Nano-sized SiO2 Research Articles

Inhibition of wax crystallization and asphaltene agglomeration by core-shell polymer@SiO2 hybride nano-particles

The gelation of crude oil with high wax and asphaltene content at low temperatures often results in the block of transportation pipeline in Africa. In recent years, it was reported that surface hydrophobic-modified nanoparticles have important applications in crude oil flow modification. In this work, four kinds of core-shell hybride nanoparticles by grafting poly (octadecyl, docosyl acrylate) and poly (acrylate-α-olefin) onto the surface of nano-sized SiO2 were synthesized by grafting polymerization method. The chemical structure of nanoparticles was analyzed by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The rheological behaviors of crude oil and precipitation of asphaltenes in the presence of nanoparticles were studied by measuring the viscose-temperature relationship curve, the cumulative wax precipitation amount, and morphology of waxes and asphaltenes. The results indicate that the docosyl polyacrylate@SiO2 nanoparticle (PDA@SiO2) can reduce the cumulative wax precipitation amount of crude oil by 72.8%, decline the viscosity of crude oil by 85.6% at 20 °C, reduce the average size of wax crystals by 89.7%, and inhibit the agglomeration of asphaltene by 74.8%. Therefore, the nanoparticles not only adjust the crystalline behaviors of waxes, but also inhibit the agglomeration of asphaltenes. Apparently, core-shell hybride nanoparticles provides more heterogeneous nucleation sites for the crystallization of wax molecules, thus inhibiting the formation of three-dimensional network structure. The core-shell polymer@SiO2 hybride nanoparticles are one of promising additives for inhibiting crystallization of waxes and agglomeration of asphaltenes in crude oil.

Anti-corrosive superhydrophobic coatings for reinforcement protection: recycling of concrete garbage

PurposeThe purpose of this paper was to prepare a ternary hierarchical rough particle to accelerate the anti-corrosive design for coastal concrete infrastructures.Design/methodology/approachA kind of micro-nano hydrophobic ternary microparticles was fabricated from SiO2/halloysite nanotubes (HNTs) and recycled concrete powders (RCPs), which was then mixed with sodium silicate and silane to form an inorganic slurry. The slurry was further sprayed on the concrete surface to construct a superhydrophobic coating (SHC). Transmission electron microscopy and energy-dispersive X-ray spectroscopy mappings demonstrate that the nano-sized SiO2 has been grafted on the sub-micron HNTs and then further adhered to the surface of micro-sized RCP, forming a kind of superhydrophobic particles (SiO2/HNTs@RCP) featured of abundant micro-nano hierarchical structures.FindingsThe SHC surface presents excellent superhydrophobicity with the water contact angle >156°. Electrochemical tests indicate that the corrosion rate of mild steel rebar in coated concrete reduces three-order magnitudes relative to the uncoated one in 3.5% NaCl solution. Water uptake and chloride ion (Cl-) diffusion tests show that the SHC exhibits high H2O and Cl- ions barrier properties thanks to the pore-sealing and water-repellence properties of SiO2/HNTs@RCP particles. Furthermore, the SHC possesses considerable mechanical durability and outstanding self-cleaning ability.Originality/valueSHC inhibits water uptake, Cl- diffusion and rebar corrosion of concrete, which will promote the sustainable application of concrete waste in anti-corrosive concrete projects.

Multi-phase shear thickening fluid based on ionic liquid dispersion medium for impact resistance and wear protection

Shear thickening fluids (STFs) have attracted increasing attention as smart materials with unique rheological properties. However, the preparation of STFs usually relies on a composite system of spherical nanoparticles with polyethylene glycol. In this work, novel multi-phase STFs (ILSTFs) were prepared in an ionic liquid by incorporating nanosized SiO2 and rod-shaped calcium metasilicate (CaSiO3) particles as a dispersed phase. Compared to traditional STFs, ILSTFs demonstrate excellent thermal stability. Rheological tests indicate that ILSTFs exhibit continuous shear thickening behavior, resulting in excellent energy absorption and impact wear resistance. In addition, ILSTFs can serve as a new type of lubricant. The tribological properties and impact resistance of ILSTFs were highly correlated with the shear thickening effect, with the multi-phase ILSTF system with CaSiO3 demonstrating superior impact wear resistance compared to the single-phase system. In this study, finite element analysis (FEA) is further utilized to investigate the local damage evolution and energy absorption rate of STF under impact loading, providing insights into the underlying mechanism. This ionic liquid-based STF holds promise for applications as a flexible filling component in the fields of lubrication technology and impact protection structures.

Controllable preparation of wollastonite-based composite coating for highly-efficient passive daytime radiative cooling in building

The building cooling has aroused widespread attention due to its significant contribution to both global warming and energy usage. To combat global warming and reduce energy consumption, an environmentally friendly beneficial alternative to electric cooling for buildings is passive daytime radiative cooling (PDRC). However, many of the reported radiative coolers still suffer from the challenge of complex preparation processes and high costs, making it difficult to scale up for building applications. Herein, the utilization of abundant and low-cost natural resources (i.e., cellulosic biomass and minerals) is strategized to produce radiative cooling material and incorporate this material into building cooling systems to boost global carbon neutrality. Guided by this concept, a hydrophobic SiO2/EC composite (HSEC) coating is designed by embedding nano-sized wollastonite-based SiO2 particles into porous ethyl cellulose (EC) polymer, and subsequently through polydimethylsiloxane (PDMS) dispersion spray treatment. Benefiting from the sufficient scattering by the nano-SiO2 particles and randomly dispersed light-scattering air voids, the resulting cooling coating shows a high solar reflectivity of 95.1 %. More importantly, the molecular vibration of the chemical in HSEC coating results in a high atmospheric window emissivity of 92.5 %. In the field test, the HSEC coating remained approximately 4.2 °C below the ambient temperature under intense solar irradiation of 412.5 W⋅m−2. This work not only offers a promising strategy for realizing the high-value utilization of wollastonite resources in building materials, but also provides a controllable approach for large-scale preparation of highly efficient radiative cooling materials to alleviate building cooling demands.

Effect of Silicon Dioxide Nanoparticles on the Sintering Properties of Beta-Tricalcium Phosphate Composites.

Composite sintered bodies comprising silicon dioxide (SiO2) nanoparticles dispersed in β-tricalcium phosphate (β-TCP) were prepared. The addition of nano-sized colloidal SiO2 to the β-TCP produced well-dispersed secondary phase nanoparticles that promoted densification by suppressing grain growth and increasing linear shrinkage of the sintered bodies. The SiO2 was found not to react with the β-TCP at 1120 °C and the substitution of silicon for phosphorous to produce a solid solution did not occur. This lack of a reaction is ascribed to the absence of available calcium ions to compensate for the increase in charge associated with this substitution. The SiO2 nanoparticles were found to be present near the intersections of grain boundaries in the β-TCP. β-TCP composite sintered body containing 2.0 and 4.0 wt% SiO2 exhibited a bending strength comparable to that of cortical bone and hence could potentially be used as a bone filling material.

Fe/amorphous-Al2SiO5 composites fabricated by low-temperature solid-phase reaction densification achieve synergistically enhanced structural and soft magnetic properties

To date, an urgent problem for various metal-based soft magnetic composites (SMCs) is that it is difficult to simultaneously achieve high strength and optimum magnetic performance, which actually restricts their large-scale applications in many electromagnetic fields. In this work, we have tried to resolve this basic problem by proposing a new concept of low-temperature solid-phase reaction densification instead of conventional particle-deformation densification to fabricate high-performance metal-based SMCs. Specifically, fully-densified nanoscale amorphous Al2SiO5 coating layers are formed through a solid phase reaction at 500 °C between initially-prepared nano-sized amorphous SiO2 and amorphous Al2O3, and meanwhile coated in situ on the surface of deformed Fe to fabricate novelly-structured Fe/amorphous-Al2SiO5 SMCs. The low-temperature solid-phase reaction for fabrication of Fe/amorphous-Al2SiO5 SMCs can avoid negative effects of high processing temperature for conventional metal-based SMCs on their structure and magnetism resulting in their high strength, increased resistivity, low core loss and high saturation magnetic inductions. Thus, Fe/amorphous-Al2SiO5 SMCs show synergistically enhanced structural and soft magnetic properties, which exceed those of most conventional metal-based SMCs. This work also provides a special and useful insight into the design and applications of metal-based composites needing both functional and structural properties.

Efficient photo-assisted degradation of wastewater dyes using CdS nanoparticles confined in porous G-C3N4/SiO2 composites

Porous g-C3N4/SiO2 (CNS) nanocomposite was prepared using nanosized colloidal SiO2 by a sol/gel/condensation technique from thiourea and tetraethyl-orthosilicate (TEOS). The fabricated sample was confined with different amounts of CdS nanoparticles (NPs) through precipitation route. various characterization techniques were used to determine the structural, morphological, optical, and textural properties of the investigated photocatalysts. The band gap energies and the potential positions of the valence band (VB) and conduction band (CB) levels in the nanocomposite were determined. We have also explored the different degradation behaviors of the studied photocatalysts toward Rhodamine B (Rh.B) and Remazol Brilliant blue R (Re.B) under solar light irradiation. Amongst all the utilized photocatalysts, 8CNS demonstrated the best photocatalytic performance with degradation rate constants of 0.069 min−1 and 0.022 min−1 for Rh.B and Re.B, respectively. These values are found to be higher than the corresponding rates obtained at g-C3N4 and CdS. The higher degradation efficiency and photostability of CdS/CNS nanocomposites can be attributed to the presence of SiO2 and the synergetic effect of CdS which led to improving both their surface area and charge separation efficiency. Our investigated photocatalyst were found to retain their degradation efficiency after multiple usages demonstrating their sustainability. Based on the potential positions of the reactive species and trapping studies, the photocatalytic degradation mechanism has thus been proposed using superoxide radicals (.O2–) and photoinduced holes (h+) as the main reactive species participate in the degradation process. Our findings should pave novel routes for the elimination of the environmentally toxic dyes using affordable photocatalysts.

Engineering biomimetic cellulose fabric for sustainably and durably cooling human body

It is essential and challenging to develop sustainable and durable passive radiative cooling materials for long-term effectively maintaining human thermal comfort when undergoing intensified global warming in our low-carbon society. Herein, inspired by the distinct structure-property relationship of fruits-branches in fruiter, this work designs an approach of fibrillation of cellulosic fibers (branches of fruiter) followed by in-situ synthesis of SiO2 nanoparticles (fruits of fruiter) easily to prepare sustainable, robust, customizable, and scalable cooling cellulose fabric. Such coupling strategy of cellulosic-fiber fibrillation and SiO2 in-situ growth strongly roughens cellulose fabric, more specifically, sufficient micro- and nano-sized cellulose fibrils and SiO2 particles, which enables our cooling cellulose fabric to effectively reflect solar light with 97% reflectance (0.4–1.0 µm) and emit mid-infrared light with 0.97 emissivity (8–13 µm). As a result, the developed cooing cellulose fabric spontaneously cools the human body with a temperature drop of 7.4 °C in high-temperature summer. It should be noted that the developed strategy realizes extraordinary adhesion performance between nanosized SiO2 and fibrillated cellulosic fibers, endowing cooling cellulose fabric with durable yet effective cooling distinction despite enduring 100-time mechanical washing and 100-day exposure to air, as well as high strength (∼48 MPa), desirable moisture evaporation rate and breathability. The present work demonstrates a promising strategy how durability, functionality, and customizability can be integrated in future material design.

Effect of Adding Nanosize SiO2 on Physicomechanical Properties and Durability of a Refractory Component Industrial Batch

Effect of Adding Nanosize SiO2 on Physicomechanical Properties and Durability of a Refractory Component Industrial Batch

Effect of Nano-Sized SiO2 Particles Addition on Microstructure and Mechanical Properties of As-Cast Ductile Iron

Effect of Nano-Sized SiO2 Particles Addition on Microstructure and Mechanical Properties of As-Cast Ductile Iron

Preparation of Sulfonated Poly(arylene ether)/SiO2 Composite Membranes with Enhanced Proton Selectivity for Vanadium Redox Flow Batteries

Proton exchange membranes (PEMs) are an important type of vanadium redox flow battery (VRFB) separator that play the key role of separating positive and negative electrolytes while transporting protons. In order to lower the vanadium ion permeability and improve the proton selectivity of PEMs for enhancing the Coulombic efficiency of VRFBs, herein, various amounts of nano-sized SiO2 particles were introduced into a previously optimized sulfonated poly(arylene ether) (SPAE) PEMs through the acid-catalyzed sol-gel reaction of tetraethyl orthosilicate (TEOS). The successful incorporation of SiO2 was confirmed by FT-IR spectra. The scanning electron microscopy (SEM) images revealed that the SiO2 particles were well distributed in the SPAE membrane. The ion exchange capacity, water uptake, and swelling ratio of the PEMs were decreased with the increasing amount of SiO2, while the mechanical properties and thermal stability were improved significantly. The proton conductivity was reduced gradually from 93.4 to 76.9 mS cm-1 at room temperature as the loading amount of SiO2 was increased from 0 to 16 wt.%; however, the VO2+ permeability was decreased dramatically after the incorporation of SiO2 and reached a minimum value of 2.57 × 10-12 m2 s-1 at 12 wt.% of SiO2. As a result, the H+/VO2+ selectivity achieved a maximum value of 51.82 S min cm-3 for the composite PEM containing 12 wt.% of SiO2. This study demonstrates that the properties of PEMs can be largely tuned by the introduction of SiO2 with low cost for VRFB applications.

Probing oxygen activation on plasmonic photocatalysts.

In this work we present an assay to probe the oxygen activation rate on plasmonic nanoparticles under visible light. Using a superoxide-specific XTT molecular probe, the oxygen activation rate on bimetallic gold-silver “rainbow” nanoparticles with a broadband visible light (> 420 nm) response, is determined at different light intensities by measuring its conversion into the colored XTT-formazan derivate. A kinetic model is applied to enable a quantitative estimation of the rate constant, and is shown to match almost perfectly with the experimental data. Next, the broadband visible light driven oxygen activation capacity of this plasmonic rainbow system, supported on nano-sized SiO2, is demonstrated towards the oxidation of aniline to azobenzene in DMSO. To conclude, a brief theoretical discussion is devoted to the possible mechanisms behind such plasmon-driven reactions.

Structure and Evolution of Quasi-Solid-State Hybrid Electrolytes Formed Inside Electrochemical Cells.

Solid-state electrolytes (SSEs) formed inside an electrochemical cell by polymerization of a liquid precursor provide a promising strategy for overcoming problems with electrolyte wetting in solid-state batteries. Hybrid solid-state polymer electrolytes (HSPEs) created by in situ polymerization of a conventional liquid precursor containing electrochemically inert nanostructures are of particular interest because they offer a mechanism for selectively reinforcing or addingnewfunctionalitiesto the electrolyte-removing the need for high degrees of polymerization. The synthesis, structure, chemical kinetics,ion-transportpropertiesand electrochemical characteristics of HSPEs created by Al(OTf)3 -initiated polymerization of 1,3-dioxolane (DOL) containing hairy, nano-sized SiO2 particles are reported. Small-angle X-ray scattering reveals the particles are well-dispersed inliquidDOL. Strong interaction between poly(ethylene glycol) molecules tethered to the SiO2 particles and poly(DOL) lead to co-crystallization-anchoring the nanoparticles in their host It also enables polymerization-depolymerization processes in DOL to be studied and controlled. The utility of the in-situ-formed HSPE, is demonstrated first in Li|HSPE|Cu half cells, which manifest Coulombic efficiencies (CE) values approaching 99%. HSPEs are also demonstrated in solid-state lithium-sulfur-polyacrylonitrile (SPAN) composite full-cell batteries. The in-situ-formed Li|HSPE|SPAN cells show good cycling stability and thus provide a promising path toward all-solid-state batteries.

Regulations on the hydration, morphology, and sulfate-attack resistivity of C3A with micro/nano-silica particles

Micro- and nano-sized SiO2 particles, i.e., silica fume (SF) and nanosilica (NS) have been extensively documented of improving the durability of concrete, but rare investigation on their specific effects on tri-calcium aluminate (3CaO·Al2O3, C3A) reactions/performances in harsh environment has been reported. This work determined the effects of SF and NS on the hydration and hardening properties of C3A-gypsum systems, and their performances under sulfate attack. Results showed that NS and SF can effectively improve the sulfate attack resistivity of the C3A-gypsum systems due to the filling effect and the reduction of crystal size/morphology-induced expansion: a significant reduction of the aspect ratio (length/diameter) can be observed in the NS-added sample comparing the pure C3A-gypsum system. Comparatively, SF can hardly change the morphology of ettringite (AFt), which could be due to that its bigger particle size cannot effectively block the ion migration. It is expected that these findings could contribute to the utilization of fine/ultra-fine SCMs in cementitious materials systems, especially those with high amount of aluminate phases.

Facile Fabrication of Nano-sized SiO2 by an Improved Sol–Gel Route: As an Adsorbent for Enhanced Removal of Cd(II) and Pb(II) Ions

Facile Fabrication of Nano-sized SiO2 by an Improved Sol–Gel Route: As an Adsorbent for Enhanced Removal of Cd(II) and Pb(II) Ions

Preparation of polymer-based foam for efficient oil-water separation based on surface engineering.

The leakages of a large number of organic solvents and oil spills not only cause extensive economic losses, but also destroy the ecological environment. However, there were few studies on the surface engineering of adsorption materials for efficient oil-water separation in complex environments. In this research, through surface engineering, the polymer-based foam exhibited high efficiency oil-water separation performance in different pH environments. Hydrophobic groups were introduced onto the surface of nano-sized SiO2 particles via hydrolysis and polycondensation reactions, and then the modified SiO2 was loaded on the foam. After modification, the water contact angle of the modified foam increased from 116.4° to 152.5°, and the oil-water separation performance was obviously enhanced. The oil removal rate of the modified foam remained above 96%. The highest capacity of petroleum diesel was 33.4 g-1, which was much higher than other similar adsorption materials. In addition, the modified foam maintained good hydrophobicity and oil removal rate in a wide pH range. The efficient oleophilic and hydrophobic foam prepared by combining green physical foaming with surface engineering was expected to be widely used in large-scale organic solvent recovery and oil leakage emergency treatment.

Enhancing CO2 storage capacity and containment security of basaltic formation using silica nanofluids

The affinity of the basalt surfaces towards CO2, quantified as wettability functions, is one of the most important driving factors for CO2 trapping capacity and containment security. SiO2 is a minor constituent, often found in traces in the seawater and formation brine injected or reinjected into the sub-surface formations. This work, thus, evaluates the effect of nano-sized SiO2 (100, 1000, and 2000 mg. L−1) on the wettability of the basalt rock surface in the pressure range of 5-20 MPa. The results from brine/CO2/rock wettability measurements show that SiO2 nanoparticles turn the CO2-wet basalt surface to weakly water-wet upon aging with nanofluids. About 40% reduction in the measured brine contact angle takes place upon treatment of the rock sample with 1000 mg. L−1 nanoparticles. We hypothesize that this change in wettability may facilitate enhanced capillary or residual trapping of CO2 in the basalt formation having adequate porosity and permeability to enhance the basalt CO2 trapping capacity.

A comprehensive green utilization strategy of lignocellulose from rice husk for the fabrication of high-rate electrochemical zinc ion capacitors

Rice husk is an important biomass residue derived from the production of rice. Rice husk contains silica (10–20 wt%) and lignocellulose (cellulose, 15–25 wt%; lignin, 10–20 wt%). The lignocellulose components in rice husk are potential carbon sources for functional carbon materials. In this work, we propose a general comprehensive green utilization strategy for the preparation of lignin-derived hierarchical porous carbon (LHPC) and cellulose-paper-based separator using the lignin and cellulose components inside rice husk, respectively. The obtained LHPC and cellulose paper separators were used as pivotal components for the fabrication of high-rate electrochemical zinc ion capacitors. Meanwhile, the silica and potassium sources in this comprehensive route were recycled as nano-sized SiO2 particles and pure KCl powders. This work constitutes a general route for the green utilization of rice husk biomass. This work opens a green avenue for the effective utilization of renewable biomasses to develop functional carbon materials and pivotal components of electrochemical energy storage devices.

Effect of water atomization on properties of type 4130 steel processed by L-PBF

In the current investigation, a comparison between two type 4130 low-alloy steel powders produced by both gas and water atomization, and later processed by Laser-powder bed fusion was carried out. Samples fabricated from the water atomized powder showed relative density levels exceeding 99%, slightly lower than those achieved with the gas atomized powder. Both steels exhibited similar metallurgical features after solidification, showing a microstructure that is mainly composed of partially tempered martensite, bainite, and retained austenite. Additionally, micro-segregation of alloying elements was detected in the as-built microstructure, which contribute to a local increase in microhardness. The excess of oxygen found in the water atomized powder tended to combine with silicon and form nano-sized SiO2 inclusions. During the laser processing, the complex heating and cooling effects generated by adjacent laser tracks and by overlapping layers led to an in-situ tempering of the fresh martensite. Accordingly, the hardness values of steels in as-built condition were equivalent to those of conventionally quenched samples tempered at 350 °C and 450 °C, for gas atomized and water atomized steels, respectively. Finally, a comparison in terms of mechanical properties of the investigated steels showed that the powder atomization process resulted in limited changes in steel performance.

Improved photocatalytic activities of recyclable porous Fe2O3 nanotubes by modifying with nano-sized SiO2 and g-C3N4 for degrading 2-chlorophenol

It is highly desired to fabricate efficient α-Fe2O3-based photocatalysts with recyclable feature for pollutants degradation. Herein, porous α-Fe2O3 nanotubes with high photocatalytic activity for degrading 2-chlorophenol (2-CP) have been successfully synthesized by a phase separation electrospinning process, with a pipe diameter of about 200 nm . The photoactivity is greatly improved by in-situ introducing SiO2, attributed to the increased surface area by decreasing the size of nanoparticles shell from ~ 30 to 15 nm. Furthermore, the photoactivity of SiO2 modified α-Fe2O3 is further improved by coupling with porous g-C3N4 nanosheets, ascribed to the promoted charge separation by the newly accepted S-scheme charge transfer mainly based on the EPR tests and photocurrent action spectra. Interestingly, the optimized α-Fe2O3-based nanotubes exhibit ~ 4-time improvement of the kinetic rate constant in 2-CP degradation compared with the reported α-Fe2O3 nanoparticles, with good recyclability by self-sediment.