Tetrabutyl Orthosilicate Research Articles

OG-POSS synergistically enhances the corrosion resistance and adhesion property of primer for silicone resin thermal protective coating

Octaglycidyldimethylsilyl polyhydric silsesquioxane (OG-POSS) in coordination with tetraethyl orthosilicate, tetrapropyl orthosilicate and tetrabutyl orthosilicate mixed solution was applied to the bonding of metal substrate and silicone resin thermal protective coating. The influence of OG-POSS addition on the interface of primer was systematically investigated by means of scanning electron microscope (SEM), salt spray test, thermogravimetric infrared spectroscopy (TGA-IR) and back temperature test. Results showed that the addition of OG-POSS favored the formation of a silane film of the primer, resulting in a more compact and continuous film. At the same time, the silane film had excellent corrosion resistance and adhesion, with a maximum adhesion strength of about 1.42 MPa. In addition, OG-POSS provided a unique Si-O-Si cage structure in the primer, which improved the ablation resistance of the interface layer, preventing the degradation and peeling of the coating in harsh environments.

Facile Preparation of Gold Nanoparticles Silica Composite Film Embedded in Anodized Aluminium Oxide-Glass Substrate

Thin film based on gold nanoparticles or AuNPs is typically used as catalyst in the industrial processes due to their high stability and good reusability. In this work, a thin AuNPs-silica composite film was fabricated firstly from sol-gel method by mixing gold pyrazolate complex to a medium comprised of ethanol, deionized water, and hydrochloric acid followed by addition of tetrabutyl orthosilicate as silica source. Next, 70 microliters of the sol-gel solution were spin-coated on several type of substrates such as glass, anodized aluminium oxide or AAO, and combination of both to yield gold complex-silica composite film. It was found that gold complex-silica composite film fabricated on combination of both AAO-glass substrate gave the best quality based on its surface thickness, layer uniformity and film brittleness. Later, the film was selected and subjected to thermal hydrogen reduction at 210 degrees Celsius for 2 hours to facilitate the formation of gold nanoparticles to give AuNPs-silica in AAO-glass film. Before the heat treatment, the light-brownish colour of the original gold complex-silica in AAO-glass film in daylight will appear as a pinkish red film under UV light, suggesting the interaction between gold atoms and supported by its luminescence spectrum at 692 nm. Upon heat treatment, the resulting AuNPs-silica in AAO-glass film gave a deep-red colour indicating the successful formation of AuNPs. The presence of AuNPs in the film was further confirmed based on the absorption peak at 545 nm, X-ray diffraction pattern at 38.20 degrees for d111 plane in wide-angle region, transmission electron microscopy images showing a small and sphere shape particles as well as its elemental composition in energy dispersive X-ray analysis. Moreover, scanning electron microscope images also suggested that the AAO pores is fully filled with the composite and is in accordance with its surface roughness study via atomic force microscopy analysis.

Controlled-Release Materials for Remediation of Trichloroethylene Contamination in Groundwater

Groundwater contamination by trichloroethylene (TCE) presents a pressing environmental challenge with far-reaching consequences. Traditional remediation methods have shown limitations in effectively addressing TCE contamination. This study reviews the limitations of conventional remediation techniques and investigates the application of oxidant-based controlled-release materials, including encapsulated, loaded, and gel-based potassium permanganate since the year 2000. Additionally, it examines reductant controlled-release materials and electron donor-release materials such as tetrabutyl orthosilicate (TBOS) and polyhydroxybutyrate (PHB). The findings suggest that controlled-release materials offer a promising avenue for enhancing TCE degradation and promoting groundwater restoration. This study concludes by highlighting the future research directions and the potential of controlled-release materials in addressing TCE contamination challenges.

Tailoring the Morphology of Monodisperse Mesoporous Silica Particles Using Different Alkoxysilanes as Silica Precursors.

The hard template method for the preparation of monodisperse mesoporous silica microspheres (MPSMs) has been established in recent years. In this process, in situ-generated silica nanoparticles (SNPs) enter the porous organic template and control the size and pore parameters of the final MPSMs. Here, the sizes of the deposited SNPs are determined by the hydrolysis and condensation rates of different alkoxysilanes in a base catalyzed sol-gel process. Thus, tetramethyl orthosilicate (TMOS), tetraethyl orthosilicate (TEOS), tetrapropyl orthosilicate (TPOS) and tetrabutyl orthosilicate (TBOS) were sol-gel processed in the presence of amino-functionalized poly (glycidyl methacrylate-co-ethylene glycol dimethacrylate) (p(GMA-co-EDMA)) templates. The size of the final MPSMs covers a broad range of 0.5-7.3 µm and a median pore size distribution from 4.0 to 24.9 nm. Moreover, the specific surface area can be adjusted between 271 and 637 m2 g-1. Also, the properties and morphology of the MPSMs differ according to the SNPs. Furthermore, the combination of different alkoxysilanes allows the individual design of the morphology and pore parameters of the silica particles. Selected MPSMs were packed into columns and successfully applied as stationary phases in high-performance liquid chromatography (HPLC) in the separation of various water-soluble vitamins.

Synthesis of mesoporous organosilica nanoparticles with a high tetrasulphide content and large pores

Tetrasulphide bridged mesoporous organosilica nanoparticles (MONs) with a high sulphur content of ∼11% and a large pore size of ∼14 nm have been synthesized using tetrabutyl orthosilicate (TBOS) as a modulator in the synthetic system. It is shown that the incorporation of TBOS modulates the hydrolysis and co-condensation of inorganic silica and organosilica precursors during the formation of MONs, leading to a higher organosilica content and larger mesopores compared with the conventional synthesis using only tetraethyl orthosilicate (TEOS) as the inorganic silica precursor. Moreover, MONs with a high tetrasulphide content exhibit enhanced GSH oxidation capability, showing their potential in applications where GSH depletion is important.

In situ construction of High-safety and Non-flammable polyimide “Ceramic” Lithium-ion battery separator via SiO2 Nano-Encapsulation

For the purpose of the needs of high-safety energy storage devices, we report a new type of high-performance core–shell structure PI/SiO2 inorganic–organic composite separator. This polymer separator has good flame retardant, strong mechanical properties, high thermal stability and high ion transmission efficiency. Unlike traditional ceramic modified separators, this hybrid separator is achieved by in situ nano-encapsulation hydrolysis. As a precursor of SiO2, Tetrabutyl orthosilicate (TBOS) is selected to coat on PI nanofibers surface, which endows a high retention rate of hydrolyzed silica and a dense/uniform coating. Due to the formation of silica nanoshell, the PI/SiO2 nanofiber separator shows an ultra-high 73.69 MPa tensile strength, a contact angle of only 6.8° and great thermal stability at 378 °C. The NCM811 half-cell equipped with composite separator shows a great capacity of 146 mAh·g−1 at 5C, which is much better than the battery using original PI separator and Celgard-2400 separator. It is worth nothing that the battery with PI/SiO2 separator exhibits superior cycle stability with little energy weaken during 100 cycles. This research provides a new strategy for preparing high-performance non-flammable organic–inorganic composite separators.

Long-term cometabolic transformation of 1,1,1-trichloroethane and 1,4-dioxane by Rhodococcus rhodochrous ATCC 21198 grown on alcohols slowly produced by orthosilicates

Long-term cometabolic transformation of 1,1,1-trichlorethane (1,1,1-TCA) and 1,4-dioxane (1,4-D) was achieved using slow release compounds (SRCs) as growth substrates for pure cultures of Rhodococcus rhodochrous ATCC 21198 (ATCC strain 21198). Resting cell transformation tests showed 1,4-D transformation occurred without a lag phase for cells grown on 2-butanol, while an induction period of several hours was required for 1-butanol grown cells. These observations were consistent with activity-based labeling patterns for monooxygenase hydroxylase components and specific rates of tetrahydrofuran (THF) degradation. 1,1,1-TCA and 1,4-D degradation rates for alcohol-grown cells were slower than those for cells grown on gaseous alkanes such as isobutane. Batch metabolism and degradation tests were performed, in the presence of 1,1,1-TCA and 1,4-D, with the growth of ATCC strain 21198 on alcohols produced by the hydrolysis of orthosilicates. Three orthosilicates were tested: tetrabutylorthosilicate (TBOS), tetra-s-butylorthosilicate (T2BOS), and tetraisopropoxysilane (T2POS). The measured rates of alcohol release in poisoned controls depended on the orthosilicate structure with TBOS, which produced a 1° alcohol (1-butanol), hydrolyzing more rapidly than T2POS and T2BOS, that produced the 2° alcohols 2-butanol and 2-propanol, respectively. The orthosilicates were added as light non-aqueous phase liquids (LNAPLs) with ATCC strain 21198 and formed dispersed droplets when continuously mixed. Continuous rates of oxygen (O2) consumption and carbon dioxide (CO2) production confirmed alcohol metabolism by ATCC strain 21198 was occurring. The rates of metabolism (TBOS > T2POS > T2BOS) were consistent with the rates of alcohol release via abiotic hydrolysis. 1,4-D and 1,1,1-TCA were continuously transformed in successive additions by ATCC strain 21198 over 125 days, with the rates highly correlated with the rates of metabolism. The metabolism of the alcohols was not inhibited by acetylene, while transformation of 1,4-D and 1,1,1-TCA was inhibited by this gas. As acetylene is a potent inactivator of diverse bacterial monooxygenases, these results suggest that monooxygenase activity was required for the observed cometabolic transformations but not for alcohol utilization. Alcohol concentrations in the biologically active reactors were maintained below the levels of detection, indicating they were metabolized rapidly after being produced. Much lower rates of O2 consumption were observed in the reactors containing T2BOS, which has benefits for in-situ bioremediation. The results illustrate the importance of the structure of the SRC when developing passive aerobic cometabolic treatment systems.

Mesoporous Silica Microspheres Composited with SBA-15s for Resonance Frequency Reduction in a Miniature Loudspeaker

Microspheres composited with mesoporous SBA-15 particles and silica were investigated as fillers in miniature loudspeakers to study the factors influencing the resonance frequency offsets(RFOs). Mesoporous silica microspheres(MSMs) were prepared by self-assembling SBA-15 mesoporous silica in a microemulsion synthesis system. The formation process involved the fabrication of a stable O/W microemulsion of tetrabutyl orthosilicate(TBOS) and hexadecyltrimethylammonium bromide(C16TAB) and encapsulation of SBA-15s. The RFO increased and then decreased with increasing particle size(in the length range of 0.7–5.5 µm and in the width range of 0.2–0.45 µm), increased with increasing pore size(in the range of 7.0–9.4 nm) of SBA-15s, and increased with decreasing particle size(105–900 µm) of MSMs.

Preparation and application of VOCs adsorption materials in textile industry

A series of HMS molecular sieves with different pore structures were prepared by using dodecylamine and octadecylamine as template and tetrabutyl orthosilicate as silicon source to study the different pH values and temperatures. Adsorption performance. The physicochemical properties of HMS molecular sieves were characterized by BET, XRD and SEM. The results showed that the HMS molecular sieve material synthesized by dodecylamine as template was obtained after standing for 12 h in water bath for 12 h, pH 2 and calcination temperature was 550 °C. The best adsorption effectis HMS molecular sieve material synthesized by octadecylamine as template agent has the best adsorption effect when the aging time is water bath for 24 h, pH is 10, and calcination temperature is 550 °C. The adsorption rates are up to 71.72% and 74.78%, respectively.

Co-encapsulation of slow release compounds and Rhodococcus rhodochrous ATCC 21198 in gellan gum beads to promote the long-term aerobic cometabolic transformation of 1,1,1-trichloroethane, cis-1,2-dichloroethene and 1,4-dioxane.

Rhodococcus rhodochrous ATCC 21198 (strain ATCC 21198) was successfully co-encapsulated in gellan gum beads with orthosilicates as slow release compounds (SRCs) to support aerobic cometabolism of a mixture of 1,1,1-trichloroethane (1,1,1-TCA), cis-1,2-dichloroethene (cis-DCE), and 1,4-dioxane (1,4-D) at aqueous concentrations ranging from 250 to 1000 μg L-1. Oxygen (O2) consumption and carbon dioxide (CO2) production showed the co-encapsulated cells utilized the alcohols that were released from the co-encapsulated SRCs. Two model SRCs, tetrabutylorthosilicate (TBOS) and tetra-s-butylorthosilicate (T2BOS), which hydrolyze to produce 1- and 2-butanol, respectively, were encapsulated in gellan gum (GG) at mass loadings as high as 10% (w/w), along with strain ATCC 21198. In the GG encapsulated beads, TBOS hydrolyzed 26 times faster than T2BOS and rates were ∼4 times higher in suspension than when encapsulated. In biologically active reactors, the co-encapsulated strain ATCC 21198 effectively utilized the SRC hydrolysis products (1- and 2-butanol) and cometabolized repeated additions of a mixture of 1,1,1-TCA, cis-DCE, and 1,4-D for over 300 days. The transformation followed pseudo-first-order kinetics. Vinyl chloride (VC) and 1,1-dichloroethene (1,1-DCE) were also transformed in the reactors after 250 days. In the long-term treatment, the batch reactors with co-encapsulated T2BOS GG beads achieved similar transformation rates, but at much lower O2 consumption rates than those with TBOS. The results demonstrate that the co-encapsulation technology can be a passive method for the cometabolic treatment of dilute groundwater plumes.

Rational synthesis of silylated Beta zeolites and selective ring opening of 1-methylnaphthalene over the NiW-supported catalysts

Heavy oil has been by-produced from refinery and petrochemical processes, and its use as low-value fuels has been restricted by stricter environmental regulations due to heavy molecules, multi-ring aromatics, and high sulfur content. In a bi-functional catalyst system of metal and zeolitic acid, balancing metallic (from metal element) and acidic function (from zeolite elements) is essential for harnessing the selective ring opening (SRO) reaction with the aim of upgrading the heavy oil. Here, we report a synthetic strategy to control the acid site distribution of Beta zeolite through the silylation reaction with tetramethyl orthosilicate (TMOS), tetraethyl orthosilicate (TEOS), and tetrabutyl orthosilicate (TBOS) as silylation agents. As the size of alkyl chain group in the silylation agents gets larger, the silylation agents were suppressed to spread into the channels and thus the formation of SiO2 layer was intentionally occurred on the external surface of the zeolite. Resulting from the selectively deposited SiO2 layer, NiW metals supported on each silylated Beta zeolite altered the metal distribution and further the balance of metallic and acidic function. NiW catalyst supported on TBOS-silylated Beta zeolite exhibited the best catalytic performance toward the SRO reaction of 1-methylnaphthalene in a fix-bed reaction system, proving the optimal balance of metallic and acidic functions. We expect that this study will benefit the control over the selective silylation reaction in order to optimize the balance of metallic and acidic functions in the bi-functional catalysts, and, hence, to promote properly aromatic saturation (hydrogenation) and ring opening (hydrocracking) for selective ring opening products.

Uniformly dispersed pt nanoparticles as fuel-cell catalyst supported onto ordered mesoporous carbon–silica composites

Ordered mesoporous carbon–silica composites, were synthesized via direct-templating method using soluble phenolic resins as carbon sources, tetrabutyl orthosilicate as SiO2 precursors and triblock copolymer F127 as the structure-directing agent. The structure and the corresponding electrocatalytic activity of carbon–silica composites with various silica contents are systematically investigated. Textual characterization results show that the ordered mesoporous structure of carbon–silica composite with trace SiO2 is well preserved. The electrochemical properties of the supported catalysts were studied by cyclic voltammogram, revealing that ordered mesoporous carbon–silica composites as the support possess excellent electrochemical performance for hydrogen oxidation. The electrochemical active surface area of carbon–silica supported Pt nanoparticles can achieve 63.8m2/g, which is about 7-fold that of non-silica supported Pt catalyst.

Synthesis of Zeolite/Mesoporous Silica Composite Microspheres by Microemulsion Method

Zeolite/mesoporous silica composite microspheres (ZMMS) have been prepared by self-assembling mesoporous silica phase with Y or Ti-MWW zeolites crystallites in a simple microemulsion system. The synthesis process involved the formation of a stable O/W microemulsion from silica precursor of tetrabutyl orthosilicate and cationic quaternary ammonium surfactants as well as a simultaneous assembling of zeolite into the oil phase by their hydrophobic interaction, in which mesoporous silica was formed by self-assembling of surfactant and silica source. Through optimizing synthesis conditions, the ZMMS materials were prepared to possess controllable mass ratio of zeolite to mesoporous silica (0—2.3) and sphere diameter (186—965 μm). The mesopore sizes of the ZMMSs were 3.75 (zeolite-Y/MMSs) and 3.98 nm (Ti-MWW/MMSs). In the liquid-phase ammoximation of cyclohexanone, Ti-MWW/mesoporous silica microspheres showed a high mechanical stability and a catalytic activity comparable to the parent Ti-MWW powders. Keywords zeolite microsphere; micro/mesoporous composite; microemulsion; zeolite-Y; Ti-MWW

Template Sol-Gel Synthesis of Phosphorescent Mesoporous Silica Film Nanocomposites Using an Amphiphilic Gold (I) Pyrazolate Complex

Herein novel mesoporous silica film nanocomposites are successfully synthesized by using phosphorescent columnar assembly of an amphiphilic trinuclear gold (I) pyrazolate complex [Au3Pz3] as a functional template in the sol-gel synthesis. By controlling the molar ratios of silica source tetrabutylorthosilicate (TBOS) to [Au3Pz3] in an acidic aqueous alcohol solution from 60:1 to 20:1, highly ordered phosphorescent nanocomposites can be fabricated with hexagonal [Au3Pz3]/silicahexand lamellar [Au3Pz3]/silicalamsilicates.

Synthesis and characterization of SBA-15 macrospheres with hierarchical pore structure

The new macroscopic-scale SBA-15 spheres with diameter of 0.2–0.5 mm are prepared by a sol–gel method, in which the tetrabutylorthosilicate (TBOS) is used as silicon source and triblock copolymer (P123) and polyoxyethylene octylphenol ether (OP-10) are used as templates. The resulting spherical samples are characterized by XRD, N 2 adsorption–desorption, TEM and SEM methods. The results show that the inner structure of SBA-15 macrospheres has macroporous channels (0.5 μm) and mesoporous skeleton (4–5 nm). These SBA-15 macrospheres with the hierarchical pore structure demonstrate high absorption capacity for Emodin molecules.

Reduction of nitrate by nanoscale zero-valent iron supported on mesoporous silica beads

The use of zero-valent iron (ZVI) represents one of the latest innovative technologies for groundwater remediation. The reactivity of ZVI is enhanced when the particle size is in the nanometer range. However, nanoscale ZVI has limited field applications for in-situ groundwater remediation such as permeable reactive barriers due to its powdery form. Therefore, a method of adhering nanoparticles on a supporting material was suggested. In this paper, functionalized mesoporous silica beads were created using 3-mercaptopropyltrimethoxy silica, tetrabutyl orthosilicate, and cetyltrimethyl ammonium bromide, and their physical and chemical characteristics were measured. The highly active ZVI nanoparticles were adhered on these mesoporous silica beads. The reactivity of the resulting material was tested using nitrate solution. The reductive reaction of nitrate indicated that the degradation of nitrate appeared to be pseudo-first order with a high reaction rate constant of 0.1619 h-1. The reaction constant decreased to 0.0122 h-1 after 3 h of experiment due to mass transfer limitation. The higher dose of the supported nanosized ZVI increased the removal rate as well as the removal efficiency of nitrate.

Synthesis and characterization of novel mesoporous silica with large wormhole-like pores: Use of TBOS as silicon source

SBA-15 was synthesized by hydrothermal process using tetramethyl orthosilicate (TMOS), tetraethyl orthosilicate (TEOS), tetrapropyl orthosilicate (TPOS), and tetrabutyl orthosilicate (TBOS) as silicon source in a stirred tank reactor provided with a mixer. The synthesized samples were characterized by SAXS, BET, TEM and SEM. The materials prepared with TMOS, TEOS and TPOS showed the same textural properties as those of SBA-15. When TBOS was used as silicon source, however, both pore size and particle size were larger than those of the samples prepared with other silicon alkoxides, and the resultant sample showed a three-dimensional wormhole-like pore structure.

Effects of Synthesis Conditions on Macroscopic and Microscopic Properties of Ordered Mesoporous Silica Fibers

Experiments were conducted to prepare ordered mesoporous silica fibers under different conditions (precursor type, temperature, acid concentration, and growth time). The ordered mesoporous silica fibers can be obtained with tetrabutyl orthosilicate as the silica source under the following conditions: temperature at 300 K; and tetrabutyl orthosilicate, cetyltrimethylammonium bromide, HCl, and water molar ratio of 1.0, 0.5, 10−98, and 2000. Synthesis at temperatures above 300 K resulted in ordered mesoporous silica of nonfibrous geometry (films or particles) due to a fast transfer rate of silica source material. A variation in acid concentration in the range of 2.0−6.4 vol % accelerates the formation of fibers with more pore microstructural ordering. Higher acid concentration leads to formation of irregular nonfibrous silica forms besides fibers due to rapid silica hydrolysis/condensation. Under controlled conditions the fibers' diameter becomes larger with a broader distribution for samples with longer gr...

Biomass, Oleate, and Other Possible Substrates for Chloroethene Reductive Dehalogenation

Comparative studies were conducted with benzoate, propionate, oleate, tetrabutyl orthosilicate (TBOS), and biomass as substrates for dehalogenation of cis-1,2-dichloroethene (cDCE). All five substrates supported dehalogenation. Sufficient calcium was required to precipitate oleate and thus reduce its toxicity to the dehalogenating microorganisms. More cDCE was dehalogenated with TBOS than with benzoate, although TBOS initially had an inhibitory effect. The most efficient dehalogenation was associated with biomass, 20% of which was used for dehalogenation, even higher than the 17% obtained with propionate. The advantages and disadvantages of these organic substances for introduction into an aquifer as electron donors for in situ dehalogenation were examined in terms of efficiency of electron use for reductive dehalogenation, and method and ease of introduction into the aquifer. Benzoate and propionate are useful for recirculation systems, while TBOS, oleate, and biomass are appropriate for more passive approaches.

Metal alkoxide primers in the adhesive bonding of mild steel

The effects of metal alkoxide type and relative humidity on the durability of alkoxide-primed, adhesively bonded steel wedge crack specimens have been determined. Aluminum tri-secbutoxide, aluminum tri-tert-butoxide, tetrabutyl orthosilicate, and titanium(IV ) butoxide were used as alkoxide primers. Grit-blasted, acetone-rinsed mild steel adherends were the substrates bonded with epoxy and polyethersulfone. The two aluminum alkoxides significantly enhanced the durability of the adhesively bonded steel, while the titanium alkoxide showed no improvement in durability over a nonprimed control. The silicon alkoxide-primed samples gave an intermediate response. The failure plane in the adhesively bonded samples varied with the relative humidity during the priming process.