Potassium Permanganate

Potassium Permanganate is an inorganic purplish-black crystalline salt that dissolves in water to give intensely pink or purple solutions. Almost all applications of potassium permanganate exploit its oxidizing properties.

Synonyms
Permanganate of potash, potassium manganesoylolate
Chemical Formula
KMnO4
CAS Number
7722-64-7

Characteristics

Molar Weight
158.03 g/mol
Melting Point
240°C (decomposes)
Density
2.7 g/cm³
Forms
Needles, Purple, Black

Uses and Applications

Key applications

  • Oxidising agent

Industries

General information about potassium permanganate

Potassium permanganate is the potassium salt of permanganic acid. It does not occur in nature and is only produced synthetically. The substance is used by industry as a strong oxidising agent.
Properties of potassium permanganate
Potassium permanganate is an odourless solid that forms dark purple crystals. It is moderately soluble in water and produces an intense purple solution even in low concentrations.
It is a strong oxidising agent that oxidises hydrochloric acid to chlorine gas, for example, and is therefore a laboratory method for producing chlorine. It also oxidises sulphites and sulphides to sulphates and alcohols to aldehydes, for example. It also decomposes organic substances.
Potassium permanganate has no melting point. It decomposes from 240 degrees Celsius to green potassium manganate, manganese dioxide, potassium oxide and oxygen and is therefore oxidising.
Due to its strong oxidising effect, potassium permanganate reacts with many reducing agents and flammable substances, sometimes violently, to the point of spontaneous combustion. If there is no spontaneous reaction, there is a risk of fire and explosion.
The substance is produced by oxidising manganese oxide to potassium permanganate.
Close up top view or Aerial view of Water Treatment tank, Water Treatment production for Purify Water, drinking water production, and distribution

Potassium permanganate in water treatment

Potassium permanganate oxidises dissolved metals, organic impurities and pathogenic microorganisms in water treatment. It improves water quality and ensures clean, clear water.
In drinking water treatment, for example, it is used to oxidise iron and manganese, which can then be precipitated as solids and filtered out. Potassium permanganate also oxidises organic substances that cause unpleasant odours and tastes in the water, such as algae decomposition products or hydrogen sulphide. It also helps to reduce organic discolouration (e.g. caused by humic acids).
Potassium permanganate also oxidises microorganisms such as bacteria and algae in the water and thus curbs their growth. It is used to combat biofilms in pipes and tanks that can impair water quality. The substance is also used to oxidise harmful substances such as phenols, cyanides or pesticides, neutralising their toxic effects.
It is also often used as a pre-treatment in combination with sand filters or other filter systems and ensures that oxidised substances can be more easily retained in the filter.

Potassium permanganate in agriculture

Potassium permanganate is used for disinfection in agriculture. It is used to clean agricultural soil, equipment, tools, seed containers and greenhouses. It kills pathogens such as bacteria, fungi and viruses.
Seeds are also disinfected with potassium permanganate before sowing to prevent the transmission of pathogens. It helps to kill mould and fungal spores on the surface of the seeds. Potassium permanganate is also used as a spray solution to combat fungal infections such as mildew on plants.
It is also used to extend the shelf life of harvested products. Potassium permanganate absorbs ethylene, a gas produced during the ripening of fruit, and thus slows down the ripening process. This is particularly useful when storing bananas, apples or tomatoes, for example.
Diluted KMnO₄ solutions are used to disinfect water pipes and drinking systems in animal husbandry. It is also used as an antiseptic solution for treating infections or wounds in farm animals.

Potassium permanganate in the pharmaceutical industry

In the pharmaceutical industry, potassium permanganate is used as an antiseptic in wound treatment and as a disinfectant.
It is used in the treatment of skin diseases such as eczema, dermatitis and fungal infections. The oxidising effect kills bacteria, fungi and other pathogens.
For chronic skin conditions such as psoriasis, potassium permanganate is used to soothe inflamed skin and reduce the risk of infection. Antiseptic potassium permanganate baths are also prescribed for extensive skin infections, such as chickenpox or ulcers.
Diluted solutions are used in foot baths to treat heavy sweating (hyperhidrosis). Potassium permanganate is also used in the pharmaceutical industry to synthesise certain medicines.

Other applications for potassium permanganate

Potassium permanganate also acts as an oxidising agent in organic chemistry. It is often used to oxidise alcohols into aldehydes, ketones or carboxylic acids. In industrial synthesis, it is used in the production of various chemical compounds, for example quinones. It is also used to synthesise manganese compounds such as manganese dioxide, which is used as a catalyst or in batteries.
In the textile and paper industry, potassium permanganate is used to oxidise dyes and impurities. It is also used to bleach fabrics and cellulose. In the plastics and metal industries, it is used for surface treatment, for example to promote the adhesion of adhesives.