Silica-based Materials Research Articles

Study of temperature-adjustment asphalt mixtures based on silica-based composite phase change material and its simulation

In recent years, extreme temperatures have occurred frequently in summer, which is a challenge to asphalt pavement and its surrounding environment. Phase change materials (PCMs) have unique energy storage characteristics, which provide a new idea for alleviating the high-temperature damage of pavement and reducing the environment temperature. In this paper, the silica composite phase change materials (SiO2-PCMs) were prepared by the sol–gel method, and SiO2-PCMs with better performance was applied to the asphalt mixture. The finite element heat transfer model was established by measuring the boundary conditions, and the temperature adjustment effect was predicted and analyzed. SiO2-PCMs meet the mixing temperature requirements of asphalt mixtures and have excellent compatibility, thermal cycle stability and anti-leakage ability. Asphalt mixture with PEG/SiO2 has an excellent temperature adjustment effect, and it can reduce the upper surface temperature of the asphalt mixture by about 9 °C. The high unity of theory and experiment is implemented by establishing the heat transfer model. PCMs reduce the temperature of asphalt pavement by storing and transforming energy, which provides reference and theoretical support for improving the near-surface thermal environment and prolonging the service life of asphalt pavement.

Insight into the development of silica-based materials as photocatalysts for CO2 photoconversion towards CH3OH: A review and recent progress

High exploitation of fossil fuel energy has resulted in substantial CO2 emissions into the atmosphere, leading to severe global warming. Tremendous strategies have been developed to explore possible approaches in minimizing the content of CO2 in the atmosphere. CO2 photoconversion into CH3OH has been put forward as a promising strategy since anthropogenic CO2 is utilized to generate valuable CH3OH assisting by clean solar energy. Silica-based materials have emerged as potential candidates for photocatalysts is accredited to their mesoporous framework with a large surface area, flexible tunability pore sizes, excellent thermal stability, and capability to suppress metal particle growth. Thus, this review encompasses the current progress on applying and developing silica-based materials as photocatalysts for CO2 photoconversion into CH3OH. Apart from that, fundamental aspects of the mechanism, the factors affecting performance, and the efficiency of silica-based materials in CO2 photoconversion to CH3OH are also comprehensively highlighted. The difficulties and prospects of CO2 photoconversion into CH3OH via silica-based materials are also discussed. In general, the most recent scenarios recommended further investigation to explore these materials since CO2 photoconversion to CH3OH has not been adequately investigated in the literature.

Synthesis of Silica-Based Quaternized Adsorption Material and Study on Its Adsorption Behavior for Pu(IV).

In this research, we explored the synthesis optimization of the silica-based quaternized adsorption material (SG-VTS-VPQ) and its adsorption behavior for Pu(IV). By optimizing the synthesis process, the grafting amount of 4-vinylpyridine reached 1.25 mmol·g−1. According to the analysis of NMR and XPS, the quaternization rate of pyridine groups reached 91.13%. In the adsorption experiments, the thermodynamic experiment results show that the adsorption of Pu(IV) by SG-VTS-VPQ is more in line with the Langmuir adsorption model and the adsorption type is a typical chemical adsorption; the kinetic results show that adsorption process is more in line with the pseudo first-order kinetic model, and the larger specific surface area of SG-VTS-VPQ plays an important role in the adsorption. The results of the adsorption mechanism show that the adsorption of Pu(IV) by SG-VTS-VPQ is mainly complex anion Pu(NO3)62− and Pu(NO3)5−. This research provides in-depth and detailed ideas for the surface modification and application of porous silica gel, and at the same time provides a new way to develop the direction of the analysis of pretreatment materials in the spent fuel reprocessing field.

Sol-gel derived silica: A review of polymer-tailored properties for energy and environmental applications

With the continuous growth in global population, energy demands are summoning the development of novel materials with high specific surface areas (SSA) for energy and environmental applications. High-SSA silica-based materials, such as aerogels, are highly popular as they are easy to form and tune. They also provide thermal stability and easy functionalization, which leads to their application in batteries, heavy metal adsorption, and gas capture. However, owing to large pore volumes, high-SSA silica exhibits weak mechanical behavior, requiring enhancement or modification to improve the mechanical properties and make them viable for these applications. The creation of macropores in these mesoporous solids is also desirable for applications utilizing membranes. To facilitate research in these critical areas, this review describes the research into sol-gel formation of silica, as well as polymer-based tailoring carried out in the last decade. Additionally, this review summarizes applications of polymer-tailored high-SSA silica materials in the energy and environmental fields and discusses the challenges associated with implementing and scaling of these materials for these applications. • Polymers are used to tailor the properties of sol-gel derived high specific surface area silicates. • Polymers can be incorporated into silica to improve the mechanical durability. • Polymers can be used as porogens to tailor the microstructure (meso- and macropores). • High specific surface area silicates are used for energy storage and environmental remediation.

Recent advances in amine catalyzed aldol condensations

ABSTRACT During the past two decades, new insights have driven the development and optimization of aminated materials as aldol condensation catalysts. Amines, either primary or secondary, facilitate the reaction via an enamine mechanism. If the spatial placement with respect to the amine allows it, weak acid sites such as silanols or hydroxyls, can cooperate as hydrogen bond donors and aid in proton transfer steps. Furthermore, the reaction environment, i.e., support and solvent and their mutual interactions, is also a key determining factor. In particular, co-feeding small amounts of water suppresses the formation of inhibiting and site-blocking species. However, silica-based materials are susceptible to hydrolysis. This led to the development of water tolerant (bio)polymer supported amine catalysts which also exhibit selective component enrichment properties, opening up opportunities for further catalyst development.

First Evidence of Tris(catecholato)silicate Formation from Hydrolysis of an Alkyl Bis(catecholato)silicate.

The hydrolysis of 3-ammoniumpropylbis(catecholato)silicate 1, giving two different silica-based materials containing different amounts of tris(catecholato)silicate, is reported. The latter species can be formed through an attack of catechol to the silicon atom in the pentacoordinate complex, in which the silicon-carbon bond is further activated toward electrophilic proton cleavage. The Knoevenagel reaction was used as a probe in order to test the availability of functional groups on the surface of such materials.

Achieving blue water-dispersed room-temperature phosphorescence of carbonized polymer dots through nano-compositing with mesoporous silica

Stabilizing triplet excited states is important for room temperature phosphorescence (RTP) materials to achieve multifunctional applications in humid environment. However, due to the lack of preparation strategies, the realization of RTP materials in water still faces challenges. Herein, a new design strategy was presented to achieve RTP in water by confining carbonized polymer dots (CPDs) in amino functional mesoporous silica (MSNs-NH2). The as-prepared MSNs-CPDs aqueous dispersion exhibited blue afterglow, lasting more than 3 s to naked eyes. The triplet excited states were protected from non-radiative deactivation by the double-confinement effect including covalent bonding fixation and mesoporous structure confinement. The MSNs-CPDs inherited the structure of MSNs-NH2, so the stability of morphology and properties were superior to CPDs and even most of silica-based CPDs RTP materials. A water-related encryption technique demonstrated the promising application of MSNs-CPDs as smart materials in the field of information security. Besides, the possibility of potential application in ion detection was also explored.

Hydrothermal crystallization of clathrasils in acidic medium: Energetic aspects

A series of clathrasils, including AST, DOH, MTN, and DDR topologies, was synthesized in an acidic medium. The general composition of the initial system was 1 SiO2: 0.3–0.5 SDA: 0.1–0.5 HF/NH4F: 0–0.3 HBr: 10–50H2O in the pH range of 2–6, where SDA stands for organic amines or ammonium ions as the structure-directing agents. And the hydrothermal syntheses were performed in the 150–200 °C temperature range. Besides elaborating the synthesis recipes and product characterizations, the study also attempted to elucidate the origins of slow crystallization kinetics. It was found that the thermodynamic stabilities of the [email protected]2 compounds play an overwhelming role in the crystalline phase selection. The finding of this study can be used as a guidance of silica-based porous materials synthesis under acidic conditions.

Anchoring of 10-phenylphenothiazine to mesoporous silica materials: A water compatible organic photocatalyst for the degradation of pollutants

• An organic photocatalyst (PTH) has been anchored onto mesoporous silica-based materials. • The PTH-containing materials have been fully characterized by different methods. • The photocatalytic activity of the materials has been tested for degradation of pollutants in water. • The SBA-15-AP-PTH was the most efficient for degrading acetaminophen and diclofenac. The application of organic photocatalysts towards the oxidation of pollutants in water is hampered by different limitations such as their insolubility in the media. Herein, we report that the grafting of a photo-organocatalyst into mesoporous silica materials is an ideal approach to obtain effective catalysts. Thereby, the photocatalyst 10-phenylphenothiazine (PTH) was easily anchored into three different mesoporous silica-based materials (MSN, MSU-2 and SBA-15) with different particle sizes and pore sizes through an amide bond formation. The materials were characterized using IR analysis, solid-state X-ray diffraction, porosity and microscopy (SEM and TEM) techniques, showing that PTH is immobilized inside the pores of the materials and its optical properties are maintained after the anchoring. Although homogeneous PTH was inactive in water media, the three photocatalytic materials were active for the degradation of pollutants. SBA-15-AP-PTH exhibited the highest catalytic performance towards the degradation of acetaminophen and diclofenac under solar irradiation, finding in this manner a new strategy for the decontamination of pollutants.

Targeted synthesis of zeolites from calculated interaction between zeolite structure and organic template.

Zeolites, a class of silica-based porous materials, have been widely employed in the chemical industry for uses such as sorption, separation, catalysis and ion exchange. Normally, the synthesis of zeolites is performed in the presence of organic templates via a trial-and-error route, which is labor-intensive and empirical. In recent years, theoretical simulation from the interaction between a zeolite structure and an organic template has been used to guide the synthesis of zeolites, which is time-saving. In this review, recent progress in the targeted synthesis of zeolites from interaction between a zeolite structure and an organic template are briefly outlined including the design of new templates for zeolite synthesis, preparation of zeolites with new composition, development of novel routes for zeolite synthesis, synthesis of intergrowth zeolites, generation of novel zeolite structures, control of zeolite morphology and modulation of aluminum distribution in zeolites. These targeted syntheses reveal that the minimum energy principle from the theoretical simulation is key for guiding zeolite crystallization. This review will be important for zeolite researchers for rationally synthesizing zeolites and effectively designing new zeolite structures.

Occurrence and Chemistry of Tropane Alkaloids in Foods, with a Focus on Sample Analysis Methods: A Review on Recent Trends and Technological Advances.

Tropane alkaloids (TAs) are natural toxins produced by different plants, mainly from the Solanaceae family. The interest in TAs analysis is due to the serious cases of poisoning that are produced due to the presence of TA-producing plants in a variety of foods. For this reason, in recent years, different analytical methods have been reported for their control. However, the complexity of the matrices makes the sample preparation a critical step for this task. Therefore, this review has focused on (a) collecting the available data in relation to the occurrence of TAs in foods for human consumption and (b) providing the state of the art in food sample preparation (from 2015 to today). Regarding the different food categories, cereals and related products and teas and herbal teas have been the most analyzed. Solid–liquid extraction is still the technique most widely used for sample preparation, although other extraction and purification techniques such as solid-phase extraction or QuEChERS procedure, based on the use of sorbents for extract or clean-up step, are being applied since they allow cleaner extracts. On the other hand, new materials (molecularly imprinted polymers, mesostructured silica-based materials, metal–organic frameworks) are emerging as sorbents to develop effective extraction and purification methods that allow lower limits and matrix effects, being a future trend for the analysis of TAs.

APTES-Modified SBA-15 as a Non-Toxic Carrier for Phenylbutazone.

Improvement of the bioavailability of poorly soluble medicinal substances is currently one of the major challenges for pharmaceutical industry. Enhancing the dissolution rate of those drugs using novel methods allows to increase their bioavailability. In recent years, silica-based mesoporous materials have been proposed as drug delivery systems that augment the dissolution rate. The aim of this study was to analyse the influence of phenylbutazone adsorption on SBA-15 on its dissolution rate. Moreover, we examined the cytotoxicity of the analyzed silica. The material was characterized by SEM, TEM, DSC, 1H-NMR, XRD, and FT-IR. The phenylbutazone did not adsorb on unmodified SBA-15, while the adsorption on APTES-modified SBA-15 resulted in 50.43 mg/g of loaded phenylbutazone. Phenylbutazone adsorbed on the APTES-modified SBA-15 was then released in the hydrochloric acidic medium (pH 1.2) and phosphate buffer (pH 7.4) and compared to the dissolution rate of the crystalline phenylbutazone. The release profiles of the amorphous form of adsorbed phenylbutazone are constant in different pH, while the dissolution rate of the crystalline phenylbutazone depends on the pH. The cytotoxicity assays were performed using the Caco-2 cell line. Our results indicate that the analyzed material ensured phenylbutazone adsorption in an amorphous state inside the mesopores and increased its dissolution rate in various pH levels. Furthermore, the cytotoxicity assay proved safety of studied material. Our study demonstrated that APTES-modified SBA-15 can serve as a non-toxic drug carrier that improves the bioavailability of phenylbutazone.

Rational Design of a Novel Silica-Based Material with Abundant Open Micropores for Efficient Voc Removal

Rational Design of a Novel Silica-Based Material with Abundant Open Micropores for Efficient Voc Removal

Study of Temperature-Adjustment Asphalt Mixtures Based on Silica-Based Composite Phase Change Material and its Simulation

Study of Temperature-Adjustment Asphalt Mixtures Based on Silica-Based Composite Phase Change Material and its Simulation

Synthesis of silica-based solids by sol-gel technique using lemon bio-waste: Juice, peels and ethanolic extract

After the consumption of the edible part, the citrus fruits are thrown into landfills generating serious pollution and disposal problems. Therefore, the use of citrus fruits for engineering applications has a dual purpose: to generate wealth from waste as an efficient reduction of solid waste. The main objective was to obtain silica-based materials from the precursor (TEOS), replacing acetic acid in acid hydrolysis with different parts of a lemon: peel, juice and peel ethanol extract.The solids obtained were characterized with different techniques such as TEM, SEM, FT-IR, potentiometric titration and XRD. TEM and SEM images were compared with the synthesized pure silica to contrast the morphology of the acidic hydrolysis with lemon. It can be concluded, in general terms, that the proposed objectives have been achieved, since materials were synthesized through a simple and fast method of obtaining, which allowed their inclusion in oxidic matrices. Until now, few attempts have been made to highlight the renewability of reagents used in the synthesis or to incorporate bio-based catalytic processes in larger scales. However, this research contributes to areas of environmentally friendly materials and synthesis, due to the synthesized solids could be used as a support in eco-catalysts.

The challenge of silanol species characterization in zeolites

The chemistry of silica-based materials, including zeolites, is strongly influenced by the nature and number of their silanols.

Decoloration and Alkaloid Enrichment of Dactylicapnos Scandens Extracts Based on Strong Anion-Exchange Resins in Tandem with Strong Cation-Exchange Silica-Based Materials

Decoloration and Alkaloid Enrichment of Dactylicapnos Scandens Extracts Based on Strong Anion-Exchange Resins in Tandem with Strong Cation-Exchange Silica-Based Materials

Structural investigation of phosphonium-based ionic liquid impregnated mesostructured silica nanoparticles and application towards the adsorption of Pb(II)

Adsorption has been widely used in waste water treatment due to its simplicity and cost-effective process. One of the popular adsorbent was silica due to their advantageous properties. Immobilizing additive onto particular adsorbent is one of the way to enhance adsorption capacity. Immobilizing ionic liquid (IL) onto silica-based support could alleviate the drawbacks of IL and enhance the adsorption capacity. Thus, silica-based materials, silica and mesostructured silica nanoparticle (MSN), were impregnated with a phosphonium-based ionic liquid (IL), trioctyldodecylphosphonium bromide (P8,8,8,12Br), which was designated as IL@SIL and IL@MSN. The structural variation of the support greatly impact the adsorbent performance. The results showed that IL@MSN with superior surface properties exhibit a faster reaction kinetic and lower thermodynamic barrier for the adsorption of Pb(II). Both adsorbents followed a pseudo second-order kinetic and chemically adsorbed Pb(II). IL@MSN showed a higher adsorption capacity in both batch and column adsorption than that of IL@SIL. The equilibrium data of both adsorbents fitted well with the Freundlich isotherm model with maximum adsorption capacity of 256.4 and 142.9 mg g−1 for IL@MSN and IL@SIL, respectively. In agreement with the batch experiment, IL@MSN showed a higher adsorption capacity in column adsorption than that of IL@SIL (325.6 and 242.2, respectively). Column adsorption with IL@MSN was able to achieve 94% removal of Pb(II) while IL@SIL achieved 70%. Superior surface properties of IL@MSN allowed a longer duration of column exhaustion than that of IL@SIL. The column experimental data showed a good fit with the Thomas model. Immobilized IL on silica based materials has potential as an adsorbent for heavy metals and structural variation over the support material played an important role.

The Role of Transmission Electron Microscopy in the Early Development of Mesoporous Materials for Tissue Regeneration and Drug Delivery Applications.

For the last 20 years, silica-based mesoporous materials have provided a sound platform for the development of biomedical technology applied to tissue engineering and drug delivery. Their unique structural and textural characteristics, chiefly, the ordered distribution of homogeneous and tunable pores with high surface areas and large pore volume, and their excellent biocompatibility provide an excellent starting point for bone tissue regeneration on the mesoporous surface, and also to load species of interest inside the pores. Adequate control of the synthesis conditions and functionalization of the mesoporous surface are critical factors in the design of new systems that are suitable for use in specific medical applications. Simultaneously, the use of appropriate characterization techniques in the several stages of design and manufacture of mesoporous particles allows us to ascertain the textural, structural and compositional modifications induced during the synthesis, functionalization and post-in vitro assays processes. In this scenario, the present paper shows, through several examples, the role of transmission electron microscopy and associated spectroscopic techniques in the search for useful information in the early design stages of mesoporous systems, with application in the fields of tissue regeneration and drug delivery systems.

Synthesis of Silica-Based Solid-Acid Catalyst Material as a Potential Osteochondral Repair Model In Vitro

For osteochondral damage, the pH value change of the damaged site will influence the repair efficacy of the patient. For better understanding the mechanism of the acid-base effect, the construction of in vitro model is undoubtedly a simple and interesting work to evaluate the influence. Here, a novel porous silica-based solid-acid catalyst material was prepared by additive manufacturing technology, exhibiting improved eliminating effects of the residue. SEM, FTIR, and TGA were used to characterize the morphology, structure, and thermal stability of the synthesized 3D material. The reaction between 4-methoxybenzyl alcohol and 3, 4-dihydro-2H-pyran was used as a template reaction to evaluate the eliminating performance of the 3D porous material. Solvents were optimized, and three reaction groups in the presence of 3D SiO2, 3D SiO2-SO3H, and 3D SiO2-NH-SO3H, as well as one without catalyst, were compared. In addition, in consideration of the complicated situation of the physiological environment in vivo, universality of the synthesized 3D SiO2-NH-SO3H catalyst material was studied with different alcohols. The results showed that the sulfonic acid-grafted 3D material had excellent catalytic performance, achieving a yield over 95% in only 20 min. Besides, the catalyst material can be recycled at least 10 times, with yields still higher than 90%. Such a solid catalyst material is expected to have great potential in additive manufacturing because the catalyst material is easy-recyclable, renewable and biocompatible. The 3D material with connective channels may also be utilized as an in vitro model for environment evaluation of osteochondral repair in the future.