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Sample records for mcm-41 mesoporous silica

  1. Tetracycline-Containing MCM-41 Mesoporous Silica Nanoparticles for the Treatment of Escherichia coli.

    Science.gov (United States)

    Koneru, Bhuvaneswari; Shi, Yi; Wang, Yu-Chieh; Chavala, Sai H; Miller, Michael L; Holbert, Brittany; Conson, Maricar; Ni, Aiguo; Di Pasqua, Anthony J

    2015-10-30

    Tetracycline (TC) is a well-known broad spectrum antibiotic, which is effective against many Gram positive and Gram negative bacteria. Controlled release nanoparticle formulations of TC have been reported, and could be beneficial for application in the treatment of periodontitis and dental bone infections. Furthermore, TC-controlled transcriptional regulation systems (Tet-on and Tet-off) are useful for controlling transgene expression in vitro and in vivo for biomedical research purposes; controlled TC release systems could be useful here, as well. Mesoporous silica nanomaterials (MSNs) are widely studied for drug delivery applications; Mobile crystalline material 41 (MCM-41), a type of MSN, has a mesoporous structure with pores forming channels in a hexagonal fashion. We prepared 41 ± 4 and 406 ± 55 nm MCM-41 mesoporous silica nanoparticles and loaded TC for controlled dug release; TC content in the TC-MCM-41 nanoparticles was 18.7% and 17.7% w/w, respectively. Release of TC from TC-MCM-41 nanoparticles was then measured in phosphate-buffered saline (PBS), pH 7.2, at 37 °C over a period of 5 h. Most antibiotic was released from both over this observation period; however, the majority of TC was released over the first hour. Efficacy of the TC-MCM-41 nanoparticles was then shown to be superior to free TC against Escherichia coli (E. coli) in culture over a 24 h period, while blank nanoparticles had no effect.

  2. Tetracycline-Containing MCM-41 Mesoporous Silica Nanoparticles for the Treatment of Escherichia coli

    Directory of Open Access Journals (Sweden)

    Bhuvaneswari Koneru

    2015-10-01

    Full Text Available Tetracycline (TC is a well-known broad spectrum antibiotic, which is effective against many Gram positive and Gram negative bacteria. Controlled release nanoparticle formulations of TC have been reported, and could be beneficial for application in the treatment of periodontitis and dental bone infections. Furthermore, TC-controlled transcriptional regulation systems (Tet-on and Tet-off are useful for controlling transgene expression in vitro and in vivo for biomedical research purposes; controlled TC release systems could be useful here, as well. Mesoporous silica nanomaterials (MSNs are widely studied for drug delivery applications; Mobile crystalline material 41 (MCM-41, a type of MSN, has a mesoporous structure with pores forming channels in a hexagonal fashion. We prepared 41 ± 4 and 406 ± 55 nm MCM-41 mesoporous silica nanoparticles and loaded TC for controlled dug release; TC content in the TC-MCM-41 nanoparticles was 18.7% and 17.7% w/w, respectively. Release of TC from TC-MCM-41 nanoparticles was then measured in phosphate-buffered saline (PBS, pH 7.2, at 37 °C over a period of 5 h. Most antibiotic was released from both over this observation period; however, the majority of TC was released over the first hour. Efficacy of the TC-MCM-41 nanoparticles was then shown to be superior to free TC against Escherichia coli (E. coli in culture over a 24 h period, while blank nanoparticles had no effect.

  3. Structure evolution of mesoporous silica SBA-15 and MCM-41 under swift heavy ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Lou, Y.; Toquer, G.; Dourdain, S.; Rey, C. [ICSM-UMR 5257, CEA/CNRS/UM2/ENSCM Marcoule, BP 17171, F-30207 Bagnols-sur-Cèze (France); Grygiel, C. [CIMAP GANIL, Bd. Henri Becquerel, BP 5133, F-14070 Caen CEDEX 5 (France); Simeone, D. [CEA, DEN, LRC CARMEN, CEA Saclay, F-91191 Gif/Yvette (France); Deschanels, X., E-mail: xavier.deschanels@cea.fr [ICSM-UMR 5257, CEA/CNRS/UM2/ENSCM Marcoule, BP 17171, F-30207 Bagnols-sur-Cèze (France)

    2015-12-15

    Two types of mesoporous silica pellets, SBA-15 and MCM-41, were prepared and irradiated by {sup 20}Ne 278 MeV (max. fluence = 2.5 × 10{sup 14} ion/cm{sup 2}) and {sup 36}Ar 493 MeV beams (max. fluence = 1 × 10{sup 13} ion/cm{sup 2}). Irradiated and non-irradiated samples were characterized by nitrogen adsorption/desorption analysis, small angle X-ray scattering, and infrared spectrometry. The different behaviours of the two materials under different conditions are observed and discussed. We point out that SBA-15 is more robust than MCM-41 under irradiation.

  4. Structure evolution of mesoporous silica SBA-15 and MCM-41 under swift heavy ion irradiation

    Science.gov (United States)

    Lou, Y.; Toquer, G.; Dourdain, S.; Rey, C.; Grygiel, C.; Simeone, D.; Deschanels, X.

    2015-12-01

    Two types of mesoporous silica pellets, SBA-15 and MCM-41, were prepared and irradiated by 20Ne 278 MeV (max. fluence = 2.5 × 1014 ion/cm2) and 36Ar 493 MeV beams (max. fluence = 1 × 1013 ion/cm2). Irradiated and non-irradiated samples were characterized by nitrogen adsorption/desorption analysis, small angle X-ray scattering, and infrared spectrometry. The different behaviours of the two materials under different conditions are observed and discussed. We point out that SBA-15 is more robust than MCM-41 under irradiation.

  5. Steam stable mesoporous silica MCM-41 stabilized by trace amounts of Al.

    Science.gov (United States)

    Tompkins, Jordan T; Mokaya, Robert

    2014-02-12

    Evaluation of low and ultralow Al content (Si/Al between 50 and 412) aluminosilicate Al-MCM-41 materials synthesized via three contrasting alumination routes, namely, direct mixed-gel synthesis, post-synthesis wet grafting, and post-synthesis dry grafting, indicates that trace amounts of Al introduced via dry grafting can stabilize mesoporous silica MCM-41 to steaming at 900 °C for 4 h. It was found that trace amounts of Al (Si/Al > 400) introduced via so-called dry grafting of Al stabilize the virtually purely siliceous MCM-41 to steaming, whereas Al incorporated via other methods that involve aqueous media such as direct mixed gel synthesis or wet grafting of Al offer only limited protection at low Al content. It is particularly remarkable that a post-synthesis dry grafted Al-MCM-41 material possessing trace amounts of Al (i.e., Si/Al ratio of 412) and surface area and pore volume of 1112 m(2)/g and 1.20 cm(3)/g, respectively, retains 90% (998 m(2)/g) of the surface area and 85% (1.03 cm(3)/g) of the pore volume after exposure to steaming at 900 °C for 4 h. Under similar steam treatment conditions, the mesostructure of pure silica Si-MCM-41 is virtually destroyed and undergoes a 93% reduction in surface area (958 m(2)/g to 69 m(2)/g) and 88% decrease in pore volume (0.97 cm(3)/g to 0.12 cm(3)/g). The steam stable ultralow (i.e., trace) Al containing MCM-41 materials is found to be virtually similar to mesoporous pure silica Si-MCM-41 with hardly any detectable acidity. The improvement in steam stability arises from not only the presence of trace amounts of Al, but also from an apparent increase in the level of silica condensation that is specific to dry grafted alluminosilicate MCM-41 materials. The more highly condensed framework has fewer silanol groups and therefore is more resistant to hydrolysis under steaming conditions.

  6. Stabilization of quercetin flavonoid in MCM-41 mesoporous silica: positive effect of surface functionalization.

    Science.gov (United States)

    Berlier, Gloria; Gastaldi, Lucia; Ugazio, Elena; Miletto, Ivana; Iliade, Patrizia; Sapino, Simona

    2013-03-01

    Antioxidants can prevent UV-induced skin damage mainly by neutralizing free radicals. For this purpose, quercetin (Q) is one of the most employed flavonoids even if the potential usefulness is limited by its unfavorable physicochemical properties. In this context, mesoporous silica (MCM-41) is herein proposed as a novel vehicle able to improve the stability and performance of this phenolic substrate in topical products. Complexes of Q with plain or octyl-functionalized MCM-41 were successfully prepared with different weight ratios by a kneading method, and then, they were characterized by XRD, gas-volumetric (BET), TGA, DSC, and FTIR analyses. The performances of the different complexes were evaluated in vitro in terms of membrane diffusion profiles, storage and photostability, antiradical and chelating activities. The physicochemical characterization confirmed an important host/guest interaction due to the formation of Si-OH/quercetin hydrogen-bonded adducts further strengthened by octyl functionalization through van der Waals forces. The immobilization of Q, particularly on octyl-functionalized silica, increased the stability without undermining the antioxidant efficacy opening the way for an innovative employment of mesoporous composite materials in the skincare field.

  7. Grafting aluminum(III) 8-hydroxyquinoline derivatives on MCM-41 mesoporous silica for tuning of the light emitting color.

    Science.gov (United States)

    Fazaeli, Yousef; Amini, Mostafa M; Mohajerani, Ezeddin; Sharbatdaran, Masoomeh; Torabi, Naime

    2010-06-15

    Fluorescent materials (Q)(3-n)(2-BuO)(n)Al (Q = 8-hydroxyquinoline, 2-methyl-8-hydroxyquinoline and 5-chloro-8-hydroxyquinoline, n = 1 or n = 2) were prepared in toluene by reacting aluminum 2-butoxide with 8-hydroxyquinoline and its derivatives. The compounds were characterized by (1)H, (13)C and (27)Al NMR in solution, and the coordination status of the aluminum atom in the complexes were determined by (27)Al NMR chemical shifts. The compounds were grafted on mesoporous silica (MCM-41) at room temperature without isolation of the complexes. The prepared materials were characterized by elemental analysis, FT-IR spectroscopy, low-angle X-ray diffraction (XRD), thermal analysis (TGA/DSC) and N(2) adsorption and desorption measurements. The results showed that the characteristic mesoporous structure of MCM-41 after grafting aluminum complexes remains intact. The photoluminescence (PL) properties of (Q)(3-n)(2-BuO)(n-1)@Al-MCM-41 were investigated. The results revealed that the maximum wavelength is modulated by the MCM-41 guest.

  8. Promotion effect of palladium on Co3O4 incorporated within mesoporous MCM-41 silica for CO Oxidation

    Science.gov (United States)

    Hassan, Hassan M. A.; Betiha, Mohamed A.; Elshaarawy, Reda F. M.; Samy El-Shall, M.

    2017-04-01

    Co3O4 incorporated within mesoporous MCM-41 silica have been successfully synthesized and promoted with Pd nanoparticles through a microwave irradiation (MWI) approach. Powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), N2-physisorped, X-ray photoelectron spectroscopy (XPS), temperature program reduction of hydrogen (H2-TPR), temperature program desorption of oxygen (O2-TPD) and high resolution transmission electron microscopy (HRTEM) were adapted to characterize these prepared catalysts. Carbon monoxide oxidation as a model reaction was then used to assess the catalytic performance of these materials. In the light of H2-TPR and XPS results, revealed that the coexisting of Co3+ and Co2+ species as well as surface Co3+/Co2+ ratio within the hexagonal mesoporous of MCM-41, could create an ideal environment to accomplish most extreme catalytic activity. On the other hand, the enhanced CO oxidation by Pd nanoparticles deposition has been explained in the light of the enhancement of the redox ability and tuning the electronic structure of Co3O4, which improved the O2 activation and reduced the adsorption ability of CO simultaneously, which significantly boosted the catalytic performance of CO oxidation. This work provides insights into factors that could lead to improved low temperature CO oxidation performance in Pd-based catalysts.

  9. Luminescent hybrid materials based on covalent attachment of Eu(III)-tris(bipyridinedicarboxylate) in the mesoporous silica host MCM-41.

    Science.gov (United States)

    Ilibi, Maturi; de Queiroz, Thiago Branquinho; Ren, Jinjun; De Cola, Luisa; de Camargo, Andrea Simone Stucchi; Eckert, Hellmut

    2014-06-14

    A luminescent inorganic-organic hybrid material was synthesized by covalent immobilization of a europium bipyridine carboxylate complex on the inner pore walls of the mesoporous silica host MCM-41 using the grafting method. Guest-host binding was achieved through double functionalization of the host surface with organosilane reagents (trimethylsilyl, TMS, and aminopropyltriethoxysilane, APTES) followed by reaction of the active amino sites of the APTES residue with the ligand 2,2'-bipyridyl-6,6'-dicarboxylic acid. Addition of EuCl3 solution dissolved in ethanol results in the formation of an immobilized complex having the probable formula Eu(L)x(3 ≥ x ≥ 1)(H2O)y, whose detailed photophysical properties were investigated. In the final step, an additional 2,2'-bipyridine-6 monocarboxylic acid ligand was added in an attempt to complete the coordination sphere of the rare earth ion. Each of the synthesis steps was monitored by (1)H, (13)C, and (29)Si solid state NMR spectroscopies, allowing for a quantitative assessment of the progress of the reaction and the influence of the paramagnetic species on the spectra. Based on these data and additional characterizations by chemical analysis, thermogravimetric analysis (TGA), N2 sorption, X-ray diffraction and FT-IR spectroscopy, a comprehensive quantitative picture of the covalent binding and complexation process was developed.

  10. Uniform surface modification of 3D Bioglass®-based scaffolds with mesoporous silica particles (MCM-41 for enhancing drug uptake capability

    Directory of Open Access Journals (Sweden)

    Elena eBoccardi

    2015-11-01

    Full Text Available The design and characterization of a new family of multifunctional scaffolds based on bioactive glass (BG of 45S5 composition for bone tissue engineering and drug delivery applications is presented. These BG-based scaffolds are developed via a replication method of polyurethane packaging foam. In order to increase the therapeutic functionality, the scaffolds were coated with mesoporous silica particles (MCM-41, which act as an in-situ drug delivery system. These sub-micron spheres are characterized by large surface area and pore volume with a narrow pore diameter distribution. The solution used for the synthesis of the silica mesoporous particles was designed to obtain at the same time a high ordered mesoporous structure and spherical shape, both are key factors for achieving the desired controlled drug release. The MCM-41 particles were synthesized directly inside the BG-based scaffolds and the drug release capability of this combined system was evaluated. Moreover the effect of MCM-41 particle coating on the bioactivity of the BG-based scaffolds was assessed. The results indicate that it is possible to obtain a multifunctional scaffold system characterized by high and interconnected porosity, high bioactivity and sustained drug delivery capability.

  11. Synthesis, spectroscopy and catalysis of [Cr(acac)3] complexes grafted onto MCM-41 materials: formation of polyethylene nanofibres within mesoporous crystalline aluminosilicates

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Ramachandra Rao, R.; Bodart, P.; Debras, G.; Collart, O.; Voort, P. van der; Schoonheydt, R.A.; Vansant, E.F.

    2000-01-01

    Chromium acetyl acetonate [Cr(acac)3] complexes have been grafted onto the surface of two mesoporous crystalline materials; pure silica MCM-41 (SiMCM-41) and Al-containing silica MCM-41 with an Si:Al ratio of 27 (AlMCM-41). The materials were characterized with X-ray diffraction, N2 adsorption, ther

  12. 温和条件下介孔分子筛{MCM-41的修饰与表征%Synthesis and Charaterization of 3-aminopropyl Modified Mesoporous Silica MCM-41 at Room Temperature

    Institute of Scientific and Technical Information of China (English)

    郑珊; 高濂; 郭景坤

    2000-01-01

    在温和条件下,以3-氨丙基三乙氧基硅烷为偶联?剂,修饰介孔分子筛MCM--41(Si/Al=35),成功地将有机官能团引入到介孔分子筛孔道中,制备了一种无机--有机?复合材料MCM-(CH2)3NH2.以XRD、FTIR、DTA--TGA、N2吸附-脱附和HREM?表征了复合材料,结果表明:有机基团-(CH2)3NH2不仅进入?孔道、修饰了MCM--41的孔壁,而且使介孔分子筛MCM--41保持了有序的孔道结构.%Under mild experiomental conditions, with 3-aminopropyltriethoxysilane as the coupling agent, mesoporous molacular sieve MCM--41(Si/Al=35) was modified, and --(CH2)3NH2 organic functional group was successfully introduced into the pore of the mesoporous sieve, the organic/inorganic complex material MCM--(CH2)3NH2 was synthesized, and characterized by XRD, FTIR, DTA-TG, nitrogen adsorption-desorption at 77K and HREM. The results of the characterization show that --(CH2)3NH2 not only gets into the modified inner wall of mesoporous MCM-41, but also makes MCM--41 remain its ordered pore structure

  13. Application of novel Polypyrrole/thiol-functionalized zeolite Beta/MCM-41 type mesoporous silica nanocomposite for adsorption of Hg2+ from aqueous solution and industrial wastewater: Kinetic, isotherm and thermodynamic studies

    Science.gov (United States)

    Javadian, Hamedreza; Taghavi, Mehdi

    2014-01-01

    Hierarchical zeolite consists of both microporous and unordered mesoporous structures. A composite of Polypyrrole/thiol-functionalized Beta/MCM-41 (PPy/SH-Beta/MCM-41) was prepared, characterized by FE-SEM, FT-IR, XRD, TGA and BET analysis and applied in the investigation of its adsorption characteristics for the removal of Hg2+ ions from aqueous solutions. Thiol-functionalized Beta/MCM-41 (SH-Beta/MCM-41) was prepared by 3-mercaptopropyltrimethoxysilane (MPTMS) in the presence of aerosil-200 as a silica source by two-step hydrothermal crystallization procedure. Batch mode experiments were conducted and three kinetic models were used to describe the adsorption process. The experimental data fitted very well with the Pseudo-second-order kinetic model. The calculated thermodynamic parameters (ΔH, ΔS and ΔG) revealed that the adsorption of Hg2+ onto PPy/SH-Beta/MCM-41 is an endothermic and spontaneous process. It was found that temperature has a positive effect on the removal efficiency and that PPy/SH-Beta/MCM-41 is potentially able to remove Hg2+ ions from aqueous solutions at even high concentrations (400 mg L-1). The recovery of Hg2+ from the PPy/SH-Beta/MCM-41 adsorbent was found to be more than 90% using 0.5 M H2SO4, and the ability of the absorbent to be reused for removal of Hg2+ was investigated.

  14. Synthesis of thiol-functionalized MCM-41 mesoporous silicas and its application in Cu(II), Pb(II), Ag(I), and Cr(III) removal

    Energy Technology Data Exchange (ETDEWEB)

    Wu Shengju; Li Fengting, E-mail: fengting@tongji.edu.cn; Xu Ran; Wei Shihui [Tongji University, State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering (China); Li Guangtao [Tsinghua University, Department of Chemistry (China)

    2010-08-15

    Thiol-functionalized MCM-41 mesoporous silicas were synthesized via evaporation-induced self-assembly. The mesoporous silicas obtained were characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption analysis, Fourier transform infrared spectroscopy (FTIR), elemental analysis (EA), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The products were used as adsorbents to remove heavy metal ions from water. The mesoporous silicas (adsorbent A) with high pore diameter (centered at 5.27 nm) exhibited the largest adsorption capacity, with a BET surface area of 421.9 m{sup 2} g{sup -1} and pore volume of 0.556 cm{sup 3-1}. Different anions influenced the adsorption of Cu(II) in the order NO{sub 3}{sup -} < OAc{sup -} < SO{sub 4}{sup 2-} < CO{sub 3}{sup 2-} < Cit{sup -} < Cl{sup -}. Analysis of adsorption isotherms showed that Cu{sup 2+}, Pb{sup 2+}, Ag{sup +}, and Cr{sup 3+} adsorption fit the Redlich-Peterson nonlinear model. The mesoporous silicas synthesized in the work can be used as adsorbents to remove heavy metal ions from water effectively. The removal rate was high, and the adsorbent could be regenerated by acid treatment without changing its properties.

  15. short communication mesoporous molecular sieve mcm-41 ...

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    An efficient synthesis of 3,4-dihydro-2(1H)-pyrimidinones and -thiones using MCM-41 as the catalyst from an .... TiO2. 3. 88. [40]. 10. MCM-41. 2. 87. This work a Isolated yields. M.p. (ºC). Entry. R. X Product ... organic synthesis. This simple ...

  16. MCM41有序介孔SiO2表面接枝PMMA的制备及其对PMMA基聚电解质膜的改性作用研究%Preparation of Poly (methyl methacrylate) grafted Ordered Mesoporous Silica(MCM41) and Its Effect in Modifying PMMA-based Polymer Electrolyte

    Institute of Scientific and Technical Information of China (English)

    徐峰; 徐立新; 陈枫; 杨晋涛; 钟明强

    2012-01-01

    The PMMA-grafted ordered mesoporous silica (MSM41-g-PMMA) was firstly prepared by surface-initiated atom transfer radical polymerization of MMA from both interior and exterior surface of MCM41 particles. A series of PM-MA-based composite polymer electrolyte membrances were then obtained by solution casting method using propylene carbonate (PC) as plasticizer and the MCM41-g-PMMA as filler. The influence of various factors on the ionic conductivi-ty of PMMA-based composite polymer electrolyte was assessed including the loading amount of the MCM41-g-PMMA, surface modification of MCM41 and temperature as well. The results from infrared spectroscopy (IR), thermogravimetry (TGA),high resolution transmittance electron microscopy(HRTEM),small-angle X-ray diffraction(SAXRD), confirmed that the PMMA could be successfully grafted on the surface of MCM41. The results of alternating current (AC) impedance testing and differential scanning calorimetry (DSC) showed that the PMMA-based polymer electrolyte, com-posited with the MCM41-g-PMMA, exhibits higher ionic conductivity and better thermal stability compared to the bare MCM41-filled system.%通过表面引发原子转移自由基聚合技术(SI-ATRP)使聚甲基丙烯酸甲酯(PMMA)接枝于有序介孔氧化硅(MCM41)粒子的孔道内外表面,制得表面PMMA接枝的MCM41复合粒子(MCM41-g-PM-MA).进一步利用增塑剂碳酸丙烯酯(PC)与所得的MCM41-g-PMMA共同对PMMA基聚合物电解质膜进行改性,通过溶液浇铸工艺制得PMMA基复合型聚电解质膜.着重考察了MCM41-g-PMMA填充比例、MCM41表面PMMA接枝以及温度等因素对上述体系离子电导率的影响.红外光谱(FTIIR)、热重(TGA)、高倍透射电镜(HRTEM)、小角X射线衍射(SAXRD)分析结果表明:PMMA已成功接枝于MCM41粒子的孔道内外表面.交流阻抗测试、差示扫描量热分析(DSC)表明:较改性前的MCM41填充体系,MCM41-g-PMMA填充的PMMA膜具有更优的离子电导率,同时具有更佳的热稳定性能.

  17. Amino-functionalized mesoporous MCM-41 silica as an efficient adsorbent for water treatment: batch and fixed-bed column adsorption of the nitrate anion

    Science.gov (United States)

    Ebrahimi-Gatkash, Mehdi; Younesi, Habibollah; Shahbazi, Afsaneh; Heidari, Ava

    2015-11-01

    In the present study, amino-functionalized Mobil Composite Material No. 41 (MCM-41) was used as an adsorbent to remove nitrate anions from aqueous solutions. Mono-, di- and tri-amino functioned silicas (N-MCM-41, NN-MCM-41 and NNN-MCM-41) were prepared by post-synthesis grafting method. The samples were characterized by means of X-ray powder diffraction, FTIR spectroscopy, thermogravimetric analysis, scanning electron microscopy and nitrogen adsorption-desorption. The effects of pH, initial concentration of anions, and adsorbent loading were examined in batch adsorption system. Results of adsorption experiments showed that the adsorption capacity increased with increasing adsorbent loading and initial anion concentration. It was found that the Langmuir mathematical model indicated better fit to the experimental data than the Freundlich. According to the constants of the Langmuir equation, the maximum adsorption capacity for nitrate anion by N-MCM-41, NN-MCM-41 and NNN-MCM-41 was found to be 31.68, 38.58 and 36.81 mg/g, respectively. The adsorption kinetics were investigated with pseudo-first-order and pseudo-second-order model. Adsorption followed the pseudo-second-order rate kinetics. The coefficients of determination for pseudo-second-order kinetic model are >0.99. For continuous adsorption experiments, NNN-MCM-41 adsorbent was used for the removal of nitrate anion from solutions. Breakthrough curves were investigated at different bed heights, flow rates and initial nitrate anion concentrations. The Thomas and Yan models were utilized to calculate the kinetic parameters and to predict the breakthrough curves of different bed height. Results from this study illustrated the potential utility of these adsorbents for nitrate removal from water solution.

  18. Zinc(II) phthalocyanines immobilized in mesoporous silica Al-MCM-41 and their applications in photocatalytic degradation of pesticides

    Energy Technology Data Exchange (ETDEWEB)

    Silva, M. [Departamento de Quimica, Universidade de Coimbra, Rua Larga, 3004-535 Coimbra (Portugal); Laboratoire de Photochimie Moleculaire et Macromoleculaire, UMR CNRS 6505, Universite Blaise Pascal, F-63177 Aubiere cedex (France); Calvete, M.J.F.; Goncalves, N.P.F.; Burrows, H.D. [Departamento de Quimica, Universidade de Coimbra, Rua Larga, 3004-535 Coimbra (Portugal); Sarakha, M. [Laboratoire de Photochimie Moleculaire et Macromoleculaire, UMR CNRS 6505, Universite Blaise Pascal, F-63177 Aubiere cedex (France); Fernandes, A.; Ribeiro, M.F. [Instituto para a Biotecnologia e Bioengenharia, Centro para a Engenharia Biologica e Quimica, Instituto Superior Tecnico - Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Azenha, M.E., E-mail: meazenha@ci.uc.pt [Departamento de Quimica, Universidade de Coimbra, Rua Larga, 3004-535 Coimbra (Portugal); Pereira, M.M., E-mail: mmpereira@qui.uc.pt [Departamento de Quimica, Universidade de Coimbra, Rua Larga, 3004-535 Coimbra (Portugal)

    2012-09-30

    Highlights: Black-Right-Pointing-Pointer Complete immobilization of zinc(II) phthalocyanines accomplished in Al-MCM-41. Black-Right-Pointing-Pointer Efficient photodegradation of model pesticides achieved using 365 nm irradiation. Black-Right-Pointing-Pointer Sodium azide experiments showed the involvement of singlet oxygen ({sup 1}O{sub 2}). - Abstract: In the present study the authors investigated a set of three new zinc(II) phthalocyanines (zinc(II) tetranitrophthalocyanine (ZnTNPc), zinc(II) tetra(phenyloxy)phthalocyanine (ZnTPhOPc) and the tetraiodide salt of zinc(II)tetra(N,N,N-trimethylaminoethyloxy) phthalocyaninate (ZnTTMAEOPcI)) immobilized into Al-MCM-41 prepared via ship-in-a-bottle methodology. The samples were fully characterized by diffuse reflectance-UV-vis spectroscopy (DRS-UV-vis), luminescence, thermogravimetric analysis (TG/DSC), N{sub 2} adsorption techniques and elemental analysis. A comparative study was made on the photocatalytic performance upon irradiation within the wavelength range 320-460 nm of these three systems in the degradation of pesticides fenamiphos and pentachlorophenol. ZnTNPc-Al-MCM-41 and ZnTTMAEOPcI-Al-MCM-41 were found to be the most active systems, with the best performance observed with the immobilized cationic phthalocyanine, ZnTTMAEOPcI-Al-MCM-41. This system showed high activity even after three photocatalytic cycles. LC-MS product characterization and mechanistic studies indicate that singlet oxygen ({sup 1}O{sub 2}), produced by excitation of these immobilized photosensitizers, is a key intermediate in the photocatalytic degradation of both pesticides.

  19. Preparation, characterization, and condensation of copper tellurolate clusters in the pores of periodic mesoporous silica MCM-41.

    Science.gov (United States)

    Kowalchuk, Collin M; Schmid, Günter; Meyer-Zaika, Wolfgang; Huang, Yining; Corrigan, John F

    2004-01-12

    The copper-tellurolate cluster [(Cu(6)(TePh)(6)(PPh(2)Et)(5)] has been loaded into the pores of MCM-41 by solid-state impregnation techniques. It was found that the best loading conditions are 110 degrees C and 10(-)(3) Torr static vacuum. The resulting material was analyzed by powder X-ray diffraction (PXRD), nitrogen adsorption isotherms, thermogravimetric analysis (TGA), (31)P CP MAS NMR spectroscopy, and TEM. It was observed that loading is accompanied by loss of the phosphine shell, with retention of the copper-tellurium core. Condensation of the impregnated material may proceed thermally or photochemically. Thermal condensation results in the formation of Cu(2)Te nanoparticles as demonstrated by PXRD, and TEM data suggests that the process has taken place inside the pores of MCM-41. Photochemical condensation yields larger metal-chalcogen clusters in the pores as suggested by the result of UV-vis diffuse reflectance spectroscopy and TEM measurements.

  20. Application of novel Polypyrrole/thiol-functionalized zeolite Beta/MCM-41 type mesoporous silica nanocomposite for adsorption of Hg{sup 2+} from aqueous solution and industrial wastewater: Kinetic, isotherm and thermodynamic studies

    Energy Technology Data Exchange (ETDEWEB)

    Javadian, Hamedreza, E-mail: Hamedreza.Javadian@yahoo.com [Department of Chemical Engineering, Shahrood Branch, Islamic Azad University, Shahrood, Islamic Republic of Iran (Iran, Islamic Republic of); Taghavi, Mehdi [Polymer Chemistry Research Laboratory, Department of Chemistry, University of Mazandaran, Babolsar, 47416-95447, Islamic Republic of Iran (Iran, Islamic Republic of)

    2014-01-15

    Hierarchical zeolite consists of both microporous and unordered mesoporous structures. A composite of Polypyrrole/thiol-functionalized Beta/MCM-41 (PPy/SH-Beta/MCM-41) was prepared, characterized by FE-SEM, FT-IR, XRD, TGA and BET analysis and applied in the investigation of its adsorption characteristics for the removal of Hg{sup 2+} ions from aqueous solutions. Thiol-functionalized Beta/MCM-41 (SH-Beta/MCM-41) was prepared by 3-mercaptopropyltrimethoxysilane (MPTMS) in the presence of aerosil-200 as a silica source by two-step hydrothermal crystallization procedure. Batch mode experiments were conducted and three kinetic models were used to describe the adsorption process. The experimental data fitted very well with the Pseudo-second-order kinetic model. The calculated thermodynamic parameters (ΔH, ΔS and ΔG) revealed that the adsorption of Hg{sup 2+} onto PPy/SH-Beta/MCM-41 is an endothermic and spontaneous process. It was found that temperature has a positive effect on the removal efficiency and that PPy/SH-Beta/MCM-41 is potentially able to remove Hg{sup 2+} ions from aqueous solutions at even high concentrations (400 mg L{sup −1}). The recovery of Hg{sup 2+} from the PPy/SH-Beta/MCM-41 adsorbent was found to be more than 90% using 0.5 M H{sub 2}SO{sub 4}, and the ability of the absorbent to be reused for removal of Hg{sup 2+} was investigated.

  1. Diffusion effects on formation process of mesoporous molecular sieve MCM-41

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The regular mesoporous molecular sieve MCM-41 has been investigated at different stages during its formation,using high resolution transmission electron microscopy and powder X-ray diffraction.The results not only support the liquid-crystal templating mechanism previously postulated,but allow the extension fo its scope to discribe ditails of MCM-41 formation.It has been observed that formation of the hexagonal liquid crystal phase on the one hand and of silica aggregates on the other,occurs simultaneously at the inception of gel formation and throughout the crystallisation.This process is most probably affected by diffusion of both the surfactant molecules and the oligomeric silicate ions.With this postulate it becomes possible to explain several experimental observation(both old and new)and to develop a multi-step synthesis method to grow large particles of MCM-41 using small calcined crystals of MCM-41 as seeds.

  2. Synthesis and characterization of mesoporous Mn-MCM-41 materials

    Energy Technology Data Exchange (ETDEWEB)

    Saladino, Maria Luisa, E-mail: saladinoluisa@unipa.it [Dipartimento di Chimica Fisica ' S. Cannizzaro' and INSTM UdR Palermo, Universita di Palermo, Parco d' Orleans II, Viale delle Scienze pad.17, Palermo 90128 (Italy); Kraleva, Elka; Todorova, Silvia [Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Spinella, Alberto; Nasillo, Giorgio [Centro Grandi Apparecchiature-UniNetLab, Universita di Palermo, Via Marini 14, Palermo 90128 (Italy); Caponetti, Eugenio [Dipartimento di Chimica Fisica ' S. Cannizzaro' and INSTM UdR Palermo, Universita di Palermo, Parco d' Orleans II, Viale delle Scienze pad.17, Palermo 90128 (Italy); Centro Grandi Apparecchiature-UniNetLab, Universita di Palermo, Via Marini 14, Palermo 90128 (Italy)

    2011-09-01

    Highlights: {center_dot} Manganese MCM-41 as catalyst. {center_dot} Influence of pH on the structure of MCM-41. {center_dot} Influence of manganese on the structure and activity of Mn-MCM-41. - Abstract: MCM-41 has been synthesized at two different pH using cetyl-trimethylammonium bromide (CTAB) surfactant as template and adding the silica precursor to aqueous solutions containing CTAB. The obtained solids were calcined at 600 deg. C for 4 h. Mn-MCM-41 powders with different Mn/Si molar ratios were prepared using the incipient wetness method, followed by calcination at 550 deg. C for 5 h. At the end of the impregnation process the powders colour changed from white to brown whose intensity depends on manganese quantity. The materials characterization was performed by X-ray diffraction, N{sub 2} adsorption, {sup 29}Si Cross Polarization-Magic Angle Spinning NMR, and X-ray Photoelectron Spectroscopy. The effects of the manganese quantity and of the structural characteristic of the MCM-41 support were studied. The catalytic activity of the prepared systems was evaluated in a complete n-hexane oxidation.

  3. Mesoporous silica based MCM-41 as solid-phase extraction sorbent combined with micro-liquid chromatography-quadrupole-mass spectrometry for the analysis of pharmaceuticals in waters.

    Science.gov (United States)

    Dahane, S; Martínez Galera, M; Marchionni, M E; Socías Viciana, M M; Derdour, A; Gil García, M D

    2016-05-15

    This paper reports the first application of the silica based mesoporous material MCM-41 as a sorbent in solid phase extraction, to pre-concentrate pharmaceuticals of very different polarity (atenolol, nadolol, pindolol, timolol, bisoprolol, metoprolol, betaxolol, ketoprofen, naproxen, ibuprofen, diclofenac, tolfenamic acid, flufenamic acid and meclofenamic acid) in surface waters. The analytes were extracted from 100mL water samples at pH 2.0 (containing 10(-3) mol/L of sodium chloride) by passing the solution through a cartridge filled with 100 mg of MCM-41. Following elution, the pharmaceuticals were determined by micro-liquid chromatography and triple quadrupole-mass spectrometry. Two selected reaction monitoring transitions were monitored per compound, the most intense one being used for quantification and the second one for confirmation. Matrix effect was found in real waters for most analytes and was overcome using the standard addition method, which compared favorably with the matrix matched calibration method. The detection limits in solvent (acetonitrile:water 10:90, v/v) ranged from 0.01 to 1.48 μg/L and in real water extracts from 0.10 to 3.85 μg/L (0.001-0.0385 μg/L in the water samples). The quantitation limits in solvent were in the range 0.02-4.93 μg/L, whereas in real water extracts were between 0.45 and 10.00 μg/L (0.0045 and 0.1000 μg/L in the water samples). When ultrapure water samples were spiked at two concentration levels of each pharmaceutical (0.1 and 0.2 μg/L) and quantified using solvent based calibration graphs, recoveries were near 100%. However, recoveries for most pharmaceuticals were comparable or better than de described above, when river water samples (spiked at the same concentration levels) were quantified by the standard addition method and slightly worse using the matrix matched calibration method. Five real samples (two rivers, one dam and two fountain water samples) were analyzed by the developed method, atenolol

  4. Selective Preparation of trans-Carveol over Ceria Supported Mesoporous Materials MCM-41 and SBA-15

    Directory of Open Access Journals (Sweden)

    Nariman F. Salakhutdinov

    2013-05-01

    Full Text Available Ce-modified mesoporous silica materials MCM-41 and SBA-15, namely 32 wt % Ce–Si–MCM-41, 16 wt % Ce–H–MCM-41 and 20 wt % Ce–Si–SBA-15, were prepared, characterized and studied in the selective preparation of trans-carveol by α-pinene oxide isomerization. The characterizations of these catalysts were performed using scanning electron microscopy, X-ray photoelectron spectroscopy, nitrogen adsorption and FTIR pyridine adsorption. Selective preparation of trans-carveol was carried out in the liquid phase in a batch reactor. The activity and the selectivity of catalyst were observed to be influenced by their acidity, basicity and morphology of the mesoporous materials. The formation of trans-carveol is moreover strongly influenced by the basicity of the used solvent and in order to achieve high yields of this desired alcohol it is necessary to use polar basic solvent.

  5. Enthalpy and interfacial free energy changes of water capillary condensed in mesoporous silica, MCM-41 and SBA-15.

    Science.gov (United States)

    Kittaka, Shigeharu; Ishimaru, Shinji; Kuranishi, Miki; Matsuda, Tomoko; Yamaguchi, Toshio

    2006-07-21

    The effect of confinement on the solid-liquid phase transitions of water was studied by using DSC and FT-IR measurements. Enthalpy changes upon melting of frozen water in MCM-41 and SBA-15 were determined as a function of pore size and found to decrease with decreasing pore size. The melting point also decreased almost monotonically with a decrease in pore size. Analysis of the Gibbs-Thomson relation on the basis of the thermodynamic data showed that there were two stages of interfacial free energy change after the constant region, i.e., below a pore size of 6.0 nm: a gradual decrease down to 3.4 nm and another decrease after a small jump upward. This fact demonstrates that the simple Gibbs-Thomson relation, i.e., a linear relation between the melting point change and the inverse pore size, is limited to the range not far from the melting point of bulk water. FT-IR measurements suggest that the decrease in enthalpy change and interfacial free energy change with decreasing pore size reflect the similarity of the structures of both liquid and solid phases of water in smaller pores at lower temperatures.

  6. Comparison of Kinetic Study of CTMA+ Removal of Molecular Sieve Ti-MCM-41 Synthesized with Natural and Commercial Silica

    OpenAIRE

    Fontes,Maria do Socorro Braga; Melo,Dulce Maria de Araújo; Costa,Cintia de Castro; Braga,Renata Martins; Melo,Marcus Antonio de Freitas; Alves,José Antônio Barros Leal Reis

    2015-01-01

    This work aimed to determine and compare the apparent activation energy, involved in thermal decomposition of CTMA+ from the pores of Ti-MCM-41 synthesized by two different source of silica in order to evaluate their influence in the template removal. The molecular sieves Ti-MCM-41 were synthesized using rice husk ash (RHA), as alternative low cost source of silica, and commercial silica gel, obtaining two mesoporous material by hydrothermal synthesis of gel molar composition of: 1.0 CTMABr: ...

  7. Characterization of AlMCM-41 synthesized with rice husk silica and utilization as supports for platinumiron catalysts

    Directory of Open Access Journals (Sweden)

    J. Chumee

    2009-06-01

    Full Text Available RH-MCM-41 was synthesized by using silica from rice husk and further modified to increase acidity by adding Al with grafting method with Si/Al ratio of 75 and 25. The resulting materials were referred to as RH-AlMCM-41(75 and RH-AlMCM-41(25. The XRD spectra of all RH-AlMCM-41 confirmed a mesoporous structure of MCM-41. Surface areas of all RH-AlMCM-41 were in the range of 700-800 m²/g, lower than that of the parent RH-MCM-41, which was 1230 m²/g. After Al addition the Si/Al ratios of RHAlMCM-41(75 and RH-AlMCM-41(25 were higher than that of the parent RH-MCM-41. The RH-AlMCM41 materials were used as supports for bimetallic platinum-iron catalysts, denoted as Pt-Fe/RH-AlMCM-41, with Pt and Fe amounts of 0.5 and 5.0% by weight, respectively. Results from TPR indicated that the presenceof Al might assist the interaction between Pt and Fe as the reduction temperature of iron oxides shifted to a lower value. All catalysts were active for phenol hydroxylation using H2O2 as an oxidant, for which the highest conversions were observed on the RH-MCM-41 material with the highest surface area. The acidity of the supports did not present a significant role in improving the catalytic performance.

  8. Selective catalysis utilizing bifunctionalized MCM-41 mesoporous materials

    Energy Technology Data Exchange (ETDEWEB)

    Strosahl, Kasey Jean [Iowa State Univ., Ames, IA (United States)

    2005-01-01

    Selective catalysis is a field that has been under intense investigation for the last 100 years. The most widely used method involves catalysts with stereochemical selectivity. In this type of catalysis, the catalyst controls which reactants will be transformed into the desired product. The secret to employing this type of catalysis, though, is to design the proper catalyst, which can be difficult. One may spend as much time developing the catalyst as spent separating the various products achieved. Another method of selective catalysis is now being explored. The method involves utilizing a multifunctional mesoporous silica catalyst with a gate-keeping capability. Properly functionalized mesoporous materials with well-defined pore morphology and surface properties can provide an ideal three-dimensional environment for anchoring various homogeneous catalysts. These materials can circumvent the multi-sited two-dimensional nature most heterogeneous systems have without adversely impacting the reactant diffusivity. These single-site nanostructured catalysts with ordered geometrical structure are advantageous in achieving high selectivity and reactivity. Mesoporous materials can be prepared to include pores lined homogeneously with tethered catalysts via co-condensation. Additionally, these materials can be reacted with another (RO)3Si~Z group by using the traditional grafting method; this group is anchored predominantly at the entrances to the pores rather than inside the pores. Thus, if these ~Z groups are chosen properly, they can select certain molecules to enter the pores and be converted to products (Scheme 1). In such multifunctional catalysts, the selectivity depends on the discrimination of the gatekeeper. Gate-keeping MCM-41 materials are at the forefront of catalytic substances.

  9. MCM-41 ordered mesoporous molecular sieves synthesis and characterization

    Directory of Open Access Journals (Sweden)

    Rogério A.A. Melo

    1999-07-01

    Full Text Available The aim of this work was to study the hydrothermal synthesis of Si and SiAlMCM-41 performed under both autogenic pressure and refluxing conditions. XRD data showed that the MCM-41 phase may be formed by both processes and that the synthesized material in the presence of Al and/or under reflux presents the hexagonally arrangement of less ordered mesopores. However, as verified by XRD and physisorption data, the order was improved with higher synthesis times. 29Si and 1H - 29Si C/P MAS NMR spectra showed that a great part of the Si atoms exists as silanol groups which originate resonance peaks at -110, -100 and -91 ppm. The presence of Al atoms may generate Si(3Si, Al and Si(2Si, 2Al environments which might be contributing to resonance peaks at -100 and -91 ppm. The 27Al MAS NMR spectrum of the as synthesized AlSiMCM-41 showed a resonance peak of tetrahedral framework aluminum close to 53 ppm and two others, one close to 14 ppm attributed to Al(H2O6+3 species and the other a weak signal close to 32 ppm attributed to pentacoordinated Al. 27Al MAS NMR spectra of the calcined sample showed a peak at 0 ppm corresponding to an hexacoordinated extra-framework aluminum formed during calcination.

  10. Cumene cracking on modified mesoporous material type MCM-41

    Directory of Open Access Journals (Sweden)

    Ahmed Belhakem

    2006-06-01

    Full Text Available The effect of ionic exchange degree of aluminated mesoporous materials H(X-AlMCM-41 materials, the method of its exchange mode and its grains form were investigated for the mesoporous catalytic activity in the cumene (i.e. isopropylbenzene cracking reaction. Benzene, propylene and xylene derivatives are the main products of this reaction. Olefins like butene and pentene appeared as the products of secondary reactions. No saturated hydrocarbons, except traces of butane, nor ethylbenzene and toluene were formed and seemed to be typical products of secondary reactions obtained with HNaY zeolites. Generally the exchanged H(X-AlMCM-41 materials by the substitution of Na+ by NH4+ are more active than those exchanged directly with acid solution (substitution of Na+ by H+ even if both the two methods used exhibit a comparable content of acid sites within catalysts at a low exchange degrees. However, the first method of exchange has exhibited an important acidity for mesoporous materials when the ionic exchange degree was increased up to 90%; it was probably due not only to the percentage of exchanged degree but also to the distribution of acid sites within the materials.

  11. Synthesis and Characterization of Mesoporous Silicon Oxynitride MCM-41 with High Nitrogen Content

    Institute of Scientific and Technical Information of China (English)

    ZHANG Cunman; XU Zheng; LIU Qian

    2005-01-01

    Mesoporous silicon oxynitrides MCM-41 were synthesized successfully. The resulting materials not only have high nitrogen contents and good structural characteristics of MCM-41 (high surface area, narrow pore size distribution and good order), but also are amorphous. The composition and structure of the materials were investigated by CNH element analysis, XPS, Si MAS NMR, XRD, HRTEM and N2 sorption, respectively. Mesoporous silicon oxynitrides MCM-41 with a high nitrogen content are still non-crystal (amorphous).

  12. MCM-41 mesoporous silica nanoparticles functionalized with aptamer and radiolabelled with {sup 90}Y and {sup 159}Gd as a potential therapeutic agent against colorectal cancer; Nanoparticulas de silica mesoporosa MCM-41 funcionalizadas com aptamero e radiomarcadas com {sup 90}Y e {sup 159}Gd como um potencial agente terapeutico contra cancer colorretal

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Carolina de Aguiar

    2014-06-01

    Colorectal cancer (CRC) is a malignancy that affects large intestine and rectum, and it is the most common malignancy of the gastrointestinal tract, the third most commonly diagnosed type of cancer in the world and the second leading cause of cancer-related death in the United States. Nowadays, available therapeutic procedures for this type of cancer are limited and ineffective. Conventional radiotherapy is not an often used approach in the treatment of CRC due to the fact that peristaltic movements hamper the targeting of ionizing radiation and this type of treatment is used as adjuvant and palliative to control symptoms. Therefore, surgical intervention is the primary therapeutic choice against this disease. Researches based on the combination of radioisotopes and nanostructured carriers systems have demonstrated significant results in improving the selectivity action as well as reducing the radiation dose into healthy tissues. MCM-41 mesoporous silica nanoparticles have unique characteristics such as high surface area and well-defined pore diameters making these nanoparticles an ideal candidate of therapeutic agent carrier. Thus, the objective of this work is to synthesize and characterize MCM-41 mesoporous silica nanoparticles conjugated with yttrium-90 and gadolinium-159 and evaluate this system as a potential therapeutic agent. The nanoparticles were synthesized via sol-gel method. The sample was characterized using FTIR, SAXS, PCS, Zeta Potential analysis, Thermal analysis, CHN elemental analysis, nitrogen adsorption, scanning and transmission electron microscopy. The ability to incorporate Y{sup +3} and Gd{sup +3} ion was determined in vitro using different ratios (1:1, 1:3, 1:5 v/v) of YCL{sub 3} and Gd{sub 2}O{sub 3} and silica nanoparticles dispersed in saline, pH 7.4. The non-incorporated Y{sup +3} and Gd{sup +3} ions were removed by ultracentrifugation procedure and the concentration of ions in the supernatant was determined by ICP-AES. Cell viability

  13. A study on hydrogen-storage behaviors of nickel-loaded mesoporous MCM-41.

    Science.gov (United States)

    Park, Soo-Jin; Lee, Seul-Yi

    2010-06-01

    The objective of the present work was to investigate the possibility of improving the hydrogen-storage capacity of mesoporous MCM-41 containing nickel (Ni) oxides (Ni/MCM-41). The MCM-41 and Ni/MCM-41 were prepared using a hydrothermal process as a function of Ni content (2, 5, and 10 wt.% in the MCM-41). The surface functional groups of the Ni/MCM-41 were identified by Fourier transform infrared spectroscopy (FTIR). The structure and morphology of the Ni/MCM-41 were characterized by X-ray diffraction (XRD) and field emission transmission electron microscopy (FE-TEM). XRD results showed a well-ordered hexagonal pore structure; FE-TEM also revealed, as a complementary technique, the structure and pore size. The textural properties of the Ni/MCM-41 were analyzed using N(2) adsorption isotherms at 77 K. The hydrogen-storage capacity of the Ni/MCM-41 was evaluated at 298 K/100 bar. It was found that the presence of Ni on mesoporous MCM-41 created hydrogen-favorable sites that enhanced the hydrogen-storage capacity by a spillover effect. Furthermore, it was concluded that the hydrogen-storage capacity was greatly influenced by the amount of nickel oxide, resulting in a chemical reaction between Ni/MCM-41 and hydrogen molecules.

  14. Lysine-Grafted MCM-41 Silica as an Antibacterial Biomaterial

    Directory of Open Access Journals (Sweden)

    María F. Villegas

    2017-09-01

    Full Text Available This paper proposes a facile strategy for the zwitterionization of bioceramics that is based on the direct incorporation of l-lysine amino acid via the ε-amino group onto mesoporous MCM-41 materials. Fourier transform infrared (FTIR studies of lysine-grafted MCM-41 (MCM-LYS simultaneously showed bands at 3080 and 1540 cm−1 and bands at 1625 and 1415 cm−1 corresponding to -NH3+/COO− pairs, which demonstrate the incorporation of the amino acid on the material surface keeping its zwitterionic character. Both elemental and thermogravimetric analyses showed that the amount of grafted lysine was 8 wt. % based on the bioceramic total weight. Moreover, MCM-LYS exhibited a reduction of adhesion of S. aureus and E. coli bacteria in 33% and 50%, respectively at physiological pH, as compared with pristine MCM-41. Biofilm studies onto surfaces showed that lysine functionalization elicited a reduction of the area covered by S. aureus biofilm from 42% to only 5% (88%. This research shows a simple and effective approach to chemically modify bioceramics using single amino acids that provides zwitterionic functionality, which is useful to develop new biomaterials that are able to resist bacterial adhesion.

  15. A spectroscopic study on the adsorption of cationic dyes into mesoporous AlMCM-41 materials

    Science.gov (United States)

    Zanjanchi, M. A.; Ebrahimian, A.; Alimohammadi, Z.

    2007-03-01

    Mesoporous materials loaded with dyes are of interest with respect to novel optical applications. The spectral behaviors of some dyes in these materials are considerably affected by the presence of surfactants. A comparative study has been carried out on the adsorption of the methylene blue, rhodamine 6G and thionine dyes into a surfactant-free and surfactant-containing mesoporous AlMCM-41. The ion exchange method has been employed for incorporation of the dye molecules into the structure of MCM-41. The exchangeable sites in the MCM-41 were generated prior to dye loading by isomorphous substitution of aluminum for silicon in the structure of the mesoporous material during the synthesis procedure. Diffuse reflectance measurements indicate adsorption of methylene blue and rhodamine 6G dye molecules into AlMCM-41 taken place via ion exchange at room temperature. The spectra show presence of monomer and dimer aggregates of the dyes established into the pores and surface of AlMCM-41. The ratio of dimer to monomer forms of rhodamine 6G incorporated in the surfactant-free and surfactant-containing AlMCM-41 is about one which is higher than those observed in aqueous solutions. The surfactant-containing AlMCM-41 induced destabilization and decomposition of methylene blue while uploading the dye. Degradation of this dye produces intermediate species identified as demethylated forms of methylene blue adsorbed on AlMCM-41. Our experiments revealed that kinetics of ion exchange for thionine dye is very slow at room temperature, but it become faster at higher temperatures. The spectral properties of thionine in AlMCM-41 are close to that of thionine in an aqueous solution, possibly due to high pore space in a mesoporous molecular sieve. No adsorption of thionine was observed for surfactant-containing AlMCM-41 even at higher temperatures.

  16. Modified Mesoporous Silicate MCM-41 for Zinc Ion Adsorption: Synthesis, Characterization and Its Adsorption Behavior

    Institute of Scientific and Technical Information of China (English)

    SEPEHRIAN, Harnid; WAQIF-HUSAIN, Syed; RAKHSHANDERU, Farrokh; KAMEL, Leila

    2009-01-01

    Modified MCM-41 has been prepared by bi-functionalization of thiol and amino functional groups onto mesoporous silicate MCM-41. Elemental analysis (EA), thermogravimetry analysis (TGA) and FTIR techniques were used to quantify the attachment of the thiol and amino functional groups to the mesoporous silicate pore wall.Powder X-ray diffraction (PXRD) and nitrogen adsorption techniques were used to establish the pore diameter,packing of the pores and specific surface area of the modified mesoporous silicate MCM-41. Adsorption behavior for 18 metal ions on this sorbent has been studied and discussed. This sorbent has high affinity for zinc ions against amino- or thiol-functionalized MCM-41 sorbents.

  17. Photocatalytic Degradation of Imidacloprid by Phospho- tungstic Acid Supported on a Mesoporous Sieve MCM-41

    Institute of Scientific and Technical Information of China (English)

    冯长根; 李彦周; 刘霞

    2012-01-01

    Solid catalysts consisting of polyoxometalates (POM) namely phosphotungstic acid H3PWL2040 (HPW) supported on a mesoporous sieve MCM-41 have been prepared and characterized by FT-IR, X-ray diffraction, nitrogen adsorption and high resolution transmission electron microscope (HRTEM). The HPW/MCM-41 with different HPW loadings from 10 to 60 wt% possess large specific surface area and rather uniform mesopores. Keggin structure of HPW retains on the prepared composite catalysts. The photocatalytic performance of HPW/MCM-41 was examined by degradation of a durable pesticide imidacloprid. It is found that the prepared photocatalysts exhibit high activity under irradiation of 365 nm monochromatic light. For 50 mL of imidacloprid (10 rag/L), conversion of imidacloprid using 20 mg of HPW/MCM-41 with 50 wt% loading level and calcined at 300 ℃ reaches 58.0% after 5 h irradiation.

  18. Hydrocarbon oxidation catalyzed by vanadium polyoxometalate supported on mesoporous MCM-41 under ultrasonic irradiation.

    Science.gov (United States)

    Tangestaninejad, Shahram; Mirkhani, Valiollah; Moghadam, Majid; Mohammadpoor-Baltork, Iraj; Shams, Esmaeil; Salavati, Hossein

    2008-04-01

    Vanadium polyoxometalate (PVMo) supported on mesoporous MCM-41, MCM-41-NH(2), as efficient and heterogeneous catalysts, with large surface area, for hydrocarbon oxidation with hydrogen peroxide is reported. Oxidation of the alkenes and alkanes gave product selectivities, which are similar to those observed for corresponding homogeneous catalyst. PVMo-MCM was prepared by introduction of PVMo into the mesoporous molecule sieves of MCM-41 by impregnation and adsorption techniques. The samples were characterized by X-ray diffraction (XRD), thermal gravimetric-differential thermal analysis (TG-DTA), FT-IR, scanning electron microscopy (SEM), UV-Vis and cyclic voltametry (CV). Ultrasonic irradiation has a particular effect on MCM-41 structural uniformity and reduced the reaction times and improved the product yields. In addition, the solid catalysts could be recovered and reused several times without loss of its activity.

  19. Catalytic ozonation of chlorobenzoic acid over cobalt oxide supported on MCM-41 mesoporous molecular sieves%钴负载MCM-41分子筛催化臭氧氧化水中氯代苯甲酸

    Institute of Scientific and Technical Information of China (English)

    曾俊喻; 邴吉帅; 蓝冰燕; 廖高祖; 张秋云; 李旭凯; 李来胜

    2012-01-01

    通过水热法合成介孔分子筛MCM-41,采用等体积浸渍法制备了Co负载MCM-41分子筛催化剂(Co/MCM-41).小角X-射线粉末衍射(XRD)、紫外-可见漫反射光谱(UV-vis DRS)、N2吸附-脱附等温线及透射电镜(TEM)等对催化剂的成分、结构的表征结果显示,Co/MCM-41保持了纯硅MCM-41有序的介孔结构,钴元素以钴氧化物形式存在,比表面达到772 m.2g-1.将Co/MCM-41分子筛用于催化臭氧氧化水中对氯苯甲酸(p-CBA)的研究,结果表明,在优化条件下(2%负载量和25℃反应温度),催化剂的加入显著改善了TOC去除率,达到84.6%,是单独臭氧氧化的1.6倍.%MCM-41 mesoporous molecular sieve was synthesized by a hydrothermal method and Co/MCM-41 was prepared by an incipient wetness impregnation method.The materials were characterized by a low angle X-ray powder diffraction(XRD),UV-Vis diffuse reflection spectroscopy(UV-DRS),N2 adsorption-desorption and transmission electron microscopy(TEM).The results showed that the material retained a highly ordered mesopore structure of pure silica MCM-41 and had a surface area of 772 m2·g-1,Cobalt ions mainly exist as cobalt oxide clusters distributed on the surface of molecular sieve.In this study,Co/MCM-41 mesoporous molecular sieve was used for catalytic ozonation of p-CBA.The results showed that under the optimal condition(2% cobalt load and 25 ℃),the mineralization of p-CBA increased to 84.6% in the presence of catalyst,which is 1.6 times that of ozone alone at the reaction time of 60 min.

  20. Sorption and pore condensation behavior of pure fluids in mesoporous MCM-48 silica, MCM-41 silica, SBA-15 silica and controlled-pore glass at temperatures above and below the bulk triple point

    Science.gov (United States)

    Thommes, Matthias; Köhn, Ralf; Fröba, Michael

    2002-08-01

    The pore condensation and hysteresis behavior of nitrogen and argon was studied on well-defined, ordered porous materials like MCM-48, MCM-41 silica (mode pore diameters, 2-5 nm) and SBA-15 (6.7 nm) at 87 and 77 K. A comparison with the results of similar sorption experiments carried out using more disordered adsorbents like controlled-pore glasses (CPG) (mode pore diameters, 11 and 16 nm) is made. The results show clearly that the shape of sorption isotherms (in particular the shape and the width of sorption hysteresis loops) depend both on temperature and pore diameter, i.e. the thermodynamic states of pore fluid and bulk fluid, but—in particular at temperatures below the bulk triple point—also strongly on the texture (and degree of disorder) of the porous material. Analyses of nitrogen (at 77 K) and argon (at 87 K) adsorption-desorption isotherms in MCM-48 silica lead to the conclusion that in this well-defined, interconnected pore network the desorption branch of the hysteresis loop represents the equilibrium transition. In addition, pore condensation of argon can still be observed at 77 K, i.e. ca. 6.5 K below the bulk triple point in MCM-48/41 and SBA-15 silica materials with pore diametersmesopore-size analysis of silica materials using argon sorption at 77 K.

  1. Thermal and hydrothermal stability of ZrMCM-41 mesoporous molecular sieves obtained by microwave irradiation

    Indian Academy of Sciences (India)

    T S Jiang; Y H Li; X P Zhou; Q Zhao; H B Yin

    2010-05-01

    ZrMCM-41 mesoporous molecular sieves were synthesized by using the zirconium sulfate as zirconium source and using cetyltrimethyl ammonium bromide as a template under microwave irradiation condition. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), inductive coupled plasma (ICP) technique, Fourier transform infrared spectroscopy (FT-IR) and N2 physical adsorption, respectively. The effect of the different initial ZrO2 : SiO2 molar ratio, the different thermal treatment temperature and hydrothermal treatment time on textural property was investigated. The results show that the obtained products possess a typical mesoporous structure of MCM-41 and have specific surface areas in the range of 598.1 ∼ 971.4 m2/g and average pore sizes in the range of ca. 2.46 ∼ 3.43 nm. On the other hand, the BET specific surface area and pore volume of the synthesized ZrMCM-41 mesoporous molecular sieve decrease with the increased amount of zirconium incorporated in the starting material, the rise of thermal treatment temperature and the prolonging of hydrothermal treatment time, the mesoporous ordering deteriorates. The mesoporous structure of the ZrMCM-41 mesoporous molecular sieve still retains after calcination at 750°C for 3 h or hydrothermal treatment at 100°C for 6 days, however, the mesoporous ordering is poor.

  2. Synthesis, Characterization and Application of the novel, regular mesoporous materials MCM-41 and MCM-48

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, R.

    1995-07-01

    In the application of zeolites to catalytic cracking of heavy oil fractions the need of regular solids with large pore sizes has become very obvious. The scope of this thesis was to synthesize and characterize the novel mesoporous materials MCM-41 and MCM-48 with the major emphasis laid on MCM-41. MCM-41 materials with bulk Si/Al ratios of 4, 9, 18 and {infinity} were synthesized and characterized by XRD and HREM. The catalytic cracking behaviour of Al-containing MCM-41 materials was investigated by pulse reactor studies using decalin as model feed and by Micro Activity Tests using atmospheric residue or n-hexadecane as feed. Aluminium containing MCM-41 was found to be active for the cracking of heavy oil fractions. Purely siliceous MCM-41 materials with pore sizes ranging from 18 Aa to 40 Aa were synthesized and their properties studied by means of NMR spectroscopy. The MCM-48, which is a cubic member of the M41S family with a three dimensional pore system, was studied by means of a combination of X-ray powder diffraction and HREM technique. 210 refs., 76 figs., 9 tabs.

  3. Novel acridone-modified MCM-41 type silica: Synthesis, characterization and fluorescence tuning

    Directory of Open Access Journals (Sweden)

    Maximilian Hemgesberg

    2011-06-01

    Full Text Available A Mobil Composition of Matter (MCM-41 type mesoporous silica material containing N-propylacridone groups has been successfully prepared by co-condensation of an appropriate organic precursor with tetraethyl orthosilicate (TEOS under alkaline sol–gel conditions. The resulting material was fully characterized by means of X-ray diffraction (XRD, N2-adsorption–desorption, transmission electron microscopy (TEM, IR and UV–vis spectroscopy, as well as 29Si and 13C CP-MAS NMR techniques. The material features a high inner surface area and a highly ordered two-dimensional hexagonal pore structure. The fluorescence properties of the organic chromophore can be tuned via complexation of its carbonyl group with scandium triflate, which makes the material a good candidate for solid state sensors and optics. The successful synthesis of highly ordered MCM materials through co-condensation was found to be dependent on the chemical interaction of the different precursors.

  4. Preparation and Spectroscopic Properties of Tris(2,2′-bipyridine)ruthenium(Ⅱ) Loaded in Siliceous Mesoporous MCM-41

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    [Ru(bpy)3]2+/MCM-41 composite material obtained by loading tris(2,2′-bipyridine)ruthenium(Ⅱ)([Ru(bpy)3]2+) in siliceous mesoporous MCM-41 was characterized by X-ray powder diffraction, UV-Vis absorption and emission spectroscopies. The absorption spectrum of [Ru(bpy)3]2+/MCM-41 is similar to that of [Ru(bpy)3]2+ aqueous solution, whereas its emission spectrum exhibits hypsochromic shift compared to the solution spectrum. On the other hand, the peak position of the emission spectrum of [Ru(bpy)3]2+/MCM-41 shifts towards longer wavelength when the loading amount increases.

  5. Enhanced electrorheology of conducting polyaniline confined in MCM-41 channels.

    Science.gov (United States)

    Cho, Min S; Choi, Hyoung J; Ahn, Wha-Seung

    2004-01-06

    A composite material of a silica-based mesoporous molecular sieve, MCM-41, with conducting polyaniline (PANI) inside the uniformly aligned one-dimensional channels (PANI/MCM-41) was prepared and its nanocomposite formation was confirmed through an electrical conductivity measurement. This nanocomposite particle was adopted for a dispersed phase in electrorheological (ER) fluids, and the ER property was measured using a Couette-type rotational rheometer equipped with a high voltage generator. Suspension of PANI/MCM-41 showed ER properties more enhanced than those of MCM-41 or PANI alone as a result of the anisotropic polarization of the PANI/MCM-41 nanocomposite.

  6. Characterization of platinum–iron catalysts supported on MCM-41 synthesized with rice husk silica and their performance for phenol hydroxylation

    Directory of Open Access Journals (Sweden)

    Jitlada Chumee, Nurak Grisdanurak, Arthit Neramittagapong and Jatuporn Wittayakun

    2009-01-01

    Full Text Available Mesoporous material RH-MCM-41 was synthesized with rice husk silica by a hydrothermal method. It was used as a support for bimetallic platinum−iron catalysts Pt–Fe/RH-MCM-41 for phenol hydroxylation. The catalysts were prepared by co-impregnation with Pt and Fe at amounts of 0.5 and 5.0 wt.%, respectively. The RH-MCM-41 structure in the catalysts was studied with x-ray diffraction, and their surface areas were determined by nitrogen adsorption. The oxidation number of Fe supported on RH-MCM-41 was + 3, as determined by x-ray absorption near edge structure (XANES analysis. Transmission electron microscopy (TEM images of all the catalysts displayed well-ordered structures, and metal nanoparticles were observed in some catalysts. All the catalysts were active for phenol hydroxylation using H2O2 as the oxidant at phenol : H2O2 mole ratios of 2 : 1, 2 : 2, 2 : 3 and 2 : 4. The first three ratios produced only catechol and hydroquinone, whereas the 2 : 4 ratio also produced benzoquinone. The 2 : 3 ratio gave the highest phenol conversion of 47% at 70 °C. The catalyst prepared by co-impregnation with Pt and Fe was more active than that prepared using a physical mixture of Pt/RH-MCM-41 and Fe/RH-MCM-41.

  7. Comparative studies of Zr-based MCM-41 and MCM-48 mesoporous molecular sieves: Synthesis and physicochemical properties

    Energy Technology Data Exchange (ETDEWEB)

    Chen, L.F. [Departamento de Ciencias Basicas, Universidad Autonoma Metropolitana-A, Av. San Pablo 180, Col. Reynosa-Tamaulipas, 02200 Mexico D.F. (Mexico)]. E-mail: chenlf2001@yahoo.com; Zhou, X.L. [Petroleum Processing Research Center, East China University of Science and Technology, 200237 Shanghai (China); Norena, L.E. [Departamento de Ciencias Basicas, Universidad Autonoma Metropolitana-A, Av. San Pablo 180, Col. Reynosa-Tamaulipas, 02200 Mexico D.F. (Mexico)]. E-mail: lnf@correo.azc.uam.mx; Wang, J.A. [Laboratorio de Catalisis y Materiales, SEPI-ESIQIE, Instituto Politecnico Nacional, Av. Politecnico S/N, Col. Zacatenco, 07738 Mexico D.F. (Mexico); Navarrete, J. [Grupo de Molecular Ingenieria, Instituto Mexicano del Petroleo, Eje Lazaro Cardenas 152, 07730 Mexico D.F. (Mexico); Salas, P. [Grupo de Molecular Ingenieria, Instituto Mexicano del Petroleo, Eje Lazaro Cardenas 152, 07730 Mexico D.F. (Mexico); Montoya, A. [Grupo de Molecular Ingenieria, Instituto Mexicano del Petroleo, Eje Lazaro Cardenas 152, 07730 Mexico D.F. (Mexico); Del Angel, P. [Grupo de Molecular Ingenieria, Instituto Mexicano del Petroleo, Eje Lazaro Cardenas 152, 07730 Mexico D.F. (Mexico); Llanos, M.E. [Grupo de Molecular Ingenieria, Instituto Mexicano del Petroleo, Eje Lazaro Cardenas 152, 07730 Mexico D.F. (Mexico)

    2006-12-30

    Two surfactant-templated synthetic routes are developed for the preparation of new types of mesoporous molecular sieves, Zr-MCM-41 and Zr-MCM-48, using different Si sources but keeping the same zirconium precursor (zirconium-n-propoxide). When fumed silica was used as Si precursor, a Zr-MCM-48 material of cubic structure was formed with a surface area of 654.8 m{sup 2}/g and an unimodal pore diameter distribution. It shows low stability: after calcination at 600 deg. C, the ordered structure was transformed into a relatively disordered worm-like mesostructure with many defects and silanol groups. The use of tetraethyl orthosilicate as Si source led to the formation of a Zr-MCM-41 mesoporous solid, which had good thermal stability and a highly ordered hexagonal arrangement, with a surface area 677.9 m{sup 2}/g and an uniform pore diameter distribution. Fourier transform infrared (FT-IR) characterization and {sup 29}Si NMR analysis confirm that zirconium ions indeed incorporated into the framework of the solid. The in situ FT-IR spectroscopy of pyridine adsorption reveals that both, Lewis and Broensted acid sites, were formed on the surface of these mesoporous materials. The strength and number of the Broensted acid sites of the Zr-MCM-48 solid were greater than those of the Zr-MCM-41, due to a lower degree of condensation reaction during the synthesis that led to more structural defects in the framework and more silanol groups stretching from the solid surface.

  8. Synthesis and Characterization of Amino-functionalized Meso-porous Silicate MCM-41 for Removal of Toxic Metal Ions

    Institute of Scientific and Technical Information of China (English)

    HAMID,Sepehrian; SYED,Waqif-Husain; MOHAMMAD,Ghannadi-Maragheh

    2009-01-01

    Amino-functionalized MCM-41 has been prepared by grafting amino containing functional groups onto mesoporous silicate MCM-41 and characterized by powder X-ray diffraction, N2 adsorption/desorption measure-ment, SEM, FT-IR, thermogravimetry and elemental analysis to confirm the ordered mesoporous structure and the functionalization of the amino groups. Sorption behavior for 18 metal ions on this sorbent has been studied and discussed.

  9. UTILIZATION OF RICE HUSK AS RAW MATERIAL IN SYNTHESIS OF MESOPOROUS SILICATES MCM-41

    Directory of Open Access Journals (Sweden)

    Suyanta Suyanta

    2011-12-01

    Full Text Available The research about synthesis and characterization of MCM-41 from rice husk has been done. Silica (SiO2 was extracted from rice husk by refluxing with 3M hydrochloric solution at 80 °C for 3 h. The acid-leached rice husk was filtered, washed, dried and calcined at 650 °C for 6 h lead the rough powder of rice husk silica with light brown in color. Characterization was carried out by X-ray diffraction (XRD and FTIR spectroscopy method. Rice husk silica was dissolved into the sodium hydroxide solution leading to the solution of sodium silicate, and used as silica source for the synthesis of MCM-41. MCM-41 was synthesized by hydrothermal process to the mixture prepared from 29 g of distilled water, 8.67 g of cetyltrimethyl ammonium bromide (CTMAB, 9.31 g of sodium silicate solution, and amount mL of 1 M H2SO4. Hydrothermal process was carried out at 100 °C in a teflon-lined stainless steel autoclave heated in the oven for 36 h. The solid phase was filtered, then washed with deionised water, and dried in the oven at 100 °C for 2 h. The surfactant CTMAB was removed by calcination at 550 °C for 10 h with heating rate 2 °C/min. The as-synthesized and calcined crystals were characterized by using FTIR spectroscopy, X-ray diffraction and N2 physisorption methods. In order to investigate the effect of silica source, the same procedure was carried out by using pure sodium silicate as silica source. It was concluded that silica extracted from rice husk can be used as raw materials in the synthesis of MCM-41, there is no significant difference in crystallinity and pore properties when was compared to material produced from commercial sodium silicate.

  10. Preparation and Acid Catalytic Activity of TiO2 Grafted Silica MCM-41 with Sulfate Treatment

    Institute of Scientific and Technical Information of China (English)

    Dai-shi Guo; Zi-feng Ma; Chun-sheng Yin; Qi-zhong Jiang

    2008-01-01

    TiO2 grafted silica MCM-41 catalyst with and without sulfate treatment were prepared.The structural and acid properties of these materials were investigated by XRD,N2 adsorption-desorption,element analysis,thermal analysis,Raman and FTIR measurements.Their acid-catalytic activities were evaluated using the cyclization reaction of pseudoionone.It was found that the obtained materials possess well-ordered mesostructure,and the grafted TiO2 components were in highly dispersed amorphous form.T/MCM41 without sulfation contained only Lewis acid sites,while Br(o)nsted and Lewis acidities were remarkably improved for the sulfated materials ST/MCM41 and d-ST/MCM41.T/MCM-41 was not active for the cyclization reaction of pseudoionone,but ST/MCM-41 and d-ST/MCM-41 possessed favorable catalytic activities.The catalytic performance of ST/MCM-41 was comparable with that of the commercial solid acid catalyst of Amberlyst-15,and better than that of d-ST/MCM-41,although the latter underwent a second TiO2 grafting process and accordingly had higher Ti and S content.The specific surface structure of Si-O-Ti-O-S=O in ST/MCM-41 and the bilateral induction effect of Si and S=O on Si-O-Ti bonds were speculated to account for its higher acid catalytic activity.

  11. A Thin Film Nanocomposite Membrane with MCM-41 Silica Nanoparticles for Brackish Water Purification

    Directory of Open Access Journals (Sweden)

    Mohammed Kadhom

    2016-12-01

    Full Text Available Thin film nanocomposite (TFN membranes containing MCM-41 silica nanoparticles (NPs were synthesized by the interfacial polymerization (IP process. An m-phenylenediamine (MPD aqueous solution and an organic phase with trimesoyl chloride (TMC dissolved in isooctane were used in the IP reaction, occurring on a nanoporous polysulfone (PSU support layer. Isooctane was introduced as the organic solvent for TMC in this work due to its intermediate boiling point. MCM-41 silica NPs were loaded in MPD and TMC solutions in separate experiments, in a concentration range from 0 to 0.04 wt %, and the membrane performance was assessed and compared based on salt rejection and water flux. The prepared membranes were characterized via scanning electron microscopy (SEM, transmission electron microscopy (TEM, contact angle measurement, and attenuated total reflection Fourier transform infrared (ATR FT-IR analysis. The results show that adding MCM-41 silica NPs into an MPD solution yields slightly improved and more stable results than adding them to a TMC solution. With 0.02% MCM-41 silica NPs in the MPD solution, the water flux was increased from 44.0 to 64.1 L/m2·h, while the rejection virtually remained the same at 95% (2000 ppm NaCl saline solution, 25 °C, 2068 kPa (300 psi.

  12. Adsorption of yellow dye on calcined or uncalcined Al-MCM-41 mesoporous materials

    Directory of Open Access Journals (Sweden)

    Bouhadjar Boukoussa

    2017-05-01

    Full Text Available Yellow dye (YD adsorption was carried out on some mesoporous materials such as calcined and uncalcined Al-MCM-41. These two matrices were synthesized by variation of Si/Al molar ratio (20, 40 and 80 under thermal conditions. The obtained materials were characterized by various methods: XRD diffraction (XRD, nitrogen adsorption at 77 K, Fourier transformed infrared spectroscopy (FTIR and energy dispersive spectroscopy by X-rays (EDX. Elimination of YD as a function of both pH and shaking, contacting time, and reaction temperature was studied. The uncalcined Al-MCM-41 had the highest adsorption capacities with adsorption rate of about 92%. Both the uncalcined and calcined materials which contain a very little amount of aluminum seem to have a high affinity toward YD molecules.

  13. Grafting of [(64)Cu]-TPPF20 porphyrin complex on Functionalized nano-porous MCM-41 silica as a potential cancer imaging agent.

    Science.gov (United States)

    Fazaeli, Yousef; Feizi, Shahzad; Jalilian, Amir R; Hejrani, Ali

    2016-06-01

    Mesoporous silica, MCM-41, functionalized with 3-aminopropyltriethoxysilane (APTES) was investigated as a potential drug delivery system, using [(64)Cu]-5, 10, 15, 20-tetrakis penta fluorophenyl porphyrin complex. [(64)Cu]-TPPF20 complex was grafted on functionalized MCM-41. The product was characterized by paper chromatography, FTIR spectroscopy, low angle X-ray diffraction, CHN and TGA/DTA analyses and atomic force microscopy. The biological evaluations of the grafted complex, [(64)Cu]-TPPF20@NH2-MCM-41, were done in Fibrosarcoma tumor-bearing Sprague-Dawley rats using scarification studies and Sopha DST-XL Dual-Head SPECT system. The actual loading amount of aminopropyl groups was found about 1.6mmol per gram of final silica. The specific activity of the final compound was found to be 3Ci/g. Amine functionalized MCM-41 was found to be a good platform for theranostic radiopharmaceuticals such as copper-64 complexes. Considering the accumulation of the tracer in tumor cells, fast wash-out from normal tissues, the short half-life copper-64 and less imposed radiation doses to patients, [(64)Cu]-TPPF20@NH2-MCM-41 can potentially be a suitable candidate for tumor imaging applications and future PET studies.

  14. Improvement of surface acidity and structural regularity of Zr-modified mesoporous MCM-41

    Energy Technology Data Exchange (ETDEWEB)

    Chen, L.F. [Departamento de Ciencias Basicas, Universidad Autonoma Metropolitana-A, Av. San Pablo 180, Col. Reynosa-Tamaulipas, 02200 Mexico D.F. (Mexico)]. E-mail: chenlf2001@yahoo.com; Norena, L.E. [Departamento de Ciencias Basicas, Universidad Autonoma Metropolitana-A, Av. San Pablo 180, Col. Reynosa-Tamaulipas, 02200 Mexico D.F. (Mexico); Navarrete, J. [Grupo de Molecular Ingenieria, Instituto Mexicano del Petroleo, Eje Lazaro Cardenas 152, 07730 Mexico D.F. (Mexico); Wang, J.A. [Laboratorio de Catalisis y Materiales, SEPI-ESIQIE, Instituto Politecnico Nacional, Av. Politecnico S/N, Col. Zacatenco, 07738 Mexico D.F. (Mexico)

    2006-06-10

    This work reports the synthesis and surface characterization of a Zr-modified mesoporous MCM-41 solid with an ordered hexagonal arrangement, prepared through a templated synthesis route, using cetyltrimethylammonium chloride as the template. The surface features, crystalline structure, textural properties and surface acidity of the materials were characterized by in situ Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), N{sub 2} physisorption isotherms, {sup 29}Si MAS-NMR and in situ FT-IR of pyridine adsorption. It is evident that the surfactant cations inserted into the network of the solids during the preparation could be removed by calcination of the sample above 500 deg. C. The resultant material showed a large surface area of 680.6 m{sup 2} g{sup -1} with a uniform pore diameter distribution in a very narrow range centered at approximately 2.5 nm. Zirconium incorporation into the Si-MCM-41 framework, confirmed by {sup 29}Si MAS-NMR analysis, increased not only the wall thickness of the mesopores but also the long-range order of the periodically hexagonal structure. Both, Lewis and Broensted acid sites, were formed on the surface of the Zr-modified MCM-41 solid. Compared to Si-MCM-41 on which only very weak Lewis acid sites were formed, the densities of both Lewis and Broensted acid sites and the strength of the acidity on the Zr-modified sample were significantly increased, indicating that the incorporation of zirconium greatly enhances the acidity of the material.

  15. Encapsulation of Eu(TTA)3 into MCM-41 Mesoporous Molecular Sieve by Sol-Gel Method

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The rare earth complex Eu(TTA)3 was successfully encapsulated into MCM-41 mesoporous molecular sieve by the addition of the complex into the sol-gel mixture for the synthesis of MCM-41 mesoporous material under microwave radiation. The as-synthesized MCM-41-hosted Eu(TTA)3 mesophase was confirmed to possess hexagonally ordered mesostructure and a uniform crystal size of about 30 nm with XRD and HRTEM techniques. Moreover, the IR spectrum, photoluminescence effect and fluorescence lifetime of the Eu(TTA)3/MCM-41 hybrid were also studied. An increase in Stokes' shift and no change in luminescence lifetime were observed to the resultant mesophase in comparison with Eu(TTA)3 in ethanol solution.

  16. ZnFe2O4-TiO2 nanoparticles within mesoporous MCM-41.

    Science.gov (United States)

    Tang, Aidong; Deng, Yuehua; Jin, Jiao; Yang, Huaming

    2012-01-01

    A novel nanocomposite ZnFe(2)O(4)-TiO(2)/MCM-41 (ZTM) was synthesized by a sol-gel method and characterized through X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), N(2) adsorption-desorption, Raman spectroscopy, and ultraviolet visible (UV-vis) spectrophotometry. The results confirmed the incorporation of ZnFe(2)O(4)-TiO(2) nanoparticles inside the pores of the mesoporous MCM-41 host without destroying its integrity. ZnFe(2)O(4) nanoparticles can inhibit the transformation of anatase into rutile phase of TiO(2). Incorporation of ZnFe(2)O(4)-TiO(2) within MCM-41 avoided the agglomeration of nanoparticles and reduced the band gap energy of TiO(2) to enhance its visible light photocatalytic activity. UV-vis absorption edges of ZTM nanocomposites redshifted with the increase of Zn/Ti molar ratio. The nanocomposite approach could be a potential choice for enhancing the photoactivity of TiO(2), indicating an interesting application in the photodegradation and photoelectric fields.

  17. ZnFe2O4-TiO2 Nanoparticles within Mesoporous MCM-41

    Directory of Open Access Journals (Sweden)

    Aidong Tang

    2012-01-01

    Full Text Available A novel nanocomposite ZnFe2O4-TiO2/MCM-41 (ZTM was synthesized by a sol-gel method and characterized through X-ray diffraction (XRD, high-resolution transmission electron microscopy (HRTEM, N2 adsorption-desorption, Raman spectroscopy, and ultraviolet visible (UV-vis spectrophotometry. The results confirmed the incorporation of ZnFe2O4-TiO2 nanoparticles inside the pores of the mesoporous MCM-41 host without destroying its integrity. ZnFe2O4 nanoparticles can inhibit the transformation of anatase into rutile phase of TiO2. Incorporation of ZnFe2O4-TiO2 within MCM-41 avoided the agglomeration of nanoparticles and reduced the band gap energy of TiO2 to enhance its visible light photocatalytic activity. UV-vis absorption edges of ZTM nanocomposites redshifted with the increase of Zn/Ti molar ratio. The nanocomposite approach could be a potential choice for enhancing the photoactivity of TiO2, indicating an interesting application in the photodegradation and photoelectric fields.

  18. Hydrothermal synthesis of meso porous silica MCM-41 using commercial sodium silicate

    Energy Technology Data Exchange (ETDEWEB)

    Melendez O, H. I.; Mercado S, A.; Garcia C, L. A.; Castruita, G.; Perera M, Y A., E-mail: ivan_melendez380@hotmail.com [Centro de Investigacion en Quimica Aplicada, Bldv. Enrique Reyna Hermosillo No. 140, Saltillo 25294, Coahuila (Mexico)

    2013-08-01

    In this work, ordered meso porous silica MCM-41 was prepared by hydrothermal synthesis using industrial-grade sodium silicate (Na{sub 2}SiO{sub 3}) as silica source, hexadecyltrimethyl-ammonium bromide (CTAB) as template agent and ethyl acetate as ph regulator. The influence of CTAB/SiO{sub 2} molar ratio, reaction time, aging temperature, and co-surfactant type on the structural and morphological properties of the obtained silica was studied. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption-desorption isotherms. Ordered meso porous MCM-41 silica was obtained at 80 C by using a range of CTAB/SiO{sub 2} molar ratio from 0.35 to 0.71 and reaction times up to 72 h and isopropanol (i-Pr OH) as co-surfactant. (Author)

  19. Desorption of water from hydrophilic MCM-41 mesopores: positron annihilation, FTIR and MD simulation studies

    Science.gov (United States)

    Maheshwari, Priya; Dutta, D.; Muthulakshmi, T.; Chakraborty, B.; Raje, N.; Pujari, P. K.

    2017-02-01

    The desorption mechanism of water from the hydrophilic mesopores of MCM-41 was studied using positron annihilation lifetime spectroscopy (PALS) and attenuated total reflection Fourier transform infrared spectroscopy supplemented with molecular dynamics (MD) simulation. PALS results indicated that water molecules do not undergo sequential evaporation in a simple layer-by-layer manner during desorption from MCM-41 mesopores. The results suggested that the water column inside the uniform cylindrical mesopore become stretched during desorption and induces cavitation (as seen in the case of ink-bottle type pores) inside it, keeping a dense water layer at the hydrophilic pore wall, as well as a water plug at both the open ends of the cylindrical pore, until the water was reduced to a certain volume fraction where the pore catastrophically empties. Before being emptied, the water molecules formed clusters inside the mesopores. The formation of molecular clusters below a certain level of hydration was corroborated by the MD simulation study. The results are discussed.

  20. Synthesis of AL-MCM-41 using gravel drilling the source of silica from wells drilling; Sintese do AL-MCM-41 usando como fonte de silica o cascalho de perfuracao de pocos de petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Fontes, M.S.B.; Costa, C.C.; Melo, D.M.A.; Viana, L.M.; Viana, S.O.; Santos, L.M., E-mail: socorro.fontes@Yahoo.com.br [Universidade Federal do Rio grande do Norte (UFRN), Natal, RN (Brazil)

    2016-07-01

    The aim of this study was to synthesize Al-MCM-41 using gravel drilling as alternative source of silica, aiming at sustainable production and low cost. For hydrothermal synthesis of Al-MCM-41 was used gravel and sodium silicate as source of silica and sodium, respectively. The structural driver used was cetyltrimethylammonium bromide (CTMABr) and solvent distilled water. The hydrothermal synthesis was conducted at 100 ° C in a Teflon autoclave 45 ml jacketed stainless steel for a period of 120 hours with daily correcting pH (range 9-10) using 30% acetic acid. The material obtained was filtered, washed, dried at 100 ° C for 3 hours and then calcined at 550 ° C for 2 hours. Then it was characterized by XRD, FTIR and TG. For the results of characterization has been observed that the use of the gravel drilling as a source of silica was promising alternative for producing a mesoporous material with a high degree of hexagonal ordering. (author)

  1. Direct electrochemistry and electrocatalytic properties of hemoglobin immobilized on a carbon ionic liquid electrode modified with mesoporous molecular sieve MCM-41.

    Science.gov (United States)

    Li, Yonghong; Zeng, Xiandong; Liu, Xiaoying; Liu, Xinsheng; Wei, Wanzhi; Luo, Shenglian

    2010-08-01

    The direct electron transfer and electrocatalysis of hemoglobin (Hb) entrapped in the MCM-41 modified carbon ionic liquid electrode (CILE) were investigated by using cyclic voltammetry in 0.10 M pH 7.0 phosphate buffer solution (PBS). Due to its uniform pore structure, high surface areas and good biocompatibility, the mesoporous silica sieve MCM-41 provided a suitable matrix for immobilization of biomolecule. The MCM-41 modified CILE showed significant promotion to the direct electron transfer of Hb, which exhibited a pair of well defined and quasi-reversible peaks for heme Fe(III)/Fe(II) with a formal potential of -0.284 V (vs. Ag/AgCl). Additionally, the Hb immobilized on the MCM-41 modified carbon ionic liquid electrode showed excellent electrocatalytic activity toward H(2)O(2). The electrocatalytic current values were linear with increasing concentration of H(2)O(2) in a wide range of 5-310 microM and the corresponding detection limit was calculated to be 5 x 10(-8)M (S/N=3). The surface coverage of Hb immobilized on the MCM-41 modified carbon ionic liquid electrode was about 2.54 x 10(-9) molcm(-2). The Michaelis-Menten constant K(m)(app) of 214 microM indicated that the Hb immobilized on the modified electrode showed high affinity to H(2)O(2). The proposed electrode had high stability and good reproducibility due to the protection effect of MCM-41 and ionic liquid, and it would have wide potential applications in direct electrochemistry, biosensors and biocatalysis.

  2. Separation of (+)-catechin and quercetin on mesoporous MCM-41 composites: Dynamics of the sorption of flavonoids

    Science.gov (United States)

    Karpov, S. I.; Korabel'nikova, E. O.

    2015-06-01

    An analysis of conditions for chromatographic separation of quercetin and (+)-catechin based on experimental data and using the equations of an asymptotic model of sorption dynamics for substances characterized by convex isotherms of sorption is presented. The effects of the equilibrium (distribution coefficient) and kinetic (diffusion coefficient) factors on the dynamics of the sorption of flavonoids by ordered mesoporous material of the MCM-41 type and its composites with grafted organosilane groups is considered. The effects of kinetic and equilibrium parameters on the broadening of adsorption fronts is demonstrated with allowance for the inner and outer diffusion limitations of the sorption process.

  3. Visible-light photo-Fenton oxidation of phenol with rGO-α-FeOOH supported on Al-doped mesoporous silica (MCM-41) at neutral pH: Performance and optimization of the catalyst.

    Science.gov (United States)

    Wang, Ying; Liang, Mingxing; Fang, Jiasheng; Fu, Jun; Chen, Xiaochun

    2017-09-01

    In this study, α-FeOOH on reduced graphene oxide (rGO-α-FeOOH) supported on an Al-doped MCM-41 catalyst (RFAM) was optimized for the visible-light photo-Fenton oxidation of phenol at neutral pH. The stability of the catalysts, effect of bubbling aeration, and degradation intermediates were investigated. Results indicated that RFAM with a large Brunauer-Emmett-Teller (BET) area and mesoporous structure displayed excellent catalytic activity for the visible-light-driven (VLD) photo-Fenton process. Phenol degradation was well described by a pseudo-first-order reaction kinetics model. Raman analysis demonstrated that an rGO-α-FeOOH (RF) composite is formed during the ferrous-ion-induced self-assembly process. Al-MCM-41 could uniformly disperse RF nanosheets and promote the mobility and diffusion of matter. The activity of the main catalyst α-FeOOH was enhanced after the incorporation of rGO nanosheets. The α-FeOOH crystal in RFAM showed catalytic activity superior to those of Fe3O4 and Fe2O3. The RFAM catalyst, with an optimal GO-Fe(2+)mass ratio of 2.33, exhibited a larger BET area, pore size, and pore volume, and thus exhibited high performance and energy utilization efficiency in the VLD photo-Fenton reaction with remarkable stability. Bubbling N2 inhibited catalytic performance, while bubbling O2 or air only slightly accelerated the phenol degradation. Visible light played an important role in accelerating the formation of reactive oxygen species (·OH) for the highly efficient phenol degradation. Analysis of degradation intermediates indicated a high phenol mineralization level and the formation of low-molecular-weight organic acids. This work would be helpful in providing an insight into a new type of catalyst assembly and a possible route to a promising heterogeneous catalyst applicable in the visible light photo-Fenton process for effective wastewater remediation at neutral pH. Copyright © 2017. Published by Elsevier Ltd.

  4. Characteristics of the mass transfer of phosphatidylcholine during its sorption on mesoporous composites based on MCM-41

    Science.gov (United States)

    Sinyaeva, L. A.; Karpov, S. I.; Belanova, N. A.; Roessner, F.; Selemenev, V. F.

    2015-12-01

    The kinetic parameters of sorption of phosphatidylcholine on mesoporous composites based on MCM-41 are considered. It is noted that the possibility of both the diffusion and adsorption rate limitations of the process should be taken into account in the description of the kinetics of sorption of non-polar fat-soluble physiologically active compounds (PACs) from hexane solutions onto mesoporous materials of MCM- 41 type. The adequacy of using the Boyd diffusion model and the Lagergren, Ho and McKay, and Elovich models to describe the kinetics of sorption of phosphatidylcholine on mesoporous composites based on MCM-41 is shown. The contributions from diffusion limitation (internal and external) and the rate of the chemical step of adsorption to the overall rate of the sorption process are determined. It is found that the sorption of the phospholipid is a mixed diffusion process.

  5. The Mechanism of Pseudomorphic Transformation of Spherical Silica Gel into MCM-41 Studied by PFG NMR Diffusometry

    National Research Council Canada - National Science Library

    Wolf-Dietrich Einicke; Dirk Enke; Muslim Dvoyashkin; Rustem Valiullin; Roger Gläser

    2013-01-01

      The pseudomorphic transformation of spherical silica gel (LiChrospher® Si 60) into MCM-41 was achieved by treatment at 383 K for 24 h with an aqueous solution of cetyltrimethylammonium hydroxide (CTAOH...

  6. Synthesis of multi-wall carbon nanotubes by the pyrolysis of ethanol on Fe/MCM-41 mesoporous molecular sieves

    Science.gov (United States)

    Zhao, Qian; Li, Yanhui; Zhou, Xuping; Jiang, Tingshun; Li, Changsheng; Yin, Hengbo

    2010-03-01

    Ordered hexagonal arrangement MCM-41 mesoporous molecular sieves were synthesized by the traditional hydrothermal method, and Fe-loaded MCM-41 mesoporous molecular sieves (Fe/MCM-41) were prepared by the wet impregnation method. Their mesoporous structures were testified by X-ray diffraction (XRD) and the N 2 physical adsorption technique. Carbon nanotubes (CNTs) were synthesized by the chemical vapor deposition (CVD) method via the pyrolysis of ethanol at atmospheric pressure using Fe/MCM-41 as a catalytic template. The effect of different reaction temperatures ranging from 600 to 800 ∘C on the formation of CNTs was investigated. The resulting carbon materials were characterized by various physicochemical techniques such as transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy. The results show that multi-wall carbon nanotubes (MWCNTs) with an internal diameter of ca. 7.7 nm and an external diameter of ca. 16.9 nm were successfully obtained by the pyrolysis of ethanol at 800 ∘C utilizing Fe/MCM-41 as a catalytic template.

  7. MCM-41 supported 12-tungstophosphoric acid mesoporous materials: Preparation, characterization, and catalytic activities for benzaldehyde oxidation with H2O2

    Science.gov (United States)

    Chen, Ya; Zhang, Xiao-Li; Chen, Xi; Dong, Bei-Bei; Zheng, Xiu-Cheng

    2013-10-01

    Mesoporous molecular sieves MCM-41 and bulk 12-tungstophosphoric acid (HPW) were synthesized and employed to prepare 5-45 wt.% HPW/MCM-41 mesoporous materials. Characterization results suggested the good dispersion of HPW within MCM-41 when the loading of HPW was less than 35 wt.% and HPW/MCM-41 retained the typical mesopore structure of the supports. The results of the catalytic oxidation of benzaldehyde to benzoic acid with 30% H2O2, in the absence of any organic solvent and co-catalysts, indicated that HPW/MCM-41 was an efficient catalyst and 30 wt.% HPW/MCM-41 sample exhibited the highest catalytic activity among these materials.

  8. An Encapsulation of the Rare Earth Complex in Modified Mesoporous Molecular Sieve MCM-41

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The encapsulation of a rare earth (RE) complex Eu(DBM)3phen in modified Si-MCM-41 with 3-aminopropyltriethoxysilane is reported for the first time.The luminescence intensity of the RE complex in the modified Si-MCM-41 is about 9 times as strong as in unmodified Si-MCM-41 and the luminescence of the RE complex in the modified Si-MCM-41 has good color purity.

  9. Mesoporous silicate MCM-41 as a particulate carrier for octyl methoxycinnamate: Sunscreen release and photostability.

    Science.gov (United States)

    Ambrogi, Valeria; Latterini, Loredana; Marmottini, Fabio; Pagano, Cinzia; Ricci, Maurizio

    2013-05-01

    Octyl methoxycinnamate (OMC) is a widely used UV filter characterized by good absorbing properties; however, it shows light susceptibility (photoinstability) and potential skin permeation. This paper describes the application of a new particulate carrier to improve OMC safety and photostability. The UV filter was included into the pores of the mesoporous silicate MCM-41 and then entrapped there by plugging the pore openings. The last step was performed treating the MCM-41 inclusion product with a lipid cosmetic ingredient by the hot-melt method. The loaded samples were characterized by X-ray powder diffraction, Fourier transform infrared spectroscopy, and N2 adsorption isotherms. Photochemical studies demonstrated that the coated samples allow a broader photoprotection range and remarkable improvement of sunscreen photostability. Finally, they were properly formulated in an emulgel, and the sunscreen release was studied in vitro by Franz diffusion cell and compared with those obtained from the same formulation containing the free filter. Sunscreen release from the studied formulations resulted negligible, meaning that the proposed approach represents a valuable strategy for UV filters stabilization toward light and safety improvement. Copyright © 2013 Wiley Periodicals, Inc.

  10. Cu-酞菁配合物在MCM-41中的装载研究%The Study of Encapsulation of Metal-phthalocyanine in Mesoporous Molecular Sieves MCM-41

    Institute of Scientific and Technical Information of China (English)

    崔子祥; 薛永强; 杜锡光; 李萍

    2011-01-01

    The2(3), 9(10), 16(17), 23 (24)-tetra-(N, N-bisethylamineethoxyl) Cu(Ⅱ)-phthalocyanine complexes with flexible peripheral substituents were synthesized and encapsulated in mesoporous molecular sieves MCM-41. The prepared samples were characterized by UV-vis-Nir, FT-IR, XRD, TEM, FESEM and N2 adsorption-desoption isotherms. Results show that the prepared phothalocyanine copper ( Ⅱ ) was encapsulated in mesoporous molecular sieves MCM-41 in the form of monomer and dimer. The phothalocyanine copper ( II ) encapsulated in MCM-41 with high concentration was in favour of preparing mesoporous molecular sieves samples with higher crystallinity and pore channel order.%合成了具有柔性取代基的2(3),9(10),16(17),23(24)-四-(N,N-二-乙胺基乙氧基)Cu-酞菁配合物,并且装载到MCM-41中.利用UV-Vis-Nir,FT-IR,XRD,TEM,FESEM及N2吸附-脱附等温线对制备的样品进行了表征.研究表明:制备的Cu-酞菁配合物能够装载到MCM-41中;较高浓度的Cu-酞菁配合物在MCM-41中的装载,有利于制备结晶度及孔道有序性较高的介孔分子筛样品.

  11. Determination of very low levels of gold and palladium in wastewater and soil samples by atomic absorption after preconcentration on modified MCM-48 and MCM-41 silica.

    Science.gov (United States)

    Ebrahimzadeh, H; Tavassoli, N; Amini, M M; Fazaeli, Y; Abedi, H

    2010-06-15

    A simple and rapid method was applied for extraction, preconcentration and determination of trace amounts of gold and palladium in wastewater by using functionalized mesoporous silica. Extraction was investigated on adsorbents prepared by grafting aminopropyl on the surface of MCM-41 and MCM-48 mesoporous silica. The optimum experimental conditions such as pH, flow rates, type and the smallest amount of eluent for elution of Au and Pd, break through volume and the influence of various cationic interferences on the sorption of gold(III) and palladium(II) were evaluated. The extraction efficiency for gold and palladium were greater than 98% and limit of detection (LOD) was lower than 0.06ng mL(-1) for gold and 0.1ng mL(-1) for palladium on both functionalized MCM-41 and MCM-48 silica. The preconcentration factor was greater than 800 for gold and 400 for palladium and the relative standard deviation (RSD) of the method was recovery to MCM-41 at higher flow rates only under identical conditions. The proposed method was applied for the determination of gold(III) and palladium(II) in some real samples, including wastewater and soil samples.

  12. Simultaneous Removal of Surfactant Template from MCM-41 and Implantation of Transition Metal Complexes into Mesopores with Supercritical Fluid

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The simultaneous removal of up to 92% of the surfactant template and chemical implantation of transition metal complexes into mesopores has been successfully achieved by treating as-synthesized pure siliceous MCM-41 with supercritical CO2 modified with CH2Cl2/MeOH mixture, resulting in the formation of functionalized material with uniform pore structure.

  13. Mo/MCM-41-Type mesoporous materials doubly promoted with Fe and Ni for hydrotreating reactions

    Energy Technology Data Exchange (ETDEWEB)

    Carlos F. Linares; Patricia Amezqueta; Carlos Scott [Universidad de Carabobo, Carabobo (Venezuela). Laboratorio de Catalisis y Metales de Transicion

    2008-09-15

    A Si-MCM-41-type material was synthesized and impregnated with a Mo solution in order to get a 15% MoO{sub 3} by weight. Then, it was doubly promoted with Ni and Fe in different proportions. Information on the structure of the precursors was revealed by XRD, TPR and surface area techniques. XRD results showed that the mesoporous materials were not affected for the successive impregnations carried out; while, their specific surface areas was partially blocked. These solids were tested for vanadyl octaethyl porphyrin hydrodeporphirinization (HDP), and individual and competitive reactions of dibenzothiophene (DBT) hydrodesulfurization (HDS) and 2-methyl naphthalene (2MN) hydrogenation (HYD). The DBT HDS activity was higher than 2MN HYD, and the presence of Fe in the catalysts did not produce a synergetic effect for this reactions. However, HDP activities of doubly promoted catalysts were superior to the monopromoted ones. 28 refs., 8 figs., 5 tabs.

  14. On the preparation and characterisation of MCM-41 supported heterogeneous nickel and molybdenum catalysts

    NARCIS (Netherlands)

    Lensveld, Dennis

    2003-01-01

    MCM-41 is an ordered mesoporous material, displaying a honeycomb-like structure of uniform mesopores (3 nm in diameter) running through a matrix of amorphous silica. Because of the high porosity (pore volume » 1.0 ml g-1) and concomitant large surface area (approximately 1,000 m2 g-1) MCM-41 is in p

  15. Catalytic conversion of palm oil over mesoporous aluminosilicate MCM-41 for the production of liquid hydrocarbon fuels

    Energy Technology Data Exchange (ETDEWEB)

    Twaiq, Farouq A.; Mohamed, Abdul Rahman; Bhatia, Subhash [School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, SPS, Pinang (Malaysia); Zabidi, Noor Asmawati M. [Universiti Teknologi Petronas, Sri Iskandar, 31750 Tronoh, Perak (Malaysia)

    2003-11-15

    The catalytic cracking of palm oil to liquid hydrocarbon fuels was studied in a fixed bed micro-reactor operated at atmospheric pressure, reaction temperature of 723 K and weight hourly space velocity (WHSV) of 2.5 h{sup -1} over the synthesized mesoporous molecular sieve MCM-41 materials. Mesoporous aluminosilicate with Si/Al ratio of 50 was synthesized using the hydrothermal method. Different pore sizes were obtained by changing the type of template and organic directing agent (ODA) used. The synthesized materials were characterized using various analytical methods such as X-ray powder diffraction (XRD), BET surface area, inductive coupled plasma (ICP), MAS NMR, FTIR and temperature-programmed desorption (TPD). The materials exhibit a crystalline structure of MCM-41 mesoporous molecular sieves with surface area varying from 550 to 1200 m{sup 2}/g and an average pore size (APS) ranging from 1.8 to 2.8 nm. The synthesized MCM-41 catalysts show high activity for palm oil cracking. The conversion of palm kernel oil, lower-molecular-weight oil, was higher as compared to higher-molecular-weight, palm olein oil. MCM-41 materials were selective for the formation of linear hydrocarbons, particularly, C{sub 13} when palm kernel oil was used and C{sub 17} when palm olein oil was fed. The yield of liquid product decreased with the increase of surface area of the catalyst. The gasoline selectivity increased whereas diesel selectivity decreased with the conversion of palm oil.

  16. Applications of Ordered Mesoporous Molecular Sieve SBA-15/MCM-41 in Electrochemical Catalysis%有序介孔分子筛SBA-15/MCM-41在电催化方面的应用

    Institute of Scientific and Technical Information of China (English)

    李洋; 邸婧; 郑华均

    2014-01-01

    The classification and development of mesoporous material were introduced in this paper. The applications of mesoporous molecular sieve SBA-15/MCM-41 in electrochemical catalysis were summa-rized in view of the present problems of electricity catalysis.%介绍了有序介孔材料的分类与发展,针对目前电催化领域存在的问题,综述了介孔分子筛SBA-15/MCM-41材料在电催化方面的应用。

  17. EFFECT OF AGING TIME TOWARD CRYSTALLINITY OF PRODUCTS IN SYNTHESIS OF MESOPOROUS SILICATES MCM-41

    Directory of Open Access Journals (Sweden)

    Suyanta Suyanta

    2010-12-01

    Full Text Available Researches about the effects of aging time toward crystallinity of products in the synthesis of mesoporous silicates MCM-41 have been done. MCM-41 was synthesized by hydrothermal treatment to the mixture of sodium silicate, sodium hydroxide, cetyltrimetylammoniumbromide (CTMAB and aquadest in the molar ratio of 8Na2SiO3 : CTMAB : NaOH : 400H2O. Hydrothermal treatment was carried out at 110 °C in a teflon-lined stainless steel autoclave heated in the oven, with variation of aging time, i.e.: 4, 8, 12, 16, 24, 36, 48, and 72 h respectively. The solid phase were filtered, then washed with deionised water, and dried in the oven at 100 °C for 2 h. The surfactant CTMAB was removed by calcinations at 550 °C for 10 h with heating rate 2 °C/min. The as-synthesized and calcined powders were characterized by using FTIR spectroscopy and X-ray diffraction method. The relative crystallinity of products was evaluated based on the intensity of d100 peaks. The best product was characterized by using N2 physisorption method in order to determine the specific surface area, mean pore diameter, lattice parameter, and pore walls thickness. It was concluded that the relative crystallinity of the products was sensitively influenced by the aging time. The highest relative crystallinity was achieved when used 36 h of aging time in hydrothermal treatment. In this optimum condition the product has 946.607 m2g-1 of specific surface area, 3.357 nm of mean pore diameter, 4.533 nm of lattice parameter, and 1.176 nm of pore walls thickness.

  18. Analyzing adsorption characteristics of CO2, N2 and H2O in MCM-41 silica by molecular simulation

    Science.gov (United States)

    Chang, Shing-Cheng; Chien, Shih-Yao; Chen, Chieh-Li; Chen, Cha'o.-Kuang

    2015-03-01

    The adsorption characteristics of carbon dioxide, nitrogen and water molecules in MCM-41 mesoporous molecular sieve have been investigated by the molecular simulation. We evaluate the pressure-adsorption isotherms and adsorption density profiles under variant gas pressure, operating temperature and mesopore radius of MCM-41 by the grand canonical Monte Carlo simulation. According to the calculated adsorption energy distributions, the adsorption mechanisms of gas in MCM-41 are mainly divided into three types, namely "surface adsorption" on the pore wall, "multilayer adsorption" on the adsorbed gas molecules and "molecular self-aggregation" near the pore center. In addition, the adsorption characteristics of water molecules in MCM-41 are found to be quite different from those of carbon dioxide and nitrogen due to the hydrogen bonds effect. The results indicate that the MCM-41 is practicable in engineering application for the capture, storage, and re-use of water molecules, since it is temperature-sensitive and can achieve significant adsorption loadings within a small range of pressure values via the capillary condensation phenomena.

  19. Synthesis and characterization of mesoporous Si-MCM-41 materials and their application as solid acid catalysts in some esterification reactions

    Indian Academy of Sciences (India)

    Tarun F Parangi; Rajesh M Patel; Uma V Chudasama

    2014-05-01

    Mesoporous MCM-41 has been synthesized by sol–gel method at room temperature possessing good thermal stability, high surface area as well as retention of surface area at high temperature. The MCM-41 neutral framework has been modified and put to practical use by incorporating Al3+ in the siliceous MCM-41 framework and supporting 12-TPA (12-tungstophosphoric acid) onto MCM-41 by process of anchoring and calcination to induce Brønsted acidity in MCM-41 to yield Al-MCM-41 and 12TPA-MCM-41, respectively. The synthesized materials have been characterized for elemental analysis by ICP-AES, XRD, SEM, TEM, EDX, FT–IR and TGA. Surface area has been determined by BET method and pore size and pore size distribution determined by BJH method. Surface acidity has been evaluated by NH3-TPD method. The potential use of Al-MCM-41 and 12TPA-MCM-41 as solid acid catalysts has been explored and compared by studying esterification as a model reaction wherein monoesters such as ethyl acetate (EA), propyl acetate (PA), butyl acetate (BA) and benzyl acetate (BzA) have been synthesized, optimizing several parameters such as catalyst amount, reaction time, reaction temperature and mole ratio of reagents.

  20. A New Strategy for the Synthesis of 3-Acyl-coumarin Using Mesoporous Molecular Sieve MCM-41 as a Novel and Efficient Catalyst

    Institute of Scientific and Technical Information of China (English)

    HERAVI,Majid M; POORMOHAMMAD,Nargess; BEHESHTIGA,Yahia Sh; BAGHERNEJAD,Bita; MALAKOOTI,Reihaneh

    2009-01-01

    3-Acyl-coumarins were obtained in high yields from ortho-hydroxybenzaldehydes and ethyl acetoacetate or ethyl benzoylacetate in acetonitrile in the presence of a catalytic amount of mesoporous molecular sieve MCM-41. 3-Acyl-coumarins were obtained in high yields from ortho-hydroxybenzaldehydes and ethyl acetoacetate or ethyl benzoylacetate in acetonitrile in the presence of a catalytic amount of mesoporous molecular sieve MCM-41.

  1. MCM-41介孔分子筛中负载酞菁配合物的研究%Study of Metal-phthalocyanine Encapsulated in Mesoporous Molecular Sieves MCM-41

    Institute of Scientific and Technical Information of China (English)

    崔子祥; 薛永强; 李萍

    2012-01-01

    Zn-phthalocyanine complex(Ⅱ), which periphery has substituents was synthesized, and encapsulated in mesoporous molecular sieves MCM-41. The prepared samples was characterized by FT-1R, UV-vis-Nir, XRD, FESEM, TEM and N2 adsorption-desorption instrument. The research shows that the prepared phthalocyanine copper zinc can be encapsulated in mesoporous molecular sieves MCM-41 in the form of monomer and dipolymer. The prepared phthalocyanine zinc with high concentration encapsulated in MCM-41 is in favour of preparing mesoporous molecular sieves samples with higher crystallinity and pore canal order.%合成了Zn-酞菁化合物,通过水热法将酞菁化合物负载在MCM-41介孔分子筛中.利用FT-IR、UV-vis-Nir、XRD、FESEM、TEM及N2吸附-脱附仪对酞菁负载后的样品进行了表征.研究结果表明:较高浓度Zn-酞菁能够负载到介孔分子筛中,并且随着酞菁配合物浓度的增加,介孔分子筛孔道的有序性及结晶度都提高.

  2. A Cu/Al-MCM-41 mesoporous molecular sieve: application in the abatement of no in exhaust gases

    Directory of Open Access Journals (Sweden)

    M. S. Batista

    2005-09-01

    Full Text Available Propane oxidation and reduction of NO to N2 with propane under oxidative conditions on a Cu-Al-MCM-41 mesoporous molecular sieve and Cu-ZSM-5 zeolites were studied. Both types of catalysts were prepared by ion exchange in aqueous solutions of copper acetate and characterised by X-ray diffraction (XRD, nitrogen sorption measurement, diffuse reflectance ultra-violet spectroscopy (DRS-UV, diffuse reflectance infra-red Fourier transform spectroscopy (DRIFTS of the adsorption of CO on Cu+ and temperature-programmed reduction with hydrogen (H2-TPR. The NO reduction was performed between 200 and 500 ºC using a GHSV = 42,000 h-1. H2-TPR data showed that in the prepared Cu-Al-MCM-41 all the Cu atoms are on the surface of the mesopores as highly dispersed CuO, which results in a decrease in specific surface area and in mesopore volume. H2-TPR together with DRIFTS data provided evidence that in Cu/ZSM-5 catalysts, Cu atoms are found as two different Cu2+ cations: Cualpha2+ and Cubeta2+, which are located on charge compensation sites, and their thermo-redox properties were different from those of Cu atoms in Cu-Al-MCM-41. The specific activity of the Cu2+ exchangeable cations in Cu-ZSM-5, irrespective of their nature, was much greater than that of the Cu2+ in Cu-Al-MCM-41, where they are found as CuO.

  3. Preparation and Properties of Zirconium Hydride on the Surface of MCM-41 Mesoporous Molecular Sieves

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Zirconium monohydride bonded to the framework oxygen of MCM-41 surface was prepared by the reaction of tetraneopentyl zirconium with MCM-41 surface hydroxyl groups, followed by the hydrogenolysis of the resulted product. The surface hydride was characterized by using infrared spectroscopy, solid-state NMR, elemental analysis, gas-phase chromatography and chemical probing reaction. It was shown that this surface species is stable below 150 ℃ and can catalytically crack alkanes into methane and ethane at 100 ℃.

  4. The Mechanism of Pseudomorphic Transformation of Spherical Silica Gel into MCM-41 Studied by PFG NMR Diffusometry

    Directory of Open Access Journals (Sweden)

    Roger Gläser

    2013-08-01

    Full Text Available The pseudomorphic transformation of spherical silica gel (LiChrospher® Si 60 into MCM-41 was achieved by treatment at 383 K for 24 h with an aqueous solution of cetyltrimethylammonium hydroxide (CTAOH instead of hexadecyltrimethylammonium bromide (CTABr and NaOH. The degree of transformation was varied via the ratio of CTAOH solution to initial silica gel rather than synthesis duration. The transformed samples were characterized by N2 sorption at 77 K, mercury intrusion porosimetry, X-ray diffraction (XRD and scanning electron microscopy (SEM. Thus, MCM-41 spheres with diameters of ca. 12 μm, surface areas >1000 m2 g−1, pore volumes >1 cm3 g−1 and a sharp pore width distribution, adjustable between 3.2 and 4.5 nm, were obtained. A thorough pulsed field gradient nuclear magnetic resonance (PFG NMR study shows that the diffusivity of n-heptane confined in the pores of the solids passes through a minimum with progressing transformation. The final product of pseudomorphic transformation to MCM-41 does not exhibit improved transport properties compared to the initial silica gel. Moreover, the PFG NMR results support that the transformation occurs via formation and subsequent growth of domains of <1 μm containing MCM-41 homogeneously distributed over the volume of the silica spheres.

  5. Proline and benzylpenicillin derivatives grafted into mesoporous MCM-41: Novel organic-inorganic hybrid catalysts for direct aldol reaction

    Indian Academy of Sciences (India)

    Dwairath Dhar; Ian Beadham; Srinivasan Chandrasekaran

    2003-10-01

    New organic-inorganic hybrid catalysts were synthesized by covalent grafting of proline and benzylpenicillin derivatives into mesoporous MCM-41. These catalysts were extensively characterized using FT-IR, 13C CP MAS solid state NMR, XRD and TEM techniques. These were used as catalysts for direct, asymmetric aldol reaction between acetone and activated aromatic aldehydes. In the reaction of 4-nitro and 4-fluoro benzaldehyde, the aldol products were obtained in 36% and 59% ee respectively. The catalysts were reusable with neither significant drop in enantioselectivity nor loss of mesostructure. An attempt was made to substantiate the proposed `enamine’ mechanism for direct aldol reaction by trapping the intermediate between proline-MCM-41 and acetone.

  6. Preparation of TiO2/MCM-41 photocatalyst using rice husk ash as silica source

    Science.gov (United States)

    Fatimah, Is; Sopia, Lusi

    2017-03-01

    This work aimed to prepare TiO2/MCM-41 from rice husk ash (RHA) agricultural waste and its application as photocatalyst in dye degradation. The preparation was conducted by two main steps; preparation of MCM-41 and titanium immobilization onto MCM-41. Sol gel method using CTMABr as templating agent was applied in MCM-41 synthesis and as TiO2 precursor, titanium isopropoxide was utilized. The study of physicochemical character change was performed by by X-ray diffraction, IR spectroscopy, BET method and thermogravimetric analysis (TGA). Photocatalytic activity of material was tested in methylene blue photodegradation system. According to the results, it is found that TiO2/MCM-41 has been successfully prepared and shows photocatalytic activity. Kinetic study of the reaction is discussed in this paper.

  7. Effect of reaction parameters on the growth of MWCNTs using mesoporous Sb/MCM-41 by chemical vapour deposition

    Science.gov (United States)

    Atchudan, R.; Pandurangan, A.; Subramanian, K.

    2011-11-01

    Mesoporous Si-MCM-41 molecular sieve was synthesized hydrothermally and different wt.% of Sb (1.0, 2.0, 3.0, 5.0, 10.0, 15.0 and 20.0) was loaded on it by wet impregnation method. The Sb/MCM-41 materials were characterized by various physico-chemical techniques such as XRD, TGA and TEM. The TEM image showed a honeycomb structure of the host material. They were used as catalytic templates for the growth of MWCNTs by CVD method with different temperatures at 700, 800, 900 and 1000 °C using acetylene as a carbon precursor. The reaction temperature was optimized for the better formation of MWCNTs and they were purified and then characterized by XRD, SEM, HR-TEM and Raman spectroscopy techniques. The formation of MWCNTs with diameter in the range of 4-6 nm was observed from HR-TEM. The good thermal stability and high productivity of catalyst observed in this study revealed that the 2 wt.% Sb loaded MCM-41 could be a promising support for the catalytic synthesis of MWCNTs at 800 °C by CVD method.

  8. Chromatographic separation and concentration of quercetin and (+)-catechin using mesoporous composites based on MCM-41

    Science.gov (United States)

    Karpov, S. I.; Belanova, N. A.; Korabel'nikova, E. O.; Nedosekina, I. V.; Roessner, F.; Selemenev, V. F.

    2015-05-01

    Data on chromatographic separation of quercetin and (+)-catechin-flavonoids with similar physicochemical (including sorption) properties—are presented. The highest efficiency of chromatographic process at high sorption capacity of the material with respect to quercetin and slightly lower capacity for (+)-catechin were observed when silylated composites of ordered MCM-41 type materials were used. The application of acetonitrile as a solvent increased the sorption capacity of the material and can be recommended for separation of related polyphenol substances and their determination using ordered MCM-41 modified with trimethylchlorosilane as a stationary phase in a chromatographic column.

  9. Study on the adsorption behaviours of naphthalene on MCM-41 and SBA-15 mesoporous molecular sieves%萘在介孔分子筛MCM-41与SBA-15上的吸附特性研究

    Institute of Scientific and Technical Information of China (English)

    杨权; 刘应书; 李子宜; 杨雄; 王占营; 姜理俊

    2015-01-01

    In this paper, the adsorption behaviours of naphthalene on two popular mesoporous molecular sieves, SBA-15 and MCM-41 were studied. The adsorption isotherms were obtained, and fitted with isotherm models of Langmuir, Freundlich and D-R. The breakthrough curves of naphthalene at different initial concentrations were measured, and well predicted by the constant-pattern wave model. Results show that the Langmuir model can well describe the adsorption isotherms of naphthalene at low concentration with R2 higher than 99%. The adsorption ability of SBA-15 with a microporous structure is stronger than that of MCM-41 which contains only mesoporous structures. The predictions on breakthrough curves by the constant-pattern model exhibited higher correlation coefficient for SBA-15 than for MCM-41. The overall mass transfer coefficient Ka of naphthalene on SBA-15 is higher than that on MCM-41 , indicating that there is a lower mass transfer resistance and the mass transfer equilibrium can be achieved faster over SBA-15 .%对低浓度气相萘在两种常见介孔分子筛MCM-41和SBA-15上的吸附特性进行研究. 得到了萘在两种吸附剂上的吸附等温线和不同初始浓度下的穿透曲线,并分别与吸附等温线模型( Langmuir、Freundlich、D-R)和恒定浓度波动力学模型进行了拟合. 结果表明, Langmuir模型能很好描述低浓度气相萘的吸附等温线( R2均在99%以上);具有微孔结构的SBA-15对萘的吸附能力要优于仅具备介孔结构的MCM-41. 动力学模型在初始浓度较低时能较好地预测萘在吸附剂上的穿透曲线,且在SBA-15上的相关系数高于MCM-41;萘在2. 76 mol/L时具有较大介孔的SBA-15的总传质系数Ka 更高,表明萘在SBA-15上的总传质阻力更低,更能较快达到传质平衡.

  10. Mesoporous silica nanoparticles inhibit cellular respiration.

    Science.gov (United States)

    Tao, Zhimin; Morrow, Matthew P; Asefa, Tewodros; Sharma, Krishna K; Duncan, Cole; Anan, Abhishek; Penefsky, Harvey S; Goodisman, Jerry; Souid, Abdul-Kader

    2008-05-01

    We studied the effect of two types of mesoporous silica nanoparticles, MCM-41 and SBA-15, on mitochondrial O 2 consumption (respiration) in HL-60 (myeloid) cells, Jurkat (lymphoid) cells, and isolated mitochondria. SBA-15 inhibited cellular respiration at 25-500 microg/mL; the inhibition was concentration-dependent and time-dependent. The cellular ATP profile paralleled that of respiration. MCM-41 had no noticeable effect on respiration rate. In cells depleted of metabolic fuels, 50 microg/mL SBA-15 delayed the onset of glucose-supported respiration by 12 min and 200 microg/mL SBA-15 by 34 min; MCM-41 also delayed the onset of glucose-supported respiration. Neither SBA-15 nor MCM-41 affected cellular glutathione. Both nanoparticles inhibited respiration of isolated mitochondria and submitochondrial particles.

  11. Catalytic degradation of methyl orange using Fenton-like mesoporous Fe-MCM-41%类Fenton试剂MCM-41负载Fe催化降解甲基橙的研究

    Institute of Scientific and Technical Information of China (English)

    田志茗; 袁昊; 杜玺

    2015-01-01

    通过浸渍法制备了MCM-41负载铁催化剂Fe-MCM-41,采用XRD、UV-vis光谱、N2吸附-脱附分析和SEM等对Fe-MCM-41进行表征,结果表明,Fe-MCM-41具有载体MCM-41的介孔结构,孔道分布均匀,平均孔径1.88 nm.研究了以Fe-MCM-41为催化剂的类Fenton体系对甲基橙染料快速降解的方法,考察了分子筛中Fe含量、H2O2及甲基橙初始浓度、溶液pH和催化剂用量等条件对染料降解率的影响.当pH=3、H2O2及甲基橙初始浓度分别为30 mmol/L和20 mmol/L、催化剂用量为2 g/L、反应60 min时,甲基橙的降解率可达96.82%.动力学研究表明,采用Fe-MCM-41催化降解甲基橙遵循一级反应动力学模型(R=0.992),对应的速率常数为8.51×10-2 min-1.%Loaded catalyst of Fe- MCM- 41 was prepared by impregnation method and characterized by means of XRD, UV- vis, N2 adsorption- desorption and SEM. The results indicated that Fe- MCM- 41 had typi⁃cal mesoporous structure features with uniform pore size distribution. The average pore diameter was 1.88 nm. Rapid decolorization of methyl orange by Fenton- like mesoporous Fe- MCM- 41 as catalyst was investi⁃gated. The effects of various parameters such as initial pH, initial H2O2 concentration, dosage of catalyst and initial dye concentration on decolorization rate were studied. The optimum reaction conditions were initial pH=3, the initial concentration of H2O2 30 mmol/L, the initial concentration of methylene blue 20 mmol/L, the dos⁃age of catalyst 2 g/L. The removal rate of methyl orange was 96.82% under the optimum conditions after 60 min of degradation time. The kinetic models indicated that the first order kinetics fit wel with the data (R=0.992) and the corresponding rate constant was 8.51×10- 2 min- 1.

  12. Highly efficient "tight fit" immobilization of alpha-chymotrypsin in mesoporous MCM-41: a novel approach using precursor immobilization and activation.

    Science.gov (United States)

    Fadnavis, Nitin W; Bhaskar, Veldurthy; Kantam, Mannepalli Lakshmi; Choudary, Boyapati Manoranjan

    2003-01-01

    The zymogen alpha-chymotrypsinogen A is bound to mesoporous silica MCM-41 with a protein loading of 170 mg/g solid (MCM-Z) by a simple stirring in aqueous tris-HCl buffer (pH 7.2). The bound zymogen is then activated with trypsin to obtain alpha-chymotrypsin immobilized on MCM-41 (MCM-E.I) that displays an effective enzyme activity corresponding to 65 mg protein/g of solid support (3250 BTEE units/g). A direct immobilization of commercially available alpha-chymotrypsin (MCM-E.II) gives lower loading (1250 BTEE units/g). Protein content of the solid support after immobilization is confirmed by thermogravimetric analysis (TGA). The enzyme is tightly bound to the support and can be used over 100 recycles over 1 week in aqueous as well as reverse micellar media. The immobilized enzyme (MCM-E.I) has been used for resolution of N-acetyl-dl-amino acid esters and racemic trans-4-methoxy-3-phenylglycidic acid (PGA) methyl ester.

  13. Dynamic behaviour of tantalum hydride supported on silica or MCM-41 in the metathesis of alkanes

    KAUST Repository

    Soignier, Sophie

    2014-01-01

    The metathesis of ethane and propane catalysed by tantalum hydride supported on silica or MCM-41 was studied under static and dynamic conditions. During the reaction, the rate decreased over time, indicating deactivation of the catalyst. The evolution of the catalytic system and surface species over time was monitored by various physico-chemical methods: FTIR, 13C NMR spectroscopy, elemental analysis and chemical reactivity. A carbonaceous deposit composed of unsaturated hydrocarbyl species was observed by 13C NMR. This deposit was responsible for poisoning of the catalyst. The deactivation of the catalyst proved more severe at higher temperatures and under static rather than dynamic conditions. A partial regeneration of the catalyst could be achieved during a series of repeated runs. Mechanistically, the deconvolution of the products\\' distribution over time indicated the occurrence of hydrogenolysis in the early stages of the reaction, while pure metathesis dominated later on. The hydrogen was supplied by the dehydrogenation of hydrocarbyl surface species involved in the deactivation process. © 2014 The Royal Society of Chemistry.

  14. Formation at low surfactant concentrations and characterization of mesoporous MCM-41

    Institute of Scientific and Technical Information of China (English)

    陈晓银; 丁国忠; 陈海鹰; 李全芝

    1997-01-01

    At low concentrations of cetyltrimethylammonium bromide,all silica-based mesoporous materials with hexagonal phase have been synthesized via interactions between self-assembled surfactant molecule aggregates and aniomc silicate polymers.The resulting materials are characterized by XRD,FT-IR,solid state 29Si MAS NMR,thermal analysis and N2 adsorption-desorption measurements.After soluble ions are removed,the interactors between surfactant micelles and silicate polymers are reorganized and then form mesostructures 1 he hexagonal framework is sonsistent with amorphous silica gel.The structures of materials depend on the synthesis conditions Hydrothermal process improves the interactions between molecules and increases the degree of framework silicon atom polymerization The.surface area and the mesopore volume of the material prepared at 100℃ increase by 87% and 71 %,respectively,compared with those obtained at room temperature.

  15. Synthesis and Characterization of Bimodal Mesoporous Silica

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiaofang; GUO Cuili; WANG Xiaoli; WU Yuanyuan

    2012-01-01

    Mesoporous silica with controllable bimodal pore size distribution was synthesized with cetyltrimethylammonium bromide (CTAB) as chemical template for small mesopores and silica gel as physical template for large mesopores.The structure of synthesized samples were characterized by Fourier transform infrared (FT-IR) spectroscopy,X-ray diffraction (XRD),scanning electron microscopy (SEM),transmission electron microscopy (TEM) and N2 adsorption-desorption measurements.The experimental results show that bimodal mesoporous silica consists of small mesopores of about 3 nm and large mesopores of about 45 nm.The small mesopores which were formed on the external surface and pore walls of the silica gel had similar characters with those of MCM-41,while large mesopores were inherited from parent silica gel material.The pore size distribution of the synthesized silica can be adjusted by changing the relative content of TEOS and silica gel or the feeding sequence of silica gel and NH4OH.

  16. Characterization and catalysis performance of mesoporous molecular sieve Al- MCM- 41 with different Si/Al ratio%不同硅铝比Al-MCM-41介孔分子筛的表征及催化合成氯乙酸正辛酯

    Institute of Scientific and Technical Information of China (English)

    宋伟明; 董晓娟; 邓启刚; 赵云鹏

    2011-01-01

    以十六烷基三甲基溴化铵( CTAB)为模板剂,正硅酸乙酯(TEOS)为硅源,乙二胺为碱性介质,当n(TEOS)∶n( NaAl02)∶n(CTAB)∶n(H2NCH2CH2NH2)∶n(H2O)=1∶x∶0.12∶ 3.5∶130,其中x=0.1,0.033,0.02,0.01,0.006 7时,水热法合成了Al - MCM - 41介孔分子筛.通过XRD,N2吸附-脱附,NH3 - TPD和TEM等手段对不同硅铝比(n(Si)/n(Al))的Al - MCM -41介孔分子筛进行了表征.结果表明,当n(Si)/n( Al)由150减小至30时,Al - MCM -41介孔分子筛仍具有典型的六方介孔结构特征,但当n( Si)/n(Al)=10时,样品结构有序性下降.Al - MCM - 41介孔分子筛酸量随着n( Si)/n( Al)减小而增大.将Al - MCM - 41介孔分子筛用于催化合成氯乙酸正辛酯,相同反应条件下,n( Si) /n( Al) =30的Al - MCM - 41介孔分子筛为催化剂时酯化率最高,由此表明,Al - MCM - 41介孔分子筛作为催化剂,反应酯化率不仅取决于样品酸量,也与其晶体结构相关.当Al - MCM - 41介孔分子筛用量为氯乙酸质量的3%,反应温度为120~140℃,n(氯乙酸)∶n(正辛醇)=1∶1.2时,酯化率可达94.34%.%Mesoporous molecular sieve MCM -41 containing Si and Al with Si/Al molar ratio equal to 10,30, 50,100 and 150 were synthesized under hydrothermal conditions using cetyltrimethylammonium bromide (CTAB) as template and tetraethylorthosilicate (TEOS) as silica source and ethylenediamine as alkaline medium. The optimum molar ratio was n(TEOS): n{ NaA102) : n( CTAB) : n( H2NCH2CH2NH2): n( H20) = 1: x: 0. 12: 3. 5: 130, where x = 0. 1,0. 033 ,0. 02,0. 01 and 0. 006 7 respectively. The structure and physical and chemical surface properties of the samples were characterized by XRD, N2 adsorption - desorption, NH3 -TPD,TEM,et al. The results indicated that when Si/Al molar ratio of the samples drops from 150 to 30,the mesoporous molecular sieve MCM - 41 keeps its characteristics of typical hexagonal mesoporous structure. However,as the Si/Al molar ratio declines further to 10, the ordered

  17. [Electron spectra of chemical assembly mesoporous MCM-41 with transition metal complexes].

    Science.gov (United States)

    Huo, Yong-qian; Li, Jun; Wang, Wei; Gong, Ya-qiong; Zhang, Feng-xing

    2004-03-01

    In the paper the complexes of metal cobalt(III), manganese(III), iron(III) and copper(II) with Schiff-base N,N-ethylenebis(salicylideneaminnato) have been synthesized and characterized. The nanosized porous material MCM-41 has been functionalized by the modification of the internal pore surface with gamma-aminopropyl and was assembled by the modification groups with metal complex of Schiff-base. These metal complexes and functionalized nanosized porous materials were charcterized by XRD, IR and UV-Vis. It is indicated by spectral analysis that the synthesized nanosized porous materials have been confirmed to be MCM-41 with hexagon bores, and the gamma-aminopropyls have been bonded on their internal pore surface. And the complexes of metal cobalt(III), manganese(III), iron(III) and copper(II) with Schiff-base N,N-ethylenebis(salicylideneaminnato) were assembled into MCM-41. The IR spectra of these samples show that there were characteristic absorptions of the amino and the Schiff base groups, and the absorption of amino shifted to longer wavelength.

  18. Activity of B(OEt)3-MCM-41 catalyst in the MPV reduction of crotonaldehyde

    Indian Academy of Sciences (India)

    Burcu Uysal

    2013-11-01

    Mesoporous silica materialMCM-41 was functionalized with boron tri-ethoxide (B(OEt)3) groups by the grafting method and denoted as `B(OEt)3-MCM-41’. With the use of TEM, X-ray diffraction, highresolution thermogravimetry (TGA) and N2 adsorption-desorption isotherms, it was shown that the initial hexagonal structure, the high specific surface area, and porosity are retained in the functionalized material. 29Si NMR- and 11B NMR- spectroscopies revealed that the surface of MCM-41 consists of boron alkoxide species. The Meerwein-Ponndorf-Verley (MPV) reduction of crotonaldehyde to but-2-en-1-ol was conducted in the presence of B(OEt)3-MCM-41 catalyst. MPV reduction of crotonaldehyde also showed that functionalization leads to the creation of Lewis acidic sites. A combination of mesoporous structure with Lewis acidic properties makes the MCM-41 functionalized with boron tri-ethoxide groups, useful as solid Lewis acid catalysts.

  19. Vanadium-substituted heteropolyacids immobilized on amine- functionalized mesoporous MCM-41: A recyclable catalyst for selective oxidation of alcohols with H{sub 2}O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Xinbo [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China); Wang, Danjun [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China); College of Chemistry Chemical Engineering, Yanan University, Shaanxi Key Laboratory of Chemical Reaction Engineering, Yan' an 716000 (China); Li, Kebin [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China); Zhen, Yanzhong [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China); College of Chemistry Chemical Engineering, Yanan University, Shaanxi Key Laboratory of Chemical Reaction Engineering, Yan' an 716000 (China); Hu, Huaiming [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China); Xue, Ganglin, E-mail: xglin707@163.com [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China)

    2014-09-15

    Graphical abstract: Vanadium-substituted phosphotungstic acids are immobilized on amine- functionalized mesoporous MCM-41 and the hybrid catalyst is proved to be a highly efficient solid catalyst for the oxidation of aromatic alcohols to the corresponding carbonyl compounds with H{sub 2}O{sub 2}, featured by the high conversion and selectivity, easy recovery, and quite steady reuse. - Highlights: • Vanadium-substituted phosphotungstic acid immobilized on amine-functionalized mesoporous MCM-41 are prepared. • HPAs were fixed on the inner surface of mesoporous MCM-41 by chemical bonding to aminosilane groups. • The hybrid catalyst showed much higher catalytic activity than the pure HPAs. • The hybrid catalyst is a highly efficient recyclable solid catalyst for the selective oxidation of aromatic alcohols. - Abstract: New hybrid materials of vanadium-substituted phosphotungstic acids (VHPW) immobilized on amine-functionalized mesoporous MCM-41 (VHPW/MCM-41/NH{sub 2}) are prepared and characterized by FT-IR, XRD, N{sub 2} adsorption, elemental analysis, SEM and TEM for their structural integrity and physicochemical properties. It is found that the structure of the heteropolyacids is retained upon immobilization over mesoporous materials. The catalytic activities of these hybrid materials are tested in the selective oxidation of alcohols to the carbonyl products with 30% aqueous H{sub 2}O{sub 2} as oxidant in toluene. The catalytic activities of different number of vanadium-substituted phosphotungstic acid are investigated, and among the catalysts, H{sub 5}[PV{sub 2}W{sub 10}O{sub 40}] immobilized on amine-functionalized MCM-41 exhibits the highest activity with 97% conversion and 99% selectivity in the oxidation of benzyl alcohol to benzaldehyde. The hybrid catalyst is proved to be a highly efficient recyclable solid catalyst for the selective oxidation of aromatic alcohols to the corresponding aldehydes with H{sub 2}O{sub 2}.

  20. Properties of the silica layer during the formation of MCM-41 studied by EPR of a silica-bound spin probe.

    Science.gov (United States)

    Baute, Debbie; Frydman, Veronica; Zimmermann, Herbert; Kababya, Shifi; Goldfarb, Daniella

    2005-04-28

    The properties of the silica layer during the formation of the mesoporous material MCM-41 were investigated by electron paramagnetic resonance (EPR) experiments carried out on a specifically designed, organo(trialkoxy)silane spin probe, SL1SiEt. Minute amounts of the spin probe were co-condensed with the silica source, tetraethyl orthosilicate (TEOS), in the synthesis of MCM-41 with cetyltrimethylammonium bromide (CTAB) under basic conditions. The mobility and location of the spin probe were followed in the CTAB micellar solution before the reaction, in the reaction mixture and in the final ordered material. It was found that the EPR spectra of hydrolyzed SL1SiEt throughout the room temperature part of the reaction are characteristic of a fast tumbling species, indicating that the silica is highly fluid prior to drying. After filtering, a slow motion type spectrum was observed, showing that the spin-label experiences considerable motional hindrance. The liquidlike behavior could be restored upon stirring the material in water. When the reaction is performed with a hydrothermal stage, the spectrum of SL1SiEt in the final product is the same as that of the room temperature synthesized material, but the addition of water did not restore the high mobility, due to a higher degree of silica cross-linking. The location of SL1SiEt throughout the formation process was obtained from electron spin-echo envelope modulation (ESEEM) measurements on MCM-41 prepared with CTAB deuterated either at the N-methyl or the alpha position and in a reaction carried out in D2O. Comparing the deuterium modulation depth, k(2H), induced by CTAB-alpha-d2, CTAB-d9, or D2O in CTAB micellar solutions of a number of reference spin probes with those of SL1SiEt revealed that the hydrolyzed SL1SiEt is located near the polar heads of the surfactant in the absence of base and TEOS. This supports the postulation of charge matching at the interface as a driving force for the formation of the mesostructure

  1. Effect of surface acidity and pore size of Al-substituted plugs-containing SBA-15 and MCM-41 silicas on the polymerization of THF

    Institute of Scientific and Technical Information of China (English)

    Zhi Qi Jia; Ming Zhao; Chun Guang Gao; Yong Xiang Zhao

    2011-01-01

    We reported here the simultaneous influence of surface acidity and pore size of Al-substituted hexagonal mesoporous silicas (Aldoped plugs-containing SBA-15 and Al-doped MCM-41) on polymerization of THF.These materials were directly synthesized by introduced aluminum isopropoxide into reaction mixture including surfactant and siliceous precursor.Al-doped plugs-containing SBA-15 (denotes as PAS) samples not only possess typical two-step desorption isotherms,which implied PAS materials generated plugs in their mesochannel,but also exhibit larger pore size and thicker wall than that of Al-doped MCM-41 (denotes as ACM),which implied PAS would have a great advantage on catalytic reaction involving large molecular (e.g.polymer of TI-IF) in industrial point'of view.To investigate catalytic activity of PAS and ACM with moderate acidic sites the polymerization of THF in the presence of acetic anhydride was carded out.The results showed PAS exhibiting good performance on polymerization of THF.Such result could be related to the large pore size and moderate acidic sites.

  2. Influence of functional silanes on hydrophobicity of MCM-41 synthesized from rice husk

    Directory of Open Access Journals (Sweden)

    S. Chiarakorn et al

    2007-01-01

    Full Text Available Mesoporous molecular sieve MCM-41 was synthesized from rice husk and rice husk ash, called RH-MCM-41 and RHA-MCM-41. The sol–gel mixtures were prepared with molar composition of 1.0 SiO2: 1.1 NaOH: 0.13 CTAB: 0.12 H2O. After calcination, the polarity of MCM-41 still remained on its surface due to the existence of some silanol groups. In this study, both RH-MCM-41 and RHA-MCM-41 were silylated with two different functional silanes trimethylchlorosilane (TMCS and phenyldimethylchlorosilane (PDMS in order to reduce the surface polarity. The efficiency of silylation was determined based on the amount of moisture adsorbed using thermogravimetric analysis (TGA. The structure of silylating agents and silica templates were found to be important parameters affecting the hydrophobic property of the MCM-41 surface. The post-grafting silylation with aliphatic silane can decrease the surface polarity better than that with aromatic silane, probably due to less sterric hindrance effect. Thus, the surface hydrophobicity of MCM-41 can be improved by the silylation of small molecular silane on RH-MCM-41.

  3. Uranium adsorption studies on aminopropyl modified mesoporous sorbent (NH 2-MCM-41) using statistical design method

    Science.gov (United States)

    Sert, Şenol; Eral, Meral

    2010-11-01

    MCM-41 has been synthesized and modified in order to graft amine groups on its surface. The modified NH 2-MCM-41 adsorbent was characterized by using XRD, SEM, surface area and porosity analyzer, and FT-IR. This characterized adsorbent was investigated for uranium adsorption using the batch method. The central composite design (CCD) combined with the response surface methodology (RSM) was selected to determine the effects of parameters and their interactions for the removal of UO22+ ions. The optimum values of the parameters determined were 4.2 for the initial pH, 60 °C for the temperature, 90 mg L -1 for the initial concentration and 173 min for the shaking time using the response surface methodology. Δ H° and Δ S° were calculated from the slope and the intercept of plots of ln K d versus 1/ T. The isotherm models, Langmuir, Freundlich, Dubinin-Radushkevich (D-R) have been studied to explain the adsorption characteristics.

  4. Vapour phase alkylation of ethylbenzene with -butyl alcohol over mesoporous Al-MCM-41 molecular sieves

    Indian Academy of Sciences (India)

    V Umamaheswari; M Palanichamy; Banumathi Arabindoo; V Murugesan

    2002-06-01

    The alkylation of ethylbenzene with -butyl alcohol was studied over Al-MCM-41 (Si/Al = 50 and 90) and Al, Mg-MCM-41 (Si/(Al + Mg) =50) in the vapour phase from 200 to 400°C. The products were --butylethylbenzene (--BEB), --butylvinylbenzene (--BVB) and --butylethylbenzene ( --BEB). Ethylbenzene conversion decreased with increase in temperature and increase in the ethylbenzene content of the feed. The reaction between the freely diffusing ethylbenzene in the channel and the -butyl cations remaining as charge compensating ions yielded --BEB. --BVB, an unexpected product in this investigation, was produced by dehydrogenation of --BEB over alumina particles present in the channels of the molecular sieves. Adsorption of ethylbenzene on Brønsted acid sites and its subsequent reaction with very closely adsorbed -butyl cations proved to be necessary to obtain --BEB. Though --BEB was obtained, the corresponding --butylvinylbenzene was not observed in this study. Study of time durations indicated rapid and slow catalyst deactivation at lower and higher streams respectively.

  5. Synthesis of an Ionic Liquid and Its Application as Template for the Preparation of Mesoporous Material MCM-41: A Comprehensive Experiment for Undergraduate Students

    Science.gov (United States)

    Hu, Jun; Yin, Jinxiang; Lin, Tianshu; Li, Guangtao

    2012-01-01

    A new solvent-free microwave experiment to synthesize the ionic liquid 1-hexadecyl-3-methylimidazolium bromide (HDMIm-Br) in high yield is presented. The structure is confirmed by IR and [superscript 1]H NMR spectra. HDMIm-Br is then used to prepare an organic-inorganic mesoporous material MCM-41. The microscopic arrangements of mesoporous…

  6. Controlled drug release on amine functionalized spherical MCM-41

    Science.gov (United States)

    Szegedi, Agnes; Popova, Margarita; Goshev, Ivan; Klébert, Szilvia; Mihály, Judit

    2012-10-01

    MCM-41 silica with spherical morphology and small particle sizes (100 nm) was synthesized and modified by post-synthesis method with different amounts of 3-aminopropyltriethoxysilane (APTES). A comparative study of the adsorption and release of a model drug, ibuprofen, was carried out. The modified and drug loaded mesoporous materials were characterized by XRD, TEM, N2 physisorption, elemental analysis, thermal analysis and FT-IR spectroscopy. A new method was developed for the quantitative determination of amino groups in surface modified mesoporous materials by the ninhydrin reaction. Good correlation was found between the amino content of the MCM-41 materials determined by the ninhydrin method and their ibuprofen adsorption capacity. Amino modification resulted in high degree of ibuprofen loading and slow release rate in comparison to the parent non-modified MCM-41.

  7. Composite hydrogel based on surface modified mesoporous silica and poly[(2-acryloyloxy)ethyl trimethylammonium chloride

    Energy Technology Data Exchange (ETDEWEB)

    Torres, Cecilia C. [Department of Organic Chemistry, Faculty of Chemical Science, University of Concepción (Chile); Urbano, Bruno F., E-mail: burbano@udec.cl [Department of Polymer Chemistry, Faculty of Chemical Science, University of Concepción (Chile); Campos, Cristian H. [Department of Organic Chemistry, Faculty of Chemical Science, University of Concepción (Chile); Rivas, Bernabé L. [Department of Polymer Chemistry, Faculty of Chemical Science, University of Concepción (Chile); Reyes, Patricio [Department of Physical Chemistry, Faculty of Chemical Science, University of Concepción (Chile)

    2015-02-15

    This work focused on the synthesis, characterization and water absorbency of a composite hydrogel based on poly[(2-acryloyloxy)ethyl trimethylammonium chloride] and mesoporous silica, MCM-41. The MCM-41 was synthesized and later surface functionalized with triethoxyvinylsilane (VTES) and 3-trimethoxysilylpropylmethacrylate (TMSPM) by a post-grafting procedure. The composite hydrogels were obtained by in-situ polymerization using a mixture of monomer, crosslinker and initiator in the presence of functionalized MCM-41. Diverse characterization techniques were used at the different stages of synthesis, namely, FT-IR, TEM, SEM, DRX, {sup 29}Si and {sup 13}C solid state NMR, and N{sub 2} adsorption isotherms at 77 K. Finally, the water uptake performance of the composites was tested as a function of time, mesoporous silica loading and coupling agent used at the functionalization. The composites using non-functionalized MCM-41 reached the highest water uptake, whereas those composite with MCM-41 TMSPM exhibited the lowest sorption. - Highlights: • Hydrophilic crosslinked polymer-mesoporous silica was obtained. • Mesoporous silica MCM-41 was synthesized and functionalized with organosilane. • Functionalization of MCM-41 affects the water uptake of composite. • Mesoporous silica is covalently bound to the polymer acting as crosslinked point.

  8. 中孔分子筛Al/SO24-/Al-MCM-41的合成、表征及催化性能%Synthesis, Characterization and Catalytic Performance of Mesoporous Molucular Sieves Al/SO24-/Al-MCM-41

    Institute of Scientific and Technical Information of China (English)

    唐晓红

    2013-01-01

    分别用H2SO4和Al2(SO4)3对中孔分子筛Al-MCM-41进行改性,得到了中孔分子筛SO24-/Al-MCM-41和Al/SO2-/Al-MCM-41.采用X射线多晶衍射(XRD)、红外光谱(FT-IR)、N2吸附-脱附和NH3程序升温脱附(NH3-TPD)等测试技术对样品的结构和表面酸性进行了表征.分别用Al-MCM-41、SO24-/Al-MCM-41和Al/SO24-/Al-MCM-41催化合成丙酸香叶酯,比较了三者的催化性能.结果表明,用Al2(SO4)3改性中孔分子筛Al-MCM-41,能得到仍保持着六方介孔结构的中孔分子筛Al/SO24-/Al-MCM-41,其酸性和催化性能比用H2SO4改性得到的SO24-/Al-MCM-41更强;用Al2(SO4)3改性不仅SO24-附着在了分子筛骨架上,而且Al也接枝在了分子筛骨架上.%SO24-/Al-MCM-41 and Al/SO24-/Al-MCM-41 were prepared by modifying Al-MCM-41 with H2SO4 and Al2 (SO4)3,respectively.Their structures and surface acidity were characterized by X-ray diffraction (XRD),Fourier transform infrared spectroscopy (FT-IR),N2adsorption-desorption and NH3temperature programmed desorption (NH3-TPD).Al-MCM-41,SO24-/Al-MCM-41 and Al/SO24-/Al-MCM-41 were used respectively as catalyst for the synthesis of geranyl propionate (GP),and their catalytic properties were compared.The results showed that the mesoporous molecular sieves Al/SO24-/Al-MCM-41 which still keep hexagonal mesoporous structure can be obtained by modifying Al-MCM-41 with Al2 (SO4)3.The acidity and catalytic performance of Al/SO24-/Al-MCM-41 is stronger than that of SO24-/Al-MCM-41 by modifying Al-MCM-41 with H2SO4.While Al2 (SO4)3 modifying Al-MCM-41,not only SO42-adheres to the framework of molecular sieve,and Al is also grafted to the framework.

  9. Improving structural stability of water-dispersed MCM-41 silica nanoparticles through post-synthesis pH aging process

    Energy Technology Data Exchange (ETDEWEB)

    Varache, Mathieu; Bezverkhyy, Igor [UMR 6303 CNRS-Université Bourgogne Franche-Comté, Laboratoire Interdisciplinaire Carnot de Bourgogne (France); Bouyer, Florence [Inserm U866, Equipe Chimiothérapie, métabolisme des lipides et réponse immunitaire anti-tumorale (France); Chassagnon, Rémi; Baras, Florence; Bouyer, Frédéric, E-mail: frederic.bouyer@u-bourgogne.fr [UMR 6303 CNRS-Université Bourgogne Franche-Comté, Laboratoire Interdisciplinaire Carnot de Bourgogne (France)

    2015-09-15

    The colloidal and structural stabilities of MCM-41 mesoporous silica nanoparticles (MSNs) are of great importance in order to prepare optimal nanovectors. In this paper, MSNs (approximatively 160 nm in diameter) were synthesized using n-cetyltrimethylammonium bromide as a template and tetraethyl orthosilicate as a silica source under high N{sub 2} flow (MSN/N{sub 2}) to obtain stable dispersions in water. The degradation of the porous nanoparticles was investigated by immersion in water. The morphology and the porous structure were studied by TEM, XRD, N{sub 2} sorption, and {sup 29}Si MAS NMR and were compared to that of MSNs prepared in ambient air (MSN/air). The volumetric properties of the MSN/N{sub 2} after 1 day in water were drastically more decreased than MSN/air (a pore volume decrease of 85 % for MSN/N{sub 2} and 59 % for MSN/air) and the 2D-hexagonal porous structure was totally lost. Furthermore, synthesizing MSNs under a high N{sub 2} flow leads to a decrease in the synthesis yield (45 % MSN/N{sub 2} and 75 % for MSN/air). The lower structural stability of the MSN/N{sub 2} is explained by the lower polycondensation degree of the MSN/N{sub 2} observed by {sup 29}Si MAS NMR (Q{sup 4}/Q{sup 3} = 0.86 for MSN/N{sub 2} and 1.61 for MSN/air) and the lower silica molar ratio in the nanomaterials (SiO{sub 2}/CTA = 3.9 for MSN/N{sub 2} 7.1 for MSN/air). This allows for enhanced solubilization of silica in water. Four strategies were hence evaluated in order to reinforce the porous structure of the MSNs. Among them, the most efficient route was based on a pH adjustment of the colloidal suspension (pH 7.5) after 2 h of synthesis without any purification and while keeping a N{sub 2} static atmosphere (called MSN/N{sub 2}/7.5). After 1 day in water, the volumetric and structural properties of MSN/N{sub 2}/7.5 were similar to that obtained for MSN/air. The improvement of the stability arose as a result of the increase in the silica condensation (Q{sup 4

  10. Ultrasonic-assisted synthesis and magnetic studies of iron oxide/MCM-41 nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Ursachi, Irina [Department of Physics ' Alexandru Ioan Cuza' University of Iasi, 11 Carol I Boulevard, 700506 Iasi (Romania); Vasile, Aurelia [Department of Chemistry, ' Alexandru Ioan Cuza' University of Iasi, 11 Carol I Boulevard, 700506 Iasi (Romania); Ianculescu, Adelina [Department of Oxide Materials and Engineering, Polytechnics University of Bucharest, 1-7 Gh. Polizu, 011061 Bucharest (Romania); Vasile, Eugeniu [METAV S.A., Research and Development, 31 C.A. Rosetti, 020011, Bucharest (Romania); Stancu, Alexandru, E-mail: alstancu@uaic.ro [Department of Physics ' Alexandru Ioan Cuza' University of Iasi, 11 Carol I Boulevard, 700506 Iasi (Romania)

    2011-11-01

    Highlights: {yields} A quick and facile route for the synthesis of iron oxide/MCM-41 nanocomposite. {yields} Magnetic nanoparticles were stabilized inside the pores of mesoporous silica MCM-41. {yields} The pore size of MCM-41 dictates the properties of iron oxide nanoparticles. {yields} The procedure provides a narrow size distribution of magnetic nanoparticles. - Abstract: Iron oxide nanoparticles were stabilized within the pores of mesoporous silica MCM-41 amino-functionalized by a sonochemical method. Formation of iron oxide nanoparticles inside the mesoporous channels of amino-functionalized MCM-41 was realized by wet impregnation using iron nitrate, followed by calcinations at 550 deg. C in air. The effect of functionalization level on structural and magnetic properties of obtained nanocomposites was studied. The resulting materials were characterized by powder X-ray diffraction (XRD), high-resolution transmission electron microscopy and selected area electron diffraction (HRTEM and SAED), vibrating sample and superconducting quantum interface magnetometers (VSM and SQUID) and nitrogen adsorption-desorption isotherms measurements. The HRTEM images reveal that the most of the iron oxide nanoparticles were dispersed inside the mesopores of silica matrix and the pore diameter of the amino-functionalized MCM-41 matrix dictates the particle size of iron oxide nanoparticles. The obtained material possesses mesoporous structure and interesting magnetic properties. Saturation magnetization value of magnetic iron oxide nanopatricles stabilized in MCM-41 amino-functionalized by in situ sonochemical synthesis was 1.84 emu g{sup -1}. An important finding is that obtained magnetic nanocomposite materials exhibit enhanced magnetic properties than those of iron oxide/MCM-41 nanocomposite obtained by conventional method. The described method is providing a rather short preparation time and a narrow size distribution of iron oxide nanoparticles.

  11. Paraquat adsorption on NaX and Al-MCM-41.

    Science.gov (United States)

    Rongchapo, Wina; Deekamwong, Krittanun; Loiha, Sirinuch; Prayoonpokarach, Sanchai; Wittayakun, Jatuporn

    2015-01-01

    The aim of this work is to determine paraquat adsorption capacity of zeolite NaX and Al-MCM-41. All adsorbents were synthesized by hydrothermal method using rice husk silica. For Al-MCM-41, aluminum (Al) was added to the synthesis gel of MCM-41 with Al content of 10, 15, 20 and 25 wt%. The faujasite framework type of NaX and mesoporous characteristic of Al-MCM-41 were confirmed by X-ray diffraction. Surface area of all adsorbents determined by N2 adsorption-desorption analysis was higher than 650 m2/g. Al content and geometry were determined by X-ray fluorescence and 27Al nuclear magnetic resonance, respectively. Morphology of Al-MCM-41 were studied by transmission electron microscopy; macropores and defects were observed. The paraquat adsorption experiments were conducted using a concentration range of 80-720 mg/L for NaX and 80-560 mg/L for Al-MCM-41. The paraquat adsorption isotherms from all adsorbents fit well with the Langmuir model. The adsorption capacity of NaX was 120 mg/g-adsorbent. Regarding Al-MCM-41, the 10% Al-MCM-41 exhibited the lowest capacity of 52 mg/g-adsorbent while the other samples had adsorption capacity of 66 mg/g-adsorbent.

  12. 介孔分子筛Al-MCM-41磺酸化后的结构和性能%Structures and Properties of Mesoporous Molecular Sieve Al-MCM-41 by Surface Sulfonation

    Institute of Scientific and Technical Information of China (English)

    宋伟明; 米兰; 邓启刚; 陈细涛

    2011-01-01

    Mesoporous AI-MCM-41(A1M) and silanized Al-MCM-41(SiAIM) were prepared through hydrothermal method and functionalized using chlorosulfonic acid. The sulphonic acid groups are covalently bonded to the surface of MCM-41 by etherification of Si-OH with chlorosuifonic acid reaction to obtained SO3H/AI-MCM-41 (SAIM) and SO3H/SiAl-MCM-41 (SSiAlM) respectively. The structures and properties of the products were analyzed by X-ray diffraction (XRD), N2 adsorption-desorption, NH3 programmed temperature desorption (NH3-TPD), surface of elemental analysis (EDS) and thermogravimetric analysis (TG/DTA). The results showed that S percentage grafting on the surface of AlM reached 0.42% when AlM was refluxed for 3 h with chlorosulfonic acid in chloroform. Under the same conditions, S percentage grafting on the SiAlM reached 2.40%. NH3-TPD acid content of SAIM and SAlM were 1.26 mmol/g and 2.28 mmol/g respectively, and both give two NH3 desorption peak (150-200 ℃, 500-520 ℃) corresponding to weak and strong acid center. XRD analysis results showed that SAIM and SSiAlM remained hexagonal mesoporous structure with good symmetry. The specific surface area SAIM and SSiAlM were 815.2 m2/g and 944.5 m2/g, average pore size of 3.2 run. SSiAlM exhibited high catalytic activity in glycol stearate reactions. The esterification rate of stearate can have been 96% when molar ratio of glycol to stearate was 1.2, reaction time 1.0 h and 5% catalyst content. The esterification of 73% can be remained when SSiAlM was reused fourth time.%以氯磺酸为磺化试剂,与Al-MCM-41 (AlM)及硅烷化后Al-MCM-41 (SiAlM)介孔分子筛进行接枝磺化反应,分别得到SO3H/Al-MCM-41 (SAlM)和 SO3H/SiAl-MCM-41 (SSiAlM).采用X射线衍射(XRD)、N2吸附-脱附、NH3程序升温脱附(NH3-TPD)、热重分析(TG/DTA)、表面元素分析(EDS)等手段对产物结构和性能进行了分析表征.研究结果表明,当AlM与氯磺酸在三氯甲烷中同流3h时,产物SAlM中S原子分率为0.42%.同

  13. Synthesis and application of Pb-MCM-41/ZnNiO2 as a novel mesoporous nanocomposite adsorbent for the decontamination of chloroethyl phenyl sulfide (CEPS)

    Science.gov (United States)

    Sadeghi, Meysam; Yekta, Sina; Ghaedi, Hamed

    2017-04-01

    In the current research, MCM-41 was successfully prepared by the sol-gel method and lead ions (Pb2+) were loaded in the synthesized MCM-41 mesoporous structure to prepare Pb-MCM-41. The ZnO-NiO nanoparticles (ZnNiO2 NPs) as a type of bimetallic oxides were then dispersed and deposited on the surface of Pb-MCM-41 through indirect method to gain the final Pb-MCM-41/ZnNiO2 nanocomposite adsorbent. The characterization study of samples carried out by SEM-EDAX, AFM, XRD and FTIR techniques. Pb-MCM-41/ZnNiO2 nanocomposite as a destructive adsorbent has been proposed for the first time for the decontamination process of chloroethyl phenyl sulfide (CEPS), a mimic of bis(chloroethyl) sulfide (i.e. sulfur mustard), and were confirmed using GC-FID, GC-MS and FTIR instruments. Besides, the effect of different experimental parameters including contact time, catalyst dose and initial concentration of CEPS on the decontamination efficiency of this agent simulant were also perused. The GC-FID analysis results verified that the maximum decontamination of CEPS was more than 90% yield. The parameters such as: contact time (240 min), adsorbent dose (0.4 g/L), and initial concentration (10 mg/L) were investigated and considered as optimized conditions for the noted reaction. Moreover, the reaction kinetic information was surveyed by employing first order model. The values of the rate constant (k) and half-life (t1/2) were determined as 0.0128 min-1 and 54.1406 min, and 0.0012 min-1 and 577.5 min for CEPS and its hydrolysis/elimination products, respectively. Data demonstrates the role of the hydrolysis and elimination products, i.e. hydroxy ethyl phenyl sulfide (HEPS) and phenyl vinyl sulfide (PVS) in the reaction of CEPS with Pb-MCM-41/ZnNiO2 nanocomposite and GC-MS analysis was exerted to identify and quantify simulant destruction products. It was clarified that Pb-MCM-41/ZnNiO2 nanocomposite gains a high capacity and potential for the effective decontamination of CEPS.

  14. Photocatalytic Properties of Nb/MCM-41 Molecular Sieves: Effect of the Synthesis Conditions

    Directory of Open Access Journals (Sweden)

    Caterine Daza Gomez

    2015-08-01

    Full Text Available The effect of synthesis conditions and niobium incorporation levels on the photocatalytic properties of Nb/MCM-41 molecular sieves was assessed. Niobium pentoxide supported on MCM-41 mesoporous silica was obtained using two methods: sol-gel and incipient impregnation, in each case also varying the percentage of niobium incorporation. The synthesized Nb-MCM-41 ceramic powders were characterized using the spectroscopic techniques of infrared spectroscopy (IR, Raman spectroscopy, X-ray diffraction (XRD, and transmission electron microscopy (TEM. The photodegradation capacity of the powders was studied using the organic molecule, methylene blue. The effect of both the method of synthesis and the percentage of niobium present in the sample on the photodegradation action of the solids was determined. The mesoporous Nb-MCM-41 that produced the greatest photodegradation response was obtained using the sol-gel method and 20% niobium incorporation.

  15. Synthesis and Characterization of Mesoporous Silica Functionalized with Calix[4]arene Derivatives

    OpenAIRE

    Sana M. Alahmadi; Mohamad, Sharifah; Maah, Mohd Jamil

    2012-01-01

    This work reports a new method to covalently attach calix[4]arene derivatives onto MCM-41, using a diisocyanate as a linker. The modified mesoporous silicates were characterized by fourier transform infrared spectroscopy (FTIR), thermal analysis (TGA) and elemental analysis. The FTIR spectra and TGA analysis verified that the calix[4]arene derivates are covalently attached to the mesoporous silica. The preservation of the MCM-41 channel system was checked by X-ray diffraction and nitrogen ads...

  16. Synthesis and Characterization of Mesoporous Silica Functionalized with Calix[4]arene Derivatives

    Directory of Open Access Journals (Sweden)

    Sana M. Alahmadi

    2012-10-01

    Full Text Available This work reports a new method to covalently attach calix[4]arene derivatives onto MCM-41, using a diisocyanate as a linker. The modified mesoporous silicates were characterized by fourier transform infrared spectroscopy (FTIR, thermal analysis (TGA and elemental analysis. The FTIR spectra and TGA analysis verified that the calix[4]arene derivates are covalently attached to the mesoporous silica. The preservation of the MCM-41 channel system was checked by X-ray diffraction and nitrogen adsorption analysis.

  17. Synthesis and characterization of mesoporous silica functionalized with calix[4]arene derivatives.

    Science.gov (United States)

    Alahmadi, Sana M; Mohamad, Sharifah; Maah, Mohd Jamil

    2012-10-23

    This work reports a new method to covalently attach calix[4]arene derivatives onto MCM-41, using a diisocyanate as a linker. The modified mesoporous silicates were characterized by fourier transform infrared spectroscopy (FTIR), thermal analysis (TGA) and elemental analysis. The FTIR spectra and TGA analysis verified that the calix[4]arene derivates are covalently attached to the mesoporous silica. The preservation of the MCM-41 channel system was checked by X-ray diffraction and nitrogen adsorption analysis.

  18. Sol-gel-cum-hydrothermal synthesis of mesoporous Co-Fe@Al₂O₃−MCM-41 for methylene blue remediation

    Indian Academy of Sciences (India)

    AMARESH C PRADHAN; ANIMESH PAUL; G RANGA RAO

    2017-03-01

    A combined sol-gel-cum-hydrothermalmethod has been employed to synthesize novelmonometallic (Mn, Fe, Co) and bimetallic (Co-Fe, Mn-Co, Fe-Mn) nanoparticles loaded onto Al₂O₃−MCM-41. Powder XRD, N2 sorption, field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) measurements show that the materials possess mesoporosity, high surface area and nanosize. Monometallic Fe, Co and Mn @Al₂O₃−MCM-41 and bimetallic Co-Fe, Fe-Mn and Mn-Co @Al₂O₃−MCM-41 materials were tested for methylene blue remediation from aqueous media. In the present study, Co-Fe@Al₂O₃−MCM-41 was found to be an excellent adsorbent. The adsorption efficiency of Co- Fe@Al₂O₃−MCM-41 has been studied as a function of adsorbent dose and pH of the solution. Maximum adsorption of methylene blue was obtained at high pH values of the solution. Framework mesoporosity, high surface area, and narrow pore distribution are the key factors for an efficient adsorption of methylene blue onCo-Fe@Al₂O₃−MCM-41.

  19. Functionalized bimodal mesoporous silicas as carriers for controlled aspirin delivery

    Science.gov (United States)

    Gao, Lin; Sun, Jihong; Li, Yuzhen

    2011-08-01

    The bimodal mesoporous silica modified with 3-aminopropyltriethoxysilane was performed as the aspirin carrier. The samples' structure, drug loading and release profiles were characterized with X-ray diffraction, scanning electron microscopy, N 2 adsorption and desorption, Fourier transform infrared spectroscopy, TG analysis, elemental analysis and UV-spectrophotometer. For further exploring the effects of the bimodal mesopores on the drug delivery behavior, the unimodal mesoporous material MCM-41 was also modified as the aspirin carrier. Meantime, Korsmeyer-Peppas equation ft= ktn was employed to analyze the dissolution data in details. It is indicated that the bimodal mesopores are beneficial for unrestricted drug molecules diffusing and therefore lead to a higher loading and faster releasing than that of MCM-41. The results show that the aspirin delivery properties are influenced considerably by the mesoporous matrix, whereas the large pore of bimodal mesoporous silica is the key point for the improved controlled-release properties.

  20. Hydroxyapatite/MCM-41 and SBA-15 Nano-Composites: Preparation, Characterization and Applications

    Directory of Open Access Journals (Sweden)

    Andrea R. Beltramone

    2009-09-01

    Full Text Available Composites of hydroxyapatite (HaP and highly ordered large pore mesoporous silica molecular sieves such as, Al-SBA-15 and Al-MCM-41 (denoted as SBA-15 and MCM-41. respectively were developed, characterized by XRD, BET, FTIR, HRTEM and NMR-MAS, and applied to fluoride retention from contaminated water. The proposed procedure by a new route to prepare the HaP/SBA-15 and HaP/MCM-41, composites generates materials with aluminum only in tetrahedral coordination, according to the 27Al NMR-MAS results. Free OH- groups of HaP nanocrystals, within the hosts, allowed high capacity fluoride retention. The activity of fluoride retention using HaP/MCM-41 or HaP/SBA-15 was 1-2 orders of magnitude greater, respectively, than with pure HaP.

  1. Fabrication of MCM-41 fibers with well-ordered hexagonal mesostructure controlled in acidic and alkaline media

    Science.gov (United States)

    Jafarzadeh, A.; Sohrabnezhad, Sh.; Zanjanchi, M. A.; Arvand, M.

    2016-10-01

    In this paper, synthesis and characterization of two type morphologies of the MCM-41mesoporous material, nano and microfibers, were investigated by electrospinning technique. The synthesis was performed in acidic and alkaline media, separately. The MCM-41 morphologies were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray powder diffraction (XRD), and nitrogen adsorption-desorption measurement. Tetraethylorthosilicate (TEOS) and cetyltrimethylammonium bromide (CTAB) were used as silica and template sources for the synthesis of MCM-41 morphologies, respectively. The SEM results showed that MCM-41 nanofibers were spun in acidic media and microfibers of MCM-41 were produced in alkaline media. The XRD study revealed a long range structural ordering of mesoporous materials. The TEM results indicated rough surfaces with uniform average diameter 200 nm for nanofibers and 2 μm for microfibers. The pore diameter and surface area of calcined MCM-41 nanofibers were 2.2 nm and 970 m2/g, respectively. For the MCM-41 microfibers, pore sizes of 2.7 nm and surface areas 420 m2/g was measured.

  2. Synthesis and fluorescence property of Eosin Y/Eu-MCM-41 mesoporous assembly material%曙红/铕-MCM-41介孔材料组装体的制备与发光性能

    Institute of Scientific and Technical Information of China (English)

    许洁; 魏长平; 迟彩霞

    2007-01-01

    室温下制备出介孔材料MCM-41,将稀土离子铕和荧光染料曙红Y作为客体组装到MCM-41主体孔道中,制得Eosin Y /Eu-MCM-41复合型介孔材料组装体.采用XRD、RTIR、N2吸附和激发与发射光谱等技术对样品结构和性能进行了表征.结果表明,制备出的复合型介孔材料组装体仍保持MCM-41的六方有序结构,客体分子主要存在于主体介孔材料孔道中.激发与发射光谱显示曙红Y为发光中心,Eosin Y /Eu-MCM-41组装体的发光强度与Eosin Y-MCM-41比较呈规律性变化,当Eosin Y/Eu摩尔比为1∶1时其发光强度最强.

  3. MCM-41 as a useful vector for rutin topical formulations: synthesis, characterization and testing.

    Science.gov (United States)

    Berlier, Gloria; Gastaldi, Lucia; Sapino, Simona; Miletto, Ivana; Bottinelli, Emanuela; Chirio, Daniela; Ugazio, Elena

    2013-11-30

    Rutin, the glycoside of quercetin, could be used in topical preparations because of its antioxidant and radical scavenging properties, but its employ in cosmetic and pharmaceutical products is limited by poor physico-chemical stability. These issues were addressed by preparing, characterizing and testing rutin inclusion complexes with MCM-41 mesoporous silica. The effect of surface functionalization with aminopropyl groups (NH₂-MCM-41) on the molecules properties was studied. The organic/inorganic interaction was confirmed by many techniques. In particular, the high inclusion of rutin in the pores of NH₂-MCM-41 was assessed by XRD, TGA, gas-volumetric analysis (BET), while FTIR spectroscopy allowed to analyse with great detail the molecular interaction with the inorganic surface. Rutin was stabilized against UV degradation, mostly by its inclusion in NH₂-MCM-41. Ex vivo studies showed a greater accumulation in porcine skin in the case of rutin complexed with NH₂-MCM-41. Not only antioxidant properties of rutin were maintained after immobilization but, with aminopropyl silica, the metal-chelating activity increased noticeably. The immobilization of rutin in aminopropyl silica resulted in better performance in terms of activity and photostability, suggesting the importance of functionalization in stabilizing organic molecules within silica pores.

  4. Direct esterification of olive-pomace oil using mesoporous silica supported sulfonic acids

    Directory of Open Access Journals (Sweden)

    F. Alrouh

    2017-02-01

    Full Text Available Mesoporous silica MCM-41 and SBA-15 containing propyl sulfonic acid groups were synthesized according to the literature and were characterized by X-ray diffraction, N2 adsorption and the H+ exchange capacities of the sulfonic acid groups were titrated. The esterification reaction of glycerol with olive-pomace oil has been carried out by using prepared functionalized mesoporous silica (MCM-41 and SBA-15 as catalysts. It has been monitored by GC two fatty acids (palmitic and oleic acids as reactants in olive-pomace oil and their related monoacylglycerols (Glycerol monopalmitate GMP and monooleate GMO as reaction product. The catalytic activities of the functionalized mesoporous silica were compared with commercial catalysts, these included homogeneous catalysts (p-toluenesulfonic acid and heterogeneous catalysts (Amberlyst-15. The total yield of monoacylglycerols (GMO + GMP was nearly 40%. Remarkably, we found that MCM-41-SO3H was recycled at least 3 times without any loss of activity.

  5. Microspectroscopic analysis of green fluorescent proteins infiltrated into mesoporous silica nanochannels.

    NARCIS (Netherlands)

    Ma, Y.; Rajendran, P.; Blum, C.; Cesa, Y.; Gartmann, N.; Bruhwiler, D.; Subramaniam, V.

    2011-01-01

    The infiltration of enhanced green fluorescent protein (EGFP) into nanochannels of different diameters in mesoporous silica particles was studied in detail by fluorescence microspectroscopy at room temperature. Silica particles from the MCM-41, ASNCs and SBA-15 families possessing nanometer-sized (3

  6. Ce-MCM-41分子筛用于臭氧氧化对氯苯甲酸的活性评价%Synthesis of cerium-doped MCM-41 for ozonation of p-chlorobenzoic acid

    Institute of Scientific and Technical Information of China (English)

    邴吉帅; 曾俊喻; 廖高祖; 李旭凯; 蓝冰燕; 张秋云; 李来胜

    2012-01-01

    Cerium-doped MCM-41(Ce-MCM-41) was prepared by a hydrothermal method and its catalytic activity for ozonation of p-chlorobenzoic acid(p-CBA) in aqueous solution was studied.Ce-MCM-41 was characterized by low angle X-ray powder diffraction(XRD),nitrogen adsorption-desorption(BET),ultraviolet-visible diffuse reflection spectrum(UV-Vis DRS) and transmission electron microscopy(TEM).The results showed that the material retained a highly ordered mesopore structure of pure silica MCM-41 and had a high surface area.Cerium was incorporated into the framework of MCM-41,locating at tetrahedrally coordinated sites.Ce-MCM-41 significantly improved the effect of ozone oxidation.After 60 min reaction time,TOC removal rate was 63% with MCM-41,86% with Ce-MCM-41(Si/Ce=60),while only 52% with O3 alone.Besides,Ce-MCM-41 had much less cerium leaching(0.085 mg·L-1) compared with that of Ce/MCM-41(0.44 mg·L-1).After being used for three times,TOC removal rate decreased only by 5%,while p-CBA removal rate kept nearly constant.Ce-MCM-41 is a promising catalyst for ozonation process.%通过水热法合成了铈掺杂MCM-41(Ce-MCM-41)介孔分子筛,并将其用于臭氧氧化水中对氯苯甲酸(p-CBA).小角X射线衍射(XRD)、氮气吸附-脱附(BET)、紫外可见漫反射光谱(UV-Vis DRS)、透射电镜(TEM)表征结果表明,铈成功进入MCM-41分子筛骨架,以正四面体形式存在,且Ce-MCM-41保持了纯硅MCM-41有序的介孔结构,具有较高的比表面积;铈的掺杂显著提高MCM-41催化臭氧氧化对氯苯甲酸的活性,反应60 min后,TOC去除率由MCM-41的63%提高到86%(Si/Ce=60),而单独臭氧氧化仅为52%;铈的溶出仅为0.085 mg.L-1,较同样负载量的铈负载Ce/MCM-41的溶出(0.44 mg.L-1)有较大减少.催化剂重复使用3次后仍保持较高的活性,这表明Ce-MCM-41具有较好的活性和稳定性,是一种有前景的臭氧氧化催化剂.

  7. Ethylenediamine-modified oriented MCM-41 at the electrode surface, cobalt adsorption ability and electrochemical performance.

    Science.gov (United States)

    Rafiee, Mohammad; Karimi, Babak; Arshi, Simin; Vali, Hojatollah

    2014-03-28

    Mesoporous silica thin films (MCM-41) functionalized with ethylenediamine groups were electrochemically fabricated on electrode surfaces. These ligand functionalized film were a promising matrix for the immobilization of cobalt ions and preparation of cobalt complexes covalently bound to the MCM-41 support. The constructed MCM-41 were characterized by TEM, EDS and TGA analysis. This method yields uniform thin films with hexagonal mesochannels aligned and accessible to electrode surface. Well-defined electrode responses were, therefore, observed for the anchored complexes which made the electrochemical analysis of the structure possible as well. Voltammetric studies revealed the reactivity of the covalently bound complexes differed significantly from the dissolved ones. The anchored complexes preferred to be in their oxidized form which inhibits formation of oxygen adducts. The covalently bound complexes had relatively good leaching stability with good catalytic performance towards hydrogen peroxide reduction.

  8. Enhanced photocatalytic and adsorptive degradation of organic dyes by mesoporous Cu/Al2O3-MCM-41: intra-particle mesoporosity, electron transfer and OH radical generation under visible light.

    Science.gov (United States)

    Pradhan, Amaresh C; Parida, K M; Nanda, Binita

    2011-07-28

    Mesoporous Cu/Al(2)O(3)-MCM-41 composite was synthesized by two step processes; in situ incorporation of high surface area mesoporous Al(2)O(3) (MA) into the framework of MCM-41 (in situ method) followed by impregnation of Cu(II) by incipient wetness method. The interesting thing is that starch was used for the first time as template for the preparation of high surface area MA. To evaluate the structural and electronic properties, these catalysts were characterized by low angle X-ray diffraction (LXRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), UV-vis DRS, FTIR and photoluminescent (PL) spectra. The various cationic dye such as methylene blue (MB), methyl violet (MV), malachite green (MG) and rhodamine 6G (Rd 6G) of high concentration 500 mg L(-1) were degraded and adsorbed very efficiently (100%) using the 5 Cu/Al(2)O(3)-MCM-41 composite within 30 and 60 min, respectively. The high and quick removal of such concerted cationic organic dyes and also mixed dyes (MB+MV+MG+Rd 6G) by means of photocatalysis/adsorption is basically due to the combined effect three characteristics of synthesized mesoporous 5 Cu/Al(2)O(3)-MCM-41 composite. These characteristics are intra-particle mesoporosity, electron transfer and ˙OH radical generation under solar light.

  9. Hidrólise de celulose por catalisadores mesoestruturados NiO-MCM-41 e MoO3-MCM-41

    Directory of Open Access Journals (Sweden)

    Adriano Sant'Ana Silva

    2012-01-01

    Full Text Available This study was carried out to synthesize, characterize and evaluate the application of mesoestruturated catalysts MCM-41, 5%MoO3-MCM-41 and 5%NiO-MCM-41 in the hydrolysis of microcrystalline cellulose. XRD results indicate that the phase of mesoporous MCM-41 was obtained and that the introduction of metal oxides did not affect this mesoporous phase. About the heterogeneous hydrolysis reaction, it was observed that the increase in temperature results in a higher concentration of glucose and the catalyst 5%MoO3-MCM-41 provides the highest concentrations of glucose.

  10. Effects of Fumed and Mesoporous Silica Nanoparticles on the Properties of Sylgard 184 Polydimethylsiloxane

    OpenAIRE

    Junshan Liu; Guoge Zong; Licheng He; Yangyang Zhang; Chong Liu; Liding Wang

    2015-01-01

    The effects of silica nanoparticles on the properties of a commonly used Sylgard 184 polydimethylsiloxane (PDMS) in microfluidics were systemically studied. Two kinds of silica nanoparticles, A380 fumed silica nanoparticles and MCM-41 mesoporous silica nanoparticles, were individually doped into PDMS, and the properties of PDMS with these two different silica nanoparticles were separately tested and compared. The thermal and mechanical stabilities of PDMS were significantly enhanced, and the ...

  11. 废弃硅藻土制备MCM-41介孔分子筛的表征及吸附性能研究%Study on surface features of mesoporous silica particles made by spent diatomaceous earth and performance of adsorption

    Institute of Scientific and Technical Information of China (English)

    孙燕; 陶红; 张章堂; 卑蕾蕾; 宋晓锋; 陈良霞

    2013-01-01

    以废弃硅藻土作为硅源,CTAB为模板剂,通过水热法合成介孔材料MCM-41,并使用X-射线荧光分析仪(XRF),X-射线粉末衍射仪(XRD),氮气等温吸附/脱附仪,傅利叶红外线吸收光谱仪(FT-IR),热重量分析仪(TGA),扫描式电子显微镜结合X射线能量色散谱(SEM-EDS)和高分辨率穿透式电子显微镜分析(HRTEM)等方式进行表征;通过吸附重金属离子实验检测该材料的性能.结果表明:所合成的材料为介孔结构,孔道排列较为整齐,MCM-41的比表面积为1060.2 cm2/g,平均孔洞体积约为1.05 cm3/g,孔径为3.95 nm,孔径分布窄,对重金属Ca2+有很好的吸附性能.本研究对废弃硅藻土的综合利用及重金属的治理具有一定的参考价值.

  12. Mesoporous silica as a carrier for topical application: the Trolox case study.

    Science.gov (United States)

    Gastaldi, L; Ugazio, E; Sapino, S; Iliade, P; Miletto, I; Berlier, G

    2012-08-28

    As part of a recent research effort aimed at employing mesoporous materials for controlled drug delivery, this paper presents MCM-41 as a carrier for topical application, using Trolox as a model unstable guest molecule. The complexes between Trolox and MCM-41 were prepared by employing different inclusion procedures, varying solvent, method and pretreatment of the silica matrix. The objectives of this study were to determine Trolox loading, analyze its integrity and availability after immobilization on mesoporous silica, evaluate MCM-41 influence on Trolox photodegradation and establish whether the preparation method significantly influences complex properties. The characterization analyses (XRD, TGA, DSC and FTIR) confirmed the hydrogen-bonding interaction and Trolox structure preservation. Gas-volumetric analysis showed a consistent decrease in surface area and in pore volume and diameter with respect to bare MCM-41 indicating that Trolox was mainly located within mesopores. In vitro diffusion tests showed a slower release of Trolox after inclusion in the MCM-41 matrix; at the same time UV irradiation studies highlighted an increased photostability for the complex particularly in O/W emulsion. Moreover the radical scavenging activity of Trolox was maintained after immobilization. In all cases, differences were observed in all tested samples, suggesting that results could be optimized by modifying the inclusion procedure and by improving the guest loading.

  13. Ni2P/Al-MCM-41催化剂的制备及其加氢脱硫性能%Preparation and hydrodesulfurization performance of Al-MCM-41 supported nickel phosphide catalysts

    Institute of Scientific and Technical Information of China (English)

    匡志敏; 龚建议; 杨运泉; 王威燕; 陈来福; 贺恒

    2011-01-01

    A1-MCM-41 mesoporous molecular sieves were prepared by the azeotropic distillation and ultrasonic dispersive technology using sodium silicate as silica source , aluminum sulfate as aluminum source and cetyltrimethyl ammonium bromide as structure-directing agent. By using A1-MCM-41 as support, nickel nitrate and diammonium hydrogen phosphate as raw materials, a series of supported Ni2P catalysts on A1-MCM-41 was prepared via the method of temperature-programmed reduction under ultrasonic oscillation. The catalysts were characterized by FT1R, BET, XRD and SEM.Hydrodesulfurization of thiophene catalyzed by Ni2P/Al-MCM-41 was carried out in a high pressure autoclave reactor. The experimental results showed that Al-MCM-41 prepared by ultrasonic dispersive technology had a much higher specific surface area, larger pore volume and pore diameter than that prepared by conventional mechanical mixing. The Al-MCM-41 prepared by azeotropic distillation with ultrasonic dispersive technology was also better than that using only ultrasonic dispersive technology.The Ni2P/A1-MCM-41 catalysts, hydrodesulfurization conversion of thiophene nearly reached 100% at the reaction time 5 h, reaction temperature 548 K, and reaction pressure 3.5 MPa.%以硅酸钠为硅源、硫酸铝为铝源、十六烷基三甲基溴化铵(CTAB)作模板剂,采用共沸蒸馏与超声波分散技术相结合的方法制备了介孔分子筛Al-MCM-41.以Al-MCM-41为载体,硝酸镍和磷酸氢二氨为原料,采用超声波振荡、程序升温还原法制备了Ni2P/Al-MCM-41催化剂,并对Al-MCM-41和Ni2P/Al-MCM-41进行了傅里叶变换红外光谱、比表面积测定、X射线衍射、扫描电镜表征.考察了Ni2P/Al-MCM-41催化剂对噻吩加氢脱硫的催化性能.结果表明:采用超声波制得的Al-MCM-41其比表面积,孔容和孔径明显高于常规搅拌制得的Al-MCM-41,共沸蒸馏制得的Al-MCM-41其比表面积、孔容和孔径高于未共沸蒸馏的Al-MCM-41;

  14. Activators generated by electron transfer for atom transfer radical polymerization of styrene in the presence of mesoporous silica nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Khezri, Khezrollah, E-mail: kh.khezri@ut.ac.ir [School of Chemistry, University College of Science, University of Tehran, PO Box 14155-6455, Tehran (Iran, Islamic Republic of); Roghani-Mamaqani, Hossein [Department of Polymer Engineering, Sahand University of Technology, PO Box 51335-1996, Tabriz (Iran, Islamic Republic of)

    2014-11-15

    Graphical abstract: Effect of mesoporous silica nanoparticles (MCM-41) on the activator generated by electron transfer for atom transfer radical polymerization (AGET ATRP) is investigated. Decrement of conversion and number average molecular weight and also increment of polydispersity index (PDI) values are three main results of addition of MCM-41 nanoparticles. Incorporation of MCM-41 nanoparticles in the polystyrene matrix can clearly increase thermal stability and decrease glass transition temperature of the nanocomposites. - Highlights: • Spherical morphology, hexagonal structure, and high surface area with regular pore diameters of the synthesized MCM-41 nanoparticles are examined. • AGET ATRP of styrene in the presence of MCM-41 nanoparticles is performed. • Effect of MCM-41 nanoparticles addition on the polymerization rate, conversion and molecular weights of the products are discussed. • Improvement in thermal stability of the nanocomposites and decreasing T{sub g} values was also observed by incorporation of MCM-41 nanoparticles. - Abstract: Activator generated by electron transfer for atom transfer radical polymerization was employed to synthesize well-defined mesoporous silica nanoparticles/polystyrene composites. Inherent features of spherical mesoporous silica nanoparticles were evaluated by nitrogen adsorption/desorption isotherm, X-ray diffraction and scanning electron microscopy analysis techniques. Conversion and molecular weight evaluations were carried out using gas and size exclusion chromatography respectively. By the addition of only 3 wt% mesoporous silica nanoparticles, conversion decreases from 81 to 58%. Similarly, number average molecular weight decreases from 17,116 to 12,798 g mol{sup −1}. However, polydispersity index (PDI) values increases from 1.24 to 1.58. A peak around 4.1–4.2 ppm at proton nuclear magnetic resonance spectroscopy results clearly confirms the living nature of the polymerization. Thermogravimetric

  15. Adsorption-based CO2 Capture by Amino-functionalized Pore-expanded MCM-41 Composite%氨基官能化的扩孔 MCM-41复合材料吸附捕集 CO2

    Institute of Scientific and Technical Information of China (English)

    陈超; 董宇翔

    2015-01-01

    Pore-expanded mesoporous silica ( MCM-41) was synthesized and employed as a host for grafting 3-[2-(2-aminoethylamino)ethylamino]propyl trimethoxysilane to obtain an amino-functionalized mesoporous silica compos-ite.The pore-expanded MCM-41 before and after amine immobilization were characterized by N 2 adsorption-desorption measurement , fourier-transform infrared spectroscopy , and thermal gravimetric analysis .CO2 capture performances of samples were then examined .Results showed that surface area , pore volume, and pore size of amino-functionalized pore-expanded MCM-41 composite were lower than those of pore-expanded MCM-41.At the same time, amino-func-tionalized pore-expanded MCM-41 composite showed much higher CO 2 adsorption capacity than that of pore-expanded MCM-41 only ( their CO2 capture capacity is 28 mg/g and 76 mg/g, respectively ) , and excellent stability in the cyclic CO2 adsorption-desorption experiments .%制备了扩孔的介孔氧化硅MCM-41,然后以其为载体,通过化学接枝法将3-[2-(2-氨基乙基氨基)乙基氨基]丙基-三甲氧基硅烷嫁接到其介孔结构中,制备了氨基官能化的介孔氧化硅复合材料。通过 N2吸附脱附实验、红外光谱、热重分析等手段对氨基官能化前后扩孔 MCM-41的物理化学属性进行了表征,然后考察了复合材料对CO2的吸附捕集性能。结果表明:与单纯扩孔 MCM-41相比,氨基官能化的扩孔 MCM-41复合材料的比表面积、总孔容及孔径均减小;同时,所制复合材料对 CO2的吸附量明显增大(两者的 CO2吸附量分别为28 mg/g 和76 mg/g),且在循环CO2吸附脱附实验中呈现出优异的稳定性。

  16. Multifunctional mesoporous silica catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Victor Shang-Yi; Tsai, Chih-Hsiang; Chen, Hung-Ting; Pruski, Marek; Kobayashi, Takeshi

    2015-03-31

    The present invention provides bifunctional silica mesoporous materials, including mesoporous silica nanoparticles ("MSN"), having pores modified with diarylammonium triflate and perfluoroaryl moieties, that are useful for the acid-catalyzed esterification of organic acids with organic alcohols.

  17. Fabrication of phosphotungstic acid functionalized mesoporous silica composite membrane by alternative tape-casting incorporating phase inversion technique

    Science.gov (United States)

    Bai, Li; Zhang, Lan; He, Hong Quan; Rasheed, Raj Kamal S./O. Abdul; Zhang, Cai Zhi; Ding, Ovi Lian; Chan, Siew Hwa

    2014-01-01

    Meso-porous silica (MCM-41) membranes functionalized by phosphotungstic acid (HPW) for high temperature proton exchange membrane fuel cells (HT-PEMFCs) are successfully developed by a cost-effective tape-casting incorporating phase inversion and vacuum assisted wet impregnation techniques. The microstructure of the membrane is characterized by field emission scanning electron microscopy (FESEM). The effect of MCM-41 content on the tensile strength, ultimate elongation, and weight gain ratio and swelling ratio in water/methanol of the membranes are investigated in detail. The thermal stability of MCM-41 membrane with/without HPW is analyzed by thermogravimetric analysis (TGA) and derivative thermogravimetry (DTG) techniques. In particular, the effects of HPW loading and MCM-41 content on the proton conductivity of HPW/MCM-41 membranes are studied comprehensively. The results on the swelling ratio and tensile tension show that the developed membranes can be applied as an electrolyte membrane for HT-PEMFCs. The developed MCM-41 membrane, in which polyethersulfone (PESf) is used as the supporting backbone, is able to operate up to 200 °C. The single cell assembled from HPW/MCM-41 membrane with 70 wt.% HPW loading gives a peak output power of ∼230 mW cm-2 and ∼125 mW cm-2 in H2/air at 90 °C and in methanol/air at 150 °C without any humidification, respectively.

  18. o-Vanillin functionalized mesoporous silica - coated magnetite nanoparticles for efficient removal of Pb(II) from water

    Science.gov (United States)

    Culita, Daniela C.; Simonescu, Claudia Maria; Patescu, Rodica-Elena; Dragne, Mioara; Stanica, Nicolae; Oprea, Ovidiu

    2016-06-01

    o-Vanillin functionalized mesoporous silica - coated magnetite (Fe3O4@MCM-41-N-oVan) was synthesized and fully characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, N2 adsorption-desorption technique and magnetic measurements. The capacity of Fe3O4@MCM-41-N-oVan to adsorb Pb(II) from aqueous solutions was evaluated in comparison with raw mesoporous silica - coated magnetite (Fe3O4@MCM-41) and amino - modified mesoporous silica coated magnetite (Fe3O4@MCM-41-NH2). The effect of adsorption process parameters such us pH, contact time, initial Pb(II) concentration was also investigated. The adsorption data were successfully fitted with the Langmuir model, exhibiting a maximum adsorption capacity of 155.71 mg/g at pH=4.4 and T=298 K. The results revealed that the adsorption rate was very high at the beginning of the adsorption process, 80-90% of the total amount of Pb(II) being removed within the first 60 min, depending on the initial concentration. The results of the present work suggest that Fe3O4@MCM-41-N-oVan is a suitable candidate for the separation of Pb(II) from contaminated water.

  19. High enantioselectivity in the asymmetric hydrogenation of ketones by a supported Pt nanocatalyst on a mesoporous modified MCM-41 support

    Institute of Scientific and Technical Information of China (English)

    Susmit Basu

    2015-01-01

    Catalysts containing metal nanotubes were prepared by the adsorption of platinum metal nano‐tubes onto functionalized and modified silica surfaces (MCM‐41 and fumed silica). (3‐Chloropro‐pyl)trimethoxysilane and cinchonidine were used for functionalization and modification, respec‐tively. Potassium chloroplatinate was used as the metal precursor to impregnate platinum metal nanotubes on the pretreated functionalized and modified silica surfaces. The solid catalysts were characterized by ESEM, TEM, EDAX, and XPS. The MCM‐41 supported platinum nanotube catalyst showed>98%to~100%enantioselectivity towards the hydrogenation of a range of pharmaceuti‐cally important chemicals such as methyl pyruvate, ethyl pyruvate, and acetophenone with nearly full conversion.

  20. Synthesis, Characterization and Catalytic Activity of Cu-Zn-Al-MCM-41 Mesoporous Molecular Sieves%Cu-Zn-Al-MCM-41介孔分子筛的合成、表征及催化性能研究

    Institute of Scientific and Technical Information of China (English)

    杨蓓玉; 顾剑江; 赵峰; 姚娟; 菅盘铭

    2013-01-01

    The catalysts of different copper content Cu-Zn-Al-MCM-41 mesoporous molecular sieves were synthesized by hydrothermal method with cetyltrimethylammonium bromide (CTAB) as template, sodium silicate as silicon source and copper nitrate, zinc sulfate, aluminium nitrate as metal source. The catalysts were characterized by XRD, TEM, FT-IR, UV-vis and BET, respectively, and their catalytic abilities were investigated by CO hydrogenation. The results show that the Cu-Zn-Al-MCM-41 mesoporous molecular sieves have uniform hexagonal mesoporous structure and uniform pore distribution with average pore diameter of about 2.5 nm. The metal ions are incorporated into the framework of MCM-41. With the increase of copper content the pore diameter of MCM-41 is increased while the surface area is decreased. The catalysts have hydrogenation and dehydration bifunctional catalytic ability. The hydrogenation of CO over the catalysts can yield 2-butanol with 2-propanol as the solvent and during the hydrogenation the catalytic activity of the catalyst is good. The conversion of CO is increased with increasing copper content of the catalyst. The conversion of CO is 89%under the condition of using the catalyst with nSi:nCu:nZn:nAl=40:4:1:1, reaction temperature=493 K and reaction time=4 h.%采用水热合成法,以十六烷基三甲基溴化铵(CTAB)为模板剂,硅酸钠为硅源,硝酸铜、硫酸锌、硝酸铝为金属源,合成了不同铜含量的Cu-Zn-Al-MCM-41介孔分子筛。利用XRD、TEM、FT-IR、UV-vis和BET技术手段对合成样品进行表征,并考察其对CO加氢反应的催化性能。结果表明,合成的Cu-Zn-Al-MCM-41介孔分子筛具有典型的六方介孔结构,孔径均一,平均直径在2.5 nm左右,且金属离子进入分子筛骨架结构中。随着铜含量的增加,孔径增大而比表面积降低。该催化剂具有加氢脱水双功能催化作用,在异丙醇存在下,对CO加氢反应生成仲

  1. Effects of Fumed and Mesoporous Silica Nanoparticles on the Properties of Sylgard 184 Polydimethylsiloxane

    Directory of Open Access Journals (Sweden)

    Junshan Liu

    2015-07-01

    Full Text Available The effects of silica nanoparticles on the properties of a commonly used Sylgard 184 polydimethylsiloxane (PDMS in microfluidics were systemically studied. Two kinds of silica nanoparticles, A380 fumed silica nanoparticles and MCM-41 mesoporous silica nanoparticles, were individually doped into PDMS, and the properties of PDMS with these two different silica nanoparticles were separately tested and compared. The thermal and mechanical stabilities of PDMS were significantly enhanced, and the swelling characteristics were also improved by doping these two kinds of nanoparticles. However, the transparency of PDMS was decreased due to the light scattering by nanoparticles. By contrast, PDMS/MCM-41 nanocomposites showed a lower coefficient of thermal expansion (CTE owing to the mesoporous structure of MCM-41 nanoparticles, while PDMS/A380 nanocomposites showed a larger elastic modulus and better transparency due to the smaller size of A380 nanoparticles. In addition, A380 and MCM-41 nanoparticles had the similar effects on the swelling characteristics of PDMS. The swelling ratio of PDMS in toluene was decreased to 0.68 when the concentration of nanoparticles was 10 wt %.

  2. Effect of amine functionalization of spherical MCM-41 and SBA-15 on controlled drug release

    Science.gov (United States)

    Szegedi, A.; Popova, M.; Goshev, I.; Mihály, J.

    2011-05-01

    MCM-41 and SBA-15 silica materials with spherical morphology and different particle sizes were synthesized and modified by post-synthesis method with 3-aminopropyltriethoxysilane (APTES). A comparative study of the adsorption and release of a model drug, ibuprofen, were carried out. The modified and drug loaded mesoporous materials were characterized by XRD, TEM, N 2 physisorption, thermal analysis, elemental analysis and FT-IR spectroscopy. Surface modification with amino groups resulted in high degree of ibuprofen loading and slow rate of release for MCM-41, whereas it was the opposite for SBA-15. The adsorbed drug content and the delivery rate can be predetermined by the choice of mesoporous material with the appropriate structural characteristics and surface functionality.

  3. Conditions of Using Mesoporous Molecular Sieves Al-MCM-41 as Catalyst to Synthesize Isoprene Ene Acid Ethyl Ester as Pesticide%利用中孔分子筛Al-MCM-41催化合成农药异戊烯酸乙酯的条件

    Institute of Scientific and Technical Information of China (English)

    唐晓红; 吴崇珍; 梁丽珍; 李成未; 李保军

    2012-01-01

    [方法]利用中孔分子筛A1-MCM-41作催化剂,直接用反应物乙醇作带水剂,以乙醇和异戊烯酸为原料,采用分批补充乙醇的工艺方法合成农药异戊烯酸乙酯.考察了催化剂用量、反应物物质的量比、反应温度和反应时间对反应转化率和选择性的影响.[结果]该反应最佳的合成条件:异戊烯酸和乙醇的物质的量比为1∶8,催化剂的量为异戊烯酸质量的1.8%,反应时间为6h,反应在剧烈回流温度下进行.在此条件下,异戊烯酸转化率可达89.9%,产品纯度大于99.7%.[结论]中孔分子筛Al-MCM-41可作为合成异戊烯酸乙酯高效而环保的固体酸催化剂.%[Methods] The isoprene ene acid ethyl ester was synthesized from isoprene ene acid and ethanol by using mesoporous molecular sieves AI-MCM-41 as catalyst and directly using reactant ethanol as dehydrant. The process methods of replenishing ethanol in batches was used. The factors such as catalyst amount, reactant ratio, reaction temperature and reaction time which affect the conversion and selectivity were investigated. [Results] The experimental result showed that the optimum conditions are as follows: the mole ratio of isoprene ene acid to ethanol is 1:8: the amount of catalyst is 1.8% to isoprene ene acid: the reaction time is 6 h at reflux temperature. The conversion is 89.9% and the purity of the product is above 99.7% under the optimum conditions. [Conclusions] The mesoporous molecular sieves AI-MCM-41 can be used as efficient and environmental solid acid catalyst on the catalytic synthesis of isoprene ene acid ethyl ester.

  4. Polyacrolein/mesoporous silica nanocomposite: Synthesis, thermal stability and covalent lipase immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Motevalizadeh, Seyed Farshad; Khoobi, Mehdi; Shabanian, Meisam [Department of Medicinal Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences Research Center, Tehran University of Medical Sciences, Tehran 14176 (Iran, Islamic Republic of); Asadgol, Zahra; Faramarzi, Mohammad Ali [Department of Pharmaceutical Biotechnology, Faculty of Pharmacy and Biotechnology Research Center, Tehran University of Medical Sciences, P.O. Box 14155-6451, Tehran 14176 (Iran, Islamic Republic of); Shafiee, Abbas, E-mail: ashafiee@ams.ac.ir [Department of Medicinal Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences Research Center, Tehran University of Medical Sciences, Tehran 14176 (Iran, Islamic Republic of); Center of Excellence in Biothermodynamics, University of Tehran, Tehran (Iran, Islamic Republic of)

    2013-12-16

    In this work, new polyacrolein/MCM-41 nanocomposites with good phase mixing behavior were prepared through an emulsion polymerization technique. Mesoporous silica was synthesized by in situ assembly of tetraethyl orthosilicate (TEOS) and cetyl trimethyl ammonium bromide (CTAB). The structure and properties of polyacrolein containing nanosized MCM-41 particle (5 and 10 wt%), were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, Dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N{sub 2} adsorption techniques, and thermogravimetric (TGA) analyses. The SEM images from the final powder have revealed good dispersion of the MCM-41 nanoparticles throughout polymeric matrix with no distinct voids between two phases. The results indicated that the thermal properties of the nanocomposite were enhanced by addition of MCM-41. Thermomyces lanuginosa lipase (TLL) was used as a model biocatalyst and successfully immobilized with polyacrolein and the nanocomposite via covalent bonds with the aldehyde groups. The activity between free enzyme, polyacrolein, and MCM-41 nanocomposite (10 wt%)-immobilized TLL was compared. The immobilized lipase with the nanocomposite shows better operational stability such as pH tolerance, thermal and storage stability. In addition, the immobilized lipase with the nanocomposite can be easily recovered and retained at 74% of its initial activity after 15 time reuses. - Graphical abstract: The influence of incorporation of mesoporous MCM-41 nanoparticle with polyacrolein on the thermal properties and enzyme immobilization was investigated. - Highlights: • Polyacrolein/MCM-41 nanocomposites were prepared by emulsion polymerization method. • Thermal stability and char residues in nanocomposites were improved. • Nanocomposites significant effects on immobilization of lipase.

  5. Fe/MCM-41催化臭氧氧化水中对氯苯甲酸的研究%Catalytic Ozonation of p-Chlorobenzoic Acid in Aqueous Solution by Fe/MCM-41

    Institute of Scientific and Technical Information of China (English)

    唐莉莉; 刘杰; 黄瑞欢; 孙丰强; 张秋云

    2013-01-01

    The catalytic activity of MCM -41 and Fe loaded MCM -41 (Fe/MCM -41) for ozonation of p - chlo-roberizoic acid (p -CBA) in aqueous solution was investigated. MCM -41 and Fe/MCM -41 were synthesized by a direct hydrothermal method and characterized by XRD, DR UV - Vis and FT - IR. The results showed that MCM - 41 and Fe/MCM -41 presented mesoporous hexagonal structure with large surface area. The presence of MCM -41 and Fe/MCM -41 improved the p - CBA and TOC removal in the ozonation process, while Fe/MCM -41 showed better catalytic activity because of its synergistic effect with O3. The TOC (p - CBA) removal efficiency in Fe/MCM -41/O3 process was 51. 4% (86. 6% ) at 60 (30) min, 39. 4 % (79. 4% ) using MCM -41 as catalyst, only 35. 4% (72. 1% ) with ozone alone.%利用水热法合成介孔材料MCM-41及Fe负载的MCM-41(Fe/MCM-41),并通过催化臭氧氧化水中对氯苯甲酸(p-CBA),考察其催化性能.经过X射线粉末衍射(XRD)、紫外可见漫反射光谱(DR UV-Vis)、傅立叶红外光谱(FT-IR)及比表面(BET)表征,表明所合成的MCM-41及Fe/MCM-41具有较规则的六方孔道结构及较大的比表面积.MCM-41与Fe/MCM-41的加入有利于p-CBA和TOC的去除,其中Fe/MCM-41与O3具有协同效应,表现出较好的催化活性.

  6. Magnetic α-Fe2O3/MCM-41 nanocomposites: preparation, characterization, and catalytic activity for methylene blue degradation.

    Science.gov (United States)

    Ursachi, Irina; Stancu, Alexandru; Vasile, Aurelia

    2012-07-01

    Catalysts based on nanosized magnetic iron oxide stabilized inside the pore system of ordered mesoporous silica MCM-41 have been prepared. The obtained materials were characterized by powder X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and N(2) adsorption-desorption isotherm. XRD analysis showed that the obtained materials consist from the pure hematite crystalline phase (α-Fe(2)O(3)) dispersed within ordered mesoporous silica MCM-41. Magnetic measurements show that the obtained nanocomposites exhibit at room temperature weak ferromagnetic behavior with slender hysteresis. The catalytic activity of the magnetic α-Fe(2)O(3)/MCM-41 nanocomposites was evaluated by the degradation of methylene blue (MB) aqueous solution. For this purpose, an ultrasound-assisted Fenton-like process was used. The effect of solution pH on degradation of MB was investigated. The results indicated that US-H(2)O(2)-α-Fe(2)O(3)/MCM-41 nanocomposite system is effective for the degradation of MB, suggesting its great potential in removal of dyes from wastewater. It was found that the degradation rate of MB increases with decrease in the pH value of the solution.

  7. A Smart pH-responsive Nano-Carrier as a Drug Delivery System: A hybrid system comprised of mesoporous nanosilica MCM-41 (as a nano-container) & a pH-sensitive polymer (as smart reversible gatekeepers): Preparation, characterization and in vitro release studies of an anti-cancer drug.

    Science.gov (United States)

    Abbaszad Rafi, Abdolrahim; Mahkam, Mehrdad; Davaran, Soodabeh; Hamishehkar, Hamed

    2016-10-10

    A smart pH-responsive drug nano-carrier for controlled release of anti-cancer therapeutics was developed through a facile route. The nano-carrier consisted of two main parts: first, the nano-container part (that mesoporous silica nanoparticles (MCM-41) were selected for this aim); and second, pH-sensitive gatekeepers (that a pH-sensitive polymer, Poly4-vinylpyridine, played this role). In the first step, MCM-41 was synthesized via template assisted sol-gel process. In the second step, polymerizable functional groups were attached onto pore entrances rather than inside walls. In the third step, polymeric gatekeepers were introduced onto pore entrances via precipitation polymerization of functionalized MCM-41 with monomers. Different methods and analysis, such as Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Powder Diffraction (XRD), Thermo-Gravimetric Analysis (TGA), Energy-Dispersive X-ray Spectroscopy (EDX), Zeta Potentials, Dynamic Light Scattering (DLS), Field Emission Scanning Electron Microscope (FE-SEM) and Transmission Electron Microscopy (TEM) were employed to approve the successful attachment of gatekeepers. Furthermore, the release studies of methotroxate (MTX), an anti-cancer drug, were performed in different media (pH4, 5.8 and 7.4) at 37±1°C. The release profiles and curves show that the release rates are completely pH-dependent and it proceeds with a decrease in pH. It is concluded that in the higher pH the gatekeepers are in their close state, but they switch to the open state as a consequence of repulsive forces between positively charged polymer chains appear in acidic media. The results suggest that this smart nano-carrier can be considered as an appropriate candidate to deliver therapeutics to cancerous tissues.

  8. Studies on the Polymerization of Styrene in the MCM-41 Phase

    Institute of Scientific and Technical Information of China (English)

    屈玲; 佟大明; 吕志平; 萧墉壮; 窦涛

    2003-01-01

    The polymerization of styrene in the media of MCM-41 is carried out by means of host-guest polymerization of styrene in MCM-41 mesoporous material with the aim to investigate the effects of interface and confinement of MCM-41 on host-guest interactions. Detailed physical properties of the mesoporous MCM-41 material containing polystyrene is characterized by XRD(X-ray diffraction), FT-IR(Fourier transform infrared), TGA(thermal gravimetric analysis), and nitrogen adsorption-desorption isotherms. We also find a great increase in the glass transition temperature of guest polystyrene influenced by the confined geometry of the host by differential scanning calorimetry(DSC).

  9. Molecular simulation of CO2 adsorption on amine modified micro/mesoporous composite of AM-5A-MCM-41%氨基修饰微孔/介孔复合材料AM-5A-MCM-41对CO2吸附分离的分子模拟

    Institute of Scientific and Technical Information of China (English)

    周建海; 赵会玲; 胡军; 刘洪来; 胡英

    2014-01-01

    Combining the advantages of high selectivity of amine groups, high capacity of microporous zeolite, and high transportation of mesoporous structures, amine modified micro/mesoporous composites may exhibit promising CO2 adsorption capability. In this study, a full-atomic mimetic amine modified micro/mesoporous composite of AM-5A-MCM-41 was constructed. CO2 adsorption and separation performance on AM-5A- MCM-41 composite were investigated by the grand canonical Monte Carlo (GCMC), in which a specific combining rule was used to describe the weak chemical interaction between CO2 molecule and amine group. The simulation results demonstrate that CO2 is preferentially adsorbed around amine groups, which is grafted at the surface of mesoporous channels; and the CO2 adsorption capacity and its isosteric heat are greatly improved on AM-5A-MCM-41, whereas those of N2 are almost kept unchanged. For the separation of mixed gas of CO2 and N2, both CO2 adsorption capacity and CO2/N2 selectivity are greatly improved, due to the enhanced interaction between CO2 molecules and amine groups. The chemisorption plays a significant role in the capture of CO2 at low pressures and high temperature, giving a selectivity as high as 87.0 at 573 K and 100 kPa. The overall results show that molecular simulations serve as a powerful implement to assist the design and development of new promising CO2 adsorbents, highlighting the importance of this approach.%构建了氨基修饰微孔/介孔复合材料AM-5A-MCM-41的全原子模型,采用巨正则Monte Carlo(GCMC)方法研究了它的CO2吸附分离性能,采用加权混合规则来描述氨基和CO2分子的弱化学作用。模拟结果表明,CO2分子优先吸附在复合材料介孔表面的氨基附近,CO2纯气体的吸附量和吸附热有了显著提高,而N2的吸附量和吸附热则基本不受影响。对于CO2和N2的混合气分离,由于复合材料对CO2的弱化学吸附作用,显著提高了CO2吸

  10. Electrochemical Behavior of Heteropoly Acid Anions Adsorbed in Electrodes Modified with Mesoporous Molecular Sieve Silica

    Institute of Scientific and Technical Information of China (English)

    Wenjiang LI; Zichen WANG; Changqing SUN; Muyu ZHAO; Youwei YAO; Aili CUI

    2001-01-01

    Heteropoly acid H4SiW12O48 (denoted as SiW12) was assembled with the mesoporous materials MCM-41 modified with 3-aminopropyltriethoxysilane (APTES) (denote MCM-41(m)). The electrochemical behavior of SiW12/MCM-41(m) complexes-based electrode indicated SiW12 anion was adsorbed by MCM-41(m). In MCM-41(m) electrode, large voltammetric waves, showing that the electrostatic bound ions adsorbed in MCM-41(m) were electrochemically active. The potential application as amperometric sensors for nitrite is anticipated.

  11. Synthesis of vanillin 1,2-propylene glycol acetal catalyzed by mesopore materials MCM-41 supported phosphotungstic acid hydrate%介孔分子筛 MCM-41负载磷钨酸催化合成香兰素1,2-丙二醇缩醛

    Institute of Scientific and Technical Information of China (English)

    王虎; 徐玲; 董哲; 于海云; 段莉梅; 刘宗瑞

    2012-01-01

    以香兰素和1,2-丙二醇为原料,以介孔分子筛MCM-41负载磷钨酸为催化剂,环己烷为带水剂,合成了香兰素1,2-丙二醇缩醛.考察了醛醇物质的量比、反应时间、带水剂用量、催化剂用量及负载量对产率的影响.实验表明,介孔分子筛MCM-41负载磷钨酸是合成香兰素1,2-丙二醇缩醛的理想催化剂,较优反应条件为:n(香兰素):n(1,2-丙二醇)=1:2.4,负载量为50%,催化剂用量为反应物总质量的2.0%,带水剂环己烷15 mL,回流反应2.0h,香兰素1,2-丙二醇缩醛的收率达92%以上.%Vanillin 1, 2-propylene glycol acetal was synthesized using 1, 2-propylene glycol and vanillin as starting materials, mesopore materials MCM-41 supported phosphotungstic acid hydrate as catalyst and cyclohexane as water stripping agent. Effects of factors on yield of product, such as molar ratio of the reactant, reaction time, the amount of water stripping agent and catalyst dosage and supported contents, were investigated. Experimental results showed that the preferential conditions are:the molar ratio of vanillin to 1, 2-propylene glycol is 1 ! 2.4; supported contents is 50%, the dosage of catalyst is 2. 0% of the total weight of the reactants; the amount of cyclohexane as water stripping agent is 15 mL; the reaction time is 2. 0 h. Under these conditions, the yield can achieve 92%.

  12. Influence of MCM-41 particle on mechanical and morphological behavior of polypropylene

    Energy Technology Data Exchange (ETDEWEB)

    Wang Na [Education Department of LiaoNing Province, Key Laboratory of Applied Technology of Polymer Materials, Shenyang Institute of Chemical Technology, Shenyang 110142 (China); Key Laboratory of Superlight Materials and Surface Technology, Harbin Engineering University, Ministry of Education, Nantong ST 145, Harbin 150001 (China)], E-mail: iamwangna@sina.com; Shao Yawei [Key Laboratory of Superlight Materials and Surface Technology, Harbin Engineering University, Ministry of Education, Nantong ST 145, Harbin 150001 (China); Shi Zhaoxin; Zhang Jing; Li Hongwei [Education Department of LiaoNing Province, Key Laboratory of Applied Technology of Polymer Materials, Shenyang Institute of Chemical Technology, Shenyang 110142 (China)

    2008-12-15

    This study investigates the effects of different types of nanoparticles and amount of nanoparticles on morphology and mechanical performance of polypropylene (PP) composites. Three different types of nanoparticles, namely mesoporous MCM-41 (without template), mesoporous MCM-41 (with template), and mesoporous MCM-41, whose pore channels were filled with different flexible polymer inside the pore channels with the aid of supercritical CO{sub 2} are considered. PP composites containing (0.5-5 wt.%) mesoporous MCM-41 were prepared by compounding. The tensile properties of the composites determined as a function of the filler loading and the different types of nanoparticles are found to vary with the different interface between different fillers and the matrix. The results of tensile tests showed that different flexible polymer filled mesoporous MCM-41 nanoparticles could simultaneously provide PP with strengthening and toughening effects at rather low filler content (0.5 wt.%). Scanning electron microscopy studies revealed a good dispersion of the MCM-41-S-PMMA and MCM-41-S-PS particles in the PP matrix and the enhancement of the interface between PP and MCM-41 are obtained.

  13. Mesoporous Silica Nanoparticles with Co-Condensed Gadolinium Chelates for Multimodal Imaging

    OpenAIRE

    Wenbin Lin; Joseph Della Rocca; Kathryn M. L. Taylor-Pashow

    2011-01-01

    Several mesoporous silica nanoparticle (MSN) contrast agents have been synthesized using a co-condensation method to incorporate two different Gd3+ complexes at very high loadings (15.5–28.8 wt %). These MSN contrast agents, with an MCM-41 type pore structure, were characterized using a variety of methods including SEM and TEM, nitrogen adsorption measurements, thermogravimetric analysis (TGA), direct current plasma (DCP) spectroscopy, and powder X-ray diffraction (PXRD). The magnetic resonan...

  14. New method for the immobilization of nitroxyl radical on mesoporous silica

    OpenAIRE

    Castanheiro, JE; Machado, A.; Casimiro, M; Ferreira, L; A. Ramos; Vital, J; Fonseca, I.

    2015-01-01

    This work reports the covalent attachment of 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (4- hydroxy-TEMPO) on the mesoporous silicas MCM-41 and SBA-15, by using ,4-diisocyanatobutane as a binder. The catalysts were characterized by nitrogen adsorption/desorption, XRD, TEM, TGA, DSC and FTIR spectroscopy. Catalytic tests were performed on the liquid phase oxidation of benzyl alcohol and the secondary alcohol isoborneol by using tert-butyl hydroperoxide as oxidant. The catalysts showed g...

  15. Synthesis of Highly ordered Large Size Mesoporous Silica and Effect of Stabilization as Enzyme Supports in Organic Solvent

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    FSM-16, MCM-41 and SBA-15 types of hexagonal mesoporous silica with a highly ordered 2-dimensional structure were synthesized by using different silicon sources and surfactants. In the 2-dimensional silicate framework, pore size can be uniformly controlled by the combined use of the surfactants having different alkyl chain lengths and the swelling agents(triisopropyl benzene). The pore-diameter of FSM-16 and MCM-41 can be expanded to be 10 nm, SBA-15 to be 15 nm. The crystal regularity was decreased with the increase of the porediameter. In FSM-16 derived from kanemite (silicon source) and MCM-41 from water glass, their anionic characteristics on the pore-wall may be stronger than those of SBA-15 derived from oligomeric tetramethoxysilane(TMOS). We have successfully used FSM-16 and MCM-41 to immobilize the enzyme having cationic residues below isoelectric point. The level of adsorption of enzymes in FSM-16 and MCM-41 was relatively high, but was low in SBA-15 support. The mechanism of enzyme to be adsorbed in mesoporous silica was suggested to be the ionic interactions. In aqueous solutions, horseradish peroxidase(HTP) was immobilized in FSM-16 with 8. 9 nm mesopores and the highest loading amount (183 mg/mg FSM) was obtained, but for the FSM-16 of pore diameter 30 nm only an amount of 28 mg/mg FSM was obtained. The catalytic activity in the organic solvent was high when HRP was immobilized in FSM-16 and MCM-41, but it was low in case of SBA-15.

  16. Formation of monodisperse mesoporous silica microparticles via spray-drying.

    Science.gov (United States)

    Waldron, Kathryn; Wu, Winston Duo; Wu, Zhangxiong; Liu, Wenjie; Selomulya, Cordelia; Zhao, Dongyuan; Chen, Xiao Dong

    2014-03-15

    In this work, a protocol to synthesize monodisperse mesoporous silica microparticles via a unique microfluidic jet spray-drying route is reported for the first time. The microparticles demonstrated highly ordered hexagonal mesostructures with surface areas ranging from ~900 up to 1500 m(2)/g and pore volumes from ~0.6 to 0.8 cm(3)/g. The particle size could be easily controlled from ~50 to 100 μm from the same diameter nozzle via changing the initial solute content, or changing the drying temperature. The ratio of the surfactant (CTAB) and silica (TEOS), and the amount of water in the precursor were found to affect the degree of ordering of mesopores by promoting either the self-assembly of the surfactant-silica micelles or the condensation of the silica as two competing processes in evaporation induced self-assembly. The drying rate and the curvature of particles also affected the self-assembly of the mesostructure. The particle mesostructure is not influenced by the inlet drying temperature in the range of 92-160 °C, with even a relatively low temperature of 92 °C producing highly ordered mesoporous microparticles. The spray-drying derived mesoporous silica microparticles, while of larger sizes and more rapidly synthesized, showed a comparable performance with the conventional mesoporous silica MCM-41 in controlled release of a dye, Rhodamine B, indicating that these spray dried microparticles could be used for the immobilisation and controlled release of small molecules.

  17. Preparation of Organic-Inorganic Hybrid Materials Based on MCM-41 and Its Applications

    Directory of Open Access Journals (Sweden)

    Sana M. Alahmadi

    2013-01-01

    Full Text Available This work reports the covalent attachment of three different calix[4]arenes (calix[4]arene (C4, p-sulfonatocalix[4]arene (C4S, and p-tert-butyl-calix[4]arene (PC4 to MCM-41, using a three-step modification process. 3-Chloropropyltrimethoxysilane (ClPTS was first attached to the mesoporous silica surface and subsequently converted to amides via the reaction with toluene diisocyanate (TDI. Finally, calix[4]arene derivatives attached to the isocyanate ending remained available on toluene di-iso-cyanate. Changes in the surface properties of the mesoporous silica caused by the chemical modification were monitored using the Fourier transform infrared spectroscopy (FTIR, thermal analysis (TGA, and elemental analysis. The FTIR spectra and TGA analysis verify that the calix[4]arene derivatives are covalently attached to the mesoporous silica. The preservation of the MCM-41 channel system was checked by the X-ray diffraction and nitrogen adsorption analysis. These materials were then used to evaluate the sorption properties of some organotins compounds (Tributyltin (TBT, Triphenyltin (TPT, and Dibutyltin (DBT.

  18. Amino-functionalized mesoporous silica modified glassy carbon electrode for ultra-trace copper(II) determination

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Xingxin [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, Jiangsu, 215123 (China); Qiu, Fagui [Department of Quartermaster Engineering, Jilin University, No. 5333, Xi' an Road, Changchun 130062 (China); Zhou, Xuan [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, Jiangsu, 215123 (China); Long, Yumei, E-mail: yumeilong@suda.edu.cn [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, Jiangsu, 215123 (China); The Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou (China); Li, Weifeng, E-mail: liweifeng@suda.edu.cn [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, Jiangsu, 215123 (China); Tu, Yifeng [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, Jiangsu, 215123 (China)

    2014-10-27

    NH{sub 2}-MCM-41 modified glassy carbon electrode was prepared and it exhibited enhanced anodic stripping response toward Cu (II), which could result from the large surface area of MCM-41 and the good chelating ability of amine-group. The as-constructed electrochemical sensor showed excellent analytical properties in the determination of Cu{sup 2+} and was successfully used for real sample assays. - Highlights: • We report a facile method to selectively detect Cu{sup 2+} based on NH{sub 2}-MCM-41 as sensing platform. • NH{sub 2}-MCM-41 has good affinity toward Cu{sup 2+}. • Detection limit of 0.9 ng L{sup −1} and linear concentration range of 5–1000 ng L{sup −1} are achieved. • The method is successfully applied to detect Cu{sup 2+} in real samples. - Abstract: This paper described a facile and direct electrochemical method for the determination of ultra-trace Cu{sup 2+} by employing amino-functionalized mesoporous silica (NH{sub 2}-MCM-41) as enhanced sensing platform. NH{sub 2}-MCM-41 was prepared by using a post-grafting process and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and fourier transform infrared (FTIR) spectroscopy. NH{sub 2}-MCM-41 modified glassy carbon (GC) electrode showed higher sensitivity for anodic stripping voltammetric (ASV) detection of Cu{sup 2+} than that of MCM-41 modified one. The high sensitivity was attributed to synergistic effect between MCM-41 and amino-group, in which the high surface area and special mesoporous morphology of MCM-41 can cause strong physical absorption, and amino-groups are able to chelate copper ions. Some important parameters influencing the sensor response were optimized. Under optimum experimental conditions the sensor linearly responded to Cu{sup 2+} concentration in the range from 5 to 1000 ng L{sup −1} with a detection limit of 0.9 ng L{sup −1} (S/N = 3). Moreover, the sensor possessed good stability and electrode renewability. In the end, the proposed

  19. Preparation of Organic-Inorganic Hybrid Materials Based on MCM-41 and Its Applications

    OpenAIRE

    Sana M. Alahmadi; Sharifah Mohamad; Mohd Jamil Maah

    2013-01-01

    This work reports the covalent attachment of three different calix[4]arenes (calix[4]arene (C4), p-sulfonatocalix[4]arene (C4S), and p-tert-butyl-calix[4]arene (PC4)) to MCM-41, using a three-step modification process. 3-Chloropropyltrimethoxysilane (ClPTS) was first attached to the mesoporous silica surface and subsequently converted to amides via the reaction with toluene diisocyanate (TDI). Finally, calix[4]arene derivatives attached to the isocyanate ending remained available on toluene d...

  20. Adsorption Of Water And Benzene Vapour In Mesoporous Materials

    Directory of Open Access Journals (Sweden)

    Paulina Taba

    2008-11-01

    Full Text Available Mesoporous materials have attracted the attention of many researchers due to the potential applications promised by the materials. This article discusses adsorption of water and benzene vapour in mesoporous materials (mesoporous silica: MCM-41, MCM-48 and their modification. MCM-41 and MCM-48 were synthesized hydrothermally at 100 oC using cethyltrimethylammonium chloride or dodecyltrimethylammonium bromide for MCM-41 (C16 or MCM-41 (C12 respectively and a mixture of cethyltrimethylammonium bromide and Triton X-100 for MCM-48 as templates. Their modifications were conducted by silylation of MCM-41 (C16 and MCM-48 with trimethylchloro silane (MCM16-TMCS and MCM48-TMCS and t-butyldimethylchloro silane (MCM16-TBDMCS and MCM48-TBDMCS. Results showed that MCM-41 and MCM-48 materials had hydrophobic features which were shown in the small amount of water adsorption at low P/P0. The hydrophobicity of samples used in this study decrease in the sequence: MCM-41 (C16 > MCM-48 > MCM-41 (C12. The hydrophobicity increased when MCM-41 and MCM-48 were silylated with TMCS or TBDMCS. All unsilylated MCM materials show higher affinity to benzene at low P/P0 than the silylated samples. The results of water and benzene adsorption showed that silylated samples are promising candidates as selective adsorbents for organic compounds.

  1. Synthesis of Highly Ordered Large Size Mesoporous Silica and Effect of Stabilization as Enzyme Supports in Organic Solvent

    Institute of Scientific and Technical Information of China (English)

    B.Li; S.Inagaki; C.Miyazaki; H.Takahashi

    2000-01-01

    The FSM-16, MCM-41 and SBA-15 type hexagonal mesoporous silica materials having a highly arrange in order of the 2-dimensional structure were synthesized by using different silicon sources and surfactants. In the 2-dimensional silicate framework, pore size can be uniformly controlled by the combined use of the surfactants having different alkyl chains length and swelling agents (triisopropyl benzene). Pore-diameter of FSM-16 and MCM-41 can be expanded to 100 A, SBA-15 is 150 A. Crystal regularity decreased with increasing the pore-diameter in the FSM-16 derived from Kanemite (silicon source) and MCM-41 from water glass, its anionic char-acteristics on the pore wall may be higher than SBA-15 derived from oligomeric tetramethoxysilane (TMOS) is also reported. We have successfully used FSM-16 and MCM-41 as immobilizing agents of enzyme having cationic residues under isoelectric point. The level of adsorption of enzymes in the FSM-16 and MCM-41 was relatively high, but was low in the SBA-15 support. The mechanism of enzyme adsorption in mesopore was suggested to be the ionic interactions. In aqueous solutions, horseradish peroxidase (HRP) immobilized in FSM-16 containing 89A mesopore showed the highest loaded amounts(183mg/mg FSM),then a FSM-16 of pore-diameter 30 A only loaded a litter amounts (28mg/mg FSM) on the outside surface. The catalytic activity in organic solvent is high when HRP was immobilized in FSM-16 and MCM-41, but is low in case of SBA- 15.

  2. Butanol Dehydration over V2O5-TiO2/MCM-41 Catalysts Prepared via Liquid Phase Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Jong-Ki Jeon

    2013-04-01

    Full Text Available MCM-41 was used as a support and, by using atomic layer deposition (ALD in the liquid phase, a catalyst was prepared by consecutively loading titanium oxide and vanadium oxide to the support. This research analyzes the effect of the loading amount of vanadium oxide on the acidic characteristics and catalytic performance in the dehydration of butanol. The physical and chemical characteristics of the TiO2-V2O5/MCM-41 catalysts were analyzed using XRF, BET, NH3-TPD, XRD, Py-IR, and XPS. The dehydration reaction of butanol was performed in a fixed bed reactor. For the samples with vanadium oxide loaded to TiO2/MCM-41 sample using the liquid phase ALD method, it was possible to increase the loading amount until the amount of vanadium oxide reached 12.1 wt %. It was confirmed that the structural properties of the mesoporous silica were retained well after titanium oxide and vanadium loading. The NH3-TPD and Py-IR results indicated that weak acid sites were produced over the TiO2/MCM-41 samples, which is attributed to the generation of Lewis acid sites. The highest activity of the V2O5(12.1-TiO2/MCM-41 catalyst in 2-butanol dehydration is ascribed to it having the highest number of Lewis acid sites, as well as the highest vanadium dispersion.

  3. Evaluation of Optimal Pore Size of (3-Aminopropyltriethoxysilane Grafted MCM-41 for Improved CO2 Adsorption

    Directory of Open Access Journals (Sweden)

    Zhilin Liu

    2015-01-01

    Full Text Available An array of new MCM-41 with substantially larger average pore diameters was synthesized through adding 1,3,5-trimethylbenzene (TMB as the swelling agent to explore the effect of pore size on final adsorbent properties. The pore expanded MCM-41 was also grafted with (3-Aminopropyltriethoxysilane (APTES to determine the optimal pore size for CO2 adsorption. The pore-expanded mesoporous MCM-41s showed relatively less structural regularity but significant increments of pore diameter (4.64 to 7.50 nm; the fraction of mesopore volume also illustrated an increase. The adsorption heat values were correlated with the order of the adsorption capacities for pore expanded MCM-41s. After amine functionalization, the adsorption capacities and heat values showed a significant increase. APTES-grafted pore-expanded MCM-41s depicted a high potential for CO2 capture regardless of the major drawback of the high energy required for regeneration.

  4. Analysis of {sup 2}H NMR spectra of water molecules on the surface of nano-silica material MCM-41: Deconvolution of the signal into a Lorentzian and a powder pattern line shapes

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, J., E-mail: jamal.hassan@kustar.ac.ae [Applied Mathematics and Sciences, KUSTAR, UAE and Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, N2L 3G1 (Canada)

    2012-01-01

    Water {sup 2}H NMR signal on the surface of nano-silica material MCM-41 consists of two overlapping resonances. The {sup 2}H water spectrum shows a superposition of a Lorentzian line shape and the familiar NMR powder pattern line shape, indicating the existence of two spin components. Exchange occurs between these two groups. Decomposition of the two signals is a crucial starting point to study the exchange process. In this article we have determined these spin component populations along with other important parameters for the {sup 2}H water NMR signal over a temperature range between 223 K and 343 K.

  5. Removal of Copper-phthalocyanine from Aqueous Solution by Cationically Templated MCM-41 and MCM-48 Nanoporous Adsorbents

    Institute of Scientific and Technical Information of China (English)

    ANBIA Mansoor; MOHAMMADI Kaveh

    2008-01-01

    The effect of cationic template on the adsorption of copper-phthalocyanine-3,4',4",4'"-tetrasulfonic acid tetra-sodium salt [Cu(tsPc)-4·4Na+] in MCM-41 and MCM-48 mesoporous materials was investigated,using cetyl-trimethylammonium bromide(CTAB)as the cationic template and tetraethyl-orthosilicate as the silica source for synthesis of mesoporous materials.The properties of synthesized samples were characterized with XRD-Iow angle and scanning electron microscopy.The as-synthesized mesoporous samples were used for the separation of Cu(tsPc)tion speed,contact time,composition of adsorbents(presence or absence of surfactants)and initial analyte concen-trations.Adsorption uptakes were rapid on the adsorbents reaching equilibrium in 1/5 h for MCM-48 and 2 h for MCM-41.The materials showed excellent adsorption capacity toward copper-phthalocyanine anion(300.5 mg/g of Cu(tsPc)-4 for as-MCM48 and 285.5 mg/g for as-MCM-41).The materials without surfactant did not show signifi-cant affinity for analyte.Dominant sorption mechanisms were interactions including electrostatic,hydrophobicity,hydrogen bonding and π-π interactions.

  6. Gadolinium(3+)-doped mesoporous silica nanoparticles as a potential magnetic resonance tracer for monitoring the migration of stem cells in vivo.

    Science.gov (United States)

    Shen, Yingying; Shao, Yuanzhi; He, Haoqiang; Tan, Yunpu; Tian, Xiumei; Xie, Fukang; Li, Li

    2013-01-01

    We investigated the tracking potential of a magnetic resonance imaging (MRI) probe made of gadolinium-doped mesoporous silica MCM-41 (Gd(2)O(3)@MCM-41) nanoparticles for transplanted bone mesenchymal stem cells (MSCs) and neural stem cells (NSCs) in vivo. The nanoparticles, synthesized using a one-step synthetic method, possess hexagonal mesoporous structures with appropriate assembly of nanoscale Gd(2)O(3) clusters. They show little cytotoxicity against proliferation and have a lower effect on the inherent differentiation potential of these labeled stem cells. The tracking of labeled NSCs in murine brains was dynamically determined with a clinical 3T MRI system for at least 14 days. The migration of labeled NSCs identified by MRI corresponded to the results of immunofluorescence imaging. Our study confirms that Gd(2)O(3)@MCM-41 particles can serve as an ideal vector for long-term MRI tracking of MSCs and NSCs in vivo.

  7. Mesoporous Silica Supported Au Nanoparticles with Controlled Size as Efficient Heterogeneous Catalyst for Aerobic Oxidation of Alcohols

    Directory of Open Access Journals (Sweden)

    Xuefeng Chu

    2015-01-01

    Full Text Available A series of Au catalysts with different sizes were synthesized and employed on amine group functionalized ordered mesoporous silica solid supports as catalyst for the aerobic oxidation of various alcohols. The mesoporous silica of MCM-41 supported Au nanoparticles (Au-1 exhibited the smallest particle size at ~1.8 nm with superior catalytic activities owing to the confinement effect of the mesoporous channels. Au-1 catalyst is also very stable and reusable under aerobic condition. Therefore, this presented work would obviously provide us a platform for synthesizing more size-controlled metal catalysts to improve the catalytic performances.

  8. Influence of synthesis conditions and mesoporous structures on the gold nanoparticles supported on mesoporous silica hosts

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Byunghwan [Korea Institute of Industrial Technology, ChonAn, Korea; Ma, Zhen [ORNL; Zhang, Zongtao [ORNL; Park, Chulhwan [Kwangwoon University; Dai, Sheng [ORNL

    2009-01-01

    Loading gold on mesoporous materials via different methods has been actively attempted in the literature, but the knowledge about the influences of synthesis details and different mesoporous structures on the size and thermal stability of gold nanoparticles supported on mesoporous hosts is still limited. In this study, Au/HMS, Au/MCM-41, Au/MCM-48, Au/SBA-15, and Au/SBA-16 samples were prepared by modifying a variety of mesoporous silicas by amine ligands followed by loading HAuCl4 and calcination. The influences of different amine ligands ((3-aminopropyl)triethoxysilane versus N-[3-(trimethoxysilyl)propyl]ethylenediamine), solvents (water versus ethanol), calcination temperatures (200 or 550 C), and mesoporous structures on the size of supported gold nanoparticles were systematically investigated employing nitrogen adsorption-desorption measurement, X-ray diffraction (XRD), diffuse reflectance UV-vis spectroscopy, and transmission electron microscopy (TEM). Interestingly, while big and irregular gold particles situate on MCM-48 with bicontinuous three-dimensional pore structure and relatively small pore size (2.4 nm) upon calcination at 550 C, homogeneous and small gold nanoparticles maintain inside SBA-15 with one-dimensional pore structure and relatively big pore size (6.8 nm). Apparently, the pore structure and pore size of mesoporous silica hosts play a key role in determining the size and thermal stability of the supported gold nanoparticles. Our results may provide some useful clues for the rational design of supported metal catalysts by choosing suitable mesoporous hosts.

  9. Fe/MCM-41 as a promising heterogeneous catalyst for ozonation of ρ-chlorobenzoic acid in aqueous solution

    Institute of Scientific and Technical Information of China (English)

    Rui Huan Huang; Jie Liu; Lai Sheng Li; Qiu Yun Zhang; Li Xuan Zeng; Ping Lu

    2011-01-01

    Mesoporous MCM-41 and Fe loaded MCM-41 (Fe/MCM-41), which were successfully prepared by a hydrothermal method and a dipping method respectively, were applied as heterogeneous catalysts for ozonation of p-chlorobenzoic acid (ρ-CBA) in aqueous solution. MCM-41 and Fe/MCM-41 were characterized by XRD, FT-IR and diffuse reflectance UV-vis (DR-UV-vis) techniques. The presence of either MCM-41 or Fe/MCM-41 improves p-CBA and total organic carbon (TOC) removal efficiency compared to ozonation alone. Under the experimental condition, TOC removal rate of Fe/MCM-41/O3 process is over 63.5% at 60 min oxidation time, 44.5% using MCM-41 as catalyst, only 37.7% with ozonation alone. The presence of /erf-butanol (TBA) in the Fe/MCM-41/ O3 process indicated that the oxidation mechanism of ρ-CBA occurs via OH in the liquid bulk. And Fe/MCM-41 is a promising catalyst.

  10. Mesoporous Nano-Silica Serves as the Degradation Inhibitor in Polymer Dielectrics

    Science.gov (United States)

    Yang, Yang; Hu, Jun; He, Jinliang

    2016-06-01

    A new generation of nano-additives for robust high performance nanodielectrics is proposed. It is demonstrated for the first time that mesoporous material could act as “degradation inhibitor” for polymer dielectrics to sequestrate the electrical degradation products then restrain the electrical aging process especially under high temperature conditions, which is superior to the existing additives of nanodielectrics except further increasing the dielectric strength. Polyethylenimine (PEI) loaded nano-scaled mesoporous silica MCM-41 (nano-MS) is doped into the dielectric matrix to prepare the PP/MCM-41-PEI nanocomposites. PEI provides the amines to capture the electrical degradation products while the MCM-41 brackets afford large adsorption surface, bring down the activating temperature of the absorbent then enhance the absorptive capacity. The electrical aging tests confirm the contribution of the mesoporous structure to electrical aging resistance and FT-IR analysis of the electrical degraded regions demonstrates the chemical absorption especially under high temperature conditions. Take the experimental data as examples, extending the aging durability and dielectric strength of polymer dielectrics by 5 times and 16%, respectively, can have substantial commercial significance in energy storage, power electronics and power transmission areas.

  11. Mesoporous Nano-Silica Serves as the Degradation Inhibitor in Polymer Dielectrics.

    Science.gov (United States)

    Yang, Yang; Hu, Jun; He, Jinliang

    2016-06-24

    A new generation of nano-additives for robust high performance nanodielectrics is proposed. It is demonstrated for the first time that mesoporous material could act as "degradation inhibitor" for polymer dielectrics to sequestrate the electrical degradation products then restrain the electrical aging process especially under high temperature conditions, which is superior to the existing additives of nanodielectrics except further increasing the dielectric strength. Polyethylenimine (PEI) loaded nano-scaled mesoporous silica MCM-41 (nano-MS) is doped into the dielectric matrix to prepare the PP/MCM-41-PEI nanocomposites. PEI provides the amines to capture the electrical degradation products while the MCM-41 brackets afford large adsorption surface, bring down the activating temperature of the absorbent then enhance the absorptive capacity. The electrical aging tests confirm the contribution of the mesoporous structure to electrical aging resistance and FT-IR analysis of the electrical degraded regions demonstrates the chemical absorption especially under high temperature conditions. Take the experimental data as examples, extending the aging durability and dielectric strength of polymer dielectrics by 5 times and 16%, respectively, can have substantial commercial significance in energy storage, power electronics and power transmission areas.

  12. Bimetallic Nanocatalysts in Mesoporous Silica for Hydrogen Production from Coal-Derived Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Kuila, Debasish [North Carolina Agricultural & Technical State Univ., Greensboro, NC (United States); Ilias, Shamsuddin [North Carolina Agricultural & Technical State Univ., Greensboro, NC (United States)

    2013-02-13

    In steam reforming reactions (SRRs) of alkanes and alcohols to produce H2, noble metals such as platinum (Pt) and palladium (Pd) are extensively used as catalyst. These metals are expensive; so, to reduce noble-metal loading, bi-metallic nanocatalysts containing non-noble metals in MCM-41 (Mobil Composition of Material No. 41, a mesoporous material) as a support material with high-surface area were synthesized using one-pot hydrothermal procedure with a surfactant such as cetyltrimethylammonium bromide (CTAB) as a template. Bi-metallic nanocatalysts of Pd-Ni and Pd-Co with varying metal loadings in MCM-41 were characterized by x-ray diffraction (XRD), N2 adsorption, and Transmission electron microscopy (TEM) techniques. The BET surface area of MCM-41 (~1000 m2/g) containing metal nanoparticles decreases with the increase in metal loading. The FTIR studies confirm strong interaction between Si-O-M (M = Pd, Ni, Co) units and successful inclusion of metal into the mesoporous silica matrix. The catalyst activities were examined in steam reforming of methanol (SRM) reactions to produce hydrogen. Reference tests using catalysts containing individual metals (Pd, Ni and Co) were also performed to investigate the effect of the bimetallic system on the catalytic behavior in the SRM reactions. The bimetallic system remarkably improves the hydrogen selectivity, methanol conversion and stability of the catalyst. The results are consistent with a synergistic behavior for the Pd-Ni-bimetallic system. The performance, durability and thermal stability of the Pd-Ni/MCM-41 and Pd-Co/MCM-41 suggest that these materials may be promising catalysts for hydrogen production from biofuels. A part of this work for synthesis and characterization of Pd-Ni-MCM-41 and its activity for SRM reactions has been published (“Development of Mesoporous Silica Encapsulated Pd-Ni Nanocatalyst for Hydrogen Production” in “Production and Purification of Ultraclean

  13. Functionalized mesoporous silica nanoparticles for oral delivery of budesonide

    Energy Technology Data Exchange (ETDEWEB)

    Yoncheva, K., E-mail: krassi.yoncheva@gmail.com [Department of Pharmaceutical Technology, Faculty of Pharmacy, Medical University of Sofia, 2 Dunav Str., 1000 Sofia (Bulgaria); Popova, M. [Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Sofia (Bulgaria); Szegedi, A.; Mihaly, J. [Institute of Nanochemistry and Catalysis, Chemical Research Center, Hungarian Academy of Sciences, Pusztaszeri út. 59-67, 1025 Budapest (Hungary); Tzankov, B.; Lambov, N.; Konstantinov, S.; Tzankova, V. [Department of Pharmaceutical Technology, Faculty of Pharmacy, Medical University of Sofia, 2 Dunav Str., 1000 Sofia (Bulgaria); Pessina, F.; Valoti, M. [Dipartimento di Scienze della Vita, Universita di Siena, via Aldo Moro 2, Siena (Italy)

    2014-03-15

    Non-functionalized and amino-functionalized mesoporous silica nanoparticle were loaded with anti-inflammatory drug budesonide and additionally post-coated with bioadhesive polymer (carbopol). TEM images showed spherical shape of the nanoparticles and slightly higher polydispersity after coating with carbopol. Nitrogen physisorption and thermogravimetic analysis revealed that more efficient loading and incorporation into the pores of nanoparticles was achieved with the amino-functionalized silica carrier. Infrared spectra indicated that the post-coating of these nanoparticles with carbopol led to the formation of bond between amino groups of the functionalized carrier and carboxyl groups of carbopol. The combination of amino-functionalization of the carrier with the post-coating of the nanoparticles sustained budesonide release. Further, an in vitro model of inflammatory bowel disease showed that the cytoprotective effect of budesonide loaded in the post-coated silica nanoparticles on damaged HT-29 cells was more pronounced compared to the cytoprotection obtained with pure budesonide. -- Graphical abstract: Silica mesoporous MCM-41 particles were amino-functionalized, loaded with budesonide and post-coated with bioadhesive polymer (carbopol) in order to achieve prolonged residence of anti-inflammatory drug in GIT. Highlights: • Higher drug loading in amino-functionalized mesoporous silica. • Amino-functionalization and post-coating of the nanoparticles sustained drug release. • Achievement of higher cytoprotective effect with drug loaded into the nanoparticles.

  14. Application of Phenyl Bonded Mesoporous Silica as A Novel Coating Layer of Solid-phase Microextraction for Determination of Benzo[a]pyrene in Water Samples

    Institute of Scientific and Technical Information of China (English)

    Xin Zhen DU; Ya Rong WANG; Qian MA; Xue Feng MAO; Jin Guo HOU

    2005-01-01

    Phenyl bonded mesoporous silica (C6H5-MCM-41) was applied as the fiber coating of solid-phase microextraction (SPME). The performance of the fiber coating was discussed coupling to HPLC. Applicability of mesoporous fiber coating was examined for the determination of benzo[a]pyrene (B[a]P) in water samples, The limit of detection (LOD) is 0.28μg.L-1. Good recovery and relative standard deviation (RSD) were obtained.

  15. Mesoporous Structure Control of Silica in Room-Temperature Synthesis under Basic Conditions

    Directory of Open Access Journals (Sweden)

    Jeong Wook Seo

    2015-01-01

    Full Text Available Various types of mesoporous silica, such as continuous cubic-phase MCM-48, hexagonal-phase MCM-41, and layer-phase spherical silica particles, have been synthesized at room temperature using cetyltrimethylammonium bromide as a surfactant, ethanol as a cosurfactant, tetraethyl orthosilicate as a silica precursor, and ammonia as a condensation agent. Special care must be taken both in the filtering of the resultant solid products and in the drying process. In the drying process, further condensation of the silica after filtering was induced. As the surfactant and cosurfactant concentrations in the reaction mixture increased and the NH3 concentration decreased, under given conditions, continuous cubic MCM-48 and layered silica became the dominant phases. A cooperative synthesis mechanism, in which both the surfactant and silica were involved in the formation of mesoporous structures, provided a good explanation of the experimental results.

  16. Utilization of rice husk ash as silica source for the synthesis of mesoporous silicas and their application to CO2 adsorption through TREN/TEPA grafting.

    Science.gov (United States)

    Bhagiyalakshmi, Margandan; Yun, Lee Ji; Anuradha, Ramani; Jang, Hyun Tae

    2010-03-15

    Mesoporous MCM-41, MCM-48 and SBA-15 were synthesized using Rice husk ash (RHA) as the silica source and their defective Si-OH sites were functionalized by 3-chloropropyltrimethoxysilane (CPTMS) which was subsequently grafted with amine compounds, Tris(2-aminoethyl)amine (TREN) and Tetraethylenepentamine (TEPA). X-ray powder diffraction (XRD) and BET results of the parent mesoporous silica suggested their closeness of structural properties to those obtained from conventional silica sources. CO(2) adsorption of branched amine TREN and straight chain amine TEPA at 25, 50 and 75 degrees C was obtained by Thermogravimetric Analyser (TGA) at atmospheric pressure. TREN grafted mesoporous silica showed 7% of CO(2) adsorption while TEPA grafted mesoporous silicas showed less CO(2) adsorption, which is due to the presence of isolated amine groups in TREN. TREN grafted mesoporous silicas were also observed to be selective towards CO(2), thermally stable and recyclable. The order of CO(2) adsorption with respect to amount of amine grafting was observed to be MCM-48/TREN>MCM-41/TREN>SBA-15/TREN.

  17. Adsorption of quinolone antibiotics in spherical mesoporous silica: Effects of the retained template and its alkyl chain length.

    Science.gov (United States)

    Liang, Zhijie; Zhaob, Zhiwei; Sun, Tianyi; Shi, Wenxin; Cui, Fuyi

    2016-03-15

    In this study, mesoporous silica (meso-silica) MCM-41 and those with the templates retained were synthesized and characterized. Adsorption capacities of the synthesized materials towards typical quinolone antibiotic pollutants, enrofloxacin and norfloxacin as representative, were investigated, and effects of the alkyl chain length of the templates on the adsorption capacity were evaluated. The results of this study indicated that the retained templates enhanced the adsorption capacities (Qmax) of the meso-silica MCM-41 toward hydrophobic enrofloxacin, but had an inhibitory effect on that towards hydrophilic norfloxacin, which were attributed to the hydrophobic inter-environment created by the long alkyl chains of the retained templates. Importantly, the adsorption capacity increased with the increase of the alkyl chain length of the retained templates. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Studies on the Polymerization of Styrene in the MCM-41 Phase%苯乙烯在MCM-41介孔材料中聚合的研究

    Institute of Scientific and Technical Information of China (English)

    屈玲; 佟大明; 吕志平; 萧墉壮; 窦涛

    2003-01-01

    The polymerization of styrene in the media of MCM-41 is carried out by means of host-guest polymerization of styrene in MCM-41 mesoporoas material with the aim to investigate the effects of interface and confinement of MCM-41 on host-guest interactions. Detailed physical properties of the mesoporous MCM-41 material containing polystyrene is characterized by XRD(X-ray diffraction), FT-IR(Fourier transform infrared), TGA(thermal gravimetric analysis), and nitrogen adsorption-desorption isotherms. We also find a great increase in the glass transition temperature of guest polystyrene influenced by the confined geometry of the host by differential scanning calorimetry (DSC).

  19. Synthesis of a new meso/microporous composite molecular sieve of MCM-41/mordenite

    Institute of Scientific and Technical Information of China (English)

    WANG Shan; DOU Tao; LI Yuping; ZHANG Ying; YAN Zichun; LI Xiaofeng

    2005-01-01

    An MCM-41/mordenite composite with twofold porous structure and stepwise-distributed acidity was prepared for the first time by using zeolite mordenite as the silica-alumina source. The composite molecular sieve has been investigated and compared with a mechanical mixture of mordenite and MCM-41 for their structure, acidity and catalytic activity by means of XRD, N2 adsorption and desorption, HRTEM, DTG, NH3-TPD and catalytic reaction. The characterization results show that the structure and property of the composite molecular sieve are quite different from those of the mechanical mixture, which might be ascribed to the incorporation of secondary building units characteristic of zeolite mordenite into the mesoporous walls of the composite which gives rise to the thicker mesoporous walls, the higher hydrothermal stability and more strong acid sites. Furthermore, the new strategy could be used as a new general method for the preparation of catalysts for the reaction system with multifold large molecules, and the results were well confirmed by the dealkylation of C10+ aromatic hydrocarbon.

  20. Molecular simulation of fluid adsorption in buckytubes and MCM-41

    Energy Technology Data Exchange (ETDEWEB)

    Maddox, M.W.; Gubbins, K.E. [Cornell Univ., Ithaca, NY (United States)

    1994-11-01

    We report canonical Monte Carlo (GCMC) molecular-simulation studies of argon and nitrogen in models of two novels adsorbents, buckytubes and MCM-41. Buckytubes are monodisperse carbon tubes with internal diameters of 1-5 nm and a regular pore structure. MCM-41 is one member of a new family of highly uniform mesoporous aluminosilicates produced by Mobil. The pore size of MM-41 can be accurately controlled within the range 1.5-1.0 nm. The adsorption of argon in a buckytube and the adsorption of nitrogen in two different MCM-41 pores are studied at 77 K. Both fluids are modeled as Lennard-Jones spheres, and an averaged fluid-wall potential, dependent only on the distance of the adsorbed molecule from the center of the tube or pore is used. Isotherms and isosteric heats are calculated. Layering transitions and a hysteresis loop are observed for the buckytube and good agreement is found between simulated and experimental isotherms for the MCM-41 systems.

  1. Immunoprecipitation of bisphenol A by antibody–mesoporous silica composites

    Directory of Open Access Journals (Sweden)

    Toru Orita

    2014-09-01

    Full Text Available Bisphenol A (BPA is of global concern because of its disruption of endocrine systems and ubiquity in aquatic environment. In this study, BPA antibody was successfully immobilised on novel mesoporous silica (MPS carriers that display unique properties such as high surface area, highly uniform pore distribution and high adsorption capacity. Mobil Crystalline Material MCM-41 (2.7 nm, Santa Barbara Amorphous SBA-15-1 (12.3 nm and SBA-15-2 (24.0 nm materials were used as supports for these antibodies. On these carriers, the BPA antibody immobilisation reached 40 μg mg−1. For each MPS, 15 ng of BPA antigen was adsorbed on 1 mg of MPS–antibody composite, which resulted in an antibody activity of 30%. The highest recovery rate of BPA antigen was observed for 80% acetonitrile in 10 mM phosphate buffer (pH 7. After six repeated runs, BPA antibodies immobilised on SBA-15-1 and SBA-15-2 retained about 30% of their initial activity. In contrast, these antibodies showed 13% lower residual activity on MCM-41 than on SBA-15-1 and SBA-15-2. This result indicated that entire antibody molecules were adsorbed inside SBA-15-1 and SBA-15-2 pores, stabilising their structural conformation.

  2. Modified silica-based heterogeneous catalysts for etherification of glycerol

    Energy Technology Data Exchange (ETDEWEB)

    Gholami, Zahra, E-mail: zahra.gholami@petronas.com.my [Centralized Analytical Laboratory, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia); Abdullah, Ahmad Zuhairi, E-mail: chzuhairi@usm.my; Gholami, Fatemeh, E-mail: fgholami59@gmail.com [School of Chemical Engineering, Universiti Sains Malaysia, Engineering Campus,14300 Nibong Tebal, Penang (Malaysia); Vakili, Mohammadtaghi, E-mail: farshid3601@gmail.com [School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang (Malaysia)

    2015-07-22

    The advent of mesoporous silicas such as MCM-41 has provided new opportunities for research into supported metal catalysis. The loading of metals into framework structures and particularly into the pores of porous molecular sieves, has long been of interest because of their potential catalytic activity. Stable heterogeneous mesoporous basic catalysts were synthesized by wet impregnation of MCM-41 with calcium nitrate and lanthanum nitrate. The surface and structural properties of the prepared catalysts were characterized using BET surface analysis, SEM and TEM. MCM-41 and modified MCM-41 were used in the solventless etherification of glycerol to produce diglycerol as the desired product. The reaction was performed at 250 °C for 8 h, and catalyst activity was evaluated. Catalytic etherification over the 20%Ca{sub 1.6}La{sub 0.6}/MCM-41 catalyst resulted in the highest glycerol conversion of 91% and diglycerol yield of 43%.

  3. Facile fabrication of an ultrasensitive sandwich-type electrochemical immunosensor for the quantitative detection of alpha fetoprotein using multifunctional mesoporous silica as platform and label for signal amplification.

    Science.gov (United States)

    Wang, Yulan; Li, Xiaojian; Cao, Wei; Li, Yueyun; Li, He; Du, Bin; Wei, Qin

    2014-11-01

    A novel and ultrasensitive sandwich-type electrochemical immunosensor was designed for the quantitative detection of alpha fetoprotein (AFP) using multifunctional mesoporous silica (MCM-41) as platform and label for signal amplification. MCM-41 has high specific surface area, high pore volume, large density of surface silanol groups (SiOH) and good biocompatibility. MCM-41 functionalized with 3-aminopropyltriethoxysilane (APTES), gold nanoparticles (Au NPs) and toluidine blue (TB) could enhance electrochemical signals. Moreover, primary antibodies (Ab1) and secondary antibodies (Ab2) could be effectively immobilized onto the multifunctional MCM-41 by the interaction between Au NPs and amino groups (-NH2) on antibodies. Using multifunctional MCM-41 as a platform and label could greatly simplify the fabrication process and result in a high sensitivity of the designed immunosensor. Under optimal conditions, the designed immunosensor exhibited a wide liner range from 10(-4) ng/mL to 10(3) ng/mL with a low detection limit of 0.05 pg/mL for AFP. The designed immunosensor showed acceptable selectivity, reproducibility and stability, which could provide potential applications in clinical monitoring of AFP.

  4. Aerobic oxidation of cyclohexene catalyzed by NiO/MCM-41 nanocomposites in the gas phase

    Indian Academy of Sciences (India)

    Amin Ebadi; Majid Mozaffari; Sanaz Shojaei

    2014-07-01

    The nanoparticles of NiO supported on mesoporous MCM-41 were synthesized and characterized with X-ray diffraction (XRD) and transmission electron microscopy (TEM). In this study, catalytic activities of the supported NiO nanoparticles for oxidation of cyclohexene to 2-cyclohexene-1-ol and 2-cyclohexene-1-one with air in the gas phase were considered. These nanoparticles of NiO supported on mesoporous MCM-41 were effective catalysts in a temperature range of 220-310°C at 1 atm of air. Under these reaction conditions, the activity of the catalysts decreases in the following order: 5 wt.% NiO/MCM-41 > 7.5 wt.% NiO/MCM-41 > 2.5 wt.% NiO/MCM-41. With 5 wt.% NiO supported on mesoporous MCM-41 and under our experimental conditions, the conversion percent of cyclohexene is 62.3% with 65.9% selectivity of 2-cyclohexene-1-ol + 2-cyclohexene-1-one and 12.2% cyclohexadiene at 280°C. To achieve higher conversion of cyclohexene and better selectivity towards 2-cyclohexene-1-ol + 2-cyclohexene-1-one, factors such as reaction temperature, loading amount of nickel oxide and space velocity were studied, and optimized conditions were investigated.

  5. Mesoporous silica/polyacrylamide composite: Preparation by UV-graft photopolymerization, characterization and use as Hg(II) adsorbent

    Science.gov (United States)

    Saad, Ali; Bakas, Idriss; Piquemal, Jean-Yves; Nowak, Sophie; Abderrabba, Manef; Chehimi, Mohamed M.

    2016-03-01

    MCM-41 ordered mesoporous silica was prepared, aminosilanized and grafted with polyacrylamide (PAAM) through in situ radical photopolymerization process. The resulting composite, denoted PAAM-NH2-MCM-41, the calcined and silanized reference MCM-41s were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and N2 physisorption at 77 K. These complementary techniques brought strong supporting evidence for the silanization process followed by PAAM grafting. The surface composition was found to be PAAM-rich as judged by XPS. The composite was then employed for the uptake of Hg(II) from aqueous solutions. Adsorption was monitored versus pH, time, and temperature. The maximum adsorption capacity at 25 °C and pH 5.2 was 177 mg g-1. Kinetically, the equilibrium was reached within 60 min for a 100 mg L-1 mercury solution. The adsorption of Hg(II) on PAAM-NH2-MCM-41 composites followed second order kinetics. Thermodynamic parameters suggested that the favorable adsorption process is exothermic in nature and the adsorption is ascribed to a decrease in the degree of freedom of adsorbed ions which results in the entropy change. This work conclusively shows that mesoporous silica-polymer hybrid metal ion adsorbents (with robust silica-polymer interface) can be prepared in a simple way by in situ radical photopolymerization in the presence of aminosilanized silica acting as a support and a macro-hydrogen donor simultaneously.

  6. Analysis on Band Gaps of MCM-41 Type of Materials

    Institute of Scientific and Technical Information of China (English)

    HAN Pei-de; LIANG Jian; XU Bing-she; LIU Xu-guang; PENG Lian-mao

    2004-01-01

    The concept and analysis method of photonic crystals and band gaps are introduced into one-dimensional(1D) ordered mesoporous materials. MCM-41 type of materials are treated theoretically as photonic crystals. The formation of band gaps is exhibited and confirmed by a calculation of transfer matrix technique. PBG was found around 9-42 nm in soft X-ray region. The photonic band-gap was predicted to be dependent on incident direction, pore size and lattice constant. The mesoporous materials with different pore sizes and different lattice constants have different band-gap widths.

  7. Adsorption of n-pentane on mesoporous silica and adsorbent deformation.

    Science.gov (United States)

    Gor, Gennady Yu; Paris, Oskar; Prass, Johannes; Russo, Patrícia A; Ribeiro Carrott, M Manuela L; Neimark, Alexander V

    2013-07-09

    Development of quantitative theory of adsorption-induced deformation is important, e.g., for enhanced coalbed methane recovery by CO2 injection. It is also promising for the interpretation of experimental measurements of elastic properties of porous solids. We study deformation of mesoporous silica by n-pentane adsorption. The shape of experimental strain isotherms for this system differs from the shape predicted by thermodynamic theory of adsorption-induced deformation. We show that this difference can be attributed to the difference of disjoining pressure isotherm, responsible for the solid-fluid interactions. We suggest the disjoining pressure isotherm suitable for n-pentane adsorption on silica and derive the parameters for this isotherm from experimental data of n-pentane adsorption on nonporous silica. We use this isotherm in the formalism of macroscopic theory of adsorption-induced deformation of mesoporous materials, thus extending this theory for the case of weak solid-fluid interactions. We employ the extended theory to calculate solvation pressure and strain isotherms for SBA-15 and MCM-41 silica and compare it with experimental data obtained from small-angle X-ray scattering. Theoretical predictions for MCM-41 are in good agreement with the experiment, but for SBA-15 they are only qualitative. This deviation suggests that the elastic modulus of SBA-15 may change during pore filling.

  8. Econazole nitrate-loaded MCM-41 for an antifungal topical powder formulation.

    Science.gov (United States)

    Ambrogi, Valeria; Perioli, Luana; Pagano, Cinzia; Marmottini, Fabio; Moretti, Massimo; Mizzi, Fabiola; Rossi, Carlo

    2010-11-01

    The aim of this article was to prepare a topical powder for the treatment of fungal infections, such as Candida intertrigo and tinea pedis. Thus, an econazole nitrate (ECO) formulation with improved drug dissolution and proper moisture adsorption was designed. ECO was melt with the mesoporous silicate MCM-41 (drug/MCM-41 1/3) and the resulting inclusion compound was characterized by X-ray powder diffraction (XRPD) and differential scanning calorimetry (DSC). The drug loading was confirmed by the decrease of specific surface area and pore volume between MCM-41 and the inclusion compound. Formulations containing the inclusion compound were prepared and submitted to in vitro dissolution test and in vitro antifungal activity. A remarkable dissolution rate improvement as well as a higher antifungal activity was observed for the inclusion compound if compared to a commercial product. Moisture sorption properties for MCM-41 and formulations were evaluated as well.

  9. Mesoporous silica nanoparticles for biomedical and catalytical applications

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xiaoxing [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    Mesoporous silica materials, discovered in 1992 by the Mobile Oil Corporation, have received considerable attention in the chemical industry due to their superior textual properties such as high surface area, large pore volume, tunable pore diameter, and narrow pore size distribution. Among those materials, MCM-41, referred to Mobile Composition of Matter NO. 41, contains honeycomb liked porous structure that is the most common mesoporous molecular sieve studied. Applications of MCM-41 type mesoporous silica material in biomedical field as well as catalytical field have been developed and discussed in this thesis. The unique features of mesoporous silica nanoparticles were utilized for the design of delivery system for multiple biomolecules as described in chapter 2. We loaded luciferin into the hexagonal channels of MSN and capped the pore ends with gold nanoparticles to prevent premature release. Luciferase was adsorbed onto the outer surface of the MSN. Both the MSN and the gold nanoparticles were protected by poly-ethylene glycol to minimize nonspecific interaction of luciferase and keep it from denaturating. Controlled release of luciferin was triggered within the cells and the enzymatic reaction was detected by a luminometer. Further developments by varying enzyme/substrate pairs may provide opportunities to control cell behavior and manipulate intracellular reactions. MSN was also served as a noble metal catalyst support due to its large surface area and its stability with active metals. We prepared MSN with pore diameter of 10 nm (LP10-MSN) which can facilitate mass transfer. And we successfully synthesized an organo silane, 2,2'-Bipyridine-amide-triethoxylsilane (Bpy-amide-TES). Then we were able to functionalize LP10-MSN with bipyridinyl group by both post-grafting method and co-condensation method. Future research of this material would be platinum complexation. This Pt (II) complex catalyst has been reported for a C-H bond activation reaction as an

  10. MCM-41-SO3H as a Highly Efficient Sulfonic Acid Nanoreactor for the Rapid and Green Synthesis of Some Novel Highly Substituted Imidazoles under Solvent-Free Condition

    Institute of Scientific and Technical Information of China (English)

    Mahdavinia, Gholam Hossein; Amani, Ali Mohammad; Sepehrian, Hamid

    2012-01-01

    Nanosized MCM-41-SO3H based on ordered mesoporous silica material with a covalent sulfonic acid group was synthesized and used as acid catalyst for the new, simple, convenient and green synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetra-substituted imidazoles. Also some of synthesis products are new. Echo-friendly protocol, short reaction times, easy and quick isolation of the products and excellent yields are the main advantages of this procedure.

  11. Effect of Hydrophobic Carbon Chain Length on the Crystal Structure of MCM-41%模板剂碳链长度MCM-41晶体结构的影响

    Institute of Scientific and Technical Information of China (English)

    张光旭; 陶玲; 张高勇

    2008-01-01

    The mesoporous molecular sieve (MCM)-41 using ionic liquid as template has been prepared.The typical template of ionic liquid Was[C16mim]X.In thiS article,the use of 1-alkyl-3-methylimidazolium([Cnmim]Br,where n=12.14,16,18,20)salts as templates in the synthesis of MCM-41 is reported.The results showed that the synthesized MCM-41 had uniforlTl pore diameter,high surface area and stable framework.The largest surface area of MCM-41 Was the one prepared with [C14mim]Br as template.When using[C18min]Br as template,the narrowest pore distribution sample Was obtained and the effect of surface tension of template solution to MCM-41 Was first discussed.

  12. Improvement of the Kruk-Jaroniec-Sayari method for pore size analysis of ordered silicas with cylindrical mesopores.

    Science.gov (United States)

    Jaroniec, Mietek; Solovyov, Leonid A

    2006-08-01

    In this work, the X-ray diffraction structure modeling was employed for analysis of hexagonally ordered large-pore silicas, SBA-15, to determine their pore width independently of adsorption measurements. Nitrogen adsorption isotherms were used to evaluate the relative pressure of capillary condensation in cylindrical mesopores of these materials. This approach allowed us to extend the original Kruk-Jaroniec-Sayari (KJS) relation (Langmuir 1997, 13, 6267) between the pore width and capillary condensation pressure up to 10 nm instead of previously established range from 2 to 6.5 nm for a series of MCM-41 and to improve the KJS pore size analysis of large pore silicas.

  13. Liquid phase oligomerization of 1-hexene over different mesoporous aluminosilicates (Al-MTS, Al-MCM-41 and Al-SBA-15) and micrometer/nanometer HZSM-5 zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Van Grieken, R.; Escola, J.M.; Moreno, J.; Rodriguez, R. [Department of Chemical and Environmental Technology, ESCET, Rey Juan Carlos University, c/Tulipan s/n, 28933 Mostoles (Spain)

    2006-05-24

    The liquid phase oligomerization of 1-hexene at 200{sup o}C and 5MPa using n-octane as solvent towards hydrocarbon mixtures useful as fuels (gasoline and diesel) was tested over several acid catalysts: micrometer ({mu}-) and nanocrystalline (n-) HZSM-5 zeolites, mesoporous hydrothermal Al-MCM-41, and sol-gel Al-MTS and Al-SBA-15 catalysts. The conversion was always above 75% except for {mu}-HZSM-5 (just 8.4%) due to its low external surface area (5m{sup 2}g{sup -1}) and the fast deactivation in the reaction conditions used in this work. The total selectivity towards oligomers was around 95% and the highest share of C{sub 9}-C{sub 12} dimers (47%), C{sub 13}-C{sub 18} trimers (33%) and heavy C{sub 19}-C{sub 30} compounds (33%) were yielded over Al-SBA-15, n-HZSM-5 and sol-gel Al-MTS, respectively. The remarkable oligomerization performance of n-HZSM-5 was ascribed to its high external surface area (102m{sup 2}g{sup -1}) and for the mesoporous catalysts, to their large BET surface area. In particular, Al-MTS showed the best behaviour due to its higher BET surface area and slightly weaker acidity. All the catalysts exhibited steady-state performance with time on stream (TOS) without drastic changes in activity up to 180min. Simulated distillation analyses proved that the lighter fuel (gasoline+diesel) was obtained over Al-MTS (final distillation temperature=463{sup o}C; C{sub 26}-C{sub 32}=8.4%) while the heaviest was obtained over n-HZSM-5 zeolite (final distillation temperature=524{sup o}C; C{sub 28}-C{sub 40}=11.7%), probably related to its stronger acidity and microporous nature. The similar nature of hydrocarbons compounds retained over the catalysts after reaction proved by FTIR spectroscopy together with the thermogravimetric analyses results, showed the stronger adsorption of the reaction products promoted by the microporous nature of zeolites. (author)

  14. Synthesis and characterization of MCM-41-supported nano zirconia catalysts

    Directory of Open Access Journals (Sweden)

    Mohamed S. Abdel Salam

    2015-03-01

    Full Text Available Series of MCM-41 supported sulfated Zirconia (SZ catalysts with different loadings (2.5–7.5% wt. were prepared using direct impregnation method. The acquired solid catalysts were characterized structurally and chemically using X-RD, HRTEM, BET, FT-IR, Raman spectroscopy and TPD analysis. The acidity of the solid catalysts was investigated through cumene cracking and isopropanol dehydration at different temperatures. As the SZ loading increases, the surface acidity of the mesoporous catalysts was enhanced, this was reflected by the higher catalytic activity toward cumene cracking and isopropanol dehydration.

  15. Catalytic performance of hierarchical H-ZSM-5/MCM-41 for methanol dehydration to dimethyl ether

    Institute of Scientific and Technical Information of China (English)

    Yu; Sang; Hongxiao; Liu; Shichao; He; Hansheng; Li; Qingze; Jiao; Qin; Wu; Kening; Sun

    2013-01-01

    Micro-mesoporous composite molecular sieves H-ZSM-5/MCM-41 were prepared by the hydrothermal technique with alkali-treated H-ZSM-5zeolite as the source and characterized by scanning electron microscopy,transmission electron microscopy,energy dispersive spectroscopy,X-ray diffraction,N2 adsorption-desorption measurement and NH3 temperature-programmed desorption.The catalytic performances for the methanol dehydration to dimethyl ether over H-ZSM-5/MCM-41 were evaluated.Among these catalysts,H-ZSM-5/MCM-41 prepared with NaOH dosage (nNa/nSi) varying from 0.4 to 0.47 presented excellent catalytic activity with more than 80%methanol conversion and 100%dimethyl ether selectivity in a wide temperature range of 170—300℃,and H-ZSM-5/MCM-41 prepared with nNa/nSi=0.47 showed constant methanol conversion of about 88.7%,100% dimethyl ether selectivity and excellent lifetime at 220℃.The excellent catalytic performances were due to the highly active and uniform acidic sites and the hierarchical porosity in the micro-mesoporous composite molecular sieves.The catalytic mechanism of H-ZSM-5/MCM-41 for the methanol dehydration to dimethyl ether process was also discussed.

  16. Biological Applications and Transmission Electron Microscopy Investigations of Mesoporous Silica Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Trewyn, Brian G. [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    The research presented and discussed within involves the development of novel biological applications of mesoporous silica nanoparticles (MSN) and an investigation of mesoporous material by transmission electron microscopy (TEM). Mesoporous silica nanoparticles organically functionalized shown to undergo endocytosis in cancer cells and drug release from the pores was controlled intracellularly and intercellularly. Transmission electron microscopy investigations demonstrated the variety of morphologies produced in this field of mesoporous silica nanomaterial synthesis. A series of room-temperature ionic liquid (RTIL) containing mesoporous silica nanoparticle (MSN) materials with various particle morphologies, including spheres, ellipsoids, rods, and tubes, were synthesized. By changing the RTIL template, the pore morphology was tuned from the MCM-41 type of hexagonal mesopores to rotational moire type of helical channels, and to wormhole-like porous structures. These materials were used as controlled release delivery nanodevices to deliver antibacterial ionic liquids against Escherichia coli K12. The involvement of a specific organosiloxane function group, covalently attached to the exterior of fluorescein doped mesoporous silica nanoparticles (FITC-MSN), on the degree and kinetics of endocytosis in cancer and plant cells was investigated. The kinetics of endocystosis of TEG coated FITC-MSN is significantly quicker than FITC-MSN as determined by flow cytometry experiments. The fluorescence confocal microscopy investigation showed the endocytosis of TEG coated-FITC MSN triethylene glycol grafted fluorescein doped MSN (TEG coated-FITC MSN) into both KeLa cells and Tobacco root protoplasts. Once the synthesis of a controlled-release delivery system based on MCM-41-type mesoporous silica nanorods capped by disulfide bonds with superparamagnetic iron oxide nanoparticles was completed. The material was characterized by general methods and the dosage and kinetics of the

  17. Evaluation of Optimal Pore Size of (3-Aminopropyl)triethoxysilane Grafted MCM-41 for Improved CO2 Adsorption

    OpenAIRE

    2015-01-01

    An array of new MCM-41 with substantially larger average pore diameters was synthesized through adding 1,3,5-trimethylbenzene (TMB) as the swelling agent to explore the effect of pore size on final adsorbent properties. The pore expanded MCM-41 was also grafted with (3-Aminopropyl)triethoxysilane (APTES) to determine the optimal pore size for CO2 adsorption. The pore-expanded mesoporous MCM-41s showed relatively less structural regularity but significant increments of pore diameter (4.64 to 7...

  18. Highly Loaded Fe-MCM-41 Materials: Synthesis and Reducibility Studies

    Directory of Open Access Journals (Sweden)

    Malose P. Mokhonoana

    2009-12-01

    Full Text Available Fe-MCM-41 materials were prepared by different methods. The Fe was both incorporated into the structure and formed crystallites attached to the silica. High Fe content MCM-41 (~16 wt% with retention of mesoporosity and long-range order was achieved by a range of new synthetic methodologies: (i by delaying the addition of Fe3+(aq to the stirred synthesis gel by 2 h, (ii by addition of Fe3+ precursor as a freshlyprecipitated aqueous slurry, (iii by exploiting a secondary synthesis with Si-MCM-41 as SiO2 source. For comparative purposes the MCM-41 was also prepared by incipient wetness impregnation (IWI. Although all these synthesis methods preserved mesoporosity and long-range order of the SiO2 matrix, the hydrothermally-fabricated Fe materials prepared via the secondary synthesis route has the most useful properties for exploitation as a catalyst, in terms of hydrothermal stability of the resulting support. Temperatureprogrammed reduction (TPR studies revealed a three-peak reduction pattern for this material instead of the commonly observed two-peak reduction pattern. The three peaks showed variable intensity that related to the presence of two components: crystalline Fe2O3 and Fe embedded in the SiO2 matrix (on the basis of ESR studies. The role of secondary synthesis of Si-MCM-41 on the iron reducibility was also demonstrated in IWI of sec-Si-MCM-41.

  19. Mesoporous silica/polyacrylamide composite: Preparation by UV-graft photopolymerization, characterization and use as Hg(II) adsorbent

    Energy Technology Data Exchange (ETDEWEB)

    Saad, Ali, E-mail: ali.saad8803@gmail.com [Laboratory of Materials, Molecules and Applications, IPEST, University of Carthage, Sidi Bou Said road, B.P. 51, 2070 La Marsa (Tunisia); Faculté des Sciences de Tunis, Université El Manar, PO Box 248, El Manar II, 2092 Tunis (Tunisia); Univ Paris Diderot, Sorbonne Paris Cité, ITODYS, UMR 7086, CNRS, F-75013 Paris (France); Bakas, Idriss [Univ Paris Diderot, Sorbonne Paris Cité, ITODYS, UMR 7086, CNRS, F-75013 Paris (France); Laboratoire AQUAMAR, Equipe Matériaux Photocatalyse et Environnement, Faculté des Sciences, Université Ibn Zohr, B.P. 8106, Cité Dakhla, Agadir (Morocco); Piquemal, Jean-Yves; Nowak, Sophie [Univ Paris Diderot, Sorbonne Paris Cité, ITODYS, UMR 7086, CNRS, F-75013 Paris (France); Abderrabba, Manef, E-mail: abderrabbamanef@gmail.com [Laboratory of Materials, Molecules and Applications, IPEST, University of Carthage, Sidi Bou Said road, B.P. 51, 2070 La Marsa (Tunisia); Chehimi, Mohamed M., E-mail: chehimi@icmpe.cnrs.fr [Univ Paris Diderot, Sorbonne Paris Cité, ITODYS, UMR 7086, CNRS, F-75013 Paris (France); Université Paris Est, ICMPE (UMR7182), CNRS, UPEC, F-94320 Thiais (France)

    2016-03-30

    Graphical abstract: - Highlights: • Mesoporous silica/polyacrylamide nanocomposite adsorbent was prepared by UV-graft polymerization. • Polyacrylamide was successfully grafted onto the silanized mesoporous silica. • The Hg(II) adsorption capacity of the nanocomposite was as high as 177 mg g{sup −1} after 1 h at RT. • Adsorption process was found to fit pseudo second order kinetics and exothermic. - Abstract: MCM-41 ordered mesoporous silica was prepared, aminosilanized and grafted with polyacrylamide (PAAM) through in situ radical photopolymerization process. The resulting composite, denoted PAAM-NH{sub 2}-MCM-41, the calcined and silanized reference MCM-41s were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and N{sub 2} physisorption at 77 K. These complementary techniques brought strong supporting evidence for the silanization process followed by PAAM grafting. The surface composition was found to be PAAM-rich as judged by XPS. The composite was then employed for the uptake of Hg(II) from aqueous solutions. Adsorption was monitored versus pH, time, and temperature. The maximum adsorption capacity at 25 °C and pH 5.2 was 177 mg g{sup −1}. Kinetically, the equilibrium was reached within 60 min for a 100 mg L{sup −1} mercury solution. The adsorption of Hg(II) on PAAM-NH{sub 2}-MCM-41 composites followed second order kinetics. Thermodynamic parameters suggested that the favorable adsorption process is exothermic in nature and the adsorption is ascribed to a decrease in the degree of freedom of adsorbed ions which results in the entropy change. This work conclusively shows that mesoporous silica–polymer hybrid metal ion adsorbents (with robust silica–polymer interface) can be prepared in a simple way by in situ radical photopolymerization in the presence of

  20. Visible Light Absorption of Binuclear TiOCoII Charge-Transfer UnitAssembled in Mesoporous Silica

    Energy Technology Data Exchange (ETDEWEB)

    Han, Hongxian; Frei, Heinz

    2007-01-30

    Grafting of CoII(NCCH3)2Cl2 onto mesoporous Ti-MCM-41 silicain acetonitrile solution affords binuclear Ti-O-CoII sites on the poresurface under complete replacement of the precursor ligands byinteractions with anchored Ti centers and the silica surface. The CoIIligand field spectrum signals that the Co centers are anchored on thepore surface in tetrahedral coordination. FT-infrared action spectroscopyusing ammonia gas adsorption reveals Co-O-Si bond modes at 831 and 762cm-1. No Co oxide clusters are observed in the as-synthesized material.The bimetallic moieties feature an absorption extending from the UV intothe visible to about 600 nm which is attributed to the TiIV-O-CoII?3TiIII-O-CoIII metal-to-metal charge-transfer (MMCT) transition. Thechromophore is absent in MCM-41 containing Ti and Co centers isolatedfrom each other; this material was synthesized by grafting CoII onto aTi-MCM-41 sample with the Ti centers protected by a cyclopentadienylligand. The result indicates that the appearance of the charge-transferabsorption requires that the metal centers are linked by an oxo bridge,which is additionally supported by XANES spectroscopy. The MMCTchromophore of Ti-O-CoII units has sufficient oxidation power to serve asvisible light electron pump for driving multi-electron transfer catalystsof demanding uphill reactions such as water oxidation.

  1. Morphological Control of Multifunctional Mesoporous Silica Nanomaterials for Catalysis Applications

    Energy Technology Data Exchange (ETDEWEB)

    Huh, Seong [Iowa State Univ., Ames, IA (United States)

    2004-12-19

    I found an efficient method to control the morphology of the organically monofunctionalized mesoporous silica materials by introducing different types of organoalkoxysilanes in a base-catalyzed co-condensation reaction. The monofunctionalized materials exhibit different particle morphologies relative to the pure MCM-41 material. The concentration dependence of the morphology is a critical factor to determine the final particle shape. A proposed mechanism of the shape evolution is also offered. After understanding the role of organoalkoxysilanes in producing various well-shaped nanomaterials, I also obtained a series of bifunctional mesoporous silica materials with certain particle morphology. A series of bifunctional mesoporous silica nanospheres (MSNs) whose physicochemical properties was investigated via solid state NMR techniques and Cu2+ adsorption capacity tests, The ratio of two different organic groups inside of mesopores of these MSNs could be fine-tuned. These MSNs serve as a useful model system to study substrate selectivity in catalytic reactions and sorption phenomena. For example, the Cu2+ adsorption capacity of these materials was dictated by the chemical nature of the mesopores generated by the different organic functional groups. An investigation of the substrate selectivity of the bifunctionalized MSNs in a competitive nitroaldol reaction using an equimolar amount of two competing 4-nitrobenzaldehyde derivatives was performed. Shape-controlled bifunctional MSNs were employed as the catalysts. The properties of the MSNs were investigated using various spectroscopic methods and electron microscopy. The more hydrophobic the surface organic groups are, the higher the ratio of hydrophobic final product. This is the first example to demonstrate the selection of substrate using physicochemical nature of the mesopore surface other than the conventional shape selection in zeolite systems. I also created a cooperative dual catalyst

  2. Magnetic properties of magnetite nanoparticles coated with mesoporous silica by sonochemical method

    Energy Technology Data Exchange (ETDEWEB)

    Ursachi, Irina [Department of Physics and CARPATH Center, ' Alexandru Ioan Cuza' University of Iasi, 11 Carol I Blvd., 700506 Iasi (Romania); Vasile, Aurelia [Department of Chemistry, ' Alexandru Ioan Cuza' University of Iasi, 11 Carol I Blvd., 700506 Iasi (Romania); Chiriac, Horia [National Institute of Research and Development for Technical Physics, 47 Mangeron Blvd., 700050 Iasi (Romania); Postolache, Petronel [Department of Physics and CARPATH Center, ' Alexandru Ioan Cuza' University of Iasi, 11 Carol I Blvd., 700506 Iasi (Romania); Stancu, Alexandru, E-mail: alstancu@uaic.ro [Department of Physics and CARPATH Center, ' Alexandru Ioan Cuza' University of Iasi, 11 Carol I Blvd., 700506 Iasi (Romania)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer MCM-41-coating of magnetite nanoparticles performed under ultrasonic irradiation. Black-Right-Pointing-Pointer Ultrasonic irradiation accelerates the formation of the MCM-41 framework. Black-Right-Pointing-Pointer The hysteretic response to an applied field was investigated applying FORC diagram. Black-Right-Pointing-Pointer The average coercive field of the Fe{sub 3}O{sub 4} nanoparticles increased after coating. -- Abstract: In this paper we present the magnetic properties of mesoporous silica-coated Fe{sub 3}O{sub 4} nanoparticles. The coating of magnetite nanoparticles with mesoporous silica shell was performed under ultrasonic irradiation. The obtained mesoporous silica-coated magnetite nanoparticles were characterized by powder X-ray diffraction, focused ion beam-scanning electron microscopy, nitrogen adsorption-desorption isotherms and vibrating sample magnetometer. The hysteretic behavior was studied using first-order reversal curves diagrams. The X-ray diffraction result indicates that the extreme chemical and physical conditions created by acoustic cavitations have an insignificant effect on crystallographic structural characteristic of magnetite nanoparticles. Changes in the coercivity distributions of the magnetite nanoparticles were observed on the first-order reversal curves diagrams for the samples with coated particles compared with the samples containing uncoated particles of magnetite. The coated particles show an increased most probable coercivity of about 20% compared with the uncoated particles which can be associated with an increased anisotropy due to coating even if the interaction field distribution measured on the diagrams are virtually identical for coated/uncoated samples.

  3. Steam reforming of glycerol over Pt-MCM-41 synthesized in a one-step process

    Science.gov (United States)

    Zhang, Xiao-Hui; Yan, Feng-Wen; Guo, Cun-Yue; Yuan, Guo-Qing

    2012-12-01

    Pt-MCM-41 materials were synthesized by a simple method via simultaneous self-assembling and Pt incorporation using cetyltrimethylammonium chloride (CTAC) as a structure directing agent. Structural characterization of the sample was carried out by N2 sorption, XRD and TEM measurements. The highly ordered structure of MCM-41 was not appreciably affected by the formation of the Pt particles. Unlike related results, the Pt nanoparticles were incorporated into the mesopores and embedded into the pore walls as framework. The Pt-MCM-41 sample was tested as a catalyst in the steam reforming of glycerol in which it exhibited moderate activity, high selectivity to hydrogen, and very low selectivity to light alkanes.

  4. Ordered mesoporous silica: microwave synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Fantini, M.C.A. [IF-USP, CP 66318, 05315-970, Sao Paulo, SP (Brazil)]. E-mail: mfantini@if.usp.br; Matos, J.R. [IQ-USP, CP 26077, 05599-970, Sao Paulo, SP (Brazil); Silva, L.C. Cides da [IQ-USP, CP 26077, 05599-970, Sao Paulo, SP (Brazil); Mercuri, L.P. [IQSC-USP, CP 780, 13560-970, Sao Carlos, SP (Brazil); Chiereci, G.O. [IQSC-USP, CP 780, 13560-970, Sao Carlos, SP (Brazil); Celer, E.B. [Department of Chemistry, Kent State University, Kent, OH 44240 (United States); Jaroniec, M. [Department of Chemistry, Kent State University, Kent, OH 44240 (United States)

    2004-09-25

    Ordered mesoporous silicas, FDU-1, synthesized by using triblock copolymer, EO{sub 39}BO{sub 47}EO{sub 39}, as template were hydrothermally treated in a microwave oven at 373 K for different periods of time. The structural and morphological properties of these silicas were investigated by X-ray diffraction and nitrogen adsorption and compared with those for the FDU-1 samples prepared by conventional hydrothermal treatment at 373 K. All samples were calcined at 813 K in N{sub 2} and air. This procedure succeeded in producing ordered cage-like mesoporous structures even after 15 min of the microwave treatment. The best sample was obtained after 60 min of the microwave treatment, which is reflected by narrow pore size distribution, uniform pore size entrances and thick mesopore walls. Longer time of the microwave treatment increased nonuniformity of the pore entrance sizes as evidenced by changes in the hysteresis loops of nitrogen adsorption isotherms.

  5. Modified MCM-41 as Catalyst for Synthesis of Geranyl Propionate%改性中孔分子筛MCM-41催化合成丙酸香叶酯

    Institute of Scientific and Technical Information of China (English)

    唐晓红

    2012-01-01

    用H2SO4对中孔分子筛MCM(mobile crystalline material)-41进行改性,得到SO42–修饰的中孔分子筛SO42–/MCM-41。通过X射线衍射、红外光谱、NH3程序升温脱附和N2吸附–脱附等方法对所合成样品进行表征。用SO42–/MCM-41催化合成丙酸香叶酯,考察了催化剂处理方法、催化剂用量、催化剂再生对香叶醇酯化反应结果的影响,并比较了H2SO4、MCM-41和SO42–/MCM-41这3种催化剂对合成丙酸香叶酯的催化性能。结果表明:用浓度为0.50mol/L的硫酸浸泡MCM-41中孔分子筛1h,再于450℃焙烧3.0h,能得到良好长程有序性和结晶度的中孔分子筛SO42–/MCM-41,用其催化合成丙酸香叶酯,香叶醇的转化率最高可达88.82%,丙酸香叶酯的选择性为85.20%;H2SO4改性对MCM-41中孔分子筛结构影响不明显,但可提高其酸性。%SO42–/mobile crystalline material(MCM-41) was prepared via the modification of MCM-41 with H2SO4.Its structure was characterized by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),NH3-temperature programmed desorption(NH3-TPD) and N2 adsorption-desorption,respectively.The geranyl propionate(GP) was synthesized.Using SO42–/MCM-41 as a catalyst.The effects of amount and regeneration of the catalyst on the reaction results were investigated.H2SO4,MCM-41 and SO42–/MCM-41 were used as a catalyst for the synthesis of GP,respectively,and their catalytic properties were compared.The results show that the mesoporous molecular sieves SO42–/MCM-41with a long-range order and a good crystallinity can be obtained by dipping the mesoporous molecular sieves MCM-41 with H2SO4 of 0.50 mol/L for 1.0 h and calcining at 450 ℃ for 3.0 h.The conversion could be 88.82% and the selectivity of GP was 85.20% when the modified MCM-41 was used as a catalyst for the esterification of geraniol.The modification effect with H2SO4 on the structure of MCM-41 mesoporous molecular sieves was not

  6. Silicon oxynitrides of KCC-1, SBA-15 and MCM-41 for CO 2 capture with excellent stability and regenerability

    KAUST Repository

    Patil, Umesh

    2012-01-01

    We report the use of silicon oxynitrides as novel adsorbents for CO 2 capture. Three series of functionalized materials based on KCC-1, SBA-15 and MCM-41 with Si-NH 2 groups were prepared using a simple one-step process via thermal ammonolysis using ammonia gas, and they demonstrated excellent CO 2 capture capabilities. These materials overcome several limitations of conventional amine-grafted mesoporous silica. They offer good CO 2 capture capacity, faster adsorption-desorption kinetics, efficient regeneration and reuse, more crucially excellent thermal and mechanical stability even in oxidative environments, and a clean and green synthesis route, which allows the overall CO 2 capture process to be practical and sustainable. This journal is © The Royal Society of Chemistry 2012.

  7. pH及温度双重敏感性MCM-41/P( AA-co-N IPAAm)的制备和释药性能%Preparation and drug release of pH and temperature sensitive MCM-41/P (AA-co-NIPAAm)

    Institute of Scientific and Technical Information of China (English)

    曹渊; 张莉; 王晓; 徐彦芹

    2012-01-01

    Mesoporous silica materials with such advantages as high surface area, large pore volume, uniform porosity, stable aqueous dispersion, excellent biocompatibility, non-toxic properties, and the capability to be functionalized with different organic groups could be prepared. Such materials have the basic conditions for drug delivery due to the above advantages. In addition, in biomedical applications, smart intelligent hydrogels can be used for encapsulation of enzymes, controlled drug release, etc. and is also a good drug-carrier material. Smart intelligent hydrogels composites with mesoporous materials with the characteristics of the two materials can be made, and have a broad prospect in application. In this paper, mesoporous molecular sieve (MCM-41) was synthesized by the microwave method, and then composite material MCM-41/P (AA-co-NlPAAm) sensitive to pH value and temperature was synthesized by polymerization of MCM-41 with acrylic acid (AA) and N-isopropylacrylamide (NIPAAm) in situ. The materials were characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, Fourier transform infrared spectroscopy (FT-IR), and thermogravimetry analysis (TGA). It was found that a new polymer composite was synthesized. The polymer composite exhibited good sensitivities to both temperature and pH. Selecting hydrochlorothiazide as a model drug, the properties of drug loading and release behavior under different pH values and different temperatures were studied with ultraviolet spectrophotometry. The results showed that composite material MCM-41/P (AA-co-NIPAAm) had a high hydrochlorothiazide storage capacity of 45. 8% and hydrochlorothiazide molecules were controlled released from the composite material by adjusting the temperature and pH of the environment. The material released drug faster in simulated intestinal fluid (pH=6. 8). When the temperature was higher than 32°C , the release amount would decrease, and when the temperature was lower than 32°C , the

  8. Biological applications and transmission electron microscopy investigation of mesoporous silica nanoparticles

    Science.gov (United States)

    Trewyn, Brian G.

    The research presented and discussed within involves the development of novel biological applications of mesoporous silica nanoparticles (MSN) and an investigation of mesoporous material by transmission electron microscopy (TEM). A series of room-temperature ionic liquid (RTIL) containing mesoporous silica nanoparticle (MSN) materials with various particle morphologies, including spheres, ellipsoids, rods, and tubes, were synthesized. By changing the RTIL template, the pore morphology was tuned from the MCM-41 type of hexagonal mesopores to rotational moire type of helical channels, and to wormhole-like porous structures. These materials were used as controlled release delivery nanodevices to deliver antibacterial ionic liquids against Escherichia coli K12. The involvement of a specific organosiloxane function group, covalently attached to the exterior of fluorescein doped mesoporous silica nanoparticles (FITC-MSN), on the degree and kinetics of endocytosis in cancer and plant cells was investigated. The kinetics of endocystosis of TEG coated FITC-MSN is significantly quicker than FITC-MSN as determined by flow cytometry experiments. The fluorescence confocal microscopy investigation showed the endocytosis of TEG coated-FITC MSN triethylene glycol grafted fluorescein doped MSN (TEG coated-FITC MSN) into both HeLa cells and Tobacco root protoplasts. Once the synthesis of a controlled-release delivery system based on MCM-41-type mesoporous silica nanorods capped by disulfide bonds with superparamagnetic iron oxide nanoparticles was completed. The material was characterized by general methods and the dosage and kinetics of the antioxidant dependent release was measured. Finally, the biological interaction of the material was determined along with TEM measurements. An electron microscopy investigation proved that the pore openings of the MSN were indeed blocked by the Fe 3O4 nanoparticles. The biological interaction investigation demonstrated Fe3O4-capped MSN

  9. Mesoporous Silica: A Suitable Adsorbent for Amines

    Directory of Open Access Journals (Sweden)

    Abdollahzadeh-Ghom Sara

    2009-01-01

    Full Text Available Abstract Mesoporous silica with KIT-6 structure was investigated as a preconcentrating material in chromatographic systems for ammonia and trimethylamine. Its adsorption capacity was compared to that of existing commercial materials, showing its increased adsorption power. In addition, KIT-6 mesoporous silica efficiently adsorbs both gases, while none of the employed commercial adsorbents did. This means that KIT-6 Mesoporous silica may be a good choice for integrated chromatography/gas sensing micro-devices.

  10. High-efficient mercury removal from environmental water samples using di-thio grafted on magnetic mesoporous silica nanoparticles.

    Science.gov (United States)

    Mehdinia, Ali; Akbari, Maryam; Baradaran Kayyal, Tohid; Azad, Mohammad

    2015-02-01

    In this work, magnetic di-thio functionalized mesoporous silica nanoparticles (DT-MCM-41) were prepared by grafting dithiocarbamate groups within the channels of magnetic mesoporous silica nanocomposites. The functionalized nanoparticles exhibited proper magnetic behavior. They were easily separated from the aqueous solution by applying an external magnetic field. The results indicated that the functionalized nanoparticles had a potential for high-efficient removal of Hg(2+) in environmental samples. The maximum adsorption capacity of the sorbent was 538.9 mg g(-1), and it took about 10 min to achieve the equilibrium adsorption. The resulted adsorption capacity was higher than similar works for adsorption of mercury. It can be due to the presence of di-thio and amine active groups in the structure of sorbent. The special properties of MCM-41 like large surface area and high porosity also provided a facile accessibility of the mercury ions into the ligand sites. The complete removal of mercury ions was attained with dithiocarbamate groups in a wide range of mercury concentrations. The recovery studies were also applied for the river water, seawater, and wastewater samples, and the values were over of 97 %.

  11. Density profile of nitrogen in cylindrical pores of MCM-41

    Science.gov (United States)

    Soper, Alan K.; Bowron, Daniel T.

    2017-09-01

    A straightforward approach using radiation scattering (X-ray or neutron) combined with atomistic modelling is used to accurately assess the pore dimensions in the porous silica, MCM-41. The method is used to calculate the density profile of nitrogen absorbed in this material at a variety of fractional pressures, p/p0, where p0 is the saturated vapour pressure, up to p/p0 = 0.36 at T = 87 K in the present instance. At this pressure two distinct layers of liquid nitrogen occur on the silica surface, with a relatively sharp gas-liquid interface. It is suggested surface tension effects at this interface strongly influence the growth of further layers.

  12. A novel method for fast enrichment and monitoring of hexavalent and trivalent chromium at the ppt level with modified silica MCM-41 and its determination by inductively coupled plasma optical emission spectrometry

    Directory of Open Access Journals (Sweden)

    Ganjali Mohammad Reza

    2006-01-01

    Full Text Available Chromium(III at the ng L-1 level was extracted using partially silylated MCM-41 modified by a tetraazamacrocyclic compound (TAMC and determined by inductively coupled plasma optical emision spectrometry (ICP OES. The extraction time and efficiency, pH and flow rate, type and minimum amount of stripping acid, and break- through volume were investigated. The method's enrichment factor and detection limit are 300 and 45.5 pg mL-1, respectively. The maximum capacity of the 10 mg of modified silylated MCM-41 was found to be 400.5?4.7 µg for Cr(III. The method was applied to the determination of Cr(III and Cr(VI in the wastewater of the chromium electroplating industry and in environmental and biological samples (black tea, hot and black pepper.

  13. Desorption Kinetics and Mechanisms of CO2 on Amine-Based Mesoporous Silica Materials

    Directory of Open Access Journals (Sweden)

    Yang Teng

    2017-01-01

    Full Text Available Tetraethylenepentamine (TEPA-based mesoporous MCM-41 is used as the adsorbent to determine the CO2 desorption kinetics of amine-modified materials after adsorption. The experimental data of CO2 desorption as a function of time are derived by zero-length column at different temperatures (35, 50, and 70 °C and analyzed by Avrami’s fractional-order kinetic model. A new method is used to distinguish the physical desorption and chemical desorption performance of surface-modified mesoporous MCM-41. The activation energy Ea of CO2 physical desorption and chemical desorption calculated from Arrhenius equation are 15.86 kJ/mol and 57.15 kJ/mol, respectively. Furthermore, intraparticle diffusion and Boyd’s film models are selected to investigate the mechanism of CO2 desorption from MCM-41 and surface-modified MCM-41. For MCM-41, there are three rate-limiting steps during the desorption process. Film diffusion is more prominent for the CO2 desorption rates at low temperatures, and pore diffusion mainly governs the rate-limiting process under higher temperatures. Besides the surface reaction, the desorption process contains four rate-limiting steps on surface-modified MCM-41.

  14. Enhanced adsorption of the cationic dyes in the spherical CuO/meso-silica nano composite and impact of solution chemistry.

    Science.gov (United States)

    Liang, Zhijie; Zhao, Zhiwei; Sun, Tianyi; Shi, Wenxin; Cui, Fuyi

    2017-01-01

    In this study, the spherical mesoporous silica (meso-silica MCM-41) and that inorganically modified with CuO (CuO/MCM-41 nano composite) were synthesized and characterized. It was demonstrated that CuO were successfully loaded in the synthesized nano composite CuO/MCM-41. Importantly, the loaded CuO had a significant enhancement effect on the adsorption of Crystal violet and Methylene blue. Adsorption kinetic of the tested cationic dyes in the synthesized materials fitted the pseudo-second-order kinetic model and Weber's intra-particle diffusion model well. According to the Langmuir isotherm model, the maximum adsorption capacities (Qmax) of the CuO/MCM-41 towards Crystal violet and Methylene blue increased to 52.9 and 87.8mg/g, while those of the pure MCM-41 were 46.2 and 65.7mg/g, respectively. Due to the surface charge of CuO and the protonation of the dye molecules, the electrostatic forces between the loaded CuO and the organic cationic dyes contributed to the enhancement effect. Additionally, the presented results indicated that the adsorption of the cationic dyes in the CuO/MCM-41 depended on pH and ion strength of the solution but insignificantly on the coexisted humic acid due to the mesoporous character of CuO/MCM-41 nano composite.

  15. Cellular membrane trafficking of mesoporous silica nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Fang, I-Ju [Iowa State Univ., Ames, IA (United States)

    2012-01-01

    This dissertation mainly focuses on the investigation of the cellular membrane trafficking of mesoporous silica nanoparticles. We are interested in the study of endocytosis and exocytosis behaviors of mesoporous silica nanoparticles with desired surface functionality. The relationship between mesoporous silica nanoparticles and membrane trafficking of cells, either cancerous cells or normal cells was examined. Since mesoporous silica nanoparticles were applied in many drug delivery cases, the endocytotic efficiency of mesoporous silica nanoparticles needs to be investigated in more details in order to design the cellular drug delivery system in the controlled way. It is well known that cells can engulf some molecules outside of the cells through a receptor-ligand associated endocytosis. We are interested to determine if those biomolecules binding to cell surface receptors can be utilized on mesoporous silica nanoparticle materials to improve the uptake efficiency or govern the mechanism of endocytosis of mesoporous silica nanoparticles. Arginine-glycine-aspartate (RGD) is a small peptide recognized by cell integrin receptors and it was reported that avidin internalization was highly promoted by tumor lectin. Both RGD and avidin were linked to the surface of mesoporous silica nanoparticle materials to investigate the effect of receptor-associated biomolecule on cellular endocytosis efficiency. The effect of ligand types, ligand conformation and ligand density were discussed in Chapter 2 and 3. Furthermore, the exocytosis of mesoporous silica nanoparticles is very attractive for biological applications. The cellular protein sequestration study of mesoporous silica nanoparticles was examined for further information of the intracellular pathway of endocytosed mesoporous silica nanoparticle materials. The surface functionality of mesoporous silica nanoparticle materials demonstrated selectivity among the materials and cancer and normal cell lines. We aimed to determine

  16. Mesoporous Silica Nanoparticles with Co-Condensed Gadolinium Chelates for Multimodal Imaging.

    Science.gov (United States)

    Taylor-Pashow, Kathryn M L; Della Rocca, Joseph; Lin, Wenbin

    2012-03-01

    Several mesoporous silica nanoparticle (MSN) contrast agents have been synthesized using a co-condensation method to incorporate two different Gd(3+) complexes at very high loadings (15.5-28.8 wt %). These MSN contrast agents, with an MCM-41 type pore structure, were characterized using a variety of methods including SEM and TEM, nitrogen adsorption measurements, thermogravimetric analysis (TGA), direct current plasma (DCP) spectroscopy, and powder X-ray diffraction (PXRD). The magnetic resonance (MR) relaxivities of these contrast agents were determined using a 3 T MR scanner. The r1 relaxivities of these nanoparticles range from 4.1 to 8.4 mM(-1)s(-1) on a per Gd basis. Additionally, the MSN particles were functionalized with an organic fluorophore and cancer cell targeting peptide to allow for demonstration of both the optical and MR contrast enhancing capabilities in vitro.

  17. Mesoporous Silica Nanoparticles with Co-Condensed Gadolinium Chelates for Multimodal Imaging

    Directory of Open Access Journals (Sweden)

    Wenbin Lin

    2011-12-01

    Full Text Available Several mesoporous silica nanoparticle (MSN contrast agents have been synthesized using a co-condensation method to incorporate two different Gd3+ complexes at very high loadings (15.5–28.8 wt %. These MSN contrast agents, with an MCM-41 type pore structure, were characterized using a variety of methods including SEM and TEM, nitrogen adsorption measurements, thermogravimetric analysis (TGA, direct current plasma (DCP spectroscopy, and powder X-ray diffraction (PXRD. The magnetic resonance (MR relaxivities of these contrast agents were determined using a 3 T MR scanner. The r1 relaxivities of these nanoparticles range from 4.1 to 8.4 mM−1s−1 on a per Gd basis. Additionally, the MSN particles were functionalized with an organic fluorophore and cancer cell targeting peptide to allow for demonstration of both the optical and MR contrast enhancing capabilities in vitro.

  18. Interaction of mesoporous silica nanoparticles with human red blood cell membranes: size and surface effects.

    Science.gov (United States)

    Zhao, Yannan; Sun, Xiaoxing; Zhang, Guannan; Trewyn, Brian G; Slowing, Igor I; Lin, Victor S-Y

    2011-02-22

    The interactions of mesoporous silica nanoparticles (MSNs) of different particle sizes and surface properties with human red blood cell (RBC) membranes were investigated by membrane filtration, flow cytometry, and various microscopic techniques. Small MCM-41-type MSNs (∼100 nm) were found to adsorb to the surface of RBCs without disturbing the membrane or morphology. In contrast, adsorption of large SBA-15-type MSNs (∼600 nm) to RBCs induced a strong local membrane deformation leading to spiculation of RBCs, internalization of the particles, and eventual hemolysis. In addition, the relationship between the degree of MSN surface functionalization and the degree of its interaction with RBC, as well as the effect of RBC-MSN interaction on cellular deformability, were investigated. The results presented here provide a better understanding of the mechanisms of RBC-MSN interaction and the hemolytic activity of MSNs and will assist in the rational design of hemocompatible MSNs for intravenous drug delivery and in vivo imaging.

  19. Magnetically separable core-shell structural γ-Fe2O3@Cu/Al-MCM-41 nanocomposite and its performance in heterogeneous Fenton catalysis.

    Science.gov (United States)

    Ling, Yuhan; Long, Mingce; Hu, Peidong; Chen, Ya; Huang, Juwei

    2014-01-15

    To target the low catalytic activity and the inconvenient separation of copper loading nanocatalysts in heterogeneous Fenton-like reaction, a core-shell structural magnetically separable catalyst, with γ-Fe2O3 nanoparticles as the core layer and the copper and aluminum containing MCM-41 as the shell layer, has been fabricated. The role of aluminum has been discussed by comparing the copper containing mesoporous silica with various Cu contents. Their physiochemical properties have been characterized by XRD, UV-vis, FT-IR, TEM, nitrogen physisorption and magnetite susceptibility measurements. Double content Cu incorporation results in an improved catalytic activity for phenol degradation at the given condition (40°C, initial pH=4), but leads to a declined BET surface area and less ordered mesophase structure. Aluminum incorporation helps to retain the high BET surface area (785.2m(2)/g) and the regular hexagonal mesoporous structure of MCM-41, which make the catalyst possess a lower copper content and even a higher catalytic activity than that with the double copper content in the absence of aluminum. The catalysts can be facilely separated by an external magnetic field for recycle usage.

  20. Synthesis of Fe-MCM-41 Using Iron Ore Tailings as the Silicon and Iron Source.

    Science.gov (United States)

    Li, Xin; Yu, Honghao; He, Yan; Xue, Xiangxin

    2012-01-01

    Highly ordered Fe-MCM-41 molecular sieve was successfully synthesized by using n-hexadecyl-trimethyl ammonium bromide (CTAB) as the template and the iron ore tailings (IOTs) as the silicon and iron source. X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), diffuse reflectance UV-visible spectroscopy, (29)Si magic-angle spinning (MAS) nuclear magnetic resonance (NMR), and nitrogen adsorption/desorption were used to characterize the samples. The results showed that the mesoporous materials had highly ordered 2-dimensional hexagonal structure. The synthesized sample had high surface area, and part of iron atoms is retained in the framework with formation of tetrahedron after removal of the template by calcinations. The results obtained in the present work demonstrate the feasibility of employing iron ore tailings as a potential source of silicon and iron to produce Fe-MCM-41 mesoporous materials.

  1. Synthesis of Fe-MCM-41 Using Iron Ore Tailings as the Silicon and Iron Source

    Directory of Open Access Journals (Sweden)

    Xin Li

    2012-01-01

    Full Text Available Highly ordered Fe-MCM-41 molecular sieve was successfully synthesized by using n-hexadecyl-trimethyl ammonium bromide (CTAB as the template and the iron ore tailings (IOTs as the silicon and iron source. X-ray diffraction (XRD, high-resolution transmission electron microscopy (HRTEM, diffuse reflectance UV-visible spectroscopy, 29Si magic-angle spinning (MAS nuclear magnetic resonance (NMR, and nitrogen adsorption/desorption were used to characterize the samples. The results showed that the mesoporous materials had highly ordered 2-dimensional hexagonal structure. The synthesized sample had high surface area, and part of iron atoms is retained in the framework with formation of tetrahedron after removal of the template by calcinations. The results obtained in the present work demonstrate the feasibility of employing iron ore tailings as a potential source of silicon and iron to produce Fe-MCM-41 mesoporous materials.

  2. Carbon dioxide capture by MgO-modified MCM-41 materials

    Energy Technology Data Exchange (ETDEWEB)

    Fu, X.; Zhao, N.; Li, J.P.; Xiao, F.K.; Wei, W.; Sun, Y.H. [Chinese Academy of Sciences, Taiyuan (China). Inst. of Coal Chemistry

    2009-07-01

    MgO/MCM-41 materials with weak basic sites were synthesized by dispersing MgO onto mesoporous Si-MCM-41. Such MgO-modified MCM-41 materials were characterized by Fourier-transform infrared spectroscopy (FT-IR), temperature programmed desorption (TPD), X-ray diffraction (XRD) and N{sub 2} adsorption/desorption measurements. The results indicated that the surface area, pore size and pore volume of the materials decreased with the introduction of MgO. Their CO{sub 2} uptakes could be significantly improved when the MgO loading was increased from 0 wt% to 20 wt%. CO{sub 2}-TPD and in situ FT-IR measurements showed that the materials possessed weak basic sites which could react with CO{sub 2} to form bicarbonate species and thereby improve the CO{sub 2} uptake. As a result, the adsorbed CO{sub 2} could be desorbed completely from the sample at 200{sup o} C. In addition, the MgO/MCM-41 materials had a high thermal stability and showed promising performances in practical applications.

  3. Encapsulation and Fluorescence of the Functional Supramolecular Material Between MCM-41 and Rh6G

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@ Molecular sieves encapsulated organic dyes and metal chelates have been reviewed[1],the luminescent behavior of some organic compounds in molecular sieves has also been studied[2,3].Rh6G (Rhodamine 6G) is one kind of organic dye which is widely used in many fields such as optics,spectroscopy and laser techniques.It has a high stability and an efficiency quantum yield as an excellent fluorescent compound.The mesoporous molecular sieve MCM-41 possesses advantageous absorption property.It is conceivable that studies on the encapsulation of the fluorescent organic compounds in MCM-41 may give a new impetus to working on solid-state luminescence.We have reported the encapsulation of rhodamine B into MCM-41 and its fluorescent property[4].In this paper,the encapsulation and the fluorescence of the functional supramolecular material of MCM-41,which was synthesized by means of MRM(Microwave radiation method),encapsulated Rh6G have been reported.

  4. Quick photo-Fenton degradation of phenolic compounds by Cu/Al2O3-MCM-41 under visible light irradiation: small particle size, stabilization of copper, easy reducibility of Cu and visible light active material.

    Science.gov (United States)

    Pradhan, Amaresh C; Nanda, Binita; Parida, K M; Das, Mira

    2013-01-14

    The present study reports the photo-Fenton degradation of phenolic compounds (phenol, 2-chloro-4-nitrophenol and 4-chloro-2-nitrophenol) in aqueous solution using mesoporous Cu/Al(2)O(3)-MCM-41 nanocomposite as a heterogeneous photo-Fenton-like catalyst. The in situ incorporation of mesoporous Al(2)O(3) (MA) into the framework of MCM-41 (sol-gel method) forms Al(2)O(3)-MCM-41 and wetness impregnation of Cu(II) on Al(2)O(3)-MCM-41 generates mesoporous Cu/Al(2)O(3)-MCM-41 composite. The effects of pH and H(2)O(2) concentration on degradation of phenol, 2-chloro-4-nitrophenol and 4-chloro-2-nitrophenol are studied. Kinetics analysis shows that the photocatalytic degradation reaction follows a first-order rate equation. Mesoporous 5 Cu/Al(2)O(3)-MCM-41 is found to be an efficient photo-Fenton-like catalyst for the degradation of phenolic compounds. It shows nearly 100% degradation in 45 min at pH 4. The combined effect of small particle size, stabilization of Cu(2+) on the support Al(2)O(3)-MCM-41, ease reducibility of Cu(2+) and visible light activeness are the key factors for quick degradation of phenolic compounds by Cu/Al(2)O(3)-MCM-41.

  5. Functionalized magnetic mesoporous silica nanoparticles for U removal from low and high pH groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Li, Dien, E-mail: dien.li@srs.gov [Savannah River National Laboratory, Aiken, SC 29808 (United States); Egodawatte, Shani [Department of Chemistry, University of Iowa, Iowa City, IA 52242 (United States); Kaplan, Daniel I. [Savannah River National Laboratory, Aiken, SC 29808 (United States); Larsen, Sarah C. [Department of Chemistry, University of Iowa, Iowa City, IA 52242 (United States); Serkiz, Steven M. [Savannah River National Laboratory, Aiken, SC 29808 (United States); Department of Physics and Astronomy, Clemson University, Clemson, SC 29634 (United States); Seaman, John C. [Savannah River Ecology Laboratory, University of Georgia, Aiken, SC 29802 (United States)

    2016-11-05

    Highlights: • Magnetic mesoporous silica nanoparticles were functionalized with organic molecules. • The functionalized nanoparticles had high surface areas and consistent pore sizes. • The functionalized nanoparticles were easily separated due to their magnetism. • They exhibited high capacity for uranium removal from low- or high-pH groundwater. - Abstract: U(VI) species display limited adsorption onto sediment minerals and synthetic sorbents in pH <4 or pH >8 groundwater. In this work, magnetic mesoporous silica nanoparticles (MMSNs) with magnetite nanoparticle cores were functionalized with various organic molecules using post-synthetic methods. The functionalized MMSNs were characterized using N{sub 2} adsorption-desorption isotherms, thermogravimetric analysis (TGA), transmission electron microscopy (TEM), {sup 13}C cross polarization and magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectroscopy, and powder X-ray diffraction (XRD), which indicated that mesoporous silica (MCM-41) particles of 100–200 nm formed around a core of magnetic iron oxide, and the functional groups were primarily grafted into the mesopores of ∼3.0 nm in size. The functionalized MMSNs were effective for U removal from pH 3.5 and 9.6 artificial groundwater (AGW). Functionalized MMSNs removed U from the pH 3.5 AGW by as much as 6 orders of magnitude more than unfunctionalized nanoparticles or silica and had adsorption capacities as high as 38 mg/g. They removed U from the pH 9.6 AGW as much as 4 orders of magnitude greater than silica and 2 orders of magnitude greater than the unfunctionalized nanoparticles with adsorption capacities as high as 133 mg/g. These results provide an applied solution for treating U contamination that occurs at extreme pH environments and a scientific foundation for solving critical industrial issues related to environmental stewardship and nuclear power production.

  6. Capillary Condensation Pathways of CO2 under Templated Mesoporous Silica Confinement

    Science.gov (United States)

    Wang, Bo; Sokol, Paul

    2014-03-01

    Adsorption of CO2 in porous medium has been of great current interest due to its potential for mitigating the global warming caused by greenhouse gases. In particular, the behavior of confined CO2 in mesoporous media near room temperature is particularly relevant to sequestration efforts. Realistic mesoporous systems, such as shales and coals, represent a complex fractal pore structure that complicates the interpretation of adsorption studies. We present the results of a study focused on the adsorption of CO2 in model mesoporous media with well-defined pore structures. Templated porous glasses, such as MCM-41 which has a regular network of 1D pores, provide an ideal system for fundamental studies of the adsorption process. In this study, we focus on the structure of adsorbed CO2 films which evolves in a mixture of phases and the development of nucleation occurs during the formation of high density liquid CO2 inside the confining matrix. We have used Small Angle Neutron Scattering to study the spatial distribution of material radially and transversely within the pores. The 30m SANS NG7 at NIST was used to map out the details of CO2 condensation pathway under mesoporous silica confinement.

  7. The impact of framework organic functional groups on the hydrophobicity and overall stability of mesoporous silica materials

    Energy Technology Data Exchange (ETDEWEB)

    Smeulders, Geert, E-mail: geert.smeulders@ua.ac.be [University of Antwerpen (Ukraine), Laboratory of Adsorption and Catalysis, Universiteitsplein 1, 2610 Wilrijk (Belgium); Meynen, Vera [University of Antwerpen (Ukraine), Laboratory of Adsorption and Catalysis, Universiteitsplein 1, 2610 Wilrijk (Belgium); Silvestre-Albero, Ana [Universidad de Alicante, Laboratorio de Materiales Avanzados, Apartado 99, 03080 Alicante (Spain); Houthoofd, Kristof [KULeuven, Centre for Surface Chemistry and Catalysis, Kasteelpark Arenberg 23, 3001 Heverlee (Belgium); Mertens, Myrjam [Flemish Institute for Technological Research (VITO N.V.), Boeretang 200, 2400 Mol (Belgium); Silvestre-Albero, Joaquin [Universidad de Alicante, Laboratorio de Materiales Avanzados, Apartado 99, 03080 Alicante (Spain); Martens, Johan A. [KULeuven, Centre for Surface Chemistry and Catalysis, Kasteelpark Arenberg 23, 3001 Heverlee (Belgium); Cool, Pegie [University of Antwerpen (Ukraine), Laboratory of Adsorption and Catalysis, Universiteitsplein 1, 2610 Wilrijk (Belgium)

    2012-02-15

    Graphical abstract: The stability (hydrothermal, mechanical and chemical) of PMOs is studied in a systematic way and ranks them between classic and other hybrid mesoporous silica materials. Highlights: Black-Right-Pointing-Pointer The stability (hydrothermal, mechanical and chemical) of PMOs is studied. Black-Right-Pointing-Pointer Compared stability of PMOs with classic and other hybrid mesoporous silica materials. Black-Right-Pointing-Pointer Immersion calorimetry to study the effect of hydrophobicity. Black-Right-Pointing-Pointer PMOs show superior stability. - Abstract: The hydrothermal, mechanical and chemical stability of various mesoporous materials have been studied in detail, using X-ray diffraction and nitrogen sorption. Pure siliceous nanoporous powders (MCM-41 and SBA-15) are evaluated against their hybrid counterparts; namely 2 types of periodic mesoporous organosilicas (benzene and ethane bridged PMOs) and an organosilane grafted MCM-41 material. In primary tests, the stability of the hybrid materials is found to be superior compared to that of the pure siliceous ones. The stability of the materials was correlated to their hydrophobicity via immersion calorimetry, applied for the first time in this context. Based on these results, a clear correlation between the hydrophobicity of a material and its stability has been revealed. In addition, with {sup 29}Si-MAS-NMR and vacuum experiments, the mechanism of the structural deterioration in the three different stability treatments could be unambiguously identified as the hydrolyzation of the siloxane bonds. The homogeneity of the hydrophobic groups throughout the entire network was found to be of great importance, irrespective of the hydrophobic nature at the surface as determined by calorimetric measurements. The results reveal that the most stable material can withstand (a) a pressure of 740 MPa during 5 min, (b) a 2 h stirring in a 2 M NaOH solution and (c) a 3 day steaming treatment at 393 K.

  8. Adsorption and desorption characteristics of DNA onto the surface of amino functional mesoporous silica with various particle morphologies.

    Science.gov (United States)

    Hikosaka, Ryouichi; Nagata, Fukue; Tomita, Masahiro; Kato, Katsuya

    2016-04-01

    Recently, deoxyribonucleic acid (DNA) adsorption on solid materials has been reported for applications such as genetic diagnosis of diseases, gene delivery, and biosensors. Mesoporous silica (MPS) is an excellent carrier because of its high surface area and large pore volume. Functionalization of the MPS surface can be controlled by silane coupling reagents, and the MPS particle morphology can be easily changed by the synthetic conditions. In this study, to evaluate the ability of DNA adsorption on MPS, the MPS surface was functionalized using four reagents, 3-aminopropyltriethoxysilane (-NH2), N-(2-aminoethyl)-3-aminopropyltriethoxysilane (-2ENH2), N-(6-aminohexyl)aminopropyltrimethoxysilane (-2HNH2), and (3-trimethoxysilylpropyl)diethylenetriamine (-3NH2), each having a different number of amino groups and alkyl chain lengths. Moreover, we prepared three types of MPSs with different particle morphologies: sheet-type structure (MPS sheet), spherical MPS (MCM-41s), and nonporous spherical silica. A high adsorption capacity was observed in MPS sheets with -2HNH2 (sheet-2HNH2) and -3NH2 (sheet-3NH2), as well as MCM-41s with -3NH2 (41s-3NH2). The adsorption and desorption rates of DNA on these three MPSs were then examined and the best results were obtained with 41s-3NH2. These results demonstrate that the amino functionalized MPS materials are useful DNA adsorbents.

  9. Ordered mesoporous silica materials with complicated structures

    KAUST Repository

    Han, Yu

    2012-05-01

    Periodically ordered mesoporous silicas constitute one of the most important branches of porous materials that are extensively employed in various chemical engineering applications including adsorption, separation and catalysis. This short review gives an introduction to recently developed mesoporous silicas with emphasis on their complicated structures and synthesis mechanisms. In addition, two powerful techniques for solving complex mesoporous structures, electron crystallography and electron tomography, are compared to elucidate their respective strength and limitations. Some critical issues and challenges regarding the development of novel mesoporous structures as well as their applications are also discussed. © 2011 Elsevier Ltd.

  10. Structural Variety and Adsorptive Properties of Mesoporous Silicas with Immobilized Oligosaccharide Groups

    Science.gov (United States)

    Trofymchuk, Iryna; Roik, Nadiia; Belyakova, Lyudmila

    2017-04-01

    In this research, we report on the synthesis of mesoporous silicas with various quantities of immobilized oligosaccharide groups and different pore ordering degree. The hydrothermal co-condensation of tetraethyl orthosilicate and β-cyclodextrin-containing organosilane in the presence of cetyltrimethylammonium bromide template was employed. The purpose of this investigation was to show the opportunity of increasing β-cyclodextrin content in silica matrix by changing the molar ratio of initial reagents during organosilane synthesis and to determine whether the enhancing of immobilized groups on the surface influences on model aromatic compound adsorption from water. It was prepared several β-cyclodextrin-organosilanes by modification of (3-aminopropyl)triethoxysilane with oligosaccharide (the molar composition of reaction mixtures were 1:1, 3:1, and 5:1) with using N, N'-carbonyldiimidazole as linking agent. Three types of MCM-41 materials were obtained with 0.018, 0.072, and 0.095 mmol g-1 β-cyclodextrin-group loading according to chemical analysis of silicas. The IR spectroscopy and potentiometric titration were also performed to confirm the presence of functional groups in the silica matrix. Nitrogen sorptometry experiments exhibited the decrease of high surface area (from 812 to 457 m2 g-1) and the average pore diameter (from 1.06 to 0.60 cm3 g-1) of synthesized silicas with increasing of immobilized oligosaccharide groups. The influence of β-cyclodextrin-organosilane presence on the forming of hexagonally arranged porous structure of silicas was evaluated by X-ray diffraction and TEM analyses. As the loading of oligosaccharide groups increases in obtained silicas, the (100) reflex in diffraction patterns is even less intense and broader, denoting the decrease of long-range pore ordering. Adsorption experiments were carried out to study the effect of β-cyclodextrin groups' attendance in silica matrix on benzene uptakes from aqueous solutions. Experimental

  11. PREPARATION AND APPLICATION OF HIGHLY ORDERED LARGE SIZE MESOPOROUS SILICA%高结晶规则大孔硅的制备和应用

    Institute of Scientific and Technical Information of China (English)

    李波; 稻恒伸一; 宫崎千绘; 高桥治雄

    2000-01-01

    FSM-16, MCM-41 and SBA-15 type hexagonal mesoporous silica materials of a highly regular arrange and 2-dimensional structure were synthesized by using different silicon sources and surfactants. In the 2-dimensional silicate framework, pore size can be controlled by the surfactants having different alkyl chains length and swelling agents (triisopropyl benzene). The pore-diameter of FSM-16 and MCM-41 can be expanded to 10 nm, SBA-15 to 15 nm. Crystal regularities decreased with the increase of the pore-diameter. In the FSM-16 derived from Kanemite (silicon source) and MCM-41 from water glass, its anionic characteristics on the pore-wall may be higher than that of SBA-15 derived from oligomeric tetramethoxysilane (TMOS). FSM-16 and MCM-41 have successfully been used as immobilizing agents of enzyme having cationic residues under isoelectric point. The level of adsorption of enzymes in the FSM-16 and MCM-41 was relatively high, but was low in the SBA-15 support. The mechanism of enzyme adsorption in mesopore was suggested to be the ionic interactions. In aqueous solutions, horseradish peroxidase (HRP). immobilized in FSM-16 containing 8.9 nm mesopore showed the highest loaded amounts (183 mg/mg FSM), then a FSM-16 of pore diameter 30 nm only loaded a litter amounts (28 mg/mg FSM) on the outside surface. The catalytic activity in organic solvent is high when HRP was immobilized in FSM-16 and MCM-41, but is low in case of SBA-15.%FSM-16,MCM-41和SBA-15等具有高规则二维六角晶格的多孔硅可用不同硅源和表面活性剂合成,其孔径可达10,15或30 nm,可用具有不同烷基链长的表面活性剂和膨胀剂控制其结晶规则性随孔径的增大而降低.用层状硅土Kanemite制备的FSM-16和来自水玻璃的MCM-41,其表面阴离子度比用四甲氧基硅烷(TMOS)制备的SBA-15高得多.如将在等电点以下呈阴离子性的生物酶插入硅孔,则由于离子间的相互作用和氢键结合力,可得到结合得十分稳定的生

  12. Rapid synthesis of Ti-MCM-41 by microwave-assisted hydrothermal method towards photocatalytic degradation of oxytetracycline.

    Science.gov (United States)

    Chen, Hanlin; Peng, Yen-Ping; Chen, Ku-Fan; Lai, Chia-Hsiang; Lin, Yung-Chang

    2016-06-01

    This study employed microwave-assisted hydrothermal method to synthesize Ti-MCM-41, which are mesoporous materials with a high surface area and excellent photocatalytic ability. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and ultraviolet-visible spectroscopy (UV-Vis) were employed. The XRD findings showed that Ti-MCM-41 exhibited a peak at 2θ of 2.2°, which was attributed to the hexagonal MCM-41 structure. The BET (Brunauer-Emmett-Teller) results agreed with the TEM findings that Ti-MCM-41 has a pore size of about 3-5nm and a high surface area of 883m(2)/g. FTIR results illustrated the existence of Si-O-Si and Si-O-Ti bonds in Ti-MCM-41. The appearance of Ti 2p peaks in the XPS results confirmed the FTIR findings that the Ti was successfully doped into the MCM-41 structure. Zeta (ζ)-potential results indicated that the iso-electric point (IEP) of Ti-MCM-41 was at about pH3.02. In this study, the photocatalytic degradation of oxytetracycline (OTC) at different pH was investigated under Hg lamp irradiation (wavelength 365nm). The rate constant (K'obs) for OTC degradation was 0.012min(-1) at pH3. Furthermore, TOC (total organic carbon) and high resolution LC-MS (liquid chromatography-mass spectrometry) analyses were conducted to elucidate the possible intermediate products and degradation pathway for OTC. The TOC removal efficiency of OTC degradation was 87.0%, 74.4% and 50.9% at pH3, 7 and 10, respectively. LC-MS analysis results showed that the degradation products from OTC resulted from the removal of functional groups from the OTC ring.

  13. Mesoporous Silica Supported Pd-MnOx Catalysts with Excellent Catalytic Activity in Room-Temperature Formic Acid Decomposition

    Science.gov (United States)

    Jin, Min-Ho; Oh, Duckkyu; Park, Ju-Hyoung; Lee, Chun-Boo; Lee, Sung-Wook; Park, Jong-Soo; Lee, Kwan-Young; Lee, Dong-Wook

    2016-01-01

    For the application of formic acid as a liquid organic hydrogen carrier, development of efficient catalysts for dehydrogenation of formic acid is a challenging topic, and most studies have so far focused on the composition of metals and supports, the size effect of metal nanoparticles, and surface chemistry of supports. Another influential factor is highly desired to overcome the current limitation of heterogeneous catalysis for formic acid decomposition. Here, we first investigated the effect of support pore structure on formic acid decomposition performance at room temperature by using mesoporous silica materials with different pore structures such as KIE-6, MCM-41, and SBA-15, and achieved the excellent catalytic activity (TOF: 593 h−1) by only controlling the pore structure of mesoporous silica supports. In addition, we demonstrated that 3D interconnected pore structure of mesoporous silica supports is more favorable to the mass transfer than 2D cylindrical mesopore structure, and the better mass transfer provides higher catalytic activity in formic acid decomposition. If the pore morphology of catalytic supports such as 3D wormhole or 2D cylinder is identical, large pore size combined with high pore volume is a crucial factor to achieve high catalytic performance. PMID:27666280

  14. Mesoporous Silica Supported Pd-MnOx Catalysts with Excellent Catalytic Activity in Room-Temperature Formic Acid Decomposition

    Science.gov (United States)

    Jin, Min-Ho; Oh, Duckkyu; Park, Ju-Hyoung; Lee, Chun-Boo; Lee, Sung-Wook; Park, Jong-Soo; Lee, Kwan-Young; Lee, Dong-Wook

    2016-09-01

    For the application of formic acid as a liquid organic hydrogen carrier, development of efficient catalysts for dehydrogenation of formic acid is a challenging topic, and most studies have so far focused on the composition of metals and supports, the size effect of metal nanoparticles, and surface chemistry of supports. Another influential factor is highly desired to overcome the current limitation of heterogeneous catalysis for formic acid decomposition. Here, we first investigated the effect of support pore structure on formic acid decomposition performance at room temperature by using mesoporous silica materials with different pore structures such as KIE-6, MCM-41, and SBA-15, and achieved the excellent catalytic activity (TOF: 593 h-1) by only controlling the pore structure of mesoporous silica supports. In addition, we demonstrated that 3D interconnected pore structure of mesoporous silica supports is more favorable to the mass transfer than 2D cylindrical mesopore structure, and the better mass transfer provides higher catalytic activity in formic acid decomposition. If the pore morphology of catalytic supports such as 3D wormhole or 2D cylinder is identical, large pore size combined with high pore volume is a crucial factor to achieve high catalytic performance.

  15. Synthesis of nanosize MCM-41 loaded with TiO 2 and study of its photocatalytic activity

    Science.gov (United States)

    Sadjadi, M. S.; Farhadyar, N.; Zare, K.

    2009-07-01

    In recent years, nanosized mesoporous materials have received significant attention due to their impact in different processes. Several diverse applications of these materials, e.g. high density magnetic recording, magnetic fluids, magnetic refrigeration as well as in photocatalysis, solar cells, photosensors, have triggered considerable research activities in the area of nanotechnology. In this work, nanosize MCM-41 was synthesized and loaded then with TiO 2 using tetra butoxy titanium (TBT). As prepared TiO 2 loaded materials was investigated by using X-ray diffraction (XRD), Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR). The photocatalytic activity of the prepared TiO 2 loaded MCM-41 was finally evaluated by the degradation of methyl orange under irradiation of UV light. The result showed that TiO 2 loaded on nanosize MCM-41 has higher photocatalytic activity than that of TiO 2.

  16. Preparation of MCM-41-supported chiral Salen Mn (Ⅲ) catalysts and their catalytic properties in the asymmetric epoxidation of olefins

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A secondary amino-modified mesoporous molecular sieve MCM-41 was obtained by reaction of bis(3-(triethoxysilyl)propyl)amine with MCM-41. The chiral Salen-Mn (Ⅲ) complex was anchored onto the modified MCM-41 by a multi-step grafting method and two heterogenized catalysts with different Mn contents were obtained. The catalysts were characterized by XRD, N2 adsorption, ICP, FT-IR and DR UV-Vis. Their catalysis on asymmetric epoxidation of several olefins was studied with NaClO and m-CPBA as oxidants respectively. It was found that both the activity and enantioselectivity of the catalysts decreased after the homogeneous catalyst was heterogenized. The reasons resulting in the decrease of catalytic performance were discussed.

  17. 有序介孔二氧化硅对正丁醛的吸附性能%Adsorption Properties of Ordered Mesoporous Silica for Butyraldehyde

    Institute of Scientific and Technical Information of China (English)

    黄天辉; 赵玉娟; 田兆福; 李小兰; 刘茜; 赵东元

    2014-01-01

    Ordered mesoporous silica materials SBA-15, MCM-41, SBA-16, KIT-6 with different pore sizes and properties were prepared. Several SBA-15 materials were synthesized with different pore diameters by changing the hydrothermal temperature. The materials produced were characterized using smal-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and nitrogen adsorption/desorption. The adsorption isotherms of organic aldehyde were measured, using butyraldehyde as a model molecule. The results were compared with those for the adsorption capacity of Y-zeolite;they showed that the specific surface area originating from the mesopores was proportional to the amount of butyraldehyde adsorption. The adsorption isotherms agreed with Langmuir mode for monolayer adsorption. Mesoporous silica MCM-41 with the highest mesopore specific surface area showed the highest adsorbed amount of butyraldehyde (484 mg∙g-1). The SBA-15 sample was selected for the fabrication of cigarette filters, and the results showed that SBA-15 significantly reduced the amount of Croton aldehyde released in cigarette smoke.%合成了一系列具有不同孔结构与性质的有序介孔二氧化硅材料SBA-15、MCM-41、SBA-16、KIT-6,同时通过改变水热温度制备了不同孔径大小的SBA-15,并利用小角X射线散射、透射电镜、扫描电镜和氮气吸附-脱附等手段,对其介孔结构进行了表征。以正丁醛为探针分子,考察了其对有机醛的吸附,并与Y-沸石的吸附性能做了对比。结果表明,材料的介孔比表面积与其对正丁醛的吸附量成正比,吸附等温线符合Langmuir模型,属于单层吸附,具有最大介孔比表面积的MCM-41对正丁醛的吸附量最大(484 mg∙g-1)。最后将SBA-15添加到卷烟滤嘴中,实验结果表明, SBA-15能显著降低卷烟烟气中巴豆醛的释放量。

  18. Cu-MCM-41 nanoparticles: An efficient catalyst for the synthesis of 5-substituted 1-tetrazoles via [3+2] cycloaddition reaction of nitriles and sodium azide

    Indian Academy of Sciences (India)

    Mohammad Abdollahi-Alibeik; Ali Moaddeli

    2016-01-01

    [3+2] cycloaddition reaction of various types of nitriles and sodium azide (NaN3) were studied in the presence of nano-sized Cu-MCM-41 as an efficient recoverable heterogeneous catalyst. Nano-sized Cu-MCM-41 mesoporous molecular sieves with various Si/Cu molar ratios were synthesized by direct insertion of metal ions at room temperature. The textural properties of the materials have been studied by means of XRD, FTIR, SEM and TEM techniques. Catalytic behavior of Cu-MCM-41 was also investigated by pyridine absorption and potentiometric titration. The reactions data verified characterization results and show that Cu-MCM-41 with Si/Cu molar ratio of 20 has considerably better catalytic activity compared to the other molar ratios. To investigate reusability, the catalyst was recovered by simple filtration and reused for several cycles with consistent activity.

  19. Mesoporous Silica Based Gold Catalysts: Novel Synthesis and Application in Catalytic Oxidation of CO and Volatile Organic Compounds (VOCs

    Directory of Open Access Journals (Sweden)

    Leonarda F. Liotta

    2013-10-01

    Full Text Available Gold nanoparticles, particularly with the particle size of 2–5 nm, have attracted increasing research attention during the past decades due to their surprisingly high activity in CO and volatile organic compounds (VOCs oxidation at low temperatures. In particular, CO oxidation below room temperature has been extensively studied on gold nanoparticles supported on several oxides (TiO2, Fe2O3, CeO2, etc.. Recently, mesoporous silica materials (such as SBA-15, MCM-41, MCM-48 and HMS possessing ordered channel structures and suitable pore diameters, large internal surface areas, thermal stabilities and excellent mechanical properties, have been investigated as suitable hosts for gold nanoparticles. In this review we highlight the development of novel mesoporous silica based gold catalysts based on examples, mostly from recently reported results. Several synthesis methods are described herein. In detail we report: the modification of silica with organic functional groups; the one-pot synthesis with the incorporation of both gold and coupling agent containing functionality for the synthesis of mesoporous silica; the use of cationic gold complexes; the synthesis of silica in the presence of gold colloids or the dispersion of gold colloids protected by ligands or polymers onto silica; the modification of silica by other metal oxides; other conventional preparation methods to form mesoporous silica based gold catalysts. The gold based catalysts prepared as such demonstrate good potential for use in oxidation of CO and VOCs at low temperatures. From the wide family of VOCs, the oxidation of methanol and dimethyldisulfide has been addressed in the present review.

  20. Functionalized magnetic mesoporous silica nanoparticles for U removal from low and high pH groundwater.

    Science.gov (United States)

    Li, Dien; Egodawatte, Shani; Kaplan, Daniel I; Larsen, Sarah C; Serkiz, Steven M; Seaman, John C

    2016-11-05

    U(VI) species display limited adsorption onto sediment minerals and synthetic sorbents in pH 8 groundwater. In this work, magnetic mesoporous silica nanoparticles (MMSNs) with magnetite nanoparticle cores were functionalized with various organic molecules using post-synthetic methods. The functionalized MMSNs were characterized using N2 adsorption-desorption isotherms, thermogravimetric analysis (TGA), transmission electron microscopy (TEM), (13)C cross polarization and magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectroscopy, and powder X-ray diffraction (XRD), which indicated that mesoporous silica (MCM-41) particles of 100-200nm formed around a core of magnetic iron oxide, and the functional groups were primarily grafted into the mesopores of ∼3.0nm in size. The functionalized MMSNs were effective for U removal from pH 3.5 and 9.6 artificial groundwater (AGW). Functionalized MMSNs removed U from the pH 3.5 AGW by as much as 6 orders of magnitude more than unfunctionalized nanoparticles or silica and had adsorption capacities as high as 38mg/g. They removed U from the pH 9.6 AGW as much as 4 orders of magnitude greater than silica and 2 orders of magnitude greater than the unfunctionalized nanoparticles with adsorption capacities as high as 133mg/g. These results provide an applied solution for treating U contamination that occurs at extreme pH environments and a scientific foundation for solving critical industrial issues related to environmental stewardship and nuclear power production.

  1. Ecodesign of ordered mesoporous silica materials.

    Science.gov (United States)

    Gérardin, Corine; Reboul, Julien; Bonne, Magali; Lebeau, Bénédicte

    2013-05-07

    Characterized by a regular porosity in terms of pore size and pore network arrangement, ordered mesoporous solids have attracted increasing interest in the last two decades. These materials have been identified as potential candidates for several applications. However, more environmentally friendly and economical synthesis routes of mesoporous silica materials were found to be necessary in order to develop these applications on an industrial scale. Consequently, ecodesign of ordered mesoporous silica has been considerably developed with the objective of optimizing the chemistry and the processing aspects of the material synthesis. In this review, the main strategies developed with this aim are presented and discussed.

  2. Polarity of an MCM-41 adsorbent surface modified with methyl and phenyl groups based on data from gas chromatography

    Science.gov (United States)

    Sukhareva, D. A.; Gus'kov, V. Yu.; Karpov, S. I.; Kudasheva, F. Kh.; Roessner, F.; Borodina, E. V.

    2016-02-01

    The polarity of an MCM-41 adsorbent surface and organosilylated composites based on it with grafted trimethylsilane and dimethylphenylsilane groups is studied via inverse gas chromatography at infinite dilution. The dispersion and specific components of the value proportional to the Helmholtz adsorption energy are calculated, and a comparative analysis of the surface polarity of MCM-41 and its modified analogs relative to the commercially available C-120 silica gel is performed. The electrostatic and donor-acceptor components of the specific Helmholtz adsorption energy are calculated through linear decomposition of the adsorption energy. It is established that MCM-41 is less polar than C-120. The modification of the initial adsorbent surface leads to a reduction in polarity, due mainly to the weakening of induction and orientation interactions. It is concluded that the surfaces of the modified samples retain the ability to form hydrogen bonds.

  3. AND logic-like pH- and light-dual controlled drug delivery by surface modified mesoporous silica nanoparticles.

    Science.gov (United States)

    Zhao, Junwei; He, Zhaoshuai; Li, Biao; Cheng, Tanyu; Liu, Guohua

    2017-04-01

    Recently, the controlled drug delivery system has become a potential platform for biomedical application. Herein, we developed a pH and light-dual controlled cargo release system exhibiting AND logic based on MCM-41 mesoporous silica nanoparticles, which was surface modified using β-cyclodextrin (β-CD) with imine bond and azobenzene derivative. The complex of β-CD and azobenzene derivative effectively blocked the cargo delivery in pH=7.0 phosphate buffered saline (PBS) solution without 365nm UV light irradiation. The cargo was fully released when both factors of acidic environment (pH=5.0 PBS) and 365nm UV light irradiation were satisfied, meanwhile only very little cargo was delivered if one factor was satisfied. The result also demonstrates that the opening/closing of the gate and the release of the cargo in small portions can be controlled. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Ruthenium carbenes supported on mesoporous silicas as highly active and selective hybrid catalysts for olefin metathesis reactions under continuous flow.

    Science.gov (United States)

    Bru, Miriam; Dehn, Richard; Teles, J Henrique; Deuerlein, Stephan; Danz, Manuel; Müller, Imke B; Limbach, Michael

    2013-08-26

    In the search for a highly active and selective heterogenized metathesis catalyst, we systematically varied the pore geometry and size of various silica-based mesoporous (i.e., MCM-41, MCM-48, and SBA-15) and microporous (ZSM-5 and MWW) versus macroporous materials (D11-10 and Aerosil 200), besides other process parameters (temperature, dilution, and mean residence time). The activity and, especially, selectivity of such "linker-free" supports for ruthenium metathesis catalysts were evaluated in the cyclodimerization of cis-cyclooctene to form 1,9-cyclohexadecadiene, a valuable intermediate in the flavor and fragrance industry. The optimized material showed not only exceptionally high selectivity to the valuable product, but also turned out to be a truly heterogeneous catalyst with superior activity relative to the unsupported homogeneous complex.

  5. Adsorption characterization of gaseous volatile organic compound on mesoporous silica particles prepared from spent diatomaceous earth.

    Science.gov (United States)

    Bei, Lei-Lei; Tao, Hong; Ma, Chih-Ming; Shiue, Angus; Chang, Chang-Tang

    2014-04-01

    This study used spent diatomaceous earth (SDE) from drink processing as source of Si and cationic surfactant (CTAB) as a template for the synthesis of mesoporous silica Materials (MSM) through hydrothermal method. The MSM was characterized by Small-angle X-ray Diffraction (SXRD), Scanning Electron Microscopy (SEM), Thermo Gravimetric Analysis (TGA), Fourier Transform Infrared (FT-IR) spectroscopy and N2 adsorption-desorption analyzer. The results showed that the surface area, pore volume and pore size was roughly ranged from 880 to 1060 m2 g(-1), 1.05 cm3 g(-1) and 4.0 nm, respectively. The properties of the synthesized MSM were also compared with those prepared from pure silica sources (MCM-41) and got almost the same characteristics. The synthesized MSM was used as adsorbent at 25 degrees C with carrier gas of air. The adsorption equilibrium revealed that adsorption capacity of MSM was 59.6, 65.7, 69.6, 84.9 mg g(-1) while the acetone concentration was 600, 800, 1000 ppm, 1600 ppm respectively. Results showed that breakthrough curves correlate to the challenge vapor concentration, adsorbent loading, and the flow rate. The results obtained in the present work demonstrated that it was feasibility of using the SDE as a potential source of silica to prepare MSM.

  6. Application of MCM-41 for dyes removal from wastewater.

    Science.gov (United States)

    Lee, Chung-Kung; Liu, Shin-Shou; Juang, Lain-Chuen; Wang, Cheng-Cai; Lin, Kuen-Song; Lyu, Meng-Du

    2007-08-25

    The adsorption of three basic dyes (Rhodamine B (RB), Crystal Violet (CV), and Methylene Green (MG)) and two acid dyes (Acid Red 1 (AR1) and Erioglaucine (EG)) onto MCM-41 was studied to examine the potential of MCM-41 for the removal of dyes from water solution. The revolution of pore structure and surface chemical characteristics of MCM-41 induced by dyes adsorption was characterized based on the analyses of XRD patterns, FTIR spectra, and nitrogen adsorption-desorption isotherms. The adsorption capacity of MCM-41 for the five dyes followed a decreasing order of RB>CV>MG>EG approximately AR1. It was experimentally concluded that if the dyes adsorption did not introduce a serious disorder on the pore structure of MCM-41 (such as RB adsorption), MCM-41 might be a good adsorbent for the removal of basic dyes from water solution. The fitness of both Langmuir and Freundlich adsorption model on describing the equilibrium isotherms of three basic dyes was examined. The suitability of both pseudo-second-order kinetic model and the intraparticle diffusion model for the description of the kinetic data was investigated, from which the adsorption mechanism was examined.

  7. TiO 2-MCM-41的制备表征及选择性吸附脱硫研究%Preparation and Characterization of TiO 2-MCM-41 and Its Performance on the Desulfurization

    Institute of Scientific and Technical Information of China (English)

    尹锋; 秦玉才; 于文宇; 王红; 裴婷婷; 吕莉; 宋丽娟

    2014-01-01

    TiO 2-MCM-41 mesoporous molecular sieve(n (Si)/n (Ti)= 5 )was synthesized by heating reflux method,using titanium tetrabutoxide as the Ti source,MCM-41 as the carrier.The samples were investigated by means of XRD,FT-IR and N2 adsorption/desorption.The static and dynamic desulfurization experiment was carried out using fluid catalytic cracking (FCC)fuel oils.Properties of selective adsorptive desulfurization of FCC gasoline on the adsorbents have been investigated in this paper by a fixed-bed adsorption experiment and a GC-SCD technique.It was indicated thatthe titania homodisperses in the modified MCM-41,titania connected with the pendant OH groups of MCM-41 via Si—O—Ti bonds.After the load of TiO 2 ,the properties of adsorptive desulfurization on the adsorbents weresignificantly improved.The removal selectivities of the sulfur compounds in the gasoline changed slightly before and after the load of TiO 2 ,while the poor removal selectivities of benzothiophene,2/3-methylthiophene,2,3-dimethylthiophene,2,4-dimethylthiophene and 2,5-dimethylthiophene on MCM-41 and TiO 2-MCM-41 were the same.%以钛酸正丁酯作为钛源,MCM-41为载体,采用加热回流法合成了 TiO 2-MCM-41介孔分子筛(n (Si)/n (Ti)=5),并借助 XRD、FT-IR、N2吸附-脱附等表征手段研究了吸附剂的结构特性。以催化裂化汽油为油品进行静态脱硫和动态脱硫实验,结合使用固定床技术和色谱-硫化学发光检测(GC-SCD)偶联技术系统考查了吸附剂的选择性吸附脱硫性能及其对不同硫化物的选择性规律。结果表明,TiO 2在介孔分子筛 MCM-41的内孔壁能均匀分散;TiO 2与 MCM-41孔道表面的 SiO 2以 Si—O—Ti 键连接;MCM-41经负载 TiO 2后,吸附脱硫性能明显提高;TiO 2-MCM-41对 FCC 汽油中各种硫化物的选择性顺序为:四氢噻吩>2-甲基四氢噻吩≈C5硫醚>3,4-二甲基噻吩>2/3-乙基噻吩>2-乙基-5-甲基噻吩>噻吩>2,5-二甲基噻吩>C1-C3硫醇>2-甲基噻吩>2,3-

  8. Confinement of a bioinspired nonheme Fe(II) complex in 2D hexagonal mesoporous silica with metal site isolation.

    Science.gov (United States)

    Jollet, Véronique; Albela, Belén; Sénéchal-David, Katell; Jégou, Pascale; Kolodziej, Emilie; Sainton, Joëlle; Bonneviot, Laurent; Banse, Frédéric

    2013-08-28

    A mixed amine pyridine polydentate Fe(II) complex was covalently tethered in hexagonal mesoporous silica of the MCM-41 type. Metal site isolation was generated using adsorbed tetramethylammonium cations acting as a patterned silanol protecting mask and trimethylsilylazane as a capping agent. Then, the amine/pyridine ligand bearing a tethering triethoxysilane group was either grafted to such a pretreated silica surface prior to or after complexation to Fe(II). These two synthetic routes, denoted as two-step and one-step, respectively, were also applied to fumed silica for comparison, except that the silanol groups were capped after tethering the metal unit. The coordination of the targeted complex was monitored using UV-visible spectrophotometry and, according to XPS, the best control was achieved inside the channels of the mesoporous silica for the two-step route. For the solid prepared according to the one-step route, tethering of the complex occurred mainly at the entrance of the channel.

  9. Nanostructured Mesoporous Silicas for Bone Tissue Regeneration

    Directory of Open Access Journals (Sweden)

    Isabel Izquierdo-Barba

    2008-01-01

    Full Text Available The research on the development of new biomaterials that promote bone tissue regeneration is receiving great interest by the biomedical scientific community. Recent advances in nanotechnology have allowed the design of materials with nanostructure similar to that of natural bone. These materials can promote new bone formation by inducing the formation of nanocrystalline apatites analogous to the mineral phase of natural bone onto their surfaces, i.e. they are bioactive. They also stimulate osteoblast proliferation and differentiation and, therefore, accelerate the healing processes. Silica-based ordered mesoporous materials are excellent candidates to be used as third generation bioceramics that enable the adsorption and local control release of biological active agents that promote bone regeneration. This local delivery capability together with the bioactive behavior of mesoporous silicas opens up promising expectations in the bioclinical field. In this review, the last advances in nanochemistry aimed at designing and tailoring the chemical and textural properties of mesoporous silicas for biomedical applications are described. The recent developed strategies to synthesize bioactive glasses with ordered mesopore arrangements are also summarized. Finally, a deep discussion about the influence of the textural parameters and organic modification of mesoporous silicas on molecules adsorption and controlled release is performed.

  10. Functionalized silica materials for electrocatalysis

    Indian Academy of Sciences (India)

    Vellaichamy Ganesan

    2015-02-01

    Electrocatalysis is an important phenomenon which is utilized in metal–air batteries, fuel cells, electrochemical sensors, etc. To increase the efficiency of the electrocatalytic process and to increase the electrochemical accessibility of the immobilized electrocatalysts, functionalized and non-functionalized mesoporous organo-silica (MCM41-type-materials) are used in this study. These materials possess several suitable properties to be durable catalysts and/or catalyst supports. Owing to the uniform dispersion of electrocatalysts (metal complex and/or metal nanoparticles (NPs)) on the functionalized and non-functionalized silica, an enormous increase in the redox current is observed. Long range channels of silica materials with pore diameter of 15–100 Å allowed metal NPs to accommodate in a specified manner in addition to other catalysts. The usefulness of MCM-41-type silica in increasing the efficiency of electrocatalysisis demonstrated by selecting oxygen, carbon dioxide and nitrite reduction reactions as examples

  11. Xinjiang Bentonite Modiifcation and Preparation of MCM-41%新疆膨润土改性及MCM-41的制备研究

    Institute of Scientific and Technical Information of China (English)

    赵越; 贾汉忠; 汪立今; 陈红霞

    2015-01-01

    In this study, bentonite from Xinjiang Province was used as silicate and acuminate sources to mix with sodium hydroxide by adopting an alkaline fusion process to extract both silicon and aluminum which are main components in bentonite. We carried out the synthesis of MCM-41 from bentonite using the supernatants which are in the form of sodium silicate and sodium aluminates and then accommodate pH value for 7.5, 8.5, 9.5, 10.5 by adding sixteen alkyl three methyl bromide and hydrothermal temperature at 80℃,100℃120℃,140℃by the hydrothermal method separately, calcinations’ temperature were 450℃, 550℃, 650℃, 750℃respectively. Compared with the experimental conditions for synthesis of MCM-41, we synthesized mesoporous molecular sieve MCM-41 from bentonite. On the basis of the data obtained from powder X-ray diffraction (XRD), fourier transforms infrared spectroscopy and N2 adsorption and desorption, we analyzed stability of materials.%以新疆某地钠基膨润土为原料,通过膨润土与氢氧化钠混合,经过碱溶处理,提取出膨润土中的主要成分Si和Al,生成硅酸钠和偏铝酸钠,加入十六烷基三甲基溴化铵,调节pH值分别为7.5、8.5、9.5、10.5,水热温度分别为80℃、100℃、120℃、140℃,高温煅烧温度分别为450℃、550℃、650℃、750℃,通过对比分析得出最合适的制备条件,成功制备出介孔分子筛MCM-41,并运用X射线衍射,傅里叶红外光谱,N2吸附-脱附等手段对材料进行表征,分析材料的稳定性。

  12. Preparation and structure characterization of nanospherical MCM- 41 molecular sieves

    Directory of Open Access Journals (Sweden)

    CHEN Ting

    2013-04-01

    Full Text Available Nanospherical MCM-41 molecular sieves have been synthesized by using hexadecyl trimethyl ammonium bromide (CTAB as templates and tetraethyl orthosilicate (TEOS as silicon sources. XRD,SEM,FT-IR,TEM,and N2 adsorption-desorption isotherms were used to investigate the effects of the reaction temperature and aging time on the morphology and structure of the samples. The results show that the nanospherical MCM-41 particles can be obtained at reaction temperatures between 20 to 80℃. With the reaction temperature increasing,the diameter of the nanospheres increases. When the reaction temperature reaches 110℃,MCM-41 molecular sieves exhibit irregular particle morphology. With the aging time of 0-15 h,the dispersion of nanospherical MCM-41 molecular sieves is very good. However,as the aging time increases,the particle size is also increased,while agglomeration is also more serious. Besides,the optimal synthesis conditions of the nanospherical MCM-41 molecular sieves were obtained by analyzing their formation mechanism.

  13. Synthesis and Characterization of Ce-Containing MCM-41

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ SUMMARY. The cerium-containing MCM-41 (Ce-MCM-41) has been synthesized with size in the micrometer range by direct hydrothermal method. Transmission electron microscopy shows the regular hexagonal array of uniform channel characteristics of MCM-41. Five peaks were detected in the lov-angle XRD patterns,an interplanar spacing d100 = 40.6 A was obtained that can be indexed on a hexagonal unit cell with a0 = 46.9 A. Nitrogen adsorption isotherm at 77 K revealed a surface area of 920 m2/g, pore size of 26.2 A and wall thickness of 18.1 A. A cell contraction of 2.6 A upon calcination was observed. The spectroscopic studies indicate that the synthesized sample is with MCM-41 structure and Ce is in the framework position. A weak Lewis acidity was indicated by infrared spectra of pyridine adsorption. The synthesized Ce-MCM-41 exhibits fairly catalytic activity for the NO reduction by CO.

  14. Synthesis and Characterization of Ce-Containing MCM-41

    Institute of Scientific and Technical Information of China (English)

    CHIEN; ShuHua

    2001-01-01

    SUMMARY.  The cerium-containing MCM-41 (Ce-MCM-41) has been synthesized with size in the micrometer range by direct hydrothermal method. Transmission electron microscopy shows the regular hexagonal array of uniform channel characteristics of MCM-41. Five peaks were detected in the lov-angle XRD patterns,an interplanar spacing d100 = 40.6 A was obtained that can be indexed on a hexagonal unit cell with a0 = 46.9 A. Nitrogen adsorption isotherm at 77 K revealed a surface area of 920 m2/g, pore size of 26.2 A and wall thickness of 18.1 A. A cell contraction of 2.6 A upon calcination was observed. The spectroscopic studies indicate that the synthesized sample is with MCM-41 structure and Ce is in the framework position. A weak Lewis acidity was indicated by infrared spectra of pyridine adsorption. The synthesized Ce-MCM-41 exhibits fairly catalytic activity for the NO reduction by CO.  ……

  15. Magnetic behavior of iron-modified MCM-41 correlated with clustering processes from the wet impregnation method

    Energy Technology Data Exchange (ETDEWEB)

    Cuello, Natalia I.; Elías, Verónica R. [Centro de Investigación y Tecnología Química (CITeQ) (UTN-CONICET), Facultad Regional Córdoba. Maestro López y Cruz Roja Argentina, Ciudad Universitaria, Córdoba 5016 (Argentina); Winkler, Elin [Centro Atómico Bariloche, Comisión Nacional de Energía Atómica – CONICET, Avenue Bustillo 9500, San Carlos de Bariloche 8400 (Argentina); Pozo-López, Gabriela; Oliva, Marcos I. [Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba – IFEG, CONICET, Ciudad Universitaria, Córdoba 5000 (Argentina); Eimer, Griselda A., E-mail: geimer@frc.utn.edu.ar [Centro de Investigación y Tecnología Química (CITeQ) (UTN-CONICET), Facultad Regional Córdoba. Maestro López y Cruz Roja Argentina, Ciudad Universitaria, Córdoba 5016 (Argentina)

    2016-06-01

    Magnetic MCM-41 type mesoporous silica materials were synthetized and modified with different iron loadings by the wet impregnation method. The evolution of iron speciation, depending on the metal loading and associated with a particular magnetic behavior was investigated by M vs. H curves, FC–ZFC curves, EPR spectroscopy and other complementary techniques such as SEM, TEM, and chemisorption of pyridine followed by FT-IR studies. A superparamagnetic contribution was larger for the lower loadings suggesting the high dispersion of very small sized iron nanospecies. However, this contribution decreased with increasing metal loading due to the growth of magnetically blocked nanoparticles (hematite) on the outer surface. Finally, a bimodal size distribution for the superparamagnetic nanospecies could be inferred; then the anisotropy constant for this phase and the corresponding nanospecies sizes were estimated. - Highlights: • All samples showed a main superparamagnetic contribution. • The oxide particles grow at expense of superparamagnetic nanospecies. • Bimodal distribution of nanospecies in superparamagnetic regime was determined. • The anisotropy constant for superparamagnetic nanospecies was calculated.

  16. Mesoporous Silica from Rice Husk Ash

    Directory of Open Access Journals (Sweden)

    V.R. Shelke

    2011-01-01

    Full Text Available Mesoporous silica is used as a raw material in several areas: in preparation of catalysts, in inks, as a concrete hardening accelerator, as a component of detergents and soaps, as a refractory constituent etc. Sodium silicate is produced by reacting rice hull ash (RHA with aqueous NaOH and silica is precipitated from the sodium silicate by acidification. In the present work, conversion of about 90% of silica contained in RHA into sodium silicate was achieved in an open system at temperatures of about 100 °C. The results showed that silica obtained from RHA is mesoporous, has a large surface area and small particle size. Rice Husk is usually mixed with coal and this mixture is used for firing boilers. The RHA therefore, usually contains carbon particles. Activated carbon embedded on silica has been prepared using the carbon already present in RHA. This carbon shows good adsorption capacity. ©2010 BCREC UNDIP. All rights reserved(Received: 25th April 2010, Revised: 17th June 2010, Accepted: 24th June 2010[How to Cite: V.R. Shelke, S.S. Bhagade, S.A. Mandavgane. (2010. Mesoporous Silica from Rice Husk Ash. Bulletin of Chemical Reaction Engineering and Catalysis, 5 (2: 63-67. doi:10.9767/bcrec.5.2.793.63-67][DOI: http://dx.doi.org/10.9767/bcrec.5.2.793.63-67

  17. Supra-amphiphilic transparent mesoporous silica coating

    Institute of Scientific and Technical Information of China (English)

    MA Jin; YANG Zhenglong; QU Xiaozhong; YANG Zhenzhong

    2006-01-01

    Transparent mesoporous silica coatings were achieved by conventional sol-gel process. The obtained coatings display permanent supraamphiphilicity, transparent appearance and good wetting property with very fast spread rate. Incorporation of functional materials such as crystalline titania nanoparticles into the coatings was also carried out without affecting the transparency and supraamphiphilicity.

  18. Electrochemical Properties of MCM-41 Supported Co3O4Composites as Supercapacitor Electrode Materials%MCM-41负载Co3O4复合超电容电极材料的电化学性能

    Institute of Scientific and Technical Information of China (English)

    王露; 刘孝恒; 汪信

    2012-01-01

    impregnating the cobalt nitrate Co( NO3 )2 H6O into the pore channels of mesoporous silica MCM-41 and then calcining the obtained precursors,the Co3O4/MCM-41-x(x is the mass ratio of cobaltic-cobattous oxide Co3O4 to MCM-41) series composites are made. The X-ray diffraction, the transmission electron microscopy, the N2 adsorption-desorption and the cyclic voltammetry and AC impedance spectroscopy are used to survey the chemical compositions, the structural characteristics and the electrochemical properties of titled materials. The results disclose that the specific surface areas and the pore volumes of materials are 280 ~ 440 m2/g and 0. 22 - 0. 34 cm3/g respectively. The loading of Co3O4,the sweep rate and the electrolyte concentration have significant influences on the electrochemical performances of the composites materials. When x is 1. 6,the sweep rate is 3 mV/s,the specific capacitance of the material is 308 F/g and the electrode solution is 6 mol/L KOH, the retention rate of the specific capacitance is 91. 3% after 500 continuous cycles.%采用灌注法将硝酸钴Co( NO3)2·6H2O负载到介孔氧化硅MCM-41孔道内,经煅烧得到Co3O4/MCM-41-x(x表示四氧化钴Co3O4与MCM-41的质量比)复合材料.利用X射线衍射、透射电子显微镜、N2吸附-脱附、循环伏安和交流阻抗技术研究了材料的化学组成、结构特征及电化学性能.结果表明,该材料的比表面积为280~440 m2/g,孔体积为0.22~0.34 cm3/g.Co3O4的负载量、扫描速率以及电解液浓度对材料的电化学性能均有显著影响.当x=1.6、扫描速率为3 mV/s、电解液为6 mol/L KOH溶液时,材料比电容高达308 F/g,500次循环测试后比电容保留率为91.3%.

  19. Dehidroisomerización de n-butano sobre catalizadores bifuncionales tipo Al-MCM-41 y Ga-MCM-41 impregnados con Pt o Ga

    Directory of Open Access Journals (Sweden)

    Dino Brisigotti

    2006-05-01

    Full Text Available A series of bi-functional catalysts was prepared by using Al-MCM-41 and Ga-MCM-41 with Si/Me ratios of 15 and 50 impregnated with 0,5 Wt% of Pt or Ga. The n-butane dehydroisomerization was studied at 773 K. Catalysts based on Pt/Al-MCM-41 were less selective (more hydrogenolyzing than those based on Ga-MCM-41. For the latter, Ga species segregated to extra-framework positions might exercise a kind of geometric effect on the Pt clusters inhibiting hydrogenolysis. The catalyst Ga/Al-MCM-41 showed the closest approach to the ideal dehydroisomerization catalyst.

  20. Ag(Ⅰ) Schiff碱配合物改性MCM-41分子筛的制备和表征%PREPARATION AND CHARACTERIZATION OF Ag(Ⅰ) SCHIFF BASE COMPLEX MODIFIED MCM?41 MOLECULAR SIEVES

    Institute of Scientific and Technical Information of China (English)

    康文彬; 喻龙宝; 黄竹谋; 施亚玉

    2010-01-01

    以3-氨丙基三乙氧基硅烷(3-aminopropyltriethoxysilane,APS)为偶联剂,用共缩聚的方法合成了氨基官能化的MCM-41介孔分子筛(amino-functionalized mesoporous MCM-41,AP-MCM-41),在分子筛孔道和表面共价偶联Ag(Ⅰ) Schiff碱配合物.采用X射线衍射、Fourier红外光谱、紫外-可见光谱、氮气吸附/脱附、元素分析和透射电子显微镜对得到的样品进行了表征.结果表明:Ag(Ⅰ) Schiff 碱配合物被成功嫁接到了分子筛的孔道和表面上,而且嫁接后的MCM-41仍然具有较好的孔径分布和有序结构,比表面积达到712.59 m~2/g,最可几孔径为3.41 nm,具有典型的介孔材料特征.透射电子显微镜观察显示具有明显的孔道结构,并且较为规整.紫外-可见光谱显示,金属配位后,样品的相应的归属峰发生了明显的漂移,说明Ag(Ⅰ) Schiff碱配合物已嫁接到了MCM-41表面并形成牢固的结构.

  1. Recycling of plastic materials employing zeolite and MCM-41 materials

    OpenAIRE

    Ortega, D.; L. Noreña; Aguilar, J; I. Hernández; Ramírez, V.

    2006-01-01

    We report on the catalytic and the thermal decomposition of low density polyethylene resulting in several fuel products (LP gas, gasoline, gas oil). We built a continuos, fixed-bed reaction system. We employed Ga-MCM-41, Al-MCM-41, commercial FCC Y zeolite (fresh and equilibrium) and natural mordenite as catalysts. We set the following reaction conditions: 450 °C reaction temperature, constant feed flow and 30 min reaction time at atmospheric pressure. We analyzed the gas and liquid products ...

  2. Studies on the Surface Properties of MCM-41

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    MCM-41 materials with a well-ordered long-range structure, a large pore size and a high surface area have been synthesized. Their surface properties including the number and the nature of the surface hydroxyl groups and surface hydrophobicity/hydrophilicity have been investigated by means of 29Si MAS NMR and FT-IR spectra and TPD of probe molecules. The results clearly show that the surface of MCM-41 has an abundance of acidic silanol groups, and that the hydrophobicity/hydrophilicity can be modified by the introduction of Al and transition metals Ti, Cr, Ni and Fe into it.

  3. SYNTHESIS AND COATING OF ORDERED MESOPOROUS SILICA

    Institute of Scientific and Technical Information of China (English)

    Wei Guo; Guangsheng Luo; Yujun Wang

    2003-01-01

    1,3,5-trimethyl benzene (TMB) was used as organic swelling agent in O/W emulsions to template ultra-large mesoporous materials using the hydrothermal method. The silicas with well-defined mesopores and hydrothermally robust framework were characterized by X-ray diffraction, transmission electron microscopy and BET surface area analysis. The influence of the quantity of TMB during preparation was studied. It has been found that the TMB/CTAB ratio must be controlled for producing high pore volume materials. Polysulfone (PSU), as the usual extraction agent, was coated on the silicas with the solvent evaporation method to produce a solid separation medium. The adsorptivity and the surface area of the coated MCM were determined: 10% PSU coated MCM adsorbed twice as much phenol as the uncoated material, reaching 0.5 mg/g silica. It was found that the surface area of the coated material decreased rapidly with an increase of the PSU loading.

  4. Active Iron Sites of Disordered Mesoporous Silica Catalyst FeKIL-2 in the Oxidation of Volatile Organic Compounds (VOC

    Directory of Open Access Journals (Sweden)

    Mojca Rangus

    2014-05-01

    Full Text Available Iron-functionalized disordered mesoporous silica (FeKIL-2 is a promising, environmentally friendly, cost-effective and highly efficient catalyst for the elimination of volatile organic compounds (VOCs from polluted air via catalytic oxidation. In this study, we investigated the type of catalytically active iron sites for different iron concentrations in FeKIL-2 catalysts using advanced characterization of the local environment of iron atoms by a combination of X-ray Absorption Spectroscopy Techniques (XANES, EXAFS and Atomic-Resolution Scanning Transmission Electron Microscopy (AR STEM. We found that the molar ratio Fe/Si ≤ 0.01 leads to the formation of stable, mostly isolated Fe3+ sites in the silica matrix, while higher iron content Fe/Si > 0.01 leads to the formation of oligonuclear iron clusters. STEM imaging and EELS techniques confirmed the existence of these clusters. Their size ranges from one to a few nanometers, and they are unevenly distributed throughout the material. The size of the clusters was also found to be similar, regardless of the nominal concentration of iron (Fe/Si = 0.02 and Fe/Si = 0.05. From the results obtained from sample characterization and model catalytic tests, we established that the enhanced activity of FeKIL-2 with the optimal Fe/Si = 0.01 ratio can be attributed to: (1 the optimal concentration of stable isolated Fe3+ in the silica support; and (2 accelerated diffusion of the reactants in disordered mesoporous silica (FeKIL-2 when compared to ordered mesoporous silica materials (FeSBA-15, FeMCM-41.

  5. Basic Functionalization of Hexagonal Mesoporous Silica

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    3-Aminopropyltricthoxysilanc (AM), 3-cthyldiaminopropyltrimcthoxysilane (ED) and 3-piperazinylpropyltriethoxysilanc (PZ), were used to chemically couple with the silanol groups of calcined hexagonal and hexagonal-like mesoporous silica SBA-3 and HMS, respectively, to produce functionalised alkaline mesoporous materials. The inerease in the dosage of organosilanes, or in reaction temperature, or in the humidity (i.e., water content) of support, is favorable to the grafting of functional molecules on the surface. When functionalization conditions are the same, the order of loadings on SBA-3 and DDA-HMS is ED>AM>PZ. However, on ODA-HMS, the loading of AM is similar to that of ED.

  6. Mesoporous silica nanoparticles for intracellular delivery of membrane-impermeable proteins.

    Science.gov (United States)

    Slowing, Igor I; Trewyn, Brian G; Lin, Victor S-Y

    2007-07-18

    An MCM-41-type mesoporous silica nanoparticle (MSN) material with a large average pore diameter (5.4 nm) is synthesized and characterized. The in vitro uptake and release profiles of cytochrome c by the MSN were investigated. The enzymatic activity of the released protein was quantitatively analyzed and compared with that of the native cytochrome c in physiological buffer solutions. We found that the enzymes released from the MSNs are still functional and highly active in catalyzing the oxidation of 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) by hydrogen peroxide. In contrast to the fact that cytochrome c is a cell-membrane-impermeable protein, we discovered that the cytochrome c-encapsulated MSNs could be internalized by live human cervical cancer cells (HeLa) and the protein could be released into the cytoplasm. We envision that these MSNs with large pores could serve as a transmembrane delivery vehicle for controlled release of membrane-impermeable proteins in live cells, which may lead to many important biotechnological applications including therapeutics and metabolic manipulation of cells.

  7. Diffusion energy profiles in silica mesoporous molecular sieves modelled with the fragment molecular orbital method

    Science.gov (United States)

    Roskop, Luke; Fedorov, Dmitri G.; Gordon, Mark S.

    2013-07-01

    The fragment molecular orbital (FMO) method is used to model truncated portions of mesoporous silica nanoparticle (MSN) pores. The application of the FMO/RHF (restricted Hartree-Fock) method to MCM-41 type MSNs is discussed and an error analysis is given. The FMO/RHF method is shown to reliably approximate the RHF energy (error ∼0.2 kcal/mol), dipole moment (error ∼0.2 debye) and energy gradient (root mean square [RMS] error ∼0.2 × 10-3 a.u./bohr). Several FMO fragmentation schemes are employed to provide guidance for future applications to MSN models. An MSN pore model is functionalised with (phenyl)propyl substituents and the diffusion barrier for benzene passing through the pore is computed by the FMO/RHF-D method with the Grimme dispersion correction (RHF-D). For the reaction coordinates examined here, the maximum FMO/RHF-D interaction energies range from -0.3 to -5.8 kcal/mol.

  8. Effects of pore topology and iron oxide core on doxorubicin loading and release from mesoporous silica nanoparticles

    Science.gov (United States)

    Ronhovde, Cicily J.; Baer, John; Larsen, Sarah C.

    2017-06-01

    Mesoporous silica nanoparticles (MSNs) have a network of pores that give rise to extremely high specific surface areas, making them attractive materials for applications such as adsorption and drug delivery. The pore topology can be readily tuned to achieve a variety of structures such as the hexagonally ordered Mobil Crystalline Material 41 (MCM-41) and the disordered "wormhole" (WO) mesoporous silica (MS) structure. In this work, the effects of pore topology and iron oxide core on doxorubicin loading and release were investigated using MSNs with pore diameters of approximately 3 nm and sub-100 nm particle diameters. The nanoparticles were loaded with doxorubicin, and the drug release into phosphate-buffered saline (PBS, 10 mM, pH 7.4) at 37 °C was monitored by fluorescence spectroscopy. The release profiles were fit using the Peppas model. The results indicated diffusion-controlled release for all samples. Statistically significant differences were observed in the kinetic host-guest parameters for each sample due to the different pore topologies and the inclusion of an iron oxide core. Applying a static magnetic field to the iron oxide core WO-MS shell materials did not have a significant impact on the doxorubicin release. This is the first time that the effects of pore topology and iron oxide core have been isolated from pore diameter and particle size for these materials.

  9. Mesoporous silica nanoparticles for active corrosion protection.

    Science.gov (United States)

    Borisova, Dimitriya; Möhwald, Helmuth; Shchukin, Dmitry G

    2011-03-22

    This work presents the synthesis of monodisperse, mesoporous silica nanoparticles and their application as nanocontainers loaded with corrosion inhibitor (1H-benzotriazole (BTA)) and embedded in hybrid SiOx/ZrOx sol-gel coating for the corrosion protection of aluminum alloy. The developed porous system of mechanically stable silica nanoparticles exhibits high surface area (∼1000 m2·g(-1)), narrow pore size distribution (d∼3 nm), and large pore volume (∼1 mL·g(-1)). As a result, a sufficiently high uptake and storage of the corrosion inhibitor in the mesoporous nanocontainers was achieved. The successful embedding and homogeneous distribution of the BTA-loaded monodisperse silica nanocontainers in the passive anticorrosive SiOx/ZrOx film improve the wet corrosion resistance of the aluminum alloy AA2024 in 0.1 M sodium chloride solution. The enhanced corrosion protection of this newly developed active system in comparison to the passive sol-gel coating was observed during a simulated corrosion process by the scanning vibrating electrode technique (SVET). These results, as well as the controlled pH-dependent release of BTA from the mesoporous silica nanocontainers without additional polyelectrolyte shell, suggest an inhibitor release triggered by the corrosion process leading to a self-healing effect.

  10. CATALYTIC PROPERTIES AND ACIDITY OF MODIFIED MCM-41 ...

    African Journals Online (AJOL)

    a

    Catalytic tests. The catalysis ... Acidity study. The acid properties of MCM-41 materials were studied in situ by pyridine adsorption in a ... showed on one hand that the values of the acid strength were similar to those founded by pyridine .... Considering the data represented in Figures 5a and 5b, it is possible to infer that.

  11. Preparation of TiO2 Nanoparticle Loaded MCM-41 and Study of Its Photo-Catalytic Activity Towards Decolorization of Methyl Orange.

    Science.gov (United States)

    Naik, Bhanudas; Hazra, Subhenjit; Dayananda, Desagani; Prasad, V S; Ghosh, Narendra Nath

    2015-09-01

    Here we report the synthesis of TiO2 nanoparticle loaded mesoporous MCM-41 photocatalysts for degradation of methyl orange dye in aqueous medium under sunlight exposure. TiO2 loaded MCM-41 was synthesized by impregnation method. Anatase form of TiO2 nanoparticles were formed in the porous matrix of the silicate MCM-41. The synthesized materials were characterized using powder X-ray diffraction method, surface area and porosimetry analysis; diffuse reflectance analysis, particle size analysis and transmission electron microscopy. The photocatalytic property of the synthesized materials were investigated towards the degradation of methyl orange under sunlight exposure and monitored by UV-visible spectrophotometer. Synthesized catalysts showed high photocatalytic activity for the degradation of methyl orange.

  12. Photocatalytic Degradation of Methyl Thionine Chloride in Aqueous Solution over Nanometer ( CdS/TiO2 )/MCM-41

    Institute of Scientific and Technical Information of China (English)

    XUE Hanling; LI Jianwei; GE Lingmei

    2006-01-01

    ( CdS / TiO2 )/MCM-41 loaded nanometer photocatalyst was prepared by the sol-gel method and dipping process, the photocatalytic degradation of methyl thionine chloride in water was investigated by using the photocatalyst. The experimental results show that the optimum concentration of CdS over TiO2 was 3% ( molar ratio ), the photocatalytic activity was enhanced when making TiO2 the anatase phase with a rise of the roasting temperature, and the carrier, mesoporous molecular sieve MCM- 41, was beneficial to improving the photocatalytic activity of TiO2 for photocatalytic degradation of methyl thionine chloride. The morphology and the crystalline phase of the photocatalyst were discussed by means of XRD and SEM techniques, and the reaction mechanism of catalytic properties was also discussed.

  13. Study on the fluorescence and thermal stability of hybrid materials Eu(Phen)2Cl3/MCM-41

    Institute of Scientific and Technical Information of China (English)

    Liangzhun YANG; Lanfen ZHANG; Jun CHEN; Liwen REN; Yanting ZHU; Xiuying WANG; Xibin YU

    2009-01-01

    A series of luminescent hybrid materials Eu (Phen)2Cl3/MCM-41 that the different assembled mass of Eu(Phen)2Cl3 included into the channels of MCM , have been synthesized by combining ultrasound technology. The properties of the hybrid materials were characterized by XRD(X-ray Diffraction), N2-adsorption-desorption, FT-IR and luminescence spectrum. The results show that the rare-earth compounds had been loaded into the holes of mesoporous material MCM-41. The luminescence intensities of the hybrid materials were improved as the increase of the loading concentration of the rare-earth complexes. The hybrid material has the maximal luminescence intensity when it reached the saturated loading concentration (7.17%). To compare with the pure rare-earth complex, the thermal stability of the hybrid materials were enhanced by about 100°C.

  14. Supramolecular-templated synthesis of mesoporous silica-zirconia nanocomposite

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Mesoporous SiO2-ZrO2 nanocomposite was successfully prepared by using supramolecular triblock copolymer as the template through evaporation-induced self-assembly approach. The textural and structural properties were characterized by X-ray diffraction, nitrogen adsorption analysis, and transmission electron microscope.Comparison between pure mesoporous silica and mesoporous silica-zirconia nanocomposite was also presented in this work. The surface area, pore size, and pore volume decreased as the Zr doping in the mesoporous silica framework. But the obtained nanocomposite maintained the cubic Im3m-type mesoporous structure.

  15. 胺基修饰的介孔二氧化硅选择性降低卷烟烟气中的氢氰酸%Selectively Reducing HCN Delivery in Mainstream Cigarette Smoke with Amino-functionalized Mesoporous Silica Materials

    Institute of Scientific and Technical Information of China (English)

    周宛虹; 孙文梁; 王律; 周懿华; 王源; 高汉华

    2013-01-01

    In order to selectively reduce the delivery of HCN in mainstream cigarette smoke, an amino-functionalized mesoporous silica material (MCM-41-NH2) was prepared and characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), specific surface area and pore size analyzer (BET) and "C solid-state nuclear magnetic resonance (NMR), then the prepared material was applied to cigarette filter to reduce the deliveries of harmful components in cigarette smoke. The results showed that: 1) Comparing with MCM-41 material, the crystal form of MCM-41-NH2 did not change significantly, however its pore size and specific surface area were reduced by 50%. 2) When MCM-41-NH2 material was added into cigarette filter, up to 25.7% of HCN in mainstream cigarette smoke was selectively reduced, while the physical parameters of cigarette and the deliveries of routine smoke components were basically the same as those of reference cigarette.%为选择性降低卷烟主流烟气中氢氰酸(HCN)的释放量,制备了一种胺基功能化的介孔二氧化硅材料(MCM-41-NH2),运用扫描电镜(SEM)、X-射线衍射(XRD)、比表面积孔径分析(BET)以及13C固体核磁共振谱(”C-NMR)对材料进行了表征,并将材料添加于卷烟滤嘴进行了烟气减害测试.结果表明:①与MCM-41材料相比,MCM-41-NH2的晶型无明显改变,但孔径和比表面积下降了50%.②该材料对卷烟主流烟气中HCN的选择性降低率达到25.7%,而烟支物理参数及烟气常规成分释放量与对照卷烟基本一致.

  16. Simultaneous extraction and preconcentration of uranium and thorium in aqueous samples by new modified mesoporous silica prior to inductively coupled plasma optical emission spectrometry determination.

    Science.gov (United States)

    Yousefi, Seyed Reza; Ahmadi, Seyed Javad; Shemirani, Farzaneh; Jamali, Mohammad Reza; Salavati-Niasari, Masoud

    2009-11-15

    A new synthesized modified mesoporous silica (MCM-41) using 5-nitro-2-furaldehyde (fural) was applied as an effective sorbent for the solid phase extraction of uranium(VI) and thorium(IV) ions from aqueous solution for the measurement by inductively coupled plasma optical emission spectrometry (ICP OES). The influences of some analytical parameters on the quantitative recoveries of the analyte ions were investigated in batch method. Under optimal conditions, the analyte ions were sorbed by the sorbent at pH 5.5 and then eluted with 1.0 mL of 1.0 mol L(-1) HNO(3). The preconcentration factor was 100 for a 100mL sample volume. The limits of detection (LOD) obtained for uranium(VI) and thorium(IV) were 0.3 microg L(-1). The maximum sorption capacity of the modified MCM-41 was found to be 47 and 49 mg g(-1) for uranium(VI) and thorium(IV), respectively. The sorbent exhibited good stability, reusability, high adsorption capacity and fast rate of equilibrium for sorption/desorption of uranium and thorium ions. The applicability of the synthesized sorbent was examined using CRM and real water samples.

  17. Electrical Relaxation in ULTEM® and ULTEM® Containing Mesoporous Silica

    Science.gov (United States)

    Turo, Andrew; Edmondson, Charles E.; Lomax, Joseph F.; Bendler, John T.; Fontanella, John J.; Wintersgill, Mary C.

    2008-08-01

    Mesoporous silica has been added to Ultem® 1000 polyetherimide using solution casting. The mesoporous silica that was added was either uncoated or coated with polystyrene. Audio frequency dielectric relaxation studies were then carried out over the temperature range 5.5 to 550 K. Several interesting results were obtained. First, the uncoated mesoporous silica caused essentially no change in the relaxation spectrum of pure Ultem®. The polystyrene coated mesoporous silica caused rather large changes. The most striking example is the introduction of a new relaxation. This relaxation occurs at about 150 K and 1000 Hz as showing in fig. 1 via the open circles.

  18. Pore Size Effect on Methane Adsorption in Mesoporous Silica Materials Studied by Small-Angle Neutron Scattering.

    Science.gov (United States)

    Chiang, Wei-Shan; Fratini, Emiliano; Baglioni, Piero; Chen, Jin-Hong; Liu, Yun

    2016-09-06

    Methane adsorption in model mesoporous silica materials with the size range characteristic of shale is studied by small-angle neutron scattering (SANS). Size effect on the temperature-dependent gas adsorption at methane pressure about 100 kPa is investigated by SANS using MCM-41 and SBA-15 as adsorbents. Above the gas-liquid condensation temperature, the thickness of the adsorption layer is found to be roughly constant as a function of the temperature. Moreover, the gas adsorption properties, such as the adsorbed layer thickness and the specific amount of adsorbed gas, have little dependence on the pore size being studied, i.e., pore radius of 16.5 and 34.1 Å, but are mainly affected by the roughness of the pore surfaces. Hence, the surface properties of the pore wall are more dominant than the pore size in determining the methane gas adsorption of pores at the nanometer size range. Not surprisingly, the gas-liquid condensation temperature is observed to be sensitive to pore size and shifts to higher temperature when the pore size is smaller. Below the gas-liquid condensation temperature, even though the majority of gas adsorption experiments/simulations have assumed the density of confined liquid to be the same as the bulk density, the measured methane mass density in our samples is found to be appreciably smaller than the bulk methane density regardless of the pore sizes studied here. The mass density of liquid/solid methane in pores with different sizes shows different temperature dependence below the condensation temperature. With decreasing temperature, the methane density in larger pores (SBA-15) abruptly increases at approximately 65 K and then plateaus. In contrast, the density in smaller pores (MCM-41) monotonically increases with decreasing temperature before reaching a plateau at approximately 30 K.

  19. Synthesis, characterization and magnetic behavior of Co/MCM-41 nano-composites

    Energy Technology Data Exchange (ETDEWEB)

    Cuello, N. [CITeQ-Universidad Tecnológica Nacional-Facultad Regional Córdoba, Maestro López esq. Cruz Roja Argentina, 5016 Córdoba (Argentina); Elías, V. [CITeQ-Universidad Tecnológica Nacional-Facultad Regional Córdoba, Maestro López esq. Cruz Roja Argentina, 5016 Córdoba (Argentina); CONICET (Argentina); Crivello, M. [CITeQ-Universidad Tecnológica Nacional-Facultad Regional Córdoba, Maestro López esq. Cruz Roja Argentina, 5016 Córdoba (Argentina); Oliva, M. [FaMAF-Universidad Nacional de Córdoba, Córdoba (Argentina); IFEG-CONICET (Argentina); Eimer, G., E-mail: geimer@scdt.frc.utn.edu.ar [CITeQ-Universidad Tecnológica Nacional-Facultad Regional Córdoba, Maestro López esq. Cruz Roja Argentina, 5016 Córdoba (Argentina); CONICET (Argentina)

    2013-09-15

    Synthesis, structure and magnetic properties of Co/MCM-41 as magnetic nano-composites have been investigated. Mesoporous materials with different degrees of metal loading were prepared by wet impregnation and characterized by ICP, XRD, N{sub 2} adsorption, UV–vis DRS, TPR and EPMA-EDS. Cobalt oxide clusters and Co{sub 3}O{sub 4} nano-particles could be confined inside the mesopores of MCM-41, being this fact favored by the Co loading increasing. In addition, larger crystals of Co{sub 3}O{sub 4} detectable by XRD also grow on the surface when the Co loading is enhanced. The magnetic characterization was performed in a SQUID magnetometer using a maximum magnetic applied field µ{sub 0}Ha=1 T. While the samples with the higher Co loadings showed a behavior typically paramagnetic, a superparamagnetic contribution is more notorious for lower loadings, suggesting high Co species dispersion. - Graphical abstract: Room temperature hysteresis loops as a function of the Co content. Display Omitted - Highlights: • Co species as isolated Co{sup 2+}, oxide clusters and Co{sub 3}O{sub 4} nano-particles were detected. • For higher Co loads were detected, by XRD, Co{sub 3}O{sub 4} particles on the external surface. • The confining of Co species inside the mesopores was achieved by increasing Co load. • Paramagnetism from oxide clusters/nano-particles becomes dominant for higher Co loads. • Superparamagnetism can be assigned to Co species of small size and finely dispersed.

  20. Functionalized Mesoporous Silica Membranes for CO2 Separation Applications

    Directory of Open Access Journals (Sweden)

    Hyung-Ju Kim

    2015-01-01

    Full Text Available Mesoporous silica molecular sieves are emerging candidates for a number of potential applications involving adsorption and molecular transport due to their large surface areas, high pore volumes, and tunable pore sizes. Recently, several research groups have investigated the potential of functionalized mesoporous silica molecular sieves as advanced materials in separation devices, such as membranes. In particular, mesoporous silica with a two- or three-dimensional pore structure is one of the most promising types of molecular sieve materials for gas separation membranes. However, several important challenges must first be addressed regarding the successful fabrication of mesoporous silica membranes. First, a novel, high throughput process for the fabrication of continuous and defect-free mesoporous silica membranes is required. Second, functionalization of mesopores on membranes is desirable in order to impart selective properties. Finally, the separation characteristics and performance of functionalized mesoporous silica membranes must be further investigated. Herein, the synthesis, characterization, and applications of mesoporous silica membranes and functionalized mesoporous silica membranes are reviewed with a focus on CO2 separation.

  1. High drug load, stable, manufacturable and bioavailable fenofibrate formulations in mesoporous silica: a comparison of spray drying versus solvent impregnation methods.

    Science.gov (United States)

    Hong, Shiqi; Shen, Shoucang; Tan, David Cheng Thiam; Ng, Wai Kiong; Liu, Xueming; Chia, Leonard S O; Irwan, Anastasia W; Tan, Reginald; Nowak, Steven A; Marsh, Kennan; Gokhale, Rajeev

    2016-01-01

    Encapsulation of drugs in mesoporous silica using co-spray drying process has been recently explored as potential industrial method. However, the impact of spray drying on manufacturability, physiochemical stability and bioavailability in relation to conventional drug load processes are yet to be fully investigated. Using a 2(3) factorial design, this study aims to investigate the effect of drug-loading process (co-spray drying and solvent impregnation), mesoporous silica pore size (SBA-15, 6.5 nm and MCM-41, 2.5 nm) and percentage drug load (30% w/w and 50% w/w) on material properties, crystallinity, physicochemical stability, release profiles and bioavailability of fenofibrate (FEN) loaded into mesoporous silica. From the scanning electronic microscopy (SEM) images, powder X-ray diffraction and Differential scanning calorimetry measurements, it is indicated that the co-spray drying process was able to load up to 50% (w/w) FEN in amorphous form onto the mesoporous silica as compared to the 30% (w/w) for solvent impregnation. The in vitro dissolution rate of the co-spray dried formulations was also significantly (p = 0.044) better than solvent impregnated formulations at the same drug loading. Six-month accelerated stability test at 40 °C/75 RH in open dish indicated excellent physical and chemical stability of formulations prepared by both methods. The amorphous state of FEN and the enhanced dissolution profiles were well preserved, and very low levels of degradation were detected after storage. The dog data for the three selected co-spray-dried formulations revealed multiple fold increment in FEN bioavailability compared to the reference crystalline FEN. These results validate the viability of co-spray-dried mesoporous silica formulations with high amorphous drug load as potential drug delivery systems for poorly water soluble drugs.

  2. Novedoso método para preparar materiales nanoporosos compuestos MFI/MCM-41 a partir de caolín venezolano. Efecto de la concentración de NaOH

    Directory of Open Access Journals (Sweden)

    Freddy Imbert

    2012-05-01

    Full Text Available A MFI/MCM-41 composite material, a zeolite type MFI and Al-MCM-41 were synthesized from kaolin, using TPA and CTAB as structure directing agents. The MFI/MCM-41 composite material was synthesized in two steps. In the first, MFI was obtained and then treated with solutions of different NaOH concentrations (1 – 4M, in the second step the reaction mixture was treated under MCM-41 synthesis conditions. The solids obtained were characterized by scanning electron microscopy (SEM, chemical analysis by energy dispersive X-ray spectroscopy (EDX, transmission electron microscopy (TEM, adsorption of N2 at 77K, X-ray diffraction (XRD. In the absence of alkaline treatment two phases were observed – zeolite and mesoporous, whereas the zeolite crystals were larger than mesoporous particles. The alkaline treatment dissolved the zeolite structure creating mesoporosity, modifying the characteristic zeolite morphology and reducing its crystal domains. The treatment with 2 or 3M NaOH eases zeolite dissolution and leads to assemble of the zeolite building units around the surfactant and into the mesoporous walls. The incorporation of the zeolite building units into the mesoporous walls is governed by the relative quantities of crystalline and amorphous materials in the synthesis gel. The treatment with 4M NaOH led exclusively to the formation of Al-MCM-41.

  3. Effect of MCM-41 on the physicochemical properties of Mo and NiMo catalysts and their performance in DBT conversion

    Energy Technology Data Exchange (ETDEWEB)

    Grzechowiak, Jolanta R.; Mrozinska, Karolina; Masalska, Aleksandra [Department of Chemistry and Technology of Fuel, Faculty of Chemistry, Wroclaw University of Technology, 7/9 Gdanska Str., 50-344 Wroclaw (Poland); Goralski, Jacek; Rynkowski, Jacek [Institute of General and Ecological Chemistry, Technical University of Lodz, 36 Zwirki Str., 90-924 Lodz (Poland); Tylus, Wlodzimierz [Institute of Inorganic Technology, Faculty of Chemistry, Wroclaw University of Technology, Smoluchowskiego Str., 50-353 Wroclaw (Poland)

    2006-05-15

    The influence of mesoporous materials on the properties and HDS activity of Mo and NiMo catalysts was investigated for supports containing 50wt.% of MCM-41. A series of catalysts was characterized by different techniques (S{sub BET}, TPD-NH{sub 3}, TPR, SEM, XPS) and tested in dibenzothiophene (DBT) conversion. On the surface of the catalysts containing mesoporous materials, agglomerations of the Mo oxo-species were observed. The presence of MCM-41 in the support visibly weakened the promoting effect of TiO{sub 2} on the reducibility of Mo oxides. The results of DBT HDS showed that the NiMo catalyst supported on MCM-41 was not only less efficient than that supported on Al{sub 2}O{sub 3} but also that supported on Al{sub 2}O{sub 3}-TiO{sub 2}. From the distribution of DBT HDS products we can conclude that over catalysts containing MCM-41 the desulphurization of DBT runs mostly via the DDS route. (author)

  4. Porosity evolution of VP-DVB/MCM-41 nanocomposite.

    Science.gov (United States)

    Zaleski, Radoslaw; Stefaniak, Wojciech; Maciejewska, Malgorzata; Goworek, Jacek

    2010-03-01

    The porous structure of nanostructured vinylpyrrolidone-divinylbenzene (VP-DVB)/MCM-41 composite was characterized using N(2) adsorption at 77K and positronium annihilation lifetime spectroscopy (PALS), atomic force microscopy (AFM) and Raman spectroscopy. Positron annihilation lifetime spectra were measured during outgassing procedure. The voids of differentiated dimensions were detected in the composite material. The number of free volumes and their dimensions depend on the degree of evacuation of volatile components from the samples.

  5. Catalytic co-pyrolysis of waste particle board and polyproplylene over nanoporous Al-MCM-41 catalysts.

    Science.gov (United States)

    Lee, Hyung Won; Choi, Suek Joo; Jeon, Jong-Ki; Park, Sung Hoon; Park, Young-Kwon

    2014-11-01

    Catalytic co-pyrolysis of particle board, a waste wood biomass, and polypropylene (PP), a petroleum-based plastic, was carried out with a mixing ratio of 1:1 over a representative mesoporous material, Al-MCM-41 catalyst. The Si/Al ratios of the Al-MCM-41 catalysts were controlled at 20 and 80 to investigate the effect of the acidity of the catalyst. The characterization of the catalyst was performed by X-ray diffraction, N2 adsorption-desorption, and NH3 temperature-programmed desorption. The catalytic pyrolysis of the particle board showed a higher yield of gas and lower yield of oil than the non-catalytic pyrolysis. In oil, the concentration of levoglucosan decreased, and those of furans, furanones, cyclopentanones, aromatics, and light phenolics increased. In the case of the co-pyrolysis of the particle board and PP, C10-C17 products corresponding to the diesel range greatly increased and resulted in an improvement of the bio-oil quality. This suggests that PP is decomposed on the acidic sites of the Al-MCM-41 catalyst, resulting in an increased production of hydrocarbons in the range of diesel.

  6. Structure of Inert Gases Adsorbed in MCM-41

    Science.gov (United States)

    Evans, Dylan; Sokol, Paul

    One-dimensional quantum liquids of 3He or 4He have generated recent interest for investigation in the Luttinger liquid model. Unfortunately, current studies lack a clear demonstration of definitively one-dimensional behavior. We propose using the templated, porous material, MCM-41, as a host for an atomic Luttinger liquid. In general, the pores of MCM-41 are too wide to provide a strictly one-dimensional environment, so we investigate preplating these pores with inert gases to effectively reduce their diameter. We present the results of studies of the structure of inert gases in MCM-41. Nitrogen sorption isotherms were used to characterize the sample. Then, using inert gases as adsorbates, we determined the minimum effective pore diameter that can be achieved in our sample before capillary condensation takes over. X-ray powder diffraction (XRD) was performed on the ideally preplated sample to investigate the structure of the adsorbates in the nanopores. The XRD measurements are compared to simulations of core-shell cylinder model scattering, and the validity of the model is assessed. The prospects for creating a definitively one-dimensional channel for the application of studying the structure and dynamics of helium confined in one dimension are discussed. This work was supported by the National Science Foundation under Grant DGE-1069091.

  7. Biodegradation-tunable mesoporous silica nanorods for controlled drug delivery.

    Science.gov (United States)

    Park, Sung Bum; Joo, Young-Ho; Kim, Hyunryung; Ryu, WonHyoung; Park, Yong-il

    2015-05-01

    Mesoporous silica in the forms of micro- or nanoparticles showed great potentials in the field of controlled drug delivery. However, for precision control of drug release from mesoporous silica-based delivery systems, it is critical to control the rate of biodegradation. Thus, in this study, we demonstrate a simple and robust method to fabricate "biodegradation-tunable" mesoporous silica nanorods based on capillary wetting of anodic aluminum oxide (AAO) template with an aqueous alkoxide precursor solution. The porosity and nanostructure of silica nanorods were conveniently controlled by adjusting the water/alkoxide molar ratio of precursor solutions, heat-treatment temperature, and Na addition. The porosity and biodegradation kinetics of the fabricated mesoporous nanorods were analyzed using N2 adsorption/desorption isotherm, TGA, DTA, and XRD. Finally, the performance of the mesoporous silica nanorods as drug delivery carrier was demonstrated with initial burst and subsequent "zero-order" release of anti-cancer drug, doxorubicin.

  8. A study of freezing-melting hysteresis of water in different porous materials. Part II: surfactant-templated silicas.

    Science.gov (United States)

    Petrov, Oleg; Furó, István

    2011-09-28

    The freezing-melting hysteresis of water in mesoporous silicas MCM-48, MCM-41 and SBA-16 has been studied by NMR cryoporometry. The hysteresis in MCM-48 was found to exhibit nearly parallel branches, matching type H1 hysteresis that had been observed earlier in controlled pore glass. The same type of hysteresis is observed in two of three different-sized MCM-41 under study (a pore diameter of 3.6 and 3 nm), superimposed with a secondary, extremely broad, type H3 hysteresis. No hysteresis was found in the smallest MCM-41 with a pore diameter hysteresis with the freezing branch being essentially steeper than the melting one, which is attributed to a pore blockage upon freezing, similar to what we observed earlier in Vycor porous glass. The data were analyzed using the model of curvature-dependent metastability of a solid phase upon melting; the validity of this model has been discussed.

  9. Use of rice husk ash as only source of silica in the formation of mesoporous materials Emprego da cinza da casca de arroz como única fonte de sílica na formação de materiais mesoporosos

    Directory of Open Access Journals (Sweden)

    A. J. Schwanke

    2013-03-01

    Full Text Available This paper reports the synthesis of molecular sieves similar to MCM-41 using rice husk ash as only source of silica. For comparison purposes, a standard synthesis was performed using aerosil 200 commercial silica. The rice husk silica was obtained by heating treatment at 600 ºC and leaching for 2 h in reflux with HCl 1mol.L-1 and used in the synthesis. The samples prepared were characterized by N2 adsorption, X-ray diffraction (XRD, scanning electronic microscopy (SEM and thermogravimetric analysis (TG. By type-IV adsorption isotherms, the formation of mesoporous materials was observed. XRD showed the formation of hexagonal unidirectional pore materials similar to MCM-41. By SEM, it could be observed that the rice husk has fibrous aspect and that synthesis using calcined and leached rice husk did not react entirely because silica was only partially dissolved.Este trabalho relata o estudo da síntese de peneiras moleculares semelhantes à MCM-41, empregando cinza da casca de arroz como única fonte de sílica. Para critérios de comparação uma síntese foi realizada com sílica comercial aerosil 200. A sílica da casca de arroz foi obtida mediante tratamento térmico a 600 ºC e lixiviação em refluxo por 2 h com HCl 1 mol/L e empregada na síntese. As amostras preparadas foram caracterizadas por adsorção de N2, difração de raios X, microscopia eletrônica de varredura (MEV e termogravimetria. Por meio das isotermas de adsorção, do tipo IV, observa-se a formação de material mesoporoso. Nos difratogramas de raios X é identificada a formação hexagonal unidirecional de poros, indicando que material apresenta semelhanças com a MCM-41. Por MEV observa-se que a casca de arroz possui aspecto fibroso e que a síntese empregando a casca de arroz calcinada e lixiviada não reagiu na sua totalidade devido a dissolução parcial da sílica.

  10. Iron oxide nanoparticles stabilized inside highly ordered mesoporous silica

    Indian Academy of Sciences (India)

    A Bhaumik; S Samanta; N K Mal

    2005-11-01

    Nanosized iron oxide, a moderately large band-gap semiconductor and an essential component of optoelectrical and magnetic devices, has been prepared successfully inside the restricted internal pores of mesoporous silica material through in-situ reduction during impregnation. The samples were characterized by powder XRD, TEM, SEM/EDS, N2 adsorption, FT-IR and UV–visible spectroscopies. Characterization data indicated well-dispersed isolated nanoclusters of (Fe2O3),` within the internal surface of 2D-hexagonal mesoporous silica structure. No occluded Fe/Fe2O3 crystallites were observed at the external surface of the mesoporous silica nanocomposites. Inorganic mesoporous host, such as hydrophilic silica in the pore walls, directs a physical constraint necessary to prevent the creation of large Fe2O3 agglomerates and enables the formation of nanosized Fe2O3 particles inside the mesopore.

  11. Phosphoryl functionalized mesoporous silica for uranium adsorption

    Science.gov (United States)

    Xue, Guo; Yurun, Feng; Li, Ma; Dezhi, Gao; Jie, Jing; Jincheng, Yu; Haibin, Sun; Hongyu, Gong; Yujun, Zhang

    2017-04-01

    Phosphoryl functionalized mesoporous silica (TBP-SBA-15) was synthesized by modified mesoporous silica with γ-amino propyl triethoxy silane and tributyl phosphate. The obtained samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), small angle X-ray diffraction (SAXRD), thermo-gravimetric/differential thermalanalyzer (TG/DTA), N2 adsorption-desorption (BET) and Fourier transform infrared spectroscopy (FT-IR) techniques. Results showed that TBP-SBA-15 had large surface areas with ordered channel structure. Moreover, the effects of adsorption time, sorbent dose, solution pH, initial uranium concentration and temperature on the uranium adsorption behaviors were investigated. TBP-SBA-15 showed a high uranium adsorption capacity in a broad range of pH values. The U(VI) adsorption rate of TBP-SBA-15 was fast and nearly achieved completion in 10 min with the sorbent dose of 1 g/L. The U(VI) adsorption of TBP-SBA-15 followed the pseudo-second-order kinetic model and Freundlich isotherm model, indicating that the process was belonged to chemical adsorption. Furthermore, the thermodynamic parameters (ΔG0, ΔH0 and ΔS0) confirmed that the adsorption process was endothermic and spontaneous.

  12. Hydrogen sulfide removal from hot coal gas by various mesoporous silica supported Mn{sub 2}O{sub 3} sorbents

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Z.F.; Liu, B.S., E-mail: bingsiliu@tju.edu.cn; Wang, F.; Wang, W.S.; Xia, C.; Zheng, S.; Amin, R.

    2014-09-15

    Graphical abstract: - Highlights: • Mn{sub 2}O{sub 3}/KIT-1 presented the best desulfurization performance at 600–850 °C. • High sulfur capacity of Mn{sub 2}O{sub 3}/KIT-1 correlated closely with 3-D channel of KIT-1. • Desulfurization character depended strongly on framework structure of sorbents. • High steam content suppressed greatly the occurrence of sulfidation reaction. - Abstract: A series of 50 wt% Mn{sub 2}O{sub 3} sorbents was prepared using various mesoporous silica, MCM-41, HMS, and KIT-1 as support. The influence of textural parameters of mesoporous silica, especially type of channel on the desulfurization performance of Mn{sub 2}O{sub 3} sorbents was investigated at 600–850 °C using hot coal gas containing 0.33 vol.% H{sub 2}S. The fresh and used sorbents were characterized by means of N{sub 2}-adsorption, x-ray diffraction (XRD), high resolution transmission microscopy (HRTEM) and H{sub 2} temperature- programmed reduction (H{sub 2}-TPR) techniques. The results confirmed that the manganese oxide was dispersed highly in regular pore channel of the mesoporous supports due to high surface area. Compared with the Mn{sub 2}O{sub 3}/diatomite, all mesoporous silica supported Mn{sub 2}O{sub 3} sorbents exhibited high breakthrough sulfur capacity and a sharp deactivation rate after the breakthrough point. Compared to Mn{sub 2}O{sub 3}/MCM-41 and Mn{sub 2}O{sub 3}/HMS sorbent, the Mn{sub 2}O{sub 3}/KIT-1 showed better desulfurization performance because of the 3D wormhole-like channel. The high sulfur capacity of the Mn{sub 2}O{sub 3}/KIT-1 sorbent was maintained during the eight consecutive desulfurization-regeneration cycles. The Mn{sub 2}O{sub 3}/KIT-1 still presented high desulfurization activity when hot coal gas contained low steam (<5%)

  13. Sn-MCM-41 as Efficient Catalyst for the Conversion of Glucose into 5-Hydroxymethylfurfural in Ionic Liquids

    Directory of Open Access Journals (Sweden)

    Qing Xu

    2013-11-01

    Full Text Available Recently, much attention has been paid to the development of technologies that facilitate the conversion of biomass into platform chemicals such as 5-hydroxymethylfurfural (5-HMF. In this paper, a tin-containing silica molecular sieve (Sn-MCM-41 was found to act as a bifunctional heterogeneous catalyst for the efficient conversion of glucose into 5-HMF in ionic liquid. In the presence of [EMIM]Br, the yield of 5-HMF converted from glucose reached 70% at 110 °C after 4 h. During the reaction, the active center of the catalyst first catalyzed the isomerization of glucose into fructose and then the dehydration of fructose into 5-HMF. After the reaction, the heterogeneous catalyst Sn-MCM-41 could be easily recovered and reused without a significant loss in activity. The catalyst Sn-MCM-41 was also able to catalyze the conversion of fructose into 5-HMF at an 80% yield. Moreover, the low toxicity of the Sn-based catalyst makes the method a greener approach for the conversion of saccharides into 5-HMF.

  14. Reduction of tobacco smoke components yield in commercial cigarette brands by addition of HUSY, NaY and Al-MCM-41 to the cigarette rod

    Directory of Open Access Journals (Sweden)

    A. Marcilla

    2015-01-01

    Full Text Available The effect of two zeolites, HUSY, NaY and a mesoporous synthesized Al-MCM-41 material on the smoke composition of ten commercial cigarettes brands has been studied. Cigarettes were prepared by mixing the tobacco with the three powdered materials, and the smoke obtained under the ISO conditions was analyzed. Up to 32 compounds were identified and quantified in the gas fraction and 80 in the total particulate matter (TPM condensed in the cigarettes filters and in the traps located after the mouth end of the cigarettes. Al-MCM-41 is by far the best additive, providing the highest reductions of the yield for most compounds and brands analyzed. A positive correlation was observed among the TPM and nicotine yields with the reduction obtained in nicotine, CO, and most compounds with the three additives. The amount of ashes in additive free basis increases due to the coke deposited on the solids, especially with Al-MCM-41. Nicotine is reduced with Al-MCM-41 by an average of 34.4% for the brands studied (49.5% for the brand where the major reduction was obtained and 18.5 for the brand behaving the worst. CO is reduced by an average of 18.6% (ranging from 10.3 to 35.2% in the different brands.

  15. Structural consequences of mild oxidative template removal in the synthesis of modified MCM-41 silicates

    Science.gov (United States)

    Meretei, Edit; Halász, János; Méhn, Dóra; Kónya, Zoltán; Korányi, Tamás I.; Nagy, János B.; Kiricsi, Imre

    2003-06-01

    Results concerning the structural consequences of template removal from MCM-41 mesoporous materials are described using ozone, N 2O and NO 2 as oxidants in comparison with the conventional method applying oxygen. Si, TiSi-, VSi and ZrSi-MCM-41 samples were synthesized by the usual methods. For characterization of the as-synthesized and treated samples XRD, nitrogen adsorption, 29Si MAS NMR-, IR- and UV-Vis spectroscopic methods were used. The catalytic activity of the samples was tested in the Friedel-Crafts alkylation of toluene by benzyl chloride. The comparison of template removal agents showed that ozone was the most active at low temperature (423 K), and the treatment was less destructive than burning off the template in oxygen. Nitrogen oxide treatment (NO 2 and N 2O) resulted in template removal at relatively low temperature (573-623 K), and structure deterioration was small. Si NMR spectroscopic data and IR spectra taken in the framework vibration range revealed that more original -SiOH groups remained as hydroxyl nests, furthermore, the heteroatom remained in tetrahedral coordination after ozone and nitrogen oxide treatment compared to burning off the template by oxygen. The results proved the advantages of ozone or nitrogen oxide treatments: (i) gentler to heteroatoms situated in the framework of the materials, probably leaves them intact, (ii) does not result in the formation of secondary micropores, which would decrease the uniform arrangement of the original pore systems, (iii) by preserving the active centers in their original coordination more uniform product distribution may be expected in catalytic reactions.

  16. An investigation into the Ti-grafting structure on MCM-41 and epoxidation catalysis

    DEFF Research Database (Denmark)

    Yuan, Q.C.; Hagen, A.; Roessner, F.

    2006-01-01

    The structure of titanium species grafted on a purely siliceous MCM-41 and their catalysis in the epoxidation of cyclohexene with tert-butyl hydroperoxide (TBHP) were investigated. FT-IR, XANES and UV-vis were used for the examination of the Ti-grafted MCM-41. The results indicated that the titan......The structure of titanium species grafted on a purely siliceous MCM-41 and their catalysis in the epoxidation of cyclohexene with tert-butyl hydroperoxide (TBHP) were investigated. FT-IR, XANES and UV-vis were used for the examination of the Ti-grafted MCM-41. The results indicated...

  17. XAFS Study of the Photo-Active Site of Mo/MCM-41

    Science.gov (United States)

    Miyamoto, Daisuke; Ichikuni, Nobuyuki; Shimazu, Shogo

    2007-02-01

    An Mo/MCM-41 catalyst was prepared and used for study of propene and 1-butene photo-metathesis reactions. XAFS analysis revealed that hydrogen reduction leads to a decreased role for the Mo=O site. The Mo-O site plays an important role for the olefin photo-metathesis reaction on the H2 reduced Mo/MCM-41. From EXAFS analysis, the active site of photo-metathesis reaction is the Mo=O part for oxidized Mo/MCM-41, whereas it is the Mo-O site for reduced Mo/MCM-41.

  18. Catalytic oxidation of 4-tert-butyltoluene over Ti-MCM-41

    Institute of Scientific and Technical Information of China (English)

    Wei Hua Yu; Chun Hui Zhou; Xiang Sheng Xu; Zhong Hua Ge

    2007-01-01

    The surface-grafted titanium MCM-41 materials were prepared by anchoring titanocene onto the inner walls of MCM-41. The materials were characterized by powder X-ray diffraction (XRD), N2 adsorption-desorption isotherm and diffuse reflectance UV-visible (UV-vis) spectroscopies. The catalytic properties of Ti-MCM-41 were tested in oxidation of 4-tert-butyltoluene with tert-butylhydroperoxide (TBHP) in liquid phase. MCM-41 with loading 4.8 mol% Ti gave the maximal conversions of 23.6% of 4-tert-butyltoluene with a complete selectivity to 4-tert-butylbenzaldehyde.

  19. Incorporation of anti-inflammatory agent into mesoporous silica

    Science.gov (United States)

    Rodrigues Braz, Wilson; Lamec Rocha, Natállia; de Faria, Emerson H.; Silva, Márcio L. A. e.; Ciuffi, Katia J.; Tavares, Denise C.; Furtado, Ricardo Andrade; Rocha, Lucas A.; Nassar, Eduardo J.

    2016-09-01

    The unique properties of macroporous, mesoporous, and microporous systems, including their ability to accommodate molecules of different sizes inside their pores and to act as drug delivery systems, have been the object of extensive studies. In this work, mesoporous silica with hexagonal structure was obtained by template synthesis via the sol-gel process. The resulting material was used as support to accommodate the anti-inflammatory agent indomethacin. The alkaline route was used to prepare the mesoporous silica; cetyltrimethylammonium bromide was employed as porogenic agent. The silica particles were functionalized with 3-aminopropyltriethoxysilane alkoxide (APTES) by the sol-gel post-synthesis method. Indomethacin was incorporated into the silica functionalized with APTES and into non-functionalized silica. The resulting systems were characterized by x-ray diffraction (XRD), specific area, infrared spectroscopy, and thermal analyses (TGA). XRD attested to formation of mesoporous silica with hexagonal structure. This structure remained after silica functionalization with APTES and incorporation of indomethacin. Typical infrared spectroscopy vibrations and organic material decomposition during TGA confirmed silica functionalization and drug incorporation. The specific surface area and pore volume of the functionalized material incorporated with indomethacin decreased as compared with the specific surface area and pore volume of the non-functionalized silica containing no drug, suggesting both the functionalizing agent and the drug were present in the silica. Cytotoxicity tests conducted on normal fibroblasts (GM0479A) cells attested that the silica matrix containing indomethacin was less toxic than the free drug.

  20. Controlled radical polymerization of vinyl acetate in presence of mesoporous silica supported TiCl4 heterogeneous catalyst

    Indian Academy of Sciences (India)

    M A Semsarzadeh; S Amiri; M Azadeh

    2012-10-01

    The heterogeneous TiCl4 catalysts supported on mesoporous mobile composition of matter (MCM-41) and mesoporous silicone particles synthesized from block copolymer of PPG–PEG–PPG (SPB) complexed with dimethyl formamide (DMF) ligand were used in a controlled free radical reaction with benzoyl peroxide (BPO) initiator in bulk polymerization of vinyl acetate (VAc). In this polymerization process, mesoporous particle of SPB increased the reactivity of TiCl4 catalyst with DMF ligand. The active site formed on the surface and the pores of the catalyst produced specific sequences of VAc on the chain with different thermal and microstructural properties and crystallinity.

  1. Colloidal suspensions of functionalized mesoporous silica nanoparticles.

    Science.gov (United States)

    Kobler, Johannes; Möller, Karin; Bein, Thomas

    2008-04-01

    The synthesis and characterization of colloidal mesoporous silica (CMS) functionalized with vinyl-, benzyl-, phenyl-, cyano-, mercapto-, aminopropyl- or dihydroimidazole moieties is reported. Uniform mesoporous particles ranging in size from 40 to 150 nm are generated in a co-condensation process of tetraethylorthosilicate (TEOS) and organotriethoxysilanes (RTES) in alkaline aqueous media containing triethanolamine (TEA) in combination with cetyltrimethylammonium chloride (CTACl) serving as a structure-directing agent. The materials are obtained as colloidal suspensions featuring long-term stability after template removal by ion exchange with an ethanolic solution of ammonium nitrate or HCl. The spherical particles exhibit a wormlike pore system with defined pore sizes and high surface areas. Samples are analyzed by a number of techniques including TEM, SEM, DLS, TGA, Raman, and cross-polarized (29)Si-MAS NMR spectroscopy, as well as nitrogen sorption measurements. We demonstrate that co-condensation and grafting methods result in similar changes in the nitrogen adsorption behavior, indicating a successful internal lining of the pores with functional groups through both procedures.

  2. BITEMPLATE SYNTHESIS OF MESOPOROUS SILICAS WITH THIOUREA GROUPS

    Directory of Open Access Journals (Sweden)

    O. I. Gona

    2009-06-01

    Full Text Available Mesoporous silicas with the thiourea functional group ≡Si(CH23NHC(SNHC2H5 have been synthesized by monotemplate and bitemplate route (bitemplate is cetylpyridinium chloride as micelle-forming surfactant and monoethanolamide of saturated n-aliphatic acid as non-micelle-forming surfactant. The infl uence of a number of factors on mesoporous silicas structure has been studied: alkoxysilanes and surfactants concentration, and as well as the nature of medium in hydrothermal treatment of mesophases. The optimum conditions under which functionalized mesoporous silicas have possessing highly ordered hexagonal structure have been found. The surface area of mesoporous silicas synthesized using optimum bitemplate solubilization composition reaches 1055-1350 m2/g and sorption volume and pore diameter are 0.75-0.95 cm3/g and 2.5-2.9 nm respectively.

  3. Sol-Gel Synthesis of Ordered β-Cyclodextrin-Containing Silicas

    OpenAIRE

    Trofymchuk, Iryna Mykolaivna; Roik, Nadiia; Belyakova, Lyudmila

    2016-01-01

    New approaches for β-cyclodextrin-containing silicas synthesis were demonstrated. Materials with hexagonally ordered mesoporous structure were prepared by postsynthesis grafting and by co-condensation methods. β-Cyclodextrin activated by a N,N′-carbonyldiimidazole was employed for postsynthesis treatment of 3-aminopropyl-modified MCM-41 support as well as for sol-gel synthesis with β-cyclodextrin-containing organosilane and tetraethyl orthosilicate participation in the presence of cetyltrimet...

  4. pH-responsive nanovalves based on hollow mesoporous silica spheres for controlled release of corrosion inhibitor

    Science.gov (United States)

    Chen, Tao; Fu, JiaJun

    2012-06-01

    In the present study, a new encapsulation technique for corrosion inhibitor is proposed. The hollow mesoporous silica spheres (HMSs) were synthesized by the co-templates method as nanocontainers for corrosion inhibitor, benzotriazole (BTA) and the supramolecular nanovalves, consisting of cucurbit[6]uril (CB[6]) rings and the functional stalks attached to the surface of HMSs achieved on-demand release. The synthesis process of HMSs and the assembly process of the nanovalves were confirmed by SEM, TEM, N2 adsorption/desorption, FTIR, TGA and solid-state 13C CP/MAS NMR. The encapsulation capacity and release characteristics of BTA-loaded, assembled HMSs were investigated. The HMSs assembled with the nanovalves possessed a higher encapsulation capacity for BTA than MCM-41 assembled under the same procedure due to its huge hollow internal structure. The pH-controlled release properties of BTA from the assembled HMSs under different pH environments were monitored by ultraviolet absorption spectra. The release profiles showed that there was almost no leakage of BTA from the assembled HMSs in neutral solution, while in alkaline solution BTA released very quickly, and the release rate increased with increasing pH values. Such a property makes the HMSs assembled with the pH-responsive nanovalves have great potential applications in smart anticorrosion coatings.

  5. pH-responsive nanovalves based on hollow mesoporous silica spheres for controlled release of corrosion inhibitor.

    Science.gov (United States)

    Chen, Tao; Fu, JiaJun

    2012-06-15

    In the present study, a new encapsulation technique for corrosion inhibitor is proposed. The hollow mesoporous silica spheres (HMSs) were synthesized by the co-templates method as nanocontainers for corrosion inhibitor, benzotriazole (BTA) and the supramolecular nanovalves, consisting of cucurbit[6]uril (CB[6]) rings and the functional stalks attached to the surface of HMSs achieved on-demand release. The synthesis process of HMSs and the assembly process of the nanovalves were confirmed by SEM, TEM, N(2) adsorption/desorption, FTIR, TGA and solid-state (13)C CP/MAS NMR. The encapsulation capacity and release characteristics of BTA-loaded, assembled HMSs were investigated. The HMSs assembled with the nanovalves possessed a higher encapsulation capacity for BTA than MCM-41 assembled under the same procedure due to its huge hollow internal structure. The pH-controlled release properties of BTA from the assembled HMSs under different pH environments were monitored by ultraviolet absorption spectra. The release profiles showed that there was almost no leakage of BTA from the assembled HMSs in neutral solution, while in alkaline solution BTA released very quickly, and the release rate increased with increasing pH values. Such a property makes the HMSs assembled with the pH-responsive nanovalves have great potential applications in smart anticorrosion coatings.

  6. Optimization of pore structure and particle morphology of mesoporous silica for antibody adsorption for use in affinity chromatography

    Science.gov (United States)

    Hikosaka, Ryouichi; Nagata, Fukue; Tomita, Masahiro; Kato, Katsuya

    2016-10-01

    Antibodies have received significant attention for use as antibody drugs, because they bind the objective protein (antigen) via antigen-antibody reactions. Recently, many reports have appeared on various monoclonal antibodies that recognize a single antigen. In this study, monoclonal antibodies are used as adsorbates on mesoporous silica (MPS) for affinity chromatography. MPS has high surface area and large pore volume; moreover, pore diameter, pore structure, and particle morphology are relatively easy to tune by adjusting the conditions of synthesis. The pore structure (two-dimensional (2D) hexagonal and three-dimensional cubic) and particle morphology (spherical and polyhedral) of MPS are optimized for use in a monoclonal antibody/MPS composite. When anti-IgG (one of the monoclonal antibodies) adsorbs on the MPS material and IgG (antigen) binds to anti-IgG/MPS composites, MCM-41p with a 2D-hexagonal pore structure and polyhedral particle morphology has the highest IgG binding efficiency. In addition, the antibody/MPS composites remain stable in chaotropic and low-pH solutions and can be cycled at least five times without decreasing IgG elution. In purification and removal tests, the use of the antibody/MPS composites allows only the objective protein from protein mixtures to be bound and eluted.

  7. A highly ordered cubic mesoporous silica/graphene nanocomposite

    Science.gov (United States)

    Lee, Chang-Wook; Roh, Kwang Chul; Kim, Kwang-Bum

    2013-09-01

    A highly ordered cubic mesoporous silica (KIT-6)/graphene nanocomposite and 2D KIT-6 nanoflakes were synthesized using a novel synthesis methodology. The non-ionic triblock copolymer, P123, played a dual role as a structure-directing agent in the formation of the cubic mesoporous structure and as a cross-linking agent between mesoporous silica and graphene. The prepared (KIT-6)/graphene nanocomposite could act as a template for the preparation of mesoporous material/graphene nanocomposites.A highly ordered cubic mesoporous silica (KIT-6)/graphene nanocomposite and 2D KIT-6 nanoflakes were synthesized using a novel synthesis methodology. The non-ionic triblock copolymer, P123, played a dual role as a structure-directing agent in the formation of the cubic mesoporous structure and as a cross-linking agent between mesoporous silica and graphene. The prepared (KIT-6)/graphene nanocomposite could act as a template for the preparation of mesoporous material/graphene nanocomposites. Electronic supplementary information (ESI) available: S1: TEM images of disordered mesoporous silica/graphene nanocomposite; S2: TEM images of KIT-6/GO nanocomposite; S3: Thermogravimetric analysis of KIT-6/GO and KG-400-700; S4: SEM and TEM images of KIT-6; S5: Low angle XRD, Raman spectra, N2 adsorption isotherms, pore size distribution and photographic images of the prepared samples; S6: TEM image and N2 adsorption isotherms of mesoporous carbon/graphene nanocomposite; S7: XPS C1s spectra of the prepared samples. See DOI: 10.1039/c3nr03108j

  8. 配合物[Mn(phen)2]2+修饰的MCM-41的合成与表征%Synthesis and Characterization of Manganese(II)-Phenanthroline Complex Functionalized MCM-41

    Institute of Scientific and Technical Information of China (English)

    郑珊; 高濂; 郭景坤

    2001-01-01

    The preparation of manganese(II)-phenanthroline complex functionalized MCM-41 was described. The modification of the internal pore surface of mesoporous MCM-41 with 3-aminopropyl or 3-methacryloyloxypropyl and yielded two different functional groups by using 3-aminopropyltriethoxysilane and (3-methacryloyloxypropyl)trimethoxysilane as the precursors.Manganese(II) phenanthroline complex was grafted onto the functional MCM-41 via the coordination of the metal ion with the functional group. The metal ion complex functionalized mesoporous materials were characterized by XRD, FTIR, N2 adsorption/desorption at 77K, solid state diffuse reflectance UV-VIS spectroscopy as well as electron spin resonance (ESR) at room temperature. After the functionalization, the vibrations such as vC=C, (δCH2 from the organic ligands or Mn(II) complex can be observed clearly. BET surface area, pore volume and most probably diameter decreased correspondingly according to the data of N2 sorption at 77K. In UV-VIS spectra, the absorption at short wavelength was strengthened because of the introduced organic ligands. And the results of ESR suggested that Mn(II) coordination in complexes didn't change remarkably.%分别以γ-氨丙基和甲基丙烯酸丙酯基修饰介孔分子筛MCM-41内孔壁,将引入的有机官能团与金属配位离子[Mn(phen)2Cl]+通过配位键成键首次合成了锰(II)配位化合物修饰的MCM-41(MCM-ap-Mn(phen)2,MCM-mp-Mn(phen)2)。通过XRD、FTIR、77K氮气吸附-脱附、UV-VIS漫反射光谱和Mn2+电子顺磁共振谱(ESR)表征了复合物MCM-ap-Mn(phen)2和MCM-mp-Mn(phen)2。由于有机基团对MCM-41孔壁的修饰,使复合物的结晶度降低;增加的有机基团和配合物使红外光谱有所改变; BET比表面积,孔容和最可几孔径均下降;γ-氨丙基或甲基丙烯酸丙酯基与Mn2+的配位而使其UV-VIS漫反射吸收光谱在短波长的吸收加强;室温下Mn2+电子顺磁共振表明Mn(II)配位环境几乎没有变化。

  9. Adsorption Behavior for CO on Modified MCM-41 with Zn and CuCl

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The Zn-Cu(Ⅰ)/HMCM-41 catalysts were successfully prepared in laboratory scale by solid-state ion exchange with CuCl salt, together with introduction of Zn to improve the dispersion degree of the active component Cu(Ⅰ) on the surface. With increase of the amounts of Zn and CuCl from 0% to 9.0% and 25.0% respectively, CO adsorption the amounts of increased from 10.6 μmol/g to 183.0 μmol/g correspondingly. The in situ FT-IR spectra for CO adsorption demonstrated that there existed two dynamic equilibriums between surface carbonyl complexes: Cu(CO)3+ Cu(CO)2++ CO and Cu(CO)2+ Cu(CO)+ + CO. The equilibriums can be shifted reversibly by changing the temperature and pressure. Due to the modified MCM-41 mesoporous materials possess both of the acidic and metallic carbonyl centers, this kind of material can be developed into mesoporous bifunctional catalysts for carbonylation reactions, in which larger molecules are involved.

  10. Preparation of resveratrol-loaded nanoporous silica materials with different structures

    Energy Technology Data Exchange (ETDEWEB)

    Popova, Margarita, E-mail: mpopova@orgchem.bas.bg [Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Szegedi, Agnes [Research Centre for Natural Sciences, Institute of Materials and Environmental Chemistry, Hungarian Academy of Sciences, 1117 Budapest, Magyar tudósok körútja 2. (Hungary); Mavrodinova, Vesselina [Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Novak Tušar, Natasa [National Institute of Chemistry, Ljubljana (Slovenia); Mihály, Judith; Klébert, Szilvia [Research Centre for Natural Sciences, Institute of Materials and Environmental Chemistry, Hungarian Academy of Sciences, 1117 Budapest, Magyar tudósok körútja 2. (Hungary); Benbassat, Niko; Yoncheva, Krassimira [Faculty of Pharmacy, 2 Dunav Str., 1000 Sofia (Bulgaria)

    2014-11-15

    Solid, nanoporous silica-based spherical mesoporous MCM-41 and KIL-2 with interparticle mesoporosity as well as nanosized zeolite BEA materials differing in morphology and pore size distribution, were used as carriers for the preparation of resveratrol-loaded delivery systems. Two preparation methods have been applied: (i) loading by mixing of resveratrol and mesoporous carrier in solid state and (ii) deposition in ethanol solution. The parent and the resveratrol loaded carriers were characterized by XRD, TEM, N2 physisorption, thermal analysis, and FT-IR spectroscopy. The influence of the support structure on the adsorption capacity and the release kinetics of this poorly soluble compound were investigated. Our results indicated that the chosen nanoporous silica supports are suitable for stabilization of trans-resveratrol and reveal controlled release and ability to protect the supported compound against degradation regardless of loading method. The solid-state dry mixing appears very effective for preparation of drug formulations composed of poorly soluble compound. - Graphical abstract: trans-Resveratrol was stabilized in the pores of BEA zeolite, MCM-41and KIL2 mesoporous silicas. - Highlights: • BEA, KIL-2 and MCM-41 materials were used as carriers for resveratrol loading. • Resveratrol encapsulation in ethanol solution and solid state procedure were applied. • The solid-state preparation appears very effective for stabilization of trans-resveratrol.

  11. Preparation of ZnO/Co-MCM-41 Molecular Sieves and Their Catalytic Performance for Isoamyl Alcohol Oxidation%Co掺杂ZnO/MCM-41分子筛的制备及对异戊醇的催化氧化性能

    Institute of Scientific and Technical Information of China (English)

    高虎飞; 赵彬侠; 刘卫娟; 刘林学; 叶维; 高晗; 章毅; 张小里

    2013-01-01

    ordered hexagonal mesopore structure of MCM-41 and had high speci-fic surface area(989 m2/g),pore size(2.88 nm) and larger pore volume(0.88 cm3/g) when Codoping amount was 0.05.The cobalt introduced into Co-MCM-41 existed mainly as single-site Co(Ⅱ) ions,which improved the effective dispersion of ZnO and moderately reduced the acidity of 5% ZnO/MCM-41 molecular sieves.At the same time,it improved the oxidation-reduction potential of 5% ZnO/MCM-41.Compared with 5%ZnO/MCM-41,The selectivity of isovaleric aldehyde increased 28.3% with 5% ZnO/0.05Co-MCM-41.

  12. Pressure-induced structure phase transition on Te/MCM41

    CERN Document Server

    Chen Hai Yong; Cui Qi Liang; Pan Yue Wu; Liu Bing Bing; Zou Guang Tian; LiuJing

    2002-01-01

    In situ high pressure energy dispersive X-ray diffraction experiments have been carried out on Te + MCM41 by using diamond anvil cell (DAC) device with synchrotron radiation source. The highest pressure is 37 GPa. In the range of authors' experimental pressure, a cubic phase transitions of Te inside MCM41 from 5 GPa is observed. Its peak intensity is weak

  13. Immobilization of Homogeneous Catalysis on Phosphinated MCM-41

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ Homogeneous catalysis Rh(PPh3)3Cl immobilized on MCM-41 modified with (OEt)3Si(CH2)3PPh2 results in a stable hydrogenation catalyst with turn over frequency (TOF) three times higher than that of Rh(PPh3)3C1 in the hydrogenation of cyclohexene. Leaching of the catalyst is only a minor factor with leaching rate 0.04 % for each cycle. However, immobilization of Rh(PPh3)2(CO)C1 on similar support can only have catalytic hydroformylation properties for the first few cycles. Decay of the catalyst is due to largh leaching rate with totally 22.4 % of Rh leached for the first three cycles.

  14. Immobilization of Homogeneous Catalysis on Phosphinated MCM-41

    Institute of Scientific and Technical Information of China (English)

    SHYU; Shin-Guang

    2001-01-01

    Homogeneous catalysis Rh(PPh3)3Cl immobilized on MCM-41 modified with (OEt)3Si(CH2)3PPh2 results in a stable hydrogenation catalyst with turn over frequency (TOF) three times higher than that of Rh(PPh3)3C1 in the hydrogenation of cyclohexene. Leaching of the catalyst is only a minor factor with leaching rate 0.04 % for each cycle. However, immobilization of Rh(PPh3)2(CO)C1 on similar support can only have catalytic hydroformylation properties for the first few cycles. Decay of the catalyst is due to largh leaching rate with totally 22.4 % of Rh leached for the first three cycles.  ……

  15. Mesoporous silica magnetite nanocomposite synthesized by using a neutral surfactant

    Science.gov (United States)

    Souza, K. C.; Salazar-Alvarez, G.; Ardisson, J. D.; Macedo, W. A. A.; Sousa, E. M. B.

    2008-05-01

    Magnetite nanoparticles coated by mesoporous silica were synthesized by an alternative chemical route using a neutral surfactant and without the application of any functionalization method. The magnetite (Fe3O4) nanoparticles were prepared by precipitation from aqueous media, and then coated with mesoporous silica by using nonionic block copolymer surfactants as the structure-directing agents. The mesoporous SiO2-coated Fe3O4 samples were characterized by x-ray diffraction, Fourier-transform infrared spectroscopy, N2 adsorption-desorption isotherms, transmission electron microscopy, 57Fe Mössbauer spectroscopy, and vibrating sample magnetometry. Our results revealed that the magnetite nanoparticles are completely coated by well-ordered mesoporous silica with free pores and stable (~8 nm thick) pore walls, and that the structural and magnetic properties of the Fe3O4 nanoparticles are preserved in the applied synthesis route.

  16. Mesoporous Silicas with Tunable Morphology for the Immobilization of Laccase

    Directory of Open Access Journals (Sweden)

    Victoria Gascón

    2014-05-01

    Full Text Available Siliceous ordered mesoporous materials (OMM are gaining interest as supports for enzyme immobilization due to their uniform pore size, large surface area, tunable pore network and the introduction of organic components to mesoporous structure. We used SBA-15 type silica materials, which exhibit a regular 2D hexagonal packing of cylindrical mesopores of uniform size, for non-covalent immobilization of laccase. Synthesis conditions were adjusted in order to obtain supports with different particle shape, where those with shorter channels had higher loading capacity. Despite the similar isoelectric points of silica and laccase and the close match between the size of laccase and the pore dimensions of these SBA-15 materials, immobilization was achieved with very low leaching. Surface modification of macro-/mesoporous amorphous silica by grafting of amine moieties was proved to significantly increase the isoelectric point of this support and improve the immobilization yield.

  17. Synthesis of cobalt-containing mesoporous catalysts using the ultrasonic-assisted "pH-adjusting" method: Importance of cobalt species in styrene oxidation

    Science.gov (United States)

    Li, Baitao; Zhu, Yanrun; Jin, Xiaojing

    2015-01-01

    Cobalt-containing SBA-15 and MCM-41 (Co-SBA-15 and Co-MCM-41) mesoporous catalysts were prepared via ultrasonic-assisted "pH-adjusting" technique in this study. Their physiochemical structures were comprehensively characterized and correlated with catalytic activity in oxidation of styrene. The nature of cobalt species depended on the type of mesoporous silica as well as pH values. The different catalytic performance between Co-SBA-15 and Co-MCM-41 catalysts originated from cobalt species. Cobalt species were homogenously incorporated into the siliceous framework of Co-SBA-15 in single-site Co(II) state, while Co3O4 particles were loaded on Co-MCM-41 catalysts. The styrene oxidation tests showed that the single-site Co(II) state was more beneficial to the catalytic oxidation of styrene. The higher styrene conversion and benzaldehyde selectivity over Co-SBA-15 catalysts were mainly attributed to single-site Co(II) state incorporated into the framework of SBA-15. The highest conversion of styrene (34.7%) with benzaldehyde selectivity of 88.2% was obtained over Co-SBA-15 catalyst prepared at pH of 7.5, at the mole ratio of 1:1 (styrene to H2O2) at 70 °C.

  18. Mesoporous Carbon Produced from Tri-constituent Mesoporous Carbon-silica Composite for Water Purification

    KAUST Repository

    Yu, Yanjie

    2012-05-01

    Highly ordered mesoporous carbon-silica nanocomposites with interpenetrating carbon and silica networks were synthesized by the evaporation-induced tri-constituent co- assembly approach. The removal of silica by concentrated NaOH solution produced mesoporous carbons, which contained not only the primary large pores, but also the secondary mesopores in the carbon walls. The thus synthesized mesoporous carbon was further activated by using ZnCl2. The activated mesoporous carbon showed an improved surface area and pore volume. The synthesized mesoporous carbon was tested for diuron removal from water and the results showed that the carbon gave a fast diuron adsorption kinetics and a high diuron removal capacity, which was attributable to the primary mesopore channels being the highway for mass transfer, which led to short diffusion path length and easy accessibility of the interpenetrated secondary mesopores. The optimal adsorption capacity of the porous carbon was determined to be 390 mg/g, the highest values ever reported for diuron adsorption on carbon-based materials.

  19. Photoluminescence of carbon dots from mesoporous silica

    Science.gov (United States)

    Nelson, D. K.; Razbirin, B. S.; Starukhin, A. N.; Eurov, D. A.; Kurdyukov, D. A.; Stovpiaga, E. Yu; Golubev, V. G.

    2016-09-01

    Photophysical properties of carbon dots were investigated under various excitation conditions and over a wide temperature region - from room to liquid helium temperatures. The carbon dots (CDs) were synthesized using mesoporous silica particles as a reactor and (3-aminopropyl)triethoxysilane (APTES) as a precursor. The photoluminescence spectra of CDs exhibit a strong dependence on the excitation wavelength and demonstrate a significant inhomogeneous broadening. Lowering sample temperature reveals the doublet structure of the spectra, which is associated with the vibronic structure of radiative transitions. The vibration energy ∼1200 cm-1 is close to the energy of Csbnd O stretching vibration. Long-lived phosphorescence of carbon dots with its decay time ∼0.2 s at T = 80 K was observed. The fluorescence and phosphorescence spectra are shown to be spectrally separated. The long-lived component of the emission was ascribed to optically forbidden triplet-singlet transitions. The value of the singlet-triplet splitting was found to be about 0.3 eV. Photo-induced polarization of the luminescence of carbon dots was revealed. The degree of the linear polarization is dependent on the wavelengths of both excitation and emitted light. The effect indicates a hidden anisotropy of optical dipole transitions in the dots and demonstrates the loss of the dipole orientation during the electron energy relaxation.

  20. Ni/Ce-MCM-41 mesostructured catalysts for simultaneous production of hydrogen and nanocarbon via methane decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Guevara, J.C.; Wang, J.A.; Chen, L.F.; Valenzuela, M.A. [ESIQIE, Instituto Politecnico Nacional, Col. Zacatenco, Av. Politecnico s/n, 07738 Mexico D. F. (Mexico); Salas, P. [Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, Apartado Postal 1-1010, Queretaro 76000 (Mexico); Garcia-Ruiz, A. [UPIICSA, Instituto Politecnico Nacional, Te 950 Col. Granjas-Mexico, 08400 Mexico D.F. (Mexico); Toledo, J.A.; Cortes-Jacome, M.A.; Angeles-Chavez, C. [Programa de Molecular Ingenieria, Instituto Mexicano del Petroleo, Eje Lazaro Cardenas 152, 07730 Mexico D. F. (Mexico); Novaro, O. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, A. P. 20-364, 01000 Mexico D.F. (Mexico)

    2010-04-15

    For the first time, simultaneous production of hydrogen and nanocarbon via catalytic decomposition of methane over Ni-loaded mesoporous Ce-MCM-41 catalysts was investigated. The catalytic performance of the Ni/Ce-MCM-41 catalysts is very stable and the reaction activity remained almost unchanged during 1400 min steam on time at temperatures 540, 560 and 580 C, respectively. The methane conversion level over these catalysts reached 60-75% with a 100% selectivity towards hydrogen. TEM observations revealed that most of the Ni particles located on the tip of the carbon nanofibers/nanotubes in the used catalysts, keeping their exposed surface clean during the test and thus remaining active for continuous reaction without obvious deactivation. Two kinds of carbon materials, graphitic carbon (C{sub g}) as major and amorphous carbon (C{sub A}) as minor were produced in the reaction, as confirmed by XRD analysis and TEM observations. Carbon nanofibers/nanotubes had an average diameter of approximately 30-50 nm and tens micrometers in length, depending on the reaction temperature, reaction time and Ni particle diameter. Four types of carbon nanofibers/nanotubes were detected and their formations greatly depend on the reaction temperature, time on steam and degree of the interaction between the metallic Ni and support. The respective mechanisms of the formation of nanocarbons were postulated and discussed. (author)

  1. Mesoporous silica and organosilica films templated by nanocrystalline chitin.

    Science.gov (United States)

    Nguyen, Thanh-Dinh; Shopsowitz, Kevin E; MacLachlan, Mark J

    2013-11-04

    Liquid crystalline phases can be used to impart order into inorganic solids, creating materials that mimic natural architectures. Herein, mesoporous silica and organosilica films with layered structures and high surface areas have been templated by nanocrystalline chitin. Aqueous suspensions of spindle-shaped chitin nanocrystals were prepared by sequential deacetylation and hydrolysis of chitin fibrils isolated from king crab shells. The nanocrystalline chitin self-assembles into a nematic liquid-crystalline phase that has been used to template silica and organosilica composites. Removal of the chitin template by either calcination or sulfuric-acid-catalyzed hydrolysis gave mesoporous silica and ethylene-bridged organosilica films. The large, crack-free mesoporous films have layered structures with features that originate from the nematic organization of the nanocrystalline chitin.

  2. Highly Aminated Mesoporous Silica Nanoparticles with Cubic Pore Structure

    KAUST Repository

    Suteewong, Teeraporn

    2011-01-19

    Mesoporous silica with cubic symmetry has attracted interest from researchers for some time. Here, we present the room temperature synthesis of mesoporous silica nanoparticles possessing cubic Pm3n symmetry with very high molar ratios (>50%) of 3-aminopropyl triethoxysilane. The synthesis is robust allowing, for example, co-condensation of organic dyes without loss of structure. By means of pore expander molecules, the pore size can be enlarged from 2.7 to 5 nm, while particle size decreases. Adding pore expander and co-condensing fluorescent dyes in the same synthesis reduces average particle size further down to 100 nm. After PEGylation, such fluorescent aminated mesoporous silica nanoparticles are spontaneously taken up by cells as demonstrated by fluorescence microscopy.

  3. Antibacterial performance of nanocrystallined titania confined in mesoporous silica nanotubes.

    Science.gov (United States)

    Cendrowski, Krzysztof; Peruzynska, Magdalena; Markowska-Szczupak, Agata; Chen, Xuecheng; Wajda, Anna; Lapczuk, Joanna; Kurzawski, Mateusz; Kalenczuk, Ryszard J; Drozdzik, Marek; Mijowska, Ewa

    2014-06-01

    In this paper, we study synthesis and characteristics of mesoporous silica nanotubes modified by titanium dioxide, as well as their antimicrobial properties and influence on mitochondrial activity of mouse fibroblast L929. Nanocrystalized titania is confined in mesopores of silica nanotubes and its light activated antibacterial response is revealed. The analysis of the antibacterial effect on Escherichia coli. (ATCC 25922) shows strong enhancement during irradiation with the artificial visible and ultraviolet light in respect to the commercial catalyst and control sample free from the nanomaterials. In darkness, the mesoporous silica/titania nanostructures exhibited antibacterial activity dependent on the stirring speed of the suspension containing nanomaterials. Obtained micrograph proved internalization of the sample into the microorganism trough the cell membrane. The analysis of the mitochondrial activity and amount of lactate dehydrogenase released from mouse fibroblast cells L929 in the presence of the sample were determined with LDH and WST1 assays, respectively. The synthesized silica/titania antibacterial agent also exhibits pronounced photoinduced inactivation of the bacterial growth under the artificial visible and UV light irritation in respect to the commercial catalyst. Additionally, mesoporous silica/titania nanotubes were characterized in details by means of high resolution transmission electron microscopy (HR-TEM), XRD and BET Isotherm.

  4. Nature of active vanadium nanospecies in MCM-41 type catalysts for olefins oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Chanquía, Corina M., E-mail: cchanquia@cab.cnea.gov.ar [Centro Atómico Bariloche, Comisión Nacional de Energía Atómica (CAB-CNEA). Av. Bustillo 9500, R8402AGP, San Carlos de Bariloche, Río Negro (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Avenida Rivadavia 1917, C1033AAJ, Ciudad Autónoma de Buenos Aires (Argentina); Cánepa, Analía L. [Centro de Investigación y Tecnología Química (CITeQ), Universidad Tecnológica Nacional, Facultad Regional Córdoba (UTN-FRC), Maestro López esq. Cruz Roja Argentina, Ciudad Universitaria, 5016, Córdoba Capital (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Avenida Rivadavia 1917, C1033AAJ, Ciudad Autónoma de Buenos Aires (Argentina); Winkler, Elin L. [Centro Atómico Bariloche, Comisión Nacional de Energía Atómica (CAB-CNEA). Av. Bustillo 9500, R8402AGP, San Carlos de Bariloche, Río Negro (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Avenida Rivadavia 1917, C1033AAJ, Ciudad Autónoma de Buenos Aires (Argentina); and others

    2016-06-01

    A multi-technique physicochemical investigation including UV–Vis-DRS, Raman spectroscopy, XPS, ESR and FTIRS with pyridine adsorption was performed to analyze the nature of different vanadium nanospecies present on MCM-41 type catalysts. By employing a direct hydrothermal synthesis, vanadium species were incorporated into siliceous structure mainly as tetrahedrally coordinated isolated V{sup δ+} ions, which would be located inside the wall and on the wall surface of the mesoporous channels. The coexistence of both vanadium oxidation states V{sup 4+} and V{sup 5+} was also revealed. Acidity measurements permitted to infer about the majority presence of Lewis acid sites, which increase with vanadium content. The catalytic performance of these materials was evaluated in the reaction of α-pinene oxidation with H{sub 2}O{sub 2}. The highest intrinsic activity of the sample with lower V loading was attributed to the high dispersion and efficiency of the isolated V{sup δ+} species that actuate as active sites. A mixture of reaction products arising from competitive processes of epoxidation and allylic oxidation was found. - Highlights: • Nature of vanadium nanospecies in mesoporous silicates was investigated. • From hydrothermal sol–gel synthesis, isolated V{sup δ+} sites were mainly generated. • The coexistence of both vanadium oxidation states V{sup 4+} and V{sup 5+} was revealed. • The catalytic performance was evaluated in α-pinene oxidation with H{sub 2}O{sub 2}. • The high catalytic activity is attributed to high dispersion of isolated V{sup δ+} ions.

  5. 功能化MCM-41的制备及对重金属离子的吸附研究%STUDY ON PREPARATION OF FUNCTIONALIZED MCM-41 AND ADSORPTION OF HEAVY METAL IONS

    Institute of Scientific and Technical Information of China (English)

    廖庆玲; 曾黎明; 郭峰; 李玲玲; 袁楚

    2013-01-01

    Functionalized MCM-41 mesoporous materials have been prepared by mercapto silane coupling agent and amino silane coupling agent through two different synthesis routes, respectively. The samples were characterized by TEM, XRD, N2 physical adsorption-desorption, IR, SEM and the adsorption of the heavy metal ions was also tested. The results showed that the adsorption capacity of heavy metal ions by the functionalized mesoporous materials, synthesized at room temperature, increased to some extent. The removal rate of Cu ions and Pt ions by the two-step method amino-functionalized material reached to 96.42% and 99.56%, respectively. The adsorption effect of the one-step functionalized material was affected due to the template agent removed incompletely.%利用巯基硅烷偶联剂和氨基硅烷偶联剂分别通过2种不同的合成方法制备出了功能化的MCM-41介孔材料,使用TEM、XRD、N2吸附-脱附、IR、SEM等手段对产物进行了测试和表征,并将各种介孔材料用于重金属离子的吸附研究.结果表明,常温下成功合成出的功能化介孔材料均在一定程度上提高了对重金属离子的吸附能力,特别是两步法氨基功能化材料对Cu2+和pt2+的去除率分别达到了96.42%和99.56%,但是一步法因模板剂去除不完全而在一定程度上影响了吸附效果.

  6. Efeito do cromo nas propriedades catalíticas da MCM-41 The effect of chromium on the catalytic properties of MCM-41

    Directory of Open Access Journals (Sweden)

    Alcineia Conceição Oliveira

    2005-02-01

    Full Text Available The effect of chromium on the catalytic properties of MCM-41 was evaluated in order to develop new catalysts for the trimethylbenzene transalkylation with benzene to produce ethylbenzene, a high-value aromatic in the industry. It was found that chromium decreases the specific surface area but increases the acidity, turning MCM-41 into an active and selective catalyst for ethylbenzene and toluene production. The coke produced on the catalyst is hydrogenated and mainly located outside the pores and thus can be easily removed. The catalyst is more active and selective than mordenite, a commercial catalyst, and thus more promising for commercial applications.

  7. Mesopori MCM-41 sebagai Adsorben: Kajian Kinetika dan Isotherm Adsorpsi Limbah Cair Tapioka

    Directory of Open Access Journals (Sweden)

    Darmansyah Darmansyah

    2016-06-01

    Full Text Available Telah dilakukan penelitian penggunaan material aluminasilikat MCM-41 sebagai adsorben limbah cair tapioka. Dalam penelitian ini dipelajari permodelan isotermal dan kinetika adsorpsi dari material MCM-41 pada proses adsorpsi limbah cair tapioka. Isotermal Langmuir dan Freundlich digunakan sebagai permodelan isotermal data penelitian. Dari data penelitian yang diperoleh pada konsentrasi COD sebesar 416 - 784 mg/L, proses adsorpsi limbah cair tapioka oleh MCM-41 sesuai dengan pendekatan isothermal Langmuir.  Kapasitas maksimum adsorpsi MCM-41 diperoleh dari pendekatan Langmuir adalah sebesar 15,92 mg/g. Model kinetika pseudo-orde pertama dan pseudo-orde kedua digunakan untuk analisis kinetika adsorpsi pada data penelitian. Model kinetik pseudo-orde pertama yang sesuai dengan proses adsorpsi limbah cair tapioka dengan laju penyerapan adalah 7,48 x 10-2 dan 7,37 x 10-2 g/(min-mg untuk konsentrasi awal secara berturut-turut adalah 608 dan 784 mg/L.

  8. SAXS andalysis of interface in organo—modified mesoporous silica

    Institute of Scientific and Technical Information of China (English)

    ZhiHongLi; YanJunGong; DongWu; YuHanSun; JunWang; YiLiu; BaozhongDon

    2001-01-01

    A small-angle x-ray scattering(SAXS)technique using synchrotron radiation as the x-ray source has been employed to characterize the microstructure of mesoporous silica prepared by one-pot template-directed synthesis methodology.The scattering of pure silica agreed with Porod’s law.the scattering of organomodified mesoporous silica showed a negative deviation from Porod’s law,suggesting that an interfacial layer exists between the pores and silica matrix.It was the organic groups comprising the interface,as shown by 29Si cross-polarization magic-angle spinning nuclear magnetic resonance imaging (29Si cp MAS/NMR) and Fourier transform infrared spectroscopy(FTIR),that caused this negative deviation of SAXS intensity from Porod’s law,and the average thichness of the interfacial layer could be deduced from this negative deviation.Copyright 2001 john Wiley and Sons,Ltd.

  9. Study on the effect of atmospheric gases adsorbed in MnFe2O4/MCM-41 nanocomposite on ortho-positronium annihilation

    Directory of Open Access Journals (Sweden)

    Wiertel Marek

    2015-12-01

    Full Text Available In this paper, results of positron annihilation lifetime spectroscopy (PALS studies of MnFe2O4/MCM-41 nanocomposites in N2 and O2 atmosphere have been presented. In particular, the influence of manganese ferrite loading and gas filling on pick-off ortho-positronium (o-Ps annihilation processes in the investigated samples was a point of interest. Disappearance of the longest-lived o-Ps component with τ5 present in the PAL spectrum of initial MCM-41 mesoporous material in the PAL spectra of MnFe2O4-impregnated MCM-41 measured in vacuum is a result of either a strong chemical o-Ps quenching or the Ps inhibition effects. The intensity I4 of the medium-lived component initially increases, reaching a maximum value for the sample with minimum manganese ferrite content, and then decreases monotonically. Analogous dependence for the intensity I3 of the shortest-lived component shows a maximum at higher MnFe2O4 content. Filling of open pores present in the studied nanocomposites by N2 or O2 at ambient pressure causes partial reappearance of the τ4 and τ5 components, except a sample with maximum ferrite content. The lifetimes of these components measured in O2 are shortened in comparison to that observed in N2 because of paramagnetic quenching. Anti-inhibition and anti-quenching effects of atmospheric gases observed in the MnFe2O4/MCM-41 samples are a result of neutralization of some surface active centers acting as inhibitors and weakening of pick-off annihilation mechanism, respectively.

  10. Ordered mesoporous silica (OMS) as an adsorbent and membrane for separation of carbon dioxide (CO2).

    Science.gov (United States)

    Chew, Thiam-Leng; Ahmad, Abdul L; Bhatia, Subhash

    2010-01-15

    Separation of carbon dioxide (CO(2)) from gaseous mixture is an important issue for the removal of CO(2) in natural gas processing and power plants. The ordered mesoporous silicas (OMS) with uniform pore structure and high density of silanol groups, have attracted the interest of researchers for separation of carbon dioxide (CO(2)) using adsorption process. These mesoporous silicas after functionalization with amino groups have been studied for the removal of CO(2). The potential of functionalized ordered mesoporous silica membrane for separation of CO(2) is also recognized. The present paper reviews the synthesis of mesoporous silicas and important issues related to the development of mesoporous silicas. Recent studies on the CO(2) separation using ordered mesoporous silicas (OMS) as adsorbent and membrane are highlighted. The future prospectives of mesoporous silica membrane for CO(2) adsorption and separation are also presented and discussed.

  11. Synthesis and Characterization of Vanadium Molybdenum Oxynitrides Nanoparticles in the Channels of MCM-41

    Institute of Scientific and Technical Information of China (English)

    ZHANG Cunman; XU Zheng; LIU Qian

    2005-01-01

    Vanaadium molybdenum oxynitrides nanoparticles were synthesized successfully in the channels of MCM-41 after surface modification, vacuum co-impregnation ami nitridation technology. The products were investigated by nitrogen sorption measurement, X-ray powder diffraction ( XRD ), high-resolution transmission electron microscopy (HRTEM), energy dispersive analysis of X-rays (EDAX) and CNH element analysis. The investigation results show that superfine nanoparticles of vanadium molybdenum oxynitrides exist in the channels of MCM-41.

  12. Nano-Titania Photocatalyst Loaded on W-MCM-41 Support and Its Highly Efficient Degradation of Methylene Blue

    Science.gov (United States)

    Shankar, H.; Saravanan, R.; Narayanan, V.; Stephen, A.

    2011-07-01

    Most of the azo dyes produced in textile, printing, paper manufacturing, pulp processing and pharmaceutical industries contain different organic contaminants. These dyes can enter the body through ingestion and the high content in living systems can prove to be carcinogenic. Therefore photocatalytic degradation of such toxic organic compounds in water, in the presence of semiconductor powders has received much attention over the last two decades. Nanocrystalline titanium dioxide, TiO2, is a well studied and commonly used material for photocatalytic applications. However, the control of particle size, monodispersity, large catalytic surface for sufficient adsorption of organic pollutants, recovery and recycle of TiO2 nanoparticles are challenging tasks. Hence in the present study, titania was introduced into the nanopores (2-10 nm size) of MCM-41 to produce stable nanoparticles of uniform size and shape. Further, in order to lengthen the life time of the excited electrons/holes during photoreaction, tungsten atoms were incorporated in to the MCM-41 silica matrix in addition to titania loading.

  13. Preparation of MCM-41 in Industrial Scale and Its Application in Heavy Oil Processing

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A series of MCM-41 molecular sieves have been prepared on an industrial scale, and the effect of preparation factors such as aging temperature, pH values on the structure and pore distribution of the MCM-41 product have been studied by using X-ray diffraction(XRD), thermogravimetric(TG) and electron microscopy (TEM). It is shown that the pH values have a significant effect on the crystallinity of the synthesized product. Under proper conditions, the MCM-41 prepared on an industrial scale has the same performance as the samples prepared on an Lab-scale. The prepared MCM-41 was used as a modifier of zeolite Y for fluid catalytic cracking (FCC) of residual oil. It is shown that the addition of the MCM-41 in the zeolite Y catalyst increases the pore size, and surface area of the catalysts, which helps to increase the yield of gasoline and diesel and decrease the production of gaseous product and carbon deposition in the catalyst. The better performance of the MCM-41 modified zeolite Y catalyst is believed to be due to its adjustment on the acidity and increase of the pore size.

  14. Functionalized mesoporous silica nanoparticles for stimuli-responsive and targeted

    Energy Technology Data Exchange (ETDEWEB)

    Knezevic, Nikola [Iowa State Univ., Ames, IA (United States)

    2009-12-15

    Construction of functional supramolecular nanoassemblies has attracted great deal of attention in recent years for their wide spectrum of practical applications. Mesoporous silica nanoparticles (MSN) in particular were shown to be effective scaffolds for the construction of drug carriers, sensors and catalysts. Herein, we describe the synthesis and characterization of stimuli-responsive, controlled release MSN-based assemblies for drug delivery.

  15. Modeling of N2 adsorption in MCM-41 materials: hexagonal pores versus cylindrical pores.

    Science.gov (United States)

    Ustinov, Eugene A

    2009-07-07

    Low-temperature nitrogen adsorption in hexagonal pores and equivalent cylindrical pores is analyzed using nonlocal density functional theory extended to amorphous solids (NLDFT-AS). It is found that, despite significant difference of the density distribution over the cross-section of the pore, the capillary condensation/evaporation pressure is not considerably affected by the pore shape being slightly lower in the case of hexagonal geometry. However, the condensation/evaporation step in the hexagonal pore is slightly larger than that in the equivalent cylindrical pore because in the latter case the pore wall surface area and, hence, the amount adsorbed at pressures below the evaporation pressure are underestimated by 5%. We show that a dimensionless parameter defined as the ratio of the condensation/evaporation step and the upper value of the amount adsorbed at the condensation/evaporation pressure can be used as an additional criterion of the correct choice of the gas-solid molecular parameters along with the dependence of condensation/evaporation pressure on the pore diameter. Application of the criteria to experimental data on nitrogen adsorption on a series of MCM-41 silica at 77 K corroborates some evidence that the capillary condensation occurs at equilibrium conditions.

  16. Synthesis of cobalt-containing mesoporous catalysts using the ultrasonic-assisted “pH-adjusting” method: Importance of cobalt species in styrene oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Baitao, E-mail: btli@scut.edu.cn; Zhu, Yanrun; Jin, Xiaojing

    2015-01-15

    Cobalt-containing SBA-15 and MCM-41 (Co-SBA-15 and Co-MCM-41) mesoporous catalysts were prepared via ultrasonic-assisted “pH-adjusting” technique in this study. Their physiochemical structures were comprehensively characterized and correlated with catalytic activity in oxidation of styrene. The nature of cobalt species depended on the type of mesoporous silica as well as pH values. The different catalytic performance between Co-SBA-15 and Co-MCM-41 catalysts originated from cobalt species. Cobalt species were homogenously incorporated into the siliceous framework of Co-SBA-15 in single-site Co(II) state, while Co{sub 3}O{sub 4} particles were loaded on Co-MCM-41 catalysts. The styrene oxidation tests showed that the single-site Co(II) state was more beneficial to the catalytic oxidation of styrene. The higher styrene conversion and benzaldehyde selectivity over Co-SBA-15 catalysts were mainly attributed to single-site Co(II) state incorporated into the framework of SBA-15. The highest conversion of styrene (34.7%) with benzaldehyde selectivity of 88.2% was obtained over Co-SBA-15 catalyst prepared at pH of 7.5, at the mole ratio of 1:1 (styrene to H{sub 2}O{sub 2}) at 70 °C. - Graphical abstract: Cobalt-containing mesoporous silica catalysts were developed via ultrasonic-assisted “pH-adjusting” technique. Compared with Co{sub 3}O{sub 4} in Co-MCM-41, the single-site Co(II) state in Co-SBA-15 was more efficient for the styrene oxidation. - Highlights: • Fast and cost-effective ultrasonic technique for preparing mesoporous materials. • Incorporation of Co via ultrasonic irradiation and “pH-adjusting”. • Physicochemical comparison between Co-SBA-15 and Co-MCM-41. • Correlation of styrene oxidation activity and catalyst structural property.

  17. MCM-41 Bound Ruthenium Complex as Heterogeneous Catalyst for Hydrogenation Ⅰ: Effect of Support, Ligand and Solvent on the Catalyst Performance

    Institute of Scientific and Technical Information of China (English)

    YU, Ying-Min; FEI, Jin-Hua; ZHANG, Yi-Ping; ZHENG, Xiao-Ming

    2006-01-01

    The functionalized MCM-41 mesoporous bound ruthenium complex was synthesized and characterized using elemental analysis, atomic absorption spectrophotometer, BET, XRD and FTIR. Hydrogenation of carbon dioxide to formic acid was investigated over these catalysts under supercritical CO2 condition. The effect of reactant gas partial pressure, supports, solvents and ligands on the synthesis of formic acid was studied. These factors could influence the catalyst activity, stability and reuse performance greatly and no byproduct was detected. These promising catalysts also offered the industrial advantages such as easy separation.

  18. Controlled Assembly of Heterobinuclear Sites on Mesoporous Silica: Visible Light Charge-Transfer Units with Selectable Redox Properties

    Energy Technology Data Exchange (ETDEWEB)

    Frei, Heinz; Han, Hongxian; Frei, Heinz

    2008-06-04

    Mild synthetic methods are demonstrated for the selective assembly of oxo-bridged heterobinuclear units of the type TiOCrIII, TiOCoII, and TiOCeIII on mesoporous silica support MCM-41. One method takes advantage of the higher acidity and, hence, higher reactivity of titanol compared to silanol OH groups towards CeIII or CoII precursor. The procedure avoids the customary use of strong base. The controlled assembly of the TiOCr system exploits the selective redox reactivity of one metal towards another (TiIII precursor reacting with anchored CrVI centers). The observed selectivity for linking a metal precursor to an already anchored partner versus formation of isolated centers ranges from a factor of six (TiOCe) to complete (TiOCr, TiOCo). Evidence for oxo bridges and determination of the coordination environment of each metal centers is based on K-edge EXAFS (TiOCr), L-edge absorption spectroscopy (Ce), and XANES measurements (Co, Cr). EPR, optical, FT-Raman and FT-IR spectroscopy furnish additional details on oxidation state and coordination environment of donor and acceptor metal centers. In the case of TiOCr, the integrity of the anchored group upon calcination (350 oC) and cycling of the Cr oxidation state is demonstrated. The binuclear units possess metal-to-metal charge-transfer transitions that absorb deep in the visible region. The flexible synthetic method for assembling the units opens up the use of visible light charge transfer pumps featuring donor or acceptor metals with selectable redox potential.

  19. Immobilized lipase on core-shell structured Fe3O4-MCM-41 nanocomposites as a magnetically recyclable biocatalyst for interesterification of soybean oil and lard.

    Science.gov (United States)

    Xie, Wenlei; Zang, Xuezhen

    2016-03-01

    A core-shell structured Fe3O4-MCM-41 nanocomposite was prepared by means of a surfactant-directed sol-gel process. Candida rugosa lipase was then bound to the magnetic core-shell material by using glutaraldehyde as a cross-linking reagent. The as-prepared Fe3O4-MCM-41 support and the immobilized lipase were characterized in detail using enzyme activity assays, TEM, XRD, FTIR, VSM and nitrogen adsorption-desorption techniques. Results showed that the magnetite nanoparticles were coated with the MCM-41 silica with the formation of core-shell structured materials, and the lipase was successfully immobilized on the core-shell structured support. The catalytic performance of the bound lipase was tested in the interesterification of lard and soybean oil. It was shown that the immobilized lipase had a better catalytic activity towards the interesterification reaction. The slip melting point of the final product was lower than that of the original blend, and the interesterification led to an obvious variation in the microstructure of the product.

  20. Diamine Functionalized Cubic Mesoporous Silica for Ibuprofen Controlled Delivery.

    Science.gov (United States)

    Sivaguru, J; Selvaraj, M; Ravi, S; Park, H; Song, C W; Chun, H H; Ha, C-S

    2015-07-01

    A diamine functionalized cubic mesostructured KIT-6 (N-KIT-6) has been prepared by post-synthetic method using calcined mesoporous KIT-6 with a diamine source, i.e., N-'[3-(tri methoxysilyl)- propyl]'ethylenediamine. The KIT-6 mesoporous silica used for N-KIT-6 was synthesized under weak acidic hydrothermal method using bitemplates, viz., Pluronic P123 and 1-butanol. The synthesized mesoporous materials, KIT-6 and N-KIT-6, have been characterized by the relevant instrumental techniques such as SAXS, N2 sorption isotherm, FT-IR, SEM, TEM and TGA to prove the standard mesoporous materials with the identification of diamine groups. The characterized mesoporous materials, KIT-6 and N-KIT-6, have been extensively used in the potential application of controlled drug delivery, where ibuprofen (IBU) employed as a model drug. The rate of IBU adsorption and release was monitored by UV vis-spectrometer. On the basis of the experimental results of controlled drug delivery system, the results of IBU adsorption and releasing rate in N-KIT-6 are higher than those of KIT-6 because of the higher hydrophobic nature as well as rich basic sites on the surface of inner pore wall silica.

  1. Prototype of low thermal expansion materials: fabrication of mesoporous silica/polymer composites with densely filled polymer inside mesopore space.

    Science.gov (United States)

    Kiba, Shosuke; Suzuki, Norihiro; Okawauchi, Yoshinori; Yamauchi, Yusuke

    2010-09-03

    A prototype of novel low thermal expansion materials using mesoporous silica particles is demonstrated. Mesoporous silica/polymer composites with densely filled polymer inside the mesopore space are fabricated by mechanically mixing both organically modified mesoporous silica and epoxy polymer. The mesopores are easily penetrated by polymers as a result of the capillary force during the mechanical composite processing. Furthermore, we propose a new model of polymer mobility restriction using mesoporous silica with a large pore space. The robust inorganic frameworks covering the polymer effectively restrict the polymer mobility against thermal energy. As a result, the degree of total thermal expansion of the composites is drastically decreased. From the mass-normalized thermal mechanical analysis (TMA) charts of various composites with different amounts of mesoporous silica particles, it is observed that the coefficient of thermal expansion (CTE) values gradually increase with an increase of the polymer amount outside the mesopores. It is proven that the CTE values in the range over the glass-transition temperatures (T(g)) are perfectly proportional to the outside polymer amounts. Importantly, the Y-intercept of the relation equation obtained by a least-square method is the CTE value and is almost zero. This means that thermal expansion does not occur if no polymers are outside the mesopores. Through such a quantative discussion, we clarify that only the outside polymer affects the thermal expansion of the composites, that is, the embedded polymers inside the mesopores do not expand at all during the thermal treatment.

  2. X-ray diffraction structure analysis of MCM-48 mesoporous silica.

    Science.gov (United States)

    Solovyov, Leonid A; Belousov, Oleg V; Dinnebier, Robert E; Shmakov, Alexander N; Kirik, Sergey D

    2005-03-03

    The structure of MCM-48 mesoporous silicate materials has been fully characterized from X-ray diffraction data by applying recently developed methods of mesostructure analysis and full-profile refinement. The pore wall thickness of both as-made and calcined MCM-48 was determined with high precision to be 8.0(1) Angstrom. No regular variations of the wall thickness were detected, but its density was found to be ca. 10% higher in the low-curvature regions. The surfactant density in the pores was assessed around 0.6-0.7 g/cm(3) and was found to have a distinct minimum in the pore center similar to that detected previously in MCM-41. A new extended model function of the density distribution in MCM-48 is proposed on the basis of the structural features that were revealed.

  3. Synthesis and Characterization of Bionanoparticle-Silica Composites and Mesoporous Silica with Large Pores

    Energy Technology Data Exchange (ETDEWEB)

    Niu, Z.; Yang, L.; Kabisatpathy, S.; He, J.; Lee, A.; Ron, J.; Sikha, G.; Popov, B.N.; Emrick, T.; Russell, T. P.; Wang. Q.

    2009-03-24

    A sol-gel process has been developed to incorporate bionanoparticles, such as turnip yellow mosaic virus, cowpea mosaic virus, tobacco mosaic virus, and ferritin into silica, while maintaining the integrity and morphology of the particles. The structures of the resulting materials were characterized by transmission electron microscopy, small angle X-ray scattering, and N{sub 2} adsorption-desorption analysis. The results show that the shape and surface morphology of the bionanoparticles are largely preserved after being embedded into silica. After removal of the bionanoparticles by calcination, mesoporous silica with monodisperse pores, having the shape and surface morphology of the bionanoparticles replicated inside the silica, was produced,. This study is expected to lead to both functional composite materials and mesoporous silica with structurally well-defined large pores.

  4. [Degradation of m-Cresol with Fe-MCM-41 in Catalytic Ozonation].

    Science.gov (United States)

    Sun, Wen-jing; Wang, Ya-min; Wei, Huang-zhao; Wang, Sen; Li, Xu-ning; Li, Jing-mei; Sun, Cheng-lin; An, Lu-yang

    2015-04-01

    Fe-MCM-41 was first used for the treatment of m-cresol in catalytic ozonation. The effect of the percentage of Fe dopping mass, catalyst dosage and the natural concentration of substrate on m-cresol conversion and TOC removal were studied. The structural property of Fe-MCM-41 was characterized by X-ray diffraction, temperature-programmed reduction, Mössbauer spectra and BET of catalysts. The results showed that Fe dopping mass had a great effect on the catalytic activity of Fe-MCM-41 in catalytic ozonation and the optimal percentage of dopping mass was 4.4% (wt). The results showed that with Fe dopping mass increase, the degree of crystallinity became weaker, the crystal surface distance reduced, as well as the specific surface area, pore volume and aperture. γ-Fe2O3 was the only form staying on the surface of MCM-41, and the catalyst had good ferromagnetism and stability. Ozonation played a role of both direct oxidation and indirect oxidation in the reaction, approximately the same ratio. Under the experimental condition of the natural pH of model wastewater,using 4.4% (wt) Fe-MCM-41 as catalyst, natural concentration of m-cresol 500 mg x L(-1), catalyst dosage 0.1 g x L(-1) and reaction time 30 min, m-cresol conversion and TOC removal were 100% and 26.8%, respectively.

  5. Synthesis of mesoporous silica microsphere from dual surfactant

    Directory of Open Access Journals (Sweden)

    Venkatathri Narayanan

    2008-12-01

    Full Text Available A new procedure is reported to synthesis mesoporous silica micro sphere for the first time. In these method two surfactants namely Span 80 and Tween 80 were used. Small angle X ray diffraction and N2 adsorption analysis shows the synthesized material has mesoporous property. The material has spherical morphology with 1-10 µm particle size. Beside the material found to have microcapsule property as observed from the Transmission electron microscopy. The Fourier transform Infrared spectroscopic analysis reveals that the materials are similar to other mesoporous materials. We also encapsulated an UV-absorber Ibuprofen inside the microcapsule, by mixing it before the synthesis. This shows a possibility of the materials in cosmetic applications.

  6. Fluorescent Functionalized Mesoporous Silica for Radioactive Material Extraction

    Energy Technology Data Exchange (ETDEWEB)

    Li, Juan; Zhu, Kake; Shang, Jianying; Wang, Donghai; Nie, Zimin; Guo, Ruisong; Liu, Chongxuan; Wang, Zheming; Li, Xiaolin; Liu, Jun

    2012-08-01

    Mesoporous silica with covalently bound salicylic acid molecules incorporated in the structure was synthesized with a one-pot, co-condensation reaction at room temperature. The as-synthesized material has a large surface area, uniform particle size, and an ordered pore structure as determined by characterization with transmission electron microscopy, thermal gravimetric analysis, and infrared spectra, etc. Using the strong fluorescence and metal coordination capability of salicylic acid, functionalized mesoporous silica (FMS) was developed to track and extract radionuclide contaminants, such as uranyl [U(VI)] ions encountered in subsurface environments. Adsorption measurements showed a strong affinity of the FMS toward U(VI) with a Kd value of 105 mL/g, which is four orders of magnitude higher than the adsorption of U(VI) onto most of the sediments in natural environments. The new materials have a potential for synergistic environmental monitoring and remediation of the radionuclide U(VI) from contaminated subsurface environments.

  7. Chemoradiotherapeutic wrinkled mesoporous silica nanoparticles for use in cancer therapy

    Science.gov (United States)

    Munaweera, Imalka; Koneru, Bhuvaneswari; Shi, Yi; Di Pasqua, Anthony J.; Balkus, Kenneth J., Jr.

    2014-11-01

    Over the last decade, the development and application of nanotechnology in cancer detection, diagnosis, and therapy have been widely reported. Engineering of vehicles for the simultaneous delivery of chemo- and radiotherapeutics increases the effectiveness of the therapy and reduces the dosage of each individual drug required to produce an observable therapeutic response. We here developed a novel chemoradiotherapeutic 1,2-dioleoyl-sn-glycero-3-phosphocholine lipid coated/uncoated platinum drug loaded, holmium-containing, wrinkled mesoporous silica nanoparticle. The materials were characterized with TEM, FTIR, 1H NMR, energy dispersive x-ray, inductively coupled plasma-mass spectrometry, and zeta potential measurements. In vitro platinum drug release from both lipid coated and uncoated chemoradiotherapeutic wrinkled mesoporous silica are reported. Various kinetic models were used to analyze the release kinetics. The radioactivity of the chemoradiotherapeutic nanocarriers was measured after neutron-activation.

  8. Chemoradiotherapeutic wrinkled mesoporous silica nanoparticles for use in cancer therapy

    Energy Technology Data Exchange (ETDEWEB)

    Munaweera, Imalka; Balkus, Kenneth J. Jr., E-mail: Balkus@utdallas.edu, E-mail: Anthony.DiPasqua@unthsc.edu [Department of Chemistry, University of Texas at Dallas, 800 West Campbell Rd., Richardson, Texas 75080 (United States); Koneru, Bhuvaneswari; Shi, Yi; Di Pasqua, Anthony J., E-mail: Balkus@utdallas.edu, E-mail: Anthony.DiPasqua@unthsc.edu [Department of Pharmaceutical Sciences, University of North Texas System College of Pharmacy, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, Texas 76107 (United States)

    2014-11-01

    Over the last decade, the development and application of nanotechnology in cancer detection, diagnosis, and therapy have been widely reported. Engineering of vehicles for the simultaneous delivery of chemo- and radiotherapeutics increases the effectiveness of the therapy and reduces the dosage of each individual drug required to produce an observable therapeutic response. We here developed a novel chemoradiotherapeutic 1,2-dioleoyl-sn-glycero-3-phosphocholine lipid coated/uncoated platinum drug loaded, holmium-containing, wrinkled mesoporous silica nanoparticle. The materials were characterized with TEM, FTIR, {sup 1}H NMR, energy dispersive x-ray, inductively coupled plasma-mass spectrometry, and zeta potential measurements. In vitro platinum drug release from both lipid coated and uncoated chemoradiotherapeutic wrinkled mesoporous silica are reported. Various kinetic models were used to analyze the release kinetics. The radioactivity of the chemoradiotherapeutic nanocarriers was measured after neutron-activation.

  9. Template preparation of twisted nanoparticles of mesoporous silica

    Institute of Scientific and Technical Information of China (English)

    Kui Niu; Zhongbin Ni; Chengwu Fu; Tatsuo Kaneko; Mingqing Chen

    2011-01-01

    Optical isomers of N-lauroyl-L-(or-D-) alanine sodium salt {C12-L-(or-D-)AlaS} surfactants were used for the preparation of mesoporous silica nanoparticles with a twisted hexagonal rod-like morphology. Thermogravimetric analysis (TGA) was used to determine the temperature for template removal. Circular dichroism (CD) spectra of the surfactant solution with various compositions illustrated the formation and supramolecular assembly of protein-like molecular architecture leading to formation of twisted nanoparticles. Scanning electron microscopy (SEM),high-resolution transmission electron microscopy (HRTEM)and X-ray powder diffraction (XRD) patterns of these as-synthesized mesoporous silica confirmed that the twisted morphology of these nanoparticles was closely related to the supramolecular-assembled complex of amino acid surfactants.

  10. Chemoradiotherapeutic wrinkled mesoporous silica nanoparticles for use in cancer therapy

    Directory of Open Access Journals (Sweden)

    Imalka Munaweera

    2014-11-01

    Full Text Available Over the last decade, the development and application of nanotechnology in cancer detection, diagnosis, and therapy have been widely reported. Engineering of vehicles for the simultaneous delivery of chemo- and radiotherapeutics increases the effectiveness of the therapy and reduces the dosage of each individual drug required to produce an observable therapeutic response. We here developed a novel chemoradiotherapeutic 1,2-dioleoyl-sn-glycero-3-phosphocholine lipid coated/uncoated platinum drug loaded, holmium-containing, wrinkled mesoporous silica nanoparticle. The materials were characterized with TEM, FTIR, 1H NMR, energy dispersive x-ray, inductively coupled plasma-mass spectrometry, and zeta potential measurements. In vitro platinum drug release from both lipid coated and uncoated chemoradiotherapeutic wrinkled mesoporous silica are reported. Various kinetic models were used to analyze the release kinetics. The radioactivity of the chemoradiotherapeutic nanocarriers was measured after neutron-activation.

  11. Interconnected mesopores and high accessibility in UVM-7-like silicas

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Cabero, Monica [Universitat de Valencia, Institut de Ciencia dels Materials (Spain); Hungria, Ana B. [Universidad de Cadiz, Departamento de Ciencia de Materiales, Ingenieria Metalurgica y Quimica Inorganica (Spain); Morales, Jose Manuel [Universitat de Valencia, Institut de Ciencia dels Materials (Spain); Tortajada, Marta; Ramon, Daniel [Biopolis S. L. (Spain); Moragues, Alaina; El Haskouri, Jamal; Beltran, Aurelio; Beltran, Daniel; Amoros, Pedro, E-mail: pedro.amoros@uv.es [Universitat de Valencia, Institut de Ciencia dels Materials (Spain)

    2012-08-15

    Nanoparticulated bimodal mesoporous silicas (NBS) have proved to constitute adequate supports in a variety of applications requiring enhanced accessibility to the active sites. Mass-transfer kinetics seems to be highly favoured in UVM-7-derived NBS materials. To understand the mass-diffusion phenomena throughout UVM-7-like supports requires well-grounded knowledge about their pore architecture. 3-D reconstructions of the UVM-7 mesostructure carried out by electron tomography reveal the existence of a true hierarchic connectivity involving both inter- and intra-nanoparticle pores. This connectivity makes self-supported nanoparticulated mesoporous bimodal carbon replicas of the supports feasible to obtaining by nanocasting. Both the temperature-induced mobility of gold nanodomains and the fast and efficient enzyme adsorption in UVM-7-like silicas are examples of non-constrained diffusion processes happening inside such an open network.

  12. Morin Flavonoid Adsorbed on Mesoporous Silica, a Novel Antioxidant Nanomaterial

    OpenAIRE

    Arriagada, Francisco; Correa, Olosmira; Günther, Germán; Nonell, Santi; Mura, Francisco; Olea-Azar, Claudio; MORALES, JAVIER

    2016-01-01

    Morin (2´,3, 4´,5,7-pentahydroxyflavone) is a flavonoid with several beneficial health effects. However, its poor water solubility and it sensitivity to several environmental factors avoid its use in applications like pharmaceutical and cosmetic. In this work, we synthetized morin-modified mesoporous silica nanoparticles (AMSNPs-MOR) as useful material to be used as potential nanoantioxidant. To achieve this, we characterized its adsorption kinetics, isotherm and the antioxidant capacity as h...

  13. Effect of Co Mo/HSO{sub 3}-functionalized MCM-41 over heavy oil

    Energy Technology Data Exchange (ETDEWEB)

    Schacht, P.; Ramirez G, M.; Ramirez, S. [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas No. 152, 07730 Mexico D. F. (Mexico); Aguilar P, J.; Norena F, L. [Universidad Autonoma Metropolitana, Unidad Azcapotzalco, Av. San Pablo No. 180, 02200 Mexico D. F. (Mexico); Abu, I., E-mail: pschacha@imp.m [University of Calgary, Department of Chemical and Petroleum Engineering, 2500 University Drive NW, Calgary, Alberta T2N 1N4 (Canada)

    2010-07-01

    The potential of Co-Mo metals supported on functionalized MCM-41 as catalyst to hydrodesulfurization of heavy oil has been explored in this work. The MCM-41 functionalized sample was synthesized according to method previously reported into the support by simultaneous impregnation. The catalyst was characterized by specific surface area and X-ray diffraction. The pore channel of MCM-41 was confirmed by transmission electronic microscopy and infra red spectroscopy. Catalytic activity tests were carried out using heavy oil from Gulf of Mexico. The API gravity was increased from 12.5 to 20.2, the kinematics viscosity was decreased from 18,700 to 110 c St at 298 K, the contents of asphaltene and sulfur were also reduced. (Author)

  14. Fuels by Waste Plastics Using Activated Carbon, MCM-41, HZSM-5 and Their Mixture

    Directory of Open Access Journals (Sweden)

    Miskolczi Norbert

    2016-01-01

    Full Text Available Waste material was pyrolyzed in a horizontal tubular reactor at 530-540°C using different catalysts, such as activated carbon, MCM-41, HZSM-5 and their mixtures. Products were investigated by gas-chromatography, EDXRFS and standardized methods. Catalysts significantly affected the yields of volatiles; e.g. HZSM-5 catalyst increased especially the yield of gaseous hydrocarbons, while MCM-41 catalyst was responsible for increasing the pyrolysis oil yield. Synergistic effects were found using mixtures of different catalysts. Furthermore the catalysts modified the main carbon frame of the products. Pyrolysis oil obtained over HZSM-5 catalyst contained large amounts of aromatics, while MCM-41 catalyst mainly isomerized the carbon frame. Regarding contaminants it was concluded, that the sulphur content could be significantly decreased by activated carbon, however it had only a slight effect to the other properties of the products.

  15. Modified MCM-41 as a drug delivery system for acetylsalicylic acid

    Science.gov (United States)

    Vyskočilová, Eliška; Luštická, Ivana; Paterová, Iva; Machová, Libuše; Červený, Libor

    2014-12-01

    The modification of prepared MCM-41 by different groups (amino, chloro and oxo) was studied. Prepared materials were treated by acetylsalicylic acid and hybrid materials were characterized, compared from the point of view of immobilized amount of active substance. The highest amount of acetylsalicylic acid was detected using methyl-tert- butyl ether as a solvent and MCM-41 without modification after 1 h (0.35 g per 1 g of the support) or MCM modified by amino group after 5 h (0.37 g per 1 g of the support) as a support. Using amino modified MCM, the longer treatment by acetylsalicylic acid converged to the equilibrium and after 24 h the immobilized amount was 0.3 g per 1 g. A dissolution in vitro study was carried out, comparing the stability of formed interactions. The slowest dissolution was detected using non-modified MCM-41 and oxo modified material.

  16. Adsorption behavior of natural anthocyanin dye on mesoporous silica

    Science.gov (United States)

    Kohno, Yoshiumi; Haga, Eriko; Yoda, Keiko; Shibata, Masashi; Fukuhara, Choji; Tomita, Yasumasa; Maeda, Yasuhisa; Kobayashi, Kenkichiro

    2014-01-01

    Because of its non-toxicity, naturally occurring anthocyanin is potentially suitable as a colorant for foods and cosmetics. To the wider use of the anthocyanin, the immobilization on the inorganic host for an easy handling as well as the improvement of the stability is required. This study is focused on the adsorption of significant amount of the natural anthocyanin dye onto mesoporous silica, and on the stability enhancement of the anthocyanin by the complexation. The anthocyanin has successfully been adsorbed on the HMS type mesoporous silica containing small amount of aluminum. The amount of the adsorbed anthocyanin has been increased by modifying the pore wall with n-propyl group to make the silica surface hydrophobic. The light fastness of the adsorbed anthocyanin has been improved by making the composite with the HMS samples containing aluminum, although the degree of the improvement is not so large. It has been proposed that incorporation of the anthocyanin molecule deep inside the mesopore is required for the further enhancement of the stability.

  17. Immobilization of mesoporous silica particles on stainless steel plates

    Science.gov (United States)

    Pasqua, Luigi; Morra, Marco

    2017-03-01

    A preliminary study aimed to the nano-engineering of stainless steel surface is presented. Aminopropyl-functionalized mesoporous silica is covalently and electrostatically anchored on the surface of stainless steel plates. The anchoring is carried out through the use of a nanometric spacer, and two different spacers are proposed (both below 2 nm in size). The first sample is obtained by anchoring to the stainless steel amino functionalized, a glutaryl dichloride spacer. This specie forms an amide linkage with the amino group while the unreacted acyl groups undergo hydrolysis giving a free carboxylic group. The so-obtained functionalized stainless steel plate is used as substrate for anchoring derivatized mesoporous silica particles. The second sample is prepared using 2-bromo-methyl propionic acid as spacer (BMPA). Successively, the carboxylic group of propionic acid is condensed to the aminopropyl derivatization on the external surface of the mesoporous silica particle through covalent bond. In both cases, a continuous deposition (coating thickness is around 10 μm) is obtained, in fact, XPS data do not reveal the metal elements constituting the plate. The nano-engineering of metal surfaces can represent an intriguing opportunity for producing long-term drug release or biomimetic surface.

  18. Synthesis, characterization and photocatalytic activity of nanotitania loaded W-MCM-41

    Science.gov (United States)

    Shankar, H.; Rajasudha, G.; Karthikeyan, A.; Narayanan, V.; Stephen, A.

    2008-08-01

    Nanocrystalline titanium oxide (TiO2) is a promising material as a photocatalyst for photodecomposition of hazardous organic pollutants under illumination, because it is cheap, safe, environmentally benign, and chemically stable. However, the control of particle size and monodispersity of TiO2 is a challenging task. The use of MCM-41, an inorganic template of uniform pore size (2-10 nm), can overcome this difficulty and produce stable nanoparticles of uniform size and shape. In an attempt to extend light absorption of the TiO2-based photocatalyst towards the visible light range and eliminate the rapid recombination of excited electrons/holes during photoreaction, a new photocatalyst (25%TiO2-loaded W-MCM-41) powder was prepared. W-MCM-41, with different ratios of Si to W (Si/W = 25, 50, 75), was synthesized by a hydrothermal method and loaded with 25 wt% TiO2 utilizing a sol-gel method. In order to compare the photocatalytic activity of our sample, titania-loaded plain MCM-41 was also prepared. These materials were characterized by various physiochemical techniques such as UV-visible absorption spectroscopy, x-ray diffraction, nitrogen adsorption-desorption isotherm measurement, Fourier transform infrared (FT-IR) spectroscopy, and transmission electron microscopy. The photocatalytic activity of the prepared samples was evaluated using methyl orange as a model organic compound. It was found that the photodegradation ability of 25% TiO2-loaded W-MCM-41 was highly related to the amount of W atoms present in the sample; the optimum atomic ratio of Si to W was 25. It has been confirmed that the recombination rate of electrons/holes in 25%TiO2/W-MCM-41 declined due to the existence of W atoms in the sample.

  19. Development of MCM-41 based catalysts for the photo-Fenton's degradation of dye pollutants

    Science.gov (United States)

    Lam, Leung Yuk Frank

    The continuous advancement in most industries has resulted in serious water pollution problems. The industrial effluents contain a variety of highly toxic organics such as dye pollutants. Numerous processes have been demonstrated for treating such pollutants. Among them, photo-Fenton's reaction is effective for organic mineralization by hydroxyl radicals generated from the Fenton's reagents (Fe2+ and H2O2). However, there is a drawback in that it requires a separation system to recover the homogeneous ferrous ion in the treated wastewater. In this research, new heterogeneous Fenton's catalysts are developed to solve such a problem and to achieve an efficient mineralization of dye pollutants. Two methods for catalyst preparation, including sol-gel hydrothermal (SG) and metal-organic chemical vapor deposition (MOCVD) techniques, were studied in this work. For SG-prepared catalysts, the iron element was successfully doped into the MCM-41 structure. These catalysts demonstrated a good catalytic efficiency but leaching of metal ions from the developed catalyst was found. In the MOCVD technique, a rotated tubular reactor system was developed to synthesize Fe/MCM-41 catalyst with uniform metal dispersion. It was found that using oxygen as a carrier gas during metal deposition was able to increase the stability of the deposited metal. In degradation of a model dye pollutant, Orange II, a total of 85% TOC mineralization was achieved at pH 3. A disadvantage of using Fe/MCM-41 was the reduced efficiency at higher pH. Cu/MCM-41 was thus developed and showed better catalytic activities than Fe/MCM-41 at neutral pH. Having the specific catalytic properties of Fe/MCM-41 and Cu/MCM-41, bimetallic (Fe+Cu) catalysts supported on MCM-41 were developed which show better activities in the Orange II mineralization than those monometallic (Fe or Cu) catalysts. The preparation conditions of the catalysts were experimentally optimized. The effects of catalyst dosage, metal loading

  20. A novel, efficient and facile method for the template removal from mesoporous materials

    KAUST Repository

    Chen, Lu

    2014-11-12

    © 2014, Jilin University, The Editorial Department of Chemical Research in Chinese Universities and Springer-Verlag GmbH. A new catalytic-oxidation method was adopted to remove the templates from SBA-15 and MCM-41 mesoporous materials via Fenton-like techniques under microwave irradiation. The mesoporous silica materials were treated with different Fenton agents based on the template’s property and textural property. The samples were characterized by powder X-ray diffraction(XRD) measurement, N2 adsorption-desorption isotherms, infrared spectroscopy, 29Si MAS NMR and thermo gravimetric analysis(TGA). The results reveal that this is an efficient and facile approach to the thorough template-removal from mesoporous silica materials, as well as to offering products with more stable structures, higher BET surface areas, larger pore volumes and larger quantity of silanol groups.

  1. Adsorption of L-phenylalanine onto mesoporous silica

    Energy Technology Data Exchange (ETDEWEB)

    Goscianska, Joanna; Olejnik, Anna; Pietrzak, Robert, E-mail: pietrob@amu.edu.pl

    2013-11-01

    Mesoporous silica materials, such as SBA-3, SBA-15, SBA-16 and KIT-6 were synthesized using tetraethyl orthosilicate as the silica source and different surfactants as templates. The products were characterised by a number of techniques, including low-temperature nitrogen sorption, X-ray diffraction and transmission electron microscopy. Results of the studies confirmed the ordered mesoporous structures of all silica samples obtained. Adsorption of L-phenylalanine on various mesoporous adsorbents was studied from solutions with different pH (5.6–9.4). Maximum sorption capacity was observed at pH 5.6, which is close to the isoelectric point of L-phenylalanine (pI = 5.48). Above this pH value, the amount of adsorbed amino acid decreased. In the range of equilibrium concentration (pH 5.6), the adsorption capacities of ordered silica samples decreased in the following order: KIT-6 (420 μmol g{sup −1}) > SBA-15 (389 μmol g{sup −1}) > SBA-16 (357 μmol g{sup −1}) > SBA-3 (219 μmol g{sup −1}). The lowest sorption capacity towards L-phenylalanine was found for SBA-3 despite the fact that it showed the largest surface area, which can be explained assuming that part of the pores in SBA-3 can be inaccessible to L-phenylalanine molecules. Large pore size of KIT-6 and SBA-15 permitted the amino acid molecule to enter into the pores of these mesoporous molecular sieves. - Highlights: • SBA-3, SBA-15, SBA-16, KIT-6 materials were prepared by hydrothermal method. • Ordered mesoporous silicas are promising as adsorbents of L-phenylalanine. • Adsorption of L-phenylalanine was studied from solutions with different pH. • Sorption capacities decrease in the following order: KIT-6 > SBA-15 > SBA-16 > SBA-3. • Large pore size of KIT-6 and SBA-15 permit the amino acid to enter into the pores.

  2. 载体MCM-41对Tb(aspirin)3phen发光性能的影响%Effect of Host MCM-41 on the Luminescence Properties of Tb (aspirin)3phen

    Institute of Scientific and Technical Information of China (English)

    彭春佳; 魏长平; 祝翠梅

    2008-01-01

    在室温下,乙二胺环境中合成了高度有序的介孔材料MCM-41,并将经热处理的发光客体Tb(aspi-rin)3phen组装进其孔道,通过激发发射光谱对其光致发光性能进行了研究.结果表明,Tb(aspirin)3phen240~375 nm区间的宽激发峰归属于配体aspirin羰基n→π*跃迁、苯环,π→π*跃迁,和phen的杂菲基团吸收,Tb3+的特征发射是由于Antenna效应引起的.相对于纯Tb(aspirin)3phen,Tb(aspirin)3phen-MCM-41B和Tb(aspirin)3phen/MCM-41A的激发谱带出现了明显的分裂,而Tb(aspirin)3phen-MCM-41A只在353nm处剩下了相对较窄的单峰.Tb(aspirin)3phen-MCM-41B,Tb(aspirin)3phen/MCM-41A和Tb(aspirin)3phen-MCM-41A的短波段激发峰依次减弱消失,长波段激发峰逐渐增强,而405 nm发射峰强度IL和544 nm发射峰强度Iln的比值I(I=IL/Iln)依次减小.MCM-41骨架与Tb(aspirin)3phen成键后,不同程度降低了配体aspirin和phen单重态S1和三重态T1能级,且对phen的影响大于aspirin.不同的MCM-41表面晶格场对配体能级的影响顺序为:MCM-41B外表面>MCM-41A外表面>MCM-41A内表面.I值可定性表示MCM-41表面晶格场对配体能级影响程度和MCM-41表面Tb(aspirin)3phen的含量.

  3. Anomalous dynamics of aqueous solutions of di-propylene glycol methylether confined in MCM-41 by quasielastic neutron scattering

    Science.gov (United States)

    Swenson, Jan; Elamin, Khalid; Chen, Guo; Lohstroh, Wiebke; Sakai, Victoria Garcia

    2014-12-01

    The molecular dynamics of solutions of di-propylene glycol methylether (2PGME) and H2O (or D2O) confined in 28 Å pores of MCM-41 have been studied by quasielastic neutron scattering and differential scanning calorimetry over the concentration range 0-90 wt.% water. This system is of particular interest due to its pronounced non-monotonic concentration dependent dynamics of 2PGME in the corresponding bulk system, showing the important role of hydrogen bonding for the dynamics. In this study we have elucidated how this non-monotonic concentration dependence is affected by the confined geometry. The results show that this behaviour is maintained in the confinement, but the slowest diffusive dynamics of 2PGME is now observed at a considerably higher water concentration; at 75 wt.% water in MCM-41 compared to 30 wt.% water in the corresponding bulk system. This difference can be explained by an improper mixing of the two confined liquids. The results suggest that water up to a concentration of about 20 wt.% is used to hydrate the hydrophilic hydroxyl surface groups of the silica pores, and that it is only at higher water contents the water becomes partly mixed with 2PGME. Hence, due to this partial micro-phase separation of the two liquids larger, and thereby slower relaxing, structural entities of hydrogen bonded water and 2PGME molecules can only be formed at higher water contents than in the bulk system. However, the Q-dependence is unchanged with confinement, showing that the nature of the molecular motions is preserved. Thus, there is no indication of localization of the dynamics at length scales of less than 20 Å. The dynamics of both water and 2PGME is strongly dominated by translational diffusion at a temperature of 280 K.

  4. Anomalous dynamics of aqueous solutions of di-propylene glycol methylether confined in MCM-41 by quasielastic neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Swenson, Jan, E-mail: jan.swenson@chalmers.se; Elamin, Khalid; Chen, Guo [Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg (Sweden); Lohstroh, Wiebke [Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Lichtenbergstr. 1, 85748 Garching (Germany); Sakai, Victoria Garcia [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0QX Oxfordshire (United Kingdom)

    2014-12-07

    The molecular dynamics of solutions of di-propylene glycol methylether (2PGME) and H{sub 2}O (or D{sub 2}O) confined in 28 Å pores of MCM-41 have been studied by quasielastic neutron scattering and differential scanning calorimetry over the concentration range 0–90 wt.% water. This system is of particular interest due to its pronounced non-monotonic concentration dependent dynamics of 2PGME in the corresponding bulk system, showing the important role of hydrogen bonding for the dynamics. In this study we have elucidated how this non-monotonic concentration dependence is affected by the confined geometry. The results show that this behaviour is maintained in the confinement, but the slowest diffusive dynamics of 2PGME is now observed at a considerably higher water concentration; at 75 wt.% water in MCM-41 compared to 30 wt.% water in the corresponding bulk system. This difference can be explained by an improper mixing of the two confined liquids. The results suggest that water up to a concentration of about 20 wt.% is used to hydrate the hydrophilic hydroxyl surface groups of the silica pores, and that it is only at higher water contents the water becomes partly mixed with 2PGME. Hence, due to this partial micro-phase separation of the two liquids larger, and thereby slower relaxing, structural entities of hydrogen bonded water and 2PGME molecules can only be formed at higher water contents than in the bulk system. However, the Q-dependence is unchanged with confinement, showing that the nature of the molecular motions is preserved. Thus, there is no indication of localization of the dynamics at length scales of less than 20 Å. The dynamics of both water and 2PGME is strongly dominated by translational diffusion at a temperature of 280 K.

  5. Structure/Property Relationships of Poly(L-lactic Acid/Mesoporous Silica Nanocomposites

    Directory of Open Access Journals (Sweden)

    Javier Gudiño-Rivera

    2013-01-01

    Full Text Available Biodegradable poly(L-lactic acid (PLLA/mesoporous silica nanocomposites were prepared by grafting L-lactic acid oligomer onto silanol groups at the surface of mesoporous silica (SBA-15. The infrared results showed that the lactic acid oligomer was grafted onto the mesoporous silica. Surface characterization of mesoporous silica proved that the grafted oligomer blocked the entry of nitrogen into the mesopores. Thermal analysis measurements showed evidence that, once mixed with PLLA, SBA-15 not only nucleated the PLLA but also increased the total amount of crystallinity. Neat PLLA and its nanocomposites crystallized in the same crystal habit and, as expected, PLLA had a defined periodicity compared with the nanocomposites. This was because the grafted macromolecules on silica tended to cover the lamellar crystalline order. The g-SBA-15 nanoparticles improved the tensile moduli, increasing also the tensile strength of the resultant nanocomposites. Overall, the silica concentration tended to form a brittle material.

  6. Fabrication of the novel core-shell MCM-41@mTiO{sub 2} composite microspheres with large specific surface area for enhanced photocatalytic degradation of dinitro butyl phenol (DNBP)

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Xiao-Na; Wang, Hui-Long, E-mail: hlwang@dlut.edu.cn; Li, Zhen-Duo; Huang, Zhi-Qiang; Qi, Hui-Ping; Jiang, Wen-Feng

    2016-05-30

    Graphical abstract: The mesoporous MCM-41@mTiO{sub 2} composite microspheres with core/shell structure, well-crystallized mesoporous TiO{sub 2} layer, high specific surface, large pore volume and excellent photocatalytic activity were synthesized by combining sol-gel and simple hydrothermal treatment. - Highlights: • The mesoporous MCM-41@mTiO{sub 2} composite was synthesized successfully. • The composite was facilely prepared by combining sol-gel and hydrothermal method. • The composite exhibited high photocatalytic degradation activity for DNBP. • The composite photocatalyst has excellent reproducibility. - Abstract: The mesoporous MCM-41@mTiO{sub 2} core-shell composite microspheres were synthesized successfully by combining sol-gel and simple hydrothermal treatment. The morphology and microstructure characteristics of the synthesized materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), N{sub 2} adsorption-desorption measurements, X-ray powder diffraction (XRD), UV–vis diffuse reflectance spectra (UV–vis/DRS) and Fourier transform infrared spectroscopy (FT-IR). The results indicate that the composite material possesses obvious core/shell structure, a pure mesoporous and well-crystallized TiO{sub 2} layer (mTiO{sub 2}), high specific surface area (316.8 m{sup 2}/g), large pore volume (0.42 cm{sup 3}/g) and two different pore sizes (2.6 nm and 11.0 nm). The photocatalytic activity of the novel MCM-41@mTiO{sub 2} composite was evaluated by degrading 2-sec-butyl-4,6-dinitrophenol (DNBP) in aqueous suspension under UV and visible light irradiation. The results were compared with commercial anatase TiO{sub 2} and Degussa P25 and the enhanced degradation were obtained with the synthesized MCM-41@mTiO{sub 2} composite under the same conditions, which meant that this material can serve as an efficient photocatalyst for the degradation of hazardous organic pollutants in wastewaters.

  7. Enhancement in visible light photocatalytic activity by embedding Cu nanoparticles over CuS/MCM-41 nanocomposite

    Science.gov (United States)

    Sohrabnezhad, Sh.; Karamzadeh, M.

    2017-07-01

    This article indicate the biogenic synthesis of copper nanoparticles (Cu NPs) using the borage flowers extract of Borago officinalis over CuS/MCM-41 nanocomposite (NC). No external reducing was utilized in the developed method. The CuS-MCM-41 NC was used as stabilizing agent. The synthesis of CuS nanostructure in MCM-41 material has been realized by hydrothermal method. Their physiochemical properties have been characterized by X-ray diffraction, transmission electron microscopy (TEM), UV-Visible diffuse reflectance spectroscopy, and Fourier transform infrared spectroscopy. On the basis of TEM images, a layer of Cu NPs has been located over CuS/MCM-41 NC with average diameter of 60-80 nm. The results revealed the spherical nature of the prepared Cu NPs with diameter less than 10 nm. The DR spectra of Cu NPs in MCM-41 and CuS-MCM-41 NCs showed surface plasmon resonance bands at 570 and 500-600 nm, respectively. The photocatalytic activity was evaluated under visible light irradiation using the photocatalytic degradation of methylene blue (MB) as a model reaction. The prepared Cu/CuS/MCM-41 nanocomposite microspheres showed higher photodegradation ability for MB than CuS/MCM-41. The degradation of MB achieved up to 80% after 60 min and the nanocomposite could be recycled and reused.

  8. Amine-functionalized magnetic mesoporous silica nanoparticles for DNA separation

    Science.gov (United States)

    Sheng, Wei; Wei, Wei; Li, Junjian; Qi, Xiaoliang; Zuo, Gancheng; Chen, Qi; Pan, Xihao; Dong, Wei

    2016-11-01

    We report a modified approach for the functionalized magnetic mesoporous silica nanoparticles (MMSN) using polymer microspheres incorporated with magnetic nanoparticles in the presence of cetyltrimethylammonium bromide (CTAB) and the core-shell magnetic silica nanoparticles (MSN). These particles were functionalized with amino groups via the addition of aminosilane directly to the particle sol. We then evaluate their DNA separation abilities and find the capacity of DNA binding significantly increased (210.22 μg/mg) compared with normal magnetic silica spheres (138.44 μg/mg) by using an ultraviolet and visible spectrophotometer (UV). The morphologies, magnetic properties, particle size, pore size, core-shell structure and Zeta potential are characterized by Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), Transmission electron microscopy (TEM), Powder X-ray diffraction (XRD), and dynamic light scattering (DLS). This work demonstrates that our MMSN own an excellent potential application in bioseparation and drug delivery.

  9. Crystallization of hollow mesoporous silica nanoparticles.

    Science.gov (United States)

    Drisko, Glenna L; Carretero-Genevrier, Adrian; Perrot, Alexandre; Gich, Martí; Gàzquez, Jaume; Rodriguez-Carvajal, Juan; Favre, Luc; Grosso, David; Boissière, Cédric; Sanchez, Clément

    2015-03-11

    Complex 3D macrostructured nanoparticles are transformed from amorphous silica into pure polycrystalline α-quartz using catalytic quantities of alkaline earth metals as devitrifying agent. Walls as thin as 10 nm could be crystallized without losing the architecture of the particles. The roles of cation size and the mol% of the incorporated devitrifying agent in crystallization behavior are studied, with Mg(2+), Ca(2+), Sr(2+) and Ba(2+) all producing pure α-quartz under certain conditions.

  10. Sustained release of fungicide metalaxyl by mesoporous silica nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Wanyika, Harrison, E-mail: hwanyika@gmail.com [Jomo Kenyatta University of Agriculture and Technology, Department of Chemistry (Kenya)

    2013-08-15

    The use of nanomaterials for the controlled delivery of pesticides is nascent technology that has the potential to increase the efficiency of food production and decrease pollution. In this work, the prospect of mesoporous silica nanoparticles (MSN) for storage and controlled release of metalaxyl fungicide has been investigated. Mesoporous silica nanospheres with average particle diameters of 162 nm and average pore sizes of 3.2 nm were prepared by a sol-gel process. Metalaxyl molecules were loaded into MSN pores from an aqueous solution by a rotary evaporation method. The loaded amount of metalaxyl as evaluated by thermogravimetric analysis was about 14 wt%. Release of the fungicide entrapped in the MSN matrix revealed sustained release behavior. About 76 % of the free metalaxyl was released in soil within a period of 30 days while only 11.5 and 47 % of the metalaxyl contained in the MSN carrier was released in soil and water, respectively, within the same period. The study showed that MSN can be used to successfully store metalaxyl molecules in its mesoporous framework and significantly delay their release in soil.

  11. Sustained release of fungicide metalaxyl by mesoporous silica nanospheres

    Science.gov (United States)

    Wanyika, Harrison

    2013-08-01

    The use of nanomaterials for the controlled delivery of pesticides is nascent technology that has the potential to increase the efficiency of food production and decrease pollution. In this work, the prospect of mesoporous silica nanoparticles (MSN) for storage and controlled release of metalaxyl fungicide has been investigated. Mesoporous silica nanospheres with average particle diameters of 162 nm and average pore sizes of 3.2 nm were prepared by a sol-gel process. Metalaxyl molecules were loaded into MSN pores from an aqueous solution by a rotary evaporation method. The loaded amount of metalaxyl as evaluated by thermogravimetric analysis was about 14 wt%. Release of the fungicide entrapped in the MSN matrix revealed sustained release behavior. About 76 % of the free metalaxyl was released in soil within a period of 30 days while only 11.5 and 47 % of the metalaxyl contained in the MSN carrier was released in soil and water, respectively, within the same period. The study showed that MSN can be used to successfully store metalaxyl molecules in its mesoporous framework and significantly delay their release in soil.

  12. Altervalent cation-doped MCM-41 supported palladium catalysts and their catalytic properties

    Directory of Open Access Journals (Sweden)

    HAIHUI JIANG

    2011-06-01

    Full Text Available Metal cation-doped MCM-41 (M-MCM-41, M = Al, Ce, Co, V or Zr supported Pd catalysts (Pd/M-MCM-41 were prepared by a solution-based reduction method. The catalysts were characterized by X-ray diffraction (XRD analysis, infrared spectroscopy (IR, scanning electron microscopy (SEM and transmission electron microscopy (TEM, and further evaluated by selective hydrogenation of para-chloronitrobenzene (p-CNB in anhydrous ethanol. The metal cation-containing Pd catalysts can efficiently enhance the selectivity for para-chloroaniline (p-CAN. The highest selectivity of 96.5 % in the molar distribution for p-CNB to p-CAN was acquired over Pd (1.8 wt. %/V-MCM-41 (Si/V = 30, molar ratio catalyst, and the corresponding turnover frequency (TOF was 1.24×10-2 mol p-CNB mol-1 Pd s-1. Water molecules adsorbed by the support have important effects on both the catalytic activity of the sample and the selectivity for p-CAN. A water molecule-mediated catalytic hydrogenation is discussed.

  13. On the hydrothermal stability of MCM-41. Evidence of capillary tension-induced effects

    NARCIS (Netherlands)

    Perez, Lidia Lopez; van Eck, Ernst R. H.; Melian-Cabrera, Ignacio

    2016-01-01

    MCM-41's limited hydrothermal stability has been often related to the hydrolysis of Si-O-Si bonds due to the low degree of condensation, its thin walls or a combination of them. In this work, evidence for an additional factor is provided; a physical effect that occurs during the drying of the

  14. Fabrication of the novel core-shell MCM-41@mTiO2 composite microspheres with large specific surface area for enhanced photocatalytic degradation of dinitro butyl phenol (DNBP)

    Science.gov (United States)

    Wei, Xiao-Na; Wang, Hui-Long; Li, Zhen-Duo; Huang, Zhi-Qiang; Qi, Hui-Ping; Jiang, Wen-Feng

    2016-05-01

    The mesoporous MCM-41@mTiO2 core-shell composite microspheres were synthesized successfully by combining sol-gel and simple hydrothermal treatment. The morphology and microstructure characteristics of the synthesized materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption measurements, X-ray powder diffraction (XRD), UV-vis diffuse reflectance spectra (UV-vis/DRS) and Fourier transform infrared spectroscopy (FT-IR). The results indicate that the composite material possesses obvious core/shell structure, a pure mesoporous and well-crystallized TiO2 layer (mTiO2), high specific surface area (316.8 m2/g), large pore volume (0.42 cm3/g) and two different pore sizes (2.6 nm and 11.0 nm). The photocatalytic activity of the novel MCM-41@mTiO2 composite was evaluated by degrading 2-sec-butyl-4,6-dinitrophenol (DNBP) in aqueous suspension under UV and visible light irradiation. The results were compared with commercial anatase TiO2 and Degussa P25 and the enhanced degradation were obtained with the synthesized MCM-41@mTiO2 composite under the same conditions, which meant that this material can serve as an efficient photocatalyst for the degradation of hazardous organic pollutants in wastewaters.

  15. Influencia de la variación de H3[P(W3O104]×H2O sobre mesoporosos MCM-41, en la reacción de isomerización de n-pentano

    Directory of Open Access Journals (Sweden)

    Lynda Belandria

    2010-05-01

    Full Text Available Conversion of n-pentane and selectivity to isomerisation are affected by changes in the acidity of the catalyst. In this study, the mesoporous MCM-41was used as the support, and Pt was incorporated by the method of solid-state ion exchange, and tungsten phosphoric acid (H3 [P (W3O10 4] × H2O (HPW in alcohol solution. The catalytic tests were carried out at 350 °C in hydrogen flow. The catalyst was characterized by the following techniques: XRD, N2 adsorption, TEM, TPD-NH3 and electron diffraction. The 30% HPW/70% (1%Pt/MCM-41 was the most active

  16. In Situ Loading of Drugs into Mesoporous Silica SBA-15.

    Science.gov (United States)

    Wan, Mi Mi; Li, Yan Yan; Yang, Tian; Zhang, Tao; Sun, Xiao Dan; Zhu, Jian Hua

    2016-04-25

    In a new strategy for loading drugs into mesoporous silica, a hydrophilic (heparin) or hydrophobic drug (ibuprofen) is encapsulated directly in a one-pot synthesis by evaporation-induced self-assembly. In situ drug loading significantly cuts down the preparation time and dramatically increases the loaded amount and released fraction of the drug, and appropriate drug additives favor a mesoporous structure of the vessels. Drug loading was verified by FTIR spectroscopy and release tests, which revealed much longer release with a larger amount of heparin or ibuprofen compared to postloaded SBA-15. Besides, the in vitro anticoagulation properties of the released heparin and the biocompatibility of the vessels were carefully assessed, including activated partial thromboplastin time, thrombin time, hemolysis, platelet adhesion experiments, and the morphologies of red blood cells. A concept of new drug-release agents with soft core and hard shell is proposed and offers guidance for the design of novel drug-delivery systems.

  17. 改性中孔分子筛MCM-41的合成研究

    Institute of Scientific and Technical Information of China (English)

    葛牧; 王开明; 李晓奇

    2011-01-01

    采用水热法合成了纯硅中孔分子筛MCM-41(Mobile Crystalline Material简称MCI),用A1、B原子和结构导向剂OP-10对纯硅MCM-41进行了改性,通过IR、SAXRD、N2吸附-脱附、TEM等技术对其物理化学性能进行表征.对于引入Al、B原子制备的改性MCM-41,考察了模板剂比例、Si/Al、Si/B等因素对产品性能的影响.实验结果表明,采用十六烷基三甲基溴化铵(1631)为模板剂、Si/Al、Si/B均为20的工艺条件下可以合成出结晶度高,孔径分布均匀的纳米级棒状改性MCM-41.对于添加OP-10制备的改性MCM-41,考察了模板剂与OP-10的摩尔比对产品性能的影响.实验结果表明,其它条件不变,1631与OP-10的摩尔比为9:2时,样品的孔径扩大,且具有较好的结构有序度.两种改性方式均具有周期短、成本低等特点,适用于工业生产.

  18. The role of curvature in silica mesoporous crystals

    KAUST Repository

    Miyasaka, Keiichi

    2012-02-08

    Silica mesoporous crystals (SMCs) offer a unique opportunity to study micellar mesophases. Replication of non-equilibrium mesophases into porous silica structures allows the characterization of surfactant phases under a variety of chemical and physical perturbations, through methods not typically accessible to liquid crystal chemists. A poignant example is the use of electron microscopy and crystallography, as discussed herein, for the purpose of determining the fundamental role of amphiphile curvature, namely mean curvature and Gaussian curvature, which have been extensively studied in various fields such as polymer, liquid crystal, biological membrane, etc. The present work aims to highlight some current studies devoted to the interface curvature on SMCs, in which electron microscopy and electron crystallography (EC) are used to understand the geometry of silica wall surface in bicontinuous and cage-type mesostructures through the investigation of electrostatic potential maps. Additionally, we show that by altering the synthesis conditions during the preparation of SMCs, it is possible to isolate particles during micellar mesophase transformations in the cubic bicontinuous system, allowing us to view and study epitaxial relations under the specific synthesis conditions. By studying the relationship between mesoporous structure, interface curvature and micellar mesophases using electron microscopy and EC, we hope to bring new insights into the formation mechanism of these unique materials but also contribute a new way of understanding periodic liquid crystal systems. © 2012 The Royal Society.

  19. Silver nanoparticles incorporated onto ordered mesoporous silica from Tollen's reagent

    Science.gov (United States)

    Zienkiewicz-Strzałka, M.; Pasieczna-Patkowska, S.; Kozak, M.; Pikus, S.

    2013-02-01

    Noble metal nanostructures supported on mesoporous silica are bridge between traditional silica adsorbents and modern catalysts. In this work the Ag/SBA-15 mesoporous materials were synthesized and characterized. Various forms of nanosilver supported on ordered mesoporous template have been successfully obtained via proposed procedures. In all synthesized materials, Tollen's reagent (diammine silver complex [Ag(NH3)2]+) was used as a silver source. Silver nanoparticles were prepared by reduction of ammoniacal silver complex by formaldehyde in the solution of stabilizer. After reduction, Ag nanoparticles could be deposited on SBA-15, or added during traditional synthesis of SBA-15 giving silver or silver chloride nanoparticles in the combination with porous silica. Silver nanostructures as nanoparticles or nanowires were also embedded onto the SBA-15 by incipient wetness impregnation of silver ions. Absorbed silver ions were next reduced under hydrogen at high temperature. There are many advantages of utilized ammoniacal silver complex as a silver source. Proposed method is capable to synthesis of various metal nanostructures with controlled composition and morphology. The silver ammonia complex is composed of two ions surrounding and protecting the central silver ion, so it is possible to obtain very small nanoparticles using simple approach without any functionalization of external and internal surface of SBA-15. This approach allows obtaining greatly small silver nanoparticles on SBA-15 (4 nm) or nanowires depending on the metal loading amount. Moreover, the colloidal silver solution prepared from Tollen's reagent, in the presence of triblock copolymer, remains stable for a long time. Reduction of Tollen's reagent to silver colloidal solution seems to be efficient, fast and interesting approach for the preparation of supported silver nanostructures Obtained samples were characterized by powder X-ray diffraction, small angle X-ray scattering (SAXS), UV

  20. New perspectives in the Fischer-Tropsch synthesis using cobalt supported on mesoporous molecular sieves; Novas perspectivas na sintese de Fischer-Tropsch usando cobalto suportado em peneiras moleculares mesoporosas

    Energy Technology Data Exchange (ETDEWEB)

    Souza, M.J.B.; Silva, A.O.S. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Dept. de Engenharia Quimica; Fernandes Junior, V.J.; Araujo, A.S. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Dept. de Quimica

    2004-07-01

    The conversion of synthesis gas to liquid products via Fischer-Tropsch synthesis (FTS) is an important process in the generation of clean fuels of sulfur and nitrogen compounds. Catalysts based on iron are very used in the conventional process due its cheap manufacture price. Recently the use of cobalt as promoter gave good results. MCM-41 mesoporous materials were discovered by Mobil scientists in the nineties and ever since they have great successes as support and catalyst in several processes of the oil industry as catalytic cracking, reformer and hydrotreating. In this work are presented new alternatives for FTS with the use of cobalt supported on molecular sieves of the type MCM-41. A comparative study with the usual catalysts based on silica was accomplished with different levels of cobalt. (author)

  1. SBA-15 mesoporous silica as a super insulating material

    Science.gov (United States)

    Belmoujahid, Y.; Bonne, M.; Scudeller, Y.; Schleich, D.; Grohens, Y.; Lebeau, B.

    2015-07-01

    The thermal insulation behavior of ordered mesoporous silica SBA-15 aggregates heat treated at 300 ∘C was studied. An important decrease in the effective thermal conductivity according to the increase of the apparent density was observed. A thermal conductivity value less than 25 mW.m-1.K-1 was reached during the compaction phenomenon. Results of thermal conductivity were correlated to the electron microscopy observations and physicochemical data (X-ray diffraction, adsorption/desorption of nitrogen volumetric measurements). These thermal properties make these materials very promising for thermal insulation applications, especially with values inferior to the thermal conductivity of air.

  2. Antibacterial activity of N-halamine decorated mesoporous silica nanoparticles

    Science.gov (United States)

    Xu, Jiarong; Zhang, Yu; Zhao, Yanbao; Zou, Xueyan

    2017-09-01

    N-halamine decorated mesoporous silica nanoparticles (mSiO2/halamine NPs) were prepared by coating mSiO2 NPs with poly (1-allylhydantoin-co-methyl methacrylate) (AH-co-MMA) by the aid of the radical polymerization, followed by chlorination treatment. The sterilizing effect on the bacterial strain is investigated by incubating Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Results indicated that the mSiO2/halamine NPs had excellent antibacterial activity and no significant change occurred in antibacterial efficiency after five recycle experiments.

  3. FACTORES QUE AFECTAN LA TEXTURA Y ESTRUCTURA DE Ti(R)-MCM-41 FACTORES QUE AFECTAN LA TEXTURA Y ESTRUCTURA DE Ti(R)-MCM-41

    OpenAIRE

    J. Ramírez Solís; T. Klimova Berestneva; J. M. Martínez R.

    2012-01-01

    Se ha estudiado el efecto que tienen el método de remoción del surfactante y el contenido de titanio sobre la estructura y propiedades texturales de los materiales mesoporosos Ti-MCM-41. Los sólidos sintetizados fueron caracterizados por fisisorción de N2, fluorescencia de rayos X (FRX), difracción de rayos X (DRX), microscopía electrónica de alta resolución (HREM), espectroscopía FT-Raman y de reflectancia difusa UV-vis. (DRS). Entre los dos métodos de remoción del surfactante estudiados, la...

  4. Fabrication of mesoporous silica/polymer composites through solvent evaporation process and investigation of their excellent low thermal expansion property.

    Science.gov (United States)

    Suzuki, Norihiro; Kiba, Shosuke; Yamauchi, Yusuke

    2011-03-21

    We fabricate mesoporous silica/epoxy polymer composites through a solvent evaporation process. The easy penetration of the epoxy polymers into mesopores is achieved by using a diluted polymer solution including a volatile organic solvent. After the complete solvent evaporation, around 90% of the mesopores are estimated to be filled with the epoxy polymer chains. Here we carefully investigate the thermal expansion behavior of the obtained mesoporous silica/polymer composites. Thermal mechanical analysis (TMA) charts revealed that coefficient of linear thermal expansion (CTE) gradually decreases, as the amount of the doped mesoporous silica increases. Compared with spherical silica particle without mesopores, mesoporous silica particles show a greater effect on lowering the CTE values. Interestingly, it is found that the CTE values are proportionally decreased with the decrease of the total amount of the polymers outside the mesopores. These data demonstrate that polymers embedded inside the mesopores become thermally stable, and do not greatly contribute to the thermal expansion behavior of the composites.

  5. MCM-41-Supported Bidentate Phosphine Rhodium Complex: An Efficient and Recyclable Heterogeneous Catalyst for the Hydrosilylation of Olefins%MCM-41-Supported Bidentate Phosphine Rhodium Complex: An Efficient and Recyclable Heterogeneous Catalyst for the Hydrosilylation of Olefins

    Institute of Scientific and Technical Information of China (English)

    胡荣华; 郝文燕; 蔡明中

    2011-01-01

    MCM-41-supported bidentate phosphine rhodium complex (MCM-41-2P-RhC13) was conveniently synthesized from commercially available and cheap γ-aminopropyltriethoxysilane via immobilization on MCM-41, followed by reacting with diphenylphosphinomethanol and rhodium chloride. It was found that the title complex is a highly efficient catalyst for the hydrosilylation of olefins with triethoxysilane and can be recovered and recycled by a simple filtration of the reaction solution and used for at least 10 consecutive trials without any decreases in activity.

  6. Progress of the Application of Mesoporous Silica-Supported Heteropolyacids in Heterogeneous Catalysis and Preparation of Nanostructured Metal Oxides

    Directory of Open Access Journals (Sweden)

    Heyong He

    2010-01-01

    Full Text Available Mesoporous silica molecular sieves are a kind of unique catalyst support due to their large pore size and high surface area. Several methods have been developed to immobilize heteropolyacids (HPAs inside the channels of these mesoporous silicas. The mesoporous silica-supported HPA materials have been widely used as recyclable catalysts in heterogeneous systems. They have shown high catalytic activities and shape selectivities in some reactions, compared to the parent HPAs in homogeneous systems. This review summarizes recent progress in the field of mesoporous silica-supported HPAs applied in the heterogeneous catalysis area and preparation of nanostructured metal oxides using HPAs as precursors and mesoporous silicas as hard templates.

  7. Synthesis of Ti-MCM-41 with Different Alkali Sources and its Catalytic Performance for Oxidation Desulfurization of Thiophene%不同碱源合成Ti-MCM-41及催化氧化-萃取脱除噻吩

    Institute of Scientific and Technical Information of China (English)

    王广建; 张晋; 郭娜娜; 杨志坚

    2013-01-01

      Ti-MCM-41 mesoporous molecular sieves were synthesized by hydrothermal synthesis method with ammonia, NaOH, TMAH as alkali source, separately, and were characterized by SEM, XRD, TEM, FT-IR and BET techniques, respectively. The effects of crystallization time, species of alkali sources and template content on the crystallization process and the transformation of microstructures were investigated. The results suggest that the crystallinity and the ordering degree of the pore structural of Ti-MCM-41 are increased with the increase of the structure stability of the alkali source. The catalytic performance of the prepared Ti-MCM-41 in the catalytic oxidation-extraction process of thiophene with hydroperoxide as oxidant was studied. Ti-MCM-41 shows a relatively high catalysis effect on the oxidation of thiophene; with acetonitrile as solvent, the highest thiophene removal ratio can achieve 90.3%. The extraction processes of thiophene sulfoxide and sulphone are not only influenced by the polarity of extractants, but also related to the structural adaptation of the solvent in the system. The 3H structure in the solvent of nitriles plays an important role in extracting process, the extract ability sequence of the solvent employed in the experiments is as follows:Nitriles>Amide≥Alcohols>Alcohol amine.%  分别以NaOH、氨水、四甲基氢氧化铵为碱源,钛酸四丁酯为钛源,水热法合成了Ti-MCM-41介孔分子筛,采用 SEM、XRD、TEM、FT-IR 和 BET 等手段对合成分子筛进行了表征分析。研究了晶化时间、碱源、模板剂用量对结晶度及微观形貌的影响。结果表明:碱源类型对Ti-MCM-41的晶化过程及其孔道结构存在较大影响,碱源结构越稳定分子筛长程有序性越好。Ti-MCM-41对催化氧化噻吩显示出较高的催化活性,以乙腈为萃取剂时其氧化-萃取脱除率最佳,可达90.3%。萃取移除噻吩的效果与溶剂在体系中的结构适

  8. Solvent free amorphisation for pediatric formulations (minitablets) using mesoporous silica

    DEFF Research Database (Denmark)

    Monsuur, Fred; Choudhari, Yogesh; Reddy, Upendra

    2016-01-01

    silica gel is densely crowded with silanol groups, which can provide hydrogen-bonding possibilities with a drug, potentially resulting in amorphisation. Purpose: Amorphous drugs provide an advantage in solubility; however, their low physical stability always remained concern. Additional there was a need......Introduction: Most silica based amorphisation strategies are using organic solvent loading methods. Towards pediatric formulations this is creating concerns. With this in mind the development of a dry amorphisation strategy was the focus of this study. The high internal surface area of mesoporous...... does not involve organic solvents and is thereby acceptable for pediatric formulations, cost effective and time saving while increasing oral bioavailability of crystalline & poorly water soluble drugs....

  9. HZSM-5/MCM-41 composite molecular sieves for the catalytic cracking of endothermic hydrocarbon fuels: nano-ZSM-5 zeolites as the source

    Science.gov (United States)

    Sang, Yu; Jiao, Qingze; Li, Hansheng; Wu, Qin; Zhao, Yun; Sun, Kening

    2014-12-01

    A series of HZSM-5/MCM-41 composite molecular sieves (HZM-Ns ( x)) were prepared by employing nano-ZSM-5 zeolites with the SiO2/Al2O3 ratios ( x) of 50, 100 and 150 as the source. These materials were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, N2 adsorption-desorption measurement, and NH3 temperature-programmed desorption. The catalytic cracking of endothermic hydrocarbon fuels over the HZM-Ns with n-decane as model was evaluated at atmospheric pressure and 500 °C. The effect of the parent zeolite, mesopore and SiO2/Al2O3 ratio on the structure, acidity, and catalytic performance of HZM-Ns was investigated. The HZM-Ns exhibited a skeletal matrix with nano-sized HZSM-5 particles (200-300 nm) with a controllable acidity well dispersed in and microporous-mesoporous hierarchical pores. The mesoporous structure improved the diffusion of the reactants and products in the pores, and the HZSM-5 nanoparticles uniformly dispersed in the MCM-41 matrix supplied a proper acidity, shorter channels, and a higher specific surface area for reaction. These resulted in a high catalytic activity, a high selectivity to light olefins and a long lifetime for n-decane catalytic cracking. The HZM-N (150) exhibited the excellent conversion, a high selectivity to light olefins and a long lifetime due to low diffusion resistance, high specific surface area, and appropriate acid distribution and strength, with the increasing SiO2/Al2O3 ratio.

  10. Cu-Mo2C/MCM-41: An Efficient Catalyst for the Selective Synthesis of Methanol from CO2

    Directory of Open Access Journals (Sweden)

    Xiaoran Liu

    2016-05-01

    Full Text Available Supported molybdenum carbide (yMo2C/M41 and Cu-promoted molybdenum carbide, using a mechanical mixing and co-impregnation method (xCuyMo2C/M41-M and xCuyMo2C/M41-I on a mesoporous molecular sieve MCM-41, were prepared by temperature-programmed carburization method in a CO/H2 atmosphere at 1073 K, and their catalytic performances were tested for CO2 hydrogenation to form methanol. Both catalysts, which were promoted by Cu, exhibited higher catalytic activity. In comparison to 20Cu20Mo2C/M41-M, the 20Cu20Mo2C/M41-I catalyst exhibited a stronger synergistic effect between Cu and Mo2C on the catalyst surface, which resulted in a higher selectivity for methanol in the CO2 hydrogenation reaction. Under the optimal reaction conditions, the highest selectivity (63% for methanol was obtained at a CO2 conversion of 8.8% over the 20Cu20Mo2C/M41-I catalyst.

  11. Degradability and Clearance of Silicon, Organosilica, Silsesquioxane, Silica Mixed Oxide, and Mesoporous Silica Nanoparticles

    KAUST Repository

    Croissant, Jonas G.

    2017-01-13

    The biorelated degradability and clearance of siliceous nanomaterials have been questioned worldwide, since they are crucial prerequisites for the successful translation in clinics. Typically, the degradability and biocompatibility of mesoporous silica nanoparticles (MSNs) have been an ongoing discussion in research circles. The reason for such a concern is that approved pharmaceutical products must not accumulate in the human body, to prevent severe and unpredictable side-effects. Here, the biorelated degradability and clearance of silicon and silica nanoparticles (NPs) are comprehensively summarized. The influence of the size, morphology, surface area, pore size, and surface functional groups, to name a few, on the degradability of silicon and silica NPs is described. The noncovalent organic doping of silica and the covalent incorporation of either hydrolytically stable or redox- and enzymatically cleavable silsesquioxanes is then described for organosilica, bridged silsesquioxane (BS), and periodic mesoporous organosilica (PMO) NPs. Inorganically doped silica particles such as calcium-, iron-, manganese-, and zirconium-doped NPs, also have radically different hydrolytic stabilities. To conclude, the degradability and clearance timelines of various siliceous nanomaterials are compared and it is highlighted that researchers can select a specific nanomaterial in this large family according to the targeted applications and the required clearance kinetics.

  12. Structrue and Characteristics of Mesoporous Silica Synthesized in Acid Medium and Its Reaction Mechanism

    Institute of Scientific and Technical Information of China (English)

    LEI Jia-heng; ZHAO Jun; CHEN Yong-xi; GUO Li-ping; LIU Dan

    2004-01-01

    Structrue and pore characteristics of the mesoporous silica synthesized in acid medium were studied by means of XRD, HRTEM, BET, FT-IR, DSC-TGA, and the reaction mechanism was also investigated deeply. The results show that mesopores in the sample possess hexagonal arrays obviously, whereas the structure of silica matrix is amorphous. The results also show that the acting mode of silica and CTMA+ inside the mesopores was chemical bonding force. The structure of mesoporous silica was mainly dependent on the aggregational condition of micelle of CTMA+ as well as their liquid-crystallized status. In addition, condensation and dehydration of silicate radicals were accompanied in the process of calcination, which resulted in the mesoporous structure ordered in local range and the pore sizes largening.

  13. Mesoporous silica as carrier of antioxidant for food packaging materials

    Science.gov (United States)

    Buonocore, Giovanna Giuliana; Gargiulo, Nicola; Verdolotti, Letizia; Liguori, Barbara; Lavorgna, Marino; Caputo, Domenico

    2014-05-01

    Mesoporous silicas have been long recognized as very promising materials for the preparation of drug delivery systems. In this work SBA-15 mesoporous silica has been functionalized with amino-silane to be used as carrier of antioxidant compound in the preparation of active food packaging materials exhibiting tailored release properties. Active films have been prepared by loading the antioxidant tocopherol, the purely siliceous SBA-15 and the aminofunctionalized SBA-15 loaded with tocopherol into LDPE matrix trough a two-step process (mixing+extrusion). The aim of the present work is the study of the effect of the pore size and of the chemical functionality of the internal walls of the mesophase on the migration of tocopherol from active LDPE polymer films. Moreover, it has been proved that the addition of the active compound do not worsen the properties of the film such as optical characteristic and water vapor permeability, thus leading to the development of a material which could be favorably used mainly, but not exclusively, in the sector of food packaging.

  14. Adsorptive removal of selected pharmaceuticals by mesoporous silica SBA-15

    Energy Technology Data Exchange (ETDEWEB)

    Bui, Tung Xuan, E-mail: bxtung@gist.ac.kr [Department of Environmental Science and Engineering, Gwangju Institute of Science and Technology (GIST), 261 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712 (Korea, Republic of); Choi, Heechul, E-mail: hcchoi@gist.ac.kr [Department of Environmental Science and Engineering, Gwangju Institute of Science and Technology (GIST), 261 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712 (Korea, Republic of)

    2009-09-15

    The removal of five selected pharmaceuticals, viz., carbamazepine, clofibric acid, diclofenac, ibuprofen, and ketoprofen was examined by batch sorption experiments onto a synthesized mesoporous silica SBA-15. SBA-15 was synthesized and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N{sub 2} adsorption-desorption measurement, and point of zero charge (PZC) measurement. Pharmaceutical adsorption kinetics was rapid and occurred on a scale of minutes, following a pseudo-second-order rate expression. Adsorption isotherms were best fitted by the Freundlich isotherm model. High removal rates of individual pharmaceuticals were achieved in acidic media (pH 3-5) and reached 85.2% for carbamazepine, 88.3% for diclofenac, 93.0% for ibuprofen, 94.3% for ketoprofen, and 49.0% for clofibric acid at pH 3 but decreased with increase in pH. SBA-15 also showed high efficiency for removal of a mixture of 5 pharmaceuticals. Except for clofibric acid (35.6%), the removal of pharmaceuticals in the mixture ranged from 75.2 to 89.3%. Based on adsorption and desorption results, the mechanism of the selected pharmaceuticals was found to be a hydrophilic interaction, providing valuable information for further studies to design materials for the purpose. The results of this study suggest that mesoporous-silica-based materials are promising adsorbents for removing pharmaceuticals from not only surface water but also wastewater of pharmaceutical industrial manufactures.

  15. Study on photocatalytic capacity of PW/MCM-41%PW/MCM-41光催化性能研究

    Institute of Scientific and Technical Information of China (English)

    黄艳芹; 程玉良; 周建伟

    2011-01-01

    PW/MCM-41 has been prepared and characterized by immersion method. The catalytic activity of the photocatalyst in the degradation reaction of photocatalytic simulated dyeing wastewater methylene blue(MB) solution is investigated. The results show that when the catalyst charge number is 30%, mass concentration of catalyst dosage 3.0 g/L,the concentration of methylene blue 10 mg/L,pH=5,and light application time 100 min.the photocatalytic degradation rate is as high as 91% over. Furthermore,the catalyst could be used repeatedly.%以浸渍法制备了负载型光催化剂PW/MCM-41,并对催化剂进行了表征,考察了催化剂在光催化模拟染料废水亚甲基蓝(MB)溶液降解反应中的催化活性.实验结果表明:催化剂负载量为30%、催化剂投加质量浓度为3.0g/L、MB溶液的初始质量浓度为10 mg/L、pH=5、光照时间100 min时,对亚甲基蓝降解率可达91%以上,且催化剂可重复使用.

  16. Fabrication of Mesoporous Silica Shells on Solid Silica Spheres Using Anionic Surfactants and Their Potential Application in Controlling Drug Release

    Directory of Open Access Journals (Sweden)

    Mansour Al-Hoshan

    2012-11-01

    Full Text Available In this work, mesoporous shells were constructed on solid silica cores by employing anionic surfactante. A co-structure directing agent (CSDA has assisted the electrostatic interaction between negatively charged silica particles and the negatively charged surfactant molecules. Synthetic parameters such as reaction time and temperature had a significant impact on the formation of mesoporous silica shelld and their textural properties such as surface area and pore volume. Core-mesoporous shell silica spheres were characterized by small angle X-ray scattering, transmission electron microscopy, and N2 adsorption–desorption analysis. The synthesized particles have a uniformly mesoporous shell of 34–65 nm and possess a surface area of ca. 7–324 m2/g, and pore volume of ca. 0.008–0.261 cc/g. The core-mesoporous shell silica spheres were loaded with ketoprofen drug molecules. The in vitro drug release study suggested that core-mesoporous shell silica spheres are a suitable nanocarrier for drug molecules offering the possibility of having control over their release rate.

  17. Fabrication of mesoporous silica shells on solid silica spheres using anionic surfactants and their potential application in controlling drug release.

    Science.gov (United States)

    El-Toni, Ahmed Mohamed; Khan, Aslam; Ibrahim, Mohamed Abbas; Al-Hoshan, Mansour; Labis, Joselito Puzon

    2012-11-06

    In this work, mesoporous shells were constructed on solid silica cores by employing anionic surfactante. A co-structure directing agent (CSDA) has assisted the electrostatic interaction between negatively charged silica particles and the negatively charged surfactant molecules. Synthetic parameters such as reaction time and temperature had a significant impact on the formation of mesoporous silica shelld and their textural properties such as surface area and pore volume. Core-mesoporous shell silica spheres were characterized by small angle X-ray scattering, transmission electron microscopy, and N(2) adsorption–desorption analysis. The synthesized particles have a uniformly mesoporous shell of 34–65 nm and possess a surface area of ca. 7–324 m2/g, and pore volume of ca. 0.008–0.261 cc/g. The core-mesoporous shell silica spheres were loaded with ketoprofen drug molecules. The in vitro drug release study suggested that core-mesoporous shell silica spheres are a suitable nanocarrier for drug molecules offering the possibility of having control over their release rate.

  18. Immobilization of enzyme (DAAO) on hybrid nanoporous MCF, SBA-15, and MCM-41 materials

    Science.gov (United States)

    Phi, Tien Q.; Le, Hy G.; Vu, Tuan A.; Phan, Thao T. H.; Pham, Huyen T.; Dao, Canh Duc; Dang, Phuong T.

    2011-12-01

    Hybrid nanoporous MCF, SBA-15 and MCM-41 materials were synthesized via hydrothermal treatment and functionalized with 3-aminopropyltriethoxysilane (APTES) via post-synthesis grafting and sequently activated by glutardialdehyde and then were used to immobilize D-amino acid oxidase (DAAO). The amino-functionalized materials were characterized by various techniques: XRD, IR and N2 adsorption-desorption (BET). From characterization results, it indicated that these materials still maintained their structure after functionalization. The data IR and TGA-DTA analysis demonstrated the incorpotation of amine functional groups on the surface of APTES-functionalized samples. The DAAO immobilized on functionalized materials exhibited higher catalytic activity and stability for conversion of cephalosporin C (CPC) compare to those of non-functionalized one. Further more, the catalytic activity as well as stability of enzyme decreased in order MCF > SBA-15 > MCM-41 with the decrease of their pore size.

  19. Preparation, Characterization and Luminescent Properties of MCM-41 Type Materials Impregnated with Rare Earth Complex

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Hybrid materials incorporating Eu-(TTA)3.2H2O(hereafter designated as Eu-TTA, with TTA:thenoyltrifluoroacetone)in unmodified or modified MCM-41 by 3-aminopropyl-triethoxysilane (APTES)were prepared by impregnation method.The obtained materials were characterized using X-ray diffraction(XRD),IR and diffuse reflectance spectroscopy and luminescence spectra.All the hybrid samples exhibited the characteristic emission bands of Eu3+ under UV light excitation at room temperature, and the excitation spectra showed significant blue-shifts compared to the pure rare-earth complex. Although the red emission intensity in the modified hybrid was almost the half of the red emission intensity in the pure Eu-TTA complex at room temperature,the hybrid showed a much higher thermal stability due to the shielding character of the MCM-41host.

  20. Catalytic Synthesis of Isopropyl Benzene over SO42-/ZrO2 -MCM-41

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Super acid catalyst SO2-4-/ZrO2 was introduced into pure silicone MCM-41 via the impregnation method and the catalyst samples obtained at different temperatures were characterized by means of XRD, IR, and Py-IR techniques.The selectively catalytic gas-phase flow reactions of benzene with propene over the catalyst samples were carried out in a made-to-measure high-pressure flow reactor equipped with a thermostat and a condenser. Effect of the preparative condition on the catalytic synthesis of isopropyl benzene over the catalyst samples was tested. The results show that SO2-4/ZrO2-MCM-41 (SZM-41) can be used as a catalyst for the title reaction, in which there are a higher conversion (97%) for the propene and a higher selectivity(93%) for the isopropyl benzene.

  1. Thermal stability and surface acidity of mesoporous silica doubly doped by incorporation of sulfate and zirconium ions

    Energy Technology Data Exchange (ETDEWEB)

    Salas, P. [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas No. 152, 07730 Mexico D.F. (Mexico)]. E-mail: psalas@imp.mx; Chen, L.F. [Departamento de Ingenieria Quimica, Universidad Autonoma Metropolitana-A, Av. San Pablo 180, Col. Reynosa-Tamaulipas, 02200 Mexico D.F. (Mexico); Wang, J.A. [Laboratorio de Catalisis y Materiales, ESIQIE, Instituto Politecnico Nacional, Col. Zacatenco, 07738 Mexico D.F. (Mexico); Armendariz, H. [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas No. 152, 07730 Mexico D.F. (Mexico); Guzman, M.L. [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas No. 152, 07730 Mexico D.F. (Mexico); Montoya, J.A. [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas No. 152, 07730 Mexico D.F. (Mexico); Acosta, D.R. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, A. P. 20-364, 01000 Mexico D.F. (Mexico)

    2005-11-15

    A sulfated Si-Zr-MCM-41 solid with highly ordered mesostructure was synthesized through a templated synthesis route where the CTAB surfactant was used as template. During the synthesis procedure, various amounts of (NH{sub 4}){sub 2}SO{sub 4} were added into the mixed solution of Zr and Si precursors to in situ sulfate the MCM-41 solids, aiming to enhance the acidity and thermal stability. The resultant materials showed a long-range ordered hexagonal arrangement with high surface area larger than 797 m{sup 2}/g and an average pore size distributed at approximate 2.5-2.8 nm. The high-resolution TEM observations confirmed that the order of the mesostructure gained when the molar ratio of SO{sub 4} {sup 2-}/(ZrO{sub 2} + SiO{sub 2}) increased from 0.1 to 0.3 but decreased as it reached 0.5, which is consistent with the results of {sup 29}Si MAS-NMR and XRD analysis. Compared to Si-MCM-41, the (Q{sup 2} + Q{sup 3})/Q{sup 4} ratio derived from the NMR spectra of the Zr-doped sample was higher, indicating that zirconium atoms were incorporated into the silica framework. Unexpectedly, in situ sulfation does not enhance the surface Broensted acidity, most likely due to the sulfur retained within the bulk of the materials; however, it indeed improved the thermal stability of the solid and long-range order of the structure.

  2. Preparation, Characterization and Luminescence of MCM-41 Immobilized Bovine Serum Albumin Composite Material%MCM-41固载牛血清白蛋白复合材料的制备、表征及发光

    Institute of Scientific and Technical Information of China (English)

    魏宇辰; 翟庆洲

    2012-01-01

    In this research, nanoscale MCM-41 molecular sieve was prepared using hydrothermal method and then bovine serum albumin (BSA) was immobilized in the above host to prepare ( MCM-41 )-BSA composite materials by physical adsorption method. Chemical analysis showed that BSA had entered into the above-stated host material and its immobilization amount was 55. 68 mg (BSA)/g (MCM-41). Powder X-ray diffraction (XRD) results indicated that crystallinity degree of composite materials was maintained good and basic frameworks of the molecular sieve were preserved intact and were not destructed due to BSA introduction. The low temperature N2 adsorption-desorption study results at 77 K showed that BSA had already partially entered in the molecular sieve pore channels. The measurement results by scanning electron microscopy (SEM) displayed that the diameter of ( MCM-41) -BSA sample was 100 ± 10 nm. The luminescence study showed that in the (MCM-41)-BSA sample the conformation of BSA was not changed.%本研究首先利用水热法制备出了纳米分子筛MCM-41,然后把牛血清白蛋白(Bovine serum albumin,BSA)物理吸附法固载在主体MCM-41中,制备出(MCM-41)-BSA复合材料.化学分析表明,BSA已进入上述主体材料中,固载量为55.68 mg (BSA)/g(MCM-41).粉末X射线衍射(XRD)结果表明,复合材料的结晶度保持良好,分子筛的基本骨架保存完好没有由于BSA的引入而遭到破坏.77 K低温N2吸附-解吸附的研究结果说明,BSA部分进入了分子筛孔道中.扫描电镜(SEM)测量结果显示,(MCM-41)-BSA样品的直径为100±10 nm.发光研究表明,(MCM-41)-BSA样品中BSA的构象未发生变化.

  3. Molecular Modeling and Adsorption Properties of Ordered Silica-Templated CMK Mesoporous Carbons.

    Science.gov (United States)

    Jain, Surendra Kumar; Pellenq, Roland J-M; Gubbins, Keith E; Peng, Xuan

    2017-03-07

    Realistic molecular models of silica-templated CMK-1, CMK-3, and CMK-5 carbon materials have been developed by using carbon rods and carbon pipes that were obtained by adsorbing carbon in a model MCM-41 pore. The interactions between the carbon atoms with the silica matrix were described using the PN-Traz potential, and the interaction between the carbon atoms was calculated by the reactive empirical bond order (REBO) potential. Carbon rods and pipes with different thicknesses were obtained by changing the silica-carbon interaction strength, the temperature, and the chemical potential of carbon vapor adsorption. These equilibrium structures were further used to obtain the atomic models of CMK-1, CMK-3, and CMK-5 materials using the same symmetry as found in TEM pictures. These models are further refined and made more realistic by adding interconnections between the carbon rods and carbon pipes. We calculated the geometric pore size distribution of the different models of CMK-5 and found that the presence of interconnections results in some new features in the pore size distribution. Argon adsorption properties were investigated using GCMC simulations to characterize these materials at 77 K. We found that the presence of interconnection results greatly improves the agreement with available experimental data by shifting the capillary condensation to lower pressures. Adding interconnections also induces smoother adsorption/condensation isotherms, and desorption/evaporation curves show a sharp jump. These features reflex the complexity of the nanovoids in CMKs in terms of their pore morphology and topology.

  4. Rapid pathogen detection with bacterial-assembled magnetic mesoporous silica.

    Science.gov (United States)

    Lee, Soo Youn; Lee, Jiho; Lee, Hye Sun; Chang, Jeong Ho

    2014-03-15

    We report rapid and accurate pathogen detection by coupling with high efficiency magnetic separation of pathogen by Ni(2+)-heterogeneous magnetic mesoporous silica (Ni-HMMS) and real time-polymerase chain reaction (RT-PCR) technique. Ni-HMMS was developed with a significant incorporation of Fe particles within the silica mesopores by programmed thermal hydrogen reaction and functionalized with Ni(2+) ion on the surface by the wet impregnation process. High abundant Ni(2+) ions on the Ni-HMMS surface were able to assemble with cell wall component protein NikA (nickel-binding membrane protein), which contains several pathogenic bacteria including Escherichia coli O157:H7. NikA protein expression experiment showed the outstanding separation rate of the nikA gene-overexpressed E. coli (pSY-Nik) when comparing with wild-type E. coli (44.5 ± 13%) or not over-expressed E. coli (pSY-Nik) (53.2 ± 2.7%). Moreover, Ni-HMMS showed lower obstacle effect by large reaction volume (10 mL) than spherical core/shell-type silica magnetic nanoparticles functionalized with Ni(2+) (ca. 40 nm-diameters). Finally, the Ni-HMMS was successfully assessed to separate pathogenic E. coli O157:H7 and applied to direct and rapid RT-PCR to quantitative detection at ultralow concentration (1 Log10 cfu mL(-1)) in the real samples (milk and Staphylococcus aureus culture broth) without bacterial amplification and DNA extraction step.

  5. Effect of Incorporation of Inhibitor Loaded Mesoporous Silica on the Corrosion Behavior of Epoxy Coatings

    Directory of Open Access Journals (Sweden)

    Mahdi Yeganeh

    2013-12-01

    Full Text Available In this research, mesoporous silica was applied as the host of corrosion inhibitor (molybdate. The loaded mesoporous silica was dispersed in an epoxy matrix. The composite was then coated on the mild steel plate. Results showed that the corrosion resistance of the scratched epoxy/mesoporous silica loaded by molybdate was better than the one without molybdate or neat epoxy. On the other hand, EDX and FTIR studies showed the release of corrosion inhibitor in the scratched zone. It was due to pH-sensitive release of corrosion inhibitor in the aggressive media. Also, XRD data showed the presence of Mo compounds on the surface of steel.

  6. Core-Shell-structured Dendritic Mesoporous Silica Nanoparticles for Combined Photodynamic Therapy and Antibody Delivery.

    Science.gov (United States)

    Abbaraju, Prasanna Lakshmi; Yang, Yannan; Yu, Meihua; Fu, Jianye; Xu, Chun; Yu, Chengzhong

    2017-07-04

    Multifunctional core-shell-structured dendritic mesoporous silica nanoparticles with a fullerene-doped silica core, a dendritic silica shell and large pores have been prepared. The combination of photodynamic therapy and antibody therapeutics significantly inhibits the cancer cell growth by effectively reducing the level of anti-apoptotic proteins. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. AgBr/nanoAlMCM-41 visible light photocatalyst for degradation of methylene blue dye.

    Science.gov (United States)

    Pourahmad, A; Sohrabnezhad, Sh; Kashefian, E

    2010-12-01

    A novel photocatalytic material was synthesized by dispersion of AgBr in nanoAlMCM-41 material. The AgBr/nanoAlMCM-41 sample shows strong absorption in the visible region because of the plasmon resonance of Ag nanoparticles in AgBr/nanoAlMCM-41. The catalysts were characterized using XRD (X-ray diffraction), UV-visible diffused reflectance spectra (UV-vis DRS) and scanning electron microscopy (SEM). The photocatalytic activity and stability of the synthesized catalysts were evaluated for methylene blue (MB) degradation in aqueous solution in the presence of 200 W tungsten filament Philips lamp. Several parameters were examined, catalyst amount, pH and initial concentration of MB, AgBr loading. The effect of dosage of photocatalyst was studied in the range 0.05-1.00 g/L. It was seen that 0.1 g/L of photocatalyst is an optimum value for the dosage of photocatalyst. The support size was obtained about 9-100 nm. In the same way, the average size of AgBr nanoparticles was about 10nm before visible radiation. After visible radiation the average size of AgBr nanoparticles was about 25 nm.

  8. Sulphonated cobalt phthalocyanine-MCM-41: An active photocatalyst for degradation of 2,4-dichlorophenol

    Energy Technology Data Exchange (ETDEWEB)

    Zanjanchi, M.A., E-mail: zanjanchi@guilan.ac.ir [Department of Chemistry, Faculty of Science, University of Guilan, P.O. Box 1914, Namjoo St., Rasht 41335 (Iran, Islamic Republic of); Ebrahimian, A.; Arvand, M. [Department of Chemistry, Faculty of Science, University of Guilan, P.O. Box 1914, Namjoo St., Rasht 41335 (Iran, Islamic Republic of)

    2010-03-15

    The photocatalytic activity of sulphonated cobalt phthalocyanine immobilized onto MCM-41 was investigated for decomposition of 2,4-dichlorophenol (2,4-DCP) in aqueous solutions. Immobilization of anion sulpho-cobalt phthalocyanine to the walls of MCM-41 was performed by pre-anchorage of 3-(aminopropyl)-triethoxysilane (APTES) onto MCM-41 via post-synthesis method. X-ray diffraction, nitrogen physisorption, diffuse reflectance spectroscopy, energy-dispersive X-ray and FT-IR methods were used to characterize the product. Photocatalytic efficiency of the prepared catalyst for degradation of 2,4-DCP was tested under illumination of UV-A and visible light. The results obtained reveal that the photocatalyst is very active in degradation of 2,4-DCP. The photodegradation process is completed within 3 h using a dose of 0.6 g/L of the catalyst under UV irradiation. The reactions follow a pseudo-first-order kinetics and the observed rate constant values change with 2,4-DCP concentrations. The reproducibility of the catalyst was tested. The reaction intermediates were identified by gas chromatoghraphy-mass spectrometery (GC-MS) technique.

  9. Sulphonated cobalt phthalocyanine-MCM-41: an active photocatalyst for degradation of 2,4-dichlorophenol.

    Science.gov (United States)

    Zanjanchi, M A; Ebrahimian, A; Arvand, M

    2010-03-15

    The photocatalytic activity of sulphonated cobalt phthalocyanine immobilized onto MCM-41 was investigated for decomposition of 2,4-dichlorophenol (2,4-DCP) in aqueous solutions. Immobilization of anion sulpho-cobalt phthalocyanine to the walls of MCM-41 was performed by pre-anchorage of 3-(aminopropyl)-triethoxysilane (APTES) onto MCM-41 via post-synthesis method. X-ray diffraction, nitrogen physisorption, diffuse reflectance spectroscopy, energy-dispersive X-ray and FT-IR methods were used to characterize the product. Photocatalytic efficiency of the prepared catalyst for degradation of 2,4-DCP was tested under illumination of UV-A and visible light. The results obtained reveal that the photocatalyst is very active in degradation of 2,4-DCP. The photodegradation process is completed within 3h using a dose of 0.6g/L of the catalyst under UV irradiation. The reactions follow a pseudo-first-order kinetics and the observed rate constant values change with 2,4-DCP concentrations. The reproducibility of the catalyst was tested. The reaction intermediates were identified by gas chromatoghraphy-mass spectrometry (GC-MS) technique.

  10. PEG-templated mesoporous silica nanoparticles exclusively target cancer cells

    Science.gov (United States)

    Morelli, Catia; Maris, Pamela; Sisci, Diego; Perrotta, Enrico; Brunelli, Elvira; Perrotta, Ida; Panno, Maria Luisa; Tagarelli, Antonio; Versace, Carlo; Casula, Maria Francesca; Testa, Flaviano; Andò, Sebastiano; Nagy, Janos B.; Pasqua, Luigi

    2011-08-01

    Mesoporous silica nanoparticles (MSNs) have been proposed as DNA and drug delivery carriers, as well as efficient tools for fluorescent cell tracking. The major limitation is that MSNs enter cells regardless of a target-specific functionalization. Here we show that non functionalized MSNs, synthesized using a PEG surfactant-based interfacial synthesis procedure, do not enter cells, while a highly specific, receptor mediated, cellular internalization of folic acid (FOL) grafted MSNs (MSN-FOL), occurs exclusively in folate receptor (FR) expressing cells. Neither the classical clathrin pathway nor macropinocytosis is involved in the MSN endocytic process, while fluorescent MSNs (MSN-FITC) enter cells through aspecific, caveolae-mediated, endocytosis. Moreover, internalized particles seem to be mostly exocytosed from cells within 96 h. Finally, cisplatin (Cp) loaded MSN-FOL were tested on cancerous FR-positive (HeLa) or normal FR-negative (HEK293) cells. A strong growth arrest was observed only in HeLa cells treated with MSN-FOL-Cp. The results presented here show that our mesoporous nanoparticles do not enter cells unless opportunely functionalized, suggesting that they could represent a promising vehicle for drug targeting applications.Mesoporous silica nanoparticles (MSNs) have been proposed as DNA and drug delivery carriers, as well as efficient tools for fluorescent cell tracking. The major limitation is that MSNs enter cells regardless of a target-specific functionalization. Here we show that non functionalized MSNs, synthesized using a PEG surfactant-based interfacial synthesis procedure, do not enter cells, while a highly specific, receptor mediated, cellular internalization of folic acid (FOL) grafted MSNs (MSN-FOL), occurs exclusively in folate receptor (FR) expressing cells. Neither the classical clathrin pathway nor macropinocytosis is involved in the MSN endocytic process, while fluorescent MSNs (MSN-FITC) enter cells through aspecific, caveolae

  11. Photocatalytic degradation of tetracycline by Ti-MCM-41 prepared at room temperature and biotoxicity of degradation products

    Science.gov (United States)

    Zhou, Kefu; Xie, Xiao-Dan; Chang, Chang-Tang

    2017-09-01

    Ti-doped MCM-41 with different Si/Ti molar ratios was prepared at room temperature to degrade tetracycline antibiotics in aqueous solution. The Ti was doped into the skeleton structure of MCM-41. The photocatalytic activity of Ti-doped MCM-41 was investigated. The optimal catalyst had Si/Ti molar ratio of 25 and over 99% removal of oxytetracycline in 150 min, and the removal could maintain 98% after 5 reuses. Ions and soluble organic matters in natural water affected the degradation reaction when Ti-doped MCM-41 was used to treat simulated wastewater of chicken farms. The degradation products of oxytetracycline, tetracycline and chlortetracycline were detected by Escherichia coli DH5α and HPLC-MS/MS. No intermediate product with higher toxicity was detected.

  12. Reaction mechanisms in irradiated, precipitated, and mesoporous silica.

    Science.gov (United States)

    Dondi, D; Buttafava, A; Zeffiro, A; Bracco, S; Sozzani, P; Faucitano, A

    2013-04-25

    A matrix EPR spectroscopy study of the low temperature γ radiolysis of precipitated (Zeosil) and mesoporous high surface silica has afforded evidence of the formation of trapped H-atoms, H-atom centers, siloxy radicals ≡Si-O(•), anomalous silyl peroxy radicals ≡Si-OO(•) with reduced g tensor anisotropy, siloxy radical-cations (≡Si-O-Si≡)(+•), E' centers, and two species from Ge impurity. Coordination of peroxyl radicals with diamagnetic ≡Si(+) centers is proposed and tested by DFT computations in order to justify the observed g tensor. Coordination of H-atoms to ≡Si(+) centers is also proposed for the structure of the H-atom centers as an alternative model not requiring the intervention of Ge, Sn, or CO impurities. The DFT method has been employed to assess the electronic structure of siloxy radical-cations and its similarity with that of the carbon radical-cation analogues; the results have prompted a revision of the structures proposed in the literature for ST1 and ST2 centers. The comparison between the two types of silica has afforded evidence of different radiolysis mechanisms leading to a greater yield of trapped H-atoms and H-atom centers in zeosil silica, which is reckoned with the 4-fold greater concentration of silanol groups. Parallel radiolysis experiments carried out by using both types of silica with polybutadiene oligomers as adsorbate have afforded evidence of free valence and energy migration phenomena leading to irreversible linking of polybutadiene chains onto silica. Reaction mechanisms are proposed based on the detection of SiO2-bonded free radicals whose structure has been defined by EPR.

  13. Characterizations and Catalytic Properties of Transition Metal Ions Incorporated in Mesoporous Materials

    Institute of Scientific and Technical Information of China (English)

    WANG Ye

    2004-01-01

    Mesoporous materials typified by MCM-41 possess well-ordered mesoporous channels with controllable pore sizes from 2-30 nm, and are expected as desirable materials for catalysis.However, silicious mesoporous materials generally do not have sufficient intrinsic catalytic activities.Thus many studies have focused on introducing catalytically active sites. It is expected that different synthetic methods would result in different coordination structures of metal cations introduced in MCM-41, and thus different catalytic properties in catalytic reactions. The author's group has used two methods, i.e., direct hydrothermal synthesis (DHT) and template-ion exchange (TIE), for the syntheses of V-, Fe-, and Cr-MCM-41 and applied them as catalysts to selective oxidations of hydrocarbons. This paper highlights the characterizations of the coordination structures of these metal cations introduced into MCM-41 by the DHT and the TIE methods, and the structural-property relationships of these metal ion-containing MCM-41 materials in selective oxidation reactions.MCM-41 was prepared by hydrothermal synthesis using hexadecyltrimethylammonium bromide and sodium silicate as the sources of template and silicon, respectively. In the DHT method, metal cations were directly added into the synthesis gel before hydrothermal synthesis, while the exchanging of metal ions in ethanolic solutions with the template cations contained in the uncalcined MCM-41 was performed in the TIE method. XRD and N2-adsorption measurements showed that the mesoporous regularity was not destroyed with both synthetic methods for all the metal ion-containing MCM-41 with appropriate contents of metal cations.For V-MCM-41, the characterizations with mainly EXAFS suggested that V5+ cations were in tetrahedral coordination and mainly incorporated inside the framework of MCM-41 to substitute Si4+in the samples by the DHT method. Tetrahedrally coordinated Vanadyl species were also obtained by the TIE method, but the VO4

  14. Amine-functionalized magnetic mesoporous silica nanoparticles for DNA separation

    Energy Technology Data Exchange (ETDEWEB)

    Sheng, Wei; Wei, Wei; Li, Junjian; Qi, Xiaoliang; Zuo, Gancheng; Chen, Qi; Pan, Xihao; Dong, Wei, E-mail: weidong@njust.edu.cn

    2016-11-30

    Highlights: • Fe{sub 3}O{sub 4}@SiO{sub 2}@EDPS with uniform size and good dispersity is prepared. • We fabricated MMSN@EDPS with distinct core-shell–shell triple-layer composition. • DNA adsorption capacity of MMSN@EDPS is considerable. - Abstract: We report a modified approach for the functionalized magnetic mesoporous silica nanoparticles (MMSN) using polymer microspheres incorporated with magnetic nanoparticles in the presence of cetyltrimethylammonium bromide (CTAB) and the core-shell magnetic silica nanoparticles (MSN). These particles were functionalized with amino groups via the addition of aminosilane directly to the particle sol. We then evaluate their DNA separation abilities and find the capacity of DNA binding significantly increased (210.22 μg/mg) compared with normal magnetic silica spheres (138.44 μg/mg) by using an ultraviolet and visible spectrophotometer (UV). The morphologies, magnetic properties, particle size, pore size, core-shell structure and Zeta potential are characterized by Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), Transmission electron microscopy (TEM), Powder X-ray diffraction (XRD), and dynamic light scattering (DLS). This work demonstrates that our MMSN own an excellent potential application in bioseparation and drug delivery.

  15. Aza-Michael addition reactions between nitroolefins and benzotriazole catalyzed by MCM-41 immobilized heteropoly acids in water

    Institute of Scientific and Technical Information of China (English)

    Shao-Lei Xie; Yong-Hai Hui; Xiang-Ju Long; Chang-Chun Wang; Zheng-Feng Xie

    2013-01-01

    MCM-41 supported heteropoly acids (HPAs) catalysts were synthesized,characterized and their catalytic activity was evaluated in an aza-Michael addition reaction between nitroolefins and benzotriazole in water at room temperature.50 wt% PW/MCM-41 showed the highest activity (up to 96% yield).The catalyst was used in six consecutive experiments without obvious loss of activity,confirming the success of the anchoring process and the catalyst stability.

  16. Preparation and Defluorination Performance of Activated Cerium(IV) Oxide/SiMCM-41 Adsorbent in Water.

    Science.gov (United States)

    Xu, Ying-Ming; Ning, An-Rong; Zhao, Jing

    2001-03-01

    By using the wetness impregnation-coprecipitation method, a new adsorbent, cerium(IV) oxide coated on SiMCM-41 ((Ce)SiMCM-41), was prepared for removal of fluoride ions from water. Factors investigated were number of impregnations, Ce/Si ratios, concentrations of F(-) ions, pH values, and calcination temperatures. The dynamics, isotherms, and mechanism of adsorption of F(-) ions were discussed. Copyright 2001 Academic Press.

  17. Novel mesoporous composites based on natural rubber and hexagonal mesoporous silica: Synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Nuntang, Sakdinun; Poompradub, Sirilux [Fuels Research Center, Department of Chemical Technology, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Butnark, Suchada [PTT Research and Technology Institute, PTT Public Company Limited, Wangnoi, Ayutthaya 13170 (Thailand); Yokoi, Toshiyuki; Tatsumi, Takashi [Division of Catalytic Chemistry, Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan); Ngamcharussrivichai, Chawalit, E-mail: Chawalit.Ng@Chula.ac.th [Fuels Research Center, Department of Chemical Technology, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Center of Excellence on Petrochemical and Materials Technology (PETROMAT), Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand)

    2014-02-14

    The present study is the first report on the synthesis and characterization of mesoporous composites based on natural rubber (NR) and hexagonal mesoporous silica (HMS). A series of NR/HMS composites were prepared in tetrahydrofuran via an in situ sol–gel process using tetraethylorthosilicate as the silica precursor. The physicochemical properties of the composites were characterized by various techniques. The effects of the gel composition on the structural and textural properties of the NR/HMS composites were investigated. The Fourier-transform infrared spectroscopy (FTIR) and {sup 29}Si magic angle spinning nuclear magnetic resonance ({sup 29}Si MAS NMR) results revealed that the surface silanol groups of NR/HMS composites were covered with NR molecules. The powder X-ray diffraction (XRD) and transmission electron microscopy (TEM) data indicated an expansion of the hexagonal unit cell and channel wall thickness due to the incorporation of NR molecules into the mesoporous structure. NR/HMS composites also possessed nanosized particles (∼79.4 nm) as confirmed by scanning electron microscopy (SEM) and particle size distribution analysis. From N{sub 2} adsorption–desorption measurement, the NR/HMS composites possessed a high BET surface area, large pore volume and narrow pore size distribution. Further, they were enhanced hydrophobicity confirmed by H{sub 2}O adsorption–desorption measurement. In addition, the mechanistic pathway of the NR/HMS composite formation was proposed. - Highlights: • NR molecules were incorporated into hexagonal meso-structure of HMS. • NR/HMS composites exhibited an expanded unit cell and channel wall thickness. • Nanosized NR/HMS composites with a lower particle size range were obtained. • NR/HMS had high surface area, large pore volume and narrow pore size distribution. • NR/HMS composites displayed an enhanced hydrophobicity.

  18. Tb(aspirin)3phen和MCM-41组装体的光谱研究

    Institute of Scientific and Technical Information of China (English)

    彭春佳; 魏长平; 祝翠梅; 许洁; 孙小飞

    2007-01-01

    MCM-41和客体Tb(aspirin)3phen进行组装,采用XRD、IR和PL进行了表征,探讨了主体McM-41和客体Tb(aspirin)1phen间的相互影响。MCM-41焙烧后再进行组装,Tb(aspirin)3phen可增加MCM-41的骨架有序性,充当“二次模板剂”的作用。IR谱图中,Tb(aspirin)3phen-MCM-41组装体在波数1384cm-1处明显保留了Tb-N键的振动吸收。405nm发射峰强度,L和544nm发射峰强度,ILn的比值I,与McM-41不同的表面环境有关,且McM-41的不同表面环境对配体phen三重态和单重态能级的影响顺序为:MCM-41B外表面〉MCM-41A外表面〉McM-41A内表面。

  19. Silica promoted self-assembled mesoporous aluminas. Impact of the silica precursor on the structural, textural and acidic properties

    NARCIS (Netherlands)

    Perez, Lidia Lopez; Zarubina, Valeriya; Mayoral, Alvaro; Melian-Cabrera, Ignacio

    2015-01-01

    This paper investigates the effect of silica addition on the structural, textural and acidic properties of an evaporation induced self-assembled (EISA) mesoporous alumina. Two silica addition protocols were applied while maintaining the EISA synthesis route. The first route is based on the addition

  20. One-step synthesis of degradable T1-FeOOH functionalized hollow mesoporous silica nanocomposites from mesoporous silica spheres

    Science.gov (United States)

    Peng, Yung-Kang; Tseng, Yu-Jui; Liu, Chien-Liang; Chou, Shang-Wei; Chen, Yu-Wei; Tsang, S. C. Edman; Chou, Pi-Tai

    2015-01-01

    The combination of a hollow mesoporous structure and a magnetic resonance (MR) contrast agent has shown its potential in simultaneous drug delivery and cell tracking applications. However, the preparation of this kind of nanocomposite is complicated and usually takes several days, which is unsuitable for scaled-up production. To overcome these hurdles, we report herein a facile method to synthesize iron oxide hydroxide functionalized hollow mesoporous silica spheres (FeOOH/HMSS) in a one-step manner. By carefully controlling the reaction kinetics of K2FeO4 in water, the gram-scale production of FeOOH/HMSS can be readily achieved at 60 °C for as short as 30 min. Most importantly, this synthetic process is also cost-effective and eco-friendly in both the precursor (K2FeO4 and H2O) and the product (FeOOH). The mechanism for the formation of a hollow structure was carefully investigated, which involves the synergetic effect of the surfactant CTAB and the side product KOH. Having outstanding biocompatibility, these degradable nanocolloids also demonstrate their feasibility in in vitro/vivo MR imaging and in vitro drug delivery.The combination of a hollow mesoporous structure and a magnetic resonance (MR) contrast agent has shown its potential in simultaneous drug delivery and cell tracking applications. However, the preparation of this kind of nanocomposite is complicated and usually takes several days, which is unsuitable for scaled-up production. To overcome these hurdles, we report herein a facile method to synthesize iron oxide hydroxide functionalized hollow mesoporous silica spheres (FeOOH/HMSS) in a one-step manner. By carefully controlling the reaction kinetics of K2FeO4 in water, the gram-scale production of FeOOH/HMSS can be readily achieved at 60 °C for as short as 30 min. Most importantly, this synthetic process is also cost-effective and eco-friendly in both the precursor (K2FeO4 and H2O) and the product (FeOOH). The mechanism for the formation of a

  1. Co- Zr/MCM-41催化氧化石蜡的研究%Study on Catalytic Oxidation of Paraffin by Using Co- Zr/MCM-41 as Catalyst

    Institute of Scientific and Technical Information of China (English)

    佟天宇

    2015-01-01

    In order to produce special wax and its additives by the catalytic oxidation process, paraffin wax oxidation reaction was researched systematically by using Co/SiO2, Co/MCM-41, Zr/MCM-41 or Co-Zr/MCM-41 as catalyst and air as oxidant. Effects of metal loading amount on its catalytic performance were investigated as well as the performance of catalyst with different metal for catalytic oxidation of paraffin. Effects of Co and Zr contents on Co-Zr/MCM-41 activity were analyzed. The results show that, using Co-Zr/MCM-41 (12% Co, 3% Zr) as catalyst, under the conditions of the oxidation temperature 140℃, oxidation time 5h, air flow rate 0.7 L/min and catalyst 2%, oxidized wax with high ester/acid ratio can be obtained.%从催化氧化石蜡生产特种蜡及其添加剂的角度出发,采用 Co/SiO2、Co/MCM-41、Zr /MCM-41、Co-Zr/MCM-41为催化剂,用空气作氧化剂,对石蜡氧化进行了实验研究。考察了金属负载量对催化性能的影响、不同负载金属催化剂的石蜡氧化活性比较、Co、Zr 含量对 Co-Zr/ MCM-41活性的影响。实验结果表明,以 MCM-41作为载体制备钴负载量为12%、锆负载量为3%的复合氧化物为催化氧化反应的催化剂,在氧化温度为140℃、氧化时间为5 h、空气流量为0.7 L/min、催化剂用量为2%的最经济反应条件下可得到高酯酸比的氧化蜡产品。

  2. Non-surfactant synthesis of mesoporous silica with dye as template

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A novel non-surfactant method was described to synthesize mesoporous silica using dye basic fuchsin as template. Chemical reactions were introduced into the formation of mesopores rather than the weak electrostatic or hydrogen-bonding interactions in the traditional surfactant routes. The reactant composition was found to be crucial to the pore structure of objective product. The formation mechanism of mesopore was also proved.

  3. Mesoporous-Silica-Functionalized Nanoparticles for Drug Delivery.

    Science.gov (United States)

    Giret, Simon; Wong Chi Man, Michel; Carcel, Carole

    2015-09-28

    The ever-growing interest for finding efficient and reliable methods for treatment of diseases has set a precedent for the design and synthesis of new functional hybrid materials, namely porous nanoparticles, for controlled drug delivery. Mesoporous silica nanoparticles (MSNPs) represent one of the most promising nanocarriers for drug delivery as they possess interesting chemical and physical properties, thermal and mechanical stabilities, and are biocompatibile. In particular, their easily functionalizable surface allows a large number of property modifications further improving their efficiency in this field. This Concept article deals with the advances on the novel methods of functionalizing MSNPs, inside or outside the pores, as well as within the walls, to produce efficient and smart drug carriers for therapy.

  4. 12-Tungstophosphates Immobilized on Chemically Modified Mesoporous Silica SBA-15

    Institute of Scientific and Technical Information of China (English)

    ZHU Jing; YOU Wan-sheng; ZHU Zai-ming; SUN Zhen-gang; ZHANG Lan-cui; GU Yuan-peng

    2005-01-01

    A functionalized material, PW/SBA-15m, was prepared successfully in diluted H2SO4 aqueous solutions by immobilizing 12-tungstophosphates on chemically modified mesoporous silica SBA-15 and characterized by elemental analysis, FTIR, 31P MAS NMR, XRD and TEM. The results indicate that the framework of SBA-15 and the Keggin structure of PW12O3-40 were retained, and that 23%-33%(mass fraction) of PW12O3-40 was immobilized; the PW12O3-40 anions were finely dispersed on the pore wall of SBA-15. Having been leached in ethanol at 60 ℃ for 7 h, the loss of PW12O3-40 anions was not found.

  5. 改性Ti-MCM-41催化剂对过氧化氢异丙苯环氧化丙烯反应的影响%Catalytic performance of the modified Ti-MCM-41 on epoxidation of propene by cumene hydroperoxide

    Institute of Scientific and Technical Information of China (English)

    倪晓磊; 刘靖; 王安杰; 胡永康

    2016-01-01

    以NH3氮化法和甲基硅烷化法等改性方法处理Ti-MCM-41分子筛,并研究了不同改性方法对分子筛结晶度、结构、酸性及疏水性的影响;考察了改性分子筛催化剂对不同来源过氧化氢异丙苯(CHP)催化环氧化丙烯制环氧丙烷(PO)反应的影响。采用XRD、N2吸附-脱附、FTIR、Py-IR、UV-Vis等表征方法对催化剂结构进行表征。表征结果显示,改性处理会导致分子筛孔道收缩、结晶度降低,但仍具有MCM-41分子筛的六方相孔结构。实验结果表明,NH3氮化改性的催化剂,由于酸强度降低,能减少CHP无效分解,CHP的利用率由66.1%提高至80.4%;而经甲基硅烷化改性的催化剂,由于表面疏水性的提高,可提高PO的选择性至99.6%。%Mesoporous Ti-MCM–41 molecular sieve was modified through nitridation with NH3 and silylation with trimethylchlorosilane(TMCS) separately,and the effects of the modification methods on the crystallinity,structure,acid strength and hydrophobicity of Ti-MCM–41 were studied by means of XRD,N2 adsorption-desorption,FTIR,Py-IR and UV-Vis. The catalytic performances of the modified Ti-MCM-41 catalysts in the epoxidation of propene with cumene hydroperoxide(CHP) to propylene oxide(PO) were investigated. The characterizations showed that,although the pores shrank and the crystallinity decreased,the ordered and uniform pores on all the catalysts were kept. In the epoxidation on the modified catalyst with NH3,the decreasing of acid strength inhibited the non-productive decomposition of CHP,so the efficiency of CHP could increase from 66.1% to 80.4%. The silylation with TMCS could enhance the hydrophobicity of Ti-MCM-41,so the selectivity to PO reached 99.6%.

  6. Pseudorotaxane capped mesoporous silica nanoparticles for 3,4-methylenedioxymethamphetamine (MDMA) detection in water

    DEFF Research Database (Denmark)

    Lozano-Torres, Beatriz; Pascual, Lluís; Bernardos, Andrea

    2017-01-01

    Mesoporous silica nanoparticles loaded with fluorescein and capped by a pseudorotaxane, formed between a naphthalene derivative and cyclobis(paraquat-p-phenylene) (CBPQT4+), were used for the selective and sensitive fluorogenic detection of 3,4-methylenedioxymethamphetamine (MDMA)....

  7. Synthesis of Mesoporous Silica and Ti-containing Molecular Sieves via A Novel Assembly

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Thermally stable mesoporous silica and Ti-containing molecular sieves have been synthesized at mild temperature using low-cost and biodegradable---amphoteric tetradecyl betaine as template. The physicochemical characterizations proved that Ti(Ⅳ) could be incorporated in the mesoporous struture.

  8. A novel fabrication of meso-porous silica film by sol-gol of TEOS

    Institute of Scientific and Technical Information of China (English)

    殷明志; 姚熹; 张良莹

    2004-01-01

    A homogeneous crack-free nano- or meso-porous silica films on silicon was fabricated by colloidal silica sol derived by hydrolyzing tetraethyl orthosilicate (TEOS) catalyzing with (C4H9)4N+OH- in water medium. The solution with ratio of H2O/TEOS≥15, R4N+ and glycerol as templates, combining with the hydrolyzed intermediate, controlled the silica aggregating; the templated silica film with heterostructure was developed into homogeneous nano-porous then meso-porous silica films after being annealed from 750 ℃ to 850 ℃; the formation mechanism of the porous silica films was discussed; morphologies of the silica films were characterized. The refractive indexes of the porous silica films were 1.256-1.458, the thermal conductivity < 0.7 W/m/K. The fabricating procedure and the sequence had not been reported before.

  9. Structure and Luminescence Properties of Eu3+-Doped Cubic Mesoporous Silica Thin Films

    Directory of Open Access Journals (Sweden)

    Lu Qingshan

    2010-01-01

    Full Text Available Abstract Eu3+ ions-doped cubic mesoporous silica thin films with a thickness of about 205 nm were prepared on silicon and glass substrates using triblock copolymer as a structure-directing agent using sol–gel spin-coating and calcination processes. X-ray diffraction and transmission electron microscopy analysis show that the mesoporous silica thin films have a highly ordered body-centered cubic mesoporous structure. High Eu3+ ion loading and high temperature calcination do not destroy the ordered cubic mesoporous structure of the mesoporous silica thin films. Photoluminescence spectra show two characteristic emission peaks corresponding to the transitions of5D0-7F1 and 5D0-7F2 of Eu3+ ions located in low symmetry sites in mesoporous silica thin films. With the Eu/Si molar ratio increasing to 3.41%, the luminescence intensity of the Eu3+ ions-doped mesoporous silica thin films increases linearly with increasing Eu3+ concentration.

  10. Structure and luminescence properties of eu3+-doped cubic mesoporous silica thin films.

    Science.gov (United States)

    Lu, Qingshan; Wang, Zhongying; Wang, Peiyu; Li, Jiangong

    2010-02-11

    Eu3+ ions-doped cubic mesoporous silica thin films with a thickness of about 205 nm were prepared on silicon and glass substrates using triblock copolymer as a structure-directing agent using sol-gel spin-coating and calcination processes. X-ray diffraction and transmission electron microscopy analysis show that the mesoporous silica thin films have a highly ordered body-centered cubic mesoporous structure. High Eu3+ ion loading and high temperature calcination do not destroy the ordered cubic mesoporous structure of the mesoporous silica thin films. Photoluminescence spectra show two characteristic emission peaks corresponding to the transitions of5D0-7F1 and 5D0-7F2 of Eu3+ ions located in low symmetry sites in mesoporous silica thin films. With the Eu/Si molar ratio increasing to 3.41%, the luminescence intensity of the Eu3+ ions-doped mesoporous silica thin films increases linearly with increasing Eu3+ concentration.

  11. Synthesis of Ordered Cubic Periodic Mesoporous Silica with High Hydrothermal Stability

    Institute of Scientific and Technical Information of China (English)

    LAI Xiao-yong; TU Jin-chun; WANG Hong; DU Jiang; YANG Mei; MAO Dan; XING Chao-jian; WANG Dan; LI Xiao-tian

    2009-01-01

    @@ 1 Introduction Since its first discovery in 1992~[1,2], ordered me-soporous silica material with large pore size, high surface area, and high pore volume has attracted great attention for the potentially wide application in catalysis, adsorption, separation, and ion exchange, etc. However, the poor hydrothermal stability of meso-porous silica has limited its wide application in industry~[3,4].

  12. Organosulfonic acid-functionalized mesoporous composites based on natural rubber and hexagonal mesoporous silica

    Energy Technology Data Exchange (ETDEWEB)

    Nuntang, Sakdinun; Poompradub, Sirilux [Fuels Research Center, Department of Chemical Technology, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Butnark, Suchada [PTT Research and Technology Institute, PTT Public Company Limited, Wangnoi, Ayutthaya 13170 (Thailand); Yokoi, Toshiyuki; Tatsumi, Takashi [Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan); Ngamcharussrivichai, Chawalit, E-mail: Chawalit.Ng@Chula.ac.th [Fuels Research Center, Department of Chemical Technology, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Center of Excellence on Petrochemical and Materials Technology (PETROMAT), Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand)

    2014-10-15

    This study is the first report on synthesis, characterization and catalytic application of propylsulfonic acid-functionalized mesoporous composites based on natural rubber (NR) and hexagonal mesoporous silica (HMS). In comparison with propylsulfonic acid-functionalized HMS (HMS-SO{sub 3}H), a series of NR/HMS-SO{sub 3}H composites were prepared via an in situ sol–gel process using tetrahydrofuran as the synthesis media. Tetraethylorthosilicate as the silica source, was simultaneously condensed with 3-mercaptopropyltrimethoxysilane in a solution of NR followed by oxidation with hydrogen peroxide to achieve the mesoporous composites containing propylsulfonic acid groups. Fourier-transform infrared spectroscopy and {sup 29}Si MAS nuclear magnetic resonance spectroscopy results verified that the silica surfaces of the NR/HMS-SO{sub 3}H composites were functionalized with propylsulfonic acid groups and covered with NR molecules. After the incorporation of NR and organo-functional group into HMS, the hexagonal mesostructure remained intact concomitantly with an increased framework wall thickness and unit cell size, as evidenced by the X-ray powder diffraction analysis. Scanning electron microscopy analysis indicated a high interparticle porosity of NR/HMS-SO{sub 3}H composites. The textural properties of NR/HMS-SO{sub 3}H were affected by the amount of MPTMS loading to a smaller extent than that of HMS-SO{sub 3}H. NR/HMS-SO{sub 3}H exhibited higher hydrophobicity than HMS-SO{sub 3}H, as revealed by H{sub 2}O adsorption–desorption measurements. Moreover, the NR/HMS-SO{sub 3}H catalysts possessed a superior specific activity to HMS-SO{sub 3}H in the esterification of lauric acid with ethanol, resulting in a higher conversion level. - Highlights: • Acidic NR/HMS-SO{sub 3}H composites were prepared by in situ sol–gel process. • Propylsulfonic acid was functionalized onto HMS surface by direct co-condensation. • NR/HMS-SO{sub 3}H exhibited a hexagonal

  13. One-step synthesis of degradable T(1)-FeOOH functionalized hollow mesoporous silica nanocomposites from mesoporous silica spheres.

    Science.gov (United States)

    Peng, Yung-Kang; Tseng, Yu-Jui; Liu, Chien-Liang; Chou, Shang-Wei; Chen, Yu-Wei; Tsang, S C Edman; Chou, Pi-Tai

    2015-02-14

    The combination of a hollow mesoporous structure and a magnetic resonance (MR) contrast agent has shown its potential in simultaneous drug delivery and cell tracking applications. However, the preparation of this kind of nanocomposite is complicated and usually takes several days, which is unsuitable for scaled-up production. To overcome these hurdles, we report herein a facile method to synthesize iron oxide hydroxide functionalized hollow mesoporous silica spheres (FeOOH/HMSS) in a one-step manner. By carefully controlling the reaction kinetics of K2FeO4 in water, the gram-scale production of FeOOH/HMSS can be readily achieved at 60 °C for as short as 30 min. Most importantly, this synthetic process is also cost-effective and eco-friendly in both the precursor (K2FeO4 and H2O) and the product (FeOOH). The mechanism for the formation of a hollow structure was carefully investigated, which involves the synergetic effect of the surfactant CTAB and the side product KOH. Having outstanding biocompatibility, these degradable nanocolloids also demonstrate their feasibility in in vitro/vivo MR imaging and in vitro drug delivery.

  14. Fabrication of mesoporous silica for ultra-low-k interlayer dielectrics

    Science.gov (United States)

    Fujii, Nobutoshi; Kohmura, Kazuo; Nakayama, Takahiro; Tanaka, Hirofumi; Hata, Nobuhiro; Seino, Yutaka; Kikkawa, Takamaro

    2005-11-01

    We have developed sol-gel self-assembly techniques to control the pore structure and diameter of ultra-low-k interlayer dielectric (ILD) films. Porous silica films have been fabricated using cationic and nonionic surfactants as templates, resulting in 2D-hexagonal and disordered pore structures, respectively. The disordered mesoporous silica film has a worm-hole like network of pore channels having a uniform diameter. Precursors of the mesoporous silica films were synthesized by use of tetraethyl-orthosilicate (TEOS), inorganic acid, water, ethanol and various surfactants. The surfactants used were cationic alkyltrimethyl-ammonium (ATMA) chloride surfactants for 2D-hexagonal pores and nonionic tri-block copolymer for disordered structures. Dimethyldiethoxysilane (DMDEOS) was added for forming the disordered mesoporous silica. The disordered cylindrical pore structure with a uniform pore size was fabricated by controlling the static electrical interaction between the surfactant and the silica oligomer with methyl group of DMDEOS. Tetramethylcycrotetrasiloxane (TMCTS) vapor treatment was developed, which improved the mechanical strength of mesoporous silica films. The TMCTS polymer covered the pore wall surface and cross-linked to passivate the mechanical defects in the silica wall. Significant enhancement of mechanical strength was demonstrated by TMCTS vapor treatment. The porous silica film modified with a catalyst and a plasma treatment achieved higher mechanical strength and lower dielectric constant than conventional porous silica films because the TMCTS vapor treatment was more effective for mechanical reinforcement and hydrophobicity.

  15. Preparation of Mesoporous Silica Templated Metal Nanowire Films on Foamed Nickel Substrates

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, Roger [University of Alabama, Tuscaloosa; Kenik, Edward A [ORNL; Bakker, Martin [University of Alabama, Tuscaloosa; Havrilla, George [Los Alamos National Laboratory (LANL); Montoya, Velma [Los Alamos National Laboratory (LANL); Shamsuzzoha, Mohammed [University of Alabama, Tuscaloosa

    2006-01-01

    A method has been developed for the formation of high surface area nanowire films on planar and three-dimensional metal electrodes. These nanowire films are formed via electrodeposition into a mesoporous silica film. The mesoporous silica films are formed by a sol-gel process using Pluronic tri-block copolymers to template mesopore formation on both planar and three-dimensional metal electrodes. Surface area increases of up to 120-fold have been observed in electrodes containing a templated film when compared to the same types of electrodes without the templated film.

  16. 负载Co介孔分子筛催化热解乙醇制备纳米碳管%Preparation of carbon nanotubes by ethanol pyrolysis on loaded Co mesoporous molecular sieve

    Institute of Scientific and Technical Information of China (English)

    张丽; 赵谦; 纪美茹; 贾佳

    2013-01-01

    以硅酸钠为原料,CTAB为模板剂,水热法合成MCM-41介孔分子筛,采用浸渍法制备负载钴的介孔分子筛(Co/MCM-41),并将其作为催化剂,CVD法热解无水乙醇制备CNTs.利用XRD、TEM、比表面积和孔径分布测定和Raman光谱等方法对所合成的介孔分子筛和纳米碳管进行了表征.结果表明:所制备的Co/MCM-41样品具有典型的MCM-41的介孔结构;当热解反应温度为750℃下所制备出的纳米碳管的品质最好.%MCM-41mesoporous molecular sieve was synthesized by hydrothermal method using cetyltri-methyl ammonium bromide as template and sodium silicate as raw material, respectively. And Co-loaded mesoporous molecular sieve (Co/MCM-41) was prepared by the wet impregnation method with cobalt chloride solution. The chemical vapor deposition method was employed to catalytically synthesize carbon nanotubes (CNTs) using Co/MCM-41 as catalytic template and alcohol as carbon source. The physicochemical properties of the obtained samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 physical adsorption and Raman spectroscopy, respectively. The results show that the Co/MCM-41 sample possesses a typical mesoporous framework of MCM-41. The Co/MCM-41 mesoporous molecular sieve with high specific surface area was successfully synthesized under hydrothermal condition. These mesoporous materials have good mesoporous ordering. When the reaction temperature is 750 ℃ , the resulting CNTs are of high quality.

  17. Investigation into the Catalytic Activity of Microporous and Mesoporous Catalysts in the Pyrolysis of Waste Polyethylene and Polypropylene Mixture

    Directory of Open Access Journals (Sweden)

    Kaixin Li

    2016-06-01

    Full Text Available Catalytic pyrolysis behavior of synthesized microporous catalysts (conventional Zeolite Socony Mobil–5 (C-ZSM-5, highly uniform nanocrystalline ZSM-5 (HUN-ZSM-5 and β-zeolite, Mesoporous catalysts (highly hydrothermally stable Al-MCM-41 with accessible void defects (Al-MCM-41(hhs, Kanemite-derived folded silica (KFS-16B and well-ordered Al-SBA-15 (Al-SBA-15(wo were studied with waste polyethylene (PE and polypropylene (PP mixture which are the main constituents in municipal solid waste. All the catalysts were characterized by Brunauer-Emmett-Teller (BET, X-ray powder diffraction (XRD, and NH3-temperature programmed desorption (TPD. The results demonstrated that microporous catalysts exhibited high yields of gas products and high selectivity for aromatics and alkene, whereas the mesoporous catalysts showed high yields of liquid products with considerable amounts of aliphatic compounds. The differences between the microporous and mesoporous catalysts could be attributed to their characteristic acidic and textural properties. A significant amount of C2–C4 gases were produced from both types of catalysts. The composition of the liquid and gas products from catalytic pyrolysis is similar to petroleum-derived fuels. In other words, products of catalytic pyrolysis of plastic waste can be potential alternatives to the petroleum-derived fuels.

  18. Solid phase extraction and trace monitoring of cadmium ions in environmental water and food samples based on modified magnetic nanoporous silica

    Energy Technology Data Exchange (ETDEWEB)

    Omidi, Fariborz [Department of Occupational Health Engineering, School of Public Health, Shahroud University of Medical Sciences, Shahroud (Iran, Islamic Republic of); Behbahani, Mohammad, E-mail: mohammadbehbahai89@yahoo.com [Department of Chemistry, Shahid Beheshti University, Evin, Tehran (Iran, Islamic Republic of); Kalate Bojdi, Majid [Faculty of Chemistry, Kharazmi (Tarbiat Moallem) University, Tehran (Iran, Islamic Republic of); Shahtaheri, Seyed Jamaleddin [Department of Occupational Health Engineering, School of Public Health and Institute for Environmental Research, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of)

    2015-12-01

    A new method has been developed for trace separation/preconcentration of cadmium ions using pyridine-functionalized magnetic nanoporous silica material (called Py-Fe{sub 3}O{sub 4}@MCM-41) as a new magnetic sorbent and their determination by flame atomic absorption spectrometry (FAAS). The Py-Fe{sub 3}O{sub 4}@MCM-41 sorbent was characterized by thermogravimetric analysis, differential thermal analysis, transmission electron microscopy, Fourier transform infrared spectrometry and X-ray diffraction. The modified Fe{sub 3}O{sub 4}@MCM-41 can be easily separated from an aqueous solution by applying an external magnetic field. Effects of pH, amount of functionalized Fe{sub 3}O{sub 4}@MCM-41, extraction time, type and quantity of eluent, desorption time, and interfering ions on the extraction efficiency were evaluated and optimized. Under the optimized conditions, the detection limit and relative standard deviation was 0.04 μg L{sup –1} and 2.9%, respectively and the maximum adsorption capacity of the synthesized sorbent for cadmium ions was 154 mg g{sup −1}. The proposed method has been applied to the determination of Cd ions at trace levels in real samples such as, rice, onion, carrot, lettuce, parsley, basil, tap water, river water and seawater with satisfactory results. - Highlights: • The introducing of modified magnetic mesoporous silica as a novel magnetic sorbent. • Trace monitoring of cadmium ions. • The limit of detection (LOD) by the proposed solid phase extraction method was 0.04 ng mL{sup −1} for the cadmium ions. • High surface areas and magnetic characteristic of the sorbent. • Maximum adsorption capacity of the sorbent was 154 mg g{sup −1}.

  19. Mesoporous silica-magnetite nanocomposite synthesized by using a neutral surfactant.

    Science.gov (United States)

    Souza, K C; Salazar-Alvarez, G; Ardisson, J D; Macedo, W A A; Sousa, E M B

    2008-05-07

    Magnetite nanoparticles coated by mesoporous silica were synthesized by an alternative chemical route using a neutral surfactant and without the application of any functionalization method. The magnetite (Fe(3)O(4)) nanoparticles were prepared by precipitation from aqueous media, and then coated with mesoporous silica by using nonionic block copolymer surfactants as the structure-directing agents. The mesoporous SiO(2)-coated Fe(3)O(4) samples were characterized by x-ray diffraction, Fourier-transform infrared spectroscopy, N(2) adsorption-desorption isotherms, transmission electron microscopy, (57)Fe Mössbauer spectroscopy, and vibrating sample magnetometry. Our results revealed that the magnetite nanoparticles are completely coated by well-ordered mesoporous silica with free pores and stable (∼8 nm thick) pore walls, and that the structural and magnetic properties of the Fe(3)O(4) nanoparticles are preserved in the applied synthesis route.

  20. Mesoporous silica-magnetite nanocomposite synthesized by using a neutral surfactant

    Energy Technology Data Exchange (ETDEWEB)

    Souza, K C; Sousa, E M B [Laboratorio de Biomateriais, Centro de Desenvolvimento da Tecnologia Nuclear, 30123-970 Belo Horizonte, MG (Brazil); Salazar-Alvarez, G [Institut Catala de Nanotecnologia (ICN), Edifici CM7, Campus Universitat Autonoma de Barcelona, E-08193 Bellaterra (Barcelona) (Spain); Ardisson, J D; Macedo, W A A [Laboratorio de Fisica Aplicada, Centro de Desenvolvimento da Tecnologia Nuclear, 30123-970 Belo Horizonte, MG (Brazil)], E-mail: sousaem@cdtn.br

    2008-05-07

    Magnetite nanoparticles coated by mesoporous silica were synthesized by an alternative chemical route using a neutral surfactant and without the application of any functionalization method. The magnetite (Fe{sub 3}O{sub 4}) nanoparticles were prepared by precipitation from aqueous media, and then coated with mesoporous silica by using nonionic block copolymer surfactants as the structure-directing agents. The mesoporous SiO{sub 2}-coated Fe{sub 3}O{sub 4} samples were characterized by x-ray diffraction, Fourier-transform infrared spectroscopy, N{sub 2} adsorption-desorption isotherms, transmission electron microscopy, {sup 57}Fe Moessbauer spectroscopy, and vibrating sample magnetometry. Our results revealed that the magnetite nanoparticles are completely coated by well-ordered mesoporous silica with free pores and stable ({approx}8 nm thick) pore walls, and that the structural and magnetic properties of the Fe{sub 3}O{sub 4} nanoparticles are preserved in the applied synthesis route.

  1. Different Synthesis Methods for Ordered Mesoporous Silicas And Their Characteristics Comparison

    Institute of Scientific and Technical Information of China (English)

    LEI Jia-heng; ZHAO Jun; CHEN Yong-xi; GUO Li-ping

    2003-01-01

    Ordered mesoporous silica were synthesized under different conditions:hydrothermal synthesis in basic medium,room temperature synthesis in acid medium and sol-gel synthesis in neutral medium,and pore structure,specific surface area and pore size distribution of samples were studied and compared in detail by means of SAXRD,HRTEM,BET,FT-IR.The results show that the mesopores in the samples obtained via above three methods all possess uniform hexagonal arrays in short range.Mesoporous silica obtained in acid medium possesses narrow pore size distribution centered around 1.24nm with specific surface area of 1220 m2·g-1;Mesoporous silica obtained in basic medium by hydrothermal synthesis at 160℃ possesses narrow pore size distribution centered around 1.90nm with specific surface area of 542.8 m2·g-1;and mesoporous silica obtained in neutral medium by sol-gel synthesis possesses broader pore size distribution centered around 4.01nm,specific surface area of 485.0 m2·g-1.Therefore,ordered mesoporous silicas with different pore sizes can be prepared using various synthetic methods and conditions.After heat treatment,Si-O-Si bending vibration strengthens and the adsorption peak of asymmetrical Si-O-Si stretching vibration broadens,and the crosslinking and condensation reaction of silica skeleton strengthen, meanwhile the amount of active centers of hydroxyl group on the surface of mesopores may be influenced,thus chemical assembly activity of mesopores may also be influenced.

  2. Coherent anti-Stokes Raman scattering (CARS) microscopy driving the future of loaded mesoporous silica imaging

    NARCIS (Netherlands)

    Fussell, A.L.; Mah, Pei Ting; Offerhaus, Herman L.; Niemi, Sanna-Mari; Salonen, Jarno; Santos, Helder A.; Strachan, Clare

    2014-01-01

    This study reports the use of variants of coherent anti-Stokes Raman scattering (CARS) microscopy as a novel method for improved physicochemical characterization of drug-loaded silica particles. Ordered mesoporous silica is a biomaterial that can be loaded to carry a number of biochemicals,

  3. Recent progress of ordered mesoporous silica-supported chiral metallic catalysts

    Directory of Open Access Journals (Sweden)

    LIU Rui

    2013-02-01

    Full Text Available Recently,ordered silica-based mesoporous chiral organometallics-functionalized heterogeneous catalysts have attracted extensive research interest due to their excellent properties,such as easy preparation,high activity and convenient recycle.This review mainly summarizesthe generally prepared strategy and the silica-based organometallics-functionalized heterogeneous catalysts reported in the literatures.

  4. SBA-15 Mesoporous Silica Modified with Gallic Acid and Evaluation of Its Cytotoxic Activity.

    Science.gov (United States)

    Lewandowski, Dawid; Ruszkowski, Piotr; Pińska, Anita; Schroeder, Grzegorz; Kurczewska, Joanna

    2015-01-01

    Gallic acid has been covalently conjugated to SBA-15 mesoporous silica surface through different linkers. Cytotoxic activity of the hybrid organic-inorganic systems against HeLa and KB cell lines has been analyzed. Up to 67% of HeLa or KB tumor cells growth inhibition has been achieved at low silica concentration used (10 μg mL(-1)).

  5. Preparation of resveratrol-loaded nanoporous silica materials with different structures

    Science.gov (United States)

    Popova, Margarita; Szegedi, Agnes; Mavrodinova, Vesselina; Novak Tušar, Natasa; Mihály, Judith; Klébert, Szilvia; Benbassat, Niko; Yoncheva, Krassimira

    2014-11-01

    Solid, nanoporous silica-based spherical mesoporous MCM-41 and KIL-2 with interparticle mesoporosity as well as nanosized zeolite BEA materials differing in morphology and pore size distribution, were used as carriers for the preparation of resveratrol-loaded delivery systems. Two preparation methods have been applied: (i) loading by mixing of resveratrol and mesoporous carrier in solid state and (ii) deposition in ethanol solution. The parent and the resveratrol loaded carriers were characterized by XRD, TEM, N2 physisorption, thermal analysis, and FT-IR spectroscopy. The influence of the support structure on the adsorption capacity and the release kinetics of this poorly soluble compound were investigated. Our results indicated that the chosen nanoporous silica supports are suitable for stabilization of trans-resveratrol and reveal controlled release and ability to protect the supported compound against degradation regardless of loading method. The solid-state dry mixing appears very effective for preparation of drug formulations composed of poorly soluble compound.

  6. Carbon dioxide adsorption on amine-impregnated mesoporous materials prepared from spent quartz sand.

    Science.gov (United States)

    Su, Yiteng; Peng, Lihong; Shiue, Angus; Hong, Gui-Bing; Qian, Zhang; Chang, Chang-Tang

    2014-07-01

    Mesoporous MCM-41 was synthesized using cetyltrimethyl ammonium bromide (CTAB) as a cationic surfactant and spent quartz sand as the silica source. Modification of the mesoporous structure to create an absorbent was then completed using 3-aminopropyltrimethoxysilane. Amine-Quartz-MCM (The A-Q-MCM) adsorbents were then characterized by N2 adsorption/desorption, elemental analysis (EA), X-ray fluorescence (XRF), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), as well as the carbon dioxide (CO2) adsorption/desorption performance. In this study, spent quartz sand was utilized to synthesize Quartz-MCM (Q-MCM) and the amine functionalized material, A-Q-MCM, which exhibited a higher uptake of CO2 at room temperature compared with the nongrafted material. The results showed that Q-MCM is similar to MCM-41 synthesized using commercial methods. The surface area, pore volume, and pore diameter were found to be as high as 1028 m2/g, 0.907 cm3/g, and 3.04 nm, respectively. Under the condition of CO2 concentration of 5000 ppm, retention time of 50 cc/min, and the dosage of 1 g/cm3, the mean adsorption capacity of CO2 onto A-Q-MCM was about 89 mg/g, and the nitrogen content of A-Q-MCM was 2.74%. The adsorption equilibrium was modeled well using a Freundlich isotherm. Implications: In this study, spent quartz sand was utilized to synthesize Q-MCM. The amine functionalized material exhibited a higher uptake of CO2 at room temperature compared with the nongrafted material. The results showed that Q-MCM is similar to MCM-41 synthesized using commercial methods. The adsorption equilibrium was modeled well using a Freundlich isotherm.

  7. Cr-MCM-41 Molecular Sieves Crystallized at Room Temperature for Reaction of Ethane with CO2

    Institute of Scientific and Technical Information of China (English)

    Yanan Li; Xin He; Shujie Wu; Ke Zhang; Guangdong Zhou; Jie Liu; Kaiji Zhen; Tonghao Wu; Tiexin Cheng

    2005-01-01

    A series of Cr-containing MCM-41 molecular sieves crystallized at room temperature with a hexagonal and well-ordered structure were synthesized. XRD, FT-IR and DRS UV-Vis techniques were used to characterize the samples. The results indicate incorporation of Cr into the MCM-41 framework,and dispersion of some Cr2O3 on the surface or/and in the bulk of the MCM-41. Test of catalytic properties of the series of samples for the topic reaction was carried out using a continuous-flow fixed-bed quartz reactor. Factors influencing the catalytic performance for this title reaction, such as Cr/Si ratio in MCM-41 and reaction temperature were investigated. The experimental results indicate that over the 5%CrMCM-41 a 43.27% conversion of ethane and a 86.70% selectivity for ethylene were achieved in the ethane dehydrogenation with CO2 to ethylene at 973 K. It is suggested that both Cr6+ and Cr3+ are the catalytic activity center.

  8. Synthesis and microwave absorbing properties of FeNi alloy incorporated ordered mesoporous carbon-silica nanocomposite

    Science.gov (United States)

    Li, Guoxian; Guo, Yunxia; Sun, Xin; Wang, Tao; Zhou, Jianhua; He, Jianping

    2012-11-01

    Ordered mesoporous carbon-silica/FeNi nanocomposite were prepared by a sol-gel method and following sintering process. The electromagnetic parameters were measured in the 0.5-18 GHz range. Compared with ordered mesoporous carbon-silica composite, the permittivity of ordered mesoporous carbon-silica/FeNi nanocomposite decreases, while the permeability almost remains unchanged. The optimal reflection loss of ordered mesoporous carbon-silica/FeNi nanocomposite can reach -45.6 dB at 11.1 GHz for a layer thickness of 3.0 mm. The enhanced microwave absorption of the mesoporous carbon-silica/FeNi nanocomposite is due to better balance between the complex permittivity and permeability, geometrical effect, as well as multiple reflections by the ordered mesoporous structure.

  9. Effect of fat chain length of sorbitan surfactant on the porosity of mesoporous silica

    Directory of Open Access Journals (Sweden)

    Marco Antonio Utrera Martines

    2009-08-01

    Full Text Available The influence of the fat chain length of sorbitan surfactant was systematically explored, especially its influence on the material pore size. Then, mesoporous silica was synthesized according to a two-step process that provides intermediary stable hybrid micelles using ethoxylated derivative of fatty esters of sorbitan surfactants as the directing-structure agent and tetraethyl orthosilicate Si(OEt4 as the silica source. Finally, the materials’ porosity could be controlled by adjusting the preparation parameters during the two steps synthesis of mesoporous silica.

  10. Stabilizing Unstable Amorphous Menthol through Inclusion in Mesoporous Silica Hosts.

    Science.gov (United States)

    Cordeiro, Teresa; Castiñeira, Carmem; Mendes, Davide; Danède, Florence; Sotomayor, João; Fonseca, Isabel M; Gomes da Silva, Marco; Paiva, Alexandre; Barreiros, Susana; Cardoso, M Margarida; Viciosa, Maria T; Correia, Natália T; Dionisio, Madalena

    2017-09-05

    The amorphization of the readily crystallizable therapeutic ingredient and food additive, menthol, was successfully achieved by inclusion of neat menthol in mesoporous silica matrixes of 3.2 and 5.9 nm size pores. Menthol amorphization was confirmed by the calorimetric detection of a glass transition. The respective glass transition temperature, Tg = -54.3 °C, is in good agreement with the one predicted by the composition dependence of the Tg values determined for menthol:flurbiprofen therapeutic deep eutectic solvents (THEDESs). Nonisothermal crystallization was never observed for neat menthol loaded into silica hosts, which can indicate that menthol rests as a full amorphous/supercooled material inside the pores of the silica matrixes. Menthol mobility was probed by dielectric relaxation spectroscopy, which allowed to identify two relaxation processes in both pore sizes: a faster one associated with mobility of neat-like menthol molecules (α-process), and a slower, dominant one due to the hindered mobility of menthol molecules adsorbed at the inner pore walls (S-process). The fraction of molecular population governing the α-process is greater in the higher (5.9 nm) pore size matrix, although in both cases the S-process is more intense than the α-process. A dielectric glass transition temperature was estimated for each α (Tg,dielc(α)) and S (Tg,dielc(S)) molecular population from the temperature dependence of the relaxation times to 100 s. While Tg,dielc(α) agrees better with the value obtained from the linearization of the Fox equation assuming ideal behavior of the menthol:flurbiprofen THEDES, Tg,dielc(S) is close to the value determined by calorimetry for the silica composites due to a dominance of the adsorbed population inside the pores. Nevertheless, the greater fraction of more mobile bulk-like molecules in the 5.9 nm pore size matrix seems to determine the faster drug release at initial times relative to the 3.2 nm composite. However, the latter

  11. Bio-templated synthesis of highly ordered macro-mesoporous silica material for sustained drug delivery

    Science.gov (United States)

    Qu, Fengyu; Lin, Huiming; Wu, Xiang; Li, Xiaofeng; Qiu, Shilun; Zhu, Guangshan

    2010-05-01

    The bimodal porous structured silica materials consisting of macropores with the diameter of 5-20 μm and framework-like mesopores with the diameter of 4.7-6.0 nm were prepared using natural Manchurian ash and mango linin as macropored hard templates and P123 as mesopore soft templates, respectively. The macroporous structures of Manchurian ash and mango linin were replicated with the walls containing highly ordered mesoporous silica as well. As-synthesized dual porous silica was characterized by scanning electron microscope (SEM), powder X-ray diffraction (XRD), transmission electron microscope (TEM) and nitrogen adsorption/desorption, fourier transform IR (FTIR) spectroscopy, and thermo-gravimetric analyzer (TGA). Ibuprofen (Ibu) was employed as a model drug and the release profiles showed that the dual porous material had a sustained drug delivery capability. And such highly ordered dual pore silica materials may have potential applications for bimolecular adsorption/separation and tissue repairing.

  12. Mesoporous Silica Materials Synthesized via Sol-Gel Methods Modified with Ionic Liquid and Surfactant Molecules

    Institute of Scientific and Technical Information of China (English)

    Cun-ying Xu; Ru-lan Tang; Yi-xin Hu; Peng-xiang Zhang

    2008-01-01

    Mesoporous silica materials were synthesized via a sol-gel method employing a room temperature ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate, [bmim][BF4]) as a new solvent medium and further modified with surfactant (hexadecyl-trimethyl-ammonium bromide, CTAB) as a pore templating material. The synthesized samples were characterized by the transmission electron microscopy, X-ray diffraction, and N2 adsorption-desorption techniques. The results indicated that the mesoporous silica synthesized by using [bmim][BF4] and CTAB as mixed templates showed better mesostructural order and smaller pore size, compared with mesoporous silica materials synthesized by using single [bmim][BF4]as template under the same conditions. This indicates that the presence of surfactant can affect the microstructures of silica prepared by the present synthesis method.

  13. Kinetic study of the catalytic pyrolysis of elephant grass using Ti-MCM-41

    Energy Technology Data Exchange (ETDEWEB)

    Fontes, Maria do Socorro Braga; Melo, Dulce Maria de Araujo; Rodrigues, Glicelia, E-mail: socorro.fontes@yahoo.com.br [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil); Barros, Joana Maria de Farias [Universidade Federal de Campina Grande (UFCG), Cuite, PB (Brazil). Dept. de Quimica; Braga, Renata Martins [Universidade Federal da Paraiba (UFPB/CEAR/DEER), Joao Pessoa, PB (Brazil). Centro de Energias Alternativas e Renovaveis. Dept. de Engenharia de Energia Renovaveis

    2014-08-15

    This work aimed to study the kinetics of thermal and catalytic pyrolysis using Ti-MCM-41 as catalyst in order to assess the catalytic pyrolysis efficiency compared to thermal pyrolysis of elephant grass. Ti-MCM-41 molecular sieve was synthesized by hydrothermal method from hydrogel with the following molar composition: 1.00 CTMABr: 4.00 SiO{sub 2}:X TiO{sub 2}: 1 + X Na{sub 2}O: 200.00 H{sub 2}O, which structure template used was cetyltrimethylammonium bromide (CTMABr). The materials synthesized were characterized by X-ray diffraction, IR spectroscopy, thermogravimetric analysis and specific area by the BET method, for subsequent application in the biomass pyrolysis process. The kinetic models proposed by Vyazovkin and Flynn-Wall were used to determine the apparent activation energy involved in the thermal and catalytic pyrolysis of elephant grass and the results showed that the catalyst used was effective in reducing the apparent activation energy involved in the thermal decomposition of elephant grass. (author)

  14. Single particle dynamics of water confined in a hydrophobically modified MCM-41-S nanoporous matrix

    Science.gov (United States)

    Faraone, Antonio; Liu, Kao-Hsiang; Mou, Chung-Yuan; Zhang, Yang; Chen, Sow-Hsin

    2009-04-01

    The single particle dynamics of water confined in a hydrophobically modified MCM-41-S sample has been studied using three high resolution quasielastic neutron scattering spectrometers in the temperature range from 300 to 210 K. A careful modeling of the dynamics allowed us to obtain good agreement among the results obtained with the three instruments, which have very different energy resolutions. The picture arising from the data is that, because of the heterogenous environment experienced by the water molecules, the dynamics show a broad distribution of relaxation times. However, the Fickian diffusive behavior is retained. In the investigated temperature range we found no evidence of the dynamic crossover, from a non-Arrhenius to an Arrhenius behavior, which was detected for water confined in hydrophilic MCM-41-S. This finding is in agreement with what was reported by Chu et al. [Phys. Rev. E 76, 021505 (2007)] for water confined in other hydrophobic confining media that the dynamic crossover takes place at a much lower temperature. The results reported in the paper help clarify the role that the chemical interaction between the water molecules and the walls of the confining host plays in determining the characteristics of the water dynamics, as compared to purely geometric constraints such as the size and shape of the pores.

  15. Alkylation of Hydroquinone with tert-Butyl Alcohol over Bis[(perfluoroalkyl)sulfonyl]imides Supported on MCM-41

    Institute of Scientific and Technical Information of China (English)

    YUAN, Yu-Bin; NIE, Jin; ZHANG, Zheng-Bo; ZHOU, San-Yi

    2006-01-01

    Bis[(perfluoroalkyl)sulfonyl]imides [HN(SO2Rf)2, and Rf represents the perfluorinated alkyl group] supported on MCM-41 were synthesized and characterized by XRD, FTIR, SEM, TGA and N2-adsorption techniques. The supported catalysts, HN(SO2Rf)2/MCM-41, were used as the catalysts for the tert-butylation of hydroquinone (HQ)with tert-butyl alcohol (TBA) in the liquid phase. A high yield (52.0%) of 2-tert-butyl hydroquinone (TBHQ) could be obtained in the presence of 5 mol% HN(SO2C4F9)2/MCM-41 under the optimized reaction conditions and the heterogeneous catalyst could be recycled at least 6 times without substantial loss of activity.

  16. Nanostructured mesoporous silica: new perspectives for fighting antimicrobial resistance

    Energy Technology Data Exchange (ETDEWEB)

    Voicu, Georgeta; Dogaru, Ionuţ; Meliţă, Daniela; Meştercă, Raluca; Spirescu, Vera; Stan, Eliza; Tote, Eliza [Politehnica University of Bucharest, Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Applied Chemistry and Materials Science (Romania); Mogoantă, Laurenţiu [University of Medicine and Pharmacy of Craiova, Research Center for Microscopic Morphology and Immunology (Romania); Mogoşanu, George Dan [University of Medicine and Pharmacy of Craiova, Department of Pharmacognosy & Phytotherapy, Faculty of Pharmacy (Romania); Grumezescu, Alexandru Mihai, E-mail: grumezescu@yahoo.com [Politehnica University of Bucharest, Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Applied Chemistry and Materials Science (Romania); Truşcă, Roxana [Metav SA-CD S.A. (Romania); Vasile, Eugeniu [Politehnica University of Bucharest, Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Applied Chemistry and Materials Science (Romania); Iordache, Florin [Institute of Cellular Biology and Pathology of Romanian Academy, “Nicolae Simionescu”, Department of Fetal and Adult Stem Cell Therapy (Romania); Chifiriuc, Mariana-Carmen [University of Bucharest, Microbiology Department, Faculty of Biology (Romania); Holban, Alina Maria [Politehnica University of Bucharest, Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Applied Chemistry and Materials Science (Romania)

    2015-05-15

    This paper investigates the antimicrobial potential of nanostructured mesoporous silica (NMS) functionalized with essential oils (EOs) and antibiotics (ATBs). The NMS networks were obtained by the basic procedure from cetyltrimethylammonium bromide and tetraethyl orthosilicate in the form of granules with diameters ranging from 100 to 300 nm with an average pore diameter of 2.2 nm, as confirmed by the BET–TEM analyses. The Salvia officinalis (SO) and Coriandrum sativum (CS) EOs and the streptomycin and neomycin ATBs were loaded in the NMS pores. TG analysis was performed in order to estimate the amount of the entrapped volatile EOs. The results of the biological analyses revealed that NMS/SO and NMS/CS exhibited a very good antimicrobial activity to an extent comparable or even superior to the one triggered by ATB, and a good in vitro and in vivo biocompatibility. Due to their regular pores, high biocompatibility, antimicrobial activity, and capacity to stabilize the volatile EOs, the obtained NMS can be used as an efficient drug delivery system for further biomedical applications.

  17. Mesoporous silica nanoparticles as a biomolecule delivery vehicle in plants

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, Hashmath I., E-mail: hashmath.i@deakin.edu.au [Deakin University, Centre for Chemistry and Biotechnology, School of Life and Environmental Sciences (Australia); Yi, Zhifeng [Deakin University, Institute for Frontier Materials (Australia); Rookes, James E. [Deakin University, Centre for Chemistry and Biotechnology, School of Life and Environmental Sciences (Australia); Kong, Lingxue X. [Deakin University, Institute for Frontier Materials (Australia); Cahill, David M. [Deakin University, Centre for Chemistry and Biotechnology, School of Life and Environmental Sciences (Australia)

    2013-06-15

    We report the uptake by wheat, lupin and Arabidopsis of mesoporous silica nanoparticles functionalised with amine cross-linked fluorescein isothiocyanate (MSN-APTES-FITC). The preparation of these particles at room temperature enabled the synthesis of 20 nm particles that contained a network of interconnected pores around 2 nm in diameter. The uptake and distribution of these nanoparticles were examined during seed germination, in roots of plants grown in a hydroponic system and in whole leaves and roots of plants via vacuum infiltration. The nanoparticles did not affect seed germination in lupin and there was no phytotoxicity. Following germination of wheat and lupin grown in a nutrient solution containing nanoparticles, they were found within cells and cell walls of the emerging root and in the vascular transport elements, the xylem, and in other associated cells. In leaves and roots of Arabidopsis the nanoparticles were found, following vacuum infiltration of whole seedlings, to be taken up by the entire leaf and they were principally found in the intercellular spaces of the mesophyll but also throughout much of the root system. We propose that MSNs could be used as a novel delivery system for small molecules in plants.

  18. Mesoporous Silica Nanoparticles under Sintering Conditions: A Quantitative Study.

    Science.gov (United States)

    Silencieux, Fanny; Bouchoucha, Meryem; Mercier, Olivier; Turgeon, Stéphane; Chevallier, Pascale; Kleitz, Freddy; Fortin, Marc-André

    2015-12-01

    Thin films made of mesoporous silica nanoparticles (MSNs) are finding new applications in catalysis, optics, as well as in biomedicine. The fabrication of MSNs thin films requires a precise control over the deposition and sintering of MSNs on flat substrates. In this study, MSNs of narrow size distribution (150 nm) are synthesized, and then assembled onto flat silicon substrates, by means of a dip-coating process. Using concentrated MSN colloidal solutions (19.5 mg mL(-1) SiO2), withdrawal speed of 0.01 mm s(-1), and well-controlled atmospheric conditions (ambient temperature, ∼ 70% of relative humidity), monolayers are assembled under well-structured compact patterns. The thin films are sintered up to 900 °C, and the evolution of the MSNs size distributions are compared to those of their pore volumes and densities. Particle size distributions of the sintered thin films were precisely fitted using a model specifically developed for asymmetric particle size distributions. With increasing temperature, there is first evidence of intraparticle reorganization/relaxation followed by intraparticle sintering followed by interparticle sintering. This study is the first to quantify the impact of sintering on MSNs assembled as thin films.

  19. Morin Flavonoid Adsorbed on Mesoporous Silica, a Novel Antioxidant Nanomaterial.

    Science.gov (United States)

    Arriagada, Francisco; Correa, Olosmira; Günther, Germán; Nonell, Santi; Mura, Francisco; Olea-Azar, Claudio; Morales, Javier

    20