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PHYSICS (536 journals)            First | 1 2 3 4 5 6 | Last

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Macalester Journal of Physics and Astronomy     Open Access  
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Microporous and Mesoporous Materials     Hybrid Journal   (Followers: 3)
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Physica B: Condensed Matter     Hybrid Journal   (Followers: 4)
physica status solidi (a)     Hybrid Journal   (Followers: 1)

  First | 1 2 3 4 5 6 | Last

Journal Cover Microporous and Mesoporous Materials
   [5 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 1387-1811
     Published by Elsevier Homepage  [2563 journals]   [SJR: 1.306]   [H-I: 93]
  • Rapid aqueous synthesis of ordered mesoporous carbons: Investigation of
           synthesis variables and application as anode materials for Li-ion
           batteries
    • Abstract: Publication date: 1 September 2014
      Source:Microporous and Mesoporous Materials, Volume 195
      Author(s): Alexandre F. Léonard , Cedric J. Gommes , Marie-Laure Piedboeuf , Jean-Paul Pirard , Nathalie Job
      Ordered mesoporous carbons (OMC) were synthesized via a direct templating pathway by a synthesis route that features short duration, moderate temperature and aqueous media. Resorcinol was used as carbon precursor and hexamethylenetetramine as a source of formaldehyde and ammonia to respectively cross-link the framework and regulate the pH. The temperature of the heat treatment leading to the formation of the solid polymer was shown to have a strong influence on the structural and textural parameters. In particular, moderate temperatures led to the coexistence of differently-sized entangled hexagonal mesostructures, whereas the higher temperatures led to a sharp decrease in the mesopore volume. The performance of these materials as anode materials for Li-ion batteries has been investigated in detail. Although these OMC show reversible capacities similar to those reported for hard carbons, their long-term cycling remains very stable for over 100 cycles of charge/discharge. The optimization of the reported short preparation pathway offers new possibilities regarding the application of ordered mesoporous carbons in various fields, such as energy storage, sorption and heterogeneous catalysis.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • Synthesis of low-silica CHA zeolite chabazite in fluoride media without
           organic structural directing agents and zeolites
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Bo Liu , Yihong Zheng , Na Hu , Tian Gui , Yuqin Li , Fei Zhang , Rongfei Zhou , Xiangshu Chen , Hidetoshi Kita
      The fluoride route was adopted for the preparation of chabazite (Si/Al=2.5–3.5) in the absence of organic structural directing agents (OSDAs). The crystallization kinetics of the fluoride-derived chabazite and the effects of gel SiO2/Al2O3 ratio, gel F−/SiO2 ratio, fluoride source and synthesis temperature on the morphology and composition of crystals were investigated. A certain amount of the specific fluoride source (NH4F) dominated the crystallization of CHA phase in the competitive growth of MER/CHA phases. The fluoride-derived chabazite by in situ synthesis had a particle size of 15–20μm. Seeded-in-gel synthesis increased the crystallization rate and resulted in the smaller crystals with higher BET surface area and microspore volume. The location of fluoride ion in zeolite framework and the role of fluoride salts on chabazite crystallization were also demonstrated.
      Graphical abstract image

      PubDate: 2014-06-14T14:57:01Z
       
  • Facile synthesis of POM@MOF embedded in SBA-15 as a steady catalyst for
           the hydroxylation of benzene
    • Abstract: Publication date: 1 September 2014
      Source:Microporous and Mesoporous Materials, Volume 195
      Author(s): Hua Yang , Jun Li , Hengyun Zhang , Ying Lv , Shuang Gao
      We present here a new hybrid material (POM@MOF@SBA-15, PMS) in which metal organic framework (MOF) MOF-199 encapsulated Kegginpolyoxometalate (POM) catalyst (names as POM@MOF) was facilely confined in mesoporous SBA-15. This mesoporous SBA-15 confined MOF-199 with encapsulated Keggin POM material was exploited to act as a stable heterogeneous POMs-based catalyst in a liquid oxidative reaction medium. Cycling experiments of the PMS catalyst were carried out in the direct synthesis of phenol from benzene and demonstrated unprecedented stability of this novel type PMS catalyst.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • Silica cubes with tunable coating thickness and porosity: From hematite
           filled silica boxes to hollow silica bubbles
    • Abstract: Publication date: 1 September 2014
      Source:Microporous and Mesoporous Materials, Volume 195
      Author(s): Sonja I.R. Castillo , Samia Ouhajji , Sander Fokker , Ben H. Erné , Chris T.W.M. Schneijdenberg , Dominique M.E. Thies-Weesie , Albert P. Philipse
      We investigate the material properties of micron-sized silica coated cubic colloids, focusing on the coating thickness and porosity. The thickness of the silica coating of core–shell α-Fe2O3@SiO2 cubes and their corresponding hollow cubes can be tuned between 20 and 80nm, spanning the range of silica bubbles to silica boxes. The porosity of the silica cubes can be increased controllably by surface-protected etching using hot water as mild etchant and polyvinylpyrrolidone (PVP) as protecting polymer. We introduce infrared spectroscopy as a quantitative tool to monitor the extent of etching over time and to evaluate the influence of PVP on the etching process. The molar mass of PVP does not affect the etching rate, whereas an increased amount of PVP leads to enhanced protection against etching. Silica etching is found to be a two-step process, comprising a fast initial etching followed by a slower continuation. Hollow, porous silica cubes maintain their shape after extensive thermal treatment, demonstrating their mechanical stability.
      Graphical abstract image

      PubDate: 2014-06-14T14:57:01Z
       
  • Structural, textural and adsorption characteristics of bentonite-based
           composite
    • Abstract: Publication date: 1 September 2014
      Source:Microporous and Mesoporous Materials, Volume 195
      Author(s): M.S. Ranđelović , M.M. Purenović , B.Z. Matović , A.R. Zarubica , M.Z. Momčilović , J.M. Purenović
      An application of coatings composed of mixed (hydr)oxides over bentonite particles in aqueous suspension, in narrow range of pH, has been proven as a useful method for obtaining bentonite based composite with a developed, specific surface area and pronounced adsorption features toward cationic pollutants. This paper deals with detailed characterization of structure as well as textural and adsorption properties of bentonite based composite. The structure of the composite was examined by using XRD technique providing results that confirm changes in orientation of layered quasi-crystalline particles of montmorillonite, which is the most common component of bentonite clay. Surface area and pore volumes were determined by N2 adsorption at −196°C using BET, t-plot, α s-plot, Dubinin Radushkevich and Dollimore–Heal method. The results have revealed that the specific surface area for composite is about two times higher than for starting bentonite. Moreover, modification of bentonite leads to significant changes in the meso- and microporosity. Adsorption properties of the composite were studied by analyzing the adsorption of dye methylene blue which was used in this study as a model of cationic pollutant in water. The most prominent role in the mechanism of dye molecules retention on the surface, interlayers and in the pores of the adsorbent is ascribed to establishing of electrostatic, van der Waals and hydrogen bonds. The shape of adsorption isotherm indicates that methylene blue can be adsorbed onto composite in more than one layer.
      Graphical abstract image

      PubDate: 2014-06-14T14:57:01Z
       
  • Sensitive chemosensing of nitro group containing organophosphate
           pesticides with MOF-5
    • Abstract: Publication date: 1 September 2014
      Source:Microporous and Mesoporous Materials, Volume 195
      Author(s): Pawan Kumar , A.K. Paul , Akash Deep
      A luminescent metal–organic framework, MOF-5 [Zn4O (BDC)3 (BDC=1,4-benzenedicarboxylate)] has been synthesized by the reaction of zinc nitrate and terephthalic acid in diethylformamide (DEF) medium. The obtained fluorescent porous material has been characterized by X-ray diffraction, transmission electron microscopy, confocal microscopy, UV–vis spectroscopy, photoluminescence spectroscopy and surface area analysis. The synthesized MOF exhibits reasonably good fluorescence characteristics (excitation wavelength=330nm, emission wavelength=493nm). The potential of above Zn based MOF for the sensing of nitro group containing organophosphate pesticides (OPs), namely parathion, methyl parathion, paraoxon and fenitrothion, is demonstrated. It has been possible to detect the above four OPs separately in the concentration range of 5–600ppb. The detection limit of the proposed method for all the said OPs is 5ppb. Interestingly, their mixture also shows the above characteristic data. The proposed method for the sensing of nitro OPs is selective towards other OPs e.g., malathion, dichlorvos and monocrotophos.
      Graphical abstract image

      PubDate: 2014-06-14T14:57:01Z
       
  • Synthesis of ZIF-8 in a deep eutectic solvent using cooling-induced
           crystallisation
    • Abstract: Publication date: 1 September 2014
      Source:Microporous and Mesoporous Materials, Volume 195
      Author(s): Yasong Wang , Yunpeng Xu , Huaijun Ma , Renshun Xu , Hao Liu , Dawei Li , Zhijian Tian
      We report an alternative route for the synthesis of ZIF-8 in a choline chloride–urea deep eutectic solvent (DES). Zinc nitrate hexahydrate and 2-methylimidazole were dissolved in the hot DES. The ZIF-8 sample could precipitate from the DES when the solution was cooled using rapid cooling or programmed cooling. The effect of the synthetic conditions, including the cooling rate of synthesis system and the reaction temperature, on the particle size and morphology of the ZIF-8 sample were investigated. The product was characterised using PXRD, SEM, TG, the particle size analysis and gas-sorption. When the system was chilled via rapid cooling, the product was 0.35μm in size, agglomerating to form irregular spheres. After programmed cooling, the product was 5–50μm with a rhombic dodecahedron or truncated rhombic dodecahedron morphology, depending on the cooling rate and reaction temperature. In addition, the precipitation of ZIF-8 in DES is also discussed. ZIF-8 synthesised in DES also displayed excellent thermal and chemical stability, as well as good gas adsorption and separation performances.
      Graphical abstract image

      PubDate: 2014-06-14T14:57:01Z
       
  • A molecular model to explain the controlled release from SBA-15
           functionalized with APTES
    • Abstract: Publication date: 1 September 2014
      Source:Microporous and Mesoporous Materials, Volume 195
      Author(s): Antonio L. Doadrio , José M. Sánchez-Montero , Juan C. Doadrio , Antonio J. Salinas , María Vallet-Regí
      A molecular model with the approximate pore diameter of SBA-15 was constructed for the first time to investigate the effect of functionalize the matrix with 3-aminopropyl-triethoxy-silane (APTES) in the release of Chicago Sky Blue 6B (CSB). It was expected that the positively charged amino groups of APTES could interact with the negatively charged sulphonic groups of CSB allowing controlling the release process. Indeed the experimental study showed that the release kinetics of CSB from SBA-15-APTES is two orders of magnitude smaller than from native SBA-15. However molecular modelling calculations investigating the possible interactions of APTES and SBA-15 yield unexpected results. In the model including only the condensation between the silanol groups of SBA-15 and APTES, the calculated interaction energy of CSB was quite similar than with the model of native SBA-15. However when additional electrostatic interactions of the –NH2 groups of APTES with the mesoporous matrix were modelled the mesoporous channels underwent a considerable deformation. These results point to the structure deformation as the cause of the greater retention of CSB in SBA-15-APTES and warn about the special features of APTES when used to functionalize mesoporous silica materials. The model built in this paper could be used to construct predictive models in analogous drug delivery systems.
      Graphical abstract image

      PubDate: 2014-06-14T14:57:01Z
       
  • Sol–gel synthesis of nanosized titanium oxide in a porous
           coordination polymer
    • Abstract: Publication date: 1 September 2014
      Source:Microporous and Mesoporous Materials, Volume 195
      Author(s): Cho Rong Kim , Takashi Uemura , Susumu Kitagawa
      Nanosized titanium oxide (TiO2) was synthesized in the channels of a porous coordination polymer (PCP) [La3+(1,3,5-benzenetrisbenzoate)] n by the sol–gel reaction of titanium tetraisopropoxide. XRD, IR, UV–vis, and gas sorption measurements demonstrated that nanosized TiO2 was formed in channels of the PCP. In this system, the resultant PCP⊃TiO2 composite showed enhancement of the adsorption of water. Furthermore, the sorption behavior of the composite could be changed by UV irradiation.
      Graphical abstract image

      PubDate: 2014-06-14T14:57:01Z
       
  • A combination of porous and crystalline characters in carbon aerogels by a
           synergistic graphitization
    • Abstract: Publication date: 1 September 2014
      Source:Microporous and Mesoporous Materials, Volume 195
      Author(s): Zijie Xu , Donghui Cai , Zhonghua Hu , Lihua Gan
      The synergistic graphitization of carbon aerogels (CAs) was carried out by annealing CAs containing different amounts of manganese additives in molten sodium metals at 800°C. Resulted samples were examined by X-ray diffraction, Raman scattering spectra, electron microscopy and gas physisorption methods. Effects of manganese additives and sodium metals on the synergistic graphitization were investigated. Graphitized CAs samples exhibit larger specific surface areas and total pore volumes than initial CAs and the graphitization of CAs can be adjusted at the same temperature by changing the content of manganese additives in CAs. The synergistic graphitization is related to the thermodynamic environment in CAs improved by the reduction of manganese additives in sodium metals. It results in a combination of porous and crystalline characters in graphitic carbons.
      Graphical abstract image

      PubDate: 2014-06-14T14:57:01Z
       
  • Novel conjugate adsorbent for visual detection and removal of toxic
           lead(II) ions from water
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Md. Rabiul Awual , Md. Munjur Hasan
      Lead (Pb(II)) is a very toxic heavy metal that even at low concentration can affect living organisms. Therefore, designing effective materials with high selectivity and cost-effeciency is essential for the control capturing of toxic Pb(II) ions. This study developed a ligand based conjugate adsorbent for simultaneous Pb(II) detection and removal from water samples. The organic ligand of 4-dodecyl-6-((4-(hexyloxy)phenyl)diazenyl) benzene-1,3-diol (DPDB) was synthesized and DPDB was successfully immobilized onto mesoporous silica by a direct immobilization approach. The Pb(II) ion was detected by the charge transfer (π–π transition) transduction mechanism with sensitivity and selectivity. The experiment conditions were optimized based on contact time, solution acidity, initial Pb(II) concentration and pH value and diverse metal salt concentrations. The adsorbent was highly sensitive, and the limit of detection was 0.18μg/L for Pb(II) ions. The Pb(II) sorption synthetic aqueous solution also underwent batch tests. However, the sorption capacity depended on the solutions pH, initial concentration and to some extent on the competing ions. The experimental data revealed that the maximum Pb(II) sorption was possible at pH 5.0. The presence of other cations and anions did not adversely affect the Pb(II) capturing by the adsorbent. The maximum sorption capacity was determined to be as high as 195.31mg/g. The extraction of Pb(II) ions from the saturated adsorbent was possible with 0.20M HCl. The regenerated adsorbent that remained maintained the high selectivity to Pb(II) ions and exhibited almost the same sorption capacity as that of the original adsorbent. However, the sorption efficiency slightly decreased after ten cycles. Therefore, the proposed adsorbent offered a cost-effective material and may be considered a viable alternative for effectively monitoring and removing toxic Pb(II) ions from water samples without the need for sophisticated instrument.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • Photoprocesses of molecules encapsulated in porous solids XI: Excited
           state dynamics of proflavine and photosensitization of TiO2 in nanoporous
           materials
    • Abstract: Publication date: 1 September 2014
      Source:Microporous and Mesoporous Materials, Volume 195
      Author(s): Karuppannan Senthilkumar , Singaravelu Chandra Mohan , Shanmugam Easwaramoorthi , Kandasamy Jothivenkatachalam , Paramasivam Natarajan
      Photosensitization of titanium dioxide (TiO2) encapsulated in the nanoporous materials of different pore size using proflavine dye as the sensitizer was studied using steady state and time resolved fluorescence spectral techniques. The titanium dioxide encapsulated nanoporous materials was prepared by ion exchange method and were characterized by UV–visible diffuse reflectance spectra, ICP-OES, BET and powder XRD techniques. The observed results show that TiO2 were encapsulated in the nanochannels and nanocavities of the host materials. The photophysical properties of proflavine are found to be influenced by the pore size and the Si/Al ratio of the host materials. Photosensitization of TiO2 in the host by proflavine was inferred from the decreased stead state fluorescence intensity of the dye molecule. In the case of the dye encapsulated TiO2 loaded ZSM-5, fluorescence intensity decreases with red shifted emission maximum. Excitation of proflavine in presence of TiO2 nanoparticles leads to protonation of proflavine in the excited state as confirmed in ultrafast time resolved fluorescence and decay associated spectral studies. On the other hand, no protonated proflavine was detected when zeolite-Y and MCM-41 were used as the host material.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • ESR and DFT study of the paramagnetic carbon centers stabilized in
           γ-irradiated zeolites exposed to carbon monoxide
    • Abstract: Publication date: 1 September 2014
      Source:Microporous and Mesoporous Materials, Volume 195
      Author(s): Marcin Sterniczuk , Jarosław Sadło , Grażyna Strzelczak , Jacek Michalik
      Free radicals are important transient species in many chemical reactions, especially in catalysis, photochemistry and radiation chemistry. However, the identification of free radicals is difficult because of their high reactivity. For catalytic systems the EPR study of radiation-induced free radicals at low temperature brings new insights to better understand many real catalytic processes. In this article we present an EPR study on carbon-centered radicals formed in γ-irradiated ZSM-5, MOR, FAU and LTA zeolites exposed to 13CO (S=1/2). Four different types of carbon-centered radicals were detected. In zeolites with high Si content such as ZSM-5, FAU Y and MOR, three types of radical centers are stabilized: center A [SiO −Al] +CO, center A′ [SiOSi] +CO and center B [SiO] CO. In low-siliceous zeolites only center A is recorded. The hyperfine splitting A av[13C] values for A and A′ centers are changing in the range 24.7–29.3mT depending on Si/Al ratio and zeolite structure. These differences are caused by subtle changes in geometry of carbon centers occurring even in zeolite frameworks belonging to the same topological group. On the other hand, the hyperfine splitting of center B is changing only in narrow range 21.0–21.4mT, indicating that magnetic properties of this center weakly depend on geometry. Additionally, in ultra stable Y zeolite (USY) a carbon radical center with exceptionally high A av[13C] value (A x =35.9mT, A y =32.3mT, A z =32.3mT) has been observed. We assigned it to the +CO radical cation which is located in the immediate vicinity of EFAL (extra framework aluminum) species. This carbon radical is very unstable and disappears completely above 120K.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • Investigation of the surfactant type effect on characteristics and
           bioactivity of new mesoporous bioactive glass in the ternary system
           SiO2–CaO–P2O5: Structural, textural and reactivity studies
    • Abstract: Publication date: 1 September 2014
      Source:Microporous and Mesoporous Materials, Volume 195
      Author(s): Nouha Letaïef , Anita Lucas-Girot , Hassane Oudadesse , Rachida Dorbez-Sridi , Philippe Boullay
      In this study, a mesoporous bioactive glass 92S6 (92% SiO2, 6% CaO, and 2% P2O5), was successfully prepared using two different surfactants. The template was further removed by calcination to generate unorganized or well-ordered pores. The bioactive glass was characterized by wide angle X-ray diffraction (WAXRD) analysis, small angle X-ray diffraction (SAXRD) analysis, Fourier Transform Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). From the isotherm desorption branch, the surface area was determined using the Brunauer–Emmett–Teller (BET) method, while pore volume and pore size distribution were determined by the Barrett–Joyner–Halenda (BJH) method. The in vitro bioactivity tests were also conducted in simulated body fluid (SBF). Finally, the samples were analyzed to quantify the apatite formation ability when soaked in SBF solution. The evolutions of silicon (Si), phosphorus (P) and calcium (Ca) concentrations in SBF were evaluated by inductively coupled plasma optical emission spectrometry (ICP-OES). The SAXRD and TEM studies evidence the influence of the structure-directing agent (ionic surfactant CTAB or non-ionic P123) in the generation of unorganized or well ordered pores in the sol–gel synthesis of a bioactive glass in the ternary system SiO2–CaO–P2O5. As observed from small-angle XRD patterns and TEM images, the presence of non-ionic surfactant and subsequent calcination lead to the formation of highly ordered mesoporous glass. The better textural properties observed in the “ordered mesoporous glasses” compared to those of “non-ordered mesoporous glasses” lead to a faster in vitro bioactivity kinetics.
      Graphical abstract image

      PubDate: 2014-06-14T14:57:01Z
       
  • Hydrothermal conversion of FAU and ∗BEA-type zeolites into MAZ-type
           zeolites in the presence of non-calcined seed crystals
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Koutaro Honda , Ayako Yashiki , Masahiro Sadakane , Tsuneji Sano
      To gain further insight into the interzeolite conversion, we investigated the seed-assisted synthesis of MAZ-type zeolite from various starting zeolites with different framework structures, such as FAU, ∗BEA, and MFI-type zeolites, without the use of an organic structure-directing agent (OSDA). The OSDA-free synthesis of MAZ-type zeolite from FAU and ∗BEA-zeolites was successfully achieved in the presence of non-calcined seed crystals. However, a pure MAZ-type zeolite could not be obtained from MFI-type zeolite. The crystallinity of the obtained MAZ-type zeolite strongly depended on the kind of framework structure of the initial zeolite. The crystallinity of MAZ from FAU was higher than that of MAZ from ∗BEA. It was confirmed that the structural similarity between the starting and the finally crystallized zeolites is a crucial factor for the interzeolite conversion process. The presence of composite building units composed of a common structural entity, namely a four-membered ring, is a key factor for the OSDA-free synthesis of MAZ-type zeolite.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • Comparative study of Zr, Nb, Mo containing SBA-15 grafted with
           amino-organosilanes
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Magdalena Olejniczak , Maria Ziolek
      Transition metals of group IV (Zr), group V (Nb), and group VI (Mo) were introduced into SBA-15 materials during the synthesis towards the production of metallosilicates, MSBA-15, to be used as supports for 3-aminopropyl-trimethoxysilane (APTMS), and 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane (3APTMS). The materials obtained were characterized by N2 adsorption/desorption, XRD, TEM, ICP, XPS, UV–Vis, FT-IR and pyridine adsorption. The results indicated that the metals were loaded in the cationic state: Zr4+, Nb5+ and Mo6+ and preferentially located on the SBA-15 surface. The highest efficiency of metal loading in SBA-15 under the conditions used in this work was reached for molybdenum, whereas the highest metal content on the surface was observed for ZrS. The number of Lewis acid sites (LAS) changed in the following order: ZrS≫NbS>MoS, whereas their strength as follows: ZrS>NbS⩾MoS(HP). Zirconium containing material exhibited additionally BrØnsted acidity. The efficiency of propyl-amine incorporation changed according to the electron state of metals: Zr<Nb<Mo. The binding of propyl-amine to metal cations determined the amine stability.
      Graphical abstract image Highlights .

      PubDate: 2014-06-14T14:57:01Z
       
  • Synthesis of carbon with bimodal porosity by simultaneous polymerization
           of furfuryl alcohol and phloroglucinol
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Maryam Peer , Ali Qajar , Ramakrishnan Rajagopalan , Henry C. Foley
      Carbon materials with bimodal porosity have shown enhanced performance in a wide variety of applications including catalysis, energy storage and fluid separation. Presence of mesoporosity is essential to lower the mass transfer limitation imposed by the microporous nature of the carbons. The synthesis approaches used to prepare bimodal carbons with controlled micro/mesopore size and narrow pore size distribution, usually involve multi step processes and the use of harsh chemicals and solvents. Herein, we present a simple one step method that can be used to synthesize carbon with bimodal pore size distribution. Simultaneous polymerization of furfuryl alcohol and phloroglucinol-formaldehyde in the presence of a structure-directing agent (Pluronic F-127) was carried out and the resultant polymer was pyrolyzed to yield the bimodal carbon. Effect of polymerization conditions such as concentrations of monomer, initiator and surfactant on the bimodal pore size distribution of the carbon was studied in detail. Pyrolyzed precursors form carbons with narrow mean micropore size of 0.5nm and mean mesopores ranging from 3.5 to 6nm. The range of the mesopore size could be altered by varying the polymerization parameters (acid and surfactant concentration) as well as selective oxidation using CO2 gas.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • Preparation and catalytic properties of RuSalen-functionalized periodic
           mesoporous silicas
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Xiufeng Shi , Binbin Fan , Hongyu Li , Ruifeng Li , Weibin Fan
      A new approach was employed to prepare metal complex-functionalized periodic mesoporous silica. This approach mainly involves the following three steps, that is, chloromethylation of –C6H4– sites in the framework of PMOs into active –C6H3CH2Cl–, amination of PMOs via reacting –C6H3CH2Cl– with piperazine and covalent attachment of RuSalen by refluxing the aminated PMOs in RuSalen ethanol solution. The obtained hybrid material was characterized with XRD, N2 sorption, FTIR, diffuse reflectance UV–vis spectroscopy, TEM and 13C MAS NMR techniques. It shows higher activity and stability in the oxidation of cyclohexene with H2O2 than the corresponding RuSalen functionalized SBA-15 prepared by the similar method except that the introduction of active –C3H6Cl was achieved by grafting 3-chloropropyltriethoxysilane on SBA-15.
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      PubDate: 2014-06-14T14:57:01Z
       
  • Detoxification of hexavalent chromium using hydrothermally modified
           agricultural detritus into mesoporous zeolitic materials
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Bhavna A. Shah , Chirag B. Mistry , Ajay V. Shah
      The present study reports the removal of hexavalent chromium by bagasse fly ash (BFA) – an agricultural detritus and synthesized modified zeolitic materials. The native BFA was successfully converted into mesoporous zeolitic materials with (ECZBFA) and without electrolyte (CZBFA) media using hydrothermal treatment. The proximate analysis and physicochemical analysis were determined by wet analysis methods. The instrumental techniques like XRF, FTIR and SEM were used to determine the chemical composition of sorbents, functional groups and its surface morphology, respectively. The optimum pH, contact time, sorbent dose, initial concentration of Cr(VI) and effect of temperature on sorption were investigated thoroughly to optimize the uptake condition. Pseudo second order model and diffusion models like film diffusion and pore diffusion models were well characterized for Cr(VI) sorption on sorbent. Langmuir, Freundlich, Dubinin–Redushkwich and Temkin isotherm were used to understand the efficiency of zeolitic materials and its nature of sorption. Out of the three mesoporous sorbents ECZBFA shows better uptake capacity of Cr(VI) than that of CZBFA and BFA. The uptake of Cr(VI) was studied by batch and column method.
      Graphical abstract image

      PubDate: 2014-06-14T14:57:01Z
       
  • Spectroscopic investigation of hydrothermally synthesized zeolites from
           expanded perlite
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): M. Król , W. Mozgawa , J. Morawska , W. Pichór
      The results of vibrational spectroscopy studies of zeolites synthesized from expanded perlite using hydrothermal method were presented. The starting material used was a waste obtained during the production of expanded perlite. The effects of synthesis temperature and time, as well as NaOH concentration and solid to liquid ratio on the obtained products were determined. The resulting materials were analyzed regarding phase composition. In particular, the structures of materials were examined using FT-IR spectroscopy in the middle and far infrared ranges as well as Raman spectroscopy. The results were compared to the XRD and XRF measurements, as well as SEM observations. It has been found that by using a sufficiently high concentration of NaOH, it is possible to efficiently synthesize zeolite at temperatures above 50°C. The presence of zeolite phase was confirmed by the measurement of spectra. Pseudolattice range, i.e. 800–400cm−1, was analyzed in detail. In this range, bands associated with the ring vibrations occur. They are characteristic for secondary building units (SBU) existing in zeolite structure. Depending on time, temperature and NaOH concentration, zeolite X, A, Na-P1 and hydroxysodalite have been identified as synthesis products in autogenous pressure.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • Fe–Ni–Al pillared montmorillonite as a heterogeneous catalyst
           for the Catalytic Wet Peroxide Oxidation degradation of Orange Acid II:
           Preparation condition and properties study
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Han Gao , Bin-Xia Zhao , Jin-Chao Luo , Di Wu , Wei Ye , Qi Wang , Xiao-Li Zhang
      The introduction of nickel in Fe–Al pillared montmorillonite was studied to enhance the catalytic performance of metal-pillared clays during Catalytic Wet Peroxide Oxidation (CWPO). Fe–Ni–Al pillared montmorillonite was synthesized by ion exchange method and tested by CWPO reaction. Catalysts were characterized by several methods: chemical composition analysis, X-ray diffraction analysis, N2 adsorption/desorption, Fourier Transformed Infrared Spectroscopy, H2 temperature-programmed reduction and thermal analysis. The results indicated the enhanced structural properties and catalytic performance of prepared clays could correspond to the introduction of active metal oxides as pillars supporting the interlayer space. Besides, the effects of active metal molar loading (AML), Fe/Ni molar ratio and calcination temperature on the pillared clays were measured and discussed. It was proposed the introduction of nickel to the pillaring solution may contribute to better active iron stability and catalytic performance. It turned out the iron presented in the clays as FeOOH form when nickel was introduced. Further, moderate calcination temperature would keep a modified clay structure and retain FeOOH as active sites in the clay, while high temperature (above 773K) heating process may damage the interlayer structure. Throughout this work, Fe(4)Ni(6)Al-MMT(773K), heated at 773K with 4:6 Fe/Ni molar ratio and 6% active metal loading, shows better catalytic behavior and stronger stability among all the prepared materials.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • Preparation of hierarchical porous carbons from amphiphilic
           poly(vinylidene chloride-co-methyl acrylate)-b-poly(acrylic acid)
           copolymers by self-templating and one-step carbonization method
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Jie Yang , Yongzhong Bao , Pengju Pan
      Based on our previous proposed method to fabricate the hierarchical porous carbons (HPCs), a series of amphiphilic poly(vinylidene chloride-co-methyl acryalte)-b-poly(acrylic acid) (PVDC-b-PAA) copolymers were prepared via RAFT polymerization and used to prepare the HPCs by self-templating and one-step carbonization method. The phase structure and thermal degradation behavior of PVDC-b-PAA copolymers, as well as the morphology and pore structure of corresponding carbons were investigated. It was found that all block copolymers exhibited micro-phase separation feature and showed the PAA-dispersed, bi-continuous, and PAA-dominated phase structures as the PVDC/PAA molar ratio varied from 3:1 to 0.77:1. Although the PVDC-b-PAA copolymers exhibited the individual glass transitions of each block, the thermal degradations of PVDC and PAA blocks were interacted and overlapped. The carbons prepared from PVDC-b-PAA contained the micro- and meso-pores, which were mainly originated from the thermal degradation of PVDC segment and the pyrolysis of PAA segment, respectively. The carbons prepared from PVDC66-b-PAA22 copolymer exhibited a maximum Brunauer–Emmett–Teller surface area of 1093m2 g−1 and a maximum total pore volume of 0.51cm3 g−1. Due to the incomplete pyrolysis of PAA segment and the jamming effect to pores caused by the PAA-based carbon, the total pore volume of HPCs prepared from PVDC-b-PAA copolymers were lower than that of HPCs prepared from the PVDC-b-polystyrene copolymers (J. Mater. Sci. 49 (2014) 1090–1098).
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • Thermal stabilization of alumina modified by lanthanum
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Pierre Alphonse , Benjamin Faure
      Transition alumina, with different La loadings, were synthesized from boehmite (AlOOH) hydrosols containing a PEO/PPO/PEO triblock copolymer (Pluronics® P123) and lanthanum nitrate. After calcination at 500°C, the xerogels prepared from these sols have large specific surface area (≈400m2/g) and very large porous volumes, increasing with the amount of La to reach 2.5cm3/g for La/(La+Al)=0.036. This material still kept a surface area close to 180m2/g and a pore volume of 2.3cm3/g when it was calcined at 1000°C. However, after calcination at 1200°C, the best textural properties (70m2/g and 0.6cm3/g) were observed for La/(La+Al)=0.015. Larger La loadings led to the formation of LaAl11O18 and LaAlO3 and the detection of these mixed oxides was associated with a decrease of surface area and pore volume. The improvement of the thermal stability of these materials can be explained by the synergy of two effects: (i) the adsorption of copolymer onto fiber-like boehmite nanoparticles, preventing their compact rearrangement during the drying and maintaining a large porosity after calcination; (ii) the inhibition of the sintering process through the formation of thermally stable species between reactive surface sites (strong Lewis acid sites) and lanthanum atoms.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • Optoelectronic properties of nanoporous Ge layers investigated by surface
           photovoltage spectroscopy
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): D. Cavalcoli , B. Fraboni , G. Impellizzeri , L. Romano , E. Scavetta , M.G. Grimaldi
      Optoelectronic properties of nanoporous Ge (np-Ge) have been investigated by Surface Photovoltage Spectroscopy. Electronic transitions in np-Ge have been compared with the ones obtained on crystalline and amorphous Ge, their dependence on ion implantation fluence and annealing treatment has been investigated. Np-Ge layers decorated with Au nanoparticles have been studied, and a significant photovoltage enhancement, probably related to light trapping effects, has been found. This result can be of major interest for future photovoltaic applications.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • Enhancement of catalytic lifetime of nanostructured SAPO-34 in conversion
           of biomethanol to light olefins
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Erfan Aghaei , Mohammad Haghighi
      Nanostructured SAPO-34 was synthesized via moderate temperature hydrothermal method in various synthesis times with controlled particle size. The effect of crystallization time on purity and crystallinity of synthesized samples was investigated. The catalysts were characterized by XRD, FESEM, BET, FTIR and EDX techniques. According to the XRD analysis, all the samples have chabazite structure related to SAPO-34. By decreasing crystallization time, pure phase was produced and the particle size reduced. BET analysis illustrated high surface area for all catalysts especially for pure samples. Synthesis at moderate temperature resulted in spherical morphology by the aggregation of nano-sized crystallites. Significant difference was observed in the deactivation behavior of the synthesized catalysts. Samples with high crystallinity and small particles had proper catalytic lifetime. In addition, all synthesized catalysts at moderate temperature had longer lifetime than the synthesized sample at lower temperature and longer crystallization time. The SAPO-34 synthesized at 250°C and 16h was found to be the best catalyst regarding to the time on stream performance due to high crystallinity and relevant morphology. This catalyst had 23h lifetime in the methanol to olefins process while the synthesized sample at low temperature had 4h lifetime.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • MIL-53 frameworks in mixed-matrix membranes
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Josephine O. Hsieh , Kenneth J. Balkus Jr. , John P. Ferraris , Inga H. Musselman
      The MIL-53 metal–organic framework (MOF) is known to change reversibly from an open-pore framework (MIL-53-ht) to a closed-pore framework (MIL-53-lt) depending on the temperature, pressure, or guest molecules absorbed. Three frameworks of the additive, MIL-53-as synthesized (MIL-53-as), MIL-53-ht, and MIL-53-lt, were prepared, characterized, and combined with Matrimid® to form mixed-matrix membranes (MMMs) for gas separations. The MIL-53-ht/Matrimid® MMMs exhibited higher values of permeability compared to Matrimid® as well as an increased CO2/CH4 selectivity suggesting that the open-pore MIL-53 framework was maintained in the polymer matrix. In addition to higher permeability values, MIL-53-as/Matrimid® MMMs showed higher selectivity for gas pairs with kinetic diameters differing by ⩾0.5Å, including H2/O2, CO2/CH4, H2/CH4, and H2/N2, suggesting the presence of excess benzene dicarboxylic acid molecules within the pores that reduced its diameter enabling the material to discriminate between smaller and larger gases. MIL-53-lt did not retain its closed-pore form in the MMM. Rather, it irreversibly converted to the open-pore form (MIL-53-ht) due to the exchange of water present in the MIL-53 pores with chloroform solvent molecules during membrane casting and to pore penetration and confinement by Matrimid® polymer chains. This finding, that a polymer matrix stabilizes a MOF pore architecture within an MMM, is significant in that the desired selectivity of a MOF-MMM system may be achievable.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • Mn-analcime: Synthesis, characterization and application to cyclohexene
           oxidation
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Amal Bejar , Semy Ben Chaabene , Maguy Jaber , Jean-François Lambert , Latifa Bergaoui
      The hydrothermal synthesis of Mn-analcime was performed by mixing manganese(II) carbonate, silicic acid and aluminum nitrate in a basic medium in the 120–175°C temperature range for 6–72h. Different Mn/Al ratios were used. The obtained samples were characterized by powder XRD, N2 physical adsorption analysis, TGA/DTA, transmission electron microscopy, elemental analysis, IR, XPS, EPR and 29Si and 27Al MAS-NMR spectroscopies. Manganese is probably mostly in the +IV oxidation state and partly substitutes silicon in the zeolite framework. The catalytic properties of Mn-analcime were evaluated in the cyclohexene oxidation reaction and highlight an interesting activity of this material, together with a good recyclability, which make it a promising catalyst for selective oxidation reactions.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • Enhancement of phosphate removal from water by TiO2/Yemeni natural
           zeolite: Preparation, characterization and thermodynamic
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Aref Alshameri , Chunjie Yan , Xinrong Lei
      In order to develop an effective technique for enhancing the efficiency of phosphate ion (PO4 3−) removal, a novel composition of TiO2/Zeolite (TZ) adsorbent was prepared and investigated systematically. The characteristics of TZ and its mechanism for PO4 3− removal were investigated and compared with that of natural zeolite (NZ). Important parameters which affect adsorption, such as contact time, pH, dosage, temperature, initial PO4 3− concentration and the presence of competing anions were investigated. Almost 100% removal efficiency was achieved by the TZ composite at low initial PO4 3− concentrations. The specific surface area and PO4 3− adsorption capacity of the composite material reached 166.5m2/g and 37.6mg/g, respectively. Moreover, Maximum adsorption occurred at around pH 2–4 and 35°C. The results of zeta potential, FTIR, XRF and EDS analyses indicated that electrostatic attraction and replacement of surface hydroxyl groups (T/OH) by phosphate were the main adsorption mechanism. Arsenate and silicate markedly decreased the removal of PO4 3− whereas the effect of other anions was insignificant. The adsorption isotherm results illustrated that Freundlich model (FM) provided the best fit for the equilibrium data. In addition to that, the change in free energy (ΔG ○), enthalpy (ΔH ○) and entropy (ΔS ○) revealed that the adsorption of PO4 3− ion by zeolite is spontaneous and endothermic at 25 and 35°C. It was concluded that a TiO2/Zeolite composite is a highly efficient and economic adsorbent material with good regeneration and can be utilized in the remediation of environmental pollution.
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      PubDate: 2014-06-14T14:57:01Z
       
  • Photochromic behavior of silver nanoparticle incorporated titanosilicate
           ETS-10 films
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Sezin Galioglu , Melda Isler , Zeynep Demircioglu , Mehmet Koc , Francis Vocanson , Nathalie Destouches , Raşit Turan , Burcu Akata
      The partially reversible photochromic behavior of Ag0 nanoparticle incorporated titanosilicate ETS-10 films was achieved for the first time. Ag+ ions were incorporated into ETS-10 matrix by ion-exchange of extra framework cations (i.e., Na+ and K+) to form Ag+ ion-exchanged ETS-10. The colored (i.e., activated state) and colorless (i.e., bleached state) forms of the photochromic system of Ag0 nanoparticle incorporated ETS-10 films were achieved through thermal reduction and exposure to visible laser at 532nm wavelength, respectively. The resulting Ag0-ETS-10 films and also Ag+-ETS-10 crystals have been characterized by ICP-OES, XRD, XPS, FE-SEM, HR-TEM, UV–vis spectroscopies. Partial restoration of color was achieved after second thermal treatment, which implies reversibility of the photochromic process. Furthermore, Density Functional Theory (DFT) results showed that ETS-10 had robust geometry and incorporation of the silver nanoparticles had minimal effect on the structure. The relationship of ETS-10’s unique structural formation along with the integration of Ag0 nanoparticles within its matrix and its subsequent photochromic property was shown for the first time.
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      PubDate: 2014-06-14T14:57:01Z
       
  • Novel activated cotton as eco-adsorbent for solvent vapor
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Ka-lok Chiu , Dickon H.L. Ng
      The potential of activated cotton (AC) as a low cost eco-absorbent for the recovery of organic solvent vapor was studied in this study. Its pore structure and chemical structure were characterized. Its adsorption speed, saturated adsorption volume and desorption process of solvent vapor were also evaluated. Its organic vapor adsorption process is fast enough to reach equilibrium within 10min. It adsorbs more solvent vapor than other activated carbons due to its high microporosity. Finally, less than 200°C is required for the complete desorption of adsorbed species.
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      PubDate: 2014-06-14T14:57:01Z
       
  • Density functional theory study of side-chain alkylation of toluene with
           formaldehyde over alkali-exchanged zeolite
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Yang Wang , Mingyuan Zhu , Lihua Kang , Bin Dai
      The adsorption of the alkali-metal cation (M=Li+, Na+, K+, Rb+, and Cs+) and the reaction mechanism of the side-chain alkylation of toluene with formaldehyde over MY basic zeolite (M=Rb+ and Cs+) were investigated using density functional theory calculations. During co-adsorption, the zeolite adsorbs toluene preferentially and then formaldehyde. The side-chain alkylation in MY zeolite (M=Rb+ and Cs+) consists of the following two steps: toluene reacts with formaldehyde to obtain phenyl ethanol, and then the intramolecular dehydration of phenyl ethanol produces styrene and water. Phenethyl alcohol dehydroxylation is the rate-controlling step. Although the activation energy is similar in Rb+- and Cs+-modified zeolite (63.09 and 62.20kcalmol−1), the products are much easily removed from the system in Cs+-modified zeolite. Scilicet, Cs+-modified zeolite is a suitable catalyst during the side-chain alkylation of toluene.
      Graphical abstract image

      PubDate: 2014-06-14T14:57:01Z
       
  • Long-domain simulation of flow in open-cell mesoporous metal foam and
           direct comparison to experiment
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Ahmed S. Suleiman , Nihad Dukhan
      Open-cell metal foam is a class of modern mesoporous media that possesses high thermal conductivity, large accessible surface area per unit volume and high porosities (often greater than 90%). When a fluid passes through the foam, the internal structure of the foam, which is web-like, produces a complex flow field including flow reversal and vigorous mixing. All of these attributes make metal foam a very attractive core for many engineering applications, e.g. heat exchangers, filtration devices and reactors. The rather complex and intrinsically random architecture of the foam is extremely difficult to capture exactly. In this paper, we use a unit cell geometrical model to numerically investigate the flow field and pressure drop inside commercial open-cell aluminum foam. The Navier–Stokes equations are solved directly, and velocity and pressure fields are obtained for various approach velocities using a commercial numerical package. The details of the modeling process are given in this paper. The pressure drop results are compared to the Forchheimer equation, from which the permeability and form drag coefficient are calculated. Comparisons to experimental data were also carried out. The commercial foam that was used in the experiment had 10 pores per inch and porosity of 90% approximately. Air was forced to flow inside the foam using an open-loop wind tunnel. Good agreement between the modeling and experimental results are obtained for low velocities, with the agreement becoming poorer for larger velocities. The results for the low-velocity range are encouraging and lend confidence to the modeling approach, which paves the way for investigating other phenomena inside the foam, using the same unit cell, e.g. heat transfer. The limitations of the models are outlined and discussed.
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      PubDate: 2014-06-14T14:57:01Z
       
  • Magnetic core-mesoporous shell nanocarriers with drug anchorages suspended
           in mesopore interior for cisplatin delivery
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Xiangyang Zhu , Jinlou Gu , Yongsheng Li , Wenru Zhao , Jianlin Shi
      The synthesis of the core–shell magnetic mesoporous silica nanocomposites has recently attracted much attention, while it is highly desirable to modify the mesoporous shell with organic components for special interaction with guest molecules. Herein we propose a facile strategy to prepare novel magnetic mesoporous nanocomposites with superparamagnetic Fe3O4 core and mesoporous silica shell functionalized with pendant carboxylic groups in their mesopore interior. The successful deposition of organic–inorganic mesoporous layer on magnetic nanoparticles is verified by XRD, TEM and BET characterizations, and the integration of organic units is manifested by FT-IR and solid state NMR techniques. The inherent carboxylic units on the obtained nanocomposites serve as effective drug anchorages for coordinating with Pt atoms in the anti-cancer drug of cisplatin, resulting in increased drug loading amount and its sustained release. The obtained nanocomposites exhibit excellent water dispersity with well-defined size distribution (around 85nm), ordered mesoporous characteristics, superparamagnetism and high magnetization (37.0emug−1). The nanocomposites could not only effectively transport the encapsulated cisplatin into cancer cells but also mediate its sustained release in endosomes or lysosomes, leading to enhanced antitumor efficiency against both A549 and MCF-7 cell lines.
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      PubDate: 2014-06-14T14:57:01Z
       
  • Toward longer life catalysts for dehydration of glycerol to acrolein
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Raja Znaiguia , Laure Brandhorst , Noëlle Christin , Virginie Bellière Baca , Patrick Rey , Jean-Marc M. Millet , Stéphane Loridant
      In this work, tungstated zirconias were prepared by different methods and evaluated for glycerol dehydration to acrolein. For all the tested catalysts, the absence of crystalline WO3 was checked by XRD and Raman microscopy. Textural properties were determined by liquid N2 adsorption and mercury penetration measurements. For catalysts prepared from hydrous zirconia (ZrO2·xH2O) incorporating W by anionic exchange, clear correlation between stability and pore diameter was shown for the first time and it was confirmed that SiO2 addition favors the formation of bigger mesopores. This effect was not observed for catalysts obtained by simple W impregnation of hydrous zirconia. In this case, among different preparation parameters investigated, only the addition of a reflux step increased the pore diameter. Finally, tungstated zirconias were prepared by W impregnation of crystalline ZrO2 thermally stable and owning chosen textural properties. As coking leads to pore shrinkage, much higher stability was obtained for catalysts owning high proportion of big mesopores (>10nm) and small proportion of pores below 5nm. These characteristics appeared to be key parameters to tailor longer life catalysts for dehydration of glycerol.
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      PubDate: 2014-06-14T14:57:01Z
       
  • Seed-assisted synthesis of high silica ZSM-35 through interface-induced
           growth over MCM-49 seeds
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Linying Wang , Peng Tian , Yangyang Yuan , Miao Yang , Dong Fan , Hui Zhou , Wenliang Zhu , Shutao Xu , Zhongmin Liu
      High-silica ZSM-35 has been successfully synthesized by adding non-calcined MCM-49 seeds to the initial gel without the help of organic structure-directing agents (OSDAs). This is the first report of seed-assisted synthesis without the common composite building units (CBUs) contained in the seeds and products. High solid yields of 65–85% have been achieved, which are the highest values ever reported for the seed-assisted synthesis. Alkaline treatment and hyperpolarized 129Xe NMR are employed to study the ZSM-35 products, and an interface-induced growth mechanism is proposed, in which ZSM-35 grows over partially dissolved MCM-49 through interface connection. It is supposed that similarity in the local atomic connection between the seeds and target zeolites, even without the common CBUs, would have the possibility to lead to a successful synthesis. The catalytic performance of H-ZSM-35 is tested in the dimethyl ether (DME) carbonylation, which shows excellent stability and high selectivity towards methyl acetate (MA).
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • Development of a hybrid membrane through coupling of high selectivity
           zeolite T on ZIF-8 intermediate layer and its performance in carbon
           dioxide and methane gas separation
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Zee Ying Yeo , Siang-Piao Chai , Peng Wei Zhu , Abdul Rahman Mohamed
      This work demonstrated a novel hybrid membrane development through coupling of zeolite T membrane on ZIF-8 intermediate layer. ZIF-8 which acted as an intermediate layer was firstly grown on a macroporous α-alumina support via vacuum seeding. Pure phase zeolite T membrane was then synthesized on ZIF-8 which was pre-grown on the α-alumina support. Single gas permeation of standing free zeolite T membrane showed a CO2/CH4 selectivity of 68 with CO2 and CH4 gas permeances of 6.08×10−8 and 0.09×10−8 mol/m2.s.Pa, respectively. On the other hand, the CO2/CH4 selectivity of the hybrid membrane was 3 folds as compared to standing free zeolite T membrane, giving the highest CO2/CH4 selectivity of 182 and the CO2 and CH4 gas permeances of 5.46×10−8 and 0.030×10−8 mol/m2.s.Pa, respectively. Both gas permeances of CO2 and CH4 increased with increasing feed pressure from 1 to 4bar with a slight decrease in the selectivity observed at the feed pressure of 4bar. While for the effect under increasing temperature, CO2 showed an increasing trend of its gas permeability from 5.46×10−8 to 6.12×10−8 mol/m2.s.Pa while CH4 gas permeability increased slightly from 0.03×10−8 to 0.042×10−8 mol/m2.s.Pa due to greater mobility of gas molecules promoted by higher temperature.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • Monitoring MCM-41 synthesis by X-ray mesostructure analysis
    • Abstract: Publication date: 1 September 2014
      Source:Microporous and Mesoporous Materials, Volume 195
      Author(s): Sergei D. Kirik , Vladimir A. Parfenov , Sergei M. Zharkov
      The electron density maps calculated from X-ray diffraction patterns of the mesoporous silica material МСМ-41 present averaged mesostructure images which in contrast to transmission electron microscopy (TEM) images are exceptionally repeating and represent the whole sample. It was shown that the averaged mesostructure parameters such as a unit cell parameter, a pore diameter, a wall width, a pore shape estimated from the X-ray powder diffraction data in combination with the continuous electron density function approach allow monitoring continuous set of the silica framework states at different stages of the material synthesis. The mentioned technique supplemented by N2-adsorption measurements and transmission electron microscopy was applied for consideration of the МСМ-41 hydrothermal stability. Attention has been given to the variations of the synthesis conditions affecting the hydrothermal stability, in particular the maintaining the basicity of the synthesis solution as well the substitution of the synthesis solution with water or a salt solution at hydrothermal treatment. The averaged pore shape was observed to be changed from cylindrical to hexagonal-prismatic form. The observed wall thickness was in the range from 0.75 to 1.25nm. The competition of silica polycondensation and surface hydrolysis was shown to be responsible for the variety of framework geometry and hydrothermal stability. It has been established that the pore diameter increases generally due to the osmotic pressure of water. If the pores acquire the average prismatic hexagonal shape, the sample has low hydrothermal stability. Under the conditions favorable for the polycondensation the pores have averaged cylindrical shape and material demonstrates higher hydrothermal stability. Cooperative mechanism of mesostructure destruction under hydrothermal conditions was observed using TEM data and was discussed in connection with irregular polycondensation.
      Graphical abstract image

      PubDate: 2014-06-14T14:57:01Z
       
  • Molecular dynamics study of water and ions transport in nano-pore of
           layered structure: A case study of tobermorite
    • Abstract: Publication date: 1 September 2014
      Source:Microporous and Mesoporous Materials, Volume 195
      Author(s): Dongshuai Hou , Zongjin Li
      Water and ions transport in the cement hydrate determines the durability of cementitious material. Due to the structural similarity, tobermorite, an important mineral analogue of the main phase of cement hydrate, was used to investigate transport behaviour at the molecular level. In this study, the structural and dynamical properties of the water/ions and the tobermorite interface were studied by the molecular dynamics (MD) simulation method. On the (001) surface of tobermorite, water molecules diffusing in the channel between the silicate chains demonstrate a number of structural water features: large density, good orientation preference, ordered interfacial organization and low diffusion rate. The dipole vector of type 1 water molecules point upwards due to the attraction from the calcium sheet, while type 2 water molecules turn downwards due to the restrained H-bonds donated from ONB atoms in the silicate chains. The stable H-bonds connected with ONB in the silicate chains restrict the mobility of the channel water molecules. The significant reduction of the diffusion coefficient matches well with the experimental results obtained by NMR, QENS and PCFR techniques. With increasing distance from the channel, the structural and dynamical behavior of the water molecules vary and gradually translate into bulk water properties at distances of 10–15Å from the liquid–solid interface. In the respect of the ions and tobermorite interaction, there is Cl− repulsion and Ca2+ adsorption from the surface. In addition, in simulation time longer than 1ns, Cl− can diffuse to the surficial Ca2+ and forms the unstable Ca-Cl cluster, which accelerates the desorption of the surface Ca atoms.
      Graphical abstract image

      PubDate: 2014-06-14T14:57:01Z
       
  • Facile synthesis of biocompatible superparamagnetic mesoporous
           nanoparticles for imageable drug delivery
    • Abstract: Publication date: 1 September 2014
      Source:Microporous and Mesoporous Materials, Volume 195
      Author(s): Tuomo Nissinen , Simo Näkki , Mika Latikka , Markku Heinonen , Timo Liimatainen , Wujun Xu , Robin H.A. Ras , Olli Gröhn , Joakim Riikonen , Vesa-Pekka Lehto
      Superparamagnetic mesoporous silicon nanoparticles have a huge potential in drug delivery and diagnostics, i.e., in theranostics. These particles can carry high drug payloads, they can be targeted by external magnetic fields, they can be imaged by magnetic resonance imaging and they are biocompatible. In the present study, we demonstrate a fast and simple synthesis procedure to produce superparamagnetic mesoporous nanoparticles by precipitating iron oxide nanocrystals inside the pores of porous silicon. Subsequently, polyethylene glycol molecules with two different molecular sizes were conjugated onto the external surfaces of the composite nanoparticles to improve the colloidal stability of the suspension without compromising the magnetic properties of the composite. The developed nanoparticles possessed many advantageous properties such as superparamagnetic behavior, high T 2 relaxivity, high pore volume and modifiable surface chemistry. In addition, the present method is more straightforward and versatile than the previous methods published, preserving the pore volume larger and accessible for high drug loadings.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • Hierarchical porous carbons by liquid phase impregnation of zeolite
           templates with lignin solution
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): M.J. Valero-Romero , E.M. Márquez-Franco , J. Bedia , J. Rodríguez-Mirasol , T. Cordero
      Templated carbon materials (TCs) with hierarchical pore structure were obtained by liquid phase impregnation of different zeolite templates using Alcell lignin solutions as carbon precursor. The effect of synthesis conditions such as templating mixture (lignin/zeolite), carbonization temperature (500, 700 and 900°C) and of zeolite framework on the structural and chemical properties of the resultant carbons was analyzed. The main original aspect of this work is the use of Alcell lignin as carbon precursor, a low-cost co-product derived from the papermaking industry, to obtain porous carbon materials with different pore size distribution, depending on the inorganic template used. Microporosity is developed from both the replication of the hard template and the carbonization of lignin, whereas mesoporosity can be adjusted by and adequate selection of the hard template and infiltration conditions. The TCs present interesting surface chemistry features, with a relatively high amount of nitrogen and oxygen stable surface groups, such as pyrrolic and pyridinic and hydroxyl and carbonyl type, respectively, which seem to have been transferred from the surface ammonia ions and oxygen of the zeolite template to the carbon materials during the synthesis. The hydroxyl groups seem to be responsible of the relatively high Brönsted acidity of the TCs.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • Measurements of water vapour sorption isotherms for RD silica gel,
           AQSOA-Z01, AQSOA-Z02, AQSOA-Z05 and CECA zeolite 3A
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): M.J. Goldsworthy
      The water vapour adsorption isotherms of RD silica gel, AQSOA-Z01, AQSOA-Z02, AQSOA-Z05 and CECA zeolite 3A are measured for temperatures between 20°C and 160°C and vapour partial pressures between 1 and 500mbar. The measurements were fit to a theoretical isotherm function and for some materials the RMS deviation was less than 5%. Since others had a poorer theoretical fit, all data was also fit to spline functions for use in numerical simulations. The variation of isosteric heats of adsorption as a function of uptake, calculated using a least squares fitting approach, are compared over a range of uptake values for each adsorbent. The heats of adsorption were between 1 and 1.6 times the heat of vaporisation for uptake values above 10% of the maximum uptake for each adsorbent. The AQSOA adsorbents display Type IV isotherm shapes and the silica gel and 3A zeolite display Type I shapes. The sorption hysteresis is investigated for the AQSOA adsorbents at a selected temperature. These adsorbents displayed a small degree of hysteresis with an H1 type behaviour.
      Graphical abstract image

      PubDate: 2014-06-14T14:57:01Z
       
  • Editorial Board
    • Abstract: Publication date: 1 September 2014
      Source:Microporous and Mesoporous Materials, Volume 195




      PubDate: 2014-06-14T14:57:01Z
       
  • Corrigendum to “Characterization of multi-walled carbon nanotube
           dispersion in resorcinol–formaldehyde aerogels” [Micropor.
           Mesopor. Mater. 184 (2014) 97–104]
    • Abstract: Publication date: 1 September 2014
      Source:Microporous and Mesoporous Materials, Volume 195
      Author(s): Majid Haghgoo , Ali Akbar Yousefi , Mohammad Jalal Zohouriaan Mehr , Alain Celzard , Vanessa Fierro , Alexandre F. Léonard , Angélique Léonard , Nathalie Job



      PubDate: 2014-06-14T14:57:01Z
       
  • Ruthenium(III) ion-exchanged zeolite Y as highly active and reusable
           catalyst in decomposition of nitrous oxide to sole nitrogen and oxygen
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Pelin Edinç Cürdaneli , Saim Özkar
      Ruthenium(III) ion-exchanged zeolite Y, prepared by ion exchange of Ru+3 ions with the extra framework Na+ cations in zeolite Y with a Si/Al ratio of 2.5, is employed to catalyze the decomposition of nitrous oxide to nitrogen and oxygen. Catalytic activity of ruthenium(III) ion-exchanged zeolite Y is studied in the decomposition of nitrous oxide to nitrogen and oxygen depending on the ruthenium loading of zeolite and flow rate of nitrous oxide helium mixture in a continuous flow vertical reactor. The results collected reveal that ruthenium(III) ion-exchange zeolite with a ruthenium loading of 3.98wt.% is highly active, long-lived, and reusable catalyst providing 100% conversion of nitrous oxide to sole nitrogen and oxygen at 350°C without any side reaction. This catalyst can be bottled under ambient conditions and repeatedly used in successive runs of nitrous oxide decomposition for up to 5months without significant loss in activity. Intrazeolite ruthenium(0) nanoclusters are slightly less active than the ruthenium(III) ion-exchanged zeolite Y in decomposition of nitrous oxide, which might be attributed to the migration of ruthenium(0) to the external surface before oxidation at high temperature. The other two metals of Group 8, iron(III) and osmium(III) ion-exchanged zeolite Y do not show activity as high as that of ruthenium(III) ion-exchanged zeolite Y in the same reaction.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • AIE luminogen functionalized mesoporous silica nanoparticles as efficient
           fluorescent sensor for explosives detection in water
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Chuanlong Miao , Dongdong Li , Yuping Zhang , Jihong Yu , Ruren Xu
      The aggregation-induced emission (AIE) luminogen functionalized mesoporous silica nanoparticles (MSNs) were prepared via post-grafting 1,2-bis[4-(bromomethyl)phenyl]-1,2-diphenylethene (TPE-MB) on 3-aminopropyltriethoxysilane modified MSNs. The obtained materials combine the unique properties of the AIE luminogen and porous materials, and their emission wavelength can be changed from 467 to 527nm by loading different amount of AIE molecules, showing an obvious red shift from blue light to yellow light. Such materials with well dispersibility in water are used as an efficient fluorescent sensor for the detection of explosives, including picric acid (PA), 4-nitrotoluene (4-NT), nitrobenzene (NB) in water. The obtained materials can be recycled by simply washing with proper solvents. The high sensitivity, increased chemical stability and recyclability of the AIE luminogen functionalized mesoporous silica nanoparticles promise that they can be used as an excellent fluorescence probe for future practical applications in explosives detection.
      Graphical abstract image

      PubDate: 2014-06-14T14:57:01Z
       
  • Morphological investigation of anodized TiO2 nanotubes fabricated using
           different voltage conditions
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Tae-Ho Kim , Jae-Wook Lee , Byung-Sung Kim , Hyeongcheol Cha , Yoon-Chae Nah
      The morphology of TiO2 nanotube layers fabricated by electrochemical anodization in an ethylene glycol solution containing 0.5wt% NH4F was investigated as a function of several voltage conditions. The effects of voltage sweep rate, retention time, and initial sweep voltage on the surface pore structure and tube length were observed in detail by scanning electron microscopy (SEM). It was clearly seen that worm-like porous structures on the TiO2 nanotube layers were formed during the voltage sweep process. These porous structures changed to round-shaped individual pores with longer tubular layers under constant voltage conditions. The initial sweep voltage also affected the pore size, even when the same final voltage was applied. These findings indicate that voltage conditions are very important factors in determining the surface and layer structure of anodized TiO2 nanotubes.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • A facile approach for the tunable wormlike or ordered pore morphology of
           mesoporous silica: Effect of catalyst types and polyethylene glycol
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Sun-Mou Lai , Hui-Yu Lai , Mu-Yu Chou
      Two different basic catalysts, NaOH and NH4OH, to the formation of mesoporous silica with completely different pore morphology at the same mole concentration with or without polyethylene glycol (PEG) were investigated. NaOH catalyzed system seemed to have a more ordered structure and larger particle size than NH4OH catalyzed system. The addition of PEG tended to promote the charge matching probability for silicate oligomers and micelles, which resulted in the more ordered pore morphology for NH4OH system. With increased ammonia concentrations, the pore morphology of disordered wormlike structure was transformed into ordered MCM-41 type mesoporous structure with particle dimension in a few tenths of nanometer to hundred nanometer. With the addition of PEG, at low ammonia concentration, the mesoporous pores became more orderly arranged as well. However, the effect of PEG on the pore and particle morphology of the NaOH catalyzed system was less evident than that of the NH4OH system. The catalyst types were also investigated at the same pH to contrast the significance of catalyst effect on the preparation of mesoporous silica, which was often neglected in the literature. NaOH catalyzed system still indicated a more ordered wormlike structure and slightly larger particle size than NH4OH catalyzed system. The XRD (X-ray diffraction) results and N2 adsorption–desorption isotherms were in agreement with the TEM (Transmission electron microscope) morphology. The significance of two different catalysts with the addition of PEG in tuning pore morphology was justified.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • Para-selective methylation of toluene with methanol over nano-sized ZSM-5
           catalysts: Synergistic effects of surface modifications with SiO2, P2O5
           and MgO
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Wei Tan , Min Liu , Yan Zhao , Keke Hou , Hongyu Wu , Anfeng Zhang , Haiou Liu , Yiren Wang , Chunshan Song , Xinwen Guo
      The nano-sized ZSM-5 catalysts were modified by surface coating with SiO2, P2O5, MgO and their combinations; the catalytic properties were investigated in the shape-selective methylation of toluene with methanol. The catalysts were characterized by XRD, XRF, N2 adsorption–desorption, temperature programmed desorption of ammonia (NH3-TPD), Fourier-transform infrared spectra of adsorbed pyridine/2,6-di-tert-butylpyridine, and adsorption of n-hexane/cyclohexane. The passivation of Lewis acid sites occurs prior to that of the Brönsted acid sites over ZSM-5 modified by SiO2, while P2O5 or MgO preferentially neutralizes the Brönsted acid sites of ZSM-5. The deposition of MgO is more efficient in passivating the acid sites and narrowing the pore openings, compared to SiO2 or P2O5 modification with the same oxide content (<9wt%). The single modification could not completely passivate the external surface acid sites and simultaneously narrow the pore openings to a proper extent; so the selectivity to para-xylene does not exceed 90% even at the highest oxide loading. The multiple modification by SiO2, P2O5 and MgO, with a suitable sequence can efficiently eliminate external surface acid sites, and simultaneously narrow the pore openings, which led to a higher para-selectivity (∼98%). The combined modification with SiO2, P2O5 and MgO in a proper sequence can lead to a synergistic effect for tailoring the acid property and pore mouth of the catalyst, thus enhancing the para-selectivity to ∼98% and improving catalytic stability, as demonstrated by flow test for 1000h on stream.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • A new hierarchical porous zirconium phosphate membrane and its adsorption
           properties
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): Abubaker Abutartour , Yunjie Jia , Lotfia El Majdoub , Qinghong Xu
      A hierarchical porous zirconium phosphate membrane was prepared from bis(hexamethylenetriaminepenta(methylenephosphonic acid)), ZrOCl2·8H2O, SiF4 and hexadecyl trimethyl ammonium bromide. The membrane contains macropores of 200nm in diameter, and mesopores of 19.2nm in diameter. The membranes pores were bridged and limited by (–Si–O–) n edges. The porous membrane exhibited high efficiency in removing Pb2+ and Cu2+ from wastewater.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
  • Chemical activation of tannin-based hydrogels by soaking in KOH and NaOH
           solutions
    • Abstract: Publication date: 15 September 2014
      Source:Microporous and Mesoporous Materials, Volume 196
      Author(s): A. Szczurek , G. Amaral-Labat , V. Fierro , A. Pizzi , A. Celzard
      Tannin–formaldehyde hydrogels prepared at different pH were chemically activated in an unusual way. Instead of impregnating dry organic or carbon gels, fresh hydrogels were indeed used as such, i.e. in the wet state. The water contained in their porosity was simply exchanged by NaOH or KOH aqueous solutions having various concentrations. The impregnated gels were thus vacuum-dried, leading to xerogels in which the alkali was extremely well dispersed inside, and then heat-treated at 750°C. The resultant activated carbon gels were characterised, and the effects of initial pH, concentration and nature of the hydroxide were discussed. The present way of activating the gels produced homogeneous materials with a foam-like structure presenting high surface areas and micropore volumes even when very low hydroxide amounts were used.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:57:01Z
       
 
 
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