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  Subjects -> ENGINEERING (Total: 2535 journals)
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ENGINEERING (1330 journals)                  1 2 3 4 5 6 7 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 8)
3D Research     Hybrid Journal   (Followers: 21)
AAPG Bulletin     Hybrid Journal   (Followers: 8)
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Abstract and Applied Analysis     Open Access   (Followers: 3)
Aceh International Journal of Science and Technology     Open Access   (Followers: 7)
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Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
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Applied Clay Science     Hybrid Journal   (Followers: 6)
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Asian Journal of Biotechnology     Open Access   (Followers: 9)
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at - Automatisierungstechnik     Hybrid Journal   (Followers: 1)
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ATZextra worldwide     Hybrid Journal  
AURUM : Mühendislik Sistemleri ve Mimarlık Dergisi = Aurum Journal of Engineering Systems and Architecture     Open Access  
Australasian Physical & Engineering Sciences in Medicine     Hybrid Journal   (Followers: 1)
Australian Journal of Multi-Disciplinary Engineering     Full-text available via subscription   (Followers: 2)
Autocracy : Jurnal Otomasi, Kendali, dan Aplikasi Industri     Open Access  
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Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 8)
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Avances en Ciencias e Ingenierías     Open Access  
Balkan Region Conference on Engineering and Business Education     Open Access   (Followers: 1)
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BER : Survey of Business Conditions in Manufacturing : An Executive Summary     Full-text available via subscription   (Followers: 3)
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Beyond : Undergraduate Research Journal     Open Access  
Bhakti Persada : Jurnal Aplikasi IPTEKS     Open Access  
Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access   (Followers: 1)
Bilge International Journal of Science and Technology Research     Open Access  
Biofuels Engineering     Open Access   (Followers: 1)
Biointerphases     Open Access   (Followers: 1)
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BioNanoMaterials     Open Access   (Followers: 2)
Biotechnology Progress     Hybrid Journal   (Followers: 40)
Bitlis Eren University Journal of Science and Technology     Open Access  
Black Sea Journal of Engineering and Science     Open Access  
Boletin Cientifico Tecnico INIMET     Open Access  
Botswana Journal of Technology     Full-text available via subscription   (Followers: 1)
Boundary Value Problems     Open Access   (Followers: 1)
Brazilian Journal of Science and Technology     Open Access   (Followers: 2)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 12)
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 13)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 14)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers Droit, Sciences & Technologies     Open Access  
Calphad     Hybrid Journal   (Followers: 2)
Canadian Geotechnical Journal     Hybrid Journal   (Followers: 32)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 44)
Carbon Resources Conversion     Open Access   (Followers: 1)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 6)
Case Studies in Thermal Engineering     Open Access   (Followers: 6)
Catalysis Communications     Hybrid Journal   (Followers: 6)
Catalysis Letters     Hybrid Journal   (Followers: 2)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 9)
Catalysis Science and Technology     Hybrid Journal   (Followers: 9)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysis Today     Hybrid Journal   (Followers: 7)
CEAS Space Journal     Hybrid Journal   (Followers: 2)
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 3)
Central European Journal of Engineering     Hybrid Journal  
Chaos : An Interdisciplinary Journal of Nonlinear Science     Hybrid Journal   (Followers: 3)
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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)
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Composite Interfaces     Hybrid Journal   (Followers: 7)
Composite Structures     Hybrid Journal   (Followers: 293)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 236)
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Journal Cover
Applied Clay Science
Journal Prestige (SJR): 0.992
Citation Impact (citeScore): 4
Number of Followers: 6  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0169-1317
Published by Elsevier Homepage  [3161 journals]
  • Effects of properties of minerals adsorbents for the adsorption and
           desorption of volatile organic compounds (VOC)
    • Abstract: Publication date: 1 June 2019Source: Applied Clay Science, Volume 173Author(s): Guangxin Zhang, Mohammad Feizbakhshan, Shuilin Zheng, Zaher Hashisho, Zhiming Sun, Yangyu Liu In this study, adsorption and desorption performance of three mineral adsorbents (diatomite, clinoptilolite, and palygorskite) was investigated for abatement of six VOC with distinct physical and chemical properties and functional groups. Among the three mineral adsorbents, palygorskite exhibited the highest adsorption capacity for all the tested VOC as indicated by the adsorption breakthrough curves. Characterization of the adsorbents showed that palygorskite had the highest specific surface area and pore volume. The distinct adsorption capacities of minerals for VOC can be attributed to the difference of VOC's boiling point and polarity. Increasing the adsorption temperature and relative humidity decreased adsorption capacity of the minerals for VOC. Non-polar VOC showed more sensitivity to changes in temperature and relative humidity compared to polar VOC. Desorption performance of the mineral adsorbents was studied in 5-cycle adsorption/desorption experiments. The results indicated that the desorption purge gas has no significant impact on desorption efficiency. However, increasing desorption temperature clearly decreased the cumulative heel on the adsorbent. Moreover, non-polar VOC desorbed better from the mineral surface than polar VOC.Graphical abstractUnlabelled Image
       
  • Ca–Mg–Al ternary mixed oxides derived from layered double hydroxide
           for selective etherification of glycerol to short-chain polyglycerols
    • Abstract: Publication date: 1 June 2019Source: Applied Clay Science, Volume 173Author(s): Prissana Sangkhum, Jirapong Yanamphorn, Aunchana Wangriya, Chawalit Ngamcharussrivichai In this study, a magnesium (Mg) and aluminum (Al) layered double hydroxide (LDH) was used as a precursor in the preparation of calcium (Ca), Mg and Al ternary mixed oxides for selective conversion of glycerol into diglycerols via solvent-free glycerol etherification. The LDH-derived MgAl mixed oxide was saturated with an aqueous solution of Ca citrate complexes, followed by calcination at 700 °C, to obtain the Ca-MgAl mixed metal oxide (MMO) catalysts. The effects of the citric acid addition and Ca loading levels on the physicochemical and catalytic properties of the resulting Ca-MgAl MMO were investigated. The Ca-MgAl MMO series were characterized by a high Ca dispersion, high total basicity (236–482 μmol g−1), an enhanced amount of strong basic sites and a new mesoporosity. The highest diglycerols selectivity of 78.3 mol% was achieved at a glycerol conversion of 40.4 mol% when the reaction was performed over the Ca-MgAl MMO catalyst synthesized with a 7.5 wt% Ca loading level, at a 3 wt% catalyst loading, 220 °C for 24 h. The formation of ternary mixed oxides improved the structural stability of the pristine MgAl mixed oxide. The catalytic performance of Ca-MgAl MMO was compared with that of commercial MgAl mixed oxides and homogeneous base (Na2CO3). The presence of strong basicity in the MMO catalysts was a key part in the selective synthesis of diglycerols.Graphical abstractUnlabelled Image
       
  • Efficient and selective removal of cationic organic dyes from their
           aqueous solutions by a nanocomposite hydrogel, katira gum-cl-poly(acrylic
           acid-co-N, N-dimethylacrylamide)@bentonite
    • Abstract: Publication date: 1 June 2019Source: Applied Clay Science, Volume 173Author(s): Subinoy Jana, Jagabandhu Ray, Barun Mondal, Tridib Tripathy A pH sensitive nanocomposite (NC) hydrogel based on katira gum-cl-poly(acrylic acid-co-N, N-dimethylacrylamide) incorporated bentonite (BT) nano clay (KG-cl-poly(AA-co-DMA)@BT abbreviated as KGNCH) is prepared by in-situ crosslinked co-polymerization technique using N, N′-methylene-bis-acrylamide (MBA) as crosslinker and potassium peroxodisulphate (KPS) as a free radical initiator. Various nanocomposite hydrogels (KGNCH-1 to KGNCH-4) are prepared by varying weight percentage of bentonite clay. The best one is selected (KGNCH-3) with respect to their highest swelling percentage in aqueous medium. The prepared KGNCH-3 is characterized by the FTIR, FESEM, XRD and EDS analysis and is used for the removal of cationic dyes [Methylene blue (MB), Crystal violet (CV) and Auramine-O (AO)] from their aqueous solutions. The adsorption of cationic dyes onto the KGNCH-3 is found to be pH dependent, the adsorption isotherm and kinetic data are best fitted with the Freundlich isotherm and pseudo second order kinetic model respectively and maximum adsorption capacity (qmax) is found to be at pH = 8.0 for MB, pH = 7.5 for CV and pH = 10 for AO. Calculation of different thermodynamic parameters shows the spontaneous and endothermic nature of the adsorption. The KGNCH-3 also exhibits excellent regeneration capacity at different pH using five cycle of adsorption-desorption studies. From the selectivity study the order of adsorption capacity of the KGNCH-3 is found to be MB > CV > AO.Graphical abstractUnlabelled Image
       
  • Bionanocomposites based on cationic and anionic layered clays as
           controlled release devices of amoxicillin
    • Abstract: Publication date: 1 June 2019Source: Applied Clay Science, Volume 173Author(s): Ediana P. Rebitski, Gabriel P. Souza, Sirlane A.A. Santana, Sibele B.C. Pergher, Ana C.S. Alcântara In the present work bionanocomposite materials based on layered double hydroxide and montmorillonite clay as drug delivery system for oral administration were prepared. With this aim, amoxicillin, an antibiotic commonly indicated for diverse kind of infections, was intercalated into Mt. or LDH interlayer space through cationic exchange and reconstruction reactions, respectively, taking advantage of the possibility to obtain positively or negatively charge in amoxicillin structure, depending on the pH of synthesis. From the diverse physicochemical characterization techniques, i.e. XRD, FTIR, TG-DTA and SEM was possible to infer that amoxicillin molecules are disposed as monolayer, covering the interlayer surface of both solids, neutralizing the charge of the lamellae, and consequently, conferring an improve in the thermal stability of the drug. In order to improve the performance of these intercalation compounds in acid media, e.g. stomach fluid (pH 1.2), these clay-amoxicillin hybrids were incorporated in a biopolymer matrix composed by carboxymethylcellulose polysaccharide and zein protein, giving rise bionanocomposite beads. These bionanocomposite materials, which were evaluated as a function of the type of intercalation compound and the amount of zein protein, showed good compatibility between their components, offering a more controlled release of amoxicillin compared to the respective hybrid or pure biopolymers blend, allowing that the active specie reaches the intestinal tract, improving the bioavailability of the drug.Graphical abstractUnlabelled Image
       
  • Stabilization of a soft marine clay using halloysite nanotubes: A
           multi-scale approach
    • Abstract: Publication date: 1 June 2019Source: Applied Clay Science, Volume 173Author(s): Endene Emmanuel, Chun Chern Lau, Vivi Anggraini, Pooria Pasbakhsh Halloysite nanotubes are novel 1D natural nanomaterials which are widely used in reinforcing polymer, adsorbents for pollution remediation, and nanoreactors for biocatalyst; owing to their high mechanical strength, thermal stability, high aspect ratio, nature-friendly, cost-effectiveness, and abundance. However, the use of halloysite nanotubes as a stabilizing agent for soft soils is currently not clear. This paper explores the possibility of stabilizing a soft marine clay by adding halloysite nanotubes. Laboratory investigations were conducted on marine clay treated with three different types of halloysite nanotubes [Matauri Bay (MB-Hal), UltraHallopure (UHP-Hal), and Dragonite (DG-Hal)] and combined under 5% by dry clay mass. Test results revealed notable improvements in the properties of the marine clay. The addition of halloysite nanotubes resulted in an increase in the clay and silt-sized contents and a decrease in the sand-sized content. The plasticity and hydraulic conductivity of the clay decreased upon treatment with the halloysite nanotubes. Moreover, the unconfined compressive strength (UCS) of the treated-clay recorded ascending values with increasing curing time. The percentage increase of the UCS for the 14-days cured DG-Hal, MB-Hal, and UHP-Hal treated-clay samples over the untreated-clay were 67%, 62%, and 51%, respectively. Microstructural study reveals that the stabilization process modified the porous network of the clay. The pores of the clay were filled by the halloysite nanoparticles. DG-Hal treated sample recorded the highest strength and lowest hydraulic conductivity for all curing durations relative to MB-Hal and UHP-Hal treated clay samples. Obtained changes in the plasticity, strength, and hydraulic conductivity of the treated samples indicates that halloysite nanotubes can be used as an effective stabilizing agent for soft soils. However, it is recommended to investigate the effect of different percentages of halloysite nanotubes to stabilize soft soils.
       
  • Calcium chloride addition to overcome the barriers for synthesizing new
           Ca-Ti layered double hydroxide by mechanochemistry
    • Abstract: Publication date: 1 June 2019Source: Applied Clay Science, Volume 173Author(s): Jun Qu, Lin Sha, Zhigao Xu, Zhengyan He, Ming Wu, Chenjie Wu, Qiwu Zhang In this study, a new binary Ca-Ti layered double hydroxide (LDH) has been synthesized for the first time by a two-step (dry and wet) milling of calcium hydroxide, hydrated titanium dioxide and a third phase of calcium chloride. No reactions were observed while milling calcium hydroxide and hydrated titanium dioxide unless the further addition of a third phase of calcium chloride which triggered the solid state reaction to form LDH phase. The traditional co-precipitation process failed to synthesize Ca-Ti LDH due to the barriers of the precipitation pH and ion radius differences between Ca2+ and Ti4+. The X-ray diffraction (XRD), Thermogravimetric Analysis (TGA), X-ray photoelectron spectroscopy(XPS) and Scanning electron microscopy (SEM) techniques were applied to characterize the prepared samples. The characterization results demonstrated the successful production of high crystalline Ca-Ti LDH phase. This work proved the feasibility of mechanochemistry to produce novel binary LDH which may be of help for the synthesis of other new layered materials in general.
       
  • Complex of chitosan pectin and clay as diclofenac carrier
    • Abstract: Publication date: May 2019Source: Applied Clay Science, Volume 172Author(s): Dorsaf Cheikh, Fátima García-Villén, Hatem Majdoub, Memia Benna Zayani, César Viseras The preparation of a new drug delivery system (DDS) based on the combination of two natural polymers chitosan (CS) and high-esterified pectin (HEP) and beidellite (Bd) was proposed. Diclofenac sodium was chosen as model drug and was loaded in the nanocomposite by means of intercalation solution technique. The samples were characterized by X-ray diffraction, Thermal analysis, Infrared spectroscopy and high resolution transmission electron microscopy coupled with energy dispersive X-Ray analysis. Drug loading capacity and encapsulation efficiency of the clay polymer nanocomposite was quantified. UV–Vis spectroscopy (276 nm) was used as the drug quantification technique throughout the whole study. In vitro drug release profile in simulated intestinal fluid was also evaluated. Results demonstrated the formation of diclofenac polymorph during the drug loading process, thus obtaining a new crystal form of the drug possessing different physico-chemical properties with respect to the diclofenac sodium salt form. Moreover, the in vitro release study showed that the bionanocomposite elaborated could form a network aiming for a modified release of diclofenac. Consequently, Na-Bd/CS/HEP nanocomposite proved to be a promising formulation to control anionic drug release process.
       
  • Comparison of the removal behavior of fluoride by Fe3+ modified
           geomaterials from water
    • Abstract: Publication date: 1 June 2019Source: Applied Clay Science, Volume 173Author(s): N.G. Corral-Capulin, A.R. Vilchis-Nestor, E. Gutiérrez-Segura, M. Solache-Ríos In the present work geomaterials (Fe3+ modified clinoptilolite (C—Fe), Fe3+ modified clinoptilolite heated at 200 °C (C—Fe 200), montmorillonite (M) and Fe3+ modified montmorillonite heated at 200 °C (M-Fe 200)) were studied to evaluate their efficiency on the removal of fluoride from water. Clinoptilolite (C) and montmorillonite (M) were treated with Fe3+ under reflux conditions and heated at 200 °C in order to improve their adsorption properties. They were characterized before and after fluoride adsorption by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR). Adsorption experiments were carried out in batch systems considering the effect of contact time, initial concentration of fluoride and initial pH. Experimental data were well adjusted to pseudo-second order kinetic model that assumes chemical interaction between adsorbent and adsorbate. Fluoride adsorption on C—Fe and M-Fe 200 were well described by a linear isotherm equation where the adsorption capacity increases as the initial fluoride concentration increases. The adsorption of fluoride by C—Fe 200 was described by Freundlich model that suggests a multilayer adsorption and the isotherm of M was well fitted to Sips model indicating a heterogeneous surface of the material. The adsorption capacities of the materials followed the order: M > C-Fe > C-Fe 200 ≈ M-Fe 200. Finally, the possible mechanism of fluoride adsorption was also discussed.
       
  • Crystal violet adsorption by oppositely twisted heat-treated halloysite
           and pecoraite nanoscrolls
    • Abstract: Publication date: 1 June 2019Source: Applied Clay Science, Volume 173Author(s): Andrei A. Krasilin, Dmitry P. Danilovich, Elena B. Yudina, Stéphanie Bruyere, Jaafar Ghanbaja, Vladimir K. Ivanov Present study focuses on crystal violet adsorption by mineral halloysite and synthetic pecoraite nanoscrolls. Being scrolled in opposite directions, these two materials serve both as good adsorbents and model objects to understand the dye adsorption mechanism. Heat treatment of the nanoscrolls allowed us to track the adsorption process features by changing the structure and surface state of the particles. Structural transitions were observed by complementary techniques including X-ray diffraction, thermal analysis, electron microscopy, N2 adsorption and ς-potential measurements. By a fast UV/VIS study of adsorption kinetics, it became possible to take a closer look at the very initial steps of the process. Intraparticle diffusion governs the overall adsorption kinetics of the dye by halloysite and pecoraite nanoscrolls. The presence of OH-groups on the nanoscrolls' surface strongly facilitates the initial stage of adsorption. Structural transition at around 600 °C increases adsorption rate and performance of synthetic pecoraite due to ς-potential sign change.Graphical abstractUnlabelled Image
       
  • Insight into the effect of crystallographic structure on thermal
           conductivity of kaolinite nanoclay
    • Abstract: Publication date: 1 June 2019Source: Applied Clay Science, Volume 173Author(s): Jianwen Li, Xiaochao Zuo, Xiaoguang Zhao, Jing Ouyang, Huaming Yang Thermal conductivity plays an important role in thermal performances of latent heat thermal energy storage (LHTES) systems with phase change materials (PCMs). With respect to the significance of kaolinite nanoclay in PCMs manufacture, previous works have paid much attention to the effect of physicochemical properties such as morphology of kaolinite on thermal conductivity. However, the relationship between the evolution of crystallographic structure and thermal conductivity has not been researched. In this work, this correlation was systematically elucidated through experimental investigation and theoretical analysis using thermogravimetry and differential scanning calorimetry (TG/DSC), X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). The results indicated that poorly ordered kaolinite possessed a low thermal conductivity, and particularly crystallinity index and conductivity showed a clear regression relationship. Further investigation determined that lower conductivity was attributed to the ill-structured geometrical configuration of silicon- and aluminum-oxygen units, which resulted in an increasing number of phonon-defect scattering events, and thus limited the mean free path of phonons in kaolinite lattices. This was contributed to the low thermal conductivity based on the characteristic property of phonon heat conduction.Graphical Unlabelled Image
       
  • Extraction of alumina from kaolin by a combination of pyro- and
           hydro-metallurgical processes
    • Abstract: Publication date: May 2019Source: Applied Clay Science, Volume 172Author(s): A.B. ElDeeb, V.N. Brichkin, R.V. Kurtenkov, I.S. Bormotov The increasing of aluminum demand globally raises the interest in developing alternative technologies to produce alumina from non-bauxitic sources, especially clays. This paper studies the extraction of alumina from the kaolin ore excavated from the Irkutsk region, Russia through the leaching process, using aqueous solutions of sodium carbonate as a leaching agent. Before the leaching process, the kaolin ore and limestone charge was sintered. The sintering process achieves the dehydroxylation of the kaolinite, which is the main mineralogical phase in the kaolin and activates its transformation to metakaolin. Metakaolin is an amorphous AlSi phase, from which alumina could be easily leached. The annealed sintered material transform into dust that is suitable for the leaching process without any additional grinding. The sintering process was taken place in the temperature range 800-1400 °C for 1 h. The effect of briquetting pressure and sintering temperature on the recovery of alumina from kaolin, were studied. About 87% of the alumina in the kaolin was extracted at 1360 °C and briquetting pressure of 5 MPa.
       
  • A comparative study of some kaolinites surface properties
    • Abstract: Publication date: May 2019Source: Applied Clay Science, Volume 172Author(s): J.A. Mbey, F. Thomas, A. Razafitianamaharavo, C. Caillet, F. Villiéras The surface properties of five kaolinites of various origins were analyzed using potentiometric titration, electrokinetic measurements and low-pressure gas adsorption associated to derivative isotherm summation (DIS) modeling. The data show that sample structure is important in determining the surface properties. The combined analytical results clearly shows the existence of a permanent negative layer charge for all the samples. The general features that could be observed for the five kaolinites are: the titration curves are shifted to lower pH with increasing ionic strength due to the layer charge; the amount of consumed proton is influenced by the permanent layer charge; although low, the permanent charge determines the electrokinetic behavior. The shape anisotropy and the charge distribution on the basal and edge surfaces are crucial parameters to understand the behavior of kaolinite particles in aqueous media. The Cameroonian sample of the set exhibits a significant permanent charge together with large specific surface area associated to fine particle size and considerable shape anisotropy.Graphical abstractUnlabelled Image
       
  • On the key role of the surface of palygorskite nanofibers in the
           stabilization of hexagonal metastable β-Ag2CO3 phase in
           palygorskite-based nanocomposites
    • Abstract: Publication date: May 2019Source: Applied Clay Science, Volume 172Author(s): O. Lakbita, B. Rhouta, F. Maury, F. Senocq, M. Amjoud, L. Daoudi This study reports an original remarkable effect of fibrous palygorskite clay mineral in the stabilization at the ambient temperature of the metastable hexagonal β-phase of Ag2CO3 along with the stable monoclinic one (m-Ag2CO3) and the refinement of their particles size (≈5–10 nm). These structural and microstructural features likely arise owing to heterogeneous nucleation induced by the surface of palygorskite fibers between CO32– anions in solution and Ag+ exchanged palygorskite (Ag+-Pal) as reactants kept maturing for short periods, which should not exceed 1 h. Besides, the phase composition of Ag2CO3 supported on palygorskite, namely β- and m-structures can be monitored by carrying on appropriate low temperature treatments under CO2 atmosphere coupled with aging during several months in such a way that either pure β or m single-phases as well as biphased mixtures with controlled composition can be obtained. Taking into account experimental results and literature data, a growth mechanism is discussed.Graphical abstractUnlabelled Image
       
  • Assembling kaolinite nanotube at water/oil interface for enhancing
           Pickering emulsion stability
    • Abstract: Publication date: May 2019Source: Applied Clay Science, Volume 172Author(s): Xiaolong Cai, Cunjun Li, Qi Tang, Bowen Zhen, Xiangli Xie, Wenfeng Zhu, Chunhui Zhou, Linjiang Wang Emulsion has a wide range of applications. Good Pickering emulsifiers have always been sought to use for high stable emulsion. In this work, nanometer-sized kaolinite nanotube was prepared and used as emulsifier to stabilize Pickering emulsion. The emulsion stability was investigated by measuring the emulsion volume, emulsion viscosity, optical microanalysis of the emulsion droplets, and Cryoelectron microscopy of the distributed structure of emulsifier at the water/oil interface. The results showed that the emulsion droplet diameter was 60 μm, and the emulsion viscosity reached up to 3470 mPa·S. The creaming index was 76% and even up to 36% after centrifugation at 2000 rpm. The enhanced emulsion stability was ascribed to assembly and alignment of the kaolinite nanotube at the water/oil interface, forming a denser single-layer particle film to prevent the coalescence of emulsion droplets.Graphical abstractUnlabelled Image
       
  • Mg and silica release in short-term dissolution tests in bentonites
    • Abstract: Publication date: May 2019Source: Applied Clay Science, Volume 172Author(s): S. Kaufhold, R. Dohrmann, A. Degtjarev, P. Koeniger, V. Post The investigation of the release of elements/structural cations from bentonites is important for high-level radioactive waste research. Smectites, the main component of bentonites, cannot be described by thermodynamics. In the present paper, therefore, element release from 38 well characterized bentonites is investigated rather than the solubility of smectites in a thermodynamic sense. The solid/liquid ratio was 0.2 mass%, temperature and time were varied. The study focused on Mg- and Si-release because Al- and Fe-concentrations measured in solution were not reproducible probably because of polymerization, recrystallization, and/or readsorption. Bentonites contain minor amounts of minerals other than smectites which could explain differences of the concentrations of released elements. Low crystalline silica phases, however, were the only admixtures significantly affecting the results. The focus, therefore, was on samples with a low amount of low crystalline silica phases. In the temperature range between 100 and 140 °C Mg and Si dissolved stoichiometrically (corresponding to the typical range of Si/Mg in dioctahedral smectites). Below 100 °C more Mg compared to Si was dissolved and the opposite was observed above 140 °C. Extrapolating these results to higher solid/liquid rations would indicate i) that the formation of Mg/Si-phases at the heater of HLRW canisters could be explained by partial smectite dissolution and ii) that different Mg/Si-phases could form depending on temperature. The element release tests used in the present study proved to be suitable to distinguish “reactive” (released more Mg and Si) from “less reactive” bentonites.Graphical abstractUnlabelled Image
       
  • Synergistic effect of Cloisite 15A and 30B nanofillers on the
           characteristics of nanocomposite polyethersulfone membrane
    • Abstract: Publication date: May 2019Source: Applied Clay Science, Volume 172Author(s): Parisa Daraei, Negin Ghaemi Considering the environmental risks of oily wastewater and the impressive role of membrane technology in refining these wastes, preparation of a highly durable well performed polymeric membrane with improved antifouling properties was taken into account in this study. For this purpose, two different clay-based nanofillers i.e., Cloisite 15A and 30B organoclays were examined as nanofiller in polyethersulfone membrane matrix. The synergistic effect of hybrid nanofiller addition on the membrane efficacy was probed using oily water filtration, morphological and mechanical characterization tests as well as the fouling investigations. It was found that embedding equal amounts of Cloisite 15A and 30B resulted in the most preferred membrane among all the prepared samples with different ratios of two nano-additives. Hybrid nanofiller resulted in higher oil rejection (99.1%), acceptable water permeability, high flux recovery (95%) after getting fouled with oil as well as higher mechanical resistance compared with bare PES and also single filler nanocomposite membranes.Graphical abstractUnlabelled Image
       
  • Effects of nano-activated carbon on water and gas permeability and
           hydrogen sulphide removal in compacted kaolin
    • Abstract: Publication date: May 2019Source: Applied Clay Science, Volume 172Author(s): H.W. Liu, S. Feng, A.K. Leung Many soil amendments have been proposed to exclusively enhance the removal of hydrogen sulphide (H2S; one of the major odorous gas) and reduce water percolation/landfill gas emission in a municipal solid waste landfill. There is no reported data about any single amendment that can simultaneously reduce (i) gas permeability (kg) and saturated water permeability (kw) and (ii) H2S emission. The present study investigated the possible use of nano-activated carbon to amend the physico-chemical properties of kaolin, including kw, kg and H2S adsorption capacity. It was revealed that adding nano-activated carbon of 6% (by mass) could reduce kw and kg by about 60% and more than an order of magnitude, respectively, while increasing the H2S adsorption capacity by more than four times.
       
  • Plasma modification of NiAlCe–LDH as improved photocatalyst for organic
           dye wastewater degradation
    • Abstract: Publication date: May 2019Source: Applied Clay Science, Volume 172Author(s): Xumei Tao, Yuanyuan Han, Chao Sun, Liang Huang, Dongyan Xu NiAlCe–LDH were prepared by co-precipitation method and modified with DBD plasma to improve the photocatalytic performance. NiAlCe–LDH were analyzed by XRD, EDS, XPS and UV–Vis characterizations, and evaluated by methyl orange degradation under ultraviolet light irradiation. NiAlCe–LDH photocatalysts exhibited good photocatalytic activities. NiAlCe–LDH with Al3+/Ce3+ molar ratio of 0.035/0.015 showed nearly 100% MO degradation within 48 min when the MO concentration was 80 mg/L and the catalyst addition amount was 1 g/L. NiAlCe–LDH modified with DBD plasma at 70 V for 20 min exhibited improved photocatalytic activity, nearly 100% MO degradation within 36 min. LDH modified by DBD plasma with improved photocatalytic performance had broadened new horizons for photocatalytic field.
       
  • Physicochemical approach to evaluating the swelling pressure of expansive
           soils
    • Abstract: Publication date: May 2019Source: Applied Clay Science, Volume 172Author(s): Tiantian Ma, Chuanqin Yao, Yi Dong, Panpan Yi, Changfu Wei Swelling pressure is an important parameter for understanding the expansive nature of the bentonites and natural clayey soils. During the wetting process, the intergranular stresses evolve due to the capillarity and adsorption of clay minerals, and swelling pressure is developed if soil deformation is constrained by the boundary conditions. Strong physicochemical interactions between clay particles and water molecules prevail in the development of intergranular stresses in expansive soils. In this paper, an empirical approach considering Donnan's osmotic effect was proposed to calculate the change in swelling pressure of expansive soils infiltrated by salt solutions with different concentrations. In the model, the intergranular stress addresses the physicochemical interactions between the minerals of clay and saturating fluids with ion concentration gradients induced by fixed negative surface charges. The differential volumetric strain assuming nonlinear elasticity identifies two mechanisms for the variation of the swelling pressure with the concentration of salt solution. The Donnan osmotic pressure decreases as the concentration increases, and the bulk modulus decreases as the concentration increases. The experimental results show that the variation of the Donnan osmotic pressure dominants the evolution of the swelling pressure with the salt solution concentration for a given soil. The comparison between the simulations and the available experimental data in the literature illustrates well the prediction of the swelling pressure of expansive soils by using the proposed model.
       
  • Moroccan clay deposits: Physico-chemical properties in view of provenance
           studies on ancient ceramics
    • Abstract: Publication date: May 2019Source: Applied Clay Science, Volume 172Author(s): Meriam El Ouahabi, Hicham El Boudour El Idrissi, Lahcen Daoudi, Mouhssin El Halim, Nathalie Fagel Features of clayey raw materials from most important traditional pottery centers in the vicinity of the main medieval sites in Morocco, and their fired products were investigated. Besides clay from the North of Morocco, the used raw material was illitic clays (10–100%) and smectite-rich clays (0–67%) with variable amount of kaolinite, quartz and feldspars. Chlorite was also present in a small amount. The main major oxides were Si2O, Al2O3 and CaO. The fired tests (800–1100 °C) displayed a decrease in open porosity of the sintered clay by raising the temperature, mainly from 1000 °C due to the inception of melting. This change was coupled with the change in mineralogical composition. New crystalline phases as Ca-silicates (diopside and gehlenite), hematite, spinel and mullite occurred during firing process, attesting to the inception of melting and were responsible for porosity reduction.Reference clays for pottery were established based on the clay mineralogy and chemical composition. The present study would help to answer some archeological questions concerning possible sourcing areas for archeological ceramics, to determine techniques for the production of artefacts, and then to interpret cultural influences. Furthermore, the obtained results will support the inception of development of a compositional database for Moroccan pottery.
       
  • Adsorption of chromium (VI) on hydrotalcite-hydroxyapatite material doped
           with carbon nanotubes: Equilibrium, kinetic and thermodynamic study
    • Abstract: Publication date: May 2019Source: Applied Clay Science, Volume 172Author(s): E. Rodrigues, O. Almeida, H. Brasil, D. Moraes, M.A.L. dos Reis Hexavalent chromium adsorption in aqueous solution was studied in a fixed bed column with a hydrotalcite-hydroxyapatite (HT-HAp) material doped with carbon nanotubes (CNT) at 333.15 K. Equilibrium, kinetic and thermodynamic behaviors were the focus of this work. The CNT doping was performed in two different proportions (5 and 15%wt.). Isotherm (Langmuir, Freundlich, Temkin, Redlich-Peterson, Sips, and Toth) and kinetics (Thomas, Yoon-Nelson, and Adams–Bohart) models were tested. HT-HAp/CNT15 sample presented the best Cr(VI) bated proportion (76.97%R). The adsorption behavior was fit by the Freundlich model, following a pseudo-second order kinetic mechanism confirmed by Thomas model. Thermodynamic parameters indicated a physisorption process.Graphical abstractUnlabelled Image
       
  • Bentonites with grafted aminogroups: Synthesis, protolytic properties and
           assessing Cu(II), Cd(II) and Pb(II) adsorption capacity
    • Abstract: Publication date: May 2019Source: Applied Clay Science, Volume 172Author(s): L.S. Kostenko, I.I. Tomashchuk, T.V. Kovalchuk, O.A. Zaporozhets Bentonites with grafted methylaminopropyl (NHCH3-Bent), aminopropyl (NH2-Bent), ethylenediaminopropyl (En-Bent) and diethylenetriaminopropyl (Dien-Bent) groups were synthesized by silylation procedure. The successful covalent grafting of silylating agents on the bentonite was confirmed by 29Si NMR, FTIR and thermal analysis. The effects of polar (ethanol) and non-polar (dioxane) solvents on grafting process were compared. The samples prepared in ethanol showed the increase of d001 value from initial 1.44 nm to 1.63–2.05 nm proportionally to the loading amount of grafted silane. However, an almost constant value of d001 (1.96–2.10 nm) was observed for all samples obtained in dioxane, which may be related to more efficient intercalation of the nonpolar solvent. High concentration of grafted aminogroups (0.7–1.6 mmol g−1) resulted in almost four times increase of adsorption capacity of Cu(II), Pb(II) and Cd (II) ions (1.35–0.91 mmol g−1) compared to the initial bentonite (0.23–0.25 mmol g−1). The modification with aminosilanes shifted the affinity sequence of the initial bentonite Pb(II) > Cd(II) > Cu(II) to Cu(II) > Pb(II) > Cd(II).Graphical abstractUnlabelled Image
       
  • l-alanine-chlorite+system&rft.title=Applied+Clay+Science&rft.issn=0169-1317&rft.date=&rft.volume=">Amino acids-clay interaction at the nano-atomic scale: The
           l-alanine-chlorite system
    • Abstract: Publication date: May 2019Source: Applied Clay Science, Volume 172Author(s): D. Moro, G. Ulian, G. Valdrè For technological purposes there is an urge towards the fundamental knowledge of biomolecules-clay interaction at a single molecular level. To this aim, in this work we investigated in detail the specific interaction between the basic amino acid l-alanine and the (001) clinochlore surface. The adsorption process of alanine was investigated by cross-correlated atomic force microscopy (AFM) and quantum mechanics simulations (QM) at the DFT/B3LYP level of theory. As similarly deduced for glycine, clinochlore surface was able to condense, organize, and agglomerate alanine molecules onto specific regions, the brucite-like ones. The amino acid was stably adsorbed onto the brucite-like surface of clinochlore, organized in dot-like structures, agglomerates and filament-like structures up to about 150 nm long. Single molecules of alanine were discriminated by AFM, with sizes in agreement with QM calculations (mean height of about 5 ± 0.5 Å and a mean width of about 11 ± 1 nm). Simulations provided also the lowest energy conformation of the molecule on the surface, the intermolecular bonding scheme and the amino acid/surface interaction energy, which could be as high as −250 kJ/mol. To further extend the knowledge of the specificity of the brucite-like sheet to interact with biomolecules, dedicated quantum mechanical investigations were also conducted to quantify the Brønsted−Lowry basic strength related to Al3+/Mg2+ substitutions in the brucite-like sheet, typically occurring in this kind of clay mineral, simulating the interaction with probe molecules with increasing acidic strength (H2O, H2CO3, HNO3 and HCl). The reported findings could be useful not only for biotechnological and environmental purposes, but also for prebiotic chemistry research, because clinochlore is one of the 420 mineral species likely to have been present in Earth's near-surface environment at the time of life's origins (Hazen, 2013).Graphical abstractUnlabelled Image
       
  • Bio-inspired fabrication of fire-retarding, magnetic-responsive,
           superhydrophobic sponges for oil and organics collection
    • Abstract: Publication date: May 2019Source: Applied Clay Science, Volume 172Author(s): Pengfei Liu, Yuping Zhang, Shanqin Liu, Yijun Zhang, Zuliang Du, Lingbo Qu In this study, durable superhydrophobic sponge with magnetic-responsive and fire-retarding was prepared. In the preparation process, polydopamine (PDA), layered double hydroxide (LDH), Fe3O4 nanoparticles and n-Octadecyl mercaptan (OM) acted as the “bio-glue”, fire retardant, magnetic materials and hydrophobic reagent, respectively. LDH and Fe3O4 nanoparticles were adhered on the skeleton surface of PU sponge via PDA to build micro/nano structure, and then the -NH2 of PDA could react with the -SH of OM (Michael addition reaction), which made the sponge repellent to water. The prepared sponge exhibited remarkable hydrophobicity (water contact angle = 163°)and highly oleophilic (oil contact angle = 0°). When used for absorbing oil and organics, the prepared sponge floated on the surface of oily wastewater, and it could be moved towards oil droplet under magnetic actuation. The as-prepared sponge could absorb various kinds of oils and organics up to 53.6 times of its own weight, and the absorbed oils could be collected through a simple squeezing process. The prepared sponge could be withstood at least 50 cycles of laundering without losing its magnetic properties and superhydrophobicity due to the viscidity of PDA and strong interaction between PDA and OM. In addition, it was difficult to ignite the prepared sponge in air after anchored LDH and Fe3O4 on the sponge skeleton surface. This might offer an environmentally friendly way to prepare “smart and safe” oil-recovery materials.Graphical abstractUnlabelled Image
       
  • Synergistically using layered and fibrous organoclays to enhance the
           rheological properties of oil-based drilling fluids
    • Abstract: Publication date: May 2019Source: Applied Clay Science, Volume 172Author(s): Guanzheng Zhuang, Jiahua Gao, Shanmao Peng, Zepeng Zhang Layered organo-montmorillonite (OMt) is widely used as the rheological additives in oil-based drilling fluids. Recently, fibrous organoclays, such as organo-palygorskite, had been reported as the rheological agent in oil-based drilling fluids. These organoclays showed different rheological properties and mechanisms. In this work, the joint use of OMt and OPal in oil-based drilling fluids was investigated. The optimized organoclays were prepared according to the previous reports and characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermal analysis. The rheological properties of mixed organoclays at different mass ratios were tested in comparison with the single organoclay. Viscous flow behavior, viscosity and thixotropy were summarized. The synergetic use of OMt and OPal could improve the rheological properties of oil-based drilling fluids, even aged at 200 °C. The optimal mass ratio of OMt to OPal was 1:1. The rheological mechanism of mixed OMt and OPal in oil was concluded based on the X-ray diffraction results of organoclay/oil gels. The presence of fibrous OPal enhanced the network structure of layered OMt and prevented the network structure from collapse by interlacing among the nanolayers.Graphical abstractUnlabelled Image
       
  • Pros and cons of coating layered double hydroxide nanoparticles with
           polyacrylate
    • Abstract: Publication date: May 2019Source: Applied Clay Science, Volume 172Author(s): Cecilia Vasti, Carla E. Giacomelli, Ricardo Rojas Preventing the aggregation of layered double hydroxide nanoparticles (LDH-NP) and producing additional functionality are two important objectives for their applications as drug nanocarriers, among others. Adsorption of polyelectrolytes like polyacrylate (PA) is a promising approach to produce protective, functional coatings, but the effect of factors such as chain length, as well as the pros and cons of this strategy, have not been described. In this work, these aspects were studied using LDH-NP intercalated with chloride and benzoate as interlayer probes. The interaction between LDH-NP and PA, as well as the effect in the aggregation of the former, was studied as a function of the molecular weight (MW = 1.2, 8.0 and 450 kDa) and the PA concentration. High MW were more effective for preventing LDH-NP aggregation as well as for minimizing the PA intercalation between the layers. Thus, the 8.0 kDa PA allowed obtaining benzoate intercalated LDH-NP with a particle size around 200 nm that maintained 40% of the exchange sites occupied by benzoate anions. PA coating not only hindered aggregation and changed the particle charge, but also provided new functionality, such as a protective layer towards proton diffusion and, consequently, dissolution of LDH-NP. PA coating is then an effective tool for LDH-NP stabilization and customization, if interlayer anion loss is controlled.Graphical abstractUnlabelled Image
       
  • The influence of acid modification on the structure of montmorillonites
           and surface properties of bentonites
    • Abstract: Publication date: May 2019Source: Applied Clay Science, Volume 172Author(s): V. Krupskaya, L. Novikova, E. Tyupina, P. Belousov, O. Dorzhieva, S. Zakusin, K. Kim, F. Roessner, E. Badetti, A. Brunelli, L. Belchinskaya Bentonites are often used as components of engineered barrier systems (EBS) for the radioactive waste disposal and isolation of hazardous nuclear facilities. In this paper, we consider possible transformations of the composition, structure and properties of bentonites when they are used as EBS components during the decommissioning of open pools with liquid radioactive waste (LRW). Operating conditions were modeled by the treatment with nitric acid at different durations (from 1 to 6 h), concentrations (from 1 to 8 M) and temperatures (20and 90°C). Nitric acid was chosen because it is used in the preparation procedure of LRW for isolation. To assess the intensity of transformations, bentonites with a high content of Al- and Fe-rich montmorillonites were selected. The work revealed effects of interlayer modification, leaching of octahedral cations, changes of the grain size distribution, specific surface area and weakening of surface basicity. It was also shown that temperature has a stronger effect on the structural transformation of montmorillonite than acid concentration and treatment duration. Formation of Al hydroxy-interlayered (HI) layers was observed due to the treatment with the nitric acid of lower concentration (1 M). The effect of a higher concentration at the same treatment duration and temperature leads to a more intensive leaching of Al from the octahedral sheets and protonation of the interlayer, which prevents the formation of Al hydroxy-interlayered (HI) layers. CO2 desorption after the nitric acid treatment decreases significantly, maintaining a relatively high value only when the conditions allow the interlayer to be protonated. Modification of structural and adsorption characteristics due to the acid treatment can be used to simulate modification of the engineered barriers' properties for a long-term operation in the disposal of radioactive and toxic wastes.
       
  • Kinetic re-evaluation on “Comparative adsorption of Pb(II), Cu(II) and
           Cd(II) on chitosan saturated montmorillonite: Kinetic, thermodynamic and
           equilibrium studies”
    • Abstract: Publication date: Available online 7 May 2018Source: Applied Clay ScienceAuthor(s): Yong-Son Hong
       
 
 
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