Use:mainly used for ink-jet paper,coating,plastic, hatch master batch, count-static master batch etc.
|SiO2 ≥||99% |
|Supphate ≤||0.8% |
|Particle Size||3-5 um|
Apparent Density ≤
Packing: 10kg / bag or Upon clients' request..
Silicon dioxide, also known as silica (from the Latin silex), is a chemical compound that is an oxide of silicon with the chemical formula SiO2. It has been known since ancient times. Silica is most commonly found in nature as quartz, as well as in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and most abundant families of materials, existing both as several minerals and being produced synthetically. Notable examples include fused quartz, crystal, fumed silica, silica gel, and aerogels. Applications range from structural materials to microelectronics to components used in the food industry.
Silicon dioxide Production
Silicon dioxide is mostly obtained by mining and purification of quartz. Quartz comprises more than 10% by mass of the earth's crust. This product will be suitable for many purposes while for others chemical processing will be required to make a purer or otherwise more suitable (e.g. more reactive or fine-grained) product.
Silicon dioxide Fumed silica
Pyrogenic silica (sometimes called fumed silica or silica fume) is a very fine particulate or colloidal form of silicon dioxide. It is prepared by burning SiCl4 in an oxygen rich hydrocarbon flame to produce a "smoke" of SiO2.
SiCl4 + 2 H2 + O2 → SiO2 + 4 HCl.
Silicon dioxide Silica fume
This product is obtained as byproduct from hot processes like ferro-silicon production. It is less pure than fumed silica and should not be confused with that product. The production process, particle characteristics and fields of application of fumed silica are all different from those of silica fume.
Silicon dioxide Precipitated silica
Amorphous silica, silica gel, is produced by the acidification of solutions of sodium silicate. The gelatinous precipitate is first washed and then dehydrated to produce colorless microporous silica. Idealized equation involving a trisilicate and sulfuric acid is shown:
Na2Si3O7 + H2SO4 → 3 SiO2 + Na2SO4 + H2O
Approximately one billion kilograms/year (1999) of silica was produced in this manner, mainly for use for polymer composites – tires and shoe soles.
Silicon dioxide On microchips
Thin films of silica grow spontaneously on silicon wafers via thermal oxidation. This route gives a very shallow layer (approximately 1 nm or 10 ?) of so-called native oxide. Higher temperatures and alternative environments are used to grow well-controlled layers of silicon dioxide on silicon, for example at temperatures between 600 and 1200 °C, using so-called dry or wet oxidation with O2 or H2O, respectively. The depth of the layer of silicon replaced by the dioxide is 44% of the depth of the silicon dioxide layer produced.
The native oxide layer can be beneficial in microelectronics, where it acts as electric insulators with high chemical stability. In electrical applications, it can protect the silicon, store charge, block current, and even act as a controlled pathway to limit current flow.
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From silicate esters
Many routes to silicon dioxide start with silicate esters, the best known being tetraethyl orthosilicate (TEOS). Simply heating TEOS at 680–730 °C gives the dioxide:
Si(OC2H5)4 → SiO2 + 2 O(C2H5)2
Similarly TEOS combusts around 400 °C:
Si(OC2H5)4 + 12 O2 → SiO2 + 10 H2O + 8 CO2
TEOS undergoes hydrolysis via the so-called sol-gel process. The course of the reaction and nature of the product are affected by catalysts, but the idealized equation is:
Si(OC2H5)4 + 2 H2O → SiO2 + 4 HOCH2CH3
Being highly stable, silicon dioxide arises from many methods. Conceptually simple, but of little practical value, combustion of silane gives silicon dioxide. This reaction is analogous to the combustion of methane:
SiH4 + 2 O2 → SiO2 + 2 H2O.
Silicon dioxide Uses
An estimated 95% of silicon dioxide produced is consumed in the construction industry, e.g. for the production of Portland cement. Other major applications are listed below.
Precursor to glass and silicon
Silica is used primarily in the production of glass for windows, drinking glasses, beverage bottles, and many other uses. The majority of optical fibers for telecommunication are also made from silica. It is a primary raw material for many ceramics such as earthenware, stoneware, and porcelain.
Silicon dioxide is used to produce elemental silicon. The process involves carbothermic reduction in an electric arc furnace:
SiO2 + 2 C → Si + 2 CO
Major component used in sand casting
Silica, in the form of sand is used as the main ingredient in sand casting for the manufacture of a large number of metallic components in engineering and other applications. The high melting point of silica enables it to be used in such applications.
Food and pharmaceutical applications
Silica is a common additive in the production of foods, where it is used primarily as a flow agent in powdered foods, or to adsorb water in hygroscopic applications. It is the primary component of diatomaceous earth. Colloidal silica is also used as a wine, beer, and juice fining agent.
In pharmaceutical products, silica aids powder flow when tablets are formed.
A silica-based aerogel was used in the Stardust spacecraft to collect extraterrestrial particles. Silica is also used in the extraction of DNA and RNA due to its ability to bind to the nucleic acids under the presence of chaotropes. Hydrophobic silica is used as a defoamer component. In hydrated form, it is used in toothpaste as a hard abrasive to remove tooth plaque.
In its capacity as a refractory, it is useful in fiber form as a high-temperature thermal protection fabric. In cosmetics, it is useful for its light-diffusing properties and natural absorbency. It is also used as a thermal enhancement compound in ground source heat pump industry.
Silicon dioxide Structure
Structural motif found in α-quartz, but also found in almost all forms of silicon dioxide.
In the majority of silicates, the Si atom shows tetrahedral coordination, with 4 oxygen atoms surrounding a central Si atom. The most common example is seen in the quartz crystalline form of silica SiO2. In each of the most thermodynamically stable crystalline forms of silica, on average, all 4 of the vertices (or oxygen atoms) of the SiO4 tetrahedra are shared with others, yielding the net chemical formula: SiO2.
Relation between refractive index and density for some SiO2 forms.
For example, in the unit cell of α-quartz, the central tetrahedron shares all 4 of its corner O atoms, the 2 face-centered tetrahedra share 2 of their corner O atoms, and the 4 edge-centered tetrahedra share just one of their O atoms with other SiO4 tetrahedra. This leaves a net average of 12 out of 24 total vertices for that portion of the 7 SiO4 tetrahedra that are considered to be a part of the unit cell for silica (see 3-D Unit Cell).
SiO2 has a number of distinct crystalline forms (polymorphs) in addition to amorphous forms. With the exception of stishovite and fibrous silica, all of the crystalline forms involve tetrahedral SiO4 units linked together by shared vertices in different arrangements. Silicon–oxygen bond lengths vary between the different crystal forms, for example in α-quartz the bond length is 161 pm, whereas in α-tridymite it is in the range 154–171 pm. The Si-O-Si angle also varies between a low value of 140° in α-tridymite, up to 180° in β-tridymite. In α-quartz the Si-O-Si angle is 144°.
Fibrous silica has a structure similar to that of SiS2 with chains of edge-sharing SiO4 tetrahedra. Stishovite, the higher-pressure form, in contrast has a rutile-like structure where silicon is 6-coordinate. The density of stishovite is 4.287 g/cm3, which compares to α-quartz, the densest of the low-pressure forms, which has a density of 2.648 g/cm3. The difference in density can be ascribed to the increase in coordination as the six shortest Si-O bond lengths in stishovite (four Si-O bond lengths of 176 pm and two others of 181 pm) are greater than the Si-O bond length (161 pm) in α-quartz. The change in the coordination increases the ionicity of the Si-O bond. But more important is the observation that any deviations from these standard parameters constitute microstructural differences or variations, which represent an approach to an amorphous, vitreous or glassy solid.
The only stable form under normal conditions is α-quartz and this is the form in which crystalline silicon dioxide is usually encountered. In nature impurities in crystalline α-quartz can give rise to colors (see list). The high temperature minerals, cristobalite and tridymite, have both a lower density and index of refraction than quartz. Since the composition is identical, the reason for the discrepancies must be in the increased spacing in the high temperature minerals. As is common with many substances, the higher the temperature the farther apart the atoms due to the increased vibration energy.
The transformation from α-quartz to beta-quartz takes place abruptly at 573 °C. Since the transformation is accompanied by a significant change in volume it can easily induce fracturing of ceramics or rocks passing through this temperature limit.
The high-pressure minerals, seifertite, stishovite, and coesite, on the other hand, have a higher density and index of refraction when compared to quartz. This is probably due to the intense compression of the atoms that must occur during their formation, resulting in a more condensed structure.
Faujasite silica is another form of crystalline silica. It is obtained by dealumination of a low-sodium, ultra-stable Y zeolite with a combined acid and thermal treatment. The resulting product contains over 99% silica, has high crystallinity and high surface area (over 800 m2/g). Faujasite-silica has very high thermal and acid stability. For example, it maintains a high degree of long-range molecular order (or crystallinity) even after boiling in concentrated hydrochloric acid.
Molten silica exhibits several peculiar physical characteristics that are similar to the ones observed in liquid water: negative temperature expansion, density maximum (at temperatures ~5000 °C), and a heat capacity minimum. Its density decreases from 2.08 g/cm3 at 1950 °C to 2.03 g/cm3 at 2200 °C. When molecular silicon monoxide, SiO, is condensed in an argon matrix cooled with helium along with oxygen atoms generated by microwave discharge, molecular SiO2 is produced with a linear structure. Dimeric silicon dioxide, (SiO2)2 has been prepared by reacting O2 with matrix isolated dimeric silicon monoxide, (Si2O2). In dimeric silicon dioxide there are two oxygen atoms bridging between the silicon atoms with an Si-O-Si angle of 94° and bond length of 164.6 pm and the terminal Si-O bond length is 150.2 pm. The Si-O bond length is 148.3 pm, which compares with the length of 161 pm in α-quartz. The bond energy is estimated at 621.7 kJ/mol.
Silicon dioxide Fused quartz
When molten silicon dioxide SiO2 is rapidly cooled, it does not crystallize but solidifies as a glass. The geometry of the silicon and oxygen centers in glass is similar to that in quartz and most other crystalline forms of the same composition, i.e., silicon is surrounded by a regular tetrahedra of oxygen centers. The difference between the glass and the crystalline forms arise from the connectivity of these tetrahedral units. Although there is no long range periodicity in the glassy network there remains significant ordering at length scales well beyond the SiO bond length. One example of this ordering is found in the preference of the network to form rings of 6-tetrahedra.
The glass transition temperature of pure SiO2 is about 1475 K.
Silicon dioxide Chemical reactions
Manufactured silica fume at maximum surface area of 380 m2/g
Silica is converted to silicon by reduction with carbon.
Fluorine reacts with silicon dioxide to form SiF4 and O2 whereas the other halogen gases (Cl2, Br2, I2) are essentially unreactive.
Silicon dioxide is attacked by hydrofluoric acid (HF) to produce hexafluorosilicic acid:
SiO2 + 6 HF → H2SiF6 + 2 H2O.
HF is used to remove or pattern silicon dioxide in the semiconductor industry.
Silicon dioxide acts as a Lux-Flood acid, being able to react with bases under certain conditions. As it does not contain any hydrogen, it cannot act as a Br?nsted–Lowry acid. While not soluble in water, some strong bases will react with glass and have to be stored in plastic bottles as a result.
Silicon dioxide dissolves in hot concentrated alkali or fused hydroxide, as described in this idealized equation:
SiO2 + 2 NaOH → Na2SiO3 + H2O.
Silicon dioxide will neutralise basic metal oxides (e.g. sodium oxide, potassium oxide, lead(II) oxide, zinc oxide, or mixtures of oxides, forming silicates and glasses as the Si-O-Si bonds in silica are broken successively). As an example the reaction of sodium oxide and SiO2 can produce sodium orthosilicate, sodium silicate, and glasses, dependent on the proportions of reactants:
2 Na2O + SiO2 → Na4SiO4;
Na2O + SiO2 → Na2SiO3;
(0.25–0.8)Na2O + SiO2 → glass.
Examples of such glasses have commercial significance, e.g. soda-lime glass, borosilicate glass, lead glass. In these glasses, silica is termed the network former or lattice former. The reaction is also used in blast furnaces to remove sand impurities in the ore by neutralisation with calcium oxide, forming calcium silicate slag.
Bundle of optical fibers composed of high purity silica.
Silicon dioxide reacts in heated reflux under dinitrogen with ethylene glycol and an alkali metal base to produce highly reactive, pentacoordinate silicates which provide access to a wide variety of new silicon compounds. The silicates are essentially insoluble in all polar solvent except methanol.
Silicon dioxide reacts with elemental silicon at high temperatures to produce SiO:
SiO2 + Si → 2 SiO
Silicon dioxide Solubility in water
The solubility of silicon dioxide in water strongly depends on its crystalline form and is 3–4 times higher for silica than quartz; as a function of temperature, it peaks at about 340 °C. This property is used to grow single crystals of quartz in a hydrothermal process where natural quartz is dissolved in superheated water in a pressure vessel that is cooler at the top. Crystals of 0.5–1 kg can be grown over a period of 1–2 months. These crystals are a source of very pure quartz for use in electronic applications.
Silicon dioxide Occurrence
Even though it is poorly soluble, silica occurs widely in many plants. Plant materials with high silica phytolith content appear to be of importance to grazing animals, from chewing insects to ungulates. Studies have shown that it accelerates tooth wear, and high levels of silica in plants frequently eaten by herbivores may have developed as a defense mechanism against predation.
It is also the primary component of rice husk ash, which is used, for example, in filtration and cement manufacturing.
Silicification in and by cells has been common in the biological world for well over a billion years. In the modern world it occurs in bacteria, single-celled organisms, plants, and animals (invertebrates and vertebrates). Prominent examples include:
Tests or frustules (i.e. shells) of diatoms, Radiolaria and testate amoebae.
Silica phytoliths in the cells of many plants, including Equisetaceae, practically all grasses, and a wide range of dicotyledons.
The spicules forming the skeleton of many sponges.
Crystalline minerals formed in the physiological environment often show exceptional physical properties (e.g., strength, hardness, fracture toughness) and tend to form hierarchical structures that exhibit microstructural order over a range of scales. The minerals are crystallized from an environment that is undersaturated with respect to silicon, and under conditions of neutral pH and low temperature (0–40 °C).
Formation of the mineral may occur either within the cell wall of an organism (such as with phytoliths), or outside the cell wall, as typically happens with tests. Specific biochemical reactions exist for mineral deposition. Such reactions include those that involve lipids, proteins, and carbohydrates.
It is unclear in what ways silica is important in the nutrition of animals. This field of research is challenging because silica is ubiquitous and in most circumstances dissolves in trace quantities only. All the same it certainly does occur in the living body, leaving us with the problem that it is hard to create proper silica-free controls for purposes of research. This makes it difficult to be sure when the silica present has had operative beneficial effects, and when its presence is coincidental, or even harmful. The current consensus is that it certainly seems important in the growth, strength, and management of many connective tissues. This is true not only for hard connective tissues such as bone and tooth but possibly in the biochemistry of the subcellular enzyme-containing structures as well.
Silicon dioxide health effects
Quartz sand (silica) as main raw material for commercial glass production
Silica ingested orally is essentially nontoxic, with an LD50 of 5000 mg/kg (5 g/kg). On the other hand, inhaling finely divided crystalline silica dust can lead to silicosis, bronchitis, or cancer, as the dust becomes lodged in the lungs and continuously irritates them, reducing lung capacities. Studies of workers with exposure to crystalline silica have shown 10-fold higher than expected rates of lupus and other systemic autoimmune diseases compared to expected rates in the general population. Prior to new rules issued in 2013, OSHA allowed 100 μg per cubic meter of air. The new regulations reduce the amount to 50 μg/m3. The exposure limit for the construction industry is also set at 50 μg/m3 down from 250 μg/m3.
In the body, crystalline silica particles do not dissolve over clinically relevant periods. Silica crystals inside the lungs can activate the NLRP3 inflammasome inside macrophages and dendritic cells and thereby result in processing of pro-Interleukin 1 beta into its mature form. Chronic exposure to silica may thereby account for some of its health hazards, as interleukin-1 is a highly pro-inflammatory cytokine in the immune system. This effect can create an occupational hazard for people working with sandblasting equipment, products that contain powdered crystalline silica and so on. Children, asthmatics of any age, allergy sufferers, and the elderly (all of whom have reduced lung capacity) can be affected in much less time. Amorphous silica, such as fumed silica is not associated with development of silicosis, but may cause irreversible lung damage in some cases. Laws restricting silica exposure with respect to the silicosis hazard specify that they are concerned only with silica that is both crystalline and dust-forming.
A study that followed subjects for 15 years found that higher levels of silica in water appeared to decrease the risk of dementia. The study found an association between an increase of 10 milligram-per-day of the intake of silica in drinking water with a decreased risk of dementia of 11%.
Crystalline silica is used in hydraulic fracturing of formation which contain tight oil and shale gas, a use which presents a health hazard to workers. In 2013 OSHA announced tightened restrictions on the amount of crystalline silica which could be present and required "green completion" of fracked wells to reduce exposure. Crystalline silica is an occupational hazard for those working with stone countertops, because the process of cutting and installing the countertops creates large amounts of airborne silica.
Application of nano-silicon dioxide in the biomedical field:
Nano-silicon dioxide, a three-dimensional network structure, there is a lot of surface residual unsaturated bond and a hydroxyl group in different states, which makes nano-SiO2 has a high surface energy, in a thermodynamically unstable state, and with high chemical activity. Due to the mesoporous silicon dioxide having ordered mesoporous structure, large specific surface area, good biocompatibility and easy surface modification, etc., that shows great prospect in the fields of bio-medicine. The research progress in targeting and imaging modified mesoporous silica multifunctional drug delivery systems were discussed, nano-silicon dioxide composite applications in biology, medicine, membrane science were prospected. Nano-silicon dioxide also have some effect on apoptosis in cultured HaCaT. Nano-SiO2 is a large-scale production of nano-materials, nano-SiO2 amorphous and oral inhalation because of the living body does not cause direct harm is considered to be safe biological nano-materials, has been widely used in disease diagnosis, biological analysis and research imaging, drug delivery, etc., resulting in the increasing of the way into the body, the study of its impact on human health is particularly important to realize it as a widely used biomaterial.
Nano-silicon dioxide material is a hot research in the 21st century, because of its large number of hydroxyl groups present on the surface of an unsaturated bond residue and different states, since the mesoporous silica having ordered and continuously adjustable mesoporous structure, large specific surface area and excellent Ease of biocompatibility and surface modification, etc., make it as a drug delivery systems research focus. In addition, because of its small size effect, quantum size effect and macroscopic quantum tunneling effect, so that the composite nanoparticles having a strange physical and chemical properties. In recent years, researchers continue to explore the advantages of nano-SiO2, at the same time, by restructuring and reorganization of the material prepared by a variety of types of composite materials, which greatly improved the monodisperse of nano-silicon dioxide, the difficult dispersion and ease of reunion and other shortcomings, making many performance has been further optimized and upgraded. It can be widely used in biology, medicine, membrane science and pesticides.
With the development of the establishment of nanotechnology and nano-drug delivery system, many traditional pharmaceutical field problems has been solved, nano-treatment system compared to conventional drugs, targeting its bioavailability and etc. have greatly improved, while these new systems may improve drug stability and drug release kinetics behavior to a greater extent to improve the therapeutic effect and reduce side effects. Therefore, the development of new, diverse nano-drug delivery system throughout Nanobiomedical important issue. Currently, there is a common pharmaceutical carrier liposomes, polymers, particles of gold (Au), mesoporous silicon dioxide (MSN), quantum dots (QD) and etc.. In recent years, inorganic nanoparticles because of their unique properties of light, electricity, magnetism, the size, morphology controllable, large specific surface area and a series of advantages, have attracted wide attention.
Preparation of nano-silicon dioxide particles:
Precipitation: the substance of different chemical compositions were first mixed in solution, the mixed solution was added agent that used to precipitate the appropriate precursors for precipitating, then dried or calcined the precipitate, to obtain the corresponding nanoparticles. Some researcher using the mass fraction of 95% to 98% concentrated H2SO4 and Na2SiO3.9H2O reaction using H2SO4 exothermic reaction was carried out smoothly, and adding a certain amount of dispersants, surfactants during the reaction to prevent the primary particles reunion, prepared a highly dispersed nano-silicon dioxide.
Sol - gel method: refers to the use of high chemical activity of silicon compounds as raw materials, such as silicates, silicates, which was dubbed the solution, after the addition of a strong acid, in order to induce polymerization of silicate, hydrolysis and condensation reaction. Sol formed in solution stable transparent system by slow polymerization aged between particles to form a three-dimensional network structure of the gel, when the inter-network full of solvent lost liquidity, they form a gel, the gel is dried, prepared nano-silicon dioxide.
Microemulsion: two immiscible solvent is formed under the action of a surfactant emulsions in microvesicles by nucleation, coalescence, agglomeration, nanoparticles were obtained after heat treatment.
Currently the most widely used methods were sol - gel silicon dioxide nanoparticles prepared and hydrothermal synthesis, these two methods are mainly use organic silicon source as raw materials, organic surfactant as a template to form nanoparticles, then removing the template by solvent extraction or calcination process, the mesoporous silica nano-particles were formed. Since mesoporous silicon dioxide having a stable framework structure and pore size rule within the range of 2 ~ 50 nm continuous tone, hydroxyl-rich surface is easy to modify, etc., it can be effectively loading and transportation of different sizes and types of drugs.
In recent years with the diagnosis and treatment of diseases, especially cancer, efficient, functional drug carriers modifications are also increasingly diverse, and has successfully targeted a variety of functions, imaging, diagnosis and treatment. Thus, multi-mesoporous silicon dioxide nano-drug delivery system is a new class of nano-drug delivery system has great application value. On the other hand, nanomaterials synthesis, surface modification technology accuracy and diversity of topography and so control has been a great development, morphology of mesoporous silicon dioxide is also more abundant. Currently reported in the literature have been successfully prepared mesoporous silicon dioxide material rod, tube, ellipsoidal, cage-like, film-like, hollow and folders mentality and other novel structure, and its release kinetics in drug delivery and improve drug science and other areas of in-depth discussions.
Multifunction targeting modified mesoporous nano-silicon dioxide delivery systems:
Compared to conventional drugs, targeting nano-drug delivery system, timeliness, efficiency and etc. have greatly improved. In the case of cancer, the most commonly used treatments have surgery, chemotherapy, gene therapy, radiation therapy, hyperthermia, photodynamic therapy, these treatments, although to some extent, played a patient to relieve symptoms and prolong life role, but because drugs can not effectively distinguish between normal tissue and the lesion sites on normal cells and tissues also cause serious damage, so the side effects are huge. Nano-drug delivery system itself has a unique size effect, you can also modify its functionality, in order to achieve the target lesion site aggregation.
Nano drug delivery targeting transfer systems include passive and active targeting targeting in two ways, namely passive targeting nano-delivery system through the EPR effect in tumor tissue tumor tissue preferentially enriched in the process; namely active targeting nano-delivery system by coupling linking specific ligand or antibody component binding to specific receptors on the cell surface, in order to achieve the targeted tissue accumulation. Excellent support mesoporous silicon dioxide material is considered a transfer of anti-cancer drugs and targeting molecules.
Morelli and etc. use PEG as a template synthesis of mesoporous silicon dioxide, and modified to form a folate-targeted drug delivery system MSN-FOL. HeLa cells with folate receptor positive and negative HEK293 cells as a model, was found carrying cisplatin MSN-FOL HeLa cells have strong growth inhibition, indicating that the system has a selective targeting. The magnetic nanoparticles and mesoporous SiO2 nanoparticle composite can be used as magnetic resonance imaging (MRI) contrast agents. Korea Hyeon group prepared a series of Fe3O4-modified mesoporous silica composite system, and applied to magnetic resonance imaging, drug delivery and so on.
Pan and etc. use mesoporous silica surface modified TAT polypeptide molecules having a nuclear targeting, and resistant cell line as a model, experiments show that the targeting system can greatly enhance the uptake of the drug-resistant cells, and drugs gathered a large number of nuclear sites, so you can achieve better therapeutic effect.
Applications of composite Nano-silicon dioxide in biomedical field:
Application of Antibacterial:
Use of the large specific surface area, multi-dielectric structure and strong adsorption capacity and singular physicochemical properties of nano-silicon dioxide, antibacterial silver ion particles are uniformly designed to mesoporous SiO2 nanoparticles, and to develop efficient, persistent high temperature, broad-spectrum antimicrobial nano-antibacterial powder. Liuyun Ying and other prepared silicon dioxide nano silver antimicrobial powder material, was tested for its antibacterial properties, results showed that 3% of the silver nano-silicon dioxide prepared antibacterial powder in the sintering temperature range of 80-140 bars colon and Staphylococcus aureus bacteria sterilization rate of almost 100%, with excellent antibacterial properties, can be used for antibacterial plastics, antibacterial and antibacterial food packaging, textiles and other fields.
Application of Nano-silicon dioxide in biological enzyme field:
In recent years, there have been many reports of nano materials and organic and inorganic composite material consisting of carriers for enzyme immobilization, as in new materials immobilized material, the metal nanoparticles exhibit many excellent properties, greatly improving the fixed vitality enzyme, showing excellent results.
Application in biomarkers and monitoring:
Inorganic nanocrystals known as quantum dots, in the biological area shown broad application prospects, especially as fluorescent probes for biomarkers, biological testing and other aspects of biological imaging. High molecular quantum dots are generally lipophilic, the need for water soluble modified. Single amino prepared Zhangbing Bo and other dispersion of silicon dioxide quantum dots, the nucleus from a single molecule level surface markers of tumor cells all the negative charge, intuitive reaction of a single cell surface charge distribution. In addition, the composite nano-SiO2 in science film also has some applications, organic - inorganic composite material capable of maintaining the advantages of the two components to improve the shortcomings of the two components, thereby enhancing the overall performance of the resulting material, manufacture organic - inorganic hybrid film, so that both the inorganic film and the organic film strengths, materialized in the film stability, and through the separation performance, stain resistance and other aspects have improved significantly.
The study of quantitative proteomics of nano-silicon dioxide affect human lung cancer cells:
Nano-silicon dioxide is a large-scale production of nano-materials, because of amorphous nano-SiO2 and oral inhalation does not cause directly harm to the living body, it is considered to be safe biological nano-materials, has been widely used in disease diagnosis, biological analysis and imaging, drug delivery,and etc., resulting in its way into the body increasing, the study of its impact on human health is particularly important to realize it as a biomaterial widely used.
After silicon dioxide nanomaterials and cells were incubated, optical microscopy and transmission electron microscopy characterization, the material into the interior of the cell, which can be seen in the transmission electron microscope in the form of vesicles within the cell exists. When silicon dioxide treated 24 h, low concentrations of SiO2 less toxic, but the processing time to 48 h, significantly increased cytotoxicity than 24 h, and with the increase of the amount of material increases. In SiO2 concentration of 200 μg / mL, the cell survival rate has dropped to about 50%. When the material in a concentration of 50 μg / mL A549 cells were cultured at 48 h, cell survival rate of about 70%, then the silicon dioxide cells have a certain degree of damage, and can guarantee the majority of cells are still alive.
Hazards of silicon dioxide dust:
Silicon dioxide in daily life, production and scientific research has an important purpose, but sometimes cause harm to humans.
Fine silicon dioxide dust than the surface area of 100m2 / g or more may be suspended in the air, if people long-term inhalation of dust containing silicon dioxide, it will suffer from silicosis (because silicon called silicon-old, formerly known as silicosis silicosis) .
Silicosis is an occupational disease, its occurrence and severity, depending on the content of dust in the air and dust in silicon dioxide content, as well as human contact time. Long-term higher silicon dioxide dust content in place, such as a human mining, foundry, sandblasting, made ceramics, refractories and other places of work made easy to contracting this disease.
Thus, in these more dust in the workplace, due to strict labor protection measures, using a variety of techniques and equipment to control dust content in the workplace, in order to ensure the health of staff.
Silicon dioxide is an international common food additives:
Silicon dioxide is an international common food additives. It can solve the product due to moisture absorption caking under pressure formed simultaneously with adsorption, it is a good flow accelerator. For protein powder, milk powder, cocoa powder, sugar, vegetable powder, instant coffee, cereals and other foods. Add food mostly silicon dioxide powder, and silicon dioxide which function in food - related anti-coagulant. Powdered food due to temperature changes, humidity increases or heap pressure between the bag and the bag and other reasons, easy to stick together agglomeration, affect product quality and shelf life. Silicon dioxide can play the role of "film" of the dolphin powder wrapped up, so that the powder separated from each other, in the best of the free-flowing state, to achieve the purpose of anti-caking.
In addition, the silicon dioxide powder wrapped outside, with numerous internal pores absorb ambient moisture in the air, but also to prevent moisture caking during storage of food.
As a food additive, silicon dioxide safety quite tricky, because after being ingested, its chemical properties remain stable in the human body will not break down, it will not be absorbed, how that last place? Only together with the feces, so it will not constitute a hazard to human health.
This caused the silicon dioxide with "silicosis" are completely different, "silicosis" is an occupational disease, its occurrence and severity, depending on the content of dust in the air and dust content of silicon dioxide, and and human contact time. Long-term higher silicon dioxide dust content in place, such as a human mining, foundry, sandblasting, made ceramics, refractories and other places of work made easy to contracting this disease. Into the human body through diet channels silicon dioxide does not pose any threat. This is mainly to two factors: the intake of different ways, with different particle sizes.
According to China's current food additive standard, maximum use of silicon dioxide in frozen drinks, salt and salt substitutes and other food products from the 25 mg / kg to 20 g / kg range, in a number of food additives that may be used the upper limit of the amount be set relatively loose, it also reflects the higher authorities assured the extent of silicon dioxide from the side.
Crystalline silicon dioxide:
16 km from the ground down almost 65% silicon dioxide(SiO2) ore, mainly in the crystalline silicon dioxide(SiO2) quartz ore (ie, the main component is quartz silicon dioxide(SiO2)). More pure quartz as colorless crystals, can be used to prepare the silicon dioxide glass, some of the high temperature chemistry laboratory equipment used is made of quartz glass, UV permeable quartz glass, can be used in the manufacture of medical and used in a mine mercury quartz lamps and other optical instruments, quartz drawn into a wire, the wire has great strength and flexibility, an important new use of quartz glass, is the production of optical fiber used in communications on the light guide, in the information age today, with a microwave and a metal wire transfer information can not meet the communication needs to work in order to enhance the capacity and transfer speed of transmitting information, the frequency of the transmitted signal must be greatly improved, in optical communications, quartz fiber as a conductor can do its faster than previous methods to increase the number of times faster, greatly improve the frequency, its low cost of production, laying fiber optic cables need a million yuan per kilometer, while the previous ordinary cables per kilometer takes 20 million, it's light quality, not afraid of corrosion, the laying of convenience, as long as 27 g per km, while the previous ordinary cables to 1.6 t, its large amount of information on each cable at the same time by one billion people call, you can also send multiple sets TV programs, good performance, anti-electromagnetic interference, confidentiality, can prevent eavesdropping, no electron radiation, and its wide source of raw materials, non-ferrous metals saving, quartz flakes do intermittent done under the influence of a high frequency electric field and contraction, the same frequency and the frequency of the applied electric field, this stretch of quartz in turn causes the surrounding medium to produce similar sound waves, since quartz has this property, it is widely used in the watch industry and ultrasound technology.
Silicon dioxide act as pharmaceutical excipients:
(1)Physical and chemical properties of silicon dioxide:
Silicon dioxide as a white, odorless, hygroscopic, fine amorphous powder, plasmid average diameter of 20 ~ 0nm, the relative density of 2.2 to 2.6. Insoluble in water, ethanol and other organic solvents, do not dissolve in acid (hydrofluoric acid exceptions), was dissolved in hot sodium hydroxide solution.
(2)Usage and dosage of silicon dioxide:
Silicon dioxide in pharmaceutical manufacturing, mainly used as disintegrating agents, anti-sticking agents, glidants. Silicon dioxide can greatly improve the particle flowability, bulk density increase, so that the resulting increase in tablet hardness, disintegration time shortened to improve the dissolution rate of drugs. In the granules can be used for the manufacture of desiccant, in order to enhance the stability of drugs. Silicon dioxide is one of the microencapsulated material, added to the product in a bag, make microcapsules density and specific surface area increased mobility enhancement. Silicon dioxide can also be used as a filter aid, fining agents and defoamers, and liquid preparations suspending agents, thickening agents. Silicon dioxide in the food industry has a similar purpose.
(3)Silicon Dioxide: [The International Pharmacopoeia (Ph. Int.)] Standard:
Silicon Dioxide is obtained by insolubilizing the dissolved silicon dioxide in sodium silicate solution. Where obtained by the addition of sodium silicate to a mineral acid, the product is termed silica gel; where obtained by the destabilization of a solution of sodium silicate in such manner as to yield very fine particles, the product is termed precipitated silicon dioxide. After ignition at 1000 for not less than 1 hour, it contains not less than 99.0 percent of silicon dioxide(SiO2).
Packaging and storage— Preserve in tight containers, protected from moisture.
Labeling— Label it to state whether it is silicon dioxide gel or precipitated silicon dioxide.
Identification— Transfer about 5 mg to a platinum crucible, mix with about 200 mg of anhydrous potassium carbonate, ignite at a red heat over a burner for 10 minutes, and cool. Dissolve the melt in 2 mL of recently distilled water, warming if necessary, and slowly add 2 mL of ammonium molybdate TS: a deep yellow color is produced.
pH 791: between 4 and 8,in a slurry (1 in 20).
Loss on drying 731— Dry it at 145 for 4 hours: it loses not more than 5.0% of its weight.
Loss on ignition 733— Ignite about 1 g of it, previously dried and accurately weighed, at 1000 for not less than 1 hour: it loses not more than 8.5% of its weight.
Chloride 221— Boil 5 g in 50 mL of water under a reflux condenser for 2 hours, cool, and filter. A 7-mL portion of the filtrate shows no more chloride than corresponds to 1.0 mL of 0.020 N hydrochloric acid (0.1%).
Sulfate 221— A 10-mL portion of the filtrate obtained in the test for Chloride shows no more sulfate than corresponds to 5.0 mL of 0.020 N sulfuric acid (0.5%).
Arsenic, Method I 211— Prepare the Test Preparation as follows. Transfer 4.0 g to a platinum dish, add 5 mL of nitric acid and 35 mL of hydrofluoric acid, and evaporate on a steam bath. Cool, add 5 mL of perchloric acid, 10 mL of hydrofluoric acid, and 10 mL of sulfuric acid, and evaporate on a hot plate to the production of heavy fumes. Cool, cautiously transfer to a 100-mL beaker with the aid of a few mL of hydrochloric acid, and evaporate to dryness. Cool, add 5 mL of hydrochloric acid, dilute with water to about 40 mL, and heat to dissolve any residue. Cool, transfer to a 100-mL volumetric flask, dilute with water to volume, and mix. A 25.0-mL portion of this solution meets the requirements of the test. The limit is 3 ppm.
Heavy metals, Method I 231— Transfer 16.7 mL of the solution prepared for the test for Arsenic into a 100-mL beaker, and neutralize with ammonium hydroxide to litmus paper. Adjust with 6 N acetic acid to a pH of between 3 and 4. Filter, using medium-speed filter paper, wash with water until the filtrate and washings measure 40 mL, and mix. The limit is 0.003%.
Assay— Transfer about 1 g of silicon dioxide Gel to a tared platinum dish, ignite at 1000 for 1 hour, cool in a desiccator, and weigh. Carefully wet with water, and add about 10 mL of hydrofluoric acid, in small increments. Evaporate on a steam bath to dryness, and cool. Add about 10 mL of hydrofluoric acid and about 0.5 mL of sulfuric acid, and evaporate to dryness. Slowly increase the temperature until all of the acids have been volatilized, and ignite at 1000. Cool in a desiccator, and weigh. The difference between the final weight and the weight of the initially ignited portion represents the weight of silicon dioxide(SiO2).
Is Silicon Dioxide Safe?
When you look on a food or supplement ingredients list, you often see things you’ve never heard of, some of them you can’t even pronounce. Though many of these ingredients may seem alarming (and some with good reason), others are safe and it’s merely their name that is off-putting. Silicon dioxide is one such ingredient, found in many products, though often misunderstood.
Why Is It in Food and Supplements?
Along with being found pretty much everywhere on earth, silicon dioxide is found in foods and supplements. But, why?
First, as a food additive, silicon dioxide serves as an anticaking agent. It is used to prevent clumping. In supplements, it’s used to prevent the various powdered ingredients from sticking together.
As with many food additives, consumers often have concerns about finding silicon dioxide on product labels. However, numerous studies have found no health risks associated with this particular ingredient.
Silicon dioxide is found naturally in many plants. For example, leafy green vegetables, beets, bell peppers, brown rice and oats, and alfalfa.
What the Research Says
The fact that it’s found in plants and drinking water, suggests it is safe. But in addition, research has shown that the silica we consume doesn’t accumulate in our bodies; rather, it’s flushed out by the kidneys.
While many of the studies on silica have been done on animals, they have found no link between silicon dioxide and increased risk of cancer, organ damage, or mortality. In addition, studies have found no evidence that silicon dioxide can affect reproductive health, birth weight, or body weight.
Finally, the Food and Drug Administration (FDA) has recognized silicon dioxide as a safe food additive, as do the World Health Organization (WHO) and the European Food Safety Authority (EFSA).
According to a paper prepared in association with WHO, the only negative health effects related to silicon dioxide have been caused by silicon deficiency. In other words, a lack of silicon dioxide may do more harm than too much.
Have Safe Limits Been Set?
Though the research doesn’t indicate any risks associated with silicon dioxide ingestion, the FDA and other global health organizations have set upper limits on its consumption. This is mainly because amounts higher than these set limits have not been sufficiently studied.
In the United States, the FDA says silicon dioxide should not exceed 2 percent of a food’s total weight.
Silicon dioxide exists naturally within the earth and our bodies. There is no evidence to suggest it is dangerous.
Silicon dioxide is a trace mineral found naturally in many plant foods and is added to many multivitamin supplements. It is necessary for healthy bones, skin, hair and nails. Silicon dioxide is often added to processed foods to keep them fresh and appetizing. You can find the important mineral in foods sources.
Foods High in Silicon Dioxide
RDI (Recommended daily intake)
As a trace mineral, only a small amount of silicon dioxide is needed daily. Many nutritionists believe the human body requires about 5-10 mg of this mineral each day.
Since the recommended daily allowance of silicon dioxide is relatively low, it is easy to get the correct amount if you eat a well-balanced diet. Foods to include in your diet are:
Not often mentioned in nutrition literature is the fact that many fruits are naturally high in silicon dioxide. The fruits highest in the mineral include raisins, grapes, oranges, apples, cherries and plums.
There are several vegetables that can provide some of the recommended daily allowance of silicon dioxide. Vegetables with silicon dioxide include artichokes, beans, peas, asparagus, beet, greens of all kinds, celery, cucumbers, lettuce, radishes and onions.
In addition to the other nutrients in nuts, almonds and peanuts contain moderately high amounts of silicon dioxide.
4. Sunflower seeds
Also known for high nutritional value, roasted sunflower seeds also contain a healthy amount of silicon dioxide.
5. Pumpkin seeds
Roasted pumpkin seeds have a moderate amount of silicon dioxide so make a simple but healthy snack.
6. Whole grains
Rice, oats and whole grain breads are high in silicon dioxide. Eating whole grains is an easy way to fill the daily requirement for this trace mineral.
Normal drinking water is a possible source of silicon dioxide. Hard water has higher levels of the mineral than soft water.
Coffee, tea and other beverages made with water will contain some amount of silicon dioxide. Beer is an excellent source of the mineral in addition to being a tasty drink. The silicon dioxide in beer is in the form of orthosilicic acid, which is important for bone health and to prevent osteoporosis.
Horsetail has the most amount of silicon dioxide of all the herbs. Parsley and garlic are two other herbs that provide a relatively high amount of the mineral. Horsetail is believed to be highest in silicon dioxide. You can find extracted horsetail powder from pharmaceutical companies.
Silicon Dioxide in Supplements
1. A food additive
Silicon dioxide is added to powdered foods and other health food supplements to keep other ingredients from binding together. For example, manufacturers add silicon dioxide to salt and many spices to keep those dry substances from clumping.
2. Health benefits
Silicon dioxide is critical for the development of strong nail, bones, teeth and hair. Research indicates that a lack of this mineral may lead to arthritis, poor bone formation, unhealthy skin and poor tooth development. Silicon dioxide also counteracts the effects of aluminum in the body, which may help prevent Alzheimer's disease.
3. Health concerns
Because silicon dioxide is a crystal, it can be an eye irritant if direct exposure occurs. When eyes are exposed to this mineral, the result will be red and watery eyes. If skin is directly exposed to silicon dioxide, the skin may become irritated and itchy. If silicon dioxide is inhaled over time such as can happen with miners, lung damage and potentially lung cancer may result.
4. Food safety
When used in food, the proportion of silicon dioxide to food must be strictly controlled. The mineral should be no more than 2 percent of the total weight of the food. It is also critical that the particle size of silicon dioxide be within limits defined by the Food and Drug Administration.
Other Silicon Dioxide Uses
In addition to its use in food, there are also manufacturing uses for silicon dioxide. These include:
Silicon dioxide has an extremely high melting point so is useful in electronics where high heat is produced. The mineral is essential for manufacturing fiber optic cables, semi-conductors, and insulation for wires.
2. Conversion of energy
Silicon dioxide has piezoelectric properties. These properties allow the mineral to convert one form of energy to another. For example, silicon dioxide allows mechanical energy to be converted to electrical energy. This conversion of energy enables television and radio stations to transmit signals.
Silica is one of the primary components of glass. Mixed with soda and boron oxide, silicon dioxide creates glass that is highly heat resistant. Thus, in addition to other glass products, silicon dioxide is critical in the creation of heat resistant cooking utensils.
Silicon dioxide is critical in the production of cement. Cement is added to other ingredients to make concrete -- the building block of much of the world's infrastructure.
5. Refractory materials
Finally, silicon dioxide is critical for production of refractory materials. These materials used in building and other areas are highly shock resistant.