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Muge Sari Yilmaz Ilayda Acaroglu Degitz Sabriye Piskin 《Journal of Thermal Analysis and Calorimetry》2017,130(2):727-734
The aim of the current study is to obtain the thermal behavior and kinetic analyses of the removal of surfactant from MCM-41 synthesized from tailings slurry at different heating rates. X-ray diffraction and thermogravimetric analyses were carried out to determine the characterization of the synthesized samples. Kissinger–Akahira–Sunose and Friedman isoconversional kinetic methods were applied for the purpose of determining the kinetic analysis parameters of the decomposition of surfactant from the mesoporous molecular sieves MCM-41 under non-isothermal conditions. For the comparison of these results, MCM-41 was synthesized from a pure silica source. The thermal behaviors of MCM-41 synthesized from tailings slurry do not differ from samples synthesized from pure silica during the decomposition reactions. The kinetic analysis’ results indicate that the decomposition reactions of the synthesized MCM-41 samples had complex reaction mechanisms. 相似文献
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P. Lizák J. Legerská S. C. Mojumdar 《Journal of Thermal Analysis and Calorimetry》2013,111(2):1013-1018
Molecular sieves MCM-41 were synthesized from rice husk ash (RHA) as alternative sources of silica, called RHA MCM-41. The material was synthesized by a hydrothermal method from a gel with the molar composition 1.00 CTMABr:4.00 SiO2:1.00 Na2O:200.00 H2O at 100 °C for 120 h with pH correction. The cetyltrimethylammonium bromide (CTMABr) was used as a structure template. The material was characterized by X-ray powder diffraction, FTIR, TG/DTG, and surface area determination by the BET method. The kinetics models proposed by Ozawa, Flynn–Wall, and Vyazovkin were used to determine the apparent activation energy for CTMA+ species decomposition from the pores of MCM-41 material. The results were compared with those obtained from the MCM-41 synthesized with silica gel. The synthesized material had specific surface area, size, and pore volume as specified by mesoporous materials developed from conventional sources of silica. 相似文献
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模板剂对全硅MCM-41介孔分子筛结构的影响 总被引:10,自引:0,他引:10
分别采用十六烷基三甲基溴化铵和十六烷基三乙基溴化铵作为模板剂,硅溶胶为硅源,用水热晶化法在碱性(NaOH)介质中合成了MCM-41介孔分子筛样品.通过XRD、N2吸附-脱附、TG-DTA、IR等测试手段对这两种样品进行了对比表征分析.考察了两种不同模板剂对其晶体结构、比表面及孔径大小的影响.实验结果表明,相对于十六烷基三甲基溴化铵做模板剂,采用大头基的十六烷基三乙基溴化铵可以合成较大孔径和孔容(分别为4.72 nm和1.14 cm3•g-1)的MCM-41介孔分子筛,而且具有较窄的孔径分布,因此对于合成大孔径的介孔分子筛MCM-41,十六烷基三乙基溴化铵是一种很好的模板剂. 相似文献
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Macroscopic mesoporous silica spheres have been fabricated by alternatively depositing preformed MCM-41 nanoparticles and polyelectrolytes onto polystyrene lattices. High surface area hollow mesoporous spheres were obtained by removal of the core by solvent or calcination. Further, the versatility of the layer-by-layer (LBL) method was extended to fabricate magnetite-mesoporous silica composites by depositing magnetite and MCM-41 nanoparticles onto polystyrene beads. Such high surface area composites are important since the mesopores can be used for encapsulation of varied materials like enzymes and drugs while the presence of magnetite ensures application in biocatalysis and separation under magnetic field. 相似文献
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The incorporation of CdS nanoparticles, prepared in reverse micellar systems, into thiol-modified mesoporous silica, such as FM41 (functionalized MCM-41) and FM48 (functionalized MCM-48), has been investigated. The nanoparticles were immobilized in the mesopores via the incorporation of water droplets of the reverse micelles. A particle-sieving effect for FM41 having large (L-FM41, 3.8 nm) and medium (M-FM41, 3.6 nm) pore size was observed, in that the incorporation of the CdS nanoparticles was decreased with increasing particle size and with decreasing pore size of the FM41. Chemical vapor deposition treatment employed to narrow the mesopores of the CdS-FM41 enhanced the stability of CdS nanoparticles against heat treatment. The CdS-FM41 composites demonstrated photocatalytic activity for H(2) generation from 2-propanol aqueous solution, the better photocatalytic activity being obtained with the larger pore size for CdS-L-FM41. Copyright 2001 Academic Press. 相似文献
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J. Goworek W. Stefaniak Agnieszka Kierys Mariola Iwan 《Journal of Thermal Analysis and Calorimetry》2007,87(1):217-222
Mesoporous silica material of MCM-41 type was synthesized by co-condensation
of highly concentrated octyltriethoxysilane (OTEOS), octadecyltriethoxysilane
(ODTEOS) and tetraethoxysilane (TEOS). The obtained hybrid materials were
characterized using XRD, TG-DSC and low temperature adsorption/desorption
of nitrogen. It was shown that the applied method of synthesis allows to obtain
silica of MCM-41 type with a high degree of hydrocarbon saturation. 相似文献
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Dá?a Halamová Vladimír Zeleňák 《Journal of inclusion phenomena and macrocyclic chemistry》2012,72(1-2):15-23
Hexagonally ordered mesoporous silica material MCM-41 (SBET?=?1090?m2/g, pore size?=?31.2 ?) was synthesized and modified by 3-aminopropyl ligands. The differences in an uptake and subsequent release of anti-inflammatory drug naproxen from unmodified and amino modified MCM-41 samples were studied. The prepared materials were characterized by high resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM), nitrogen adsorption/desorption, Fourier-Transform Infrared Spectroscopy (FT-IR), Small-angle X-ray scattering (SAXS), thermoanalytical methods (TG/DTA) and elemental analysis. The amount of the drug released was monitored with thin layer chromatography (TLC) with densitometric detection in defined time intervals. The amounts of the released naproxen from mesoporous silica MCM-41/napro and amine-modified silica sample A-MCM-41/napro were 95 and 90% of naproxen after 72?h. In this study we compare the differences of release profiles from mesoporous silica MCM-41 and mesoporous silica SBA-15. 相似文献
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以溶液硅源和表面硅源两种合成路线在SiO2颗粒表面进行了MCM-41的原位合成,结果发现以两种方式均可得到MCM-41的有序结构。溶液硅源原位合成MCM-41的长程结构较好,两种硅源原位合成的MCM-41均能够在脱除模板剂过程中保持其长程有序结构。表面硅源原位合成MCM-41的孔径分布较窄,最可几孔径为3.81nm。本文还考察了OH/CTABr及SiO2/OH比对表面硅源原位合成MCM-41长程结构特征的影响。 相似文献
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Yang H Zheng K Zhang Z Shi W Jing S Wang L Zheng W Zhao D Xu J Zhang P 《Journal of colloid and interface science》2012,369(1):317-322
Ordered MCM-41-type mesoporous silica nanoparticles (MSNs) with pore size of 2.6 nm were synthesized and were further modified with various amounts of 3-aminopropyltriethoxysilane (APTES), respectively, by a direct co-condensation method. These amine functionalized mesoporous silica nanoparticles (Am-MSNs) were employed to complex with plasmid DNA (pDNA) to study their adsorption and protection capacities. The results demonstrate the MSNs functionalized with aminopropyl groups present advanced adsorption capacities for pDNA immobilization. And Am-MSNs with high APTES amount lead to high amount of pDNA adsorption. Further investigation of pDNA protection shows that Am-MSNs with moderate APTES amount could completely protect pDNA from enzymatic degradation, while those with smaller and/or higher amount of APTES could partially provide protection of pDNA. 相似文献
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Osamu Terasaki Zheng Liu Tetsu Ohsuna Hyun June Shin Ryong Ryoo 《Microscopy and microanalysis》2002,8(1):35-39
Structures of Pt-nanowires, synthesized in channels of silica mesoporous materials MCM-41, SBA-15 and MCM-48, were investigated by transmission electron microscopy. One dimensional (1D) Pt-nanowires were formed inside the channels of the MCM-41, and were single crystals with a length of several tens to several hundreds nanometers and a diameter of ca. 3 nm pt-nanowires synthesized in SBA-15 formed a new 3D-network following 3D-pore geometry of SBA-15; that is, the main 1D-channels are interconnected to each other through randomly distributed tunnels. These Pt-nanowires showed a well single crystalline. MCM-48 has two non-intersecting chiral channels, and Pt-networks were mostly formed in one of the two channels. Therefore the networks were also chiral; however, the chirality of Pt-networks remained to be determined. It was shown that all Pt-nanowires were formed following the channel geometries of silica mesoporous materials used. 相似文献
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An approach of immobilizing mobile crystalline material (MCM)-41 mesoporous silica nanoparticles on the inner wall of an open-tubular (OT) capillary as the support for coating chiral selector of cellulose tris(3,5-dimethylphenyl-carbamate) (CDMPC) was carried out. By taking advantage of the improved phase ratio of OT capillary with the immobilization of MCM-41 mesoporous material, the cellulose derivative of CDMPC as the chiral selector was simply coated on the MCM-41 nanoparticle layer via the hydrogen-bonding interaction, and the enantioseparation was successively carried out. Eight pairs of acidic, neutral and basic enantiomers were resolved in capillary electrochromatography or capillary liquid chromatography mode. The concentration of CDMPC for coating was systematically investigated to obtain the optimized chromatographic properties on enantioseparation by controlling the supposed film thickness of CDMPC on MCM-41 nanoparticle layer. Comparing with a bare fused silica capillary column coated with CDMPC under the same coating procedure as MCM-41-modified capillary did, the MCM-41-modified capillary column offered much higher enantioselectivity. This result indicated the significance of using the mesoporous nanoparticles as the electrochromatographic support to enhance the phase ratio of OT capillary column in capillary electrochromatography and capillary liquid chromatography. For investigating the effect of experimental conditions on the enantioseparation with this prepared OT capillary column, the content of organic modifier acetonitrile in the mobile phase was thus extensively evaluated to achieve a better chiral separation. 相似文献
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The mesoporous material MCM-41 was synthesized by a hydrothermal method, and perylene bisimide dye was incorporated into its channels by impregnation. The absorption, FTIR, fluorescence emission, and decay spectra of perylene bisimide dye in CHCl3 and in MCM-41 were studied to investigate the effect of the one-dimensional channel of MCM-41 on the photophysical and photochemical properties of the dye. The results indicated that the nanochannels of MCM-41 shifted the absorption and emission maxima to red and broadened the spectra, with loss of vibrational structure. The fluorescence decay curves fitted a double-exponential function and the lifetime of perylene bisimide dye in MCM-41 was prolonged. The huge surface area of the mesoporous molecular sieve MCM-41 prevented aggregation of dye molecules, which can thus be used at high concentration. 相似文献
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Guo-Dong Chen Zhi-Dan Tian Ling-Zhi Wang Jin-Long Zhang Masakazu Anpo 《Research on Chemical Intermediates》2011,37(8):891-899
The fluorescent dye molecules, 4-piperidine-1,8-naphthalimide, were successfully fixed into the amino modified pore channel
of mesoporous MCM-41 type materials by in situ reaction of 4-piperidinyl-1,8-naphthalic anhydride with the amino group. The
formation of amide bonds on the pore surface was verified by infrared spectra. The maximum fluorescence emission peak of this
hybrid material has a red shift of 13 nm compared to that of a naphthalimide derivative in ethanol solution. Moreover, the
fluorescence intensity of dye molecules grafted into Ce-doped MCM-41 is higher than that in pure silica MCM-41. This phenomenon
is attributed to the inhibited internal electron transfer from piperidine to naphthalimide groups by Ce4+, thus improving the fluorescence intensity of the naphthalimide group. The unique fluorescence behavior of the 1,8-naphthalimide
derivative doped hybrid mesoporous material makes it a good candidate for the metal ions microdetection. 相似文献
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Hukkamäki J Suvanto S Suvanto M Pakkanen TT 《Langmuir : the ACS journal of surfaces and colloids》2004,20(23):10288-10295
Mesoporous high surface area MCM-41 and SBA-15 type silica materials with fibrous morphology were synthesized and used as support materials for the ALCVD (atomic layer chemical vapor deposition) preparation of Co/MCM-41 and Co/SBA-15 catalysts. Co/MCM-41 and Co/SBA-15 catalysts were prepared by deposition of Co2(CO)8 from the gas phase onto the surfaces of preheated support materials in a fluidized bed reactor. For both silica materials, two different kinds of preparation methods, direct deposition and a pulse deposition method, were used. Pure silica supports as well as supported cobalt catalysts were characterized by various spectroscopic (IR) and analytical (X-ray diffraction, Brunauer-Emmett-Teller, elemental analysis) methods. MCM-41 and SBA-15 fibers showed considerable ability to adsorb Co2(CO)8 from the gas phase. For MCM-41 and SBA-15 silicas, cobalt loadings of 13.7 and 12.1 wt % were obtained using the direct deposition method. The cobalt loadings increased to 23.0 and 20.7 wt % for MCM-41 and SBA-15 silicas, respectively, when the pulse deposition method was used. The reduction behavior of silica-supported cobalt catalysts was found to depend on the catalyst preparation method and on the mesoporous structure of the support material. Almost identical reduction properties of SBA-15-supported catalysts prepared by different deposition methods are explained by the structural properties of the mesoporous support and, in particular, by the chemical structure of the inner surfaces and walls of the mesopores. Pulse O2/H2 chemisorption experiments showed catalytically promising redox properties and surface stability of the prepared MCM-41- and SBA-15-supported cobalt catalysts. 相似文献
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Using mesoporous silica MCM-41 for in-line enrichment of atmospheric volatile organic compounds 总被引:1,自引:0,他引:1
A mesoporous silica MCM-41 with pore size of 29A was synthesized and assessed for its applicability as a sorbent for in-line trapping of volatile organic compounds (VOCs) from air samples. Several commercially available microporous carbon molecular sieves, i.e., Carbosieve SIII, Carboxen 1000, Carboxen 1003, and Carbotrap purchased from Supelco, were employed to form either single sorbent traps or multi-sorbent traps for comparing adsorption properties with those of the silica MCM-41. A standard gas mixture containing more than 50 target compounds with size varying from C(2) to C(12) was adsorbed by these sorbents and the per carbon response of flame ionization detection (FID) for the target compounds was calculated for obtaining the adsorption profiles. While the multi-carbon sorbents show very uniform adsorption ability across the entire carbon range from C(3) to C(12), the mesoporous silica MCM-41, however, shows little sorption for smaller molecules from C(3) to C(7), but exhibit comparable sorption ability for C(8)-C(12) compounds. Desorption at various temperatures indicates that C(8)-C(12) compounds once trapped can be easily released at moderate temperatures of about 150 degrees C, whereas for carbon sorbents the desorption temperatures for sufficient recovery need to go beyond 300 degrees C due to much tighter hold-up in the microporous structure. Sorption ability for MCM-41 is also reflected on linearity. Compounds with sufficient sorption as suggested by the adequate per carbon response also exhibit excellent precision and linearity with R(2) close to unity, an important requirement for quantitative analysis of ambient VOCs. 相似文献
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Lai CY Trewyn BG Jeftinija DM Jeftinija K Xu S Jeftinija S Lin VS 《Journal of the American Chemical Society》2003,125(15):4451-4459
An MCM-41 type mesoporous silica nanosphere-based (MSN) controlled-release delivery system has been synthesized and characterized using surface-derivatized cadmium sulfide (CdS) nanocrystals as chemically removable caps to encapsulate several pharmaceutical drug molecules and neurotransmitters inside the organically functionalized MSN mesoporous framework. We studied the stimuli-responsive release profiles of vancomycin- and adenosine triphosphate (ATP)-loaded MSN delivery systems by using disulfide bond-reducing molecules, such as dithiothreitol (DTT) and mercaptoethanol (ME), as release triggers. The biocompatibility and delivery efficiency of the MSN system with neuroglial cells (astrocytes) in vitro were demonstrated. In contrast to many current delivery systems, the molecules of interest were encapsulated inside the porous framework of the MSN not by adsorption or sol-gel types of entrapment but by capping the openings of the mesoporous channels with size-defined CdS nanoparticles to physically block the drugs/neurotransmitters of certain sizes from leaching out. We envision that this new MSN system could play a significant role in developing new generations of site-selective, controlled-release delivery nanodevices. 相似文献