Papers by Keyword: Mesoporous Silica

Abstract: Emissions are substances that enter the air, whether or not they have the potential as pollutants. Emission gases can have adverse effects on the health of living beings, especially humans, and can contribute to an increase in the Earth's temperature. Therefore, separation efforts are needed to minimize the negative impacts caused by them. Adsorption method was categorized as absorption, cryogenic distillation, and membrane. Although there were shortcomings in adsorbing emission gases through the method, it remained a promising approach. Adsorption was recognized for its economic viability, technological effectiveness, thermally stability, corrosion resistance, high load capacity, and tunable surface properties. However, adsorption materials were categorized as porous carbon, zeolites, metal-organic frameworks (MOFs), porous polymers, and porous silica. A significant limitation of the method was its susceptibility to decreased capacity in the presence of water vapor. The analysis results showed that porous silica became a superior adsorption material due to its high porosity, which facilitated rapid gas diffusion. To enhance selectivity and adjust pore size, material modifications, particularly silica, became necessary. This showed that surface modification for silicasupported the improvements in selectivity and pore size.

Abstract: This manuscript presents a novel instant additive for elastomeric polymers, specifically focusing on the modification of synthesized mesoporous silica using carbonyl telechelic natural rubber (CTNR). The surface of mesoporous silica particles was modified using a two-step approach. In the first step, a strategy involving the grafting of 3-aminopropyltriethoxysilane (APTES) onto the silica particles was employed. Subsequently, in the second step, a Schiff's base reaction was carried out between the aldehyde functional group of CTNR and the amines on the modified silica surface. The grafting percentage achieved through this process was determined to be 4.70%. This novel instant additive has the potential to enhance the properties and performance of elastomeric polymers by leveraging the unique characteristics of CTNR and the mesoporous silica surface. Further investigations and applications of this additive can contribute to advancements in the field of elastomeric polymer materials.

Abstract: Targeted drug delivery systems with nanomaterials as drug carriers to specific organs can increase the therapeutic effect and reduce the side effects. Magnetic mesoporous silica nanoparticles are a multifunctional platform in drug delivery and magnetic hyperthermia therapy. In this study, the synthesis was developed with iron sand from Glagah Beach as a source for the magnetic nanoparticles formation and CTAB as a surfactant template. The research method was carried out in three steps, including the synthesis of magnetic nanoparticles (Fe₃O₄), coating of magnetic nanoparticles (Fe₃O₄@SiO₂), and surfactant-templating (Fe₃O₄@SiO₂@CTAB/SiO₂).The SEM analysis results showed that the Fe₃O₄ particles have various sizes. The weight concentration of Fe in Fe₃O₄ increased from 70.25% to 78.58% compared to Fe in iron sand by EDX analysis. The XRD results showed that the crystalline size of Fe₃O₄ and Fe₃O₄@SiO₂ particles are 6.31 nm and 2.37 nm, respectively. From the results of BET analysis, it is known that the longer sonication time, the pore diameter tends to decrease. It may be due to CTAB filling in the pore during the surfactant-templating process. The highest surface area of Fe₃O₄@SiO₂@CTAB/SiO₂ particle obtained was 14.31 m²/g with a pore diameter of 3.915 nm which has a mesoporous structure.

Abstract: Mesoporous silica nanoparticles were synthesized via sol–gel method to produce uniform size nanoparticles using n-Octadecyl-trimethoxy silane which gives a good dispersion of silica nanoparticles in hydrophobic mediums. Scanning electron microscopy (SEM), infrared spectroscopy, X-ray diffraction (XRD), thermal gravimetric analysis, and nitrogen adsorption-desorption tests were used to thoroughly investigate the nanocomposites' morphology and structure. BET results show a high surface are of 760 m²/g and specific high pore size (30Ȧ) and pore volume (0.336 cm³/g). The SEM results present that the mesoporous silica nanoparticles possess a well dispersed and uniform particle morphology and FTIR interpenetrating the well-prepared silica nanoparticles which possess Si-O-Si and Si-O bond. The XRD analysis confirmed the amorphous nature silica nanoparticles. The electrochemical properties of silica nanoparticles were evaluated in a potassium chloride solution. With the advantages of a large specific surface area and a suitable pore size distribution, a pair of broad and symmetric redox peaks centred at -0.15 V and 0.6 V appears. Mesoporous silica with a large effective specific surface area demonstrated excellent electrochemical performance, making them excellent candidates for supercapacitors and fuel cells.

Abstract: DME has been received the attention as a renewable energy due to its thermal efficiencies equivalent to diesel fuel, lower NO_x emission, near-zero smoke and non-toxic. DME can be obtained by methanol dehydration over solid acid catalysts or directly from syngas over bifunctional catalysts. The catalytic dehydration of methanol to DME has been widely studied in the literature over pure or modified γ -aluminas (γ-Al₂O₃) and zeolites. Mesoporous silica has obtained much consideration due to its well-defined structural order, high surface area, and tunable pore diameter. In this work, sulfonic acid and aluminium modified mesoporous silica were synthesized and tested as catalysts for production of dimethyl ether from methanol. The modified silicas were studied utilizing XRD, N₂ physisorption, pyridine adsorption, and scanning electronic microscopy. The effects of reaction temperature and water deactivation on the methanol selectivity and conversion to dimethyl ether were investigated. Sulfonic acid modified mesoporous silica showed higher selectivity and stability of DME than that of aluminosilicate. The grafting of mesoporous silica with sulfonic groups displayed much more enhanced hydrothermal stability than Al-MCM-41 and γ-Al₂O₃.

Abstract: Synthesis of Ni-NH₂/mesoporous silica bifunctional catalyst for conversion of used cooking oil into biofuel was carried out. The impregnation of Ni into the MS8 with a specific surface area of 666.6 m²/g, volume pore of 0.46 cm³/g, and diameter pore of 4.9 nm was done by wet impregnation method. The functionalization of NH₂ into the MS8 and Ni/MS8 was done by the grafting method. The catalytic activity test in used cooking oil hydrocracking was done by thermal (without catalyst), catalyst physical mixture of Ni/MS8 and NH₂/MS8, and Ni-NH₂/MS8 bifunctional catalyst. The results showed that the Ni/MS8 catalyst with acidity values ​​of 12.804 mmol/g was successfully modified with amine groups to produce Ni-NH₂/MS8 bifunctional catalyst. This catalyst was utilized in the hydrocracking process of used cooking oil to produce the highest liquid product of 92.85 wt.% with the selectivity of gasoline and diesel fractions of 4.04 and 63.35 wt.% respectively.

Abstract: The aim of this research is to synthesize mesoporous silica directly from the bottom ash waste through the melting method using alkali at high temperatures. The resulting mesoporous silica will be used as CH₄ gas adsorbent. The bottom ash waste was firstly separated by Fe and Ca using 37% HCl followed by melting at high temperatures and producing silica extract. The extract will be used as the basic material for making mesoporous silica which impregnation with PEG 4000. The resulting solids will then be characterized using XRD and BET. The result of mesoporous silica was then carried out by measuring CH₄ gas adsorption capacity by gravimetric method with interval temperature of 30, 40, and 50 °C and pressure of 1, 3, and 5 atm.

Abstract: Mesoporous silica (MPS) coatings on β-tricalcium phosphate (β-TCP) granules and their protein adsorptive capabilities were studied. β-TCP granules containing 2 wt% of aluminum oxide and 6 wt% of silicon oxide were prepared using a pan-type granulator and heated at 1200 oC. MPS coatings on β-TCP granules was carried out by a dip-coating method, but the β-TCP granules were not covered by the MPS particles. A silica interlayer was formed on the β-TCP granules via magnetron sputtering prior to the coating of the MPS. The β-TCP granules coated with the silica interlayer were fully covered by the MPS particles. A silica interlayer may offer bonding between the β-TCP granules and MPS coating. The adsorption of protein on the MPS-coated β-TCP granules was evaluated by UV-VIS spectroscopy. The adsorption capacity of protein on the β-TCP granules was improved by the MPS coatings on the β-TCP granules, and that of the β-TCP granules coated with the silica interlayer showed a higher protein adsorption capacity.

Abstract: Spherical phosphorus–containing mesoporous silica (PMPS) particles were synthesized. In the PMPS particle preparation using the cationic surfactant (cetyltrimethylammonium bromide) as the template, the amphiphilic surfactant (Pluronic P123) and diethyl(2–bromoethyl)phosphonate were used for the particle shape control and the phosphorus source, respectively. Furthermore, we investigated the chemical reactions of the PMPS particles in simulated body fluid (SBF). By the phosphorus–containing, the hydroxyapatite formation and silicate ion dissolution ability on the PMPS particle surfaces were enhanced. These characteristic features will be useful for the biomedical applications such as bone formation.

Abstract: Attractive for MEMS, PZT thick films are often microstructured on Si supporting platforms to span the gap between ceramics and thin film technologies. Printing process might lead to lower cost than ceramic process to open routes for MEMS applications. In this paper processing by screen-printing of Au/PZT/Au thick-films supported on alumina or completely released from the substrate are described. Investigations of the film microstructures nevertheless show lower densification than those of bulk ceramics. Prior to selective coating deposition, routes to improve the reduction of the film’s porosity are proposed.