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  Subjects -> ENGINEERING (Total: 2266 journals)
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ENGINEERING (1195 journals)                  1 2 3 4 5 6 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 7)
3D Research     Hybrid Journal   (Followers: 19)
AAPG Bulletin     Full-text available via subscription   (Followers: 5)
AASRI Procedia     Open Access   (Followers: 15)
Abstract and Applied Analysis     Open Access   (Followers: 3)
Aceh International Journal of Science and Technology     Open Access   (Followers: 2)
ACS Nano     Full-text available via subscription   (Followers: 216)
Acta Geotechnica     Hybrid Journal   (Followers: 6)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 1)
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: 10)
Adıyaman Üniversitesi Mühendislik Bilimleri Dergisi     Open Access  
Adsorption     Hybrid Journal   (Followers: 4)
Advanced Engineering Forum     Full-text available via subscription   (Followers: 4)
Advanced Science     Open Access   (Followers: 5)
Advanced Science Focus     Free   (Followers: 3)
Advanced Science Letters     Full-text available via subscription   (Followers: 5)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 6)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 18)
Advances in Artificial Neural Systems     Open Access   (Followers: 3)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5)
Advances in Complex Systems     Hybrid Journal   (Followers: 7)
Advances in Engineering Software     Hybrid Journal   (Followers: 25)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 14)
Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 9)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 18)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 22)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 8)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 28)
Advances in Operations Research     Open Access   (Followers: 11)
Advances in OptoElectronics     Open Access   (Followers: 5)
Advances in Physics Theories and Applications     Open Access   (Followers: 13)
Advances in Polymer Science     Hybrid Journal   (Followers: 40)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Remote Sensing     Open Access   (Followers: 35)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aerobiologia     Hybrid Journal   (Followers: 1)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 4)
AIChE Journal     Hybrid Journal   (Followers: 29)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access  
Alexandria Engineering Journal     Open Access   (Followers: 1)
AMB Express     Open Access   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 28)
American Journal of Engineering and Applied Sciences     Open Access   (Followers: 11)
American Journal of Engineering Education     Open Access   (Followers: 9)
American Journal of Environmental Engineering     Open Access   (Followers: 16)
American Journal of Industrial and Business Management     Open Access   (Followers: 23)
Analele Universitatii Ovidius Constanta - Seria Chimie     Open Access  
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of Regional Science     Hybrid Journal   (Followers: 7)
Annals of Science     Hybrid Journal   (Followers: 7)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applicable Analysis: An International Journal     Hybrid Journal   (Followers: 1)
Applied Catalysis A: General     Hybrid Journal   (Followers: 5)
Applied Catalysis B: Environmental     Hybrid Journal   (Followers: 6)
Applied Clay Science     Hybrid Journal   (Followers: 4)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 3)
Applied Nanoscience     Open Access   (Followers: 7)
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Physics Research     Open Access   (Followers: 4)
Applied Sciences     Open Access   (Followers: 3)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 4)
Arabian Journal for Science and Engineering     Hybrid Journal   (Followers: 5)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 4)
Archives of Foundry Engineering     Open Access  
Archives of Thermodynamics     Open Access   (Followers: 8)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
ASEE Prism     Full-text available via subscription   (Followers: 2)
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: 7)
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: 7)
Avances en Ciencias e Ingeniería     Open Access  
Balkan Region Conference on Engineering and Business Education     Open Access   (Followers: 1)
Bangladesh Journal of Scientific and Industrial Research     Open Access  
Basin Research     Hybrid Journal   (Followers: 3)
Batteries     Open Access   (Followers: 3)
Bautechnik     Hybrid Journal   (Followers: 1)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 23)
Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 3)
BER : Manufacturing Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Motor Trade Survey     Full-text available via subscription   (Followers: 1)
BER : Retail Sector Survey     Full-text available via subscription   (Followers: 2)
BER : Retail Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Survey of Business Conditions in Manufacturing : An Executive Summary     Full-text available via subscription   (Followers: 3)
BER : Survey of Business Conditions in Retail : An Executive Summary     Full-text available via subscription   (Followers: 3)
Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access   (Followers: 1)
Biofuels Engineering     Open Access  
Biointerphases     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 9)
Biomedical Engineering     Hybrid Journal   (Followers: 16)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 13)
Biomedical Engineering Letters     Hybrid Journal   (Followers: 5)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 16)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 31)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 8)
Biomedical Science and Engineering     Open Access   (Followers: 4)
Biomedizinische Technik - Biomedical Engineering     Hybrid Journal  
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Hybrid Journal   (Followers: 1)
Biotechnology Progress     Hybrid Journal   (Followers: 39)
Boletin Cientifico Tecnico INIMET     Open Access  
Botswana Journal of Technology     Full-text available via subscription  
Boundary Value Problems     Open Access   (Followers: 1)
Brazilian Journal of Science and Technology     Open Access   (Followers: 2)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 10)
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 14)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 3)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Full-text available via subscription   (Followers: 13)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 40)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 7)
Case Studies in Thermal Engineering     Open Access   (Followers: 4)
Catalysis Communications     Hybrid Journal   (Followers: 6)
Catalysis Letters     Hybrid Journal   (Followers: 2)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 6)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysis Today     Hybrid Journal   (Followers: 5)
CEAS Space Journal     Hybrid Journal  
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 3)
Central European Journal of Engineering     Hybrid Journal   (Followers: 1)
CFD Letters     Open Access   (Followers: 6)
Chaos : An Interdisciplinary Journal of Nonlinear Science     Hybrid Journal   (Followers: 2)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
Chinese Journal of Engineering     Open Access   (Followers: 2)
Chinese Science Bulletin     Open Access   (Followers: 1)
Ciencia e Ingenieria Neogranadina     Open Access  
Ciencia en su PC     Open Access   (Followers: 1)
Ciencias Holguin     Open Access   (Followers: 1)
CienciaUAT     Open Access  
Cientifica     Open Access  
CIRP Annals - Manufacturing Technology     Full-text available via subscription   (Followers: 11)
CIRP Journal of Manufacturing Science and Technology     Full-text available via subscription   (Followers: 14)
City, Culture and Society     Hybrid Journal   (Followers: 21)
Clay Minerals     Full-text available via subscription   (Followers: 9)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
Coal Science and Technology     Full-text available via subscription   (Followers: 4)
Coastal Engineering     Hybrid Journal   (Followers: 11)
Coastal Engineering Journal     Hybrid Journal   (Followers: 4)
Coatings     Open Access   (Followers: 2)
Cogent Engineering     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 4)
Color Research & Application     Hybrid Journal   (Followers: 1)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 13)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 13)
Communications Engineer     Hybrid Journal   (Followers: 1)
Communications in Numerical Methods in Engineering     Hybrid Journal   (Followers: 2)
Components, Packaging and Manufacturing Technology, IEEE Transactions on     Hybrid Journal   (Followers: 23)
Composite Interfaces     Hybrid Journal   (Followers: 6)
Composite Structures     Hybrid Journal   (Followers: 252)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 177)
Composites Part B : Engineering     Hybrid Journal   (Followers: 223)
Composites Science and Technology     Hybrid Journal   (Followers: 164)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access  
Computational Geosciences     Hybrid Journal   (Followers: 12)
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
Computational Science and Discovery     Full-text available via subscription   (Followers: 2)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 6)
Computer Science and Engineering     Open Access   (Followers: 17)
Computers & Geosciences     Hybrid Journal   (Followers: 25)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 5)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 4)
Computers and Geotechnics     Hybrid Journal   (Followers: 8)
Computing and Visualization in Science     Hybrid Journal   (Followers: 6)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 25)
Conciencia Tecnologica     Open Access  
Concurrent Engineering     Hybrid Journal   (Followers: 3)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 6)
Control and Dynamic Systems     Full-text available via subscription   (Followers: 7)
Control Engineering Practice     Hybrid Journal   (Followers: 40)
Control Theory and Informatics     Open Access   (Followers: 7)
Corrosion Science     Hybrid Journal   (Followers: 24)
CT&F Ciencia, Tecnologia y Futuro     Open Access  
CTheory     Open Access  
Current Applied Physics     Full-text available via subscription   (Followers: 4)

        1 2 3 4 5 6 | Last

Journal Cover Applied Clay Science
  [SJR: 0.826]   [H-I: 83]   [4 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0169-1317
   Published by Elsevier Homepage  [3032 journals]
  • Development and characterization of porous membranes based on
           kaolin/chitosan composite
    • Authors: Sonia Bouzid Rekik; Sana Gassara; Jamel Bouaziz; André Deratani; Semia Baklouti
      Pages: 1 - 9
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Sonia Bouzid Rekik, Sana Gassara, Jamel Bouaziz, André Deratani, Semia Baklouti
      Chitosan/kaolin composite porous membranes were successfully prepared by solvent casting and evaporation process. The suspensions with different concentration of kaolin and chitosan showed a Newtonian behaviour. Strong interaction between chitosan and kaolin was revealed by FTIR and thermogravimetric analysis. The effect of kaolin content on the morphology and properties of the obtained membranes was studied. It was found by SEM observation that the kaolin particles were well dispersed in the chitosan matrix generating a porous microstructure. Incorporation of kaolin particles also improved the mechanical and thermal properties of the membranes and reduced drastically the water washout of chitosan in moderate acidic medium. Owing to their porous structure, the water permeability of the composite chitosan/kaolin membrane was significantly enhanced. The better formulation of the dope suspension in the range studied was 4% chitosan and 5% kaolin in acetic acid. These membranes made from naturally occurring materials might play an important role in advanced research in water treatment and environmental science.

      PubDate: 2017-03-16T09:26:35Z
      DOI: 10.1016/j.clay.2017.03.008
      Issue No: Vol. 143 (2017)
       
  • Clay mineralogy of altered tephra beds and facies correlation between the
           Permian-Triassic boundary stratigraphic sets, Guizhou, south China
    • Authors: Hanlie Hong; Qian Fang; Chaowen Wang; Gordon Jock Churchman; Lulu Zhao; Nina Gong; Ke Yin
      Pages: 10 - 21
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Hanlie Hong, Qian Fang, Chaowen Wang, Gordon Jock Churchman, Lulu Zhao, Nina Gong, Ke Yin
      The Permian-Triassic boundary (PTB) successions in south China contain numerous altered volcanic ash (tephra) beds (K-bentonites), which presents the opportunity to correlate the PTB position in both marine and non-marine sections, especially when no feasible biostratigraphic markers are available in the profiles. Clay mineralogical and geochemical studies of two altered ash beds in the Zhongzai (ZZ) and Tucheng (TC) sections, in Guizhou Province, south China, deposited in littoral and interactive marine-terrestrial environments, respectively, permit an investigation of the alteration of ash and correlation of ash beds between disparate facies. The results show that the two ZZ altered ashes consist of mainly R1 I/Sm and minor R0 I/Sm. Sample ZZ-1 has slightly more R1 I/Sm but less R0 I/Sm relative to sample ZZ-2. The TC ash samples contain mainly kaolinite and mixed-layer kaolinite/smectite (K/Sm). The poorly-crystallized kaolinite is present in pseudo-hexagonal plates, and the well-crystallized kaolinite occurs in book-like aggregates in veins or cavities. K/Sm minerals are derived from the transformation of smectite to kaolinite. Obviously, the TC ashes experienced terrestrial weathering and resedimentation prior to final burial and preservation, and local microenvironmental conditions control the formation of clay minerals. The ZZ ash samples have markedly higher 87Sr/86Sr values than those of the TC samples. The notable difference in 87Sr/86Sr value of ash beds between the sections is attributed to variations in RbSr partitioning during the chemical weathering process in different environments. The ZZ ash samples have notably higher 143Nd/144Nd ratios than those of the TC samples, suggesting that the ZZ ashes are likely derived from eruptions involving continental crust and the TC ashes originate from eruptions involving new continental island arcs, in agreement with the REE distributions and the Ti vs. Zr, TiO2 vs. Al2O3, and Zr/TiO2 vs. Nb/Y discrimination plots. The occurrence of tephras from such markedly different volcanic source materials different in PTB stratigraphic sets previously believed to be synchronous, Guizhou, south China, suggests that correlation between disparate facies by an ash marker requires geochemical fingerprinting of the materials to confirm correlations or otherwise.

      PubDate: 2017-03-16T09:26:35Z
      DOI: 10.1016/j.clay.2017.03.014
      Issue No: Vol. 143 (2017)
       
  • Mechanochemically activated saponite as materials for Cu2+ and Ni2+
           removal from aqueous solutions
    • Authors: L. Petra; P. Billik; Z. Melichová; P. Komadel
      Pages: 22 - 28
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): L. Petra, P. Billik, Z. Melichová, P. Komadel
      Saponites are nanosized layered aluminosilicates from the smectite group of clay minerals, which can be further functionalized to prepare low-cost materials for water purification. Mechanochemical activation of saponite was achieved by high-energy grinding in a planetary ball mill. X-ray diffraction, infrared spectroscopy, scanning electron microscopy, thermal analysis, and the determination of cation-exchange capacity and specific surface area were used to characterize parent and functionalized solids. Prepared adsorbents were used for Cu2+ and Ni2+ removal from aqueous solutions. Compared to the untreated sample, activated saponites had significantly increased capacity to take away metal cations. The equilibrium data showed the maximum of Cu2+ and Ni2+ uptake of 295 and 129mg/g, respectively. In comparison with the pristine material, the measured values increased by 764% and 170% for Cu2+ and Ni2+ respectively. The formation of reactive Mg(OH)2 as the saponite decomposition product was also discussed.
      Graphical abstract image

      PubDate: 2017-03-16T09:26:35Z
      DOI: 10.1016/j.clay.2017.03.012
      Issue No: Vol. 143 (2017)
       
  • Properties and application of Nigerian bentonite clay deposits for
           drilling mud formulation: Recent advances and future prospects
    • Authors: Richard O. Afolabi; Oyinkepreye D. Orodu; Vincent E. Efeovbokhan
      Pages: 39 - 49
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Richard O. Afolabi, Oyinkepreye D. Orodu, Vincent E. Efeovbokhan
      The vast deposits of Nigerian bentonite clay have many significant uses in different aspects of industrial fields of which the oil and gas industry is a potential consumer of this clay mineral. In this review article, the key mineralogical characteristics and rheological properties of these clay deposits in various locations and their related application for drilling mud formulation were comprehensively reviewed. Various research efforts on these bentonite clay deposits over the past couple of years were summarized with some critical comments and analysis. Attention was given to the clay reserve estimates, mineralogy of the clay deposits, chemical modification of the clays, rheological properties of drilling mud formulated from these clays and its suitability for drilling operations. Moreover, future prospects and key problems to be solved regarding the use of Nigerian bentonite deposits for drilling mud formulation were discussed. This review shed new light on both fundamental and practical studies that are concentrated on the use of Nigerian bentonite for drilling mud formulation.

      PubDate: 2017-03-20T21:52:04Z
      DOI: 10.1016/j.clay.2017.03.009
      Issue No: Vol. 143 (2017)
       
  • Physical and chemical characterization and recovery of potash fertilizer
           from glauconitic clay for agricultural application
    • Authors: Saurabh Shekhar; D. Mishra; A. Agrawal; K. K Sahu
      Pages: 50 - 56
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Saurabh Shekhar, D. Mishra, A. Agrawal, K. K Sahu
      Glauconite is a natural occurring iron-rich, heterogeneous, phyllosilicate rock containing around 4–8% of potash (K2O) locked in the alumino-silicate matrix. An attempt has been made to develop a complete flow-sheet for the recovery of potash from a typical glauconite sample containing 3.93% K2O, 10.75% Fe2O3, 4.41% Al2O3 and 70.35% SiO2. Initially, the detail physico-chemical characterization and beneficiation study was performed to enrich the potash content from 3.93% to 5.52% by removing free silica. The enriched fraction of glauconite was further processed to recover locked potash through chemical treatment. Potassium recovery by direct acid leaching was found to be very poor and also resulted in simultaneous dissolution of iron. Therefore, a combined sulfation roasting–water leaching process was developed to break the matrix and selectively recover potash. Various parameters such as sulphuric acid concentration, roasting and leaching temperature were optimized to achieve >98% potash dissolution. The potassium from the leach solution was recovered as sulfate of potash (SOP) suitable for fertilizer application.
      Graphical abstract image

      PubDate: 2017-03-20T21:52:04Z
      DOI: 10.1016/j.clay.2017.03.016
      Issue No: Vol. 143 (2017)
       
  • Nanohybrid sensor based on carboxyl functionalized graphene dispersed
           palygorskite for voltammetric determination of niclosamide
    • Authors: Zhouxiang Zhang; Yuanyuan Yao; Jingkun Xu; Yangping Wen; Jie Zhang; Wanchuan Ding
      Pages: 57 - 66
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Zhouxiang Zhang, Yuanyuan Yao, Jingkun Xu, Yangping Wen, Jie Zhang, Wanchuan Ding
      The stably dispersible palygorskite (Pal) nanorods onto carboxyl functionalized graphene (Gr-COOH) nanosheets were successfully employed for the facile fabrication of a novel nanohybrid sensing platform and the voltammetric determination of niclosamide (NA) in tablet and paddy water samples. A water-processable Gr-COOH can improve the dispersion and stability in water of Pal. The structure and properties of the formed Pal-Gr-COOH nanohybrid were characterized. The electrochemical behavior of NA, analytical conditions and the sensing performance of the prepared sensor were investigated. The sensor displayed the enhanced synergistically electrocatalytic ability toward NA in a linear range from 0.02–0.99μM with low limit of detection (4.6nM), good sensitivity, high reproducibility and satisfactory practicability, suggesting Pal-Gr-COOH nanohybrid will provide a promising platform for sensing application and facile preparation and potential application of other nanoclay mineral nanocomposites.
      Graphical abstract image

      PubDate: 2017-03-20T21:52:04Z
      DOI: 10.1016/j.clay.2017.03.013
      Issue No: Vol. 143 (2017)
       
  • Tailored montmorillonite nanoparticles and their behaviour in the alkaline
           cement environment
    • Authors: Juliana Calabria-Holley; Styliani Papatzani; Benjamin Naden; John Mitchels; Kevin Paine
      Pages: 67 - 75
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Juliana Calabria-Holley, Styliani Papatzani, Benjamin Naden, John Mitchels, Kevin Paine
      This is the first time an analytical protocol is proposed to investigate and live-monitor the behaviour of montmorillonite nanoparticles, of different natures, in alkaline cement environment (pH of 12–13). In this study inorganic and organomodified montmorillonite nanoparticles were characterised via TEM, XRD, SEM-EDX and TGA. The inorganic montmorillonite used consisted of a purified montmorillonite commercially available as HPS-clay, and an organomodified montmorillonite, namely XDB-organoclay, consisted of purified montmorillonite modified with Noramonium MB2HT salt. Both montmorillonite nanoparticles were tailored to increase their compatibility with the hydrating cement environment. This gave rise to three different slurries: (i) reference-slurry, (ii) inorganic-slurry, and (iii) organic-slurry. The slurries were characterised and investigated through UV/vis, to measure suspension quality in terms of physical stability and rheological properties, and by AFM and FTIR to determine the chemical stability. The results indicated that the organic-slurry can offer a good stability, preventing aggregation of the clay particles at the targeted pH (13). The inorganic-slurry showed a reduction in surface charge and increased double layer repulsion. At pH13 it was possible to obtain dispersion of the reference slurry although it underwent gelation and became viscous. The research findings informed that the inorganic slurry favours miscibility of the montmorillonite nanoparticles with cement particles and offers additional nucleation sites for CSH. Therefore it can be considered an alternative to organomodified montmorillonite as an addition in cement based materials.
      Graphical abstract image

      PubDate: 2017-03-20T21:52:04Z
      DOI: 10.1016/j.clay.2017.03.005
      Issue No: Vol. 143 (2017)
       
  • Effect of dietary palygorskite on performance of lactating ewes
    • Authors: B. Kotsampasi; V.A. Bampidis; C. Christodoulou; N. Theophilou; V. Christodoulou
      Pages: 76 - 79
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): B. Kotsampasi, V.A. Bampidis, C. Christodoulou, N. Theophilou, V. Christodoulou
      Twenty eight lactating Chios ewes were used in an experiment to determine effects of dietary activated micronized palygorskite (Pal; Sanfed® Ultra, Geohellas SA, Athens, Greece) supplementation on productivity and milk composition. In the experiment, which started on day 43 postpartum, ewes were allocated after equal distribution relative to milk yield and lactation number (i.e., 2 or 3), into 4 treatment groups being Pal0, Pal2.5, Pal5.0 and Pal7.5 of 7 ewes each and accommodated in individual pens. For a period of 60days (i.e., days 43–102 postpartum), ewes were fed one of four isonitrogenous (crude protein 175g/kg, dry matter (DM) basis) and isoenergetic (net energy for lactation (NEl) 7.69MJ/kg DM) concentrates (1.35kg DM/ewe/day) and alfalfa hay (1.02kg DM/ewe/day). The concentrate for treatment Pal0 (Control) had no Pal, while that for treatments Pal2.5, Pal5.0 and Pal7.5 contained 2.5, 5.0 and 7.5g/kg of Pal (as mixed basis), respectively. All ewes remained healthy until the end of the experiment without visually altered behavior. In the 60day experimental period, milk fat, crude protein and NEl contents were highest with the Pal5.0 treatment (P<0.01, P=0.01 and P<0.01, respectively). In contrast, milk lactose content was lowest (P<0.01) with the Pal2.5 treatment. With increased Pal feeding, milk fat and NEl yields were highest with the Pal5.0 treatment (P<0.01 and P=0.03, respectively), but milk yield and yields of other components, as well as milk somatic cell counts and colony forming units were not affected. Dietary Pal supplementation, at levels up to 5.0g/kg, in isonitrogenous and iso-NEl diets fed to lactating ewes increased milk fat and NEl yields and improved milk quality, increasing fat, crude protein and NEl contents, while, at higher level (7.5g/kg), dietary Pal supplementation did not affect milk yield and composition, with optimal Pal feeding levels identified between 3.4 and 4.0g/kg of concentrate.

      PubDate: 2017-03-20T21:52:04Z
      DOI: 10.1016/j.clay.2017.03.020
      Issue No: Vol. 143 (2017)
       
  • Gold nanoparticle-decorated halloysite nanotubes – Selective catalysts
           for benzyl alcohol oxidation
    • Authors: Anish Philip; Jenna Lihavainen; Markku Keinänen; Tuula T. Pakkanen
      Pages: 80 - 88
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Anish Philip, Jenna Lihavainen, Markku Keinänen, Tuula T. Pakkanen
      Preparation of gold nanoparticle-decorated halloysite nanotubes (Au-Hal) by a deposition method and evaluation of their catalytic activity in an oxidation of benzyl alcohol are reported. An electrostatic attraction between positively charged polyethylenimine (PEI)-capped gold nanoparticles and the negatively charged external surfaces of halloysite nanotubes (Hal nanotubes) was the key factor in fabrication of Au-Hal nanotubes. Au-Hal catalysts showed good conversions and surprisingly high benzaldehyde selectivities (above 90%) in the benzyl alcohol oxidation. Influence of the amount of PEI used as a capping agent, the gold content and calcination of Au-Hal catalysts on the conversion and selectivity was investigated. A notable increase in the benzaldehyde selectivity at higher PEI contents and a significant drop in the benzaldehyde selectivity on calcination clearly indicate the central role of PEI in the selective formation of benzaldehyde. The high benzaldehyde selectivity of uncalcined catalysts are probably due to PEI donor molecules coordinating to certain surface sites on Au nanoparticles and thus blocking the catalytic sites required for further oxidation of benzaldehyde to benzoic acid. The high combined selectivity of benzoic acid and benzyl benzoate obtained with the calcined catalysts indicates that naked gold nanoparticles have the catalytic sites available for the benzoic acid formation.
      Graphical abstract image

      PubDate: 2017-03-27T15:51:32Z
      DOI: 10.1016/j.clay.2017.03.015
      Issue No: Vol. 143 (2017)
       
  • Understanding the clay-PEG (and hydrophobic derivatives) interactions and
           their effect on clay hydration and dispersion: A comparative study
    • Authors: Santiago Villabona-Estupiñán; Jorge de Almeida Rodrigues; Regina Sandra Veiga Nascimento
      Pages: 89 - 100
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Santiago Villabona-Estupiñán, Jorge de Almeida Rodrigues, Regina Sandra Veiga Nascimento
      In oil and gas well drilling, the effective minimization of clay-water interactions is an essential function that water-based drilling fluids must meet in order to maintain the integrity of the shale formations as well as suitable rheological properties. In this work, the protective effect of poly(ethylene glycol) 2000 (PEG2000) and two hydrophobic derivatives on the hydration and dispersion of reactive clay materials was investigated. Thus, conventional inhibition tests were combined with adsorption measurements and analyses by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and thermogravimetry (TGA) in an attempt to establish structure-performance relationships. It was found that both PEG2000 and its hydrophobic derivatives can strongly adsorb, in equimolar amounts, on mineral clay following a Langmuir type behavior, in which bilayers are formed in the clay interlayer region at surface saturation. It was found that the PEG backbone rules the adsorption process, while the hydrocarbon tails of the hydrophobically modified products do not play a decisive role. However, it was verified that hydrocarbon tails play a central role in the mechanism of inhibition of clay particles hydration. Bentonite inhibition test revealed that the incorporation of two hydrocarbon tails at the PEG2000 chain ends duplicate the performance of oligomer, regarding the product with just one tail.
      Graphical abstract image

      PubDate: 2017-03-27T15:51:32Z
      DOI: 10.1016/j.clay.2017.03.021
      Issue No: Vol. 143 (2017)
       
  • Preparation of aggregates based on waste foundry sand: Reuse of calcined
           clay
    • Authors: Ruofei Xiang; Yuanbing Li; Keke Huang; Shujing Li
      Pages: 101 - 106
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Ruofei Xiang, Yuanbing Li, Keke Huang, Shujing Li
      Used calcined clay, waste foundry sand (WFS), was adopted to prepare aggregates with the addition of clay, alumina powder, and bran. Bulk density, porosity, cold crushing strength, phase compositions, microstructure, and thermal conductivity were investigated. Thermal calculation was adopted to assess the generation of the liquid phase during sintering. In the specimens composed of WFS and clay, the increase in clay concentration led to a decrease in cold crushing strength even if the variation in bulk density was not obvious. When WFS, clay, alumina powder, and bran were adopted in manufacturing aggregates, the addition of bran influenced the phase composition of the samples because of the formation of pores. With an increased WFS content, the cold crushing strength improved due to an increase in the amount of liquid phase during the sintering process. The thermal conductivities obtained from the samples by mechanical pressing were ideal and showed the influence of heat shielding effect from zircon.

      PubDate: 2017-03-27T15:51:32Z
      DOI: 10.1016/j.clay.2017.03.027
      Issue No: Vol. 143 (2017)
       
  • DFT study of the intercalation of layered double hydroxides and layered
           hydroxide salts with dodecylsulfate and dodecylbenzene sulfonate:
           Exfoliation and hydration properties
    • Authors: Sérgio R. Tavares; Fernando Wypych; Alexandre A. Leitão
      Pages: 107 - 114
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Sérgio R. Tavares, Fernando Wypych, Alexandre A. Leitão
      DFT calculations were performed for the simulation of the intercalations of Zn2Al-layered double hydroxide and Zn-layered hydroxide salts with dodecylsulfate and dodecylbenzene sulfonate. A structural and energetic analyses of the exfoliation processes were computed and compared with Perdew-Burke-Ernzerhof exchange-correlation (PBE) and Van der Waals-aware density (vdW-DF) functionals and with the semi-empirical approach DFT-D2. It could be concluded that the layers cell parameters were not affected by the applied approach. On the other hand, the basal spacing and the exfoliation energies presented variations with respect to the simulation. The influence of water molecules hydrating the polar heads of the anions intercalated in the interlayer region was also investigated. Furthermore, the interactions between the anions and the positive layers and the influence of hydration waters could be resolved by means of charge density difference plots and Bader charges. Projected density of states (PDOS) showed the possible acid and basic sites of these compounds for both dehydrated and hydrated structures.
      Graphical abstract image

      PubDate: 2017-03-27T15:51:32Z
      DOI: 10.1016/j.clay.2017.03.018
      Issue No: Vol. 143 (2017)
       
  • Mixed matrix hollow fibre membrane comprising polyetherimide and modified
           montmorillonite with improved filler dispersion and CO2/CH4 separation
           performance
    • Authors: Asif Jamil; Oh Pei Ching; Azmi M. Shariff
      Pages: 115 - 124
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Asif Jamil, Oh Pei Ching, Azmi M. Shariff
      Mixed matrix membrane with nano-filler embedded in polymer matrix, is receiving overwhelming attention for gas separation applications due to its attractiveness in providing an economic solution to enhance permselectivity. However, achieving uniform dispersion of nano-filler in host polymer remains a key challenge in developing membrane. In this work, mixed matrix hollow fibre membranes comprising polyetherimide (PEI) with various modified montmorillonite (f-Mt) loading, was developed via phase inversion method for CO2/CH4 separation. The Mt was modified with aminolauric acid to impart organophilicity to enhance compatibility towards organic polymer matrix. The synthesized hollow fibers were characterized using field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), and permeation test. The permeation tests were carried out with pure gases at ambient temperature with varying pressures of 2 and 4 bars. An increasing trend in ideal selectivity was observed up to 2wt% f-Mt loading. Thereafter, opposite trend was observed with increasing filler loading due to exfoliated layers that created more tortuous path for the penetrating gas molecules. The maximum ideal selectivity was found with 2wt% f-Mt loading at 2bar, which showed 39% increment as compared to neat PEI hollow fibre membrane. This increment in gas selectivity was related to the dispersion state and aspect ratio of f-Mt. Various phenomenological models were employed to calculate the aforementioned properties. Adopting to Cussler and Yang-Cussler models, the aspect ratio of the f-Mt was found to be 35 and 50, respectively with 3–4 particles per tactoid.

      PubDate: 2017-03-27T15:51:32Z
      DOI: 10.1016/j.clay.2017.03.017
      Issue No: Vol. 143 (2017)
       
  • Fabrication, microstructural and mechanical characterization of Luffa
           Cylindrical Fibre - Reinforced geopolymer composite
    • Authors: Mazen Alshaaer; Saida Abu Mallouh; Juma'a Al-Kafawein; Yasair Al-Faiyz; Tarek Fahmy; Abderrazek Kallel; Fernando Rocha
      Pages: 125 - 133
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Mazen Alshaaer, Saida Abu Mallouh, Juma'a Al-Kafawein, Yasair Al-Faiyz, Tarek Fahmy, Abderrazek Kallel, Fernando Rocha
      This study reports on the preparation, microstructure, density and mechanical properties of new geopolymer composites (LG-composite) that are unidirectionally and randomly reinforced with 10vol% natural Luffa Cylindical fibres (LCF). The geopolymer matrix was synthesized from metakaolin activated with sodium silicate and sodium hydroxide solutions. A greater amount of geopolymer gel was formed after introducing the LCF into the geopolymer matrix. As a result of the strong alkali setting reactions (geopolymerization), the hemicelluloses and lignin present in the LCF were extracted, leaving a rough LCF surface. In this way the hydrophobicity of the rough LCF increased and helped strengthen the bonding between fibre and geopolymer matrix. Two main morphological types of crystalline objects were observed in the LG-composite due to the incorporation of the extracted constituents of LCF: fibre-like crystals, or whiskers, and fine crystals of cubic shape. These crystals assist in crack healing while increasing the tensile strength and toughness of the composite. In terms of mechanical properties, it is found that by introducing LCF as reinforcement, the compressive and flexural strengths of the end geopolymeric products respectively increase from 13 MP and 3.4MPa up to 31MPa and 14.2MPa. The LCF-reinforced geopolymer composite exhibited ductile-like failure with a strain hardening Modulus of 72MPa, unlike the brittle matrix. In addition, the bulk density decreases from 1.5g/cm3 to 1.38g/cm3. A preliminary aging study has demonstrated that the LG-composite shows no significant deterioration in mechanical performance over a duration of 20months.

      PubDate: 2017-03-27T15:51:32Z
      DOI: 10.1016/j.clay.2017.03.030
      Issue No: Vol. 143 (2017)
       
  • X-ray coupled Laser Desorption Ionization assessment of layered double
           hydroxides for nitrate adsorption based on ion size, affinity and
           compromised layer height
    • Authors: Jaybalan Tamahrajah; Irina Goncharova; Ivan Pytskii; Andrey A. Shiryaev; Alexey A. Averin; Michail R. Kiselev; Alevtina Shaphigulina; Wan Jefrey Basirun; Alexey K. Buryak; Galina A. Pethukova; Frank Roessner
      Pages: 134 - 141
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Jaybalan Tamahrajah, Irina Goncharova, Ivan Pytskii, Andrey A. Shiryaev, Alexey A. Averin, Michail R. Kiselev, Alevtina Shaphigulina, Wan Jefrey Basirun, Alexey K. Buryak, Galina A. Pethukova, Frank Roessner
      The adsorption of nitrates with NO3(aq) solutions ranging from 20mg/L to 400mg/L with Layered-Double-Hydroxides (LDH) PURAL 70 (Mg70) and an Erbium containing LDH (Er40) were investigated. The X-ray Diffraction measurements (XRD) are accompanied by complemented Matrix Assisted Laser Desorption Ionization-Time of Flight (MALDI-TOF) measurements for prove of NO3- containing LDH. The shift in the XRD reflection angle for both Mg70 and Er40 corresponds to MALDI-TOF Data for presence of nitrate for all LDH except for Er40MW, as its nitrate adsorption capacity is the lowest. Both methods show the adsorption of nitrates for microwaved LDH and further calcined LDH, proving the memory effect. UV–vis spectroscopy was used to determine the nitrate concentration. The study shows substantial amount of nitrate adsorption for all LDH. Adsorption ranges from 2 to 5mg-NO3(aq)/g-LDH for initial NO3(aq) concentration from 20mg/L to 400mg/L. Leaching of element from the LDH structure is done by ICP-MS measurements to guarantee no further pollution of environmental waters with mentioned elements. Leaching for Mg ranges from170 to 1600mg/m3 and Al, Er and Fe leaching is less than 10mg/m3.
      Graphical abstract image

      PubDate: 2017-03-27T15:51:32Z
      DOI: 10.1016/j.clay.2017.03.022
      Issue No: Vol. 143 (2017)
       
  • A comparative study of the amaranth azo dye adsorption/desorption from
           aqueous solutions by layered double hydroxides
    • Authors: K. Abdellaoui; I. Pavlovic; M. Bouhent; A. Benhamou; C. Barriga
      Pages: 142 - 150
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): K. Abdellaoui, I. Pavlovic, M. Bouhent, A. Benhamou, C. Barriga
      Magnesium aluminum layered double hydroxides (LDH) were synthesized by the co-precipitation method with nitrate and carbonate as interlayer anion (MgAlNO3 and MgAlCO3) followed by the calcination of a carbonate containing LDH sample to obtain the mixed oxide MgAl500. The resulting materials were characterized by several physicochemical techniques. Calcined and uncalcined LDHs were used as adsorbents to remove the amaranth azo dye in an aqueous solution. Adsorption results indicated that MgAl500 had a greater adsorption capacity (1.6mmol·g−1) than non-calcined LDHs (0.8 and 0.2mmol·g−1for MgAlNO3 and MgAlCO3, respectively). Isotherms showed that the adsorption of the dye was consistent with the Langmuir model. The kinetic experiments of dye adsorption showed that the system reached the adsorption equilibrium in 3h for the three adsorbents. The kinetic data fitted well with the pseudo-second order model. Powder X ray diffraction patterns of the adsorption products suggest that adsorbed amaranth anion was intercalated in the MgAlNO3 interlayers by anion exchange and in the MgAl500 by the rehydration and reconstruction process, according to the value of the basal space d003 =17.7Å. Whereas in the case of MgAlCO3, .it was probably adsorbed on the external particle surface. The influence of common inorganic anions present in the solution was also studied and a decrease in the dye removal was observed in the following order HPO4 2−>CO3 2 – >SO4 2 − >Cl-. The dye desorption was tested with carbonate and phosphate solution and it was partial in all cases. The recyclability of the used adsorbents was performed by calcinations, and the percentage of removal decreases after the first cycle for MgAlNO3 and MgAl500. Dye removal improved after the first cycle then decreased after the second cycle for MgAlCO3.

      PubDate: 2017-04-03T16:26:09Z
      DOI: 10.1016/j.clay.2017.03.019
      Issue No: Vol. 143 (2017)
       
  • Electrochemically synthesized cobalt redox active layered double
           hydroxides for supercapacitors development
    • Authors: Ylea Vlamidis; Erika Scavetta; Marco Giorgetti; Nicola Sangiorgi; Domenica Tonelli
      Pages: 151 - 158
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Ylea Vlamidis, Erika Scavetta, Marco Giorgetti, Nicola Sangiorgi, Domenica Tonelli
      This paper describes the electrosynthesis and characterization in alkaline solutions of two layered double hydroxides (LDHs) containing Co as divalent cation and Al or Fe as trivalent one on Pt supports. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) experiments demonstrated a capacitive behaviour. LDHs containing Al3+ or Fe3+ displayed different responses, highlighting a key role of the trivalent metal. High specific capacitances calculated from charge-discharge experiments at a current density of 1Ag−1, were displayed by the two materials and resulted 854 and 869Fg−1 for the Al or Fe containing LDH, respectively. The long-term cycling capability was also investigated giving satisfactory results. The presence of Fe improves the performance of the LDH as pseudocapacitor, especially to achieve better performances in terms of energy and power densities. In view of the development of low cost supercapacitors preliminary tests aimed to deposit Co based LDHs on a large area graphite substrate were also successfully carried out.

      PubDate: 2017-04-11T17:14:07Z
      DOI: 10.1016/j.clay.2017.03.031
      Issue No: Vol. 143 (2017)
       
  • Assessment of pozzolanic activity of calcined coal-series kaolin
    • Authors: Yuanyuan Liu; Shaomin Lei; Min Lin; Yang Li; Zhao Ye; Yanming Fan
      Pages: 159 - 167
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Yuanyuan Liu, Shaomin Lei, Min Lin, Yang Li, Zhao Ye, Yanming Fan
      Coal-series kaolin (from the Yichang region of China) was tested as a potential pozzolanic material to be used in the cement and concrete industry. Thermal treatment was used to activate the raw coal-series kaolin (RCK). Phase identification before and after calcination was studied by X-ray diffraction and Fourier transform infrared spectroscopy. The pozzolanic activity of calcined coal-series kaolin (CCK) was tested by two direct methods, modified Chapelle and Frattini tests, and one indirect method, strength activity index. Aside from thermal treatment, grinding process for CCK was also used to evaluate the effect of particle size distribution on pozzolanic activity. The results showed that pozzolanic activity of CCK was greatly influenced by dehydroxylation and particle size. The modified Chapelle test overestimated pozzolanic activity in the low pozzolanic region (0–1300mg CH/gCCK), and was suitable for complete dehydroxylation samples. The Frattini test accurately assessed CH consumption by pozzolanic reaction, and the strength activity index confirmed the physical effect contribution to CS enhancement at earlier stage and pozzolanic reaction contribution to enhanced microstructure (pore and grain size refinement) and hence improved mechanical strength of cementitious material at later stage.

      PubDate: 2017-04-03T16:26:09Z
      DOI: 10.1016/j.clay.2017.03.038
      Issue No: Vol. 143 (2017)
       
  • Photocatalytic Cr(VI) reduction by mixed metal oxide derived from ZnAl
           layered double hydroxide
    • Authors: Xiaoya Yuan; Qiuye Jing; Jingtao Chen; Li Li
      Pages: 168 - 174
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Xiaoya Yuan, Qiuye Jing, Jingtao Chen, Li Li
      Mixed metal oxide (MMO) is one of the most important photocatalyts intensively investigated for water remediation. In this study, ZnO/ZnAl2O4 (ZnAl-MMO) nanocomposite was readily prepared via one-step calcination of ZnAl-layered double hydroxide (ZnAl-LDH) at 900°C.·The obtained MMO composite was thoroughly characterized by powder X-ray diffraction (XRD), Scanning electron microscopy (SEM), High-resolution transmission electron microscopy (HRTEM), UV–Vis diffuse reflectance spectroscopy (DRS). ZnAl-MMO was composed of nano-scaled ZnO and ZnAl2O4 crystal grains of high crystallinity and exhibited strong UV light adsorption with a well-developed interface between the two components of the composite. ZnAl-MMO showed high photocatalytic Cr(VI) reduction activity under UV light irradiation and its rate constant was as high as 0.8134h−1. The photoreduction activity of ZnAl-MMO photocatalyt was ascribed to the synergistic effect between two components of the nanocomposite.
      Graphical abstract image

      PubDate: 2017-04-03T16:26:09Z
      DOI: 10.1016/j.clay.2017.03.034
      Issue No: Vol. 143 (2017)
       
  • A comparative study of co-precipitation and sol-gel synthetic approaches
           to fabricate cerium-substituted MgAl layered double hydroxides with
           luminescence properties
    • Authors: A. Smalenskaite; D.E.L. Vieira; A.N. Salak; M.G.S. Ferreira; A. Katelnikovas; A. Kareiva
      Pages: 175 - 183
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): A. Smalenskaite, D.E.L. Vieira, A.N. Salak, M.G.S. Ferreira, A. Katelnikovas, A. Kareiva
      Mg/Al/Ce layered double hydroxides (LDHs) intercalated with carbonate and hydroxide anions were synthesized using co-precipitation and sol-gel method. The obtained materials were characterized by thermogravimetric (TG) analysis, X-ray diffraction (XRD) analysis, fluorescence spectroscopy (FLS) and scanning electron microscopy (SEM). The chemical composition, microstructure and luminescent properties of these LDHs were investigated and discussed. The Ce3+ substitution effects were investigated in the Mg3Al1− x Ce x LDHs by changing the Ce3+ concentration in the metal cation layers from 0.05 to 10mol%. It was demonstrated, that luminescence properties of cerium-substituted LDHs depend on the morphological features of the host lattice.

      PubDate: 2017-04-03T16:26:09Z
      DOI: 10.1016/j.clay.2017.03.036
      Issue No: Vol. 143 (2017)
       
  • Effects of microstructure of clay minerals, montmorillonite, kaolinite and
           halloysite, on their benzene adsorption behaviors
    • Authors: Liangliang Deng; Peng Yuan; Dong Liu; Faïza Annabi-Bergaya; Junming Zhou; Fanrong Chen; Zongwen Liu
      Pages: 184 - 191
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Liangliang Deng, Peng Yuan, Dong Liu, Faïza Annabi-Bergaya, Junming Zhou, Fanrong Chen, Zongwen Liu
      Montmorillonite (Mt), kaolinite (Kaol) and halloysite (Hal) are commonly investigated porous clay minerals, but their performance for the adsorption of volatile organic compounds (VOC) was rarely studied. In this work, the dynamic adsorption of benzene, as a model VOC, on Mt, Kaol and Hal was investigated. The effect of the microstructures of the above-mentioned clay minerals on benzene adsorption were explored by comparing the benzene adsorption of the different derivates of these clay minerals, which were obtained by adjusting the interlayer space and the porosity of the clay minerals through heating treatment. Calcium-based montmorillonite (Ca2+-Mt) heated at 120°C exhibited higher benzene adsorption capacity (141.2mg/g) than sodium-based montmorillonite (Na+-Mt) heated at 120°C (87.1mg/g), because the interlayer distance of Ca2+-Mt was sufficiently large to accommodate the adsorption of benzene. However, for calcined Ca2+-Mt and Na+-Mt, the collapse of their interlayer space resulted in that the interlayer micropores no longer existed and reduced benzene adsorption. Kaol exhibited the lowest benzene adsorption capacity (56.7mg/g) among the studied clay minerals because its interlayer space was not available for adsorption and because its specific surface area (SSA) was relatively small. As a polymorph of Kaol but with a tubular morphology, Hal showed a higher benzene adsorption capacity than Kaol owing to its larger SSA. In particular, heating at 120°C resulted in the increase of the benzene adsorption of Hal, which was ascribed to the exposure of the adsorption sites initially occupied by water molecules. These results demonstrate that the benzene adsorption capacity of the above-mentioned clay minerals was not only highly related to their SSA but also strongly affected by their porosity features.

      PubDate: 2017-04-03T16:26:09Z
      DOI: 10.1016/j.clay.2017.03.035
      Issue No: Vol. 143 (2017)
       
  • Functional organoclay with high thermal stability and its synergistic
           effect on intumescent flame retardant polypropylene
    • Authors: Dan Xiao; Zhi Li; Xiaomin Zhao; Uwe Gohs; Udo Wagenknecht; Brigitte Voit; De-Yi Wang
      Pages: 192 - 198
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Dan Xiao, Zhi Li, Xiaomin Zhao, Uwe Gohs, Udo Wagenknecht, Brigitte Voit, De-Yi Wang
      In this work a novel functional modifier for clay with increased thermal stability and synergistic effect on the flame retardancy of intumescent flame retardant polypropylene (IFR PP) composites was developed. First, triphenyl(undec-10-enyl)phosphonium bromide (TPB) was synthesized and characterized by FT-IR and 1H NMR spectroscopy. TPB has a high thermal stability with an initial decomposition temperature of about 270°C. Subsequently, TPB was used to prepare functional organoclay (OC) by cation exchange reaction. OC was characterized by thermogravimetric analysis (TGA) and wide-angle X-ray scattering (WAXS). The interlayer distance of novel OC increased to 1.85nm. OC was used in IFR PP nanocomposites prepared by melt mixing. The morphology, thermal stability and fire behavior of these IFR PP nanocomposites were investigated by SEM, TEM, TGA, limiting oxygen index (LOI), vertical burning test (UL94), and cone calorimeter (CC) test. In comparison to IFR (18wt%) PP composites, IFR (16wt%)+OC (2wt%) PP nanocomposites passed the UL94 V-0 rating and showed no dripping. The LOI value decreased from 30.5 to 28.8 due to the use of low molar mass TBP. It was shown by cone calorimeter tests that the additional used of 1 or 2wt% OC leads to a reduced heat release rate, smoke production rate and total smoke production. All these experimental results showed that this novel OC provided an excellent synergistic effect on the flame retardancy of IFR PP composites. Finally, electron beam treatment was used to enhance the thermal stability of flame retardant nanocomposites.

      PubDate: 2017-04-03T16:26:09Z
      DOI: 10.1016/j.clay.2017.03.039
      Issue No: Vol. 143 (2017)
       
  • Novel ceramics prepared from inferior clay rich in CaO and Fe2O3:
           Properties, crystalline phases evolution and densification process
    • Authors: Feng Jiang; Yu Li; Lihua Zhao; Daqiang Cang
      Pages: 199 - 204
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Feng Jiang, Yu Li, Lihua Zhao, Daqiang Cang
      Inferior clay rich in CaO and Fe2O3 is a typical clay with huge reserves in southwest of China, which cannot be used in traditional aluminosilicate system ceramics. To efficiently utilize the inferior clay, a method of preparing novel ceramics containing CaO and Fe2O3 was put forward. In this study, effects of inferior clay proportion on properties, CaO on evolution of crystalline phases and Fe2O3 on densification process were analyzed by XRF, XRD, TG-DTA and SEM-EDS combined with physical properties tests. The results showed that addition of inferior clay (from 20 to 70wt%) significantly affected sintering temperature (from 1190 to 1130°C). High activity CaO decomposed by carbonate transformed into anorthite and diopside at low temperature. Fe2O3 promoted generation of low-temperature liquid phase, which facilitated densification process. The fired ceramics (60wt% inferior clay) sintered at 1130°C exhibited excellent properties with water absorption of 0.05%, linear shrinkage of 6.8% and flexural strength of 70MPa. This batch was applied into an industrial experiment and 1160m2 qualified ceramics (ISO 10545-4:2004) were fabricated.

      PubDate: 2017-04-11T17:14:07Z
      DOI: 10.1016/j.clay.2017.03.026
      Issue No: Vol. 143 (2017)
       
  • Phase transformation and morphology evolution of sepiolite fibers during
           thermal treatment
    • Authors: Yuedan Zhang; Lijuan Wang; Fei Wang; Jinsheng Liang; Songsong Ran; Jianfeng Sun
      Pages: 205 - 211
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Yuedan Zhang, Lijuan Wang, Fei Wang, Jinsheng Liang, Songsong Ran, Jianfeng Sun
      In this study, the phase transformation and micromorphology evolution of sepiolite fibers were studied along with the increase of temperature from 300 to 1300°C, using raw sepiolite samples as raw materials. Through characterization by scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD), thermo-gravimetric analysis (TGA/DTG) and differential scanning calorimeter (DSC), it was found that the determined transition temperature values for the dehydrations of the hygroscopic water and the zeolitic water were 120°C and 340°C, and the values for the dehydration of the bound water and the dehydroxylation of the hydroxyls were about 500°C and 810°C. Moreover, orthoenstatite (MgSiO3) was recrystallized from dehydroxylated phase at 852°C and then transformed into protoenstatite at 970°C, and enstatite crystals grew along with c-axis of the fiber with the increase of temperature. Amorphous phase as the other phase of sepiolite dehydroxylation recrystallized into cristobalite in the temperature range of 1130–1200°C and the samples began to melt at the above temperature range. In terms of morphology, both sepiolite bundles and laths remained constant after heating up to 1000°C and sintering phenomenon appeared when the temperature was up to 1100°C. The bundles partly melted and adhered each other, which further formed a porous structure after calcination at 1200°C. When the temperature was up to 1300°C, the sample substantially melted except for a small amount of enstatite and cristobalite crystals. The present study reflects the thermal reaction of sepiolite, which could be applied in exploring the reinforcement mechanism of sepiolite reinforced ceramic body composites.

      PubDate: 2017-04-11T17:14:07Z
      DOI: 10.1016/j.clay.2017.03.042
      Issue No: Vol. 143 (2017)
       
  • Structural and thermodynamic investigation of the hydration-dehydration
           process of Na+-Montmorillonite using DFT calculations
    • Authors: Carla G. Fonseca; Viviane S. Vaiss; Fernando Wypych; Renata Diniz; Alexandre A. Leitão
      Pages: 212 - 219
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Carla G. Fonseca, Viviane S. Vaiss, Fernando Wypych, Renata Diniz, Alexandre A. Leitão
      This work is mainly focused on investigating the atomic structure of the interlayer water molecules inside Na+-Montmorillonite, their key interactions in the structure and the thermodynamics of the dehydration process. A theoretical study of the different degrees of hydration was performed using calculations based on DFT with several exchange-correlation functionals. The weak layer–water molecules interactions suggested the need of dispersion corrections to simulate correctly the basal spacing and the thermodynamic potentials for the dehydration process. The existence of the structures with sodium cation in planar geometry, representative of the one-water layer model and in octahedral geometry in a two-water layer model was confirmed. The stages of the dehydration of Na+–Mt were evaluated by thermodynamics calculations leading to a good description of the results from TGA/DTG studies. The thermodynamic data suggest also that the one-water layer structure as an intermediate with a metastable configuration.

      PubDate: 2017-04-11T17:14:07Z
      DOI: 10.1016/j.clay.2017.03.025
      Issue No: Vol. 143 (2017)
       
  • Ab initio simulations of the intercalation of iron(III) porphyrinates in
           Zn2Al-LDH: Structural analysis and evaluation of their basic and acid
           sites
    • Authors: Sérgio R. Tavares; Shirley Nakagaki; Fernando Wypych; Alexandre A. Leitão
      Pages: 220 - 226
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Sérgio R. Tavares, Shirley Nakagaki, Fernando Wypych, Alexandre A. Leitão
      Density functional theory (DFT) calculations were performed to study the interaction between three dehydrated porphyrinates anions after the intercalation between Zn2Al layered double hydroxide layers, reported experimentally. A good agreement was obtained for the unit cell parameters and an analysis of the simulation approaches was conducted for the first-generation porphyrin metallated with iron(III). Post-processing calculations were also performed in order to evaluate the stabilization of these intercalation compounds and to pinpoint the acid/basic sites. These intercalation compounds are mainly stabilized by charge transfers and, for the case of the iron(III)metallated porphyrins studied in the present work, the acidity of the iron(III) centers analyzed by PDOS was not significantly affected by the porphyrin ring phenyl substitutions.
      Graphical abstract image

      PubDate: 2017-04-11T17:14:07Z
      DOI: 10.1016/j.clay.2017.03.029
      Issue No: Vol. 143 (2017)
       
  • Kinetic, equilibrium and thermodynamic studies for sorption of
           2,4-dichlorophenol onto surfactant modified fuller's earth
    • Authors: Jasmin Shah; M. Rasul Jan; M. Zeeshan; M. Imran
      Pages: 227 - 233
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Jasmin Shah, M. Rasul Jan, M. Zeeshan, M. Imran
      The applicability of surfactant modified fuller's earth (SMFE) for removing 2,4-dichlorophenol (2,4-DCP) from water has been investigated through batch sorption process. Fuller's earth was treated with sodium dodecyl sulphate (SDS) for conversion of fuller's earth into surfactant modified fuller's earth. The influence of pH, agitation time, sorbent dose, temperature and initial concentration of 2,4-DCP were investigated. A strong dependence of the sorption capacity on pH was observed, the capacity increased as the pH value decreased. The sodium dodecyl sulphate increased the hydrophobicity of the sorbent and provided particular affinity for 2,4-DCP molecules. The SMFE showed high efficiency towards 2,4-DCP and >97% removal was achieved from an initial concentration of 20mg/L at 100°C using pH3. The kinetics of the sorption process was described by a pseudo-second-order kinetic model. The mechanism of sorption kinetics was investigated using intraparticle diffusion model. The sorption isotherm was consistent with the Langmuir sorption isotherm and maximum monolayer capacity of the SMFE was found to be 126.58mg/g at room temperature. The mean adsorption energy (E) value 18.25kJ/mol indicated chemical sorption and endothermic sorption process.

      PubDate: 2017-04-11T17:14:07Z
      DOI: 10.1016/j.clay.2017.03.040
      Issue No: Vol. 143 (2017)
       
  • A new approch to sepiolite dispersion by treatment with ionic liquids
    • Authors: Juliana A. de Lima; Fernanda F. Camilo; Roselena Faez; Sandra A. Cruz
      Pages: 234 - 240
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Juliana A. de Lima, Fernanda F. Camilo, Roselena Faez, Sandra A. Cruz
      The possibility of sepiolite disaggregation is a challenge to enhance significantly its performance and extend its application. In this direction, this work introduces the treatment of sepiolite (Sep) with three different ionic liquid (IL). The used ionic liquids were 1-methyl-3-butylimidazolium bis(trifluoromethanesulfonyl) imide (BMImTf2N), 1-methyl-3-octylimidazolium bis(trifluoromethanesulfonyl) imide (OMImTf2N) and 1-methyl-3- dodecylimidazolium bis(trifluoromethanesulfonyl) imide (DMImTf2N). The influence on structural, thermal properties and morphology in Sep treated with IL were evaluated using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TG), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), N2 sorption measurements, 29Si nuclear magnetic resonance (29Si NMR) and zeta potential. Sepiolite structure was preserved for all the samples treated with ionic liquids. FTIR and XRD results show that BMImTf2N substitutes water molecules coordinated to Mg+2 more efficiently. Thermogravimetric analysis indicated that the interaction between Sep and IL delayed the release of water. From these data, it was also possible to confirm the presence of 5 mass% of IL in all samples. FESEM and TEM images demonstrated more disaggregated Sep fibers with IL, especially the samples treated with BMImTf2N. This fact is attributed to the immobilization of ionic liquid on Sep tunnels, which is coherent with 29Si NMR analyses. The potential applications of these modified sepiolites are as reinforcing agent for polymers, template for nanostructured materials and support for catalysts.
      Graphical abstract image

      PubDate: 2017-04-18T09:08:33Z
      DOI: 10.1016/j.clay.2017.03.032
      Issue No: Vol. 143 (2017)
       
  • Synthesis and characterization of Zn-Al layered double hydroxide nanofluid
           and its application as a coolant in metal quenching
    • Authors: A.M. Tiara; Samarshi Chakraborty; Ishita Sarkar; Surjya K. Pal; Sudipto Chakraborty
      Pages: 241 - 249
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): A.M. Tiara, Samarshi Chakraborty, Ishita Sarkar, Surjya K. Pal, Sudipto Chakraborty
      The current study comprises of the synthesis and characterization of Zn-Al layered double hydroxide (LDH) nanofluid for use as a potential coolant in the steel industry. Coprecipitation method was used in the preparation of Zn-Al LDH nanoparticles by using the nitrate salts of Zn, Al and Na, in the ratio of 2:1:2. The nanofluids were characterized based on their particle size, stability, surface tension, thermal conductivity and viscosity. TEM analysis revealed that the nanoparticles were needle-shaped with an average particle size of 45.61nm and aspect ratio of 7.3. Different concentrations of the nanofluid, from 40ppm to 240ppm, were used to analyze the effect of particle concentration on the enhancement in thermal conductivity and viscosity. Stability analysis of the nanofluid exhibited good results, even without any stabilizer. An optimum cooling rate of 125°C/s was obtained for a nanofluid concentration of 160ppm, which is 1.29 times when compared to water.

      PubDate: 2017-04-11T17:14:07Z
      DOI: 10.1016/j.clay.2017.03.028
      Issue No: Vol. 143 (2017)
       
  • Acid clay minerals as eco-friendly and cheap catalysts for the synthesis
           of β-amino ketones by Mannich reaction
    • Authors: Fernando Gómez-Sanz; María Virtudes Morales-Vargas; Beatriz González-Rodríguez; María Luisa Rojas-Cervantes; Elena Pérez-Mayoral
      Pages: 250 - 257
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Fernando Gómez-Sanz, María Virtudes Morales-Vargas, Beatriz González-Rodríguez, María Luisa Rojas-Cervantes, Elena Pérez-Mayoral
      The characterization and catalytic performance of different smectites, one raw saponite and some commercial montmorillonites, exhibiting mesoporous and acid character are herein reported. The catalysts under study are able to catalyze efficiently via Mannich-type reactions the synthesis of β-amino ketones, which are important building blocks for the drugs synthesis and biologically active natural products. Montmorillonite K10 (Mt-K10) was the most efficient catalyst for the Mannich reaction between the pre-formed imine, N-benzylideneaniline, and cyclohexanone resulting in a recyclable catalyst for at least three catalytic cycles without activity loss. Almost quantitative yield to the β-amino carbonyl compound was obtained after 240min when operating under the most favorable conditions. The catalytic performance of the smectites seemed to be influenced by their porosity, but also by both Brönsted and Lewis acid site concentrations. In fact, the concentration of the Lewis acid catalytic sites would be the key in the Michael addition of cyclohexanone to the imine, although the Brönsted acid sites contribution cannot be neglected. The β-amino carbonyl compound was also synthesized in an excellent yield (86%) in only 15min of reaction time through the one-pot three component reaction, by reaction between benzaldehyde, aniline and cyclohexanone.
      Graphical abstract image

      PubDate: 2017-04-11T17:14:07Z
      DOI: 10.1016/j.clay.2017.03.033
      Issue No: Vol. 143 (2017)
       
  • Ceramic porcelain stoneware production with Spanish clays purified by
           means of the removal of iron compounds and organic matter using physical
           methods
    • Authors: E. Barrachina; I. Calvet; D. Fraga; J.B. Carda
      Pages: 258 - 264
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): E. Barrachina, I. Calvet, D. Fraga, J.B. Carda
      As the production of ceramic porcelain stoneware in Spain is totally conditioned by the importation of ball clays, because of the lack of adequate Spanish ball clays, this work has focused on the formulation of ceramic porcelain body from Spanish clays purified by means of physical removal processes. This method was applied to three Spanish clays containing common clay impurities of iron (hematite and siderite) and organic matter. Iron removal was carried out using the wet sieve method, the hydrocycloning method and the electromagnetic filtering method, obtaining a reduction in iron content of up to 80wt%, while the clay containing organic matter was treated thermally at 400°C for 30min so as to leave it almost completely purified. These treated clays, after being characterized (chemical and mineralogical composition, plasticity, organic carbon, thermal behaviour and colour), were used in the porcelain stoneware body composition instead of imported clays, the result being a composition capable of substituting the standard porcelain stoneware formulation in terms of sintering, morphology, colour, flexural strength and dilatometry.

      PubDate: 2017-04-11T17:14:07Z
      DOI: 10.1016/j.clay.2017.03.024
      Issue No: Vol. 143 (2017)
       
  • Efficiency of stress transfer between polymer matrix and nanoplatelets in
           clay/polymer nanocomposites
    • Authors: Yasser Zare; Mohammad Fasihi; Kyong Yop Rhee
      Pages: 265 - 272
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Yasser Zare, Mohammad Fasihi, Kyong Yop Rhee
      The Hui-Shia model, which considers the complete stress transfer between polymer matrix and particles (perfect interfacial adhesion), overpredicts the Young's modulus of clay/polymer nanocomposites (CPN). In this work, the effective aspect ratio and volume fraction of nanoclay are expressed assuming the imperfect load transfer, the minimum length of platelets required for efficient stress transfer (L c ) and the interfacial shear strength (τ). Additionally, “I” parameter as the level of stress transfer in CPN is defined and determined using the effective parameters. The large nanoclay platelets with low “L c ” give a high level of “I”. Also, high “L c ” and slight “τ” observe the poor levels of effective parameters and Young's modulus of CPN. The “I” values are calculated for some samples which indicate the different levels of stress transfer in CPN. It is possible to analyze the levels of interfacial properties and stress transfer in CPN using the developed model.

      PubDate: 2017-04-11T17:14:07Z
      DOI: 10.1016/j.clay.2017.03.043
      Issue No: Vol. 143 (2017)
       
  • Size-controlled synthesis of palygorskite/Ag3PO4 nanocomposites with
           enhanced visible-light photocatalytic performance
    • Authors: Jie Luo; Guorong Duan; Weiwei Wang; Yuting Luo; Xiaoheng Liu
      Pages: 273 - 278
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Jie Luo, Guorong Duan, Weiwei Wang, Yuting Luo, Xiaoheng Liu
      The synthesis of nanoparticles with a tight control on their sizes is a requirement for many nanotechnologies and application goals. Herein, a simple method has been reported to prepare size-controlled Ag3PO4 nanoparticles deposited on the surface of palygorskite (PAL) nanorods (called as PAL/Ag3PO4 nanocomposites). The particle size of Ag3PO4 could be well controlled by adjusting the concentration of PAL due to its typical negative surface charges and specific colloidal-rheological properties. Results show that the optimal content of PAL (20mass%) could be selected to obtain the perfect Ag3PO4 nanoparticles with the average diameter size of 10nm and the visible-light photocatalytic activity and stability of PAL/Ag3PO4 nanocomposites for degrading 10mg/L methyl orange (MO) solution were enhanced. This new work can provide a promising strategy for controllable preparation and efficient application of nanomaterials.

      PubDate: 2017-04-11T17:14:07Z
      DOI: 10.1016/j.clay.2017.04.004
      Issue No: Vol. 143 (2017)
       
  • Recent progress in layered double hydroxides (LDH)-containing hybrids as
           adsorbents for water remediation
    • Authors: Mukarram Zubair; Muhammad Daud; Gordon McKay; Farrukh Shehzad; Mamdouh A. Al-Harthi
      Pages: 279 - 292
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Mukarram Zubair, Muhammad Daud, Gordon McKay, Farrukh Shehzad, Mamdouh A. Al-Harthi
      With rapidly growing industrial development worldwide, the need for a new class of nanoparticles and techniques for treating wastewater remains a major concern to protect the environment. Layered double hydroxides and particularly LDH-containing hybrids are emerging as potential nano-sized adsorbents for water treatment. Recent studies have demonstrated LDH-containing hybrids as promising multifunctional materials for potential utilization in various applications such as, photo-catalysis, energy storage, nanocomposites and water purification. This article reviews the recent applications of LDH-containing hybrids as adsorbents for water remediation. The maximum adsorption capacities of various toxic heavy metals and dyes on different LDH hybrids were reported as 483mg/g for Pb2+, 95mg/g for Cd2+, 181mg/g for Cu2+, 649mg/g for Cr6+, 180mg/g As5+, 813mg/g for Hg2+, 450 for Ag+, 277mg/g for U6+, 1062mg/g for methyl orange, 185mg/g for methylene blue, and 1250mg/g for Congo red, which is comparatively higher than other commercial adsorbents. This review discusses the adsorption performance of manifold LDH-containing hybrids for treating various pollutants such as heavy metals and dyes. The mechanisms of interaction of LDH-containing hybrids with pollutants and the influence of key adsorption parameters such as pH, contact time, adsorbent dose and temperature have been comprehensively discussed. Moreover, the regeneration potential and reuse of spent LDH-containing hybrids and its toxicity effects have also been reviewed.
      Graphical abstract image

      PubDate: 2017-04-11T17:14:07Z
      DOI: 10.1016/j.clay.2017.04.002
      Issue No: Vol. 143 (2017)
       
  • Cs+ immobilization by designed micaceous adsorbent under subcritical
           conditions
    • Authors: Francisco J. Osuna; Agustín Cota; Esperanza Pavón; M. Carolina Pazos; María D. Alba
      Pages: 293 - 299
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Francisco J. Osuna, Agustín Cota, Esperanza Pavón, M. Carolina Pazos, María D. Alba
      The adsorption of Cs+ by clay minerals is a complicate process, being cation exchange and frayed-edge sites the major mechanisms that govern it. However, environmental variables have a significant impact on the process. In this work, the influence of the temperature and time in the cesium adsorption capacity of Na-Mica-n (n=2 and 4) have been explored under subcritical conditions. Those synthetic micas were able to immobilize cations Cs+ combining adsorption at nonspecific sites, at specific sites and chemical reaction. The distribution constant of Cs+ was larger in the Na-Mica-2 denoting a higher concentration of specific adsorption sites when layer charge decreased.
      Graphical abstract image

      PubDate: 2017-04-11T17:14:07Z
      DOI: 10.1016/j.clay.2017.03.041
      Issue No: Vol. 143 (2017)
       
  • Evaluation and reutilization of water sludge from fresh water processing
           plant as a green clay substituent
    • Authors: Yew Pei Ling; Ren-Haw Tham; Siew-Ming Lim; Muhammad Fahim; Chee-Heong Ooi; Puspanathan Krishnan; Akihiko Matsumoto; Fei-Yee Yeoh
      Pages: 300 - 306
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Yew Pei Ling, Ren-Haw Tham, Siew-Ming Lim, Muhammad Fahim, Chee-Heong Ooi, Puspanathan Krishnan, Akihiko Matsumoto, Fei-Yee Yeoh
      Water sludge from a fresh water processing plant in Sungai Dua Penang was investigated from the aspects of physicochemical properties and its reutilization possibility. Morphology and size distribution of the water sludge were studied via field emission scanning electron microscopy and sieving method, respectively. The water sludge particles of irregular shapes and sizes exhibited a relatively large specific surface area of 27m2/g, pore size of 8.8nm and pore volume of 0.05cm3/g. Besides, the water sludge chemical composition comprised of major components such as silica (SiO2, 40.33wt%) and alumina (Al2O3, 31.84wt%), which are the basic content of soil. The presence of aluminium in water sludge justified the addition of coagulant during water processing process. 97.9% of the mineral phase in the water sludge was identified as kaolinite (Al2Si2O5) and quartz (SiO2) that showed beneficial mechanical properties in the sludge-based products, e.g. pottery clay. Whereas hematite phase (Fe2O3, 1.6%) in water sludge contributes to the reddish color of the final products after firing, which makes an ideal raw material for terra cotta. Application of the water sludge as an environmentally friendlier green clay was explored through the clay reformulation. In short, reutilization of water sludge to partially replace mineral clay for ceramic products have been successful and may be useful in solving environmental issues and waste management.

      PubDate: 2017-04-18T09:08:33Z
      DOI: 10.1016/j.clay.2017.04.007
      Issue No: Vol. 143 (2017)
       
  • Fluid inclusion microthermometry to calibrate vitrinite reflectance
           (between 50 and 270°C), illite Kübler-Index data and the
           diagenesis/anchizone boundary in the external part of the Central Alps
    • Authors: Josef Mullis; Rafael Ferreiro Mählmann; Monika Wolf
      Pages: 307 - 319
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): Josef Mullis, Rafael Ferreiro Mählmann, Monika Wolf
      Fluid inclusion composition and homogenization temperatures in fibre and prismatic quartz from 45 Alpine fissures formed synkinematically during orogenic metamorphism in the external part of the Central Alps were compared with organic matter maturation determined by vitrinite reflectance %Rr (random)/%Rmax of the host rocks. Fluid immiscibility led to both, coexisting water bearing higher hydrocarbon- (HHC) or methane-rich fluid inclusions and HHC or methane bearing water-rich fluid inclusions. The homogenization temperatures of the latter reveal inclusion formation temperatures. Earliest fibre and prismatic quartz in diagenetic and low-grade anchimetamorphic rocks crystallized more or less close to maximum temperatures. Thus, the homogenization temperatures of hydrocarbon saturated water-rich fluid inclusions are used as geothermometer between ~50 and 270±5°C. The process of vitrinite maturation is irreversible and the level of organic maturity is basically the product of temperature and time at moderate pressures (~1 to ≥3kbar). Based on the close interaction of solid (vitrinite), liquid and volatile organic matter (i.e. HHC, CH4) and water, fluid inclusion homogenisation temperatures are used to calibrate vitrinite reflectance (VR) measurements in the temperature range from ~50 to 270±5°C. The following relationship between fluid inclusion homogenization temperatures, VR and fluid composition for the external part of the Central Alps has been established: 200 ± 5 ° C VR = 2.4 ± 0.2 % R max : Transition of higher hydrocarbons wet gas to methane with ≤ 1 mole % of wet gas 270 ± 5 ° C VR = 5.7 ± 0 . 7 % R max : End of the methane stability due to red ‐ ox reactions . Applying fluid inclusion data and the VR versus illite Kübler-Index (KI) correlation the paleo-geothermal gradient is determined. In different structural units of the external part of the Central Alps the conditions vary between 45 and ≤20°C/km. At these normal to slightly enhanced orogenic geothermal gradients and at a heat flow=65±10mW/m2 the KI 0.42 Δ°2θ of the diagenesis/anchizone boundary is fixed at: 240 ± 15 ° C and VR = 4.0 ± 0.7 % R max It is envisaged that this temperature limit may be indicative for external orogenic settings at normal to slightly hyperthermal heat flow. This will help to a better understanding of correlating organic matter versus clay mineral indices to determine geothermal settings for basic research and exploration.

      PubDate: 2017-04-18T09:08:33Z
      DOI: 10.1016/j.clay.2017.03.023
      Issue No: Vol. 143 (2017)
       
  • Green synthesis of g-C3N4/CuONP/LDH composites and derived g-C3N4/MMO and
           their photocatalytic performance for phenol reduction from aqueous
           solutions
    • Authors: Mihaela Mureseanu; Teodora Radu; Radu-Dorin Andrei; Mihaela Darie; Gabriela Carja
      Pages: 1 - 12
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Mihaela Mureseanu, Teodora Radu, Radu-Dorin Andrei, Mihaela Darie, Gabriela Carja
      A facile, environmentally friendly route for the synthesis of ZnAlLDH/g-C3N4/CuONP composite was demonstrated by exploiting the specific behaviour of the freshly calcined ZnAlLDH/melamine hybrids in Cu(OAc)2 aqueous solution. ZnAlLDH was synthesised and thereafter calcined at 550°C in air, in the absence or in presence of melamine, to obtain the mixtures of metal oxides (ZnAlMMO and ZnAlMMO/g-C3N4, respectively). Furthermore, by structural reconstruction of the freshly calcined ZnAlLDH in the aqueous solution of Cu(OAc)2 we transformed ZnAlMMO and ZnAlMMO/g-C3N4 into ZnAlLDH/CuONP and ZnAlLDH/g-C3N4/CuONP, respectively. The effects of coupling g-C3N4 with ZnAlLDH, but also the effects of the formation of CuONP on the surface of g-C3N4/ZnAlLDH on the morphology, structural, optical, electrochemical and thermal properties were investigated by powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), UV–Vis spectroscopy, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). The obtained results revealed a synergic heterojunction between the semiconductor components coupled with ZnAlLDH, with a tuned position of energy bands in the g-C3N4/ZnAlLDH and a good dispersion of CuONP in the composite. Furthermore, the heterojunction between g-C3N4 and calcined LDH was proved in ZnAlMMO/g-C3N4, which was an intermediate in the green synthesis of the reconstructed hydrotalcites. When tested for phenol photodegradation under irradiation with UV and Vis light the best efficiency was obtained for the ZnAlMMO/g-C3N4 sample (100% phenol conversion after 4h irradiation under UV, though 75% conversion was reached after 24h irradiation with Vis light). The mechanism of charge separation and the electron transfer in the heterojunction of g-C3N4 with CuONP and ZnAlLDH, was also discussed.
      Graphical abstract image

      PubDate: 2017-02-16T16:59:13Z
      DOI: 10.1016/j.clay.2017.02.012
      Issue No: Vol. 141 (2017)
       
  • Influence of voltage and temperature on electro-osmosis experiments
           applied on marine clay
    • Authors: Zhijia Xue; Xiaowei Tang; Qing Yang
      Pages: 13 - 22
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Zhijia Xue, Xiaowei Tang, Qing Yang
      A series of electro-osmosis experiments were conducted to explore the effect of voltage and temperature on the electro-osmosis properties of marine clay, including current, average consolidation degree, horizontal shrinkage, shear strength, water content, and anode corrosion. As shown for the resistivity of marine clay, the temperature increased when the electro-osmosis phenomenon occurred. From mechanical and electro-chemical point of view, this study explained the differences in the average consolidation degree and horizontal shrinkage under various experimental conditions. Although a voltage loss appeared due to the anode corrosion, the high voltage and temperature were still found beneficial for the reduction of the soil water content and the increase of shear strength. Furthermore, the electro-osmosis effect at high voltage included the contribution of joule heating.

      PubDate: 2017-02-23T18:22:10Z
      DOI: 10.1016/j.clay.2017.01.033
      Issue No: Vol. 141 (2017)
       
  • Design of pH-responsive antimicrobial nanocomposite as dual drug delivery
           system for tumor therapy
    • Authors: Fatemeh Bazmi Zeynabad; Roya Salehi; Mehrdad Mahkam
      Pages: 23 - 35
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Fatemeh Bazmi Zeynabad, Roya Salehi, Mehrdad Mahkam
      A novel antibacterial clay/polymer nanocomposite with average particle size of 20–40nm and two cationic compartments in polymer was synthesized via ion exchange. The structure of the nanocomposites was characterized by XRD, FT-IR, TG-DTA, and SEM. This multifunctional nanocomposite was used for dual drug delivery of anticancer drug methotrexate (MTX) and an antibacterial agent ciprofloxacin (CIP) with encapsulation efficiency of >90% for both drugs. The in vitro antimicrobial activity of the clay/polymer nanocomposites was studied against Escherichia coli and Pseudomonas aeruginosa bacteria by a well diffusion method. The nanocomposite showed good or moderate antimicrobial activities. However, CIP loaded nanocomposites showed enhanced antimicrobial activity in comparison to free CIP. The potential antitumoral activity of this clay/polymer nanocomposite system was evaluated against MCF7 cell lines by MTT assay and cell cycle studies. The cytotoxicity studies demonstrated enhanced cytotoxicity of developed MTX loaded nanocomposite in comparison to free MTX. Cell cycle study showed that MTX-loaded nanocomposite caused S-phased arrest in MCF-7 cells compared to control non-treated cells (P <0.001). Therefore, dual drug-loaded antibacterial nanocomposite has the potential to be used for cancer therapy.

      PubDate: 2017-02-23T18:22:10Z
      DOI: 10.1016/j.clay.2017.02.015
      Issue No: Vol. 141 (2017)
       
  • Multi-scale analysis and time evolution of pozzolanic activity of lime
           treated clays
    • Authors: E. Vitale; D. Deneele; M. Paris; G. Russo
      Pages: 36 - 45
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): E. Vitale, D. Deneele, M. Paris, G. Russo
      A multi-scale investigation on the influence of clay mineralogy on the pozzolanic activity of lime treated clays has been presented. Two clays of different mineralogy have been considered for this study, namely kaolin and bentonite. The time dependent mineralogical and microstructural changes induced by lime addition have been monitored at increasing curing time by means of X-ray diffraction (XRD), thermogravimetric analysis, 29Si NMR spectroscopy, Scanning electron microscopy (SEM) and nitrogen adsorption/desorption measurements. Different lime contents of the treated samples have been considered in order to highlight the ongoing of pozzolanic reactions. The time scale of chemical reactions taking place after the addition of lime depends on clay mineralogy. In the short term, flocculation phenomena due to the cation exchange reactions control the microstructural features of lime treated kaolin. The low reactivity of kaolinite clay minerals to pozzolanic reactions was detected as a delay in precipitation of new hydrated phases. The chemo-physical evolution of lime treated bentonite depends on the combined effect of cation exchange and pozzolanic reactions which develop with a comparable time scale. The results of micro-scale investigations were directly linked to the experimental evidences at volume scale of the samples, allowing an interpretation of the mechanical improvement of the treated clays in the short and long term as a function of the chemo-physical evolution of the system.

      PubDate: 2017-02-23T18:22:10Z
      DOI: 10.1016/j.clay.2017.02.013
      Issue No: Vol. 141 (2017)
       
  • Tortuosity model to predict the combined effects of crystallinity and
           nano-sized clay mineral on the water vapour barrier properties of
           polylactic acid
    • Authors: Bowen Tan; Noreen Louise Thomas
      Pages: 46 - 54
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Bowen Tan, Noreen Louise Thomas
      The combined effects of crystallinity and nano-sized clay mineral (montmorillonite) fillers on the water vapour barrier properties of poly(lactic acid) (PLA) nanocomposites are investigated. Both amorphous and semi-crystalline PLA nanocomposites containing 0 to 5wt% montmorillonite clay are prepared by melt compounding followed by compression moulding with two different thermal treatments: quenching and annealing. Thermal properties and morphology are investigated using differential scanning calorimetry (DSC), polarised light microscopy, transmission electron microscopy (TEM) and wide-angle X-ray diffraction (WAXD). It is confirmed that the nanocomposite structures are intercalated and the montmorillonite aspect ratio is measured to be 40 in both quenched and annealed samples. Water vapour transmission rates (WVTR) through the film samples are measured. A new tortuous path model is developed that fits the WVTR data and accounts for the effects of crystallinity as well as montmorillonite aspect ratio, concentration and orientation.
      Graphical abstract image

      PubDate: 2017-02-23T18:22:10Z
      DOI: 10.1016/j.clay.2017.02.014
      Issue No: Vol. 141 (2017)
       
  • Swelling deformation of compacted GMZ bentonite experiencing chemical
           cycles of sodium-calcium exchange and salinization-desalinization effect
    • Authors: Yong-Gui Chen; Ling-Yan Jia; Quan Li; Wei-Min Ye; Yu-Jun Cui; Bao Chen
      Pages: 55 - 63
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Yong-Gui Chen, Ling-Yan Jia, Quan Li, Wei-Min Ye, Yu-Jun Cui, Bao Chen
      In China, GMZ bentonite has been recognized as the first choice of buffer material while Beishan area in Gansu province has been considered as the potential disposal site for high-level radioactive waste (HLW) repository. As the groundwater at the repository field is rich in Na+ and Ca2+, the swelling properties of compacted GMZ bentonite will be affected by the chemistry of groundwater. In this work, the swelling deformation behaviors of compacted GMZ bentonite were tested at a vertical stress of 0.1MPa to assess the influence of cation exchange between Na+ and Ca2+, as well as the salinization-desalinization effect by cyclical infiltrations of distilled water and saline solutions. Results show that Na-bentonite is partly transformed into Ca-bentonite once NaCl solution is replaced with CaCl2 solution. Comparing to NaCl solution, the inhibiting effect of CaCl2 solution is weak, and thus the additional swelling is observed. Along with chemical cycles, the total strain of compacted GMZ bentonite gradually increases, while the chemical sensitivity of strain behavior reduces. This tendency is also detected for GMZ bentonite experiencing the desalinization path of distilled water prior to each infiltration of salt solution. Regarding the relative strain of GMZ bentonite, the difference in osmotic suction between distilled water and salt solution is more relevant than the sodium-calcium replacement.

      PubDate: 2017-03-20T21:52:04Z
      DOI: 10.1016/j.clay.2017.02.016
      Issue No: Vol. 141 (2017)
       
  • Functional clay aerogel composites through hydrophobic modification and
           architecture of layered clays
    • Authors: Omar Abo Madyan; Mizi Fan; Zhaohui Huang
      Pages: 64 - 71
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Omar Abo Madyan, Mizi Fan, Zhaohui Huang
      This paper implements hydrophobic modified clay layers with ammonia salts (Organoclay) using ultra-sonication and water as a solvent to develop functional clay/Poly vinyl alcohol (PVA) aerogel composites through an environmentally friendly freeze drying process. Various compositions have been designed aiming at the high effectiveness of reducing moisture absorption while increasing the structural integrity and overall compressive modulus but reducing the thermal conductivity of the aerogel composites. The results showed significant enhancement to both physical and mechanical properties of the aerogel composites. The microstructure systems of the aerogel composites could be tailored to result in multifunctional performance for the targeted applications. The moisture absorption could be reduced five folds compared to that of normal clay aerogels depending on the exposure relative humidity. While the modulus of the aerogel composites was doubled from an initial modulus of 0.39 to 0.82MPa, the thermal conductivity was reduced by up 20% reaching values as low as 0.0315w/mk. These aerogel composites could be an effective and efficient thermal insulation material to be implemented in the construction industry.
      Graphical abstract image

      PubDate: 2017-02-23T18:22:10Z
      DOI: 10.1016/j.clay.2017.01.013
      Issue No: Vol. 141 (2017)
       
  • Adsorptive removal of 134Cs+, 60Co2+ and 152+154Eu3+ radionuclides from
           aqueous solutions using sepiolite: Single and multi-component systems
    • Authors: Mamdoh R. Mahmoud; Ghada M. Rashad; Essam Metwally; Ebtissam A. Saad; Ahmed M. Elewa
      Pages: 72 - 80
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Mamdoh R. Mahmoud, Ghada M. Rashad, Essam Metwally, Ebtissam A. Saad, Ahmed M. Elewa
      Single and multi-component adsorptive removal of 134Cs+, 60Co2+ and 152+154Eu3+ from aqueous solutions onto sepiolite are studied in the present study. Removal of these radionuclides in single systems is found to be strongly dependent on the initial pH on the solution. Removals >99% (for 60Co2+ and 152+154Eu3+) and of about 82% (for 134Cs+) are achieved at initial pH values higher than 4 and 5, respectively. The kinetic data and the equilibrium isotherms are modeled by two kinetic models, the pseudo-first-order and the pseudo-second-order, and two isotherm models, Langmuir and Freundlich, respectively. The effect of various coexisting cations, Na+, Ca2+ and Al3+, at different concentrations on the adsorption processes of the concerned radionuclides in single systems was evaluated. Desorption studies of radionuclide-loaded sepiolite are studied using different concentrations of organic, EDTA and HA (strong complexing agents for radionuclides), and inorganic, HCl, NaCl, CaCl2, Mg(NO3)2 and AlCl3, desorbing agents. Adsorption mechanisms of radionuclides onto sepiolite are deeply discussed. Multi-component adsorptive removal of 134Cs+, 60Co2+ and 152+154Eu3+ onto sepiolite as a function of adsorbent weight and time was also studied. The influence of the solution pH on co-removal efficiency of radionuclides was investigated in presence of EDTA. Furthermore, the present investigation evaluated the removal efficiency of radionuclides, in multi-systems, in presence of different concentrations either of NaCl or CaCl2.

      PubDate: 2017-02-23T18:22:10Z
      DOI: 10.1016/j.clay.2016.12.021
      Issue No: Vol. 141 (2017)
       
  • Fabrication of kaolin-based cement plug for CO2 storage wells
    • Authors: Naim M. Faqir; Salaheldin Elkatatny; Mohammd Mahmoud; Reyad Shawabkeh
      Pages: 81 - 87
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Naim M. Faqir, Salaheldin Elkatatny, Mohammd Mahmoud, Reyad Shawabkeh
      A new material from clay was developed that has a resistance to carbon dioxide flow in upstream for plugging CO2 storage wells. Thermogravimetric and thermal stability of this material showed a minimal variation in weight loss with incremental heating up to 420°C. Adsorption-desorption of CO2 at various modeled temperature showed an exothermic and spontaneous process with maximum adsorption capacity of 775mg/g obtained at 640psi (43.5bar) and 50°C. Higher pressure led to more storage capacity with physisorption hysteresis curves. Freundlich and BET models best fit the equilibrium adsorption data with average regression coefficient of 0.995. The new material can substitute the conventional cement plugs for upstream carbon sequestration and prevents the migration of the stored CO2 through the cement plug to the surface. Also the developed new cement showed no chemical interaction which confirms the economical impact of using this cement to plug the CO2 sequestrations wells.

      PubDate: 2017-03-03T14:36:19Z
      DOI: 10.1016/j.clay.2017.02.011
      Issue No: Vol. 141 (2017)
       
  • Preparation and characterization of Fe,Co,Si-pillared montmorillonites
           with aminosilanes as silicon pillars precursor
    • Authors: Liang Fang; Li Wang; Tao Zhou; Lihua Liu; Jian Zhou; Menglin Li
      Pages: 88 - 94
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Liang Fang, Li Wang, Tao Zhou, Lihua Liu, Jian Zhou, Menglin Li
      Fe,Co,Si-pillared montmorillonites with micro- and mesopores and high thermal stability were prepared by directly introducing transition metal ions (Fe and Co) and aminosilanes to the interlayer of calcium montmorillonite (Ca-Mt) from Inner Mongolia. The presence of Fe, Co and Si in the interlayer spaces of montmorillonite (Mt) and properties of these pillared Mt were investigated by a combination of X-ray diffraction, elemental analysis, N2 adsorption-desorption, thermal analysis, NH3 temperature-programmed desorption and H2 temperature-programmed reduction capacity tests techniques. The results indicated that the enhanced physicochemical properties of pillared Mt could be attributed to the formation of Fe, Co and Si composite pillars supporting the interlayer space. Particularly, aminosilane played an important role in improving the basal spacing and thermal stability of pillared montmorillonites.
      Graphical abstract image

      PubDate: 2017-03-03T14:36:19Z
      DOI: 10.1016/j.clay.2017.02.006
      Issue No: Vol. 141 (2017)
       
  • Photocatalytic degradation of organic contaminants over clay-TiO2
           nanocomposites: A review
    • Authors: Beata Szczepanik
      Pages: 227 - 239
      Abstract: Publication date: 1 June 2017
      Source:Applied Clay Science, Volume 141
      Author(s): Beata Szczepanik
      Heterogeneous photocatalysis is an efficient, economical and environmentally friendly technology for removing organic contaminants from the aqueous environment. Titania is one of the most popular photocatalyst for decomposing organic compounds due to its strong photocatalytic activity, chemical and biological inertness and high photochemical stability. Extensive literature analysis has shown many possibilities to improve the efficiency of photodecomposition of organic compounds over TiO2. Clay minerals with large surface areas for adsorption and high adsorption capacity used to synthesize nanocomposites with TiO2 (especially anatase) enhance the decomposition of organic pollutants by photocatalytic degradation. Recently, clay minerals have been used more often to prepare hybrid photocatalysts. Dispersing TiO2 nanoparticles onto the surfaces of clay minerals improves the photocatalytic activity of TiO2 by providing more active surface sites and reducing the agglomeration of TiO2 particles. The present review paper offers the following: an overview of the trend in the use of the clay/TiO2 nanocomposite photocatalysts, especially halloysite/TiO2 materials for removal of organic contaminants from water, report on the recent work done and important applications for photocatalytic degradation of organic pollutants.
      Graphical abstract image

      PubDate: 2017-03-08T15:09:02Z
      DOI: 10.1016/j.clay.2017.02.029
      Issue No: Vol. 141 (2017)
       
  • Vermiculite/poly(lactic acid) composites: Effect of nature of vermiculite
           on hydrolytic degradation in alkaline medium
    • Authors: Dolores
      Abstract: Publication date: July 2017
      Source:Applied Clay Science, Volume 143
      Author(s): M. Dolores Fernández, M. Jesús Fernández
      Unmodified and different organomodified vermiculites were used for the preparation of poly(l-lactide) (PLLA) composites via melt mixing. The effect of the clay mineral surface modification, the type of organic modifier of the vermiculite and sample thickness on the degradation of PLLA in alkaline medium at 37°C was studied. The degradation was evaluated by analyzing mass loss, pH, molecular weights, and morphological changes. Alkaline hydrolysis of PLLA was accelerated by the presence of clay mineral and the degradation rate was very much dependent on type of clay mineral and state of dispersion. Morphological changes suggested that the erosion mechanism of polymer matrix occurred at the film surfaces and started at the interface of polymer and clay minerals. The results presented here show that the hydrolytic degradation of PLLA can be controlled through the preparation of nanocomposites introducing the appropriate organomodified nanoclay mineral.
      Graphical abstract image

      PubDate: 2017-03-16T09:26:35Z
       
 
 
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