Hexagonal P6mm Research Articles

One-dimensionally oriented self-assembly of ordered mesoporous nanofibers featuring tailorable mesophases via kinetic control

One-dimensional (1D) nanomaterials have sparked widespread research interest owing to their fascinating physicochemical properties, however, the direct self-assembly of 1D porous nanomaterials and control over their porosity still presents a grand challenge. Herein, we report a monomicelle oriented self-assembly approach to fabricate 1D mesoporous nanostructures with uniform diameter, high aspect ratio and ordered mesostructure. This strategy features the introduction of hexamethylenetetramine as a curing agent, which can subtly control the monomicelle self-assembly kinetics, thus enabling formation of high-quality 1D ordered mesostructures. Meanwhile, the micellar structure can be precisely manipulated by changing the reactant stoichiometric ratio, resulting in tailorable mesophases from 3D cubic (Im-3m) to 2D hexagonal (p6mm) symmetries. More interestingly, the resultant mesoporous nanofibers can be assembled into 3D hierarchical cryogels on a large scale. The 1D nanoscale of the mesoporous nanofibers, in combination with small diameter (~65 nm), high aspect ratio (~154), large surface area (~452 m2 g−1), and 3D open mesopores (~6 nm), endows them with excellent performances for sodium ion storage and water purification. Our methodology opens up an exciting way to develop next-generation ordered mesoporous materials for various applications.

Synthesis of spherical amine-functionalized silica molecular sieve and application as selective adsorbents for aromatic hydrocarbons analysis

In this work, spherical amine-functionalized mesoporous silica (Sp-Amino-Si) molecular sieve was fabricated by an acid hydrothermal method using 3-aminopropyltriethoxysilane as a modifier and toluene as the solvent. The results of scanning electron microscopy, Barrett-Joyner-Halenda pore size distribution, Fourier transform-infrared spectroscopy, and low-angle X-ray diffraction patterns revealed that the Sp-Amino-Si was monodispersed microspheres with uniform and controllable pore sizes sharing two-dimensional hexagonal P6mm symmetry and a large number of amino groups. The Sp-Amino-Si molecular sieve was verified to be suitable for the selective separation of aromatic hydrocarbons (AMHs) containing two fused benzene rings among other compounds from environmental water matrix. Under the optimized conditions, the Sp-Amino-Si exhibited much higher adsorption efficiency for AMHs (above 88.19%), comparing to the original SBA-15 (below 44.52%). The maximum adsorption capacities for naphthalene, methyl naphthalene, 2-methyl naphthalene, and acenaphthene were 477.1, 1006.5, 893.3, and 1253.2 µg·g−1, respectively. The high selectivity of Sp-Amino-Si for the four AMHs attributed to the size sieving and p-π interactions between the lone pair electrons of amine groups and the π-electrons in AMHs molecules. The Sp-Amino-Si based solid-phase extraction coupled with high performance liquid chromatography detection method was constructed for the analysis of the four AMHs, and the recoveries of spiked AMHs ranged from 89.67% to 112.74% with a relative standard deviation lower than 5.75%. This study provides some inspiration and a reliable method for AMHs separation, removal, and analysis.

Stepwise Monomicelle Assembly for Highly Ordered Mesoporous TiO2 Membranes with Precisely Tailored Mesophase and Porosity.

Mesoporous materials with crystalline frameworks have been acknowledged as very attractive materials in various applications. Nevertheless, due to the cracking issue during crystallization and incompatible hydrolysis and assembly, the precise control for crystalline mesoscale membranes is quite infertile. Herein, we presented an ingenious stepwise monomicelle assembly route for the syntheses of highly ordered mesoporous crystalline TiO2 membranes with delicately controlled mesophase, mesoporosity, and thickness. Such a process involves the preparation of monomicelle hydrogels and follows self-assembly by stepwise solvent evaporation, which enables the sensitive hydrolysis of TiO2 oligomers and dilatory micelle assembly to be united. In consequence, the fabricated mesoporous TiO2 membranes exhibit a broad flexibility, including tunable ordered mesophases (worm-like, hexagonal p6mm to body-centered cubic Im3̅m), controlled mesopore sizes (3.0-8.0 nm), and anatase grain sizes (2.3-8.4 nm). Besides, such mesostructured crystalline TiO2 membranes can be extended to diverse substrates (Ti, Ag, Si, FTO) with tailored thickness. The great mesoporosity of the in situ fabricated mesoscopic membranes also affords excellent pseudocapacitive behavior for sodium ion storage. This study underscores a novel pathway for balancing the interaction of precursors and micelles, which could have implications for synthesizing crystalline mesostructures in higher controllability.

Architecture of Nanoantioxidant Based on Mesoporous Organosilica Trp-Met-PMO with Dipeptide Skeleton.

A nanoantioxidant of mesoporous organosilica (Trp-Met-PMO) based on the framework of tryptophan-methionine dipeptide was first designed and constructed by condensation between self-created dipeptide organosilica precursor (Trp-Met-Si) and tetraethyl orthosilicate (TEOS) in alkaline conditions under the template hexadecyl trimethyl ammonium bromide (CTAB). Trp-Met-Si was prepared by the reaction between dipeptide Trp-Met and conventional organosilicon coupling agent isocyanatopropyltriethoxysilane (IPTES) via a multiple-step reaction method. The material Trp-Met-PMO was confirmed by XRD, FT-IR and N2 adsorption-desorption analysis. The material Trp-Met-5-PMO with low amounts of organosilica precursor remained a mesoporous material with well-ordered 2D hexagonal (P6mm) structure. With increasing amounts of organosilica precursor, a mesoporous structure was still formed, as shown in the material Trp-Met-100-PMO with the highest amounts of organosilica precursor. Moreover, pore size distribution, surface area and porosity of Trp-Met-PMO are regulated with different amounts of organosilica precursor Trp-Met-Si. The antioxidant activity of Trp-Met-PMO was evaluated by ABTS free radical-scavenging assay. The results showed that antioxidant activity was largely enhanced with increasing contents of organosilica precusor Trp-Met-Si in the skeleton. The material Trp-Met-40-PMO exhibited maximum scavenging capacity of ABTS free radicals, the inhibition percent was 5.88%. This study provides a design strategy for nanoantioxidant by immobilizing short peptides within the porous framework of mesoporous material.

Insight into the role of anions in the formation of mesoporous silicates

Cationic surfactants can form micellar structures in solution and the condensation of silicate around these micellar structures results in the inorganic/organic mesostructured composites. Anions other than silicates in the solution were believed to be located closely to the headgroup of the cationic surfactant micelle and thus affected the effective headgroup area, a component of the surfactant packing parameter g (g = V/a0l, where V is the chain volume, a0 is the effective headgroup area, and l is the chain length). In the presence of H2SO4, HCl, HBr, and HNO3, the surfactant cetyltriethylammonium bromide (CTEABr) directed the well-ordered mesophases of three-dimensional (3D) hexagonal P63/mmc, cubic Pm3‾n, 2D hexagonal p6mm, and cubic Ia3‾d, respectively. The diversity of the mesophases from CTEABr was attributed to the anion tuning of the effective headgroup area of CTEA+ in surfactant packing parameter g by closely located anions of SO42−, Cl−, Br−, and NO3− with various radii and hydratability. In this work, we discovered that part of Cl−, Br−, and NO3− can penetrate into the micellar system of CTEA+, which may increase the chain volume V of CTEA+ to some degree. The distance of anions to the center of the micelle, determined by the liquid 1H NMR analyses, was in the order of SO42− > Cl− > Br− > NO3−, which is consistent with the Hofmeister series. The deeper penetration of anions into the micelle may lead to the larger chain volume V and surfactant packing parameter g. Such insight into the location of anions in micellar system provided us a new picture on the formation mechanism of mesoporous silica and other mesostructured materials in solution.

A Chemosensor of 1,8-Dihydroxyanthraquinone PMOs Prepared in a Ternary Deep Eutectic Solvent for the Sensitive Detection of Cu2.

A novel type of organic–inorganic hybrid periodic mesoporous materials based on 1,8-dihydroxyanthraquinone (DHAQ-PMOs) was synthesized in a ternary deep eutectic solvent (DES). In the process of the material synthesis, an organosiloxane precursor (DHAQ-Si) and tetraethylorthosilicate (TEOS) were used as the mixed Si source, and cetyltrimethylammonium bromide (CTAB) was used as the structure directing agent. The DES formed by choline chloride (ChCl), urea (U), and ethylene glycol (EG) was used as a green solvent. The water needed for the hydrolysis of DHAQ-Si and TEOS was provided from free water in the sodium hydroxide solution. As characterized by small-angle X-ray scattering, nitrogen adsorption/desorption isotherms, and high-resolution transmission electron microscopy, the obtained mesoporous materials exhibit a two-dimensional hexagonal (P6mm) structure. DHAQ possesses double fluorescence emission peaks at ca. 520 and 580 nm due to the effect of the excited-state intramolecular proton transfer (ESIPT). For DHAQ-PMOs, the silica framework can provide a rigid environment that makes the fluorescence properties more stable and the fluorescence emission peak appears to red-shift obviously. The DHAQ-PMOs have high selectivity and sensitivity in a wide pH range that can be used to detect Cu2+, and the limit of detection (LOD) is as low as 2.39 × 10–9 M. Fluorescence polarization experiments, high-resolution mass spectrometry, and Fourier transform infrared spectroscopy were used to study the coordination interaction between DHAQ and Cu2+. The density functional theory (DFT) was used to further prove the coordination ability and interaction between DHAQ and Cu2+. XPS spectra were also done to prove the coordination of DHAQ and DHAQ-PMO-10 with Cu2+. In addition, confocal fluorescence microscope images exhibit that DHAQ-PMOs can detect Cu2+ in living cells. The results show that DHAQ-PMOs have great application potential as a sensor for the detection of Cu2+.

Understanding Pore Surface Modification of Sucrose-Modified Iron Oxide/Silica Mesoporous Composite for Degradation of Methylene Blue

Santa Barbara Amorphous (SBA-15) containing iron oxide with a sucrose-modified in a heterogeneous reaction for degradation methylene blue (MB) successful synthesized used hydrothermal, ultrasonication, and wet impregnation method. SBA-15 is mesoporous silica that can easily serve as external and internal surfaces making it suitable for a wide range of applications. The structure and morphology of materials were characterized using Surface Area Analyzer (SAA), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope-Energy Dispersive X-Ray (SEM-EDX), and Transmission Electron Microscopy (TEM). Iron oxide impregnated as a maghemite phase has an average size of 12 nm and well distributed on the SBA-15. After modified with sucrose the materials remaining stable, which has a two-dimensional hexagonal (p6mm) structure, high specific surface area, and large pore volume (up to 1.82 cm3.g−1). The degradation of MB was evaluated under visible light irradiation using UV-Vis spectroscopy. Catalytic activity showed efficiencies of 52.9; 70.2; and 21.1% for SBA-15, Fe2O3/SBA-15, and sucrose-modified Fe2O3/SBA-15 respectively. Sucrose-modified Fe2O3/SBA-15 has the lowest efficiency, which probably occurs due to the presence of pore-blocking and the formation of micropores on the external pore. The modification with sucrose has the advantage of producing a high surface area even though there is a catalytic center due to partial decomposition which causes a decrease in the efficiency of degradation of MB. All materials provide a high micro surface area so that they can be further adapted and can be widely applied to many potential applications as both catalyst support and an adsorbent. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Single-step electrochemical sensing toward ppb-level nitrite in cured meat sensitized with functionalized Ia3d mesoporous carbon

A simple and sensitive electrochemical sensor is designed for evaluating nitrite (NO2−) in cured meat by using the functionalized mesoporous carbon composites (CMK-8) as sensing interface. Herein, the synthesized CMK-8 with 3-D bicontinuous cubic (Ia3d) space groups has obvious electrochemical superiority over the usual CMK-3 with 2-D hexagonal (p6mm) space groups, and offers a powerful platform for gold nanoparticles (AuNPs) decoration inside and outside the ordered carbon pores via electrostatic adsorption and size matching. Benefitting from the synergistic effects of AuNPs and CMK-8 under suitable ratio, AuNPs-CMK-8 provides a favorable biocompatible microenvironment for hemoglobin (Hb) attachment, and also accelerates electron transfer between NO2− and active centers of Hb. The electrochemical determination is accomplished through one-step catalytic process without complicated operation or multiple reagents, greatly improving temporal efficiency. The limit of detection (LOD) as low as 2.1 nM (corresponding to 0.097 ppb by weight) is well qualified for the requirement for rapid monitoring nitrite in cured meat. Overall, the sensing strategy possesses the characteristics of excellent sensitivity, anti-interference ability, and single-step fashion, giving a promising solution to evaluate nitrite residual for ensuring cured meat safety.

Tryptophan functionalized framework of nanoporous material as fluorescent sensor for trace detection of Zn2+ ions

A novel fluorescent sensor of tryptophan functionalized mesoporous silica (Trp-Meso-Si) for detecting Zn2+ ion was designed by modifying the framework of nanoporous material with Tryptophan organic silicon source under the template via co-condensation method. Tryptophan organic silicon source was first synthesized by selecting natural amino acid as reagent via multi-steps reactions. The sensing material Trp-Meso-Si was well characterized by various spectroscopic techniques. The results indicate that material 5%-Trp-Meso-Si with low amounts of Tryptophan exhibits well-ordered one-dimensional hexagonal P6mm structure. However, the sample 15%-Trp-Meso-Si with high amounts of Tryptophan shows strongest fluorescent intensity at the same excited wavelength of 285 nm. All the materials Trp-Meso-Si indicate fluorescent signal at excited wavelength because of tryptophan as fluorophore moiety. In the fluorescent recognition experiments, Trp-Meso-Si could selectively and sensitively detect trace concentrations of Zn2+ ions in aqueous solution with satisfactory detection limits of 0.9 × 10−7 M. Tryptophan within the framework of mesoporous silica material showed strong affinity for Zn2+ ions according to a 3:1 ratio of [tryptophan] and [Zn2+] by plenty of groups with lone pair electrons.

Synthesis, Characterization and Use of Mesoporous Silicas of the Following Types SBA-1, SBA-2, HMM-1 and HMM-2.

Mesoporous silicas have enjoyed great interest among scientists practically from the moment of their discovery thanks to their unique attractive properties. Many types of mesoporous silicas have been described in literature, the most thoroughly MCM-41 and SBA-15 ones. The focus of this review are the methods of syntheses, characterization and use of mesoporous silicas from SBA (Santa Barbara Amorphous) and HMM (Hybrid Mesoporous Materials) groups. The first group is represented by (i) SBA-1 of three-dimensional cubic structure and Pmn symmetry and (ii) SBA-2 of three-dimensional combined hexagonal and cubic structures and P63/mmc symmetry. The HMM group is represented by (i) HMM-1 of two-dimensional hexagonal structure and p6mm symmetry and (ii) HMM-2 of three-dimensional structure and P63/mmc symmetry. The paper provides comprehensive information on the above-mentioned silica materials available so far, also including the data for the silicas modified with metal ions or/and organic functional groups and examples of the materials applications.

N and S Co-doped Ordered Mesoporous Carbon: An Efficient Electrocatalyst for Oxygen Reduction Reaction in Microbial Fuel Cells

Background: Porous carbon materials are promising candidate supports for various applications. In a number of these applications, doping of the carbon framework with heteroatoms provides a facile route to readily tune the carbon properties. The oxygen reduction reaction (ORR), where the reaction can be catalyzed without precious metals is one of the common applications for the heteroatom-doped carbons. Therefore, heteroatom doped catalysts might have a promising potential as a cathode in Microbial fuel cells (MFCs). MFCs have a good potential to produce electricity from biological oxidization of wastes at the anode and chemical reduction at the cathode. To the best of our knowledge, no studies have been yet reported on utilizing Sulfur trioxide pyridine (STP) and CMK-3 for the preparation of (N and S) doped ordered porous carbon materials. The presence of highly ordered mesostructured and the synergistic effect of N and S atoms with specific structures enhance the oxygen adsorption due to improving the electrocatalytic activity. So the optimal catalyst, with significant stability and excellent tolerance of methanol crossover can be a promising candidate for even other storage and conversion devices. Methods: The physico-chemical properties of the prepared samples were determined by Small Angle X-ray Diffraction (SAXRD), N2 sorption-desorption, Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FESEM) and X-ray Photoelectron Spectroscopy (XPS). The prepared samples were further applied for oxygen reduction reaction (ORR) and the optimal cathode was tested with the Microbial Fuel Cell (MFC) system. Furthermore, according to structural analysis, The HRTEM, and SAXRD results confirmed the formation of well-ordered hexagonal (p6mm) arrays of mesopores in the direction of (100). The EDS and XPS approved that N and S were successfully doped into the CMK-3 carbon framework. Results: Among all the studied CMK-3 based catalysts, the catalyst prepared by STP precursor and pyrolysis at 900°C exhibited the highest ORR activity with the onset potential of 1.02 V vs. RHE and 4 electron transfer number per oxygen molecule in 0.1 M KOH. The high catalyst durability and fuel-crossover tolerance led to stable performance of the optimal cathode after 5000 s operation, while the Pt/C cathode-based was considerably degraded. Finally, the MFC system with the optimal cathode displayed 43.9 mW·m-2 peak power density showing even reasonable performance in comparison to a Pt/C 20 wt.%.cathode. Conclusions: The results revealed that the synergistic effect of nitrogen and sulfur co-doped on the carbon substrate structure leads to improvement in catalytic activity. Also, it was clearly observed that the porous structure and order level of the carbon substrate could considerably change the ORR performance.

Synthesis of highly ordered mesoporous carbons nanofiber web based on electrospinning strategy for supercapacitor

Abstract Ordered mesoporous carbons fiber webs (OMCWs) with 2-D hexagonal (p6mm) pore structure were prepared by the electrospinning method using low molecular resin as carbon precursors, F127 as structure directed agent and PVP (polyvinyl pyrrolidone, Mw = 1,300,000) as fiber forming agent under wide range various electrospinning speed (0.1–0.5 ml/h) and voltages (15–25 kv). The microstructure of OMCWs could be tunable from cylinder to nano ribbon by carefully controlling the amount of PVP. OMCWs could be directly used in supercapacitor as electrode materials without any binders or conductive additives. The specific capacitance of OMCWs could reach as high as 119 F/g under the current density of 0.5 A/g, demonstrating the great potential application for electrode for supercapacitor.

Inorganic Salt Assisted Self‐Assembly of Periodic Mesoporous Organosilicas with Various Structures under Alkaline Conditions

Ethylene‐bridged PMOs have been prepared with the assistance of inorganic salts using CTACl as surfactant under alkaline conditions. The effects of various sodium salts on the formation of ethylene‐bridged PMOs was thoroughly investigated. It was found that the self‐assembly of PMOs is not profoundly affected by the concentration of salts, but to be controlled predominantly by the types of anions that contained in the salts. The addition of NaCl during the synthesis can lead to PMOs with mixed mesophases (cubic Pm3n and 2‐D hexagonal P6mm), while a pure 2‐D hexagonal and lamellar mesophase can be obtained by adding NaBr and NaI respectively. The effects of inorganic salts can be roughly predicted through the binding strengths of counterions to the surface of surfactant micelles. Additionally, the pore wall thickness and degree of cross‐linking of PMOs will be increased with the addition of inorganic salts, thus leading to mesoporous materials with improved hydrothermal stability. The study contributes fundamental understanding of the formation of PMOs with the assistance of inorganic salts, providing a facile method to prepare ordered mesoporous materials with more diversified structures and morphologies.

Functionalized Silica Particle Based Single Ion Conducting Hybrid Electrolyte for Li-Ion Battery

For advanced energy storage (batteries and supercapacitors), energy conversion (fuel cells and solar cells), and electromechanical transduction devices (electroactive ionic actuators and sensors), it is vital to utilize single-ion polymer conductors (ionomers) that have been designed by covalently attaching anions (or cations) to the polymer chains. This allows the high lithium transference number in lithium polymer batteries as well as the fast response time under low voltage operating conditions in ionic polymer actuators. However, current single-ion conductors exhibit relatively low conductivities, precluding use of these materials in potential applications. This is predominantly due to relatively slow polymer segmental motion, resulting in decreased ion mobility, and large ion dissociation energy, lowering the number of simultaneous charge carries. In order to overcome the issues, we have synthesized porous silica-based lithium single-ion conducting nanoparticles containing anions with lithium counter ions. These nanoparticles are then introduced into poly(ethylene oxide) matrix, allowing us to prepare nanocomposite polymer electrolytes. Anion functionalized mesoporous silica (FMS-TFSISPE) nanoparticles were prepared by the two-step selective functionalization method. Poly(ethylene glycol) group was attached using sol-gel method on mesoporous silica particles. Trifluoromethanesulfonimide group functionalized to silica particles for binding lithium cation. The particles are uniformly distributed with an average size of 50 nm. HRTEM measurement further suggests that the clear mesoporous structure is observed. In order to extensively investigate the structural information on FMS-TFSISPE, the N2 adsorption/desorption isotherm is obtained as shown, where FMS-TFSISPE shows type IV isotherms of typical mesoporous materials, and the BET surface area is 995 m2 g- 1. The average pore size of the FMS-TFSISPE nanoparticles is about 3 nm which is close to that observed by the HRTEM measurement. The small angle XRD analysis shows three resolved peaks from which the pore structure corresponds to a 2D hexagonal (P6mm) structure. From the structure analysis, we successfully synthesized the FMS-TFSISPE nanoparticles with well-ordered hexagonal arrays of mesopore channels and exceptionally high surface area and pore volume. It is apparent that FMS-TFSISPE nanoparticles have a considerable effect on the enhancement of the ionic conductivity of these electrolytes, and their conductivities increase monotonically with increasing FMS-TFSISPE content. The maximum enhancement in conductivity is found for the nanohybrid electrolyte containing 30 wt % FMS-TFSISPE and order of sDC ~ 10- 3 S/cm at 25 oC, 10 times higher than the minimum practical requirement for single-ion conductors. We develop a novel nanohybrid single-ion conductor based porous silica structure. These systems display exceptional ionic conductivity and lithium transference number. It is shown that such nanohybrid electrolytes significantly immobilize the anion movement and pave the way for fast lithium ion-only conducting pathway. Provided that the optimization of the nanohybrid electrolytes with high-energy and -power electrodes is realized, the use of our highly conducting single-ion conductor in practical polymer electrolyte batteries will be envisaged.

Fabrication of ordered mesoporous carbons with tunable pore architecture by the cosolvent

Ordered mesoporous carbons (OMCs) with tunable mesophase were prepared by a novel cosolvent method using low molecular resin as carbon precursor, and P123(Poly(ethyleneoxide)-poly(propyleneoxide)-poly(ethyleneoxide)triblock copolymers, EO20PO70EO20) as a template via an Evaporation-induced Self-assembly Process (EISA). The results show that the pore structure of OMCs could be oriented from 2D hexagonal (p6mm) to 2D centered rectangular (C2mm) structure. Two key descriptors of mesophase were identified. One is the ratio of PEO/PPO of triblock copolymer, and the other one is cosolvent, both of which would have effects on the interface of mesophase during the EISA process. Furthermore, it was confirmed that the ordered mesophase could be obtained in a very short time during the EISA process even accompanied by the microemulsion phenomenon.

The effect of calcination rate on the structure of mesoporous bioactive glasses

Mesoporous bioactive glasses (MBGs) are designed to have high specific surface area. They are formulated by a sol–gel process to formulate the glass followed by calcination. This study evaluates how calcination heating rate influences the porous architecture, and thereby the specific surface area, of MBGs. MBGs of molar ratio 80:15:5 for SiO2:CaO:P2O5 were calcined using both low (1 °C/min) and high (20 °C/min) heating rates, termed as L-MBG and H-MBG, respectively. The results obtained from small-angle X-ray diffraction (SAXRD) confirm that the MBGs possess 2D hexagonal (P6mm) spacing groups and wide-angle XRD confirms the amorphicity of both MBGs. Energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy confirm that both batches of MBGs have similar chemical composition. Fourier transform infrared spectroscopy identifies the same functional groups present in both batches. However, transmission electron microscopy indicates that H-MBG samples exhibited discontinuities in their ordered channel structure, confirmed by the lower SAXRD peak intensity of H-MBG compared to L-MBG. These discontinuities led to a reduced surface area. L-MBG exhibits more than quadruple the surface area and double the pore volume (373.87 m2/g and 0.27 cm3/g) of H-MBG (85.91 m2/g and 0.13 cm3/g), measured through Brunauer, Emmett, and Teller nitrogen adsorption analysis. This higher surface area resulted in a significant (p < 0.05) increase in the quantity of ion release from the L-MBGs compared to the H-MBGs. It is concluded that the application of a low heating rate during calcination, of the order of 1 °C/min, is more likely to result in ordered mesoporous bioactive glasses with high surface area and pore volume than MBG samples processed at a higher heating rate.

Synthesis of ultra small nanoparticles (&lt; 50 nm) of mesoporous MCM-48 for bio-adsorption

Mono-dispersed spherical MCM-48 mesoporous silica nanoparticles (MSN) with cubic Ia3d mesostructure were synthesized under different stirring conditions using hexadecyltrimethyl ammonium bromide as structure directing agent and EO20PO70EO20 copolymer as particle size control. Results indicated that the EO20PO70EO20 works well in the reduction of nanoparticle size. In addition, increasing the stirring rate transformed mesoporosity from 2-D hexagonal P6mm to 3-D cubic Ia3d. The biomolecule adsorption properties of prepared ultra small nanoparticles of MCM-48 were compared with that of MCM-48 with ten times larger particle sizes. MCM-48 with smaller particle sizes adsorbed much more vitamin B12 compared with MCM-48 with larger particles. In addition, diffusion of vitamin in the intraparticle spaces occurred only for MCM-48 with ultra-small nanoparticles.

Odd-Even Effect in Synthesis of Mesoporous Silica Using Long-Chain Acyl-L-Alanine Sodium Salt Templating.

In this research, hexagonal and cubic mesoporous silica with ordered parallel pore channels was synthesized using odd chain-length N-undecanoyl-L-alanine sodium salt and even chain-length N-lauroyl-L-alanine sodium salt as template respectively. Aminopropylsiloxane was used as the co-structure-directing agents (CSDA). The ordered mesostructure was characterized by infrared spectroscopy, small X-ray diffraction patterns (XRD), scanning electron microscope (SEM), trasmission electron microscope (TEM), and nitrogen sorption analysis. The results indicated that mesoporous silica which was prepared by asymmetric odd chain-length surfactants presented a looser strucuture with large volume than mesoporous silica prepared by the even chain-length surfactant. It led to the transformation from 2D hexagonal (p6mm) phase to cubic (Ia¯3d) mesophase.

Synthesis of iron oxide nanoparticles modified mesoporous carbon and investigation of its application for removing dibenzothiophene from fuel model

In this study, magnetic ordered mesoporous carbon (γ-Fe2O3/CMK-3) containing iron oxide nanoparticles embedded in the carbon walls by wet impregnation method was prepared and used as a high effective magnetic adsorbent to adsorb polyaromatic sulfur compound (dibenzothiophene). The structure and morphology of adsorbent were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption–desorption (BET), thermal gravimetric (TGA) and alternating gradient force magnetometer techniques (AGFM). These techniques illustrate that the maghemite nanoparticles have an average size of 10 ± 3 nm and are well distributed on the ordered mesoporous carbon host. After embedding maghemite nanoparticles, the uniformity of mesoporous framework of CMK-3 still remaining stable, which has an ordered two-dimensional hexagonal (p6mm) structure, high specific surface area, maxima pore size of 5.5 nm and large pore volume (up to 1.01 cm3 g−1). The γ-Fe2O3/CMK-3 nanocomposite shows superparamagnetic behavior with a saturation magnetization of 0.5 emu g−1, which makes it favorable compound for magnetic separation procedure. The resulting magnetic mesoporous nanocomposite was investigated for adsorption of dibenzothiophene (DBT) as a model sulfur compound in n-hexane as fuel model. Various factors influencing the adsorption of DBT, including adsorption temperature, contact time and initial DBT concentration were studied. The kinetic data was well described by pseudo-second-order kinetic model and the equilibrium adsorption data was fitted to the Langmuir thermodynamic model. In addition, the adsorbent could be regenerated by washing with toluene and over 85% adsorption capacity could be maintained after three regeneration cycles. The results confirmed that γ-Fe2O3/CMK-3 has the potential superiority in removal of DBT from fuel model with a maximum adsorption capacity of 67 mg DBT per gram of adsorbent and an easy magnetically separable process.

Influence of Synthesis Parameters in Obtaining KIT-6 Mesoporous Material

In the present work, modifications were made in the typical synthesis of KIT-6 mesoporous material. The molar ratio of P123 and its dissolution time, the type of alcohol, the aging time, and the heat treatment time were varied. The materials obtained were characterized by X-ray diffraction (XRD), thermogravimetry and differential thermogravimetry (TG/DTG), Fourier-transform infrared spectroscopy (FTIR), adsorption and desorption of N2 and transmission electron microscopy (TEM). It was observed that the modifications interfered directly in the ordered structure of materials, displaying materials with cubic structures Ia3d (KIT-6 mesoporous material) and hexagonal structures P6mm, (SBA-15 mesoporous material). The type of alcohol probably acts on generation of the micelle, influencing the formation of the porous system and ordered structure. The results obtained indicate that the cubic structure of KIT-6 can be formed with a reduction of 30% in the P123 concentration, and decreases of 2, 6 and 12 h in times of P123 dissolution, aging and heat treatment, respectively. The modifications carried out in the synthesis procedure have resulted in ir being possible to employ materials with different characteristics, such as mesoscopic ordering and textural properties, in applications in the areas of catalysis and adsorption.