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Journal Cover Microporous and Mesoporous Materials
  [SJR: 1.243]   [H-I: 116]   [6 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1387-1811
   Published by Elsevier Homepage  [3039 journals]
  • Synthesis characterization and performance evaluation of ionic liquid
           immobilized SBA-15 /quaternised polysulfone composite membrane for
           alkaline fuel cell
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Vijayakumar Elumalai, Sangeetha Dharmalingam
      1-Methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride, an imidazolium based ionic liquid, was synthesized and chemically grafted onto the synthesized mesoporous silica (SBA-15), resulting in a mesoporous solid (IL-SBA-15) with ion-exchange properties. The prepared IL- SBA-15 was characterized by FT-IR, solid state CP/MAS 13C NMR, solid state CP/MAS 29Si NMR, BET, XRD and TEM. Composite membranes with high ion exchange capacity (IEC) were then prepared by incorporating IL-SBA-15 into the quaternary polysulfone (QPSU) in different weight percentages (1–4%). The morphology and crystalline nature of the membranes were analyzed by SEM and XRD respectively. The membrane properties such as water uptake, IEC and hydroxyl conductivity were studied for its suitability in Anion Exchange Membrane Fuel Cell(AEMFC). The prepared membranes were tested in an in-house built AEMFC of 25 cm2 electrode area with platinum anode and silver cathode. 3 wt% IL-SBA-15 containing composite membrane showed a maximum power density of 278 mW/cm2 at 60 °C. The results suggest that these composite membranes have the potential to be used as an electrolyte in AEMFC.
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      PubDate: 2016-09-20T13:20:38Z
       
  • Behavior of Lewis and Brönsted surface acidity featured by Ag, Au, Ce,
           La, Fe, Mn, Pd, Pt, V and W decorated on protonated titanate nanotubes
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): R. Camposeco, S. Castillo, Isidro Mejia-Centeno, J. Navarrete, V. Rodriguez-Gonzalez
      Ag, Au, Ce, La, Fe, Mn, Pd, Pt, V and W nanoparticles were decorated on the surface of titanate nanotubes obtained by hydrothermal treatment. Likewise, the titanate nanotubes with the incorporated active transition, precious and rare earth metals were characterized by XRD, HRTEM, and BET. FTIR-pyridine and UV–Vis were used in order to quantify the acid sites present in different metal catalysts, the main goal of this work. Metal nanoparticles were incorporated in-situ on the surface of the titanate nanotubes by the hydrothermal treatment. The average sizes displayed by the metal nanoparticles were between 1 and 5 nm, finding highly uniform dispersion for all the metals. As a result of the metal incorporation, the acidity of each catalytic system was tuned specially, increasing the number of Brönsted and Lewis sites, which modified significantly the total surface acidity of the 1-D titanate nanotubes.
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      PubDate: 2016-09-20T13:20:38Z
       
  • Optimal synthesis of amino-functionalized mesoporous silicas for the
           adsorption of heavy metal ions
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Shiyou Hao, Antonio Verlotta, Paolo Aprea, Francesco Pepe, Domenico Caputo, Weidong Zhu
      Amino-functionalized mesoporous silicas (AFMS) were synthesized by a neutralization route using the anionic surfactant dodecanoic acid (DAA) as structure-directing agent (SDA), aminopropyltrimethoxysilane (APTMS) as co-structure-directing agent (CSDA), and tetraethoxysilane (TEOS) as silicon source. The synthesis parameters, which affect the structural properties and the amino loadings of the resultant AFMS, were optimized. Various techniques, such as FT-IR, XRD, N2 adsorption-desorption, and TEM, were used to characterize the synthesized AFMS. The selective removal of Cu2+, Pb2+, Cd2+, and Zn2+ from aqueous solutions in single-, binary-, ternary-, and quaternary-component systems by the synthesized AFMS was thoroughly investigated. The measured single-component adsorption isotherms of Cu2+, Pb2+, Cd2+, and Zn2+ on the AFMS optimally synthesized can be well described by the Sips model, in which the extracted adsorption capacities are 2.34, 2.86, 1.71, and 1.36 mmol/g (0.149, 0.593, 0.192, and 0.089 g/g) for Cu2+, Pb2+, Cd2+, and Zn2+, respectively, higher than those on other adsorbents reported in the literature. Furthermore, Pb2+ and Cu2+ can be more selectively removed by the synthesized adsorbent, compared to Cd2+ and Zn2+, confirmed by the results on the multi-component adsorption.
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      PubDate: 2016-09-20T13:20:38Z
       
  • Post-synthesis bromination of benzene bridged PMO as a way to create a
           high potential hybrid material
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): W. Huybrechts, G. Mali, P. Kuśtrowski, T. Willhammar, M. Mertens, S. Bals, P. Van Der Voort, P. Cool
      Periodic mesoporous organosilicas provide the best of two worlds: the strength and porosity of an inorganic framework combined with the infinite possibilities created by the organic bridging unit. In this work we focus on post-synthetical modification of benzene bridged PMO, in order to create bromobenzene PMO. In the past, this proved to be very challenging due to unwanted structural deterioration. However, now we have found a way to brominate this material whilst keeping the structure intact. In-depth structural analysis by solid state NMR and XPS shows both vast progress over previous attempts as well as potential for improvement.
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      PubDate: 2016-09-20T13:20:38Z
       
  • Selective dynamic separation of Xe and Kr in Co-MOF-74 through strong
           binding strength between Xe atom and unsaturated Co2+ site
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Seung-Joon Lee, Ki Chul Kim, Tae-Ung Yoon, Min-Bum Kim, Youn-Sang Bae
      From pure experimental isotherms and ideal adsorbed solution theory (IAST), we confirmed a recent report that Co-MOF-74 provides the highest Xe uptake as well as the highest Xe/Kr selectivity among the three M-MOF-74 series (M = Co, Mg, and Zn). From breakthrough experiments, we then showed the first demonstration of the potential of Co-MOF-74 for Xe/Kr separations under mixture flow conditions. Remarkably, the experimental breakthrough curves for three consecutive cycles are essentially unchanged even if the column was regenerated under helium flows at room temperature between each cycle. Isosteric heat of adsorption (Qst) for Xe, adsorbed Xe molecules per metal, and binding strengths and electronic density of states (DOS) analyses from first principles calculations all indicate that unsaturated Co2+ sites attract Xe more strongly than do unsaturated Mg2+ and Zn2+ sites. The DOS analyses show that the d orbital of the Co2+ is the main contributors for the strong interaction. These results suggest that Co-MOF-74 is a promising adsorbent for separations of Xe and Kr.
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      PubDate: 2016-09-20T13:20:38Z
       
  • Mesoporous C18-bonded ethyl-bridged organic-inorganic hybrid silica: A
           facile one-pot synthesis and liquid chromatographic performance
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Xiu-Yun Yue, Dan-Dan Jiang, Lun Shu, Sha Chen, Zuo-Ren Nie, Qi Wei, Su-Ping Cui, Qun-Yan Li
      A facile one-pot method was used to prepare C18-bonded ethyl-bridged organic-inorganic hybrid silica via the co-hydrolysis and condensation of 1,2-bis(triethoxysilyl)ethane (BTESE) and octadecyltriethoxysilane (ODTES) under basic condition. The pore structure, chemical composition and liquid chromatographic performance of the obtained materials were investigated. The sample MSS-0.08, prepared with an ODTES/BTESE mole ratio of 0.08, exhibits a desirable mesoporous structure with a surface area of 352.82 m2 g−1, a pore volume of 0.21 cm3 g−1 and an average pore size of 3.72 nm and shows a hydrophobic property with a water contact angle of 139.8° ± 0.1°. When used as stationary phase for high performance liquid chromatography (HPLC), MSS-0.08 realizes a baseline separation for a mixture of uracil, pyridine, phenol, 1-naphthylamine and naphthalene and exhibits a high degree of resistance to alkali at elevated temperature.
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      PubDate: 2016-09-20T13:20:38Z
       
  • Amine hybrid zirconia/silica composite aerogel for low-concentration CO2
           capture
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Yong Kong, Xiaodong Shen, Sheng Cui
      Amine hybrid zirconia/silica composite aerogel (AHZSA) was prepared via a simple, low-cost and environment-friendly method, i.e. one-pot sol-gel process along with supercritical drying. The pore strucutre, morphology, surface chemistry and CO2 capture performances of AHZSA were investigated. AHZSA possesses microstructure of the typical aerogels and has a large amount of macropores, which favors the gas diffusion in the pore space. The amine loading and surface amine content of AHZSA is 8.18 and 9.60 mmol/g, respectively. The CO2 adsorption capacity of AHZSA at 30, 50, 70 and 90 °C in the absence of water vapor is 2.70, 2.10, 2.00 and 1.48 mmol/g, respectively. The CO2 adsorption capacity at 30 °C increases to 3.40 mmol/g after the introduction of water vapor. Adsorption and desorption kinetics of AHZSA suggest that AHZSA is dynamic for low-concentration CO2 capture. The adsorbent preparation method is inspiring and the resulting adsorbent is capable, dynamic, and regenerable for low-concentration CO2 capture.
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      PubDate: 2016-09-20T13:20:38Z
       
  • Aluminum doped mesoporous silica SBA-15 for the removal of remazol yellow
           dye from water
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Khalid Ahmed, Fozia Rehman, Cleo T.G.V.M.T. Pires, Abdur Rahim, Ana L. Santos, Claudio Airoldi
      Aluminum doped mesoporous silica SBA-15 was synthesized and characterized using nuclear magnetic resonance spectroscopy, nitrogen adsorption, X-rays diffraction, thermogravimetry, scanning and transmission electron microscopy. The modified mesoporous silicas [Al]SBA-15 and [2Al]SBA-15 showed high sorption capacities of remazol yellow dye (RY) of about 0.971 and 0.821 mmol g−1 respectively, when compared to original precursor silica SBA-15 (0.725 mmol g−1). The sorption kinetic of RY dye was slow and the equilibrium reached in 4–5 h. The effect of pH on sorption process was studied at room temperature and maximum dye sorption was achieved at pH 7. Kinetic data of RY sorption onto mesoporous silica was best fitted to second-order kinetic model. The equilibrium data were fitted to the Langmuir, Freundlich and Sips isotherm models. The obtained results suggest that doped mesoporous silica can be an efficient, cheap sorbent and convenient method for the removal of reactive dyes such a RY from industrial effluents.
      Graphical abstract image

      PubDate: 2016-09-12T13:12:04Z
       
  • Shell-like hierarchical porous carbons for high-rate performance
           supercapacitors
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Xiaojun He, Zide Liu, Hao Ma, Nan Zhang, Moxin Yu, Mingbo Wu
      Shell-like hierarchical porous carbons (SHPCs) were prepared from petroleum pitch by a nano-ZnO-template strategy coupled with in-situ KOH activation technique. The as-made SHPCs feature interconnected thin carbon shells and abundant short hierarchical pores, which are favorable for both the rapid transfer of electrons and ions during the charge-discharge process. The SHPCs made under optimal conditions show a specific surface area up to 2646 m2 g−1. As electrodes for supercapacitors, SHPCs exhibit a high specific capacitance up to 296 F g−1 at 0.05 A g−1 in 6 M KOH electrolyte, good rate performance remaining at 237 F g−1 at 20 A g−1 and a good cycle stability with over 96.5% capacitance retention after 5000 cycles. This work suggests a facile strategy for high-efficiency synthesis of SHPCs from petroleum pitch as electrode materials for supercapacitors and other energy stotage devices.
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      PubDate: 2016-09-12T13:12:04Z
       
  • Aberration-corrected STEM analysis of the RHO family of zeolites with
           embedded isoreticular structures
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Alvaro Mayoral, Jung Gi Min, Suk Bong Hong
      Spherical aberration (Cs) corrected STEM has proved to be an excellent approach for obtaining high-resolution images of beam sensitive materials. Using this analytical method, for the first time, we were able to image the structural expansion of four members of the RHO family of embedded isoreticular zeolites along [001] orientation and thus to identify the main constituent cages, conforming their structures.
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      PubDate: 2016-09-12T13:12:04Z
       
  • Fly ash as raw material for the synthesis of zeolite-encapsulated
           porphyrazine and metallo porphyrazine tetrapyrrolic macrocycles
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Sandra Belviso, Francesco Cavalcante, Antonio Lettino, Pietro Ragone, Claudia Belviso
      In this work, free-base thioethyl-porphyrazine and its copper (II) complex were encapsulated into zeolites during their synthesis by hydrothermal method at low incubation temperature (45 °C and 60 °C) using fly ash as raw material. The zeolite-included tetrapyrroles, H2(OESPz)-Zeo and Cu(OESPz)-Zeo, were characterized by XRD, SEM, TG/DTA and UV–Vis. X-ray diffraction patterns show that large amount of zeolite A and sodalite formed in H2(OESPz)-Zeo and Cu(OESPz)-Zeo, respectively whereas thermal analysis as well as UV–Vis spectroscopic investigation reveal the presence of tetrapyrroles inside newly-formed zeolitic solid matrix. The mechanism of zeolite synthesis around organic compounds to form “ship in a bottle” complexes is displayed by SEM analysis.
      Graphical abstract image

      PubDate: 2016-09-12T13:12:04Z
       
  • Improved stability in SBA-15 mesoporous materials as catalysts for
           photo-degradation processes
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Verónica R. Elías, Gabriel O. Ferrero, Rafael G. Oliveira, Griselda A. Eimer
      SBA-15 materials were modified with Cr, Ni and Fe and characterized by ICP, SAXS, XRD, N2 adsorption, TPR and UV–Vis DRS. Their photo-catalytic activity was evaluated for the degradation of Acid Orange 7 (AO7) in aqueous suspensions irradiated by artificial UV–Vis light. The results showed that the Cr-modified catalyst exhibited the highest activity. The presence of Cr6+ highly dispersed on the internal surface of the SBA-15 structure would be responsible for this observed behavior. Then, when TiO2 was loaded on this solid, the photo-activity was increased due to a heterojunction effect between the two metals. Moreover, the TiO2 cover resulted in the Cr species protection leading to a notable decrease of the Cr leaching into the reaction medium. In addition, comparing with the already reported results for modified MCM-41 catalysts, the solid synthesized here allowed achieving the solution biodegradability in shorter irradiation periods and could be re-used even after four cycles without loss of activity. Thus, the high performance of this material leads to make it a very promising photo-catalyst for pre-treatment of recalcitrant contaminants present in aqueous effluents.
      Graphical abstract image

      PubDate: 2016-09-12T13:12:04Z
       
  • Improvement of catalytic activity over Cu--Fe modified Al-rich Beta
           catalyst for the selective catalytic reduction of NOx with NH3
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Li Xu, Chuan Shi, Bingbing Chen, Qi Zhao, Yongjun Zhu, Hermann Gies, Feng-Shou Xiao, Dirk De Vos, Toshiyuki Yokoi, Xinhe Bao, Ute Kolb, Mathias Feyen, Stefan Maurer, Ahmad Moini, Ulrich Müller, Weiping Zhang
      Copper and iron bimetal modified Al-rich Beta zeolites from template-free synthesis were prepared for selective catalytic reduction (SCR) of NO x with NH3 in exhaust gas streams. Comparing to the Cu-based and Fe-based mono-component Beta catalysts, Cu(3.0)-Fe(1.3)-Beta bi-component catalyst shows better low-temperature activity and wider reaction-temperature window. Over 80% of NO conversion can be achieved at the temperature region of 125–500 °C. Due to the synergistic effect of copper and iron evidenced by XRD, UV–Vis–NIR, EPR and XPS measurements, the dispersion state of active components as well as the ratio of Cu2+/Cu+ and Fe3+/Fe2+ were improved over Cu(3.0)-Fe(1.3)-Beta. Isolated Cu2+ and Fe3+ ions which located at the exchange sites could be the active species at the low-temperature region, while FeO x cluster species may be more important to the high-temperature activity. During the test of sulfur resistance, Fe-containing samples including Cu(3.0)-Fe(1.3)-Beta and Fe(2.7)-Beta-4 present better performance compared to Cu(4.1)-Beta-4. Deactivation of Cu-based catalyst is attributed to the easier deposition of sulfates over the surface according to the results of TGA coupled with TPD experiments.
      Graphical abstract image

      PubDate: 2016-09-12T13:12:04Z
       
  • Rapid synthesis of ZSM-22 zeolites using imidazolium-based ionic liquids
           as OSDAs in fluoride media
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Peng Lu, Lei Chen, Yanfei Zhang, Yangyang Yuan, Li Xu, Xiaomin Zhang, Lei Xu
      Developing facile and rapid synthesis route for zeolites is becoming increasingly desirable due to economical considerations. Here, we report on the one-pot rapid synthesis of ZSM-22 in fluoride media using imidazolium-based ionic liquids as organic structure directing agents (OSDAs). Pure-silica and aluminum-containing ZSM-22 zeolites were rapidly synthesized in 24 h using 1, 3-alkylimidazolium ionic liquids as OSDAs in various crystallization conditions. The crystallization time of present synthesis route surpasses most of the currently reported methods. Different synthesis parameters were investigated and the optimum synthetic conditions were refined. The XRD and SEM results showed that the products were highly crystalline pure ZSM-22 zeolites with a long rod shape. 29Si MAS NMR indicated defect-free zeolite framework was achieved thanks to the using of fluoride as mineralizer. 27Al MAS NMR verified the Al was existed in tetrahedrally coordinated states indicating its successful incorporation into the zeolitic framework. The present work demonstrates a possible and fast synthesis route of ZSM-22 and potential applications will be expected.
      Graphical abstract image

      PubDate: 2016-09-12T13:12:04Z
       
  • Influence of crystal topology and interior surface functionality of
           metal-organic frameworks on PFOA sorption performance
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Meng-Jia Chen, An-Chih Yang, Nan-Hui Wang, Hao-Che Chiu, Yung-Lin Li, Dun-Yen Kang, Shang-Lien Lo
      Perfluorooctanoic acid (PFOA) is an emerging persistent organic pollutant. This paper reports on the use of metal-organic frameworks (MOFs) as sorbents for the removal of PFOA from aqueous solutions. Specifically, we investigated the effects of topology and surface functionality on PFOA sorption and the uptake kinetics of MOF materials. Zeolitic imidazolate framework-7 (ZIF-7) and ZIF-8 share the same topology but differ in their organic ligands. ZIF-8 and ZIF-L comprise the same metal ion and organic ligand differ in their crystal structure. ZIF-8 and ZIF-L were used to evaluate the effects of MOF topology on their effectiveness as PFOA sorbents. The PFOA sorption performance of ZIF-7, ZIF-8, and ZIF-L was then compared with the performance of two commercialized sorbents, zeolite 13X and activated carbon. ZIF-8 and ZIF-L were shown to outperform the two commercial sorbents and the PFOA sorption capacity and kinetics of ZIF-L are comparable to the benchmark values achieved for PFOA. It appears that the interlayer spacing within ZIF-L plays a key role in sorption performance by reducing the structural restrictions found in most three-dimensional porous materials and thereby allowing for the faster diffusion of PFOA. The discoveries in this work could assist in the development of guidelines for the design of new high-performance sorbents for small-molecule pollutants in aqueous phase.
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      PubDate: 2016-09-12T13:12:04Z
       
  • A review on the fabrication of zeolite and mesoporous inorganic nanofibers
           formation for catalytic applications
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Shaheen Fatima Anis, Abdullah Khalil, Saepurahman, Gnanapragasam Singaravel, Raed Hashaikeh
      Zeolites are microporous materials which are commonly used as catalysts in the petroleum refining industry. Due to increasing global demands for fuels and olefins, there has been a growing interest in synthesizing zeolites with better catalytic activity, selectivity, and lifetime. In this context, zeolite nanoparticles have been found to have higher catalytic activity as compared to their micro counterparts because of their greater surface area. Despite this advantage, zeolite nanoparticles have limitations in practical usage because of their unavoidable agglomeration. One approach to overcome this problem is to shape the zeolites in the nanofibers form. Among several reported routes to produce zeolite nanofibers, electrospinning carries a unique significance because of several advantages. Herein, we review the existing literature on the fabrication of zeolites nanofibers using the electrospinning technique. Owing to the relatively novel nature of this approach, fabrication of other materials related to zeolites such as mesoporous materials is also included for comparison. This review also highlights some basic characterization, reported catalytic performance, challenges and strategies in fabricating zeolite nanofibers.
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      PubDate: 2016-09-12T13:12:04Z
       
  • Stimuli-responsive mesoporous silica nanoparticles for cancer therapy: A
           review
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): André F. Moreira, Diana R. Dias, Ilídio J. Correia
      The application of nanocarriers as selective drug delivery platforms, as imaging or as diagnostic agents has been evaluated in several studies in the area of biomedicine, namely for cancer therapy. Such systems have the potential to perform a controlled and site-specific delivery of therapeutic agents leading to a reduction of side effects and, ultimately, to an improved therapeutic outcome. Among the different nanocarriers developed so far, mesoporous silica nanoparticles have attracted the attention of the scientific community for being applied as drug delivery systems that are capable of controlling, both in space and time, the drug release. In this review, the modifications performed, so far, on mesoporous silica nanoparticles to imprint them a stimulus responsive behavior (namely, pH, redox potential, adenosine triphosphate, enzyme or temperature) in order to allow their application in cancer therapy are highlighted.
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      PubDate: 2016-09-12T13:12:04Z
       
  • Optically transparent silver-loaded mesoporous thin film coating with
           long-lasting antibacterial activity
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Paolo Nicolas Catalano, Magdalena Pezzoni, Cristina Costa, Galo Juan de Avila Arturo Soler-Illia, Martin Gonzalo Bellino, Martin Federico Desimone
      Infectious diseases caused by microorganisms affect millions of people worldwide. In an effort to prevent infections induced by bacteria, a variety of antibacterial coatings have been designed. In this sense, the possibility to combine broad-range bactericidal agents such as silver and chemically and mechanically stable matrices such as mesoporous oxide thin films has been encouraging. In this study, titania–silica bilayer mesoporous thin film (MTF) coatings have been produced and loaded with silver species, and their bactericidal efficiency against Pseudomonas aeruginosa and Staphylococcus aureus was assessed over time. In this sense, coatings loaded with silver ions (MTF + Ag+) were analyzed in comparison with coatings confining silver nanoparticles (MTF + AgNP). EDS analysis revealed that both types of MTF coatings were loaded with high amounts of silver (MTF + Ag+ = 25%; MTF + AgNP = 34%). MTF + Ag+ showed extremely high bactericidal efficiency (percent reduction of 99.5 to >99.999) against both strains along 10 cycles of use, comparable to that observed with MTF + AgNP. Interestingly, silver release from both types of coatings was similar over the same testing period. However, contrary to MTF + AgNP, MTF + Ag+ have shown absolute optical transparency. This is relevant for any type of coating, as conservation of optical properties of the material surface where they are intended to be applied, is highly desirable. Moreover, the maximum silver ion sorption capacity of film coatings was 3 μg cm−2 and MTF + Ag+ were still loaded with silver after 10 cycles of use which indicates that the bactericidal effect could be extended beyond. These results spotlight the potentiality of MTF + Ag+ as antibacterial coatings for any ceramic and/or metallic surface with no alteration of optical and mechanical properties.
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      PubDate: 2016-09-12T13:12:04Z
       
  • Editorial Board
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235




      PubDate: 2016-09-08T06:28:06Z
       
  • Synthesis and characterization of mesoporous CaCO3@PSS microspheres as a
           depot system for sustained Methylene Blue delivering
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): S.L. Yefimova, I.I. Bespalova, G.V. Grygorova, A.V. Sorokin, P.V. Mateychenko, X.Q. Cui, Yu. V. Malyukin
      Polystyrene sulfonate (PSS)-doped calcium carbonate microparticles (CaCO3@PSS) were synthesized and used for the encapsulation of Methylene Blue (MB). SEM and TEM images suggest the formation of spherical particles with about 2 μm diameters and raspberry-like structure. Brunauer–Emmett–Teller method was used to analyze the specific surface area and the pore size distribution of the CaCO3@PSS microparticles. The sorption of MB from aqueous solution onto CaCO3@PSS microspheres was studied and equilibrium isotherm determined. A physisorption process was indicated by the values of sorption energy (B D ) 2.39 × 10−7 mol2/J2, mean free energy (E D ) 1.5 kJ/mol and heat of sorption (B) 28.8 J/mol estimated from the Dubinin-Radushkevich and Temkin isotherms. The Langmuir model precisely describes the isotherm and the maximum adsorption capacity was 149.3 mg/g indicating homogeneous nature of adsorption sites and monolayer coverage of MB on the CaCO3@PSS microparticle inner and outer surfaces. The pseudo-second-order model can better describe the adsorption kinetics with a maximum adsorption attained within 5 h. The intra-particle diffusion process was identified as the main mechanism controlling the rate of the dye sorption. The MB release from CaCO3@PSS microspheres was found to be pH-responsive. The presence of negatively charged PSS− groups in pores of CaCO3@PSS microparticles prevents the initial burst release of MB, decreasing the release rate of MB. The experimental results indicate high potential of CaCO3@PSS microspheres as carriers for encapsulation and controlled release of cationic dye molecules, such as photosensitizer MB, used in photodynamic therapy.
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      PubDate: 2016-09-08T06:28:06Z
       
  • Determination of micropore volume and external surface of zeolites
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Christoph Buttersack, Jens Möllmer, Jörg Hofmann, Roger Gläser
      Original and thermally degraded FAU type zeolites were characterized by nitrogen adsorption at 77 K and compared with isotherms for amorphous silica from literature. The isotherms were evaluated by the method of Remy and Poncelet which is an additive composition of the Dubinin-Radushkevich and the BET equation. Nonlinear fits typically generate two optimal values. One is attributed to very low, the other to very high values of the C-constants of the BET part. The conversion of the DR-isotherm to a set of Langmuir isotherms with different affinities shows that the low value is correct. For comparison all data were compared with those obtained by the t-plot method. The t-plot generally yields a less good fit with the experimental data, lower micropore volumes and deviating external surfaces, especially in the case of thermally degraded zeolites with an enhanced degree of mesopores. The entire isotherms from p/p o  = 0.5 to 0.98 are covered by an additive combination of the Dubinin-Radushkevich equation and the general Aranovich equation. That equation, however, fails for the determination of the external surface.
      Graphical abstract image

      PubDate: 2016-09-08T06:28:06Z
       
  • Size-controlled synthesis of MCM-49 zeolite from NaX for liquid-phase
           alkylation of benzene with ethylene
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Enhui Xing, Yanchun Shi, Wenhua Xie, Fengmei Zhang, Xuhong Mu, Xingtian Shu
      Size-controlled synthesis of MCM-49 zeolite (MWW, SiO2/Al2O3 > 20) was achieved in presence of parent zeolite NaX (FAU, SiO2/Al2O3 = 2.5), hexamethyleneimine (HMI), NaOH and SiO2, with d6r as a common composite building unit between FAU (d6r and sod) and MWW (d6r and mel) structure. The samples prepared at different crystallization stages were characterized by XRD, SEM, 29Si/27Al/13C MAS NMR to investigate the intermediates during the direct zeolite-zeolite transformation from NaX to MCM-49. H-MCM-49 transformed from NaX has smaller and more regular MWW crystal sizes than conventional H-MCM-49. Also an increase in the acid sites determined by pyridine-FTIR was observed. A substantial improvement in both ethylene conversion and ethylbenzene selectivity was achieved over H-MCM-49 transformed from NaX because of smaller crystal sizes and more acid sites.
      Graphical abstract image

      PubDate: 2016-09-08T06:28:06Z
       
  • Adsorption equilibria of CO2 and small hydrocarbons in AEI-, CHA-, STT-,
           and RRO-type siliceous zeolites
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Trong D. Pham, Raul F. Lobo
      AEI, CHA, and STT siliceous zeolites and RUB-41 (RRO) were prepared with low concentration of internal silanols and were characterized by X-ray diffraction, N2 adsorption isotherms, electron microscopy, and 29Si MAS NMR spectroscopy. Adsorption isotherms of methane, ethylene, ethane, propylene, propane, and CO2 were measured volumetrically on siliceous zeolites AEI, CHA, RRO, and STT at various temperatures ranging from 273 K to 323 K up to a pressure of 101.3 kPa. The Clausius-Clapeyron equation was used to calculate the isosteric heats of adsorption. The amount adsorbed depends strongly on adsorbate polarizability in the low-pressure region, and on the adsorbent micropore volume in the high-pressure region. Adsorption entropy losses are independent of temperature and increase with increasing adsorption enthalpy. RRO showed the highest pure-component selectivity of CO2 over CH4, and potential for the separation of the natural gas mixtures; AEI, CHA, and RRO-type materials showed potential for the kinetic separation of propylene/propane.
      Graphical abstract image

      PubDate: 2016-09-08T06:28:06Z
       
  • Porous carbon nanosheets derived from Al-based MOFs for supercapacitors
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Yi Liu, Jiao Xu, Shucheng Liu
      In this work, we report preparation of porous carbon nanosheets (CNs) through carbonization of an Al-based metal-organic frameworks (DUT-5) at 700 °C under an inert gas atmosphere. The obtained CNs shows a two-dimensional (2D) nanostructure, with a high BET surface area (415.2 m2 g−1) and pore volume (0.99 cm3 g−1). The electrochemical performance of the as-synthesized CNs was evaluated in a three-electrode configuration with 6 M KOH electrolyte. The capacitance values are calculated to be 119, 100, 88, 84 and 80 F g−1, respectively, at current densities of 0.25, 0.5, 1, 2 and 3 A g−1. Finally, the symmetric supercapacitors (SCs) were fabricated by utilizing the CNs as the positive and negative electrode. The working voltage of the SCs can be extended to 1.5 V in 6 M KOH and achieved an energy density up to 3.0 Wh kg−1 at a power density of 1384 W kg−1, indicating the potential of assembled system in practical application.
      Graphical abstract image

      PubDate: 2016-09-08T06:28:06Z
       
  • Solid-state dealumination of zeolite Y: Structural characterization and
           acidity analysis by calorimetric measurements
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Luciana Diniz Borges, Julio Lemos de Macedo
      Zeolite Y was dealuminated in the solid-state at several degrees (5, 10, 15 and 20%) using (NH4)2SiF6 as dealumination agent. The materials were heated to 80, 100, 120, 140, 160, 180 and 200 °C to investigate the best temperature at which the samples retain their crystallinity and acidity. The solids obtained were characterized by XRD, FTIR, TG/DTG, XRF, 27Al and 29Si MAS NMR and N2 physisorption. They were also subjected to pyridine adsorption and calorimetric experiments. Structural and textural results showed that lower temperatures (80 and 100 °C) and smaller degrees of dealumination (5 and 10%) maintained the zeolite crystallinity and increased its specific surface area, microporosity and mesoporosity. The study of the materials acidity indicated the presence of Brønsted acid sites with different strength, hydrogen bonding sites and Lewis sites originated from acid leaching. The calorimetric measurements showed higher enthalpy values for some of the dealuminated materials than for the parent zeolite. It also evidenced an increase for the number of acid sites between −160 and −140 kJ mol−1 and a reduction for the other sites, between −140 and −80 kJ mol−1.
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      PubDate: 2016-09-08T06:28:06Z
       
  • Thermal stability of barrerite and Na-exchanged barrerite: An in situ
           single crystal X-ray diffraction study under dry conditions
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Georgia Cametti, Thomas Armbruster, Mariko Nagashima
      The thermal stability of barrerite (Na8.2K3.0Ca2.2Mg0.2Al17Si55O144·50H2O) from Kuiu Island, Alaska, was investigated from 25 °C to 500 °C by in situ single-crystal X-ray diffraction under dry conditions. Corresponding experiments were performed on Na-exchanged barrerite Na17Al17Si55O144·45H2O from the same locality. The natural sample showed a gradual transformation of the A phase with dehydration to the B phase associated with rupture of T-O-T links and formation of new connections. Though, the high temperature modification (phase D) was not observed in the studied temperature range. In contrast to natural barrerite (space group Amma), Na-exchanged barrerite was found to be monoclinic F2/m at room temperature and transformed to A2/m (same cell setting) with beginning dehydration at 50 °C. Its dehydration trend, monitored by unit-cell volume, corresponded to structural modifications observed for natural barrerite. The D phase of this sample was produced by ex situ experiments at 525 °C under ambient conditions. A new model for transformation from the disordered B phase to the ordered highly condensed D phase (space group A21 ma) is presented. In addition, the new in situ equilibrated single-crystal experiments are compared with dynamic X-ray powder diffraction studies.
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      PubDate: 2016-09-08T06:28:06Z
       
  • Synthesis and encapsulation of fluorescein in zeolite Y
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Małgorzata Łukarska, Aldona Jankowska, Jacek Gapiński, Samuel Valable, Clement Anfray, Benjamin Ménard, Svetlana Mintova, Stanisław Kowalak
      Fluorescein was entrapped inside FAU type zeolite (Y) by generating it from resorcinol and phthalic anhydride. Prior to the formation of fluorescein, zeolite Y was modified with various cations (H, Zn, Ce, Na, K). The modified zeolite acted as catalysts for the fluorescein Friedel–Crafts reaction synthesis, while at the same time it played a role of matrix for the stabilization and homogeneous dispersion of the guest molecules. The nature of the different cations influenced the content of fluorescein generated in the zeolite, and favoured the formation of some dye isomers (i.e. anion, dianion, cation or transition metal complex). The contribution of different fluorescein derivatives in the products was reflected in their absorption and fluorescence properties. The H-, Ce-, and Zn- containing Y zeolites revealed the highest content of fluorescein due to their distinct acid active sites. The composites with H- and ZnY zeolites indicated much higher fluorescence than that of the pristine fluorescein. Moreover, fluorescein in zeolite Y matrices did not show any photobleaching under continuous illumination (λ = 730 nm, in a two-photon experiment for 180 s), which suggests that these materials could be used for biomedical applications.
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      PubDate: 2016-09-08T06:28:06Z
       
  • Sulfosuccinic acid-sulfonated polyether ether ketone/organo functionalized
           microporous zeolite-13X membrane electrolyte for direct methanol fuel
           cells
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): S. Sasikala, K. Hari Gopi, Santoshkumar D. Bhat
      Impact of modified hydrophilic microporous zeolite namely 13X by introducing organo-sulfonic acid groups through silane condensation; and its dispersion in sulfosuccinic acid-sulfonated polyether ether ketone (SSA-sPEEK) to form a mixed matrix membrane for its application in direct methanol fuel cells is explored. Organo-sulfonic acid groups present in modified zeolite-13X serves for dual purpose by restricting methanol cross-over and also providing additional ion conducting groups for overall improvement of the performance. Crosslinking of sPEEK with SSA proves to be beneficial in providing stability to the matrix and also helps in enhancing the ionic conductivity. Characteristic properties like ion exchange capacity, water sorption, water-methanol mixture sorption and proton conductivity for these mixed matrix membranes have been investigated. DMFC comprising SSA-sPEEK-HSO3-zeolite-13X (80:20 ratio) mixed matrix membrane delivers peak power density of 130 mW/cm2, whereas peak power density of 73 mW/cm2 was obtained for DMFC comprising pristine sPEEK membrane at 70 °C. These indicate that SSA-sPEEK-HSO3-zeolite-13X mixed matrix membrane exhibit higher DMFC performance and lower methanol permeability in comparison with pristine sPEEK membrane.
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      PubDate: 2016-09-08T06:28:06Z
       
  • Preparation and properties of sulfonated poly (2, 6-dimethyl-1,
           4-phenyleneoxide)/mesoporous silica hybrid membranes for alkali recovery
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Xueyun Li, Jibin Miao, Ru Xia, Bin Yang, Peng Chen, Ming Cao, Jiasheng Qian
      Cation exchange membranes (CEMs) aimed at alkali recovery were prepared by incorporation of amino-modified mesoporous silica (AMMS) particles into sulfonated poly (2, 6-dimethyl-1, 4-phenyleneoxide) (SPPO). The as-prepared membranes possess water uptake (WR) of 36–42.1%, swelling degree of 49.7–60.5%, mass loss around 8–16.6%, tensile strength (TS) of 26–30.8 MPa, as well as favorable thermal stability. The samples were investigated in NaOH/Na2WO4 model waste feed solution for alkali recovery via diffusion dialysis (DD) at various temperatures. Results revealed that the hybrid membrane always maintain high values of OH− coefficients and separation factors as well even at 55 °C. Improved performances of hybrid membranes were most likely due to the acid-base pairs between amino and sulfonic acid group and crosslinking between sulfonic acid groups under thermal treatment.
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      PubDate: 2016-09-08T06:28:06Z
       
  • Synthesis and characterization of thiol-functionalized MCM-41 nanofibers
           and its application as photocatalyst
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): A. Jafarzadeh, Sh. Sohrabnezhad, M.A. Zanjanchi, M. Arvand
      In this paper, the simple fabrication of MCM-41 mesoporous material nanofibers (NFs) by an electrospinning technique was suggested. The morphology of the MCM-41nanofibers (MCM-41NFs) depended on spinning voltages. Tetraethylorthosilicate (TEOS) and polyvinyl alcohol (PVA) were used as a silica source and fiber forming polymer for MCM-41NFs synthesis, respectively. MCM-41NFs were modified with organic silicanes (3-mercaptopropyltrimethoxysilane). Thiol–functionalized MCM-41 nanofibers (MCM-41-SHNFs) prepared has been used for dispersing of AgBr nanoparticles (NPs) by precipitation method. The MCM-41 and AgBr/MCM-41-SHNFs photocatalyst were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray powder diffraction (XRD), diffuse reflectance spectroscopy (DRS), Brunauer-Emmett-Teller (BET) and nitrogen adsorption–desorption measurements. The smooth and long MCM-41NFs were observed in voltages less than 16 kV. TEM and SEM images showed synthesis of MCM-41NFs with a diameter of 200 nm. The BET results indicated that the pore diameter and surface area of calcined MCM-41NFs were reduced in thiol - functionalized MCM-41 and AgBr/MCM-41-SHNF nanocomposite. Silver bromide, with different weight percentage (30%, 40% and 50%) was coupled into MCM-41-SH nanofibers. The images displayed presence of AgBr NPs with particle size ∼35 nm over nanofibers support. The AgBr/MCM-41-SH nanofibers were used for the photocatalytic degradation of methyl blue (MB) under visible light. The results showed that for the various AgBr loadings in the composites, MB photocatalytic degradation efficiency arrived at the maximum of 60% at 40% loading, or with 40AgBr/MCM-41-SHNFs photocatalyst. The MB removal reached 87% at 0.25 g/L of the 40AgBr/MCM-41-SHNFs dosage, 3.2 ppm of initial MB concentration, and 6.5 of unadjusted initial pH. The cycle experiments on the AgBr/MCM-41-SHNFs photocatalyst indicated that NFs enhance photoinduced stability of photosensitive silver compounds in all cycles. The MCM-41-SHNFs reduced photocorrosion of AgBr NPs. On the basis of the experimental results, a possible mechanism for the enhanced photocatalytic activity and photoinduced stability of AgBr/MCM-41-SHNFs photocatalyst was proposed. The enhancement of photocatalytic activity was attributed to the increase of separation efficiency of electrons and holes in AgBr. The MCM-41-SHNF played an important role in decreasing recombination of photogenerated electrons-holes and increasing MB absorption.
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      PubDate: 2016-09-08T06:28:06Z
       
  • Effect of carbonization temperature on adsorption property of ZIF-8
           derived nanoporous carbon for water treatment
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Zahra Abbasi, Ezzatollah Shamsaei, Soo Kwan Leong, Bradley Ladewig, Xiwang Zhang, Huanting Wang
      The heat treatment effect on the adsorption capabilities of nanoporous carbon particles derived from Zeolitic Imidazolate Framework-8 (ZIF-8) was investigated at 600, 1000 and 1200°C in this study. The results showed that heat treatment at 1000°C had a significant effect on the adsorption capacity of ZIF-8 (almost 10 times) for the removal of methylene blue (MB) dye from water. Nanoporous carbons were synthesized by direct carbonization of ZIF-8. SEM and TEM images showed that the carbon resulting from ZIF-8 carbonization at various temperatures retained the original structure and morphology of ZIF-8. The carbon nanoparticles carbonized at 1000°C exhibited outstanding adsorption capacities (186.3 mg/g) compared to nanoparticles carbonized at 600°C (49.5 mg/g) and 1200°C (36.7 mg/g) as well as ZIF-8 (19.5 mg/g) due to the change in surface charge and pore size distribution. The surface functionalities of materials were also characterized by Raman Spectroscopy, N2 adsorption-desorption, FTIR and TGA. The surface charge of the carbon particles changed from positive (ZIF-8) to negative as a result of conversion to carbon confirmed by zeta potential of the samples. The ZIF-8 derived carbon nanoparticles were found to be efficient adsorbents for water treatment purposes due to the satisfactory adsorption properties such as high adsorption capacity and good wettability.
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      PubDate: 2016-09-02T10:56:45Z
       
  • Prediction of phase transitions by investigating CO2 adsorption on 1%
           lithium doped MIL-101 (Cr) MOF with anomalous type isosteric heat of
           adsorption
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Sibnath Kayal, How Wei Benjamin Teo, Anutosh Chakraborty
      The amount of adsorbate uptakes and heats of adsorption (Q st ) for CO2 + 1% Li doped MIL-101 (Cr) metal organic framework (MOF) system are measured at wide ranges of pressures and temperatures. Some data are reported for the regions below the triple point (200 K–216.5 K). The multilayer CO2 adsorption uptakes in a series of discontinuous jump are found in the sub-triple region. Various types and shapes of Q st are observed and the unexpected differences in Q st at sub-triple, sub-critical and super critical regions are explained. At sub-triple zone, two sharp spikes of Q st against uptakes are found for identifying the transitions of adsorbate layer from the gaseous phase to the solid phase. The gas – liquid transition is also observed from the uptake dependence Q st data at 220 K and 240 K. A monotonic decrease in Q st is found at higher temperatures.
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      PubDate: 2016-09-02T10:56:45Z
       
  • Carbon nanotube templated synthesis of metal containing hierarchical
           SAPO-34 catalysts: Impact of the preparation method and metal avidities in
           the MTO reaction
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): Ali Zeinali Varzaneh, Jafar Towfighi, Saeed Sahebdelfar
      Hierarchical SAPO-34 was synthesized hydrothermally using carbon nanotube as hard template and modified with Co and Ni by isomorphous substitution and impregnation methods. The prepared catalysts were characterized by XRD, SEM, TEM, XRF, UV–vis, NH3-TPD, H2-TPR, FTIR and N2 physisorption measurements and their catalytic performance was evaluated for transformation of methanol to light olefins (MTO). There were meaningful differences in terms of crystallinity, acidity, porosity and reducibility among the synthesized catalysts modified by impregnation and isomorphous substitution methods. In addition, the ethylene and propylene yields and the catalytic longevity were strongly dependent on Ni and Co avidities as well as on the modification procedure. The results indicated that compared to the unmodified hierarchical SAPO-34, the catalyst modified with Ni by means of isomorphous substitution improved the yield of ethylene while methane production was promoted over SAPO-34 impregnated with Ni. On the other hand, the Co-containing SAPO-34 samples enhanced the production of both ethylene and propylene relative to the unmodified mesostructured SAPO-34 and these modifications prolonged the catalyst lifetime. These changes in the catalytic behaviors could be ascribed to the changes in the acid sites and porous structure.
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      PubDate: 2016-09-02T10:56:45Z
       
  • Enhanced methods of crystallization: The crossover synthesis from gel to
           melt flow - A case study on sodalites
    • Abstract: Publication date: 1 December 2016
      Source:Microporous and Mesoporous Materials, Volume 236
      Author(s): J.-Ch. Buhl
      A new crystallization pathway composed of a combination of gel synthesis and crystallization in a melt flow is demonstrated using the sodalite system as a case study. The specific characteristics of this enhanced method of crystallization persists in a controlled heating of a pressed pellet of a mixture of selected solids, containing a “water donator” as well as a “fluxing agent”. The reaction of zeolite 13 X (“water donator and SiAl-source”) NaOH granulate (“fluxing agent”) and a template salt like NaCl (or others) is shown to yield suitable products already after a few hours of heating the mix-pellet under open conditions. In a first synthesis series experiments were performed to investigate the details of the reaction mechanism. Beside a study of the role of the hydrate water, the NaOH granulate and certain template salts, even the total decomposition of the zeolite 13 X framework structure could be demonstrated under the conditions of the crossover from gel to flux growth. According to the results it could be claryfied that the mechanism consists of alkaline aluminosilicate gel formation and crystallization in the early period but shifts into crystal growth in NaOH melt at elevated temperature. In a second series examples of tailored sodalites and the characterization of these products will show the effectiveness of the new method. From SEM invertigations could be further derived that the crystal size and morphology depends on Tmax. the holding period at Tmax. and nano- or micro-crystalline sodalites can be obseved.
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      PubDate: 2016-09-02T10:56:45Z
       
  • Metal-organic frameworks based mixed matrix membranes for pervaporation
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Zhiqian Jia, Guorong Wu
      Metal-organic frameworks (MOFs)/polymer mixed matrix membranes (MMMs) have great potential in pervaporation separation due to the ease of design and modification of MOFs, along with the compatibility between MOFs and polymer matrix. This article reviews the current status of MOFs MMMs for pervaporation, including polymer (hydrophobicity/hydrophilicity, structure stability), MOFs (stability, hydrophobicity/hydrophilicity, surface functional structure, particles morphology and pores size), mass transfer, and applications (dehydration of organic solvents, removal of dilute organic compounds from aqueous streams, separation of organic-organic mixtures, and membrane reactor). The perspectives and suggestions of MOFs MMMs are given.
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      PubDate: 2016-08-24T14:04:39Z
       
  • Importance of hydrogen for low-temperature detemplation of high-silica MFI
           zeolite crystals
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Lin Lang, Shuheng Zhao, Junfei Jiang, Wenshen Yang, Xiuli Yin
      Many attempts have been made for template removal from inorganic porous materials at mild temperature (below 350 °C), because high-temperature calcination is attributed as the trigger of the framework damages. In this study, a new two-step method, coupling by low-temperature hydrocracking and oxidation, is proposed for efficient removal of the organic templates in high-silica MFI zeolite crystals of different size at a mild temperature (300 °C). With this approach, unlike in conventional calcination above 400 °C, the pristine zeolite framework is preserved and no coke-like residues are formed, consistently verified by NMR, TGA, and Raman spectra. The reason for this phenomenon is proved as a special propyl-radical- mechanism in H2 atmosphere, indicated by GC measurement and analysis online. This provides an alternative option for the low-temperature detemplation of high-silica microporous materials.
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      PubDate: 2016-08-19T14:00:27Z
       
  • Syntheses of SSZ-39 and mordenite zeolites with
           N,N-dialkyl-2,6-dimethyl-piperidinium hydroxide/iodides: Phase-selective
           syntheses with anions
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Biswa Nath Bhadra, Pill Won Seo, Jong Won Jun, Jong Hwa Jeong, Tae-Wan Kim, Chul-Ung Kim, Sung Hwa Jhung
      SSZ-39 and mordenite zeolites were obtained from the conversion of zeolite Y in the presence of the same reaction precursors (organic templates, NaOH, water, etc.) under a wide range of reaction conditions. The applied templates were N,N-dialkyl-2,6-dimethyl-piperidinium-OH and -I (alkyl: ethyl or methyl). Curiously, SSZ-39 and mordenite were obtained from hydroxides and iodides, respectively, showing firstly the importance of the anion in the selective crystallization of zeolites. Reactions were also performed at the same set of pH values (achieved by adding small amounts of NaOH to the iodide-based precursors) to investigate the effect of basicity; the results did not vary appreciably with the pH of the synthesis precursors. Based on the phase conversion (MOR – > AEI or ANA with increasing reaction time and pH), the selective formation of SSZ-39 and mordenite from hydroxides and iodides, respectively, could be explained in terms of zeolite-promoting and -preventing anions (hydroxide and iodide, respectively). The phase conversion of zeolites could be explained on the basis of the maximum pore size of zeolites, rather than the framework densities. The obtained zeolites (SSZ-39 and mordenite), in their protonated forms, were employed in ethanol dehydration and direct ethylene-to-propylene conversion, and the results showed that the two zeolites have potential application in acid catalysis. In particular, the SSZ-39 with an AEI structure can be applied in the direct production of propylene from ethylene or ethanol.
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      PubDate: 2016-08-19T14:00:27Z
       
  • Manipulation of the surface microstructure and its effects on the flux of
           NaA zeolite membranes in pervaporation
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Nanke Ma, Zhiying Zhan, Zhengbao Wang
      NaA membranes with different microstructures are synthesized on macroporous alumina tubes with the addition of crystallization improving agents (CIAs) which have the same composition with the synthesis hydrogel but are aged for a longer time (e.g., 24 h). The as-synthesized membranes are characterized by SEM, contact angle measurement and pervaporation test. It is found that the addition of the CIAs in the synthesis hydrogel has significant influence on the surface roughness of zeolite membrane, resulting in the change of the hydrophilicity and thus flux of the zeolite membrane. Dense NaA membranes with high flux of 4.53 kg m−2 h−1 can be obtained at 100 °C for 3 h with the addition of 10 wt% CIAs in the synthesis hydrogel. The flux is increased by 14% compared with the membrane synthesized at the same condition without CIAs. The surface roughness of the membranes can also be changed by the method of polishing and re-synthesizing with the assist of nano-seeds. After polishing, the flux decreases to 3.83 kg m−2 h−1; however, the flux can be recovered to 4.45 kg m−2 h−1 after re-synthesizing. This study provides a good method to enhance the separation efficiency and indicates that the surface microstructure of membranes influences their pervaporation performance.
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      PubDate: 2016-08-19T14:00:27Z
       
  • Gas transport through mixed matrix membranes composed of polysulfone and
           copper terephthalate particles
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Piotr Kubica, Aleksandra Wolinska-Grabczyk, Eugenia Grabiec, Marcin Libera, Marcin Wojtyniak, Sylwia Czajkowska, Marian Domański
      In this work gas transport and structural investigations of heterogeneous membranes composed of polysulfone and copper terephthalate (CuTPA) particles are reported. Three types of CuTPA, varying in surface area, pore volume and pore size distribution, as it was shown by nitrogen physisorption, were investigated as membrane fillers. Structural characterization of pure CuTPA and composite membranes was carried out by positron annihilation lifetime spectroscopy, calorimetry, derivatography, electron microscopy, X-ray diffraction and density measurements. CuTPA possessing high porosity was found to increase permeability of heterogeneous membranes to N2, O2, He, CO2. In contrast, permeability decrease was observed for two other types of CuTPA with lower porosity. Additionally, membranes containing highly porous CuTPA were annealed at two different temperatures and it was found that higher temperature results in higher both membrane permeability and selectivity. For example, CO2 permeability for membrane annealed at 150 °C was 1.65-times higher than that for pure PSF, whereas membrane annealed at 200 °C was 3.3-times more permeable. This significant change in membrane permeability was ascribed to residual solvent removal from CuTPA pores.
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      PubDate: 2016-08-19T14:00:27Z
       
  • Metal loaded nanoporous silicas with tailor-made properties through
           hyperbranched polymer assisted templating approaches
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): E.G. Deze, A. Papavasiliou, S.K. Papageorgiou, F.K. Katsaros, E.P. Kouvelos, G.E. Romanos, N. Boukos, Q. Xin, J.L. Nyalosaso, P. Cool
      Over the last years, mesoporous silicas have gathered considerable interest especially in the field of catalysis, singled out as excellent catalytic supports owing to their intriguing textural features. Herein, the synthesis of novel nanoporous silicate materials containing copper or palladium nanoparticles, by means of co-assembly and one-pot templating pathways is described. Inclusion of metal nanoparticles within the porous network of the silicate materials is accomplished with the use of hyperbranched Polyethyleneimines (PEIs), serving both as chelating and secondary structure directing agents. The co-assembly method involves the introduction of PEI into the initial reaction mixture containing the triblock copolymer Pluronic P123 as the main template and TEOS as the silica source, whereas incorporation of metal nanoparticles is performed at a second step. In the one-pot approach, the only difference is that metal loading is carried out in a single step through the direct insertion of PEI already complexed with the desired metal, into the synthetic gel. Several parameters are investigated including solution's pH, reaction path and PEI's molecular weight. Results from TGA, XRD, N2 porosimetry, electron microprobe, SEM, TEM and UV-DR analyses, confirm that both synthetic strategies can produce nanoporous materials with advanced and tunable textural and morphological characteristics and thus widened application prospects. Among the examined synthesis parameters, PEI molecular weight and synthetic gel's pH were found to have the most pronounced effect on final material pore architecture, morphology, metal loading and dispersion. Preliminary deNOx activity tests in the NO + CO reaction indicated that the developed materials could find use in environmental applications.
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      PubDate: 2016-08-19T14:00:27Z
       
  • Use of chabazite, a naturally abundant zeolite, for the investigation of
           the adsorption kinetics and mechanism of methylene blue dye
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Hamza Aysan, Serpil Edebali, Celalettin Ozdemir, Muazzez Celi̇k Karakaya, Necati Karakaya
      Chabazite, one of the common types of zeolite, was used in our study to remove methylene blue (MB) dye from aqueous solutions. The characterization of chabazite was performed using scanning electron microscope (SEM), Fourier Transform infrared (FTIR), X ray diffraction (XRD), and thermogravimetric-differential thermal analyses TG/DTA. During the experimental study, the effects of some parameters, such as contact time, adsorbent dosage, pH, stirring speed, and concentration, on the removal efficiency of chabazite were taken into consideration. To evaluate the experimental data, Langmuir, Freundlich, and Tempkin isotherm models were used. The experimental data were well fitted to the Langmuir isotherm model, with a correlation coefficient of 0.95. The adsorption kinetics of MB dye on chabazite could be described by a pseudo second-order model.
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      PubDate: 2016-08-15T03:49:35Z
       
  • A novel modelling approach to surface and Knudsen multicomponent diffusion
           through NaY zeolite membranes
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Alessio Caravella, Pasquale F. Zito, Adele Brunetti, Enrico Drioli, Giuseppe Barbieri
      A novel pairing between Knudsen and surface diffusion is developed for multicomponent mass transport in NaY zeolite membranes considering the actual conditions inside the pores owing to competitive adsorption of the species. The motivation behind this study starts from the consideration that the adsorption of the species, in particular of the most strongly adsorbed ones (like CO2), can significantly influence the Knudsen permeation. This occurs because the pore geometrical parameters affecting permeation, i.e., porosity, tortuosity and mean diameter, are modified by the steric effect owing to the presence of the adsorbed molecules, whose size is close to pore diameter. Therefore, in the present work, all these geometrical parameters are expressed as functions of the adsorption loading. This leads to a model that correctly predicts the blocking effect on the Knudsen diffusion mechanism at a low temperature, where the adsorption strength is sufficiently high to cause a severe occupation of the channel cross-section. As a consequence, such a model allows membrane selectivity to be predicted in a wide range of temperature and pressure. For instance, the CO2/H2 selectivity is observed to change from 25 to 0.3 when the temperature goes from 303 to 673 K. Hence, this novel approach, which is well-validated in both binary- and ternary-mixture conditions, is a useful tool for the analysis of the mass transport of multicomponent mixtures through NaY zeolite membranes, particularly at lower temperatures, where the adsorption strength provides a higher selectivity.
      Graphical abstract image

      PubDate: 2016-08-15T03:49:35Z
       
  • Synthesis of biomass derived levulinate esters on novel sulfated Zr/KIL-2
           composite catalysts
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Margarita Popova, Ágnes Szegedi, Hristina Lazarova, Alenka Ristić, Yuri Kalvachev, Genoveva Atanasova, Nicole Wilde, Nataša Novak Tušar, Roger Gläser
      Zirconia nanomaterials were prepared by impregnation of KIL-2 type silica with 4, 8, 15 and 25 wt% of ZrO2, and were modified by sulfate groups in order to vary the type, strength and density of the active sites. The samples were characterized by X-ray powder diffraction (XRD), EDX analysis, N2 physisorption, SEM, TEM, UV–Vis spectroscopy, XPS, and thermogravimetric analysis (TGA). The acidic properties were investigated by FT-IR spectroscopy of adsorbed pyridine. The catalytic properties of ZrKIL-2 catalysts and their sulfated varieties were studied in levulinic acid (LA) esterification with ethanol or n-butanol. The sulfated materials showed significantly higher activity compared to the non-sulfated ones due to their stronger Brönsted and Lewis acid sites. It was found that the silica supported sulfated samples show different activity depending on the applied alcohol. With increasing ZrO2 content up to 15 wt% increasing catalytic activity and selectivity was observed to produce levulinate esters. A further increase of the amount of zirconia leads to a decrease in catalytic activity because of the significant decrease of ZrO2 dispersion and the structure deterioration of the catalyst. For the first time insight was provided into the relation between sulfates group leaching and zirconia dispersion.
      Graphical abstract image

      PubDate: 2016-08-10T03:44:32Z
       
  • Use of surface modified natural zeolite (SMNZ) in pharmaceutical
           preparations. Part 2. A new approach for a fast functionalization of
           zeolite-rich carriers
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Bruno de Gennaro, Mariano Mercurio, Piergiulio Cappelletti, Lilia Catalanotti, Aleksandra Daković, Alberto De Bonis, Celestino Grifa, Francesco Izzo, Milan Kraković, Vincenzo Monetti, Alessio Langella
      Main purpose of the research was to define an operative protocol, applicable at industrial scale, optimizing the functionalization of natural zeolites with surfactants, especially in pharmaceutical and environmental sphere. Three zeolite-rich samples from Italy (PHI_SAV), Slovakia (CLI_SK) and California (CLI_CA) were used for preparation of SMNZ. Two different protocols allowed to carry out surfactant adsorption equilibrium runs and surfactant sorption kinetics by varying different parameters: mixing speed (4000, 6000, and 8000 rpm); contact time (15 ÷ 90 min) and initial surfactant concentration (from 25% to 200% of the external cation exchange capacity - ECEC) at a constant solid/liquid ratio (1 g/50 mL). Zeolite-rich materials were treated with solutions of cetylpiridinium chloride (CP-Cl). The functionalization of SMNZ was obtained by using a high-speed disperser. The amount of absorbed surfactant onto two carriers (CLI_SK and PHI_SAV) was evaluated through kinetic experiments under the following conditions: the initial CP-Cl concentration of 150% of the ECEC and a disperser speed of 8000 rpm. Results showed that after 15 min, equilibrium was attained with the adsorbed amount of about 0.14 meq/g of CP-Cl (equivalent to the ECEC of the investigated zeolitic support), confirming formation of monolayer (emi-micelle). The functionalization (micelle formation) of two samples occurred after 70 min of solid/liquid interaction with a total yield equal to 150% of the ECEC, thus indicating formation of a patchy bilayer. By contrast, CLI_CA behaves completely differently since the formation of emi-micelle was achieved only at much higher speed (18000 rpm) and not earlier than 90 min of mixing.
      Graphical abstract image

      PubDate: 2016-08-10T03:44:32Z
       
  • Dynamic measurements and wettability phenomena in mesoporous anodic films
           prepared on 1050 and 2024T3 aluminium alloys
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Kévin Giffard, Laurent Arurault, Christine Blanc
      The wettability of mesoporous anodic films has until now been a parameter rarely studied although it remains crucial especially for sealing treatment following anodising. Wettability measurement is in fact complex as it depends on a number of process parameters relating to the three phases (mesoporous anodic film, deposited liquid and ambient gas). In the present study, an innovative experimental approach was first adopted involving measuring the characteristics of a deposited water drop (contact angle, chord length and height of the drop) in relation to time. Following this, a flow balance allowed the amount of water having infiltrated the mesopores to be determined for two types of anodic film, one tortuous (on an AA 2024T3 substrate), the other not (on an AA 1050 substrate). On the basis of models already available in the literature, a phenomenological mechanism (spreading, penetration and evaporation) was finally proposed and discussed especially with respect to the tortuosity and prior drying of mesoporous anodic films.
      Graphical abstract image

      PubDate: 2016-08-10T03:44:32Z
       
  • The importance of electrode characterization to assess the supercapacitor
           performance of ordered mesoporous carbons
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Ángela Sánchez-Sánchez, Teresa A. Centeno, Fabián Suárez-García, Amelia Martínez-Alonso, Juan Manuel D. Tascón
      Carbon based-supercapacitors are widely used in numerous applications but the knowledge of the specific role of carbon features in their performance is still insufficient. The main aim of this work is to warn readers that the current interpretation of the device operation, mostly based on powdered carbon properties, may be misleading in certain cases and should be complemented with the physicochemical characterization of the corresponding electrodes. Ordered mesoporous carbons highly enriched in surface functionalities were prepared by carbonization of 3-aminobenzoic acid into SBA-15 template. These carbons achieved a specific capacitance as high as 220 F/g in 2 M H2SO4 aqueous electrolyte. The pseudocapacitance contribution ranged between 35 and 70% of the overall capacitance. It was shown that the structural and textural changes underwent by these advanced carbons during their processing in form of electrodes prevented the full exploitation of their outstanding properties for high-power applications. This makes a difference regarding conventional, disordered activated carbons, which virtually preserve their structure during electrode preparation.
      Graphical abstract image

      PubDate: 2016-08-10T03:44:32Z
       
  • High-pressure behavior of HEU-type zeolites: X-ray diffraction study of
           clinoptilolite-Na
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Yurii V. Seryotkin
      Clinoptilolite-Na, Na2.55Ca1.67K0.37(H2O)21.5[Al6.21Si29.79O72], with the space group C2/m, a = 17.6229(4), b = 17.9957(3), c = 7.39625(15) Å, β = 116.353(3)°, V = 2101.85(7) Å3, and Z = 1 has been studied by single-crystal X-ray diffraction method in normal conditions as well as under compression in penetrating (water-containing) and non-penetrating (paraffin) media. When compressing in water medium, clinoptilolite is subjected to the additional hydration at the starting stage unlike the structurally similar heulandite with persistent increasing the content of H2O over the wide pressure range. This occurs owing to the additional population of partially vacant positions. With further increasing the pressure, H2O molecules are redistributed in the extraframework subsystem saving the total number. Both literature and our data on compression of zeolites of the isomorphous heulandite-clinoptilolite series in non-penetrating media evidence that the compressibility along the coordinate directions noticeably differs from sample to sample including differences in the direction of the largest compression. This is evidently associated with variations in the zeolite composition.
      Graphical abstract image

      PubDate: 2016-08-10T03:44:32Z
       
  • Mineralogical characterization of zeolites present on basaltic rocks from
           Combia geological formation, La Pintada (Colombia)
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): J.F. Gelves, G. Sierra Gallego, M.A. Marquez
      The present study report the presence of natural zeolites, which were found in the andesitic basalts from the Combia geological formation, municipality of La Pintada, Antioquia department (Colombia). The collected samples were characterized using X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with detector X-ray energy dispersive (SEM/EDX), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and polarized light optical microscopy (PLOM). The results shown the presence of an associated zeolites heulandite group with predominance of heulandite phase rich in calcium and potassium, with prevalence of platy habit and in a lesser extent the habit coffin type, tabular and block were also evidenced. The presence of chabazite, phillipsite and mordenite, were evidenced as minority zeolites phases. Based on the zeolites properties, the phases founded in Combia formation could be an interest materials for technological applications in areas such agriculture, catalysis or gas separation applications. Especially in Colombia this kind of mineral can be important because much of the current consumption is imported from other territories.
      Graphical abstract image

      PubDate: 2016-08-10T03:44:32Z
       
  • Methane in zeolitic imidazolate framework ZIF-90: Adsorption and diffusion
           by molecular dynamics and Gibbs ensemble Monte Carlo
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): Vo Thuy Phuong, T. Chokbunpiam, S. Fritzsche, T. Remsungnen, T. Rungrotmongkol, C. Chmelik, J. Caro, S. Hannongbua
      There is experimental evidence from adsorption and permeation studies that methane can enter the Zeolitic Imidazolate Framework (ZIF)-90 framework despite the fact that the critical diameter of methane (3.8 Å) is larger than the window size of ZIF-90 (3.5 Å) assuming a rigid framework. Therefore, adsorption and diffusion of methane in the ZIF-90 were investigated by Molecular Dynamics (MD) and Gibbs Ensemble Monte Carlo. Various interaction force fields have been tested and a suitable one has been proposed. Results of structural and dynamical properties of methane in ZIF-90 are presented. Like for methane in ZIF-8, no gate opening was found in this paper for methane in ZIF-90 up to a pressure of 260 bar. Therefore, the adsorption and diffusion of methane in ZIF-90 can be explained by a flexible framework.
      Graphical abstract image

      PubDate: 2016-08-10T03:44:32Z
       
  • Protein encapsulation in SBA-15 with expanded pores
    • Abstract: Publication date: 15 November 2016
      Source:Microporous and Mesoporous Materials, Volume 235
      Author(s): P.R.A.F. Garcia, R.N. Bicev, C.L.P. Oliveira, O.A. Sant’Anna, M.C.A. Fantini
      This work reports the encapsulation of proteins with different molecular weights into SBA-15 ordered mesoporous silica, a potential immunological adjuvant. The Human Gammaglobulin G (HGG) and Bovine Serum Albumin (BSA) proteins were incorporated into the mesoporous silica with expanded pores. A structure swelling agent, triisopropylbenzene (TIPB), was used in the synthesis process, promoting an increase of the average pore diameter and a more disordered pore network, as revealed by nitrogen adsorption isotherm (NAI) and small angle X-ray scattering (SAXS) data. SAXS measurements were also performed to obtain the overall size of the studied proteins. The results showed that both proteins have dimensions that would allow their encapsulation inside the pores of SBA-15. The HGG and BSA proteins were dissolved in phosphate buffered saline (PBS) solutions before encapsulation. It was evidenced the filling of the micropores by the PBS solution and a larger variation in pore volume and surface area for the material with higher mean pore diameter, which was also confirmed by the modeling of SAXS data. It was not observed any significant difference in the SAXS and NAI results of both proteins, indicating that the immunogens could be encapsulated in the silica macroporosity, obstructing the mesopore entrances.
      Graphical abstract image

      PubDate: 2016-08-10T03:44:32Z
       
 
 
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