Functional SBA-15 Research Articles

Amino functional SBA-15 assisted NU-1000 for the rapid and efficient adsorption of tetracycline antibiotics

Amino functional SBA-15 assisted NU-1000 for the rapid and efficient adsorption of tetracycline antibiotics

Preparation of SBA-15 surface lanthanum ion-imprinted polymer and its adsorption properties

The preparation of a lanthanum ion-imprinted polymer is described via surface ion imprinting, with polyethyleneimine as the functional monomer and SBA-15 as the matrix material. Its structure was characterized and analyzed, and static adsorption experiments were carried out to determine the best experimental conditions for the adsorption of lanthanum ions. The effects of initial concentration, temperature, adsorption time and pH on the adsorption of lanthanum ion surface-imprinted polymer were investigated. In addition, the regeneration performance of La(III)-IIP-PEI/SBA-15 on lanthanum ion was studied and showed that La(III)-IIP-PEI/SBA-15 has strong specific recognition ability and high reuse performance.

H3PMo12O40 Immobilized on Amine Functionalized SBA-15 as a Catalyst for Aldose Epimerization.

In this work various amount of phosphomolybdic acid (PMo) were immobilized on amine functionalized SBA-15 and used as heterogeneous catalysts in the epimerization of glucose in aqueous solution. 13.3PMo/NH2-SBA-15 exhibited the best catalytic performance with a glucose conversion of 34.8% and mannose selectivity of 85.6% within two hours at 120 °C. The activation energy of 80.1 ± 0.1 kJ·mol−1 was lower than that of 96 kJ·mol−1 over the homogeneous H3PMo12O40 catalyst. The catalytic activities of 13.3PMo/NH2-SBA-15 for the transformation of some other aldoses including mannose, arabinose and xylose were also investigated.

Fine Copper Nanoparticles on Amine Functionalized SBA-15 as an Effective Catalyst for Mannich Reaction and Dye Reduction

Copper nanoparticles dispersed on amine functionalised mesoporous silica SBA-15 (Cu/NH2-SBA-15) were synthesised by a simple sol–gel and impregnation method using sodium borohydride (NaBH4) as a reducing agent. The morphology, mesostructure and functionality of the ordered mesoporous Cu/NH2-SBA-15 were evaluated by powder X-ray diffraction (PXRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Nitrogen adsorption–desorption isotherms (BET) and Fourier transform infrared spectroscopy (FTIR). The results obtained revealed, that the amine functionalised SBA-15 holds hexagonal lamelliform with surface area and pore size of 250 m2/g, 2.2 nm respectively. Moreover, these short vertical channels have a substantial role in the uniform dispersion of copper nanoparticles within the meso-channels of amine functionalised SBA-15. Cu nanoparticles in the size range of 4–7 nm were dispersed on the NH2-SBA-15 support. To confirm the potential catalytic activity, Cu/NH2-SBA-15 was tested in Mannich reaction. The catalyst showed an excellent catalytic activity for the yield (90%) of β-amino carbonyl compounds that serve as a building block for the synthesis of lactams, peptides, amino alcohols and precursor for various amino acids. Further, the activity of the catalyst was also tested for the reduction of dyes. The structural influence over the reduction pathways was studied on triphenyl methane dyes.

Modification of mesoporous silica with molecular imprinting technology: A facile strategy for achieving rapid and specific adsorption

In order to improve the diffusion kinetics of molecularly imprinted materials (MIMs), applying imprinting technology to mesoporous materials is a promising strategy. In the present study, an imprinting approach based on the combination of mesoporous silica materials and molecular imprinting technology is reported. Molecularly imprinted material (MIM) for 2,4-dichlorophenoxyacetic acid (2,4-D) was prepared by using 2,4-D as the template molecule, alkyne-modified β-cyclodextrin and propargyl amine as the combinatorial functional monomers and SBA-15 as the supporter. The functional monomers were anchored to the azide-modified SBA-15 by azide–alkyne Click reaction. The synthesized MIM was characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), elemental analysis (EA), thermal gravimetric analysis (TGA), low-angle X-ray diffraction (XRD) and N2 adsorption–desorption analysis. The interactions between template and functional monomers were studied by proton NMR analysis and UV–vis experiments. The results of the equilibrium binding experiments and selective tests showed that the prepared MIM has binding affinity and specificity for a group of analytes which have similar size and shape to those of template. Binding kinetic experiments demonstrated that the present imprinting approach can effectively enhance the mass transfer rate. The solid phase extraction of 2,4-D using MIM as the adsorbent was investigated. The extraction conditions for the processes of loading, washing and eluting were optimized. The recoveries of the molecularly imprinted solid phase extraction (MISPE) column for 2,4-D were 76.3–88.9% with relative standard deviations (RSD) of 3.48–7.64%.

Rational design and synthesis of aldehyde-functionalized mesoporous SBA-15 for high-performance ammonia sensor

Herein, we report novel ammonia gas sensor materials having aldehyde functional groups grafted onto the pore surface of highly ordered mesoporous materials SBA-15. The functional SBA-15 was synthesized via co-condensation of tetraethyl orthosilicate and formylsilanetriol using an amphiphilic block copolymer P123 as a structure-directing agent, in which formylsilanetriol was first synthesized through the reduction of 2-cyanoethyltriethoxysilane in the presence of diisobutylaluminium hydride. Structural and textural characterizations by x-ray diffraction, transmission electron microscopy and N2 adsorption–desorption porosimetry were conducted and the results show the materials having well-defined mesoporous long-range ordering with pore size of 6.2nm. Furthermore, FT-IR and solid-state magic angle spinning nuclear magnetic resonance spectroscopy studies proved covalent anchoring of the aldehyde functional group onto the pore walls of SBA-15. The results indicated that the materials successfully kept their mesoporous nature after grafting of the aldehyde groups. Gas-sensing tests were investigated by coating the aldehyde-functionalized SBA-15 onto quartz crystal microbalance transducers. The results reveal that the sensors can be as promising candidates as ammonia detectors with desirable sensing behaviors, including high sensitivity (the frequency shift was 22Hz at 1ppm and the QCM sensors were exposed to nitrogen stream until a stable baseline (±2Hzmin−1)), fast response (response time within 11s, recovery time within 13s) and good reversibility.

Thermogravimetric Analysis (TGA) Profile at Different Calcination Conditions for Synthesis of PTES-SBA-15

The aim of this work is to study the effects of calcination condition on the properties of mesoporous silica, SBA-15 modified with phenyl group of organosilane. Functional group SBA-15 were synthesized and hydrothermally aged. The surfactant template was conventionally removed by calcination at varied temperature and duration. Thermogravimetric Analysis (TGA) was employed to characterize the pure and modified SBA-15. The TGA profile presented here would include modified SBA-15 functionalized using two different methods, direct-synthesis and post-grafting. The characterization profile from TGA showed that the temperature of calcination has large influence in determining the effectiveness of surfactant removal and incorporation of alkoxysilane into pure silica whether by post-grafting or direct synthesis method. However, the duration of calcination does not significantly affect these characteristics. Besides, mesoporous structure of SBA-15 by post-grafting method shows higher degree of functionalization than that of direct-synthesis.

Thiols make for better catalysts: Au nanoparticles supported on functional SBA-15 for catalysis of Ullmann-type homocouplings.

A strategy for arraying small gold nanoparticles on a mesoporous support modified with single-component or mixed self-assembled monolayers is described. The use of mixed surface modifiers allows easy access to a range of surface chemistries and modalities of interaction between nanoparticles and supports. A combination of thiol groups and linear semifluorinated chains effectively stabilized the nanoparticles against aggregation, while preserving their catalytic activity. The thiol-fluorous-supported catalyst was found active in Ullmann-type homocoupling of aryl halides and showed exceptional selectivity in this reaction.

Propylsulfonic and arenesulfonic functionalized SBA-15 silica as an efficient and reusable catalyst for the acidolysis of soybean oil with medium-chain fatty acids

The objective of this work was to develop a feasible ecofriendly process to produce medium-chain fatty acid (MCFA)-enriched structured lipids (SLs) in heterogeneous manners. For this purpose, the propyl-SO3H or arene-SO3H-modified SBA-15 materials were prepared through a surface functionalization of SBA-15 silica with propyl-SO3H and arene-SO3H groups. The organosulfonic acid-functionalized SBA-15 materials were characterized by Brönsted acidity determination, elemental analysis, XRD, C13 MAS NMR, FT-IR, SEM, TG, TEM, and N2 adsorption-desorption techniques. Results showed that the propyl-SO3H and arene-SO3H groups were successfully tethered on the SBA-15 support, and the ordered mesoporous structure of SBA-15 silica was well retained after the organofunctionalization. This organic-inorganic hybrid material displayed high surface acidities and high activities in the acidolysis of soybean oil with caprylic or capric acid to produce SLs containing MCFAs. The influences of processing parameters on the reaction were investigated. The two studied catalysts showed an excellent recyclability for the reaction.

Dihydroxy bezladely derivatives functionalized mesoporous silica SBA-15 for the sorption of U(VI)

Three different modified SBA-15 have been synthesized by a post-grafting method using 3,4-dihydroxy benzaldehyde (OHBA), 2,4-dihydroxy benzaldehyde (MHBA), 2,4-dihydroxy acetophenone (RATP). These materials were characterized by NMR, TEM, FT-IR and elemental analysis. Batch experiments have been conducted to study the effects of pH, temperature, adsorbent dosage, ionic strength, shaking time, initial concentration of metal ion, and coexisting ions on uranium(VI) sorption behaviors of pure and functional SBA-15. In addition, the adsorption of U(VI) could be well-described by the Langmuir, Freundlich isotherms and pseudo-second kinetic models. The results suggest the sorption capacity and selectivity of SBA-15 were improved after functionalization.

Facile synthesis of gold nanoparticles on propylamine functionalized SBA-15 and effect of surface functionality of its enhanced bactericidal activity against gram positive bacteria

The facile synthesis of an SBA-15-pr-+NH3.Au0 nano-hybrid material by spontaneous autoreduction of aqueous chloroaurate anions on propylamine functionalized SBA-15 was successfully demonstrated. The as-synthesized SBA-15-pr-+NH3.Au0 nano-hybrid material was well characterized using low and wide angle x-ray diffraction (XRD), N2 adsorption–desorption isotherms, Fourier transform infrared (FTIR), transmission electron microscopy (TEM), scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDX), x-ray photoelectron spectroscopy (XPS), UV-Visible spectroscopy and atomic absorption spectroscopy (AAS). The activity of the nano-hybrid material as a potent bactericidal agent was successfully tested against Gram positive/negative bacteria viz. Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The colony killing percentage of Gram positive bacteria was found to be higher than Gram negative bacteria due to the stronger electrostatic interaction between the positively-charged amine functionality of SBA-15 and the negatively charged functionality of the bacterial cell wall.

Atom transfer radical polymerization of diverse functional SBA-15 for selective separation of proteins

Poor detection of low-abundant proteins is a common problem in most current protein identification schemes. This is attributed partially to the existence of high-abundant protein. Therefore, selective removal of specific proteins prior to analysis is in great demand. In response these needs, we previously described two kinds of ion exchange groups functionalized SBA-15 synthesized by direct silylanization reaction. Herein, we designed and synthesized strong anion, cation and zwitterion functionalized SBA-15 via atom transfer radical polymerization (ATRP). The previous and current materials were characterized and theirs adsorption abilities for some model proteins (bovine serum albumin (BSA), hemoglobin (Hb), myoglobin (Mb) and lysozyme (Lys)) were evaluated. The results demonstrated that different functionalized SBA-15 is capable to selective removal of certain proteins in protein mixture. It also indicated that this sample preparation technique could be potentially applied to reduce the complexity on protein identification for biological samples with a wide dynamic range.

Removal of uranium(vi) from aqueous solution using iminodiacetic acid derivative functionalized SBA-15 as adsorbents

Three different functional SBA-15 were prepared by a post-grafting method using three iminodiacetic acid derivatives of ethylenediaminetriacetic acid (ED3A), diethylenetriaminetetraacetic acid (DT4A), and 1,2-cyclohexylenedinitrilotriacetic acid (CyD3A), which were used as adsorbents for removal of uranium(vi) from aqueous solution. These materials were characterized by FT-IR, NMR, TEM, nitrogen adsorption/desorption experiments, and elemental analysis. The effect of pH, ionic strength, contact time, solid-liquid ratio, initial metal ion concentration, temperature, and coexisting ions on uranium(vi) sorption behaviors of the functionalized SBA-15 was studied. Typical sorption isotherms (Langmuir and Freundlich) were determined for the sorption process, and the maximum sorption capacity was calculated. The influence of functional groups on uranium(vi) sorption was also discussed. As a result, compared with other current U(vi) sorbents (granite, kaolin, attapulgite), SBA-15-1,2-cyclohexylenedinitrilotriacetic acid (SBA-15-CyD3A) possessed good selective sorption properties, which had potential application in separation of uranium(vi).

Development of bio-based F-SBA-15 reinforced epoxy nanocomposites for low-k dielectric applications

The present work focuses on the utilization of renewable biomaterial as reinforcement for the development of nanocomposites for high-performance low- k microelectronic applications. In the present work, rice husk ash (RHA) was chemically treated and processed to obtain two-dimensional mesoporous silica (SBA-15), which was functionalized using 3-glycidoxypropyl trimethoxy silane through sonication process. The surface functionalized SBA-15 (F-SBA-15) with varying weight percentages (1, 3, and 5 wt%) was incorporated into the epoxy resin. The resulting F-SBA-15-reinforced epoxy composites were characterized by Fourier transform infrared spectroscopy, x-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, and impedance analyzer. Among the composite samples with varying loadings, the dielectric behavior of 5 wt% F-SBA-15-loaded composite sample possesses the lowest value of dielectric constant, that is, 2.14 at 1 MHz frequency when compared with that of other samples. Further, the thermal stability was also enhanced to an appreciable extent, when compared with that of the samples with lower F-SBA-15 loadings.

Adsorption of phenolic compounds from aqueous solutions using functionalized SBA-15 as a nano-sorbent

Amino functional mesoporous silica SBA-15 materials have been prepared as efficient adsorbents for halophenols in wastewater. The organic–inorganic hybrid material was obtained using successive grafting procedures of SBA-15 silica with 3-aminopropyl-trimethoxysilane (NH2–SBA-15). The comparison of adsorption of halophenols on untreated mesoporous SBA-15 and NH2–SBA-15 is studied. It is found that NH2–SBA-15 shows significant adsorption for halophenols. The samples were characterized by X-Ray Diffraction (XRD), nitrogen adsorption-desorption isotherms, Scanning Electron Microscopy (SEM), and Fourier Transform Infrared (FT–IR). Batch adsorption studies have been carried out to study the effect of various parameters, such as contact time, pH, adsorbent dose and initial adsorbate concentration. The equilibrium adsorption data of halophenols onto NH2–SBA-15 were analyzed using Freundlich and Langmuir adsorption isotherms. From the sorption studies it was observed that the uptake of 4-chlorophenol (CP) was higher than 4-bromophenol (BP) and 4-iodophenol (IP).

3D net-linked mesoporous silica monolith: New environmental adsorbent and catalyst

This paper reported the synthesis, characterization, adsorption and catalysis of new morphology-assisted functional SBA-15, the 3D net-linked mesoporous silica monolith, and its actual function in selective reducing tobacco specific nitrosamines (TSNA) level of smoke, in order to explore the new route elevating the efficiency of environment adsorbents/catalysts through their morphology controlling. It is feasible to control the hydrolization and condensation of silica source in synthesis, and then piloting the formation and the secondary arrangement of primary particles, finally forming the monolith with 3D net-linked morphology. The resulting sample not only had the shape of monolith, but also possessed a considerable mechanical intensity hence it could be directly sieved for use without molding. With the assistant of net-linked morphology, this monolith sample could intercept the particles with μm sizes in tobacco smoke, and selectively capture the TSNA adhered on the particle, providing new functional material for environment protection. Through dry-impregnation it is also successful to modify the monolith with zirconia guest without damage of 3D net-linked morphology, dramatically increasing the activity of the composite in the instantaneous adsorption of volatile nitrosamine such as N-nitrosopyrrolidine (NPYR) and the temperature programmed surface reaction (TPSR) of N′-nitrosonornicotine (NNN), offering a powerful environmental catalyst to degrade carcinogenic pollutants.

Highly Sensitive Fluorescence Probe Based on Functional SBA-15 for Selective Detection of Hg2+

An inorganic–organic hybrid fluorescence chemosensor (DA/SBA-15) was prepared by covalent immobilization of a dansylamide derivative into the channels of mesoporous silica material SBA-15 via (3-aminopropyl)triethoxysilane (APTES) groups. The primary hexagonally ordered mesoporous structure of SBA-15 was preserved after the grafting procedure. Fluorescence characterization shows that the obtained inorganic–organic hybrid composite is highly selective and sensitive to Hg2+ detection, suggesting the possibility for real-time qualitative or quantitative detection of Hg2+ and the convenience for potential application in toxicology and environmental science.

Highly sensitive and selective fluorescence sensor based on functional SBA-15 for detection of Hg2+ in Aqueous Media

A new Rhodamine-based chemosensor RBSN designed for the selective detection of Hg(2+) in aqueous media is synthesized and structural characterized. It features brightness blue emission in the presence of Hg(2+) with the fluorescent detection limit for Hg(2+) in aqueous media being ppb levels and exhibits excellent Hg(2+)-specific luminescence enhancement over various competitive cations, including alkali and alkaliearth, the first-row transition metals and heavy metals. By immobilizing RBSN to the mesoporous SBA-15, a highly selective and sensitive chemosensor toward mercury cations in aqueous solution was achieved. RBSN/SBA-15 could quantitatively determinate mercury cations at ppb level in the practical environmental media, suggesting the possibility for real-time quantitative detection of Hg(2+) and the convenience for potential application in toxicological and environmental science.

Highly sensitive fluorescence probe based on functional SBA-15 for selective detection of Hg2+in aqueous media

An inorganic-organic hybrid fluorescence chemosensor (R6G-SBA-15) was prepared by covalent immobilization of a Rhodamine 6G derivative within the channels of mesoporous silica material SBA-15 via triethoxysilane groups. The primary hexagonally ordered mesoporous structure of SBA-15 is preserved after the grafting procedure. R6G-SBA-15 features effectively chromogenical and fluorogenical responses with a broad pH span (2-10), excellent sensitivity to environmentally relevant mercury levels lower to ppb range. It also exhibits Hg(2+)-specificity over various competitive cations, including alkali and alkaliearth, the first-row transition metals as well as heavy metals such as Pb(2+), Cd(2+) and Ag(+), etc. Additional experiments establish the well-fitted linearity function of the fluorescent intensity with the concentration of Hg(2+) in aqueous solution, suggesting the possibility for real-time qualitative or quantitative detection of Hg(2+) and the convenience for potential application in toxicology and environmental science.

Grafting of thermo-responsive polymer inside mesoporous silica with large pore size using ATRP and investigation of its use in drug release

The design of a delivery system was reported based on stimuli-responsive poly(N-isopropylacrylamide) (PNIPA) inside a mesostructured cellular foam (MCF) via atom transfer radical polymerization (ATRP), and the control of drug release in response to the environmental temperature was investigated. The successful synthesis of PNIPA inside the MCF was confirmed by Fourier transform infrared (FT-IR), transmission electron microscopy (TEM) and nitrogen adsorption/desorption measurements. Control of drug release through the porous network was performed by measuring the uptake and release of ibuprofen (IBU). The delivery system of MCF-PNIPA demonstrated a high IBU storage capacity of 58 wt% (IBU/silica), which is much higher than that reported for functional SBA-15 (37 wt%). The multilayer polymers inside the pores of the MCF were considered to form an internal cavity for drug molecules in addition to responding to changes in external temperature.