Fibrous Mesoporous Silica Research Articles

Synthesis and photocatalytic performance of recyclable core-shell mesoporous Fe3O4@Bi2WO6 nanoparticles

Composite photocatalysts composed of semiconductor and magnetic matters are of great concern due to their excellent catalytic and recyclable performances. In this work, Fe3O4 nanoparticles are modified by a fibrous mesoporous silica layer (F-SiO2), on which a mesoporous Bi2WO6 shell is grown in situ through hydrothermal reaction. Along with the formation of Bi2WO6 shell, the F-SiO2 layer fades away by the acid etching. As a result, novel spherical core-shell mesoporous Fe3O4@Bi2WO6 nanoparticles with a high BET surface area of 127.3 m2/g are fabricated. The photocatalytic decomposition of methylene blue (MB) under visible light irradiation reveals that the mesoporous Fe3O4@Bi2WO6 nanoparticles show excellent physisorption and photocatalytic performances. The total removal ratio of MB can be achieved as high as 98%. Furthermore, the mesoporous Fe3O4@Bi2WO6 nanoparticles maintain high photocatalytic activity after five cycles. This work provides a new way to construct recyclable mesoporous Bi2WO6-based nanomaterials with high performance to remove organic pollutants.

Synergistic effects of stellated fibrous mesoporous silica and synthetic dsRNA analogues for cancer immunotherapy.

Stellated fibrous mesoporous silica nanospheres significantly improve the cellular uptake of cancer antigen and the maturation of bone marrow derived dendritic cells in vitro. Moreover, the combination of poly(I:C) with stellated fibrous MS nanospheres markedly decreases the necessary dose of poly(I:C) for anti-tumor immunity, and thus opens new opportunities for the future clinical application of poly(I:C) in cancer immunotherapy.

Fibrous N-doped hierarchical porous carbon microspheres: Synthesis and adsorption performance

The creation of high surface area and effective active sites is the key problem for the synthesis of high-performance porous carbon materials. In this work, polyacrylonitrile-coated fibrous silica (F-SiO2@PAN) microspheres were prepared by in situ polymerization of acrylonitrile on fibrous mesoporous silica microspheres induced by γ-ray radiation. After F-SiO2@PAN microspheres were carbonized and etched with hydrofluoric acid, uniform fibrous N-doped porous carbon (FNC) microspheres with an average size of 286nm and a molar ratio of C/N of 5.2 were successfully prepared. As revealed by TEM, SEM, and N2 adsorption-desorption isotherms analysis, FNC microspheres have a hierarchal micro-macroporous structure with a particular high surface area of 554.5m2/g. The FNC microspheres also exhibit a good water dispersibility and an excellent adsorption ability to rhodamine B in water. The equilibrium adsorption capacity of FNC microspheres could reach 95.4mg/g, which is 1.6 times as that of the primary silica template microspheres. The adsorption kinetics and thermodynamics of FNC microspheres are in accord with the pseudo-second-order kinetic equation and Freundlich isotherm model, respectively. This work provides a facile synthesis method for novel N-doped hierarchical micro-macroporous carbon microsphere as a potential high-performance adsorbent material.

Polymer-modified fibrous mesoporous silica nanoparticles as coating material for open-tubular capillary electrochromatography

A novel fibrous mesoporous silica nanoparticles (fSiO2) stationary phase grafted with polymer (Poly (2-(dimethylamino) ethyl methacrylate) (PDMAEMA) was developed for open tubular capillary electrochromatography (OT-CEC). The preparation procedure included synthesizing fSiO2 through biphase stratification approach, removing the surfactants, silanization and in situ graft polymerization with monomers via atom transfer radical polymerization (ATRP). Subsequently, PDMAEMA-modified mesoporous silica nanoparticles (P-fSiO2)/ethanol solution was immobilized onto the inner surface of the pretreated capillary and functionalized with octadecylsilane to fabricate the open-tubular column. Separation of polycyclic aromatic hydrocarbons (PAHs) and proteins were carried out to evaluate the performance of the column in CEC. The run-to-run, day-to-day and column-to-column reproducibility in terms retention time of naphthalene was 1.9%, 2.2%, and 3.7%, respectively. The effects of solvent concentration and pH on the separation were evaluated. The method was also used for the separation of real bio-sample, egg white proteins.

Synthesis of Mesoporous Silica Particles with Fibrous Morphology via Self-Assembly Process in Microemulsion System

In this research, several precursors were chosen to solve the drawbacks of using toxic and expensive chemicals in the synthesis of fibrous mesoporous silica particle via self-assembly process in microemulsion system. The synthesis of this emerging material normally is realized by using toxic cetylpyridinium bromide (CPB) as common structure directing agent in conjunction with combined cyclohexane and n-pentanol as expensive solvent and co-solvent, respectively. Less toxic cetyltrimethylammonium bromide (CTAB) can be the replacement for CPB but the use of this surfactant may drastically reduce the surface area of the resulting product. Herein, we report that the use of CTAB with combined toluene and n-butanol as affordable solvents can be used to synthesize fibrous mesoporous silica particle with high surface area. The material was well characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), N2 adsorption/ desorption, X-ray difraction (XRD)and thermal gravimetry (TG). This material might be applied in potential applications such as catalysis, drug delivery and adsorption. Moreover, it can be used as a hard-template for fabricating another novel fibrous materials.

Synthesis of hybrid SBA-15 functionalized with molybdophosphoric acid as efficient catalyst for glycerol esterification to fuel additives

Fibrous mesoporous hybrid silica (SBAH-15) with mesopore diameter of 70Å was synthesized using pluronic P123 (EO20PO70EO20) as surfactant, with Brij S100 as nonionic co-surfactant. Series of catalysts with different molybdophosphoric acid (MPA) loading (5–25%) were synthesized by the thermal decomposition of MPA species in the lattice of SBAH-15. Catalysts calcined at 560°C undergone a thermal decomposition of MPA resulted in the formation of β-MoO3 active species. The effectiveness of the hybrid support was evaluated by comparison with analogous catalyst prepared by incorporating MPA into the framework of classical SBA-15. The catalytic performance of the prepared acid catalysts was examined during glycerol esterification with acetic acid. Mono-, di- and triacetyl glycerol (MAG, DAG and TAG, respectively) were the esterification reaction products. SBAH-15(15) catalyst, with 15wt.% MPA loading, exhibited an excellent activity during this reaction, indicated by the complete glycerol conversion (after 1h) with a corresponding combined selectivity of 86% toward both DAG and TAG. The best reaction conditions are: reaction temperature of 110°C, glycerol to acetic acid molar ratio of 1:6 and reaction time of 3h. The SBAH-15(15) catalyst demonstrated good stability in activity upon recycling for four times.

Effect of Pentanol on Morphologies and Pore Structure of Mesoporous Silica

Using wormlike micelles of cetyltrimethylammonium bromide (CTAB) and nitric acid as templates, fibrous mesoporous silica was synthesized and the effects of pentanol on the morphologies and ordered pore structure of mesoporous silica were studied. The resulting mesoporous silica was characterized by small-angle X-ray diffraction, nitrogen adsorption−desorption measurements, and scanning electron microscopy. Results showed that the amount of mesoporous silica with fibrous shapes decreased with the decrease of the molar ratio of CTAB to pentanol and that mesoporous silica with a spherical appearance only was obtained at a molar ratio of 1:3 (CTAB to pentanol). The pore structure of mesoporous silica was more ordered when the molar ratio of CTAB to pentanol was between 1:1 and 1:2, and distances between centers of two adjacent pores increased with the decrease of the molar ratio of CTAB to pentanol. There existed a type IV adsorption isotherm and an H1 hysteresis loop in N2 adsorption−desorption curves; total...

Synthesis of mesoporous silica fiber using spinning method

A very simple procedure for the synthesis of fibrous mesoporous silica using a spinning method was developed. It was based on the sol–gel process and solvent evaporation process using cetyltrimethylammonium chloride as a template. Fibrous mesoporous silica was drawn by using a viscous solution which consisted of a surfactant (cetylmethylammonium chloride) and hydrolyzed silica alkoxide (TMOS). Fibrous mesoporous materials have two distinct pores, 0.9 and 1.9 nm, with a specific surface area of about 580 m 2/g in 1000 rpm of spinning speed. The intensity of the X-ray diffraction pattern of the mesoporous fibers was increased after both the fiber spinning and calcination process. Increasing the spinning speed from 500 to 2000 rpm in the spinning process increased the specific surface area of the mesoporous fibers from 547 to 605 m 2/g, and simultaneously decreased the diameter of the fibers from 80 to 20 μm.