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  Subjects -> EARTH SCIENCES (Total: 651 journals)
    - EARTH SCIENCES (466 journals)
    - GEOLOGY (73 journals)
    - GEOPHYSICS (28 journals)
    - HYDROLOGY (21 journals)
    - OCEANOGRAPHY (63 journals)

EARTH SCIENCES (466 journals)                  1 2 3 | Last

Showing 1 - 200 of 371 Journals sorted alphabetically
Acta Geochimica     Hybrid Journal   (Followers: 5)
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: 8)
Acta Geotechnica     Hybrid Journal   (Followers: 7)
Acta Meteorologica Sinica     Hybrid Journal   (Followers: 3)
Advances in High Energy Physics     Open Access   (Followers: 19)
Advances In Physics     Hybrid Journal   (Followers: 19)
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: 5)
AMBIO     Hybrid Journal   (Followers: 15)
Anales del Instituto de la Patagonia     Open Access   (Followers: 1)
Andean geology     Open Access   (Followers: 13)
Annales Henri Poincaré     Hybrid Journal   (Followers: 3)
Annales UMCS, Geographia, Geologia, Mineralogia et Petrographia     Open Access  
Annals of Geophysics     Open Access   (Followers: 13)
Annals of GIS     Hybrid Journal   (Followers: 22)
Annual Review of Marine Science     Full-text available via subscription   (Followers: 11)
Anthropocene     Hybrid Journal   (Followers: 3)
Anthropocene Review     Hybrid Journal   (Followers: 6)
Applied Clay Science     Hybrid Journal   (Followers: 5)
Applied Geochemistry     Hybrid Journal   (Followers: 14)
Applied Geomatics     Hybrid Journal   (Followers: 3)
Applied Geophysics     Hybrid Journal   (Followers: 8)
Applied Ocean Research     Hybrid Journal   (Followers: 5)
Applied Petrochemical Research     Open Access   (Followers: 2)
Aquatic Conservation Marine and Freshwater Ecosystems     Hybrid Journal   (Followers: 36)
Arctic Science     Open Access   (Followers: 6)
Arctic, Antarctic, and Alpine Research     Full-text available via subscription   (Followers: 9)
Artificial Satellites : The Journal of Space Research Centre of Polish Academy of Sciences     Open Access   (Followers: 19)
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: 2)
Atlantic Geology : Journal of the Atlantic Geoscience Society / Atlantic Geology : revue de la Société Géoscientifique de l'Atlantique     Full-text available via subscription   (Followers: 10)
Atmosphere-Ocean     Full-text available via subscription   (Followers: 12)
Atmospheric and Climate Sciences     Open Access   (Followers: 28)
Australian Journal of Earth Sciences: An International Geoscience Journal of the Geological Society of Australia     Hybrid Journal   (Followers: 11)
Boletim de Ciências Geodésicas     Open Access  
Boreas: An International Journal of Quaternary Research     Hybrid Journal   (Followers: 10)
Bragantia     Open Access   (Followers: 2)
Bulletin of Earthquake Engineering     Hybrid Journal   (Followers: 11)
Bulletin of Geosciences     Open Access   (Followers: 10)
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: 18)
Cadernos de Geociências     Open Access  
Canadian Mineralogist     Full-text available via subscription   (Followers: 4)
Canadian Water Resources Journal     Hybrid Journal   (Followers: 20)
Carbonates and Evaporites     Hybrid Journal   (Followers: 3)
CATENA     Hybrid Journal   (Followers: 5)
Chemical Geology     Hybrid Journal   (Followers: 20)
Chemie der Erde - Geochemistry     Hybrid Journal   (Followers: 4)
Chinese Geographical Science     Hybrid Journal   (Followers: 5)
Chinese Journal of Oceanology and Limnology     Hybrid Journal   (Followers: 4)
Ciencia del suelo     Open Access   (Followers: 2)
Ciencias Espaciales     Open Access  
Climate and Development     Hybrid Journal   (Followers: 12)
Coastal Management     Hybrid Journal   (Followers: 25)
Cogent Geoscience     Open Access  
Comptes Rendus Geoscience     Full-text available via subscription   (Followers: 8)
Computational Geosciences     Hybrid Journal   (Followers: 14)
Computational Mathematics and Mathematical Physics     Hybrid Journal   (Followers: 3)
Computers and Geotechnics     Hybrid Journal   (Followers: 10)
Contemporary Trends in Geoscience     Open Access   (Followers: 3)
Continental Shelf Research     Hybrid Journal   (Followers: 9)
Contributions to Mineralogy and Petrology     Hybrid Journal   (Followers: 12)
Contributions to Plasma Physics     Hybrid Journal   (Followers: 3)
Coral Reefs     Hybrid Journal   (Followers: 18)
Cretaceous Research     Hybrid Journal   (Followers: 8)
Cybergeo : European Journal of Geography     Open Access   (Followers: 6)
Depositional Record     Open Access  
Developments in Geotectonics     Full-text available via subscription   (Followers: 3)
Developments in Quaternary Science     Full-text available via subscription   (Followers: 3)
Développement durable et territoires     Open Access   (Followers: 3)
Diatom Research     Hybrid Journal   (Followers: 2)
Doklady Physics     Hybrid Journal   (Followers: 1)
Dynamics of Atmospheres and Oceans     Hybrid Journal   (Followers: 11)
E&S Engineering and Science     Open Access  
E3S Web of Conferences     Open Access  
Earth and Planetary Science Letters     Hybrid Journal   (Followers: 130)
Earth and Space Science     Open Access   (Followers: 14)
Earth Interactions     Full-text available via subscription   (Followers: 13)
Earth Science Research     Open Access   (Followers: 7)
Earth Surface Dynamics (ESurf)     Open Access   (Followers: 5)
Earth Surface Processes and Landforms     Hybrid Journal   (Followers: 19)
Earth System Dynamics     Open Access   (Followers: 9)
Earth System Dynamics Discussions     Open Access   (Followers: 6)
Earth's Future     Open Access   (Followers: 1)
Earth, Planets and Space     Open Access   (Followers: 71)
Earthquake Engineering and Engineering Vibration     Hybrid Journal   (Followers: 9)
Earthquake Science     Hybrid Journal   (Followers: 11)
Earthquake Spectra     Full-text available via subscription   (Followers: 18)
Ecohydrology     Hybrid Journal   (Followers: 11)
Ecological Questions     Open Access   (Followers: 7)
Electromagnetics     Hybrid Journal   (Followers: 5)
Energy Efficiency     Hybrid Journal   (Followers: 11)
Energy Exploration & Exploitation     Hybrid Journal   (Followers: 4)
Environmental Earth Sciences     Hybrid Journal   (Followers: 27)
Environmental Geology     Hybrid Journal   (Followers: 20)
Environmental Geosciences     Full-text available via subscription   (Followers: 5)
Environmental Geotechnics     Hybrid Journal   (Followers: 5)
Erwerbs-Obstbau     Hybrid Journal  
Estuaries and Coasts     Hybrid Journal   (Followers: 17)
Estuarine, Coastal and Shelf Science     Hybrid Journal   (Followers: 33)
Estudios Geográficos     Open Access  
European Journal of Mineralogy     Full-text available via subscription   (Followers: 14)
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: 3)
Frontiers of Earth Science     Hybrid Journal   (Followers: 8)
Fundamental and Applied Limnology / Archiv für Hydrobiologie     Full-text available via subscription   (Followers: 4)
GEM - International Journal on Geomathematics     Hybrid Journal   (Followers: 1)
Geo-Marine Letters     Hybrid Journal   (Followers: 7)
Geoacta     Open Access   (Followers: 4)
Geobiology     Hybrid Journal   (Followers: 8)
Geocarto International     Hybrid Journal   (Followers: 22)
Geochemical Perspectives     Hybrid Journal   (Followers: 2)
Geochemistry : Exploration, Environment, Analysis     Hybrid Journal   (Followers: 8)
Geochemistry, Geophysics, Geosystems     Full-text available via subscription   (Followers: 30)
Geochimica et Cosmochimica Acta     Hybrid Journal   (Followers: 48)
Geochronometria     Hybrid Journal   (Followers: 3)
Geoderma Regional : The International Journal for Regional Soil Research     Full-text available via subscription   (Followers: 4)
Geodinamica Acta     Open Access   (Followers: 3)
Geodynamics & Tectonophysics     Open Access   (Followers: 2)
Geoenvironmental Disasters     Open Access   (Followers: 3)
Geofluids     Open Access   (Followers: 4)
Geoforum     Hybrid Journal   (Followers: 23)
Géographie physique et Quaternaire     Full-text available via subscription   (Followers: 1)
Geography and Natural Resources     Hybrid Journal   (Followers: 7)
Geoheritage     Hybrid Journal   (Followers: 1)
Geoinformatica Polonica : The Journal of Polish Academy of Arts and Sciences     Open Access  
Geoinformatics & Geostatistics     Hybrid Journal   (Followers: 9)
Geological Journal     Hybrid Journal   (Followers: 14)
Geology Today     Hybrid Journal   (Followers: 27)
Geology, Geophysics and Environment     Open Access   (Followers: 1)
Geomagnetism and Aeronomy     Hybrid Journal   (Followers: 3)
Geomatics, Natural Hazards and Risk     Hybrid Journal   (Followers: 9)
Geomechanics for Energy and the Environment     Full-text available via subscription   (Followers: 1)
GEOmedia     Open Access   (Followers: 1)
Geomorphology     Hybrid Journal   (Followers: 27)
Geophysical & Astrophysical Fluid Dynamics     Hybrid Journal   (Followers: 2)
Geophysical Journal International     Hybrid Journal   (Followers: 34)
Geophysical Prospecting     Hybrid Journal   (Followers: 7)
Geophysics     Full-text available via subscription   (Followers: 19)
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: 10)
Geoscience Letters     Open Access   (Followers: 1)
Geoscience Records     Open Access  
Geosciences     Open Access   (Followers: 2)
Geosciences Journal     Hybrid Journal   (Followers: 11)
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: 5)
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: 19)
Global Biogeochemical Cycles     Full-text available via subscription   (Followers: 15)
Gondwana Research     Hybrid Journal   (Followers: 9)
GPS Solutions     Hybrid Journal   (Followers: 17)
Grassland Science     Hybrid Journal  
Ground Water     Hybrid Journal   (Followers: 34)
Ground Water Monitoring & Remediation     Hybrid Journal   (Followers: 19)
Groundwater for Sustainable Development     Full-text available via subscription   (Followers: 3)
Helgoland Marine Research     Open Access   (Followers: 3)
History of Geo- and Space Sciences     Open Access   (Followers: 4)
Hydrobiologia     Hybrid Journal   (Followers: 18)
Hydrogeology Journal     Hybrid Journal   (Followers: 21)
Hydrological Processes     Hybrid Journal   (Followers: 28)
Hydrology and Earth System Sciences     Open Access   (Followers: 28)
ICES Journal of Marine Science: Journal du Conseil     Hybrid Journal   (Followers: 53)
IEEE Journal of Oceanic Engineering     Hybrid Journal   (Followers: 13)
Indian Geotechnical Journal     Hybrid Journal   (Followers: 4)
Indonesian Journal on Geoscience     Open Access   (Followers: 2)
Interdisciplinary Environmental Review     Hybrid Journal   (Followers: 3)
International Geology Review     Hybrid Journal   (Followers: 16)
International Journal of Advanced Geosciences     Open Access  
International Journal of Advanced Remote Sensing and GIS     Open Access   (Followers: 36)
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: 28)
International Journal of Applied Earth Observation and Geoinformation     Hybrid Journal   (Followers: 36)
International Journal of Coal Geology     Hybrid Journal   (Followers: 2)
International Journal of Disaster Risk Reduction     Hybrid Journal   (Followers: 16)
International Journal of Earth Sciences     Hybrid Journal   (Followers: 38)
International Journal of Earthquake and Impact Engineering     Hybrid Journal   (Followers: 2)
International Journal of Geo-Engineering     Open Access   (Followers: 3)

        1 2 3 | Last

Journal Cover Applied Clay Science
  [SJR: 0.826]   [H-I: 83]   [5 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0169-1317
   Published by Elsevier Homepage  [3043 journals]
  • Synthesis of dimethyl carbonate by transesterification reaction using
           ceria-zinc oxide catalysts prepared with different chelating agents
    • Authors: Praveen Kumar; Vimal Chandra Srivastava; Roger Gläser; Patrick With; Indra Mani Mishra
      Pages: 13 - 21
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Praveen Kumar, Vimal Chandra Srivastava, Indra Mani Mishra
      This paper reports the use of novel ceria-zinc catalyst for the preparation of dimethyl carbonate (DMC) using transesterification of PC with methanol. Ceria-zinc oxide catalysts were prepared by a sol-gel method using citric acid, oxalic acid and tartaric acid as chelating agents (named as CZC, CZO, and CZT, respectively). The synthesized catalysts were characterized by XRD, N2 adsorption-desorption, FTIR, SEM-EDX, ICP-OES, and CO2-temperature program desorption. Experimental results revealed that the catalytic performance of CZC was closely related to the surface area and presence of basic sites in the catalyst. CZC showed high selectivity and PC conversion. Effects of operating parameters such as methanol/PC molar ratio, catalyst dose, reaction temperature, reaction time were studied. The reusability of CZC as a catalyst for DMC selectivity and PC conversion with turn-over frequency (TOF) was also studied.
      Graphical abstract image

      PubDate: 2017-10-11T09:14:33Z
      DOI: 10.1016/j.powtec.2016.12.016
      Issue No: Vol. 309 (2017)
       
  • Effects of calcination temperature and the addition of ZnO on coal waste
           activation: A mineralogical and morphological evolution
    • Authors: Raquel Vigil de la Villa; Rosario García; Sagrario Martínez-Ramírez; Moisés Frías
      Pages: 1 - 9
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Raquel Vigil de la Villa, Rosario García, Sagrario Martínez-Ramírez, Moisés Frías
      Eco-efficient cements based on industrial wastes constitute a priority line of research for the sustainability of the cement sector, in response to the challenges of the circular economy at a European level. Eco-innovation and investigation of new alternative sources of primary materials from waste arise as potential actions directed at the achievement of greater efficiency in the use of resources. From among the broad range of industrial wastes, those that contain kaolinite (K) and phyllosilicates are ideal as active additions in the manufacture of cements, having previously undergone a process of thermal activation. Earlier works have indicated that the chemical reactivity of natural K (untreated kaolin) may be increased through the addition of ZnO as a chemical agent. In this study, the effect of ZnO as a chemical agent is for the first time studied, when added to coal waste in proportions of 0.5, 1.0, 1.5 and 3.0% by weight, prior to the thermal activation process of the waste that is calcinated at 550°, 600°, and 650°C for 2h. The mineralogy and the pozzolanic activity of the activated products are considered, and their influence on the evolution of the hydrated phases at 1, 7, and 28days of reaction in the pozzolan/lime system. Subsequently, the results are compared with those obtained from pure natural kaolinite activated at 600°C/2h, with ZnO addition and without chemical agent ZnO, with an added quantity of 1.0% in weight. The results showed important variations when the chemical activator (ZnO) was used for the natural kaolinite (NK) and the industrial waste. The chemical activator favors the disaggregation of the phyllosilicates from the aggregates, strengthening the pozzolanic reaction in the natural/lime kaolinite system. However, the activator in the coal waste/lime system, in addition to favoring the disaggregation of the aggregate, leaves epitaxial deposits on the surface and on the edges of the materials, saturating the substrate surface loading, with an inhibitory effect on the pozzolanic reaction. The abundance of metakaolinite (MK) and the partial dehydroxylation of the mica with its subsequent reorganization, explains the appearance of these minerals as one of the products of the reaction. With SEM/EDX, the existence of CSH gels of a spongy appearance may be observed following thermal activation of the coal waste; while if the activation is done under the combined effect of temperature and the addition of 1.0% ZnO, then the chemical activator favors the formation of long fibers and the appearance of gels, with compositions similar to LDH and calcium aluminates.

      PubDate: 2017-09-08T03:01:58Z
      DOI: 10.1016/j.clay.2017.08.031
      Issue No: Vol. 150 (2017)
       
  • The Maastrichtian-Danian Dakhla Formation, Eastern Desert, Egypt:
           Utilization in manufacturing lightweight aggregates
    • Authors: Tarek I. Anan; Ahmed G. Abd El-Wahed
      Pages: 10 - 15
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Tarek I. Anan, Ahmed G. Abd El-Wahed
      The Dakhla Formation at Um El Hueitat area, south of Safaga City, Eastern Desert, Egypt is composed mainly of shale with some marl, limestone and phosphate intercalations. Suitability of the technological sample representing smectitic-rich clay deposits of the Dakhla Formation for lightweight product was studied. The mineralogical and chemical compositions of the technological sample indicate that it is suitable for manufacturing lightweight bloated clay aggregate. This was done by processing its plastic pellets through firing to 1000–1300°C.

      PubDate: 2017-09-14T03:06:36Z
      DOI: 10.1016/j.clay.2017.08.027
      Issue No: Vol. 150 (2017)
       
  • Preparation and characterization of sodium lauroyl sarcosinate adsorbed on
           cetylpyridinium-montmorillonite as a possible antibacterial agent
    • Authors: Saadet Yapar; Mustafa Ateş; Günseli Özdemir
      Pages: 16 - 22
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Saadet Yapar, Mustafa Ateş, Günseli Özdemir
      An organo-montmorillonite was synthesized to generate a two-level antibacterial agent. The material (Mt-CP-SR) was prepared through the adsorption of sodium lauroyl sarcosinate (SR) on montmorillonite modified with cetylpyridinium (Mt-CP) and its structure was characterized by conducting ATR-FTIR, XRD, and SEM analyses. The results of the ATR-FTIR analyses indicated that SR on the surface could be detected when its amount exceeded the CEC of the Mt. The XRD analyses revealed that the adsorption of CP and SR causes the separation of Mt layers into smaller stacks. The adsorption and desorption study of SR onto and from 0.7 CEC Mt-CP were investigated to determine the amount of SR adsorbed at varying initial SR concentrations and the amount of SR released when diluted with water. Around 140mg of SR could be loaded on one gram of the Mt intercalated with 170mg of CP. The results indicated that desorption of SR from the surface is gradual and SR and CP have strong interactions on the montmorillonite (Mt) surface. The antibacterial activity of the material was tested against E. coli, S. aureus, and P. aeruginosa. Additionally, the SR solutions and CP+SR solutions in equimolar ratios were subjected to antibacterial tests for comparison purposes. SR proved to be effective against all three bacteria and the MIC values were found as 75mg/mL for E. coli, 37.5mg/mL for S. aureus, and 300mg/mL for P. aeruginosa. The MBC was 300mg/mL for E. coli and S. aureus. The solutions of CP+SR mixtures were ineffective against P. aeruginosa, whereas, they were effective against S. aureus. The prepared Mt-CP-SR samples were found to be effective against S. aureus and E. coli. These results indicate that the material could be used in antibacterial liquid soaps, in toothpaste formulations, personal care products, and topical applications against acne, and wounds without any negative contribution to the physico-chemical and detergency properties of the materials.

      PubDate: 2017-09-14T03:06:36Z
      DOI: 10.1016/j.clay.2017.08.025
      Issue No: Vol. 150 (2017)
       
  • Evaluation of organic modification of montmorillonite with ionic and
           nonionic surfactants
    • Authors: Jefferson Lopes Alves; Paulo de Tarso Vieira e Rosa; Ana Rita Morales
      Pages: 23 - 33
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Jefferson Lopes Alves, Paulo de Tarso Vieira e Rosa, Ana Rita Morales
      This work aims at evaluating the organophilization of montmorillonite with two different types of surfactants: one ionic, containing C16-C18 di(alkyl ester) dimethyl ammonium chloride (EA) and one nonionic, containing ethoxylated tallow amine (ETA). Aqueous dispersion and semi-solid routes were compared in terms of functionalization efficiency by statistical analysis, and supercritical CO2 was performed as a complementary and comparative method. Besides, the effect of the washing process after functionalization was evaluated. X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) and contact angle were used to evaluate the intercalation of surfactants into montmorillonite and process yield. The d001-value was improved by both surfactants intercalation, and the conformations of the species inside the clay minerals were suggested. The final arrangement of the organic species into Mt was modified as a function of the concentration of surfactant added, and by the washing steps. Most process parameters evaluated showed significant effects on d001-value and process yield. The semi-solid method was confirmed as a good alternative route due to its efficiency and it could be an environmentally friendly option to be used. ETA-modified montmorillonites showed similar d001-values (around 4.0nm) and higher thermal stability than EA-modified montmorillonite.

      PubDate: 2017-09-14T03:06:36Z
      DOI: 10.1016/j.clay.2017.09.001
      Issue No: Vol. 150 (2017)
       
  • Synthesis and characterization of 12-tungstophosphoric acid intercalated
           layered double hydroxides and their application as esterification
           catalysts for deacidification of crude oil
    • Authors: Yan Wu; Xinyue Liu; Yanqing Lei; Yue Qiu; Menglu Wang; Hao Wang
      Pages: 34 - 41
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Yan Wu, Xinyue Liu, Yanqing Lei, Yue Qiu, Menglu Wang, Hao Wang
      12-tungstophosphoric acid (H3PW12O40, HPW) intercalated layered double hydroxides (LDH) (M2+/Al3+ =2, M2+ =Mg2+, Zn2+, Ni2+) were prepared by an ion-exchange method. The as-prepared LDH show a strong reflection around 8.4° corresponding to a basal spacing of 1.05nm, which is considered as heteropolyacid salts or polytungstate intercalated LDH in almost all literature. Further systemic experiments and characterizations demonstrated that such reflection can be attributed to the intercalation of HPW, in which HPW may graft with the vacancies in the layer and orient in the interlayer with the C2 axis perpendicular to the layers. HPW intercalated LDH show higher catalytic activity than nitrate LDH for the esterification between ethylene glycol and naphthenic acids in crude oil. It is found that the total amount of acidic sites dominates the esterification activity. Due to the immobilized HPW active sites and the enlarged interlayer space, HPW intercalated LDH may act as an interlayer catalytic reactor to improve the esterification activity.
      Graphical abstract image

      PubDate: 2017-09-14T03:06:36Z
      DOI: 10.1016/j.clay.2017.09.007
      Issue No: Vol. 150 (2017)
       
  • A two-step technique for tensile strength of montmorillonite/polymer
           nanocomposites assuming filler morphology and interphase properties
    • Authors: Yasser Zare; Kyong Yop Rhee
      Pages: 42 - 46
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Yasser Zare, Kyong Yop Rhee
      This paper presents a two-step methodology for prediction of tensile strength in montmorillonite/polymer nanocomposites (MPN) assuming the effects of montmorillonite morphology (intercalation/exfoliation) and interphase properties. The suggested technique is evaluated by the experimental data of tensile strength in some samples. A good agreement is shown between experimental measurements and predictions, which can determine the intercalation/exfoliation level and interphase properties. A high aspect ratio of Mt platelets increases the interfacial interaction and mechanical involvement between polymer chains and nanoparticles causing high strengthening effect. Moreover, high concentration of well-exfoliated Mt as well as thick and strong interphase produces desirable tensile strength in MPN.

      PubDate: 2017-09-20T03:10:43Z
      DOI: 10.1016/j.clay.2017.08.026
      Issue No: Vol. 150 (2017)
       
  • Sustainable catalytic properties of silver nanoparticles supported
           montmorillonite for highly efficient recyclable reduction of methylene
           blue
    • Authors: Ning Wang; Yunxia Hu; Zongren Zhang
      Pages: 47 - 55
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Ning Wang, Yunxia Hu, Zongren Zhang
      Water contamination by organic dyes has become a serious environmental pollution. Here, a facile, green and cost-effective synthesis approach was developed to in situ grow silver nanoparticles (Ag NPs) on the eco-friendly and low cost natural material montmorillonite (Mt) through dopamine chemistry. The loading amount of silver on the montmorillonite reached 20 mass %. The Ag NPs supported montmorillonite (Ag NPs@Mt) exhibited excellent catalytic performances to reduce a model organic dye methylene blue in the presence of NaBH4 with catalytic efficiency higher than 98% and apparent reduction rate constant k app higher than 1.70min−1. More importantly, the Ag NPs@Mt was proven to show excellent recyclability for at least 20cycles and long-term stability for one month soaking in water. This low-cost and recyclable Ag NPs@Mt shows great potential in large scale application to treat dye containing wastewater.
      Graphical abstract image

      PubDate: 2017-09-20T03:10:43Z
      DOI: 10.1016/j.clay.2017.08.024
      Issue No: Vol. 150 (2017)
       
  • Clayey wastes-based lightweight aggregates: Heating transformations and
           physical/mechanical properties
    • Authors: M. Loutou; M. Hajjaji
      Pages: 56 - 62
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): M. Loutou, M. Hajjaji
      Heating transformations of pellets of selected binary blends of raw clay, cement kiln dust and phosphate sludge were investigated by using different techniques (XRD, DSC, FT-IR and SEM), and their main technical properties were followed as a function of temperature. It was found that calc-aluminosilicate phase (gehlenite/labradorite) neoformed at T<900°C from the breakdowns of kaolinite and chlorite, and lime of decomposed carbonates. Moreover, fluorapatite (a component of phosphate waste-containing blends) gave rise to calcium phosphate (Ca3(PO4)2) and melt, which played a chief role in the sintering process of the pellets. The melt abundance induced the dissolution of mullite, which was the major constituent of the cement kiln dust. The results also showed that the compressive strength of the pellets increased and water absorption together with density (except for the phosphate waste-clay blend) decreased with increasing temperature. These evolutions were discussed in relation to the microstructure changes. The suitability of the blends in LWAs manufacturing was evaluated basing on the magnitudes of the measured properties.

      PubDate: 2017-09-26T03:14:50Z
      DOI: 10.1016/j.clay.2017.09.011
      Issue No: Vol. 150 (2017)
       
  • An insight into the carbonation of calcined clayey dolomite and its
           performance to remove Cd (II)
    • Authors: Hanlin Wang; Haibo Liu; Jingjing Xie; Hongwei Li; Tianhu Chen; Peng Chen; Dong Chen
      Pages: 63 - 70
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Hanlin Wang, Haibo Liu, Jingjing Xie, Hongwei Li, Tianhu Chen, Peng Chen, Dong Chen
      Highly active porous materials composed of calcite and periclase nanoparticles was prepared by the carbonation of thermally treated clayey dolomite, having great potential for heavy metal pollution control in water and soil. The effect of coexisting steam and hydration pretreatment on the carbonation of calcined clayey dolomite (CCD) was studied by fixed bed reactor and mass spectrum on-line monitoring. The phase, surface chemistry, thermal activity, pore type and morphology of CCD after carbonation were characterized by XRD, FTIR, TG, N2 adsorption–desorption isotherm and TEM. The results showed that the initial and complete carbonation temperatures of CCD under anhydrous conditions were 400°C and 600°C, respectively. The presence of 10% steam decreased the initial and complete temperatures by 100°C, respectively. The complete carbonation temperature was reduced to 400°C when the CCD was hydrated and dried before carbonation. However, the hydrated CCD which not dried can be directly carbonated at room temperature, and the carbonation rate (newborn calcite mass fraction) firstly decreased, then increased with the increase of temperature in the range of 50–500°C. According to the TG results, the decomposition temperatures of the newborn calcite produced by 650°C carbonation of CCD decreased by 50°C compared with that of common calcite. The research on cadmium removal showed that the removal efficiency of 50mg/L Cd (II) by 650°C carbonation of CCD rapidly reached 99.8% within 1h, while the equilibrium pH decreased by 2units compared with CCD without carbonation. The carbonation of CCD formed nano calcite of lower decomposition temperature and also hampered the hydroxylation to decrease the effluent pH. The experimental results displayed carbonation can control the physicochemical property of the CCD, and the carbonated product is potential to be used for the removal of Cd (II) from aqueous solution.

      PubDate: 2017-09-26T03:14:50Z
      DOI: 10.1016/j.clay.2017.09.012
      Issue No: Vol. 150 (2017)
       
  • Laser beam backscattering as a new tool to study the effect of inhibitors
           on shale particles-water interactions: A real-time analysis
    • Authors: Vinicius Kartnaller; Conny Cerai Ferreira; Santiago Villabona-Estupiñán; Elizabeth Roditi Lachter; Jorge de Almeida Rodrigues Junior; Regina Sandra Veiga Nascimento; João Cajaiba
      Pages: 89 - 97
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Vinicius Kartnaller, Conny Cerai Ferreira, Santiago Villabona-Estupiñán, Elizabeth Roditi Lachter, Jorge de Almeida Rodrigues Junior, Regina Sandra Veiga Nascimento, João Cajaiba
      The interaction between clay-rich shales formations and water is one of the most relevant factors for well instability in drilling operations, representing a significant challenge for the oil and gas industry. To minimize the problems related to water sensitivity, chemical additives or inhibitors are incorporated into water-based drilling fluids, acting over the water-shale interactions and maintaining the integrity of the sedimentary rock. In this work a novel approach is proposed to gain new information about the dynamics of the inhibitory process and to evaluate the shale inhibition efficiency of different chemical additives using a laser beam backscattering technique. This technique is based on the analysis of laser backscattering profiles promoted by dispersed particles in a suspension, which results in a particle chord length distribution (CLD). The technique was adequate for monitoring the consequences of the interactions between water and shales, differentiating its reactivities by monitoring the effect of different inhibitors on each system's CLD over time. Two cationic inhibitors (KCl and PDADMAC, a cationic polymer) were tested, and the obtained results showed that the inhibition phenomenon is more than the inhibitor itself, and it depends on the shale structure and the capability of the inhibitor to interact with its clay stacks. A methodology was also developed to calculate an inhibition efficiency score (IES), in which the technique's real-time factor enables it to estimate how much better an inhibitor is when compared to others over time. Among the evaluated systems, the inhibitor that achieved the biggest efficiency for shale was KCl, resulting in 69%.
      Graphical abstract image

      PubDate: 2017-09-26T03:14:50Z
      DOI: 10.1016/j.clay.2017.09.010
      Issue No: Vol. 150 (2017)
       
  • Toxicological assessment of two silane-modified clay minerals with
           potential use as food contact materials in human hepatoma cells and
           Salmonella typhimurium strains
    • Authors: Sara Maisanaba; María Llana-Ruíz-Cabello; Silvia Pichardo; Ana Isabel Prieto; Ana M. Cameán; María Jordá-Beneyto; Ángeles Jos
      Pages: 98 - 105
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Sara Maisanaba, María Llana-Ruíz-Cabello, Silvia Pichardo, Ana Isabel Prieto, Ana M. Cameán, María Jordá-Beneyto, Ángeles Jos
      Reinforced technological properties can be achieved by adding small amounts of organo-modified clay minerals into traditional polymeric matrices. The result is a final product with improved characteristics destined to several applications, among them, food packaging. However, it is mandatory to evaluate the toxicity of novel food contact materials, as well as all new substances destined to this purpose. The present work shows for the first time in a human target cell line from hepatic origin (HepG2), and in Salmonella typhimurium, a prokaryotic system, the in vitro toxicological evaluation of Clay3 and Clay4, two silane-modified montmorillonites intended to be incorporated into food containers. Cytotoxic effects were evaluated (0 to 250μg/mL) after 24 and 48h of exposure and only Clay4 showed toxic effects. Once the mean effective concentration was calculated, different mechanistic biomarkers were investigated for Clay4: cell death, reactive oxygen species (ROS) production, glutathione content, mutagenicity, and standard and oxidative genotoxicity. Only a significant ROS production after both times of exposure, as well as a significant oxidative DNA damage after the longer time assayed were obtained with Clay4. Between both silane-modified clay minerals studied Clay3 is the better candidate to develop new reinforced packaging materials in base to its good toxicological profile.

      PubDate: 2017-09-26T03:14:50Z
      DOI: 10.1016/j.clay.2017.09.018
      Issue No: Vol. 150 (2017)
       
  • CTAB modified large surface area nanoporous geopolymer with high
           adsorption capacity for copper ion removal
    • Authors: Aditi Singhal; Bhanu P. Gangwar; J.M. Gayathry
      Pages: 106 - 114
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Aditi Singhal, Bhanu P. Gangwar, J.M. Gayathry
      Nanoporous geopolymer was synthesized with and without using Cetyl trimethylammonium bromide (CTAB) by condensing the mixture of metakaolin and alkali solution at a fixed ratio at room temperature. The surface area of CTAB-geopolymer was found to be more (216m2/g) as compared to without CTAB added geopolymer (137m2/g). The experimental results verified that the geopolymer could adsorb copper ions completely at lower concentrations and partially at higher concentrations. Pseudo second order model fits well at all the concentration from 55 to 1700ppm as the values of the correlation coefficient lies between 0.96 and 0.99. Intraparticle diffusion model at the concentration 55ppm explains that there is only boundary layer diffusion (instantaneous) and after this step, all the Cu ions are exchanged by the nanoporous geopolymer. At 120ppm, intraparticle diffusion model shows multilinearity. Different adsorption models - Langmuir, Freundlich and Tempkin were also tested to evaluate the most appropriate model and it was found that adsorption follows Langmuir model. The adsorption capacity and pseudo second order rate constant is estimated to be 1.65meq/g which is significantly higher than the fly ash based nonporous geopolymer.

      PubDate: 2017-09-26T03:14:50Z
      DOI: 10.1016/j.clay.2017.09.013
      Issue No: Vol. 150 (2017)
       
  • Insights into the formation mechanism of imogolite from a full-range
           observation of its sol-gel growth
    • Authors: Peixin Du; Peng Yuan; Antoine Thill; Faïza Annabi-Bergaya; Dong Liu; Shun Wang
      Pages: 115 - 124
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Peixin Du, Peng Yuan, Antoine Thill, Faïza Annabi-Bergaya, Dong Liu, Shun Wang
      Imogolite (Imo) was prepared via a sol-gel method. The time-dependent changes in its morphology, structure and texture during the whole synthesis process (from amorphous precursors to the final products through nanoscale intermediates) were monitored by atomic force microscopy (AFM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) and N2 physisorption. The results showed that a shape transition from a spherical open imogolite local structure (ImoLS) to a tubular open ImoLS occurred in the process of proto-imogolite (proto-Imo) formation. Based on the overall structure of the obtained solid products and the occurring main reactions, Imo synthesis process was described in five steps: i) formation of amorphous precursors by hydrolysis and condensation of Al and Si; ii) formation of proto-Imo with an open ImoLS at the expense of the amorphous precursors; iii) open ImoLS dominates; it grows and assembles into the first closed ImoLS (tubes and spheres); iv) closed ImoLS dominates and continues to form (mainly tubes) at the expense of open ImoLS; and v) no more open ImoLS; further growth of already-formed Imo via oriented aggregation. These findings provide new insights into the formation mechanism and structure of proto-Imo and Imo, which helps to clarify the Imo synthesis procedure.

      PubDate: 2017-09-26T03:14:50Z
      DOI: 10.1016/j.clay.2017.09.021
      Issue No: Vol. 150 (2017)
       
  • Characterisation and identification of local kaolin clay from Ghana: A
           potential material for electroporcelain insulator fabrication
    • Authors: Abu Yaya; Elvis K. Tiburu; Mary E. Vickers; Johnson K. Efavi; Boateng Onwona-Agyeman; Kevin M. Knowles
      Pages: 125 - 130
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Abu Yaya, Elvis K. Tiburu, Mary E. Vickers, Johnson K. Efavi, Boateng Onwona-Agyeman, Kevin M. Knowles
      The aim of this work was to evaluate two kaolin clays from the southern part of Ghana, Assin-Fosu and Kumasi clays, as source clays for the fabrication of electroporcelain insulators. X-ray diffraction, differential thermal analysis, thermogravimetric analysis, chemical analyses and scanning electron microscopy observations showed the fired clay minerals have broadly similar characteristics, but with significant differences in their chemical composition. The alumina contents were determined to be 35±2wt% and 22±2wt% respectively for the two kaolins and the silica contents 49±3wt% and 58±3wt% respectively. It is concluded that Assin-Fosu kaolin is a reliable local source material for electroporcelain fabrication, while Kumasi kaolin is more suitable for making wall and floor tiles.

      PubDate: 2017-09-26T03:14:50Z
      DOI: 10.1016/j.clay.2017.09.015
      Issue No: Vol. 150 (2017)
       
  • Physical and mechanical properties improvement of a porous clay ceramic
    • Authors: Hiba Zouaoui; Jamel Bouaziz
      Pages: 131 - 137
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Hiba Zouaoui, Jamel Bouaziz
      This work deals with the chemical, physical, thermal and mechanical analyses of porous clay and non-plastic clays mixtures from Tunisia. Five mixtures which are M1 (70 mass% clay +30 mass% waste brick), M2 (70 mass% clay +15 mass% waste brick +15 mass% sand), M3 (70 mass% clay +30 mass% sand), M4 (70 mass% clay +30 mass% chamotte) and M5 (70 mass% clay +15 mass% chamotte +15 mass% sand) were sintered between 900 and 1100°C and were evaluated for their possible ceramic applications. Thermal analysis (DTA/TG), dilatometry, X-ray diffraction (XRD), scanning electron microscopy (SEM) and physical-mechanical analyses (tensile strength, water absorption and bulk density) were used to assess the thermal behavior, phase evolution and microstructure of the fired mixtures. The formations of both the anorthite phase and the vitreous phase have improved the required ceramic product performance. M1 has the highest values of tensile strength and bulk density at 1100°C. According to the European Norm EN 14411, all the mixtures belong to the BIII group which are suitable for the production of earthenware and unglazed stoneware.

      PubDate: 2017-10-03T17:56:04Z
      DOI: 10.1016/j.clay.2017.09.002
      Issue No: Vol. 150 (2017)
       
  • Functionalization of halloysite nanotubes for the preparation of
           carboxymethyl cellulose-based nanocomposite films
    • Authors: Long-Feng Wang; Jong-Whan Rhim
      Pages: 138 - 146
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Long-Feng Wang, Jong-Whan Rhim
      Halloysite nanotubes (Hal) were treated with acid to prepare uniformly charged acid treated Hal (Hal-A). After acid treatment, the surface charge (zeta potential) of Hal changed from +0.08mV to −32.65mV. Functionalized Hal-A were prepared through adsorbing metal ions by immersing the Hal-A into saturated solutions of three different metal salts, silver nitrate, zinc nitrate, and copper acetate. The number of metal ions attached to the Hal-A and their functionality were dependent on the type of metal ions. The functionalized Hal-A exhibited strong antimicrobial activity against food-borne pathogenic bacteria, L. monocytogenes and E. coli. The CMC-based film showed a significant increase in mechanical, water vapor barrier, and thermal stability properties after forming a composite with Hal. In particular, CMC-based films incorporated with the functionalized Hal-A showed strong antimicrobial activity against both L. monocytogenes and E. coli.

      PubDate: 2017-10-03T17:56:04Z
      DOI: 10.1016/j.clay.2017.09.023
      Issue No: Vol. 150 (2017)
       
  • Thermoexfoliated and hydrophobized vermiculites for oleic acid removal
    • Authors: Celia Marcos; Roberto Menéndez; Irene Rodríguez
      Pages: 147 - 152
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Celia Marcos, Roberto Menéndez, Irene Rodríguez
      The aim of the present study was to investigate the removal efficiency of oleic acid from aqueous solutions by thermally expanded and hydrophobized vermiculites. The expansion of the samples was carried out in a furnace at 1000°C for 2min. The hydrophobization using polymethyl-hydro-siloxane as hydrophobing derivatizing reagent was performed by immersion and hydrophobizing atmosphere methods. The investigation was started with two vermiculites from Brazil, the Goiás and Piauí states, respectively. After some previous tests the Goiás vermiculite was selected to investigate five effects: 1) Adsorption at different pH. 2) Adsorption at different concentrations of hydrophobizing reactive and different weights of vermiculite. 3) Adsorbent mass. 4) Influence of the number of stages of adsorption. 5) Influence of salinity. Oleic acid uptake was quantitatively evaluated using the Langmuir, Freundlich and Dubinin–Kaganer–Radushkevich (DKR) models. In addition, the adsorption equilibrium was described well by the DKR isotherm model, indicative of a cooperative process. The maximum adsorption capacity obtained with DKR model was of 1.29mol/g of oleic acid. The hydrophobization Goiás vermiculite and the adsorption of oleic acid were verified using infrared spectroscopy. The findings of this study showed that this thermally expanded and hydrophobized vermiculite: 1) was very suitable for the recovery of oleic acid in water; 2) the adsorption increased with the increase of the salinity of the aqueous medium; 3) it was possible to reuse vermiculite unsaturated to recover more oleic acid.

      PubDate: 2017-10-03T17:56:04Z
      DOI: 10.1016/j.clay.2017.09.026
      Issue No: Vol. 150 (2017)
       
  • An experimental study on oven-drying methods for laboratory determination
           of water content of a calcium-rich bentonite
    • Authors: Lin Zhi Lang; Wei Xiang; Wei Huang; De Shan Cui; Tom Schanz
      Pages: 153 - 162
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Lin Zhi Lang, Wei Xiang, Wei Huang, De Shan Cui, Tom Schanz
      Studies on the dehydration of montmorillonites imply that the standard oven-drying method (drying at 110 ± 5°C) may underestimate the water content of bentonites. This study quantifies, identifies, explains, and removes the residual water in a calcium-rich bentonite dried using the standard oven-drying method. A thermogravimetric-differential scanning calorimetry (TG-DSC) test was performed to determine the true water content. According to this test, the effect of the drying time and temperature on the amount of residual water in the bentonite was examined, including the oven-drying and vacuum-drying methods. To identify and explain the residual water, specific surface area (SSA) derived from the nitrogen adsorption isotherm and dehydration reaction characterised by TG-DSC curves of samples with a residual water content of 0–13.38% were obtained. The experimental results demonstrate that the standard oven-drying method underestimates the water content of calcium-rich bentonites by 2.1–3.1%. The 2.1–3.1% of residual water includes both interlayer water and adsorbed water on the external surface. The 2.1–3.1% of residual water is the water forming the inner shell around Ca2+ cations in the interlayer and on the external surface of montmorillonite particles. It is impractical to distinguish between the adsorbed water and interlayer water only based on the dehydration reaction characterised by TG-DSC curves. Drying profiles of 12h of drying at 200°C in an oven and 1h of drying at 150–200°C under vacuum are sufficient for removing the adsorbed and interlayer waters from the bentonite.

      PubDate: 2017-10-03T17:56:04Z
      DOI: 10.1016/j.clay.2017.09.022
      Issue No: Vol. 150 (2017)
       
  • Heating-freezing effects on the orientation of kaolin clay particles
    • Authors: Karam A. Jaradat; Zubin Darbari; Mohamed Elbakhshwan; Sherif L. Abdelaziz; Simerjeet K. Gill; Eric Dooryhee; Lynne E. Ecker
      Pages: 163 - 174
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Karam A. Jaradat, Zubin Darbari, Mohamed Elbakhshwan, Sherif L. Abdelaziz, Simerjeet K. Gill, Eric Dooryhee, Lynne E. Ecker
      The effects of temperature changes on the particle orientation of a consolidated kaolin are studied using XRD experiments. Two sets of equipment were utilized in this study: a benchtop equipment, and a synchrotron beamline at the National Synchrotron Light Source II (NSLS-II) at Brookhaven National Laboratory. The kaolin specimens tested in the benchtop XRD were subjected to elevated and freezing temperatures ex-situ, while those used for the NSLS-II experiment were exposed to the temperature changes in-situ. The temperatures considered in this study range from freezing (−10°C) to elevated temperature below boiling (90°C). The thermally-induced reorientation of clay mineral particles is highly dependent on the relative orientation of the clay mineral particles with respect to the applied thermal gradient. For example, kaolin samples with kaolinite particles oriented perpendicular to the thermal gradient, and to the expected thermally-induced pore water flow, experience much higher particles reorientations compared to samples with particles initially oriented parallel to the thermal gradient. Moreover, freezing kaolin preserved its microstructure as ice crystals form.

      PubDate: 2017-10-03T17:56:04Z
      DOI: 10.1016/j.clay.2017.09.028
      Issue No: Vol. 150 (2017)
       
  • Physico-mechanical and gas permeability characteristics of kaolin based
           ceramic membranes prepared with a new pore-forming agent
    • Authors: David O. Obada; David Dodoo-Arhin; Muhammad Dauda; Fatai O. Anafi; Abdulkarim S. Ahmed; Olusegun A. Ajayi
      Pages: 175 - 183
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): David O. Obada, David Dodoo-Arhin, Muhammad Dauda, Fatai O. Anafi, Abdulkarim S. Ahmed, Olusegun A. Ajayi
      The objective of this study was to prepare low-cost macroporous ceramic membranes using natural kaolin obtained from deposits in Nigeria and Ghana, and powdery high density polyethelene (PHDPE) as porogen agent. The ceramic membranes have been prepared with porogen content wt% between (0 and 20)% by die pressing. Pellets were fired at 1150°C and soaking time of 4h. The raw materials were characterized using TG/DTA, particle size distribution (PSD) and Zeta potential. The membranes cast as circular disks were subjected for characterization studies using XRD and SEM analysis. In a bid to correlate the physico-mechanical properties vis-à-vis pore former content, the effect of the sintering temperature and pore former (PHDPE) content on porosity, density, water absorption and mechanical strength were evaluated. The membrane corrosion resistance was found to be unaltered with experimental conditions. Obtained membranes showed good porosity with maximum at about 62% with a mechanical strength that does not exceed 18MPa. These membranes can be considered as efficient regarding the results shown in the gas permeation tests at different sintering temperatures. A PHDPE percentage of 20% and a sintering temperature of 1150°C were chosen as the optimum for gas permeation based on enlarged pore diameter of sintered membranes.

      PubDate: 2017-10-03T17:56:04Z
      DOI: 10.1016/j.clay.2017.09.014
      Issue No: Vol. 150 (2017)
       
  • Structure and photoluminescence of a new binary Mg/Tb layered double
           hydroxide
    • Authors: Xiaoqing Wang; Yufeng Chen; Huajian Zhou; Kunlei Zhang
      Pages: 184 - 191
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Xiaoqing Wang, Yufeng Chen, Huajian Zhou, Kunlei Zhang
      A series of binary Mg/Tb layered double hydroxides (Mg/Tb-LDH) with different Mg2+/Tb3+ molar ratios of 2.0, 3.0, 4.0, and 5.0 have been synthesized in ammonia water media by hydrothermal method. Various characterizations, including inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray diffraction (XRD), and photoluminescent spectra (PL), etc., were used to study the composition, structure, and photoluminescent property of samples. Results revealed that the molar ratios of Mg2+/Tb3+ present in the samples approximated to that of the initial molar ratios of chemical reagents. All the Mg/Tb-LDH samples have similar hexagonal structure as that of the brucite Mg(OH)2 despite their lattice c values are greatly larger than that of the Mg(OH)2. These Mg/Tb-LDH exhibited good photoluminescence. Moreover, the emissions due to 5D4 → 7FJ (J=5, 6) transitions of Tb3+ gradually enhanced as the Mg2+/Tb3+ molar ratios varied from 5.0, 4.0 to 3.0; then markedly decreased with the Mg2+/Tb3+ molar ratio down to 2.0. The strongest emissions were observable to be at Mg2+/Tb3+ molar ratio of 3.0. This new binary Mg/Tb-LDH may be potential application as luminescent materials.
      Graphical abstract image

      PubDate: 2017-10-03T17:56:04Z
      DOI: 10.1016/j.clay.2017.09.025
      Issue No: Vol. 150 (2017)
       
  • Novel thio-kaolinite nanohybrid materials and their application as heavy
           metal adsorbents in wastewater
    • Authors: Marijke Struijk; Fernando Rocha; Christian Detellier
      Pages: 192 - 201
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Marijke Struijk, Fernando Rocha, Christian Detellier
      A new clay nanohybrid adsorbent material was obtained by grafting the compound 3,6-dithia-1,8-octanediol (HO(CH2)2S(CH2)2S(CH2)2OH) onto the internal aluminol surfaces of both the urea- and dimethylsulfoxide (DMSO) precursors of two kaolinite clay minerals: the Source clay KGa-1b and a Portuguese clay sample collected from the Clays of Taveiro formation. All samples were characterised by X-ray diffraction and solid-state 13C cross-polarisation nuclear magnetic resonance (CP-MAS NMR) spectroscopy. Initial materials and final products were also characterised by thermal gravimetric analysis (TGA) and Fourier-Transform infrared (FTIR) spectroscopy. The results describe nanohybrid materials that are resistant to hydrolysis and exhibit different grafting fashions. The potential application of these materials as a heavy metal adsorbents was tested in ZnCl2 solutions as well as in zinc-spiked raw wastewater. The first assessment of the zinc adsorption capacity of the Source clay KGa-1b was made. Zinc concentrations were analysed concomitant with other metal species by inductively coupled plasma mass spectrometry (ICP-MS), demonstrating variable adsorption capacities of the different clay samples, and a consistently greater zinc removal in the wastewater system compared to simple zinc solutions. Measured concentrations of concomitantly analysed metals reveal a potentially worrying release of certain heavy metal species from some of the clay samples as a result of zinc adsorption.
      Graphical abstract image

      PubDate: 2017-10-03T17:56:04Z
      DOI: 10.1016/j.clay.2017.09.024
      Issue No: Vol. 150 (2017)
       
  • Poly(ε-caprolactone) filled with polydopamine-coated high aspect ratio
           layered double hydroxide: Simultaneous enhancement of mechanical and
           barrier properties
    • Authors: Long Mao; Yuejun Liu; Huiqing Wu; Jianhong Chen; Jin Yao
      Pages: 202 - 209
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Long Mao, Yuejun Liu, Huiqing Wu, Jianhong Chen, Jin Yao
      Inspired by the versatile adhesion capability of marine adhesive proteins, core-shell structured polydopamine-coated layered double hydroxide (LDH@PDA) were prepared successfully by in-situ growing PDA on the surface of MgAl-LDH with a high aspect ratio. LDH@PDA/poly(ε-caprolactone) (PCL) nanocomposites were prepared by blending LDH@PDA and pure PCL via solution casting method to obtain homogeneous films. The results of thermal analysis confirmed that LDH@PDA can act as a nucleating agent. And thermal stability of nanocomposites was improved due to core-shell structured LDH@PDA. With incorporation of as low as 1wt% of LDH@PDA, a 20% increase in tensile strength (41.1MPa), 26% increase in elongation at break (772%) and 26% reduction in the oxygen relative permeability were achieved. The improvement in the mechanical and gas barrier properties of nanocomposites at low filler loading was attributed to the strong interfacial interaction of LDH@PDA wtih the PCL matrix.
      Graphical abstract image

      PubDate: 2017-10-03T17:56:04Z
      DOI: 10.1016/j.clay.2017.09.031
      Issue No: Vol. 150 (2017)
       
  • Comparative study of Keggin-type polyoxometalate pillared layered double
           hydroxides via two synthetic routes: Characterization and catalytic
           behavior in green epoxidation of cyclohexene
    • Authors: Juanjuan Ma; Min Yang; Qian Chen; Shusu Zhang; Han Cheng; Shiyue Wang; Lin Liu; Chengyan Zhang; Zhiwei Tong; Zhong Chen
      Pages: 210 - 216
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Juanjuan Ma, Min Yang, Qian Chen, Shusu Zhang, Han Cheng, Shiyue Wang, Lin Liu, Chengyan Zhang, Zhiwei Tong, Zhong Chen
      MgAl LDH pillared by Keggin-type polyoxometalate [PW12O40]3− (PW12) have been fabricated by the ion-exchange and exfoliation/restacking methods respectively (denoted as PW12/LDHEx and PW12/LDHRe). X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FTIR) spectroscopy and N2 adsorption-desorption were used to characterize the structure and morphology of the intercalated compounds. PW12/LDHRe can be obtained without the formation of the impurity phase, which is unavoidable for the ion-exchange product PW12/LDHEx. XRD results showed that the C3 axis of the PW12 anions is perpendicularly oriented to the surface of LDH layers. The catalytic properties of these hybrid materials were investigated in the green epoxidation of cyclohexene with oxygen as oxidant and isobutyraldehyde as co-reagent. Both hybrids were demonstrated to be efficient heterogeneous catalysts and can be recycled five times without obvious loss of catalytic activity. By comparison, PW12/LDHRe shows relatively higher catalytic activity and the conversion can reach 100% after 1.5h at 60°C.
      Graphical abstract image

      PubDate: 2017-10-03T17:56:04Z
      DOI: 10.1016/j.clay.2017.09.030
      Issue No: Vol. 150 (2017)
       
  • Thermal treatment of clay-based ceramic membranes for microfiltration of
           Acutodesmus obliquus
    • Authors: Julcelly Dayara de Oliveira Henriques; Marina Wendt Pedrassani; Walderson Klitzke; André Bellin Mariano; José Viriato Coelho Vargas; Rafael Bruno Vieira
      Pages: 217 - 224
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Julcelly Dayara de Oliveira Henriques, Marina Wendt Pedrassani, Walderson Klitzke, André Bellin Mariano, José Viriato Coelho Vargas, Rafael Bruno Vieira
      Tubular ceramic microfiltration membranes were prepared by extruding thermally treated clay (TC) and raw clay to form a porous tubular membrane with the addition of cationic manioc starch and toasted manioc flour. The influence of an applied thermal treatment on the proprieties of the clay and the microfiltration membranes was characterized by measuring the particle size distribution, pore size distribution, and mechanical strength and by conducting X-ray fluorescence analysis, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry. The membranes were used for microfiltration of Acutodesmus obliquus microalgae with various applied pressures in the range of 2×104–1×105 Pa with a volumetric flow rate of 6.94×10−5 m3·s−1 at a temperature of 10±5°C. The efficiency of each of the ceramic membranes was evaluated in terms of the permeate flux for water and microalgae and the microalga retention. The addition of TC to the membrane resulted in an optimal microalga permeate flux of 3.24×10−2 kg·m−2·s−1 and a microalga retention of 98.3% at 4×104 Pa and had positive impacts on the other proprieties measured. Overall, these results demonstrate a potential application of TC in ceramic membranes for crossflow microfiltration processes.

      PubDate: 2017-10-03T17:56:04Z
      DOI: 10.1016/j.clay.2017.09.017
      Issue No: Vol. 150 (2017)
       
  • Economic potential of glauconitic rocks in Bakchar deposit (S-E Western
           Siberia) for alternate potash fertilizer
    • Authors: Maxim Rudmin; Santanu Banerjee; Aleksey Mazurov; Boris Makarov; Dmitry Martemyanov
      Pages: 225 - 233
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Maxim Rudmin, Santanu Banerjee, Aleksey Mazurov, Boris Makarov, Dmitry Martemyanov
      This paper explores suitability of glauconitic rocks in the Upper Cretaceous Bakchar deposit in Western Siberia as alternate potash fertilizer. The K2O content of these glauconitic rocks varies from 2.5 to 4.1wt.%, indicating their good potential as K-fertilizer for agronomic uses. According to the different compositional and textural characteristics, glauconitic rocks can be divided into three types, i.e., glauconitolite, glauconitic sandstone and glauconite-chamosite ooidal ironstone, with glauconite concentrations 58.5wt.%, 25.7wt.% and 24.6wt.%, respectively. The intermediate size fraction of glauconitolite concentrates up to 90.4wt.% of glauconite grains by using wet sieving. Magnetic separation further increases the concentration of glauconite grains for each type of rock samples, especially of glauconitic sandstone. Mixing of glauconitic products with soil increases the germination rate of oat seeds by up to 5.2%, the seedling height records an increase from 0.8% to 18.8%. Both untreated glauconitolite and its granulometric fraction result same rate of growth of oat seedlings. The results of this study suggest that the Bakchar glauconitic deposit can be used as a substitute potash fertilizer, with or without sieving and magnetic separation.

      PubDate: 2017-10-03T17:56:04Z
      DOI: 10.1016/j.clay.2017.09.035
      Issue No: Vol. 150 (2017)
       
  • Traditional brick productions in Madagascar: From raw material processing
           to firing technology
    • Authors: Celestino Grifa; Chiara Germinario; Alberto De Bonis; Mariano Mercurio; Francesco Izzo; Francesco Pepe; Piero Bareschino; Ciro Cucciniello; Vincenzo Monetti; Vincenzo Morra; Piergiulio Cappelletti; Giuseppe Cultrone; Alessio Langella
      Pages: 252 - 266
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Celestino Grifa, Chiara Germinario, Alberto De Bonis, Mariano Mercurio, Francesco Izzo, Francesco Pepe, Piero Bareschino, Ciro Cucciniello, Vincenzo Monetti, Vincenzo Morra, Piergiulio Cappelletti, Giuseppe Cultrone, Alessio Langella
      Bricks are the most common building materials of Madagascar due to the large availability of clayey raw material, the simple technology of production and the ease of use. The brick production is mainly organised in local workshops close to supplying site of clayey deposit where sediments are extracted, moulded in bricks, dried and then fired in open-air furnaces. Fuel varies from peat soils to wood depending on the local availability. Correspondingly, firing time varies from few days in wood furnaces to some weeks in peat fired furnaces. Samples of bricks and raw materials as well as peat fuel, from four workshops located in central and southwestern Madagascar were collected and analysed to infer the technological skills of the Malagasy traditional brick manufacture. Central Highlands Madagascar workshops use clayey lateritic soils formed from in situ weathering of basement rocks. The main plastic component of these deposits is kaolinite. Also the clayey sediments from southwestern Madagascar have kaolinite along with low-ordered clay minerals and carbonates such as calcite and minor Sr-rich dolomite. As far as fired bricks are concerned, experimental data evidenced quite low firing temperatures (below 600°C) in the two different furnaces, regardless the type of fuel. As far as peat fuel is concerned, its low calorific value along with a large amount of furnace energy dispersion does not allow to achieve the temperatures required to produce good quality bricks, notwithstanding long firing time (some weeks). On the other hand, firewood powdered furnaces, although providing much higher energy and a consequent much shorter firing process (few days), also suffer of diffuse heat dispersions which concur to the bad quality of the final product. The specific energy input calculated for type 1 furnace (peat fuel) ranges between 0.09MJ/kg and 0.18MJ/kg of clayey material thus confirming a rather inadequate firing process for the production of good quality bricks, and a rough estimate indicates that volume ratios between peat and clayey material as low as 1:1 should be used in order to reach “modern” specific energy inputs.

      PubDate: 2017-10-11T09:14:33Z
      DOI: 10.1016/j.clay.2017.09.033
      Issue No: Vol. 150 (2017)
       
  • Experimental study on the application of an ionic liquid as a shale
           inhibitor and inhibitive mechanism
    • Authors: Zhihua Luo; Longxiang Wang; Peizhi Yu; Zhangxin Chen
      Pages: 267 - 274
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Zhihua Luo, Longxiang Wang, Peizhi Yu, Zhangxin Chen
      Wellbore instability is caused to a great degree by shale hydration, which results from the interaction between the exposed shale formation and water-based drilling fluids in the exploration of oil and natural gas reservoirs. In this paper, an ionic liquid (ILB) is utilized as an efficient shale inhibitor in water-based drilling fluids to minimize shale hydration. The inhibitive property of ILB is evaluated by hot-rolling dispersion, capillary suction time and bentonite swelling tests. The test results indicate that 0.05wt% ILB exhibits superior inhibition performance than 5wt% conventional inhibitor potassium chloride (KCl) and its inhibition effect is approximately equal to that of 2wt% polyether diamine (PA). But different from KCl and PA, the presence of low concentration of ILB can also improve the rheological properties of water-based drilling fluids at high temperature, and meanwhile has no adverse effect on their filtration property. The investigation of inhibition mechanism indicates that the thermal stability of Na-Mt is greatly improved due to the intercalation with cationic group of ILB, leading to excellent inhibition property of ILB at high temperature. Furthermore, the adsorption of ILB in the interlayer of Na-Mt weakens the hydrophilicity of Na-Mt, which further inhibits water ingress.

      PubDate: 2017-10-11T09:14:33Z
      DOI: 10.1016/j.clay.2017.09.038
      Issue No: Vol. 150 (2017)
       
  • Mechanochemical activation of serpentine for recovering Cu (II) from
           wastewater
    • Authors: Pengwu Huang; Zhao Li; Min Chen; Huimin Hu; Zhiwu Lei; Qiwu Zhang; Wenyi Yuan
      Pages: 1 - 7
      Abstract: Publication date: 1 December 2017
      Source:Applied Clay Science, Volume 149
      Author(s): Pengwu Huang, Zhao Li, Min Chen, Huimin Hu, Zhiwu Lei, Qiwu Zhang, Wenyi Yuan
      In this paper, a novel method for copper removal was introduced, in which serpentine, a hydrated magnesium silicate, was activated by mechanical force to raise its reactivity as high as Mg hydroxide to remove Cu (II) from wastewater. Copper precipitation occurred easily when agitating the activated serpentine in copper sulfate solution. Characterizations of the activated samples and the samples after treatment of Cu (II) were also performed by X-ray diffraction (XRD), Thermogravimetry & Differential Scanning Calorimetry (TG-DSC). Chemical precipitation with wroewolfeite (CuSO4·3Cu(OH)2·2H2O), a basic copper sulfate, rather than the well known general adsorption by the raw mineral without activation, was formed and gave a very high capacity up to 538.8mg/g for copper removal, comparable with the precipitation by alkaline neutralization of Mg/Ca hydroxide. One more important advantage of using the activated serpentine allowed a selective copper removal from the solution with other metals as Ni (II), Mn (II), Zn (II) and Cd (II) remaining in the solution. The copper precipitate without coexistence of other metals may serve as a good source for copper recycling. The process based on using activated serpentine exhibits the merits for both environmental purification and copper recovery from secondary source/waste, providing a usable method for waste serpentine source as well.
      Graphical abstract image

      PubDate: 2017-09-08T03:01:58Z
      DOI: 10.1016/j.clay.2017.08.030
      Issue No: Vol. 149 (2017)
       
  • Comparison of dehydration in kaolin and illite using DC conductivity
           measurements
    • Authors: Marian Kubliha; Viera Trnovcová; Ján Ondruška; Igor Štubňa; Ondrej Bošák; Tiit Kaljuvee
      Pages: 8 - 12
      Abstract: Publication date: 1 December 2017
      Source:Applied Clay Science, Volume 149
      Author(s): Marian Kubliha, Viera Trnovcová, Ján Ondruška, Igor Štubňa, Ondrej Bošák, Tiit Kaljuvee
      Temperature dependencies of the DC conductivity of kaolin and illite are measured from 20°C up to 450°C using “as received” samples and samples after heating to 400°C and 450°C. Release of physically bound water (PBW) from green kaolin shows two maxima, at 55°C and 298°C. Release of the PBW from green illite takes place in 3 steps at 72°C, 186°C, and 298°C. Up to 200°C, the dominant charge carriers are H+ and OH– ions in both materials. At higher temperatures, alkali ions (both Na+ and K+ in kaolin, prevalently K+ in illite) are the dominant charge carriers with the conduction activation energy of 1.19±0.02eV in kaolin and of 1.12±0.02eV in illite. Above 400°C, dehydroxylation runs in illite. Due to this process, the DC conductivity of illite increases; in partly dehydroxylated illite, higher conduction activation energy (1.22eV) indicates that alkali metal ions are moving in a more disordered structure. In kaolin, dehydroxylation starts only above 450°C.

      PubDate: 2017-09-08T03:01:58Z
      DOI: 10.1016/j.clay.2017.08.012
      Issue No: Vol. 149 (2017)
       
  • Accelerated sorption of boron from aqueous solution by few-layer
           hydrotalcite nanosheets
    • Authors: Zhu Shu; Qinghai Guo; Yun Chen; Jun Zhou; Wei Guo; Yaowu Cao
      Pages: 13 - 19
      Abstract: Publication date: 1 December 2017
      Source:Applied Clay Science, Volume 149
      Author(s): Zhu Shu, Qinghai Guo, Yun Chen, Jun Zhou, Wei Guo, Yaowu Cao
      Boron is toxic to humans and animals at high concentrations. Hydrotalcite (HT) is an anion clay mineral capable of removing boron from water. In this work, the strategy of delamination of hydrotalcite was proposed and demonstrated to be effective in accelerating the boron sorption. Few-layer hydrotalcite (FHT) nanosheets were facilely obtained via rinsing the co-precipitated HT with acetone before final isolation, and achieved boron sorption equilibrium about 10 times faster than HT. The 2D nanosheet morphology helped FHT not only to disperse more fully in boron solution but also to expose more active sites on its external surface. As a result, the route for boron transferring from bulk solution to active sorption sites was effectively shortened on FHT, which finally induced a rapid boron removal.

      PubDate: 2017-09-20T03:10:43Z
      DOI: 10.1016/j.clay.2017.09.003
      Issue No: Vol. 149 (2017)
       
  • Evaluation of polymeric Al-modified bentonite for its potential
           application as ceramic coating
    • Authors: J.M. Martinez; C. Volzone; L.B. Garrido
      Pages: 20 - 27
      Abstract: Publication date: 1 December 2017
      Source:Applied Clay Science, Volume 149
      Author(s): J.M. Martinez, C. Volzone, L.B. Garrido
      A polymeric Al-modified bentonite (B-OHAl) obtained by intercalation of OH-Al species was used as precursor for mullite-containing coatings. Raw clay and B-OHAl were characterized by X-ray fluorescence (XRF), Infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TG-DTA). Rheological and electrokinetic behavior of B-OHAl dispersions were optimized by the addition of sodium polyacrylate (NaPA) for its use in dip coating on ceramic substrates. Moderate densification and mullite development of B-OHAl by thermal treatment up to 1200°C was observed by mercury intrusion porosimetry (MIP), XRD and scanning electron microscopy SEM. NaPA addition on dispersions and an increase in porosity values in substrate led to higher amounts of coating retained in dip coated composites sintered at 1200°C.

      PubDate: 2017-09-20T03:10:43Z
      DOI: 10.1016/j.clay.2017.09.004
      Issue No: Vol. 149 (2017)
       
  • Biosafe organic diacid intercalated LDH/PVC nanocomposites versus pure LDH
           and organic diacid intercalated LDH: Synthesis, characterization and
           removal behaviour of Cd2+ from aqueous test solution
    • Authors: Shadpour Mallakpour; Masoud Hatami
      Pages: 28 - 40
      Abstract: Publication date: 1 December 2017
      Source:Applied Clay Science, Volume 149
      Author(s): Shadpour Mallakpour, Masoud Hatami
      Highly real nanostructured clay adsorbents of layered double hydroxide (LDH) intercalated with biosafe and anionic organic diacid was produced at a constant pH with the coprecipitation method. XRD results disclosed that organic anionic segment is horizontally oriented in the interlayer space, which is obvious from developed basal spacing of 0.76 to 1.36nm. Also, a successfully LDH intercalation with examined biosafe diacid was observed using FT-IR and TGA analysis. Organo-intercalated LDH (I-LDH)/PVC nanocomposites (NCs) with different content of I-LDH loading were organized through ultrasound irradiation as a green method. The morphological behaviors and structured properties of achieved NCs were studied by characteristic analyses such as FT-IR, XRD FE-SEM and TEM. Results of thermal analysis disclosed positive influence of I-LDH on degradation temperature in compared to the neat PVC, and also residue at 800°C enhanced from 23 to 42%. The resulting LDH samples were studied for their performance in removing Cd2+ metal ion from aqueous test solution and the removal efficiency of these materials at proper pH, different adsorbent mass, Cd2+ concentrations and different times were documented by atomic adsorption spectrometry. In all samples, with the developed in the adsorbent mass, the removal efficiency for Cd2+ was improved at the 50mg/L of metal ion concentration and constant pH of 7.0. The maximum Cd2+ uptake was 86.17% related to the I-LDH/PVC NC 15wt%, and also the experimental data indicated a good compliance with the Langmuir isotherm and pseudo-second-order kinetic model for different LDH samples.
      Graphical abstract image

      PubDate: 2017-09-20T03:10:43Z
      DOI: 10.1016/j.clay.2017.09.006
      Issue No: Vol. 149 (2017)
       
  • Chamotte clay as potential low cost adsorbent to be used in the palm
           kernel biodiesel purification
    • Authors: Flavia D. Santos; Leyvison Rafael V. da Conceição; Annie Ceron; Heizir F. de Castro
      Pages: 41 - 50
      Abstract: Publication date: 1 December 2017
      Source:Applied Clay Science, Volume 149
      Author(s): Flavia D. Santos, Leyvison Rafael V. da Conceição, Annie Ceron, Heizir F. de Castro
      Solid waste from the red ceramic industry (chamotte clay) was assessed as glycerol adsorbent for biodiesel purification by dry washing. Its structure and composition was analyzed by several techniques, such as X-ray diffraction, FT-IR, scanning electron microscopy and particle size. By using a simulated medium (5w/v% glycerol in an ethanol solution), a face centered composite design was used to analyze the combined effect of chamotte concentration and temperature on glycerol removal. Chamotte levels of 2.5w/v% at 45°C maximized glycerol removal (1282mgglycerolg−1) with minimum loss of adsorbate. Kinetic data on glycerol adsorption by chamotte clay could be adjusted using the pseudo-second order model, which indicates that the rate-limiting step may be chemisorption. Moreover, chamotte clay was used for purifying ethyl biodiesel samples from palm kernel oil by chemical and biochemical catalysis. In the presence of chamotte clay, low glycerol levels (<0.02wt%) were found in comparison with crude biodiesel (0.29±0.03wt%). Chamotte clay was also able to remove residual levels of monoacylglycerols and diacylglycerols and provided samples with properties that are similar to those attained by traditional wet washing.
      Graphical abstract image

      PubDate: 2017-09-20T03:10:43Z
      DOI: 10.1016/j.clay.2017.09.009
      Issue No: Vol. 149 (2017)
       
  • Predicting the swelling pressure of MX-80 bentonite
    • Authors: Vicente Navarro; Gema De la Morena; Ángel Yustres; Jesús González-Arteaga; Laura Asensio
      Pages: 51 - 58
      Abstract: Publication date: 1 December 2017
      Source:Applied Clay Science, Volume 149
      Author(s): Vicente Navarro, Gema De la Morena, Ángel Yustres, Jesús González-Arteaga, Laura Asensio
      This paper proposes a calculation procedure to estimate the swelling pressure of bentonites. The experimental information needed to obtain the estimations can be obtained from relatively conventional tests, including the determination of the water retention curve, and swelling pressure tests using oedometric sample holders. This allows to obtain physically based predictions of the changes in swelling pressure with environment salinity. To facilitate the calculations, an open access spreadsheet in which the proposed approach has been implemented is attached as Supplementary material. A set of significant swelling pressure tests are modelled, obtaining very good fits. The fits not only build confidence in the proposed methodology, but also improve the validation of the hydro-chemo-mechanical formulation on which the proposed procedure is based.

      PubDate: 2017-09-20T03:10:43Z
      DOI: 10.1016/j.clay.2017.08.014
      Issue No: Vol. 149 (2017)
       
  • Functional characterization on colloidal suspensions containing xanthan
           gum (XGD) and polyanionic cellulose (PAC) used in drilling fluids for a
           shale formation
    • Authors: Yurany Villada; Felipe Gallardo; Eleonora Erdmann; Natalia Casis; Laura Olivares; Diana Estenoz
      Pages: 59 - 66
      Abstract: Publication date: 1 December 2017
      Source:Applied Clay Science, Volume 149
      Author(s): Yurany Villada, Felipe Gallardo, Eleonora Erdmann, Natalia Casis, Laura Olivares, Diana Estenoz
      Drilling fluids are employed in the operation of hydrocarbon exploitation. Two kinds of drilling fluids are commonly used: water based muds and oil based muds. The oil based muds are characterized by their high performance in unconventional reservoirs due to the very low interaction with the reactive formation. Their environmental impact promotes the design of water based muds that present low toxicity. In this paper a water based mud for shale formation with similar rheological characteristics to the oil based mud used in the oil industry of Argentina was designed and the effect of xanthan gum and polyanionic cellulose on the main functional characteristics was studied. Rheometric analysis showed a shear-thinning behavior with notable effect on the concentration of polymers. After dynamic aging test, fluids with composition of PAC=8.00g/L and XGD=3.00g/L exhibited rheological properties very close to oil base mud. Structural changes were assessed from optical microscopy and scanning electron microscopy. Particles agglomeration due to the presence of polymers was observed. Furthermore, mud filtration essays allowed to evaluate the performance of PAC as control agent. The Carreau model and statistical analysis were used to determine rheological parameters.
      Graphical abstract image

      PubDate: 2017-09-20T03:10:43Z
      DOI: 10.1016/j.clay.2017.08.020
      Issue No: Vol. 149 (2017)
       
  • Impact of an integrated no-till soybean–beef cattle production system on
           Oxisol mineralogy in southern Brazil
    • Authors: Vanessa Thoma Bertolazi; Alberto Vasconcellos Inda; Laurent Caner; Amanda Posselt Martins; Marcos André B. Vaz; Marine Bonnet; Ibanor Anghinoni; Paulo César F. Carvalho
      Pages: 67 - 74
      Abstract: Publication date: 1 December 2017
      Source:Applied Clay Science, Volume 149
      Author(s): Vanessa Thoma Bertolazi, Alberto Vasconcellos Inda, Laurent Caner, Amanda Posselt Martins, Marcos André B. Vaz, Marine Bonnet, Ibanor Anghinoni, Paulo César F. Carvalho
      Agricultural activities in the state of Rio Grande do Sul (RS), southern Brazil, have traditionally been quite intensive and led to decreased overall soil quality, and to depletion of soil organic matter and nutrients. There have been attempts at restoring soil quality by using integrated crop–livestock systems (ICLS). ICLS in association with no-tillage (NT) potentially increase soil organic matter content and nutrient supplies. The aim of this work was to assess the influence of grazing intensity in three different treatments [viz., intensive grazing (IG), moderate grazing (MG) and no grazing (NG)] on the mineralogy of an Oxisol in an integrated soybean–cattle beef production system in southern Brazil by using various types of methods and tests. Mineralogical XRD analyses of the clay fraction (<2μm) showed it to consist mainly of kaolinite and 2:1 clay minerals of the hydroxy-interlayered mineral (HIM) type. The reflections for 2:1 clay minerals under the IG treatment were better defined than those for the minerals under NG, which suggests the prevalence of HIMs. The 2:1 clay minerals in the IG group exhibited expandable layers. Splitting the clay fraction into three subfractions according to size (<0.05μm, 0.05–0.1μm and 0.1–2μm) exposed considerable alterations. Thus, hydroxy-aluminum interlayered vermiculite (HIV-Al) was present irrespective of treatment. Also, the HIV-Al reflection was better defined under IG and MG than under NG, which suggests strong aluminization of 2:1 clay minerals. Chemical analyses revealed a decrease in total organic carbon (TOC) with increasing depth in all treatments. The decrease was especially marked under NG by effect of the absence of animals favoring accumulation of plant shoots. pHwater was higher under IG as a result of the removal of aluminum from the soil solution increased aluminization of 2:1 clay minerals. K concentrations in solution were low under IG as a result of the formation of HIMs and/or swelling layers with exchangeable K; by contrast, solution K levels under NG where high owing to the absence of HIMs. The presence of animals, which increases K availability through animal wastes, may have resulted in competition between exchangeable K+ and Al3+ to form HIMs. Without splitting the clay fraction it would have been impossible to confirm the mineralogical alteration in 2:1 phyllosilicates due to the impact of ICLS systems.

      PubDate: 2017-09-20T03:10:43Z
      DOI: 10.1016/j.clay.2017.08.028
      Issue No: Vol. 149 (2017)
       
  • Analytical solution for clay plug swelling experiments
    • Authors: Simon A. Mathias; H. Chris Greenwell; Charlotte Withers; Ali R. Erdogan; Jim N. McElwaine; Chris MacMinn
      Pages: 75 - 78
      Abstract: Publication date: 1 December 2017
      Source:Applied Clay Science, Volume 149
      Author(s): Simon A. Mathias, H. Chris Greenwell, Charlotte Withers, Ali R. Erdogan, Jim N. McElwaine, Chris MacMinn
      Clay swelling experiments frequently involve monitoring the one-dimensional displacement with time of an initially dry clay plug as it imbibes water from a supply at its base. This article presents a new analytical solution for interpreting such experiments based on Richards' equation for flow in a partially saturated porous medium combined with a linear empirical function relating moisture ratio with void ratio. The analytical solution is described by just two parameter groups. The first parameter group describes the swelling potential of the clay. The second parameter group describes the rate at which the swelling plug reaches equilibrium, which is controlled by permeability and capillary pressure. Application of the analytical solution is demonstrated by calibration to one-dimensional displacement data from clay swelling experiments for an illite and bentonite clay.

      PubDate: 2017-09-20T03:10:43Z
      DOI: 10.1016/j.clay.2017.07.021
      Issue No: Vol. 149 (2017)
       
  • Development of cost effective bentonite adsorbent coating for the removal
           of organic pollutant
    • Authors: Shazlina Abd Hamid; Mohammad Shahadat; Suzylawati Ismail
      Pages: 79 - 86
      Abstract: Publication date: 1 December 2017
      Source:Applied Clay Science, Volume 149
      Author(s): Shazlina Abd Hamid, Mohammad Shahadat, Suzylawati Ismail
      The present study deals with the development of an innovative cost effective bentonite adsorbent coating (BAC) and simple mathematical equations are applied to enumerate coating requirement in treating textile effluent. The BAC has been successfully used for the removal of cationic dye from industrial wastewater. It has very good potential to be commercialized and applied by industries innovatively on the existing facilities with simple modifications. By installing bentonite coated fins inside tank, the concentration of dye can be easily reduced up to 90%. The BAC demonstrates good temperature and water resistant efficiency which can be easily coated on many surfaces. The best thickness and surface area of BAC for the optimal adsorption of dye (277.8mgg−1) was found as 87μm and 1.12×10−2 m2, respectively. The equilibrium adsorption data were best fitted by the Langmuir isotherm which indicates homogeneous monolayer adsorption. The mathematical formula obtained from isotherm model could be used in the removal and recovery of cationic dye (organic pollutant) in textile industry on large scale.
      Graphical abstract image

      PubDate: 2017-09-20T03:10:43Z
      DOI: 10.1016/j.clay.2017.07.022
      Issue No: Vol. 149 (2017)
       
  • Naturally occurring layered-mineral magnesium as a bactericidal against
           Escherichia coli
    • Authors: Luis Zarate-Reyes; Cynthia Lopez-Pacheco; Antonio Nieto-Camacho; María Teresa Ramírez Apán; Eduardo Palacios; Stephan Kaufhold; Kristian Ufer; Eduardo Garcia-Zepeda; Javiera Cervini-Silva
      Pages: 87 - 96
      Abstract: Publication date: 1 December 2017
      Source:Applied Clay Science, Volume 149
      Author(s): Luis Zarate-Reyes, Cynthia Lopez-Pacheco, Antonio Nieto-Camacho, María Teresa Ramírez Apán, Eduardo Palacios, Stephan Kaufhold, Kristian Ufer, Eduardo Garcia-Zepeda, Javiera Cervini-Silva
      Graphical abstract image

      PubDate: 2017-09-20T03:10:43Z
      DOI: 10.1016/j.clay.2017.07.035
      Issue No: Vol. 149 (2017)
       
  • Effect of waste rubber fibres on the geotechnical properties of clay
           stabilized with cement
    • Authors: J.S. Yadav; S.K. Tiwari
      Pages: 97 - 110
      Abstract: Publication date: 1 December 2017
      Source:Applied Clay Science, Volume 149
      Author(s): J.S. Yadav, S.K. Tiwari
      The voluminous generation of discarded waste rubber tires of about 1.5 million per year has created an aggravating situation across the globe because it exerts the deleterious effect on the human health and ecological systems. This paper focuses on the influence of inclusion of waste rubber tire fibres on some of the geotechnical properties of uncemented/cemented clay. For this investigation, three percentages of cement (0%, 3%, and 6%) and five percentages of rubber fibre (0%, 2.5%, 5%, 7.5%, and 10%) were considered. The tests namely, compaction, unconfined compressive strength, split tensile strength, California bearing ratio, swelling pressure, wet/dry cycles durability along with the scanning electron microscopy were conducted on the clay-cement-rubber fibre mixtures to ascertain the suitability of rubber fibres with cement stabilized clay. The test results revealed that the incorporation of rubber fibre reduces the unconfined compressive strength and split tensile strength of cement-stabilized clay but prosperously improves the rate of loss of post-peak strength and change the brittle failure behavior of cemented clay to ductile. The results of California bearing ratio test showed that the resistance against the penetration of the cement stabilized clay decreases as the content of rubber fibre increases. The swelling pressure of the clay was found to decrease with the increase in cement and rubber fibre content. The encouraging results of wet/dry cycles durability test proves the propriety of other tests on clay-cement-rubber fibre mixtures. Based on the test results, the maximum percentage of rubber fibre content mixed with cement-stabilized clay was found to be 7.5%. The study has shown that clay-cement-rubber fibre mixtures containing 6% cement and upto to 7.5% rubber fibre can be use as fill material, backfill material for retaining wall, sub-base of low volume traffic roads, and side slope of the canal.

      PubDate: 2017-09-20T03:10:43Z
      DOI: 10.1016/j.clay.2017.07.037
      Issue No: Vol. 149 (2017)
       
  • Gastroprotective effects of Tunisian green clay on ethanol-induced gastric
           mucosal lesion in rats
    • Authors: Ridha Ben Ali; Anouar Ounis; Dorra Ben Said; Chadli Dziri; Michèle Véronique El May
      Pages: 111 - 117
      Abstract: Publication date: 1 December 2017
      Source:Applied Clay Science, Volume 149
      Author(s): Ridha Ben Ali, Anouar Ounis, Dorra Ben Said, Chadli Dziri, Michèle Véronique El May
      Natural green clay is mostly used in pharmaceutical and cosmetic products. The effect of this raw material from different outcrops around the world demonstrates its beneficial role on human health. The green clay from southern Tunisia is widely used in local traditional medicine and cosmetic preparations but its biological activity in vivo has not been studied yet. For this reason, this work was interested in deciphering the properties of the Tunisian green clay such as mineralogy composition and biological effect. In fact, the mineralogical study of this green clay shows two types of clay minerals such as illite and kaolinite with proportion of 75% and 25%, respectively. In order to study the biological effect, green clay was administered orally to rats for 1h at 50, 75, 100 and 125mg/kg doses. After that, ethanol 95% was given to these rats to induce a gastric ulcer. Then, several parameters (e.g. Ulcer index, protective rate, mucus production gastric and mucosa histology) were measured to evaluate the gastroprotective activity. The histology study shows normal gastric mucosa in rats pretreated at 75, 100 and 125mg/kg doses and the decrease of Ulcer Index (%I=97%) and lesions areas. The oral administing mixture of Tunisian green clay with ethanol in rats induces severe mucosal lesion and hemorrhagic bands. This clay colored by methylene blue shows that clay was linked to the mucus excreted by the stomach surface. The green clay didn't neutralize ethanol gastro toxicity and formed a layer on the gastric mucosa to protect it by a mechanical action. When investigated on rats at an effective dose treatment (75mg/kg) for 30days, the subchronic toxicity test of green clay did not reveal any signs of mortality and toxicity, and it demonstrated the normal hematological and biochemical parameters of rats. Thus, the Tunisian green clay can be considered as a safe natural product since it has a potential gastroprotective activity on ethanol induced gastric mucosal lesions in rats.

      PubDate: 2017-09-20T03:10:43Z
      DOI: 10.1016/j.clay.2017.08.008
      Issue No: Vol. 149 (2017)
       
  • Synthesis, characterization and photocatalytic activity of TiO2-halloysite
           and Fe2O3-halloysite nanocomposites for photodegradation of chloroanilines
           in water
    • Authors: Beata Szczepanik; Paweł Rogala; Piotr M. Słomkiewicz; Dariusz Banaś; Aldona Kubala-Kukuś; Ilona Stabrawa
      Pages: 118 - 126
      Abstract: Publication date: 1 December 2017
      Source:Applied Clay Science, Volume 149
      Author(s): Beata Szczepanik, Paweł Rogala, Piotr M. Słomkiewicz, Dariusz Banaś, Aldona Kubala-Kukuś, Ilona Stabrawa
      The TiO2- and Fe2O3-halloysite nanocomposites were prepared using acid treated halloysite from Poland. The TiO2-halloysite nanocomposite was synthesized using titanium isopropoxide as a precursor under hydrothermal treatment at 65°C. The Fe2O3-halloysite nanocomposite was obtained using the sol-gel method. Gelatinous ferric hydroxide was applied as a ferric precursor. Chemical and phase composition, particle morphology, and physical properties of these nanocomposites were studied with the use of wavelength dispersive X-ray fluorescence (WDXRF), X-ray diffraction (XPRD), electron microscopy (TEM), FTIR technique, and N2 adsorption/desorption isotherms. The photocatalytic activities of TiO2- and Fe2O3-halloysite nanocomposites for aniline, 2-chloro-, and 2,6-dichloroaniline degradation under the UV irradiation were determined. The TiO2- and Fe2O3-halloysite nanocomposites showed significantly higher photocatalytic activity in decomposing aniline and its chloro derivatives than that of the commercial TiO2, commercial photocatalyst P25, and halloysite contains natural TiO2 dispersed on their surface.
      Graphical abstract image

      PubDate: 2017-09-20T03:10:43Z
      DOI: 10.1016/j.clay.2017.08.016
      Issue No: Vol. 149 (2017)
       
  • The role of the stress-path and importance of stress history on the flow
           of water along fractures and faults; an experimental study conducted on
           kaolinite gouge and Callovo-Oxfordian mudstone
    • Authors: Robert Cuss; Jon Harrington Shanvas Sathar Simon Norris Jean Talandier
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Robert J. Cuss, Jon F. Harrington, Shanvas Sathar, Simon Norris, Jean Talandier
      The flow of water along discontinuities, such as fractures or faults, is of paramount importance in understanding the hydromechanical response of an underground geological disposal facility for radioactive waste. This paper reports four experiments conducted on kaolinite gouge on a 30° slip-plane and on realistic fractures created in Callovo-Oxfordian mudstone (COx) from France. Test histories were conducted that initially loaded the gouge material in step changes in vertical stress, followed by unloading of the sample in similar steps. This loading-unloading history showed considerable hysteresis in hydraulic flow, with only partial recovery of fracture transmissivity. This demonstrates the importance of stress history on fracture flow; consideration of just the current stress acting upon a fracture or fault may result in inaccuracies of predicted hydraulic flow. The stress dependency of fracture flow in both kaolinite and COx can be described by a power-law or cubic relationship, which is likely to be dependent on the fracture roughness, thickness of gouge material, saturation state, permeability of the host material, and clay mineralogy (i.e. swelling potential). The observed response of fracture transmissivity to normal stress in COx is a complex superposition of mechanical response of the fracture and the swelling of clay in the fracture surface. The stress-dependency of flow was also seen to be dependent on orientation with respect to bedding. A fracture perpendicular with bedding accommodates greater compression and results in a lower transmissivity. The orientation dependence is related to the anisotropic swelling characteristics of COx.

      PubDate: 2017-10-11T09:14:33Z
       
  • Development of a novel ‘nanocarrier’ system based on Halloysite
           Nanotubes to overcome the complexation of ciprofloxacin with iron: An in
           vitro approach
    • Authors: Deepak Rawtani; Gaurav Pandey Maithri Tharmavaram Pooja Pathak Satyaprasad Akkireddy
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Deepak Rawtani, Gaurav Pandey, Maithri Tharmavaram, Pooja Pathak, Satyaprasad Akkireddy, Y.K. Agrawal
      The bioavailability of ciprofloxacin (CIP) is known to decrease upon administration due to its complexation with iron present in the body. A possible way to prevent this complexation is by entrapping the drug in a carrier. In this study, Halloysite Nanotubes (HNT) post functionalization with 3-aminopropyltriethoxysilane (APTES) were used as ‘nanocarrier’ for the entrapment of CIP. The complexation studies between CIP and iron revealed 71%±1.2% decrease in drug's absorbance upon complexation. Further, the in vitro antibacterial studies also exhibited a reduction in the antibacterial property of CIP on complexation with iron. Pristine HNT exhibited no interaction with CIP and iron. But post functionalization, the nanotubes had a strong interaction with iron and removed 80%±0.9% of it from the solution. Drug loading studies using functionalized HNT (fHNT) presented a 70%±1.7% loading of CIP on it. The samples of HNT (before and after functionalization and after drug loading) were characterized with TEM, XRD, FTIR and DSC. The drug release studies exhibited a sustained release of CIP from drug loaded fHNT. Further, drug loaded fHNT (CIP-fHNT) removed iron from the iron-rich solution and released the loaded drug back into the solution.
      Graphical abstract image

      PubDate: 2017-10-11T09:14:33Z
       
  • Urea–hydroxyapatite-montmorillonite nanohybrid composites as slow
           release nitrogen compositions
    • Authors: Nadeesh Madusanka; Chanaka Sandaruwan Nilwala Kottegoda Dinaratne Sirisena Imalka Munaweera
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Nadeesh Madusanka, Chanaka Sandaruwan, Nilwala Kottegoda, Dinaratne Sirisena, Imalka Munaweera, Ajith De Alwis, Veranja Karunaratne, Gehan A.J. Amaratunga
      Nanohybrid composite was developed by the encapsulation of urea modified hydroxyapatite nanoparticles into the nanolayers of montmorillonite. The nanohybrid composites were synthesized by two approaches; solution phase synthesis and liquid assisted grinding techniques and were tested for their slow release nitrogen in soil. The characterization results revealed the successful realization of a nanohybrid containing urea modified hydroxyapatite nanoparticles encapsulated in montmorillonite. The release behavior of urea in different pH values indicated a slow and sustained release of nitrogen. The rate of release of N was significantly lower in the nanohybrid composite prepared using solvent assisted grinding techniques. Pot trials conducted using Oryza sativa (rice) demonstrated a significant yield enhancement with the novel plant nutrient system. Montmorillonite nanohybrid composite thus prepared can be used as an environmentally friendly fertilizer formulation which could be extended to solve one of the major problems faced in the global fertilization of low nitrogen use efficiency in agriculture.
      Graphical abstract image

      PubDate: 2017-10-11T09:14:33Z
       
  • Zn-clay minerals in the Skorpion Zn nonsulfide deposit (Namibia):
           Identification and genetic clues revealed by HRTEM and AEM study
    • Authors: Giuseppina Balassone; Fernando Nieto Giuseppe Maria Boni Nicola Mondillo
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): Giuseppina Balassone, Fernando Nieto, Giuseppe Arfè, Maria Boni, Nicola Mondillo
      Zn-clays worldwide occur in various supergene nonsulfide (Zn-Pb) ores, where they can be the prevailing economic minerals or represent minor concentrations in the mineral assemblage. The world-class Zn smectite-rich Skorpion mine (Namibia) is considered one of the most important supergene nonsulfide zinc deposits in the world. At Skorpion, the trioctahedral Zn-bearing smectite predominates over the other Zn-oxidized minerals. This work is focused on microtextural observation and chemical analyses on the clay nano-particles of the supergene nonsulfide ores from Skorpion, carried out for the first time using TEM/HRTEM and AEM investigations. This approach helped to better understand the formation mechanism of the Skorpion Zn-clays and related phases down to the nanoscale. The microtextures of the Skorpion Zn-clays suggest they formed from fluids, meteoric and/or hydrothermal in nature, in two textural contexts: smectites can grow on previously deposited phyllosilicates (mica) (CCP texture), and/or directly nucleate from Zn-rich solutions (PCA texture). The Skorpion sauconite is chemically characterized by a greater homogeneity if compared with natural sauconites from other occurrences; it is quite stoichiometric, with Ca as interlayer cation and limited quantities of Mg and Fe, with an average composition of Ca0.14K0.02(Zn2.7Mg0.09Al0.14Fe0.10)(Si3.4Al0.6)O10(OH)2·nH2O. Contrary to Peru nonsulfide ores (Accha and Yanque), at the micro- and nanoscale the occurrence of Zn-beidellite at Skorpion is very subordinated. Chlorite and baileychlore have been also detected. Detrital micas are commonly the template for epitaxial sauconite growth. Typical supergene processes at ambient temperatures should be considered for the genesis of the Skorpion sauconite-bearing deposit, with some local contribution of low-T hydrothermal fluids. The micro- and nano-features of the Skorpion mineral assemblage confirm the complex mineralogical nature of the smectite-rich nonsulfide (micro)systems, with remarkable implications for mineralogical evaluation and processing.

      PubDate: 2017-10-11T09:14:33Z
       
  • New hybrid organic polymer montmorillonite/chitosan/polyphenylenediamine
           composites for nonlinear optical studies
    • Authors: Ramya Ch.; Rajashree P.L. Nayak Narayana Rao
      Abstract: Publication date: 15 December 2017
      Source:Applied Clay Science, Volume 150
      Author(s): E. Ramya, Ch. Rajashree, P.L. Nayak, D. Narayana Rao
      Biodegradable hybrid composites Chitosan/para-phenylenediamine (CS/pPDA), montmorillonite/chitosan/para-phenylenediamine (Mt/CS/pPDA), chitosan/ortho-phenylenediamine (CS/oPDA) and montmorillonite/chitosan/ortho-phenylenediamine (Mt/CS/oPDA) clay polymer nanocomposites (CPN) were successfully synthesized. The CPN composites were confirmed by using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), UV–Vis spectroscopy and photoluminescence (PL) measurements. The nonlinear optical properties (NLO) of CPN were studied by using Z-scan technique in the picosecond (ps) and femtosecond (fs) durations. Open aperture Z-scan studies revealed reverse saturable absorption (RSA) behavior, which gives nonlinear absorption and closed aperture data revealed nonlinear refraction in both time domains. Sign and magnitude of the third order nonlinearity were evaluated. Optical limiting characteristics of the systems for optical switching were examined. Hence, the new CPN can be used as optical limiters.

      PubDate: 2017-10-11T09:14:33Z
       
 
 
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