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  Subjects -> ENGINEERING (Total: 2410 journals)
    - CHEMICAL ENGINEERING (206 journals)
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    - ENGINEERING (1268 journals)
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ENGINEERING (1268 journals)                  1 2 3 4 5 6 7 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 8)
3D Research     Hybrid Journal   (Followers: 21)
AAPG Bulletin     Hybrid Journal   (Followers: 8)
AASRI Procedia     Open Access   (Followers: 15)
Abstract and Applied Analysis     Open Access   (Followers: 3)
Aceh International Journal of Science and Technology     Open Access   (Followers: 3)
ACS Nano     Hybrid Journal   (Followers: 281)
Acta Geotechnica     Hybrid Journal   (Followers: 7)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 7)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 3)
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: 7)
Advanced Journal of Graduate Research     Open Access  
Advanced Science     Open Access   (Followers: 5)
Advanced Science Focus     Free   (Followers: 5)
Advanced Science Letters     Full-text available via subscription   (Followers: 10)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 7)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 17)
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Advances in Complex Systems     Hybrid Journal   (Followers: 7)
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Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 13)
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Advances in Physics Theories and Applications     Open Access   (Followers: 14)
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Advances in Remote Sensing     Open Access   (Followers: 45)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aerobiologia     Hybrid Journal   (Followers: 3)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 6)
AIChE Journal     Hybrid Journal   (Followers: 35)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access   (Followers: 1)
Alexandria Engineering Journal     Open Access   (Followers: 1)
AMB Express     Open Access   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 26)
American Journal of Engineering and Applied Sciences     Open Access   (Followers: 10)
American Journal of Engineering Education     Open Access   (Followers: 11)
American Journal of Environmental Engineering     Open Access   (Followers: 16)
American Journal of Industrial and Business Management     Open Access   (Followers: 24)
Annals of Combinatorics     Hybrid Journal   (Followers: 4)
Annals of Pure and Applied Logic     Open Access   (Followers: 3)
Annals of Regional Science     Hybrid Journal   (Followers: 7)
Annals of Science     Hybrid Journal   (Followers: 7)
Antarctic Science     Hybrid Journal   (Followers: 1)
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: 18)
Applied Clay Science     Hybrid Journal   (Followers: 6)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 11)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 4)
Applied Nanoscience     Open Access   (Followers: 8)
Applied Network Science     Open Access   (Followers: 3)
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Physics Research     Open Access   (Followers: 5)
Applied Sciences     Open Access   (Followers: 3)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 5)
Arab Journal of Basic and Applied Sciences     Open Access  
Arabian Journal for Science and Engineering     Hybrid Journal   (Followers: 5)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 5)
Archives of Foundry Engineering     Open Access  
Archives of Thermodynamics     Open Access   (Followers: 9)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
ASEE Prism     Full-text available via subscription   (Followers: 3)
Asia-Pacific Journal of Science and Technology     Open Access  
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: 9)
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: 9)
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: 5)
Batteries     Open Access   (Followers: 6)
Bautechnik     Hybrid Journal   (Followers: 1)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 28)
Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 4)
BER : Manufacturing Survey : Full Survey     Full-text available via subscription   (Followers: 1)
BER : Motor Trade Survey     Full-text available via subscription  
BER : Retail Sector Survey     Full-text available via subscription   (Followers: 1)
BER : Retail Survey : Full Survey     Full-text available via subscription   (Followers: 1)
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)
Beyond : Undergraduate Research Journal     Open Access  
Bhakti Persada : Jurnal Aplikasi IPTEKS     Open Access  
Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access   (Followers: 1)
Bilge International Journal of Science and Technology Research     Open Access  
Biofuels Engineering     Open Access   (Followers: 1)
Biointerphases     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 11)
Biomedical Engineering     Hybrid Journal   (Followers: 15)
Biomedical Engineering     Hybrid Journal   (Followers: 1)
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: 21)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 37)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 8)
Biomedical Science and Engineering     Open Access   (Followers: 4)
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Open Access   (Followers: 2)
Biotechnology Progress     Hybrid Journal   (Followers: 40)
Bitlis Eren University Journal of Science and Technology     Open Access  
Boletin Cientifico Tecnico INIMET     Open Access  
Botswana Journal of Technology     Full-text available via subscription   (Followers: 1)
Boundary Value Problems     Open Access   (Followers: 1)
Brazilian Journal of Science and Technology     Open Access   (Followers: 2)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 12)
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 13)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 14)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal   (Followers: 2)
Canadian Geotechnical Journal     Hybrid Journal   (Followers: 31)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 43)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 6)
Case Studies in Thermal Engineering     Open Access   (Followers: 6)
Catalysis Communications     Hybrid Journal   (Followers: 6)
Catalysis Letters     Hybrid Journal   (Followers: 2)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 7)
Catalysis Science and Technology     Free   (Followers: 8)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysis Today     Hybrid Journal   (Followers: 7)
CEAS Space Journal     Hybrid Journal   (Followers: 2)
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 3)
Central European Journal of Engineering     Hybrid Journal  
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: 3)
CienciaUAT     Open Access   (Followers: 1)
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: 13)
City, Culture and Society     Hybrid Journal   (Followers: 22)
Clay Minerals     Full-text available via subscription   (Followers: 10)
Clean Air Journal     Full-text available via subscription   (Followers: 1)
Clinical Science     Hybrid Journal   (Followers: 9)
Coal Science and Technology     Full-text available via subscription   (Followers: 3)
Coastal Engineering     Hybrid Journal   (Followers: 11)
Coastal Engineering Journal     Hybrid Journal   (Followers: 6)
Coatings     Open Access   (Followers: 4)
Cogent Engineering     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 4)
Color Research & Application     Hybrid Journal   (Followers: 3)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 14)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 15)
Communications Engineer     Hybrid Journal   (Followers: 1)
Communications in Information Science and Management Engineering     Open Access   (Followers: 4)
Communications in Numerical Methods in Engineering     Hybrid Journal   (Followers: 2)
Components, Packaging and Manufacturing Technology, IEEE Transactions on     Hybrid Journal   (Followers: 28)
Composite Interfaces     Hybrid Journal   (Followers: 7)
Composite Structures     Hybrid Journal   (Followers: 286)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 219)
Composites Part B : Engineering     Hybrid Journal   (Followers: 253)
Composites Science and Technology     Hybrid Journal   (Followers: 198)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access   (Followers: 1)
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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: 8)
Computer Science and Engineering     Open Access   (Followers: 19)
Computers & Geosciences     Hybrid Journal   (Followers: 31)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 8)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 5)
Computers and Geotechnics     Hybrid Journal   (Followers: 11)
Computing and Visualization in Science     Hybrid Journal   (Followers: 7)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 34)
Conciencia Tecnologica     Open Access  
Concurrent Engineering     Hybrid Journal   (Followers: 3)

        1 2 3 4 5 6 7 | Last

Journal Cover
Applied Clay Science
Journal Prestige (SJR): 0.992
Citation Impact (citeScore): 4
Number of Followers: 6  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0169-1317
Published by Elsevier Homepage  [3159 journals]
  • Analytical and experimental analyses for mechanical and biological
           characteristics of novel nanoclay bio-nanocomposite scaffolds fabricated
           via space holder technique
    • Abstract: Publication date: 1 December 2018Source: Applied Clay Science, Volume 165Author(s): S. Sahmani, M. Shahali, A. Khandan, S. Saber-Samandari, M.M. Aghdam In the present work, bioactive nanoclay-TiO2 (NC-T) bio-nanocomposite scaffolds containing different TiO2 weight fractions are fabricated spacer for bone tissue engineering applications via the space holder technique using NaCl particles as the. The microstructure, surface morphology (porosity) and bioactivity potential of the manufactured bio-nanocomposite scaffolds are examined using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF), energy dispersive spectroscopy (EDS), and inductively-coupled plasma optical emission spectroscopy (ICP-OES) techniques. The scaffold with optimized mechanical properties is predicted as NC-15wt%T with proper interconnected porosity and micro/macro pore size within the range of 1–2 (μm) and 3–5 (μm), respectively. Also, its mechanical properties including compressive strength, elastic modulus and crystallite size are extracted equal to 5.74 MPa, 438 MPa and 70–120 nm, respectively. The feasibility of the fabricated scaffolds for bioactive bone tissue engineering application (apatite deposition) is also evaluated using simulated body fluid (SBF) and physiological saline (PS) solutions. At the end, the nonlinear bending and vibration characteristics of an axially loaded beam-type bone implant made of the NC-T/NaCl bio-nanocomposite scaffolds are predicted analytically. In general view, the obtained results indicate that the NC-15wt%T/NaCl bio-nanocomposite scaffold may have excellent advantages for future research in bone regenerative applications.
       
  • An insight into the comprehensive application of opal-palygorskite clay:
           Synthesis of 4A zeolite and uptake of Hg2+
    • Abstract: Publication date: 1 December 2018Source: Applied Clay Science, Volume 165Author(s): Zongshan Wu, Tianhu Chen, Haibo Liu, Can Wang, Peng Cheng, Dong Chen, Jingjing Xie To availably utilize opal-palygorskite clay, dry beneficiation technique was applied to separate opal and palygorskite clay. Based on separated opal from opal-palygorskite clay, 4A zeolite was successfully synthesized by using a hydrothermal method. Box-Behnken was used to optimize Na2O/SiO2, H2O/Na2O and SiO2/Al2O3 with cation exchange capacity (CEC) as the response value. The optimum parameters was determined to be Na2O/SiO2 = 1.0, H2O/Na2O = 40, and SiO2/Al2O3 = 2.0, and CEC got the maximum of 2.99 mmol/(g·dry zeolite) under the conditions. The as-obtained 4A zeolite was characterized by using X-ray diffraction (XRD), thermo gravimetric analysis (TG), acid-base titration, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and then was applied to remove Hg2+ from aqueous solution. The maximum removal capacity of Hg2+ was 41.99 mg/g and adsorption equilibrium was obtained with contact time of 2 h. Effects of pH, ionic strength, temperatures, metal cations, strippant kinds and cycle times on removal behaviors of Hg2+ onto 4A zeolite were investigated by batch experiments. The kinetics and isotherms of Hg2+ adsorption fitted well by pseudo-second kinetic and Langmuir models. When Hg2+-adsorbed 4A zeolite was desorbed using 1 mol/L NaNO3 solution, the adsorption efficiency was maintained about 70% after four cycles.
       
  • Reinforcing effect of organoclay in nitrile rubber - Effect of mill mixing
           and latex stage mixing
    • Abstract: Publication date: 1 December 2018Source: Applied Clay Science, Volume 165Author(s): Bhavya Bhadran, Dhanya Vijayan, Neena George, C.S. Julie Chandra, P.M. Sabura Begum, Rani Joseph The urge for materials with diverse applications has paved the way to fabricate composites based on, one-dimensional filler like nanoclays. The main aim of the work was to study the effect of mill mixing and latex stage mixing on the reinforcing effect of organoclay in Nitrile Rubber. The non-ionic surfactant assisted latex stage mixing route proved to be more efficient and feasible when compared to mill mixing. Mechanical properties were measured and, about 150% increase in tensile strength and 79% increase in tensile modulus were obtained for the latex based composites at 3 phr clay loading when compared to neat rubber composites. Dynamic strain sweep tests revealed that, the low strain modulus for latex mixed composites was higher. Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC) results indicated that the addition of organoclay hardly affected the thermal properties of the rubber matrix. Transmission Electron Micrographs revealed homogeneous dispersion of partially exfoliated and intercalated nanoclay platelets in the latex state substantiating the viability of latex mixing over mill mixing. The extent of reinforcement in the nanocomposites was also analyzed with the help of different micromechanical models.Graphical abstractUnlabelled Image
       
  • Green synthesis of nano-muscovite and niter from feldspar through
           accelerated geomimicking process
    • Abstract: Publication date: 1 December 2018Source: Applied Clay Science, Volume 165Author(s): Jiangyan Yuan, Jing Yang, Hongwen Ma, Shuangqing Su, Qianqian Chang, Sridhar Komarneni Synthesis of nano-muscovite has significant implications for applications such as electrical insulation, composite materials and paper-making. In this study, an energy-saving, efficient and sustainable route to synthesize muscovite from K-feldspar was developed by mimicking natural chemical weathering process of feldspar. Here, well-crystallized nano-muscovite of uniform flaky morphology with a thickness of 20–40 nm was obtained at 250 °C in just 18 h after treatment of K-feldspar under hydrothermal conditions. Moreover, additional potassium generated by the dissolution of K-feldspar into solution was collected as KNO3. This is truly a green chemical process for the synthesis of muscovite and niter in a closed system as it not only conserved all the starting chemicals for reuse but also generated two useful by-products, niter and CaSiO3.Graphical abstractUnlabelled Image
       
  • The adsorption of nortriptyline on montmorillonite, kaolinite and gibbsite
    • Abstract: Publication date: 1 December 2018Source: Applied Clay Science, Volume 165Author(s): Shahrzad Sadri, Bruce B. Johnson, Maika Ruyter-Hooley, Michael J. Angove Nortriptyline (NT) is a tricyclic antidepressant in common use in many countries. Its presence in drinking water indicates that current wastewater treatment practices fail to remove it effectively from effluents with consequent adverse effects on aquatic organisms. Since mineral surfaces readily remove many organic substance from effluent streams, this research sought to study the adsorption of NT on montmorillonite, kaolinite and gibbsite. Adsorption edge and isotherm experiments were performed to determine the relative effectiveness of the three substrates for NT removal, and X-ray diffraction (XRD) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy were used in order to gain an understanding of the mode of adsorption. Adsorption of NT on all three substrates was effectively independent of pH in the range from 3 to 12. Both montmorillonite and kaolinite proved to be excellent adsorbents of NT with maximum adsorption capacities of 19.3 and 6.4 μmol m−2 respectively at pH 6.0, but gibbsite adsorbed relatively little. The XRD and ATR-FTIR results indicated that NT formed as a multilayer on montmorillonite with no evidence of intercalation. Both electrostatic and hydrophobic interactions appeared to play important roles in the adsorption.
       
  • The zone of incipient 40Ar* loss-monitoring 40Ar* degassing behavior in a
           contact metamorphic setting
    • Abstract: Publication date: 1 December 2018Source: Applied Clay Science, Volume 165Author(s): Annette Süssenberger, Klaus Wemmer, Susanne Theodora Schmidt The 40Ar* retentivity behavior was studied in the contact metamorphic aureole of the Torres del Paine intrusion (51°S, Chile) and provides constraints on the closure temperature in contact metamorphic settings. The temperature conditions of the regional anchizonal to epizonal metamorphosed pelitic host rock and the contact metamorphic pelite were recorded by illite crystallinities (Kübler Index) and by Raman spectroscopy on carbonaceous matter. K/Ar age determinations were carried out on illite fine fractions (
       
  • Mechanochemical activation of phlogopite to directly produce slow-release
           potassium fertilizer
    • Abstract: Publication date: 1 December 2018Source: Applied Clay Science, Volume 165Author(s): Ahmed Said, Qiwu Zhang, Jun Qu, Yanchu Liu, Zhiwu Lei, Huimin Hu, Zhigao Xu Phlogopite, one trioctahedral mica, was activated by solvent-free ball milling to serve directly as slow-release potassium fertilizer. Before the final breakdown of the crystal structure, phase transformation of trigonal phlogopite into monoclinic by milling at 300 rpm for 120 min was observed for the first time. Different solubility of the amorphous product and monoclinic crystalline product in water or 2% citric acid was also obtained. The content of water soluble potassium (quick acting potassium) and 2.0% citric acid soluble one (slow release potassium) in the products could be easily changed by adjusting the milling speed depending on the requirement for plant growth. 100.0% K extraction in 2.0% citric acid solution from the amorphous sample and near 30% K extraction in water from the sample milled at 300 rpm was achieved. Several analytical methods such as XRD, SEM, FT-IR and TG-DTG were used to characterize the activated sample and to understand the reason for the easier dissolution of potassium. The proposed process was economical and environment-friendly, which could help to maintain a balanced supply of potassium fertilizer for sustainable development of agriculture by compensating partially current high-cost chemical fertilizer.
       
  • Kinetic and thermodynamic assessment on isoniazid/montmorillonite
           adsorption
    • Abstract: Publication date: 1 December 2018Source: Applied Clay Science, Volume 165Author(s): Esperanza Carazo, Ana Borrego-Sánchez, Rita Sánchez-Espejo, Fátima García-Villén, Pilar Cerezo, Carola Aguzzi, César Viseras The properties of montmorillonite (Mt) as a natural nanocarrier of drugs have been fully reported. Isoniazid (INH), a first-line tuberculostatic drug, was intercalated into this inorganic matrix and the equilibrium and thermodynamic aspects of the adsorption process were evaluated. Adsorption experiments were performed at different times and temperatures in aqueous medium. The overall adsorption process was the result of two simple processes: INH adsorption on the activated sites of Mt. followed by a slight precipitation phase of INH molecules over the adsorbed monolayer. Formation of the nanohybrid was spontaneous, exothermic and exoentropic, obtaining an increase in the thermodynamic stability of the system. The hybrid material (Mt-INH) was successfully prepared with high drug loading. Solid state characterization of the pure materials and the resulting nanohybrid was carried out. Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TGA), differential scanning calorimetry (DSC), surface charge, X-ray powder diffraction (XRPD) and high resolution transmission electron microscopy (HRTEM) coupled with energy dispersive spectroscopy (XEDS) and elemental X-ray maps served to correctly resolve the structure of the nanohybrid and to assess the nature and degree of the drug-clay interactions.Graphical abstractUnlabelled Image
       
  • Texture profile analysis (TPA) of clay/seawater mixtures useful for peloid
           preparation: Effects of clay concentration, pH and salinity
    • Abstract: Publication date: 1 December 2018Source: Applied Clay Science, Volume 165Author(s): Manuel Pozo, Francisco Armijo, Francisco Maraver, José Manuel Ejeda, Iluminada Corvillo The liquid phase of a peloid can be mineral-medicinal, marine or salt lake water. This study was designed to experimentally determine the interaction between two bentonites and one sepiolite, and seawater as well as dilutions thereof to verify the effect of salinity on instrumental texture measurements in clay-water mixtures prepared with these components. In all the clay-water mixtures tested, instrumental hardness and adhesiveness decreased with water content. For a given instrumental hardness or adhesiveness, bentonite retained more water in the mixture with distilled water than with seawater. In contrast, sepiolite retained more water in the mixture with seawater than with distilled water. These differences affected the thermal behaviour of the clay-water mixtures. Instrumental hardness and adhesiveness curves may be a suitable tool to tailor concentrated dispersions and after maturation could be used in thalassos and medical spas as peloids.
       
  • Influence of thermal loading on index and physicochemical properties of
           Barmer bentonite
    • Abstract: Publication date: 1 December 2018Source: Applied Clay Science, Volume 165Author(s): Rohini C. Kale, K. Ravi The concept of the deep geological repository (DGR) has been widely accepted for the safe disposal of high-level nuclear waste (HLW). Compacted bentonite/bentonite-sand mixture is considered as buffer material in the deep geological repository due to its favorable physicochemical and hydro-mechanical properties. The bentonite buffer is expected to be exposed to high temperature for a long duration because the heat released from the waste canister and due to the geo-thermal gradient inside the deep geological repository. The temperature from the waste canister can go initially as high as 200 °C and probably reduce to ambient temperature upon the decay of the waste material. This long duration temperature variation induces a thermal loading on the bentonite buffer, affecting its index, physicochemical and hydro-mechanical properties. Hence there is a need to critically examine the effect of the induced thermal loading on the long-term performance of the buffer as this study will be quite useful for the preliminary understanding before fixing its design values for the use as a part of engineered barrier system (EBS) in DGR. In the present study, two bentonites (Barmer 1 (B1) and Barmer 2 (B2)) from Barmer district of Rajasthan, India, was subjected to four temperature levels, i.e., 60 °C, 110 °C, 150 °C and 200 °C for a time duration of 3, 7, 15, 21, 28 days. Changes in the physicochemical properties of both bentonites were observed and reported. The decrease in the Atterberg's limit, swelling, specific gravity, optimum moisture content, pH and exchangeable monovalent cation and increase in maximum dry density was recorded with an increase in temperature as well as with the duration of heating.
       
  • Green synthesis and characterization of colored Tunisian clays: Cosmetic
           applications
    • Abstract: Publication date: 1 December 2018Source: Applied Clay Science, Volume 165Author(s): S. Gamoudi, E. Srasra Colored clays are prepared by a solid state reaction of dried leaves of flowers with a Tunisian clay used for pharmaceutical and cosmetic applications. The structural properties, photo- and thermal stability of the resulting samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Differential scanning calorimetry analysis (DSC) and UV–visible spectroscopy. The mineralogical structure, physicochemical properties and pharmacopoeial tests of the purified clay suggested that this clay mineral can function in cosmetic products. The XRD results of colored clays revealed a slight difference in values of basal spacing d001 when compared to values obtained from purified clay. FTIR analysis confirmed changes in functional groups and surface properties of purified clay. DSC results proved a high thermal stability for purified and modified clays. UV–visible spectra of colored materials displayed a new band compared to purified clay in 400–700 nm wavelength region. The microbiological tests revealed the suitability of all clays for the cosmetic products.Graphical abstractUnlabelled Image
       
  • A comparative study about superamphiphobicity and stability of
           superamphiphobic coatings based on Palygorskite
    • Abstract: Publication date: 1 December 2018Source: Applied Clay Science, Volume 165Author(s): Jie Dong, Qing Zhu, Qingyun Wei, Baohui Zheng, Shangbin Li, Junping Zhang Naturally rich clay minerals are receiving increasing attention recently in preparation of super anti-wetting coatings, superhydrophobic and superamphiphobic ones. Clay minerals are a class of very promising natural building blocks for constructing microstructures of the coatings. Clay minerals such as Palygorskite (Pal), kaolinite, halloysite nanotubes and montmorillonite have been used. However, the comparative study about the effects of source of clay minerals on properties of the coatings remains a gap to be filled. Here, the first comparative study about superamphiphobicity and stability of superamphiphobic coatings based on Pal from different sources was reported. The superamphiphobic coatings were fabricated by hydrolytic condensation of silanes in the presence of Pal followed by spray-coating the as-prepared dispersions onto substrates. Five Pal samples from Anhui, Jiangsu and Gansu Provinces of China were chosen, and their effects on superamphiphobicity and stability of the coatings were studied using various analytical techniques including scanning electron microscopy and X-ray photoelectron spectroscopy. The superamphiphobicity and stability depend on micro/nanostructures of the coatings, originating from the microstructures of Pal. The Pal sample from Anhui is more suitable for preparing superamphiphobic coatings than the others because of the higher Mg content and the higher aspect ratio of the Pal nanorods. The finding will shed light on the progress of the clay-based super anti-wetting coatings.Graphical abstractUnlabelled Image
       
  • Montmorillonite as a reinforcement and color stabilizer of gelatin films
           containing acerola juice
    • Abstract: Publication date: 1 December 2018Source: Applied Clay Science, Volume 165Author(s): Hálisson L. Ribeiro, Edy S. Brito, Men de sá M. Souza Filho, Henriette M.C. Azeredo Montmorillonite (Mt) is well known as reinforcing agent in films. Moreover, it stabilizes anthocyanin pigments. In this study, Mt has been added as both reinforcement and color stabilizer to gelatin films containing acerola juice. Films were produced with different Mt concentrations (0–6.5% on gelatin). Increasing Mt contents resulted in enhanced tensile strength and modulus, although the elongation has been decreased. Mt also reduced the water vapor permeability in up to 45%. Mt presented two effects on film color: first, it changed its color from yellowish to red; and second, it stabilized film color throughout storage, mainly when added at 3.9%. It has been suggested that metals from Mt (such as Fe3+ or Al3+) may have formed complexes to anthocyanins, changing and stabilizing their color.Graphical abstractUnlabelled Image
       
  • Dispersive solid phase extraction/fluorescence analysis of riboflavin
           using sepiolite as sorbent
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Rocío Mateos, Soledad Vera-López, Ana María Díez-Pascual, María Paz San Andrés The use of a natural clay, sepiolite (Sep), and graphene (G)/Sep mixtures as sorbents for the solid phase extraction in dispersive mode (dSPE) with fluorescence detection of a biologically interesting molecule, riboflavin, is reported. The retention of riboflavin by Sep is quantitative with different volumes of the sample and 10–50 mg of the clay. The desorption process has been performed using aqueous solutions of surfactants of different nature: anionic sodium dodecylsulphate (SDS), cationic hexadecyltrimethylammonium chloride (CTAC) and non-ionic polyoxyethylene-23-lauryl eter (Brij L23). The non-ionic surfactant provides the highest riboflavin recoveries; upon optimization of the process, that takes less than half an hour, an extraction yield of 93% was attained using 40 mM Brij L23. The developed method has been applied to the analysis of beer, soya drink and infant milk samples with excellent accuracy (recoveries of 100%) and very good precision, avoiding the interferences of the matrix components that hinder the direct fluorescence analysis of riboflavin.Graphical abstractUnlabelled Image
       
  • Cobalt-doped Ni–Mn layered double hydroxide nanoplates as
           high-performance electrocatalyst for oxygen evolution reaction
    • Abstract: Publication date: Available online 1 August 2018Source: Applied Clay ScienceAuthor(s): Yi Wang, Xiaohe Liu, Ning Zhang, Guanzhou Qiu, Renzhi Ma Active, stable and low-cost electrocatalysts are in high demand to replace the traditional noble metal catalysts towards efficient water splitting. Here we report a type of nickel-manganese (Ni–Mn) layered double hydroxide (LDH) with controllable doping content of cobalt as an oxygen evolution reaction (OER) electrocatalyst with excellent performance in alkaline media. Co-doped Ni–Mn LDH nanoplates were synthesized via a facile hydrothermal method. It was found that the doping content of cobalt significantly affected the OER activities. The best electrocatalyst was based on a doping ratio of 21.1% Co, exhibiting a low overpotential of ~310 mV at a current density of 10 mA cm−2, a Tafel slope of ~59 mV dec−1 as well as excellent stability. This work demonstrates a facile synthetic method of rationally doping transition-metal hydroxides to develop new OER electrocatalysts with remarkable performance in water splitting.Graphic abstractNiMn LDH nanoplates with tunable cobalt doping content could be successfully prepared via a simple hydrothermal method. The doping content of cobalt in NiMn LDH nanoplates has a significant influence on their OER activities. The 21.1% Co-doped NiMn LDH exhibited excellent OER efficiency realizing an overpotential of 310 mV, Tafel plot of 59 mV/decade and a stable operating potential without fluctuating above 5 mV for 9 h. This work demonstrates a facile synthetic method and doping strategy for exploring electrocatalysts with remarkable OER performance, which will promote the development of transition-metal based hydroxides as high-performance electrocatalyst for water splitting.Unlabelled Image
       
  • Mechanochemical synthesis of CdS/MgAl LDH-precursor as improved
           visible-light driven photocatalyst for organic dye
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Zhao Li, Min Chen, Ziqiang Ai, Lei Wu, Qiwu Zhang CdS/Mg–Al LDH-precursor composites were synthesized by a mechanochemical method. X-ray diffraction analysis confirmed the formation of the CdS/Mg–Al LDH-precursor composites. SEM-EDS analysis demonstrated the uniform distribution of CdS nanoparticles among LDH-precursor matrix. The obtained nanocomposites exhibited much higher photocatalytic activities on methylene blue (MB) degradation under visible light irradiation. The high photocatalytic activity could be ascribed to the special structure of the wide-distribution of CdS nanoparticles within LDH-precursor matrix. A detailed investigation on the mechanism and the reaction kinetics for the photocatalytic process were also performed. This work provides a very simple and environment-friendly way to prepare a series of photocatalysts based on LDH-precursor with transition metal sulfide well dispersed inside.
       
  • Synthesis of palygorskite/polystyrene nanocomposites without crosslinked
           network via in-situ radical bulk polymerization technique
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Peng Liu, Hongxing Wang, Changou Pan, Mingliang Pei, Aiqin Wang Clay/polymer nanocomposites have attracted more and more attention owing to their superior performance for potential applications. The in-situ polymerization has been regarded as the promising strategy for the mass production of the clay/polymer nanocomposites with well-defined interfacial property. However, the gelation usually accompanies with the grafting reaction during the polymerization especially for the high aspect ratio nanomaterials, resulting to crosslinked network. In order to solve the problem, the thoil-modified palygorskite nanorods (Pal-SH) were prepared as clay-based chain transfer reagent for the radical bulk polymerization of styrene, as an example. With different dosages of the Pal-SH nanorods from 0.5% to 1.0% and 2.0%, well-defined polystyrene grafted palygorskite nanorods (Pal-PS) were obtained without crosslinked network, with high grafting percentage (PG%) of 40.0, 43.2, and 51.3% respectively. The proposed approach provides a promising technique for the mass production of high aspect ratio nanomaterials-based polymer nanocomposites with well-defined interfacial property, especially avoiding crosslinked network.Graphical abstractUnlabelled Image
       
  • Effects of dietary sepiolite usage on performance, carcass
           characteristics, blood parameters and rumen fluid metabolites in Merino
           cross breed lambs
    • Abstract: Publication date: Available online 30 July 2018Source: Applied Clay ScienceAuthor(s): Ender Burçak, Sakine Yalçın The aim of this experiment was to determine the effects of dietary sepiolite supplementation on performance, carcass characteristics, blood parameters and rumen fluid metabolites in Merino cross breed lambs. For this purpose, a total of 21 weaned lambs, which were 3–3.5 months of age were allocated to one control group and two treatment groups each containing 7 lambs. The experiment lasted for a total of 90 days, of which the adaptation and experimental periods were 22 and 68 days, respectively. Pelleted alfalfa and concentrates were given to lambs individually. Concentrate diets of first and the second treatment groups were supplemented with 1 and 2% sepiolite as top dressed, respectively. There were no significant differences observed in body weights, body weight gains, hot and cold carcass yields, meat pH and meat composition among the groups. Relative weights of internal organs and carcass parts were also not affected by sepiolite supplementation. The addition of 1 and 2% sepiolite to the diets of animals increased the consumption of concentrates and total dry matter intake (P 
       
  • Research progress on the raw and modified montmorillonites as adsorbents
           for mycotoxins: A review
    • Abstract: Publication date: Available online 30 July 2018Source: Applied Clay ScienceAuthor(s): Yan Li, Guangyan Tian, Gongyue Dong, Shansong Bai, Xiaoyu Han, Jinsheng Liang, Junping Meng, Hong Zhang Mycotoxin, as one of the most common pollutants in animal feeds, is harmful and widespread, which has severely restricted the healthy development of livestock and feed industries. Therefore, to remove mycotoxins from animal feeds is becoming an intractable problem. Currently, naturally occurred clay minerals, especially montmorillonite (Mt), have been considered as promising adsorbents for high-efficient removal of toxic mycotoxins from animal feeds because they are eco-friendly, low-cost, and highly efficient for adsorption of mycotoxin. It is important to timely summary the latest researches, which helps the followers to develop or exploit other new adsorbents for mycotoxins. Thus, this review intensively summarized the latest research progress on raw Mt and the modified ones as adsorbents for mycotoxins, and especially on the adsorption mechanism. In addition, the future applications of Mt as adsorbents for removal of mycotoxins were discussed.Graphical abstractUnlabelled Image
       
  • Clay dosage and water/cement ratio of clay-cement grout for optimal
           engineering performance
    • Abstract: Publication date: Available online 29 July 2018Source: Applied Clay ScienceAuthor(s): Cong Zhang, Junsheng Yang, Xuefeng Ou, Jinyang Fu, Yipeng Xie, Xiong Liang Clay-cement grout is widely used in grouting engineering, but the varied field demands are often difficult to satisfy since the properties of the grout are affected by multiple factors and cannot be simply predicted. This Note presents an experimental study to investigate the effect of clay dosage and water/cement ratios on the performance of clay-cement grout. Twenty batches of grout samples were designed by varying the water/cement ratios from 0.5 to 2 and clay dosages from 5% to 45% which are in the ranges commonly used in engineering practice. The results showed that the optimal performance of the clay-cement grout was highly dependent on the clay dosage and water/cement ratio. In general, higher clay dosage and lower water/cement ratio improved the stability and led to lower permeability of the clay-cement grout but led to a poor performance in terms of fluidity and strength. A methodology was proposed for determining the optimum clay dosage and water/cement ratio to fulfill various field demands. The applicability and economic benefits of the presented method were evaluated by a detailed case study which also demonstrated the effectiveness of the framework for the determination of the optimum dosage of ingredients for clay-cement grout.
       
  • LDH-VB9-TiO2 and LDH-VB9-TiO2/crosslinked PVA nanocomposite prepared via
           facile and green technique and their photo-degradation application for
           methylene blue dye under ultraviolet illumination
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Shadpour Mallakpour, Masoud Hatami Vitamin B9 (VB9) as a biological molecule was used for the intercalation of MgAl-layered double hydroxide (LDH) which can increase the active sites and organic nature of LDH samples. Then, the LDH-VB9-TiO2 composite was synthesized with mass ratio of LDH-VB9:TiO2 equal to 1:1 through ultrasonic technique as a green and environmentally approach, and then the LDH-VB9-TiO2 was applied with three different mass ratios as organic-inorganic fillers in order to prepare in-situ crosslinked poly(vinyl alcohol) (CSPVA) nanocomposites (NC)s. The physio-chemical structure of CSPVA NCs was studied with variety of analyses such as FT-IR, XRD, FE-SEM, TEM and TGA. Finally, the prepared compounds were used for the photo-degradation of methylene blue (MB) dye from aqueous solution under ultraviolet lights. The photo-degradation performance of samples showed that the rate constant of Kapp was in the order of LDH-VB9-TiO2 > TiO2 > LDH-VB9/TiO2-CSPVA NC. Moreover, the value of half-life for degradation of MB dye was very remarkable for LDH-VB9-TiO2 sample (t1/2 = 81.53 min) in compared to the MB degradation without any photocatalyst sample (t1/2 = 6930 min). So, it can be concluded that the LDH-VB9 with nano-sheet structure has significant effect on the photo-degradation of MB dye in the presence TiO2. These kinds of NCs can be used as economy and environmentally friendly compounds in the industrial applications such as water purification.Graphical abstractUnlabelled Image
       
  • Well-defined and highly stable AlNi composite pillared clay supported PdOx
           nanocrystal catalysts for catalytic combustion of benzene
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Zhu Chen, Jingrong Li, Zhen Cheng, Shufeng Zuo In the study, the effects of synthesis conditions for AlNi composite pillaring agents (Al/Ni molar ratio, aging temperature and aging time) on the structure and stability of AlNi pillared clays (AlNi-PILC) were investigated. And the results showed that the above synthesis factors could control and adjust the specific surface area, pore volume and basal spacing of AlNi-PILC. The formation of spinal NiAl2O4 markedly improved the thermal stability and anti-sintering properties of AlNi-PILC and maintain a stable mesoporous structure. Pd/AlNi-PILC nanocrystalline catalyst obtained by using a high-temperature solution-phase reduction method presented a strong interaction between the active species PdOx (x = 0, 1) and AlNi-PILC. The PdOx nanocrystals had excellent stability with a small diameter (1–2 nm) and the nanocrystals were evenly mono dispersed on the surface of AlNi-PILC. Thus, 0.2%Pd/AlNi-PILC exhibited excellent catalytic oxidation properties and completed catalytically oxidize low concentrations of benzene at 250 °C. Furthermore, 0.2%Pd/AlNi-PILC maintained 90% benzene conversion at 240 °C after a continuous reaction for 1000 h in dry air. And in either wet conditions or in the chlorine-containing VOCs, 0.2%Pd/AlNi-PILC maintained high catalytic activity and thus showed potential in industrial applications.Graphical abstractUnlabelled Image
       
  • Carbohydrate concentrations and enzyme activities as influenced by
           exchangeable cations, mineralogy and clay content
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Fatemeh Rakhsh, Ahmad Golchin Enzymes can exist in bound or free form within the soil, but the impact of interactions between extracellular enzymes with the amount and type of clay minerals and exchangeable cations on the activities of enzymes and decomposition or retention of carbohydrates in soil is still poorly understood. Appropriate amounts of homoionic Na-, Ca- and Al-clay minerals from Georgia kaolinite, Illinois illite and Wyoming montmorillonite were mixed with pure sand to prepare artificial soils with different clay contents, exchange cations and clay types to examine the effects of exchangeable cations, mineralogy and clay content on the concentrations of hot water and dilute acid extractable carbohydrates and activities of acid and alkaline phosphatases and CM-cellulase. There was a significant effect of clay content on the concentrations of carbohydrates and activities of enzymes. The concentrations of carbohydrates increased when the clay contents of soils increased from 0 to 5 and 10%, respectively, showing that the clay contents influence the capacity of soils for stabilization of carbohydrates. But opposite trends were found in enzyme activities. The enzyme activities decreased significantly as the clay contents of the artificial soils increased. The concentrations of carbohydrates and activities of enzymes were significantly affected by exchangeable cations. In soils with 5 and 10% clay, the concentrations of carbohydrates were maximum in Al-soils and minimum in Ca-soils, in contrast, the activities of enzymes were maximum in Ca-soils and minimum in Al-soils. There was a significant effect of clay mineralogy on the concentrations of carbohydrates and activities of enzymes. The concentrations of carbohydrates were highest in soils with Wyoming montmorillonite clay mineral and lowest in soils with Georgia kaolinite clay mineral. But the activities of enzymes were lower in soils with Wyoming montmorillonite clay mineral than soils with Georgia kaolinite and Illinois illite clay minerals, indicating the influence of specific surface area (SSA) and cation exchange capacity (CEC) of clay minerals on carbohydrate retention and enzyme activities. The results of this study indicate that carbohydrates are stabilized in soils through the interaction with clay minerals and a small amount of clay (5%) significantly increases carbohydrate retention and reduces enzyme activities in soils. Exchangeable cations exert their influence on enzyme activities and hence carbohydrate dynamics by controlling the activities of enzymes through modifying the physicochemical characteristics of soils.
       
  • Alteration of fine fraction of bentonite from Kopernica (Slovakia) under
           acid treatment: A combined XRD, FTIR, MAS NMR and AES study
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Martin Pentrák, Viktor Hronský, Helena Pálková, Peter Uhlík, Peter Komadel, Jana Madejová Acid activation of clay minerals is one of the most effective methods proposed to produce materials with increased acidity and adsorption properties. In this work fine fraction of bentonite from deposit Kopernica (Slovakia) was treated with 6 mol/L HCl. Variety of methods were employed in order to investigate the structural changes occurring as a result of the acid activation. Quantitative XRD analysis and FTIR revealed a dominant presence of montmorillonite, with K-feldspars, quartz, volcanic glass, opal C, ferrihydrite, biotite and kaolinite admixtures in acid untreated sample. 29Si MAS NMR spectra also confirmed accessory siliceous phases. 27Al MAS NMR showed that approximately 10% of Al was bound in the tetrahedral sites of montmorillonite. Gradual decrease of the Al, Fe and Mg content, an upward shift of the complex SiO stretching band and the appearance of Q4(0Al), Q3(1OH) signals in the 29Si MAS NMR spectra of the extensively reacted materials indicated a substantial modification of the montmorillonite layers and formation of an amorphous silica product. The accessory minerals quartz, K-feldspars and kaolinite were dissolved more slowly. The presence of kaolinite and quartz/K-feldspars in solid product was confirmed even after treatment for 36 h. The acid treatment affected also the surface and acidity characteristics of the samples. The total specific surface area (EGME SSA) gradually decreased with decreasing montmorillonite content in the reaction product. In contrast, the changes in the N2BET SSA showed that reaction with an acid first increased it to a maximum after treatment for 6 h, but more extensive treatments had a negative effect. After pyridine adsorption the IR spectra of the samples treated for 1 up to 6 h showed, in addition to the bands related to the H-bonded and physisorbed pyridine, also the diagnostic band of pyridinium cation near 1540 cm−1 confirming the presence of strong Brønsted acid sites.
       
  • Synthesis of light olefins from CO2 hydrogenation over
           (CuO-ZnO)-kaolin/SAPO-34 molecular sieves
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Pengfei Wang, Fei Zha, Lu Yao, Yue Chang CuZn oxide/SAPO-34 molecular sieves was used as bifunctional catalyst for the direct synthesis of light olefins from CO2 and H2, but the production of SAPO-34 molecular sieves required high cost and the CuZn oxide (CuO-ZnO) particles were prone to sintering, which severely restricted its industrial application. Herein, kaolin was used as raw material to prepare SAPO-34 molecular sieves and as supports to prepare kaolin-supported CuO-ZnO catalysts. The samples were characterized by X-ray diffraction, Scanning Electron Microscope, Energy Dispersive Spectroscopy, N2 sorption, H2 temperature programmed reduction, NH3 temperature programmed desorption and Fourier Transforms Infrared spectra techniques. The results showed that the SAPO-34 molecular sieves presented lamellar structure and the CuO-ZnO particles were well dispersed on the surface of kaolin. The results of catalytic reaction for the direct synthesis of light olefins from CO2 and H2 indicated that the (CuO-ZnO)-kaolin/SAPO-34 molecular sieves could enhance not only the yield of light olefins, but also the lifetime.Graphical abstractUnlabelled Image
       
  • Routine investigation of structural parameters of dioctahedral smectites
           by the Rietveld method
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Xiaoli Wang, Kristian Ufer, Reinhard Kleeberg X-ray powder diffraction (XRD) in combination with the Rietveld method is a common technique for crystal structure analysis. However, almost all minerals of the smectite group show turbostratic disorder preventing the direct application of Rietveld refinement. Ufer et al. (2004) proposed to overcome this limitation by using a single layer model with the BGMN program. This model is now routinely used for quantitative phase analysis of smectite-containing samples. However, the refinement of some important structural features, such as the layer charge density (LCD) and the octahedral iron content has not been achieved successfully yet. Typically, these structural features can be obtained only by analytical methods which require purified smectite samples. The project was firstly aimed to prove the validity of the refinement of selected structural parameters by using a set of purified and well-characterized samples and then applied this method to raw bentonites with natural impurities.The Rietveld refinements were carried out on the X-ray powder diffraction patterns of the Cu-triethylenetetramine (Cutrien) exchanged dioctahedral smectites to avoid the problems of unknown cation species and complex hydration behavior in the interlayer. The refinements of the occupancy of octahedral iron and the LCD led to reasonable results for iron-poor purified samples. The application of the structure model to Cutrien -exchanged smectite-rich samples with natural impurities, e.g. bentonites without previous purification, showed that some important structural details of turbostratically disordered dioctahedral smectites can be determined by the Rietveld method from XRD patterns of the Cutrien -exchanged samples. The technique may be applied in routine structural characterization of raw smectites in bulk rock samples without a prior chemical analysis of purified smectite fractions.
       
  • Design and preparation acid-activated montmorillonite sustained-release
           drug delivery system for dexibuprofen in vitro and in vivo evaluations
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Tingting Li, Lele Zhao, Ziliang Zheng, Min Zhang, Yidan Sun, Qingping Tian, Shuqiu Zhang Montmorillonite (Mt) plays a very important role in controlling drug delivery. In this paper, the hydrochloric acid (HCl) treated Mt. was exploited to obtain composites, which were able to enhance dexibuprofen (IBU) loading and achieve to sustain release drug. The textural properties of the Mt. were strongly dependent on the treatment of HCl. The drug loading of pristine Mt. was 190 mg/g, while it was increased to 298 mg/g for Acid-Mt. In vitro release showed that the IBU was released about 92% from IBU/Acid-Mt within 12 h, while the pure IBU was released all within 4 h in simulated intestinal fluid, which meant that the IBU/Acid-Mt were able to retard the drug release with a controlled manner. The release profiles of IBU from composites were fitted by Higuchi and Korsmeyer-Peppas equations, which manifested that diffusion sustained release dominated the main mechanism. Meanwhile, in vivo pharmacokinetics studies in rats displayed that the IBU/Acid-Mt exhibited better gradual drug release than the commercial IBU suspension. For the IBU/Acid-Mt composites, the area under the plasma concentration-time curve from 0 to 24 h (AUC0–24) and mean residence time (MRT0–24) were 644.49 ± 73.26 μg/h/mL and 7.65 ± 0.48 h, both of which were significantly larger than commercial IBU suspension (AUC0–24 of 439.88 ± 84.41 μg/h/mL and MRT0–24 of 3.10 ± 0.38 h), respectively (P 
       
  • Effect of polymer molar mass and montmorillonite content on polymer
           flooding using a glass micromodel
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Sadegh Rahimi, Mahmoud Habibian, Mahsa Baghban Salehi Generally, the nanoclay dispersions in polymer of different materials reveal rheological and morphological behaviors. In this research, the effects of the sodium montmorillonite and molar mass of the hydrolyzed polyacrylamide were experimentally investigated on the oil recovery factor (Estimation of in-place oil to recoverable oil) at the pore scale using a glass micromodel. Experiments were designed based on Central Composite Design method for high molar mass clay polymer nanocomposites (HCPN) and low molar mass clay polymer nanocomposites (LCPN). Two quadratic models were thus developed to predict oil recovery of both clay polymer nanocomposites (CPN). According to the images of the micromodel pores with the nanoclay, the oil droplets changed to emulsion in the solution, making them pass easily through the pores. Optimization results showed that the oil recovery for HCPN with 1493 ppm of polymer concentration and with nanoclay mass ratio of 1, was about 79. Also, for LCPN with 2306 ppm of polymer concentration, and 0.85 mass ratio of nanoclay the oil recovery was reached to 74. Furthermore, the obtained results of scanning electron microscope, energy-dispersive X-ray spectroscopy and X-Ray diffraction appropriately confirmed dispersion of nanoparticles in solution of both optimal CPN. Moreover, the thermal gravimetric analysis presented an increase of thermal strength in the presence of nanomaterials. In addition, both CPN of HCPN and LCPN indicated non-Newtonian behavior. However, in the frequency
       
  • Effect of P3O10 5− intercalated hydrotalcite on the flame retardant
           properties and the degradation mechanism of a novel
           polypropylene/hydrotalcite system
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Sheng Xu, Si-Yu Li, Min Zhang, Hong-Yan Zeng, Jin-Ze Du, Chao-Rong Chen P3O105− intercalated Mg/Al hydrotalcite (LDH-P) was successfully prepared by impregnation-reconstruction, and its microstructure and surface chemical properties were characterized. It was found that P3O105− anion has completely intercalated into the interlayer space of the LDH-P. And the LDH-P exhibited a higher dispersity and weaker hydrophobicity than the CO32– intercalated Mg/Al hydrotalcite (LDH-C). The LDH-P was investigated as a potential flame retardant for polypropylene (PP) matrix, then the LDH-P and PP composite (PP/LDH-P) was characterized using X-ray diffraction (XRD) and thermogravimetric analysis (TGA) as well as the limited oxygen index (LOI), vertical burning UL94 and mechanical test, the results revealed that the introduction of LDH-P into PP not only increased the char residue, but also formed compact and folded morphology of char residue providing more effective protection for underlying materials against heat and oxygen compare with LDH-C. The morphological structures and component observed by digital photos, scanning electron micrograph (SEM) and Fourier transform infrared (FT-IR) of fire residues demonstrated that P-C vibration between LDH-P and PP was generated by intercalating LDH-P with P3O105− anion. Compared with the LDH-C, the LDH-P promoted the formation of a more continuous and compact char layer during the burning process. Thus, the LDH-P intercalating with P3O105− anion enhanced the flame retardancy of PP matrix. Promising developments for use of LDH-P in flame retardant formulations were expected in future applications.Graphical abstractUnlabelled Image
       
  • Methyl blue adsorption properties and bacteriostatic activities of Mg-Al
           layer oxides via a facile preparation method
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Yu Qiao, Qiurong Li, Hongjin Chi, Menglin Li, Yuanfei Lv, Shuangjiang Feng, Ruiyan Zhu, Kun Li The methods and materials for more effective elimination of carcinogenic dyes and bacteria in domestic wastewater have drawn great attention. In this study, methyl blue, Escherichia coli and Staphylococcus aureus could be removed and inhibited by versatile Mg-Al layer oxides. Mg-Al layered double hydroxide (LDH) was synthesized via a facile one-step method. Especially, the layered double metal oxide (LDO) as the calcined product of LDH was obtained. The adsorption efficiency for methyl blue from aqueous solutions on these samples was studied in a batch experiment. The results showed that as-prepared Mg-Al LDO exhibited an excellent adsorption performance for methyl blue, and in comparison with LDH, the removal efficiency of Mg3Al LDO could reach more than 94%. In addition, the antimicrobial activity of LDH and corresponding LDO against the gram-negative bacterial species E. coli and the gram-positive bacterial species S. aureus were investigated. The antibacterial efficiency increased from 49.65% (Mg3Al LDH) to 99.30% (Mg3Al LDO). The results revealed that the Mg-Al LDO exhibited an excellent antibacterial performance for these bacterial species compared with LDH. All above results showed that the as-prepared versatile materials provide a broad application prospect in wastewater purification.
       
  • Effect of clay treatment on the thermal degradation of PHB based
           nanocomposites
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Romina P. Ollier, David A. D'Amico, Walter F. Schroeder, Viviana P. Cyras, Vera A. Alvarez A detailed understanding of the thermal degradation processes taking place during the melt processing of bio-nanocomposites is crucial in order to increase the processing window of these materials. In this work, the influence of the content of neat clay and modified-clay on the thermal degradation of a biodegradable bacterial poly(3-hydroxybutyrate) (PHB) matrix, was studied. The modified clay consisted in a multi-treated organobentonite, which was first acid-activated, then silylated and further modified by cationic exchange treatment. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) tests were carried out to investigate the thermal behavior of the different nanocomposites as a function of temperature, whereas size exclusion chromatography (SEC) runs were performed to analyze the changes on the molecular weight distribution of the PHB. The obtained results reveal that the organic modifiers of the muti-treated clay promote the thermal degradation process leading to a dramatic decrease in the molecular weight of PHB. It was demonstrated that the degradation mechanism of PHB was not modified by the incorporation of neat clay or modified-clay, and that the process can be well described by the Avrami–Erofeev random nucleation model (m = 4), in which the reaction is controlled by initial random nucleation followed by overlapping growth.Graphical abstractUnlabelled Image
       
  • In-situ high temperature X-ray diffraction study of dickite
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Yu Yan, Hejing Wang Despite abundant thermal studies, the accurate phase-transition temperatures and thermal properties above dickite structure still remain unknown. This article focused on the dickite sample, derived from Fujian province, China, to figure out its phase transition from room temperature (RT) up to 1200 °C and to refine its structures at RT and 550 °C using in-situ high temperature X-ray diffraction (HTXRD) for the first time. The phase transition from dickite to meta-dickite took place within the range of 550–650 °C, and from meta-dickite to mullite happened in the interval of 900–950 °C. The structure parameters of dickite with temperature were refined, and their thermal expansion coefficients were therefore determined. The refined structures at RT and 550 °C indicated thermal expansion affected strongly along c axis and the volume expansion was dominantly controlled by the enlarged distortion of the tetrahedral sheet. The relationship between mass percentage and temperature revealed that the formations of meta-dickite and mullite both started at a fast speed and then slowed down later.Graphical abstractUnlabelled Image
       
  • Al+layered+double+hydroxides+on+steel+in+saturated+calcium+hydroxide+solution&rft.title=Applied+Clay+Science&rft.issn=0169-1317&rft.date=&rft.volume=">Chloride removal and corrosion inhibitions of nitrate,
           nitrite-intercalated MgAl layered double hydroxides on steel in saturated
           calcium hydroxide solution
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Jinxia Xu, Yingbin Song, Yihan Zhao, Linhua Jiang, Youjing Mei, Ping Chen The aim of this study is to evaluate the chloride removal and corrosion inhibitions of NO3−, NO2− intercalated MgAl layered double hydroxides (LDH) on steel in saturated calcium hydroxide solution by a comparative experiment. Mg-Al-LDH intercalated with NO2− was synthesized by anion exchange in the host material, Mg-Al-NO3 LDH, which was prepared by a coprecipitation method. The chloride equilibrium isotherm, corrosion potential and polarization resistance of steel (decided by electrochemical impedance spectroscopy (EIS)) in the solution were measured. Besides, scanning electron microscopy (SEM), X-ray diffraction instrument (XRD) and infrared spectroscopy were applied to observe the morphologies and microstructures of LDH. The results indicate that the LDH intercalated with NO3−, NO2− have excellent chloride removal capacities. Compared to LDH-NO3, the maximum chloride uptake amount for LDH-NO2 is relatively lower. However, the corrosion of steel for LDH-NO2 has a higher chloride threshold level. The dual effects, i.e., the uptake of chloride ion as an absorbent and the release of NO2− ions as an inhibitor, contribute to the better inhibition effect for LDH-NO2.
       
  • Optimising rational chemical analysis for quantitative determination of
           the composition of clay in soils
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Tatyana Vakalova, Valeriy Pogrebenkov, Vladimir Vereshagin, Tamara Khabas, Inna Revva A fractional (rational) chemical analytical method is proposed by which the material composition of clay rocks can be quantified and the clay-forming minerals present can be characterised. Subjecting raw clay to this procedure allows for the determination of the chemical composition of its fine-grained fraction, the amount and composition of exchangeable cations, water-soluble salts, carbonates and colloidal minerals, and the amount of amorphous silica and free quartz. A new, effective method is proposed for the qualitative and quantitative evaluation of the amorphous component in clays. This involves extracting colloids by treating the clay fractions with Tamm's reagent, a buffer solution of oxalic acid and ammonium oxalate with a pH of 3.25. Additionally, through calculations based on the results of chemical analyses, the illite content (derived from the content of non-exchangeable potassium oxide) and the chemical composition of the clay residue are determined. This enables the rock-forming clay mineral to be characterised and its structural chemical formula to be determined. This allows prediction of the physico-chemical and technological properties of the clay.
       
  • A molecular dynamics framework to explore the structure and dynamics of
           layered double hydroxides
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Germán Pérez-Sánchez, Tiago L.P. Galvão, João Tedim, José R.B. Gomes It is presented a straightforward procedure based on the CLAYFF force field to perform molecular dynamics (MD) computer simulations with the GROMACS open source package of layered double hydroxide (LDH) materials with different intercalated anions. This procedure enables running very long simulations of systems where all atomic positions are allowed to move freely, while maintaining the integrity of the LDH structure intact. Therefore, it has the potential to model different important applications of LDH involving ion-exchange and interlayer equilibrium processes in diverse areas as drug delivery, water purification, and corrosion protection. The magnesium-aluminium based LDH with a metallic ratio 2:1 (Mg2Al) was chosen to validate our computer simulation framework, because of the comprehensive experimental and computational studies reported in the literature devoted to the understanding of the structure of Mg2Al LDH. Potential parameters from the literature were used to model the Mg2Al LDH with different intercalated anions using a new set of atomic point charges calculated with the DDEC6 formalism. Once the model was validated through careful comparisons of the simulated and experimental structures, the procedure was adapted to the Zn2Al LDH materials. Lennard-Jones parameters had to be developed for zinc (II) cations and calibrated using the experimental structural data found in the literature for Zn2Al LDH and the height of the galleries determined experimentally in this work for Zn2Al with intercalated nitrate anions. The consistency of the model is proved by carrying out MD simulations to reproduce in the computer the typical experimental conditions in which the Zn2Al LDH is immersed in a sodium chloride water solution to act as a nanotrap for aggressive anions in corrosion protection applications. The LDH structure is maintained in the MD simulation in which the LDH is free to move alongside the solution and allowing a natural anion exchange between the LDH and the solution as well as dehydration/hydration of the basal space.
       
  • The use of mineralogical indicators for the assessment of firing
           temperature in fired-clay bodies
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Alberto Viani, Giuseppe Cultrone, Konstantinos Sotiriadis, Radek Ševčík, Petr Šašek Fired-clay bricks are frequently object of conservative actions aimed at the preservation of cultural heritage. Information on firing conditions is relevant for the production of custom made replacement bricks, since, as a widely accepted principle, they should be close match to the pre-existing ones. In this work, the mineralogical and microstructural evolution of fired-clay bodies is described using a combination of analytical techniques, and an approach for the assessment of firing temperature using calibration curves built from the results of X-ray powder diffraction quantitative phase analysis with the Rietveld method, is presented. The weight fractions of hematite, mullite and the amorphous fraction, from two raw clays fired in the laboratory at different temperatures, have been used to assess the firing temperature of two industrially produced bricks. The values derived applying these three methods were in good agreement with the nominal temperatures of the industrial cycles. This approach might be of interest for the assessment of the firing conditions of a broader range of historical/archaeological fired-clay materials.
       
  • Origin and distribution of clay minerals of soils in semi-arid zones:
           example of Ksob watershed (Western High Atlas, Morocco)
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Fatima Ezzahra Omdi, Lahcen Daoudi, Nathalie Fagel The Ksob basin watershed is located in a region with a semi-arid climate; it is characterized by large area, variable geology and clay mineralogy, variable topography and different types of thin soils. In the aim to determine the origin and distribution of clay mineral of soils of this basin, three types of samples were considered in this study; the parent rock, the different horizon of soils and the recent river deposit. Clay mineralogical composition, particle size distribution, soil texture, carbonate, moisture and organic matter content (SOM), pH and conductivity were measured to identify the soil properties. Chlorite and illite of the studied soils basin were principally inherited from the parent materials, while vermiculite was principally formed in the soil environment. The other phases (dioctahedral smectite, illite-smectite mixed layers, kaolinite and palygorskite) can result from both inheritance and transformation. Ttrioctahedral smectite and palygorskite can also results from neoformation. Carbonate, SOM content and pH of the studied soils vary independently with clay mineralogy. However soils texture, parent rock, topography and climate strongly influence soil clay mineralogy and its evolution.
       
  • Variation in thickness of a layered silicate on spherical silica particles
           affected HPLC chiral chromatographic resolution
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Tomohiko Okada, Mutsuki Oguri, Kazuki Tajima, Tomohiko Yamakami, Hisako Sato The proposed study aims to prepare clay-coated spherical silica particles to be applied as a column packing material for chiral high performance liquid chromatography (HPLC). These particles were prepared by directly growing a hectorite-like layered silicate on porous and non-porous amorphous silica. The direct crystallization of the layered silicate was performed using the reactions of lithium fluoride, magnesium chloride, and silica in the presence of urea under hydrothermal conditions (373 K for 2 d) and led to a homogeneous coverage on the silica surfaces within a 0.4 μm thickness of the aggregates. The resulting layered silicate involved full ion-exchange reactions with an enantiomeric Δ-tris(1,10-phenanthroline)ruthenium(II). The organically modified particles packed into a stainless steel tube optically resolved a racemic mixture of tris(acetylacetonato)ruthenium(II) in a flow of methanol. The resolution efficiency determined by the retention time and full width at half maximum was influenced by the crystalline size and could be adjusted using different porosities of the initial silica and by varying the quantities of added Li and Mg ions to the starting mixtures. Fine platy crystals and their thin layer aggregates on the porous silica contributed toward the good resolution efficiency and a reduction in the elution volume owing to the rapid diffusion of the racemic mixture into the layered silicate.Graphical abstractUnlabelled Image
       
  • Superhydrophobic kaolinite modified graphene oxide-melamine sponge with
           excellent properties for oil-water separation
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Min Peng, Guiqiu Chen, Guangming Zeng, Anwei Chen, Kai He, Zhenzhen Huang, Liang Hu, Jiangbo Shi, Hui Li, Lei Yuan, Tiantian Huang In this work, a facile and cost-effective method was reported to fabricate a novel, robust, and superhydrophobic kaolinite modified graphene oxide-melamine sponge (K-GOMS). The GO sheets were used to increase the roughness of the sponge smooth surface. The hydrophobic kaolinite adhered on GO sheets significantly enhanced the superhydrophobicity of the K-GOMS surface with a water contact angle of 152.3°. Several organic solvents and oils were selected to test the adsorption performance of the obtained adsorbents. The results revealed that the superhydrophobic K-GOMS exhibited not only superior adsorption capacity for various organic solvents and oils, from 60 to 113 times of its own weight, but also outstanding recyclability with an adsorption capacity retention higher than 94% after 30 cycles of diesel oil adsorption, and excellent environmental tolerance in wide range of pH values and temperatures. Therefore, this study provides an effective way for constructing facile, low-cost, and large-scale production of superhydrophobic adsorbents for oil-water separation.
       
  • Biological activity and sorption ability of synthetic montmorillonite
           modified by silver/lysozyme nanoparticles
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Olga Yu Golubeva, Elena Yu Brazovskaya, Olga V. Shamova New bioactive materials based on synthetic montmorillonite (Mt) of different chemical compositions (Na2x(Al2(1-x),Mg2x)Si4O10(OH)2·nH2O, where x = 1, 0.75, 0.5 and 0.1) modified by silver/lysozyme nanoparticles (Ag/Lys) have been synthesized. Antimicrobial and hemolytic activities, as well as sorption ability of composite materials towards the simulated toxic agent of medium molecular weight (methylene blue) in environments, similar to those found in human body (рН 1.8 and 6.9) has been studied. It was found that Ag/Lys-Mt materials are active against Gram-negative and Gram-positive bacteria (Escherichia coli ATCC 25922, Staphylococcus aureus SG-511), while maintaining a low hemolytic effect. The hemolytic activities of synthetic Mt with specified characteristics are presented for the first time. The study of synthetic Mt of different chemical compositions made it possible to establish the main regularities of the effect of Mt composition on the interaction with Ag/Lys nanoparticles. An increase in the aluminium oxide content in Mt leads to an increase in the negative zeta potential of the surface, an increase in the hemolytic activity (toxicity) of the samples, a decrease in silver content at the Mt surface, and consequently, to a decrease in antimicrobial activity with respect to aluminium-free samples. At the same time, the adsorption capacity of samples of all the compositions remains sufficiently high. This makes it possible to talk about the possibility of using them as antiseptic substances for external application, as well as new enterosorbents with antibiotic properties.Graphical abstractUnlabelled Image
       
  • Charge controlled immobilization of chloroperoxidase on both inner/outer
           wall of NHT: Improved stability and catalytic performance in the
           degradation of pesticide
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Xueting Fan, Mancheng Hu, Shuni Li, Quanguo Zhai, Fei Wang, Yucheng Jiang Halloysite nanotubes (HNT) is a kind of kaolin clay consisting of one alumina octahedron sheet and one silica tetrahedron sheet formed by rolling flat sheets into a hollow tubular structure. It is an ideal carrier for immobilization of enzyme due to its large surface area, biocompatibility, and chemical and mechanical stability besides abundance and low-cost. In order to make the most of this carrier for enzyme immobilization, in this work, two strategies were proposed for entrapping and embedding chloroperoxidase (CPO) on both inner/outer wall of HNT rather than in the hollow space alone by pH modulated electrostatic adsorption. Besides the enhanced loading amount, the thermal stability and tolerance to organic solvents of immobilized CPO (I-CPO) was greatly improved compared to the free enzyme. The free CPO can retain only 11.66% activity after 1 h incubation at 80 °C, while the I-CPO remained 87.63% activity at the same condition. Even after 1.5 h incubation at 90 °C, when the free CPO lost all its activity, the I-CPO can still remain 40.3% activity; Moreover, in the presence of organic solvent (ethyl acetate, acetonitrile, methanol, and DMF) with volume fraction of 10%, almost no loss of activity of I-CPO was observed, but free CPO can only remain 41.6%, 38.2%, and 23.5% of its initial activity in ethyl acetate, acetonitrile, methanol-water mixed system respectively, and even inactivated completely in DMF in the same condition. Furthermore, the enzymatic kinetic parameters (Km, and kcat/Km) suggested the affinity and specificity of I-CPO to the substrate was improved.I-CPO was very efficient when applied in the degradation of isoproturon in wastewater. The isoproturon with initial concentration of 26.7 μmol·L−1 can be completely degraded only in 10 min, indicating a potential practical application of I-CPO in treatment of wastewater containing pesticide.Graphical abstractUnlabelled Image
       
  • Quartz types in shale and their effect on geomechanical properties: An
           example from the lower Cambrian Niutitang Formation in the Cen'gong block,
           South China
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Jingshou Liu, Wenlong Ding, Ruyue Wang, Zhonghu Wu, Dajian Gong, Xinghua Wang, Shuai Yin, Baocheng Jiao We identified the sources of quartz in shales of the Niutitang Formation in the Cen'gong block, northern Guizhou Province, China, based on thin-section studies using a scanning electron microscope (SEM), rock cores and field observations. By analyzing the petrology, total organic carbon (TOC), major elements, and illite “crystallinity”, we investigated the formation of silica in the Niutitang shales. Our results show that the quartz in the Niutitang shales consists mainly of detrital quartz, biogenic quartz, and quartz that transformed from clay minerals. The amount of excess SiO2 in the Niutitang shales was approximately 5–35%, and the Al/(Fe + Al + Mn) and Si/(Si + Al + Fe) ratios ranged from 0.45 to 0.85 and from 0.7 to 0.91, respectively, which indicates that the silica was not solely biogenic. The values of excess SiO2, Al/(Fe + Al + Mn), Si/(Si + Al + Fe), and TOC increased with increasing quartz content, which implies that increasing quartz concentrations were associated with gradual increases in biogenic quartz and decreases in detrital quartz. Quartz from different sources can result in varying rock geomechanical properties and fracture abundance. Compared with pure biogenic quartz or detrital quartz, an appropriate proportion of mixed biogenic quartz and detrital quartz can make rocks more brittle and therefore lead to more fractures.
       
  • Enhanced adsorption of perchlorate by gemini surfactant-modified
           montmorillonite: Synthesis, characterization and their adsorption
           mechanism
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Kancharla Srinivasarao, Subbaiah Muthu Prabhu, Wuhui Luo, Keiko Sasaki Organo-montmorillonites (OMt) adsorb perchlorate (ClO4−) through anion exchange mechanism. Each gemini surfactant (GCn) provides two anion exchangeable sites due to its unique molecular structure. Due to the presence of more anion exchangeable sites, the preparation of OMt with GCn enables the possibility for higher amount of ClO4− uptake than their single-chain counterparts. In this work, gemini surfactant modified montmorillonites (GCn-Mt) were synthesized using three different alkyl chain length containing gemini surfactants (CnH2n+1(Me)2-C6H12-CnH2n+1(Me)2·2Cl), where n varied to 12, 14 and 16 and were examined in detail for the adsorption of ClO4− from aqueous solution. The structure of the GCn-Mt before and after adsorption of ClO4− was characterized by an array of techniques such as powder XRD, FT-IR, XPS, TGA and CHN analysis. The adsorption of ClO4− onto the GCn-Mt was best described by the Langmuir adsorption isotherm and pseudo-second-order kinetic model. The GC16-Mt showed the highest removal capacity of 1.08 mmol/g and at a rapid rate, achieving 95% within 1 min, with an equilibrium time of 15 mins. The GC16-Mt retained its high removal capacity and selectivity in presence of a variety of coexisting anions such as HCO3−, NO3−, CO32−, SO42−, SiO32−, and H2PO4−, and at a wide pH range (2−12). Combining the high removal capacity and selectivity with fast kinetics, the GCn-Mt has great potential for ClO4− removal from aqueous solutions.Graphical abstractUnlabelled Image
       
  • From experimental variability to the sorption related retention parameters
           necessary for performance assessment models for nuclear waste disposal
           systems: The example of Pb adsorption on clay minerals
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Esra Orucoglu, Christophe Tournassat, Jean-Charles Robinet, Benoît Madé, Mélanie Lundy Surface complexation models (SCMs) have been developed in the last decades to describe metal ion sorption to clay minerals and especially to montmorillonite. In principle, these models can provide relevant information about sorption of radionuclides to be used in performance assessment (PA) of radioactive waste disposal systems. However, these SCMs have been developed in parallel with the acquisition of distinct adsorption datasets, which are not always consistent with each other. The objective of this study was to compare new experimental adsorption results with literature data to understand these discrepancies and to propose a SCM approach that could be amenable to determine sorption related retention parameters necessary for PA calculations. This study focused on lead (Pb) adsorption on montmorillonite, illite and in a natural clay (Callovo Oxfordian) as case studies of a strongly sorbing radionuclide that undergoes a range of retention processes depending on the chemical conditions. The experiments showed that many experimental artifacts lead to misinterpretations of the processes underlying the measured retention values. These include Pb precipitation in the presence of carbonate in solution. The determination of SCM parameters to provide sorption related information for PA of clay minerals should rely on preliminary building of an adequate adsorption database, where adequate means that all experimental conditions are met to quantify surface complexation only.
       
  • Mixed hydrothermal and meteoric fluids evidenced by unusual H- and
           O-isotope compositions of kaolinite-halloysite in the Fe(-Mn) Tamra
           deposit (Nefza district, NW Tunisia)
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Augustin Dekoninck, Béchir Moussi, Torsten Vennemann, Fakher Jamoussi, Nadine Mattielli, Sophie Decrée, Hédi-Ridha Chaftar, Nouri Hatira, Johan Yans The iron mine of Tamra (Nefza District, NW Tunisia) is a 50 m thick Upper Mio-Pliocene sedimentary series impregnated by Fe-Mn oxides associated with white clay lenses with high halloysite and kaolinite content. This mineralization results from i) synsedimentary weathering/pedogenesis, and ii) mixing surface water and regional hydrothermal fluids. The oxygen and hydrogen isotope composition of halloysite-kaolinite and goethite-hematite is examined in order to provide new insights into the ore formation. This study concludes that halloysite-kaolinite was not equilibrated only with meteoric fluids: the δ18O values have a range towards high values that are not consistent with weathering conditions for their formation and/or during their subsequent alteration. The δD and δ18O values of goethite lead to the same conclusion. The stable isotope compositions could be related to fluid-rock interaction with the underlying marls (and/or skarns), providing relatively high δ18O values to the fluids responsible for the white clay formation. This model also shows that the Pb-isotope compositions of halloysite-kaolinite are explained by a felsic and a carbonated end-member, similar to other ore deposits (IOCG and Sedex) of the vicinity. Several factors should be considered for the precipitation of halloysite-kaolinite and/or destabilization of primary clays in the Tamra ore, i.e. mixing of deep hot saline fluids, related to a thermally driven circulation, and meteoric waters. This hydrothermal contribution postdates the main synsedimentary weathering/pedogenetic Fe-enrichment and may be related to late Fe, Mn, Pb, Zn and As inputs of the Fe-Mn oxides.
       
  • Effect of polyampholyte-bentonite interactions on the properties of
           saltwater mud
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Ling Lin, Pingya Luo Hydrolyzed poly(acrylamide/dimethyl diallyl ammonium chloride) was synthesized via free-radical copolymerization followed by hydrolyzation. The synthesized polyampholyte was characterized by Fourier transform-IR and 1H NMR measurements. An intensive investigation was carried out to identify the effect of salt, temperature, pH, polymer composition, and intrinsic viscosity on the adsorption of the polyampholyte samples on bentonite, the bentonite particle size distribution, and the filtration of saltwater mud. In the mud samples, the polyampholyte interacted with bentonite via adsorption. By introducing electrostatic repulsion and entropic repulsion, the polyampholyte helped maintain a broad bentonite particle size distribution, allowing the bentonite to form a densely packed filter cake after aging treatment. In summary, using a polyampholyte with a high cationic group content, a high intrinsic viscosity, and an anionic group content in a specific range resulted in a strong adsorptive ability on bentonite and allowed ideal control over the clay particle size distribution and mud filtration behavior.
       
  • In situ self-assembled preparation of the hybrid nanopigment from raw
           sepiolite with excellent stability and optical performance
    • Abstract: Publication date: October 2018Source: Applied Clay Science, Volume 163Author(s): Shengtao Wu, Haishuai Cui, Conghui Wang, Fang Hao, Pingle Liu, Wei Xiong A novel nanopigment with excellent stability and optical performance was prepared by installing rhodamine B (Rhb) onto the hexagonally ordered mesoporous silica (Al-MCM-41) using in situ self-assembled method (Rhb@SSA). The Rhb molecules were assembled and enriched in special microenvironment between the template and silica walls by the reconstructed process. Raw sepiolite (Sep) was used as effective and environmentally-friendly source of silicon and aluminum in the synthesis of Al-MCM-41. The structure and performance of nanopigments obtained by different supports and preparation methods were characterized by XRD, BET, SEM-EDX, TEM, FT-IR, TGA, UV–Vis, the excitation spectrum and emission spectrum and colorimetric tests. The cetyl-trimethyl ammonium bromide (CTAB) with dual functions of templating-photosensitizer plays an important role in formation of the Al-MCM-41 and the colour performance enhancement. 0.5% Rhb@SSA prepared via impregnation method shows better performance than those of 0.5% Rhb/Sep and 0.5% Rhb/Al-MCM-41.Graphical abstractUnlabelled Image
       
  • MCM2016- special issue of applied clay science
    • Abstract: Publication date: Available online 6 July 2018Source: Applied Clay ScienceAuthor(s): Asuman Günal Türkmenoğlu, Haluk Akgün
       
  • Kinetic re-evaluation on “Comparative adsorption of Pb(II), Cu(II) and
           Cd(II) on chitosan saturated montmorillonite: Kinetic, thermodynamic and
           equilibrium studies”
    • Abstract: Publication date: Available online 7 May 2018Source: Applied Clay ScienceAuthor(s): Yong-Son Hong
       
  • Laboratory research on the influence of swelling clay on the quality of
           
    • Abstract: Publication date: Available online 4 May 2018Source: Applied Clay ScienceAuthor(s): Mateusz Kmieć, Bartłomiej Karpiński, Michał Antoszkiewicz, Marek Szkodo Swelling clay phenomenon is frequently observed during oil and gas drilling operations and has a significant impact on the quality of cementing procedure. Certain types of clayey minerals increase their volume in contact with water-based drilling fluids. After drilling is completed, borehole remains unsupported and filled with water-based drilling fluids for several hours, before a casing string is inserted and secured with cement. In the period of time between completing the drilling and inserting the casing string the clay can expand hindering proper cementing or blocking the casing string in a wellbore. Filling the annular space between a casing pipe and wellbore walls with cement is crucial for further exploitation of a well. An improper performance of displacement work (primary cementing) may cause both financial losses and environmental damage. The aim of this study is to describe the impact of distorted annular space geometry on cement sheath quality and to examine the possibility of improving the distorted geometry with a prototype wellbore tool. The tool was designed to be mounted as a first pipe section on the casing string (cementing shoe/reamer shoe). Two test stands were designed and constructed. The first one simulates the well cementing process, while the second one simulates the downward movement of the casing pipe in the well (run in hole process) drilled in expansive clay. Six distorted annular space sections were cemented using the first test stand. The sections were scanned with μXCT (computed micro-tomography) to locate discontinuities in the cement sheath. This research has confirmed an adverse influence of annular space obstructions on the cement sheath quality, thus the necessity of removing them before cementing. The obstructions can be removed by means of newly designed clay cutting wellbore tool. Therefore, the prototype of such a tool was tested on the second test stand. The experiment allowed to evaluate an influence of a swollen clay obstruction on the force needed to push the prototype tool through the obstruction. The same experiment was conducted with a standard cementing shoe in order to obtain comparative data. Hole geometry improvement, ability to fragment and remove clay cuttings have been observed. The research has confirmed that the prototype tool efficiently improves the borehole geometry and, consequently, improves the cement sheath quality.
       
  • Adsorption of linuron by an Algerian palygorskite modified with magnetic
           iron
    • Abstract: Publication date: Available online 24 March 2018Source: Applied Clay ScienceAuthor(s): Lala Setti Belaroui, Affaf Ouali, Abdelkader Bengueddach, Alberto Lopez Galindo, Aránzazu Peña Three types of palygorskite nanoparticles for the retention of the herbicide linuron in water were tested: purified palygorskite (Pur Pal), palygorskite modified by magnetic iron oxides (FeO Pal1) and this one synthesized by hydrothermal treatment (FeO Pal2). The adsorbents were characterized by X-ray diffraction (XRD), infrared spectroscopy (FTIR), electron microscopy (TEM) and chemical analysis (XRF). XRD patterns indicate the presence of a magnetic Fe2O3 compound, and TEM images evidence how these crystals cover the palygorskite fibers' surface with different crystallite sizes (7–15 nm in FeO Pal1 and 30-50 nm in FeO Pal2). The adsorbent mass, the contact time, the initial adsorbate concentration and the effect of temperature were evaluated for linuron retention. Adsorption kinetics revealed that adsorption followed a pseudo-second order equation. Adsorption isotherms were better fitted to the Freundlich than to the Langmuir equation. Removed linuron amounts were ranged as FeO Pal2 (83%) > FeO Pal1 (55%) > Pur Pal (27%). The adsorbents could be used as a cheap alternative for pesticide removal in environmentally-contaminated waters.Graphical abstractUnlabelled Image
       
  • Evaluation of a sand bentonite mixture as a shaft/borehole sealing
           material
    • Abstract: Publication date: Available online 5 January 2018Source: Applied Clay ScienceAuthor(s): Haluk Akgün, Mustafa K. Koçkar The mechanical and hydrological characteristics of compacted sand bentonite mixtures with bentonite contents ranging from 5 to 40% were investigated in the laboratory in order to assess their use as a waste isolation material and to select an optimum sand bentonite mixture. Laboratory tests included compaction, compaction permeability, unconfined compression and direct shear tests which led to a recommendation to select a mixture with a bentonite content of 30% for the isolation of underground geological waste disposal repositories. This study complements the previous studies of the authors of this manuscript by determining the mechanical and hydrological properties of sand bentonite mixtures that possess bentonite contents> 30% to determine the geotechnical properties (i.e., unconfined compressive strength, Young's modulus, cohesion and angle of internal friction) and the mechanical behavior of these relatively high levels of bentonite mixtures for the first time in the literature.
       
 
 
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