Potassium Hydroxide

Definition - What does Potassium Hydroxide mean?

Potassium hydroxide is a strong inorganic alkaline compound with the chemical formula KOH. It is a noncombustible, hydrophilic substance and therefore is highly corrosive to metal and tissue. It readily absorbs moisture from the atmosphere and forms a caustic solution that attacks aluminum and zinc.

Potassium hydroxide is used in chemical manufacturing, petroleum refining and cleaning formulations.

Potassium hydroxide is also known as caustic potash.

Corrosionpedia explains Potassium Hydroxide

Potassium hydroxide (KOH) is an inorganic substance that is alkaline and fully decomposes in water into the potassium ion (K+) and hydroxide ion (OH-). The decomposition in water generates heat and causes a vigorous sound and reaction.

Uses for potassium hydroxide include:

  • An intermediate in industrial manufacturing processes, such as manufacturing fertilizers, potassium carbonate or other potassium salts and organic chemicals
  • Manufacturing detergents and alkaline batteries
  • Manufacturing drain cleaning products, paint removers and degreasing agents
  • Removing organic acids and sulfur compounds in petroleum refineries.

Potassium hydroxide solutions corrode aluminum and its alloys due to the formation of hydrogen gas. This corrosion attack can be prevented by adding the corresponding potassium salts of the acids.

In corrosion behavior and safety requirements, potassium hydroxide is very similar to sodium hydroxide (NaOH). Though potassium hydroxide is slightly more aggressive, this generally relates to its higher boiling point and the increased likelihood of higher-temperature exposure. Nickel alloys are less sensitive to stress cracking in potassium hydroxide than in sodium hydroxide. Plastics and linings indicate the same levels of resistance for potassium hydroxide and sodium hydroxide except fiberglass-reinforced plastic, which shows lower resistance to potassium hydroxide regardless of the resin type used.

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