SODIUM SILICATE
SODIUM SILICATE
Sodium silicate, commonly known as ‘water glass,’ is prominent due to its wide commercial and industrial applications, including its use as a fireproofing agent, in cement formulations, and as a binder in various industries.
Sodium silicate’s excellent water solubility makes it valuable in household chemicals, water treatment processes, and for fireproofing wood and fabrics.
The various grades of sodium silicate are characterized by their SiO₂ – ₂O weight ratio, which affects their application in different industrial processes such as adhesives, water treatment, and construction materials.
CAS Number: 6834-92-0
EC Number: 229-912-9
Molecular Formula: H2O3Si.2Na
Molecular weight: 122,063
Synonyms: SODIUM SILICATE, Sodium metasilicate, 6834-92-0, 1344-09-8, Waterglass, Sodium siliconate, Water glass, Disodium metasilicate, Sodium sesquisilicate, Sodium silicate glass, Sodium water glass, Britesil, Carsil, Dryseq, Sikalon, Silican, Soluble glass, Agrosil S, Agrosil LR, Portil A, Silica E, Silica K, Silica N, Silica R, Pyramid 1, Pyramid 8, Carsil (silicate), Britesil H 20, Britesil H 24, Silicic acid, sodium salt, Dupont 26, Metso pentabead 20, Metso 99, Metso beads 2048, Caswell No. 792, Sodium silicate (Na2SiO3), disodium oxosilanediolate, as Bond 1001, 49FG, L 96 (salt), Silicic acid (H2SiO3), disodium salt, Sodium metasilicate, anhydrous, Sodium metasilicate (Na2SiO3), HSDB 5028, EINECS 215-687-4, UNII-IJF18F77L3, DP 222, EPA Pesticide Chemical Code 072603, N 38, Q 70, CHEBI:60720, MFCD00003492, disodium;dioxido(oxo)silane, Silicic acid (H2SiO3), disodium salt, pentahydrate (8CI,9CI), Sodium metasilicate anhydrous, IJF18F77L3, EC 215-687-4, Crystamet, Orthosil, 052612U92L, Silicic acid (H2SiO3), sodium salt (1:2), Simet A, Sodium metasilicate, puriss., Metso beads, drymet, Disodium monosilicate, Metso 20, HK 30 (van), HSDB 753, EINECS 229-912-9, disodium oxosilanebis(olate), Silicic acid, disodium salt, Chemsilate, Ru Silicate, UNII-052612U92L, sodium meta-silicate, Sodium silicon oxide, STARSO, SUPERCERAC, XYPEX, For fly ash activator, N 38 (silicate), GM 10 (silicate), PORTIL AW, STIXSO RR, PORTIL K, PORTIL N, SIMET AP, EXPANTROL 4BW, Silicic acid (H2SiO3) , disodium salt, DAB VI, EXPANTROL 2, PQ N CLEAR, WATER GLASS 3, SIMET 5G, SILCO 4, BRITESIL C 20, BRITESIL C 24, CRYSTAL 79, SIMET GA 5, ANTEF C 2, ANTEF M 1, CRYSTAL 100N, CRYSTAL 120A, Epitope ID:158534, PYRAMID P 40, SILCO S 4, ZEOPOL 25, ZEOPOL 33, EC 229-912-9, SILICON SODIUM OXIDE, SODIUM BETA-SILICATE, NASIL 40, DU PONT 26, P 84 (SILICATE), CRYSTAL 0070, HK 30 (SILICATE), SILCHEM 2500, SP 20 (SILICATE), SP 33 (SILICATE), SP 70 (SILICATE), SP 90 (SILICATE), B-W, METSO 510, K 28 (BINDER), SS 3 (SALT), STABISOL 300/12, METSO 2048, SS 3, DTXSID7029669, DTXSID9029647, SODIUM METASILICATE [MI], SODIUM SILICATE (MART.), P 3 SAXIN 5502, GM 10, HK 30, SB 41, SODIUM METASILICATE [HSDB], SP 33, SP 70, SP 90, AMY37025, SS-C 200, HS 240, SODIUM METASILICATE [WHO-DD], AKOS024429002, s15025, Silicic acid (CH2SiO3), disodium salt, SILICON SODIUM OXIDE (SINA2O3), SODIUM SILICON OXIDE (NA2SIO3), 84992-49-4, L 96, NS00074479, Q425397, Sodium trisilicate, >=18% Na (as Na2O) basis, >=60% Si (as SiO2) basis, powder, Waterglass, Disodium metasilicate, Sodium siliconate, Sodium polysilicate, Water glass, Sodium sesquisilicate, Sodium silicate glass, Sodium silicate solution, Sodium water glass, Disodium silicat, Sodium metasilicate, anhydrous, 49FG, disodium oxosilanediolate, UNII-052612U92L
Sodium silicate with a wide range of applications in many branches of the chemical, processing and construction industries.
Sodium silicate is an ecological product, used e.g. for wood impregnation.
The color of Sodium silicate is iridescent with a gray shade or a clear liquid without smell.
Sodium silicate is characterized by many parameters such as molar concentration, molar ratio, density, sum of oxides and viscosity.
These parameters determine the quality of Sodium silicate and its applicability.
Sodium silicate has a very wide range of applications in the chemical industry, processing and construction.
Due to Sodium silicates good water solubility, Sodium silicate is used in the production of household chemicals, e.g. detergents, powders and washing up liquids.
In the water treatment process, to clean Sodium silicate of heavy metals, to soften to get rid of compounds that cause scale deposits.
Sodium silicate is also used for the preparation and impregnation of wood and fabrics to obtain a fireproof surface (wood impregnated with water glass does not support the burning process).
Another branch of industry in which water glass is used is the paper industry, used for whitening cellulose products and chipboard, and as a binder for various types of adhesive compounds, i.e. glues and putties.
In construction as an addition
to ement or mortar. Formulations based on water glasses are called ecological building materials.
Sodium silicate regulates the process of moisture absorption, strengthens concrete, increases the adhesion and resistance of plasters to weather conditions, i.e. low temperature and humidity.
In the steel industry, for the production of high quality foundry molds.
Sodium silicate is also used for the production of corrosion inhibitors and for the production of anti-dusting agents.
In the cosmetics industry for the production of pigments.
To stabilize soil and land, and even in the refinery industry to stabilize the structure of oil.
The anions are often poymeric.
These compounds are generally colorless transpaent solids or white powders, and soluble in water in various amounts.
Sodium silicate is also the technical and common name for a mixture of such compounds, chiefly the metasilicate, also called waterglass, water glass, or liquid glass.
The product has a wide variety of uses, including the formulation of cements, passive fire protection, textile and lumber processing, manufacture of refractory ceramics, as adhesives, and in the production of silica gel.
The commercial product, available in water solution or in solid form, is often greenish or blue owing to the presence of iron-containing impurities.
In industry, the various grades of sodium silicate are characterized by their SiO2:Na2O weight ratio (which can be converted to molar ratio by multiplication with 1.032).
The ratio can vary between 1:2 and 3.75:1.
Grades with ratio below 2.85:1 are termed alkaline.
Those with a higher SiO2:Na2O ratio are described as neutral.
Sodium silicate appears as a powdered or flaked solid substance.
Strong irritant to skin, eyes, and mucous membranes.
Concentrated aqueous solutions used as a glue.
Sodium silicate is an inorganic sodium salt having silicate as the counterion.
Sodium silicate contains a silicate ion.
The most well-known example is meta silicate and its formula is Na2SiO3.
Sodium silicate is known as water glass or liquid glass.
Silicates are widely used in the chemical and textile industry.
The most commonly used examples are sodium silicate and potassium silicate.
The purer ones of sodium silicate are colorless or white in color.
Sodium silicate is usually found colorless. However, commercially used derivatives may contain colors such as blue or green.
Sodium silicate is the most important of the soluble silicates. This material is often called “water glass” and is ordinarily supplied as a colorless, viscous water solution displaying little tack.
Positive pressure must be used to hold the substrates together. This material will withstand temperatures of up to 1100 °C.
The main applications of sodium silicate adhesives are in bonding paper and making corrugated boxboard, boxes, and cartons.
They are also used in wood bonding and in bonding metal sheets to various substrates; in bonding glass to glass, porcelain, leather, textiles, stoneware, and so on; bonding glass-fiber assemblies; optical glass applications; manufacture of shatter-proof glass; bonding insulation materials; refractory cements for tanks, boilers, ovens, furnaces; acid-proof cements; fabrication of foundry molds; briquettes; and abrasive polishing wheel cements.
Sodium silicate is a chemical compound of silicon dioxide (SiO2 from pure silver sand), disodiumoxide (Na2O) and water.
The great success of sodium silicate is explained by its versatile functionality.
Sodium silicate offers a highly interesting combination of properties, which can be adapted freely to meet your requirements, changing the ratio between its components.
We are at your complete service to assist you in selecting the most appropriate sodium silicate for your application.
Sodium Silicate Solutions are moderate to highly concentrated liquid solutions of sodium silicate for use in chemical synthesis, solution deposition and other applications.
Sodium silicate, commonly known as “waterglass”, is prominent due to wide commercial and industrial application.
Sodium silicate is often composed of an oxygen-silicon polymer backbone housing water in molecular matrix pores.
Sodium silicate products are manufactured as solids or thick liquids, depending on intended use.
For instance, waterglass functions as a sealant in metal components.
Lastly, although sodium silicate production is a mature industry, there is ongoing research for new applications given its heat conductive properties.
Sodium silicate, 2Na2OSiO2, is the simplest form of glass.
Sodium silicate is found as lumps of greenish glass soluble in steam under pressure, white powders of varying degrees of solubility, or liquids cloudy or clear.
Sodium silicate is noncombustible; however, when the powdered form is suspended in air, Sodium silicate could cause a dust explosion if an ignition source is present.
Breathing the dust may also cause health problems.
The glass form could also create a hazard to responders in an accident.
The primary uses are as catalysts, soaps, adhesives, water treatment, bleaching, waterproofing, and flame retardant.
The general formula of sodium silicate is Na2 (SiO2) nO.
The most well-known example is meta silicate and its formula is Na2SiO3.
Sodium silicate is known as water glass or liquid glass.
Silicates are widely used in the chemical and textile industry.
The most commonly used examples are sodium silicate and potassium silicate.
The purer ones of sodium silicate are colorless or white in color.
Sodium silicate is usually found colorless.
However, commercially used derivatives may contain colors such as blue or green.
Uses of Sodium Silicate:
Sodium silicate is used in catalysts, silica gels, detergents, bleaching paper and textiles, ore treatments, foundry molds, and drilling fluids.
Sodium silicate is also used to waterproof cement and as a fireproofing agent.
Sodium silicate is used as a starting material for zeolites and silica catalysts, as an adhesive and binder, corrosion inhibitor, penetrating sealant, in cements, drilling fluids, for fireproofing wood, paper, and fabric, as a detergent booster, in waste water treatment, and as shell coating to preserve eggs.
Sodium silicate is used as a flocculant to separate solid from liquid phases in aqueous suspensions.
Alkali metal silicates are used as starting materials for products like silicas and zeolites, in detergents and cleaners, and pulp and paper production
Sodium silicate is also used to a lesser extent in soil stabilization and sealing, adhesives and binders (construction materials, paperboard and cardboard, ceramic binders, refractories, welding rods, and foundry molds and cores), surface coatings (titanium dioxide production, paints for masonry and glass, and spray coatings for tunnel construction and mining), water/wastewater treatment, enhanced oil recovery, and textile processing (bleach and dye stabilizing).
Sodium silicate is used as an anticaking agent, drying agent, humectant, and processing aid for foods.
Sodium silicate is used as a starting material for zeolites and silica catalysts, as an adhesive and binder, corrosion inhibitor, penetrating sealant, in cements, drilling fluids, for fireproofing wood, paper, and fabric, as a detergent booster, in waste water treatment, and as shell coating to preserve eggs.
Sodium silicate is used in boiler compounds, cleaners (laundry, dairy, floor, and metal), bleaches, aluminum paint strippers, pesticides (insecticides, fungicides, and antimicrobials), for deinking paper, and washing carbonated drinking bottles; Generally recognized as safe (GRAS) when directly added to human food.
Exempted from the requirement of a tolerance when used as a surfactant, emulsifier, wetting agent, suspending agent, dispersing agent, or buffer.
Modifies water hardness in soaps and detergents.
Sodium silicate is also used as anti-corrosive agent in boiler water; Produced in anhydrous, pentahydrate, and nonahydrate forms.
Sodium silicate is an important glass industry chemical compound, due to the presence of silica and sodium oxide.
The liquid form of sodium silicate finds many applications such as iron deflocculant in wastewater treatment plants, glass manufacturing, fire protection, detergent auxiliaries, cement formulation, drilling fluids, textile processing, desiccant, production of silica gel and manufacture of refractory ceramics.
Sodium silicate solution is used as a paper cement in the production of cardboard.
Sodium silicate is used as a drilling fluid for the stabilization of borehole walls.
In the automotive industry, this chemical compound is used as a crack sealer and exhaust system joint for repairing resonators, tailpipes, mufflers and other components.
Sodium silicate is used for the preservation of eggs, when refrigeration is not available.
Sodium silicate flocculant is used to clarify beer and wine, through precipitation of colloidal particles.
Gels of sodium silicate are used as substrates for the growth of algae in aquaculture hatcheries.
Industry Uses:
Pigments
Surfactant (surface active agent)
Other
Absorbent
Intermediates
Dust suppressant
Intermediate
Surface active agents
Functional fluids (open systems)
Not Known or Reasonably Ascertainable
Paint additives and coating additives not described by other categories
Filler
Adhesives and sealant chemicals
Corrosion inhibitor
Processing aids, not otherwise listed
Binder
Processing aids, specific to petroleum production
Stabilizing agent
Corrosion inhibitors and anti-scaling agents
Cleaning agent
Other (specify)
Plasticizers
Consumer Uses:
Binder
Corrosion inhibitor
Thickening agent
Chelating agent
Other (specify)
Hardener
Adsorbent
Other
Processing aids not otherwise specified
Surfactant (surface active agent)
Adhesion/cohesion promoter
Surface active agents
Intermediate
Flame retardants
Filler
Paint additives and coating additives not described by other categories
Chemical reaction regulator
Surface modifier
Not Known or Reasonably Ascertainable
Adhesives and sealant chemicals
Other Uses of Sodium Silicate:
Adhesive:
The largest application of sodium silicate solutions is a cement for producing cardboard.
When used as a paper cement, the tendency is for the sodium silicate joint eventually to crack within a few years, at which point Sodium silicate no longer holds the paper surfaces cemented together.
Sodium silicate solutions can also be used as a spin-on adhesive layer to bond glass to glass
Sodium silicate glass-to-glass bonding has the advantage that Sodium silicate is a low temperature bonding technique, as opposed to fusion bonding.
Sodium silicate is also less processing intensive than glass-to-glass anodic bonding, which requires an intermediate layer such as SiN to act as a diffusion barrier for sodium ions.
Deposition of such a layer requires a low pressure chemical vapor deposition step.
A disadvantage of sodium silicate bonding, however, is that Sodium silicate is very difficult to eliminate air bubbles.
This is due in part because this bonding technique doesn’t require bonding in vacuum and Sodium silicate also doesn’t use field assistance like in anodic bonding.
Though this lack of field assistance can sometimes be beneficial, because field assistance can provide such high attraction between wafers as to bend a thinner wafer and collapse onto the nanofluidic cavity or MEMS elements.
Drilling fluids:
Sodium silicate is frequently used in drilling fluids to stabilize borehole walls and to avoid the collapse of bore walls.
Sodium silicate is particularly useful when drill holes pass through argillaceous formations containing swelling clay minerals such as smectite or montmorillonite.
Concrete and general masonry treatment:
Concrete treated with a sodium silicate solution helps to reduce porosity in most masonry products such as concrete, stucco, and plasters.
This effect aids in reducing water penetration, but has no known effect on reducing water vapor transmission and emission.
A chemical reaction occurs with the excess present in the concrete that permanently binds the silicates with the surface, making them far more durable and water repellent.
This treatment generally is applied only after the initial cure has taken place.
These coatings are known as silicate mineral paint.
An example of the reaction of sodium silicate with the calcium hydroxide found in concrete to form calcium silicate hydrate (or C-S-H) gel, the main product in hydrated Portland cement, follows.
Detergent auxiliaries:
Sodium silicate is used in detergent auxiliaries such as complex sodium disilicate and modified sodium disilicate.
The detergent granules gain their ruggedness from a coating of silicates.
Water treatment:
Sodium silicate is used as an alum coagulant and an iron flocculant in wastewater treatment plants.
Sodium silicate binds to colloidal molecules, creating larger aggregates that sink to the bottom of the water column.
The microscopic negatively charged particles suspended in water interact with sodium silicate.
Their electrical double layer collapses due to the increase of ionic strength caused by the addition of sodium silicate (doubly negatively charged anion accompanied by two sodium cations) and they subsequently aggregate.
This process is called coagulation.
Refractory use:
Sodium silicate is a useful binder of solids, such as vermiculite and perlite.
When blended with the aforementioned lightweight aggregates, Sodium silicate can be used to make hard, high-temperature insulation boards used for refractories, passive fire protection and high temperature insulations, such as moulded pipe insulation applications.
When mixed with finely divided mineral powders, such as vermiculite dust (which is common scrap from the exfoliation process), one can produce high temperature adhesives.
The intumescence disappears in the presence of finely divided mineral dust, whereby the waterglass becomes a mere matrix.
Sodium silicate is inexpensive and abundantly available, which makes its use popular in many refractory applications.
Sand casting:
Sodium silicate is used as a binder of the sand when doing sand casting of iron or steel.
Sodium silicate allows the rapid production of a strong mold, by passing CO2 through the mixture of sand and sodium silicate in the mold box, which hardens Sodium silicate almost instantly.
Dye auxiliary:
Sodium silicate solution is used as a fixative for hand dyeing with reactive dyes that require a high pH to react with the textile fiber.
After the dye is applied to a cellulose-based fabric, such as cotton or rayon, or onto silk, Sodium silicate is allowed to dry, after which the sodium silicate is painted on to the dyed fabric, covered with plastic to retain moisture, and left to react for an hour at room temperature.
Passive fire protection:
Expantrol proprietary sodium silicate suspended in about a 6.5-mm-thick layer of red rubber, type 3M FS195, inserted into a metal pipe, then heated, to demonstrate hard char intumescence, strong enough to shut a melting plastic pipe
Palusol-based intumescent plastic pipe device used for commercial firestopping
Sodium silicates are inherently intumescent.
They come in prill (solid beads) form, as well as the liquid, water glass.
The solid sheet form must be waterproofed to ensure long-term passive fire protection (PFP).
Standard, solid, bead-form sodium silicates have been used as aggregate within silicone rubber to manufacture plastic pipe firestop devices.
The silicone rubber was insufficient waterproofing to preserve the intumescing function and the products had to be recalled, which is problematic for firestops concealed behind drywall in buildings.
Pastes for caulking purposes are similarly unstable.
This, too, has resulted in recalls and even litigation.
Not unlike other intumescents, sodium silicate, both in bead form and in liquid form, are inherently endothermic, due to liquid water in the water glass and hydrates in the prill form.
The absence in the US of mandatory aging tests, whereby PFP systems are made to undergo system performance tests after the aging and humidity exposures, are at the root of the continued availability, in North America, of PFP products that can become inoperable within weeks of installation.
Indiscriminate use of sodium silicates without proper waterproofing measures are contributors to the problems and risk.
When sodium silicates are adequately protected, they function extremely well and reliably for long periods.
Evidence of this can be seen in the many DIBt approvals for plastic pipe firestop devices using Palusol (a product of BASF), which use waterproofed sodium silicate sheets.
Metal repair:
Sodium silicate is used, along with magnesium silicate, in muffler repair and fitting paste.
When dissolved in water, both sodium silicate and magnesium silicate form a thick paste that is easy to apply.
When the exhaust system of an internal combustion engine heats up to Sodium silicate’s operating temperature, the heat drives out all of the excess water from the paste.
The silicate compounds that are left over have glass-like properties, making a temporary, brittle repair.
Automotive repair:
Sodium silicate is also used currently as an exhaust system joint and crack sealer for repairing mufflers, resonators, tailpipes, and other exhaust components, with and without fiberglass reinforcing tapes.
In this application, the sodium silicate (60–70%) is typically mixed with kaolin (40-30%), an aluminium silicate mineral, to make the sodium silicate “glued” joint opaque.
The sodium silicate, however, is the high-temperature adhesive; the kaolin serves simply as a compatible high-temperature coloring agent.
Some of these repair compounds also contain glass fibres to enhance their gap-filling abilities and reduce brittleness.
Sodium silicate can be used to fill gaps within the head gasket.
Commonly used on aluminum alloy cylinder heads, which are sensitive to thermally induced surface deflection.
This can be caused by many things including head-bolt stretching, deficient coolant delivery, high cylinder head pressure, overheating, etc.
Sodium silicate is added to the system through the radiator, and allowed to circulate.
Sodium silicate is suspended in the coolant until it reaches the cylinder head.
Sodium silicate loses water molecules to form a glass seal with a remelt temperature above 810 °C (1,490 °F).
A sodium silicate repair can last two years or longer.
The repair occurs rapidly, and symptoms disappear instantly.
Contamination of engine oil is a serious possibility in situations in which a coolant-to-oil leak is present.
Sodium silicate (glass particulate) contamination of lubricants is detrimental to their function.
Sodium silicate solution is used to inexpensively, quickly, and permanently disable automobile engines.
Running an engine with about 2 liters of a sodium silicate solution instead of motor oil causes the solution to precipitate, catastrophically damaging the engine’s bearings and pistons within a few minutes.
In the United States, this procedure was used to comply with requirements of the Car Allowance Rebate System (CARS) program.
Safe construction:
A mixture of sodium silicate and sawdust has been used in between the double skin of certain safes.
This not only makes them more fire resistant, but also makes cutting them open with an oxyacetylene torch extremely difficult due to the smoke emitted.
Crystal gardens:
When crystals of a number of metallic salts are dropped into a solution of water glass, simple or branching stalagmites of coloured metal silicates are formed.
This phenomenon has been used by manufacturers of toys and chemistry sets to provide instructive enjoyment to many generations of children from the early 20th century until the present.
An early mention of crystals of metallic salts forming a “chemical garden” in sodium silicate is found in the 1946 Modern Mechanix magazine.
Metal salts used included the sulfates and/or chlorides of copper, cobalt, iron, nickel, and manganese.
Pottery:
Sodium silicate is used as a deflocculant in casting slips helping reduce viscosity and the need for large amounts of water to liquidize the clay body.
Sodium silicate is also used to create a crackle effect in pottery, usually wheel-thrown.
A vase or bottle is thrown on the wheel, fairly narrow and with thick walls.
Sodium silicate is brushed on a section of the piece.
After 5 minutes, the wall of the piece is stretched outward with a rib or hand.
The result is a wrinkled or cracked look.
Sodium silicate is also the main agent in “magic water”, which is used when joining clay pieces, especially if the moisture level of the two differs.
Sealing of leaking water-containing structures
Sodium silicate with additives was injected into the ground to harden it and thereby to prevent further leakage of highly radioactive water from the Fukushima Daiichi nuclear power plant in Japan in April, 2011.
The residual heat carried by the water used for cooling the damaged reactors accelerated the setting of the injected mixture.
Applications of Sodium Silicate:
Employed in preparation of NaZnSiO3OH, a novel chiral framework material which has potential application in ion exchange, adsorption and catalysis.
The industry range in which sodium silicate is used is quite wide.
The areas where sodium silicate is used are commonly used in the chemical industry, cement industry, textile industry and timber processing industry.
Sodium silicate is also frequently used in automobiles and refractory machines.
Sodium silicate is colorless and clear in physical properties.
Sodium silicate is known as water glass or sıvı cam liquid glass.
In addition, the classification status may change depending on the crystal structure.
Sodium silicate is mixed with water, it has a physical structure similar to syrup.
Some sodium silicates may not be readily soluble in water.
Some sodium silicates may not be readily soluble in water.
Pressure must be applied to facilitate mixing of such sodium silicates with water.
Sodium silicate is widely used in detergent production, ceramic and pottery making, fireproof paper production, wood industry, cement industry and clothing dyes in the textile industry.
Sodium silicate is used for the hardening of concrete
Sodium silicate is used as a rust solvent in cleaning materials.
Other Applications:
Detergents
Paper
Water treatment
construction materials
Production of silica gel
As an ink solvent
Ceramic production
Clothing dyes
In mining
Applications Area:
Soil hardening agent and sealant for preventing leakage
Raw material for precipitated silica (white carbon)
Hydrogen peroxide stabilizer for bleaching paper pulp; ink remover for used paper
Hardening agent for castings sand
Buillder for synthetic detergent and soap additives
Properties of Sodium Silicate:
Sodium silicates are colorless glassy or crystalline solids, or white powders.
Except for the most silicon-rich ones, they are readily soluble in water, producing alkaline solutions.
Sodium silicates are stable in neutral and alkaline solutions.
In acidic solutions, the silicate ions react with hydrogen ions to form silicic acids, which tend to decompose into hydrated silicon dioxide gel.
Heated to drive off the water, the result is a hard translucent substance called silica gel, widely used as a desiccant.
Sodium silicate can withstand temperatures up to 1100 °C.
Sodium silicate is a low cost multi-functional product.
Sodium silicate offers an interesting combination of properties such as alkalinity, hardness-binding capacity, protection against corrosion.
This results in many diversified industrial applications.
Soluble sodium silicates are wholly inorganic and once diluted have no significant environmental impact.
They form by contact with Ca, Mg, Al or Fe insoluble silicates that occur in abundance in nature.
When neutralized they recycle themselves to amorphous silica.
Physical properties of sodium silicate-based substances make them very attractive for commercial/industrial use.
Liquids and solids based on sodium silicate and produced by PQ Corporation have a density from 1.6g/cubic cm. to about 1.4 g/cubic cm.
Also note that the data tables contain information on the observed state of each product under moderate conditions.
Sodium silicate products exist as white solid and a variety of liquids with visibly different properties.
Differences in reaction conditions and manufacturing methods lead to clear, opaque, and “syrupy” waterglass products.
Sodium silicates are crystalline solids that have a glassy appearance.
The common terms for an aqueous solution of sodium silicate are water glass and liquid glass.
They produce alkaline solutions, since they are soluble in water.
Sodium silicate is soluble is stable in alkaline as well as neutral solutions.
However, acidic medium, the ions of silicate react with the ions of hydrogen to produce silicic acid, which has the tendency to decompose into hydrated silicon dioxide gel.
The final product obtained, after driving off the water is silica gel, which is a hard-translucent substance.
Sodium silicates are colorless glassy or crystalline solids, or white powders.
Except for the most silicon-rich ones, they are readily soluble in water, producing alkaline solutions.
When dried up Sodium silicate still can be rehydrated back in water.
Sodium silicates are stable in neutral and alkaline solutions.
In acidic solutions, the silicate ions react with hydrogen ions to form silicic acids, which tend to decompose into hydrated silicon dioxide gel.
Heated to drive off the water, the result is a hard translucent substance called silica gel, widely used as a desiccant.
Sodium silicate can withstand temperatures up to 1100 °C.
Characteristics of Sodium Silicate:
Exhibits alkaline properties as water glass, with viscosity changing markedly depending on the concentration.
When a slightly large amount of acid is added to water glass, sol or gel silica（SiO2）will be disposed.
Solubility of Sodium Silicate:
Aqueous solution of sodium silicate – water glass is mixed with water in every ratio.
The product is insoluble in most organic solvents.
Production of Sodium Silicate:
Solutions of sodium silicates can be produced by treating a mixture of silica (usually as quartz sand), caustic soda, and water, with hot steam in a reactor.
The overall reaction is
2x NaOH + SiO2 → (Na2O)x·SiO2 + x H2O
Sodium silicates can also be obtained by dissolving silica SiO
2 (whose melting point is 1713 °C) in molten sodium carbonate (that melts with decomposition at 851 °C):
x Na2CO3 + SiO2 → (Na2O)x·SiO2 + CO2
The material can be obtained also from sodium sulfate (melting point 884 °C) with carbon as a reducing agent:
2x Na2SO4 + C + 2 SiO2 → 2 (Na2O)x·SiO2 + 2 SO2 + CO2
In 1990, 4 million tons of alkali metal silicates were produced.
Ferrosilicon:
Sodium silicate may be produced as a part of hydrogen production by dissolving ferrosilicon in an aqueous sodium hydroxide (NaOH • H2O) solution:
2NaOH + Si + H2O → 2Na2SiO3 + 2H2
Bayer process:
Though unprofitable, Na2SiO3 is a byproduct of Bayer process which is often converted to calcium silicate (Ca2SiO4).
History of Sodium Silicate:
Soluble silicates of alkali metals (sodium or potassium) were observed by European alchemists already in the 1500s.
Giambattista della Porta observed in 1567 that tartari salis (cream of tartar, potassium hydrogen tartrate) caused powdered crystallum (quartz) to melt at a lower temperature.
Other possible early references to alkali silicates were made by Basil Valentine in 1520 and by Agricola in 1550.
Around 1640, Jean Baptist van Helmont reported the formation of alkali silicates as a soluble substance made by melting sand with excess alkali, and observed that the silica could be precipitated quantitatively by adding acid to the solution.
In 1646, Glauber made potassium silicate, which he called liquor silicum, by melting potassium carbonate (obtained by calcinating cream of tartar) and sand in a crucible, and keeping Sodium silicate molten until it ceased to bubble (due to the release of carbon dioxide).
The mixture was allowed to cool and then was ground to a fine powder.
When the powder was exposed to moist air, Sodium silicate gradually formed a viscous liquid, which Glauber called “Oleum oder Liquor Silicum, Arenæ, vel Crystallorum” (i.e., oil or solution of silica, sand or quartz crystal).
However, Sodium silicate was later claimed that the substances prepared by those alchemists were not waterglass as it is understood today.
That would have been prepared in 1818 by Johann Nepomuk von Fuchs, by treating silicic acid with an alkali; the result being soluble in water, “but not affected by atmospheric changes”.
The terms “water glass” and “soluble glass” were used by Leopold Wolff in 1846 by Émile Kopp in 1857 and by Hermann Krätzer in 1887.
In 1892, Rudolf Von Wagner distinguished soda, potash, double (soda and potash), and fixing (i.e., stabilizing) as types of water glass.
The fixing type was “a mixture of silica well saturated with potash water glass and a sodium silicate” used to stabilize inorganic water color pigments on cement work for outdoor signs and murals.
Handling and Storage of Sodium Silicate:
Handling:
Personal Protection:
Wear appropriate personal protective equipment (PPE) including gloves, safety goggles, and protective clothing to prevent skin and eye contact.
Ventilation:
Ensure adequate ventilation in areas where sodium silicate is used or stored to avoid inhaling vapors or dust.
Avoid:
Direct contact with acids and strong reducing agents, which can cause reactions.
Handling Procedures:
Use non-reactive containers and equipment.
Avoid creating dust or mist.
Storage:
Sodium silicate should be stored away from high temperatures and acidic materials.
In addition, Sodium silicate should be stored in dry and cool places not in direct contact with sunlight.
Containers:
Store in original containers or compatible, tightly sealed containers.
Conditions:
Keep in a cool, dry place.
Protect from moisture and direct sunlight.
Segregation:
Store away from acids, strong bases, and incompatible materials.
Ensure that storage areas are clearly labeled.
Stability and Reactivity of Sodium Silicate:
Stability:
Sodium silicate is generally stable under normal conditions of use and storage.
Decomposition:
Can decompose at high temperatures or in contact with acids, releasing silica and sodium salts.
Reactivity:
Incompatible Materials:
Reacts with acids, strong bases, and reducing agents.
Hazardous Reactions:
Produces heat and potentially hazardous gases when mixed with acids.
Conditions to Avoid:
Avoid exposure to moisture and acids.
Handle with care to prevent inadvertent reactions.
First Aid Measures of Sodium Silicate:
Inhalation:
Move to fresh air immediately.
If symptoms persist, seek medical attention.
Skin Contact:
Wash the affected area with plenty of water and soap.
Remove contaminated clothing.
Seek medical attention if irritation persists.
Eye Contact:
Rinse immediately with plenty of water for at least 15 minutes.
Remove contact lenses if present and easy to do. Seek medical attention immediately.
Ingestion:
Do not induce vomiting.
Rinse mouth with water and seek medical attention immediately.
Fire-Fighting Measures of Sodium Silicate:
Extinguishing Media:
Use water spray, foam, or dry chemical extinguishers.
Fire Fighting Procedures:
Wear self-contained breathing apparatus and protective clothing.
Sodium silicate itself is not flammable, but it can decompose and release harmful fumes when exposed to high heat or fire.
Fire and Explosion Hazards:
Hazardous Combustion Products:
May produce silica and sodium salts upon decomposition.
Explosion Hazard:
Sodium silicate does not pose an explosion hazard but can react with acids to release heat and gases.
Accidental Release Measures of Sodium Silicate:
Spill Response:
Personal Protection:
Wear appropriate PPE, including gloves, goggles, and protective clothing.
Containment:
Isolate the spill area.
Prevent spill from spreading by using barriers or absorbents.
Cleanup:
Collect material using non-reactive tools and place into appropriate waste containers.
Clean the area with water and detergent.
Disposal:
Dispose of in accordance with local regulations and guidelines.
Exposure Controls/Personal Protection of Sodium Silicate:
Exposure Limits:
Occupational Exposure Limits:
Check local regulations and guidelines for specific exposure limits.
Engineering Controls:
Ventilation:
Use adequate ventilation systems to minimize airborne concentrations.
Personal Protective Equipment (PPE):
Respiratory Protection:
Use an appropriate respirator if airborne concentrations are high.
Hand Protection:
Wear chemical-resistant gloves.
Eye Protection:
Wear safety goggles or face shield.
Skin Protection:
Use protective clothing and ensure to cover exposed skin.
Hygiene Practices:
General Hygiene:
Wash hands and face thoroughly after handling.
Avoid eating, drinking, or smoking in areas where sodium silicate is handled.
Identifiers of Sodium Silicate:
Chemical name: Silicic acid, sodium salt
CAS No: 1344-09-8
EC-No .: 215-687-4
CAS NUMBER: 1344-09-8
EC NUMBER: 215-687-4
MOLECULAR FORMULA: Na2O(SiO2)x · xH2O
Chemical Formula: Na₂SiO₃ (for the anhydrous form)
Molar Mass: Approximately 122.06 g/mol (for the anhydrous form)
IUPAC Name: Sodium metasilicate
Synonym(s): sodium metasilicate, waterglass, disodium metasilicate
Mol. Formula: H2O3Si.2Na
EC / List no.: 229-912-9
CAS no.: 6834-92-0
Molecular weight: 122,063
Properties of Sodium Silicate:
Quality Level: 100
grade: reagent grade
assay: 12.0-13.0% Si basis (gravimetric) 13.4-14.4% NaOH basis (titration by HCl, titration)
form: liquid
composition: Na2O, ~10.6% SiO2, ~26.5%
application(s): ion chromatography: suitable
density: 1.39 g/mL at 25 °C
Molar module: 3.2 ÷ 3.4
Oxide content (SiO2 + Na2O): not less than 35%
Density (20oC) g / cm3: 1.37 ÷ 1.40
Dynamic viscosity (P): not less than 1
Physical state: Liquid at 20oC and 101.3 kPa
Color: white, transparent or translucent
Odor: No characteristic odor
pH: 11-13 at 20oC
Solid Form: Usually found as a white or transparent, glassy solid.
Liquid Form: A clear, colorless to slightly cloudy liquid.
Solubility:
In Water: Highly soluble, forming an alkaline solution.
In Organic Solvents: Generally insoluble in organic solvents.
Density:
Solid: Approximately 2.4-2.6 g/cm³ (for the solid form).
Liquid: Varies depending on concentration but generally around 1.4-1.6 g/cm³.
Molecular Weight: 122.063 g/mol
Hydrogen Bond Donor Count: 0
Hydrogen Bond Acceptor Count: 3
Rotatable Bond Count: 0
Exact Mass: 121.94120896 g/mol
Monoisotopic Mass: 121.94120896 g/mol
Topological Polar Surface Area: 63.2Ų
Heavy Atom Count: 6
Complexity: 18.8
Isotope Atom Count: 0
Defined Atom Stereocenter Count: 0
Undefined Atom Stereocenter Count: 0
Defined Bond Stereocenter Count: 0
Undefined Bond Stereocenter Count: 0
Covalently-Bonded Unit Count: 3
Compound Is Canonicalized: Yes
Specifications of Sodium Silicate:
Silica (SiO₂): Typically 28-35% by weight.
Sodium Oxide (Na₂O): Typically 8-15% by weight.
Appearance: Clear, colorless to slightly cloudy liquid.
Density: Approximately 1.4-1.6 g/cm³ (varies with concentration).
pH (10% solution): Generally between 11-13.
Viscosity:
Typical Range: Can vary significantly depending on concentration, but often ranges from 1-10 cP (centipoise).
Solubility:
In Water: Fully soluble.
Boiling Point:
Varies: Typically does not have a defined boiling point due to decomposition; evaporates at high temperatures.
Sodium Silicate Solid (Anhydrous Form)
Chemical Composition:
Silica (SiO₂): Typically 60-70% by weight.
Sodium Oxide (Na₂O): Typically 30-40% by weight.
Appearance: White or transparent, glassy solid.
Density: Approximately 2.4-2.6 g/cm³.
Melting Point: Not well-defined; typically decomposes before melting.
Hardness:
Relative Hardness: Hard and brittle.
Solubility:
In Water: Soluble, forming an alkaline solution.
Solubility in Organic Solvents:
Typically: Insoluble.