for Journals by Title or ISSN
for Articles by Keywords
help
  Subjects -> ENGINEERING (Total: 2279 journals)
    - CHEMICAL ENGINEERING (191 journals)
    - CIVIL ENGINEERING (185 journals)
    - ELECTRICAL ENGINEERING (101 journals)
    - ENGINEERING (1203 journals)
    - ENGINEERING MECHANICS AND MATERIALS (390 journals)
    - HYDRAULIC ENGINEERING (55 journals)
    - INDUSTRIAL ENGINEERING (65 journals)
    - MECHANICAL ENGINEERING (89 journals)

ENGINEERING (1203 journals)                  1 2 3 4 5 6 7 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 7)
3D Research     Hybrid Journal   (Followers: 19)
AAPG Bulletin     Full-text available via subscription   (Followers: 5)
AASRI Procedia     Open Access   (Followers: 15)
Abstract and Applied Analysis     Open Access   (Followers: 3)
Aceh International Journal of Science and Technology     Open Access   (Followers: 2)
ACS Nano     Full-text available via subscription   (Followers: 222)
Acta Geotechnica     Hybrid Journal   (Followers: 7)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 2)
Acta Scientiarum. Technology     Open Access   (Followers: 3)
Acta Universitatis Cibiniensis. Technical Series     Open Access  
Active and Passive Electronic Components     Open Access   (Followers: 7)
Adaptive Behavior     Hybrid Journal   (Followers: 11)
Adıyaman Üniversitesi Mühendislik Bilimleri Dergisi     Open Access  
Adsorption     Hybrid Journal   (Followers: 4)
Advanced Engineering Forum     Full-text available via subscription   (Followers: 6)
Advanced Science     Open Access   (Followers: 4)
Advanced Science Focus     Free   (Followers: 3)
Advanced Science Letters     Full-text available via subscription   (Followers: 5)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 7)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 17)
Advances in Artificial Neural Systems     Open Access   (Followers: 4)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5)
Advances in Complex Systems     Hybrid Journal   (Followers: 7)
Advances in Engineering Software     Hybrid Journal   (Followers: 25)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 14)
Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 10)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 20)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 24)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 9)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 28)
Advances in Operations Research     Open Access   (Followers: 11)
Advances in OptoElectronics     Open Access   (Followers: 5)
Advances in Physics Theories and Applications     Open Access   (Followers: 12)
Advances in Polymer Science     Hybrid Journal   (Followers: 40)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Remote Sensing     Open Access   (Followers: 37)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aerobiologia     Hybrid Journal   (Followers: 1)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 4)
AIChE Journal     Hybrid Journal   (Followers: 29)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access  
Alexandria Engineering Journal     Open Access   (Followers: 1)
AMB Express     Open Access   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 28)
American Journal of Engineering and Applied Sciences     Open Access   (Followers: 11)
American Journal of Engineering Education     Open Access   (Followers: 9)
American Journal of Environmental Engineering     Open Access   (Followers: 16)
American Journal of Industrial and Business Management     Open Access   (Followers: 23)
Analele Universitatii Ovidius Constanta - Seria Chimie     Open Access  
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of Regional Science     Hybrid Journal   (Followers: 7)
Annals of Science     Hybrid Journal   (Followers: 7)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applicable Analysis: An International Journal     Hybrid Journal   (Followers: 1)
Applied Catalysis A: General     Hybrid Journal   (Followers: 6)
Applied Catalysis B: Environmental     Hybrid Journal   (Followers: 8)
Applied Clay Science     Hybrid Journal   (Followers: 4)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 3)
Applied Nanoscience     Open Access   (Followers: 7)
Applied Network Science     Open Access  
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Physics Research     Open Access   (Followers: 3)
Applied Sciences     Open Access   (Followers: 2)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 4)
Arabian Journal for Science and Engineering     Hybrid Journal   (Followers: 5)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 4)
Archives of Foundry Engineering     Open Access  
Archives of Thermodynamics     Open Access   (Followers: 7)
Arid Zone Journal of Engineering, Technology and Environment     Open Access  
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
ASEE Prism     Full-text available via subscription   (Followers: 3)
Asian Engineering Review     Open Access  
Asian Journal of Applied Science and Engineering     Open Access   (Followers: 1)
Asian Journal of Applied Sciences     Open Access   (Followers: 2)
Asian Journal of Biotechnology     Open Access   (Followers: 8)
Asian Journal of Control     Hybrid Journal  
Asian Journal of Current Engineering & Maths     Open Access  
Asian Journal of Technology Innovation     Hybrid Journal   (Followers: 8)
Assembly Automation     Hybrid Journal   (Followers: 2)
at - Automatisierungstechnik     Hybrid Journal   (Followers: 1)
ATZagenda     Hybrid Journal  
ATZextra worldwide     Hybrid Journal  
Australasian Physical & Engineering Sciences in Medicine     Hybrid Journal   (Followers: 1)
Australian Journal of Multi-Disciplinary Engineering     Full-text available via subscription   (Followers: 2)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 8)
Avances en Ciencias e Ingeniería     Open Access  
Balkan Region Conference on Engineering and Business Education     Open Access   (Followers: 1)
Bangladesh Journal of Scientific and Industrial Research     Open Access  
Basin Research     Hybrid Journal   (Followers: 3)
Batteries     Open Access   (Followers: 4)
Bautechnik     Hybrid Journal   (Followers: 1)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 23)
Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 3)
BER : Manufacturing Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Motor Trade Survey     Full-text available via subscription   (Followers: 1)
BER : Retail Sector Survey     Full-text available via subscription   (Followers: 2)
BER : Retail Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Survey of Business Conditions in Manufacturing : An Executive Summary     Full-text available via subscription   (Followers: 3)
BER : Survey of Business Conditions in Retail : An Executive Summary     Full-text available via subscription   (Followers: 3)
Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access   (Followers: 1)
Biofuels Engineering     Open Access  
Biointerphases     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 9)
Biomedical Engineering     Hybrid Journal   (Followers: 16)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 13)
Biomedical Engineering Letters     Hybrid Journal   (Followers: 5)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 17)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 32)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 8)
Biomedical Science and Engineering     Open Access   (Followers: 3)
Biomedizinische Technik - Biomedical Engineering     Hybrid Journal  
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Hybrid Journal   (Followers: 2)
Biotechnology Progress     Hybrid Journal   (Followers: 39)
Boletin Cientifico Tecnico INIMET     Open Access  
Botswana Journal of Technology     Full-text available via subscription  
Boundary Value Problems     Open Access   (Followers: 1)
Brazilian Journal of Science and Technology     Open Access   (Followers: 2)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 10)
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 14)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 3)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Hybrid Journal   (Followers: 14)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 41)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 7)
Case Studies in Thermal Engineering     Open Access   (Followers: 3)
Catalysis Communications     Hybrid Journal   (Followers: 6)
Catalysis Letters     Hybrid Journal   (Followers: 2)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 6)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysis Today     Hybrid Journal   (Followers: 5)
CEAS Space Journal     Hybrid Journal  
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 3)
Central European Journal of Engineering     Hybrid Journal   (Followers: 1)
CFD Letters     Open Access   (Followers: 6)
Chaos : An Interdisciplinary Journal of Nonlinear Science     Hybrid Journal   (Followers: 2)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
Chinese Journal of Engineering     Open Access   (Followers: 2)
Chinese Science Bulletin     Open Access   (Followers: 1)
Ciencia e Ingenieria Neogranadina     Open Access  
Ciencia en su PC     Open Access   (Followers: 1)
Ciencias Holguin     Open Access   (Followers: 1)
CienciaUAT     Open Access  
Cientifica     Open Access  
CIRP Annals - Manufacturing Technology     Full-text available via subscription   (Followers: 11)
CIRP Journal of Manufacturing Science and Technology     Full-text available via subscription   (Followers: 14)
City, Culture and Society     Hybrid Journal   (Followers: 21)
Clay Minerals     Full-text available via subscription   (Followers: 9)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
Coal Science and Technology     Full-text available via subscription   (Followers: 3)
Coastal Engineering     Hybrid Journal   (Followers: 11)
Coastal Engineering Journal     Hybrid Journal   (Followers: 4)
Coatings     Open Access   (Followers: 3)
Cogent Engineering     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 4)
Color Research & Application     Hybrid Journal   (Followers: 1)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 13)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 13)
Communications Engineer     Hybrid Journal   (Followers: 1)
Communications in Numerical Methods in Engineering     Hybrid Journal   (Followers: 2)
Components, Packaging and Manufacturing Technology, IEEE Transactions on     Hybrid Journal   (Followers: 25)
Composite Interfaces     Hybrid Journal   (Followers: 6)
Composite Structures     Hybrid Journal   (Followers: 255)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 179)
Composites Part B : Engineering     Hybrid Journal   (Followers: 227)
Composites Science and Technology     Hybrid Journal   (Followers: 169)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access  
Computational Geosciences     Hybrid Journal   (Followers: 13)
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
Computational Science and Discovery     Full-text available via subscription   (Followers: 2)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 6)
Computer Science and Engineering     Open Access   (Followers: 17)
Computers & Geosciences     Hybrid Journal   (Followers: 28)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 5)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 4)
Computers and Geotechnics     Hybrid Journal   (Followers: 10)
Computing and Visualization in Science     Hybrid Journal   (Followers: 5)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 29)
Conciencia Tecnologica     Open Access  
Concurrent Engineering     Hybrid Journal   (Followers: 3)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 6)
Control and Dynamic Systems     Full-text available via subscription   (Followers: 8)
Control Engineering Practice     Hybrid Journal   (Followers: 41)
Control Theory and Informatics     Open Access   (Followers: 7)
Corrosion Science     Hybrid Journal   (Followers: 25)
CT&F Ciencia, Tecnologia y Futuro     Open Access  

        1 2 3 4 5 6 7 | Last

Journal Cover Applied Clay Science
  [SJR: 0.826]   [H-I: 83]   [4 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0169-1317
   Published by Elsevier Homepage  [3034 journals]
  • Bentonites functionalized by impregnation with TiO2, Ag, Pd and Au
           nanoparticles
    • Authors: Tatiane de Mattos Amadio; Dachamir Hotza; João Batista Rodrigues Neto; Magda Blosi; Anna Luisa Costa; Michele Dondi
      Pages: 1 - 6
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): Tatiane de Mattos Amadio, Dachamir Hotza, João Batista Rodrigues Neto, Magda Blosi, Anna Luisa Costa, Michele Dondi
      This work aimed to characterize bentonites with different features and origins (Brazil, Argentina, Italy and United States) that were impregnated with Ag, TiO2, Pd and Au nanoparticles. Either commercial (TiO2) or synthesized (Ag, Pd and Au) nanoparticles (NP) were used and characterized by DLS and XRD. Subsequently, the dispersed NP was impregnated on bentonite by two alternative methods, imbibition or dipping. The efficiency of impregnation of bentonite by metallic nanoparticles was finally tested by ICP-OES, which was over 90% in all cases. Particularly, Ag nanoparticles showed an impregnation efficiency above 99%, as confirmed by SEM-FEG. To improve impregnation, a thermal pretreatment for the bentonites was necessary at 700°C. Both impregnation methods resulted in a suitable distribution and stability of Ag nanoparticles.

      PubDate: 2017-06-01T16:08:31Z
      DOI: 10.1016/j.clay.2017.05.028
      Issue No: Vol. 146 (2017)
       
  • Lauric acid/modified sepiolite composite as a form-stable phase change
           material for thermal energy storage
    • Authors: Qiang Shen; Jing Ouyang; Yi Zhang; Huaming Yang
      Pages: 14 - 22
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): Qiang Shen, Jing Ouyang, Yi Zhang, Huaming Yang
      A series of novel composite phase change materials (PCMs) were prepared by impregnating lauric acid (LA) into the chemically modified sepiolite (SEP) via a vacuum impregnation method. Modification strategy was developed to improve the adsorption capacity of SEP, and the effects of thermal and chemical modification on the physical and chemical properties of SEP were investigated. The loading of LA inside the acid treated SEP could reach up to 60wt%, which was 50% higher than that of pristine SEP. The corresponding latent heats of the composite PCMs exhibited 125.2J/g at the melting temperatures of 42.5°C and 113.9J/g at the freezing temperatures of 41.3°C, respectively. The increased latent heat could be attributed to the better microstructure of the modified SEP. The thermal conductivity (0.59W/(m·k)) of the composite PCMs was higher than that of LA. The composite PCMs presented chemical and thermal reliability after 200 thermal cycling tests. The form-stable composite PCMs could be the promising candidate material for thermal energy storage.
      Graphical abstract image

      PubDate: 2017-06-01T16:08:31Z
      DOI: 10.1016/j.clay.2017.05.035
      Issue No: Vol. 146 (2017)
       
  • Magnesium oxide as alternative binder for unfired clay bricks
           manufacturing
    • Authors: Sandra Espuelas; Joshua Omer; Sara Marcelino; Angel Maria Echeverría; Andres Seco
      Pages: 23 - 26
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): Sandra Espuelas, Joshua Omer, Sara Marcelino, Angel Maria Echeverría, Andres Seco
      Replacement of fired bricks by unfired ones could be an effective way to reduce the building industry environmental footprint: Their manufacture not only requires less energy and natural resources but also generates less waste. Bricks are based on the use of an additive cementitious material in the form of a binder, usually lime or cement. Such additives have a great environmental impact owing to the high energy consumption and CO2 during in their manufacturing process. In this article experiments are carried out in order to investigate the applicability of a MgO rich industry by-product as a binder for the production of unfired clay bricks. From the experiments, the MgO was observed to show ability to enhance the mechanical properties of a clay brick in much the same way as lime does. Water absorption tests on bricks revealed the superiority of MgO over lime in enhancing the durability properties of unfired bricks. The laboratory results demonstrate the high potential of MgO based additives as alternative binders to the calcium based ones. Consequently, this offers opportunity for reducing the environmental impact associated with the use of fired clay bricks. In addition, it could allow an effective way for the valorization of MgO containing industry by-products that currently discarded to landfills.

      PubDate: 2017-06-01T16:08:31Z
      DOI: 10.1016/j.clay.2017.05.034
      Issue No: Vol. 146 (2017)
       
  • Contribution of nanoclay to the additive partitioning in polymers
    • Authors: Aida Nasiri; Nathalie Gontard; Emmanuelle Gastaldi; Stéphane Peyron
      Pages: 27 - 34
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): Aida Nasiri, Nathalie Gontard, Emmanuelle Gastaldi, Stéphane Peyron
      The polymer nanocomposites have become unabatedly popular due to their exceptional properties which results in a plethora of applications including the food packaging. However, safety aspect of these materials is still under debate, specifically in view point of the unknown interactions of nanoparticles with various additives added during the packages processing. For the commonly used polyolefins, the partitioning of additives rather than their diffusivity dictates the extant and extent of these interactions. In this work, the partitioning of various additives between a clay-polymer nanocomposite (CPN) and several food simulants was measured based on a worst-case scenario in viewpoint of the selected polymer and additives. The added value of the CPN in comparison with the pure polymer (LLDPE) was analyzed with regards to their Hansen solubility parameters and log K-log P linearity. Ultimately, an estimation method based on the Flory-Huggins theory was proposed to predict the partition coefficients in CPN.
      Graphical abstract image

      PubDate: 2017-06-01T16:08:31Z
      DOI: 10.1016/j.clay.2017.05.024
      Issue No: Vol. 146 (2017)
       
  • Chitosan and surfactant co-modified montmorillonite: A multifunctional
           adsorbent for contaminant removal
    • Authors: Lifang Zhu; Linhan Wang; Yin Xu
      Pages: 35 - 42
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): Lifang Zhu, Linhan Wang, Yin Xu
      The demands for multifunctional adsorbents are increasing in these days because wastewater may simultaneously contain various types of contaminants. In this work, montmorillonite (Mt) was modified with both hexadecyltrimethylammonium (HDTMA) and chitosan (CTS), with the purpose of synthesizing multifunctional adsorbents that can efficiently adsorb hydrophobic organic contaminants, heavy metal cations, and dyes from water. The structural characteristics of the resulting modified samples (H/C-Mt) were first investigated using XRD, FTIR, TG, and Zeta potential measurements. According to the obtained results, both chitosan and HDTMA were intercalated into Mt interlayers, forming hydrophobic organo-phases. With increasing CTS loading amount, the basal spacing of C/T-Mt gradually increased, and the Zeta potential evolved from negative to positive. C/T-Mt could effectively uptake phenol, Cd2+, Conger red (CR), and crystal violet (CV) from water. The organo-phases created by HDTMA were responsible for the uptake of phenol on C/T-Mt, while the functional groups on CTS (e.g., OH, NH2) contributed to the adsorption of Cd2+. The positively charged surfaces of C/T-Mt, together with the hydrophobic interactions between C/T-Mt and contaminants, contributed to the effective uptake of CR on C/T-Mt. As for CV, the hydrophobic interactions should be the main reason for its adsorption on C/T-Mt. The obtained results suggested that C/T-Mt could be a multi-functional adsorbent for the effective uptake of different types of contaminants from water.
      Graphical abstract image

      PubDate: 2017-06-06T16:20:07Z
      DOI: 10.1016/j.clay.2017.05.027
      Issue No: Vol. 146 (2017)
       
  • Influence of allophane distribution on photocatalytic activity of
           allophane–titania composite films
    • Authors: Hiromasa Nishikiori; Shingo Matsunaga; Naoyuki Furuichi; Hitoshi Takayama; Koji Morita; Katsuya Teshima; Hiromi Yamashita
      Pages: 43 - 49
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): Hiromasa Nishikiori, Shingo Matsunaga, Naoyuki Furuichi, Hitoshi Takayama, Koji Morita, Katsuya Teshima, Hiromi Yamashita
      Allophane–titania composite films were prepared from titanium alkoxide sols dispersing the natural clay mineral allophane as a nano-sized adsorbent. The composites of the titania dispersing the allophane particles in the whole film efficiently degraded trichloroethylene and acetaldehyde better than the normal titania and the titania dispersing the allophane only on the film surface. The titania dispersing the allophane particles in the whole film produced lower amounts of the intermediate products in certain stages than the titania. These results are due to the effective reactant transport from the allophane to titania. Photocatalytic degradation of glucose and photoelectrochemical measurements using an electrolyte solution containing glucose indicated that oxidative degradation of the glucose enhanced the generation of electricity during UV irradiation. A higher short circuit current was observed using the film dispersing the allophane on the surface layer with an ca. 50-nm thickness than the titania and those dispersing the allophane only on the film surface. Allophane effectively adsorbed the glucose molecules and transported them to the titania, then the products were desorbed into the liquid phase. Therefore, the holes were efficiently transported and consumed by the glucose oxidation.
      Graphical abstract image

      PubDate: 2017-06-06T16:20:07Z
      DOI: 10.1016/j.clay.2017.05.026
      Issue No: Vol. 146 (2017)
       
  • Determination of the specific surface area of layered silicates by
           methylene blue adsorption: The role of structure, pH and layer charge
    • Authors: Nóra Hegyesi; Richárd T. Vad; Béla Pukánszky
      Pages: 50 - 55
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): Nóra Hegyesi, Richárd T. Vad, Béla Pukánszky
      The specific surface area of three layered silicates was determined by three independent methods; it was estimated from the average dimensions of individual silicate layers, determined by nitrogen adsorption using the BET model and calculated from the adsorption of methylene blue on their surface in aqueous sol. The BET model gave smaller surface areas than expected, because nitrogen molecules cannot penetrate freely into the interlayer space of the silicates. Geometric calculations and the methylene blue approach yielded very similar values for two different types of Laponite when the pH of the dispersion was adjusted to 6.5 or the edges of the silicate were modified with tetrasodium pyrophosphate dispersing agent. The measurement of surface area in water without the control of pH yielded smaller surface area, because methylene blue decreased the pH of the solution resulting in the competitive adsorption of methylene blue cations and protons at the basal surface. The methylene blue approach resulted in larger surface area than expected for the silicate with large ion exchange capacity, because of the tilted orientation of the adsorbed methylene blue molecules. All these factors must be considered during the use of the methylene blue method for the determination of the specific surface area of smectites.
      Graphical abstract image

      PubDate: 2017-06-06T16:20:07Z
      DOI: 10.1016/j.clay.2017.05.007
      Issue No: Vol. 146 (2017)
       
  • Stabilization of expansive Belle Fourche shale clay with different
           chemical additives
    • Authors: Mustafa Dayioglu; Bora Cetin; Soonkie Nam
      Pages: 56 - 69
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): Mustafa Dayioglu, Bora Cetin, Soonkie Nam
      Improving the engineering properties of expansive soils is very important in northern plains, Texas and mid-west regions of the United States. In this study, expansive Belle Fourche clay (B) from South Dakota, was mixed with the class C fly ash (FC), class F fly ash (FF) and lime. Swelling pressure (SWP) and unconfined compressive strength (UCS) tests were conducted on samples that were cured at different periods (0, 7 and 28days). Furthermore, freeze and thaw (F-T) effects on the swelling and strength properties of the clay and selected mixtures were investigated. Results showed that the SWP of the Belle Fourche clay (B) decreased significantly with addition of lime 4% by dry weight of soil from 235kPa to almost 0kPa. Mixing fly ashes also reduced the SWP to 47kPa and 100kPa with class C and class F fly ashes, respectively. Increase in F-T cycles reduced the SWP, whereas the SWP increased with 2 and 4 F-T cycles for the mixtures with the fly ashes. However, after 4cycles, the pressure of the same mixtures decreased. On the contrary, to the clay-fly ash mixtures, F-T did not affect the SWP of the clay-lime mixtures. In terms of strength, chemical treatment increased UCS. The overall effectiveness of the treatment under the curing and F-T was in the order of FC, lime, and FF. The UCSs of the clays treated with these additives were 3.58, 1.82, and 1.63 times higher than the non-treated clay. F-T reduced the UCS of the clay and the clay treated with FF. Although the UCS of the FC and lime mixtures increased within 2cycles of F-T, they did not show the same strength improving performance with more F-T cycles. It was observed that mixtures with higher liquid limit and plasticity index (PI) tended to have higher SWP and lower UCS. This study claimed that chemically stabilized soils with high CaO content, CaO/SiO2, CaO/Al2O3, and CaO/(SiO2 +Al2O3) ratios had higher potential to decrease SWP of expansive soils and increase UCS of weak soils.

      PubDate: 2017-06-06T16:20:07Z
      DOI: 10.1016/j.clay.2017.05.033
      Issue No: Vol. 146 (2017)
       
  • Mullite-zirconia composites prepared from halloysite reaction sintered
           with boehmite and zirconia
    • Authors: A. Raghdi; M. Heraiz; F. Sahnoune; N. Saheb
      Pages: 70 - 80
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): A. Raghdi, M. Heraiz, F. Sahnoune, N. Saheb
      In this study, Algerian halloysite, a naturally occurring clay mineral, was used as low-cost precursor for the production of mullite-zirconia composites. The halloysite was reaction sintered with boehmite and zirconia in the temperature range 1250–1650°C for 2h. Differential thermal analysis (DTA), thermogravimetry (TG), dilatometry, high temperature X-ray diffraction (XRD), and scanning electron microscopy (SEM) complementary techniques were used to characterize the prepared materials. The influence of ZrO2 content on the microstructure, densification, hardness, and coefficient of linear thermal expansion of the composites was investigated. Algerian halloysite was found suitable material for the synthesis of low-cost mullite based composites. All prepared samples exhibited same phase transformations that ended at 1550°C with the formation of monolithic mullite in halloysite-boehmite mixture and mullite-zirconia composites in halloysite-boehmite-zirconia mixture. The composite materials showed higher values of hardness and coefficient of linear thermal expansion compared with monolithic mullite. The composite containing 10% ZrO2 possessed the highest hardness value of 13.5GPa. The composite containing 30% ZrO2 possessed the lowest value of linear coefficient of thermal expansion of 7.5725×10−6 K−1 between 200 and 1500°C.
      Graphical abstract image

      PubDate: 2017-06-06T16:20:07Z
      DOI: 10.1016/j.clay.2017.05.037
      Issue No: Vol. 146 (2017)
       
  • Excavated soil waste as fine aggregate in fly ash based geopolymer mortar
    • Authors: P. Priyadharshini; K. Ramamurthy; R.G. Robinson
      Pages: 81 - 91
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): P. Priyadharshini, K. Ramamurthy, R.G. Robinson
      To explore the significance of geopolymer technology on producing environmental friendly waste based mortar which could be a sustainable replacement for conventional mortar; Low, medium and high plastic soil from different locations was used as fine aggregate to produce fly ash based geopolymer mortars. The experiments were designed using central composite design of response surface methodology. Molarity of NaOH, curing temperature and fly ash content were the key parameters considered in this study. The interaction effect of these parameters with four different fine aggregates (river sand, low, medium and high plastic soils) were identified and discussed. It is demonstrated that geopolymerisation helps in utilizing even high plastic soil as fine aggregate in construction applications. Soil based geopolymer mortar resulted in lower density range compared to conventional geopolymer of similar strength values. The test results show that strength and shrinkage properties of soil based geopolymer mortar significantly depends on the type of clay present in the soil. Geopolymer mix with each specific soil has an optimum combination of NaOH, curing temperature and binder dosage that helps them achieve the desired properties such as higher compressive strength and lower dry density, water absorption and shrinkage values.

      PubDate: 2017-06-06T16:20:07Z
      DOI: 10.1016/j.clay.2017.05.038
      Issue No: Vol. 146 (2017)
       
  • Oxidative degradation of sulfanilamide catalyzed by Fe/Cu/Al-pillared
           clays
    • Authors: Sesegma Ts. Khankhasaeva; Elvira Ts. Dashinamzhilova; Darima V. Dambueva
      Pages: 92 - 99
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): Sesegma Ts. Khankhasaeva, Elvira Ts. Dashinamzhilova, Darima V. Dambueva
      An oxidative degradation of an antibiotic sulfanilamide with hydrogen peroxide was carried out in the presence of Fe/Cu/Al-pillared clays as heterogeneous Fenton type catalysts. Fe/Cu/Al-pillared clays were synthesized by intercalation of layered aluminosilicate containing 95wt% montmorillonite with mixed polymeric Fe,Cu,Al-polyoxocations (Al/(Fe+Cu)=10/1, OH/(Fe+Cu+Al)=2.0mol/mol). The materials were characterized by chemical analysis, low-temperature nitrogen adsorption and XRD. Fe/Cu/Al-pillared clays were active catalysts for sulfanilamide oxidation with hydrogen peroxide in aqueous solutions: in the presence of these materials oxidation rate increased significantly and conversion of sulfanilamide reached 99–100%. The effect of experimental factors such as H2O2/sulfanilamide molar ratio, the catalyst content, the reaction temperature and the pH on the conversion of sulfanilamide were studied. The optimal conditions for the catalytic oxidation of sulfanilamide in the presence of Fe/Cu/Al-pillared clay that permit achieving a high conversion of sulfanilamide and catalyst stability were determined. The Fe/Cu/Al-pillared clay could be used in four consecutive cycles without regeneration and loss of activity. The main intermediate products of sulfanilamide oxidative degradation were sulfanilic acid, benzenesulfonic acid, p-benzoquinone and aliphatic carboxylic acids. The results of the study proved that Fe/Cu/Al-pillared clays were effective catalysts for oxidative degradation of sulfanilamide in aqueous solutions.
      Graphical abstract image

      PubDate: 2017-06-06T16:20:07Z
      DOI: 10.1016/j.clay.2017.05.018
      Issue No: Vol. 146 (2017)
       
  • Synthesis, cation exchange and dehydration/rehydration of sodium gordaite:
           NaZn4(OH)6(SO4)Cl·6H2O
    • Authors: Swami Area Maruyama; Fernanda Krause; Sergio Rodrigues Tavares Filho; Alexandre Amaral Leitão; Fernando Wypych
      Pages: 100 - 105
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): Swami Area Maruyama, Fernanda Krause, Sergio Rodrigues Tavares Filho, Alexandre Amaral Leitão, Fernando Wypych
      Sodium gordaite (NaG - NaZn4(OH)6(SO4)Cl·6H2O) was synthesized under air and inert atmosphere and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and selected area electron diffraction spectra (SAED). Intercalated hydrated sodium cations from NaG were exchanged by calcium, potassium and lithium, presenting changes of basal distance from 13.03Å in NaG to, respectively, 16.1Å, 16.1 and 17.9Å (in the sample synthesized under air) and from 13.05Å in NaG to 17.8Å, 17.5 and 17.7Å (in the sample synthesized under inert atmosphere). In the samples synthesized under air, all compounds were co-intercalated with carbonate anions, especially those after the exchange reaction with Ca+2 and K+, while this contamination was almost completely removed when the NaG synthesis was performed under inert atmosphere.
      Graphical abstract image

      PubDate: 2017-06-06T16:20:07Z
      DOI: 10.1016/j.clay.2017.05.029
      Issue No: Vol. 146 (2017)
       
  • Production of clay ceramics using agricultural wastes: Study of
           properties, energy savings and environmental indicators
    • Authors: R. Sani; A. Nzihou
      Pages: 106 - 114
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): R. Sani, A. Nzihou
      In this study, agro-wastes were used as additive raw materials for the production of fired clay ceramics. The objectives of this study are to evaluate the impact of adding agro-wastes into clay body on the thermal and mechanical properties of ceramic materials, to determine the net energy consumption and to determine gas emissions during firing process. The clay and agro-wastes were characterized by chemical elemental analysis, thermogravimetric and differential thermal analysis (TGA-DTA). The fired clay ceramics were produced with clay and optimal proportions of wheat straw (WS) and olive core flour (OCF). The thermal and mechanical properties were evaluated by measuring thermal conductivity with hot-disk method and bending test respectively. The results showed that for clay incorporated OCF (4, 8wt%) and WS (3, 7wt%), thermal conductivity was decreased by 16 to 30%. However, the mechanical strength of the same samples has slightly decreased respectively. TGA-DTA provided an approach to estimate the heat required or released for both clay and agro-wastes thermal decomposition. The addition of agro-wastes into the clay body showed that energy consumption of fired clay ceramics production decreased to above 36% for clay incorporated 4wt% OCF (C-4wt%OCF). The energy saving during the firing process was a tangible outcome. In order to determine the impact of the agro-wastes addition, the environmental indicators were discussed for the clay incorporated WS and OCF respectively. Total gas yield released were measured by Micro-GC after the combustion of clay incorporated OCF and WS in fixed bed reactor respectively. The analysis of gas emissions are related to the combustion of organic and inorganic compounds of agro-wastes and clay body, respectively. The CO2 emissions coming from the combustion of agro-wastes reached up to 4.38% for C-8wt%OCF. However, the CO2 emissions associated with decarbonatation of clay body decreased. Adding agro-wastes into the clay body results to improving thermal properties without negative impact on the mechanical properties of ceramic materials, also to a significant energy saving and decreasing of the inorganic CO2 emissions related to the decarbonatation of clay body. The relevance of this work, pointed out in the data presented in regards to the state-of-the art is that the paper is focused on fired clay ceramic properties, on energy savings and on the evaluation of environmental indicators in the laboratory scale.
      Graphical abstract image

      PubDate: 2017-06-06T16:20:07Z
      DOI: 10.1016/j.clay.2017.05.032
      Issue No: Vol. 146 (2017)
       
  • The modification of rectorite with carbon layers and trisodium
           trimetaphosphate for the removal of Pb2+
    • Authors: Ning Wang; Zhitao Feng; Xiaofei Ma; Pengwu Zheng
      Pages: 115 - 121
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): Ning Wang, Zhitao Feng, Xiaofei Ma, Pengwu Zheng
      At the presence of rectorite (Rec), starch was treated with hydrothermal carbonization to fabricate carbon layer with many oxygen containing groups on the surface of Rec layer, which were further reacted with trisodium trimetaphosphate (STMP) to introduce phosphate ester groups on Rec. The obtained RecCPN were used to remove heavy metal ions from aqueous solution. The adsorption kinetics and isotherms could be described with the pseudo- second-order model and the Langmuir model. The maximum monolayer adsorption capacities could reach 258.40mg/g for RecCPN at pH5 and 303K, in which the Pb2+ adsorption processes was spontaneous. The positive values of ΔH0 indicated that the interaction of Pb2+ with phosphate ester groups was endothermic. RecCPN still exhibited the good adsorption capacity in the adsorption-desorption cycles. In addition, RecCPN showed advantageous selectivity towards Pb2+ over other metal ions (Cu2+, Ni2+, Co2+ and Cd2+) and still removed above 90% Pb2+ at the initial trace Pb2+ concentration (0.5mg/L).

      PubDate: 2017-06-06T16:20:07Z
      DOI: 10.1016/j.clay.2017.05.044
      Issue No: Vol. 146 (2017)
       
  • Estimating Hofmeister energy in ion-clay mineral interactions from the
           Gouy-Chapman theory
    • Authors: Wei Du; Rui Li; Xinmin Liu; Rui Tian; Wuquan Ding; Hang Li
      Pages: 122 - 130
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): Wei Du, Rui Li, Xinmin Liu, Rui Tian, Wuquan Ding, Hang Li
      Hofmeister effects are of scientific importance in cation-clay mineral interactions. In this study, we present a kinetics-based approach to estimate the Hofmeister energy of such interactions from the Gouy-Chapman theory. Montmorillonite was employed as the experimental material; the Hofmeister energies of Cs+ and Na+ were estimated. A mathematical relationship between the Hofmeister energy (as well as the classical Coulomb energy and the total energy) of a cation and its equilibrium adsorption amount was first established based on the modified Gouy-Chapman theory; the miscible displacement technique was then employed to estimate the amount of the cation adsorbed at equilibrium. The Hofmeister energy was calculated by introducing the equilibrium adsorption amount into the established mathematical relationship. The validity of the suggested approach was further corroborated. Our study indicated that the observed Hofmeister energy in cation-clay mineral interactions cannot be explained by cationic size, hydration, or dispersion forces. The observed Hofmeister energy bears two important characteristics: it increased with an increase of electric field strength, and it was much larger for the softer Cs+ cation than for the harder Na+ cation. These characteristics implied that Hofmeister effects in cation-clay mineral interactions are closely related to the changes of cationic energy in the strong electric field near the clay mineral surface. Because of the strong Hofmeister energy from the Gouy-Chapman theory, the apparent charge of Cs+ increased from the normal/typical value of +1 to an effective charge of +2.354; in contrast, the apparent charge of Na+ merely increased from the normal/typical +1 to an effective charge of +1.112 in this clay mineral system.

      PubDate: 2017-06-06T16:20:07Z
      DOI: 10.1016/j.clay.2017.05.039
      Issue No: Vol. 146 (2017)
       
  • One-pot exfoliation of kaolinite by solvothermal cointercalation
    • Authors: Éva Makó; András Kovács; Viktoria Antal; Tamás Kristóf
      Pages: 131 - 139
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): Éva Makó, András Kovács, Viktoria Antal, Tamás Kristóf
      A one-pot solvothermal synthesis procedure of kaolinite-cetyltrimethylammonium chloride complex directly from kaolinite-urea precursor to produce kaolinite nanoscrolls is reported. Compared to the commonly applied solution/stirring method, the applied solvothermal synthesis is simple, convenient and effective, requiring an order of magnitude less time and reagent volume. The type of precursor, as well as the reaction time and temperature significantly affect the exfoliation rate of kaolinite. In addition, a strong correlation is demonstrated between the effectiveness of exfoliation and the interaction between the guest molecules and the octahedral sheets of kaolinite. The present findings reveal that the eco-friend kaolinite-urea precursor is favorable for direct intercalation of cetyltrimethylammonium chloride from methanol solution at 100°C (and at equilibrium vapor pressure of methanol), and that the formed kaolinite-cetyltrimethylammonium chloride complex can easily transform into kaolinite nanoscrolls. This conceptually new method utilizing supposed cointercalation processes can open the way to a new series of cost-efficient chemical routes for the direct exfoliation of kaolinite.
      Graphical abstract image

      PubDate: 2017-06-06T16:20:07Z
      DOI: 10.1016/j.clay.2017.05.042
      Issue No: Vol. 146 (2017)
       
  • Adsorption of switchable surfactant mixed with common nonionic surfactant
           on montmorillonite: Mechanisms and arrangement models
    • Authors: Xiaojun Hu; Senlin Tian; Shujiao Zhan; Jianxi Zhu
      Pages: 140 - 146
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): Xiaojun Hu, Senlin Tian, Shujiao Zhan, Jianxi Zhu
      To improve understanding of adsorption behavior of mixed surfactants on typical clay components in soil for potential applications of surfactant-enhanced remediation (SER) technologies during remediation of hydrophobic organics-contaminated soil, the adsorption mechanisms and arrangement models of an electrochemical switchable cationic surfactant (11-Ferrocenylundecyl) trimethylammonium bromide (FTMA), mixed with the nonionic surfactant Tween 80 on montmorillonite were investigated. The mixed system in the presence of Tween 80 remains electrochemically reversible. The adsorption isotherms of the pure FTMA and FTMA-Tween 80 mixed system on montmorillonite were Langmuir type. The major mechanism of pure FTMA adsorption is via cation exchange as the total capacity is close to the cation exchange capacity (CEC) of montmorillonite. With the addition of Tween 80, the cation exchange of FTMA would be weakened by the function of hydrogen bonding. As the added concentration of FTMA and Tween 80 are 2874mg/L and 50 times of critical micelles concentration of Tween 80, adsorption capacity of FTMA and mixed surfactants decrease from 280.6 to 235.2mg/g and 400 to 298mg/g. Moreover, the adsorption capacity of Tween 80 linearly decreases from 118.7 to 62.7mg/g. Meanwhile, as the amount of FTMA increases from 0.4 to 1.0 times CEC of montmorillonite, the arrangement model of FTMA in the interlayer of montmorillonite changes from a flat monolayer, lateral bilayer to pseudotrilayer. When mixed with Tween 80, the interlayer space of montmorillonite increased significantly, and it showed a gradual increasing trend of interlayer space as the concentration of Tween 80 increased. The results of the present study show that the combined use of cationic and nonionic surfactants can reduce the adsorption loss of surfactants during remediation of polluted soil and then be conducive to the application of SER technologies.

      PubDate: 2017-06-06T16:20:07Z
      DOI: 10.1016/j.clay.2017.05.025
      Issue No: Vol. 146 (2017)
       
  • Stabilization of kaolin clay slurry with sodium silicate of different
           silicate moduli
    • Authors: A. Stempkowska; J. Mastalska-Popławska; P. Izak; L. Ogłaza; M. Turkowska
      Pages: 147 - 151
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): A. Stempkowska, J. Mastalska-Popławska, P. Izak, L. Ogłaza, M. Turkowska
      In the ceramic technological processes, the suspensions with high concentration of ceramic particles (>60%) play a very important role because this let to obtain inter alia reasonable casting rates what is one of the most important steps during the ceramics manufacturing. The article shows the attempts to modify the rheological properties of concentrated ceramic slurries, based on kaolin KOC. Different alkali sodium silicate based stabilizers, i.e. sodium water glasses ((Na2SiO2)nO) of silicate moduli in the range 1.74–3.25, were used for the research. The flow curves were analyzed and the technological parameters of slurries were described. Special attention was paid to the stabilization of slurries with the use of sodium water glasses of higher silicate moduli (>2). It was found that the best results of the stabilization of the kaolin slurry can be obtained while using sodium water glass of silicate moduli 2–2.5. Sodium water glasses of the moduli smaller than 2 precipitated free silica in the suspension and increased the alkalinity of ceramic slurry while those larger than 2.5 created independent silicate micelles, co-existing with the dispersed kaolin grains. The mechanisms appearing during the stabilization of ceramic slurry with the use of sodium water glass were ion exchange and, the so called depleted stabilization.

      PubDate: 2017-06-06T16:20:07Z
      DOI: 10.1016/j.clay.2017.05.046
      Issue No: Vol. 146 (2017)
       
  • The pyrolysis kinetics of the conversion of Malaysian kaolin to metakaolin
    • Authors: M. Irfan Khan; Hafeez Ullah Khan; Khairun Azizli; Suriati Sufian; Zakaria Man; Ahmer Ali Siyal; Nawshad Muhammad; M. Faiz ur Rehman
      Pages: 152 - 161
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): M. Irfan Khan, Hafeez Ullah Khan, Khairun Azizli, Suriati Sufian, Zakaria Man, Ahmer Ali Siyal, Nawshad Muhammad, M. Faiz ur Rehman
      The aim of this work was to study the pyrolysis kinetics of the thermal transformation of kaolin to metakaolin with the aid of models and model free isoconversional methods. Thermal treatment in the range of 600–850°C is used to convert kaolin into an amorphous and highly reactive metakaolin (MK). In this study, the thermal transformation of kaolin to metakaolin was investigated using thermokinetics and instrumental analysis. Kaolin was subjected to thermogravimetric analysis (TGA) at heating rates of 10, 20 and 40°C/min, in the temperature range of 50–800°C. Approximately, 14.2% of mass loss was recorded during the TG analysis. 95% of the degree of dehydroxylation was attained at 635°C, representing the minimum temperature for this process. The TGA and its related data were analyzed using model free (based on DTG, DTA and TG) and model based kinetics methods. Both DTG and DTA peak temperatures were employed for the thermokinetics of kaolin using Ozawa, Kissinger and Starink methods; giving an E a in the range of 246.6–252.5kJ·mol−1. A slight higher average E a (266–267kJ·mol−1 vs 246.6–252.5kJ·mol−1) was observed when TGA based integral methods (KAS, FWO and Starink) were used. The mechanism of the thermokinetics was investigated using the Redfern model and the best fitting was given by 3rd order chemical reaction (F3) function. Both model-free and model based thermokinetics methods could be used to validate the thermal transformation of kaolinite to metakaolinite.

      PubDate: 2017-06-11T16:36:27Z
      DOI: 10.1016/j.clay.2017.05.017
      Issue No: Vol. 146 (2017)
       
  • Characterization of Tunisian clay suitable for pharmaceutical and cosmetic
           applications
    • Authors: S. Gamoudi; E. Srasra
      Pages: 162 - 166
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): S. Gamoudi, E. Srasra
      The aim of this study is to assess the suitability of purified Tunisian clay for its possible pharmaceutical and cosmetic uses. Mineralogical, chemical and physicochemical characterization was performed with the aid of tools like X-ray diffraction (XRD), Chemical composition, DTA/TGA analysis, Cation exchange capacity (CEC), particle size distribution by laser dispersion (PSD), surface area (BET method), Point of zero charge (PZC) and surface charge density σH. Pharmacopoeia tests were also carried: Swelling capacity, sedimentation volume and pH measurement. For microbiological tests, the absence of Salmonella species, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa was tested. The X-ray diffraction data revealed that the Tunisian sample is an interstratified illite-smectite. The percentage of smectitic fraction is estimated to be 78%. The chemical, textural and porosimetric results show important values suggesting that this mineral clay can function in creams, powders and emulsions. In view of the fundamentals of major pharmacopoeias for use of bentonite in pharmacy and considering the swelling capacity and sedimentation volume values, and microbiological results we could designate a pharmaceutical acceptable denomination for Tunisian purified clay.

      PubDate: 2017-06-11T16:36:27Z
      DOI: 10.1016/j.clay.2017.05.036
      Issue No: Vol. 146 (2017)
       
  • Heterogeneous poly(ionic liquids) catalyst on nanofiber-like palygorskite
           supports for biodiesel production
    • Authors: Wen Zhang; Meisheng Li; Jie Wang; Yijiang Zhao; Shouyong Zhou; Weihong Xing
      Pages: 167 - 175
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): Wen Zhang, Meisheng Li, Jie Wang, Yijiang Zhao, Shouyong Zhou, Weihong Xing
      New heterogeneous poly(ionic liquids) catalysts (PAL-PILs) were successfully prepared by grafting polymerization of acid ionic liquids (ILs) (1-butysulfonate-3-vinylimidazole hydrogen sulfate) onto nanofiber-like palygorskite (PAL) supports that had been, in advance, covalently modified by γ-methacryloxypropyl trimethoxy silane (OPAL). Using the ester yields and PILs grafting degrees as main indexes, the optimized immobilization conditions were that the mass ratio of OPAL to ILs monomer was 1:2, the immobilization temperature and time were 60°C and 30h, the initiator (2,2′-Azobis(2-methylpropionitrile) dosage was about 5wt%, respectively. Then, the esterification between methanol and oleic acid was carried out to investigate the catalytic properties of PAL-PILs. For the homogeneous ILs catalyst, the yield of methyl oleate was about 85%. For the PAL-PILs, on which only about 41% of ILs used in homogeneous catalysis was immobilized, the yield could reach over 69% after reacting only 5h at 75°C at atmospheric pressure, when the molar ratio of methanol to oleic acid is adjusted to 12:1. More importantly, the yield of methyl oleate still maintained at about 22% after 6 recycling experiments. Moreover, the PAL-PILs catalysts exhibited efficient catalytic properties and could be recycled easily. These results offer great potential for the PAL-PILs in the biodiesel production for further research.
      Graphical abstract image

      PubDate: 2017-06-11T16:36:27Z
      DOI: 10.1016/j.clay.2017.05.031
      Issue No: Vol. 146 (2017)
       
  • Modelling the deterioration of the near surface caused by drying induced
           cracking
    • Authors: Ross A. Stirling; Stephanie Glendinning; Colin T. Davie
      Pages: 176 - 185
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): Ross A. Stirling, Stephanie Glendinning, Colin T. Davie
      Assets such as roads, railways, pipelines and flood embankments are inherently vulnerable to the action of weather and in the long term, climatic change. Their exposure makes them highly susceptible to deterioration during the course of their design life and beyond. The drivers of deterioration are believed to be human (e.g. traffic, maintenance) and environmental (e.g. weather, pollution, burrowing) but the actual deterioration processes are not well understood. Among the weather-driven processes, it is believed that desiccation of the near-surface and the development of cracking can significantly influence the mechanical, hydrological and thermal behaviour of geotechnical structures primarily by impacting the transmission of water between the atmosphere and soil. Enhanced infiltration during rainfall events can potentially lead to rapidly elevated pore water pressures and reduced shear strength and is widely cited as the strength reduction mechanism behind the wide spread failure of infrastructure slopes. This paper describes the development of a pseudo-discrete continuum Finite Difference model and its application to investigate the influence of soil properties (including elastic modulus, hydraulic conductivity and soil-water retention) on the desiccation process and eventual crack initiation and propagation behaviour. The generation of a desiccated crust typified by highly negative pore pressures and increasingly disintegrated texture is demonstrated. The influence of projected higher drying rates and seasonal drying-wetting cycles (that could result from climate change) on crack pattern development is investigated to gain an understanding of progressive deterioration. This points towards the potential for increased future deterioration rates of geotechnical infrastructure.

      PubDate: 2017-06-11T16:36:27Z
      DOI: 10.1016/j.clay.2017.06.003
      Issue No: Vol. 146 (2017)
       
  • The time-dependent swelling of argillaceous rock under
           resaturated conditions
    • Authors: L.L. Wang; R.W. Yang; S. Chanchole; G.Q. Zhang
      Pages: 186 - 194
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): L.L. Wang, R.W. Yang, S. Chanchole, G.Q. Zhang
      The evolution of argillaceous rock suffering from desaturation/resaturation is a key factor that affects the safety of deep geological repositories of radioactive waste. However, the behavior of this rock when resaturated to nearly 100% relative humidity (RH) has been poorly studied, because water condensation was frequently encountered in the conventional RH-control technique. This issue has been overcome in the present work using an environmental scanning electron microscope (ESEM) that provides improved RH control. The recorded micrographs subsequently were analyzed for full-field strain measurement using digital-image correlation techniques. The results reveal that the swelling (the sample in the size of several millimeters) attained stability in less than an hour during the 30%–80% RH step; however, the swelling strain continued to rise for up to 10h during the 80%–99% RH step. The anomalous time-dependent swelling at nearly 100% RH is not explicable in terms of hydraulic flow or propagation of swelling-induced microcracks. The evolution of strain fields shows that the areas of continuous swelling are located mainly inside the clay matrix. We suggest that the creep-like swelling of clay might be related to an osmotic flow (driven by a solute-concentration gradient) that dissipates more slowly than the hydraulic flow (driven by pressure gradient). The existence of time-dependent swelling in argillaceous rock under resaturated conditions should be considered for the reliability assessment of long-term radioactive waste disposal.

      PubDate: 2017-06-11T16:36:27Z
      DOI: 10.1016/j.clay.2017.05.041
      Issue No: Vol. 146 (2017)
       
  • The formation mechanism of organoammonium-kaolinite by solid-solid
           reaction
    • Authors: Ding Wang; Qinfu Liu; Dandan Hou; Hongfei Cheng; Ray L. Frost
      Pages: 195 - 200
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): Ding Wang, Qinfu Liu, Dandan Hou, Hongfei Cheng, Ray L. Frost
      Solid-solid reactions and its corresponding solution method have been utilized to study the formation and intercalation mechanism of organoammonium-kaolinite formed from quaternary ammonium salt and kaolinite (Kaol) by using a methoxy-modified Kaol as an intermediate. The products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetry and differential scanning calorimetry (TG–DSC) analysis. Results showed that butyl trimethylammonium and hexyl trimethylammonium ions were successfully intercalated into the silicate layers, while the larger ions (CnH2n+1N(CH3)3 +, n≥8) were not. The intercalated alkylammonium ions were lying flat and poorly packed between the interlayer spaces of Kaol. In addition, a similar thermal behavior in the products obtained by both methods was also revealed. During the intercalation process, the alkylammonium ions were introduced by ion-dipole intercalation. In addition to the ion-dipole force, some other factors may contributed to these results, such as the geometrical constraint, the pH value of the mixed solution, the adsorbed water molecules, and the charge distribution at the external surfaces (the latter three will play a role if solutions are used). When solid-state reaction was used, the attraction caused by ion-dipole force was not strong enough to overcome the geometrical constraints, therefore larger alkylammonium ions were not intercalated.
      Graphical abstract image

      PubDate: 2017-06-11T16:36:27Z
      DOI: 10.1016/j.clay.2017.05.022
      Issue No: Vol. 146 (2017)
       
  • Methodological reconstruction of dioctahedral 1:1 phyllosilicate polytypes
    • Authors: Carlos E. Teixeira; Paulo R.G. Brandão; Ricardo W. Nunes
      Pages: 201 - 205
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): Carlos E. Teixeira, Paulo R.G. Brandão, Ricardo W. Nunes
      The layered kaolin-group minerals are composed mainly by three polytypes: kaolinite, dickite and nacrite. The geometrical polytypic reconstruction of these phases regards both the topological properties of individual networks (e.g., OH network linked to the hexagonal siloxane surface) and energetic aspect of superposition of cations. Starting from early attempts made by Bookin and Newnham, Zvyagin, Dornberger-Schiff and Durovic proposed their own symbolic representation of these structures. This work used the symbolic proposal of Zvyagin to prepare a methodological strategy to build the 52 species of dioctahedral polytypes. Two examples are shown to demonstrate the methodology and the CIF file of all the structures are made available.

      PubDate: 2017-06-11T16:36:27Z
      DOI: 10.1016/j.clay.2017.06.001
      Issue No: Vol. 146 (2017)
       
  • Molecular dynamics simulation of hydrated Na-montmorillonite with
           inorganic salts addition at high temperature and high pressure
    • Authors: Camara Moussa; Jiafang Xu; Xiaopu Wang; Jun Zhang; Zhe Chen; Xiaodi Li
      Pages: 206 - 215
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): Camara Moussa, Jiafang Xu, Xiaopu Wang, Jun Zhang, Zhe Chen, Xiaodi Li
      The swelling behaviors of Na-montmorillonite (Na-Mt) in non-ambient environment have been the subject of considerable speculation due to the difficulties associated with their study. Inorganic salts are often used to minimize clay mineral hydration. The influence of inorganic salts addition (NaCl, CaCl2, KCl) on the hydration of Na-Mt at high temperature and high pressure (HTHP) was investigated by molecular dynamics simulation at 6GPa and different temperatures (200, 300, 400, 500 and 600K) in an isobaric isothermal ensemble (NPT). Water model and force field used in the clay-water system are SPC/E model and universal force field (UFF), respectively. The results show that after adding inorganic salts into Na-Mt, the mobility of the interlayer species increases, and the hydration shell of the interlayer cations decreases with a rise in temperature. The influence of temperature on the diffusion of water molecules is much greater than that of the ions present in the interlayer. Temperature increase and hydration degree play an important role on the diffusion behavior of the interlayer species. The size, valence, mass and hydration energy of cations present between the layers affect the structure of Na-Mt interlayer. The inorganic salts are able to inhibit the hydration of Na-Mt by reducing the mobility of the interlayer species and the basal spacing. After analyzing the effect of each salt on Na-Mt, it was found that, the most stable state of Na-Mt at HTHP is achieved with KCl addition, compared with NaCl and CaCl2. It is expected the results obtained from this study would help to understand the inhibition effect of inorganic salts on Na-Mt, and predict the swelling of Na-Mt at HTHP.

      PubDate: 2017-06-11T16:36:27Z
      DOI: 10.1016/j.clay.2017.05.045
      Issue No: Vol. 146 (2017)
       
  • Layered europium hydroxide system for phosphorous sensing and remediation
    • Authors: Cláudia C.L. Pereira; João Carlos Lima; Artur J. Moro; Bernardo Monteiro
      Pages: 216 - 222
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): Cláudia C.L. Pereira, João Carlos Lima, Artur J. Moro, Bernardo Monteiro
      A Layered Lanthanide Hydroxide (LLH) material based on europium (LEuH, Eu8(OH)20Cl4.6H2O) was intercalated with 2,6-naphtalenedicarboxylate (NDC) yielding a material presenting the bright red luminescence characteristic of Eu3+, both by direct excitation of europium and energy transfer from NDC. The material behaves as a sensor towards anions which display the ability to exchange with NDC. The sensor was tested with several anions (phosphate, sulphate, pyrophosphate, acetate, and tetraborate anions) and the changes in NDC (λem =380nm) and europium (λem =615nm) emission intensities upon excitation of NDC (λex =357nm), were studied. Phosphate was found to have the highest degree of intercalation and displayed a strong increase (400% fold) on the fluorescence intensity of NDC. The presence of phosphate was further confirmed with Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-AES). Taking advantage of LEuH selectivity towards phosphate, its applicability in phosphorus remediation was studied presenting high sequestration capacity followed by controlled release of phosphate in three consecutive cycles and improved stability of the LEuH host material. These results highlight the significant potential of LLHs as new scavenging agents for inorganic phosphate.
      Graphical abstract image

      PubDate: 2017-06-17T01:46:04Z
      DOI: 10.1016/j.clay.2017.06.002
      Issue No: Vol. 146 (2017)
       
  • Geothermal clay-based geopolymer binders: Synthesis and microstructural
           characterization
    • Authors: Qian Wan; Feng Rao; Shaoxian Song; Carlos Alberto León-Patiño
      Pages: 223 - 229
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): Qian Wan, Feng Rao, Shaoxian Song, Carlos Alberto León-Patiño
      Geothermal clay rich in kaolinite was first prepared into geopolymer binders. Preparation conditions of calcination on geothermal clay, Na2SiO3 and NaOH combination in alkaline activator, and water content were studied. Thermal nature of the geothermal clay was characterized by TG-DSC and XRD measurements, which shows characteristics of kaolinite and cristobalite during calcination. Mechanical property, morphology and microstructure of the geothermal clay-based geopolymers were characterized by compressive strength measurements, SEM observation and NMR spectra analysis. With optimal synthesizing parameters, geothermal clay-based geopolymer possessed a compressive strength of 19.5MPa, as well as a homogeneous geopolymeric gel with high percentages of Q 4 (2Al) and Q 4 (1Al). As geothermal clay is supposed to be of intermediate dissolution reactivity in geopolymerization, this synthesis might extend the kinds of raw aluminosilicates in geopolymer formation.

      PubDate: 2017-06-17T01:46:04Z
      DOI: 10.1016/j.clay.2017.05.047
      Issue No: Vol. 146 (2017)
       
  • Improving flame retardancy of IFR/PP composites through the synergistic
           effect of organic montmorillonite intercalation cobalt hydroxides modified
           by acidified chitosan
    • Authors: Qinghong Kong; Ting Wu; Hongkai Zhang; Yi Zhang; Manman Zhang; Tianyu Si; Lin Yang; Junhao Zhang
      Pages: 230 - 237
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): Qinghong Kong, Ting Wu, Hongkai Zhang, Yi Zhang, Manman Zhang, Tianyu Si, Lin Yang, Junhao Zhang
      To improve the flame retardancy of IFR/PP composites, organic montmorillonite (Mt) intercalation cobalt compounds (Co-OMt) were prepared and modified by acidified chitosan to further expand the interlayer spacing of Mt. The Co-OMt/IFR/PP nanocomposites were fabricated via melt blending method. The results indicated that cobalt hydroxides and acidified chitosan were successfully intercalated into interlayers of Mt, which promoted the fine dispersion of Co-OMt in PP matrix. The results of limiting oxygen index (LOI) and vertical burning (UL-94) tests indicated that IFR/PP composites only reached V-2 rating and the LOI value was 26.5%. With addition of 4mass% Co-OMt, 4mass% Co-OMt/IFR/PP nanocomposites passed UL-94 V-0 rating and the LOI value was high to 32.1%. Furthermore, the cone calorimeter tests results confirmed that peak heat release rate (PHRR), total heat release (THR) and peak smoke production rate (PSPR) of 4mass% Co-OMt/IFR/PP nanocomposites decreased by 33.7%, 11.8% and 16.7% compared with those of IFR/PP composites. The notably improved flame retardant and smoke suppression properties were attributed to the fine dispersion of Co-OMt with layered structure and excellent catalytic performance in PP matrix, which promoted the fully cover of consolidated and compact residual layers on the surface of polymer during combustion, ultimately suppressing heat and mass transfer between polymer matrix and flame zone.

      PubDate: 2017-06-17T01:46:04Z
      DOI: 10.1016/j.clay.2017.05.048
      Issue No: Vol. 146 (2017)
       
  • Synthesis of a kaolin-based geopolymer using a novel fusion method and its
           application in effective water softening
    • Authors: M. Naghsh; K. Shams
      Pages: 238 - 245
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): M. Naghsh, K. Shams
      In this study, kaolin-based geopolymer was synthesized using a two-step method that consists of a fusion step (fusion of kaolin and sodium hydroxide), and a hydration and dealkalization step. The fusion step was performed at a temperature range of 400–800°C for 10 to 20h, and the hydration and dealkalization step was carried out by washing the fusion product with demineralized water for a short time (<10min). The synthesized geopolymer was characterized using XRD, FTIR, SEM, EDS and BET analyses. The sorption efficiency of the synthesized geopolymer was examined via removing Ca2+ and Mg2+ from both model media and groundwater. Results showed that sodium hydroxide to kaolin ratio, fusion time and temperature have profound effects on the performance of geopolymer in reduction of water hardness. Response Surface Methodology (RSM) was used to determine the optimal geopolymer synthesis conditions. RSM results indicated that the sodium hydroxide to kaolin ratio of >2.2, the fusion time of >14h and the fusion temperature range of 500–700°C provide the optimal synthesis conditions. Moreover, the synthesized geopolymer can efficiently adsorb Ca2+ and Mg2+ from both model media and groundwater. Based on the Langmuir isotherm model, the maximum Ca2+ adsorption capacity was 76.34mg/g at 25°C, increasing to 94.34mg/g at 45°C. Similarly, the maximum Mg2+ adsorption capacity increased from 39.68mg/g at 25°C to 51.55mg/g at 45°C. The adsorption experimental data at the above mentioned temperatures (i.e., 25 and 45°C) fitted well with the pseudo-second-order model. Finally, efficient regeneration of the saturated geopolymer, using sodium chloride solution, suggested that the dominating mechanism of water softening by the synthesized geopolymer is ion exchange.

      PubDate: 2017-06-17T01:46:04Z
      DOI: 10.1016/j.clay.2017.06.008
      Issue No: Vol. 146 (2017)
       
  • Sepiolite-TiO2 nanocomposites for photocatalysis: Synthesis by microwave
           hydrothermal treatment versus calcination
    • Authors: Feng Zhou; Chunjie Yan; Hongquan Wang; Sen Zhou; Sridhar Komarneni
      Pages: 246 - 253
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): Feng Zhou, Chunjie Yan, Hongquan Wang, Sen Zhou, Sridhar Komarneni
      Sepiolite-TiO2 nanocomposites were synthesized by conventional calcination process and microwave hydrothermal (M-H) treatment and were tested and compared for their photocatalytic activity. XRD analysis indicated that nanocomposites after calcination at 500°C or M-H treatment for 40min at about 200°C appear to be the optimal conditions, which assured the amorphous TiO2 to crystalline anatase phase transition. The deposition of the TiO2 on the surface of sepiolite by M-H treatment yielded small dispersed nanoparticles at all treatment times used in this study. However, TiO2 particle size increased with increasing calcination temperature, which was confirmed by SEM and TEM. N2-adsorption-desorption isotherms indicated that calcination process reduced the specific surface areas of the nanocomposites while the M-H treatment led to a higher surface area with better photocatalytic performance for the degradation of Orange G. The intact structure of sepiolite and the homogeneous dispersion of the TiO2 nanocrystals on sepiolite surfaces led to enhanced photocatalytic activity in M-H treated samples.
      Graphical abstract image

      PubDate: 2017-06-17T01:46:04Z
      DOI: 10.1016/j.clay.2017.06.010
      Issue No: Vol. 146 (2017)
       
  • In situ high temperature X-ray diffraction study of illite
    • Authors: Guanyu Wang; Hejing Wang; Nan Zhang
      Pages: 254 - 263
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): Guanyu Wang, Hejing Wang, Nan Zhang
      Despite extensive researches, many aspects of the structural transformation that occur in illite on heating remain unclear. This study concentrates on samples from a mine located in Wenzhou, Zhejiang Province, China to supplement data obtained by previous investigators. In situ high temperature X-ray diffraction (HTXRD), infrared spectroscopy (IR), field emission scanning electron microscope (FESEM) and electron microprobe (EMP) analysis were used to record the characterization of the raw material. XRD pattern showed the illite sample was primarily in 2M1 polytype. The phase transition from illite into dehydroxylated phase started at about 525°C in static air and at about 550°C in vacuum, and from dehydroxylated phase into mullite occurred at above 1100°C. These lattice parameters of illite (RT – 1100°C) and mullite (1125–1150°C) both in static air and in vacuum were refined. The variations of illite lattice parameters with temperature (°C) were therefore well described. Thermal expansion coefficients of illite (RT – 1100°C) were determined. In situ high temperature X-ray diffraction study revealed four stages during heating: expansion, dehydroxylation, post-dehydroxylation and mullite stages.

      PubDate: 2017-06-17T01:46:04Z
      DOI: 10.1016/j.clay.2017.06.006
      Issue No: Vol. 146 (2017)
       
  • Rheological behavior and morphology of acrylonitrile-butadiene
           rubber/poly(ethylene-co-vinyl acetate) blends filled by various organoclay
           contents
    • Authors: Mohammad Razavi-Nouri; Mahmoud Karami; Ghasem Naderi
      Pages: 1 - 10
      Abstract: Publication date: 1 September 2017
      Source:Applied Clay Science, Volume 145
      Author(s): Mohammad Razavi-Nouri, Mahmoud Karami, Ghasem Naderi
      The blends of acrylonitrile-butadiene rubber (NBR) and poly(ethylene-co-acetate) (EVA) with different mass ratios (20, 40 and 60 mass% NBR) and organoclay (OC) contents (1,3, 5 and 7 mass% OC) were prepared in an internal mixer. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results revealed that for the nanocomposites containing 7 mass% OC, the majority of OC layers were exfoliated although some intercalated structures could also be observed. The scanning electron micrographs of the nanocomposites containing 40 mass% NBR showed that the rubber average domain size decreased significantly with the increase in the OC content in comparison with that of the corresponding unfilled blend. Atomic force microscopy (AFM) images indicated that the addition of OC improved the mixing efficiency of the two parent polymers by which the two-phase morphology could not be detected to any further extent. The rheological experiments showed that percolation was taken place when the OC content was about 3 mass%. Moreover, the elasticity of the materials containing 3 mass% OC and beyond was much higher than that of NBR and its value increased with the increase in the OC content. These nanocomposites also had a plateau region in the entire range of angular frequency studied.
      Graphical abstract image

      PubDate: 2017-05-27T18:18:32Z
      DOI: 10.1016/j.clay.2017.05.021
      Issue No: Vol. 145 (2017)
       
  • Crystallochemical aspect of clay and clayish matter minerals luminescence
    • Authors: Nina N. Boroznovskaya; Luiza A. Zyryanova; Alexandra P. Korneva; Tatyana S. Nebera; Maria O. Ivanova
      Pages: 11 - 16
      Abstract: Publication date: 1 September 2017
      Source:Applied Clay Science, Volume 145
      Author(s): Nina N. Boroznovskaya, Luiza A. Zyryanova, Alexandra P. Korneva, Tatyana S. Nebera, Maria O. Ivanova
      X-ray luminescence (XRL) spectra in optical range of wave-lengths and thermoluminescence (TL) curves of several clay and clayish matter minerals were recorded for the first time. Mineral composition of all the samples was determined on the base of X-ray diffraction results. It was stated that XRL of clay minerals is related to their crystallochemical characteristics (type and degree of regularity of structure and isomorphism occurrence in particular). In the opinion of the authors, differences between luminescent characteristics of halloysite and kaolin minerals are related to syngony (triclinic or monoclinic) and possibility of Si4+ substitution with Al3+ in tetrahedral coordination that lead to uncompensated charges appearing and formation of luminescence centres based on silicon and aluminium tetroxides.

      PubDate: 2017-05-27T18:18:32Z
      DOI: 10.1016/j.clay.2017.05.019
      Issue No: Vol. 145 (2017)
       
  • Potassium adsorption and release properties of clays in peat-based
           horticultural substrates for increasing the cultivation safety of plants
    • Authors: I. Binner; S. Dultz; M. Schellhorn; M.K. Schenk
      Pages: 28 - 36
      Abstract: Publication date: 1 September 2017
      Source:Applied Clay Science, Volume 145
      Author(s): I. Binner, S. Dultz, M. Schellhorn, M.K. Schenk
      Clay amendments are used widely in the horticultural industry in peat-based substrates, as they have the capability to improve the potassium (K) buffering capacity. The K adsorption and desorption behavior of different clays was characterized here to develop criteria for identification of clays suitable for substrate amendment and to evaluate their significance for plant K uptake. K adsorption of saprolitic, bentonitic and relocated clays from the Westerwald area, Germany, was characterized with adsorption isotherms for calculating the maximum adsorption capacity for K. The K desorption was quantified in a percolation experiment using 0.01M CaCl2 as extractant. The influence of a varying K adsorption capacity of the clays on the K availability to plants was investigated in a growth experiment. The availability of K in substrates was determined by 0.01M CaCl2 (CAT), Ca-acetate-lactate and NH4 acetate. Different cultivation practices were simulated by varying the start of K topdressing: “immediate,” “delayed” and “no” K topdressing. A higher K adsorption capacity of the clays amended resulted in a lower K concentration in the pore solution of clay-amended peat-based substrates, while the CAT extractable K concentration was the same. It also resulted in an enhanced plant growth and higher K concentrations in the shoot without K topdressing. The uptake of K by plants exceeded the amount of exchangeable K in some peat-clay blends where no K was fertilized. The amount of K released from the clays in the plant experiments was in the same magnitude as the maximal desorbable K determined in the percolation experiment and was highly dependent on the mineralogical composition in the order: smectitic>illitic, kaolinitic clay. The K released from the clays contributed significantly to the supply of K to plants.

      PubDate: 2017-06-01T16:08:31Z
      DOI: 10.1016/j.clay.2017.05.013
      Issue No: Vol. 145 (2017)
       
  • A probabilistic approach for the assessment of the influence of the
           dielectric constant of pore fluids on the liquid limit of smectite and
           kaolinite
    • Authors: Giovanni Spagnoli; Asuri Sridharan; Pierpaolo Oreste; Lucio Di Matteo
      Pages: 37 - 43
      Abstract: Publication date: 1 September 2017
      Source:Applied Clay Science, Volume 145
      Author(s): Giovanni Spagnoli, Asuri Sridharan, Pierpaolo Oreste, Lucio Di Matteo
      Liquid limit (LL) is defined as a limiting water content separating the viscous liquid state and plastic state of soil consistency. LL of clays, being a basic physico-chemical property, plays a role in environmental geotechnical engineering practice. Since it is well-known that kaolinite and smectite behave quite differently from each other from the geotechnical point of view, ninety-one data regarding smectite (Na and Ca) and kaolinite mixed with organic pore fluids having different dielectric constant (ε) values have been carefully analyzed. Data confirm that for a decreasing ε value of the pore fluid a decrease in LL is observed for the smectitic clays, with different magnitude depending on the main ion, whereas for kaolinitic clays this decreasing ε causes an increase in attractive forces causing flocculation and increase in LL values. A probabilistic approach has been performed to assess the robustness of the regression functions. For smectitic and kaolinitic clays the mathematical dependency of LL with ε is validated by the probabilistic analysis.

      PubDate: 2017-06-01T16:08:31Z
      DOI: 10.1016/j.clay.2017.05.009
      Issue No: Vol. 145 (2017)
       
  • Structure and slow release property of chlorpyrifos/graphene
           oxide-ZnAl-layered double hydroxide composite
    • Authors: Jiexiang Liu; Qiao Zhao; Xiaoguang Zhang
      Pages: 44 - 52
      Abstract: Publication date: 1 September 2017
      Source:Applied Clay Science, Volume 145
      Author(s): Jiexiang Liu, Qiao Zhao, Xiaoguang Zhang
      A series of the graphene oxide-ZnAl-layered double hydroxide composites loaded with pesticide chlorpyrifos (CPF/GO-LDH) were fabricated by an exfoliation-restacking method. CPF/GO-LDH composites were characterized by powder X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and transmission electron microscopy (TEM), thermogravimetry analysis and differential scanning calorimetry (TGA-DSC). The interlayer distances of CPF/GO-LDH with various GO/LDH mass ratios were in the range of 0.70–0.87nm, which were analyzed on the basis of electrostatic interaction between LDH nanosheets and GO substrate. The combustion temperature of CPF in the composites was enhanced 130–170°C. Release behaviors of CPF/GO-LDH composites in buffer solutions were investigated and analyzed. The sustainable slow releases were observed during the whole stage studied, and the release rates and equilibrium release amounts of CPF were closely dependent on release mediums and GO/LDH mass ratios. The release behaviors of CPF/GO-LDH were fitted with pseudo second-order and parabolic diffusion models. The present study suggested that the CPF/GO-LDH could be potentially applied for controlled-release of the pesticide.

      PubDate: 2017-06-17T01:46:04Z
      DOI: 10.1016/j.clay.2017.05.023
      Issue No: Vol. 145 (2017)
       
  • Facile and controllable synthesis of iron nanoparticles directed by
           montmorillonite and polyvinylpyrrolidone
    • Authors: Mingde Fan; Lijie Zhang; Ruizhe Wang; Haozhe Guo; Shiyu Jia
      Pages: 1 - 8
      Abstract: Publication date: August 2017
      Source:Applied Clay Science, Volume 144
      Author(s): Mingde Fan, Lijie Zhang, Ruizhe Wang, Haozhe Guo, Shiyu Jia
      Porous host-hybridized metal nanoparticles are of great potential in sorption and catalysis related processes. The objective of this study was to synthesize property-controllable iron nanoparticles in montmorillonite and polyvinylpyrrolidone involved borohydride reduction system. In this system, mixed primary and secondary iron nanoparticles were readily generated. These resulting nanoparticles displayed an α-Fe@iron-oxide@polyvinylpyrrolidone core-double-shell architecture, in which the oxide shells protect the α-Fe cores from thorough oxidation in essential. In hybridization process, a polymer barrier was developed on the clay mineral surfaces. Due to the barrier-related steric hindrances and/or the alkaline pH-derived electrostatic repulsions, the clay mineral particles built a card-house flocculation structure, which can be converted to a semi-card-house form in dry products by suitable washing and drying treatments. The binding of the polymer to the iron and clay mineral surfaces would be mainly through hydrogen bonding. In general, the card-house pores and polymer layers made the hybridized iron nanoparticles much smaller and more dispersed than their bare counterparts. Specifically, by adjusting the molar mass and concentration of the polymer and the reductant amount, the hybridized iron nanoparticles could be further optimized. This synthesis route is carried out in situ under ambient temperature and atmosphere, greatly simplifying the process for iron nanoparticles preparation.
      Graphical abstract image

      PubDate: 2017-05-07T18:25:22Z
      DOI: 10.1016/j.clay.2017.04.022
      Issue No: Vol. 144 (2017)
       
  • Fluid flow and effective conductivity calculations on numerical images of
           bentonite microstructure
    • Authors: F. Bouchelaghem; R. Pusch
      Pages: 9 - 18
      Abstract: Publication date: August 2017
      Source:Applied Clay Science, Volume 144
      Author(s): F. Bouchelaghem, R. Pusch
      Hydraulic conductivities of compacted water-saturated bentonite were computed based on the real microstructure. The Homogenization of Periodic Media approach employed fully acknowledges the heterogeneous and multiscale microstructure of clay, as well as locally varying physical flow properties. Consequently, three levels of description were considered : the microscopic level of clay particles, the mesoscopic level of clay aggregates, mineral grains and inter-aggregate porosity, and the macroscopic level of the sample subjected to fluid pressure gradients in the laboratory. Starting from the local description of fluid flow, the expression of the effective hydraulic conductivity tensor was derived. The soft and dense gels and the open voids may form a connected flow path or remain occluded. The local problems were solved on the microstructure obtained from a digitalized micrograph by image analysis. The contribution to macroscopic flow by the soft and dense gels was investigated in various configurations, and comparisons were made with hydraulic conductivity data for MX-80 bentonite.

      PubDate: 2017-05-07T18:25:22Z
      DOI: 10.1016/j.clay.2017.04.023
      Issue No: Vol. 144 (2017)
       
  • X-ray crystallinity of different soil nanoclays in relation to phosphatase
           adsorption
    • Authors: Ranjan Paul; S.C. Datta; K.M. Manjaiah; Ranjan Bhattacharyya
      Pages: 19 - 25
      Abstract: Publication date: August 2017
      Source:Applied Clay Science, Volume 144
      Author(s): Ranjan Paul, S.C. Datta, K.M. Manjaiah, Ranjan Bhattacharyya
      Nanoclays, which are active component of soils, play a very important role for enzyme adsorption. To study the effect of nanoclays on enzyme adsorption, these were isolated from three genetically different Indian soils, i.e. black soil (Vertisols), red soil (Alfisols) and recent alluvial soil (Inceptisols). Then X-ray coherent particle sizes of different nanoclays (with and without amorphous aluminosilicates) before and after acid phosphatase adsorption were studied. Result showed that basal spacing of smectite present in nanoclays increased due to intercalation of enzyme molecules, whereas ‘d’ spacing in kaolinite did not change due to enzyme immobilization. Average particle size, calculated by Scherrer equation, increased due to enzyme immobilization for all nanoclays. In case of kaolinite, enzyme molecules acted as linkers and bind more than one particle together, which resulted in increased apparent particle size. Crystallite size of kaolinite was also more than that of mica or smectite. Increased average particle size after enzyme immobilization was confirmed from transmission electron microscopy (TEM) images.

      PubDate: 2017-05-12T19:02:06Z
      DOI: 10.1016/j.clay.2017.05.002
      Issue No: Vol. 144 (2017)
       
  • Water-based synthesis of TiO2/CeO2 composites supported on plasma-treated
           montmorillonite for parathion methyl degradation
    • Authors: Jiří Henych; Martin Kormunda; Martin Šťastný; Pavel Janoš; Petr Vomáčka; Jindřich Matoušek; Václav Štengl
      Pages: 26 - 35
      Abstract: Publication date: August 2017
      Source:Applied Clay Science, Volume 144
      Author(s): Jiří Henych, Martin Kormunda, Martin Šťastný, Pavel Janoš, Petr Vomáčka, Jindřich Matoušek, Václav Štengl
      The undemanding water-based synthesis was employed for the preparation of TiO2/CeO2 composites supported on Montmorillonite (MT). The prior plasma treatment of Montmorillonite led to significantly faster dispergation in water during the synthesis. The composites were used as reactive adsorbents against toxic organophosphorus pesticide parathion methyl. Efficient pillaring of the Montmorillonite layers by surface deposition of TiO2/CeO2 composites reflected in a substantially improved degradation activity towards parathion methyl in non-polar (heptane) and polar solvents (acetonitrile) investigated by HPLC/DAD. Moreover, the use of plasma treated Montmorillonite in the composites resulted in a higher degradation rate than with use of pristine MT. The formation of composites and their physicochemical properties were studied by XRD, XPS, FTIR, nitrogen physisorption, SEM and HRTEM/EDS mapping. Prior plasma treatment of the MT in a simple arrangement led to an easier formation of the composites and caused further improvement of the samples activity.
      Graphical abstract image

      PubDate: 2017-05-12T19:02:06Z
      DOI: 10.1016/j.clay.2017.05.001
      Issue No: Vol. 144 (2017)
       
  • Protein interference on aflatoxin B1 adsorption by smectites in corn
           fermentation solution
    • Authors: Sabrina Sharmeen Alam; Youjun Deng
      Pages: 36 - 44
      Abstract: Publication date: August 2017
      Source:Applied Clay Science, Volume 144
      Author(s): Sabrina Sharmeen Alam, Youjun Deng
      Corn is the main feedstock used for ethanol production in the United States. To reduce wastage and toxicity to human and animal, using aflatoxin contaminated corn in biofuel industry is thought to be rational. Yet up to three-fold of increment of the mycotoxins in the co-product have detrimental impact on animal health. It would be desirable to inactivate or to remove aflatoxins during fermentation of corn. Smectites were previously found to be highly efficient for aflatoxin B1 adsorption in ethanol and glucose solution, two major compounds in corn fermentation solution. The primary objective of the present study was to evaluate the aflatoxin B1 adsorption efficiency by smectites in real corn fermentation solution. The secondary objective was to identify any interfering compound that might hinder aflatoxin B1 adsorption. Aflatoxin B1 adsorption by smectites in fermentation solution was found to be low. A calcium smectite (3MS) had aflatoxin B1 adsorption capacity (Qmax) of 0.22molkg−1in the fermentation solution but 0.54molkg−1 in the aqueous solution. The Fourier transform infrared (FTIR) analyses indicated that some compounds from fermentation solution were adsorbed on the smectites and had irreversible bonding with the clay minerals. Those compounds competed with aflatoxin B1 for the adsorbing sites of smectites. The major infrared bands due to interfering compounds were at ~1653, 1532, 1451, and 1235cm−1. These bands appeared when smectites were added to either clean or aflatoxin B1 spiked fermentation solutions. Similar spectral bands were obtained after treating the smectites with zein, a major protein in corn. Thus, the major interfering compounds in fermentation solution were believed to be proteins. The XRD results proved the adsorption of the proteins in the interlayer of smectites. After heating at 300°C, smectites reacted with fermentation solution had d-spacing of at least 15Å, whereas the pure smectites collapsed to ~10Å. This reflected great interferences of the compounds, most possibly proteins on aflatoxin B1 adsorption by the smectites. However, despite of strong interferences, adsorption experiments suggested that smectites were still able to adsorb aflatoxin B1 to some extent. Presence of characteristic aflatoxin B1 bands at ~1595, 1383, 1362, 1304, 1272, and 1205cm−1 on smectite complexes treated in fermentation solution revealed the existence of the mycotoxins on the clay minerals. Strategies should be taken to enhance the selectivity of smectites for the aflatoxins in corn fermentation solution.

      PubDate: 2017-05-12T19:02:06Z
      DOI: 10.1016/j.clay.2017.04.024
      Issue No: Vol. 144 (2017)
       
  • One-dimensional compression behaviour of reconstituted clays with and
           without humic acid
    • Authors: Ling-Ling Zeng; Zhen-Shun Hong; Yu-Feng Gao
      Pages: 45 - 53
      Abstract: Publication date: August 2017
      Source:Applied Clay Science, Volume 144
      Author(s): Ling-Ling Zeng, Zhen-Shun Hong, Yu-Feng Gao
      It is often recognized that organic matter contained in natural clays and dredged clays is detriment to the engineering properties by increasing their compressibility. This study takes humic acid as an example to illustrate that organic matter may decrease the compressibility of reconstituted clays with a wide spectrum of predominant clay minerals: kaolinite, illite and smectite, based on experimental results from thirty types of one dimensional incremental load consolidation tests. It is found that the main factors of influencing the compression behaviour of reconstituted clays with humic acid are initial void ratio and void ratio at liquid limit. The difference in compression curves between reconstituted clays with and without humic acid can be attributed to humic acid effects on particle density and liquid limit of clays. The humic acid effect on the compressibility of smectite-dominant reconstituted clays is found to be much more sensitive than that for kaolinite- and illite-dominant reconstituted clays. A quantitative approach is also suggested to assess the compression behaviour of kaolinite- and illite-dominant reconstituted clays with humic acid using intrinsic compression concept.

      PubDate: 2017-05-12T19:02:06Z
      DOI: 10.1016/j.clay.2017.04.025
      Issue No: Vol. 144 (2017)
       
  • Exfoliation of layered double hydroxide solids into functional nanosheets
    • Authors: Ning Mao; Chun Hui Zhou; Dong Shen Tong; Wei Hua Yu; C.X. Cynthia Lin
      Pages: 60 - 78
      Abstract: Publication date: August 2017
      Source:Applied Clay Science, Volume 144
      Author(s): Ning Mao, Chun Hui Zhou, Dong Shen Tong, Wei Hua Yu, C.X. Cynthia Lin
      Exfoliated layered double hydroxide (LDH) nanosheets are a class of positively charged 2D nanoparticles. These LDH nanosheets can be used for a wide range of functional polymer nanocomposites and hierarchically structured materials. In this review we summarize and evaluate latest scientific advances in exfoliating LDH compounds, including exfoliation methods, mechanisms, properties and applications of exfoliated LDH nanosheets. Then identify the prevailing challenges and the directions of future work. In the first section of this review we dicuss the liquid exfoliation of LDH compounds, free of intercalation of organic species, in formamide, saturated aqueous L-asparagine or aqueous NaOH/urea solution with the help of ultrasonic treatment, mechanical shaking or stirring. We then examine the liquid exfoliation of LDH compounds with preceding organic species-intercalation. Such organic species include carboxylate, sulfonate, dodecyl sulfate, and amphoteric biomolecular amino acids. Next, we dicuss the exfoliation of LDH in monomer or polymer to form LDH/polymer nanocomposites. The polymer nanocomposites include LDH/polyethylene, LDH/polyethylene-graft-maleic anhydride, LDH/poly (vinyl alcohol), LDH/polystyrene, LDH/poly (ethylene terephthalate), LDH/poly (butylene adipate-co-terephtalate), LDH/poly ((butylene succinate)-co-adipate), LDH/poly caprolactone, LDH/poly (l-lactic) acid, LDH/acrylic polymer, LDH/polyacrylamide, LDH/poly(amide-imide) and LDH/poly (methyl methacrylate). The properties of these LDH/polymer nanocomposites are also discussed. In addition to polymer nanocomposites, recent studies indicate that the exfoliated LDH nanosheets can be used in electrorheological media, magnetic materials, low infrared emissivity materials, catalysts, and biosensors. The literature survey and analysis suggests that future work should place emphasis on the innovation of green and cost-effective exfoliation methods, and deepen understanding of the interfacial interactions between the LDH nanosheets and organic species/polymers, and the new assembly tactics of exfoliated LDH nanosheets with functional molecules or nanomaterials to expand applications.
      Graphical abstract image

      PubDate: 2017-05-17T19:32:21Z
      DOI: 10.1016/j.clay.2017.04.021
      Issue No: Vol. 144 (2017)
       
  • Kaolinite-alunite association in late Gothic white grounds from Slovakia:
           A local peculiarity in painting technology
    • Authors: David Hradil; Janka Hradilová; Petr Bezdička; Irena Matulková
      Pages: 79 - 87
      Abstract: Publication date: August 2017
      Source:Applied Clay Science, Volume 144
      Author(s): David Hradil, Janka Hradilová, Petr Bezdička, Irena Matulková
      In European Gothic paintings, the use of materials other than calcium carbonates (chalk) or calcium sulphates (gypsum) in painting preparations was rare. Therefore, alternatively used materials, such as, e.g., white clays, can be seen as peculiarities, which correspond to the local availability or artist's preference. In this study white chalk-based grounds from masterpieces attributed to the workshop of Master Paul from Levoča, Slovakia, were investigated. It was motivated by the assumption of restorers that Master Paul complemented the chalk ground by more malleable white clay to achieve a very fine modelling of his polychrome statues. The results were compared with other artworks, where the use of white clays in grounds was previously indicated, and with reference samples of kaolin from Central-European sources. It was found that detailed microanalysis of the white earths in paintings leads to distinguishing of regional provenances. While in Czech paintings, either from Gothic or Baroque periods, residual kaolins from West-Bohemian deposits were identified, in the late Gothic Slovak paintings white earths came from hydrothermal kaolin deposits situated, most probably, in Tokaj Mountains, Hungary. Here presented finding is probably the first ever evidence of natural alunite and hydrothermal kaolinite in painted artworks, where they were applied as white pigments.
      Graphical abstract image

      PubDate: 2017-05-17T19:32:21Z
      DOI: 10.1016/j.clay.2017.05.004
      Issue No: Vol. 144 (2017)
       
  • Intercalation of vermiculite in presence of surfactants
    • Authors: Sevim
      Abstract: Publication date: 15 September 2017
      Source:Applied Clay Science, Volume 146
      Author(s): Sevim İşçi
      Vermiculite was modified with surfactants in order to enable intercalation of vermiculite layers. Since vermiculite has negative charges on its surfaces, it was expected that cationic surfactant would expand the clay mineral layers more than an anionic surfactant. Nevertheless, negative parts of the anionic surfactants interacted with the positively charged edges of vermiculite and caused to super lattice structure so, unexpectedly the expansion of the layers was determined to be fully collapsed phase of vermiculite. Colloidal and structural properties of vermiculite dispersions were examined in presence of anionic, cationic and nonionic surfactants. The results showed that cationic surfactant covered the surface of the vermiculite with a second layer but the expansion of the clay mineral layer was limited compared to the anionic surfactant. The anionic surfactant produced electrostatic interaction with the positively charged edges of vermiculite and fully expanded the layer structure of the vermiculite.
      Graphical abstract image

      PubDate: 2017-06-01T16:08:31Z
       
  • Physical and strength development in lime treated gypseous soil with fly
           ash — Micro-analyses
    • Authors: Arvind Kumar; Jha P.V. Sivapullaiah
      Abstract: Publication date: 1 September 2017
      Source:Applied Clay Science, Volume 145
      Author(s): Arvind Kumar Jha, P.V. Sivapullaiah
      An attempt has been made to examine the role of fly ash content (0–30%) to control undesirable strength loss in lime–treated expansive soil containing gypsum (0–6%) after curing for different periods up to one year. Further, detailed experimental investigations have been performed to assess the plasticity, swell index and compaction behavior of soil treated with these additives. Results of the strength behavior revealed that a significant effect of higher fly ash content in the strength development of lime–treated soil is observed after longer curing periods. Presence of increasing amounts of gypsum accelerates early strength gain initially, but reduces long–term strength gain in soil–lime–fly ash mixes. Fly ash improves the strength of lime–treated gypseous soil. However, beneficial use of fly ash to improve the strength of lime treated gypseous soil depends on the amount of gypsum present in the soil and length of curing periods. Micro–analyses (XRD and SEM) revealed that the strength development is controlled by reaction products formed such as cementitious compounds and ettringite crystals.

      PubDate: 2017-05-27T18:18:32Z
       
 
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
Fax: +00 44 (0)131 4513327
 
Home (Search)
Subjects A-Z
Publishers A-Z
Customise
APIs
Your IP address: 54.145.85.87
 
About JournalTOCs
API
Help
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-2016