K2SiO3

K2SiO3, commonly known as potassium metasilicate or potassium silicate, is an inorganic compound that dissolves readily in water to give highly alkaline solutions. It is widely sold as a solid or as an aqueous “water glass” solution and is used as a binder, adhesive, and source of soluble silica in various industrial and agricultural applications.

Industrial production typically involves reacting silica (SiO2) with a soluble potassium compound such as potassium carbonate (K2CO3) or potassium hydroxide (KOH) at high temperature. A representative reaction is K2CO3 + SiO2 → K2SiO3 + CO2. The solid product is usually obtained as K2SiO3 or as hydrates such as K2SiO3·nH2O, and the material can form stable solutions with high pH when dissolved in water. In solution, potassium silicate is a strong base, with solutions commonly exhibiting pH values around 12.

Properties of K2SiO3 include its whiteness, water solubility, and high alkalinity. It is hygroscopic in some forms and can form gels upon hydrolysis or exposure to CO2 and moisture. In aqueous form, it can react with acids, yielding silicic species and potassium salts. It is generally handled as a caustic substance, requiring appropriate protective equipment to avoid skin and eye contact.

Applications are diverse: in construction and manufacturing as a glassy binder and sealant, in wood and brick bonding, and as a durable binder in certain cements and refractory materials. In horticulture, it serves as a source of soluble silica to strengthen plant tissues. It is also used in some detergents and specialty coatings. Safety considerations include its caustic nature and potential irritation upon exposure.