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  Subjects -> EARTH SCIENCES (Total: 656 journals)
    - EARTH SCIENCES (472 journals)
    - GEOLOGY (73 journals)
    - GEOPHYSICS (28 journals)
    - HYDROLOGY (21 journals)
    - OCEANOGRAPHY (62 journals)

EARTH SCIENCES (472 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: 13)
Anadolu University Journal of Science and Technology     Open Access  
Anales del Instituto de la Patagonia     Open Access   (Followers: 1)
Andean geology     Open Access   (Followers: 13)
Annales Henri Poincaré     Hybrid Journal   (Followers: 3)
Annales UMCS, Geographia, Geologia, Mineralogia et Petrographia     Open Access  
Annals of Geophysics     Open Access   (Followers: 12)
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: 9)
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: 4)
Applied Petrochemical Research     Open Access   (Followers: 2)
Applied Remote Sensing Journal     Open Access   (Followers: 33)
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: 27)
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: 20)
Carbonates and Evaporites     Hybrid Journal   (Followers: 3)
CATENA     Hybrid Journal   (Followers: 4)
Chemical Geology     Hybrid Journal   (Followers: 15)
Chemie der Erde - Geochemistry     Hybrid Journal   (Followers: 4)
Chinese Geographical Science     Hybrid Journal   (Followers: 5)
Chinese Journal of Oceanology and Limnology     Hybrid Journal   (Followers: 3)
Ciencias Espaciales     Open Access  
Climate and Development     Hybrid Journal   (Followers: 12)
Coastal Management     Hybrid Journal   (Followers: 24)
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: 8)
Contributions to Mineralogy and Petrology     Hybrid Journal   (Followers: 9)
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: 10)
E&S Engineering and Science     Open Access  
E3S Web of Conferences     Open Access  
Earth and Planetary Science Letters     Hybrid Journal   (Followers: 103)
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: 17)
Estuarine, Coastal and Shelf Science     Hybrid Journal   (Followers: 34)
Estudios Geográficos     Open Access  
European Journal of Mineralogy     Full-text available via subscription   (Followers: 12)
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: 43)
Geochronometria     Hybrid Journal   (Followers: 3)
Geoderma Regional : The International Journal for Regional Soil Research     Full-text available via subscription   (Followers: 3)
Geodinamica Acta     Hybrid Journal   (Followers: 3)
Geodynamics & Tectonophysics     Open Access   (Followers: 1)
Geoenvironmental Disasters     Open Access   (Followers: 3)
Geofluids     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  
GEOmedia     Open Access   (Followers: 1)
Geomorphology     Hybrid Journal   (Followers: 25)
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: 6)
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  
GSA Today     Partially Free  
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: 27)
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: 13)
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: 11)

        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  [3039 journals]
  • Green synthesis of g-C3N4/CuONP/LDH composites and derived g-C3N4/MMO and
           their photocatalytic performance for phenol reduction from aqueous
           solutions
    • 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)
       
  • Phenol and/or Zn2+ adsorption by single- or dual-cation
           organomontmorillonites
    • Authors: Guifang Wang; Shuai Zhang; Yuyan Hua; Xin Su; Shaojian Ma; Jing Wang; Qi Tao; Yujue Wang; Sridhar Komarneni
      Pages: 1 - 9
      Abstract: Publication date: May 2017
      Source:Applied Clay Science, Volume 140
      Author(s): Guifang Wang, Shuai Zhang, Yuyan Hua, Xin Su, Shaojian Ma, Jing Wang, Qi Tao, Yujue Wang, Sridhar Komarneni
      Single- or dual-cation organomontmorillonites (OMt) modified by one or two cationic surfactants, respectively and/or cysteamine hydrochloride (CSH) were used to remove Zn2+ and/or phenol from aqueous solutions. The OMt were characterized by XRD, FTIR spectroscopy and N2 adsorption-desorption isotherm analyses. The adsorption results of Zn2+ and phenol showed that OMt had much larger adsorption capacities of phenol than that of Na+-Mt or CSH-Mt in the presence of Zn2+. Experiments with the simultaneous presence of both the contaminants showed that one did not affect the adsorption of the other with all the adsorbents. The uptakes of Zn2+ and phenol onto dual-cation OMt increased with increasing solution pH, contact time, temperature and initial concentration of Zn2+ and phenol. The adsorption equilibrium time was 10min for both contaminants and the maximum adsorption capacities of Zn2+ and phenol were found under alkaline environment. The adsorption of both Zn2+ and phenol can be better described by Freundlich model than Langmuir isotherm. Phenol adsorption onto OMt was caused primarily by partitioning into an organic phase in the interlayers, and the uptakes of phenol increased with increasing alkyl chain length and loading amount of surfactant in single-cation OMt. Zn2+ adsorption onto dual-cation OMt was due to ion exchange, formation of complexes and/or precipitation mechanism depending on the solution pH.
      Graphical abstract image

      PubDate: 2017-01-28T10:30:20Z
      DOI: 10.1016/j.clay.2017.01.023
      Issue No: Vol. 140 (2017)
       
  • High energy ball milling for the processing of organo-montmorillonite in
           bulk
    • Authors: Upashana Chatterjee; B.S. Butola; Mangala Joshi
      Pages: 10 - 16
      Abstract: Publication date: May 2017
      Source:Applied Clay Science, Volume 140
      Author(s): Upashana Chatterjee, B.S. Butola, Mangala Joshi
      The key issue for improving the barrier properties of clay polymer nanocomposite (CPN) is to obtain an effective dispersion and exfoliation of the clay platelets into the polymer matrix. Processing of nanoclay in bulk for industrial application still is a challenge. This paper aims to investigate high energy ball milling as an easy technique to achieve the exfoliation of organo-montmorillonite (OMt). OMt was ball-milled under different conditions and the structural changes have been characterized through XRD patterns, HR-TEM images, SEM images, particle size analysis and FT-IR spectra. A series of polyurethane based nanocomposite coating was prepared using these ball-milled OMt and the functional performances, specifically resistance to helium gas permeability and tearing strength were explored targeting inflatables for defence applications.

      PubDate: 2017-02-04T10:43:46Z
      DOI: 10.1016/j.clay.2017.01.019
      Issue No: Vol. 140 (2017)
       
  • Adsorption characteristics of Na-A zeolites synthesized from Egyptian
           kaolinite for manganese in aqueous solutions: Response surface modeling
           and optimization
    • Authors: Ahmed M. Zayed; Ali Q. Selim; Essam A. Mohamed; Mahmoud S.M. Abdel Wahed; Moaaz K. Seliem; Mika Sillanpӓӓ
      Pages: 17 - 24
      Abstract: Publication date: May 2017
      Source:Applied Clay Science, Volume 140
      Author(s): Ahmed M. Zayed, Ali Q. Selim, Essam A. Mohamed, Mahmoud S.M. Abdel Wahed, Moaaz K. Seliem, Mika Sillanpӓӓ
      Egyptian kaolinite was processed to synthesize NaA zeolites; zeolite by calcination (ZC) and zeolite by alkali fusion (ZF). Characterization of the prepared zeolites was carried out using X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) surface area. The influence of initial manganese (Mn2+) concentration, contact time and zeolite dose in manganese uptake by ZC and ZF were studied. The removal efficiency of ZF for ions was high compared to that of ZC at all contact times and adsorbent masses. The adsorption characteristics for Mn2+ were described well using the Langmuir and the pseudo-second order equations. Optimization of Mn2+ uptake using the experimental runs of the response surface methodology (RSM) indicated that the maximum manganese removal efficiency by ZC and ZF was 82.2% and 99.96%, respectively, at the conditions of 50mg/L of manganese concentration, 500min of contact time and 1.4g of dose. According to the polynomial model, the dose of ZF (0.9 to 1.12g) at contact time (190 to 340min) was predicted to enhance the maximum removal efficiency of manganese (50mg/L) to 100%. In ZC case, the maximum removal efficiency of Mn2+ was not improved using the RSM design.

      PubDate: 2017-02-04T10:43:46Z
      DOI: 10.1016/j.clay.2017.01.027
      Issue No: Vol. 140 (2017)
       
  • Novel approach to fabricate organo-LDH hybrid by the intercalation of
           sodium hexadecyl sulfate into tricalcium aluminate
    • Authors: Mingzhe Sun; Ping Zhang; Daishe Wu; Ray L. Frost
      Pages: 25 - 30
      Abstract: Publication date: May 2017
      Source:Applied Clay Science, Volume 140
      Author(s): Mingzhe Sun, Ping Zhang, Daishe Wu, Ray L. Frost
      In this work, a simple but efficient approach to synthesize sodium hexadecyl sulfate (SHS) intercalated layered double hydroxide (CaAl-LDH-SHS) is proposed. By intercalating SHS ions into the hydrates of C3A, CaAl-LDH-SHS is successfully prepared within 2h at 25°C. In order to understand the intercalation behavior and structure of the products, various techniques such as powder X-ray diffraction (XRD), thermogravimetric-differential thermal analysis (TG-DTA), scanning electron microscopy (SEM) and mid-infrared (MIR) spectroscopy combined with near-infrared (NIR) spectroscopy were adopted. The XRD analysis revealed that SHS was successfully intercalated into the hydrate of C3A, with an expanded basal spacing d (001) of 2.66nm. The CH and S O stretching vibrations observed in the FT-IR spectra further evidenced the presence of SHS in the resulting products. The average platelet diameter of 1–2μm and average thickness of 20–30nm of CaAl-LDH-SHS were obtained from the SEM image and XRD analysis.
      Graphical abstract image

      PubDate: 2017-02-04T10:43:46Z
      DOI: 10.1016/j.clay.2017.01.026
      Issue No: Vol. 140 (2017)
       
  • Preparation and properties of montmorillonite/carbon foam nanocomposites
    • Authors: Yanmao Wang; Yulin Liu; Qilang Lin; Shaohai Dong; Lei Xiong
      Pages: 31 - 37
      Abstract: Publication date: May 2017
      Source:Applied Clay Science, Volume 140
      Author(s): Yanmao Wang, Yulin Liu, Qilang Lin, Shaohai Dong, Lei Xiong
      Montmorillonite (Mt)/carbon foam nanocomposites were prepared by direct carbonization of organic montmorilonite (OMt)/bismaleimide (BMI) resin mixtures at ambient pressure. Carbonization behaviors of the OMt/BMI resin mixtures were studied using X-ray diffraction (XRD) and thermogravimetric analysis (TGA). In addition, the influences of the additive amount of OMt on the microstructures, physical properties and compressive behaviors and oxidation resistance of the resulting nanocomposites were investigated. Results show that with the increasing of the additive amount of OMt, the pore walls of the nanocomposites become thick and their average pore sizes decrease. When the additive amount of OMt varies from 0 to 1.5wt%, the mechanical properties, bulk density and oxidation resistance of the nanocomposites are improved and their thermal conductivity is markedly decreased. For the nanocomposite prepared with 1.5wt% of OMt, its bulk density, thermal conductivity, compressive strength and modulus arrive at 0.35g/cm3, 0.108W/m·K, 6.90MPa and 207MPa, respectively.

      PubDate: 2017-02-04T10:43:46Z
      DOI: 10.1016/j.clay.2017.01.030
      Issue No: Vol. 140 (2017)
       
  • Comparative and competitive adsorptive removal of Ni2+ and Cu2+ from
           aqueous solution using iron oxide-vermiculite composite
    • Authors: S. Gharin Nashtifan; A. Azadmehr; A. Maghsoudi
      Pages: 38 - 49
      Abstract: Publication date: May 2017
      Source:Applied Clay Science, Volume 140
      Author(s): S. Gharin Nashtifan, A. Azadmehr, A. Maghsoudi
      In this study, iron oxide-vermiculite composite (Iovc) with a high specific surface area (SSA) was prepared to remove Ni2+ and Cu2+ from aqueous solution. It was characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier-transform infrared (FTIR), and scanning electron microscopy (SEM). The effects of initial pH of the solution, contact time and adsorbent concentration on the adsorption efficiency were investigated systemically. Equilibrium adsorption isotherms were measured for the single component by using various models. The homogenous adsorption of Ni2+ and Cu2+ was confirmed in the single system by Langmuir and Koble–Corrigan models. For the binary adsorption of Cu2+ and Ni2+ ions have been analyzed by using non-modified Langmuir, modified Langmuir, extended Langmuir, extended Freundlich and Sheindorf–Rebuhn–Sheintuch (SRS) models. The competitive extended Langmuir model described well the competitive adsorption of Ni2+ and Cu2+. Maximum adsorption capacities for Ni2+ and Cu2+ in the binary system are 101.3 and 59.7mg/g, respectively. In the kinetic study, the experimental data fitted well the pseudo-second-order kinetics for Ni2+ and Cu2+ adsorption data. Furthermore, calculated thermodynamic parameters, ΔG°, ΔH° and ΔS° of adsorption showed that the adsorption of Ni2+ and Cu2+ was feasible, spontaneous and an exothermic process.

      PubDate: 2017-02-04T10:43:46Z
      DOI: 10.1016/j.clay.2016.12.020
      Issue No: Vol. 140 (2017)
       
  • The mangrove reactor: Fast clay transformation and potassium sink
    • Authors: Javier Cuadros; Gabriel Andrade; Tiago Osório Ferreira; Carmen Silvia de Moya Partiti; Renato Cohen; Pablo Vidal-Torrado
      Pages: 50 - 58
      Abstract: Publication date: May 2017
      Source:Applied Clay Science, Volume 140
      Author(s): Javier Cuadros, Gabriel Andrade, Tiago Osório Ferreira, Carmen Silvia de Moya Partiti, Renato Cohen, Pablo Vidal-Torrado
      Most known clay mineral reactions are slow. Clay formation by weathering is recognized as faster (hundreds of thousands to few million years) than clay reverse weathering (few to tens My), even if the latter takes place in deep diagenetic conditions at temperatures above 100°C. Identifying hot spots of fast clay retrograde reactions acting as effective potassium sinks would contribute to eliminating the present imbalance of the potassium budget towards release into the oceans. We have identified and modeled the reaction kaolinite + Fe + cations → Fe-illite occurring in Brazilian mangroves, which takes place through kaolinite-smectite and illite-smectite intermediates. The reaction is very fast, transforming 72–154gm−2 y−1 of kaolinite into Fe-illite, or 16–38% of the newly sedimented kaolinite each year. This kaolinite-to-illite transformation is 10s–100s times faster than kaolinite formation by weathering. Extrapolation of the calculated potassium consumption to mangrove forests worldwide produces 0.6–3×1012 gy−1, or 1–6% of the yearly potassium riverine input into the oceans.
      Graphical abstract image

      PubDate: 2017-02-04T10:43:46Z
      DOI: 10.1016/j.clay.2017.01.022
      Issue No: Vol. 140 (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)
       
  • Halloysite-carboxymethyl cellulose cryogel composite from natural sources
    • Authors: Sultan Butun Sengel; Mehtap Sahiner; Nahit Aktas; Nurettin Sahiner
      Pages: 66 - 74
      Abstract: Publication date: May 2017
      Source:Applied Clay Science, Volume 140
      Author(s): Sultan Butun Sengel, Mehtap Sahiner, Nahit Aktas, Nurettin Sahiner
      In this work, novel superporous composite cryogel using natural source such as carboxymethyl cellulose (CMC) and halloysite nanotubes (Hal nanotubes) was prepared. The composite was prepared via cryogelation method including the Hal nanotubes within polymeric matrices before cryogelation. A series of the Hal nanotubes/carboxymethyl cellulose composite were prepared by varying the used amounts of crosslinker, and Hal nanotubes amounts. Additionally, Hal nanotubes were modified with different modifying agent such as (3-aminopropyl)triethoxysilane (APTES), (3-chloro-2-hydroxypropyl)trimethylammonium chloride (CHPTACI), polyethylenimine (PEI), epichlorohydrin (ECH), diethylenetriamine (DETA), taurine (TA), and tris(2-aminoethyl)amine (TAEA), these modified Hal nanotubes were used in CMC cryogel composite preparation. Characterization of the synthesized materials was performed by Scanning and Transmission Electron Microscopy (SEM and TEM), Zeta Potential (ZP) measurement, Thermogravimetric Analysis (TGA), Fourier Transform Infrared (FT-IR) spectroscopic measurement and Surface area and Porosity Analyzer.
      Graphical abstract image

      PubDate: 2017-02-11T16:26:07Z
      DOI: 10.1016/j.clay.2017.01.031
      Issue No: Vol. 140 (2017)
       
  • Influence of purification method of Na-montmorillonite on textural
           properties of clay mineral composites with TiO2 nanoparticles
    • Authors: K. Bahranowski; A. Gaweł; A. Klimek; A. Michalik-Zym; B.D. Napruszewska; M. Nattich-Rak; M. Rogowska; E.M. Serwicka
      Pages: 75 - 80
      Abstract: Publication date: May 2017
      Source:Applied Clay Science, Volume 140
      Author(s): K. Bahranowski, A. Gaweł, A. Klimek, A. Michalik-Zym, B.D. Napruszewska, M. Nattich-Rak, M. Rogowska, E.M. Serwicka
      Na-montmorillonite purified either by dialysis or by multiple centrifugation was used for the preparation of two types of clay mineral/TiO2 composites: one obtained by conventional pillaring, the other by mixing of organo-montmorillonite with inverse micelles containing Ti oxo-hydroxy species. The manner of preparation of the parent clay mineral affected strongly the textural properties of pillared montmorillonite materials but had much less effect on the texture of composites prepared with inverse microemulsion. The observed phenomena are discussed in terms of the montmorillonite component structural organization upon formation of composites. Suitability of both purification methods for preparation of Na-montmorillonite designed for synthesis of composite materials is assessed.
      Graphical abstract image

      PubDate: 2017-02-11T16:26:07Z
      DOI: 10.1016/j.clay.2017.01.032
      Issue No: Vol. 140 (2017)
       
  • Mechanical and microstructural properties of metakaolin-based geopolymer
           cements from sodium waterglass and phosphoric acid solution as hardeners:
           A comparative study
    • Authors: Hervé Kouamo Tchakouté; Claus Henning Rüscher
      Pages: 81 - 87
      Abstract: Publication date: May 2017
      Source:Applied Clay Science, Volume 140
      Author(s): Hervé Kouamo Tchakouté, Claus Henning Rüscher
      Sodium waterglass with mass ratios SiO2/Na2O and H2O/Na2O equal to 1.5 and 10, respectively was prepared from commercial silica fume as a silica source. The phosphoric acid solution with molar concentration 10M was prepared by dilution of commercial phosphoric acid in distilled water. The ATR-infrared spectrum of alkaline hardener shows the presence of SiQ0, SiQ1 and SiQ2 units suggesting a more depolymerized solution. While the acid hardener contains H2PO4 − due to the deprotonation of commercial H3PO4 indicating that the molar concentration 10M contained an appropriate amount of water necessary for the workability. The formation of H2PO4 − is appropriate for the second step of geopolymerization. Metakaolin-based geopolymer cements were obtained by adding each fresh hardener to metakaolin. The results show that the compressive strength of phosphate-based geopolymer cement is 93.8MPa while the one of alkali-based geopolymer cement is 63.8MPa. The difference of the compressive strength could be related to the formation of berlinite (AlPO4) in the structure of phosphate-based geopolymer cement which acts as a filler and reinforces the structure and therefore the compressive strength of the specimen. However, the microstructures of both geopolymer cements are homogeneous and compact structure. It was typically found that phosphate-based geopolymer cement has a higher compressive strength compared to the one of alkali-based geopolymer cement. It is important to note that the hardening of metakaolin-based geopolymer cement from phosphoric acid solution required an energy gradient while metakaolin-based geopolymer cement from sodium waterglass hardens at room temperature like regular Portland cement. The purpose of this work was to compare the mechanical and microstructural properties of metakaolin-based geopolymer cements obtained in the same condition using sodium waterglass and phosphoric acid solution as hardeners. Due to their higher mechanical properties, phosphate-based geopolymer cement could be used for the construction of roads and bridges and geopolymer cements from alkaline medium could be used for building the houses.

      PubDate: 2017-02-11T16:26:07Z
      DOI: 10.1016/j.clay.2017.02.002
      Issue No: Vol. 140 (2017)
       
  • Insight into the preparation of Fe3O4 nanoparticle pillared layered double
           hydroxides composite via thermal decomposition and reconstruction
    • Authors: Lei Li; Guangxia Qi; Masami Fukushima; Bangda Wang; Hui Xu; Yi Wang
      Pages: 88 - 95
      Abstract: Publication date: May 2017
      Source:Applied Clay Science, Volume 140
      Author(s): Lei Li, Guangxia Qi, Masami Fukushima, Bangda Wang, Hui Xu, Yi Wang
      As one of layered double hydroxides (LDH) based heterogeneous catalysts, transition metal oxide pillared LDH composite has attracted considerable research interests as its excellent catalytic efficiency and thermal stability. However, during the preparation especially by reconstruction techniques, abundant interlayer regions of LDH are contaminated by some unexpected anion such as LDH affinitive CO3 2−, which will result in inaccessible interlayer active site. In this paper, magnetic nanoparticle Fe3O4 pillared LDH composite was synthesized with exchangeable NO3 − as the main interlayer anion by decomposition and reconstruction route. The anion exchange, decomposition and reconstruction processes were comprehensively investigated. XRD, TG-DTA-MS, SEM and other methods have been employed to characterize materials. The results show that anion exchange between ferric citrate anion and LDH follows Langmuir isotherm model and pseudo-second-order model. The decomposition and oxidation of anion exchange product (LDH-Fe(C6H4O7)−) can be complete at 550°C for 20min and crystal Fe3O4 with nanostructure is formed between 500 and 600°C. When calcined product (LDO-Fe3O4) is reconstructed by rehydration in 0.015M HNO3-30wt% NaNO3 mixture aqueous solution, CO3 2− contamination derived from CO2 in air can be averted and lamellar structure is successfully recovered with Fe3O4 and NO3 − remaining in the interlayer gallery of LDH.
      Graphical abstract image

      PubDate: 2017-02-11T16:26:07Z
      DOI: 10.1016/j.clay.2017.01.028
      Issue No: Vol. 140 (2017)
       
  • New insights into microbial smectite illitization in the Permo-Triassic
           boundary K-bentonites, South China
    • Authors: Qian Fang; G. Jock Churchman; Hanlie Hong; Zhong-Qiang Chen; Jiacheng Liu; Jianxin Yu; Wen Han; Chaowen Wang; Lulu Zhao; Harald Furnes
      Pages: 96 - 111
      Abstract: Publication date: May 2017
      Source:Applied Clay Science, Volume 140
      Author(s): Qian Fang, G. Jock Churchman, Hanlie Hong, Zhong-Qiang Chen, Jiacheng Liu, Jianxin Yu, Wen Han, Chaowen Wang, Lulu Zhao, Harald Furnes
      Microbially mediated smectite illitization has been extensively demonstrated in laboratory experiments. Despite occasional observations in geological environments, the transformation mechanism is still poorly understood. Here we investigated a series of volcanic ash (tephra) samples from the Permo-Triassic boundary (PTB) successions of South China, using short-wavelength infrared (SWIR) spectroscopy, in combination with XRD, MIR, EPMA, SEM, TEM, and 27Al NMR analyses, in order to establish a better understanding of microbial illitization, and to test the applicability of SWIR as a monitor for this process. Mixed-layer illite-smectite (I-Sm) clays are the predominant clay minerals, with illite percentages ranging from 32 to 93%. The (060) value of I-Sm varies from 1.4956 to 1.4996Å, indicating a dioctahedral precursor smectite. The precursor smectite of I-Sm is nearly free of Fe, and is probably montmorillonite. The b-cell dimension (b 0 parameter) exhibits a positive correlation with the illite percentage of I-Sm, suggesting that the illitization occurs with significant cation substitutions. The different spectroscopic results all indicate that tetrahedral Al substitutes for Si, and octahedral Al is mainly substituted by Mg and/or Fe with illitization, consistent with the findings of XRD analysis. Chemical compositions and trends in their variation show typical features of a dissolution-precipitation (DP) mechanism. The SEM images reveal abrupt changes in morphology and the TEM analyses suggest progressive changes in polytype with illitization, also supporting the DP process. The transformation mechanism of I-Sm contradicts the conventional wisdom concerning diagenetic bentonite I-Sm, similar to that of hydrothermal origin, probably as the result of to the involvement of microorganisms. The SWIR parameters, such as position, depth, area and asymmetry of the absorption bands, versus illite percentage in I-Sm, generally give good correlations. SWIR spectroscopy is demonstrated as a valuable method to identify I-Sm with different percentages of illite, and with a capability as a sensitive monitor for I-Sm structure ordering and crystal-chemistry. Thus it can be used as an alternative or complementary method in conventional I-Sm studies, as well as in epithermal and hydrocarbon-reservoir explorations and astrobiological investigations.

      PubDate: 2017-02-11T16:26:07Z
      DOI: 10.1016/j.clay.2017.01.029
      Issue No: Vol. 140 (2017)
       
  • Effects of nanoclay addition on phase morphology and stability of
           polycarbonate/styrene-acrylonitrile blends
    • Authors: Rafael Grande; Luiz Antonio Pessan
      Pages: 112 - 118
      Abstract: Publication date: May 2017
      Source:Applied Clay Science, Volume 140
      Author(s): Rafael Grande, Luiz Antonio Pessan
      In this work, an extensive study was performed on the compatibility and morphological stability of polycarbonate/styrene-acrylonitrile (PC/SAN) blends and on the effects of nanoclay addition to these systems. PC/SAN blends of different compositions were prepared by melt extrusion and their morphologies were characterized as prepared and after annealing at high temperature to evaluate their morphological stability. The effects of nanoclay with different organic modifiers and acrylonitrile (AN) content in the SAN copolymer on the morphology of the PC/SAN blends were also evaluated. The results indicate that the nanoclay reduces the domain size of SAN phase and stabilizes the system morphology even without complete exfoliation. Organoclays particles with polar organic modifiers were preferably located inside the SAN domains, while in blends containing organoclays with nonpolar modifiers, the clay particles migrated to the interface, resulting in domain reduction and improved morphological stability.
      Graphical abstract image

      PubDate: 2017-02-11T16:26:07Z
      DOI: 10.1016/j.clay.2017.02.001
      Issue No: Vol. 140 (2017)
       
  • Controlled formation of pseudoisocyanine J-aggregates in the interlayer
           space of synthetic saponite
    • Authors: Marián Matejdes; Daisuke Himeno; Yasutaka Suzuki; Jun Kawamata
      Pages: 119 - 123
      Abstract: Publication date: May 2017
      Source:Applied Clay Science, Volume 140
      Author(s): Marián Matejdes, Daisuke Himeno, Yasutaka Suzuki, Jun Kawamata
      In presented work dye assemblies with J-type intermolecular coupling, which are well recognized not only for their exciton transport but also for hole and electron transport properties were investigated. The use of materials consisting of J-type dye assemblies can be significantly enhanced if their photonic properties can be controlled by some external stimuli. For these reasons the switching abilities between J-type aggregated and non-aggregated states of a cationic cyanine dye, 1,1′-diethyl-2,2′-cyanine (pseudoisocyanine, PIC) intercalated in the interlayer space of synthetic saponite (Sap) were compared. The switching was performed by adding and removing of dimethyl sulfoxide (DMSO) from the interlayer space. The PIC/Sap hybrid film prepared at 70% CEC loading level has shown excellent stability within 20cycles of photophysical response after adding and removing of DMSO from the interlayer space, indicating that presented experimental approach can be useful in the future development of artificial light harvesting or semiconductor systems with controllable properties.
      Graphical abstract image

      PubDate: 2017-02-11T16:26:07Z
      DOI: 10.1016/j.clay.2017.02.007
      Issue No: Vol. 140 (2017)
       
  • Effect of morphological properties of layered double hydroxides on
           adsorption of azo dye Methyl Orange: A comparative study
    • Authors: Kaoutar El Hassani; Buscotin Horax Beakou; Daina Kalnina; Elhassan Oukani; Abdellah Anouar
      Pages: 124 - 131
      Abstract: Publication date: May 2017
      Source:Applied Clay Science, Volume 140
      Author(s): Kaoutar El Hassani, Buscotin Horax Beakou, Daina Kalnina, Elhassan Oukani, Abdellah Anouar
      The present research discussed the utilization of layered double hydroxides (LDH) materials with different morphologies as adsorbents for Methyl Orange (MO) removal from aqueous solution. The adsorption properties of LDH with flower-like morphology (f-LDH) have been investigated for azo dye, Methyl Orange (MO), and compared to conventional stone-like coprecipitated LDH phases (c-LDH). Flower-like LDH with high specific surface area of 133m2/g were synthesized by coprecipitation method in dilute alkaline solution. With relatively high specific surface areas, the as-prepared flower-like LDH, when tested as adsorbents in azo dye removal, showed excellent performance and were better than those of conventional coprecipitated LDH. The adsorption isotherms, kinetics and mechanisms for azo dye MO onto as-prepared flower-like LDH were also investigated. The high uptake capability of the as-prepared flower-like adsorbents 500.6mg of MO/g of LDH make them potentially attractive adsorbents in water purification avoiding calcination step. Hence, a low cost material will be acquired with much more benefits namely preserving energy.

      PubDate: 2017-02-16T16:59:13Z
      DOI: 10.1016/j.clay.2017.02.010
      Issue No: Vol. 140 (2017)
       
  • Adsorption of Acid Yellow 42 dye on calcined layered double hydroxide:
           Effect of time, concentration, pH and temperature
    • Authors: Rodrigo Morais Menezes dos Santos; Rosembergue Gabriel Lima Gonçalves; Vera Regina Leopoldo Constantino; Celso Valentim Santilli; Pablo Damasceno Borges; Jairo Tronto; Frederico Garcia Pinto
      Pages: 132 - 139
      Abstract: Publication date: May 2017
      Source:Applied Clay Science, Volume 140
      Author(s): Rodrigo Morais Menezes dos Santos, Rosembergue Gabriel Lima Gonçalves, Vera Regina Leopoldo Constantino, Celso Valentim Santilli, Pablo Damasceno Borges, Jairo Tronto, Frederico Garcia Pinto
      The adsorption of textile dyes onto Layered Double Hydroxides (LDH) and their thermally decomposed products is a promising strategy for the treatment of contaminated effluents - combining high removal efficiency with reasonable cost. The main purpose of this paper was to investigate the adsorption of textile azo dye Acid Yellow 42 (AY) onto calcined and uncalcined Mg-Al-CO3-LDH. A set of analytical techniques was used to characterize the materials, namely X-ray diffraction (XRD), Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), thermogravimetric analyses (TGA), N2 adsorption-desorption isotherms and Scanning Electron Microscopy (SEM). In the study of azo dye adsorption, the following factors were assessed: kinetics, adsorption capacity, effect of temperature, initial pH value, and recyclability of the adsorbent material. The adsorption capacity of calcined LDH (CLDH) was almost four times greater than that of the LDH precursor: 1266mg·g−1 (1.669mmol·g−1) and 330.0mg·g−1 (0.4350mmol·g−1), respectively, at pH equal to 7.0 and 25°C. The greater adsorption capacity for CLDH is related to the recovery property of these materials in light of the so called “memory effect”, which allows an intercalation process of the anionic dye, as demonstrated by XRD data.
      Graphical abstract image

      PubDate: 2017-02-16T16:59:13Z
      DOI: 10.1016/j.clay.2017.02.005
      Issue No: Vol. 140 (2017)
       
  • Strength enhancement of clean and kerosene-contaminated sandy lean clay
           using nanoclay and nanosilica as additives
    • Authors: S.M. Ali Zomorodian; Moghispour Shabnam; Soleymani Armina; Brendan C. O'Kelly
      Pages: 140 - 147
      Abstract: Publication date: May 2017
      Source:Applied Clay Science, Volume 140
      Author(s): S.M. Ali Zomorodian, Moghispour Shabnam, Soleymani Armina, Brendan C. O'Kelly
      In oil-rich countries, contamination of soils with oil products can occur during the refining, transportation and operation processes. From a geotechnical viewpoint, oil contamination adversely affects the geomechanical behaviour/properties. Also, depending on the circumstances, some fine soil deposits may have insufficient bearing capacity or undergo excessive settlement under loading. Both scenarios described typically require some form of ground improvement. Given their widespread application in various fields, the selective use of nanoparticles to improve the geotechnical properties can be a new approach. This paper presents an experimental study performed at bench scale on sandy lean clay (CL) soil with two main objectives: (i) to investigate the effect of increasing kerosene content on its constitutive behaviour/strength; (ii) to investigate the strength and stiffness improvements achieved for the clean and kerosene-contaminated soil using nanoclay and nanosilica materials as additives, both independently and together, including the effect of curing period. Significant and progressive reductions in strength and stiffness occurred for ≥8wt% kerosene content. Significant gains in soil strength and stiffness were achieved for 0.5–2.5wt% nanoparticle addition. For the clean CL soil, 1wt% nanoclay or 1.5wt% nanosilica addition produced the greatest improvement in strength. Compared with nanosilica, on the basis of its lower optimum wt% value required for both the clean and contaminated CL soil materials, the nanoclay material investigated was deemed more efficient in improving the uniaxial strength/stiffness.

      PubDate: 2017-02-16T16:59:13Z
      DOI: 10.1016/j.clay.2017.02.004
      Issue No: Vol. 140 (2017)
       
  • Efficiency and mechanism of stabilization/solidification of Pb(II),
           Cd(II), Cu(II), Th(IV) and U(VI) in metakaolin based geopolymers
    • Authors: Bassam I. El-Eswed; Omar M. Aldagag; Fawwaz I. Khalili
      Pages: 148 - 156
      Abstract: Publication date: May 2017
      Source:Applied Clay Science, Volume 140
      Author(s): Bassam I. El-Eswed, Omar M. Aldagag, Fawwaz I. Khalili
      This work deals with stabilization/solidification of Pb(II), Cd(II), Cu(II), Th(IV) and U(VI) in metakaolin (MK) based geopolymer (GP) prepared using one activator (sodium silicate) or two activators (sodium silicate and sodium hydroxide). Different leaching solutions with varying pH and ionic strength were used: deionized water, 0.1M HCl, 0.1M NaCl, 1.0M NaCl and 0.1M NaOH to evaluate the efficiency of stabilization. Effective stabilization was achieved regardless of using one or two activators. The efficiency of stabilization was found to increase with increasing the ionic size of heavy metal which was explained by ion-pair theory. The leaching of total ions from the GP matrix was studied by conductivity measurements which indicated that heavy metal ions in the GP matrix resulted in reduction of the leaching of the alkali ions. This excluded the mechanism that heavy metal ions can be exchanged with the alkali ions balancing the negatively charged Al tetrahedral in GP. Heavy metals were proposed to form coordination bonds between the nonbridging SiO− and AlO− of GP framework (crosslinkers) leading to more effective stabilization of total ions in the GP matrix. The FTIR study suggested formation of heavy metal hydrates, carbonates and silicates. The XRD patterns revealed an amorphous structure, and the SEM analysis indicated almost condensed homogenous surface of GP.
      Graphical abstract image

      PubDate: 2017-02-16T16:59:13Z
      DOI: 10.1016/j.clay.2017.02.003
      Issue No: Vol. 140 (2017)
       
  • Adsorption of phosphate ions from aqueous solution by modified bentonite
           with magnesium hydroxide Mg(OH)2
    • Authors: Mohamed El Bouraie; Alaa A. Masoud
      Pages: 157 - 164
      Abstract: Publication date: May 2017
      Source:Applied Clay Science, Volume 140
      Author(s): Mohamed El Bouraie, Alaa A. Masoud
      This study investigated phosphate ions removal from aqueous solutions by using modified bentonite with magnesium hydroxide in batch system. Raw bentonite (RB) and Mg-modified bentonite (MB) were characterized by Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FT-IR). Adsorption experiments were conducted on the adsorption of phosphate onto RB and MB in batch experiments. Phosphate ion removal by MB was pH dependent, and the optimum adsorption was observed at pH7. The adsorption process was relatively fast and equilibrium conditions were established within 120min at 45°C. The results were analyzed according to the Langmuir and Freundlich isotherm equations. The adsorption data is well interpreted by the Langmuir isotherm. Phosphate solution at a concentration of 25mg/L was adsorbed by MB, and the final adsorption efficiency was >54%. The results showed that phosphate adsorption density of MB was high with the maximum adsorption density of 14.33mg/m2, which suggested that MB was an excellent adsorbent for effective phosphate removal from water. Thermodynamically negative ΔG°, positive ΔH°, and positive ΔS° demonstrated the high affinity, and endothermic adsorption process between MB and phosphate from aqueous solutions.

      PubDate: 2017-02-16T16:59:13Z
      DOI: 10.1016/j.clay.2017.01.021
      Issue No: Vol. 140 (2017)
       
  • Sorption of cesium from aqueous solutions by some Egyptian pottery
           materials
    • Authors: Moubarak A. Sayed; A.I. Helal; S.M. Abdelwahab; H.F. Aly
      Pages: 1 - 8
      Abstract: Publication date: April 2017
      Source:Applied Clay Science, Volume 139
      Author(s): Moubarak A. Sayed, A.I. Helal, S.M. Abdelwahab, H.F. Aly
      Removal of Cs(I) from aqueous solutions using low-cost adsorbents such as Egyptian pottery materials under different experimental conditions was investigated. Three kinds of pottery, in addition to their raw materials were tested. Instrumental characterizations of the Egyptian pottery materials were performed by different techniques such as XRF and XRD. The effects of pH, initial metal concentration, shaking time, adsorbent weight and temperature on the removal of Cs(I) from aqueous solutions by the pottery materials were studied. The results indicated that the optimum pH for the removal of Cs(I) was found to be 7.0 for all types of pottery materials. The present study suggested raw pottery materials to be potentially low cost sorbent for the removal of Cs+ ions from aqueous solutions more than fired pottery materials.

      PubDate: 2017-01-22T10:24:18Z
      DOI: 10.1016/j.clay.2017.01.016
      Issue No: Vol. 139 (2017)
       
  • Development of new acid-imide modified Mg-Al/LDH reinforced
           semi-crystalline poly(amide-imide) containing naphthalene ring; study on
           thermal stability and optical properties
    • Authors: Mohsen Hajibeygi; Meisam Shabanian; Mehrdad Omidi-Ghallemohamadi
      Pages: 9 - 19
      Abstract: Publication date: April 2017
      Source:Applied Clay Science, Volume 139
      Author(s): Mohsen Hajibeygi, Meisam Shabanian, Mehrdad Omidi-Ghallemohamadi
      New poly(amide-imide) Mg-Al/layered double hydroxide (LDH) nanocomposites (PAINC) were prepared by solution intercalation technique from new semi crystalline poly(amide-imide) (PAI) containing naphthalene with new diacid-diimide modified Mg-Al LDH (DLDH) and sodium dodecylbenzene sulfonate (SDBS) modified Mg-Al LDH (SLDH). The X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) results showed a uniform distribution for LDH sheets with in the PAI matrix. Thermal properties of all the samples were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The thermal properties results in both nitrogen and air atmospheres showed that the addition of DLDH resulted substantial increase in the thermal stability and char yields of PAINC and indicated that DLDH had the better effect than the SLDH in thermal properties of PAI. The UV–Vis spectra of all PAINC showed reduction in intensities with increase LDH content.
      Graphical abstract image

      PubDate: 2017-01-22T10:24:18Z
      DOI: 10.1016/j.clay.2017.01.011
      Issue No: Vol. 139 (2017)
       
  • Effects of montmorillonite (Mt) and two different organo-Mt additives on
           the performance of asphalt
    • Authors: M.A. Vargas; L. Moreno; R. Montiel; O. Manero; H. Vázquez
      Pages: 20 - 27
      Abstract: Publication date: April 2017
      Source:Applied Clay Science, Volume 139
      Author(s): M.A. Vargas, L. Moreno, R. Montiel, O. Manero, H. Vázquez
      In this work, comparative rheological tests on asphalt mixtures containing unmodified Montmorillonite (Mt) and two modified organo-Mt were carried out. The blended asphalt binders were characterized using softening point, penetration, and rheological tests, and compared with the unmodified asphalt. The nanostructure distribution of Mt platelets in asphalt was evaluated using X-ray diffraction (XRD), TEM and fluorescence microscopy. An increase in the softening point and a decrease in binder penetration were observed upon the addition of nanoparticles. Also, the elastic modulus (G′) increased significantly at low frequencies and high concentration of nano-Mt. Asphalt and nanocomposites are thermo-rheologically simple materials; the temperature dependence was modeled using the time-temperature superposition principle. The complex viscosity of 10wt.% trimethyloctadecacylammonium chloride (TMOA) in asphalt increased in two decades, whereas that of the aminopropyl-triethoxysilane/octadecyl-amine (APTES) and Mt at the same concentration increased only in one decade. The G*/sinδ values and viscosity analyses revealed that the TMOA-modified asphalt exhibited an improved viscoelastic response and resistance to rutting. Organo-nanocomposite modified-asphalt generates an intercalated structure, as revealed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Zero shear viscosity (ZSV) is important to predict the rutting behavior of asphalt binders. The ZSV of asphalt and nanocomposites were calculated using the Cross and the Carreau models.

      PubDate: 2017-01-22T10:24:18Z
      DOI: 10.1016/j.clay.2017.01.009
      Issue No: Vol. 139 (2017)
       
  • Modification of organo-montmorillonite with disodium H-phosphonate to
           develop flame retarded polyamide 6 nanocomposites
    • Authors: Tomasz M. Majka; Agnieszka Leszczyńska; Baljinder K. Kandola; Wiwat Pornwannachai; Krzysztof Pielichowski
      Pages: 28 - 39
      Abstract: Publication date: April 2017
      Source:Applied Clay Science, Volume 139
      Author(s): Tomasz M. Majka, Agnieszka Leszczyńska, Baljinder K. Kandola, Wiwat Pornwannachai, Krzysztof Pielichowski
      Montmorillonite (Mt) hold a great potential in improving inflammability of polyamide nanocomposites. This paper presents research on a novel class of flame retardants prepared by adsorption of disodium H-phosphonate (DHP) on the sodium montmorillonite (Mt) and organophilized montmorillonite (OMt) - clay surface. Using instrumental analyses including X-ray diffraction (XRD), thermogravimetric analysis (TGA), cone calorimetry, limiting oxygen index (LOI), UL-94 technique and scanning electron microscopy (SEM) the influence of DHP and Mt or OMt in PA6 on the thermal stability and fire reaction properties of PA6 was investigated. The adsorption of DHP on Mt and OMt delayed the onset of the degradation temperature of PA6 by 8 and 23°C, respectively. The flame resistance of nanocomposite with 0.75wt% of DHP stabilizer adsorbed on OMt surface was significantly improved as 59% reduction in maximum peak of heat release rate compared to neat PA6 was observed. The UL-94 and cone calorimeter results have shown that the tested materials burn differently, which are reported here as three behaviors during combustion. Based on these results it was found that the surface-modified Mt protects the polymeric material against the degradation within the temperature range used by formation of phosphorus-mineral char.

      PubDate: 2017-01-22T10:24:18Z
      DOI: 10.1016/j.clay.2017.01.012
      Issue No: Vol. 139 (2017)
       
  • Structural and dielectric comparative studies of geopolymers prepared with
           metakaolin and Tunisian natural clay
    • Authors: H. Douiri; S. Louati; S. Baklouti; M. Arous; Z. Fakhfakh
      Pages: 40 - 44
      Abstract: Publication date: April 2017
      Source:Applied Clay Science, Volume 139
      Author(s): H. Douiri, S. Louati, S. Baklouti, M. Arous, Z. Fakhfakh
      Metakaolin and calcined Tunisian natural clay were used as potential aluminosilicate sources to synthesize phosphoric acid - inorganic polymers known as geopolymers. Structural and dielectric properties of these two kinds of clay were studied. X-ray diffraction patterns showed that the main phases presented for both clays were quartz and illite. Besides, these two specimen showed a great similarity in their dielectric properties in a frequency range [102–106] Hz. Nevertheless, a dissimilarity was observed at low frequencies [1−102] Hz as a result of the difference in their mineral compositions. In a second time, a comparative study between two geopolymers made of metakaolin and the calcined natural clay was realized. New crystalline phases, produced during geopolymerization reaction were detected in both geopolymers X-ray diffraction patterns. Dielectric results revealed a difference in their dielectric parameters in the low frequency range. It resulted from a variation in charge distribution into the two geopolymer structures. However, for high frequencies a great similarity was observed for both geopolymers.

      PubDate: 2017-01-22T10:24:18Z
      DOI: 10.1016/j.clay.2017.01.018
      Issue No: Vol. 139 (2017)
       
  • Preparation and characterization of an organo-palygorskite-Fe3O4
           nanomaterial for removal of anionic dyes from wastewater
    • Authors: Antonieta Middea; Luciana S. Spinelli; Fernando Gomes Souza Jr; Reiner Neumann; Thais L.A.P. Fernandes; Otavio da F.M. Gomes
      Pages: 45 - 53
      Abstract: Publication date: April 2017
      Source:Applied Clay Science, Volume 139
      Author(s): Antonieta Middea, Luciana S. Spinelli, Fernando Gomes Souza Jr, Reiner Neumann, Thais L.A.P. Fernandes, Otavio da F.M. Gomes
      The organophilization of clays to increase interfacial interactions is a typical practice when the objective is its encapsulation with a polymer. This work intend to synthesize and characterize an organo-palygorskite-Fe3O4, to change the hydrophilicity of the material and investigate its efficiency in the removal of two anionic dyes from aqueous solution with the aim to use this material to treat wastewater contaminated with dyes. The organophilization of modified palygorskite–Fe3O4 was done with a cationic surfactant (cetyl trimethylammonium bromide, CTAB) and the material obtained was characterized by XRF, SEM, XRD, FTIR, Nano Zetasizer, density, BET surface area, TGA/DTA and contact angle measurements. XRF and FTIR confirmed the presence of carbon in the modified palygorskite–Fe3O4 nanoparticles while XRD showed new crystalline phases from CTAB. Furthermore, a positive zeta potential value appeared and an inversion in the nanoparticles' hydrophobicity happened due to the increase of organic carbon content in the organo-palygorskite-Fe3O4. The adsorbed anionic dye on organo-palygorskite-Fe3O4 may be completely recovered by the action of a magnet, showing an excellent adsorptive property and economical alternative adsorbents to treat dye wastewater. The negative values calculated for the free energies of adsorption indicate that the adsorption of methyl orange and indigo carmine on the active sites of organo-palygorskite-Fe3O4 surface was spontaneous and that the indigo carmine had the best interaction with the magnetic organo clay.

      PubDate: 2017-01-22T10:24:18Z
      DOI: 10.1016/j.clay.2017.01.017
      Issue No: Vol. 139 (2017)
       
  • Metakaolin based geopolymer as an effective adsorbent for adsorption of
           zinc(II) and nickel(II) ions from aqueous solutions
    • Authors: İlknur Kara; Dilek Yilmazer; Sibel Tunali Akar
      Pages: 54 - 63
      Abstract: Publication date: April 2017
      Source:Applied Clay Science, Volume 139
      Author(s): İlknur Kara, Dilek Yilmazer, Sibel Tunali Akar
      Metakaolin based geopolymer (MKG) was investigated as an adsorbent to remove Zn(II) and Ni(II) ions from aqueous solution. The parameters of initial pH, adsorbent amount, time of contact and initial metal ion concentration on the metal removal performance of MKG were studied using a batch method at 25°C. The amount of Zn(II) and Ni(II) ions adsorbed onto MKG increased with increasing contact time with an adsorption equilibrium being reached within 40min and 50min for Zn(II) and Ni(II), respectively. The optimum values of initial pH were 6.39 for Zn(II) and 7.25 for Ni(II). The uptake of Zn(II) and Ni(II) ions by MKG was observed to decrease by increasing the adsorbent amount. The Langmuir isotherm described the adsorption data very well and the maximum monolayer adsorption capacities determined from the Langmuir adsorption isotherm were found to be 1.14×10−3 and 7.26×10−4 molg−1 for Zn(II) and Ni(II), respectively. The kinetic studies showed that adsorption followed the pseudo-second-order kinetic model. The continuous mode adsorption studies showed the optimum flow rates were 2.0mLmin−1 for Zn(II) and 1.0mLmin−1 for Ni(II). The breakthrough points were observed at 150 and 280min for Zn(II) and Ni(II), respectively. It is concluded that Zn(II) and Ni(II) ions in aqueous solutions are efficiently removed by MKG which could be employed as a low-cost and excellent alternative for wastewater treatment.

      PubDate: 2017-01-22T10:24:18Z
      DOI: 10.1016/j.clay.2017.01.008
      Issue No: Vol. 139 (2017)
       
  • Effects of alkali on one-part alkali-activated cement synthesized by
           calcining bentonite with dolomite and Na2CO3
    • Authors: Mei Xun Peng; Zheng Hong Wang; Qiu Guo Xiao; Fei Song; Wen Xie; Liang Cai Yu; Hao Wen Huang; Shou Jun Yi
      Pages: 64 - 71
      Abstract: Publication date: April 2017
      Source:Applied Clay Science, Volume 139
      Author(s): Mei Xun Peng, Zheng Hong Wang, Qiu Guo Xiao, Fei Song, Wen Xie, Liang Cai Yu, Hao Wen Huang, Shou Jun Yi
      A novel approach was employed to synthesize one-part alkali-activated cements (AACs) for potential property/cost ratio advantage by calcining low-quality bentonite with dolomite and Na2CO3. The clinkers and the corresponding 80°C-cured hydrates were characterized with multiple analytical methods. The primitively optimized 80°C-cured paste made from the clinker calcined at 1100°C with (CaO+MgO)/SiO2 at a molar ratio of 2.1 and R2O/SiO2 at a molar ratio of 0.4 resulted in the highest 28day compressive strength of 38.3MPa, which was twice of that without alkali additive. Accompanied with glassy phases, the poorly crystallized cementing active minerals in the optimum clinker contained C3A, belite, and MgO, as identified by X-ray diffraction analysis. MgO remained inert during hydration of clinkers calcined at 1200°C or without Na2CO3 additive. Release of Ca(OH)2 during hydration of belite only appeared in the hydrates of the clinkers calcined without alkali additive, and it was used up in the hydrates of belite-containing clinkers with Na2CO3 additive. The 80°C-cured optimum hydrate was subject to the most seriously carbonization along with the most compact microstructures among all hydrates. The alkali additive improved the cementing activities of one-part R2O-MO-Al2O3-SiO2 cement system in two ways as it not only optimized the phase composition of the clinkers but also facilitated the hydration.

      PubDate: 2017-01-28T10:30:20Z
      DOI: 10.1016/j.clay.2017.01.020
      Issue No: Vol. 139 (2017)
       
  • Synthesis, characterization and optimization of
           poly(p-phenylenediamine)-based organoclay composite for Cr(VI) remediation
           
    • Authors: Lindani Mdlalose; Mohammed Balogun; Katlego Setshedi; Matshawe Tukulula; Luke Chimuka; Avashnee Chetty
      Pages: 72 - 80
      Abstract: Publication date: April 2017
      Source:Applied Clay Science, Volume 139
      Author(s): Lindani Mdlalose, Mohammed Balogun, Katlego Setshedi, Matshawe Tukulula, Luke Chimuka, Avashnee Chetty
      The contamination of the water supply with high levels of heavy metals from various human and industrial activities continues to present a major environmental problem. Heavy metals such as hexavalent chromium (Cr(VI)) are of particular concern since they pose serious health and environmental risks. Many polymeric materials with remarkable anion adsorbing properties have been developed and reported in the literature. However, there is still need to reduce the cost and/or improve the performance of these materials for environmental remediation. We report here the synthesis, characterization and application of a poly(para-phenylenediamine) (poly-pPD) organoclay-based composite for removal of Cr(VI) complexes from wastewater. Adsorption capacity of the composite was evaluated at different sample pH, contact time, adsorbent dose and initial concentration. The poly-pPD-based organoclay adsorbent with <55% of the polymer showed similar superior performance to pure polymer over a wide pH range compared to pristine organoclay. Adsorption was better described by the pseudo second-order kinetic model and Langmuir isotherm model, suggesting that chemisorption was the main mechanism of the adsorption process. The Langmuir maximum adsorption capacity for Cr(VI) was 217.4mg/g and 185.2mg/g whereas for total Cr it was 193.3mg/g and 148.8mg/g for poly-pPD and poly-pPD-organoclay, respectively. Using XPS, it was proven that the adsorbent also reduces Cr(VI) to Cr (III). The prepared poly-pPD-organoclay showed reuse over seven times but still retaining 80% of the recovery for Cr(VI). The composite also performed excellently in batch application to real industrial wastewater containing high levels of Cr(VI) ions and competing anions such as nitrates and sulfates.

      PubDate: 2017-01-28T10:30:20Z
      DOI: 10.1016/j.clay.2017.01.015
      Issue No: Vol. 139 (2017)
       
  • Organomontmorillonite/graphene-PLA/PCL nanofilled blends: New strategy to
           enhance the functional properties of PLA/PCL blend
    • Authors: Boubkeur Seddik Bouakaz; Abderrahmane Habi; Yves Grohens; Isabelle Pillin
      Pages: 81 - 91
      Abstract: Publication date: April 2017
      Source:Applied Clay Science, Volume 139
      Author(s): Boubkeur Seddik Bouakaz, Abderrahmane Habi, Yves Grohens, Isabelle Pillin
      The aim of this work is to study the effect of combining organomontmorillonites (Cloisite®15A and Cloisite®30B) with epoxy functionalized graphene on the morphology and different properties of a polylactic acid (PLA)/poly(ε-caprolactone) (PCL) blend. To this end, rheological, morphological, barrier and thermal properties were evaluated. The use of nanofiller mixtures caused significant enhancements in terms of storage and loss modulus of a PLA/PCL matrix, indicating a high degree of co-reinforcement in comparison to that observed when the nanofillers were filled separately. The results from transmission electron microscopy and the non-dependency of the storage modulus in the low frequencies showed that both graphene sheets and clay mineral layers resulted in a fine dispersion and better exfoliation in the PLA/PCL blend matrix. The compatibility of the biodegradable PLA/PCL blend was improved in the presence of organoclays and organoclay/graphene mixtures. PLA/PCL nanofilled blends exhibited higher barrier properties than the pure blend and interesting values were obtained by adding hybrids of organomontmorillonite and graphene, which were linked to their degree of intercalation and also to the existence of synergy between these nanofillers. Melt blending of PLA/PCL and all different nanofillers induced significant improvements of thermal stability. The use of filler mixtures to prepare composite materials is a very interesting way to have the best properties using classical methods of preparation.
      Graphical abstract image

      PubDate: 2017-01-28T10:30:20Z
      DOI: 10.1016/j.clay.2017.01.014
      Issue No: Vol. 139 (2017)
       
  • Removal of manganese (II) by edge site adsorption on raw and milled
           vermiculites
    • Authors: B. Kebabi; S. Terchi; H. Bougherara; L. Reinert; L. Duclaux
      Pages: 92 - 98
      Abstract: Publication date: April 2017
      Source:Applied Clay Science, Volume 139
      Author(s): B. Kebabi, S. Terchi, H. Bougherara, L. Reinert, L. Duclaux
      The adsorption mechanism of manganese nitrate on vermiculite was studied by analysis of the isotherms of the cations exchanged from the vermiculite (K+ and Ca2+) and the ions (NO3 − and Mn2+) adsorbed on the vermiculite. The Langmuir-type manganese adsorption isotherm of the raw vermiculite shows a maximum uptake of 28.32mg·g−1. The adsorption temperature dependence between 25°C and 45°C has demonstrated an endothermic and spontaneous adsorption. The amount of exchanged Mn2+ ions in equivalent per gram represents only 17% of the total adsorbed uptake, of which 14% have been exchanged against Ca2+ ions and 3% against K+ ions. 83% of the Mn2+ and NO3 − ions have been co-adsorbed by complexation at the edges of the layers. The grinding of the vermiculite has involved a decrease in the grains size from 2–3mm to 100μm and thus an increase in the edge layer adsorption site content allowing an increase of 19% of the maximum adsorption uptake compared to raw vermiculite. The ultrasonic milling of vermiculite in aqueous dispersion at 20kHz allowed to decrease the size of the grains further (8μm) and led to increase the maximum uptake by 31%. The sonication of the vermiculite dispersion in 35% hydrogen peroxide has allowed to obtain a maximum adsorption uptake of 36.77mg·g−1 (30% of increase compared to raw vermiculite). The linear variation of the Mn2+ adsorption capacity with respect to the sum of the estimated geometric perimeter of the sonicated particles (assuming square shaped particles) confirms an adsorption process at the edge of layers.
      Graphical abstract image

      PubDate: 2017-01-28T10:30:20Z
      DOI: 10.1016/j.clay.2016.12.041
      Issue No: Vol. 139 (2017)
       
  • The importance of specific surface area in the geopolymerization of heated
           illitic clay
    • Authors: Jan Dietel; Laurence N. Warr; Marko Bertmer; Annett Steudel; Georg H. Grathoff; Katja Emmerich
      Pages: 99 - 107
      Abstract: Publication date: April 2017
      Source:Applied Clay Science, Volume 139
      Author(s): Jan Dietel, Laurence N. Warr, Marko Bertmer, Annett Steudel, Georg H. Grathoff, Katja Emmerich
      Geopolymers are inorganic binders formed by adding alkaline (hydroxide) solution to silicates such as blast furnace slag, fly ash or calcined clay to dissolve Si and Al that polymerizes and precipitates while hardening. The most common clay used as geopolymer raw material is kaolin. The aim of this study was to investigate the suitability of clays dominated by 2:1 dioctahedral layer silicates using the example of Friedland clay as a cheaper alternative to kaolin and determine the necessary preparation steps required to produce an effective geopolymer binder material. After a Rietveld-based quantification of the raw clay, the successive thermal modifications of the mineral phases were analyzed using simultaneous thermal analysis coupled with mass spectrometer (STA-MS), temperature-resolved X-ray diffraction (TXRD), and 27Al solid-state nuclear magnetic resonance spectroscopy (NMR) measurements. Friedland clay heated to 875°C was found to produce a geopolymer with the highest compressive strength, but in contrast to the literature, the Si:Al ratio and the amount of 5-fold coordinated Al were not found to be the key parameters that determined the success of geopolymer synthesis. The specific surface area and the amount of Si and Al dissolved are here reported to be the key factors determining the suitability of clays dominated by 2:1 dioctahedral layer silicates as raw materials for geopolymer production.

      PubDate: 2017-02-11T16:26:07Z
      DOI: 10.1016/j.clay.2017.01.001
      Issue No: Vol. 139 (2017)
       
  • Immobilization of a cationic manganese(III) porphyrin on lithium gordaite
           (LiZn4(OH)6(SO4)Cl·6H2O), a layered hydroxide salt with cation exchange
           capacity
    • Authors: Swami Arêa Maruyama; Kátia Cristina Molgero Westrup; Shirley Nakagaki; Fernando Wypych
      Pages: 108 - 111
      Abstract: Publication date: April 2017
      Source:Applied Clay Science, Volume 139
      Author(s): Swami Arêa Maruyama, Kátia Cristina Molgero Westrup, Shirley Nakagaki, Fernando Wypych
      Sodium gordaite (NaG - NaZn4(OH)6(SO4)Cl·6H2O) was synthesized, characterized and the intercalated sodium cations (in hydrated state) of NaG were replaced by lithium where the basal parameter was altered from 13.03Å to 17.84Å. The obtained lithium gordaite (LiG) was used as support for the immobilization of a cationic manganese(III) porphyrin (MnP) on the outer surfaces of the layered crystals. Before and after MnP immobilization, the material was investigated by several instrumental techniques, showing that this class of layered compounds is a new alternative for the immobilization of cationic species for a broad range of potential applications.
      Graphical abstract image

      PubDate: 2017-02-11T16:26:07Z
      DOI: 10.1016/j.clay.2017.01.010
      Issue No: Vol. 139 (2017)
       
  • Basic activation of lower Eocene clay from Meknassy-Mezzouna basin
           (centerwestern Tunisia), synthesis of zeolite and clarification of soybean
           oils
    • Authors: Mohamed Mosbahi; Ali Tlili; Mahmoud Khlifi; Fakher Jamoussi
      Pages: 1 - 11
      Abstract: Publication date: 15 March 2017
      Source:Applied Clay Science, Volume 138
      Author(s): Mohamed Mosbahi, Ali Tlili, Mahmoud Khlifi, Fakher Jamoussi
      The present work is interested particularly in a basic activation of smectitic clay by solid Na2CO3. The clay samples, belonging to Ypresian Chouabine formation, are taken from the lithological section made in the Oued Errizgui (Jebel Meheri El Jebbes) in the Meknassy-Mezzouna basin. Chemical characterization and mineralogical study shows that studied clays are mostly smectitic and associated with a small amount of sepiolite and palygorskite. The accessory minerals correspond to quartz and dolomite. Moreover, relatively high specific surface (50.47m2/g) encourages the activation of these clays by Na2CO3. Thus, the optimal activation conditions were obtained for 5% Na2CO3 at 75°C during 1h. Under these conditions, the specific surface of smectitic clays increases to 58.63m2/g. The basic activation can cause dissolution of dolomites, crystal grow of zeolites, recrystallization of smectite and Na=Ca ionic exchange between Ca-smectite and basic solution. The activated smectitic clays provide better results compared to those given by the Tonsil product used for the clarification of neutral soybean oils by the refinery of SATHOP and SOZITEX companies. In fact, the bleaching power of the activated clay is much better (71.48%) than that of the Tonsil (56.12%). This is corroborated by the visual examination of the clarified oils.

      PubDate: 2017-01-07T01:26:29Z
      DOI: 10.1016/j.clay.2016.12.011
      Issue No: Vol. 138 (2017)
       
  • Preparation and performance of amine-tartaric salt as potential clay
           swelling inhibitor
    • Authors: Gang Chen; Jiao Yan; Li Lili; Jie Zhang; Xuefan Gu; Hua Song
      Pages: 12 - 16
      Abstract: Publication date: 15 March 2017
      Source:Applied Clay Science, Volume 138
      Author(s): Gang Chen, Jiao Yan, Li Lili, Jie Zhang, Xuefan Gu, Hua Song
      A series of small molecular clay swelling inhibitor was prepared with tartaric acid and amines, presented as amine-tartaric salts (ATS). The inhibitor was screened based on the linear expansion rate of bentonite. The results show that the inhibitor prepared with tartaric acid and triethylenetetramine with the mole ratio of 1:1 (named as ATS-4) is the best inhibitor of the hydration expansion and dispersion of bentonite. The inhibitive properties of ATS-4 were evaluated by various methods, including clay linear swelling tests, anti-swelling tests, mud ball immersing tests, mud-making inhibition experiments and particle distribution measurements etc. The results show that ATS-4 has superior performance to inhibit the hydration swelling and dispersion of clays by controlling the particle size of clay. On the other hand, the bentonite linear expansion rate in 0.5% ATS-4 aqueous solution is much lower than that of others, and the hydration expansion degree of the mud ball in ATS-4 aqueous solution is appreciably weaker than the control test, and it is compatible with the conventional additives in water-based drilling fluids. Then, the inhibition mechanism of the amine-tartaric salt was well discussed based on thermogravimetric analysis (TGA), scanning electron microscope (SEM), X-ray diffraction analysis (XRD), single crystal X-ray diffraction and ion exchange tests.

      PubDate: 2017-01-07T01:26:29Z
      DOI: 10.1016/j.clay.2016.12.039
      Issue No: Vol. 138 (2017)
       
  • In situ ion induced gelation of colloidal dispersion of Laponite: Relating
           microscopic interactions to macroscopic behavior
    • Authors: Rashmi P. Mohanty; Khushboo Suman; Yogesh M. Joshi
      Pages: 17 - 24
      Abstract: Publication date: 15 March 2017
      Source:Applied Clay Science, Volume 138
      Author(s): Rashmi P. Mohanty, Khushboo Suman, Yogesh M. Joshi
      Aqueous dispersion of Laponite, when exposed to CO2 environment leads to in situ inducement of magnesium and lithium ions, which is, however absent when dispersion is exposed to air. Consequently, in the rheological experiments, Laponite dispersion preserved under CO2 shows more spectacular enhancement in the elastic and viscous moduli as a function of time compared to that exposed to air. By measuring concentration of all the ions present in a dispersion as well as change in pH, the evolving inter-particle interactions among the Laponite particles is estimated. DLVO analysis of a limiting case is performed, wherein two particles approach each other in a parallel fashion – a situation with maximum repulsive interactions. Interestingly it is observed that DLVO analysis explains the qualitative details of an evolution of elastic and viscous moduli remarkably well thereby successfully relating the macroscopic phenomena to the microscopic interactions.
      Graphical abstract image

      PubDate: 2017-01-07T01:26:29Z
      DOI: 10.1016/j.clay.2016.12.036
      Issue No: Vol. 138 (2017)
       
  • Highly luminescent hybrid materials based on smectites with polyethylene
           glycol modified with rhodamine fluorophore
    • Authors: Samuel Sas; Martin Danko; Valéria Bizovská; Kamil Lang; Juraj Bujdák
      Pages: 25 - 33
      Abstract: Publication date: 15 March 2017
      Source:Applied Clay Science, Volume 138
      Author(s): Samuel Sas, Martin Danko, Valéria Bizovská, Kamil Lang, Juraj Bujdák
      Highly luminescent anisotropic materials are promising for light harvesting systems, sensors, solid lasers and optical devices. To achieve this, polyethylene glycol (PEG) was derivatized with a reactive rhodamine B (RhB) fluorophore to produce a luminescent, water-soluble and positively-charged polymer (RhPEG) that can be intercalated between layers of smectites. An optimal degree of polymer derivatization was applied to avoid fluorescence quenching. The optical properties of RhPEG were similar to those of the RhB precursor. Colloids were prepared using RhPEG and the montmorillonite Kunipia (Mt) and the synthetic saponite Sumecton (Sap), with polymer/smectite mass ratios of 0.05–0.25, and were cast into thin solid films by a vacuum filtration deposition technique. The luminescent hybrid films exhibited a similar structure to those obtained by the intercalation of non-modified PEG. Optical properties depended considerably on the smectite type. The hybrid films made of Sap, the smectite with low charge density, negligibly induced the molecular aggregation of RhPEG and had high fluorescence quantum yields, similar to dilute solutions of RhB or RhPEG. On the other hand, the results of spectroscopic methods indicated molecular aggregation of RhPEG when intercalated between Mt layers leading to considerable fluorescence quenching, making this material unsuitable for the fabrication of photoactive optical films.
      Graphical abstract image

      PubDate: 2017-01-07T01:26:29Z
      DOI: 10.1016/j.clay.2016.12.034
      Issue No: Vol. 138 (2017)
       
  • Beneficiation and influencing factors of coal-series kaolin for the
           reduction of COD
    • Authors: Teng Huang; Shaomin Lei; Yuanyuan Liu; Mengjiao Ji; Yanming Fan
      Pages: 34 - 39
      Abstract: Publication date: 15 March 2017
      Source:Applied Clay Science, Volume 138
      Author(s): Teng Huang, Shaomin Lei, Yuanyuan Liu, Mengjiao Ji, Yanming Fan
      Coal-series kaolin is the product of seam deposition in coal-accumulating basin. With the high content of reducing substances such as pyrite and fossil, the COD (chemical oxygen demand) can range from 5000 to 30,000μg/g in coal-series kaolin, which is a serious disadvantage for the clarification of glass industry. Through reverse flotation, the COD has effectively enriched in flotation froth products, while the COD in flotation concentrate is 3533μg/g, and can be reduced to 290μg/g at 450°C, which is only <2% of the raw ore. The oxidizing roasting of flotation concentrate has great significance for the decreasing of COD in the coal-series kaolin. Pyrite would also have great influence on the reduction of COD, with a high degree of oxidation, COD decreases more significantly, and the content of pyrite shows linear correlation with COD, which would provide an approximate method to evaluate the COD in coal-series kaolin.

      PubDate: 2017-01-07T01:26:29Z
      DOI: 10.1016/j.clay.2016.12.032
      Issue No: Vol. 138 (2017)
       
  • Development, characterization and cytotoxicity of novel silane-modified
           clay minerals and nanocomposites intended for food packaging
    • Authors: Sara Maisanaba; Natalia Ortuño; María Jordá-Beneyto; Susana Aucejo; Ángeles Jos
      Pages: 40 - 47
      Abstract: Publication date: 15 March 2017
      Source:Applied Clay Science, Volume 138
      Author(s): Sara Maisanaba, Natalia Ortuño, María Jordá-Beneyto, Susana Aucejo, Ángeles Jos
      Layered silicates are largely used to develop polymer nanocomposites with improved physical properties compared to the original polymeric matrix. In this work, the silylation of sodium montmorillonite (Mt) was performed in distilled water using 3-aminopropyltriethoxysilane and vinyltrimethoxysilane, obtaining two different silane modified clay minerals named Clay3 and Clay4, respectively. Clay3 indicated a better profile with a notable increase in the interlayer space compared to Mt. For this reason, Clay3 was selected to scale up its production and to be incorporated in polypropylene (PP) matrix. The PP-Clay3 nanocomposite showed an enhancement in elasticity, a reduction of 15% in the oxygen transmission rate and important antimicrobial effects in comparison to pristine PP. Also, for the first time, cytotoxic effects in human cell lines exposed to Clay3 and Clay4 were evaluated. No cytotoxic damage was observed after Clay3 exposure but an important decrease in cell viability was produced by Clay4. The PP-Clay3 nanocomposite is an attractive alternative for the food packaging industry although further work is needed to get better results in the case of Clay4. Moreover, individual case by case evaluation of clay minerals under different conditions is required in order to obtain the most complete toxicity information.
      Graphical abstract image

      PubDate: 2017-01-07T01:26:29Z
      DOI: 10.1016/j.clay.2016.12.042
      Issue No: Vol. 138 (2017)
       
  • The corrosion of kaolinite by iron minerals and the effects on
           geopolymerization
    • Authors: R.C. Kaze; L.M. Beleuk à Moungam; M.L. Fonkwe Djouka; A. Nana; E. Kamseu; U.F. Chinje Melo; C. Leonelli
      Pages: 48 - 62
      Abstract: Publication date: 15 March 2017
      Source:Applied Clay Science, Volume 138
      Author(s): R.C. Kaze, L.M. Beleuk à Moungam, M.L. Fonkwe Djouka, A. Nana, E. Kamseu, U.F. Chinje Melo, C. Leonelli
      Iron-rich aluminosilicates with disordered structure (laterites) due to the corrosion of kaolinite by iron minerals were investigated as solid precursors for geopolymerization. The particle size distribution, B.E.T surface area, thermal activation, and chemical and mineralogical compositions were used to evaluate the reactivity of iron-rich laterites (35wt.% of Fe2O3-FeO). The raw materials in the temperature range between 25 and 500°C showed geopolymerization behaviour similar to that of metakaolin. At temperatures higher than 500°C, the coarsening of particles and the decrease of B.E.T surface area correspond to an initial sintering of laterites explaining the poor polycondensation/geopolymerization and the decrease of strength of the final products. The increase of the temperature of calcination of raw laterites between 25 and 500°C corresponds to a reduction of the setting time of geopolymer products. However, this variation of temperature did not significantly affect the flexural strength that remained between ~4 and ~6MPa, confirming the possibility to produce sustainable matrices, with more energy saving, using highly corroded laterites.
      Graphical abstract image

      PubDate: 2017-01-07T01:26:29Z
      DOI: 10.1016/j.clay.2016.12.040
      Issue No: Vol. 138 (2017)
       
  • Thermal stability of tetrabutyl-phosphonium and -ammonium exchanged
           montmorillonite: Influence of acid treatment
    • Authors: Helena Pálková; Małgorzata Zimowska; Ľuboš Jankovič; Bogdan Sulikowski; Ewa M. Serwicka; Jana Madejová
      Pages: 63 - 73
      Abstract: Publication date: 15 March 2017
      Source:Applied Clay Science, Volume 138
      Author(s): Helena Pálková, Małgorzata Zimowska, Ľuboš Jankovič, Bogdan Sulikowski, Ewa M. Serwicka, Jana Madejová
      Thermal stability of acid-treated organo-montmorillonites was investigated by thermogravimetric analysis (TA) coupled with infrared (IR) spectroscopic analysis of evolved gasses, and by in-situ measurement of near-IR (NIR) spectra of solid samples. The organoclays prepared from Na-form of SAz-1 montmorillonite (Na-S) and tetrabutylphosphonium (Bu4P+) and tetrabutylammonium (Bu4N+) salts were treated with 6M HCl at 80°C for 2–12h. Elemental analysis revealed higher resistance of Bu4P-S and Bu4N-S to decomposition compared to Na-S, leaving 44 and 52% of the octahedral Mg and/or Al in the solid reaction products after 12h treatment. Bu4N-S decomposed in slightly lower extent than Bu4P-S, pointing thus to the influence of the type of cation headgroup on its stability in HCl. The TG/DTG profiles of both samples showed pronounced mass loss due to decomposition of organic cations within temperature 200–800°C. While Bu4N-S showed onset temperature of near 200°C, significantly higher temperatures, above 300°C, was found for Bu4P-S. The intensities of the absorption bands related to CH vibrations of aliphatic hydrocarbons in the IR spectra reached maxima at 277°C and 446°C for Bu4N-S and Bu4P-S, respectively. The mass loss attributed to the organic cation decomposition for acid-treated samples dropped down below 50% of its initial value due to the leaching of organic phase. Moreover, the onset temperature of organic phase release was shifted to higher temperature indicating that only more strongly held cations remained in the samples. NIR spectra showed that the intensity decrease of the first 2νCH overtones band due to organic cation release began at lower temperature for Bu4N-S (above 380°C) than for Bu4P-S (above 500°C).
      Graphical abstract image

      PubDate: 2017-01-14T07:49:10Z
      DOI: 10.1016/j.clay.2016.12.043
      Issue No: Vol. 138 (2017)
       
  • Effects of formation and penetration properties of biodegradable
           montmorillonite/chitosan nanocomposite film on the barrier of package
           paper
    • Authors: Shanhui Wang; Yi Jing
      Pages: 74 - 80
      Abstract: Publication date: 15 March 2017
      Source:Applied Clay Science, Volume 138
      Author(s): Shanhui Wang, Yi Jing
      The conventional package paper was coated with biodegradable montmorillonite/chitosan nanocomposite, in order to extend the application scope of paper. The effect of coating weight, montmorillonite dispersion rate, montmorillonite and dispersant content on the surface and penetration properties of montmorillonite/chitosan nanocomposite coated paper were being investigated. The surface properties of the coated paper were observed by using scanning electron microscope (SEM) and atomic force microscope (AFM). The water permeation and water vapor barrier properties were confirmed through penetration dynamics analyzer (PDA) and water vapor permeability tester (WVP), respectively. The results indicated that montmorillonite/chitosan nanocomposite had a poorer formation than pure chitosan, but it had better water vapor barrier properties. The paper coated with lower content of montmorillonite, or with higher dispersion speed and dispersant content, had better smoothness and elongation. Additionally, the coated paper had excellent barrier properties under the conditions of high montmorillonite and dispersant content, dispersion rate and coating weight.

      PubDate: 2017-01-14T07:49:10Z
      DOI: 10.1016/j.clay.2016.12.037
      Issue No: Vol. 138 (2017)
       
  • Effects of microbial cells and their associated extracellular polymeric
           substances on the bio-flocculation of kaolin and quartz
    • Authors: Ramin Akbari Ghashoghchi; Mohammad Raouf Hosseini; Ali Ahmadi
      Pages: 81 - 88
      Abstract: Publication date: 15 March 2017
      Source:Applied Clay Science, Volume 138
      Author(s): Ramin Akbari Ghashoghchi, Mohammad Raouf Hosseini, Ali Ahmadi
      Microbes can function as bio-surfactants to selectively flocculate or disperse particles, and separate minerals. In the present study, Bacillus licheniformis cells and metabolite were used to change the settling behavior of kaolin and quartz. Moreover, to perform a more detailed study on the metabolite, settling effect of its protein and polysaccharide constituents were also investigated separately. In the best condition, about 40% improvement in kaolin settling was observed using bacterial cells and metabolite at pH=7 and 3, respectively. Also, enhancement in quartz sedimentation using the same bio-flocculants was >50% at pH=1–3. In addition, polysaccharide was more effective in kaolin flocculation, while protein was more influential in quartz agglomeration. Results of adsorption tests suggested that all of the bio-surfactants were more inclined to be adsorbed on quartz, and generally, increasing the pH value decreased the reagent adsorption and mineral flocculation. Moreover, although reducing the mineral concentration from 50 to 20g/l improved the settling of both kaolin and quartz, the highest difference (50%) in their sedimentation occurred at the higher mineral concentration. Finally, according to the statistics, clay concentration was the most influential parameter on kaolin, and the dispersion pH was the most effective variable in quartz bio-flocculation.

      PubDate: 2017-01-14T07:49:10Z
      DOI: 10.1016/j.clay.2017.01.002
      Issue No: Vol. 138 (2017)
       
  • Stearic acid modified montmorillonite as emerging microcapsules for
           thermal energy storage
    • Authors: Kang Peng; Liangjie Fu; Xiaoyu Li; Jing Ouyang; Huaming Yang
      Pages: 100 - 106
      Abstract: Publication date: 15 March 2017
      Source:Applied Clay Science, Volume 138
      Author(s): Kang Peng, Liangjie Fu, Xiaoyu Li, Jing Ouyang, Huaming Yang
      In order to obtain an efficient phase change material (PCM), emerging montmorillonite/stearic acid (Mt/SA) microcapsules containing SA core with Mt shell were designed and prepared via self-assembly of Mt in the SA emulsion. The Mt/SA microcapsules were coated with SiO2 from the hydrolysis and polycondensation of TEOS to enhance the structure stability. The microstructure, thermal properties and reliability of Mt/SA microcapsules were investigated via scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The Mt/SA microcapsules presented sphere-like particles and had a size distribution from 10 to 30μm. The freezing latent heat of the Mt/SA microcapsules was 118J/g at 52.3°C. The energy storage rate of the Mt/SA microcapsules was faster compared to SA. The Mt/SA microcapsules had excellent structural stability, high energy storage capacity and stable energy storage and release performances. The energy storage performances of the Mt/SA microcapsules were superior to the Mt/SA composites prepared via vacuum impregnation. Excellent energy storage reliability and capability of the Mt/SA microcapsules have advantages for solar energy storage fields.
      Graphical abstract image

      PubDate: 2017-01-22T10:24:18Z
      DOI: 10.1016/j.clay.2017.01.003
      Issue No: Vol. 138 (2017)
       
  • Graphitic-C3N4 modified ZnAl-layered double hydroxides for enhanced
           photocatalytic removal of organic dye
    • Authors: Xiaoya Yuan; Wenyu Li
      Pages: 107 - 113
      Abstract: Publication date: 15 March 2017
      Source:Applied Clay Science, Volume 138
      Author(s): Xiaoya Yuan, Wenyu Li
      Layered double hydroxides (LDH) are one of the most important photocatalyts intensively investigated for photodecolorization of organic dyes. ZnAl-LDH was successfully modified with graphitic-C3N4 (g-C3N4) by a simple in situ crystallization technique. The obtained C3N4/ZnAl-LDH composites were thoroughly characterized by Scanning electron microscopy (SEM), High-resolution transmission electron microscopy (HRTEM), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–Vis diffuse reflectance spectroscopy (DRS). The detailed analysis indicated that g-C3N4 sheets could act as substrate to induce the growth of LDH crystallites and ZnAl-LDH platelets randomly distributed on the sheets with a strong interaction between them. The photocatalytic activities of C3N4/ZnAl-LDH composites toward decolorization of methylene blue (MB) highly depended on the loading of g-C3N4. At the g-C3N4 weight loading of 18%, the rate constant of C3N4/ZnAl-LDH was more than five times and nearly two times than that of pure ZnAl-LDH and g-C3N4 respectively. The enhanced activity of C3N4/ZnAl-LDH composites could be ascribed to the synergistic effect between two components of the composites.
      Graphical abstract image

      PubDate: 2017-01-22T10:24:18Z
      DOI: 10.1016/j.clay.2017.01.004
      Issue No: Vol. 138 (2017)
       
  • Middle Eocene clay from Goset Abu Khashier: Geological assessment and
           utilization with drinking water treatment sludge in brick manufacture
    • Authors: MA Tantawy; Ramadan SA Mohamed
      Pages: 114 - 124
      Abstract: Publication date: 15 March 2017
      Source:Applied Clay Science, Volume 138
      Author(s): MA Tantawy, Ramadan SA Mohamed
      This investigation aims to study the physico-ceramic properties of bricks that were made from the Goset Abu Khashier clay (Qarara Formation, Middle Eocene deposits, El-Minia, Egypt) replaced with 15–60wt% drinking water treatment sludge (DWTS). The Qarara Formation deposits located in the east bank of the Nile River between Beni Suef and El-Minia Governorates, belong to the Middle Eocene deposits. The Qarara Formation deposits in the Goset Abu Khashier area contain several million tons of clay deposits. The Qarara Formation is composed of a grey to green shale (silty clay) grading upward to marl and limestone. The clay contains kaolinite (29wt%), montmorillonite (20wt%), albite (27wt%) and quartz (23wt%). The clay contains a high content of silica (49.41wt%) and a low content of alumina (19.77wt%) with considerable amounts of Fe2O3 (11.37wt%) and fluxing oxides (3.7wt%). Clay bricks containing 15–60wt% DWTS were fired at a temperature of 700–1000°C. The ceramic properties of bricks were determined according to the ASTM specifications. The phase composition of bricks was determined by XRD, FTIR and SEM techniques. It was investigated that the incorporation of DWTS in the body of clay bricks moderates the ceramic properties of fired bricks to be in agreement with the limiting values that were recommended for traditional bricks. XRD results illustrated that dehydration of kaolinite and the formation of metakaolinite facilitates vitrification and contributes to brick densification. FTIR results showed the formation of a wollastonite phase and indicated that increasing DWTS content facilitates the persistence of a vitrified phase. SEM micrographs illustrated that the porosity and densification of brick matrix was affected by the formation of amorphous vitreous phases and decreased with DWTS contents. It is recommended that the replacement of examined clay by 15–30wt% of DWTS is considered as the appropriate percentage for building bricks production and minimizes environmental impacts due to DWTS disposal into water bodies.

      PubDate: 2017-01-22T10:24:18Z
      DOI: 10.1016/j.clay.2017.01.005
      Issue No: Vol. 138 (2017)
       
  • Effects of raw and heated palygorskite on rumen fermentation in vitro
    • Authors: H.F. Zeng; L.J. Lin; Y.M. Xi; Z.Y. Han
      Pages: 125 - 130
      Abstract: Publication date: 15 March 2017
      Source:Applied Clay Science, Volume 138
      Author(s): H.F. Zeng, L.J. Lin, Y.M. Xi, Z.Y. Han
      To investigate the effect of raw and heated palygorskite on rumen fermentation in an in vitro gas-production system, 54 incubators were evenly divided into three groups: control (0% palygorskite), treatment I (3% raw palygorskite) and treatment II (3% heated palygorskite). The effect of heated modification on the microstructure of palygorskite was investigated by X-ray diffraction and scanning electron microscopy analyses. The physicochemical features were evaluated by zeta potential analysis, cation-exchange capacity, ethylene blue absorption and specific surface area (the BET method). Gas production (GP) was recorded at 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22 and 24h of incubation in vitro. The 18 incubators from each group were stopped at 6h, 12h and 24h, respectively, and the inoculants were determined for rumen fermentation parameters. The results showed that the GP in the treatment groups was higher than in the control group starting at 4h of incubation (P <0.05). Compared with the controls, adding raw palygorskite increased the concentrations of acetate and total volatile fatty acids (TVFAs) at 6h (P <0.05). Adding heated palygorskite increased the concentrations of acetate at 6h and 24h (P <0.05), of propionate at 12h (P <0.05), of acetate/propionate (A/P) at 6h (P <0.05) and of TVFAs at 6h and 24h (P <0.05). The concentrations of lactic acid in the treatment groups were lower than in the control group at 12h (P <0.05), while pH was higher at 12h and 24h (P <0.05, range 6–7). The concentration of NH3-N in the treatment I group was higher than in the control group at 24h (P <0.01), while in the treatment II group, it was higher at 12 and 24h (P <0.05). The results indicated that supplemental raw and heated palygorskite could improve rumen microbial fermentation, promote VFA formation and nitrogen use, especially when adding heated palygorskite.

      PubDate: 2017-01-22T10:24:18Z
      DOI: 10.1016/j.clay.2017.01.006
      Issue No: Vol. 138 (2017)
       
 
 
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