Silica Particle Size Research Articles

SO2 Adsorption and Kinetics Analysis during Supported Triethanolamine Acetate Ionic Liquid Desulfurization.

Ionic liquid desulfurization is an effective method for achieving green and circulating desulfurization. To overcome the negative impact of the high viscosity of ionic liquids on the desulfurization process, an economical and efficient supported ionic liquid-triethanolamine acetate ionic liquid/silica (TAIL/SiO2) was prepared in this study. TAIL is synthesized using triethanolamine and acetic acid and subsequently loaded onto silica gel particles. The effects of the reaction temperature, humidity, silica particle size, and loading ratio on SO2 adsorption are investigated using a fixed-bed reactor. The results indicate that the surface of the silica gel loaded with ionic liquid formed uneven spherical clusters, and the aggregate volume increased with an increase in the loading ratio. The TAIL/SiO2 sulfur capacity could be effectively increased by increasing the loading ratio (exceeding 0.74 is unfavorable), decreasing the silica particle size, and reducing the reaction temperature and moisture content. The maximum sulfur capacity can reach 124.98 mg SO2/(g TAIL/SiO2) under experimental conditions, which is higher than that of activated carbon. The Bangham rate model effectively predicts the kinetics of the adsorption process of SO2.

Synthesis and Evaluation of a Chitosan-Silica-Based Bone Substitute for Tissue Engineering.

Bone defects have prompted the development of biomaterial-based bone substitutes for restoring the affected tissue completely. Although many biomaterials have been designed and evaluated, the combination of properties required in a biomaterial for bone tissue engineering still poses a challenge. In this study, a chitosan-silica-based biocomposite was synthetized, and its physicochemical characteristics and biocompatibility were characterized, with the aim of exploring the advantages and drawbacks of its use in bone tissue engineering. Dynamic light scattering measurements showed that the mean hydrodynamic size of solid silica particles (Sol-Si) was 482 ± 3 nm. Scanning electron microscopy of the biocomposite showed that Sol-Si were homogenously distributed within the chitosan (CS) matrix. The biocomposite swelled rapidly and was observed to have no cytotoxic effect on the [3T3] cell line within 24 h. Biocompatibility was also analyzed in vivo 14 days post-implant using a murine experimental model (Wistar rats). The biocomposite was implanted in the medullary compartment of both tibiae (n = 12). Histologically, no acute inflammatory infiltrate or multinucleated giant cells associated to the biocomposite were observed, indicating good biocompatibility. At the tissue-biocomposite interface, there was new formation of woven bone tissue in close contact with the biocomposite surface (osseointegration). The new bone formation may be attributed to the action of silica. Free silica particles originating from the biocomposite were observed at the tissue-biocomposite interface. According to our results, the biocomposite may act as a template for cellular interactions and extracellular matrix formation, providing a structural support for new bone tissue formation. The CS/Sol-Si biocomposite may act as a Si reservoir, promoting new bone formation. A scaffold with these properties is essential for cell differentiation and filling a bone defect.

Spray-Dried Photonic Balls with a Disordered/Ordered Hybrid Structure for Shear-Stress Indication.

Optical microscale shear-stress indicator particles are of interest for the in situ recording of localized forces, e.g., during 3D printing or smart skins in robotic applications. Recently developed particle systems are based on optical responses enabled by integrated organic dyes. They thus suffer from potential chemical instability and cross-sensitivities toward humidity or temperature. These drawbacks can be circumvented using photonic balls as shear-stress indicator particles, which employ structural color as the element to record forces. Here, such photonic balls are prepared from silica and iron oxide nanoparticles via the scalable and fast spray-drying technique. Process parameters to create photonic balls with a disordered core and an ordered particle structure toward the exterior of the supraparticles are reported. This hybrid disordered-ordered structure is responsible for a color loss of the indicator particles during shear-stress application because of irreversible structural destruction. By adjusting the primary silica particle sizes, nearly all colors of the visible spectrum can be achieved and the sensitivity of the response to shear stress can be adjusted.

High Surface Area Silica Particles Using Anionic Surfactant Template Prepared by One-step Spray Drying System for Dye Removal Application

This study reported the effect of sodium lauryl sulfate (SLS) as a template on silica morphology and its properties. The precursor was prepared by producing silica nanofluid by the sol-gel method and mixed with various SLS concentrations. After that, the precursor was spray-dried to generate silica powder. An increase in SLS concentration up to 2 critical micelle concentration (CMC) indicates an increase in the silica particle size from 2.12 μm in untemplated silica particles to 2.58 μm. On the other hand, when the SLS concentration increases to 3 CMC, the particle size decreases to 2.19 μm. A significant increase in total pore volume and surface area is obtained for silica particles synthesized at least at the SLS concentration of 2 CMC, around eight higher volumes than without SLS addition. In addition, they have a macropore compared to silica particles synthesized without SLS addition that only exhibits mesopore. The surface area was 1,011 m2/g for the SLS concentration at 3 CMC, whereas the silica without SLS has only a surface area of 131 m2/g. The SLS concentration at 2 CMC or higher leads to a significant increase in its physical properties because the micelle formation is enough for sacrificed template formation. Methylene blue solution was used as an adsorbate for evaluating the dye adsorption capacity that followed the Langmuir isothermal adsorption model. The highest theoretical maximum monolayer adsorption capacity was 142.9 mg/g, obtained by silica adsorbent with the SLS concentration at 3 CMC.

Primary study of synthesis and dispersion of zirconia and silica nanoparticles for post-endodontic composite

Zirconia and silica-based composite are introduced as an alternative to post-core systems due to their high elastic modulus. The cast metal post-core systems in the application of dental material can cause stress concentration within the surrounding radicular dentin, resulting in root fractures. These materials provide more esthetical appealing and biocompatible restorations. However, the use of zirconia and silica nanoparticles as fillers tends to agglomerate in an organic solvent. The objective of the present report is to synthesize zirconia and silica nanoparticles by solgel method and subsequently, disperse them in an organic solvent by beads milling methods. The particle size distribution and stability were observed correspondingly using the particles size analyzer (PSA) and zeta potential. The initial average sizes of silica and zirconia particles in organic media were correspondingly 2.7 mm and 191 nm, respectively. After beads milling for 5 hours, silica and zirconia nanoparticles successfully were dispersed with average particles size of 91.5 nm and 124 nm, respectively. The zeta potentials of silica and zirconia suspensions were - 21.1 and -10.6 mV, respectively. The SEM image for both particles showed spherical morphology with agglomerated particles having primary particle sizes below 100 nm. Therefore, it was concluded that both particles can be applied as filler for a post-endodontic composite with an additional surfactant before polymerization.

Synthesis of Stober silica nanoparticles in solvent environments with different Hansen solubility parameters

• Changing the solvent in the Stober synthesis is a good tool to control particle size. • The addition of non-polar liquids results formation of smaller particles. • Dispersion and polar thermodynamic parameters influence on nanoparticle size. • A decrease of hydrogen interaction index leads to size increase of nanoparticles. The most commonly used technique for obtaining SiO 2 nanoparticles of controlled size is the Stober synthesis. In this paper, a series of Stober syntheses in media with different thermodynamic parameters are described and the obtained nanoparticles were characterized by electron microscopy. As a result, it was shown that the solvent variation in the Stober synthesis is a working tool for controlling the particle size of silica. The addition of nonpolar liquids to the reaction mixture led to the formation of smaller particles. Also, it was found that an increase in the dispersion and polar parameters of the solvent leads to an increase in the size of the resulting SiO 2 nanoparticles. The same observations were obtained with a decrease in the index of hydrogen interactions between solvent molecules.

Synthesis and Spatial Order Characterization of Controlled Silica Particle Sizes Organized as Photonic Crystals Arrays.

The natural occurrence of precious opals, consisting of highly organized silica particles, has prompted interest in the synthesis and formation of these structures. Previous research has shown that a highly organized photonic crystal (PhC) array is only possible when it is based on a low polydispersity index (PDI) sample of particles. In this study, a solvent-only variation method is used to synthesize different sizes of silica particles (SiPs) by following the traditional sol-gel Stöber approach. The controlled rate of the addition of the reagents promoted the homogeneity of the nucleation and growth of the spherical silica particles, which in turn yielded a low PDI. The opalescent PhC were obtained via self-assembly of these particles using a solvent evaporation method. Analysis of the spatial statistics, using Voronoi tessellations, pair correlation functions, and bond order analysis showed that the successfully formed arrays showed a high degree of quasi-hexagonal (hexatic) organization, with both global and local order. Highly organized PhC show potential for developing future materials with tunable structural reflective properties, such as solar cells, sensing materials, and coatings, among others.

Parametric optimisation of shear thickening fluid treatment for ultra-high molecular weight polyethylene woven fabric

The shear thickening fluid (STF) treatment enhances the low and high velocity impact resistance performances of para-aramid woven fabrics for soft armour application. This research investigates the effects of important parameters on the STF add on and impact energy absorption with the aim to develop a hybrid soft armour. The STF add-on on ultra-high molecular weight polyethylene (UHMWPE) woven fabrics was varied by altering the silica particle size, dilution ratio of STF and padding pressure. The results of the full factorial design of experiment showed that the energy absorption is independent of the add-on. Further, a soft armour panel (SAP) was made from the STF treated woven fabric. The ballistic performance of the panel was evaluated in terms of back face signature (BFS) against a 9 × 19 mm lead core bullet and was compared to that of a weight equivalent untreated panel. A hybrid SAP with unidirectional (UD) laminates of UHMWPE as strike face layers and STF treated woven fabrics as backing layers was prepared, and the BFS was found to be equivalent to that of a SAP containing 100% UD laminates (∼30 mm). The results imply that a certain number of UD laminate layers can be replaced with STF treated flexible woven fabrics without compromising on the ballistic performance of SAP.

The influence of inorganic fillers on the light transmission through resin-matrix composites during the light-curing procedure: an integrative review.

The objective of this study was to perform an integrative review on the effect the inorganic fillers on the light transmission through the resin-matrix composites during the light-curing procedure. A bibliographic review was performed on PubMed using the following search terms: "fillers" OR "particle" AND "light curing" OR "polymerization" AND "light transmission" OR "light absorption" OR "light irradiance" OR "light attenuation" OR "light diffusion" AND "resin composite." The search involvedarticles published in English language in the last 10years. Selected studies reported a decrease in biaxial strength and hardness in traditional resin-matrix composites in function ofthe depth of polymerization. However, there were no significant differences in biaxial strength and hardness recorded along the polymerization depth of Bulk-Fill™ composites. Strength and hardness were enhanced by increasing the size and content of inorganic fillers although some studies revealed a progressive decrease in the degree of conversion on increasing silica particle size. The translucency of glass-ceramic spherical fillers promoted light diffusion mainly in critical situations such as in the case of deep proximal regions of resin-matrix composites. The amount of light transmitted through the resin-matrixcomposites is influenced by the size, content, microstructure, and shape of the inorganic filler particles. The decrease of the degree of conversion affects negatively the physical and mechanical properties of the resin-matrix composites. The type and content of inorganic fillers in the chemical composition of resin-matrix composites do affect their polymerization. As a consequence, the clinical performance of resin-matrix composites can be compromised leading to variable physical properties and degradation. The polymerization mode of resin-matrix composites can be improved according to the type of inorganic fillers in their chemical composition.

Role of ionic concentration in the kinetic attachment of kaolinite and sand

Clay particle deposition in porous media is critical in many geotechnical applications that rely on filtration. The deposition of particles in the filter medium can result in clogging, which causes a reduction in the hydraulic conductivity of the filter medium. Particle attachment and detachment are a function of the interaction energy between clay particles and the filter bed material, which is frequently sand. These mechanisms are governed by the size of the clay particles as well as the solution chemistry. Batch kinetic adsorption tests were carried out to investigate the impact of ionic strength on the attachment of kaolinite to silica sand grains. Significant attachment of kaolinite was observed as ionic strength of the pore fluid increased and as the size of silica particles decreased. The short-term deposition of clay particles was not sensitive to ionic strength; however, in contrast, long-term deposition was a strong function of ionic strength.

Controlling the particle size of spherical silica by adjusting the gas flow environment around the flame

To synthesize silica particles, a dry process consisting of burning an organosilicon compound as raw monomer has been widely studied. Previously, we used six starting materials in the dry process and investigated the effects of monomer species on the particle shape and size of silica. Here, we fixed the raw monomer species and amount of gas supplied from the burner and focused on the relationship between the gas environment around the flame and silica particle size. Specifically, we focused on quaternary gas flowing around the flame as a factor that affected the temperature around the flame. Its flow rate and velocity were expected to directly affect the temperature around the flame. We established the relationship between the temperature environment around the flame, specifically the amount of heat absorbed by the hot water for cooling the reactor and silica particle sizes. The temperature environment around the flame was determined by the balance between the reactor's size and amount of quaternary gas. Simultaneously, it was emitted as the amount of heat absorbed per unit heat transfer area of hot water. Consequently, we concluded that the environment around the flame determined the size of spherical silica particles and successfully controlled the particle size. This article is protected by copyright. All rights reserved

Preparation and particle size effects study of sustainable self-cleaning and durable silicon materials with superhydrophobic surface performance

Superhydrophobic materials with surface drying, self-cleaning, and antibiological pollution characters are broadly used in biotechnology, medicine, and shipbuilding sectors. In this paper, micro-nano silica is modified using a silane-based coupling agent. An organosilicon compound is grafted to the silica surface to obtain a superhydrophobic material with low surface energy. The results show that the superhydrophobic material with a 20 nm particle size silica modified with vinyltriethoxysilane (VTES-SiO2) offers the best properties with a contact angle of 163.32° and a rolling angle of smaller than 3°. Compared with the raw material, the treated silica reveals superhydrophobicity under nano conditions with a rolling angle smaller than 3°. The wettability of the prepared material does not decrease after being placed in the air for 3 months. Moreover, it still maintains self-cleaning performance after being placed in water for one month, showing the potential of long-term use of the material. The prepared materials provide excellent superhydrophobic properties while is environmentally friendly. Thus, this study delivers potential value for the preparation of environmentally friendly superhydrophobic materials with broad application prospects of superhydrophobicity and self-cleaning characters.

Dual-Colored Janus Microspheres with Photonic and Plasmonic Faces.

Photonic and plasmonic colors, stemming from nanostructures of dielectric materials and metals, are promising for pigment-free coloration. In particular, nanostructures with structural colors have been employed in stimuli-responsive Janus microparticles to provide active color pixels. Here, the authors report a simple strategy to produce electro-responsive Janus microspheres composed of photonic and plasmonic faces for active color change. The photonic microspheres are first prepared by self-assembly of silica particles in emulsion droplets of photocurable resin. The silica particles form 3D crystalline arrays in the interior and 2D hexagonal arrays on the interface. The emulsion droplets are photocured and the silica particles are selectively removed to make porous photonic microspheres with hexagonal arrays of dimples on the surface. Directional deposition of gold or aluminum on the photonic microsphere develops plasmonic color on the top hemisphere while maintaining photonic color on the bottom hemisphere. Moreover, the metal deposited on one side renders the Janus microspheres electro-responsive. Therefore, the photonic and plasmonic colors are switchable by the orientation control of the Janus microspheres with an external electric field. The photonic and plasmonic colors are independently adjustable by employing two different sizes of silica particles in core-shell emulsion drops.

Heterocoagulation simulation of nano alumina and silica particle dispersion using discrete element method

Abstract Heterocoagulation in alumina–silica suspension is studied using 2-dimensional discrete element method simulations. Controlling the structure and stability of the binary suspensions via selecting the appropriate size of precursors is crucial in ceramics processing. Alumina and silica particles with a broad range of sizes and size ratios are investigated. The size and the size ratio determine the degree of heterocoagulation and impact the suspension’s structure. Analyzing simulation results shows that when the sizes of silica and alumina particles are comparable, and the radii of particles are below 300 nm, a chain-like structure is formed. In suspensions with high size asymmetry, smaller silica particles surround larger alumina particles, and the degree of heterocoagulation is dependent on the composition of the suspension. The results show that suspension composition can also be used to tune the heterocoagulation structure.

Transport properties of radiation vulcanized natural rubber latex nanocomposites

Radiation vulcanized natural rubber latex (RVNRL) nanocomposites were prepared by the incorporation of aqueous dispersions of nanosilica and nanoclay in RVNRL latex. The sorption, diffusion, and permeation coefficients of the composites were measured at 303 K. The magnitude of the diffusion coefficient showed a decreasing trend in RVNRL/nanosilica composites followed by nanoclay and china clay composites. The diffusion of solvent through rubber followed a first-order kinetics. The transport phenomenon was found to follow an anomalous behaviour. XRD analysis showed that nano silica particles were homogeneously distributed in the rubber matrix. The particle size of the nano silica is 10 nm as confirmed from TEM analysis. RVNRL/nano silica composites showed better dispersion of filler particles in natural rubber.

The effect of using solvent medium in the ultrasonication of silica precipitates

In this study, further processing of silica precipitated from sodium silicate was carried out using an ultrasonic transducer. The ultrasonication process was carried out with the aim to obtain smaller particles and uniform distribution of silica precipitated. The ultrasonication process was carried out using three solvents medium in water, ethanol, and ethylene glycol. The effect of solvents used on the distribution and particle size of silica precipitated was observed using Scanning Electron Microscopy-Energy Dispersive X-Ray (SEM-EDX) and Particle Size Analyzer (PSA). From the results of observations using FE-SEM, it was shown that the ultrasonication of silica precipitates with water has the greatest influence on particle size and distribution. While the analysis using PSA did not show any size reduction due to the agglomeration between the particles. The smallest particle size that could be obtained from this process is about 17 nm with average value of 88 nm.

Preparation of Natural Rubber Composites with High Silica Contents Using a Wet Mixing Process.

A wet mixing process is proposed for filled rubber composites with a high silica loading to overcome the drawbacks of high energy consumption and workplace contamination of the conventional dry mixing process. Ball milling was adopted for preparing the silica dispersion because it has a simple structure, is easy to operate, and is a low-cost process that can be easily scaled up for industrial production. The response surface methodology was used to optimize the making of the silica dispersion. The optimum conditions for a well-dispersed silica suspension with the smallest silica particle size of 4.9 mm were an about 22% silica content and 62 h of ball milling. The effects of dry and wet mixing methods on the properties of silica-filled rubber composites were investigated in a broad range of silica levels from low to high loadings. The mixing method choice had little impact on the properties of rubber composites with low silica loadings. The silica-filled rubber demonstrated in this study, however, shows superior characteristics over the rubber composite prepared with conventional dry mixing, particularly with high silica loadings. When compared to silica-filled natural rubbers prepared by dry mixing (dry silica rubber, DSR), the wet mixing (for WSR) produced smaller silica aggregates with better dispersion. Due to the shorter heat history, the WSR exhibits superior curing characteristics such as a longer scorch time (2.2–3.3 min for WSR and 1.0–2.1 min for DSR) and curing time (4.1–4.5 min for WSR and 2.2–3.1 min for DSR). Additionally, the WSR has superior mechanical properties (hardness, modulus, tensile strength, and especially the elongation at break (420–680% for WSR and 360–620% DSR)) over the DSR. The rolling resistance of WSR is lower than that of DSR. However, the reversed trend on the wet skid resistance is observed.

Combinatorial Approach of Binary Colloidal Crystals and CRISPR Activation to Improve Induced Pluripotent Stem Cell Differentiation into Neurons.

Conventional methods of neuronal differentiation in human induced pluripotent stem cells (iPSCs) are tedious and complicated, involving multistage protocols with complex cocktails of growth factors and small molecules. Artificial extracellular matrices with a defined surface topography and chemistry represent a promising venue to improve neuronal differentiation in vitro. In the present study, we test the impact of a type of colloidal self-assembled patterns (cSAPs) called binary colloidal crystals (BCCs) on neuronal differentiation. We developed a CRISPR activation (CRISPRa) iPSC platform that constitutively expresses the dCas9-VPR system, which allows robust activation of the proneural transcription factor NEUROD1 to rapidly induce neuronal differentiation within 7 days. We show that the combinatorial use of BCCs can further improve this neuronal differentiation system. In particular, our results indicate that fine tuning of silica (Si) and polystyrene (PS) particle size is critical to generate specific topographies to improve neuronal differentiation and branching. BCCs with 5 μm silica and 100 nm carboxylated PS (PSC) have the most prominent effect on increasing neurite outgrowth and more complex ramification, while BCCs with 2 μm Si and 65 nm PSC particles are better at promoting neuronal enrichment. These results indicate that biophysical cues can support rapid differentiation and improve neuronal maturation. In summary, our combinatorial approach of CRISPRa and BCCs provides a robust and rapid pipeline for the in vitro production of human neurons. Specific BCCs can be adapted to the late stages of neuronal differentiation protocols to improve neuronal maturation, which has important implications in tissue engineering, in vitro biological studies, and disease modeling.

Controlling factors of the particle size of spherical silica synthesized by a dry process

AbstractSilica is an important inorganic compound used in many materials, including quartz products and resin fillers. To synthesize silica by a dry process, combustion methods using organosilicon compounds as raw monomers have been extensively studied. However, few studies have considered mass production or compared preparation methods using different types of organosilicon compounds and the same equipment. In this study, we used six starting materials in a dry process and examined the effect of monomer species on particle shape and size. The amount of raw monomer supplied was adjusted so that the calorific value of combustion was the same for all the raw monomers. We focused on the calorific value because it affects the construction cost of industrial‐scale production plants. For example, when the calorific value is high, the manufacturing plant is large and costly because the heat generated after the reaction must be removed. We obtained spherical silica particles by a dry process using six monomers. The particle size depended on both the basic unit of the monomer and the required oxygen (RO) ratio of the primary burner gas. This combination was essential in determining the speed of the initial reaction, number of nuclei, and residence time. Consequently, we established a factor that determines the size of spherical silica particles and successfully adjusted the particle size.

Experimental analyzing the static puncture resistance performance of shear thickening fluid impregnated polypropylene hybrid composite target structures for armour application

The challenges of today’s protective material developers' requirements for body armour target structure design, strength, stiffness, and light weight structures have historically come from composite structures having high cost, complex manufacturing, and time-consuming process. Hence, there is a need to identify suitable alternate materials with reliable composites and essential design requirements for high impact armour structures. At present, hybrid composite structures are increasingly utilized in armour structure developments because they offer quick adoption to produce low cost, high impact strength, and a methodology for easy and quick manufacturing process without compromising the performance of traditional composite structures. This experimental analysis reports that the prepared hybrid composite target structures are composed of woven polypropylene fabric impregnated with single, double, and triple layers with a prepared shear thickening fluid (STF) concentration (50 vol% silica dispersed in polyethylene glycol 600 g/mol) used as a core layer in this structure and a neat/silica gel coated aluminum face sheet is used as the skin material. The prepared STF is characterized through rheological analysis exhibits shear thickening behavior reveals that extensively depends on silica particle morphology, volume fraction, and particle size distribution. The prepared hybrid composite target structure test results demonstrate a significant enhancement in tensile strength, modulus, better peel resistance properties, and puncture resistance evaluated in different geometry of projectiles like flat, hemispherical, elliptical, and conical indentor penetration velocity at 500 mm/min have been performed to demonstrate the improvements in the target structure. It enhances the performance layer thickness increases with increasing puncture resistance for all indentors sequently identified and penetration damage of target structures varied with respect to indentor nose head surface area of contacts.