistry-transport modeling including co-diffusion of ions, surface diffusion, anion exclusion and effect of ionic strength.
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      PubDate: 2017-03-08T15:09:02Z
      DOI: 10.1016/j.clay.2017.02.025
      Issue No: Vol. 141 (2017)
  • Photocatalytic degradation of organic contaminants over clay-TiO2
           nanocomposites: A review
    • Authors: Beata Szczepanik
      Pages: 227 - 239
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Beata Szczepanik
      Heterogeneous photocatalysis is an efficient, economical and environmentally friendly technology for removing organic contaminants from the aqueous environment. Titania is one of the most popular photocatalyst for decomposing organic compounds due to its strong photocatalytic activity, chemical and biological inertness and high photochemical stability. Extensive literature analysis has shown many possibilities to improve the efficiency of photodecomposition of organic compounds over TiO2. Clay minerals with large surface areas for adsorption and high adsorption capacity used to synthesize nanocomposites with TiO2 (especially anatase) enhance the decomposition of organic pollutants by photocatalytic degradation. Recently, clay minerals have been used more often to prepare hybrid photocatalysts. Dispersing TiO2 nanoparticles onto the surfaces of clay minerals improves the photocatalytic activity of TiO2 by providing more active surface sites and reducing the agglomeration of TiO2 particles. The present review paper offers the following: an overview of the trend in the use of the clay/TiO2 nanocomposite photocatalysts, especially halloysite/TiO2 materials for removal of organic contaminants from water, report on the recent work done and important applications for photocatalytic degradation of organic pollutants.
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      PubDate: 2017-03-08T15:09:02Z
      DOI: 10.1016/j.clay.2017.02.029
      Issue No: Vol. 141 (2017)
  • Influence of mechanical treatment on thermophysical processes in illitic
           clay during firing
    • Authors: Štefan Csáki; Igor Štubňa; Patrik Dobroň; Peter Minárik; Martina Záleská; Tereza Václavů; Libor Vozár
      Pages: 240 - 247
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Štefan Csáki, Igor Štubňa, Patrik Dobroň, Peter Minárik, Martina Záleská, Tereza Václavů, Libor Vozár
      The influence of mechanical treatment on thermophysical properties of illitic clay was studied during firing using the acoustic emission technique (AE), scanning electron microscopy (SEM), X-ray diffracion analysis (XRD) and thermal analyses (DTA, TGA, DIL). The milling process promotes the formation of agglomerates created from the illite crystals damaged by milling. Due to the newly formed crystal defects, the course of dehydroxylation as well as the high temperature processes were shifted to lower temperatures owing to rising milling time. The AE activity during heating increases with increasing the milling time. Thus, longer milling time contributes to the crack formation during heating. However, during cooling, the low AE activity indicates that the crack formation was suppressed. The density of the samples increases with increasing milling time, thus a denser, more homogeneous microstructure is formed.

      PubDate: 2017-03-08T15:09:02Z
      DOI: 10.1016/j.clay.2017.02.031
      Issue No: Vol. 141 (2017)
  • Use of ionic monomers to prepare halloysite polymer nanocomposites with
           reinforced mechanical performance
    • Authors: Yu Jiang; Peipei Wang; Junping Zheng
      Pages: 248 - 256
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Yu Jiang, Peipei Wang, Junping Zheng
      Pristine halloysite (Hal) nanotubes were used to fabricate polymer-based nanocomposites via in situ polymerization: Methyl methacrylate (MMA) was selected as main monomer, and respectively copolymerized with a small quantity of ionic comonomer 2-(methacryloyloxy)ethyltrimethylammonium chloride (MTC) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS), meanwhile Hal was added during the polymerization process. The noncovalent interactions between Hal and ionic comonomers are key factors of successful preparation of Hal P(MMA-co-MTC) nanocomposite and Hal P(MMA-co-AMPS) nanocomposite. The mechanical properties of nanocomposites were investigated in detail. The results indicate that, the nanocomposites demonstrated excellent mechanical performance due to strong interfacial adhesion ameliorated by noncovalent interactions; Hal exhibited much stronger interfacial adhesion with P(MMA-co-MTC) matrix compared to that with P(MMA-co-AMPS) matrix; and the nanocomposites containing 1.5wt% Hal content and 10wt% MTC content showed the highest tensile strength and flexural strength, respectively improved by 47.5% and 165.6% compared with neat PMMA. The highlight of this work is to provide a simple and feasible Hal polymer nanocomposites preparation technique with high mechanical performance improvement and slight Hal loadings.

      PubDate: 2017-03-08T15:09:02Z
      DOI: 10.1016/j.clay.2017.03.003
      Issue No: Vol. 141 (2017)
  • Risedronate functionalized layered double hydroxides nanoparticles with
           bone targeting capabilities
    • Authors: Dariana Aristizabal Bedoya; Cecilia Vasti; Ricardo Rojas; Carla E. Giacomelli
      Pages: 257 - 264
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Dariana Aristizabal Bedoya, Cecilia Vasti, Ricardo Rojas, Carla E. Giacomelli
      Layered double hydroxides nanoparticles (LDH-NPs) are increasingly studied as drug nanocarriers for cellular delivery. Nevertheless, stable functionalizations providing targeting capabilities without disrupting the size of the carriers are necessary to achieve optimized performance. Here, LDH-NPs were functionalized with risedronate (Ris) to improve the osteotropicity of the nanocarriers without altering the nanosized distribution. Ris is a nitrogen containing bisphosphonate with rich acid-base reactivity that can lead Ris functionalized LDH-NPs also as pH-responsive drug nanocarriers. The current work is focused on the strategy to synthesize functionalized LDH-NPs with a maximum adsorption and a minimum intercalation of Ris while maintaining their nanosize. The speciation and interactions of Ris at the surface of LDH-NPs were analyzed using Raman microscopy whereas the functionalization stability and size distribution were checked in simulated biological media. Finally, pH sensitivity and hydroxyapatite binding capacity of Ris functionalized LDH-NPs were evaluated. HRis3− anions were incorporated to the LDH-NPs surface with high affinity providing with a negative zeta potential that controlled the size at around 100nm. The size of Ris functionalized LDH-NPs was not affected by the high ionic strength or the presence of proteins in simulated biological media. Further, the functionalization was stable against protein adsorption and anionic exchange. As expected, Ris functionalized LDH-NPs are bioresponsive with a high sensitivity for pH changes and specific affinity for hydroxyapatite, which makes them appealing drug nanocarriers for new bone therapies.
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      PubDate: 2017-03-08T15:09:02Z
      DOI: 10.1016/j.clay.2017.03.001
      Issue No: Vol. 141 (2017)
  • Novel intercalation mechanism of zwitterionic surfactant modified
    • Authors: Jianxi Zhu; Ping Zhang; Yanhong Qing; Ke Wen; Xiaoli Su; Lingya Ma; Jingming Wei; Hongmei Liu; Hongping He; Yunfei Xi
      Pages: 265 - 271
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Jianxi Zhu, Ping Zhang, Yanhong Qing, Ke Wen, Xiaoli Su, Lingya Ma, Jingming Wei, Hongmei Liu, Hongping He, Yunfei Xi
      In this present work, a novel intercalation mechanism of zwitterionic surfactant modified montmorillonites (ZSMMt) has been introduced. Using 3-(N,N-dimethylpalmityl-ammonio) propane sulfonate (SB16) and montmorillonite (Mt), a series of zwitterionic surfactant modified Mt were synthesized. The resulting organoclays were investigated by X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), and thermogravimetric (TG) analysis, corroborated by the useful information provided by the element analysis. As revealed by XRD results, the basal spacing of ZSMMt increases from 1.47nm to 4.13nm with the increase of zwitterionic surfactant loading from 0.2 to 4.0 times of the cation exchange capacity (CEC). According to chemical composition analysis results, the number of Ca2+ ions released during the process of ZSMMt preparation is very limited and the ratios of Ca/Si and Ca/Al of ZSMMt are comparable with those of raw Mt. These results suggest that Ca2+ still remain in the interlayer spaces of Mt. There is no noticeable exchange reaction that takes place between the zwitterionic surfactant and the interlayer Ca2+. After the zwitterionic surfactant intercalation, the IR vibration shifts from 1194 to 1191cm−1, which implies a new bonding between the Ca2+ and sulfonate group of SB16. The decomposition temperature of the ZSMMt, almost 60–80°C higher than that of bulk surfactants, clearly reflects the strong interaction force after intercalation. The present study thus concludes that the intercalation mechanism of ZSMMt is not an exchange process but an ion-dipole interaction between Mt and zwitterionic surfactant, thereby, a novel cross-coupling intercalation mechanism of preparing organoclays has been proposed.
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      PubDate: 2017-03-08T15:09:02Z
      DOI: 10.1016/j.clay.2017.03.002
      Issue No: Vol. 141 (2017)
  • Effect of alkali-activated metakaolin cement on compressive strength of
    • Authors: Kornnika Wianglor; Sakprayut Sinthupinyo; Manow Piyaworapaiboon; Arnon Chaipanich
      Pages: 272 - 279
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Kornnika Wianglor, Sakprayut Sinthupinyo, Manow Piyaworapaiboon, Arnon Chaipanich
      This paper reports the compressive strength and microstructure characteristic of alkali-activated metakaolin (MK) cement under two curing methods. MK was used to replace part of Portland cement (PC) at 70, 80, 85, 90, 95 and 100% by mass of binder. Sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) were used as activating agents (Na2SiO3 to NaOH ratio of 0.67). NaOH with 10 molar concentrations, liquid alkali/binder ratio of 0.8 and water base was used. Mortar and paste specimens were cured at 23±2°C (55% RH) and 60°C (95% RH). The results indicated that calcium silicate hydrate (C–S–H) and calcium carbonate (CaCO3) phases were detected by thermogravimetry (TGA). Setting time and drying shrinkage decreased when metakaolin replacement level increased, the compressive strength of alkali-activated metakaolin cement increased with the increase of PC content and increased with temperature. The curing of specimens at 60°C (95% RH) enhanced the compressive strength, matrices appeared denser than when cured at 23±2°C (55% RH) and phases of (C, N)-A-S-H gel and or C–S–H gel can be seen clearly.

      PubDate: 2017-03-16T09:26:35Z
      DOI: 10.1016/j.clay.2017.01.025
      Issue No: Vol. 141 (2017)
  • Comparison of the hydrogeochemical and mechanical behaviours of compacted
           bentonite using different conceptual approaches
    • Authors: A. Yustres; A. Jenni; L. Asensio; X. Pintado; K. Koskinen; V. Navarro; P. Wersin
      Pages: 280 - 291
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): A. Yustres, A. Jenni, L. Asensio, X. Pintado, K. Koskinen, V. Navarro, P. Wersin
      This study compares the capabilities of two numerical models that simulate the behaviour of compacted saturated MX-80 bentonite exposed to different chemical environments. Both codes have different approaches: one of them is a reactive transport model, and the other is a hydrogeomechanical model. The study shows that the combined use of both approaches provides a useful basis for designing bentonite barriers in the geological disposal of high-level nuclear waste. Although, their application is now limited to simple geometries and boundary conditions, the proposed approaches are a first step towards a fully thermo-hydro-mechano-chemical model. It is also shown that there is a need for a greater understanding of the chemomechanical coupling that occurs at the microstructural scale to achieve this comprehensive model in the future.
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      PubDate: 2017-03-16T09:26:35Z
      DOI: 10.1016/j.clay.2017.03.006
      Issue No: Vol. 141 (2017)
  • μ-Raman spectroscopy and X-ray diffraction of asbestos' minerals for
           geo-environmental monitoring: The case of the southern Apennines natural
    • Authors: Maria Carmela Dichicco; Angela De Bonis; Giovanni Mongelli; Giovanna Rizzo; Rosa Sinisi
      Pages: 292 - 299
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Maria Carmela Dichicco, Angela De Bonis, Giovanni Mongelli, Giovanna Rizzo, Rosa Sinisi
      Asbestos is a term commonly used to refer to those silicate minerals that show a typical fibrous habitus and crystallize as separable fibres. For the past decade, considerable research has focused on the strong correlation between deadly diseases and the exposure to asbestos-like minerals present in different environmental matrices. These harmful minerals generally occur as naturally exposed friable fibres that can be easily released into the environment as a result of both natural processes and anthropogenic activities. At the Calabria-Lucania boundary (southern Italy), the intense spreading of the asbestos fibres is also a consequence of the cataclastic features of the serpentinite outcropping. Therefore, it is necessary to intensify the geo-environmental monitoring in this area. The identification of asbestiform minerals in serpentinites is generally brought about by techniques requiring sample preparation such as: Scanning Electron Microscopy - Energy Dispersion Spectrometry, Transmission Electron Microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, polarized light optical microscopy, and differential thermal analyses. In this work, we evaluate the use of μ-Raman spectroscopy, on both low and high wavenumbers, in identifying the different serpentine and amphibole minerals. The comparison between the μ-Raman spectroscopy and X-ray powder diffraction is also discussed based on analytical procedures and results.

      PubDate: 2017-03-16T09:26:35Z
      DOI: 10.1016/j.clay.2017.02.024
      Issue No: Vol. 141 (2017)
  • Potential use of modified hydrotalcites as adsorbent of Bentazon and
    • Authors: A. Pérez; R. Otero; A. Romero Esquinas; J.R. Jiménez; J.M. Fernández
      Pages: 300 - 307
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): A. Pérez, R. Otero, A. Romero Esquinas, J.R. Jiménez, J.M. Fernández
      The objective of the present research was to investigate the adsorption of pesticides on hydrotalcites modified with tetradecanedioate anions (TDD) or with humic acids (HA). In this study has been compared the pesticide adsorption on two different organohydrotalcites (OHTs) with tetradecanedioate anions in the interlayer (MA-TDD, MAF-TDD) and on other with humic acid (MAF-HA), all obtained by the coprecipitation method. Additionally, a calcined hydrotalcite has been used to adsorb Bentazon. X-ray diffraction of adsorption products on the organohydrotalcites MA-TDD and MAF-TDD showed the introduction of TDD anion and Metazachlor in the interlayer. Kinetic tests showed that the adsorption of pesticides Bentazon and Metazachlor involves intraparticle diffusion. Based on the results of regeneration tests, calcined hydrotalcite is an effective adsorbent for the removal of Bentazon from contaminated water. The results of regeneration tests suggest the possibility of using organohydrotalcites MA-TDD, MAF-TDD and MAF-HA to remove Metazachlor from contaminated water.

      PubDate: 2017-03-16T09:26:35Z
      DOI: 10.1016/j.clay.2017.03.007
      Issue No: Vol. 141 (2017)
  • A mechanism for the sphere/tube shape transition of nanoparticles with an
           imogolite local structure (imogolite and allophane)
    • Authors: A. Thill; P. Picot; L. Belloni
      Pages: 308 - 315
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): A. Thill, P. Picot, L. Belloni
      Imogolite and allophane are two strongly curved nanominerals. Indeed, imogolite has a tubular shape with a diameter of only 2.5nm. Allophane is often presented as a spherical nanostructure with a diameter of about 5nm. The mechanism explaining the strong curvature of these two nanominerals has been extensively discussed. However, whether or not these two nanomaterials are related to each other is not clear and the mechanism responsible for the selection between the two different shapes is not well established. In this article, we propose that imogolite and allophane are nanopolymorphs of the imogolite local structure and that the transition from spherical to tubular shape occurs at an early stage of the precipitation because of edge stress in proto-imogolite. This hypothesis for the shape selection is supported by the use of a nanomechanical model tuned to mimic the main characteristics of imogolite-like nanomaterials.
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      PubDate: 2017-03-16T09:26:35Z
      DOI: 10.1016/j.clay.2017.03.011
      Issue No: Vol. 141 (2017)
  • Geochemical characterization of clay deposits in the Amuq Valley (Southern
           Turkey) and the implications for archaeometric study of ancient ceramics
    • Authors: Pınar Gutsuz; Mustafa Kibaroğlu; Gürsel Sunal; Sinem Hacıosmanoğlu
      Pages: 316 - 333
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Pınar Gutsuz, Mustafa Kibaroğlu, Gürsel Sunal, Sinem Hacıosmanoğlu
      Clay-rich deposits of the Amuq Valley (Southern Turkey) were investigated using chemical methods to explore compositional characteristics of the clays within the valley and for distinguish chemical groups that can be used as reference materials in archaeometric studies of the ancient ceramic materials in this region. A total of 63 clay samples were collected from different spots throughout the valley and analyzed by X-ray fluorescence and inductively coupled plasma mass spectrometry (ICP-MS) techniques. Analytical results demonstrated that the clay-rich basin deposits show compositional variation both in stratigraphic and spatial levels. Parent rocks exposed within the catchment area of the basin deposit (transported to the basin through the main drainage systems of the Orontes, Afrin, and Karasu Rivers), seems to be one of the major factors affecting the compositional characteristics of the basin deposits. Four different geochemical reference groups were identified: the Orontes clay group, Afrin clay group, Karasu clay group and Kırıkhan clay group. Established reference groups provide opportunities for a better understanding of the local ceramic production and the exchange pattern within the valley and between the adjacent regions.

      PubDate: 2017-03-20T21:52:04Z
      DOI: 10.1016/j.clay.2017.03.004
      Issue No: Vol. 141 (2017)
  • Corrigendum to “Layered double hydroxide-agarose composites for water
           treatment: Carbonate contamination during the drying process” [Clay
           116-117 (2015) 93-101]
    • Authors: Toshiyuki Hibino
      First page: 334
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Toshiyuki Hibino

      PubDate: 2017-03-20T21:52:04Z
      DOI: 10.1016/j.clay.2016.03.036
      Issue No: Vol. 141 (2017)
  • Surface-active physicochemical characteristics of spent bleaching earth on
           soil-plant interaction and water-nutrient uptake: A review
    • Authors: Soh Kheang Loh; Kah Yein Cheong; Jumat Salimon
      Pages: 59 - 65
      Abstract: Publication date: May 2017
      Source:Applied Clay Science, Volume 140
      Author(s): Soh Kheang Loh, Kah Yein Cheong, Jumat Salimon
      The activated or neutral form of bentonite-based spent bleaching earth/clay (SBE) is a by-product generated during the bleaching process in edible oil refinery. Its untreated form is disposed of directly at landfills involving high cost and land area, and possibly causing environmental problems. Recently, this undesirable dumping exercise has been prohibited. To overcome this, SBE is regenerated and reused for value addition, e.g. as bio active materials for water/wastewater treatment. A more recent approach being converting SBE into bio fertilizers; of which the fertilizer characteristics in relation to physical, chemical and biological interaction with soil and its surrounding ecosystem (nutrients, water, pollutants, microorganisms, climate, etc.) is vital in agricultural applications associated with soil fertility management and crops productivity. Previously, SBE's structural characteristics, surface chemistry and activation have been disclosed. This paper provides an insight on soil-crop interactions and agronomy with SBE functions as a soil amendment.

      PubDate: 2017-02-04T10:43:46Z
      DOI: 10.1016/j.clay.2017.01.024
      Issue No: Vol. 140 (2017)
  • Vermiculite/poly(lactic acid) composites: Effect of nature of vermiculite
           on hydrolytic degradation in alkaline medium
    • Authors: Dolores
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): M. Dolores Fernández, M. Jesús Fernández
      Unmodified and different organomodified vermiculites were used for the preparation of poly(l-lactide) (PLLA) composites via melt mixing. The effect of the clay mineral surface modification, the type of organic modifier of the vermiculite and sample thickness on the degradation of PLLA in alkaline medium at 37°C was studied. The degradation was evaluated by analyzing mass loss, pH, molecular weights, and morphological changes. Alkaline hydrolysis of PLLA was accelerated by the presence of clay mineral and the degradation rate was very much dependent on type of clay mineral and state of dispersion. Morphological changes suggested that the erosion mechanism of polymer matrix occurred at the film surfaces and started at the interface of polymer and clay minerals. The results presented here show that the hydrolytic degradation of PLLA can be controlled through the preparation of nanocomposites introducing the appropriate organomodified nanoclay mineral.
      Graphical abstract image

      PubDate: 2017-03-16T09:26:35Z
  • Unique solvatochromism of cyanine/saponite hybrid systems
    • Authors: Sas
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): A. Czímerová, S. Sas, A. Čeklovský
      The present study is primarily focused on the investigation of spectral properties of cationic cyanine dye (1,1′-diethyl-4, 4′-carbocyanine iodide, denoted as “NK5”) adsorbed into the structure of synthetic clay mineral (Sumecton SA, denoted as “SUM”) as a host matrix. The hybrid systems were investigated by means of absorption and fluorescence spectroscopy. Beside the solvent effect, the influence of dye/saponite ratio on the formation of specific dye species was studied in detail. It was found that used solvents have greatly affected the spectral properties of prepared hybrids. The NK5/saponite systems in ethanol and methanol were dominated by isolated dye cations. In the NK5/saponite systems in acetone and acetonitrile, the formation of higher aggregates was significantly suppressed. Moreover, the fluorescence spectra showed evidence of the formation of highly fluorescent J-aggregates. Finally, the fluorescence quantum yields of the NK5/saponite systems in various solvents were calculated. It was found that polar protic solvents as ethanol and methanol could stabilize the hybrid cyanine/saponite system with higher quantum yields as in case of used aprotic solvents.
      Graphical abstract image

      PubDate: 2017-03-08T15:09:02Z
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