Sodium Silicates also known as soluble glass, are inorganic substances composed primarily of silicon oxide (SiO2) and sodium oxide (Na2O).
These compounds are produced by the fusion of sodium carbonate and silicon dioxide (high purity silica sand):
Na2CO3 + nSiO2 → Na2O n(SiO2) + CO2
The generic form of sodium silicates can be represented as Na2O nSiO2 xH2O, based on this formula may have different compositions or relationships ranging from 1.6 SiO2 : 1 Na2O hasta 3.3 SiO2 : 1 Na2O, which are those that can be managed satisfactorily within allowable ranges of solubility of silicates.
For marketing the Sodium Silicate is presented as an aqueous solution, ready for delivery to the customer in pipes, containers, drums and jugs.
Sodium Silicates have various industrial uses, because its components (sodium oxide and silicon oxide) act together, which is not present most of the alkalies.
– Laundry Soap.
Is recommend the use of Sodium Silicates S-41 and S-42. .
Sodium Silicates have displaced resins such as colophony, rosin, etc., in soap manufacturing. The above situation arose in the beginning by the scarcity and high cost of saponified resins. Subsequently the use of silicates was widespread, because the researchers found several advantages attributable to silicate in the new formulations.
Among the main advantages we find:
a) Avoiding free fats that produce the “rancid” of soap in storage.
b) Encourage the formation of foam that is abundant and persistent.
c) Check the solubility to prevent the soap to be consumed quickly.
d) Regulate the potential of hydrogen (pH) to not damage the skin and mantain it during the washing operation (acts as a buffer).
e) Reacting with the Ca2+ and Mg2+ ions contained in the water called “hard”, which allows the soap to be used efficiently in the washing process.
Is recommended the use of sodium silicate S-2.35.
In detergents, sodium silicate has an active participation in their properties, among which we mention:
a) Inhibiting Corrosion.- Sodium silicate forms a protective layer on the surface of metal that helps prevent corrosion of metals.
b) Increase the wetting.- One of the first steps in the washing process is the moisture, sodium silicate lowers the surface tension, which favors this process.
c) Emulsification.- The silicates help the dispersion of fat stains (usually acid), suspended in the wash solution and prevent its re-deposition.
d) Defloculation.- Favors the breaking of spots of inorganic particles (dirt, sand, etc.) disperses in the water preventing its reunification.
e) Saponification.- Acts in the process of breaking down fat molecules to form a soluble soap.
f) Alkalinity.- Sodium oxide increases alkalinity in the wash process.
g) Damping.- It has a dampening effect (Buffer) that maintains a high pH in the presence of acid soil.
h) Power and conditioner sequestering.- The Silicates react with the Ca2+ and Mg2+ ions contained in the water, allowing the generation of compounds that are removed in the rinse, removing the minerals and therefore the hardness of water.
Is recommend the use of Sodium Silicates S-41 and S-42.
Sodium Silicates possess characteristics that make it work themselves as adhesives, among which include:
a) Wet surfaces:
Silicate based adhesives quickly wet glass, ceramic surfaces, asbestos, cellulose fiber, synthetic wool, hair, nylon, wood resin and most minerals like: steel, aluminum, zinc, lead and some other metal surfaces.
b) Increased viscosity:
The second step in the actions of silicate based adhesives is the transformation of liquid to a solid that is commonly favored by moisture loss in the order of 5% of the weight of the adhesive. The speed of water removal depends primarily on the silicate ratio, alkaline solutions are dried more slowly, therefore the appropriate solutions for this application are the ones with higher silica content.
c) Adhesion Force (Union):
The third important factor in the use of silicates as adhesives is the bond strength that is present when they are applied, as they provide binding forces of about 1000 psi, which is sufficient to support or join materials of fragile nature.
Sometimes they add substances such as dextrin, starch and casein to sodium silicate solutions in order to improve their property as adhesives. The first two provide flexibility only to the glue, while the Casein provides mechanical strength.
Products that are manufactured with adhesives based on sodium silicate:
- Corrugated cardboard.
- Fiber board.
- Spiral tubes.
- Lamination of foil, tin.
- Insulating walls construction.
– Refractory mortars.
Is recommend the use of sodium silicate C-42.
The use of Sodium Silicate in this branch of industry is due to complete dehydration of the silicate solutions occurs at high temperatures, generally in the range of 1000-1100 ° C. Researchers have found an important application in the repair and protection of refractory surfaces, which are covered with a mixture consisting of sodium silicate and clay in thin layers.
a) Facilitate the formation of strong unions when dried.
b) They resist high temperatures.
c) They have resistance to acids except hydrofluoric acid.
d) They have resistance to dissolution, even if a dehydration.
e) They are easy to implement.
Is recommend the use of sodium silicate S-42.
Application of Sodium Silicate in the textile industry focuses primarily on bleaching operation.
The peroxide bleaching is best carried out in an alkaline bath in which oxygen is released, which is what gives the effect of bleaching. When silica is present in colloidal form the bath is even more effective, beacuse it stabilize and reduce the breakdown or loss of oxygen. Also Silicates preserve and stabilize the solid compounds of bleach, which decompose in water to form hydrogen peroxide, these substances are generally perborates percarbonates, persulfates and peroxides of alkali metals.
Research has shown that the addition of silicate in peroxide baths leads to more stable and durable, therefore using less reagents.
The peroxide baths that are nuetralized with silicate are capable of bleaching wool, silk, cotton and rayon fabrics or blends of that use these fibers.
The sodium silicate has effects that act directly on the bleach and can act as a detergent in conjunction with caustic soda.
It is considered that the protective action of silicates is due to its quality to maintain deflocculated ferric hydroxide and with this doesn’t allow to exercise its local action, this situation is important since sometimes is used iron oxide as catalyst for the peroxide hydrogen action.
Moreover Sodium Silicate addition contributes to the penetration and wetting of the fibers, helping to remove impurities that may be present.
– Water Treatment.
For this application is recommended the use of sodium silicate S-41.
Sodium silicate forms a protective layer on the surface of the metal to prevent corrosion, so it can be used as corrosion inhibiting agent, both in the drinking water distribution systems and in the industrial water.
The sodium silicate can be used as sequestering agent of iron and manganese, present in source water, which prevents the coloration caused by the oxidation of these elements.
– Paints and Pigments.
The sodium silicates generally used in such applications are the ones with highest ratios of type S-41 or S-42.
Metallic paints: They are paintings with a sodium silicate vehicle-based and metallic pigments, are useful for painting or coating surfaces that are to receive or handle heat.
When mixing the sodium silicate and aluminum powders, you can achieve a paint or coating for oven doors, hot stoves and other appliances where heat conservation is an objective and where a paint containing organic material will burn out quickly.
Sodium Silicates are also used as vehicles for paints that are applied to plaster walls and concrete floors or walls as they form insoluble layers, the application is durable indoor and outdoor, dry at room temperature with a matte finish, no difficulties in implementing it, is not toxic and does not give off odors.
The amount that can be added varies depending on the resistance that has the pigments to the alkaline compounds. The mixture of pigments, usually metal oxides, is done before adding silicate in a proportion ranging from 7-10% depending on the type of formulation.
The metal surfaces are more protected from corrosion if used silicate-based paints to which they are added or zinc or lead.
For greater strength and stiffness, sometimes rubber latex can be added at a rate of 10% for applications in pipes or equipment in which protection is required.
– Paper Deinking.
For this application is recommended the use of sodium silicate S-41 or Pentasil.
Sodium Silicates are used to remove the ink without causing damage to the fibers of the paper.
– Foundry industry.
Is recommended the use of sodium silicate M-50, S-2.35 and FAE-51.
The silicate is used as a binder in the manufacture of molds for casting metal parts, ferrous and nonferrous metals. The molds produced with properties suitable hardness and porosity, which allows a proper release of gases. It should be noted that to achieve faster hardening CO2 can be applied..
– Petroleum industry.
Is recommended the use of sodium silicate S-2.0 and S-2.35.
The sodium silicate is used as an additive in water based drilling fluids. It helps to achieve fluidity in providing drilling mud management.