Silica Component Research Articles

Controlled fabrication of functionalized nanoscale zero-valent iron/celluloses composite with silicon as protective layer for arsenic removal

From the perspective of basic human health, arsenic is extremely toxic and highly lethal, which will enter surface water and groundwater through industrial production and eventually enter human beings through the food chain, causing immeasurable harm. Herein, a new composite material, namely NZVI@SiO2@ celluloses (FSC), was successfully synthesized by hydrothermal and reduction methods based on cotton fiber as the carrier, nanoscale zero-valent iron (NZVI) as the active component of arsenic removal and silica as the protective layer. The crystal structure, morphology and chemical elements of the composite were characterized and determined by SEM, XPS, TEM, and XRD techniques. The results demonstrated that rod-like NZVI with the diameter of 50–80nm was distributed evenly on the surface of cotton fiber, and the coating of silica forming a 10–20nm transparent shell can effectively prevent the oxidation of NZVI from losing its effectiveness on the surface. In addition, the optimal adsorption conditions by FSC were investigated by concentration, controlling pH value, interfering ions and temperature. The obtained results show that the prepared materials have better adsorption capacity for sodium arsenite under acidic conditions of pH at 2.8–4; and the maximum adsorption capacity could reach about 70mg/g when the concentration was 300mg/L at 30°C. The pseudo-first-order and pseudo-second-order kinetic models were all in good agreement with the experimental data, further identifying the adsorption kinetics mechanism of FSC on arsenic. Because NZVI alone is easily oxidized in the air, and agglomeration is also likely to occur, the combination of NZVI, silica and cotton fiber perfectly solved these defects and further improved the adsorption performance in this work. Moreover, the comparison on removal effects of various adsorbents simultaneously indicates that FSC will have a great application prospect in the future water pollution treatment.

Preparation of magnetically retrievable CoFe2O4@SiO2@Dy2Ce2O7 nanocomposites as novel photocatalyst for highly efficient degradation of organic contaminants

CoFe2O4@SiO2@Dy2Ce2O7 magnetic nanocomposite as recyclable photocatalyst has been prepared for the first time. The cobalt ferrite component was produced through combustion route with the aid of grape juice as novel and green fuel, and the silica component was prepared through sol-gel route with the aid of 2,2-dimethyl-1,3-propanediamine as new basic agent as well as Dy2Ce2O7 component has been synthesized through a modified Pechini route with the aid of 2,2-dimethyl-1,3-propanediamine as novel pH regulator. The as-fabricated CoFe2O4@SiO2@Dy2Ce2O7 nanostructures were characterized by FESEM, DRS, TEM, EDX, XRD, VSM and BET. This is the first try on the survey of photocatalytic efficiency of CoFe2O4@SiO2@Dy2Ce2O7 nanostructures. Role of kind of irradiation source, catalyst loading and kind of contaminant has been described upon improving performance of CoFe2O4@SiO2@Dy2Ce2O7 nanostructures. The results indicated that the fabricated CoFe2O4@SiO2@Dy2Ce2O7 could be potentially utilized as efficient and favorable kind of recyclable photocatalyst for removal of water contaminants.

Dissolution of silica component of glass network at early stage of corrosion in initially silica‐saturated solution

AbstractCorrosion of glass in silica‐saturated solution has been performed with the assumption that dissolution of silicate species from the glass network would not occur. Using surface‐sensitive analytical techniques, we report experimental evidence suggesting the dissolution of silicate network species from a model nuclear waste glass, called international simple glass (ISG), in an aqueous solution initially saturated with soluble silica species. Results from low energy ion scattering and X‐ray photoelectron spectroscopy reveal a complete depletion of mobile element species (B, Na) from the ISG surface and an enrichment of Zr on the outmost surface. In support of spectroscopic analyses, results from topographic imaging with atomic force microscopy show a stochastic dissolution of glass surface resulting in a higher surface roughness with increasing corrosion time in aqueous solution. This study shows that a true equilibrium between soluble silica species in the solution phase and silicate species in the glass network could not be warranted by performing corrosion experiments in the solution where dissolved silica species are initially equilibrated with amorphous silica in the presence of KOH. The leaching of mobile species (B, Na) could affect the saturation level of aqueous solution and induce further dissolution of the glass surface.

Skeletons of Glass Sponges as a Substrate for Creating Functional Composite Organosilicon Materials

The article describes a method of creating a three-dimensional organosilicon composite material based on the glass sponge spicules through a combination of soft etching and controlled mechanical action, non-destroying spicules. When in an alkaline medium, the material of the spicules’ outer concentric layers is dissolved and silica passes into solution. After 20 to 30 days in alkaline medium, the silica is in excess and precipitates on organic components, forming a network of 300–500-nm thick organosilicon trabeculae, by which the spicules are fused into a single structure. The resulting composite material contains a mineral component of silica and an organic component. The results indicate that the natural organosilicon material can be reformed as a result of self-assembly into three-dimensional or flat structures.

On-Demand Detaching Nanosystem for the Spatiotemporal Control of Cancer Theranostics.

Engineering multiple theranostic modalities into a single nanoscale entity holds great potential to rejuvenate cancer treatments; however, enabling the sophisticated spatiotemporal control of each component for maximizing theranostic improvement and minimizing side effects concurrently remains a challenge. Herein, an intelligent detachable "nanorocket" is developed to sequentially manipulate and optimize multitheranostic processes for magnetic resonance-assisted ultrasound-drug combined therapy (MR-HIFU-Drug). The "nanorocket" is constructed by integrating multicomponent (MnCO3, doxorubicin, silica) on the pH-sensitive CaCO3 nanoparticles step by step via cation exchange and controlled heterogeneous nucleation, in which doxorubicin is encapsulated in both carbonates and silica component. The "nanorocket" can initiate sequential detachment in the acidic tumor microenvironment. Specifically, carbonates decompose instantly, releasing Mn2+ as the MR contrast agent and leaving hollow silica nanostructure behind as the HIFU synergistic agent. Consequently, burst release of drug is also triggered, further triggering the degradation of silica, which in turn regulates the slow release of drug from the silica matrix. Thus, efficient tumor inhibition is achieved by enhanced HIFU ablation and biphase release of doxorubicin with a stepwise clearance of Mn and Si. This work establishes a system for the systematic spatiotemporal dispatch of diverse theranostic components for the balance of efficacy and safety in cancer theranostics.

Olivine melting at high pressure condition in the chassignite Northwest Africa 2737

Shock-induced melting textures and assemblages in the chassignite Northwest Africa (NWA) 2737 were investigated. NWA 2737 consists mainly of coarse-grained olivine (Fa19.6–20.5) and minor amounts of low-Ca pyroxene, plagioclase (now maskelynite), and chromite. Several melt inclusions formed through pre-igneous activity are enclosed in the olivine grains, and some melt inclusions were melted again by the impact event. Several olivine fragments are entrained in the melt inclusion and dissociated into spherulitic ferroan–periclase and interstitial fine-grained clinopyroxene assemblages. The olivine fragments were melted once by the shock metamorphism, and ferroan–periclase crystallized from the olivine melt. We expect that bridgmanite crystallized from the residual melt and inverted to clinopyroxene through the subsequent high-temperature event, although we cannot rule out the possibility that the ferroan–periclase and clinopyroxene assemblage is the partial melting product of olivine. Parts of the melted olivine in the melt inclusion are mixed with the glass (having low-Ca pyroxene + a small amount of silica components) filling the matrix portion of the melt inclusion. Then, olivine, clinopyroxene, and tridymite crystallized from the mixed melts. We infer that the olivine–clinopyroxene–tridymite assemblage is the crystallization product from the mixed melts during rapid cooling at low- or ambient-pressure conditions. Olivine grains adjacent to the melt inclusion dissociated to clinopyroxene + ferroan–periclase assemblage. As the distance from the melt inclusion increased, polycrystalline olivine crystal assemblage formed. We expect that the polycrystalline olivine assemblage is the remnant of ringwoodite: metastable ringwoodite formed in the olivine grain by the shock metamorphism, and back transformed into olivine again through high temperature and low pressure conditions. Mineral assemblages in and adjacent to the melt inclusion show evidence for high pressure and high temperature conditions and for low pressure and high temperature conditions. The pressure–temperature–time path recorded in NWA 2737 is not simple, i.e., the ejection path from the impact site is complex.

Water-soluble organic polymer/silica composite nanofilms with improved fluorescence quantum yield

Two-dimensional photoluminescent materials have promising applications in optoelectronics, biosensors, and functional inks. However, it remains a big challenge for fabrication of water-soluble photoluminescent nanofilms with relative quantum yield higher than 50%. In this contribution, we report on facile fabrication of water-soluble organic polymer/silica composite nanofilms with relative quantum yield higher than 70%, through surface modification of organic polymer nanofilms with only a trace amount of organosilanes. The photoluminescence intensity, photostability, and quantum yield of the composite nanofilms are improved compared with individual organic polymer nanofilms. The type of organosilanes has minor effect on the enhanced optical properties of organic polymer nanofilms. The enhanced optical properties of the composite nanofilms are attributed to the strong interactions between silica and organic polymer components, based on theoretical calculations and instrumental analysis. The aqueous solution of composite nanofilms can be applied as cultivation medium for the growth of mung bean sprouts and as a fluorescent indicator for imaging the sprout tissue in vivo.

FEATURES OF MELTING IN THE THERMOCHEMICAL PLUME CONDUIT AND HEAT AND MASS TRANSFER DURING CRYSTALLIZATION DIFFERENTIATION OF BASALTIC MELT IN A MUSHROOM-SHAPED PLUME HEAD

The number Ka=N/N1is used to evaluate the thermal power of a plume;Nis the thermal power transferred from the plume base to its conduit, andN1is the thermal power transferred from the plume conduit into the surrounding mantle. At the relative thermal power 1.9<Ka<10, after eruption of the melt from the plume conduit to the surface, melting occurs in the crustal block above the plume roof, resulting in the formation of a mushroom-shaped head of the plume. A thermochemical plume originates at the core-mantle boundary and ascends (melts up) to the surface. Based on laboratory and theoretical modeling data, we present the flow structure of melt in the conduit and the head of the thermochemical plume. The features of melting in the plume conduit are elucidated on the basis of the phase diagram of the CaO-MgO-Al2O3-SiO2model system. The two upper convection cells of the plume conduit relate to the region of basic and ultrabasic compositions. Our study shows that melting in these cells proceeds according to monovariant equilibria of eutectic type L=Cpx+Opx+An+Sp and L=Fo+An+Cpx+Opx. In case of the CaO–MgO–Al2O3–SiO2–Na2O system, crystallization differentiation proceeds as separation of plagioclase crystals. Separation of plagioclase crystals enriched in anorthite component leads to enrichment of the residual melt in silica and alkaline components. Assuming the initial basaltic melt, we calculated the compositional changes in the melt, which are powered by the heat and mass transfer processes in the mushroom-shaped plume head. The calculations were performed in two stages: (1) after settling of refractory minerals; (2) after settling of plagioclase in the melt resulting from the first stage. In the second stage, the melt contains 88.5 % of plagioclase component. The calculations were performed for melt temperatureTmelt=1410 °C and pressureP=2.6 kbar and 6.3 kbar. The calculated weight contents of oxides, the normative compositions for solid phase, and the oxide content and normative composition for the residual melt were tabulated. The SiO2content in the residual melt amounts to 59.6–62.3 % and corresponds to the crustal SiO2content.

Distributions of Silica and Biopolymer Structural Components in the Spore Elater of Equisetum arvense, an Ancient Silicifying Plant.

Equisetum species are primitive vascular plants that benefit from the biogenesis of silica bio-organic inclusions in their tissues and participate in the annual biosilica turnover in local eco-systems. As means of Equisetum reproduction and propagation, spores are expected to reflect the evolutionary adaptation of the plants to the climatic conditions at different times of the year. Combining methods of Raman and scanning electron microscopy and assisted with density functional theory, we conducted material spatial-spectral correlations to characterize the distribution of biopolymers and silica based structural elements that contribute to the bio-mineral content of the elater. The elater tip has underlying skeletal-like structural elements where cellulose fibers provide strength and flexibility, both of which are necessary for locomotion. The surface of the elater tips is rich with less ordered pectin like polysaccharide and shows a ridged, folded character. At the surface we observe silica of amorphous, colloidal form in nearly spherical structures where the silica is only a few layers thick. We propose the observed expansion of elater tips upon germination and the form of silica including encapsulated biopolymers are designed for ready dispersion, release of the polysaccharide-arginine rich content and to facilitate silica uptake to the developing plant. This behavior would help to condition local soil chemistry to facilitate competitive rooting potential and stem propagation.

Influence of Glassy Carbon Surface Finishing on Its Wear Behavior during Precision Glass Moulding of Fused Silica

Laser technology has a rising demand for high precision Fused Silica components. Precision Glass Moulding (PGM) is a technology that can fulfil the given demands in efficiency and scalability. Due to the elevated process temperatures of almost 1400 °C and the high mechanical load, Glassy Carbon was qualified as an appropriate forming tool material for the moulding of Fused Silica. Former studies revealed that the tools’ surface finishing has an important influence on wear behaviour. This paper deals with investigation and analysis of surface preparation processes of Glassy Carbon moulds. In order to fulfil standards for high precision optics, the finishing results will be characterised by sophisticated surface description parameters used in the optics industry. Later on, the mould performance, in terms of wear resistance, is tested in extended moulding experiments. Correlations between the surface finish of the Glassy Carbon tools and their service lifetime are traced back to fundamental physical circumstances and conclusions for an optimal surface treatment are drawn.

Thermodynamics, structure, and transport properties of the MgO–Al2O3 liquid system

Seven liquids along the MgO–Al2O3 join were simulated at zero pressure in temperature (T) range 2000–6000 K using the first-principles molecular dynamics method. The simulation results show continuous changes in various physical properties with composition (molar fraction of alumina, X). They suggest that the binary mixing tends to be nearly ideal with no immiscibility along the entire join. The calculated mean coordination numbers of MgO and AlO polyhedra gradually increase with increasing X, for example, their respective values are 4.6 and 4.3 at/near the MgO end, 5.2 and 4.6 for MgAl2O4 spinel composition, and 5.5 and 4.8 at/near the alumina end. The mean O–O coordination number remains almost unchanged along the join at ≥ 12 implying a closely packed arrangement. In contrast, all other coordination types including O–Mg and O–Al change dramatically along the join. The calculated self-diffusion and viscosity coefficients vary much less with composition (by a factor of 4 or less along the entire join) than with temperature (by two orders of magnitudes over the T range considered). Their T–X variations can be well described by the respective Arrhenius equations with composition-dependent activation energies and pre-exponential parameters. While the alumina and silica components are considered to play a similar role with regard to the structural polymerization of amorphous aluminosilicates, our results show that they influence the melt transport properties very differently. Therefore, the general notion that these two oxide components play an equivalent role in multicomponent magmatic melts is not unambiguous.

Soy protein acid hydrolysate/silica hybrid material as novel adsorbent for methylene blue

Abstract The current study purposes to use a sustainable, low cost and abundant plant protein, soy protein hydrolysate (SPH), as a functional polymer to support silica gel matrix. Tetraethoxysilane (TEOS) was used as silica precursor and 3-glycidoxypropyltrimethoxysilane (GPTMS) was used as crosslinking agent between SPH and silica gel. SPH/silica hybrid was prepared through facile chemical crosslinking method. FTIR showed that GPTMS act as covalent crosslinking agent between SPH and silica network in the crosslinked hybrid. SEM analysis exhibited a homogenous morphology for the prepared SPH/silica hybrid, suggesting a well integrity between SPH and silica components. The novel hybrid was also characterized through XRD and TEM. The crosslinked SPH/silica hybrid exhibited high absorption capacity for methylene blue (MB) removal from aqueous solutions. The adsorption results fitted well with pseudo second order and Langmuir isotherm model and the maximum removal efficiency was 357 mg/g. These results demonstrated that SPH/silica hybrid is effective adsorbent for removal of MB, which would provide a new sustainable adsorbent for water purification.

Natural factors forming the quality of carbonate raw materials

The article is devoted to the study of natural factors that influence the regularities in the distribution of the quality of carbonate raw materials in the deposits of the Articulation Zone of the Donbass Basin with the Priazovskiy block of the Ukrainian Shield. Paleogeographic conditions of sedimentation and the processes of secondary quality change were established by comparing the lithologic-stratigraphic sections of deposits in different parts of the Articulation Zone: from the west (Novotroitskoe deposit) through the center (Elenovskoe deposit) and to the east (Karakubskoe deposit). The variability in the quality of carbonate raw materials was estimated from the results of statistical processing of the chemical analysis of exploratory samples. Geochemical associations were established for carbonate rocks within the stratigraphic horizons of each deposit. The best in quality of all deposits of the Donbass Articulation Zone are the carbonate rocks of the Cl t c horizon. The conditions for their formation were the most stable. They are characterized by a negative connection of the main quality component (CaO) with all other quality indicators. At the same time, the association of indicators associated with a significant positive connection is retained: SiO2, R2O3, S.The process of forming carbonate strata are accompanied by intense silicification processes that relate to climatic changes in temperature, salinity and depth of the sea basin. This is confirmed statistically, because the significant negative correlation between the main component of quality and silica is established on the horizons of carbonate rocks with an increased silica content. The process of dolomitization of the carbonate stratum took place in two stages. At the beginning of the accumulation of the carbonate layer, the sea basin was characterized by lower temperatures and higher magnesium contents than in the subsequent period. Therefore, the lower stratum of the Novotroitskoe and Elenovskoe deposits include sedimentary dolomites. Later, the conditions changed, so there are no dolomites in the Karakubskoe deposit. The second stage of dolomitization is associated with the post-carbon andesite-trachyandesite magmatic complex. The rocks of this complex are found in the carbonate stratum in the form of interplastic intrusions, dikes and stock-like bodies. This contributed to the appearance of sulphide mineralization, zones of silicification and recrystallization of carbonate minerals in spot-dolomitized limestones. The structural-tectonic factor, which is manifested by intensive leaching processes, exerts the greatest influence on the degradation of the quality of carbonate raw materials. In zones of tectonic disturbances, they have maximum extension areas. The structural transformationsthat began in the Donbas after the early Carboniferous disrupted the primary stratified occurrence and quality of the carbonate thickness. The upper Visean horizons are subject to intensively leached, similar to tectonic,melange.The contribution made by these studies to scientific knowledge lies in the identification of the natural factors that determined not only the quality of carbonate rocks, but also indicators of the development stages of the Donbass Articulation Zone of two major tectonic structures - Donbass and the Ukrainian Shield. The practical significance of the results of the work is connected with the fixed possibility of conducting geological and technological mapping and further construction of varietal maps of the deposits of carbonate raw materials.

Primary data on the impact from trap magmatism on the hydrogeochemistry of brines in the southwestern part of the Kureyka syncline (Siberian Platform)

The new data on the trap magmatism affecting the hydrogeochemistry of brines in southwestern Kureyka syncline in the west of the ancient Siberian platform are presented. The brines occurring in Paleozoic and Proterozoic deposits have salinity (total dissolved solids) varying broadly: from 30.2 to 469.6 g/dm3 for Na Cl, Na-Ca Cl, Ca-Na Cl, Ca-Mg Cl and Ca Cl types, among which the mixed types (Ca-Na Cl and Na-Ca Cl) are found prevailing. The activity of intrusive trap magmatism in the contact zone (with a strike length of up to 400 m) facilitated the disintegration of organic compounds in the free and water-dissolved form (CH4, C2H6, C3H8, iC4H10, nC4H10, iC5H12, nC5H12, C6H14, I, B, NH4). The reaction of the intruding traps brines interaction significantly affected the initial composition of brines, showing a shift towards their saturation with iron, aluminum, silica and other components and thus bearing the evidence of possible salt-induced metal extraction from magmatic melts into an ore-bearing fluid.

Aerated concrete, obtained by joint grinding of components

The effect of joint grinding Portland cement clinker, silica component and mineral additives (diopside, wollastonite) to a specific surface of 280-300 m2 / kg on non-autoclaved aerated concrete properties (strength, average density and thermal conductivity), and also the joint grinding influence on porosity of hardened cement paste made from portland cement clinker with mineral admixtures were investigated in the work. It was found that these factors ensure the production of non-autoclaved aerated concrete with an average density of 580 kg/m3, a compressive strength of 3.3 MPa and a thermal conductivity of 0.131 W / m · ° C.

Formation of optimal structure of cellular concrete

The paper presents the results of experimental studies on the effect of silica-containing components on the structure and properties of cellular concrete. It is shown that the creation of the optimal pore structure of concrete and the structure of the interporous frame, the intensification of hydration and crystallization processes in hydrothermal treatment can improve the physical and mechanical characteristics of cellular concrete. At the level of modern knowledge about the structure and properties of cellular concrete, the potential for increasing its strength characteristics has been studied. Through the effective use of the energy potentials of the multicomponent binder, including Portland cement, calcium lime and activated silica components, the nanopore structure of the matrix stone is formed.

A Novel Recycling Technology of Bamboo Using NaOH

The bamboo industry in Japan is declined, and disordered bamboo forests are increasing. Although maintenance of bamboo forest is needed, a large amount of bamboo wastes after logging is generated and left untreated. Therefore, new utilization of bamboo wastes after logging are desired. In this research, we aimed to develop a new recycling technology for bamboo using alkali hydroxide. By pyrolyzing bamboo using hydroxide under an inert atmosphere, thermal decomposition of organic contents and alkali fusion of silica component inside the bamboo were carried out simultaneously to recover combustible gas, charcoal and silica component. The thermal decomposition behavior of bamboo, the properties of the obtained charcoal and extraction of silica in the presence of alkali hydroxide were investigated, and the optimum condition of bamboo recycling treatment was examined. As a result, it was found that when 1 g of bamboo was pyrolyzed at higher than 500 °C with 3 g NaOH ,the almost silica was extracted, a large amount of gas generated, and a carbonized material with specific surface area of about more than 1100 m2 /g was obtained.

Effect of non-linear amplification of phase and amplitude modulations on laser-induced damage of thick fused silica optics with large beams at 351 nm

Nonlinear propagation of high power, large aperture laser beams leads to the amplification of the spatial pre-existing small scale modulations, and therefore locally increases the laser energy density as the beam propagates through the optical component. The measurement of the energy density distribution on the exit face of the tested component is therefore more challenging, as the impact of the propagation must be taken into account. It is for this reason that the damage densities of thick fused silica components have never been precisely measured. To this end, a dedicated imaging setup has been developed to accurately measure the energy density distribution on the exit face of 34-mm thick fused silica optical components during laser damage experiments with a centimeter-scale laser beam. The impact of nonlinear propagation on the beam spatial profile has been studied experimentally and confronted to numerical simulations that solve the nonlinear Schrödinger equation for the experimental spatial and phase profiles. The results clearly indicate that the imaging setup can accurately measure the amplification of the beam spatial modulations. The beam energy density on the exit face is therefore correctly measured and, for the first time, the damage density of thick optics can be accurately determined.

Karakterisasi Bionanofiller Dari Limbah Padi Sebagai Alternatif Penguatan Pada Polimer Komposit

<p>Agricultural waste such as rice straw, rice husk and rice husk ash have not been utilized properly. This waste of agricultural produce can actually be used as an alternative to bionanofiller because it contains an excellent source of silica. The silica content contained in the rice waste when combined with the polymer matrix can produce composites having high thermal and mechanical properties. Characterization of bionanofiller from this rice waste is done by SEM, XRF, FTIR, XRD and particle density. The result of SEM analysis from this rice waste is feasible to be used as filler because it has size 1 μm. Likewise with the results of XRF analysis that rice waste contains a high enough silica component that is 80.6255% - 89.83%. FTIR test results also show that bionanoparticles from rice waste have the same content of silica. In the XRD analysis the best selective gain of rice waste is found in rice husk ash which is characteristic of amorp silica at a range of 2ϴ = 22<br />. The largest density analysis of paddy waste was found in rice husk 0.0419 gr / cm , followed by rice straw by of 0.0417 gr / cm 3 and rice hulk ash 0.0407 g / cm 3</p>

Detection of the damage threshold of fused silica components and morphologies of repaired damage sites based on the beam deflection method

Abstract This article proposes a method to quickly detect the damage threshold of the fused silica components and the characteristics of the repair point damage. With a device detecting the beam deflection, the laser damage threshold is detected, quickly and effectively. Then, based on the beam deflection though mitigated sites, the beam deflection signals of the damage repair points are measured and the morphologies of mitigated sites are analyzed. This method is helpful in the online assessment of the damage resistance of the downstream optics and provides the guidance of the repair process.