Functionalized bimodal mesoporous silicas as carriers for controlled aspirin delivery

International Nuclear Information System (INIS)

Gao Lin; Sun Jihong; Li Yuzhen

2011-01-01

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 f t =kt n 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. - Graphical abstract: Loading (A) and release profiles (B) of aspirin in N-BMMs and N-MCM-41 indicated that BMMs have more drug loading capacity and faster release rate than that MCM-41. Highlights: → Bimodal mesoporous silicas (BMMs) and MCM-41 modified with amino group via post-treatment procedure. → Loading and release profiles of aspirin in modified BMMs and MCM-41. → Modified BMMs have more drug loading capacity and faster release rate than that modified MCM-41.

Efficient adsorption concentration and photolysis of acetaldehyde on titania-mesoporous silica composite

Science.gov (United States)

Yamaguchi, Satoshi; Matsumoto, Akihiko

2017-07-01

Titania-mesoporous silica composite (TiO2/MCM) was prepared by hydrolysis of titaniumtetraisopropoxide (TTIP) with the presence of mesoporous silica MCM-41. The TiO2/MCM samples consisted of highly dispersed TiO2 on the surface of MCM-41. Dynamic adsorption and photocatalytic decomposition features for acetaldehyde (CH3CHO) were measured by flow method. The amount of CH3CHO decomposition on TiO2/MCM-41 increased with the TiO2 amount, suggesting that a large amount of CH3CHO was adsorbed on mesopores of MCM-41 of the TiO2/MCM and was efficiently decomposed on finely dispersed TiO2 surface by ultraviolet irradiation.

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

International Nuclear Information System (INIS)

Torres, Cecilia C.; Urbano, Bruno F.; Campos, Cristian H.; Rivas, Bernabé L.; Reyes, Patricio

2015-01-01

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, 29 Si and 13 C solid state NMR, and N 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

Preparation of hierarchical micro-mesoporous aluminosilicate composites by simple Y zeolite/MCM-48 silica assembly

Energy Technology Data Exchange (ETDEWEB)

Enterría, Marina, E-mail: marina@incar.csic.es; Suárez-García, Fabián; Martínez-Alonso, Amelia; Tascón, Juan M.D.

2014-01-15

Highlights: • Hierarchical micro-mesoporous aluminosilicates were synthesized. • Y zeolite core/MCM-48 silica shell structures were obtained. • Y zeolite favors the formation of the mesostructure. • Porosity and structure can be varied by modifying the preparation variables. • Duration of the hydrothermal step has a great effect on the materials properties. -- Abstract: A simple procedure to obtain hierarchical micro-mesoporous aluminosilicate composites was developed by growing MCM-48 silica over commercial Y zeolite. The obtained hierarchical composites have a microporous core and a mesoporous shell. The process consists in assembling dispersed Y zeolite with a mesoporous silica phase that is formed “in situ” by “soft-templating” with cetryltrimethylammonium bromide (CTAB) as surfactant. The Y zeolite/MCM-48 silica ratio and aging time were varied to study their effects on the final porosity and structure of the hierarchical composites. The pore textural and structural characteristics of the composites did not match those of the corresponding Y zeolite/MCM-48 silica physical mixtures. This implies that the synthesized composites integrate micropores and mesopores in the same bulk. The obtained composites exhibited micropore and mesopore volumes ranging between 0.15–0.31 and 0.30–0.51 cm{sup 3}/g, respectively. X-ray diffraction and N{sub 2} adsorption results revealed that the presence of zeolite in the reaction medium favors the formation of mesopores in the obtained materials, especially for short hydrothermal treatments. TEM results showed that the obtained adsorbents are constituted by an integrated micro-mesoporous bimodal system in which Y zeolite is surrounded by a thin cover of MCM-48 silica.

Preparation of hierarchical micro-mesoporous aluminosilicate composites by simple Y zeolite/MCM-48 silica assembly

International Nuclear Information System (INIS)

Enterría, Marina; Suárez-García, Fabián; Martínez-Alonso, Amelia; Tascón, Juan M.D.

2014-01-01

Highlights: • Hierarchical micro-mesoporous aluminosilicates were synthesized. • Y zeolite core/MCM-48 silica shell structures were obtained. • Y zeolite favors the formation of the mesostructure. • Porosity and structure can be varied by modifying the preparation variables. • Duration of the hydrothermal step has a great effect on the materials properties. -- Abstract: A simple procedure to obtain hierarchical micro-mesoporous aluminosilicate composites was developed by growing MCM-48 silica over commercial Y zeolite. The obtained hierarchical composites have a microporous core and a mesoporous shell. The process consists in assembling dispersed Y zeolite with a mesoporous silica phase that is formed “in situ” by “soft-templating” with cetryltrimethylammonium bromide (CTAB) as surfactant. The Y zeolite/MCM-48 silica ratio and aging time were varied to study their effects on the final porosity and structure of the hierarchical composites. The pore textural and structural characteristics of the composites did not match those of the corresponding Y zeolite/MCM-48 silica physical mixtures. This implies that the synthesized composites integrate micropores and mesopores in the same bulk. The obtained composites exhibited micropore and mesopore volumes ranging between 0.15–0.31 and 0.30–0.51 cm 3 /g, respectively. X-ray diffraction and N 2 adsorption results revealed that the presence of zeolite in the reaction medium favors the formation of mesopores in the obtained materials, especially for short hydrothermal treatments. TEM results showed that the obtained adsorbents are constituted by an integrated micro-mesoporous bimodal system in which Y zeolite is surrounded by a thin cover of MCM-48 silica

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.

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.

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

International Nuclear Information System (INIS)

Ursachi, Irina; Vasile, Aurelia; Ianculescu, Adelina; Vasile, Eugeniu; Stancu, Alexandru

2011-01-01

Highlights: → A quick and facile route for the synthesis of iron oxide/MCM-41 nanocomposite. → Magnetic nanoparticles were stabilized inside the pores of mesoporous silica MCM-41. → The pore size of MCM-41 dictates the properties of iron oxide nanoparticles. → 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 -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.

Recycling of surfactant template in mesoporous MCM-41 synthesis

Science.gov (United States)

Lai, J. Y.; Twaiq, F.; Ngu, L. H.

2017-06-01

The recycling of surfactant template is investigated through the reuse of the surfactant template in the mesoporous MCM-41 synthesis process. In the synthesis of MCM-41, tetraethylorthosilicate (TEOS) solution in water was utilized as the silica source while hexadecyltrimethylammonium bromide (CTAB) solution in ethyl alcohol was used as a surfactant template. The synthesized gel is formed thoroughly by mixing the two solutions under acid conditions with a pH value of 0.5 for 1 hour and kept for crystallization for 48 hours. The as-synthesized MCM-41 powder is recovered by filtration while the filtrate (mother liquor) was then reused for the second synthesis cycle. The synthesis procedure was repeated till no further solid product was formed. The synthesized gel was not produced in the unifying solution in the fifth cycle of MCM-41 synthesis. The quality of the calcined MCM-41 powder produced in each synthesis cycle was evaluated by calculating the amount of MCM-41 produced and the surface area of the powder product. The result showed that 1.28, 0.37, 1.64, 1.90 and 0.037 g were obtained in the 1st, 2nd, 3rd, 4th and 5th synthesis cycle, respectively. The surface area of the powder produced was found to be 1170, 916, 728, and 508 m2/g for 1st, 2nd, 3rd and 4th respectively. The concentration of the surfactant template has reached value lower than the critical micelle concentration (CMC) and remained constant after the 4th cycle. There was no further formation of gel due to low availability in the interaction between silicate anions and surfactant cations when the amount of TEOS was fixed for every synthesis cycle.

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. Crown Copyright © 2010. Published by Elsevier Inc. All rights reserved.

Thermal and hydrothermal stability of ZrMCM-41 mesoporous ...

Indian Academy of Sciences (India)

Administrator

The mesoporous structure of the ZrMCM-41 mesoporous molecular sieve still retains after calcination at 750°C for 3 h or ... adsorption, sensor and petrochemical industry. 2–5. However, the ... the pH value of the mixed solution was adjusted to.

Synthesis and physicochemical properties of Zr-MCM-41 mesoporous molecular sieves and Pt/H3PW12O40/Zr-MCM-41 catalysts

International Nuclear Information System (INIS)

Chen, L.F.; Wang, J.A.; Norena, L.E.; Aguilar, J.; Navarrete, J.; Salas, P.; Montoya, J.A.; Del Angel, P.

2007-01-01

For the first time, modifications of the surface and framework of Si-MCM-41 by depositing a heteropolyacid on the surface and by introducing foreign Zr 4+ ions into the framework are investigated. The Zr-modified Si-MCM-41 mesoporous materials (hereafter referred as WSZn, n=Si/Zr=25, 15, 8, 4) were synthesized through a surfactant-templated preparation approach, using low-cost fumed silica as the Si precursor. After impregnation with 25 wt% of H 3 PW 12 O 40 , the surface Broensted acidity of the Pt/H 3 PW 12 O 40 /WSZn catalysts was greatly enhanced by 2-10 times relative to the bare WSZn support. Two kinds of supported heteropolyacids were formed: (i) bulk-like heteropolyacid crystals with unchanged Keggin structures, and (ii) highly dispersed heteropolyacid with distorted Keggin units. The formation of various kinds of heteropolyacid structures is closely related to the interaction between the heteropolyanions and the hydroxyl groups in the host support. - Graphical abstract: Modifications of the surface and framework of Si-MCM-41 by depositing a heteropolyacid on the surface and by introducing foreign Zr 4+ ions into the framework are investigated. Broensted acidity of the Pt/H 3 PW 12 O 40 /Zr-MCM-41 catalysts was greatly enhanced by 2-10 times relative to the bare Zr-MCM-41 support

A study of some fundamental physicochemical variables on the morphology of mesoporous silica nanoparticles MCM-41 type

Science.gov (United States)

Beltrán-Osuna, Ángela A.; Gómez Ribelles, José L.; Perilla, Jairo E.

2017-12-01

All variables affecting the morphology of mesoporous silica nanoparticles (MSN) should be carefully analyzed in order to truly tailored design their mesoporous structure according to their final use. Although complete control on MCM-41 synthesis has been already claimed, reproducibility and repeatability of results remain a big issue due to the lack of information reported in literature. Stirring rate, reaction volume, and system configuration (i.e., opened or closed reactor) are three variables that are usually omitted, making the comparison of product characteristics difficult. Specifically, the rate of solvent evaporation is seldom disclosed, and its influence has not been previously analyzed. These variables were systematically studied in this work, and they were proven to have a fundamental impact on final particle morphology. Hence, a high degree of circularity ( C = 0.97) and monodispersed particle size distributions were only achieved when a stirring speed of 500 rpm and a reaction scale of 500 mL were used in a partially opened system, for a 2 h reaction at 80 °C. Well-shaped spherical mesoporous silica nanoparticles with a diameter of 95 nm, a pore size of 2.8 nm, and a total surface area of 954 m2 g-1 were obtained. Final characteristics made this product suitable to be used in biomedicine and nanopharmaceutics, especially for the design of drug delivery systems.

Pore radius fine tuning of a silica matrix (MCM-41) based on the synthesis of alumina nanolayers with different thicknesses by atomic layer deposition

International Nuclear Information System (INIS)

Zemtsova, Elena G.; Arbenin, Andrei Yu.; Plotnikov, Alexander F.; Smirnov, Vladimir M.

2015-01-01

The authors investigated a new approach to modify the surface of the mesoporous silica matrix MCM-41. This approach is based on manipulating the chemical composition of the porous surface layer and also on fine tuning the pore radius by applying the atomic layer deposition (ALD) technique. The synthesis of alumina nanolayers was performed on the planar and the porous matrix (MCM-41) by the ALD technique using aluminum tri-sec-butoxide and water as precursors. The authors show that one cycle on silicon, using aluminum tri-sec-butoxide and water as precursors, results in a 1–1.2 Å increase in alumina nanolayer thickness. This is comparable to the increase in thickness per cycle for other precursors such as trimethylaluminum and aluminum chloride. The authors show that the synthesis of an Al 2 O 3 nanolayer on the pore surface of the mesoporous silica matrix MCM-41 by the ALD technique results in a regular change in the porous structure of the samples. The specific porosity (ml/g) of the MCM-41 was 0.95 and that of MCM-41 after 5 ALD cycles was 0.39. The pore diameter (nm) of MCM-41 was 3.3 and that of MCM-41 after 5 ALD cycles was 2.3

Ibuprofen in mesopores of Mobil Crystalline Material 41 (MCM-41): a deeper understanding.

Science.gov (United States)

Skorupska, Ewa; Jeziorna, Agata; Paluch, Piotr; Potrzebowski, Marek J

2014-05-05

In this work, we compared two methods (incipient wetness and melting) for the encapsulation of ibuprofen in the pores of Mobil Crystalline Material 41 (MCM-41) through NMR (nuclear magnetic resonance) spectroscopy. (1)H NMR spectra were recorded under very fast MAS (sample spinning 60 kHz) conditions in both 1D and 2D mode (NOESY sequence). We also performed (13)C cross-polarization magic angle spinning (CP/MAS) experiments, (13)C single pulse experiments (SPE), and (1)H-(13)C HSQC HR/MAS (heteronuclear single quantum coherence high resolution) HR/MAS correlations. Evaluation of the encapsulation methods included an analysis of the filling factor of the drug into the pores. The stability of Ibu/MCM in an environment of ethanol or water vapor was tested. Our study showed that melting a mixture of Ibu and MCM is a much more efficient method of confining the drug in the pores compared to incipient wetness. The optimal experiments for the former method achieved a filling factor of approximately 60%. We concluded that the major limitation to the applicability of the incipient wetness method (filling factor ca. 20%) is the high affinity of solvent (typically ethanol) for MCM-41. We found that even ethanol vapor can remove Ibu from the pores. When a sample of Ibu/MCM was stored for a few hours in a closed vessel with ethanol vapor, Ibu was transported from the pores to the outer walls of MCM. We observed a similar phenomenon with water vapor, although this process is slower compared to the analogous procedure using ethanol. Our study clearly demonstrates that existing methods used to encapsulate drugs in mesoporous silica nanoparticles (MSNs) require reevaluation.

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)

Multifunctional materials such as MCM-41÷Fe3O4÷folic acid as drug delivery system.

Science.gov (United States)

Popescu, Simona; Ardelean, Ioana Lavinia; Gudovan, Dragoş; Rădulescu, Marius; Ficai, Denisa; Ficai, Anton; Vasile, Bogdan Ştefan; Andronescu, Ecaterina

2016-01-01

In this study, MCM-41 mesoporous silica nanoparticles (NPs) and MCM-41÷Fe3O4 mesoporous silica NPs were prepared by sol-gel method using CTAB (cetyltrimethylammonium bromide) as template and TEOS (tetraethyl orthosilicate) as silica precursor in order to use these materials as drug delivery system (DDS) for different biologically active agents. The MCM-41 and MCM-41÷Fe3O4 mesoporous silica NPs were characterized using specific physico-chemical methods [transmission electron microscopy (TEM), scanning electron microscopy (SEM), nitrogen adsorption and desorption studies - BET (Brunauer-Emmett-Teller) method, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy], while the release studies were done by a high-performance liquid chromatography (HPLC)-modified method. The pH dependence of the delivery of folic acid from the mesoporous structures was analyzed and found that the release is pH sensitive. The lower delivery at strongly acid pH comparing with neutral/slightly alkaline pH could be beneficial because in stomach the folic acid can be destroyed.

Synthesis, characterization, and catalytic properties of stable mesoporous molecular sieve MCM-41 prepared from zeolite mordenite

International Nuclear Information System (INIS)

Wang Shan; Dou Tao; Li Yuping; Zhang Ying; Li Xiaofeng; Yan Zichun

2004-01-01

Mesoporous molecular sieves (denoted as M-MCM-41) with ordered hexagonal structure have been successfully synthesized from the assembly of precursors from preformed zeolite Mordenite with CTAB surfactant micelle in alkaline media. The samples were characterized by XRD, N 2 adsorption, IR and DTG. The materials exhibit highly hydrothermal stability, as compared with conventional MCM-41. Characterization results indicate that the mesoporous walls of M-MCM-41 contain the secondary building units similar to those in microporous crystal of zeolite Mordenite. In catalytic dealkylation of C10 + aromatic hydrocarbon, M-MCM-41 shows higher activities in comparison with Mordenite and MCM-41, which would be ascribed to the combination of advantages of both MCM-41 (large pores) and Mordenite (strong acidity). Furthermore, this synthesis strategy could be used as a new general method for the preparation of hydrothermally stable mesoporous aluminosilicate materials under alkaline conditions

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

International Nuclear Information System (INIS)

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

2010-01-01

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-cholropropyltrimethoxysilane (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 deg. 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.

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.

Synthesis of AL-MCM-41 using gravel drilling the source of silica from wells drilling

International Nuclear Information System (INIS)

Fontes, M.S.B.; Costa, C.C.; Melo, D.M.A.; Viana, L.M.; Viana, S.O.; Santos, L.M.

2016-01-01

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)

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.

Promotion effect of palladium on Co{sub 3}O{sub 4} incorporated within mesoporous MCM-41 silica for CO Oxidation

Energy Technology Data Exchange (ETDEWEB)

Hassan, Hassan M.A., E-mail: hassan.hassan@suezuniv.edu.eg [Department of Chemistry, Faculty of Science, Suez University, Suez (Egypt); Institut fur Anorganische Chemie und Strukturchemie, Heinrich-Heine Universitat, Dusseldorf (Germany); Betiha, Mohamed A. [Egyptian Petroleum Research Institute, Cairo 11727, Nasr City, Cairo (Egypt); Elshaarawy, Reda F.M. [Department of Chemistry, Faculty of Science, Suez University, Suez (Egypt); Institut fur Anorganische Chemie und Strukturchemie, Heinrich-Heine Universitat, Dusseldorf (Germany); Samy El-Shall, M. [Department of Chemistry, Virginia Commonwealth University Richmond, VA 23284-2006 (United States)

2017-04-30

Highlights: • Co{sub 3}O{sub 4} incorporated MCM-41 materials were successfully synthesized using MWI direct approach. • Co3{sup +} cation is considered as favorable site for CO adsorption resulted in promote the CO oxidation. • The loading of Pd species resulted in enhancement of activity for CO oxidation. - Abstract: Co{sub 3}O{sub 4} 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), N{sub 2}-physisorped, X-ray photoelectron spectroscopy (XPS), temperature program reduction of hydrogen (H{sub 2}-TPR), temperature program desorption of oxygen (O{sub 2}-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 H{sub 2}-TPR and XPS results, revealed that the coexisting of Co{sup 3+} and Co{sup 2+} species as well as surface Co{sup 3+}/Co{sup 2+} 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 Co{sub 3}O{sub 4}, which improved the O{sub 2} 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.

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.

Synthesis and characterization of mesoporous Mn-MCM-41 materials

International Nuclear Information System (INIS)

Saladino, Maria Luisa; Kraleva, Elka; Todorova, Silvia; Spinella, Alberto; Nasillo, Giorgio; Caponetti, Eugenio

2011-01-01

Highlights: · Manganese MCM-41 as catalyst. · Influence of pH on the structure of MCM-41. · 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 2 adsorption, 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.

Cumene cracking on modified mesoporous material type MCM-41

African Journals Online (AJOL)

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 ...

Synthesis of MCM-41 nanomaterial from Algerian bentonite ...

African Journals Online (AJOL)

Mesoporous materials of the MCM-41 type were synthesized from Algerian bentonite as an aluminosilicate source without the addition of pure silica and aluminum reagents. The samples were synthesized under hydrothermal condition using cetyltrimithylammonium bromide (CTAB) as surfactant. The influence of initial ...

Zero-valent Fe confined mesoporous silica nanocarriers (Fe(0) @ MCM-41) for targeting experimental orthotopic glioma in rats

Science.gov (United States)

Shevtsov, M. A.; Parr, M. A.; Ryzhov, V. A.; Zemtsova, E. G.; Arbenin, A. Yu; Ponomareva, A. N.; Smirnov, V. M.; Multhoff, G.

2016-01-01

Mesoporous silica nanoparticles (MSNs) impregnated with zero-valent Fe (Fe(0) @ MCM-41) represent an attractive nanocarrier system for drug delivery into tumor cells. The major goal of this work was to assess whether MSNs can penetrate the blood-brain barrier in a glioblastoma rat model. Synthesized MSNs nanomaterials were characterized by energy dispersive X-ray spectroscopy, measurements of X-ray diffraction, scanning electron microscopy and Mössbauer spectroscopy. For the detection of the MSNs by MR and for biodistribution studies MSNs were labeled with zero-valent Fe. Subsequent magnetometry and nonlinear-longitudinal-response-M2 (NLR-M2) measurements confirmed the MR negative contrast enhancement properties of the nanoparticles. After incubation of different tumor (C6 glioma, U87 glioma, K562 erythroleukemia, HeLa cervix carcinoma) and normal cells such as fibroblasts and peripheral blood mononuclear cells (PBMCs) MSNs rapidly get internalized into the cytosol. Intracellular residing MSNs result in an enhanced cytotoxicity as Fe(0) @ MCM-41 promote the reactive oxygen species production. MRI and histological studies indicated an accumulation of intravenously injected Fe(0) @ MCM-41 MSNs in orthotopic C6 glioma model. Biodistribution studies with measurements of second harmonic of magnetization demonstrated an increased and dose-dependent retention of MSNs in tumor tissues. Taken together, this study demonstrates that MSNs can enter the blood-brain barrier and accumulate in tumorous tissues. PMID:27386761

Polyethylenimine-modified curcumin-loaded mesoporus silica nanoparticle (MCM-41) induces cell death in MCF-7 cell line.

Science.gov (United States)

Harini, Lakshminarasimhan; Karthikeyan, Bose; Srivastava, Sweta; Suresh, Srinag Bangalore; Ross, Cecil; Gnanakumar, Georgepeter; Rajagopal, Srinivasan; Sundar, Krishnan; Kathiresan, Thandavarayan

2017-02-01

Breast cancer accounts for the first highest mortality rate in India and second in world. Though current treatment strategies are effectively killing cancer cells, they also end in causing severe side effects and drug resistance. Curcumin is a nutraceutical with multipotent activity but its insolubility in water limits its therapeutic potential as an anti-cancer drug. The hydrophilicity of curcumin could be increased by nanoformulation or changing its functional groups. In this study, curcumin is loaded on mesoporous silica nanoparticle and its anti-cancer activity is elucidated with MCF-7 cell death. Structural characteristics of Mobil Composition of Matter - 41(MCM-41) as determined by high-resolution transmission electron microscopy (HR-TEM) shows that MCM-41 size ranges from 100 to 200 nm diameters with pore size 2-10 nm for drug adsorption. The authors found 80-90% of curcumin is loaded on MCM-41 and curcumin is released efficiently at pH 3.0. The 50 µM curcumin-loaded MCM-41 induced 50% mortality of MCF-7 cells. Altogether, their results suggested that increased curcumin loading and sustained release from MCM-41 effectively decreased cell survival of MCF-7 cells in vitro.

Transformation of levoglucosan over H-MCM-22 zeolite and H-MCM-41 mesoporous molecular sieve catalysts

International Nuclear Information System (INIS)

Kaeldstroem, M.; Kumar, N.; Heikkilae, T.; Tiitta, M.; Salmi, T.; Murzin, D. Yu.

2011-01-01

Catalytic transformation of levoglucosan (1-6-anhdyro-β-D-glucopyranose) was carried out in a fixed bed reactor at 573 K over zeolite and mesoporous material catalysts. Proton forms of MCM-22-30 and MCM-41-20 catalysts were tested in the conversion, changing also the residence time. The yield of the transformation product phases was substantially influenced by the structures, at the same time the formation of the different compounds were dependent on the structures of the acidic zeolite catalysts. Oxygenated species were the main liquid product, consisting mainly of aldehydes and furfurals (glycolaldehyde, formaldehyde, acetaldehyde, furfural, 5-methylfurfural, acetic acid). The formation of the liquid products was higher over MCM-41-20 than over MCM-22-30 for all the oxygenated species except acetic acid, indicating larger formation of non-condensable products over the microporous material. By increasing the residence time the formation of acetic acid increased in transformations over MCM-22, however, such increase also led to generation of more gases with both catalysts. The deactivation due to coking was more severe over the zeolite compared to the mesoporous material. It was, however, possible to successfully regenerate the spent zeolites without changing the structure. -- Highlights: → Transformation of levoglucosan (1-6-anhdyro-β-D-glucopyranose) was done at 573 K. → MCM-22-30 and MCM-41-20 catalysts were tested. → Oxygenated species (glycolaldehyde, formaldehyde, acetaldehyde, furfural, 5-methylfurfural, acetic acid) were the main liquid products. → Acidity had an influence on product distribution and deactivation.

Metal Nanoparticles Supported on Al-MCM-41 via In Situ Aqueous Synthesis

International Nuclear Information System (INIS)

Alonso-Lemus, I.; Aguilar-Elguezabal, A.; Alvarez-Contreras, L.; Verde-Gomez, Y.

2010-01-01

MCM-41 have been used to custom synthesize catalysts in because of the controllable properties, such as pore size, active phase incorporation, crystal size, and morphology, among others. In this paper, a simple and versatile method for the incorporation of platinum, ruthenium, and palladium onto Al-MCM-41 mesoporous silica by direct inclusion of various precursors was studied. M/Al-MCM-41 structure, textural properties, morphology, and elemental composition were analyzed. The results obtained indicate that the Al-MCM-41 mesoporous-ordered structure was not affected by metallic particle incorporation. High-surface areas were obtained (1131 m2/g). Metallic nanoparticles dispersion on Al-MCM-41 was homogeneous for all samples and its particles sizes were between 6?nm to 20 nm. Microscopy results show round shape particles in platinum and palladium samples; however, ruthenium catalysts exhibit a spherical and rod shapes. Electrochemical testing for Pt/Al-MCM-41 showed electrocatalytic activity for H2 oxidation which indicates that these materials can be used as a catalyst in electrochemical devices.

Catalytic co-pyrolysis of cellulose and polypropylene over all-silica mesoporous catalyst MCM-41 and Al-MCM-41.

Science.gov (United States)

Chi, Yongchao; Xue, Junjie; Zhuo, Jiankun; Zhang, Dahu; Liu, Mi; Yao, Qiang

2018-08-15

Fast pyrolysis is one of the most economical and efficient technologies to convert biomass to bio-oil and valuable chemical products. Co-pyrolysis with hydrogen rich materials such as plastics over zeolite catalysts is one of the significant solutions to various problems of bio-oil such as high oxygen content, low heat value and high acid content. This paper studied pyrolysis of cellulose and polypropylene (PP) separately and co-pyrolysis of cellulose and PP over MCM-41 and Al-MCM-41. The pyrolysis over different heating rates (10K/min, 20K/min, 30K/min) was studied by Thermogravimetry Analysis (TGA) and kinetic parameters were obtained by Coats-Redfern method and isoconversion method. TG and DTG data shows that the two catalysts advance the pyrolysis reaction of PP significantly and reduce its peak temperature of DTG curve from 458°C to 341°C. The activation energy of pyrolysis of PP also has a remarkable reduction over the two catalysts. Py-GC/MS method was used to obtain the product distribution of pyrolysis of cellulose and PP separately and co-pyrolysis of cellulose and PP over MCM-41 and Al-MCM-41 at constant temperature of 650°C. Experiment results proved that co-pyrolysis with PP bring significant changes to the product distribution of cellulose. Oxygenated compounds such as furans are decreased, while yields of olefins and aromatics increase greatly. The yield of furans increases with the catalysis of MCM-41 as for the pyrolysis of cellulose and co-pyrolysis, while the yield of olefins and aromatics both experience significant growth over Al-MCM-41, which can be explained by the abundant acid centers in Al-MCM-41. Copyright © 2018 Elsevier B.V. All rights reserved.

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.

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.

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

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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.

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. Copyright © 2016 Elsevier Ltd. All rights reserved.

Microspectroscopic analysis of green fluorescent proteins infiltrated into mesoporous silica nanochannels

NARCIS (Netherlands)

Ma, Yujie; Rajendran, Prayanka; Blum, Christian; Cesa, Yanina; Gartmann, Nando; Brühwiler, Dominik; Subramaniam, Vinod

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

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.

Spectral studies on the interaction of acetylacetone with aluminum-containing MCM-41 mesoporous materials

International Nuclear Information System (INIS)

Zanjanchi, M.A.; Vaziri, M.

2008-01-01

Diffuse reflectance spectroscopy (DRS) was used to study the interaction of acetylacetone (acac) with the mesoporous aluminum-containing MCM-41 materials. A room temperature synthesis method was used for preparation of purely siliceous MCM-41 and for aluminum-containing MCM-41 materials. Samples with Si/Al ratios of 50, 20, 10 and 5 were synthesized. The synthesized mesoporous materials possess highly ordered structure and high surface area as evidenced from X-ray diffraction and nitrogen physisorption measurements, respectively. The treatment of the as-synthesized aluminum-containing MCM-41 samples with acac shows a distinct band at ∼290 nm. This band is assigned to six coordinated aluminum atoms in the structure which is produced by diffusion of acac molecules through surfactant micelles and their interaction with aluminum atoms. The 290-nm band disappears upon several successive washing of the sample with ethanol. The treatment of the calcined aluminum-containing MCM-41 sample with acac produces the same 290-nm band where its intensity increases with the aluminum content of the sample. The intensity of this band is reduced upon successive ethanol washing, but remains nearly constant after three times washing. This irremovable aluminum species can be assigned to framework aluminum. The measured acidity for our aluminum-containing MCM-41 samples correlates linearly with the intensity of 290-nm band for the ethanol treated samples. This supports the idea that the Bronsted acidity in aluminum-modified MCM-41 samples is a function of the amount of tetrahedral framework aluminum in the structure

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

Science.gov (United States)

Villegas, María F; Garcia-Uriostegui, Lorena; Rodríguez, Ofelia; Izquierdo-Barba, Isabel; Salinas, Antonio J; Toriz, Guillermo; Vallet-Regí, María; Delgado, Ezequiel

2017-09-26

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 -NH 3+ /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.

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.

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

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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.

Synthesis and characterization of Co (Ni or Cu)-MCM-41 mesoporous molecular sieves with different amount of metal obtained by using microwave irradiation method

International Nuclear Information System (INIS)

Jiang Tingshun; Zhao Qian; Chen Kangmin; Tang Yajing; Yu Longbao; Yin Hengbo

2008-01-01

Co (Ni or Cu)-MCM-41 mesoporous molecular sieves with different amount of metal were synthesized by using cetyltrimethyl ammonium bromide as a template and by a novel microwave irradiation method. These samples were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and N 2 physical adsorption. The experimental results show that Co (Ni or Cu)-MCM-41 mesoporous molecular sieves were successfully synthesized. When the as-synthesized samples were calcined at 550 deg. C for 10 h, the template was effectively removed. Under microwave irradiation condition, Co-MCM-41 mesoporous molecular sieves have specific surface areas in a range of 745.7-1188.8 m 2 /g and average pore sizes in a range of 2.46-2.75 nm; Ni-MCM-41 mesoporous molecular sieves have specific surface areas in a range of 625.8-1161.3 m 2 /g and average pore sizes of ca. 2.7 nm; Cu-MCM-41 mesoporous molecular sieves have specific surface areas in a range of 601.6-1142.9 m 2 /g and average pore sizes in a range of 2.46-2.76 nm. On the other hand, with increasing the introduced metal amount, the specific surface area and pore volume of the synthesized Co (Ni or Cu)-MCM-41 mesoporous molecular sieves became small, and the mesoporous ordering of the samples became poor. Under the comparable synthesis conditions, the synthesized Co-MCM-41 mesoporous molecular sieve has a bigger specific surface area and a more uniform pore distribution as compared with the synthesized Ni-MCM-41and Cu-MCM-41 mesoporous molecular sieves

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

Intermediate-range order in mesoporous silicas investigated by a high-energy X-ray diffraction technique

International Nuclear Information System (INIS)

Wakihara, Toru; Fan, Wei; Ogura, Masaru; Okubo, Tatsuya; Kohara, Shinji; Sankar, Gopinathan

2008-01-01

We perform a high-energy X-ray diffraction study comparing bulk amorphous silica with MCM-41 and SBA-15 that are representative mesoporous silicas prepared in basic and acidic conditions, respectively. It is revealed that mesoporous silicas, especially SBA-15, have less ordered structures and contain larger fractions of three- and four-membered rings than does bulk amorphous silica. (author)

Utilization of a by-product produced from oxidative desulfurization process over Cs-mesoporous silica catalysts.

Science.gov (United States)

Kim, Hyeonjoo; Jeong, Kwang-Eun; Jeong, Soon-Yong; Park, Young-Kwon; Kim, Do Heui; Jeon, Jong-Ki

2011-02-01

We investigated the use of Cs-mesoporous silica catalysts to upgrade a by-product of oxidative desulfurization (ODS). Cs-mesoporous silica catalysts were characterized through N2 adsorption, XRD, CO2-temperature-programmed desorption, and XRF. Cs-mesoporous silica prepared by the direct incorporation method showed higher catalytic performance than a Cs/MCM-41 catalyst by impregnation method for the catalytic decomposition of sulfone compounds produced from ODS process.

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.

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.

Ordered mesoporous silica-based inorganic nanocomposites

International Nuclear Information System (INIS)

Wang Qingqing; Shantz, Daniel F.

2008-01-01

This article reviews the synthesis and characterization of nanoparticles and nanowires grown in ordered mesoporous silicas (OMS). Summarizing work performed over the last 4 years, this article highlights the material properties of the final nanocomposite in the context of the synthesis methodology employed. While certain metal-OMS systems (e.g. gold in MCM-41) have been extensively studied this article highlights that there is a rich set of chemistries that have yet to be explored. The article concludes with some thoughts on future developments and challenges in this area. - Graphical abstract: HAADF TEM image of gold nanoparticles in amine-functionalized MCM-41 (from Ref. [22])

Synthesis and characterization of V, Mo and Nb incorporated micro-mesoporous MCM-41 materials

Energy Technology Data Exchange (ETDEWEB)

Solmaz, Arzu, E-mail: arzu.solmaz@rshm.gov.tr [Gazi University, Faculty of Engineering, Chemical Engineering Department, 06570 Ankara (Turkey); Balci, Suna, E-mail: sunabalci@gazi.edu.tr [Gazi University, Faculty of Engineering, Chemical Engineering Department, 06570 Ankara (Turkey); Dogu, Timur, E-mail: tdogu@metu.edu.tr [Middle East Technical University, Faculty of Engineering, Chemical Engineering Department, 06531 Ankara (Turkey)

2011-01-01

Highly microporous metal-MCM-41 ordered mesoporous structure catalysts having different metal/Si (V, Mo, Nb) atomic ratios and combinations of metal sources were hydrothermally synthesized. The structural properties estimated using different techniques were found to be in agreement with each other. Metals were successfully incorporated into MCM-41 without deteriorating the ordered hexagonal structure. The metal ions in the synthesis solutions probably settled on the hydrophilic end of the template hence the metal incorporation resulted improvements in the micropore structure. Low loading of metals caused an increase in the surface area and pore volume values of the catalysts. The highest total (1310 m{sup 2} g{sup -1}) and micropore surface area values (1083 m{sup 2} g{sup -1}) were obtained by Nb incorporation. The micro- and mesopore dimensions of MCM-41 increased from 0.5 to 1.1 nm and from 2.5 to 2.8 nm, respectively, with metal incorporation. Low V/Si ratios and presence of Nb in the starting solution enhanced narrow mesopore size distribution. The pore dimension and wall thickness values estimated from nitrogen adsorption and X-ray diffraction methods were consistent with the corresponding values obtained using transmission electron microscopy.

Adsorption of Pb2+ on Thiol-functionalized Mesoporous Silica, SH-MCM-48

Science.gov (United States)

Taba, P.; Mustafa, R. D. P.; Ramang, L. M.; Kasim, A. H.

2018-03-01

Modification of mesoporous silica, MCM-48, by using 3- mercaptopropyltrimethoxysilane has been successfully conducted. MCM-48 and SH-MCM-48 were characterized using XRD and FTIR. SH-MCM-48 was used as an adsorbent of Pb2+ ions from solution. A number of Pb2+ ions adsorbed were studied as the function of time, pH, and concentration. The concentration of the ions after adsorption was determined by an Atomic Absorption Spectrophotometer. The removal of the adsorbed ions from the SH-MCM-48 was also studied using several desorbing agents. The result showed that the optimum time was 20 minutes and optimum pH was 4. The adsorption of Pb(II) ion followed the pseudo-second-order with the rate constant of 0,2632 g•mg-1•min-1. Adsorption of Pb(II) ion fitted the Langmuir isotherm with the adsorption capacity of 0,1088 mmol/g. The best desorbing agent to remove the adsorbed ion from SH-MCM-48 was 0.3 M HCl solution with the desorption percentage of 58.6%.

Synthesis, characterization, and near-infrared luminescent properties of the ternary thulium complex covalently bonded to mesoporous MCM-41

International Nuclear Information System (INIS)

Feng Jing; Song Shuyan; Xing Yan; Zhang Hongjie; Li Zhefeng; Sun Lining; Guo Xianmin; Fan Weiqiang

2009-01-01

The crystal structure of a ternary Tm(DBM) 3 phen complex (DBM=dibenzoylmethane; phen=1, 10-phenanthroline) and the synthesis of hybrid mesoporous material in which the complex covalently bonded to mesoporous MCM-41 are reported. Crystal data: Tm(DBM) 3 phen C 59 H 47 N 2 O 7 Tm, monoclinic, P21/c, a=19.3216(12) A, b=10.6691(7) A, c=23.0165(15) A, α=90 deg., β=91.6330(10) deg., γ=90 deg., V=4742.8(5) A 3 , Z=4. The properties of the Tm(DBM) 3 phen complex and the corresponding hybrid mesoporous material [Tm(DBM) 3 phen-MCM-41] have been studied. The results reveal that the Tm(DBM) 3 phen complex is successfully covalently bonded to MCM-41. Both Tm(DBM) 3 phen complex and Tm(DBM) 3 phen-MCM-41 display typical near-infrared (NIR) luminescence upon excitation at the maximum absorption of the ligands, which contributes to the efficient energy transfer from the ligands to the Tm 3+ ion, an antenna effect. The full width at half maximum (FWHM) centered at 1474 nm in the emission spectrum of Tm(DBM) 3 phen-MCM-41 is 110 nm, which is the potential candidate of broadening amplification band from C band (1530-1560 nm) to S + band (1450-1480 nm) in optical area. - Graphical abstract: The crystal structure of Tm(DBM) 3 phen complex (DBM=dibenzoylmethane; phen=1, 10-phenanthroline). The complex is successfully covalently bonded to MCM-41 (Tm(DBM) 3 phen-MCM-41). After ligand-mediated excitation, the emission spectrum of Tm(DBM) 3 phen-MCM-41 shows the bands 802 and 1474 nm. The FWHM of the 1474-nm band for Tm(DBM) 3 phen-MCM-41 is 110 nm, such a broad spectrum enables a wide gain bandwidth for optical amplification

Controlled drug release on amine functionalized spherical MCM-41

International Nuclear Information System (INIS)

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

2012-01-01

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, N 2 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. - Graphical abstract: Determination of surface amino groups by ninhidrin method. Highlights: ► Spherical MCM-41 modified by different amounts of APTES was studied. ► Ibuprofen (IBU) adsorption and release characteristics was tested. ► The ninhydrin reaction was used for the quantitative determination of amino groups. ► Stoichiometric amount of APTES is enough for totally covering the surface with amino groups. ► Good correlation was found between the amino content and IBU adsorption capacity.

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

Energy Technology Data Exchange (ETDEWEB)

Culita, Daniela C., E-mail: danaculita@yahoo.co.uk [“Ilie Murgulescu” Institute of Physical Chemistry, Splaiul Independentei 202, Bucharest (Romania); Simonescu, Claudia Maria; Patescu, Rodica-Elena [Politehnica University, Faculty of Applied Chemistry and Materials Science, Bucharest (Romania); Dragne, Mioara [S.C. KEMCRISTAL S.R.L., Muncii Str., No. 51, Fundulea, Călăraşi (Romania); Stanica, Nicolae [“Ilie Murgulescu” Institute of Physical Chemistry, Splaiul Independentei 202, Bucharest (Romania); Oprea, Ovidiu [Politehnica University, Faculty of Applied Chemistry and Materials Science, Bucharest (Romania)

2016-06-15

o-Vanillin functionalized mesoporous silica – coated magnetite (Fe{sub 3}O{sub 4}@MCM-41-N-oVan) was synthesized and fully characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, N{sub 2} adsorption–desorption technique and magnetic measurements. The capacity of Fe{sub 3}O{sub 4}@MCM-41-N-oVan to adsorb Pb(II) from aqueous solutions was evaluated in comparison with raw mesoporous silica – coated magnetite (Fe{sub 3}O{sub 4}@MCM-41) and amino – modified mesoporous silica coated magnetite (Fe{sub 3}O{sub 4}@MCM-41-NH{sub 2}). 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 Fe{sub 3}O{sub 4}@MCM-41-N-oVan is a suitable candidate for the separation of Pb(II) from contaminated water. - Graphical abstract: A novel magnetic adsorbent based on o-vanillin functionalized mesoporous silica – coated magnetite was synthesized and fully characterized and its adsorption capacity for Pb(II) ions in aqueous solutions was evaluated. The maximum adsorption capacity for Pb(II) ions was determined to be 155.71 mg g{sup −1}. The adsorption rate was very high at the beginning of the adsorption process, 90% of the total amount of Pb(II) being removed within the first 60 min. Display Omitted.

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

International Nuclear Information System (INIS)

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

2016-01-01

o-Vanillin functionalized mesoporous silica – coated magnetite (Fe 3 O 4 @MCM-41-N-oVan) was synthesized and fully characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, N 2 adsorption–desorption technique and magnetic measurements. The capacity of Fe 3 O 4 @MCM-41-N-oVan to adsorb Pb(II) from aqueous solutions was evaluated in comparison with raw mesoporous silica – coated magnetite (Fe 3 O 4 @MCM-41) and amino – modified mesoporous silica coated magnetite (Fe 3 O 4 @MCM-41-NH 2 ). 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 Fe 3 O 4 @MCM-41-N-oVan is a suitable candidate for the separation of Pb(II) from contaminated water. - Graphical abstract: A novel magnetic adsorbent based on o-vanillin functionalized mesoporous silica – coated magnetite was synthesized and fully characterized and its adsorption capacity for Pb(II) ions in aqueous solutions was evaluated. The maximum adsorption capacity for Pb(II) ions was determined to be 155.71 mg g −1 . The adsorption rate was very high at the beginning of the adsorption process, 90% of the total amount of Pb(II) being removed within the first 60 min. Display Omitted

Solid-state (49/47)Ti NMR of titanium-based MCM-41 hybrid materials.

Science.gov (United States)

Ballesteros, Ruth; Fajardo, Mariano; Sierra, Isabel; Force, Carmen; del Hierro, Isabel

2009-11-03

Titanium solid-state NMR spectroscopy data for a series of organic-inorganic titanium MCM-41 based materials have been collected. These materials have been synthesized by first modifying the mesoporous silica MCM-41 in one step with a mixture of silanes: a triazine propyl triethoxysilane acting as functional linker and methyltrimethoxysilane or hexamethyldisilizane as capped agents to mask the remaining silanol groups. Second, the appropiate titanium precursor Ti(OPr(i))(4), [{Ti(OPr(i))(3)(OMent)}(2)] (OMent = 1R,2S,5R-(-)-menthoxo), Ti(OPr(i))(4), or [Ti(eta(5)-C(5)HMe(4))Cl(3)], has been immobilized by reaction with the modified MCM-41. Finally, after Ti(OPr(i))(4) immobilization onto the organomodified support the reaction with the chiral (+)-diethyl-l-tartrate was accomplished. The materials without functional linker have been also prepared by reaction in one step of the capped agent and the titanium precursor with the mesoporous silica. Relevant correlations of titanium NMR resonance chemical shifts and line widths can be inferred depending on different factors. The immobilization procedure used to prepare titanium-based MCM-41 hybrid materials and the choice of the silylating reagents employed to mask the silanol groups present on the silica surfaces produce significant differences in the Ti NMR spectra. Furthermore, depending on the electronic and sterical influence of the substituents directly attached to the titanium center, chemical shifts and line widths are modified providing novel information about titanium structure.

Partial hydrogenation of alkynes on highly selective nano-structured mesoporous silica MCM-41 composite catalyst

International Nuclear Information System (INIS)

Kojoori, R.K.

2016-01-01

In this research, we have developed a silica MCM-41/Metformin/Pd (II) nano composite catalyst for the selective hydrogenation of alkynes to the corresponding (Z)-alkenes under a mild condition of atmospheric pressure and room temperature. Firstly, functionalized Si-MCM-41 metformin catalyst with the optimum performance was prepared. Then, the synthesized catalyst was elucidated by X-ray powder diffraction, BET surface area, FT-IR spectrophotometer, Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) and applied in partial hydrogenation of different alkynes, with high selectivity and high yield. The products were characterized by 1H-NMR, 13C-NMR, FT-IR, and Mass Spectrometry (MS) that strongly approved the (Z)-double bond configuration of produced alkenes. This prepared catalyst is competitive with the best palladium catalysts known for the selective liquid phase hydrogenation of alkynes and can be easily recovered and regenerated with keeping high activity and selectivity over at least three cycles with a simple regeneration procedure. (author)

Synthesis of Nano-Zinc Oxide Loaded on Mesoporous Silica by Coordination Effect and Its Photocatalytic Degradation Property of Methyl Orange.

Science.gov (United States)

Shen, Zhichuan; Zhou, Hongjun; Chen, Huayao; Xu, Hua; Feng, Chunhua; Zhou, Xinhua

2018-05-09

Salicylaldimine-modified mesoporous silica (Sal-MCM-3 and Sal-MCM-9) was prepared through a co-condensation method with different amounts of added salicylaldimine. With the coordination from the salicylaldimine, zinc ions were impregnated on Sal-MCM-3 and Sal-MCM-9. Then, Zn-Sal-MCM-3 and Zn-Sal-MCM-9 were calcined to obtain nano-zinc oxide loaded on mesoporous silica (ZnO-MCM-3 and ZnO-MCM-9). The material structures were systematically studied by Fourier transform infrared spectroscopy (FTIR), N₂ adsorption/desorption measurements, X-ray powder diffraction (XRD), zeta potential, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet diffused reflectance spectrum (UV-vis DRS), and thermogravimetry (TGA). Methyl orange (MO) was used to investigate the photocatalysis behavior of ZnO-MCM-3 and ZnO-MCM-9. The results confirmed that nano ZnO was loaded in the channels as well as the outside surface of mesoporous silica (MCM-41). The modification of salicylaldimine helped MCM-41 to load more nano ZnO on MCM-41. When the modification amount of salicylaldimine was one-ninth and one-third of the mass of the silicon source, respectively, the load of nano ZnO on ZnO-MCM-9 and ZnO-MCM-3 had atomic concentrations of 1.27 and 2.03, respectively. ZnO loaded on ZnO-MCM-9 had a wurtzite structure, while ZnO loaded on ZnO-MCM-3 was not in the same crystalline group. The blocking effect caused by nano ZnO in the channels reduced the orderliness of MCM-41. The photodegradation of MO can be divided in two processes, which are mainly controlled by the surface areas of ZnO-MCM and the loading amount of nano ZnO, respectively. The pseudo-first-order model was more suitable for the photodegradation process.

Síntese do material mesoporoso MCM-41 usando esponja de água-doce como fonte de sílica

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Orivaldo da Silva Lacerda Júnior

2013-01-01

Full Text Available Fresh water sponge was used as a silica source for the synthesis of MCM-41 via the hydrothermal process. The silica was extracted from the sponge by washing with nitric acid and piranha solution. Synthesis of MCM-41 was performed at 100 °C for 5 days and the procedure was optimized, with modifications made to the leaching temperature of the silica and the synthesis of mesoporous material, which was characterized by XRD, FT-IR, SEM and adsorption of N2. The optimal result was achieved at a temperature of 135 °C for 3 days, showing ordered mesoporous material with a surface area of 1080 m² g-1.

Influence of aluminum addition in the framework of MCM-41 mesoporous molecular sieve synthesized by non-hydrothermal method in an alkali-free system

International Nuclear Information System (INIS)

La-Salvia, Nathália; Lovón-Quintana, Juan José; Lovón, Adriana Siviero Pagani; Valença, Gustavo Paim

2017-01-01

Purely siliceous MCM-41 and Al-containing MCM-41 (Al-MCM-41) mesoporous materials were synthesized by non-hydrothermal method in alkali-free ions medium at room temperature and short reaction times. Under these synthesis conditions, it was also investigated the influence of Al incorporation in the crystal structure of MCM-41. The solids were characterized by ICP-OES, AAS, N 2 adsorption at 77 K, XRD, TEM, NH3 -TPD, 27 Al and 29 Si-MAS-NMR, FT-IR and TGA. The resulting mesoporous materials showed a well-defined hexagonally ordered pore geometry maintaining a uniform and unimodal pore size distribution with high specific surface areas (1000-1400 m 2 g -1 ). The Al +3 ions were introduced successfully in the structure of the purely siliceous MCM-41 expanding the unit cell parameter and forming four-coordinated Al species, and in a less extent, forming six-coordinated Al species. In addition, the surface acidity of the MCM-41 increased with Al loading. Contrary, the presence of Al in the MCM-41 mesoporous structure resulted in a decrease of the crystallinity and specific surface area possibly due to the presence of Al species in highly distorted tetrahedral structures and Al extra-framework or amorphous alumina occluded in the pores. The MCM-41 type mesoporous materials obtained in this work show similar characteristics of those synthesized by conventional hydrothermal methods. (author)

Surface modification to improve the sorption property of U(VI) on mesoporous silica

International Nuclear Information System (INIS)

Lijuan Song; Yulong Wang; Lu Zhu; Bolong Guo; Suwen Chen; Wangsuo Wu

2014-01-01

Polyoxometalates K 7 [α-PW 11 O 39 ]·14H 2 O (PW11) modified mesoporous silica (MCM-48) with cubic structure, was prepared by impregnation and calcination methods. The modified mesoporous silica sorbent (PW11/MCM-48) was studied as a potential adsorbent for U(VI) from aqueous solutions. MCM-48 and PW11/MCM-48 were confirmed by X-ray diffraction and nitrogen physisorption techniques. The results indicate the original keggin structure of PW11 and mesoporous structure of MCM-48 are maintained after supporting PW11 on mesoporous silica MCM-48. The effects of contact time, solid-to-liquid ratio (m/V), solution pH and ionic strength on U(VI) sorption behaviors of the pure and modified mesoporous silicas were also studied. Typical sorption isotherms such as Langmuir and Freundlich isotherms were determined for sorption process. The results suggest that the sorption of U(VI) on MCM-48 or PW11/MCM-48 are strongly dependent on pH values but independent of ionic strength. The sorption capacity of PW11/MCM-48 for U(VI) is about ten times more than that of MCM-48. (author)

Metal-Chelate Immobilization of Lipase onto Polyethylenimine Coated MCM-41 for Apple Flavor Synthesis.

Science.gov (United States)

Sadighi, Armin; Motevalizadeh, Seyed Farshad; Hosseini, Morteza; Ramazani, Ali; Gorgannezhad, Lena; Nadri, Hamid; Deiham, Behnaz; Ganjali, Mohammad Reza; Shafiee, Abbas; Faramarzi, Mohammad Ali; Khoobi, Mehdi

2017-08-01

An enzyme immobilized on a mesoporous silica nanoparticle can serve as a multiple catalyst for the synthesis of industrially useful chemicals. In this work, MCM-41 nanoparticles were coated with polyethylenimine (MCM-41@PEI) and further modified by chelation of divalent metal ions (M = Co 2+ , Cu 2+ , or Pd 2+ ) to produce metal-chelated silica nanoparticles (MCM-41@PEI-M). Thermomyces lanuginosa lipase (TLL) was immobilized onto MCM-41, MCM-41@PEI, and MCM-41@PEI-M by physical adsorption. Maximum immobilization yield and efficiency of 75 ± 3.5 and 65 ± 2.7% were obtained for MCM@PEI-Co, respectively. The highest biocatalytic activity at extremely acidic and basic pH (pH = 3 and 10) values were achieved for MCM-PEI-Co and MCM-PEI-Cu, respectively. Optimum enzymatic activity was observed for MCM-41@PEI-Co at 75 °C, while immobilized lipase on the Co-chelated support retained 70% of its initial activity after 14 days of storage at room temperature. Due to its efficient catalytic performance, MCM-41@PEI-Co was selected for the synthesis of ethyl valerate in the presence of valeric acid and ethanol. The enzymatic esterification yield for immobilized lipase onto MCM-41@PEI-Co was 60 and 53%, respectively, after 24 h of incubation in n-hexane and dimethyl sulfoxide media. Graphical Abstract Divalent metal chelated polyethylenimine coated MCM-41 (MCM-41@PEI-M) was used for immobilization of Thermomyces lanuginosa lipase catalyzing green apple flavor preparation.

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

Science.gov (United States)

Anunziata, Oscar A.; Martínez, Maria L.; Beltramone, Andrea R.

2009-01-01

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.

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

International Nuclear Information System (INIS)

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

2016-01-01

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 m 2 /g, respectively. For the MCM-41 microfibers, pore sizes of 2.7 nm and surface areas 420 m 2 /g was measured. - Graphical abstract: Electrospinning method was used for fabricating of MCM-41 microfibers from TEOS in alkaline media (top) and MCM-41 nanofibers in acidic media (bottom). - Highlights: • Synthesis of MCM-41 nanofibers and microfibers by electrospinning technique. • MCM-41 nanofibers were synthesized in acidic media. • MCM-41 manofibers spun in alkaline media. • Electrospinning was a simple method for preparing of fibers with respect to chemical method.

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

International Nuclear Information System (INIS)

Wang Na; Shao Yawei; Shi Zhaoxin; Zhang Jing; Li Hongwei

2008-01-01

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 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

Coordination and Oxidation States of Iron Incorporated in Mesoporous MCM41

International Nuclear Information System (INIS)

Lazar, K.; Pal-Borbely, G.; Szegedi, A.; Beyer, H. K.

2002-01-01

Mesoporous Fe-MCM41 samples (Si/Fe=25) were synthesized and characterized under evacuation and reducing/oxidizing treatments by in situ FTIR and Moessbauer spectroscopies. Both Fe(II) and Fe(III) located in low coordination states in top layers of pore walls exhibit Lewis acidity and may participate in Fe(III) ↔ Fe(II) processes at low temperatures (570 K). Furthermore, Fe(III) ↔ Fe(II) cycles can be achieved and repeated with participation of the full amount of iron at higher temperatures (670 K). The accompanying formation of oxygen vacancies and restoration of the structure in the reverse process does not result in extended damages; the MCM41 structure retains its stability under the conditions applied.

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.

Controlled drug release on amine functionalized spherical MCM-41

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Szegedi, Agnes, E-mail: szegedi@chemres.hu [Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, 1025 Budapest, Pusztaszeri ut 59-67 (Hungary); Popova, Margarita; Goshev, Ivan [Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Sofia (Bulgaria); Klebert, Szilvia [Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, 1025 Budapest, Pusztaszeri ut 59-67 (Hungary); Mihaly, Judit [Institute of Molecular Pharmacology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, 1025 Budapest, Pusztaszeri ut 59-67 (Hungary)

2012-10-15

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, N{sub 2} 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. - Graphical abstract: Determination of surface amino groups by ninhidrin method. Highlights: Black-Right-Pointing-Pointer Spherical MCM-41 modified by different amounts of APTES was studied. Black-Right-Pointing-Pointer Ibuprofen (IBU) adsorption and release characteristics was tested. Black-Right-Pointing-Pointer The ninhydrin reaction was used for the quantitative determination of amino groups. Black-Right-Pointing-Pointer Stoichiometric amount of APTES is enough for totally covering the surface with amino groups. Black-Right-Pointing-Pointer Good correlation was found between the amino content and IBU adsorption capacity.

Study on thermal, mechanical and adsorption properties of amine-functionalized MCM-41/PMMA and MCM-41/PS nanocomposites prepared by ultrasonic irradiation.

Science.gov (United States)

Mohammadnezhad, Gholamhossein; Abad, Saeed; Soltani, Roozbeh; Dinari, Mohammad

2017-11-01

In this study, two common industrial polymers, poly(methyl methacrylate) (PMMA) and polystyrene (PS), were incorporated into amine-functionalized MCM-41 mesoporous silica as reinforcement agents via an ultrasonic assisted method as a facile, fast, eco-friendly, and versatile synthetic tool. Amino functionalization of MCM-41 were performed by 3-aminopropyl triethoxysilane as a coupling agent and it is denoted as APTS-MCM-41. The obtained nanocomposites (NCs), APTS-MCM-41/PMMA and APTS-MCM-41/PS, were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning and transmission electron microscopies (SEM and TEM), and thermogravimetric analysis (TGA). Their mechanical properties were also probed via stress-strain curves and improved tensile properties were observed in the NCs relative to the neat polymers. Additionally, APTS-MCM-41/PMMA exhibited better mechanical properties than APTS-MCM-41/PS. Sorption studies were carried out on the two NCs and the effect of different process parameters, namely, pH, contact time, and initial Cd(II) concentration investigated in batch mode. Pseudo-second order and intraparticle diffusion models explain the Cd(II) kinetics more effectively for APTS-MCM-41/PMMA and APTS-MCM-41/PS, respectively. The adsorption isotherm data fitted well to Langmuir isotherm for both NCs and the maximum monolayer adsorption capacities were found to be 24.75mg/g and 10.42mg/g for APTS-MCM-41/PMMA and APTS-MCM-41/PS, respectively. The results demonstrate that the NCs show potential for use in adsorption of heavy metal ion such as Cd(II) from aqueous media. Copyright © 2017 Elsevier B.V. All rights reserved.

Influence of aluminum addition in the framework of MCM-41 mesoporous molecular sieve synthesized by non-hydrothermal method in an alkali-free system

Energy Technology Data Exchange (ETDEWEB)

La-Salvia, Nathália; Lovón-Quintana, Juan José; Lovón, Adriana Siviero Pagani; Valença, Gustavo Paim, E-mail: nathalialasalvia@gmail.com [Laboratório para o Estudo de Processos de Adsorção e Catálise - LEPAC, Faculdade de Engenharia Química, Universidade Estadual de Campinas - UNICAMP, Campinas, SP (Brazil)

2017-11-15

Purely siliceous MCM-41 and Al-containing MCM-41 (Al-MCM-41) mesoporous materials were synthesized by non-hydrothermal method in alkali-free ions medium at room temperature and short reaction times. Under these synthesis conditions, it was also investigated the influence of Al incorporation in the crystal structure of MCM-41. The solids were characterized by ICP-OES, AAS, N{sub 2} adsorption at 77 K, XRD, TEM, NH3 -TPD, {sup 27}Al and {sup 29}Si-MAS-NMR, FT-IR and TGA. The resulting mesoporous materials showed a well-defined hexagonally ordered pore geometry maintaining a uniform and unimodal pore size distribution with high specific surface areas (1000-1400 m{sup 2} g{sup -1}). The Al{sup +3} ions were introduced successfully in the structure of the purely siliceous MCM-41 expanding the unit cell parameter and forming four-coordinated Al species, and in a less extent, forming six-coordinated Al species. In addition, the surface acidity of the MCM-41 increased with Al loading. Contrary, the presence of Al in the MCM-41 mesoporous structure resulted in a decrease of the crystallinity and specific surface area possibly due to the presence of Al species in highly distorted tetrahedral structures and Al extra-framework or amorphous alumina occluded in the pores. The MCM-41 type mesoporous materials obtained in this work show similar characteristics of those synthesized by conventional hydrothermal methods. (author)

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

International Nuclear Information System (INIS)

Melendez O, H. I.; Mercado S, A.; Garcia C, L. A.; Castruita, G.; Perera M, Y A.

2013-01-01

In this work, ordered meso porous silica MCM-41 was prepared by hydrothermal synthesis using industrial-grade sodium silicate (Na 2 SiO 3 ) as silica source, hexadecyltrimethyl-ammonium bromide (CTAB) as template agent and ethyl acetate as ph regulator. The influence of CTAB/SiO 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 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)

Enhancement of Catalytic Performance of MCM-41 Synthesized with Rice Husk Silica by Addition of Titanium Dioxide for Photodegradation of Alachlor

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Surachai Artkla

2009-01-01

Full Text Available Photocatalytic degradation of alachlor, a herbicide, in water on both bare TiO2 and TiO2 supported on mesoporous material, marked as TiO2/RH-MCM-41 were studied. The RH-MCM-41 support was synthesized from rice husk silica and other reagents by hydrothermal method. The required amount of titanium precursor (TiO2 P25 Degussa to give 10-60% was mixed with RH-MCM-41 and calcined at 300 °C for 6 h. The catalytic activities of TiO2 and TiO2/RH-MCM-41 for alachlor degradation were performed under UV radiation with wavelength of 300 nm. The ratio of catalyst weight to volume of alachlor solution was 1 g/L and all products were characterized by high performance liquid chromatograph. The reaction equilibrium was established in 30 min. in deionized water without adjusting the solution pH. The TiO2/RH-MCM-41 could adsorb alachlor more than the bare TiO2 (namely, 17% vs. 5% and the photocatalytic activity of alachlor degration on all TiO2/RH-MCM-41s was higher than that on the bare TiO2. By comparison per weight of TiO2, the 10%TiO2/RH-MCM-41 gave the highest alachlor conversion of 100% after 20 min. while 1% bare TiO2 showed conversion of 95%.

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

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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.

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

Science.gov (United States)

Kadhom, Mohammed; Yin, Jun; Deng, Baolin

2016-12-06

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)).

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

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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.

Preparation and use of chemically modified MCM-41 and silica gel as selective adsorbents for Hg(II) ions

International Nuclear Information System (INIS)

Puanngam, Mahitti; Unob, Fuangfa

2008-01-01

Adsorbents for Hg(II) ion extraction were prepared using amorphous silica gel and ordered MCM-41. Grafting with 2-(3-(2-aminoethylthio)propylthio)ethanamine was used to functionalize the silica. The functionalized adsorbents were characterized by nitrogen adsorption, X-ray diffraction, 13 C MAS NMR spectroscopy and thermogravimetric analysis. The adsorption properties of the modified silica gel and MCM-41 were compared using batch method. The effect of pH, stirring time, ionic strength and foreign ions were studied. The extraction of Hg(II) ions occurred rapidly with the modified MCM-41 and the optimal pH range for the extraction by the modified materials was pH 4-7. Foreign ions, especially Cl - had some effect on the extraction efficiency of the modified silica gel and the modified MCM-41. The adsorption behavior of both adsorbents could be described by a Langmuir model at 298 K, and the maximum adsorption capacity of the modified silica gel and MCM-41 at pH 3 was 0.79 and 0.70 mmol g -1 , respectively. The modified MCM-41 showed a larger Langmuir constant than that of the modified silica gel, indicating a better ability for Hg(II) ion adsorption. The results indicate that the structure of the materials affects the adsorption behavior. These materials show a potential for the application as effective and selective adsorbents for Hg(II) removal from water

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

MCM-41 ordered mesoporous molecular sieves synthesis and characterization

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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.

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

International Nuclear Information System (INIS)

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

2011-01-01

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. -- Graphical Abstract: Ibuprofen delivery from the parent and amino-modified spherical MCM-41 materials with 100 nm (small) and 500 nm (large) particle sizes. Display Omitted Highlights: → Spherical type MCM-41 and SBA-15 with different particle sizes were modified by APTES. → Adsorption and release rate of ibuprofen were compared. → High degree of ibuprofen loading, slow release rate for MCM-41, the opposite for SBA-15. → MCM-41 with 100 nm particles was more stable and showed slower release rate

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)

Miniaturized solid-phase extraction of macrolide antibiotics in honey and bovine milk using mesoporous MCM-41 silica as sorbent.

Science.gov (United States)

Du, Li-Jing; Yi, Ling; Ye, Li-Hong; Chen, Yu-Bo; Cao, Jun; Peng, Li-Qing; Shi, Yu-Ting; Wang, Qiu-Yan; Hu, Yu-Han

2018-02-16

A simple and effective method of miniaturized solid-phase extraction (mini-SPE) was developed for the simultaneous purification and enrichment of macrolide antibiotics (MACs) (i.e. azithromycin, clarithromycin, erythromycin, lincomycin and roxithromycin) from honey and skim milk. Mesoporous MCM-41 silica was synthesized and used as sorbent in mini-SPE. Several key parameters affecting the performance of mini-SPE procedure were thoroughly investigated, including sorbent materials, amount of sorbent and elution solvents. Under the optimized condition, satisfactory linearity (r 2  > 0.99), acceptable precision (RSDs, 0.3-7.1%), high sensitivity (limit of detection in the range of 0.01-0.76 μg/kg), and good recoveries (83.21-105.34%) were obtained. With distinct advantages of simplicity, reliability and minimal sample requirement, the proposed mini-SPE procedure coupled with ultrahigh performance liquid chromatography and quadrupole time-of-flight tandem mass spectrometry could become an alternative tool to analyze the residues of MACs in complex food matrixes. Copyright © 2018 Elsevier B.V. All rights reserved.

Room temperature synthesis of Si-MCM-41 using polymeric version of ethyl silicate as a source of silica

International Nuclear Information System (INIS)

Gaydhankar, T.R.; Samuel, V.; Jha, R.K.; Kumar, R.; Joshi, P.N.

2007-01-01

Synthesis of mesoporous MCM-41 materials at room temperature using less expensive polymeric version of ethyl silicate (40 wt% SiO 2 ) as a source of silica was established. The influence of crucial synthesis parameters such as molar ratios of H 2 O/NH 4 OH, NH 4 OH/SiO 2 and CTMABr/SiO 2 in gel on the quality of the phase formed was investigated. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and low temperature N 2 adsorption-desorption isotherms have been employed to characterize the products. The magnitude of orderness, textural properties and thermal stability of the Si-MCM-41 samples prepared under identical judiciously pre-controlled synthesis conditions using ethyl silicate and conventional tetraethyl orthosilicate (TEOS) were assessed. Even though, ethyl silicate has proved to be suitable source for the preparation of MCM-41 at room temperature, there exists an optimum value of H 2 O/NH 4 OH for different NH 4 OH/SiO 2 molar ratios in the gel. Changes in the morphology were observed when NH 4 OH/SiO 2 , H 2 O/NH 4 OH molar ratios in the gels were changed

Cu(II) recognition materials: Fluorophores grafted on mesoporous silica supports

International Nuclear Information System (INIS)

Kledzik, Krzysztof; Orlowska, Maja; Patralska, Dorota; Gwiazda, Marcin; Jezierska, Julia; Pikus, Stanislaw; Ostaszewski, Ryszard; Klonkowski, Andrzej M.

2007-01-01

There were designed and synthesized naphthalene and pyrene derivatives consisting of fluorophore group and of receptor fragment with donor N and O atoms. These fluorosensors were covalently attached by grafting carboxyl group to surfaces of silica xerogel or mesoporous silicas (MCM-41 and MCM-48) functionalized either with 3-aminopropyl or 3-glycidoxypropyl groups. The pyrene derivatives 2 and 3 covalently grafted on MCM-48 silica functionalized with 3-aminopropyl groups are potential recognition elements of a fluorescence chemical sensor. Fluorescence emission of the prepared recognition materials is quenched specifically owing to photoinduced electron transfer (PET) effect after coordination reactions with Cu(II) ions. Moreover, both the materials exhibit selectivity for Cu(II) ions in aqueous solutions in presence of such metal ions as: alkali, alkaline earth and transition. During UV irradiation the studied recognition elements undergo slowly photochemical degradation

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

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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.

Mesoporous MCM-41 embeded with Ru(II)-based chemosensor: Preparation, characterization, and emission variation towards pH

International Nuclear Information System (INIS)

Jingxia, Wang

2014-01-01

In this article, a pH sensing mesoporous MCM-41 material containing covalently bonded Ru(II) complex in the silicate network was prepared and named as Ru–MCM-41. The emission signal shows a tendency to decrease upon increasing pH values. The luminescent pH sensor can be explained by the protonation and deprotonation of the PIP ligand (PIP=2-phenyl-1H-imidazo[4,5-f][1,10]phenanthroline) and the fact that the mesoporousity of the MCM-41 matrix favors the –OH that diffused to the complex, resulting in quick emission quenching. It also shows a slight sensitivity towards dissolved molecular oxygen and varying temperatures, which, however, may not be too troublesome for actual applications. The sensing mechanism is also investigated. - Highlights: • An Ru complex was covalently grafted in mesoporous silicate network. • The emission signal decreased with increasing pH values. • The protonation and deprotonation of the ligand caused emission variation. • The emission was insensitive towards oxygen and temperature

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

2017-07-01

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.

Evaluation of the influence of sulfur-based functional groups on the embedding of silver nanoparticles into the pores of MCM-41

International Nuclear Information System (INIS)

Oliveira, Roselaine da S.; Camilo, Fernanda F.; Bizeto, Marcos A.

2016-01-01

The incorporation of noble metals in the pores of mesoporous silicas might produce materials with interesting catalytic and sensing capabilities, but the proper control of pore filling and the avoidance of nanoparticles migration to outside the pores are processes not yet completely understood. In this work, we evaluated the role of –SH and –SO_3H groups post-grafted into MCM-41 on the production of silver nanoparticles by using 1-butanol as reducing agent. Thiol groups were the most efficient on promoting the formation of nanoparticles within the pores. Conversely, sulfonic groups establish electrostatic interactions with silver cations that preclude the formation of nanoparticle in yields comparable to thiol groups. MCM-41 without functional groups did not have good affinity to silver and the nanoparticles are produced outside the pores. This study showed the importance on selecting an adequate surface functional group in order to obtain silver nanoparticles filling the pores of MCM-41. - Graphical abstract: Silver nanoparticles formation inside the pores of sulfur-groups functionalized mesoporous silica. - Highlights: • Silver nanoparticles formation inside the pores of mesoporous silica. • n-butanol as reducing agent of impregnated silver cations. • Tuning the silica surface properties by grafting sulfur-based functional groups. • Influence on the loading and distribution of the nanoparticles through the pores.

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

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.

SiC-dopped MCM-41 materials with enhanced thermal and hydrothermal stabilities

International Nuclear Information System (INIS)

Wang, Yingyong; Jin, Guoqiang; Tong, Xili; Guo, Xiangyun

2011-01-01

Graphical abstract: Novel SiC-dopped MCM-41 materials were synthesized by adding silicon carbide suspension in the molecular sieve precursor solvent followed by in situ hydrothermal synthesis. The dopped materials have a wormhole-like mesoporous structure and exhibit enhanced thermal and hydrothermal stabilities. Highlights: → SiC-dopped MCM-41 was synthesized by in situ hydrothermal synthesis of molecular sieve precursor combined with SiC. → The dopped MCM-41 materials show a wormhole-like mesoporous structure. → The thermal stability of the dopped materials have an increment of almost 100 o C compared with the pure MCM-41. → The hydrothermal stability of the dopped materials is also better than that of the pure MCM-41. -- Abstract: SiC-dopped MCM-41 mesoporous materials were synthesized by the in situ hydrothermal synthesis, in which a small amount of SiC was added in the precursor solvent of molecular sieve before the hydrothermal treatment. The materials were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, N 2 physical adsorption and thermogravimetric analysis, respectively. The results show that the thermal and hydrothermal stabilities of MCM-41 materials can be improved obviously by incorporating a small amount of SiC. The structure collapse temperature of SiC-dopped MCM-41 materials is 100 o C higher than that of pure MCM-41 according to the differential scanning calorimetry analysis. Hydrothermal treatment experiments also show that the pure MCM-41 will losses it's ordered mesoporous structure in boiling water for 24 h while the SiC-dopped MCM-41 materials still keep partial porous structure.

Vanadium-substituted heteropolyacids immobilized on amine- functionalized mesoporous MCM-41: A recyclable catalyst for selective oxidation of alcohols with H2O2

International Nuclear Information System (INIS)

Dong, Xinbo; Wang, Danjun; Li, Kebin; Zhen, Yanzhong; Hu, Huaiming; Xue, Ganglin

2014-01-01

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 2 O 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 2 ) are prepared and characterized by FT-IR, XRD, N 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 2 O 2 as oxidant in toluene. The catalytic activities of different number of vanadium-substituted phosphotungstic acid are investigated, and among the catalysts, H 5 [PV 2 W 10 O 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 2 O 2

MCM-41 mesoporous silica nanoparticles functionalized with aptamer and radiolabelled with 90Y and 159Gd as a potential therapeutic agent against colorectal cancer

International Nuclear Information System (INIS)

Ferreira, Carolina de Aguiar

2014-01-01

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 +3 and Gd +3 ion was determined in vitro using different ratios (1:1, 1:3, 1:5 v/v) of YCL 3 and Gd 2 O 3 and silica nanoparticles dispersed in saline, pH 7.4. The non-incorporated Y +3 and Gd +3 ions were removed by ultracentrifugation procedure and the concentration of ions in the supernatant was determined by ICP-AES. Cell viability was assessed by colorimetric MTT

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

Quaternary ammonium-functionalized MCM-48 mesoporous silica as a sorbent for the dispersive solid-phase extraction of endocrine disrupting compounds in water.

Science.gov (United States)

Zhang, Shijuan; Lu, Fengli; Ma, Xiaoyun; Yue, Mingbo; Li, Yanxin; Liu, Jiammin; You, Jinmao

2018-07-06

MCM-48 mesoporous silica was functionalized with dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride, a quaternary ammonium salt with a long hydrophobic chain, to prepare a new sorbent for the dispersive solid-phase extraction (DSPE) of seven endocrine disrupting compounds (EDCs) including 4-hexylphenol, 4-octylphenol, 4-nonylphenol, bisphenol A, estrone, 17β-estradiol and estriol in water. A series of differently functionalized MCM-48 materials were also synthesized, and they served as reference materials to study the mechanism. The developed DSPE method was combined with HPLC with fluorescence detection to evaluate the adsorption performance. The results indicated that the quaternary ammonium-functionalized MCM-48 mesoporous silica can be used as ideal sorbent for EDCs in water with recoveries of higher than 95% due to the electrostatic interactions and hydrophobic effect. Hydrogen bonding and π-π interactions in other synthesized materials could lead to about 25-30% increase in recoveries, but the results for polyhydroxy compounds were still not satisfying. The quaternary ammonium-functionalized MCM-48 mesoporous silica was successfully applied to the DSPE of EDCs in real water samples. The optimum extraction conditions were sorbent amount, 15 mg; desorption time; 5 min; elution volume, 0.8 mL; sample pH 3.0; and salt addition, 5 g/L. The limits of detection were in the range of 1.2-2.6 ng/L, while the limits of quantitation were in the range of 4.3-8.3 ng/L. Copyright © 2018 Elsevier B.V. All rights reserved.

Bimetallic iron and cobalt incorporated MFI/MCM-41 composite and its catalytic properties

International Nuclear Information System (INIS)

Li, Baoshan; Xu, Junqing; Li, Xiao; Liu, Jianjun; Zuo, Shengli; Pan, Zhiyun; Wu, Ziyu

2012-01-01

Graphical abstract: The formation of FeCo-MFI/MCM-41 composite is based on two steps, the first step of synthesizing the MFI-type proto-zeolite unites under hydrothermal conditions. The second step of assembling these zeolite fragment together new silica and heteroatom source on the CTAB surfactant micelle to synthesize the mesoporous product with hexagonal structure. Highlights: ► Bimetallic iron and cobalt incorporated MFI/MCM-41 composite was prepared using templating method. ► FeCo-MFI/MCM-41 composite simultaneously possessed two kinds of meso- and micro-porous structures. ► Iron and cobalt ions incorporated into the silica framework with tetrahedral coordination. -- Abstract: The MFI/MCM-41 composite material with bimetallic Fe and Co incorporation was prepared using templating method via a two-step hydrothermal crystallization procedure. The obtained products were characterized by a series of techniques including powder X-ray diffraction, N 2 sorption, transmission electron microscopy, scanning electron microscope, H 2 temperature programmed reduction, thermal analyses, and X-ray absorption fine structure spectroscopy of the Fe and Co K-edge. The catalytic properties of the products were investigated by residual oil hydrocracking reactions. Characterization results showed that the FeCo-MFI/MCM-41 composite simultaneously possessed two kinds of stable meso- and micro-porous structures. Iron and cobalt ions were incorporated into the silicon framework, which was confirmed by H 2 temperature programmed reduction and X-ray absorption fine structure spectroscopy. This composite presented excellent activities in hydrocracking of residual oil, which was superior to the pure materials of silicate-1/MCM-41.

Synthesis and characterization of mesoporous Si-MCM-41 materials ...

Indian Academy of Sciences (India)

Administrator

The poten- tial use of Al-MCM-41 and 12TPA-MCM-41 as solid acid catalysts has been explored and compared by study- ... such as difficulty in handling, causing an acidic waste water ... been supported onto MCM-41 by process of anchoring.

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}.

The viability of MCM-41 as separator in secondary alkaline cells

Science.gov (United States)

Meskon, S. R.; Othman, R.; Ani, M. H.

2018-01-01

The viability of MCM-41 membrane as a separator material in secondary alkaline cell is investigated. The inorganic membrane was employed in an alkaline nickel-zinc system. MCM-41 mesoporous material consists of arrays of hexagonal nano-pore channels. The membrane was synthesized using sol-gel route from parent solution comprising of quarternary ammonium surfactant, cethyltrimethylammonium bromide C16H33(CH3)3NBr (CTAB), hydrochloric acid (HCl), deionized water (H2O), ethanol (C2H5OH), and tetraethylortosilicate (TEOS). Both the anodic zinc/zinc oxide and cathodic nickel hydroxide electrodeposited film were coated with MCM-41 membrane. The Ni/MCM-41/Zn alkaline cell was then subjected to 100-cycle durability test and the structural stability of MCM-41 separator throughout the progression of the charge-discharge cycles is studied. X-ray diffraction (XRD) analysis on the dismantled cell shows that MCM-41 began to transform to lamellar MCM-50 on the 5th cycle and transformed almost completely on the 25th cycle. The phase transformation of MCM-41 hexagonal structure into gel-like MCM-50 prevents the mesoporous cell separator from diminished in the caustic alkaline surround. This work has hence demonstrated MCM-41 membrane is viable to be employed in secondary alkaline cells.

Optical oxygen sensing materials based on a novel dirhenium(I) complex assembled in mesoporous silica

International Nuclear Information System (INIS)

Liu Yanhong; Li Bin; Cong Yan; Zhang Liming; Fan Di; Shi Linfang

2011-01-01

A new dirhenium(I) complex fac-[{Re(CO) 3 (4,7-dinonadecyl-1,10-phenanthro -line)} 2 (4,4'-bipyridyl)] (trifluoromethanesulfonate) 2 (denoted as D-Re(I) ) is assembled in MCM-41 and SBA-15 type mesoporous silica support. The emission peaks of D-Re(I) in D-Re(I)/MCM-41 and D-Re(I)/SBA-15 are observed at 522 and 517 nm, respectively. Their long excited lifetimes, which are of the order of microseconds, indicate the presence of phosphorescence emission arising from the metal to ligand charge-transfer (MLCT) transition. The luminescence intensities of D-Re(I)/MCM-41 and D-Re(I)/SBA-15 decrease remarkably with increase in the oxygen concentration, meaning that they can be used as optical oxygen sensing materials based on luminescence quenching. The ratios I 0 /I 100 of D-Re(I)/MCM-41 and D-Re(I)/SBA-15 are estimated to be 5.6 and 20.1, respectively. The obtained Stern-Volmer oxygen quenching plots of the mesoporous sensing materials could be fitted well to the two-site Demas model and Lehrer model. - Research highlights: → Dirhenium(I) complex assembled in mesoporous molecular sieves for oxygen sensor design. → Large α-diimine ligand L used to improve oxygen sensing properties. → High sensitivity (I 0 /I 100 ) up to 20.1.

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.

MCM-41 functionalized with YVO{sub 4}:Eu{sup 3+}: a novel drug delivery system

Energy Technology Data Exchange (ETDEWEB)

Yang Piaoping [Key Laboratory of Rare Earth Chemistry and Physics, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Quan Zewei [Key Laboratory of Rare Earth Chemistry and Physics, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Lu Lanlan [Key Laboratory of Rare Earth Chemistry and Physics, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Huang Shanshan [Key Laboratory of Rare Earth Chemistry and Physics, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Lin Jun [Key Laboratory of Rare Earth Chemistry and Physics, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Fu Honggang [School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080 (China)

2007-06-13

Luminescence functionalization of ordered mesoporous MCM-41 silica was realized by depositing a YVO{sub 4}:Eu{sup 3+} phosphor layer on its surface via the Pechini sol-gel process. This material, which combines the mesoporous structure of MCM-41 and the strong red luminescence property of YVO{sub 4}:Eu{sup 3+}, has been studied as a host carrier for drug delivery/release systems. The structure, morphology, texture and optical properties of Materials were well characterized by x-ray diffraction (XRD), Fourier infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), N{sub 2} adsorption and photoluminescence (PL) spectra. The results indicated that the specific surface area and pore volume of MCM-41, which were directly correlated to the drug-loading amount and ibuprofen (IBU) release rate, decreased in sequence after deposition of YVO{sub 4}:Eu{sup 3+} and loading of IBU as expected. The IBU-loaded YVO{sub 4}:Eu{sup 3+}MCM-41 system still showed red luminescence under UV irradiation (365 nm) and a controlled release property for IBU. In addition, the emission intensity of Eu{sup 3+} increases with an increase in the cumulative released amount of IBU, making the extent of drug release easily identified, tracked and monitored by the change of luminescence, which demonstrates its potential application in drug delivery/release systems.

Blue-green photoluminescence in MCM-41 mesoporous nanotubes

CERN Document Server

Shen, J L; Lui, Y L; Cheng, P W; Cheng, C F

2003-01-01

Different photoluminescence (PL) techniques have been used to study the blue-green emission from siliceous MCM-41 nanotubes. It was found that the intensity of the blue-green PL is enhanced by rapid thermal annealing (RTA). This enhancement is explained by the generation of twofold-coordinated Si centres and non-bridging oxygen hole centres, in line with the surface properties of MCM-41. On the basis of the analysis of the PL following RTA, polarized PL, and PL excitation, we suggest that the triplet-to-singlet transition of twofold-coordinated silicon centres is responsible for the blue-green PL in MCM-41 nanotubes. (letter to the editor)

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. Copyright © 2013 Elsevier Inc. All rights reserved.

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.

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

Ce, Ti modified MCM-48 mesoporous photocatalysts: Effect of the synthesis route on support and metal ion properties

Science.gov (United States)

Mureseanu, Mihaela; Filip, Mihaela; Somacescu, Simona; Baran, Adriana; Carja, Gabriela; Parvulescu, Viorica

2018-06-01

New Ti-MCM-48 and CeTi-MCM-48 photocatalysts were obtained by impregnation of the MCM-48 silica support synthesized by a hydrothermal process with aqueous solution of Ti and Ce precursors. The immobilization of metal cations presented a low effect on the porosity, morphology and structure of MCM-48 mesoporous silica support as was evidenced by N2 adsorption-desorption, X-ray diffraction, SEM and TEM electron microscopy. EDAX analysis and X-ray photoelectron microscopy (XPS) indicated that titanium cations were present on the mesoporous silica surface only as Ti4+ species and the effect of ceria on titanium speciation was different, compared to the CeTi-MCM-48 sample, previously obtained by direct synthesis. The photocatalytic properties of mono- and bimetallic catalysts were evaluated in degradation of phenol from water and correlated with the active metallic species concentration, distribution, speciation and their interaction with the support or each other. An advanced oxidation mechanism for phenol degradation by radical species was proposed.

11C-radioisotope study of methanol co-reaction with ethanol over Ni-MCM-41 silica-alumina and Ni-alumina

International Nuclear Information System (INIS)

Sarkadi-Priboczki, E.; Kovacs, Z.; Tsoncheva, T.; Kumar, N.; Murzin, D.Yu.

2009-01-01

Complete text of publication follows. The Ni modifies the properties of acidic alumina and light acidic MCM-41 silica-alumina supports. The radioisotopic method is a suitable tool for distinction of the 11 Cradioisotopic methanol and its co-derivates from derivates of non-radioactive ethanol on these catalysts. Experimental. The Ni/A l 2O 3 (5 wt % Ni) is commercially available while H-MCMN-41 (Si/Al=20) and Ni-ion-exchanged MCM-41 silica-alumina (5 wt % Ni) were prepared and characterized in previous works. Before catalysis the Ni/Al 2 O 3 and Ni-MCM-41 were pre-reduced. The 11 C-methanol was formed by a radiochemical process from 11 C-carbon dioxide produced at cyclotron (T 1/2 = 20.4 min). The mixture of equivalent volume of radioactive methanol and non-radioactive ethanol was introduced into glass tube micro-flow reactor at ambient temperature. After adsorption, the valves were closed and the catalyst was heated up to the required temperatures. The desorption rate of the remaining 11 C-derivatives on catalysts were continuously followed by radiodetectors and the derivatives of methanol with ethanol were analyzed by Radio/FID-gas chromatography (FID is coupled on-line with a radiodetector). The ethanol and its derivates were identified by FID while the 11 C-methanol and its co-derivates (with ethanol) were detected by both of FID and radiodetector. Results The 11 C-dimethyl ether was the common product of the single 11 C-methanol transformation on H-MCM-41, Ni-MCM-41 and Ni- Al 2 O 3 at low temperature (200-280 degC) due to middle strong acid sites. At higher temperature (280-350 degC), the dimethyl ether and hydrocarbons were the dominant products on H-MCM-41 while dimethyl ether selectivity decreased on Ni-alumina and Ni-MCM-41 in favor of methane. The selectivities of methanol to formaldehyde and methane were the highest on Ni-MCM-41. During co-reaction of 11 C-methanol with non-radioactive ethanol, the 11 C-labeled coethers, namely 11 C-methyl ethyl ether

Mesoporous CeTiSiMCM-48 as novel photocatalyst for degradation of organic compounds

International Nuclear Information System (INIS)

Mureseanu, Mihaela; Parvulescu, Viorica; Radu, Teodora; Filip, Mihaela; Carja, Gabriela

2015-01-01

This work presents novel photocatalysts containing Ti and/or Ce embedded in the mesoporous silica framework (TiSiMCM-48, CeSiMCM-48 and CeTiSiMCM-48) that were prepared via a facile sol–gel process in the presence of ionic structure directing agents. The structural properties of the obtained materials were analyzed by X-ray diffraction (XRD), nitrogen adsorption-desorption, scanning and transmission electron microscopy (SEM, TEM), EDAX analysis, X-ray photoelectron microscopy (XPS), ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS) and Fourier transformation infrared spectroscopy (FT-IR). The results indicated that Ce and Ti were highly dispersed or incorporated into the framework of the cubic SiMCM-48, with an enhanced light-trapping effect both in the UV and Vis regions. When applied to the photocatalytic degradation of phenol, the best results were obtained for the bimetallic hybrid. The best activity of CeTiSiMCM-48 photocatalyst was ascribed to improved electron–hole pair separation efficiency and formation of more reactive oxygen species due to the presence of Ce 4+ /Ce 3+ . The mesoporous support increases the dispersability of the photoactive Ti 4+ or Ce 4+ /Ce 3+ species on the catalyst surface and the accessibility of the substrate to the active sites. Furthermore, the catalysts can be easily recovered and reused for four cycles without significant loss of activity. - Highlights: • Novel photocatalysts containing Ti and/or Ce embedded in the mesoporous MCM-48 silica. • Ce 4+ /Ce 3+ improved electron–hole pair separation and reactivity of oxygen species. • The mesoporous support increases the dispersability of the photoactive species. • The photocatalyst was highly active and stable for phenol degradation under UV irradiation. • TiCeSiMCM-48 can be recycled up to four cycles without significant loss of activity

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.

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

Synthesis and characterization of silica mesoporous material produced by hydrothermal continues pH adjusting path way

Directory of Open Access Journals (Sweden)

A. Salemi Golezani

2016-08-01

Full Text Available Mesoporous silica molecular sieves MCM-41 were synthesized under hydrothermal conditions. For this purpose, a solution with a molar coefficient of water, cetyltri-methyl ammonium bromide surfactants as template and sodium silicate as the source of SiO2 are used. Phase formation, morphology and gas absorption properties were investigated by XRD and BET analysis, respectively. The results showed that silica mesoporous material has been successfully synthesized. A favorable special surface and porosity volume together with regular arrangement of nano metric-hexagonal porosities were obtained from this synthesis. Thickness of the wall and average diameter of the pores are 0.8 nm and 4 nm, respectively.

A secondary, coplanar design Ni/MCM-41/Zn microbattery

Science.gov (United States)

Meskon, S. R.; Othman, R.; Ani, M. H.

2018-01-01

A secondary Ni/Zn microbattery (∼200 µm thick) has been developed in a coplanar electrode configuration. The cell is essentially of a circular shape (∼30 mm in diameter) consisting of a fine circular ring (cathode) and a circle (anode) split apart (~800 µm). Unlike the stacking cell architecture, coplanar configuration offers simple design, ease of fabrication and eventually cost saving. The use of MCM-41 mesoporous silica as the membrane separator cum electrolyte reservoir enables the successful implementation of coplanar configuration. The fabrication of Ni/Zn microbattery first begins with electrodeposition of zinc (Zn) and nickel hydroxide (Ni(OH)2) thin films onto patterned FR4 printed circuit board, followed by deposition of zinc oxide (ZnO) slurry onto the zinc active layer, and finally ends by multiple drop-coating procedures of MCM-41 from its precursor solution at ambient temperature. Once a potassium hydroxide (6 M KOH)/MCM-41 electrolyte-separator mixture is incorporated, the cell is sealed with an acrylic sheet and epoxy adhesive. The fabricated microbatteries were capable to sustain around 130 deep charge-discharge cycles. When rated at 0.1 mA, the energy density of the microbattery was around 3.82 Wh l-1 which is suitable for low rate applications and storage for micro energy harvesters such as piezoelectric generators.

Synthesis of Co/MCM-41catalysts and characterization by XRD, EDX, DTA/TG, SEM and TEM

International Nuclear Information System (INIS)

Sousa, B.V.; Rodrigues, M.G.F.

2009-01-01

Full text: In this work, molecular sieve MCM-41 was prepared as well as the Co/MCM-41 catalyst, via humid impregnation with concentration of 5 wt.% and 10 wt.% Co/MCM- 41. The attainment of the mesoporous molecular sieve, Si-MCM-41, was confirmed by the x-ray diffractogram. It was verified that after the calcination all the bromine (Br) was removed indicating that the calcination process removed all surfactant in the mesoporous structure. XRD and EDX analyses indicated that cobalt was found in the form of Co3O2 in the Co/MCM-41 catalysts. The diffraction standards showed that the impregnation and calcination processes caused changes in the structure only for catalyst with 10 wt.% Co/MCM-41. The DTA/TG curves showed that cobalt nitrate was totally decomposed on the MCM-41. From the images of SEM, it was possible to observe that the Co/MCM-41 catalysts were composed by clusters of small crystals. The images obtained from TEM showed clearly the presence of metal cobalt particles in a well dispersed form for catalyst with 5 wt.% Co/MCM41, except for the catalyst with 10 wt.% Co/MCM41. (author)

Mesoporous silica (MCM-41)-Fe2O3 as a novel magnetic nanosensor for determination of trace amounts of amino acids.

Science.gov (United States)

Hasanzadeh, Mohammad; Shadjou, Nasrin; Omidinia, Eskandar

2013-08-01

Magnetic (Fe2O3) mobile crystalline material-41 (MCM-41) was prepared and characterized using transmission electron microscopy (TEM) and nitrogen adsorption-desorption techniques. Due to the large surface area (1213 m(2)g(-1)) and remarkable electrocatalytic properties of MCM-41-Fe2O3, the MCM-41-Fe2O3 modified glassy carbon electrode (MCM-41-Fe2O3/GCE) exhibits potent electrocatalytic activity toward the electro-oxidation of amino acids. MCM-41-Fe2O3/GCE brings new capabilities for electrochemical sensing by combining the advantages of Fe2O3 magnetic nanoparticles and MCM-41 with very large surface area. Cyclic voltammetry, hydrodynamic amperometry and flow injection analysis used to determination of amino acids at higher concentration range. Fast response time, excellent catalytic activity, and ease of preparation are the advantages of the proposed amino acid sensor. Copyright © 2013 Elsevier B.V. All rights reserved.

Synthesis of sulfated titania supported on mesoporous silica using direct impregnation and its application in esterification of acetic acid and n-butanol

International Nuclear Information System (INIS)

Wang Yuhong; Gan Yunting; Whiting, Roger; Lu Guanzhong

2009-01-01

A new method has been developed for the preparation of sulfated titania (S-TiO 2 ) supported on mesoporous silica. The use of direct exchange of metal containing precursors for the surfactants in the as-synthesized MCM-41 substrate produced a product with high sulfur content without serious blockage of the pore structure of MCM-41. The pore sizes and volumes of the resultant S-TiO 2 /MCM-41 composites were found to vary markedly with the loading of TiO 2 . The strong acidic character of the composites obtained was examined by using them as catalysts for the esterification of acetic acid and n-butanol. - Abstract: XRD profiles of the composites of S-TiO 2 /MCM-41 with different TiO 2 contents. The low angle peaks indicate the MCM-41-like structure retained and a TiO 2 phase appeared at high angle region. Display Omitted

Synthesis of mesoporous hollow silica nanospheres using polymeric micelles as template and their application as a drug-delivery carrier.

Science.gov (United States)

Sasidharan, Manickam; Zenibana, Haruna; Nandi, Mahasweta; Bhaumik, Asim; Nakashima, Kenichi

2013-10-07

Mesoporous hollow silica nanospheres with uniform particle sizes of 31-33 nm have been successfully synthesized by cocondensation of tetramethoxysilane (TMOS) and alkyltrimethoxysilanes [RSi(OR)3], where the latter also acts as a porogen. ABC triblock copolymer micelles of poly(styrene-b-2-vinyl pyridine-b-ethylene oxide) (PS-PVP-PEO) with a core-shell-corona architecture have been employed as a soft template at pH 4. The cationic shell block with 2-vinyl pyridine groups facilitates the condensation of silica precursors under the sol-gel reaction conditions. Phenyltrimethoxysilane, octyltriethoxysilane, and octadecyltriethoxysilanes were used as porogens for generating mesopores in the shell matrix of hollow silica and the octadecyl precursor produced the largest mesopore among the different porogens, of dimension ca. 4.1 nm. The mesoporous hollow particles were thoroughly characterized by small-angle X-ray diffraction (SXRD), thermal (TG/DTA) and nitrogen sorption analyses, infra-red (FTIR) and nuclear magnetic resonance ((13)C-CP MAS NMR and (29)Si MAS NMR) spectroscopies, and transmission electron microscopy (TEM). The mesoporous hollow silica nanospheres have been investigated for drug-delivery application by an in vitro method using ibuprofen as a model drug. The hollow silica nanospheres exhibited higher storage capacity than the well-known mesoporous silica MCM-41. Propylamine functionalized hollow particles show a more sustained release pattern than their unfunctionalized counterparts, suggesting a huge potential of hollow silica nanospheres in the controlled delivery of small drug molecules.

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.

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

International Nuclear Information System (INIS)

Silva, M.; Calvete, M.J.F.; Gonçalves, N.P.F.; Burrows, H.D.; Sarakha, M.; Fernandes, A.; Ribeiro, M.F.; Azenha, M.E.; Pereira, M.M.

2012-01-01

Highlights: ► Complete immobilization of zinc(II) phthalocyanines accomplished in Al-MCM-41. ► Efficient photodegradation of model pesticides achieved using 365 nm irradiation. ► Sodium azide experiments showed the involvement of singlet oxygen ( 1 O 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 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 ( 1 O 2 ), produced by excitation of these immobilized photosensitizers, is a key intermediate in the photocatalytic degradation of both pesticides.

Amine-modified ordered mesoporous silica: Effect of pore size on carbon dioxide capture

Energy Technology Data Exchange (ETDEWEB)

V. Zelenak; M. Badanicova; D. Halamova; J. Cejka; A. Zukal; N. Murafa; G. Goerigk [P.J. Safarik University, Kosice (Slovak Republic)

2008-10-15

Three mesoporous silica materials with different pore sizes and pore connectivity were prepared and functionalized with aminopropyl (AP) ligands by post-synthesis treatment. The materials were characterized by small angle X-ray scattering (SAXS), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and nitrogen adsorption/desorption experiments. The carbon dioxide sorption on modified mesoporous molecular sieves was investigated by using of microbalances at 25{sup o}C, and the influence of pore size and pore architecture on CO{sub 2} sorption was discussed. The large pore silica, SBA-15, showed the largest carbon dioxide sorption capacity (1.5 mmol/g), relating to highest amine surface density in this material. On the other hand, three-dimensional accessibility of amine sites inside the pores of SBA-12 silica resulted in a faster response to CO{sub 2} uptake in comparison with MCM-41 and SBA-15 molecular sieves

Selective Catalytic Reduction of NO with NH3 Over V-MCM-41 Catalyst.

Science.gov (United States)

Kwon, Woo Hyun; Park, Sung Hoon; Kim, Ji Man; Park, Su Bin; Jung, Sang-Chul; Kim, Sang Chai; Jeon, Jong-Ki; Park, Young-Kwon

2016-02-01

V-MCM-41, a mesoporous catalyst doped with V2O5, was applied for the first time to the removal of atmospheric NO. The quantity of V2O5 added was 10 wt% and 30 wt%. The characteristics of the synthesized catalysts were examined using XRD, N2 soprtion, and NH3-TPD. With increasing quantity of V2O5 added, specific surface area decreased and pore size increased. When the quantity of V2O5 was 10 wt%, the MCM-41 structure was retained, whereas considerable collapse of mesoporous structure was observed when 30 wt% V2O5 was added. The examination of acid characteristics using NH3-TPD showed that 30 wt% V-MCM-41 had the higher NH3 adsorption ability, implying that it would exhibit high activity for NH3 SCR reaction. In the NO removal experiments, 30 wt% V-MCM-41 showed much higher NO removal efficiency than 10 wt% V-MCM-41, which was attributed to its high NH3 adsorption ability.

Recovery of silica from electronic waste for the synthesis of cubic MCM-48 and its application in preparing ordered mesoporous carbon molecular sieves using a green approach

Energy Technology Data Exchange (ETDEWEB)

Liou, Tzong-Horng, E-mail: thliou@mail.mcut.edu.tw [Ming Chi University of Technology, Department of Chemical Engineering, Taiwan (China)

2012-07-15

The electronics industry is one of the world's fastest growing manufacturing industries. However, e-waste has become a serious pollution problem. This study reports the recovery of e-waste for preparing valuable MCM-48 and ordered mesoporous carbon for the first time. Specifically, this study adopts an alkali-extracted method to obtain sodium silicate precursors from electronic packaging resin ash. The influence of synthesis variables such as gelation pH, neutral/cationic surfactant ratio, hydrothermal treatment temperature, and calcination temperature on the mesophase of MCM-48 materials is investigated. Experimental results confirm that well-ordered cubic MCM-48 materials were synthesized in strongly acidic and strongly basic media. The resulting mesoporous silica had a high surface area of 1,317 m{sup 2}/g, mean pore size of about 3.0 nm, and a high purity of 99.87 wt%. Ordered mesoporous carbon with high surface area (1,715 m{sup 2}/g) and uniform pore size of CMK-1 type was successfully prepared by impregnating MCM-48 template using the resin waste. The carbon structure was sensitive to the sulfuric acid concentration and carbonization temperature. Converting e-waste into MCM-48 materials not only eliminates the disposal problem of e-waste, but also transforms industrial waste into a useful nanomaterial.

MCM-41介孔碳材料的合成及其电化学性能%Synthesis of MCM-41 Mesoporous Carbon Materials and Their Electrochemical Performance

Institute of Scientific and Technical Information of China (English)

宋伟明; 徐立洋; 孙立; 邓启刚; 冯建; 程晓宇

2017-01-01

以十六烷基三甲基溴化铵(CTAB)为模板剂,可溶性淀粉(Starch)为碳源,通过软模板法一步合成了高度有序的介孔碳材料.通过热重分析(TG)、X射线衍射(XRD)、N2吸附-脱附和透射电子显微镜(TEM)对材料的结构进行了表征.结果表明:当m(模板剂CTAB)∶m(可溶性淀粉)=1.0∶1.5,650℃焙烧碳化3h,并用氢氟酸去除二氧化硅后,所得到的MCM-41有序介孔碳材料(OMC-650)的比表面积为985 m2/g,平均孔径为2.5nm,且孔径分布均匀.XRD和FEM分析结果表明,OMC-650具有典型的MCM-41结构特征,有序性良好.以OMC-650作为工作电极,氧化汞为参比电极,铂为辅助电极,用6 mol/L KOH做电解液,测其比电容为150 F/g,且经过1 000次充放电循环后,其比电容仍为138 F/g,为原电容的92％,说明所合成的材料具有良好的电容稳定性.%A highly ordered mesoporous carbon material was synthesized by a soft template method with hexadecyltrimethylammonium bromide (CTAB) as a template and soluble starch (Starch) as a carbon source.The structures of the resultant materials were characterized by thermal gravimetric analysis (TG),X-ray diffraction (XRD),N2 adsorption-desorption isotherms and transmission electron microscopy (TEM).The results showed that MCM-41 ordered mesoporous carbon material (OMC-650) was obtained when the mass ratio of CTAB to Starch was 1.0∶1.5,carbonized for 3 h at 650 ℃,and then removing the silica with hydrofluoric acid.OMC-650 possessed specific surface area of 985 m2/g and average pore diameter of 2.5 nm and exhibited a uniform distribution.XRD and TEM analysis showed that OMC-650 possesses a typical MCM-41 structural feature with high ordered structure.The electrochemical tests were conducted in a three-electrode system in 6 mol/L KOH solution.When OMC-650 was used as a working electrode,mercury oxide electrode was used as a reference electrode,and Pt wire electrode served as an auxiliary electrode.The specific capacitance of

Effect of Mesoporous Silica and Hydroxyapatite Nanoparticles on the Tensile and Dynamic Mechanical Thermal Properties of Polypropylene and Polypropylene Foam

Directory of Open Access Journals (Sweden)

Alireza Albooyeh

2014-12-01

Full Text Available The main purpose of this paper is the experimental study on the tensile and dynamic - mechanical thermal properties of polypropylene (PP and polypropylene foam reinforced with mesoporous silica (MCM-41, hydroxyapatite (HA and the composite of mesoporous silica and hydroxyapatite (MCM41-HA nanoparticles. Nanocomposites and nanocomposite foams containing PP, maleic anhydride grafted polypropylene, different nanoparticles and chemical blowing agent (for foam samples are mixed using the melt-compounding technique in a twin-screw extruder. The results of the tests show that at the same nanoparticles content, all the nanofillers cause better mechanical properties than neat PP and PP foam. Also, due to the porous structure of the foam samples, these samples have the higher damping characteristics and lower tensile properties than the solid samples. Because of higher rigidity and higher strength of HA nanoparticles, the greatest increase in modulus and tensile strength occurs by adding these nanoparticles to neat PP and PP foam. The highest damping factor is obtained by adding MCM-41-HA nanoparticles to PP and PP foam, because of the porous nature of the MCM-41 particles which were reinforced by HA particles. The results of differential scanning calorimetry show that the addition of different nanoparticles does not have any significant effect on crystallinity and melting behavior of PP. Scanning electron microscopy images show that the nanomaterials were fine and uniformly dispersed within the polymer matrix. Furthermore, the addition of different nanoparticles to PP foam causes to increase the cell density, to reduce the cell sizes and to improve the cell sizes distribution. In this respect, the lowest cell sizes and the highest cell density are created by adding HA and MCM41-HA  nanopaticles to PP foams.

Effect of SiO2/Al2O3 Ratio on Micro-Mesopore Formation for Pt/Beta-MCM-41 via NaOH Treatment and the Catalytic Performance in N-heptane Hydro isomerization

Science.gov (United States)

Gao, Li; Shi, Zhiyuan; Liu, Yingming; Zhao, Yuanshou; Liu, Qinghua; Xu, Chengguo; Bai, Peng; Yan, Zifeng

2018-01-01

Micro-mesoporous composite material Beta-MCM-41(BM) were hydrothermally synthesized by treating parent beta with molar SiO2/Al2O3 ratios of 12.5, 20 and 30 as precursors. The influence of SiO2/Al2O3 ratio of zeolite beta on effective micro-mesoporous composite formation was studied by investigating the crystallinity, morphology, chemical composition, acidity and textural property of Beta-MCM-41 through XRD, nitrogen adsorption, SEM, TEM, NH3-TPD, FTIR and Pyridine-FTIR. The catalytic performance was evaluated in terms of n-heptane hydro isomerization. The results demonstrated that Beta-MCM-41 supported Pt catalysts showed higher selectivity to isoheptanes than Pt/Beta. It was attributed to the superiorities of the pore structure and mesoporous accelerated the diffusion of larger molecules of isoheptanes.

Improvement of the Derjaguin-Broekhoff-de Boer theory for capillary condensation/evaporation of nitrogen in mesoporous systems and its implications for pore size analysis of MCM-41 silicas and related materials.

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Kowalczyk, Piotr; Jaroniec, Mietek; Terzyk, Artur P; Kaneko, Katsumi; Do, Duong D

2005-03-01

In this work, we propose an improvement of the classical Derjaguin-Broekhoff-de Boer (DBdB) theory for capillary condensation/evaporation in mesoporous systems. The primary idea of this improvement is to employ the Gibbs-Tolman-Koenig-Buff equation to predict the surface tension changes in mesopores. In addition, the statistical film thickness (so-called t-curve) evaluated accurately on the basis of the adsorption isotherms measured for the MCM-41 materials is used instead of the originally proposed t-curve (to take into account the excess of the chemical potential due to the surface forces). It is shown that the aforementioned modifications of the original DBdB theory have significant implications for the pore size analysis of mesoporous solids. To verify our improvement of the DBdB pore size analysis method (IDBdB), a series of the calcined MCM-41 samples, which are well-defined materials with hexagonally ordered cylindrical mesopores, were used for the evaluation of the pore size distributions. The correlation of the IDBdB method with the empirically calibrated Kruk-Jaroniec-Sayari (KJS) relationship is very good in the range of small mesopores. So, a major advantage of the IDBdB method is its applicability for small mesopores as well as for the mesopore range beyond that established by the KJS calibration, i.e., for mesopore radii greater than approximately 4.5 nm. The comparison of the IDBdB results with experimental data reported by Kruk and Jaroniec for capillary condensation/evaporation as well as with the results from nonlocal density functional theory developed by Neimark et al. clearly justifies our approach. Note that the proposed improvement of the classical DBdB method preserves its original simplicity and simultaneously ensures a significant improvement of the pore size analysis, which is confirmed by the independent estimation of the mean pore size by the powder X-ray diffraction method.

Aluminum Doped MCM-41 Nanoparticles as Platforms for the Dual Encapsulation of a CO-Releasing Molecule and Cisplatin.

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Carmona, Francisco J; Jiménez-Amezcua, Ignacio; Rojas, Sara; Romão, Carlos C; Navarro, Jorge A R; Maldonado, Carmen R; Barea, Elisa

2017-09-05

Mesoporous silica Al-MCM-41 nanoparticles have been used, for the first time, as vehicles for the single and dual encapsulation of the cationic CO-releasing molecule (CORM) [Mn(1,4,7-triazacyclononane)(CO) 3 ] + (ALF472 + ) and the well-known antineoplastic drug, cis-[PtCl 2 (NH 3 ) 2 ] (cisplatin). Thus, two new hybrid materials, namely, ALF472@Al-MCM-41 and ALF472-cisplatin@Al-MCM-41, have been isolated and fully characterized. The results reveal that the presence of CORM molecules enhances cisplatin loading 3-fold, yielding a cargo of 0.45 mmol g -1 of ALF472 + and 0.12 mmol g -1 of the platinum complex for ALF472-cisplatin@Al-MCM-41. It is worth noting that ALF472@Al-MCM-41 shows a good dispersion in phosphate buffered saline solution, while the dual hybrid material slightly aggregates in this simulated physiological medium (hydrodynamic size: 112 ± 23 and 336 ± 50 nm, respectively). In addition, both hybrid materials (ALF472@Al-MCM-41 and ALF472-cisplatin@Al-MCM-41) behave as photoactive CO-releasing materials, delivering 0.25 and 0.11 equiv of CO, respectively, after 24 h and exhibiting a more controlled CO delivery than that of the free CORM. Finally, metal leaching studies have confirmed the good retention capacity of Al-MCM-41 toward the potentially toxic manganese fragments (86% of retention after 72 h) as well as the low release of cisplatin (ca. 7% after 72 h).

Immobilization induced molecular compression of ionic liquid in ordered mesoporous matrix

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Tripathi, Alok Kumar; Singh, Rajendra Kumar

2018-02-01

In this work, ionic liquid (IL) 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide ([EMIM][FSI]) has been immobilized into ordered mesoporous silica MCM-41 by a physical imbibition process. Transmission electron microscopy confirms the filling of mesopores of MCM-41. The effect of IL content in MCM-41 was probed in terms of thermal stability, chemical interactions, and dielectric properties. N2-sorption results indicate the compression of the IL in the nanopores of MCM-41, which contributes to an increase of the melting point probed by differential scanning calorimetry. The quantum chemical calculations confirmed that the ion-ion interaction in ion-pairs of IL were preferred over the hydrogen bonding interaction in the presence of SiO2 molecules, and these interactions probably compress the molecular size in the nanopores of MCM-41. Strong interactions between IL and porous MCM-41 were suggested as the mechanism of this immobilization, which was characterized by FTIR and dielectric spectroscopy.

Synthesis, Characterizations, and Applications of Metal-Ions Incorporated High Quality MCM-41 Catalysts

International Nuclear Information System (INIS)

Lim, Steven S.; Haller, Gary L.

2013-01-01

Various metal ions (transition and base metals) incorporated MCM-41 catalysts can be synthesized using colloidal and soluble silica with non-sodium involved process. Transition metal ion-typically V 5+ , Co 2+ , and Ni 2+ -incorporated MCM-41 catalysts were synthesized by isomorphous substitution of Si ions in the framework. Each incorporated metal ion created a single species in the silica framework, single-site solid catalyst, showing a substantial stability in reduction and catalytic activity. Radius of pore curvature effect was investigated with Co-MCM-41 by temperature programmed reduction (TPR). The size of metallic Co clusters, sub-nanometer, could be controlled by a proper reduction treatment of Co-MCM-41 having different pore size and the initial pH adjustment of the Co-MCM-41 synthesis solution. These small metallic clusters showed a high stability under a harsh reaction condition without serious migration, resulting from a direct anchoring of small metallic clusters to the partially or unreduced metal ions on the surface. After a complete reduction, partial occlusion of the metallic cluster surface by amorphous silica stabilized the particles against aggregations. As a probe reaction of particle size sensitivity, carbon single wall nanotubes (SWNT) were synthesized using Co-MCM-41. A metallic cluster stability test was performed by CO methanation using Co- and Ni-MCM-41. Methanol and methane partial oxidations were carried out with V-MCM-41, and the radius of pore curvature effect on the catalytic activity was investigated

Application of Mn/MCM-41 as an adsorbent to remove methyl blue from aqueous solution.

Science.gov (United States)

Shao, Yimin; Wang, Xi; Kang, Yuan; Shu, Yuehong; Sun, Qiangqiang; Li, Laisheng

2014-09-01

In this study, the application of Mn loaded MCM-41 (Mn/MCM-41) was reported as a novel adsorbent for methyl blue (MB) from aqueous solution. The mesoporous structure of Mn/MCM-41 was confirmed by XRD technique. Surface area, pore size and wall thickness were calculated from BET equation and BJH method using nitrogen sorption technique. FT-IR studies showed that Mn were loaded on the hexagonal mesoporous structures of MCM-41. It is found that the MCM-41 structure retained after loading of Mn but its surface area and pore diameter decreased due to pore blockage. Adsorption of MB from aqueous solution was investigated by Mn/MCM-41 with changing Mn content, adsorbent dosage, initial MB concentration, contact time, pH and the temperature. Under the chosen condition (25°C, 0.02 g adsorbent dosage, 6.32 pH, 50 mg L(-1) MB, 1 wt.% Mn), a high MB adsorption capacity (45.38 mg g(-1)) was achieved by Mn/MCM-41 process at 120 min, 8.6 times higher than MCM-41. The electrostatic interaction was considered to be the main mechanism for the dye adsorption. The experimental data fitted well to Freundlich and Dubinin-Radushkevich isotherms. The adsorption of MB on Mn/MCM-41 followed pseudo-second-order kinetics. Thermodynamic parameters suggested that the adsorption process is endothermic and spontaneous. Copyright © 2014 Elsevier Inc. All rights reserved.

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

Science.gov (United States)

Choi, Hyeonhee; Bae, Jung-Hyun; Kim, Do Heui; Park, Young-Kwon; Jeon, Jong-Ki

2013-04-29

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.

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

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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.

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

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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.

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%.

Modified silica-based heterogeneous catalysts for etherification of glycerol

International Nuclear Information System (INIS)

Gholami, Zahra; Abdullah, Ahmad Zuhairi; Gholami, Fatemeh; Vakili, Mohammadtaghi

2015-01-01

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 1.6 La 0.6 /MCM-41 catalyst resulted in the highest glycerol conversion of 91% and diglycerol yield of 43%

Hydrogen sulfide removal from hot coal gas by various mesoporous silica supported Mn2O3 sorbents

International Nuclear Information System (INIS)

Zhang, Z.F.; Liu, B.S.; Wang, F.; Wang, W.S.; Xia, C.; Zheng, S.; Amin, R.

2014-01-01

Graphical abstract: - Highlights: • Mn 2 O 3 /KIT-1 presented the best desulfurization performance at 600–850 °C. • High sulfur capacity of Mn 2 O 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 2 O 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 2 O 3 sorbents was investigated at 600–850 °C using hot coal gas containing 0.33 vol.% H 2 S. The fresh and used sorbents were characterized by means of N 2 -adsorption, x-ray diffraction (XRD), high resolution transmission microscopy (HRTEM) and H 2 temperature- programmed reduction (H 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 2 O 3 /diatomite, all mesoporous silica supported Mn 2 O 3 sorbents exhibited high breakthrough sulfur capacity and a sharp deactivation rate after the breakthrough point. Compared to Mn 2 O 3 /MCM-41 and Mn 2 O 3 /HMS sorbent, the Mn 2 O 3 /KIT-1 showed better desulfurization performance because of the 3D wormhole-like channel. The high sulfur capacity of the Mn 2 O 3 /KIT-1 sorbent was maintained during the eight consecutive desulfurization-regeneration cycles. The Mn 2 O 3 /KIT-1 still presented high desulfurization activity when hot coal gas contained low steam (<5%)

Drug delivery from hydrophobic-modified mesoporous silicas: Control via modification level and site-selective modification

International Nuclear Information System (INIS)

Tang Qunli; Chen Yuxi; Chen Jianghua; Li Jin; Xu Yao; Wu Dong; Sun Yuhan

2010-01-01

Dimethylsilyl (DMS) modified mesoporous silicas were successfully prepared via co-condensation and post-grafting modification methods. The post-grafting modification was carried out by the reaction of the as-synthesized MCM-41 material (before CTAB removal) with diethoxydimethylsinale (DEDMS). N 2 adsorption-desorption and 29 Si MAS NMR characterization demonstrated that different amount of DMS groups were successfully incorporated into the co-condensation modified samples, and the functional DMS groups were placed selectively on the pore openings and external pore surfaces in the post-grafting modified samples. Subsequently, the controlled drug delivery properties from the resulting DMS-modified mesoporous silicas were investigated in detail. The drug adsorption experiments showed that the adsorption capacities were mainly depended on the content of silanol group (CSG) in the corresponding carriers. The in vitro tests exhibited that the incorporation of DMS groups greatly retarded the ibuprofen release rate. Moreover, the ibuprofen release profiles could be well modulated by varying DMS modification levels and site-selective distribution of functional groups in mesoporous carriers. - The distribution of DMS groups on the pore surfaces of the mesostructures strongly affects the drug release rate. The P-M41-1 and the P-M41-2 possess the close DMS modification levels as the C-M41-10, but the ibuprofen release rates from the P-M41-1 and P-M41-2 are much slower than that from the C-M41-10.

Influence of different structured channels of mesoporous silicate on the controlled ibuprofen delivery

Energy Technology Data Exchange (ETDEWEB)

Gao, Lin [Department of Chemistry and Chemical Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, 100 PingLeYuan, Chaoyang District, Beijing 100124 (China); Sun, Jihong, E-mail: jhsun@bjut.edu.cn [Department of Chemistry and Chemical Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, 100 PingLeYuan, Chaoyang District, Beijing 100124 (China); Zhang, Li; Wang, Jinpeng; Ren, Bo [Department of Chemistry and Chemical Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, 100 PingLeYuan, Chaoyang District, Beijing 100124 (China)

2012-08-15

The bimodal mesoporous silicas with short random mesoporous channels and MCM-41 with long ordered mesopores were synthesised and modified with 3-(2-aminoethylamino) propyltrimethoxysilane as ibuprofen carriers to study the influence of mesoporous structure on drug delivery property. For further comparing the different mesoporous channels, modified SBA-15 with relative large and long ordered mesopores was also synthesized as drug carriers. The resultant samples were characterized with X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectra, N{sub 2} adsorption-desorption isotherms, thermogravimetric analyses, solid-state {sup 29}Si NMR spectra, elemental analysis, and UV-vis spectra. Meanwhile, the Korsmeyer-Peppas equation f{sub t} = kt{sup n} was employed to analyze the drug release profile and three release mediums including simulated fluid solution, distilled water and simulated gastric fluid were used. The results indicated that the modified BMMs with the bimodal mesopores leaded to the most drug loading amount of 25.0 mg/0.1 g, while the MCM-41 with the long and one-dimensional mesopores had the least loading amount around 20.3 mg/0.1 g. Meanwhile, the easier diffusion behavior of drug molecules in the bimodal mesopore channels of BMMs resulted in relatively faster drug release properties in comparison with MCM-41, while the release time maintained in SBF for about 12 h (release percent was about 90 wt%) and corresponding release constant k obtained from Korsmeyer-Peppas equation was around 4.10. Highlights: Black-Right-Pointing-Pointer BMMs, MCM-41 and SBA-15 with different mesostructure channels were modified with amino groups via post-treatment procedure. Black-Right-Pointing-Pointer Loading and release profiles of ibuprofen in modified BMMs, MCM-41 and SBA-15. Black-Right-Pointing-Pointer BMMs presents more drug loading amount than MCM-41 as well as better controlled release than SBA-15.

Influence of different structured channels of mesoporous silicate on the controlled ibuprofen delivery

International Nuclear Information System (INIS)

Gao, Lin; Sun, Jihong; Zhang, Li; Wang, Jinpeng; Ren, Bo

2012-01-01

The bimodal mesoporous silicas with short random mesoporous channels and MCM-41 with long ordered mesopores were synthesised and modified with 3-(2-aminoethylamino) propyltrimethoxysilane as ibuprofen carriers to study the influence of mesoporous structure on drug delivery property. For further comparing the different mesoporous channels, modified SBA-15 with relative large and long ordered mesopores was also synthesized as drug carriers. The resultant samples were characterized with X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectra, N 2 adsorption–desorption isotherms, thermogravimetric analyses, solid-state 29 Si NMR spectra, elemental analysis, and UV–vis spectra. Meanwhile, the Korsmeyer–Peppas equation f t = kt n was employed to analyze the drug release profile and three release mediums including simulated fluid solution, distilled water and simulated gastric fluid were used. The results indicated that the modified BMMs with the bimodal mesopores leaded to the most drug loading amount of 25.0 mg/0.1 g, while the MCM-41 with the long and one-dimensional mesopores had the least loading amount around 20.3 mg/0.1 g. Meanwhile, the easier diffusion behavior of drug molecules in the bimodal mesopore channels of BMMs resulted in relatively faster drug release properties in comparison with MCM-41, while the release time maintained in SBF for about 12 h (release percent was about 90 wt%) and corresponding release constant k obtained from Korsmeyer–Peppas equation was around 4.10. Highlights: ► BMMs, MCM-41 and SBA-15 with different mesostructure channels were modified with amino groups via post-treatment procedure. ► Loading and release profiles of ibuprofen in modified BMMs, MCM-41 and SBA-15. ► BMMs presents more drug loading amount than MCM-41 as well as better controlled release than SBA-15.

Synthesis, characterization and catalytic activity toward methanol oxidation of electrocatalyst Pt4+-NH2-MCM-41

International Nuclear Information System (INIS)

Zheng Huajun; Chen Zuo; Wang Limin; Ma Chun’an

2012-01-01

Highlights: ► It was first confirmed that the Pt 4+ exhibited a good electro-catalytic property for methanol oxidation. ► The Pt 4+ perfectly distributed on a mesoporous molecular sieve matrix synthesis by a facile method. ► The good performance of catalyst resistance to poisoning because of a homogeneous distribution of Pt 4+ and large specific surface area. - Abstract: Mesoporous material with functional group (Pt 4+ -NH 2 -MCM-41) was prepared by grafting aminopropyl group and adsorbing platinum ions on the surface of the commercial molecular sieve (MCM-41). The characterization carried out by X-ray photoelectron spectroscopy, X-ray diffraction, and N 2 adsorption–desorption measurement pointed out that Pt was adsorbed on the NH 2 -MCM-41 surface as the oxidation state (Pt 4+ ) and the surface area of Pt 4+ -NH 2 -MCM-41 was up to 564 m 2 /g. Transmission electron microscopy and elemental mapping indicated a homogeneous distribution of Pt 4+ throughout all surface of the mesoporous materials. Electro-catalytic properties of methanol oxidation on the Pt 4+ -NH 2 -MCM-41 electrode were investigated with electrochemical methods. The results showed that the Pt 4+ -NH 2 -MCM-41 electrode exhibited catalytic activity in the methanol electro-oxidation with the apparent activation energy being 49.29 kJ/mol, and the control step of methanol electro-oxidation was the mass transfer process. It is first proved that platinum ions had good electro-catalytic property for methanol oxidation and provided a new idea for developing electrode materials in future.

Adsorption-Induced Deformation of Hierarchically Structured Mesoporous Silica-Effect of Pore-Level Anisotropy.

Science.gov (United States)

Balzer, Christian; Waag, Anna M; Gehret, Stefan; Reichenauer, Gudrun; Putz, Florian; Hüsing, Nicola; Paris, Oskar; Bernstein, Noam; Gor, Gennady Y; Neimark, Alexander V

2017-06-06

The goal of this work is to understand adsorption-induced deformation of hierarchically structured porous silica exhibiting well-defined cylindrical mesopores. For this purpose, we performed an in situ dilatometry measurement on a calcined and sintered monolithic silica sample during the adsorption of N 2 at 77 K. To analyze the experimental data, we extended the adsorption stress model to account for the anisotropy of cylindrical mesopores, i.e., we explicitly derived the adsorption stress tensor components in the axial and radial direction of the pore. For quantitative predictions of stresses and strains, we applied the theoretical framework of Derjaguin, Broekhoff, and de Boer for adsorption in mesopores and two mechanical models of silica rods with axially aligned pore channels: an idealized cylindrical tube model, which can be described analytically, and an ordered hexagonal array of cylindrical mesopores, whose mechanical response to adsorption stress was evaluated by 3D finite element calculations. The adsorption-induced strains predicted by both mechanical models are in good quantitative agreement making the cylindrical tube the preferable model for adsorption-induced strains due to its simple analytical nature. The theoretical results are compared with the in situ dilatometry data on a hierarchically structured silica monolith composed by a network of mesoporous struts of MCM-41 type morphology. Analyzing the experimental adsorption and strain data with the proposed theoretical framework, we find the adsorption-induced deformation of the monolithic sample being reasonably described by a superposition of axial and radial strains calculated on the mesopore level. The structural and mechanical parameters obtained from the model are in good agreement with expectations from independent measurements and literature, respectively.

Optical properties of (nanometer MCM-41)-(malachite green) composite materials

International Nuclear Information System (INIS)

Li Xiaodong; Zhai Qingzhou; Zou Mingqiang

2010-01-01

Nanosized materials loaded with organic dyes are of interest with respect to novel optical applications. The optical properties of malachite green (MG) in MCM-41 are considerably influenced by the limited nanoporous channels of nanometer MCM-41. Nanometer MCM-41 was synthesized by tetraethyl orthosilicate (TEOS) as the source of silica and cetyltrimethylammonium bromide (CTMAB) as the template. The liquid-phase grafting method has been employed for incorporation of the malachite green molecules into the channels of nanometer MCM-41. A comparative study has been carried out on the adsorption of the malachite green into modified MCM-41 and unmodified MCM-41. The modified MCM-41 was synthesized using a silylation reagent, trimethychlorosilane (TMSCl), which functionalized the surface of nanometer MCM-41 for proper host-guest interaction. The prepared (nanometer MCM-41)-MG samples have been studied by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, low-temperature nitrogen adsorption-desorption technique at 77 K, Raman spectra and luminescence studies. In the prepared (nanometer MCM-41)-MG composite materials, the frameworks of the host molecular sieve were kept intact and the MG located inside the pores of MCM-41. Compared with the MG, it is found that the prepared composite materials perform a considerable luminescence. The excitation and emission spectra of MG in both modified MCM-41 and unmodified MCM-41 were examined to explore the structural effects on the optical properties of MG. The results of luminescence spectra indicated that the MG molecules existed in monomer form within MCM-41. However, the luminescent intensity of MG incorporated in the modified MCM-41 are higher than that of MG encapsulated in unmodified MCM-41, which may be due to the anchored methyl groups on the channels of the nanometer MCM-41 and the strong host-guest interactions. The steric effect from the pore size of the host materials is significant. Raman

Conductivity of liquid lithium electrolytes with dispersed mesoporous silica particles

International Nuclear Information System (INIS)

Sann, K.; Roggenbuck, J.; Krawczyk, N.; Buschmann, H.; Luerßen, B.; Fröba, M.; Janek, J.

2012-01-01

Highlights: ► The conductivity of disperse lithium electrolytes with mesoporous fillers is studied. ► In contrast to other investigations in literature, no conductivity enhancement could be observed for standard battery electrolytes and typical mesoporous fillers in various combinations. ► Disperse electrolytes can become relevant in terms of battery safety. ► Dispersions of silicas and electrolyte with LiPF 6 as conducting salt are not stable, although the silicas were dried prior to preparation and the electrolyte water content was controlled. Surface modification of the fillers improved the stability. ► The observed conductivity decrease varied considerably for various fillers. - Abstract: The electrical conductivity of disperse electrolytes was systematically measured as a function of temperature (0 °C to 60 °C) and filler content for different types of fillers with a range of pore geometry, pore structure and specific surface area. As fillers mesoporous silicas SBA-15, MCM-41 and KIT-6 with pore ranges between 3 nm and 15 nm were dispersed in commercially available liquid lithium electrolytes. As electrolytes 1 M of lithium hexafluorophosphate (LiPF 6 ) in a mixture of ethylene carbonate (EC) and diethylene carbonate (DEC) at the ratio 3:7 (wt/wt) and the same solvent mixture with 0.96 M lithium bis(trifluoromethanesulfon)imide (LiTFSI) were used. No conductivity enhancement could be observed, but with respect to safety aspects the highly viscous disperse pastes might be useful. The conductivity decrease varied considerably for the different fillers.

Preparation and spectroscopic studies of PbS/nanoMCM-41 nanocomposite

Directory of Open Access Journals (Sweden)

A. Pourahmad

2014-11-01

Full Text Available The present work describes the preparation and characterization of nanosized PbS particles inside the mesopore channels of nanoMCM-41 silicate molecular sieves. The encapsulation of the lead sulfide was carried out at room temperature by ion-exchange method. Diffuse reflectance ultraviolet–visible spectroscopic studies showed a significant shift in the absorption band for the entrapped metal sulfide as compared to corresponding bulk sulfide. Thus, confirming the quantum confinement of the incorporated nanoparticles in nanoMCM-41.

Enhanced photocatalytic hydrogen production from an MCM-41-immobilized photosensitizer-[Fe-Fe] hydrogenase mimic dyad.

Science.gov (United States)

Wang, Wen; Yu, Tianjun; Zeng, Yi; Chen, Jinping; Yang, Guoqiang; Li, Yi

2014-11-01

A covalently linked photosensitizer-catalytic center dyad Ps-Hy, consisting of two bis(2-phenylpyridine)(2,2'-bipyridine)iridium(iii) chromophores (Ps) and a diiron hydrogenase mimic (Hy) was constructed by using click reaction. Ps-Hy was incorporated into K(+)-exchanged molecular sieve MCM-41 to form a composite (Ps-Hy@MCM-41), which has been successfully applied to the photochemical production of hydrogen. The catalytic activity of Ps-Hy@MCM-41 is ∼3-fold higher as compared with that of Ps-Hy in the absence of MCM-41. The incorporation of Ps-Hy into MCM-41 stabilizes the catalyst, and consequently, advances the photocatalysis. The present study provides a potential strategy for improving catalytic efficiency of artificial photosynthesis systems using mesoporous molecular sieves.

Preparation of chitosan/MCM-41-PAA nanocomposites and the adsorption behaviour of Hg(II) ions

Science.gov (United States)

Fu, Yong; Huang, Yue; Hu, Jianshe

2018-03-01

A novel functional hybrid mesoporous composite material (CMP) based on chitosan and MCM-41-PAA was reported and its application as an excellent adsorbent for Hg(II) ions was also investigated. Innovatively, MCM-41-PAA was prepared by using diatomite and polyacrylic acid (PAA) with integrated polymer-silica hybrid frameworks, and then CMP was fabricated by introducing MCM-41-PAA to chitosan using glutaraldehyde as a cross-linking agent. The structure and morphology of CMP were characterized by X-ray diffraction, Fourier transform infrared spectra, thermogravimetric analysis, scanning electron microscopy and Brunauer-Emmett-Teller measurements. The results showed that the CMP possessed multifunctional groups such as -OH, -COOH and -NH2 with large specific surface area. Adsorption behaviour of Hg(II) ions onto CMP was fitted better by the pseudo-second-order kinetic model and the Langmuir model when the initial Hg(II) concentration, pH, adsorption temperature and time were 200 mg l-1, 4, 298 K and 120 min, respectively, as the optimum conditions. The corresponding maximum adsorption capacity could reach 164 mg g-1. According to the thermodynamic parameters determined such as free energy, enthalpy and entropy, the adsorption process of Hg(II) ions was spontaneous endothermic adsorption.

Preparation of chitosan/MCM-41-PAA nanocomposites and the adsorption behaviour of Hg(II) ions

Science.gov (United States)

Fu, Yong; Huang, Yue; Hu, Jianshe

2018-01-01

A novel functional hybrid mesoporous composite material (CMP) based on chitosan and MCM-41-PAA was reported and its application as an excellent adsorbent for Hg(II) ions was also investigated. Innovatively, MCM-41-PAA was prepared by using diatomite and polyacrylic acid (PAA) with integrated polymer–silica hybrid frameworks, and then CMP was fabricated by introducing MCM-41-PAA to chitosan using glutaraldehyde as a cross-linking agent. The structure and morphology of CMP were characterized by X-ray diffraction, Fourier transform infrared spectra, thermogravimetric analysis, scanning electron microscopy and Brunauer–Emmett–Teller measurements. The results showed that the CMP possessed multifunctional groups such as –OH, –COOH and –NH2 with large specific surface area. Adsorption behaviour of Hg(II) ions onto CMP was fitted better by the pseudo-second-order kinetic model and the Langmuir model when the initial Hg(II) concentration, pH, adsorption temperature and time were 200 mg l−1, 4, 298 K and 120 min, respectively, as the optimum conditions. The corresponding maximum adsorption capacity could reach 164 mg g−1. According to the thermodynamic parameters determined such as free energy, enthalpy and entropy, the adsorption process of Hg(II) ions was spontaneous endothermic adsorption. PMID:29657793

Preparation and controlled release of mesoporous MCM-41/propranolol hydrochloride composite drug.

Science.gov (United States)

Zhai, Qing-Zhou

2013-01-01

This article used MCM-41 as a carrier for the assembly of propranolol hydrochloride by the impregnation method. By means of chemical analysis, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy and low-temperature N(2) adsorption-desorption at 77 K, the characterization was made for the prepared materials. The propranolol hydrochloride guest assembly capacity was 316.20 ± 0.31 mg/g (drug/MCM-41). Powder XRD test results indicated that during the process of incorporation, the frameworks of the MCM-41 were not destroyed and the crystalline degrees of the host-guest nanocomposite materials prepared still remained highly ordered. Characterization by SEM and TEM showed that the composite material presented spherical particle and the average particle size of composite material was 186 nm. FT-IR spectra showed that the MCM-41 framework existed well in the (MCM-41)-propranolol hydrochloride composite. Low-temperature nitrogen adsorption-desorption results at 77 K showed that the guest partially occupied the channels of the molecular sieves. Results of the release of the prepared composite drug in simulated body fluid indicated that the drug can release up to 32 h and its maximum released amount was 99.20 ± 0.11%. In the simulated gastric juice release pattern of drug, the maximum time for the drug release was discovered to be 6 h and the maximum cumulative released amount of propranolol hydrochloride was 45.13 ± 0.23%. The drug sustained-release time was 10 h in simulated intestinal fluid and the maximum cumulative released amount was 62.05 ± 0.13%. The prepared MCM-41 is a well-controlled drug delivery carrier.

A potential bioactive wound dressing based on carboxymethyl cellulose/ZnO impregnated MCM-41 nanocomposite hydrogel

Energy Technology Data Exchange (ETDEWEB)

Rakhshaei, Rasul [Research Laboratory of Dendrimers and Nanopolymers, Faculty of Chemistry, University of Tabriz, P.O. Box 51666, Tabriz (Iran, Islamic Republic of); Namazi, Hassan, E-mail: namazi@tabrizu.ac.ir [Research Laboratory of Dendrimers and Nanopolymers, Faculty of Chemistry, University of Tabriz, P.O. Box 51666, Tabriz (Iran, Islamic Republic of); Research Center for Pharmaceutical Nanotechnology, Tabriz University of Medical Science, Tabriz (Iran, Islamic Republic of)

2017-04-01

Lack of antibacterial activity, deficient water vapor and oxygen permeability, and insufficient mechanical properties are disadvantages of existing wound dressings. Hydrogels could absorb wound exudates due to their strong swelling ratio and give a cooling sensation and a wet environment. To overcome these shortcomings, flexible nanocomposite hydrogel films was prepared through combination of zinc oxide impregnated mesoporous silica (ZnO-MCM-41) as a nano drug carrier with carboxymethyl cellulose (CMC) hydrogel. Citric acid was used as cross linker to avoid the cytotoxicity of conventional cross linkers. The prepared nanocomposite hydrogel was characterized using X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Zeta potential and UV–vis spectroscopy. Results of swelling and erosion tests showed CMC/ZnO nanocomposite hydrogel disintegrated during the first hours of the test. Using MCM-41 as a substrate for ZnO nanoparticles solved this problem and the CMC/ZnO-MCM-41 showed a great improvement in tensile strength (12%), swelling (100%), erosion (53%) and gas permeability (500%) properties. Drug delivery and antibacterial properties of the nanocomposite hydrogel films studied using tetracycline (TC) as a broad spectrum antibiotic and showed a sustained TC release. This could efficiently decrease bandage exchange. Cytocompatibility of the nanocomposite hydrogel films has been analyzed in adipose tissue-derived stem cells (ADSCs) and results showed cytocompatibility of CMC/ZnO-MCM-41. Based on these results the prepared CMC nanocomposite hydrogel containing ZnO impregnated MCM-41, could serve as a kind of promising wound dressing with sustained drug delivery properties. - Highlights: • CMC nanocomposite hydrogel incorporated with TC loaded ZnO-MCM-41 nanoparticles have been prepared as active wound dressing. • Citric acid was used as cross linker to avoid conventional toxic crosslinkers. • CMC/ZnO-MCM-41

A potential bioactive wound dressing based on carboxymethyl cellulose/ZnO impregnated MCM-41 nanocomposite hydrogel.

Science.gov (United States)

Rakhshaei, Rasul; Namazi, Hassan

2017-04-01

Lack of antibacterial activity, deficient water vapor and oxygen permeability, and insufficient mechanical properties are disadvantages of existing wound dressings. Hydrogels could absorb wound exudates due to their strong swelling ratio and give a cooling sensation and a wet environment. To overcome these shortcomings, flexible nanocomposite hydrogel films was prepared through combination of zinc oxide impregnated mesoporous silica (ZnO-MCM-41) as a nano drug carrier with carboxymethyl cellulose (CMC) hydrogel. Citric acid was used as cross linker to avoid the cytotoxicity of conventional cross linkers. The prepared nanocomposite hydrogel was characterized using X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Zeta potential and UV-vis spectroscopy. Results of swelling and erosion tests showed CMC/ZnO nanocomposite hydrogel disintegrated during the first hours of the test. Using MCM-41 as a substrate for ZnO nanoparticles solved this problem and the CMC/ZnO-MCM-41 showed a great improvement in tensile strength (12%), swelling (100%), erosion (53%) and gas permeability (500%) properties. Drug delivery and antibacterial properties of the nanocomposite hydrogel films studied using tetracycline (TC) as a broad spectrum antibiotic and showed a sustained TC release. This could efficiently decrease bandage exchange. Cytocompatibility of the nanocomposite hydrogel films has been analyzed in adipose tissue-derived stem cells (ADSCs) and results showed cytocompatibility of CMC/ZnO-MCM-41. Based on these results the prepared CMC nanocomposite hydrogel containing ZnO impregnated MCM-41, could serve as a kind of promising wound dressing with sustained drug delivery properties. Copyright © 2016 Elsevier B.V. All rights reserved.

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

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

International Nuclear Information System (INIS)

Smeulders, Geert; Meynen, Vera; Silvestre-Albero, Ana; Houthoofd, Kristof; Mertens, Myrjam; Silvestre-Albero, Joaquin; Martens, Johan A.; Cool, Pegie

2012-01-01

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: ► The stability (hydrothermal, mechanical and chemical) of PMOs is studied. ► Compared stability of PMOs with classic and other hybrid mesoporous silica materials. ► Immersion calorimetry to study the effect of hydrophobicity. ► 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 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.

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.

CO2 capture on micro/meso-porous composites of (zeolite A)/(MCM-41) with Ca2+ located: Computer simulation and experimental studies

International Nuclear Information System (INIS)

Jianhai Zhou; Huiling Zhao; Jinxia Li; Yujun Zhu; Jun Hu; Honglai Liu; Ying Hu

2013-01-01

Composing of both zeolite and meso-porous structures, micro/meso-porous composites exhibit promising CO 2 capture capabilities. In this work, a full-atomic mimetic 5A-MCM-41 structure with bimodal pores has been constructed, in which the microporous structure of 5A zeolite is constructed and optimized based on zeolite A with Ca and Na cations introduced; whereas the meso-porous MCM-41 structure is produced by caving the cylindrical pores in the obtained 5A zeolite matrix. CO 2 adsorption on 5A-MCM- 41 has been simulated by the grand canonical Monte Carlo (GCMC). The simulation results demonstrated that CO 2 is preferentially adsorbed in micropores, and the CO 2 adsorption capacity and its isosteric heat on 5A-MCM-41 are much larger than those of N 2 . The CO 2 selectivity of 5A-MCM-41 results from the electrostatic interaction of the quadrupole CO 2 molecule with Ca 2+ cations of the zeolite. Furthermore, the hierarchical micro/meso-porous composites are synthesized to verify the simulated predictions. By the hydrothermal reaction using 5A zeolite 'seeds' as the silicon source and hexadecyl trimethylammonium bromide (CTAB) as the meso-porous template, 5A-MCM-41 composites are obtained, the characteristic results show that typical 5A microporous structure is remained and disordered meso-porous networks are produced in the composites.Moreover, the CO 2 adsorption capacity of the 5A-MCM- 41 composites can reach as high as 4.08 mmol/g at 100 kPa and 298 K. These observations have been strongly supported that micro/meso-porous composites with metal ions located would be promising adsorbents for CO 2 separation. (authors)

Mesoporous silica obtained with methyltriethoxysilane as co-precursor in alkaline medium

Science.gov (United States)

Putz, Ana-Maria; Wang, Kunzhou; Len, Adél; Plocek, Jiri; Bezdicka, Petr; Kopitsa, Gennady P.; Khamova, Tamara V.; Ianăşi, Cătălin; Săcărescu, Liviu; Mitróová, Zuzana; Savii, Cecilia; Yan, Minhao; Almásy, László

2017-12-01

Mesoporous silica particles have been synthesized by sol-gel method from tetraethoxysilane (tetraethylorthosilicate, TEOS) and methyltriethoxysilane (MTES), in ethanol and water mixture, at different ratios of the of the silica precursors. Ammonia was used as catalyst at room temperature and hexadecyltrimethylammonium bromide (cetyltrimethylammonium bromide, CTAB) as the structure directing agent. Nitrogen sorption, X-ray diffraction and small-angle neutron scattering gave information on the evolution of the gel structure and pore morphologies in the function of MTES/TEOS molar ratio. Thermogravimetric and differential thermal analysis showed that with addition of MTES the exothermic peak indicating the oxidation of the low molecular weight organic fragments shift to higher temperature. A room-temperature, one-pot synthesis of MCM-41 type materials is presented, in which the variation of the MTES concentration allows to change the hydrophobicity, preserving the specific properties materials, like the ordered pore structure, large specific surface area and high porosity. Specifically, the obtained materials had cylindrical pores, specific surface areas up to 1101 m2/g and total pore volumes up to 0.473 cm3/g. The obtained mesoporous materials are susceptible for further functionalization to improve their selective uptake of guest species in drug delivery applications.

Functionalized silica materials for electrocatalysis

Indian Academy of Sciences (India)

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 ...

Characterization of mesoporous VOx/MCM-41 composite materials obtained via post-synthesis impregnation

International Nuclear Information System (INIS)

Bukallah, Saeed B.; Bumajdad, Ali; Khalil, Kamal M.S.; Zaki, Mohamed I.

2010-01-01

Spherical-particle MCM-41 was synthesized at room temperature, and, then, impregnated with aqueous solutions of NH 4 VO 3 to produce variously loaded VO x /MCM-41 composite materials. Bulk and surface properties of the materials thus produced were characterized by means of X-ray powder diffractometry (XRD), infrared spectroscopy (FTIR), N 2 sorptiometry and X-ray photoelectron spectroscopy (XPS). Results obtained indicated that subsequent calcination at 550 deg. C (for 2 h) of the blank and impregnated MCM-41 particles, results in materials assuming the same bulk structure of MCM-41, and exposing uniformly mesporous, high area surfaces (P w = 2.0-2.3 nm; 974-829 m 2 /g), except for the material obtained at 20 wt%-V 2 O 5 that was shown to suffer a considerable loss on surface area (down to 503 m 2 /g). XPS results implied that the immobilization of the VO x species occurs via interaction with surface OH/H 2 O groups of MCM-41, leading to the formation of vanadate (VO 3 - ) surface species, as well as minor V-O-Si and V 2 O 5 -like species. However, in all cases, the vanadium sites remained pentavalent and exposed on the surface.

Pore ordering in mesoporous matrices induced by different directing agents

Czech Academy of Sciences Publication Activity Database

Putz, A.-M.; Cecilia, S.; Ianasi, C.; Dudás, Z.; Székely, N. K.; Plocek, Jiří; Sfarloaga, P.; Sacarescu, L.; Almásy, L.

2015-01-01

Roč. 22, č. 2 (2015), s. 321-331 ISSN 1380-2224 Institutional support: RVO:61388980 Keywords : Mesoporous silica * MCM-41 * Dodecyl-trimethyl ammonium bromide * Hexadecyl-trimethylammonium bromide Subject RIV: CA - Inorganic Chemistry Impact factor: 1.385, year: 2015

Preparation of resveratrol-loaded nanoporous silica materials with different structures

International Nuclear Information System (INIS)

Popova, Margarita; Szegedi, Agnes; Mavrodinova, Vesselina; Novak Tušar, Natasa; Mihály, Judith; Klébert, Szilvia; Benbassat, Niko; Yoncheva, Krassimira

2014-01-01

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. - 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

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.

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…

Structure and thermal performance of poly(ethylene glycol) alkyl ether (Brij)/porous silica (MCM-41) composites as shape-stabilized phase change materials

Energy Technology Data Exchange (ETDEWEB)

Zhang, Lingjian; Shi, Haifeng, E-mail: haifeng.shi@gmail.com; Li, Weiwei; Han, Xu; Zhang, Xingxiang, E-mail: zhangpolyu@gmail.com

2013-10-20

Graphical abstract: The maximum 50 wt% Brij58 is loaded into the porous MCM-41 networks, and a new peak at 18.8° in XRD patterns confirmed the changes of crystallization behavior of Brij58 against the bulk one. - Highlights: • Poly(ethylene glycol) hexadecyl ether and poly(ethylene glycol) octadecyl ether have the good thermal storage ability. • New peak at 18.8° proved the coexisted confined crystallization and nucleation-induced crystallization. • Poly(ethylene glycol) alkyl ether/MCM-41 PCMs exhibits the good thermal stability. - Abstract: A series of shape-stabilized phase change materials (PCMs), composed of poly(ethylene glycol) hexadecyl ether (Brij58) or poly(ethylene glycol) octadecyl ether (Brij76) and porous silica (MCM-41), were prepared by the physical mixing method. The structure, thermal stability, energy storage ability and crystallization behavior of these composites are deeply investigated and characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), wide-angle X-ray diffraction (WAXD) and thermogravimetric analysis (TGA). Obvious phase transition behavior and energy storage capability are observed for these Brij/MCM-41 composites, and the heat storage efficiency increased with the weight of Brij component. New peak at 18.8° demonstrated that the pore size and the surface adsorption ability of MCM-41 affect the crystallization behavior of Brij molecule. The crystalline structure and energy storage ability of these Brij/MCM-41 composites are discussed based on the crystallization process.

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%)

Structural analysis and characterization of synthesized ordered mesoporous silicate (MCM-41) using small angle X-rays scattering and complementary techniques

Science.gov (United States)

Akinlalu, Ademola V.

were generated with a proprietary software called edens. In this dissertation, the following observations have been revealed resulting from SAXS measurement. 1. As one increases the hydrolysis duration of ethyl acetate, a gradual collapse of the lattice spacing of the mesoporous silcate MCM-41 is observed. We found from SAXS that there is a slight right shift of the spectra toward the higher q-values indicating that we are gradually losing orderliness in the lattice spacing and hexagonal structure of the mesoporous silica. Also, the intensity of the peak of second and third peaks are diminutive when compared to sample with shorter hydrolysis time. 2. A comparison of the SAXS spectra for the different molar concentration sample reveals that the 0:5M samples shows a deteriorating structural characteristics as compared to the 0:25 and 0:75M samples respectively and a clear decrease in the (100) reflection planes. Also noticed is the slight rightward shift in the overall spectrum prole. This observation suggest that further analysis is needed so as to better understand the result. 3. We establish that during MCM-41 synthesis, longer reaction time is needed to produce quality sample with well defined structurally characteristic for its intended application because according to spectrum for the sample with a longer reaction time (aging), a shift towards the lower q-values indicates that a sample with a larger lattice parameter and wall thickness but the intensities of its peak are diminishing when compared to the other of relatively shorter reaction time. Other complementary techniques were used to corroborated the result obtained from SAXS. Nitrogen adsorption-desorption analysis at 77K was used to generate the isotherms while B.E.T method was used in conjunction with the isotherms to obtained the very important surface area information. SEM provide a visual structural morphology of the samples and FTIR gave the fingerprint detail of the bonds and vibration types between

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.

Synthesis and characterization of mesoporous Si–MCM-41 ...

Indian Academy of Sciences (India)

Administrator

Table S1. MCM-41 synthesis strategies—parameters optimized. BET surface area at different temperature (m2/g). SiO2. Template Template H2O Temp. Aging. Parameters. No. source source mole mole. (°C) time (h) pH. 550 °C. 700 °C. 900 °C. Aging time. 1. Na2SiO3. CTABr. 0⋅25. 80. RT. 1. 10⋅5. 640. 490. 370. 2.

Synthesis and catalytic performance of ZSM-5/MCM-41 composite molecular sieve from palygorskite

Science.gov (United States)

Jiang, Jinlong; Wu, Mei; Yang, Yong; Duanmu, Chuansong; Chen, Jing; Gu, Xu

2017-10-01

ZSM-5/MCM-41 composite molecular sieve has been hydrothermally synthesized through a two-step crystallization process using palygorskite (PAL) as silicon and aluminum source. The products were characterized by various means and their catalytic properties for acetalization of cyclohexanone and esterification of acetic acid and n-butanol were also investigated. In the first step ZSM-5 zeolite could be formed from the acid-treated PAL after hydrothermal treatment using tetrapropylammonium bromide as template. XRD patterns, N2 adsorption and desorption data, and TEM images show that the composite obtained in the secondary step had a well-ordered mesoporous MCM-41 phase and a microporous ZSM-5 zeolite phase. Compared with ZSM-5, ZSM-5/MCM-41 composite possessed more total acid amount, weak acid sites and large pore structure due to the formation of MCM-41 and exhibited higher catalytic activity for the acetalization and esterification reaction.

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.

Development of an Amperometric Glucose Biosensor Based on the Immobilization of Glucose Oxidase on the Se-MCM-41 Mesoporous Composite

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Sabriye Yusan

2018-01-01

Full Text Available A new bioenzymatic glucose biosensor for selective and sensitive detection of glucose was developed by the immobilization of glucose oxidase (GOD onto selenium nanoparticle-mesoporous silica composite (MCM-41 matrix and then prepared as a carbon paste electrode (CPE. Cyclic voltammetry was employed to probe the catalytic behavior of the biosensor. A linear calibration plot is obtained over a wide concentration range of glucose from 1 × 10−5 to 2 × 10−3 M. Under optimal conditions, the biosensor exhibits high sensitivity (0.34 µA·mM−1, low detection limit (1 × 10−4 M, high affinity to glucose (Km = 0.02 mM, and also good reproducibility (R.S.D. 2.8%, n=10 and a stability of about ten days when stored dry at +4°C. Besides, the effects of pH value, scan rate, mediator effects on the glucose current, and electroactive interference of the biosensor were also discussed. As a result, the biosensor exhibited an excellent electrocatalytic response to glucose as well as unique stability and reproducibility.

Energy down converting organic fluorophore functionalized mesoporous silica hybrids for monolith-coated light emitting diodes

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Markus Börgardts

2017-04-01

Full Text Available The covalent attachment of organic fluorophores in mesoporous silica matrices for usage as energy down converting phosphors without employing inorganic transition or rare earth metals is reported in this article. Triethoxysilylpropyl-substituted derivatives of the blue emitting perylene, green emitting benzofurazane, and red emitting Nile red were synthesized and applied in the synthesis of mesoporous hybrid materials by postsynthetic grafting to commercially available MCM-41. These individually dye-functionalized hybrid materials are mixed in variable ratios to furnish a powder capable of emitting white light with CIE chromaticity coordinates of x = 0.33, y = 0.33 and an external quantum yield of 4.6% upon irradiation at 410 nm. Furthermore, as a proof of concept two different device setups of commercially available UV light emitting diodes, are coated with silica monoliths containing the three triethoxysilylpropyl-substituted fluorophore derivatives. These coatings are able to convert the emitted UV light into light with correlated color temperatures of very cold white (41100 K, 10700 K as well as a greenish white emission with correlated color temperatures of about 5500 K.

Fast and efficient mesoporous adsorbents for the separation of toxic compounds from aqueous media.

Science.gov (United States)

Anbia, Mansoor; Mohammadi, Nourali; Mohammadi, Kaveh

2010-04-15

The effect of cationic template on the adsorption of chromium (VI), furfural and copperphthalocyanine-3,4',4'',4'''-tetrasulfonic acid tetrasodium salt (CuPc) in MCM-41 and MCM-48 mesoporous materials was investigated in this work. We used cetyltrimethylammonium bromide (CTAB) as the cationic template and sodiummetasilicate (for MCM-41) and tetraethyl-orthosilicon (for MCM-48) as the silica source for the synthesis of mesoporous materials. The properties of synthesized samples were characterized with XRD-low angle, SEM, N(2) adsorption-desorption and TG-DT analysis. The extent of adsorption was investigated as a function of solution pH, shaking speed, contact time, analyte concentration, reaction temperature and supporting electrolyte (sodium chloride) concentration. Langmuir and Freundlich isotherms were used to model the adsorption equilibrium data. The as-synthesized mesoporous samples showed very high adsorption capacity for the analytes and adsorption uptakes were rapid on the adsorbents reaching equilibrium in less than 2 h. The materials without surfactant did not show significant affinity for the analytes. 2009 Elsevier B.V. All rights reserved.

FACTORES QUE AFECTAN LA TEXTURA Y ESTRUCTURA DE Ti(R-MCM-41 FACTORES QUE AFECTAN LA TEXTURA Y ESTRUCTURA DE Ti(R-MCM-41

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J. Ramírez Solís

2012-02-01

Full Text Available 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 aplicación de un disolvente polar (solución de H2SO4 0.05 M en etanol resultó ser más efectivo para remover el surfactante y disminuir la destrucción del material mesoporoso durante la calcinación. Las muestras tratadas con este método presentaron un mayor orden en el arreglo hexagonal de los poros (HREM, DRX y áreas superficiales más grandes. El efecto del aumento del contenido de TiO2 en los sólidos sintetizados se traduce en una disminución significativa de la intensidad del pico característico de MCM-41 (2Q = 2.2-2.5o y de las características texturales (SBET, volumen de poros, lo que indica que durante la síntesis no es posible incorporar más de 10 mol. % de TiO2 al MCM-41.Studied was the effect surfactant removal and titanium content have on the structure and textural properties of Ti-MCM-41 mesoporous materials. The synthesized solids were characterized by N2 adsorption, X-ray fluorescence (FRX, X-ray diffraction (DRX, electronic microscopy of high resolution(HREM, and FT-Raman and UV-vis diffuse reflectance spectroscopy (DRS. Between the two methods of surfactant removal studied, the application of a polar solvent (solution of 0.05 M H2SO4 in ethanol was to be more effective in removing the surfactant and diminishing the destruction of mesoporous material during calcination. The samples treated by this method showed a more ordered hexagonal pore arrangement (HREM, XRD and larger surface area. The effect of an increase in TiO2

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.

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.

Chemical design of pH-sensitive nanovalves on the outer surface of mesoporous silicas for controlled storage and release of aromatic amino acid

International Nuclear Information System (INIS)

Roik, N.V.; Belyakova, L.A.

2014-01-01

Mesoporous silicas with hexagonally arranged pore channels were synthesized in water–ethanol-ammonia solution using cetyltrimethylammonium bromide as template. Directed modification of silica surface with N-[N′-(N′-phenyl)-2-aminophenyl]-3-aminopropyl groups was realized by postsynthetic activation of halogenoalkylsilicas, which have surface uniformly or selectively distributed 3-chloropropyl groups, with 2-aminodiphenylamine in the liquid phase. Chemical composition of silica materials was estimated by IR spectroscopy and chemical analysis of the surface products of reactions. Characteristics of porous structure of MCM-41-type silicas were determined from X-ray and low-temperature nitrogen ad-desorption measurements. Release ability of synthesized silica carriers was established on encapsulation of 4-aminobenzoic acid in pore channels and subsequent delivery at pH=6.86 and pH=1.00. It was found that N-[N′-(N′-phenyl)-2-aminophenyl]-3-aminopropyl groups block pore entrances at neutral pH preventing 4-aminobenzoic acid release. At pH=1.00 repulsion of positively charged surface aromatic amino groups localized near pore orifices provides unhindered liberation of aromatic amino acid from mesoporous channels. - Graphical abstract: Blocking of pores with N-[N′-(N′-phenyl)-2-aminophenyl]-3-aminopropyl groups at pH=6.86 for storage of ABA and opening of pore entrances at pH=1.00 for unhindered ABA liberation. - Highlights: • Modification of MCM-41 with N-[N′-(N′-phenyl)-2-aminophenyl]-3-aminopropyl groups. • Study of release ability of synthesized silica carriers in relation to amino acid. • Controlled blocking and opening of pores by amino groups at pH change were performed. • Retention of amino acid at pH=6.86 and its liberation at pH=1.00 was proved

Mesoporous silica nanoparticles supported copper(II) and nickel(II) Schiff base complexes: Synthesis, characterization, antibacterial activity and enzyme immobilization

Science.gov (United States)

Tahmasbi, Leila; Sedaghat, Tahereh; Motamedi, Hossein; Kooti, Mohammad

2018-02-01

Mesoporous silica nanoparticles (MSNs) were prepared by sol-gel method and functionalized with 3-aminopropyltriethoxysilane. Schiff base grafted mesoporous silica nanoparticle was synthesized by the condensation of 2-hydroxy-3-methoxybenzaldehyde and amine-functionalized MSNs. The latter material was then treated with Cu(II) and Ni(II) salts separately to obtain copper and nickel complexes anchored mesoporous composites. The newly prepared hybrid organic-inorganic nanocomposites have been characterized by several techniques such as FT-IR, LA-XRD, FE-SEM, TEM, EDS, BET and TGA. The results showed all samples have MCM-41 type ordered mesoporous structure and functionalization occurs mainly inside the mesopore channel. The presence of all elements in synthesized nanocomposites and the coordination of Schiff base via imine nitrogen and phenolate oxygen were confirmed. MSNs and all functionalized MSNs have uniform spherical nanoparticles with a mean diameter less than 100 nm. The as-synthesized mesoporous nanocomposites were investigated for antibacterial activity against Gram-positive (B. subtilis and S. aureus) and Gram-negative (E. coli and P. aeruginosa) bacteria, as carrier for gentamicin and also for immobilization of DNase, coagulase and amylase enzymes. MSN-SB-Ni indicated bacteriocidal effect against S.aureus and all compounds were found to be good carrier for gentamicin. Results of enzyme immobilization for DNase and coagulase and α-amylase revealed that supported metal complexes efficiently immobilized enzymes.

Preparation, characterization and optical properties of Lanthanum-(nanometer MCM-41) composite materials

International Nuclear Information System (INIS)

Zhai, Q. Z.; Wang, P.

2008-01-01

Nanometer MCM-41 molecular sieve was prepared under a base condition by using cetyltrimethylammonium bromide as template and tetraethyl orthosilicate as silica source by means of hydrothermal method. Lanthanum(III) was incorporated into the nanometer MCM-41 by a liquid phase grafting method. The prepared nano composite materials were characterized by means of powder X-ray diffraction, spectrophotometric analysis, Fourier transform infrared spectroscopy, low temperature nitrogen adsorption-desorption technique, solid diffuse reflectance absorption spectra and luminescence. The powder X-ray diffraction studies show that the nanometer MCM-41 molecular sieve is successfully prepared. The highly ordered meso porous two-dimensional hexagonal channel structure and framework of the support MCM-41 is retained intact in the prepared composite material La-(nanometer MCM-41). The spectrophotometric analysis indicates that lanthanum exists in the prepared nano composite materials. The Fourier transform infrared spectra indicate that the framework of the MCM-41 molecular sieve still remains in the prepared nano composite materials and some framework vibration peaks show blue shifts relative to those of the MCM-41 molecular sieve. The low temperature nitrogen adsorption-desorption indicates that the guest locales in the channel of the molecular sieve. Compared with bulk lanthanum oxide, the guest in the channel of the molecular sieve has smaller particle size and shows a significant blue shift of optical absorption band in solid diffuse reflectance absorption spectra. The observed blue shift in the solid state diffuse reflectance absorption spectra of the lanthanum-(nanometer MCM-41) sample show the obvious stereoscopic confinement effect of the channel of the host on the guest, which further indicates the successful encapsulation of the guest in the host. The La-(nanometer MCM-41) sample shows luminescence

Mesoporous (organo) silica decorated with magnetic nanoparticles as a reusable nanoadsorbent for arsenic removal from water samples.

Science.gov (United States)

Hasanzadeh, Mohammad; Farajbakhsh, Farzad; Shadjou, Nasrin; Jouyban, Abolghasem

2015-01-01

Over the last decade, numerous removal methods using solid-supported magnetic nanocomposites have been employed in order to remove arsenic from aqueous solution. In this report, removal of arsenic from aqueous solution by an organo silica, namely, magnetic mobile crystalline material-41 (MCM-41) functionalized by chlorosulphonic acid (MMCM-41-SO3H), was investigated using atomic absorption spectroscopy. The synthesized magnetic mesoporous materials have satisfactory As (V) adsorption capacity. Linearity for arsenic was observed in the concentration range of 5-100 ppb. In addition, the coefficient of determination (R2) was more than 0.999 and the limit of detection (LOD) was 0.061 ppb. Considering these results, MMCM-41-SO3H has a great potential for the removal of As (V) contaminants and potentially for the application in large-scale wastewater treatment plants.

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

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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.

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

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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.

Ordered nanoporous silica as carriers for improved delivery of water insoluble drugs: a comparative study between three dimensional and two dimensional macroporous silica

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Wang Y

2013-10-01

Full Text Available Ying Wang, Qinfu Zhao, Yanchen Hu, Lizhang Sun, Ling Bai, Tongying Jiang, Siling WangDepartment of Pharmaceutics, Shenyang Pharmaceutical University, Liaoning Province, People’s Republic of ChinaAbstract: The goal of the present study was to compare the drug release properties and stability of the nanoporous silica with different pore architectures as a matrix for improved delivery of poorly soluble drugs. For this purpose, three dimensional ordered macroporous (3DOM silica with 3D continuous and interconnected macropores of different sizes (200 nm and 500 nm and classic mesoporous silica (ie, Mobil Composition of Matter [MCM]-41 and Santa Barbara Amorphous [SBA]-15 with well-ordered two dimensional (2D cylindrical mesopores were successfully fabricated and then loaded with the model drug indomethacin (IMC via the solvent deposition method. Scanning electron microscopy (SEM, N2 adsorption, differential scanning calorimetry (DSC, and X-ray diffraction (XRD were applied to systematically characterize all IMC-loaded nanoporous silica formulations, evidencing the successful inclusion of IMC into nanopores, the reduced crystallinity, and finally accelerated dissolution of IMC. It was worth mentioning that, in comparison to 2D mesoporous silica, 3DOM silica displayed a more rapid release profile, which may be ascribed to the 3D interconnected pore networks and the highly accessible surface areas. The results obtained from the stability test indicated that the amorphous state of IMC entrapped in the 2D mesoporous silica (SBA-15 and MCM-41 has a better physical stability than in that of 3DOM silica. Moreover, the dissolution rate and stability of IMC loaded in 3DOM silica was closely related to the pore size of macroporous silica. The colorimetric 3-(4,5-Dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT and Cell Counting Kit (CCK-8 assays in combination with direct morphology observations demonstrated the good biocompatibility of nanoporous

Hexamethyldisilazane Removal with Mesoporous Materials Prepared from Calcium Fluoride Sludge.

Science.gov (United States)

Kao, Ching-Yang; Lin, Min-Fa; Nguyen, Nhat-Thien; Tsai, Hsiao-Hsin; Chang, Luh-Maan; Chen, Po-Han; Chang, Chang-Tang

2018-05-01

A large amount of calcium fluoride sludge is generated by the semiconductor industry every year. It also requires a high amount of fuel consumption using rotor concentrators and thermal oxidizers to treat VOCs. The mesoporous adsorbent prepared by calcium fluoride sludge was used for VOCs treatment. The semiconductor industry employs HMDS to promote the adhesion of photo-resistant material to oxide(s) due to the formation of silicon dioxide, which blocks porous adsorbents. The adsorption of HMDS (Hexamethyldisiloxane) was tested with mesoporous silica materials synthesized from calcium fluoride (CF-MCM). The resulting samples were characterized by XRD, XRF, FTIR, N2-adsorption-desorption techniques. The prepared samples possessed high specific surface area, large pore volume and large pore diameter. The crystal patterns of CF-MCM were similar with Mobil composite matter (MCM-41) from TEM image. The adsorption capacity of HMDS with CF-MCM was 40 and 80 mg g-1, respectively, under 100 and 500 ppm HMDS. The effects of operation parameters, such as contact time and mixture concentration, on the performance of CF-MCM were also discussed in this study.

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.

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

synthesis, characterization and catalytic activity of the pillared molecular sieve MCM-36

NARCIS (Netherlands)

He, Y.; Nivarthy, G.S.; Eder, F.; Eder, F.; Seshan, Kulathuiyer; Lercher, J.A.

1998-01-01

MCM-36 materials were prepared by swelling the layered MCM-22 precursors with large organic molecules and then pillaring the resulting material with polymeric silica. A mesopore region with 0.25–0.3 nm thickness between the microporous layers was identified. The BET surface area obtained for MCM-36

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.

Grafting of a novel gold(III) complex on nanoporous MCM-41 and evaluation of its toxicity in Saccharomyces cerevisiae.

Science.gov (United States)

Fazaeli, Yousef; Amini, Mostafa M; Ashourion, Hamed; Heydari, Homayoun; Majdabadi, Abbas; Jalilian, Amir Reza; Abolmaali, Shamsozoha

2011-01-01

The goal of this research was to investigate the potential of newly synthesized gold complex trichloro(2,4,6-trimethylpyridine)Au(III) as an anticancer agent. The gold(III) complex was synthesized and grafted on nanoporous silica, MCM-41, to produce AuCl(3)@PF-MCM- 41 (AuCl(3) grafted on pyridine-functionalized MCM-41). The toxicity of trichloro(2,4,6- trimethylpyridine)Au(III) and AuCl(3)@PF-MCM-41 in Saccharomyces cerevisiae (as a model system) was studied. The gold(III) complex showed a mid cytotoxic effect on yeast viability. Using the drug delivery system, nanoporous MCM-41, the gold(III) complex became a strong inhibitor for growth of yeast cells at a very low concentration. Furthermore, the animal tests revealed a high uptake of AuCl(3)@PF-MCM-41 in tumor cells. The stability of the compound was confirmed in human serum.

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.

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.

Solid State NMR Characterization of Ibuprofen:Nicotinamide Cocrystals and New Idea for Controlling Release of Drugs Embedded into Mesoporous Silica Particles.

Science.gov (United States)

Skorupska, Ewa; Kaźmierski, Sławomir; Potrzebowski, Marek J

2017-05-01

Grinding and melting methods were employed for synthesis of pharmaceutical cocrystals formed by racemic (R/S) and entiomeric (S) ibuprofen (IBU) and nicotinamide (NA) as coformer. Obtained (R/S)-IBU:NA and (S)-IBU:NA cocrystals were fully characterized by means of advanced one- and two-dimensional solid state nuclear magnetic resonance (SS NMR) techniques with very fast magic angle spinning (MAS) at 60 kHz. The distinction in molecular packing and specific hydrogen bonding pattern was clearly recognized by analysis of 1 H, 13 C, and 15 N spectra. It is concluded from these studies that both methods (grinding and melting) provide exactly the same, specific forms of cocrystals. Thermal solvent-free (TSF) approach was used for loading of (R/S)-IBU:NA and (S)-IBU:NA into the pores of MCM-41 mesoporous silica particle (MSP). The progress and efficiency of this process was analyzed by NMR spectroscopy. It has been confirmed that TSF method is an effective and safe technique of filling the MSP pores with active pharmaceutical ingredients (APIs). By analyzing the NMR results, it has been further proved that excess of IBU and NA components, which are not embedded into the pores during melting and cooling, crystallize on the MCM-41 walls preserving very specific arrangement, characteristic for crystalline samples. By investigating kinetic of release for (R/S)-IBU/MCM-41, (S)-IBU:NA/MCM-41, and (R/S)-IBU:NA/MCM-41 samples containing active components exclusively inside of the pores, it was revealed that release of IBU is much faster for the first of the samples compared to those containing IBU and NA inside the pores. The hypothesis that the rate of release of API can be controlled by specific composition of cocrystal embedded into the MSP pore was further supported by study of (R/S)-IBU:BA/MCM-41 sample with benzoic acid (BA) as coformer.

Effects of surface acidities of MCM-41 modified with MoO3 on adsorptive desulfurization of gasoline

International Nuclear Information System (INIS)

Shao Xinchao; Zhang Xiaotong; Yu Wenguang; Wu Yuye; Qin Yucai; Sun Zhaolin; Song Lijuan

2012-01-01

Highlights: ► The MoO 3 -MCM-41 samples prepared by spontaneous monolayer dispersion and impregnation with a different MoO 3 filling have been studied. ► The relative concentration of hydroxyl groups present on before and after containing MoO 3 samples was monitored by in situ FTIR to speculate the bonding style of MoO 3 and MCM-41. ► The surface acidities of the MoO 3 -MCM-41 adsorbents were investigated systematically and correlated with the desulfurization performance. - Abstract: A series of MCM-41 samples containing molybdenum oxide as active species in the mesoporous channels loaded by spontaneous monolayer dispersion (SMD) and impregnation (IM) have been prepared and characterized using XRD, N 2 adsorption–desorption analysis, Fourier transform infrared spectroscopy (FTIR) and intelligent gravimetric analyzer (IGA). The relative number of hydroxy on the adsorbents was investigated by in situ FTIR. Surface acidities of the adsorbents were studied by infrared spectroscopy of adsorbed pyridine and correlated with reactivity for adsorptive desulfurization. The IGA technique was employed to investigate adsorption behavior of thiophene and benzene on the adsorbents at 303 K. It is shown that MoO 3 can be highly dispersed up to 0.2 g g −1 in the MCM-41 channels by the SMD strategy with the ordered mesoporous structure of the MoMM samples remaining intact. The ordered mesostructure of MCM-41 is, however, destroyed at higher MoO 3 contents of 0.26 and 0.32 g g −1 with particle sizes of 1.2 nm and 3.6 nm, respectively, observed. For the MoMI(0.2) sample prepared by the IM method, the aggregation of the MoO 3 particles takes place with a particle size of 6.5 nm obtained. The results are also revealed that the dispersion extent of the MoO 3 species is related to the abundant surface hydroxy of MCM-41. The host species and guest species undergo solid-state reaction to form Si-O-Mo bonds in the mixtures which enhance both the Lewis acid and Brönsted acid of

Response of Fibroblasts MRC-5 to Flufenamic Acid-Grafted MCM-41 Nanoparticles

Directory of Open Access Journals (Sweden)

Giovanna Gomes Lara

2018-01-01

Full Text Available Recently, flufenamic acid (FFA was discovered among fenamates as a free radical scavenger and gap junction blocker; however, its effects have only been studied in cancer cells. Normal cells in the surroundings of a tumor also respond to radiation, although they are not hit by it directly. This phenomenon is known as the bystander effect, where response molecules pass from tumor cells to normal ones, through communication channels called gap junctions. The use of the enhanced permeability and retention effect, through which drug-loaded nanoparticles smaller than 200 nm may accumulate around a tumor, can prevent the local side effect upon controlled release of the drug. The present work, aimed at functionalizing MCM-41 (Mobil Composition of Matter No. 41 silica nanoparticles with FFA and determining its biocompatibility with human fibroblasts MRC-5 (Medical Research Council cell strain 5. MCM-41, was synthesized and characterized structurally and chemically, with multiple techniques. The biocompatibility assay was performed by Live/Dead technique, with calcein and propidium–iodide. MRC-5 cells were treated with FFA-grafted MCM-41 for 48 h, and 98% of cells remained viable, without signs of necrosis or morphological changes. The results show the feasibility of MCM-41 functionalization with FFA, and its potential protection of normal cells, in comparison to the role of FFA in cancerous ones.

Response of Fibroblasts MRC-5 to Flufenamic Acid-Grafted MCM-41 Nanoparticles.

Science.gov (United States)

Lara, Giovanna Gomes; Cipreste, Marcelo Fernandes; Andrade, Gracielle Ferreira; Silva, Wellington Marcos da; Sousa, Edésia Martins Barros de

2018-01-09

Recently, flufenamic acid (FFA) was discovered among fenamates as a free radical scavenger and gap junction blocker; however, its effects have only been studied in cancer cells. Normal cells in the surroundings of a tumor also respond to radiation, although they are not hit by it directly. This phenomenon is known as the bystander effect, where response molecules pass from tumor cells to normal ones, through communication channels called gap junctions. The use of the enhanced permeability and retention effect, through which drug-loaded nanoparticles smaller than 200 nm may accumulate around a tumor, can prevent the local side effect upon controlled release of the drug. The present work, aimed at functionalizing MCM-41 (Mobil Composition of Matter No. 41) silica nanoparticles with FFA and determining its biocompatibility with human fibroblasts MRC-5 (Medical Research Council cell strain 5). MCM-41, was synthesized and characterized structurally and chemically, with multiple techniques. The biocompatibility assay was performed by Live/Dead technique, with calcein and propidium-iodide. MRC-5 cells were treated with FFA-grafted MCM-41 for 48 h, and 98% of cells remained viable, without signs of necrosis or morphological changes. The results show the feasibility of MCM-41 functionalization with FFA, and its potential protection of normal cells, in comparison to the role of FFA in cancerous ones.

pH and ion strength modulated ionic species loading in mesoporous silica nanoparticles

International Nuclear Information System (INIS)

Liu, Wei; Liu, Jianbo; Yang, Xiaohai; Wang, Kemin; Wang, Qing; Yang, Meng; Li, Li; Xu, Jianguo

2013-01-01

Mesoporous silica nanoparticles (MSN) have emerged as appealing host materials to accommodate guest molecules for biomedical applications, and recently various methods have been developed to modulate the loading of guest molecules in the silica matrix. Herein, it was demonstrated that pH and ion strength showed great influence on the loading of charged species into the nanoparticles, taking MCM-41 as a host MSN model and methylviologen (MV 2+ ) and 1,5-naphthalene disulfonate (NDS 2− ) as typical charged ionic guest molecules. As the pH increased from 3.0 to 8.0, the loading amount of MV 2+ increased gradually, while on the contrary, it decreased gradually for NDS 2− , for the solution pH changed the electrostatic interaction between the silica matrix and the ionic guest molecules. Additionally, the adding of NaCl reduced the electrostatic interaction, which resulted in a decreasing of the electrostatic rejection and electrostatic accumulation for the molecules carrying the same and the opposite charge to the particle respectively. Thus, pH and ion strength can be employed as simple approaches to modulate the loading of charged molecules and permselectivity in MSN. This work has a definite guidance function for molecule loading, transport modulation, controlled release as well as sensors based on MSN. (paper)

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. Copyright © 2016. Published by Elsevier B.V.

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.

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

Synthesis, characterization, and application of surface-functionalized ordered mesoporous nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Chung, Po-Wen [Iowa State Univ., Ames, IA (United States)

2009-01-01

The dissertation begins with Chapter 1, which is a general introduction of the fundamental synthesis of mesoporous silica materials, the selective functionlization of mesoporous silica materials, and the synthesis of nanostructured porous materials via nanocasting. In Chapter 2, the thermo-responsive polymer coated mesoporous silica nanoparticles (MSN) was synthesized via surface-initated polymerization and exhibited unique partition activities in a biphasic solution with the thermally induced change. In Chapter 3, the monodispersed spherical MSN with different mesoporous structure (MCM-48) was developed and employed as a template for the synthesis of mesoporous carbon nanoparticles (MCN) via nanocasting. MCN was demonstrated for the delivery of membrane impermeable chemical agents inside the cells. The cellular uptake efficiency and biocompabtibility of MCN with human cervical cancer cells were also investigated. In addition to the biocompabtibility of MCN, MCN was demonstrated to support Rh-Mn nanoparticles for catalytic reaction in Chapter 4. Owing to the unique mesoporosity, Rh-Mn nanoparticles can be well distributed inside the mesoporous structure and exhibited interesting catalytic performance on CO hydrogenation. In Chapter 5, the synthesis route of the aforementioned MCM-48 MSN was discussed and investigated in details and other metal oxide nanoparticles were also developed via nanocasting by using MCM-48 MSN as a template. At last, there is a general conclusion summarized in Chapter 6.

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.

Synthesis of Novel Mesoporous Silica Materials with Hierarchical Pore Structures

Energy Technology Data Exchange (ETDEWEB)

Yoon, Suk Bon; Choi, Wang Kyu; Choi, Byung Seon; Moon, Jei Kwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2012-05-15

Porous materials with various pore sizes in the range of micropore (< 2 nm), mesopore (2-50 nm), and macropore (> 50 nm) are attractive due to their many emerging applications such as catalysts, separation systems, and low dielectric constant materials. The discovery of new M41S mesoporous silica families with pore sizes larger than 2 nm in diameter in 1992 extended the applications into much wider pore ranges, bringing in a new prosperous era in porous material research. The synthesis of these silica materials has been mainly accomplished through a self-assembly between surfactant molecules and inorganic species under various pH conditions. Recently, core-shell nanoparticles with a silica core and mesoporous shell under basic conditions were synthesized using the silica nanoparticles as a core, and a silica precursor (TEOS) and cationic surfactant (CTABr) as a material for the formation of the mesoporous shell. The resultant materials were very monodispersive in size and showed a narrow pore size distribution in the range of ca 2-3 nm in diameter, depending on the alkyl-chain length of the surfactants used. In this work, the mesoporous shell coated-fumed silicas (denoted as MS M-5s) were synthesized by using fumed silica instead of the silica nanoparticle as a core based on previous reports. Also, the structural properties of the MS M-5s such as the specific surface area and pore volume were easily controlled by varying the amount of the silica precursor and surfactant. The resultant materials exhibited a BET surface area of ca 279-446 m{sup 2}/g and total pore volume of ca 0.64-0.74 cm{sup 3}/g and showed a narrow pore size distribution (PSD) due to the removal of the organic surfactant molecules

Influence of incorporation method of sulfated zirconia in MCM-41 molecular sieve; Influencia do metodo de incorporacao da zirconia sulfatada na peneira molecular MCM-41

Energy Technology Data Exchange (ETDEWEB)

Pereira, C.E.; Santos, J.S.B.; Cavalcante, J.N.A.; Andrade, M.R.A.; Sousa, B.V., E-mail: eduardopereira.eq@gmail.com [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Centro de Ciencia e Tecnologia

2016-07-01

Sulfated metal oxides and sulfated zirconia have attracted great attention in recent years due to its high catalytic activity. The sulfated zirconia has the function of assigning the acidic material, through the formation of Bronsted acids and Lewis sites. The incorporation of sulfated zirconia in MCM-41 molecular sieve was carried out through the techniques: dry and wet. The wet process involves the use of an excess of solution on the volume of the support pores. Therefore, the concentration of the metal precursor on the support depends on the solution concentration and the pore volume of the support. In the process of incorporating by dry, the volume of the solution containing the precursor does not exceed the pore volume of the support. After either procedure, the impregnated support must be dried in order to allow the precursor compound can be converted into a catalytically active phase. This study aims to evaluate two methods of incorporation of sulfated zirconia in the mesoporous molecular sieve MCM-41. The process of merger took for wet and dry impregnation. Through the XRD patterns it was possible to identify the presence of the hexagonal structure of the molecular sieve, as well as the tetragonal and monoclinic phases of zirconia. From the spectroscopic analysis in the infrared region to the method the wet, it was possible to identify the vibrational frequencies related to the merger of sulfated zirconia in the MCM-41 structure of the molecular sieve. (author)

Adsorption of toxic metal ion Cr(VI) from aqueous state by TiO2-MCM-41: equilibrium and kinetic studies.

Science.gov (United States)

Parida, Kulamani; Mishra, Krushna Gopal; Dash, Suresh Kumar

2012-11-30

This paper deals with the immobilization of various weight percentage of TiO(2) on mesoporous MCM-41, characterization of the materials by X-ray diffraction (XRD), nitrogen adsorption-desorption, Fourier Transform Infrared (FTIR) analysis, UV-vis diffuse reflectance spectroscopy (DRS) and evaluation of the adsorption capacity toward Cr(VI) removal. It is found that the MCM-41 structure retained after loading of TiO(2) but the surface area and pore diameter decreased due to pore blockage. Adsorption of Cr(VI) from aqueous state was investigated on TiO(2)-MCM-41 by changing various parameters such as pH, metal ion concentration, and the temperature. When TiO(2) loading was more than 20 wt.%, the adsorption activity (25)TiO(2)-MCM-41 reduced significantly due to considerable decrease in the surface area. It is also observed that TiO(2) and neat MCM-41 exhibits very less Cr(VI) adsorption compared to TiO(2)-MCM-41. The adsorption of Cr(VI) onto (20)TiO(2)-MCM-41 at pH~5.5 and temperature 323 K was 91% at 100mg/L Cr(VI) metal ion concentration in 80 min. The experimental data fitted well to Langmuir and Freundlich isotherms. The adsorption of Cr(VI) on TiO(2)-MCM-41 followed a second order kinetics with higher values of intra-particle diffusion rate. Thermodynamic parameters suggested that the adsorption process is endothermic in nature and desorption studies indicated a chemisorption mode. Copyright © 2012 Elsevier B.V. All rights reserved.

Analysis of nitrogen and carbon tetrachloride adsorption isotherms and pore size distribution for siliceous MCM-41 synthesized from rice husk silica

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Siriluk Chiarakorn

2004-02-01

Full Text Available RH-MCM-41 particles were synthesized using sodium silicate prepared from rice husk as a silica source and hexadecyltrimethylammonium bromide (CTAB as a surfactant. The molar compositions were 1.0SiO2: 1.1NaOH: 0.13CTAB: 0.12H2O. This material was used for adsorption isotherm studies of carbon tetrachloride (CT at 25 oC using a magnetically coupled microbalance, and compared with adsorption isotherms using nitrogen at 77 K. The CT isotherms were classified as reversible Type V isotherms, and the nitrogen adsorption isotherm was Type IVc. Capillary condensation was found in a very narrow pressure range, indicating the presence of nearly uniform pores in the RH-MCM-41 particles, which agrees very well with TEM results. The surface area estimated by using the BET method was (800 ± 8 m2 g-1. Pore size distributions (PSD of nitrogen and CT adsorption isotherms for a series of MCM-41 were calculated by using method recommended by Naono and Hakuman (1997. The pore size distributions from the nitrogen isotherm using the BJH and Naono methods showed quite narrow pore diameter distributions, centered around 27 and 29 Å, respectively. Similarly, the peak pore diameters calculated from CT isotherms using the BJH and Naono methods were 24 and 28 Å. It was found that the PSDs analyzed by the BJH method were underestimated compared to that from Naono method.

Free-radical sensing by using naphthalimide based mesoporous silica (MCM-41) nanoparticles: A combined fluorescence and cellular imaging study

Science.gov (United States)

Jha, Gaurav; Roy, Subhasis; Sahu, Prabhat Kumar; Banerjee, Somnath; Anoop, N.; Rahaman, Abdur; Sarkar, Moloy

2018-01-01

Keeping in mind the advantages of material-based systems over simple molecule-based systems, we have designed and developed three inorganic-organic hybrid systems by anchoring 1,8-naphthalimide derivatives to mesoporous silica nanoparticles for detection of free radicals. Prior to photophysical study, systems are characterized by spectroscopic, microscopic and thermo-gravimetric techniques. Steady state and time-resolved fluorescence studies demonstrate that the hydrazine based system is senstive towards detection of various free radicals. Cellular imaging study reveals cell permeability and toxicity study demonstrates the non-toxic nature of the material. These studies have suggested that present system has the potential to be used in various biological applications.

Functionalized Mesoporous Silica Membranes for CO2 Separation Applications

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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.

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

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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.

A review on chemical methodologies for preparation of mesoporous silica and alumina based materials.

Science.gov (United States)

Naik, Bhanudas; Ghosh, Narendra Nath

2009-01-01

The discovery of novel family of molecular sieves called M41S aroused a worldwide resurgence in the field of porous materials. According to IUPAC definition inorganic solids that contain pores with diameter in the size range of 20-500 A are considered mesoporous materials. Mesoporous silica and alumina based materials find applications in catalysis, adsorption, host- guest encapsulation etc. This article reviews the current state of art and outline the recent patents in mesoporous materials research in three general areas: Synthesis, various mechanisms involved for porous structure formation and applications of silica and alumina based mesoporous materials.

Study of the reinforcement of rubber styrene-butadiene with mesoporous silices by solid-state nuclear magnetic resonance

International Nuclear Information System (INIS)

Sierra, Ligia; Lopez, Betty; Pena, Bibiana; Rios, Juan Esteban; Castano, Nelson

2001-01-01

The knowledge about the interaction rubber/filler for the rubber reinforced with carbon black of silica is important to understand the physical properties, which determine the reinforcement. This paper presents a comparative study of the interactions between styrene butadiene rubber (SBR) and silica for a silica Ultrasil type and mesoporous silica MCM-41 type prepared by different procedures, based on solid state nuclear magnetic resonance: 1H MAS NMR; 13C MAS NMR, 13C CP/MAS, 29Si MAS and 29Si CP/MAS NMR. Mesoporous silica synthesized under certain specific conditions showed better interaction with the rubber than the ultrasil VN3 silica, commonly used as a reinforcement load. Mechanical tests for the SBR vulcanised with this silica indicate an important increase for values of elongation and tearing resistance, but an increase in the vulcanization time in it is compared with the SBR vulcanise with Ultrasil

Preparation, characterization and photocatalytic applications of amine-functionalized mesoporous silica impregnated with transition-metal-monosubstituted polyoxometalates

International Nuclear Information System (INIS)

Li Li; Liu, Chunming; Geng Aifang; Jiang Chunjie; Guo Yihang; Hu Changwen

2006-01-01

Amine-functionalized mesoporous silica materials impregnated with transition-metal-monosubstituted polyoxometalates, K 5 [M(H 2 O)PW 11 O 39 ]-(EtO) 3 SiCH 2 CH 2 CH 2 NH 2 -MCM-48 (M = Co/Ni), were prepared by coordination of nickel/cobalt centers in the clusters with the amine surface groups in amine-functionalized mesoporous silica supports. The materials obtained were characterized by powder X-ray diffraction (XRD), UV-vis diffuse reflectance spectra (UV-vis-DR), infrared (IR) spectra, magic-angle spinning 31 P MAS NMR, transmission electron microscopy (TEM) and nitrogen adsorption measurements, indicating that the primary Keggin structures remained intact in as-prepared composites, and the composites possessed mesoporous structures. The composites exhibited UV-photocatalytic activity to degrade dye rhodamine B (RB), and the pesticides including hexachlorobenzene (HCB) and methylparathion (MPT). Leakage of K 5 [M(H 2 O)PW 11 O 39 ] from the support was hardly observed during the photocatalytic tests, attributed to strong coordination interactions between the Keggin units and the amine-functionalized silica surface. -- Graphical abstract: The K 5 [M(H 2 O)PW 11 O 39 ]-(EtO) 3 SiCH 2 CH 2 CH 2 NH 2 -SiO 2 composites were prepared by coordination of M centers in the Keggin units with the amine surface groups in amine-functionalized mesoporous silica supports, and the composites exhibited photocatalytic activity to degrade aqueous rhodamine B, hexachlorobenzene and methyl parathion

Innovative preparation of Au/C by replication of gold-containing mesoporous silica catalysts

KAUST Repository

Kerdi, Fatmé

2010-01-01

A new strategy, based on the nanocasting concept, has been used to prepare gold nanoparticles (NPs) highly dispersed in meso-structured carbons. Gold is first introduced in various functionalized mesostructured silicas (MCM-48 and SBA-15) and particles are formed inside the porosity upon reduction of Au 3+ cations. Silica pores are then impregnated with a carbon precursor and the composite material is heated at 900°C under vacuum. Silica is then removed by acid leaching, leading to partially encapsulated gold particles in mesoporous carbon. Carbon prevents aggregation of gold particles at high temperature, both the mean size and distribution being similar to those observed in silica. However, while Au@SiO2 exhibit significant catalytic activity in the aerobic oxidation of trans-stilbene in the liquid phase, its Au@C mesostructured replica is quite inactive. © 2010 Elsevier B.V. All rights reserved.

Synthesis of acid-base bifunctional mesoporous materials by oxidation and thermolysis

Energy Technology Data Exchange (ETDEWEB)

Yu, Xiaofang [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China); Zou, Yongcun [State Key Laboratory of Inoranic Synthesis and Preparative Chemistryg, College of Chemistry, Jilin University, Changchun 130012 (China); Wu, Shujie; Liu, Heng [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China); Guan, Jingqi, E-mail: guanjq@jlu.edu.cn [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China); Kan, Qiubin, E-mail: qkan@jlu.edu.cn [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China)

2011-06-15

Graphical abstract: A novel and efficient method has been developed for the synthesis of acid-base bifunctional catalyst. The obtained sample of SO{sub 3}H-MCM-41-NH{sub 2} containing amine and sulfonic acids exhibits excellent catalytic activity in aldol condensation reaction. Research highlights: {yields} Synthesize acid-base bifunctional mesoporous materials SO{sub 3}H-MCM-41-NH{sub 2}. {yields} Oxidation and then thermolysis to generate acidic site and basic site. {yields} Exhibit good catalytic performance in aldol condensation reaction between acetone and various aldehydes. -- Abstract: A novel and efficient method has been developed for the synthesis of acid-base bifunctional catalyst SO{sub 3}H-MCM-41-NH{sub 2}. This method was achieved by co-condensation of tetraethylorthosilicate (TEOS), 3-mercaptopropyltrimethoxysilane (MPTMS) and (3-triethoxysilylpropyl) carbamicacid-1-methylcyclohexylester (3TAME) in the presence of cetyltrimethylammonium bromide (CTAB), followed by oxidation and then thermolysis to generate acidic site and basic site. X-ray diffraction (XRD) and transmission electron micrographs (TEM) show that the resultant materials keep mesoporous structure. Thermogravimetric analysis (TGA), X-ray photoelectron spectra (XPS), back titration, solid-state {sup 13}C CP/MAS NMR and solid-state {sup 29}Si MAS NMR confirm that the organosiloxanes were condensed as a part of the silica framework. The bifunctional sample (SO{sub 3}H-MCM-41-NH{sub 2}) containing amine and sulfonic acids exhibits excellent acid-basic properties, which make it possess high activity in aldol condensation reaction between acetone and various aldehydes.

Effects of surface acidities of MCM-41 modified with MoO{sub 3} on adsorptive desulfurization of gasoline

Energy Technology Data Exchange (ETDEWEB)

Shao Xinchao, E-mail: sxc86@yahoo.cn [Key Laboratory of Petrochemical Catalytic Science and Technology, Liaoning ShiHua University, Fushun 113001 (China); Zhang Xiaotong; Yu Wenguang; Wu Yuye [Key Laboratory of Petrochemical Catalytic Science and Technology, Liaoning ShiHua University, Fushun 113001 (China); Qin Yucai [Key Laboratory of Petrochemical Catalytic Science and Technology, Liaoning ShiHua University, Fushun 113001 (China); College of Chemistry and Chemical Engineering, China University of Petroleum (East China), Qingdao, Shandong 257061 (China); Sun Zhaolin [Key Laboratory of Petrochemical Catalytic Science and Technology, Liaoning ShiHua University, Fushun 113001 (China); School of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Song Lijuan, E-mail: lsong56@263.net [Key Laboratory of Petrochemical Catalytic Science and Technology, Liaoning ShiHua University, Fushun 113001 (China) and College of Chemistry and Chemical Engineering, China University of Petroleum (East China), Qingdao, Shandong 257061 (China)

2012-12-15

Highlights: Black-Right-Pointing-Pointer The MoO{sub 3}-MCM-41 samples prepared by spontaneous monolayer dispersion and impregnation with a different MoO{sub 3} filling have been studied. Black-Right-Pointing-Pointer The relative concentration of hydroxyl groups present on before and after containing MoO{sub 3} samples was monitored by in situ FTIR to speculate the bonding style of MoO{sub 3} and MCM-41. Black-Right-Pointing-Pointer The surface acidities of the MoO{sub 3}-MCM-41 adsorbents were investigated systematically and correlated with the desulfurization performance. - Abstract: A series of MCM-41 samples containing molybdenum oxide as active species in the mesoporous channels loaded by spontaneous monolayer dispersion (SMD) and impregnation (IM) have been prepared and characterized using XRD, N{sub 2} adsorption-desorption analysis, Fourier transform infrared spectroscopy (FTIR) and intelligent gravimetric analyzer (IGA). The relative number of hydroxy on the adsorbents was investigated by in situ FTIR. Surface acidities of the adsorbents were studied by infrared spectroscopy of adsorbed pyridine and correlated with reactivity for adsorptive desulfurization. The IGA technique was employed to investigate adsorption behavior of thiophene and benzene on the adsorbents at 303 K. It is shown that MoO{sub 3} can be highly dispersed up to 0.2 g g{sup -1} in the MCM-41 channels by the SMD strategy with the ordered mesoporous structure of the MoMM samples remaining intact. The ordered mesostructure of MCM-41 is, however, destroyed at higher MoO{sub 3} contents of 0.26 and 0.32 g g{sup -1} with particle sizes of 1.2 nm and 3.6 nm, respectively, observed. For the MoMI(0.2) sample prepared by the IM method, the aggregation of the MoO{sub 3} particles takes place with a particle size of 6.5 nm obtained. The results are also revealed that the dispersion extent of the MoO{sub 3} species is related to the abundant surface hydroxy of MCM-41. The host species and guest

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.

Synthesis of Dicyclopentadiene Oligomer Over Nanoporous Al-MCM-41 Catalysts.

Science.gov (United States)

Park, Eunseo; Kim, Jinhan; Yim, Jin-Heong; Han, Jeongsik; Kwon, Tae Soo; Park, Y K; Jeon, Jong-Ki

2016-05-01

One step reaction composed of DCPD oligomerization and DCPD oligomer isomerization was investigated over nanoporous Al-MCM-41 catalysts. The effects of aluminum grafting over MCM-41 on the catalyst characteristics were studied with respect to the synthesis of TCPD isomer. Physical and chemical properties of the catalysts were analyzed by N2 adsorption, temperature-programmed desorption of ammonia, and infrared spectroscopy of adsorbed pyridine. The overall number of acid sites as well as the number of Lewis acid sites increased with increasing of aluminum content over MCM-41. When utilizing MCM-41 and Al-MCM-41 as the catalyst, DCPD oligomerization reaction activity greatly increased compared to the thermal reaction. The highest TCPD isomer selectivity over the Al-MCM-41 catalyst with the highest aluminum content could be ascribed to the largest amount of acid sites. This study showed an increased level of TCPD isomer selectivity by an increasing level of Lewis acid sites through aluminum addition over MCM-41.

Enhanced adsorptive and photocatalytic achievements in removal of methylene blue by incorporating tungstophosphoric acid-TiO2 into MCM-41

International Nuclear Information System (INIS)

Zanjanchi, M.A.; Golmojdeh, H.; Arvand, M.

2009-01-01

The use of titania-dispersed materials in photocatalytic processes has been proposed as an alternative to the conventional bare TiO 2 , in order to modify the surface area and activity of the catalyst. A homogeneously dispersed Keggin unit into TiO 2 was synthesized using tungstophosphoric acid (TPA) and titanium tetraisopropoxide. This compound was then loaded into MCM-41 by dispersing it in a suspension containing the mesoporous phase. Two other titanium-containing MCM-41 catalysts, Ti-MCM-41 and TiO 2 /MCM-41 were also prepared using isomorphous substitution synthesis method and impregnation method, respectively, for the sake of comparison. The prepared photocatalysts were characterized by X-ray diffraction (XRD), nitrogen physisorption (BET) and chemical analysis. The catalysts were used to study degradation of methylene blue (MB) in aqueous solution. XRD result shows a pure anatase crystalline phase for TPA-containing TiO 2 indicating that there is good molecular distribution of tungstophosphoric acid into TiO 2 structure. Supported TPA-TiO 2 into MCM-41 shows both TPA-TiO 2 and MCM-41 characteristic X-ray reflections in the high-angle and low-angle parts of the XRD patterns, respectively. The experimental results show that adsorption is a major constituent in the elimination of MB from the dye solutions by the TPA-containing materials. Exploitation of both adsorption and photocatalytic processes speeds up the removal of the dye using the TPA-TiO 2 -loaded MCM-41 photocatalyst. The elimination of MB is completed within 15 min for a 30 mg l -1 MB solution containing a catalyst dose of 100 mg/100 ml. The efficiencies of the other photocatalysts such as commercial TiO 2 , Ti-MCM-41, TiO 2 /MCM-41 and TPA-TiO 2 for adsorption and degradation of MB were also studied and compared with that of the prepared catalyst.

Influence of incorporation method of sulfated zirconia in MCM-41 molecular sieve

International Nuclear Information System (INIS)

Pereira, C.E.; Santos, J.S.B.; Cavalcante, J.N.A.; Andrade, M.R.A.; Sousa, B.V.

2016-01-01

Sulfated metal oxides and sulfated zirconia have attracted great attention in recent years due to its high catalytic activity. The sulfated zirconia has the function of assigning the acidic material, through the formation of Bronsted acids and Lewis sites. The incorporation of sulfated zirconia in MCM-41 molecular sieve was carried out through the techniques: dry and wet. The wet process involves the use of an excess of solution on the volume of the support pores. Therefore, the concentration of the metal precursor on the support depends on the solution concentration and the pore volume of the support. In the process of incorporating by dry, the volume of the solution containing the precursor does not exceed the pore volume of the support. After either procedure, the impregnated support must be dried in order to allow the precursor compound can be converted into a catalytically active phase. This study aims to evaluate two methods of incorporation of sulfated zirconia in the mesoporous molecular sieve MCM-41. The process of merger took for wet and dry impregnation. Through the XRD patterns it was possible to identify the presence of the hexagonal structure of the molecular sieve, as well as the tetragonal and monoclinic phases of zirconia. From the spectroscopic analysis in the infrared region to the method the wet, it was possible to identify the vibrational frequencies related to the merger of sulfated zirconia in the MCM-41 structure of the molecular sieve. (author)

Investigation of Room Temperature Synthesis of Titanium Dioxide Nanoclusters Dispersed on Cubic MCM-48 Mesoporous Materials

OpenAIRE

Sridhar Budhi; Chia-Ming Wu; Dan Zhao; Ranjit T. Koodali

2015-01-01

Titania containing cubic MCM-48 mesoporous materials were synthesized successfully at room temperature by a modified Stöber method. The integrity of the cubic mesoporous phase was retained even at relatively high loadings of titania. The TiO2-MCM-48 materials were extensively characterized by a variety of physico-chemical techniques. The physico-chemical characterization indicate that Ti4+ ions can be substituted in framework tetrahedral positions. The relative amount of Ti4+ ions in tetrahe...

Phase separation of acetonitrile-water mixtures and minimizing of ice crystallites from there in confinement of MCM-41.

Science.gov (United States)

Kittaka, Shigeharu; Kuranishi, Miki; Ishimaru, Shinji; Umahara, Osamu

2007-03-07

The effect of confinement of an acetonitrile-water mixture, whose correlation length was comparable to the pore size of the mesopores of MCM-41 (d=2.4-3.6 nm), on the phase changes was studied. Used techniques were low temperature differential scanning calorimetry and Fourier transform infrared spectroscopy, where the phase separation, lowering of the freezing and melting temperatures, and phase transitions of the acetonitrile were detected. The latter occurred in the mesopores at temperatures similar to that of the pure liquid, while the melting temperature of the water in the mesopores<3.1 nm decreased markedly at higher acetonitrile contents, suggesting a marked lowering of ice crystallite size.

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.

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

KAUST Repository

Yu, Yanjie

2012-01-01

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.

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.

Electrochemistry and determination of epinephrine using a mesoporous Al-incorporated SiO{sub 2} modified electrode

Energy Technology Data Exchange (ETDEWEB)

Zeng, Yanhong; Yang, Jinquan; Wu, Kangbing [Department of Chemistry, Huazhong University of Science and Technology, Wuhan 430074 (China)

2008-05-30

The potential application of Al-incorporated mesoporous SiO{sub 2} (denoted as Al-MCM-41) in electrochemistry as a novel electrode material was investigated. The peak currents of K{sub 3}[Fe(CN){sub 6}] remarkably increase and the peak potential separation obviously decreases at the mesoporous Al-MCM-41 modified carbon paste electrode (CPE). These phenomena suggest that the mesoporous Al-MCM-41 modified CPE possesses larger electrode area and electron transfer rate constant. Furthermore, the electrochemical behavior of epinephrine (EP) was investigated in different supporting electrolytes such as 0.01 mol L{sup -1} HClO{sub 4} and pH 7.0 phosphate buffer. It is found that the mesoporous Al-MCM-41 modified CPE exhibits catalytic ability to the oxidation of EP due to remarkable peak current enhancement and negative shift of peak potential. The electrochemical oxidation mechanism was also discussed. Finally, a novel electrochemical method was proposed for the determination of EP, which used to determine EP in urine samples. (author)

Electrochemistry and determination of epinephrine using a mesoporous Al-incorporated SiO{sub 2} modified electrode

Energy Technology Data Exchange (ETDEWEB)

Zeng Yanhong; Yang Jinquan [Department of Chemistry, Huazhong University of Science and Technology, Wuhan 430074 (China); Wu Kangbing [Department of Chemistry, Huazhong University of Science and Technology, Wuhan 430074 (China)], E-mail: kbwu@mail.hust.edu.cn

2008-05-30

The potential application of Al-incorporated mesoporous SiO{sub 2} (denoted as Al-MCM-41) in electrochemistry as a novel electrode material was investigated. The peak currents of K{sub 3}[Fe(CN){sub 6}] remarkably increase and the peak potential separation obviously decreases at the mesoporous Al-MCM-41 modified carbon paste electrode (CPE). These phenomena suggest that the mesoporous Al-MCM-41 modified CPE possesses larger electrode area and electron transfer rate constant. Furthermore, the electrochemical behavior of epinephrine (EP) was investigated in different supporting electrolytes such as 0.01 mol L{sup -1} HClO{sub 4} and pH 7.0 phosphate buffer. It is found that the mesoporous Al-MCM-41 modified CPE exhibits catalytic ability to the oxidation of EP due to remarkable peak current enhancement and negative shift of peak potential. The electrochemical oxidation mechanism was also discussed. Finally, a novel electrochemical method was proposed for the determination of EP, which used to determine EP in urine samples.

Structure of water in mesoporous organosilica by calorimetry and inelastic neutron scattering

Science.gov (United States)

Levy, Esthy; Kolesnikov, Alexander I.; Li, Jichen; Mastai, Yitzhak

2009-01-01

In this paper, we describe the preparation of mesoporous organosilica samples with hydrophilic or hydrophobic organic functionality inside the silica channel. We synthesized mesoporous organosilica of identical pore sizes based on two different organic surface functionality namely hydrophobic (based on octyltriethoxysilane OTES) and hydrophilic (3-aminopropyltriethoxysilane ATES) and MCM-41 was used as a reference system. The structure of water/ice in those porous silica samples have been investigated over a range temperatures by differential scanning calorimetry (DSC) and inelastic neutron scattering (INS). INS study revealed that water confined in hydrophobic mesoporous organosilica shows vibrational behavior strongly different than bulk water. It consists of two states: water with strong and weak hydrogen bonds (with ratio 1:2.65, respectively), compared to ice-Ih. The corresponding O-O distances in these water states are 2.67 and 2.87 Ǻ, which strongly differ compared to ice-Ih (2.76 Ǻ). INS spectra for water in hydrophilic mesoporous organosilica ATES show behavior similar to bulk water, but with greater degree of disorder.

Mesoporous silica obtained with methyltriethoxysilane as co-precursor in alkaline medium

Czech Academy of Sciences Publication Activity Database

Putz, A.-M.; Wang, K.; Len, A.; Plocek, Jiří; Bezdička, Petr; Kopitsa, G. P.; Khamova, T. V.; Ianasi, C.; Sacarescu, L.; Mitróová, Z.; Savii, C.; Yan, M.; Almásy, L.

2017-01-01

Roč. 424, SI 3 (2017), s. 275-281 ISSN 0169-4332. [International Conference on Physics of Advanced Materials (ICPAM) /9./. Cluj Napoca, 08.09.2016-14.09.2016] Institutional support: RVO:61388980 Keywords : Sol-gel process * mtes/teos * Hydrophobic silica * mcm-41 Subject RIV: CA - Inorganic Chemistry OBOR OECD: Inorganic and nuclear chemistry Impact factor: 3.387, year: 2016

Gel-like properties of MCM-41 material and its transformation to MCM-50 in a caustic alkaline surround

International Nuclear Information System (INIS)

Saputra, Hens; Othman, Raihan; Sutjipto, A.G.E.; Muhida, R.; Ani, M.H.

2012-01-01

Highlights: ► MCM-41 material transforms gradually into MCM-50 lamellar gel upon controlled exposure to 6 M KOH. ► The formation of MCM-50 ordered gel structure occurs at KOH weight content of 40–70 wt. %. ► MCM gel phase shows pseudoplastic behavior and possesses homogeneous matrix texture. -- Abstract: MCM-41 material, prepared by sol–gel method, reveals gel-like properties in a caustic alkaline environment, i.e., 6 M potassium hydroxide (KOH) electrolyte. The gellation of MCM-41 starts at a KOH weight ratio of 40 wt.%. The structural change of the material is verified with X-Ray diffractograms and supported by observation using Scanning Electron Microscope (SEM). As the KOH weight ratio increases, the MCM-41 hexagonal arrays structure gradually transforms into MCM-50 lamellar structure before disappearing completely at 80 wt.% KOH. The MCM gel phase is further characterized by rotational viscometry and texture analysis. The gel phase shows shear thinning or pseudoplastic behavior and possesses homogeneous matrix structure.

Acid-base equilibria inside amine-functionalized mesoporous silica.

Science.gov (United States)

Yamaguchi, Akira; Namekawa, Manato; Kamijo, Toshio; Itoh, Tetsuji; Teramae, Norio

2011-04-15

Acid-base equilibria and effective proton concentration inside a silica mesopore modified with a trimethyl ammonium (TMAP) layer were studied by steady-state fluorescence experiments. The mesoporous silica with a dense TMAP layer (1.4 molecules/nm(2)) was prepared by a post grafting of N-trimethoxysilylpropyl-N,N,N-trimethylammonium at surfactant-templated mesoporous silica (diameter of silica framework =3.1 nm). The resulting TMAP-modified mesoporous silica strongly adsorbed of anionic fluorescence indicator dyes (8-hydroxypyrene-1,3,6-trisulfonate (pyranine), 8-aminopyrene-1,3,6-trisulfonate (APTS), 5,10,15,20-tetraphenyl-21H,23H-porphinetetrasulfonic acid disulfuric acid (TPPS), 2-naphthol-3,6-disulfonate (2NT)) and fluorescence excitation spectra of these dyes within TMAP-modified mesoporous silica were measured by varying the solution pH. The fluorescence experiments revealed that the acid-base equilibrium reactions of all pH indicator dyes within the TMAP-modified silica mesopore were quite different from those in bulk water. From the analysis of the acid-base equilibrium of pyranine, the following relationships between solution pH (pH(bulk)) and the effective proton concentration inside the pore (pH(pore)) were obtained: (1) shift of pH(pore) was 1.8 (ΔpH(pore)=1.8) for the pH(bulk) change from 2.1 to 9.1 (ΔpH(bulk)=7.0); (2) pH(pore) was not simply proportional to pH(bulk); (3) the inside of the TMAP-modified silica mesopore was suggested to be in a weak acidic or neutral condition when pH(bulk) was changed from 2.0 to 9.1. Since these relationships between pH(bulk) and pH(pore) could explain the acid-base equilibria of other pH indicator dyes (APTS, TPPS, 2NT), these relationships were inferred to describe the effective proton concentration inside the TMAP-modified silica mesopore. © 2011 American Chemical Society

Adsorption of CO2 on amine-functionalised MCM-41: experimental and theoretical studies.

Science.gov (United States)

dos Santos, Thiago Custódio; Bourrelly, Sandrine; Llewellyn, Philip L; Carneiro, José Walkimar de M; Ronconi, Célia Machado

2015-04-28

Adsorption of CO2 on MCM-41 functionalised with [3-(2-aminoethylamino)propyl]trimethoxysilane (MCM-41-N2), N(1)-(3-trimethoxysilylpropyl)diethylenetriamine (MCM-41-N3), 4-aminopyridine (MCM-41-aminopyridine), 4-(methylamino)pyridine (MCM-41-methylaminopyridine) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (MCM-41-guanidine) was investigated. The amine-functionalised materials were characterised by (29)Si and (13)C solid-state nuclear magnetic resonance, N2 adsorption/desorption isotherms, X-ray diffraction and transmission electron microscopy. CO2 adsorption at 1.0 bar and 30 °C showed that the amount of CO2 (nads/mmol g(-1)) adsorbed on MCM-41-N2 and MCM-41-N3 is approximately twice the amount adsorbed on MCM-41. For MCM-41-aminopyridine, MCM-41-methylaminopyridine and MCM-41-guanidine, the CO2 adsorption capacity was smaller than that of MCM-41 at the same conditions. The proton affinity (computed with wB97x-D/6-311++G(d,p)) of the secondary amino groups is higher than that of the primary amino groups; however, the relative stabilities of the primary and secondary carbamates are similar. The differential heat of adsorption decreases as the number of secondary amino groups increases.

Mesoporous silica formulation strategies for drug dissolution enhancement: a review.

Science.gov (United States)

McCarthy, Carol A; Ahern, Robert J; Dontireddy, Rakesh; Ryan, Katie B; Crean, Abina M

2016-01-01

Silica materials, in particular mesoporous silicas, have demonstrated excellent properties to enhance the oral bioavailability of poorly water-soluble drugs. Current research in this area is focused on investigating the kinetic profile of drug release from these carriers and manufacturing approaches to scale-up production for commercial manufacture. This review provides an overview of different methods utilized to load drugs onto mesoporous silica carriers. The influence of silica properties and silica pore architecture on drug loading and release are discussed. The kinetics of drug release from mesoporous silica systems is examined and the manufacturability and stability of these formulations are reviewed. Finally, the future prospects of mesoporous silica drug delivery systems are considered. Substantial progress has been made in the characterization and development of mesoporous drug delivery systems for drug dissolution enhancement. However, more research is required to fully understand the drug release kinetic profile from mesoporous silica materials. Incomplete drug release from the carrier and the possibility of drug re-adsorption onto the silica surface need to be investigated. Issues to be addressed include the manufacturability and regulation status of formulation approaches employing mesoporous silica to enhance drug dissolution. While more research is needed to support the move of this technology from the bench to a commercial medicinal product, it is a realistic prospect for the near future.

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.

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.

Silica coated ionic liquid templated mesoporous silica nanoparticles ...

African Journals Online (AJOL)

A series of long chain pyridinium based ionic liquids 1-tetradecylpyridinium bromide, 1-hexadecylpyridinium bromide and 1-1-octadecylpyridinium bromide were used as templates to prepare silica coated mesoporous silica nanoparticles via condensation method under basic condition. The effects of alkyl chain length on ...

Epoxidation of limonene over Ti MCM 41 and Ti BETA

International Nuclear Information System (INIS)

Cubillos Lobo, Jairo Antonio; Gonzalez Rodriguez, Lina Maria; Montes de Correa, Consuelo

2002-01-01

Ti MCM 41 were synthesized and evaluated in the epoxidation of limonene, using peroxide of hydrogen (H 2 O) as agent oxidizer. The characteristic hexagonal phase of Ti MCM 41 was obtained by heating the precursor gel during three days at 100 centigrade degrees. Further heating up to ten days leads to a decrease of this phase. The increase (Ti) in the synthesis gel also decreases that phase. The increase of Ti in the synthesis gel also decreases that phase UV VIS and FTIR spectroscopy indicates that Ti was incorporated in the lattice of Ti MCM 41 as well as, in Ti BETA. SEM micrographs of Ti MCM 41 show that the morphology changes with the Ti loading. Ti MCM 41 was most active than Ti BETA for limonene epoxidation even though both show high selectivity to epoxides

The retained templates as "helpers" for the spherical meso-silica in adsorption of heavy metals and impacts of solution chemistry.

Science.gov (United States)

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

2017-06-15

The spherical mesoporous silica (meso-silica) MCM-41 and those with different dosage of the retained templates were prepared and characterized. Particularly, effects of the retained template and its dosage on the adsorption of typical heavy metals (Cu 2+ and Cd 2+ ) in the synthesized materials were investigated. The results indicated that the retained templates acted as "helpers" for the adsorption of Cu 2+ and Cd 2+ in the spherical meso-silica MCM-41, and the maximum adsorption capacities (Q max ) increased with the increase of the retained template dosage. The interaction between the metal ions and the cationic heads of the templates contributed to the enhancement effect due to the anions (Cl - and OH - ) electronically adsorbed on the interface of the template micelles. Additionally, the presented results indicated that the adsorption of Cu 2+ and Cd 2+ depended on pH and high ion strength of the solution but not on the coexisted humic acid. Copyright © 2017 Elsevier Inc. All rights reserved.

Mesoporous Silica from Rice Husk Ash

Directory of Open Access Journals (Sweden)

S.A. Mandavgane

2010-12-01

Full Text Available Mesoporous silica is used as a raw material in several areas: in preparation of catalysts, in inks, as aconcrete 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 precipitatedfrom the sodium silicate by acidification. In the present work, conversion of about 90% of silica containedin RHA into sodium silicate was achieved in an open system at temperatures of about 100 °C. The resultsshowed 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, usuallycontains carbon particles. Activated carbon embedded on silica has been prepared using the carbon alreadypresent 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

Application of as-synthesised MCM-41 and MCM-41 wrapped with reduced graphene oxide/graphene oxide in the remediation of acetaminophen and aspirin from aqueous system.

Science.gov (United States)

Akpotu, Samson O; Moodley, Brenda

2018-03-01

In this study, ASM41 (as-synthesised MCM-41), MCM-41, MCM-41 encapsulated with graphene oxide (MCM-41-GO) and reduced graphene oxide (MCM-41-G) were fabricated and utilized in the remediation of acetaminophen and aspirin from water. A surfactant template (cetyltrimethylammonium bromide) was added to ASM41 to make it more hydrophobic and its effects on the remediation of acetaminophen and aspirin from wastewater was studied. To further improve the adsorption capacity of the adsorbent, MCM-41 was encapsulated with GO and G which also aided in easy separation of the adsorbent from the aqueous solution. Comparative studies of the adsorption of acetaminophen and aspirin on all four adsorbents were investigated. Batch adsorption studies of acetaminophen and aspirin were carried out to determine the effects of pH, initial concentration, time and adsorbent dose. Adsorption mechanism was through EDA, π-π interactions, and hydrophobic effects. Data from sorption kinetics showed ASM41 had the highest q m value for aspirin (909.1 mg/g) and MCM-41-G had the highest q m value for acetaminophen (555.6 mg/g). The significant adsorption by ASM41 can be attributed to increased hydrophobicity due to the retention of the surfactant template. Thermodynamic studies revealed the adsorption process as spontaneous and exothermic. Desorption studies revealed that adsorbents could be regenerated and reused for adsorption. Copyright © 2017 Elsevier Ltd. All rights reserved.

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.

Photocatalytic removal of Congo red dye using MCM-48/Ni2O3 composite synthesized based on silica gel extracted from rice husk ash; fabrication and application.

Science.gov (United States)

Shaban, Mohamed; Abukhadra, Mostafa R; Hamd, Ahmed; Amin, Ragab R; Abdel Khalek, Ahmed

2017-12-15

MCM-48 mesoporous silica was successfully synthesized from silica gel extracted from rice husk ash and loaded by nickel oxide (Ni 2 O 3 ). The resulted composite was characterized using X-ray diffraction, scanning electron microscope, and UV-vis spectrophotometer. The role of MCM-48 as catalyst support in enhancing the photocatalytic properties of nickel oxide was evaluated through the photocatalytic degradation of Congo red dye under visible light source. MCM-48 as catalyst support for Ni 2 O 3 shows considerable enhancement in the adsorption capacity by 17% and 29% higher than the adsorption capacity of MCM-48 and Ni 2 O 3 , respectively. Additionally, the photocatalytic degradation percentage increased by about 64% relative to the degradation percentage using Ni 2 O 3 as a single component. The adsorption mechanism of MCM-48/Ni 2 O 3 is chemisorption process of multilayer form. The using of MCM-48 as catalyst support for Ni 2 O 3 enhanced the adsorption capacity and the photocatalytic degradation through increasing the surface area and prevents the nickel oxide particles from agglomeration. This was done through fixing nickel oxide particles throughout the porous structure which providing more exposed active adsorption sites and active photocatalyst sites for the incident photons. Based on the obtained results, supporting of nickel oxide particles onto MCM-48 are promising active centers for the degradation of Congo red dye molecules. Copyright © 2017 Elsevier Ltd. All rights reserved.

Preparation and Humidity Sensing Properties of KCl/MCM-41 Composite

International Nuclear Information System (INIS)

Li, Liu; Lian-Yuan, Wang; Wei, Li; Li-Ying, Kou; Zhi-Cheng, Zhong; Li-Fang, Liu

2010-01-01

KCl/mobil composition of matter-41 (MCM-41) composite has been synthesized via a heat-treating process and characterized by x-ray diffraction, high resolution transmission electron microscopy, and nitrogen adsorption/desorption isotherms. In contrast with pure MCM-41, KCl/MCM-41 composite exhibits improved humidity sensing properties within the relative humidity range of 11–95%. The impedance of KCl/MCM-41 composite changes by about four orders of magnitude over the whole humidity range with the response time and the recovery times are about 30 s and 35 s, respectively. Small humidity hysteresis and good stability are also observed based on our product. These results make our product a good candidate in fabricating humidity sensors with high performances and low synthetic complexity

Decay dynamics of blue-green luminescence in meso-porous MCM-41 nanotubes

International Nuclear Information System (INIS)

Lee, Y.C.; Liu, Y.L.; Wang, C.K.; Shen, J.L.; Cheng, P.W.; Cheng, C.F.; Ko, C.-H.; Lin, T.Y.

2005-01-01

Time-resolved photoluminescence (PL) was performed to investigate the decay of blue-green luminescence in MCM-41 nanotubes. The PL decay exhibits a clear nonexponential profile, which can be fitted by a stretched exponential function. In the temperature range from 50 to 300 K the photogenerated carriers become thermally activated with a characteristic energy of 29 meV, which is an indication of the phonon-assisted nonradiative process. The temperature dependence of the lifetime of PL decay has been explained using a model based on the radiative recombination of localized carriers and the phonon-assisted nonradiative recombination

Dehydration of xylose to furfural over MCM-41-supported niobium-oxide catalysts.

Science.gov (United States)

García-Sancho, Cristina; Sádaba, Irantzu; Moreno-Tost, Ramón; Mérida-Robles, Josefa; Santamaría-González, José; López-Granados, Manuel; Maireles-Torres, Pedro

2013-04-01

A series of silica-based MCM-41-supported niobium-oxide catalysts are prepared, characterized by using XRD, N2 adsorption-desorption, X-ray photoelectron spectroscopy, Raman spectroscopy, and pyridine adsorption coupled to FTIR spectroscopy, and tested for the dehydration of D-xylose to furfural. Under the operating conditions used all materials are active in the dehydration of xylose to furfural (excluding the MCM-41 silica support). The xylose conversion increases with increasing Nb2 O5 content. At a loading of 16 wt % Nb2 O5 , 74.5 % conversion and a furfural yield of 36.5 % is achieved at 170 °C, after 180 min reaction time. Moreover, xylose conversion and furfural yield increase with the reaction time and temperature, attaining 82.8 and 46.2 %, respectively, at 190 °C and after 100 min reaction time. Notably, the presence of NaCl in the reaction medium further increases the furfural yield (59.9 % at 170 °C after 180 min reaction time). Moreover, catalyst reutilization is demonstrated by performing at least three runs with no loss of catalytic activity and without the requirement for an intermediate regeneration step. No significant niobium leaching is observed, and a relationship between the structure of the catalyst and the activity is proposed. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Structure study of the tri-continuous mesoporous silica IBN-9 by electron crystallography

KAUST Repository

Zhang, Daliang

2011-12-01

High resolution electron microscopy (HRTEM) has unique advantages for structural determination of nano-sized porous materials compared to X-ray diffraction, because it provides the important structure factor phase information which is lost in diffraction. Here we demonstrate the structure determination of the first tri-continuous mesoporous silica IBN-9 by electron crystallography. IBN-9 has a hexagonal unit cell with the space group P6 3/mcm and a = 88.4 , c = 84.3 . HRTEM images taken along three main directions, [0 0 1], [11̄0] and [1 0 0] were combined to reconstruct the 3D electrostatic potential map, from which the tri-continuous pore structure of IBN-9 was discovered. The different steps of structure determination of unknown mesoporous structures by electron crystallography are described in details. Similar procedures can also be applied for structure determination of other porous and nonporous crystalline materials. © 2011 Elsevier Inc. All rights reserved.

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

Synthesis and characterization of lanthanum incorporated mesoporous molecular sieves

International Nuclear Information System (INIS)

Pesquera, C.; Gonzalez, F.; Blanco, C.; Sanchez, L.

2004-01-01

A series of mesoporous materials under reflux conditions have been synthesized with two silicon sources (fumed silica and sodium silicate) and lanthanum added. The following Si/La molar ratio was used in the samples: 100; 75; 50 and 25. The calcined products were characterized by means of X-ray diffraction, nitrogen adsorption isotherms and energy dispersive X-ray spectrometry (EDS). The BET surface area gradually decreases with an increase in the lanthanum content of the LaxMCM-41 samples. Moreover, the average pore size tends to decrease along with the increase in the La content in the samples

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.

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

KAUST Repository

Soignier, Sophie; Saggio, Guillaume; Taoufik, Mostafa; Basset, Jean-Marie; Thivolle-Cazat, Jean

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.

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.

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. Copyright © 2016 Elsevier B.V. All rights reserved.

Cross flow ultrafiltration of Cr (VI) using MCM-41, MCM-48 and Faujasite (FAU) zeolite-ceramic composite membranes.

Science.gov (United States)

Basumatary, Ashim Kumar; Kumar, R Vinoth; Ghoshal, Aloke Kumar; Pugazhenthi, G

2016-06-01

This work describes the removal of Cr (VI) from aqueous solution in cross flow mode using MCM-41, MCM-48 and FAU zeolite membranes prepared on circular shaped porous ceramic support. Ceramic support was manufactured using locally available clay materials via a facile uni-axial compaction method followed by sintering process. A hydrothermal technique was employed for the deposition of zeolites on the ceramic support. The porosity of ceramic support (47%) is reduced by the formation of MCM-41 (23%), MCM-48 (22%) and FAU (33%) zeolite layers. The pore size of the MCM-41, MCM-48 and FAU membrane is found to be 0.173, 0.142, and 0.153 μm, respectively, which is lower than that of the support (1.0 μm). Cross flow ultrafiltration experiments of Cr (VI) were conducted at five different applied pressures (69-345 kPa) and three cross flow rates (1.11 × 10(-7) - 2.22 × 10(-7) m(3)/s). The filtration studies inferred that the performance of the fabricated zeolite composite membranes is optimum at the maximum applied pressure (345 kPa) and the highest rejection is obtained with the lowest cross flow rate (1.11 × 10(-7) m(3)/s) for all three zeolite membrane. The permeate flux of MCM-41, MCM-48 and FAU zeolite composite membranes are almost remained constant in the entire duration of the separation process. The highest removal of 82% is shown by FAU membrane, while MCM-41 and MCM-48 display 75% and 77% of Cr (VI) removal, respectively for the initial feed concentration of 1000 ppm with natural pH of the solution at an applied pressure of 345 kPa. Copyright © 2016 Elsevier Ltd. All rights reserved.

Modified Ta/MCM-41 catalysts for enantioselective oxidation of thioanisole

OpenAIRE

Fadhli, Marwa; Khedher, Ilyes; Fraile, José M.

2015-01-01

Ta-MCM41 catalysts have been prepared by grafting of Ta(OEt)5 on MCM41, pre-calcined at three different temperatures (550, 650 and 750 °C). These solids have been modified with two chiral ligands: R-(+)-diethyl l-tartrate (DET) and R-(+)-diisopropyl l-tartrate (DIPT). The formation of the chiral tantalum species and their influence on the structure of MCM41 have been studied by several characterization techniques, such as XRD, FTIR, N2 adsorption isotherms and MAS NMR. The grafted tantalum sp...

MCM-41 support for ultrasmall gamma-Fe2O3 nanoparticles for H2S removal

Czech Academy of Sciences Publication Activity Database

Cara, C.; Rombi, E.; Musinu, A.; Mameli, V.; Ardu, A.; Angotzi, M. S.; Atzori, L.; Nižňanský, Daniel; Xin, H. L.; Cannas, C.

2017-01-01

Roč. 5, č. 41 (2017), s. 21688-21698 ISSN 2050-7488 Institutional support: RVO:61388980 Keywords : Nano-sized particles * mesoporous silica nanoparticles * oxide sorbents Subject RIV: CA - Inorganic Chemistry OBOR OECD: Inorganic and nuclear chemistry Impact factor: 8.867, year: 2016

Ordered cubic nanoporous silica support MCM-48 for delivery of poorly soluble drug indomethacin

Science.gov (United States)

Zeleňák, Vladimír; Halamová, Dáša; Almáši, Miroslav; Žid, Lukáš; Zeleňáková, Adriána; Kapusta, Ondrej

2018-06-01

Ordered MCM-48 nanoporous silica (SBET = 923(3) m2·g-1, VP = 0.63(2) cm3·g-1) with cubic Ia3d symmetry was used as a support for drug delivery of anti-inflammatory poorly soluble drug indomethacin. The delivery from parent, unmodified MCM-48, and 3-aminopropyl modified silica carrier was studied into the simulated body fluids with the pH = 2 and pH = 7.4. The studied samples were characterized by thermal analysis (TG/DTG-DTA), N2 adsorption/desorption, infrared spectroscopy (FT-IR), powder XRD, SEM, HRTEM methods, measurements of zeta potential (ζ) and dynamic light scattering (DLS). The determined content of indomethacin in pure MCM-48 was 21 wt.% and in the amine-modified silica MCM-48A-I the content was 45 wt.%. The release profile of the drug, in the time period up to 72 h, was monitored by TLC chromatographic method. It as shown, that by the modification of the surface, the drug release can be controlled. The slower release of indomethacin was observed from amino modified sample MCM-48A-I in the both types of studied simulated body fluids (slightly alkaline intravenous solution with pH = 7.4 and acidic gastric fluid with pH = 2), which was supported and explained by zeta potential and DLS measurements. The amount of the released indomethacin into the fluids with various pH was different. The maximum released amount of the drug was 97% for sample containing unmodified silica, MCM-48-I at pH = 7.4 and lowest released amount, 57%, for amine modified sample MCM-48A-I at pH = 2. To compare the indomethacin release profile four kinetic models were tested. Results showed, that that the drug release based on diffusion Higuchi model, mainly governs the release.

Study of the influence of the silica source on the synthesis of the zeolite precursor MCM-22

International Nuclear Information System (INIS)

Barbosa, A.S.; Santos, E.R.F. dos; Leite, R.C.N.; Rodrigues, M.G.F.

2012-01-01

Zeolite MCM-22 precursors were synthesized under hydrothermal conditions in systems with hexamethyleneimine HMI as bulking agent (driver). Synthesis parameter, such as sources of silica (aerosil® and quartz) was modified to investigate the effects on the morphology and crystallization in precursor MCM-22 zeolite. The products were characterized by X-Ray Diffraction (XRD), Energy Dispersive Spectroscopy (EDX) and Scanning Electron Microscopy (SEM). According to, the X-ray diffraction showed the same characteristic peaks of zeolite MCM-22. It was found that the parameter in this work of synthesis, silica source, affects the hydrothermal synthesis of zeolite MCM-22 precursor. This can be evidenced by the different morphologies found using the different sources of silica. (author)

Simultaneous efficient adsorption of Pb2+ and MnO4− ions by MCM-41 functionalized with amine and nitrilotriacetic acid anhydride

International Nuclear Information System (INIS)

Chen, Feiyun; Hong, Mingzhu; You, Weijie; Li, Chong; Yu, Yan

2015-01-01

Highlights: • MCM-41 was successfully modified with amine and nitrilotriacetic acid anhydride. • The adsorbent can simultaneously remove Pb 2+ and MnO 4 − by adjusting pH of the system. • The maximum adsorption capacities of Pb 2+ and MnO 4 − are 147 mg/g and 156 mg/g. • The absorbent exhibits good regeneration and reusability for 5 cycles use. - Abstract: A novel adsorbent NH 2 /MCM-41/NTAA, capable of simultaneous adsorption of cations and anions from aqueous solution, was prepared by immobilization of amine and nitrilotriacetic acid anhydride (NTAA) onto MCM-41. The structures and properties before and after surface modification were systematically investigated through X-ray diffraction (XRD), transmission electron microscope (TEM) and scanning electron microscope (SEM), nitrogen adsorption–desorption, and infrared spectroscopy (FTIR), thermogravimetry (TGA) and X-ray photoelectron spectroscopy (XPS). They together confirm that the amine and NTAA group were chemically bonded to the internal surface of the mesoporous. The NH 2 /MCM-41/NTAA were used to adsorb Pb 2+ and MnO 4 − in an aqueous solution in a batch system, and the maximum adsorption efficiency was found to occur at pH 5.0 and 3.0, respectively. NH 2 /MCM-41/NTAA exhibit preferable removal of Pb 2+ through electrostatic interactions and chelation, whereas it captures MnO 4 − by means of electrostatic interactions. The experimental data are fitted the Langmuir isotherm model reasonably well, with the maximum adsorption capacity of 147 mg/g for Pb 2+ and of 156 mg/g for MnO 4 − . The adsorption rates of both Pb 2+ and MnO 4 − are found to follow the pseudo-second order kinetics. Furthermore, the NH 2 /MCM-41/NTAA adsorbent performs good recyclability and reusability for 5 cycles use. This study indicates a potential applicability of NH 2 /MCM-41/NTAA as new absorbents for effective simultaneous adsorption of hazardous metal ions and anions from wastewater.

Catalytic properties and acidity of modified MCM-41 mesoporous materials with low Si/Al ratio: heptane isomerisation

Directory of Open Access Journals (Sweden)

Ahmed Belhakem

2006-06-01

Full Text Available The catalytic properties and acidity of modified MCM-41 with a low Si/Al ratio and 0-95% NH4+ exchange were investigated. The samples were characterised by X-ray diffraction, scanning and transmission electron microscopy, and nitrogen adsorption. The acidity was studied by pyridine adsorption, temperature programmed desorption (TPD of ammonia, and infrared (IR spectroscopy. Adsorption of pyridine and IR spectroscopy indicated various types of Lewis and Brönsted acid sites. The density distribution of acid sites was determined by TPD. Both Lewis and Brönsted acid sites were found to be active in the heptane isomerisation. The presence of aluminium (low Si/Al combined to the ionic exchange between Na+ and NH4+ increases the acidity of MCM-41 materials. A close correlation between acidity and isomerisation was observed. Coke deposition, which reduces the activity, was also studied.

Catalytic Oxidation of Vanillyl Alcohol Using FeMCM-41 Nanoporous Tubular Reactor

Science.gov (United States)

Elamathi, P.; Kolli, Murali Krishna; Chandrasekar, G.

Iron containing nanoporous MCM-41 (FeMCM-41) with different Si/Fe ratios of 50, 100 and 150 was synthesized by hydrothermal synthesis process. The materials obtained from hydrothermal synthesis were characterized by various physico chemical techniques such as XRD, N2 adsorption, DR UV-vis, EPR and FTIR spectroscopy. XRD analyses of FeMCM-41 materials confirmed the presence of well-ordered crystalline structure. N2 isotherm of FeMCM-41 materials showed type IV adsorption isotherm. EPR and DR UV-vis analysis of FeMCM-41 samples indicates the presence of high tetrahedral coordination at the Si/Fe ratios of 100 and 150. The catalytic performance of FeMCM-41 nano tubular reactor was tested in the liquid phase oxidation of vanillyl alcohol into vanillin using H2O2 (50wt% in water). The reaction products were analyzed by gas chromatography in DB-5 capillary column with flame ionization detector. The products were confirmed by 1H NMR, 13C NMR and LC-Mass spectroscopy. The maximum conversion of vanillyl alcohol (85%) and selectivity towards vanillin (82%) were observed using the catalyst FeMCM-41(100) in 30min at 60∘C. The influence of reaction temperature, reaction time, reactants molar ratio, Si/Fe ratio and amount of catalyst were investigated.

Functionalized mesoporous silica materials for molsidomine adsorption: Thermodynamic study

International Nuclear Information System (INIS)

Alyoshina, Nonna A.; Parfenyuk, Elena V.

2013-01-01

A series of unmodified and organically modified mesoporous silica materials was prepared. The unmodified mesoporous silica was synthesized via sol–gel synthesis in the presence of D-glucose as pore-forming agent. The functionalized by phenyl, aminopropyl and mercaptopropyl groups silica materials were prepared via grafting. The fabricated adsorbent materials were characterized by Fourier transform infrared spectroscopy (FTIR) analysis, N 2 adsorption/desorption and elemental analysis methods. Then their adsorption properties for mesoionic dug molsidomine were investigated at 290–313 K and physiological pH value. Thermodynamic parameters of molsidomine adsorption on the synthesized materials have been calculated. The obtained results showed that the adsorption process of molsidomine on the phenyl modified silica is the most quantitatively and energetically favorable. The unmodified and mercaptopropyl modified silica materials exhibit significantly higher adsorption capacities and energies for molsidomine than the aminopropyl modified sample. The effects are discussed from the viewpoint of nature of specific interactions responsible for the adsorption. - Graphical abstract: Comparative analysis of the thermodynamic characteristics of molsidomine adsorption showed that the adsorption process on mesoporous silica materials is controlled by chemical nature of surface functional groups. Molsidomine adsorption on the phenyl modified silica is the most quantitatively and energetically favorable. Taking into account ambiguous nature of mesoionic compounds, it was found that molsidomine is rather aromatic than dipolar. Display Omitted - Highlights: • Unmodified and organically modified mesoporous silica materials were prepared. • Molsidomine adsorption on the silica materials was studied. • Phenyl modified silica shows the highest adsorption capacity and favorable energy. • Molsidomine exhibits the lowest affinity to aminopropyl modified silica

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.

The 11C-radioisotopic study of methanol conversion on V-MCM-41; the influence of methyl iodide on the transformation

International Nuclear Information System (INIS)

Sarkadi-Priboczki, E.; Szelecsenyi, F.; Kovacs, Z.; Solmaz, A.; Balci, S.; Dogu, T.

2007-01-01

Complete text of publication follows. The MCM-41 mesoporous material has Lewis and even Bronsted acid sites to produce dimethyl ether with some hydrocarbons, while over metal modified MCM-41 mostly formaldehyde and dimethoxy methane (i.e. methylal) or methyl formate are produced. In present experiments V incorporated basically mild acid sites of MCM-41 was prepared by low temperature direct synthesis. The V-MCM-41 has enough main active Lewis sites (by V-) to form formaldehyde and also light Bronsted acid sites to let the adsorbed formaldehyde eliminate and afterwards, with methanol, to form dimethoxy methane in nonoxidative environment. This V-MCM-41 has been tested by ethanol conversion in non-oxidative environments too and diethoxy methane as main product was detected. In present work the methanol conversion, as well as the methanol co-reaction with methyl iodide are studied from the same V-MCM-41 sample using 11 C-technique. The 11 C-labelled radioactive methanol has been already applied for determination of methanol conversion rates on Cu-modified MCM-41. The V-MCM-41 was prepared by direct hydrothermal synthesis method. The adsorption rate of 11 C-methanol and, after the reaction, the desorption rate of the remaining 11 C-derivatives on catalyst were continuously detected by gamma detectors. The derivatives were analyzed by radio-gas chromatography (gas chromatograph with FID coupled on-line with a radioactivity detector). Both dimethyl ether and hydrocarbon formation are also in slight degrees according to weak Lewis and Bronsted acidities. Since the conversion was carried out without added oxygen gas, only the frame oxygen can take part into catalysis. In presence of non-radioactive methyl iodide, the radioactive methanol is converted to radioactive methyl iodide on V-MCM-41. The radio-GC analysis confirmed that the iodide induced change of the reaction performance was reversible i.e. the radioactive methyl iodide was regenerated to non-radioactive methyl

Use of TiO{sub 2}/Cr-MCM-41 molecular sieve irradiated with visible light for the degradation of thiophene in the gas phase

Energy Technology Data Exchange (ETDEWEB)

Marques, Fabielle C.; Canela, Maria Cristina; Stumbo, Alexandre M. [Laboratorio de Ciencias Quimicas (LCQUI), Universidade Estadual do Norte Fluminense Darcy Ribeiro, Av. Alberto Lamego, 2000 Campos dos Goytacazes-RJ, CEP 28013-602 (Brazil)

2008-04-15

Photocatalytic processes using TiO{sub 2} and UV radiation to eliminate pollutants are not yet suitable for industrial facilities due to their high consumption of energy. Transition metals incorporated onto mesoporous MCM-41 molecular sieves impregnated with TiO{sub 2} constitute an alternative that allows the use of solar light. In this study, Cr-substituted MCM-41 were synthesized (Si/Cr = 100, 50 and {infinity}) and impregnated with TiO{sub 2} (10 and 20 wt.%). Raman results showed the formation of anatase. Electronic spectroscopy and EPR exposed the formation of trivalent chromium after impregnation with TiO{sub 2}, which is related to a Cr-TiO{sub 2} interaction. The synthesized photocatalysts, as well as TiO{sub 2} P25, were tested in the degradation of thiophene in gaseous phase. A test with UV lamp showed 100% of conversion for 20%TiO{sub 2}/Cr-MCM-41(100) and exceeded the activity of TiO{sub 2} P25, probably due to the higher dispersion of TiO{sub 2} on the surface of the molecular sieve. During tests using visible light and 20%TiO{sub 2}/Cr-MCM-41(50) higher conversions than those of 20%TiO{sub 2}/Cr-MCM-41(100) and TiO{sub 2} P25 were observed. These results indicate that chromium concentration is a key factor influencing the photocatalytic activity under visible light. (author)

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.

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

Science.gov (United States)

Marcilla, A; Gómez-Siurana, A; Berenguer, D; Martínez-Castellanos, I; Beltrán, M I

2015-01-01

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).

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.

Removal of Cr(VI from Aqueous Solutions Using mino-fuctionalized Nanoporous MCM-41

Directory of Open Access Journals (Sweden)

Farshid Ghorbani

2016-09-01

Full Text Available An amino-functionalized nanoporous material was prepared by grafting 3-aminopropyl trimethoxysilane (APTMS group onto MCM-41. The as-synthesized material was characterized by X-ray diffraction (XRD analysis, nitrogen adsorption-desorption measurements (BET, thermogravimetric analysis (TGA, and Fourier transform infrared spectrometry (FTIR to confirm the ordered mesoporous structure and the functionalization of the amino group. The NH2-MCM-41 thus obtained was employed as the sorbent to remove Cr(VI ions from aqueous solutions. The batch adsorption process was carried out to evaluate the effects of solution pH, adsorbent dosage, metal ion concentration, and temperature. Results revealed that removal efficiency increased to a maximum of 124 mg.g‒1 and metal uptake decreased (0.1 g.l‒1 with increasing sorbent dosage from 0.1 to 3.5 g.l‒1. A reverse trend was, however, observed with increasing Cr(VI concentration. It was also found that a pH equal to 3 was the optimum level for the removal of Cr(VI ions from aqueous solutions. Thermodynamic examinations revealed the strong dependence of the adsorption process on temperature such that adsorption capacity increased with increasing temperature, indicating the endothermic and spontaneous nature of the adsorption process.

Functionalized mesoporous silica materials for molsidomine adsorption: Thermodynamic study

Energy Technology Data Exchange (ETDEWEB)

Alyoshina, Nonna A.; Parfenyuk, Elena V., E-mail: evp@iscras.ru

2013-09-15

A series of unmodified and organically modified mesoporous silica materials was prepared. The unmodified mesoporous silica was synthesized via sol–gel synthesis in the presence of D-glucose as pore-forming agent. The functionalized by phenyl, aminopropyl and mercaptopropyl groups silica materials were prepared via grafting. The fabricated adsorbent materials were characterized by Fourier transform infrared spectroscopy (FTIR) analysis, N{sub 2} adsorption/desorption and elemental analysis methods. Then their adsorption properties for mesoionic dug molsidomine were investigated at 290–313 K and physiological pH value. Thermodynamic parameters of molsidomine adsorption on the synthesized materials have been calculated. The obtained results showed that the adsorption process of molsidomine on the phenyl modified silica is the most quantitatively and energetically favorable. The unmodified and mercaptopropyl modified silica materials exhibit significantly higher adsorption capacities and energies for molsidomine than the aminopropyl modified sample. The effects are discussed from the viewpoint of nature of specific interactions responsible for the adsorption. - Graphical abstract: Comparative analysis of the thermodynamic characteristics of molsidomine adsorption showed that the adsorption process on mesoporous silica materials is controlled by chemical nature of surface functional groups. Molsidomine adsorption on the phenyl modified silica is the most quantitatively and energetically favorable. Taking into account ambiguous nature of mesoionic compounds, it was found that molsidomine is rather aromatic than dipolar. Display Omitted - Highlights: • Unmodified and organically modified mesoporous silica materials were prepared. • Molsidomine adsorption on the silica materials was studied. • Phenyl modified silica shows the highest adsorption capacity and favorable energy. • Molsidomine exhibits the lowest affinity to aminopropyl modified silica.

Effect of template in MCM-41 on the adsorption of aniline from aqueous solution.

Science.gov (United States)

Yang, Xinxin; Guan, Qingxin; Li, Wei

2011-11-01

The effect of the surfactant template cetyltrimethylammonium bromide (CTAB) in MCM-41 on the adsorption of aniline was investigated. Various MCM-41 samples were prepared by controlling template removal using an extraction method. The samples were then used as adsorbents for the removal of aniline from aqueous solution. The results showed that the MCM-41 samples with the template partially removed (denoted as C-MCM-41) exhibited better adsorption performance than MCM-41 with the template completely removed (denoted as MCM-41). The reason for this difference may be that the C-MCM-41 samples had stronger hydrophobic properties and selectivity for aniline because of the presence of the template. The porosity and cationic sites generated by the template play an important role in the adsorption process. The optimal adsorbent with moderate template was achieved by changing the ratio of extractant; it has the potential for promising applications in the field of water pollution control. Copyright © 2011 Elsevier Ltd. All rights reserved.

Functionalisation of mesoporous materials for application as additives in high temperature PEM fuel cell membranes

Energy Technology Data Exchange (ETDEWEB)

Sharifi, Monir

2012-03-06

The presented thesis contains six original research articles dedicated to the preparation and characterization of organic-inorganic mesoporous materials as additives for polymer electroly1e membrane fuel cells (PEMFCs). The mesoporous materials Si-MCM-41 and benzene-PMO (periodic mesoporous organosilica) were chosen for the investigations. These materials were modified with functional groups for enhanced proton conductivity and water-keeping properties. In order to improve these materials Broenstedt acidic groups were introduced in the framework of mesoporous Si-MCM-41. Therefore, some silicium atoms in the framework were substituted by aluminium using different aluminium sources. Here NaAlO{sub 2} exhibits clearly the best results because the entire aluminium incorporated within the framework is tetragonally coordinated as observed by {sup 2}7AI MAS NMR. The increase of the proton conductivities results from an improved hydrophilicity, a decreased particle size, and newly introduced Broenstedt acidity in the mesoporous Al-MCM-41. However, mesoporous Si-MCM-41 materials functionalised by co-condensation with sulphonic acid groups exhibit the best results concerning proton conductivity, compared to those prepared by grafting. Hence, these materials where characterized in more detail by SANS and by MAS NMR measurements. The first one indicated that by co-condensation the entire inner pore surface is altered by functional groups which are, thus, distributed much more homogeneously than samples functionalised by grafting. This result explains the improved proton conductivities. Additionally, {sup 2}9Si NMR spectra proved that samples prepared by co-condensation lead to a successful and almost complete incorporation of mercaptopropyltrimethoxysilan (MPMS) into the mesoporous framework. Furthermore, it was shown by {sup 1}3C MAS NMR spectroscopy that the majority of the organic functional groups remained intact after H{sub 2}0{sub 2}-oxidation. However, proton

Sulfuric acid functional zirconium (or aluminum) incorporated mesoporous MCM-48 solid acid catalysts for alkylation of phenol with tert-butyl alcohol

International Nuclear Information System (INIS)

Jiang, Tingshun; Cheng, Jinlian; Liu, Wangping; Fu, Lie; Zhou, Xuping; Zhao, Qian; Yin, Hengbo

2014-01-01

Several zirconium (or aluminum) incorporated mesoporous MCM-48 solid acid catalysts (SO 4 2− /Zr-MCM-48 and SO 4 2− /Al-MCM-48) were prepared by the impregnation method and their physicochemical properties were characterized by means of XRD, FT-IR, TEM, NH 3 -TPD and N 2 physical adsorption. Also, the catalytic activities of these solid acid catalysts were evaluated by the alkylation of phenol with tert-butyl alcohol. The effect of weight hour space velocity (WHSV), reaction time and reaction temperature on catalytic properties was also studied. The results show that the SO 4 2− /Zr-MCM-48 and SO 4 2− /Al-MCM-48 still have good mesoporous structure and long range ordering. Compared with the Zr (or Al)–MCM-48 samples, SO 4 2− /Zr-MCM-48 and SO 4 2− /Al-MCM-48 solid acid catalysts have strong acidity and exhibit high activities in alkylation reaction of phenol with tert-butyl alcohol. The SO 4 2− /Zr-MCM-48-25 (molar ratio of Si/Zr=0.04) catalyst was found to be the most promising and gave the highest phenol conversion among all catalysts. A maximum phenol conversion of 91.6% with 4-tert-butyl phenol (4-TBP) selectivity of 81.8% was achieved when the molar ratio of tert-butyl alcohol:phenol is 2:1, reaction time is 2 h, the WHSV is 2 h −1 and the reaction temperature is 140 °C. - Highlights: • Sulfuric acid functional mesoporous solid acid catalysts were prepared via impregnation method. • The alkylation of phenol with tert-butyl alcohol was carried out over these solid acid catalysts. • The catalytic activity of SO 4 2− /Zr-MCM-48-25 catalyst is much higher than that of the others. • A maximum phenol conversion of 91.6% was achieved under optimum reaction conditions for SO 4 2− /Zr-MCM-48-25

Highly Aminated Mesoporous Silica Nanoparticles with Cubic Pore Structure

KAUST Repository

Suteewong, Teeraporn; Sai, Hiroaki; Cohen, Roy; Wang, Suntao; Bradbury, Michelle; Baird, Barbara; Gruner, Sol M.; Wiesner, Ulrich

2011-01-01

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.

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.

Metathesis of 2-pentene over Mo and W supported mesoporous molecular sieves MCM-41 and SBA-15

Czech Academy of Sciences Publication Activity Database

Ibrahim, M. A.; Akhtar, M. N.; Čejka, Jiří; Montanari, E.; Balcar, Hynek; Kubů, Martin; Al-Khattaf, S. S.

2017-01-01

Roč. 53, SEP 2017 (2017), s. 119-126 ISSN 1226-086X R&D Projects: GA ČR(CZ) GAP106/12/0189 Institutional support: RVO:61388955 Keywords : metathesis * MCM-41 * SBA-15 Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 4.421, year: 2016

Mechanism insight of pollutant degradation and bromate inhibition by Fe-Cu-MCM-41 catalyzed ozonation.

Science.gov (United States)

Chen, Weirui; Li, Xukai; Tang, Yiming; Zhou, Jialu; Wu, Dan; Wu, Yin; Li, Laisheng

2018-03-15

A flexible catalyst, Fe-Cu-MCM-41, was employed to enhance diclofenac (DCF) mineralization and inhibit bromate formation in catalytic ozonation process. Greater TOC removal was achieved in Fe-Cu-MCM-41/O 3 process (78%) than those in Fe-MCM-41/O 3 (65%), Cu-MCM-41/O 3 (73%) and sole ozonation (42%). But it was interesting that both Cu-MCM-41/O 3 and Fe-MCM-41/O 3 achieved 93% bromate inhibition efficiency, only 71% inhibition efficiency was observed in Fe-Cu-MCM-41/O 3 . Influence of pH, TBA/NaHSO 3 and detection of by-products were conducted to explore the mechanism. By Pyridine adsorption-IR and XPS, a relationship was found among activity of catalysts, Lewis acid sites and electron transfer effect between Fe (II/III) and Cu (I/II). Fe-Cu-MCM-41 promoted ozone decomposition to generate OH, which accounted for enhanced DCF mineralization. The consumption of aqueous O 3 also suppressed the oxidative of Br - and HBrO/Br - . More HBrO/BrO - accumulated in catalytic ozonation process and less bromate generated. Bromate formation in Fe-Cu-MCM-41/O 3 process was sensitive with pH value, the acidic condition was not favor for bromate formation. Both DCF mineralization and bromate inhibition were influenced by surface reaction. Moreover, Fe-Cu-MCM-41 showed excellent catalytic performance in suppressing the accumulation of carboxylic acid, especially for oxalic acid. Nearly no oxalic acid was detected during Fe-Cu-MCM-41/O 3 process. Copyright © 2017 Elsevier B.V. All rights reserved.

Comparative Study of Tributyltin Adsorption onto Mesoporous Silica Functionalized with Calix[4]arene, p-tert-Butylcalix[4]arene and p-Sulfonatocalix[4]arene

Directory of Open Access Journals (Sweden)

Sana Alahmadi

2014-04-01

Full Text Available The adsorption of tributyltin (TBT, onto three mesoporous silica adsorbents functionalized with calix[4]arene, p-tert-butylcalix[4]arene and p-sulfonatocalix[4]arene (MCM-TDI-C4, MCM-TDI-PC4 and MCM-TDI-C4S, respectively has been compared. Batch adsorption experiments were carried out and the effect of contact time, initial TBT concentration, pH and temperature were studied. The Koble–Corrigan isotherm was the most suitable for data fitting. Based on a Langmuir isotherm model, the maximum adsorption capacities were 12.1212, 16.4204 and 7.5757 mg/g for MCM-TDI-C4, MCM-TDI-PC4 and MCM-TDI-C4S, respectively. The larger uptake and stronger affinity of MCM-TDI-PC4 than MCM-TDI-C4 and MCM-TDI-C4S probably results from van der Waals interactions and the pore size distribution of MCM-TDI-PC4. Gibbs free energies for the three adsorption processes of TBT presented a negative value, reflecting that TBT/surface interactions are thermodynamic favorable and spontaneous. The interaction processes were accompanied by an increase of entropy value for MCM-TDI-C4 and MCM-TDI-C4S (43.7192 and 120.7609 J/mol K, respectively and a decrease for MCM-TDI-PC4 (−37.4704 J/mol K. It is obviously observed that MCM-TDI-PC4 spontaneously adsorbs TBT driven mainly by enthalpy change, while MCM-TDI-C4 and MCM-TDI-C4S do so driven mainly by entropy changes.

Comparative study of hydrogen storage on metal doped mesoporous materials

Science.gov (United States)

Carraro, P. M.; Sapag, K.; Oliva, M. I.; Eimer, G. A.

2018-06-01

The hydrogen adsorption capacity of mesoporous materials MCM-41 modified with Co, Fe, Ti, Mg and Ni at 77 K and 10 bar was investigated. Various techniques including XRD, N2 adsorption and DRUV-vis were employed for the materials characterization. The results showed that a low nickel loading on MCM-41 support promoted the presence of hydrogen-favorable sites, increasing the hydrogen storage capacity.

In Situ Growth of Mesoporous Silica with Drugs on Titanium Surface and Its Biomedical Applications.

Science.gov (United States)

Wan, Mimi; Zhang, Jin; Wang, Qi; Zhan, Shuyue; Chen, Xudong; Mao, Chun; Liu, Yuhong; Shen, Jian

2017-06-07

Mesoporous silica has been developed for the modification of titanium surfaces that are used as implant materials. Yet, the traditional modification methods failed to effectively construct mesoporous silica on the titanium surface evenly and firmly, in which the interaction between mesoporous silica and titanium was mainly physical. Here, in situ growth of mesoporous silica on a titanium surface was performed using a simple evaporation-induced self-assembly strategy. Meantime, in situ introduction of drugs (heparin and vancomycin) to mesoporous silica was also adopted to improve the drug-loading amount. Both the above-mentioned processes were completed at the same time. Transmission electron microscopy, N 2 adsorption-desorption isotherms, Fourier transform infrared spectroscopy, scanning electron microscopy, and water contact angle measurements were used to characterize the structure of the mesoporous silica film. Results indicated that the mesoporous silica film that in situ grew on the titanium surface was smooth, thin, transparent, and stable. Cytotoxicity, proliferation performance of osteoblast cells, and in vitro and in vivo studies of the antibacterial activity of the coating were tested. This is the first study to modify the titanium surface by the in situ growth of a mesoporous silica coating with two kinds of drugs. The stability of the mesoporous silica coating can be attributed to the chemical bonding between dopamine and silicon hydroxyl of the mesoporous silica coating, and the smooth surface of mesoporous silica is a result of the method of in situ growth. The large amount of drug-loading also could be ascribed to the in situ introduction of drugs during the synthetic process. The strategy proposed in this work will bring more possibilities for the preparation of advanced functional materials based on the combination of mesoporous structure and metallic materials.

Uranium adsorption studies on aminopropyl modified mesoporous sorbent (NH{sub 2}-MCM-41) using statistical design method

Energy Technology Data Exchange (ETDEWEB)

Sert, Senol, E-mail: senol.sert@ege.edu.t [Ege University, Institute of Nuclear Sciences, 35100 Bornova-Izmir (Turkey); Eral, Meral [Ege University, Institute of Nuclear Sciences, 35100 Bornova-Izmir (Turkey)

2010-11-30

MCM-41 has been synthesized and modified in order to graft amine groups on its surface. The modified NH{sub 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 UO{sub 2}{sup 2+} ions. The optimum values of the parameters determined were 4.2 for the initial pH, 60 {sup o}C for the temperature, 90 mg L{sup -1} for the initial concentration and 173 min for the shaking time using the response surface methodology. {Delta}H{sup o} and {Delta}S{sup o} were calculated from the slope and the intercept of plots of ln K{sub d} versus 1/T. The isotherm models, Langmuir, Freundlich, Dubinin-Radushkevich (D-R) have been studied to explain the adsorption characteristics.

NMR studies of organic liquids confined in mesoporous materials: (1) Pore size distribution and (2) Phase behaviour and dynamic studies in restricted geometry

International Nuclear Information System (INIS)

Foerland, Kjersti

2005-01-01

In the thesis NMR spectroscopy is used for studying liquids confined in various porous materials. In the first part, pore size distributions of mesoporous silicas and controlled pore glasses were determined by measuring the 1H NMR signal from the non-frozen fraction of the confined liquid as a function of temperature, using benzene, acetonitrile and HMDS as probe molecules. In the second part, the molecular dynamics of acetonitrile, hexamethyldisilane, cyclohexane and cyclopentane confined in mesoporous materials were studied as a function of temperature. 6 papers are included with titles: 1) Pore-size determination of mesoporous materials by 1H NMR spectroscopy. 2) Pore-size distribution in mesoporous materials as studied by 1H NMR. 3) Dynamic 1H and 2H NMR investigations of acetonitrile confined in porous silica. 4) NMR investigations of hexamethyldisilane confined in controlled pore glasses: Pore size distribution and molecular dynamics studies. 5) 1H and 2H NMR studies of cyclohexane nano crystals in controlled pore glasses. 6) 1H NMR relaxation and diffusion studies of cyclohexane and cyclopentane confined in MCM-41

NMR studies of organic liquids confined in mesoporous materials: (1) Pore size distribution and (2) Phase behaviour and dynamic studies in restricted geometry

Energy Technology Data Exchange (ETDEWEB)

Foerland, Kjersti

2005-07-01

In the thesis NMR spectroscopy is used for studying liquids confined in various porous materials. In the first part, pore size distributions of mesoporous silicas and controlled pore glasses were determined by measuring the 1H NMR signal from the non-frozen fraction of the confined liquid as a function of temperature, using benzene, acetonitrile and HMDS as probe molecules. In the second part, the molecular dynamics of acetonitrile, hexamethyldisilane, cyclohexane and cyclopentane confined in mesoporous materials were studied as a function of temperature. 6 papers are included with titles: 1) Pore-size determination of mesoporous materials by 1H NMR spectroscopy. 2) Pore-size distribution in mesoporous materials as studied by 1H NMR. 3) Dynamic 1H and 2H NMR investigations of acetonitrile confined in porous silica. 4) NMR investigations of hexamethyldisilane confined in controlled pore glasses: Pore size distribution and molecular dynamics studies. 5) 1H and 2H NMR studies of cyclohexane nano crystals in controlled pore glasses. 6) 1H NMR relaxation and diffusion studies of cyclohexane and cyclopentane confined in MCM-41.

Study of the influence of the silica source on the synthesis of the zeolite precursor MCM-22; Estudo da influencia da fonte de siilica na sintese do precursor zeolitico MCM-22

Energy Technology Data Exchange (ETDEWEB)

Barbosa, A.S.; Santos, E.R.F. dos; Leite, R.C.N.; Rodrigues, M.G.F., E-mail: antoniellybarbosa@yahoo.com.br [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais

2012-07-01

Zeolite MCM-22 precursors were synthesized under hydrothermal conditions in systems with hexamethyleneimine HMI as bulking agent (driver). Synthesis parameter, such as sources of silica (aerosil® and quartz) was modified to investigate the effects on the morphology and crystallization in precursor MCM-22 zeolite. The products were characterized by X-Ray Diffraction (XRD), Energy Dispersive Spectroscopy (EDX) and Scanning Electron Microscopy (SEM). According to, the X-ray diffraction showed the same characteristic peaks of zeolite MCM-22. It was found that the parameter in this work of synthesis, silica source, affects the hydrothermal synthesis of zeolite MCM-22 precursor. This can be evidenced by the different morphologies found using the different sources of silica. (author)

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.

Facile synthesis of mesoporous silica sublayer with hierarchical pore structure on ceramic membrane using anionic polyelectrolyte.

Science.gov (United States)

Kang, Taewook; Oh, Seogil; Kim, Honggon; Yi, Jongheop

2005-06-21

A facile method for introducing mesoporous silica sublayer onto the surface of a ceramic membrane for use in liquid-phase separation is described. To reduce the electrostatic repulsion between the mesoporous silica sol and the ceramic membrane in highly acidic conditions (pH ceramic membrane, as confirmed by experimental titration data. Consistent with the titration results, the amount of mesoporous silica particles on the surface of the ceramic membrane was low, in the absence of PSS- treatment, whereas mesoporous silica sublayer with hierarchical pore structure was produced, when 1 wt % PSS- was used. The results show that mesoporous silica grows in the confined surface, eventually forming a multistacked surface architecture. The mesoporous silica sublayer contained uniform, ordered (P6 mm) mesopores of ca. 7.5 nm from mesoporous silica as well as macropores ( approximately mum) from interparticle voids, as evidenced by transmission electron microscopy and scanning electron microscopy analyses. The morphologies of the supported mesoporous silica could be manipulated, thus permitting the generation of uniform needlelike forms or uniform spheroid particles by varying the concentration of PSS-.

Dendritic silica nanomaterials (KCC-1) with fibrous pore structure possess high DNA adsorption capacity and effectively deliver genes in vitro.

Science.gov (United States)

Huang, Xiaoxi; Tao, Zhimin; Praskavich, John C; Goswami, Anandarup; Al-Sharab, Jafar F; Minko, Tamara; Polshettiwar, Vivek; Asefa, Tewodros

2014-09-16

The pore size and pore structure of nanoporous materials can affect the materials' physical properties, as well as potential applications in different areas, including catalysis, drug delivery, and biomolecular therapeutics. KCC-1, one of the newest members of silica nanomaterials, possesses fibrous, large pore, dendritic pore networks with wide pore entrances, large pore size distribution, spacious pore volume and large surface area--structural features that are conducive for adsorption and release of large guest molecules and biomacromolecules (e.g., proteins and DNAs). Here, we report the results of our comparative studies of adsorption of salmon DNA in a series of KCC-1-based nanomaterials that are functionalized with different organoamine groups on different parts of their surfaces (channel walls, external surfaces or both). For comparison the results of our studies of adsorption of salmon DNA in similarly functionalized, MCM-41 mesoporous silica nanomaterials with cylindrical pores, some of the most studied silica nanomaterials for drug/gene delivery, are also included. Our results indicate that, despite their relatively lower specific surface area, the KCC-1-based nanomaterials show high adsorption capacity for DNA than the corresponding MCM-41-based nanomaterials, most likely because of KCC-1's large pores, wide pore mouths, fibrous pore network, and thereby more accessible and amenable structure for DNA molecules to diffuse through. Conversely, the MCM-41-based nanomaterials adsorb much less DNA, presumably because their outer surfaces/cylindrical channel pore entrances can get blocked by the DNA molecules, making the inner parts of the materials inaccessible. Moreover, experiments involving fluorescent dye-tagged DNAs suggest that the amine-grafted KCC-1 materials are better suited for delivering the DNAs adsorbed on their surfaces into cellular environments than their MCM-41 counterparts. Finally, cellular toxicity tests show that the KCC-1-based

A controlled release of ibuprofen by systematically tailoring the morphology of mesoporous silica materials

International Nuclear Information System (INIS)

Qu Fengyu; Zhu Guangshan; Lin Huiming; Zhang Weiwei; Sun Jinyu; Li Shougui; Qiu Shilun

2006-01-01

A series of mesoporous silica materials with similar pore sizes, different morphologies and variable pore geometries were prepared systematically. In order to control drug release, ibuprofen was employed as a model drug and the influence of morphology and pore geometry of mesoporous silica on drug release profiles was extensively studied. The mesoporous silica and drug-loaded samples were characterized by X-ray diffraction, Fourier transform IR spectroscopy, N 2 adsorption and desorption, scanning electron microscopy, and transmission electron microscopy. It was found that the drug-loading amount was directly correlated to the Brunauer-Emmett-Teller surface area, pore geometry, and pore volume; while the drug release profiles could be controlled by tailoring the morphologies of mesoporous silica carriers. - Graphical abstract: The release of ibuprofen is controlled by tailoring the morphologies of mesoporous silica. The mesoporous silica and drug-loaded samples are characterized by powder X-ray diffraction, Fourier transform IR spectroscopy, N 2 adsorption and desorption, scanning electron microscopy, and transmission electron microscopy. The drug-loading amount is directly correlated to the Brunauer-Emmett-Teller surface area, pore geometry, and pore volume; while the drug release profiles can be controlled by tailoring the morphologies of mesoporous silica carriers

Rod-shaped silica particles derivatized with elongated silver nanoparticles immobilized within mesopores

Energy Technology Data Exchange (ETDEWEB)

Mnasri, Najib [Institut Charles Gerhardt de Montpellier, CNRS UMR 5253, Université Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5 (France); Materials, Environment and Energy Laboratory (UR14ES26), Faculty of Science, University of Gafsa, 2112 Gafsa (Tunisia); Charnay, Clarence; Ménorval, Louis-Charles de [Institut Charles Gerhardt de Montpellier, CNRS UMR 5253, Université Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5 (France); Elaloui, Elimame [Materials, Environment and Energy Laboratory (UR14ES26), Faculty of Science, University of Gafsa, 2112 Gafsa (Tunisia); Zajac, Jerzy, E-mail: jerzy.zajac@umontpellier.fr [Institut Charles Gerhardt de Montpellier, CNRS UMR 5253, Université Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5 (France)

2016-11-15

Silver-derivatized silica particles possessing a non-spherical morphology and surface plasmon resonance properties have been achieved. Nanometer-sized silica rods with uniformly sized mesopore channels were prepared first making use of alkyltrimethyl ammonium surfactants as porogens and the 1:0.10 tetraethyl orthosilicate (TEOS) : 3-aminopropyltriethoxysilane (APTES) mixture as a silicon source. Silica rods were subsequently functionalized by introducing elongated silver nanoparticles within the intra-particle mesopores thanks to the AgNO{sub 3} reduction procedure based on the action of hemiaminal groups previously located on the mesopore walls. The textural and structural features of the samples were inferred from the combined characterization studies including SEM and TEM microscopy, nitrogen adsorption-desorption at 77 K, powder XRD in the small- and wide-angle region, as well as UV–visible spectroscopy. {sup 129}Xe NMR spectroscopy appeared particularly useful to obtain a correct information about the porous structure of rod-shaped silica particles and the silver incorporation within their intra-particle mesopores. - Highlights: • Mesoporous monodisperse submicron-sized silica rods were achieved. • Silver nanoparticles were located lengthwise within the intra-particle mesopores. • Textural and plasmonic properties of particles studied by {sup 129}Xe NMR and UV–Vis.

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 titanium atoms are grafted on the wall surface of the MCM-41 by four-fold coordination. The four-fold coordinated titanium species are mainly grafted by two or one -O-Si-O- bridges on the MCM-41, resulting in so-called bipodal or monopodal titanium centres in partially polymerised states. The ratio...... of monopodal to bipodal titanium increases with the increase in Ti-content. These partially polymerised titanium species considered as catalytic active centres have high activity and selectivity in the epoxidation reaction. The used Ti-grafted MCM-41 samples were regenerated by heating in nitrogen or air...

The Formation of Metal (M=Co(II), Ni(II), and Cu(II)) Complexes by Aminosilanes Immobilized within Mesoporous Molecular Sieves

International Nuclear Information System (INIS)

Park, Dong Ho; Park, Sung Soo; Choe, Sang Joon

1999-01-01

The immobilization of APTMS(3-(2-aminoethylamino)propyltrimethoxysilane) and AAPTMS(3-(2-(2-aminoethyl) aminoethylamino)propyltrimethoxysilane) on the surface of high quality mesoporous molecular sieves MCM-41 and MCM-48 have been confirmed by F.T.-IR spectroscopy, Raman spectroscopy, 29 Si solid state NMR, and a surface polarity measurement using Reichardt's dye. The formation of metal (Co(II), Ni(II), and Cu(II)) complexes by immobilized aminosilanes have been investigated by photoacoustic spectroscopy(PAS). The assignment of UV-Vis. PAS bands makes it possible to identify the structure of metal complexes within mesoporous molecular sieves. Co(II) ion may be coordinated mainly in a tetrahedral symmetry by two APTMS onto MCM-41, and in an octahedral one by two AAPTMS. Both Ni(II) and Cu(II) coordinated by aminosilanes within MCM-41 form possibly the octahedral complexes such as [Ni(APTMS) 2 (H 2 O) 2 ] 2+ , [Ni(AAPTMS) 2 ] 2+ , [Cu(APTMS) 2 (H 2 O) 2 ] 2+ , and [Cu(AAPTMS)(H 2 O) 3 ] 2+ , respectively. The PAS band shapes of complexes onto MCM-48 are similar to those of corresponding MCM-41 with the variation of PAS intensity. Most of metal ion(II) within MCM-41 and MCM-48 are coordinated by aminosilanes without the impregnation on the surface

Sulfuric acid functional zirconium (or aluminum) incorporated mesoporous MCM-48 solid acid catalysts for alkylation of phenol with tert-butyl alcohol

Energy Technology Data Exchange (ETDEWEB)

Jiang, Tingshun, E-mail: tshjiang@mail.ujs.edu.cn; Cheng, Jinlian; Liu, Wangping; Fu, Lie; Zhou, Xuping; Zhao, Qian; Yin, Hengbo

2014-10-15

Several zirconium (or aluminum) incorporated mesoporous MCM-48 solid acid catalysts (SO{sub 4}{sup 2−}/Zr-MCM-48 and SO{sub 4}{sup 2−}/Al-MCM-48) were prepared by the impregnation method and their physicochemical properties were characterized by means of XRD, FT-IR, TEM, NH{sub 3}-TPD and N{sub 2} physical adsorption. Also, the catalytic activities of these solid acid catalysts were evaluated by the alkylation of phenol with tert-butyl alcohol. The effect of weight hour space velocity (WHSV), reaction time and reaction temperature on catalytic properties was also studied. The results show that the SO{sub 4}{sup 2−}/Zr-MCM-48 and SO{sub 4}{sup 2−}/Al-MCM-48 still have good mesoporous structure and long range ordering. Compared with the Zr (or Al)–MCM-48 samples, SO{sub 4}{sup 2−}/Zr-MCM-48 and SO{sub 4}{sup 2−}/Al-MCM-48 solid acid catalysts have strong acidity and exhibit high activities in alkylation reaction of phenol with tert-butyl alcohol. The SO{sub 4}{sup 2−}/Zr-MCM-48-25 (molar ratio of Si/Zr=0.04) catalyst was found to be the most promising and gave the highest phenol conversion among all catalysts. A maximum phenol conversion of 91.6% with 4-tert-butyl phenol (4-TBP) selectivity of 81.8% was achieved when the molar ratio of tert-butyl alcohol:phenol is 2:1, reaction time is 2 h, the WHSV is 2 h{sup −1} and the reaction temperature is 140 °C. - Highlights: • Sulfuric acid functional mesoporous solid acid catalysts were prepared via impregnation method. • The alkylation of phenol with tert-butyl alcohol was carried out over these solid acid catalysts. • The catalytic activity of SO{sub 4}{sup 2−}/Zr-MCM-48-25 catalyst is much higher than that of the others. • A maximum phenol conversion of 91.6% was achieved under optimum reaction conditions for SO{sub 4}{sup 2−}/Zr-MCM-48-25.

Controlled synthesis of the tricontinuous mesoporous material IBN-9 and its carbon and platinum derivatives

KAUST Repository

Zhao, Yunfeng

2011-08-23

Controlled synthesis of mesoporous materials with ultracomplicated pore configurations is of great importance for both fundamental research of nanostructures and the development of novel applications. IBN-9, which is the only tricontinuous mesoporous silica with three sets of interpenetrating three-dimensional channel systems, appears to be an excellent model mesophase for such study. The extensive study of synthesis space diagrams proves mesophase transition among the cylindrical MCM-41, tricontinuous IBN-9 and bicontinuous MCM-48, and also allows a more precise control of phase-pure synthesis. On the other hand, rational design of structure-directing agents offers a possibility to extend the synthesis conditions of IBN-9, as well as tailor its pore size. Moreover, an unprecedented helical structure consisting of twisted 3-fold interwoven mesoporous channels is reported here for the first time. The unique tricontinuous mesostructure of IBN-9 has been well-replicated by other functional materials (e.g., carbon and platinum) via a "hard- templating" synthesis route. The obtained carbon material possesses large surface area (∼1900 m2/g), high pore volume (1.56 cm 3/g), and remarkable gas adsorption capability at both cryogenic temperatures and room temperature. The platinum material has an ordered mesostructure composed of highly oriented nanocrystals. © 2011 American Chemical Society.

Catalytic Activity and Photophysical Properties of Biomolecules Immobilized on Mesoporous Silica

DEFF Research Database (Denmark)

Ikemoto, Hideki

Mesoporous silicas, based on Santa Barbara Amorphous-15 (SBA-15), with different morphology, structure, pore size and functional groups have been synthesized. Two metalloenzymes and a photosynthetic membrane protein were immobilized on or confined in the pores of the mesoporous silicas to prepare...

Silica-supported, single-site titanium catalysts for olefin epoxidation. A molecular precursor strategy for control of catalyst structure.

Science.gov (United States)

Jarupatrakorn, Jonggol; Don Tilley, T

2002-07-17

A molecular precursor approach involving simple grafting procedures was used to produce site-isolated titanium-supported epoxidation catalysts of high activity and selectivity. The tris(tert-butoxy)siloxy titanium complexes Ti[OSi(O(t)Bu)(3)](4) (TiSi4), ((i)PrO)Ti[OSi(O(t)Bu)(3)](3) (TiSi3), and ((t)BuO)(3)TiOSi(O(t)Bu)(3) (TiSi) react with the hydroxyl groups of amorphous Aerosil, mesoporous MCM-41, and SBA-15 via loss of HO(t)Bu and/or HOSi(O(t)Bu)(3) and introduction of titanium species onto the silica surface. Powder X-ray diffraction, nitrogen adsorption/desorption, infrared, and diffuse reflectance ultraviolet spectroscopies were used to investigate the structures and chemical natures of the surface-bound titanium species. The titanium species exist mainly in isolated, tetrahedral coordination environments. Increasing the number of siloxide ligands in the molecular precursor decreases the amount of titanium that can be introduced this way, but also enhances the catalytic activity and selectivity for the epoxidation of cyclohexene with cumene hydroperoxide as oxidant. In addition, the high surface area mesoporous silicas (MCM-41 and SBA-15) are more effective than amorphous silica as supports for these catalysts. Supporting TiSi3 on the SBA-15 affords highly active cyclohexene epoxidation catalysts (0.25-1.77 wt % Ti loading) that provide turnover frequencies (TOFs) of 500-1500 h(-1) after 1 h (TOFs are reduced by about half after calcination). These results demonstrate that oxygen-rich siloxide complexes of titanium are useful as precursors to supported epoxidation catalysts.

Adsorption of heavy metals on amine-functionalized MCM-48

Science.gov (United States)

Taba, P.; Budi, P.; Puspitasari, A. Y.

2017-04-01

The ordered mesoporous silica with cubic structure, MCM-48 was synthesized by post-synthesis under basic media using colloidal silica, cetyltrimethylammonium bromide, and Triton X-100. The modified material, NH2-MCM-48 was prepared using 3-aminopropyl trimetoxysilane (3-APTMS). X-ray diffraction and FT-IR were used to characterize the samples. The modified material was utilized for adsorption of Cu2+and Mn2+ from aqueous solution. Parameters used for studying the adsorption process were pH, time of contact, and the initial concentrations of Cu2+ and Mn2+ ions. Desorption of ions from the adsorbent was also studied using several desorbing agents. The pseudo-second order was found to be the kinetic order for the metals adsorption. The adsorption of Cu2+ and Mn2+ on NH2-MCM-48 was fixed by the Langmuir model better than the Freundlich model with the capacity of 0.52 and 0.80 mmol g-1 for Cu2+ and Mn2+, respectively. The best desorbing agents for removing the adsorbed Cu2+ and Mn2+ from the adsorbent were 1 M HNO3 and 1 M HC1, respectively.

A Clean, Mild, and Efficient Preparation of Aryl 14H-benzo[a,j]xanthene leuco-dye Derivatives Via Nanocatalytic MCM-41-SO3H Under Ultrasonic Irradiation in Aqueous Media.

Science.gov (United States)

Fathollahi, Mostafa; Rostamizadeh, Shahnaz; Amani, Ali M

2018-01-01

The present study has developed an efficient and eco-friendly protocol for the synthesis of aryl-14-H-dibenzo[a,j] xanthenes through a one-pot condensation reaction of 2-naphthol and arylaldehydes in aqueous media using the nanocatalytic MCM-41-SO3H under ultrasonic illumination. Using SEM and XRD analyses, MCM-41-SO3H nanoparticles were characterized. Therefore, for high magnification, taking the SEM image, the mesoporous surface of MCM-41-SO3H nanoparticles coated with gold for 2 minutes was characterized. Moreover, at a scan rate of 0.02° (2θ)/sec, XRD analysis from 1.5° (2θ) to 10.0° (2θ) was performed. For our considered sample, some well-ordered XRD patterns with one main peak as well as three minor peaks equal to those of MCM-41 materials were observed. The suggested route demonstrates very promising properties like higher yields, decrease in the time of reaction (5-10 min), mild and straightforward conditions, low level of toxicity, and inclusion of a cost-efficient and ecofriendly catalyst having considerable reusability. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

[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.

Mesoporous silica nanoparticles as vectors for gene therapy

Energy Technology Data Exchange (ETDEWEB)

Crapina, Laura Cipriano; Bizeto, Marcos, E-mail: lauracrapina@hotmail.com [Universidade Federal de Sao Paulo (UNIFESP), SP (Brazil)

2016-07-01

Full text: Mesoporous silica nanoparticles present unique physical-chemical properties, such as high surface area, tunable pore size, easy surface chemical modification, good biocompatibility and low toxicology. Those properties make this class of inorganic materials promising for several potential applications in the biomedical field. This work seeks to develop mesoporous silica nanoparticles with characteristics suitable to the transport of nucleic acids, such as plasmid DNA and microRNA, with the aim of substituting viral vectors in gene therapy. A successful nanocarrier must have positive charge at physiological conditions and pore diameter larger than 30 Å. The mesoporous silica was synthesized according to the method described by Bein and collaborators [1]. Based on a cocondensation synthetic route, positively charged nanoparticles were obtained through the insertion of N-3-(trimethoxysilyl)propyldiethylenetriamine in the silica walls. Pore expansion was achieved through the incorporation of 1,2,4- trimethylbenzene into the hexadecyltrimethylammonium micellar aggregates, which are a structure-directing agent for the mesopores. The resulting nanoparticles were characterized by DLS, ζ potential, XRD, FTIR, SEM, TEM, TGA and elemental analysis. In addition, the capability of nucleic acid adsorption was tested and confirmed by gel electrophoresis. Discovery of a non-viral therapeutic agent would aid the viability of gene therapy, which is a treatment for chronic ischemia, metabolic and genetic disorders. Reference: [1] K. Moeller, J. Kobler, T. Bein, Journal of Materials Chemistry, 17, 624-631, (2007). (author)

Synthesis of cerium oxide catalysts supported on MCM-41 molecular sieve; Sintese de catalisadores de oxido de cerio suportados na peneira molecular MCM-41

Energy Technology Data Exchange (ETDEWEB)

Souza, E.L.S.; Barros, T.R.B.; Sousa, B.V. de, E-mail: emylle.souza@gmail.com [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Engenharia Quimica

2016-07-01

Porous materials have been widely studied as catalysts and catalyst support. The MCM-41 structure is the one that has been most studied because of its application possibilities in chemical processes. This work aimed to obtain and characterize cerium oxide catalysts supported on MCM-41 molecular sieve. The molecular sieve was synthesized by the conventional method with the following molar composition: 1 SiO2: 0.30 CTABr: NH3 11: 144 H2O. Then, 25% w/w cerium was incorporated into the MCM-41 using the wet impregnation process and the material obtained was activated by calcination. From the XRD patterns was confirmed the structure of the molecular sieve, and were identified the cerium oxide phases in its structure. The textural catalysts characteristics were investigated by isotherms of N2 adsorption/desorption (BET method). (author)

Textural mesoporosity and the catalytic activity of mesoporous molecular sieves with wormhole framework structures

International Nuclear Information System (INIS)

Pauly, T.R.; Liu, Y.; Pinnavaia, T.J.; Billinge, S.J.L.; Rieker, T.P.

1999-01-01

Three different water-alcohol cosolvent systems were used to assemble mesoporous molecular sieve silicas with wormhole framework structures (previously denoted HMS silicas) from an electrically neutral amine surfactant (Sdegree) and a silicon alkoxide precursor (Idegree). The fundamental particle size and associated textural (interparticle) porosity of the disordered structures were correlated with the solubility of the surfactant in the water-alcohol cosolvents used for the SdegreeIdegree assembly process. Polar cosolvents containing relatively low volume fractions of C n H 2n+1 OH alcohols (n = 1--3) gave heterogeneous surfactant emulsions that assembled intergrown aggregates of small primary particles with high textural pore volumes (designated HMS-HTx). Conversely, three-dimensional, monolithic particles with little or no textural porosity (designated HMS-LTx) were formed from homogeneous surfactant solutions in lower polarity cosolvents. Aluminum substituted AL-HMS-HTx analogues with high textural porosity and improved framework accessibility also were shown to be much more efficient catalysts than AL-HMS-LTx or monolithic forms of hexagonal AL-MCM-41 for the sterically demanding condensed phase alkylation of 2,4-di-tert-butylphenol with cinnamyl alcohol. Transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) studies verified the textural differences between wormhole HMS and electrostatically assembled hexagonal MCM-41 and SBA-3 molecular sieves. Power law fits to the scattering data indicated a surface fractal (D s = 2.76) for HMS-HTx, consistent with rough surfaces. A second power law at lower-q indicated the formation of a mass fractal (D m = 1.83) consistent with branching of small fundamental particles. Hexagonal MCM-41 and SBA-3 silicas, on the other hand, exhibited scattering properties consistent with moderately rough surfaces (D s = 2.35 and 2.22, respectively) and large particle diameters (much g t1 micro m). HMS-LTx silicas