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  Subjects -> EARTH SCIENCES (Total: 636 journals)
    - EARTH SCIENCES (462 journals)
    - GEOLOGY (68 journals)
    - GEOPHYSICS (27 journals)
    - HYDROLOGY (21 journals)
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EARTH SCIENCES (462 journals)                  1 2 3 4 5 | Last

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: 7)
Acta Geotechnica     Hybrid Journal   (Followers: 9)
Acta Meteorologica Sinica     Hybrid Journal   (Followers: 4)
Advances in High Energy Physics     Open Access   (Followers: 11)
Advances In Physics     Hybrid Journal   (Followers: 7)
Aeolian Research     Hybrid Journal   (Followers: 3)
African Journal of Aquatic Science     Hybrid Journal   (Followers: 12)
Algological Studies     Full-text available via subscription   (Followers: 2)
Alpine Botany     Hybrid Journal   (Followers: 6)
AMBIO     Hybrid Journal   (Followers: 13)
Anales del Instituto de la Patagonia     Open Access   (Followers: 2)
Andean geology     Open Access   (Followers: 5)
Annales Henri Poincaré     Hybrid Journal   (Followers: 1)
Annales UMCS, Geographia, Geologia, Mineralogia et Petrographia     Open Access   (Followers: 2)
Annals of Geophysics     Full-text available via subscription   (Followers: 10)
Annals of GIS     Hybrid Journal   (Followers: 18)
Annals of Glaciology     Full-text available via subscription   (Followers: 2)
Annual Review of Marine Science     Full-text available via subscription   (Followers: 11)
Anthropocene     Hybrid Journal  
Anthropocene Review     Hybrid Journal   (Followers: 3)
Applied Clay Science     Hybrid Journal   (Followers: 3)
Applied Geochemistry     Hybrid Journal   (Followers: 8)
Applied Geomatics     Hybrid Journal   (Followers: 7)
Applied Geophysics     Hybrid Journal   (Followers: 6)
Applied Ocean Research     Hybrid Journal   (Followers: 6)
Applied Petrochemical Research     Open Access   (Followers: 3)
Applied Remote Sensing Journal     Open Access   (Followers: 11)
Aquatic Conservation Marine and Freshwater Ecosystems     Hybrid Journal   (Followers: 20)
Arctic Science     Open Access   (Followers: 4)
Arctic, Antarctic, and Alpine Research     Full-text available via subscription   (Followers: 9)
Artificial Satellites     Open Access   (Followers: 14)
Asia-Pacific Journal of Atmospheric Sciences     Hybrid Journal   (Followers: 2)
Asian Journal of Earth Sciences     Open Access   (Followers: 20)
Atlantic Geology : Journal of the Atlantic Geoscience Society / Atlantic Geology : revue de la Société Géoscientifique de l'Atlantique     Full-text available via subscription   (Followers: 3)
Atmosphere-Ocean     Full-text available via subscription   (Followers: 7)
Atmospheric and Climate Sciences     Open Access   (Followers: 15)
Australian Journal of Earth Sciences: An International Geoscience Journal of the Geological Society of Australia     Hybrid Journal   (Followers: 13)
Boletim de Ciências Geodésicas     Open Access  
Boreas: An International Journal of Quaternary Research     Hybrid Journal   (Followers: 10)
Bragantia     Open Access   (Followers: 2)
Bulletin of Earthquake Engineering     Hybrid Journal   (Followers: 10)
Bulletin of Geosciences     Open Access   (Followers: 9)
Bulletin of the Lebedev Physics Institute     Hybrid Journal   (Followers: 1)
Bulletin of the Seismological Society of America     Full-text available via subscription   (Followers: 18)
Bulletin of Volcanology     Hybrid Journal   (Followers: 16)
Canadian Journal of Plant Science     Full-text available via subscription   (Followers: 13)
Canadian Mineralogist     Full-text available via subscription   (Followers: 2)
Canadian Water Resources Journal     Hybrid Journal   (Followers: 20)
Carbonates and Evaporites     Hybrid Journal   (Followers: 4)
CATENA     Hybrid Journal   (Followers: 4)
Chemical Geology     Hybrid Journal   (Followers: 10)
Chemie der Erde - Geochemistry     Hybrid Journal   (Followers: 4)
Chinese Geographical Science     Hybrid Journal   (Followers: 5)
Chinese Journal of Geochemistry     Hybrid Journal   (Followers: 3)
Chinese Journal of Oceanology and Limnology     Hybrid Journal   (Followers: 2)
Ciencia del suelo     Open Access   (Followers: 1)
Ciencias Espaciales     Open Access  
Climate and Development     Hybrid Journal   (Followers: 12)
Coastal Management     Hybrid Journal   (Followers: 17)
Cogent Geoscience     Open Access  
Comptes Rendus Geoscience     Full-text available via subscription   (Followers: 6)
Computational Geosciences     Hybrid Journal   (Followers: 13)
Computational Mathematics and Mathematical Physics     Hybrid Journal   (Followers: 1)
Computers and Geotechnics     Hybrid Journal   (Followers: 7)
Contemporary Trends in Geoscience     Open Access   (Followers: 2)
Continental Shelf Research     Hybrid Journal   (Followers: 8)
Contributions to Mineralogy and Petrology     Hybrid Journal   (Followers: 8)
Contributions to Plasma Physics     Hybrid Journal   (Followers: 2)
Coral Reefs     Hybrid Journal   (Followers: 16)
Cretaceous Research     Hybrid Journal   (Followers: 6)
Cybergeo : European Journal of Geography     Open Access   (Followers: 5)
Depositional Record     Open Access  
Developments in Geotectonics     Full-text available via subscription   (Followers: 3)
Developments in Quaternary Science     Full-text available via subscription   (Followers: 3)
Développement durable et territoires     Open Access   (Followers: 2)
Diatom Research     Hybrid Journal  
Doklady Physics     Hybrid Journal   (Followers: 1)
Dynamics of Atmospheres and Oceans     Hybrid Journal   (Followers: 3)
E&S Engineering and Science     Open Access  
E3S Web of Conferences     Open Access  
Earth and Planetary Science Letters     Hybrid Journal   (Followers: 75)
Earth and Space Science     Open Access  
Earth Interactions     Full-text available via subscription   (Followers: 11)
Earth Science Research     Open Access   (Followers: 7)
Earth Surface Dynamics (ESurf)     Open Access   (Followers: 3)
Earth Surface Processes and Landforms     Hybrid Journal   (Followers: 13)
Earth System Dynamics     Open Access   (Followers: 7)
Earth System Dynamics Discussions     Open Access   (Followers: 4)
Earth's Future     Open Access   (Followers: 1)
Earth, Planets and Space     Open Access   (Followers: 3)
Earthquake Engineering and Engineering Vibration     Hybrid Journal   (Followers: 7)
Earthquake Science     Hybrid Journal   (Followers: 8)
Earthquake Spectra     Full-text available via subscription   (Followers: 13)
Ecohydrology     Hybrid Journal   (Followers: 10)
Electromagnetics     Hybrid Journal   (Followers: 2)
Energy Efficiency     Hybrid Journal   (Followers: 12)
Energy Exploration & Exploitation     Full-text available via subscription   (Followers: 3)
Environmental Earth Sciences     Hybrid Journal   (Followers: 12)

        1 2 3 4 5 | Last

Journal Cover   Applied Clay Science
  [SJR: 1.17]   [H-I: 71]   [3 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0169-1317
   Published by Elsevier Homepage  [2800 journals]
  • Anisotropy of thermal conductivity and elastic properties of extruded
           clay-based materials: Evolution with thermal treatment
    • Abstract: Publication date: November 2015
      Source:Applied Clay Science, Volumes 116–117
      Author(s): J. Bourret, N. Tessier-Doyen, R. Guinebretiere, E. Joussein, D.S. Smith
      Kaolinite and muscovite are major clay mineral phases found in the raw materials used for tile and brick production. As phyllosilicates, the crystal structures are layered yielding anisotropic properties. The thermo-physical properties of an extruded clay material, essentially composed of kaolinite, quartz and muscovite have been investigated in the parallel and perpendicular directions to the extrusion axis. Texture is characterized by scanning electron microscopy observations and X-ray diffraction measurements. Values of effective thermal conductivity measured by the laser flash technique and Young's modulus measured with an ultrasonic pulse-echo method reveal an anisotropy factor of 2 for the material in the green body at the macroscopic scale. The thermal conductivity of the solid phases of the material without the quartz fraction was then estimated using an analysis based on the Maxwell–Eucken and Landauer relations. This yields an anisotropy ratio=3.5 for the clay phase, explained by the alignment of kaolinite and muscovite particles with the extrusion process. The elastic and thermal properties evolve as a function of the heat treatment temperature for the clay, resulting in isotropic behavior after treatment at 1300°C. These evolutions are concomitant with mineralogical transformations of kaolinite including the formation of mullite above 1000°C.


      PubDate: 2015-08-30T18:59:33Z
       
  • Analyzing the effect of various soil properties on the estimation of soil
           specific surface area by different methods
    • Abstract: Publication date: November 2015
      Source:Applied Clay Science, Volumes 116–117
      Author(s): Hossein Bayat, Eisa Ebrahimi, Sabit Ersahin, Estela N. Hepper, Devendra Narain Singh, Abdel-monem Mohamed Amer, Yeliz Yukselen-Aksoy
      Depending on the method used, measuring the specific surface area (SSA) can be expensive and time consuming and limited numbers of studies have been conducted to predict SSA from soil properties. In this study, 127 soil sample data were gathered from the available literature. The data set included SSA values and some of the soil physical and chemical index properties. At the first step, linear regression, non-linear regression, regression trees, artificial neural networks, and a multi-objective group method of data handling were used to develop seven pedotransfer functions (PTFs) for the purpose of finding the best method in predicting SSA. Results showed that the artificial neural networks performed better than the other methods used in the development and validation of PTFs. At the second step, to find the best set of SSA for predicting input variables and to investigate the importance of the input parameters, the artificial neural networks were further used and 25 models were developed. The results showed that the PTF, containing the input variables of sand%, clay%, plastic limit, liquid limit, and free swelling index performed better than the other PTFs. This can be attributed to the close relation between the free swelling index and Atterberg limits with the soil clay mineralogy, which is one of the most important factors controlling SSA. The sensitivity analysis showed that the greatest sensitivity coefficients were found for the cation exchange capacity, clay content, liquid limit, and plasticity index in different models. Overall, the artificial neural networks method was proper to predict SSA from soil variables.


      PubDate: 2015-08-30T18:59:33Z
       
  • Effect of formation pH, molar ratio and calcination temperature on the
           synthesis of an anionic clay based adsorbent targeting defluoridation
    • Abstract: Publication date: November 2015
      Source:Applied Clay Science, Volumes 116–117
      Author(s): P.S. Ghosal, A.K. Gupta, S. Ayoob
      Calcined Ca Al (NO3) LDH, an anionic clay based adsorbent, was synthesized at different process conditions. The influence of formation pH, molar ratio, and calcination temperature on the physicochemical characteristics of this adsorbent was assessed. The response surface methodology (RSM) was applied to optimize the adsorption capacity by employing a 33 factorial design. Characterization of the adsorbent was conducted through XRD, FTIR, EDX, SEM and N2 adsorption desorption analysis. A significant variation in adsorption capacity (6.4 to 12.5mg/g) was observed for the experimental points designed. XRD results demonstrated that the increase in formation pH enhances the crystallinity of the LDH material. The defluoridation capacity was observed to decrease with increasing pH or molar ratio, as the aluminum content in LDH structure was found to be inversely correlated with both the factors. The fluoride adsorption capacity was found to attain optima at a calcination temperature of approximately 500°C. The reconstruction of the original structure from the calcined product of LDH through a ‘memory effect’ may enhance its adsorption capacity. The maximum adsorption capacity by the Langmuir isotherm model was estimated to be 108.69mg/g.
      Graphical abstract image

      PubDate: 2015-08-30T18:59:33Z
       
  • The potential of clinoptilolite-rich tuffs from Croatia and Serbia for the
           reduction of toxic concentrations of cations and anions in aqueous
           solutions
    • Abstract: Publication date: November 2015
      Source:Applied Clay Science, Volumes 116–117
      Author(s): Karmen Margeta, Štefica Cerjan Stefanović, Venčeslav Kaučič, Nataša Zabukovec Logar
      Natural zeolites have a great potential as low-cost, non-toxic and highly selective sorbents in pollution control, especially in waste-water management. The potential of Croatian and Serbian clinoptilolite-rich (HEU-type zeolite) tuffs from four different deposits have been evaluated for their use in metal removal from aqueous solutions by the application of adsorption equilibrium studies, structural studies of metal-loaded zeolite tuffs and their regeneration or further treatment, which were performed in our laboratories or were reported by other authors. The results showed that metals like copper could be completely removed from aqueous solutions at low metal concentrations using Serbian and/or Croatian zeolites (up to 120mg Cu/L). At higher concentrations the efficiency of zeolites slowly decreased, also in accordance with the theoretical adsorption capacities. The studies confirmed that a higher content of zeolite in tuffs from Serbia (70–80% vs. 50% for Croatian tuff) resulted in their better adsorption performance for selected metals. Additionally, the pretreatment of zeolites with Na+ significantly enhanced the uptake of all metal cations, while the pretreatment with Fe3+, which resulted in stable iron-oxo-species on the zeolite surface and positive charge of the framework, enabled the adsorption of anions, like arsenites, arsenates and chromates. The reversibility of the metal uptake depended on the type of metal; for example, post-treatment of the samples with HCl, NaCl or NH4Cl solutions revealed irreversible adsorption of chromium and arsenic and mostly reversible adsorption of zinc and copper. The possible strategies for the regeneration or immobilization of the used metal-loaded zeolites, like immobilization in cements or the use as catalysts, were also considered.
      Graphical abstract image

      PubDate: 2015-08-30T18:59:33Z
       
  • The non-micellar template model for porous clay heterostructures: A
           perspective from the layer charge of base clay
    • Abstract: Publication date: November 2015
      Source:Applied Clay Science, Volumes 116–117
      Author(s): Yuebo Wang, Xiaoli Su, Xiaoqin Lin, Ping Zhang, Ke Wen, Jianxi Zhu, Hongping He
      In this paper, the effect of layer charge (LC) of base clay on the structural properties of porous clay heterostructures (PCHs) was studied. Three natural montmorillonites (Mt) with different LC and a series of reduced-charge Mt were used in the synthesis of PCH to discuss the non-micellar template model for PCH from the perspective of base clay. The PCH samples are the intergrowth of a porous silica-intercalated clay and an amorphous silica component. The XRD and TEM studies revealed that the d001-values of PCH samples prepared from natural Mt (simply as “natural PCH” for short) were larger than 3nm. The interstratified structures in PCH samples from reduced-charge Mt (simply as “reduced-charge PCH” for short) were the result of the collapse of interlayer spaces caused by the inhomogeneous LC reduction. The organic carbon contents (f OC) of organo-montmorillonite (OMt) were negatively correlated with the bulk silica contents (f SiO2-b) of the corresponding PCH samples. For the natural PCH, the extra spaces from decreased surfactant within interlayer were occupied by amorphous silica in the pillaring reaction. The decreased specific surface area (SSA), porosity and the invariant dominant pore size (1.3–1.4nm) of PCH suggested that blocking the pore channels in the interlayer spaces with increased silica was more pronounced than propping the layers permanently apart and building porous structures. Based on the effect of organic template and base clay on the structural properties in our previous and present work, Mt-based PCH probably is a type of porous materials with invariant pore size.
      Graphical abstract image

      PubDate: 2015-08-30T18:59:33Z
       
  • The influence of dispersion and distribution of ultrafine kaolinite in
           polyamide-6 on the mechanical properties and fire retardancy
    • Abstract: Publication date: November 2015
      Source:Applied Clay Science, Volumes 116–117
      Author(s): M. Batistella, A.S. Caro-Bretelle, B. Otazaghine, P. Ienny, R. Sonnier, C. Petter, J.M. Lopez-Cuesta
      The aim of this paper is to demonstrate that morphological particle properties inside the polymer matrix are responsible for the variability of mechanical properties (elasticity, strength, resilience) and fire retardancy properties. Ultrafine kaolinites were modified and employed to obtain composites of polyamide. These composites were characterized by means of mechanical (tensile static and dynamic tests) and fire retardancy properties (cone calorimeter). Their morphological properties differed significantly according to the aspect ratio and surface treatment of the kaolinites. These morphologies, characterized by the particle dispersion (interparticle distance ID) and size distribution (median diameter MD) in the polymer matrix, were directly related to the mechanical properties. The experimental results demonstrate the sensitivity of strength, resilience and flammability to particle dispersion and distribution. The yield stress decreases with the increase of MD, the resilience decreases with the increase of ID with a critical ID value from which the composite became brittle, and the pHRR increases with the increase of ID.


      PubDate: 2015-08-25T18:39:15Z
       
  • Physicochemical and in vitro cation release relevance of therapeutic muds
           “maturation”
    • Abstract: Publication date: November 2015
      Source:Applied Clay Science, Volumes 116–117
      Author(s): Rita Sánchez-Espejo, Pilar Cerezo, Carola Aguzzi, Alberto López-Galindo, José Machado, César Viseras
      Therapeutic muds are used in the treatment of illnesses of the locomotor apparatus, including osteoarthritis and rheumatologic diseases. The mechanisms of action of this therapy are a matter of discussion, mainly for the different traditions of pelotherapy centers. Heat plays a fundamental role in the beneficial effects of thermal mud therapy together with the possible transfer across the skin barrier of chemical elements presented in the mud. Preparation procedures of therapeutic muds have been orally transmitted since ancient times, being accepted that muds require a “maturation” process to achieve the desired therapeutic results. Pharmaceutical research of maturation is crucial to ascertain the possible changes induced by this operation in the properties of muds. In particular, it is necessary to verify the changes associated with physical and/or chemical therapeutic mechanisms that sustain the traditional use of maturation in the preparation of therapeutic muds. Two clay samples were used to prepare thermal muds with mineral medicinal water from the thermal spring of Graena (Cortes y Graena, Granada, Spain). Muds were matured for three months and characterized over time for those properties considered relevant in view of their topical administration (rheological properties and particle size distribution) and possible mechanisms of action (composition, pH, cation exchange capacity, thermal properties and amount of cations released). Maturation of the studied therapeutic muds did not induce alteration of clay minerals, even if a decrease in amplitude of particle size distribution, changes in pH and disappearance of thixotropic behavior were observed. Maturation increased the release of cations from therapeutic muds but did not improve their thermal properties. In the studied case, thermophysical activity did not require maturation. Conversely, maturation increased the amount of cations released from the muds, appearing as a beneficial process for possible chemical therapeutic effects associated with the ionic content of these systems. Maturation could therefore explain the differential chemical effects associated with the use of therapeutic muds compared to other thermotherapeutic agents.


      PubDate: 2015-08-25T18:39:15Z
       
  • Synchrotron X-ray diffraction of bole layers from Portuguese gilded
           baroque retables
    • Abstract: Publication date: November 2015
      Source:Applied Clay Science, Volumes 116–117
      Author(s): C. Barata, F. Rocha, A.J. Cruz, S. Andrejkovičová, S. Reguer
      Studies based on a scientific approach to materials and techniques used in Portuguese gilded retables from the Baroque are very scarce and focus particularly on works with erudite features and on the characterization of the superficial gold leaf. The conservation and appearance of gilded surfaces, however, depended on the qualities of the clayey ground layer underneath, which is the bole. Colour and texture are closely related to its mineralogical composition. Boles were healing clays. Red to orange varieties could also be used for gilding, usually agglutinated with animal glue when the gold surface was meant to be burnished. Armenian was the name used to identify the best quality material. Microsamples collected from erudite and popular gilded retables, respectively belonging to the city of Oporto and its rural surroundings, were selected for elemental and mineralogical characterization. It was intended to shed light on the characteristics of boles used in Portuguese retables and to understand if there are any differences between materials used in works of distinct artistic quality. Elemental analysis was performed through SEM–EDS. SR-XRD was used for phase identification, performed with a six-circle diffractometer at the DIFFABS beamline of SOLEIL Synchrotron. Portuguese clay standards of identifiable composition and provenance were also analysed. The results suggest that boles are mainly kaolinitic, with variable amounts of illite and smectite. Gypsum was used as an extender. Although the proportions of the main clay minerals are similar in erudite and popular works, in Oporto homogeneity is clearly higher.


      PubDate: 2015-08-25T18:39:15Z
       
  • Effect of acid activation of Saudi local clay mineral on removal
           properties of basic blue 41 from an aqueous solution
    • Abstract: Publication date: November 2015
      Source:Applied Clay Science, Volumes 116–117
      Author(s): Fethi Kooli, Yan Liu, Rawan Al-Faze, Awadh Al Suhaimi
      Local clay mineral from Khulais area, was activated at different acid to clay mineral ratios (in mass) at 90°C. The local clay mineral contained a major phase of smectite, in addition to kaolinite and quartz as impurities. Upon acid activation, structural changes in the treated clay minerals occurred for the smectite phase. The other phases were not affected as indicated by powder x-ray diffraction and Fourier transform infrared. Decrease in contents for Al2O3, MgO, Fe2O3, and Na2O, followed by a relative increase in SiO2 occurred. The acid activated clays exhibited lower cation exchange capacity, and higher specific surface areas. These changes in chemical compositions and other properties were related to the extent of the acid activation process. The acidity of local clay mineral was enhanced up to a certain level of activation, then it decreased gradually. A maximum specific surface area of 330m2/g was achieved at an acid to clay mineral ratio of 0.5. The increase of surface area was not the main key that controlled the removal capacity of the acid activated clays for basic blue-41 dye. The acid activation has improved the removal capacity of the raw clay mineral from 50mg/g to 73mg/g. This capacity was reduced with the extent of the acid activation, and was related to the destruction of the removal sites during the acid activation and not to the specific surface areas of the clay mineral. The recycling of spent acid activated clay was achieved by the sulfate radical oxidation, and about 85% of dye removal could be still retained after six recycle runs.


      PubDate: 2015-08-25T18:39:15Z
       
  • Water/clay ratio, clay porosity models and impacts upon clay
           transformations
    • Abstract: Publication date: November 2015
      Source:Applied Clay Science, Volumes 116–117
      Author(s): David Savage, Jinsong Liu
      The performance of bentonite used in geological repositories for radioactive waste may be impaired by long-term clay transformations to non-swelling minerals. Intrinsic to alteration processes is the role of water/clay ratio, defined in a bentonite-pore fluid system by (the inverse of) porosity. Water/(water+clay) mass ratios are low for both ‘total’ (≤0.25) and ‘free’ (≤0.05) porosities in compacted bentonite at the dry density envisaged for waste package buffers (≥1500kgm−3). A survey of laboratory experimental studies of clay alteration has shown that they have tended to focus on systems with dispersed clays at high water/(water+clay) mass ratios (≥0.75) because of experimental practicalities and a desire to accelerate reactions. New thermodynamic calculations have illustrated that the fluid/clay ratio can have an important impact not only upon the magnitude of alteration, but also upon the nature of the reaction path. Reaction of a pure Na-montmorillonite with cement pore fluids, a Fe-rich fluid and a KCl solution to attempt to simulate reaction of clay with cement/concrete, iron/steel, and potassium-rich fluids (to investigate the smectite to illite reaction path), respectively has shown that under fluid-dominated conditions (high water/clay ratio), clay alteration consisted of C–S–H solids, low-Si zeolites, and chlorite. Under clay-dominated conditions (low water/clay ratios), alteration typically consisted of high-Si zeolites, feldspar and Mg-corrensite. Consequently, it is of key importance that the most relevant water/clay ratio (‘porosity’) is used not only in geochemical calculations, but also in experimental systems.


      PubDate: 2015-08-25T18:39:15Z
       
  • Particle films and their applications in horticultural crops
    • Abstract: Publication date: November 2015
      Source:Applied Clay Science, Volumes 116–117
      Author(s): R.R. Sharma, S. Vijay Rakesh Reddy, S.C. Datta
      Due to rising health concern, the idea of Good Agricultural Practices (GAPs) has emerged, especially for growing crops organically. In this context, several innovative technologies have been developed by agricultural scientists, such as the particle film technology (PFT). They are basically aqueous formulations made from chemically inert clay or mineral particles, which are specifically formulated for coating to reduce the damage caused by insects, diseases, solar injury, freeze injury and to improve fruit finish, color, carbon assimilation rate, yield and postharvest fruit quality. The development of the first such kaolin-based formulation, named Surround®, for commercial use was by Engelhard Corporation, Iselin, New Jersey (U.S.A.) in 1999. During the last two decades, a significant amount of research work has been conducted on the development of several such films (Surround® CF, Surround® WP, Raynox®, Cocoon™, Purshade™, Parasol®, Screen®, Snow®, Eclipse™, etc.) and their effects on various agricultural and horticultural crops. Considering the usefulness of these films, we attempted to compile the scattered information on the developed particle films, their modes of action and effects on various horticultural crops, in the form of a review. The review is particularly focused on history, modes of action, application and a variety of effects of particle films on horticultural crops.


      PubDate: 2015-08-25T18:39:15Z
       
  • Effect of precursor synthesis on the physicochemical properties of
           Zn–Mg–Al mixed oxides
    • Abstract: Publication date: November 2015
      Source:Applied Clay Science, Volumes 116–117
      Author(s): Weberton Reis do Carmo, Juliana Fischer-Haddad, Luciano Honorato Chagas, Marilia S.S. Beltrão, Gustavo S.G. de Carvalho, Luiz Carlos A. de Oliveira, Talita E. Souza, Alexandre Amaral Leitão, Renata Diniz
      In this work, the influence of the zinc content and synthesis methodology on the physicochemical properties of mixed oxide derivatives from the hydrotalcite precursor MgZnAl-HT were evaluated. Layered double hydroxides (LDH) were prepared by co-precipitation, ultrasound and urea hydrolysis methods followed by calcination at 500°C. The materials were studied by such techniques as inductively coupled plasma, X-ray powder diffraction, Raman spectroscopy and 27Al solid-state NMR spectroscopy. The textural and morphological properties of mixed oxides were evaluated through the adsorption/desorption of N2 and scanning electron microscopy (SEM). Different textural and morphological properties were observed for the samples.


      PubDate: 2015-08-25T18:39:15Z
       
  • Layered double hydroxide–agarose composites for water treatment:
           carbonate contamination during the drying process
    • Abstract: Publication date: November 2015
      Source:Applied Clay Science, Volumes 116–117
      Author(s): Toshiyuki Hibino
      Layered double hydroxides (LDH) are anion exchangers and have been investigated intensively as adsorbents for removal of hazardous and toxic anionic substances in water treatment. However, LDH, which are usually synthesized in the form of a powder, are often difficult to separate from suspensions in water treatment. Incorporating LDH into composite hydrogels is a strategy to avoid this difficulty: in this study, aqueous suspensions of Cl-containing LDH of high and low crystallinity were mixed with agarose solution while heating, and the mixtures were allowed to cool to form gels. However, in wet conditions, LDH would be susceptible to carbonate contamination from atmospheric CO2. In this context, LDH–agarose composite hydrogels were synthesized, and gels dried in three different ways (air drying, oven drying in air at 110°C, and vacuum drying) were evaluated as anion adsorbents by using SO4 2−. The air-dried gels showed significant reductions in SO4 2− adsorption abilities compared to those of the original undried gels: 56% reduction for air-dried gels containing the low-crystallinity LDH and 29% reduction for air-dried gels containing the high-crystallinity LDH. This result shows that carbonate contamination was extremely serious for low-crystallinity LDH in the gel. In contrast, the oven- and vacuum-dried gels retained adsorption abilities that were almost the same as those of the original undried gels, regardless of crystallinity of LDH in the gels. Powdery form of LDH showed similar results about drying. These results show how important the drying methods are, and provide fundamental information about carbonate contamination.


      PubDate: 2015-08-25T18:39:15Z
       
  • A study on the influence of inorganic salts on the behaviour of compacted
           bentonites
    • Abstract: Publication date: November 2015
      Source:Applied Clay Science, Volumes 116–117
      Author(s): J. Dutta, A.K. Mishra
      Clay liners are frequently installed at waste disposal sites as a means of preventing pollutant migration and minimizing or eliminating the potential for ground water contamination. Because of their low hydraulic conductivity and high contaminant adsorption capacity, bentonite is used as a liner material to prevent subsurface contamination. However, presence of various chemicals in waste could affect the hydraulic and contamination adsorption capacity of bentonite and in turn reduce its usefulness as barrier material. In addition to the salt solution, a change in the mineralogical composition such as montmorillonite content, cation exchange capacity, specific surface area, exchangeable sodium percentage of the bentonite also significantly influences its swelling and hydraulic behaviour. This study was carried out to study the effect of salt solution and mineralogical composition on the behaviour of compacted bentonite. Two bentonites with varying mineralogical composition, which was reflected in their different liquid limit and free swelling value, were evaluated for their free swelling, Atterberg limits, swelling potential, swelling pressure, and hydraulic conductivity in the presence of various concentrations of NaCl and CaCl2 solution. To study the effect of initial compaction conditions on swelling and hydraulic behaviour in presence of salt solution, studies were also carried out on samples compacted at optimum moisture content (OMC)–maximum dry density (MDD) and 5% dry of OMC–MDD. The result shows that the liquid limit, swelling volume, swelling pressure of the compacted bentonites decreased, whereas, plastic limit and hydraulic conductivity increased with increase in the salt concentration. The results also show that the effect of the salt on the properties of the bentonites depends on the salt type, salt concentration and initial compaction condition of the bentonite. The effects due to salt concentration were found to be more pronounced for the bentonite of higher quality which is marked by a higher swelling capacity, liquid limit, cation exchange capacity, exchangeable sodium percentage and specific surface area.


      PubDate: 2015-08-25T18:39:15Z
       
  • Influence of synthesis method in preparation of HDTMA+- and
           HDPy+-illites/smectites
    • Abstract: Publication date: November 2015
      Source:Applied Clay Science, Volumes 116–117
      Author(s): S. Gamoudi, N. Frini-Srasra, E. Srasra
      Intercalation of cationic surfactants hexadecylpyridinium (HDPy+) and hexadecyltrimethylammonium (HDTMA+) into the interlayer space of homoionic (Na+-, Ca++- and Zn++-) illites/smectites using three methods (solution intercalation, solid–solid reaction and microwave irradiation) was investigated in this study. The changes in the surfaces and structures of the organo-illites/smectites with cationic surfactant were characterized using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The results showed that the intercalation of surfactant cations was complete within 24h, 15min and 2min by conventional method, solid–solid reaction and microwaves irradiation, respectively. HDPy+t and HDTMA+ surfactants were retained by Zn++-illites/smectites suggesting important surface properties (CEC=80meq/100g clay, SBET =116.5m2/g) and developed acid–base properties (point of zero proton charge PZC, density charge σH). HDPy+ cation loading was effective suggesting that the aromatic polar group is favored for intercalation. Different configurations of surfactants within interlayer space of clay mineral were proposed based on the basal spacings which increased with surfactant loading. The presence of symmetrical and asymmetrical vibration bands of the –CH2 group in the IR spectrum of the modified illites/smectites and the variation of their frequencies and their intensities confirmed the results obtained by XRD.
      Graphical abstract image

      PubDate: 2015-08-25T18:39:15Z
       
  • Synergy between fillers in organomontmorillonite/graphene–PLA
           nanocomposites
    • Abstract: Publication date: November 2015
      Source:Applied Clay Science, Volumes 116–117
      Author(s): Boubkeur Seddik Bouakaz, Isabelle Pillin, Abderrahmane Habi, Yves Grohens
      Polylactic acid (PLA) nanocomposites filled with two organomontmorillonites (Cloisite® 15A and 30B), graphene functionalized epoxy (Gr) and montmorillonites–graphene mixtures were prepared via melt blending method. The main objective of this research was to study the synergetic effect of organically modified layered silicates with graphene when they are incorporated together into a PLA matrix. For this purpose, the rheological, morphological, barriers, and mechanical properties of elaborated materials were investigated. In contrast to binary composites containing different amounts of graphene (Gr–PLA), the addition of 3 phr of Cloisites® into Gr–PLA systems improved their elasticity and a secondary plateau was observed at the low frequencies in rheological measurements. Transmission electronic microscopy (TEM) images showed an enhancement of dispersion and exfoliation of two nanofillers (organomontmorillonite and graphene) in ternary nanocomposites attributed to a right combination of repulsive and attractive interactions between Cloisite® 15A-graphene and Cloisite® 30B-graphene systems, respectively. Dynamical Mechanical property (storage modulus) and water vapor permeability (WVP) were significantly improved by the microstructure development of materials; hence very interesting values of elastic modulus (G′) and WVP coefficient were obtained in the case of organomontmorillonite/graphene-PLA systems and particularly for Cloisite® 15A/graphene-PLA nanocomposites.
      Graphical abstract image

      PubDate: 2015-08-25T18:39:15Z
       
  • Plasma-surface modification on bentonite clay to improve the performance
           of adsorption of methylene blue
    • Abstract: Publication date: November 2015
      Source:Applied Clay Science, Volumes 116–117
      Author(s): Ömer Şahin, Mustafa Kaya, Cafer Saka
      The present study consists of the cold plasma treatment was applied for the surface modification of bentonite to improve the removal of methylene blue (MB) from aqueous solution. To achieve the aim, the conditions for adsorption, including cold plasma application time, plasma gas effect, and pH were investigated with respect to the adsorption capacity of MB. The changes of the surface property before and after cold plasma treatment were discussed. Cold plasma treated bentonite is characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR), BET surface area, and X-ray diffraction (XRD). Equilibrium adsorption data were analyzed by Freundlich and Langmuir equations. Langmuir isotherm exhibited the best fit with the experimental data. Adsorption kinetics were fitted with pseudo-first-order, and pseudo-second order. Cold plasma treated bentonite was exhibited largest adsorption capacity (303mg/g) at 30°C.


      PubDate: 2015-08-25T18:39:15Z
       
  • Editorial Board
    • Abstract: Publication date: September 2015
      Source:Applied Clay Science, Volume 114




      PubDate: 2015-08-21T18:35:10Z
       
  • Chemical modification of palygorskite with maleic anhydride modified
           polypropylene: Mechanical properties, morphology, and crystal structure of
           palygorskite/polypropylene nanocomposites
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): Jianjun Chen, Yang Yu, Jinyao Chen, Huilin Li, Junyi Ji, Daijun Liu
      Maleic anhydride modified polypropylene (PP) (PP-g-MAH) was chemically grafted onto palygorskite (Pal) via the bridge linking of [3-(2-aminoethyl)aminopropyl]trimethoxysilane (Z-6020) and PP-g-MAH in the presence of ultrasonic oscillation. The modified Pal was added to a PP matrix as a nano-filler to prepare Pal/PP nanocomposites by melt blending. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to discern that PP-g-MAH and Z-6020 were chemically grafted onto Pal via acrylation between NH2 and anhydride groups. The Pal/PP nanocomposites were characterized by Scanning electron microscopy, transmission electron microscopy and wide angle X-ray diffraction. The toughness and strength of PP could be improved markedly by the addition of modified Pal. The modified Pal was dispersed uniformly in the PP matrix in the form of individual crystal needles, which demonstrated the presence of strong interactions between the modified Pal and PP. The modified Pal could induce the formation of β-form PP crystals and promote the motion of PP chains during crystallization.
      Graphical abstract image

      PubDate: 2015-08-17T18:29:38Z
       
  • Dissolution behavior of Jordanian clay-rich materials in alkaline
           solutions for alkali activation purpose. Part I
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): Islam Aldabsheh, Hani Khoury, Jan Wastiels, Hubert Rahier
      In the framework of the search for non-traditional cements the dissolution behavior of three Jordanian clay-rich raw materials in alkaline solutions was investigated in different concentrations (2, 5 and 10M) using (NaOH and KOH) at 25°C. Different analytical techniques were used to characterize the raw materials mineralogically, chemically, thermally and structurally. The concentration of Si and Al was monitored using Atomic Absorption Spectroscopy (AAS) during dissolution. The solid residue was characterized using X-ray Diffraction (XRD), microscopic study, Scanning Electron Microscopy (SEM), Nuclear Magnetic Resonance Spectroscopy (NMR) and Thermo Gravimetric Analysis (TGA). The results indicate that the used materials, kaolinite, smectite-rich clay, and diatomaceous clay are to some degree soluble in concentrated alkaline solutions. The raw materials have a higher extent of dissolution with increasing concentration, time and temperature of dissolution. The extent of dissolution is somewhat higher in NaOH than in KOH solution. Si and Al dissolve congruently in the case of kaolinite. For the smectite rich clay Al dissolves faster while for diatomaceous rich clay Si dissolves faster. Characterization of solid residues of aluminosilicate materials revealed the formation of new phases of sodium aluminum silicate hydrate (SAS) and sodium aluminum carbonate silicate (SACS). This means that the conditions chosen do not purely evaluate the dissolution but that competition with precipitation needs to be taken into account. The studied Jordanian raw materials have a good potential to be used for alkali activation.
      Graphical abstract image

      PubDate: 2015-08-17T18:29:38Z
       
  • Preparation of metal sulfide mixtures in montmorillonite by
           solid–solid reactions
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): Jirabhorn Kabilaphat, Nithima Khaorapapong, Kanji Saito, Makoto Ogawa
      Novel hybrids composed of mixed metal sulfides (manganese sulfide and zinc sulfide (MnS/ZnS) or cadmium sulfide (MnS/CdS), as well as zinc sulfide and cadmium sulfide (ZnS/CdS)) with montmorillonite were synthesized by solid–solid reactions between the ion exchanged montmorillonite and sodium sulfide. The products were characterized by powder X-ray diffraction, transmission electron microscopy, as well as Raman, UV–visible and photoluminescence spectroscopies. The Raman spectra indicated the presence of manganese sulfide, zinc sulfide, and/or cadmium sulfide in the products. The absorption onsets observed at 318–366nm for MnS/ZnS@montmorillonite, at 330–521nm for MnS/CdS@montmorillonite, and at 360–480nm for ZnS/CdS@montmorillonite indicated the formation of two metal sulfides in the interlayer spaces. In comparison with those of bulk MnS (340nm), ZnS (360nm) and CdS (525nm), the absorption onsets owing to both metal sulfides were blue shifted probably due to quantum confinement effect, suggesting that the products are composed of nanometer sized sulfide particles. The photoluminescence bands owing to manganese sulfide (416 and 435nm), zinc sulfide (413 and 440nm), and cadmium sulfide (451 and 469nm) were also seen. The emission intensity of MnS/ZnS@montmorillonite was stronger than that of MnS/CdS@montmorillonite, probably due to the higher band gap energy of MnS/ZnS system that resulted in the increase of recombination of excitons.
      Graphical abstract image

      PubDate: 2015-08-17T18:29:38Z
       
  • Performance of ready-mixed clay plasters produced with different clay/sand
           ratios
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): Mehmet Emiroğlu, Ahmet Yalama, Yasemin Erdoğdu
      Recent studies have shown that the usage of earthen building materials such as adobe, rammed earth and clay plaster has increased due to their moisture balancing and breathing characteristics, availability of their raw materials, suitable costs, sustainability and environmentally friendly properties. Although making adobe and clay plaster is quite an old building application, nowadays, more durable clay plasters can be produced on the basis of quality control in the industrial sense. In the literature, there are many studies dealing with adobe and rammed earth materials. However, investigations covering the characteristics of clay plasters are limited. In this study, the performance of ready-mixed clay plasters was examined with regard to the moisture content of the samples during the test, the mixture content of the water and the clay/sand ratios. Compressive strength and shrinkage (volumetric and observational) of the clay plasters were considered as key parameters for the performance analysis. In addition, simple field tests, used for analysis of the composition of earth building materials, were carried out in order to evaluate the effect of the clay/sand ratio on the performance of the clay plasters. As a result, an increase in the initial water content of the mixture and/or the moisture content of the samples during the test had a negative effect on the compressive strength. Furthermore, the optimum clay/sand ratio was between 0.43 and 0.66 by weight when the shrinkage and compressive strength results were considered all together.


      PubDate: 2015-08-13T17:54:05Z
       
  • Kaolinite stabilized paraffin composite phase change materials for thermal
           energy storage
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): Chuanchang Li, Liangjie Fu, Jing Ouyang, Aidong Tang, Huaming Yang
      Three kinds of kaolinites (platelet, PKaol; layered, LKaol; and rod, RKaol) were used to stabilize paraffin to prepare PKaol/paraffin, LKaol/paraffin, and RKaol/paraffin composites. The effects of kaolinite microstructure on the thermal storage properties of the composites were investigated in detail. It was found that the crystallinity of the paraffin in the composites increased when the proportion of kaolinite pores that are smaller than 5nm decreased; the pore size also affected the transfer of the heat within the paraffin in the region near the kaolinite. The paraffin in LKaol/paraffin composite showed higher crystallinity (F c, 98.4%) and greater effective energy storage per unit mass (E ef, 215.6J·g−1) than that in the two other composites, indicating that most of the paraffin can contribute to energy storage. This is probably because the LKaol pore structure is more suitable for supporting phase change materials (PCM). This also led to less phonon scattering and therefore a larger phonon mean free path for paraffin in this composite, and a higher thermal conductivity (0.78W·m−1·K−1). Furthermore, the effect of nanopore confinement within the composites was elucidated at the atomic level. The as-prepared PCM have potential for application in solar thermal energy storage and solar heating.
      Graphical abstract image

      PubDate: 2015-08-13T17:54:05Z
       
  • From natural aluminosilicate minerals to zeolites: synthesis of ZSM-5 from
           rectorites activated via different methods
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): Haiyan Liu, Tong Shen, Wanwan Wang, Tiesen Li, Yuanyuan Yue, Xiaojun Bao
      The key to success in synthesizing zeolites from natural aluminosilicate minerals is the effective activation. This article presents an energy-saving and high-efficient method based on a submolten salt (SMS) system. Taking rectorite as an example, the effects of various activation methods on the reactivity of the resulting minerals were investigated. The results showed that after being thermally treated at 900°C, the rectorite was transformed into meta-rectorite consisting of distorted crystallized AlO6 and SiO4/AlO4 units; after being alkali-fused at 900°C, the crystallized SiO4 units were depolymerized into disilicates (Na2SiO3/Na2Si2O7) and monosilicates (Na4SiO4), and the AlO6/AlO4 units were converted into sodium aluminates (NaAlO2/Na2Al2O4); after being SMS-activated at 250°C, the SiO4 units were exclusively depolymerized into monosilicates, and the AlO6/AlO4 units were converted into NaAlO2 and/or Na2Al2O4. As a result, when taking the alkali-fused or SMS-activated minerals as the starting materials, pure-phase ZSM-5 zeolites were obtained.
      Graphical abstract image

      PubDate: 2015-08-13T17:54:05Z
       
  • Chemical activation of vermiculite to produce highly efficient material
           for Pb2+ and Cd2+ removal
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): F.S. Hashem, M.S. Amin, S.M.A. El-Gamal
      In this study vermiculite from Egypt was chemically activated by leaching with 0.5M HCl solution or by treatment with 30% H2O2 solution. SEM and X-ray results showed that leaching of vermiculite with HCl solution results in partial transformation of its ordered layer structure into delaminated structure while its treatment with H2O2 solution results in high separation and fragmentation of the layers with no structure change. The expansibility factor, k was measured on the base of the changes in the internal layer space of raw and activated vermiculite and it was found to be 2.5 and 14.83 for samples activated by HCl and H2O2, respectively. As indicated from DSC tests, the chemically activated vermiculite treated with Cd2+ or Pb2+ ions showed higher thermal stability than that of raw vermiculite treated with the same ions. The removal efficiency of peroxide activated vermiculite was higher than that of the acid activated vermiculite for both cadmium and lead ions.


      PubDate: 2015-08-13T17:54:05Z
       
  • Freeze–thaw resistance and chloride-ion penetration of
           cement-stabilized clay exposed to sulfate attack
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): Ali Mardani-Aghabaglou, İrem Kalıpcılar, Gözde İnan Sezer, Alper Sezer, Selim Altun
      It is well known that existence of sulfate in groundwater has adverse effects on strength and permeability of cement stabilized clay. On the other hand, freeze/thaw action also causes a reduction in strength and a subsequent increase in permeability of cement stabilized clay. However, a study concerning the coupled effects of these two phenomena is not encountered in the literature. Therefore, in this study, effects of sulfate attack and freeze–thaw action on strength and penetrability properties of cement stabilized kaolin were investigated within an experimental framework. The results revealed that the use of sulfate resistant cement is more feasible than the use of ordinary Portland cement, when cement stabilized clay is exposed to subsequent effects of freeze–thaw action and sulfate attack. Evidence from test results also proved that, irrespective of cement type, freeze–thaw resistance of cement stabilized clay specimens exposed to sulfate attack was lower than those of sulfate-free specimens. The results including the effects of cement inclusion level, sulfate salt type, curing period, and number of freeze–thaw cycles were presented in detail. Finally, empirical relationships among unconfined compressive strength, freeze–thaw cycles, cement content and curing period were established.


      PubDate: 2015-08-13T17:54:05Z
       
  • Effect of Mg-sericite flocculant for treatment of brewery wastewater
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): Hee-Jeong Choi
      The aim of this study was to investigate organic/inorganic matter removal using Mg-sericite flocculant in brewery wastewater. Mg-sericite flocculant successfully removed 98–100% of organic/inorganic substances in brewery wastewater at the following optimal Mg-sericite dosage: 30mg/L for turbidity and SS, 100mg/L for COD, 50mg/L for BOD, 30mg/L for TN and NH4-N and 20mg/L for TP and PO4-P. These results indicated that approximately 12.3mg/L, 11.0mg/L, 1.0mg/L, 0.5mg/L, 0.3mg/L and 0.4mg/L of COD, BOD, TN, NH4-N, TP and PO4-P were removed by 1mg/L Mg-sericite, respectively. The biopolymer, Mg-sericite, can be a promising flocculant due to its high efficiency and low dose requirements. In addition, Mg-sericite does not contaminate treated wastewater, which can be recycled to reduce not only the cost and the demand for water but also the extra operational costs for reusing brewery wastewater. This flocculation method can be used to reduce brewery wastewater treatment costs.


      PubDate: 2015-08-08T17:37:25Z
       
  • Structural effects of organobentonites on controlled release of
           pretilachlor
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): Junyong Mo, Lintao Dai, Libiao Chen, Yajing Wang, Aimin Huang, Lisheng Wang, Lin Ma
      To provide controlled release properties to the formulation containing pretilachlor, organobentonites with different loading levels of dodecyltrimethyl ammonium chloride (DTMA) and hexadecyltrimethyl ammonium chloride (HTMA) were prepared and used as carrier. The organobentonites were characterized by Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analysis, and the adsorption towards pretilachlor was investigated, to reveal the structural effects of organobentonites on the release of pretilachlor. Organobentonites with quaternary alkylammonium surfactant showed excellent adsorption capacity for pretilachlor and greatly reduced its release in water. On the basis of the parameter of an empirical equation used to fit the release data, the release of pretilachlor from organobentonites could be deduced to be predominated by Fickian diffusion mechanism. The time taken for 50% of active ingredient to be released, T 50, from DTMA-bentonite with surfactant loading of 60, 80, 100 and 120% of the cation exchange capacity was 12.9, 12.7, 18.5 and 26.7 times of that for the formulation without organobentonites and exhibited good linear relationship with the adsorption constant K f from the Freundlich equation. Similar results were obtained for HTMA-bentonite. Hydrophobic interaction played a key roll in the adsorption and sustained release of pretilachlor. An increasing loading level of quaternary alkylammonium surfactant on organobentonites generally led to an enhancement of the sustained release. The permeability of organobentonite also had an important impact on the diffusion of the herbicide. The extension of the alkyl chain of the quaternary ammonium surfactant resulted in an increased permeability of organobentonites and release of pretilachlor, owing to the increased basal spacing and lower surfactant packing density.
      Graphical abstract image

      PubDate: 2015-08-08T17:37:25Z
       
  • Preparation and characterization of hybrid materials consisting of
           high-energy ground montmorillonite and α-amino acids
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): Lukáš Petra, Peter Billik, Peter Komadel
      Two amino acids (l-cysteine and l-glutamic acid) were adsorbed on high-energy ground montmorillonite to prepare novel hybrid materials. The present minerals were analysed by X-ray diffraction (XRD) and C content was obtained. The amount of adsorbed glutamic acid was negligible in comparison to samples prepared by addition of cysteine. XRD assay showed the presence of cystine formed by oxidation of cysteine catalyzed probably by Fe(III) from the montmorillonite layers. Hybrid materials consisting of clay minerals and amino acids are promising biodegradable and nontoxic materials.
      Graphical abstract image

      PubDate: 2015-08-08T17:37:25Z
       
  • Elaboration and characterization of modified sepiolites and their humidity
           sensing features for environmental monitoring
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): Ahmed S. Afify, M. Hassan, M. Piumetti, I. Peter, B. Bonelli, J.-M. Tulliani
      After precipitation under basic conditions and subsequent thermal treatment, different oxide/hydroxide nanoparticles (based on W4+, Co2+, Cu2+, Gd3+, La3+, Mn2+, Nd3+, Sm3+, Sr2+, Y3+ and Zn2+) were formed onto sepiolite grains. Thermogravimetric–Differential Thermal Analysis (TG–DTA) combined with X-ray diffraction (XRD), nitrogen adsorption at −196°C, Field Emission-Scanning Electron Microscopy (FE-SEM), Diffuse Reflectance UV–visible (DR-UV–vis) spectroscopy and Infra-Red (IR) spectroscopy were used to study the particle size distribution, the morphology and the composition of the modified sepiolites. Humidity sensors were prepared in the form of pellets, where powders were uniaxially pressed and thermally treated at 550°C for 1h then, gold electrodes were screen-printed. Among the different studied compositions, tungsten-doped sepiolite exhibited a significant response towards relative humidity (RH) at room temperature starting from 40% RH.
      Graphical abstract image

      PubDate: 2015-08-08T17:37:25Z
       
  • Effects of the organic modification of different clay minerals and their
           application in biodegradable polymer nanocomposites of PHBV
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): Tales S. Daitx, Larissa N. Carli, Janaina S. Crespo, Raquel S. Mauler
      The aim of this work is to study the interactions of different nanoparticles modified with (3-aminopropyl)triethoxysilane (APTES) and to relate them with the morphology and the final properties of the PHBV nanocomposites. The compounds were prepared by melt processing in a twin screw extruder with 3mass% of nanoparticles and the resulting nanocomposites were physically and mechanically characterized to evaluate the effect of the different reactive groups available for interactions within the polymer matrix. The nanocomposites prepared with either the unmodified montmorillonite (Mt) or the modified (m-Mt) form presented similar or improved thermal and mechanical properties of the matrix, while those prepared with organically modified halloysite (m-Hal) presented a general decrease in the properties compared to neat PHBV. The differences between the properties can be attributed to the different interactions of the clay minerals with the modifier and with the polymer. In the m-Hal the amino groups are located at the edges and freely react with the carbonyl groups of the PHBV decreasing its molecular weight. In the m-Mt, these groups are confined to the clay mineral interlayer and thus the interactions with the polymer are nondestructive.
      Graphical abstract image

      PubDate: 2015-08-08T17:37:25Z
       
  • Preparation and characterization of novel clay/PLA nanocomposites
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): Rola Mansa, Chih-Te Huang, Ana Quintela, Fernando Rocha, Christian Detellier
      In this work, the preparation of a polylactide-nanocomposite material using, as a filler, the smectite-rich clay fraction of a Cenozoic formation in Bragança, Portugal, is introduced as a promising and cost-efficient approach to nanocomposite preparation. Nanocomposites of a mixed morphology were achieved, as confirmed via the visual observation of the dispersion and intercalation of the clay layers by TEM imaging; mostly analogous morphologies were achieved through the use of reference clay mineral, montmorillonite SWy-2, for the preparation of similar nanocomposites. With both sets of nanocomposites, TGA results indicated an enhanced thermal stability, as compared to neat PLA. In the case of the nanocomposites prepared using the clay fraction from Bragança, this effect was observed at temperatures at which 25% weight loss was observed. On the other hand, in the case of the SWy-2-based nanocomposites, the improved thermal stability effect was evident at higher temperatures, at which 50% weight loss took place. The complementary thermal stability effects provided by the two sets of nanocomposites prepared, combined with their comparable morphology, are promising results towards a feasible and contemporary approach to nanocomposite preparation, worthy of further research.


      PubDate: 2015-08-04T17:13:12Z
       
  • Characterization of clays from Mezafe and Mengono (Ne-Libreville, Gabon)
           for potential uses in fired products
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): J.E. Boulingui, C. Nkoumbou, D. Njoya, F. Thomas, J. Yvon
      Clay materials may contribute to promote the sustainable development of population accommodations in a developing country as Gabon. They are low cost versatile raw materials for the building industry. A mineral survey led to the discovery of clay occurrences along the highway Libreville-Cocoa-beach from Mezafe to Mengono (NE Libreville). These clays were characterized by chemical analyses, grain size distribution (sieving, sedimentometry and Fraunhofer laser light scattering), plasticity, X-ray diffraction on crude powder and oriented fine fractions (natural, glycolated or heated at 550°C), Fourier transform infrared spectroscopy, adsorption–desorption of nitrogen, cation exchange capacity, and scanning electron microscopy. Samples were fired from 900 to 1150°C and a few properties such as water absorption, linear shrinkage and bending strength were determined. Mineralogically, raw clay samples are made up mainly of quartz, kaolinite, illite and chlorite. Accessories are orthoclase, anatase, ilmenite, magnetite, goethite, lepidocrocite, Fe–Al sulfate, La–Ce rich crandallite or a mineral likely related to Ce-belovite, pyrite, Cu–Fe rich silicate, carbonates, bitumen and other organic matters. The decrease of SiO2 contents and the increase of Al2O3 contents of fractions under 125μm suggest the presence of large size quartz grains and fine kaolinite particles. The sum kaolinite+illite+chlorite increases from 25–42% in crude samples to 37–48% in clay fractions (135μm) with an increment rate of 15–40% at Mezafe and above 50% at Mengono. Thus, screening only can yield clay-rich raw materials similar to some European commercial kaolins. Results of firing from 900 to 1150°C show that water absorption, linear shrinkage and bending strength values are in the norm of tiles and fired earth. Only one sample's properties need to be enhanced for terra-cotta production.


      PubDate: 2015-08-04T17:13:12Z
       
  • Magnetic hydrotalcites as solid basic catalysts for cellulose hydrolysis
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): Sheng Xu, Meng-Chen Liao, Hong-Yan Zeng, Chao-Rong Chen, Heng-Zhi Duan, Xiao-Jun Liu, Jin-Ze Du
      Magnetic Mg–Fe–CO3 hydrotalcites (LDHs) with different Mg/Fe molar ratios were prepared and their microstructure and surface chemical properties were characterized. The particles were used to hydrolyze cellulose with β-1,4-glycosidic bonds. The catalytic activity relating to the electron–hole pairs, basicity, crystallinity and specific surface area depended on the Mg/Fe molar ratio. The LDH with Mg/Fe molar ratio of 3.0 (LDH-3) possessed the best crystallinity, the strongest ability to trap electrons, the highest basicity and specific surface area, exhibiting the highest catalytic activity in the cellulose hydrolysis. It could be because of the high crystallinity and basicity, especially plentiful strong basic sites, made the LDH-3 a strong ability to trap electrons leading to great affinity for β-1,4-glycosidic bonds of cellulose. The LDH-3 showed a maximum yield (46.5%) of soluble reducing sugars with high glucose selectivity (84.4%) at 150°C for 24h. Moreover, the solid catalyst could be easily separated and possibly reused.


      PubDate: 2015-08-04T17:13:12Z
       
  • Synthesis and characterisation of hydrotalcites produced by an aluminium
           hazardous waste: A comparison between the use of ammonia and the use of
           triethanolamine
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): R. Galindo, A. López-Delgado, I. Padilla, M. Yates
      Hydrotalcite-like compounds were co-precipitated with diluted sodium hydroxide from an unconventional aluminium source: the aluminium waste generated by the tertiary aluminium industry, with the assistance of ammonia and triethanolamine at pH10. These products were characterised by several techniques (XRD, FT-IR, UV–vis-NIR, SEM, DTA-TG and BET methods) to compare results. The characterisation of products confirmed significant differences depending on basic reagent selected. Products co-precipitated with ammonia showed less crystal growth, a more significant iron content in the structure and higher internal surface area. Products from triethanolamine showed the entry of organic molecules into the layered structure. These findings were important for the improvement of methods based on waste treatment, transforming an aluminium hazardous waste into a value added product as layered double hydroxides.
      Graphical abstract image

      PubDate: 2015-08-04T17:13:12Z
       
  • Factor space differentiation of brick clays according to mineral content:
           Prediction of final brick product quality
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): Milica Arsenović, Lato Pezo, Slavka Stanković, Zagorka Radojević
      Chemical composition and XRD qualitative analysis were used to calculate mineral contents of 139 brick clay raw materials using LPNORM. The second order polynomial models (SOP) for all the samples, which express the relation between mineral contents and the characteristics of fired laboratory products, did not fit to experimental data satisfactorily, due to low coefficients of determination (r2). In order to improve the models, the samples are divided into four groups in factor space (four quadrants), according to their mineral content similarity, using principal component analysis (PCA). Predictive models of compressive strength (CS), water absorption (WA), firing shrinkage (FS), weight loss during firing (WLF) and volume mass of cubes (VMC) are obtained for each of the groups. Second order polynomial (SOP) models are developed, and the influence of certain minerals to brick clay bricks quality within the groups is discussed. Developed models were able to predict the final quality of products in a wide range of mineral content and temperature treatment data, showing coefficient of determination (r 2) in range between 0.704–0.995. In order to estimate the adequacy of these models, the results were applied to the experimental data and compared according to additional statistical tests, so the next values are determined: coefficients of determination, reduced chi-square (χ2), mean bias error (MBE), mean percent error (MPE) and root mean square error (RMSE).


      PubDate: 2015-08-04T17:13:12Z
       
  • An improved method for determining the external specific surface area and
           the plasticity index of clayey samples based on a simplified method for
           non-swelling fine-grained soils
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): E. Garzón, P.J. Sánchez-Soto
      Previous studies have used the clay content of soils for estimating the specific surface areas and different correlations have been found, including plasticity-value correlations. Based on several assumptions, Dolinar (2012) proposed a simplified method for determining the external specific surface area of non-swelling fine-grained soils. An equation relates the external specific surface area (BET-nitrogen) with percentage of clay fraction (<2μm), determined by hydrometer method, and plasticity index (Atterberg). In this work, based on that simplified method, the authors have developed an improved method for determining the external specific surface area of fine-grained clay samples. Instead of percentage of clay fraction, it was proposed to use the clay mineral content estimated by XRD methods. From an analysis of previous Dolinars results, the calculated and measured values of external specific surface area were studied for a group of non-swelling and fine-grained soil samples (Dolinar's samples), five non-swelling clayey samples and data samples from the literature. Additionally, an estimation of the plasticity index (Atterberg) has been also considered in this improved method. Both these methods, simplified and improved, were tested and compared using all these samples. It demonstrated the practical application of both these methods for an estimation of external specific surface area and plasticity index. However, in the present research two models were considered to determine the specific surface areas (BET and Langmuir) and the influence of several sources of errors in these predictions was discussed. The predictions were found more accurate when specific surface area from Langmuir's model is considered. It is concluded that the present research will be useful for the prediction of external specific surface area and plasticity index of non-swelling clayey materials and to dispose of theoretical practical relationships between clay mineralogy and geotechnical properties of valuable interest.


      PubDate: 2015-08-04T17:13:12Z
       
  • Microstructural evolution, phase transformation, and variations in
           physical properties of coal series kaolin powder compact during firing
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): Xiaohong Xu, Xinbin Lao, Jianfeng Wu, Yaxiang Zhang, Xiaoyang Xu, Kun Li
      Coal series kaolin (CSK) from coalmine in Shanxi, China was studied in the form of powder compact by using die-pressing technique. Mineralogical, morphological, and chemical characteristics of CSK were given. The microstructural evolution, phase transformation, and relevant variations in physical properties of the fired CSK with elevating temperature were investigated. Results indicated that mullite began to form at the temperature as low as 1002.8°C. Columnar mullite appeared when firing at 1500°C. Transformation of cristobalite to liquid phase favored the densification of the fired powder compacts and made them acquire the densest microstructure in 1580–1600°C temperature interval. Die-pressing technique and flake-like nature of CSK particle induced the interlocking texture on the plane perpendicular to die-pressing direction. Low content of impurities as TiO2 and Fe2O3 increased the formation temperature of the columnar mullite and endowed samples with high refractoriness (as high as 1600°C). The advantages of using CSK for industrial ceramic preparation are its high purity, low mullitization temperature, and high refractoriness.


      PubDate: 2015-07-28T20:48:25Z
       
  • Estimation of material and interfacial/interphase properties in
           clay/polymer nanocomposites by yield strength data
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): Yasser Zare
      In this article, a new and simple approach is presented for calculation of material and interfacial/interphase properties in clay/polymer nanocomposites (CPN) by the experimental results of yield strength. The “B” interaction parameter from Pukanszky model is correlated with several material and interfacial/interphase characteristics such as yield strength of polymer matrix (σm), the aspect ratio of clay (α), the stress transfer parameter (s), thickness (ti) and strength (σi) of interphase. The suggested equations are applied to calculate and examine the material and interfacial/interphase properties for several samples of CPN. Also, the effects of all parameters on “σi” and “ti” are determined to predict the relations between material and interfacial/interphase properties. According to the suggested equations, low “B” and high “ti” produced insignificant “σi” in CPN. Furthermore, a thick interphase caused a large stress transfer from polymer matrix to clay at interphase region.


      PubDate: 2015-07-27T22:36:08Z
       
  • Fe2O3–palygorskite nanoparticles, efficient adsorbates for pesticide
           removal
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): Affaf Ouali, Lala Setti Belaroui, Abdelkader Bengueddach, Alberto Lopez Galindo, Aránzazu Peña
      Recently, magnetic adsorbents have aroused a significant attention because of their excellent adsorption capacity. An Algerian palygorskite/magnetic iron oxide was prepared by chemical co-precipitation and characterized using infrared spectroscopy, X-ray diffraction and X-ray fluorescence. The results prove the formation of a red brick powder, with magnetic character, showing a high percentage of iron oxide on palygorskite. To verify the ability of the magnetic palygorskite for retaining organic pollutants, three different samples were evaluated for the adsorption of the fungicide fenarimol from aqueous samples: sifted palygorskite, purified palygorskite and Fe2O3/palygorskite. The effects of different variables were assessed: adsorbent mass, reaction time, initial pesticide concentration and desorption stability. Fenarimol adsorption kinetics followed a pseudo-second order model. The adsorption rates were 11%, 50% and 70%, for sifted, purified and Fe2O3/palygorskite, respectively. Both Langmuir and Freundlich models could be used to describe fenarimol adsorption on sifted and purified palygorskites. However only the Freundlich model could fit the adsorption data on Fe2O3/palygorskite, probably due to the adsorbent heterogeneity. Stability of fenarimol desorption from the three samples, where the fungicide had been previously preadsorbed, showed that the extent of desorbed fenarimol from Fe2O3/palygorskite remained constant along the studied period (15days).


      PubDate: 2015-07-27T22:36:08Z
       
  • Effect of metakaolin addition and seawater mixing on the properties and
           hydration of concrete
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): Qiu Li, Haining Geng, Zhonghe Shui, Yun Huang
      The effect of metakaolin (MK) and seawater mixing on the properties and hydration products of concrete was studied by analytical techniques. MK improved compressive strength by refining pore structure without altering porosity. Seawater increased compressive strength at early age without altering pore structure. The combination of MK and seawater improved both early and later age strength. Hydration products in pastes containing MK were Portlandite, ettringite, hemicarboaluminate, monocarboaluminate and C-S-H gels. In pastes with seawater, instead of hemicarboaluminate and monocarboaluminate, hydrocalumite was identified. MK promoted hydrocalumite formation. MK decreased CH content with increase of MK content and age. Seawater increased CH content at early age with MK content. The combination increased CH content at early age and decreased later. At 28days, most chloride in seawater was immobilized by hydrocalumite. The combination improved properties of concrete at both early and later age.


      PubDate: 2015-07-27T22:36:08Z
       
  • Preparation and characterization of novel composite AlCr-pillared clays
           and preliminary investigation for benzene adsorption
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): Menglin Ding, Shufeng Zuo, Chenze Qi
      In this study, a one-step high-temperature and high-pressure method was used to synthesize AlCr composite pillaring agents. Compared to conventional methods, the method greatly reduced the steps and material consumption. A series of composite AlCr-pillared clays (AlCr-PILC) were synthesized by ion exchange. The structure of the AlCr composite pillaring agent could be altered by changing the Al/Cr molar ratio, reaction temperature, and reaction time, thereby affecting the structure and properties of AlCr-PILC (including surface area, pore volume, pore diameter, and basal spacing). The structure and properties of the experimental materials were characterized by X-ray diffraction, N2 adsorption, high-resolution electron microscopy, and benzene adsorption and desorption experiments. The results indicated that after 4h of calcination at 550°C, the specific surface area, pore volume, and maximum basal spacing of AlCr-PILC reached 266–362m2/g, 0.16–0.22cm3/g, and 2.06nm, respectively. The benzene adsorption capacity of the synthesized AlCr-PILC was much larger than the capacity of the starting clays, reaching 48.3μmol/g. In addition, complete desorption could be achieved at 250°C. Therefore, the synthesized AlCr-PILC was a good material for adsorption.
      Graphical abstract image

      PubDate: 2015-07-23T22:22:40Z
       
  • Susceptibility of strength development by lime in gypsiferous soil—A
           micro mechanistic study
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): Arvind Kumar Jha, P.V. Sivapullaiah
      The role of gypsum on the strength of lime treated soils after a long period of interaction is not well understood yet. The present study is performed to scrutinize the physical and strength behavior of lime treated soil with varying gypsum content. Lime and gypsum contents varying from 0 to 6% are considered in the present study for curing periods up to 28days. To understand the long-term effects, the work has been extended up to 365days, particularly with the use of 6% lime content and varying gypsum contents. Atterberg's limits turned out to be marginally affected by cation exchange. Unconfined compressive strength behavior of lime treated soil varies considerably with gypsum content and curing period. However, trivial alteration in strength is observed in the soil treated with lower lime content (up to 4%) and gypsum content up to 6%. On the contrary, strength of soil–6% lime mixture with addition of varying gypsum content shows acceleration in early strength at 14days curing period. However, the strength at 28days of curing declines but regains afterwards for 90days. The trend at longer curing period for 180 and 365days is, however, not unique but varies with gypsum contents. An attempt has been made to explain these changes on the basis of the form of gypsum, formation and conversion of reacted compounds (CASHH, CASH, CSH and Ettringite). The proposed explanations were supported by detailed characterization through thermal analysis, XRD, SEM and EDAX studies of soil–lime–gypsum mixtures.


      PubDate: 2015-07-23T22:22:40Z
       
  • Composition, firing behavior and ceramic properties of the Sejnène
           clays (Northwest Tunisia)
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): A. Bennour, S. Mahmoudi, E. Srasra, S. Boussen, N. Htira
      This study focuses on the results of various analyses and ceramic aptitude tests carried out on two representative clay samples of the Oligo-Miocene from Sejnène, in Northwest Tunisia. The original clays were characterized by chemical analysis, powder X-ray diffraction (XRD), TGA measurements, infrared spectroscopy, Bigot curves and evaluation of the plasticity. The mineralogical study proved that these clays are mainly composed of kaolinite and illite, with a small amount of interstratified I/S. The chemical analysis indicated that the clays of ClaySej1 are more siliceous than those of ClaySej2, which have higher levels of elemental fluxes (Fe2O3, Na2O, K2O and CaO). The mineralogical metamorphoses during the firing process were recorded via the X-ray diffraction of the raw clays and subsequent firing at 300, 600, 800, 1000 and 1200°C for 3h with a heating rate of 10°C/min. The main transformations were observed at 1000°C with the appearance of new crystalline phases especially in the ClaySej2 sample. The samples were hand-pressed in a rectangular mold and sintered at 950, 1050 and 1100°C with a heating rate of 10°C/min. The variations in flexural strength, linear shrinkage, water absorption and color were also determined and showed sensitivity to the chemical and mineralogical compositions.


      PubDate: 2015-07-23T22:22:40Z
       
  • Saponites containing divalent transition metal cations in octahedral
           positions — Exploration of synthesis possibilities using microwave
           radiation and NMR characterization
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): R. Trujillano, E. Rico, M.A. Vicente, V. Rives, I. Sobrados, J. Sanz
      The synthesis using microwave radiation of saponites containing Co2+, Zn2+ or Cu2+ in octahedral positions has been explored (in the case of Cu2+, together with Mg2+ or Ni2+). Pure saponite phases were formed under some synthesis conditions, although in other cases some impurities were also formed. Microwave treatment at 180°C favored the formation of ordered solids, but induced the crystallization of other phases in some cases. Cu2+-containing saponites were formed only if Mg2+ or Ni2+ were used as octahedral sheet co-cations. The solids were characterized by different techniques, including MAS-NMR spectroscopy, which gave very precise information in the case of Zn-saponite, allowing us to estimate the content of tetrahedral Al, but much more undefined information for samples with paramagnetic cations. Nevertheless, the presence of tetrahedral Fe3+ and octahedral Fe2+ species was evidenced. Cu2+ slightly perturbed the NMR signals, while Co2+ strongly perturbed 27Al, 23Na and especially 29Si NMR spectral signals.
      Graphical abstract image

      PubDate: 2015-07-23T22:22:40Z
       
  • Layered clay aqueous dispersion as a novel dye leveling agent in leather
           processing: Synthesis, characterization and application studies
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): Sujata Mandal, S. Natarajan, S. Suresh, R. Chandrasekar, G. Jothi, C. Muralidharan, Asit Baran Mandal
      Dyeing is an important process step of leather manufacture that is performed to obtain intended final color. Intensity variation and inconsistency in color characteristics among leathers processed in a batch are major concerns of tanners. Variations in final leather color result in either rework or rejection of leather leading to significant productivity and economic loss. Moreover, to produce certain natural-look leather products, uniform dyeing of the entire leather surface and color uniformity of the leathers among each batch are an absolute necessity. In this study, an aqueous dispersion of layered double hydroxide (LDH) has been synthesized and used as dye leveling agent in leather dyeing operation to enhance the shade intensity of the leather and color uniformity among different pieces of leathers. The physico-chemical characteristics of the LDH dispersion in water and its efficacy towards achieving the objective have been studied. Leathers processed using the aqueous dispersion of LDH showed excellent color uniformity and consistency with no detrimental effect on color fastness characteristics of the leather.
      Graphical abstract image

      PubDate: 2015-07-23T22:22:40Z
       
  • Mineralogical analysis of ceramic tiles by FTIR: A quantitative attempt
    • Abstract: Publication date: October 2015
      Source:Applied Clay Science, Volume 115
      Author(s): J.D. Jordá, M.M. Jordán, R. Ibanco-Cañete, M.A. Montero, J.A. Reyes-Labarta, A. Sánchez, M. Cerdán
      A method for quantitative mineralogical analysis by ATR-FTIR has been developed. The method relies on the use of the main band of calcite as a reference for the normalization of the IR spectrum of a mineral sample. In this way, the molar absorptivity coefficient in the Lambert–Beer law and the components of a mixture in mole percentage can be calculated. The GAMS equation modeling environment and the NLP solver CONOPT (©ARKI Consulting and Development) were used to correlate the experimental data in the samples considered. Mixtures of different minerals and gypsum were used in order to measure the minimum band intensity that must be considered for calculations and the detection limit. Accordingly, bands of intensity lower than 0.01 were discarded. The detection limit for gypsum was about 7% (mol/total mole). Good agreement was obtained when this FTIR method was applied to ceramic tiles previously analyzed by X-ray diffraction (XRD) or mineral mixtures prepared in the lab.


      PubDate: 2015-07-19T22:08:37Z
       
  • Fluorescence tuning of 2D montmorillonite optically active layers with
           beta-cyclodextrine/dye supramolecular complexes
    • Abstract: Publication date: September 2015
      Source:Applied Clay Science, Volume 114
      Author(s): Marián Matejdes , Adriana Czímerová , Marián Janek
      Montmorillonite 2D-optically active layers were investigated using non-ionic Coumarine and cationic Pyronine dyes. The modification of thin montmorillonite films (MF) was done by single dye species and/or with β-cyclodextrine (CD) supramolecular complexes (SC). Equilibrium constants for SC formation were determined in the range 0.1·103 −6.0·103 for temperatures 283–323K. Thus amounts of dye incorporated in the SC with CD prepared at temperature 293K is more than 96% for Coumarine and more than 81% for Pyronine dye. Adsorption of SC in MF was proved by detection of increased first basal reflections using X-ray diffraction. The molecular transition moments for monomeric dye species in 2D MF of SC for Pyronine absorbing at 560nm were inclined 60° and co-adsorbed dimers or higher aggregates of molecules tilted around 33° towards montmorillonite surface. Coumarine absorption in the whole investigated spectral range indicated average molecule inclination around 28°. The angle of the Coumarine dye is favourable for the formation of J-aggregates with sufficient fluorescence intensity detected at 478nm for solid state applications.
      Graphical abstract image

      PubDate: 2015-07-02T09:43:56Z
       
  • Clay and clay minerals for fluoride removal from water: A state-of-the-art
           review
    • Abstract: Publication date: September 2015
      Source:Applied Clay Science, Volume 114
      Author(s): A. Vinati , B. Mahanty , S.K. Behera
      The presence of fluoride in water has become a matter of great concern around the world due to its chronic human carcinogenic behavior. Developing easily accessible and environmentally sustainable removal strategies is therefore a challenge for the scientists. Among the different treatment technologies, adsorption process for fluoride removal is considered cost-effective, flexible, and easy to design and operate. This review discusses the recent trends in scientific research and development on the exploitation of clay and clay minerals for fluoride removal from water, focusing on the effect of various factors on the adsorption, mechanism, isotherms and kinetics of the adsorption process.
      Graphical abstract image

      PubDate: 2015-07-02T09:43:56Z
       
  • Room temperature and high temperature sealing properties and compression
           properties of compressive gaskets made of micrometric vermiculite
           particles
    • Abstract: Publication date: September 2015
      Source:Applied Clay Science, Volume 114
      Author(s): A.N. Nguyen , L. Mirabel , L. Duclaux , L. Reinert , P. Dehaudt , J.F. Juliaa , A. Beziat
      Vermiculite gaskets obtained by pressing vermiculite powders in the range of 17.7–80MPa, were studied for their sealing (leak rate measurements) and compressive properties (compressibility and resiliency). The in plane permeability at room temperature was found to decrease strongly through increasing elaboration pressure, that reduced both the median pore radius (<30nm) and the macropore volume fraction (<45%), measured by mercury intrusion. After annealing at temperatures of up to 600°C, the out of plane permeability (measured at room temperature) was increasing from ~10−20 (at 200°C) to ~10−24 due to the increase in anisotropy related to the densification and the formation of interlayer bonds. The global leak rate was found to be determined exclusively by the contact leak rate and independent of the material's permeability. The leak rates measured at room temperature were also found to be dependent on the gasket's resiliency values. The global helium leak rate (2.5×10−2 atm·cm3·s−1·m−1, for 35MPa working pressure, under 5bar helium pressure) was relied neither on the working temperature (25°C to 800°C) nor the material porosity for gaskets pressed at 200°C and 80MPa. The resiliency (~5%) and compressibility (9%) values of these gaskets were reduced, as heating the materials to 800°C due to the densification induced by both pressure and temperature, increasing their rigidity.
      Graphical abstract image

      PubDate: 2015-07-02T09:43:56Z
       
 
 
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