Potassium hydroxide, also known as lye, is a colourless inorganic liquid that acts as a strong base (alkali). Its chemical formula is KOH. KOH solution is also known as caustic potash or potash lye and has many different applications.
During the KOH liquid production process, chlorine and hydrogen are formed as co-products. This caustic potash as it’s known is the base that is used in the production of potassium carbonate, potassium phosphates, liquid fertilizers, and potassium soaps and detergents.
In the home it is consumed in personal care products such as liquid lotions, soaps and shampoos.
As a strong base, it reacts with grease and fats, making it a useful ingredient in drain and oven cleaners as well as in non-phosphate detergents.
Along with sodium hydroxide (NaOH), this solid is a prototypical strong base. It has many industrial and niche applications, most of which exploit its caustic nature and its reactivity toward acids.
Potassium hydroxide and sodium hydroxide are remarkably similar and can often be used in the same applications. In manufacturing soaps, are used in saponification, a process that converts fats into soap. Likewise, both compounds can be used to make biodiesel. However, despite their similarities, there are a few uses in which you cannot swap one for the other. For example, Potassium Hydroxide is used as an electrolyte in alkaline batteries and Sodium Hydroxide is used in water purification.
Of all the compounds in the hydroxide group, potassium hydroxide and sodium hydroxide are the most chemically similar. Their chemical reactions, physical appearance in solid and liquid form and behaviour are closely matched, which allows them to stand in for one another in a number of uses.
Their differences start at a molecular level. Potassium hydroxide is slightly smaller than sodium hydroxide which means it cuts through oil molecules faster than sodium hydroxide. This makes potassium hydroxide a great choice for soaps that need to remove caked-on oil. It also releases slightly less heat than sodium hydroxide when exposed to water.
The world consumes 700,000 to 800,000 tonnes of the compound every year.