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Chemical collection and stock control for UK schools, universities and hospitals

Potassium permanganate (CAS 7722-64-7): storage and disposal

Purple black crystals of potassium permanganate, and made up solutions such as 0.02 M, are held across schools, colleges, universities, histology rooms, pharmacies and veterinary practices. It is classified as an oxidiser that may intensify fire, harmful if swallowed, suspected of damaging the unborn child and damaging to organs through prolonged exposure, and very toxic to aquatic life. Organic material and acid on the shelf are the usual problems.

CAS number
7722-64-7
Form
Solid
Storage class
Oxidiser
Signal word
Danger
Usual EWC code
16 05 06*
  • Oxidising pictogramOxidising
  • Harmful or irritant pictogramHarmful or irritant
  • Serious health hazard pictogramSerious health hazard
  • Hazardous to the environment pictogramHazardous to the environment

What to do this week

  1. Check the label is readable and write down the opened date if it is not already there.
  2. Check it is stored as oxidiser stock and apart from the items listed under "Do not store with".
  3. If you no longer need it, add it to your disposal list so it goes on the next collection.

Safe storage in a school or lab

Ignition on contact is what decides where this goes. Permanganate ignites glycerol and other organic material when they meet, and it reacts violently with concentrated sulfuric acid, so a school prep room cupboard that also holds glycerol, ethanol or acid bottles is the wrong place. Use the oxidiser space on non-combustible shelving, well clear of flammable, acid, alkali, toxic and corrosive stock, and of ethers, activated charcoal and aluminium powder. Keep the crystals in a glass or plastic tub with a tight lid, and the 0.02 M solution in its own labelled bottle. Because of the unborn child warning, handling by pregnant staff should be avoided.

How to tell it has deteriorated

Normal crystals are dark purple and dry, and a fresh solution is a clear, deep purple. What does not look normal is brown. Old solutions form a brown deposit of manganese dioxide as they age, which clouds the liquid and coats the bottle wall, and brown stains around a cap or on a shelf show that crystals or liquid have escaped. Stains also mark skin, labels and worktops, so check them closely. A tub with caked crystals, a corroded cap or paper dust inside is worse, as organic contamination is the danger for an oxidiser. A bottle that has lost its label is recorded as it is found.

How it must be disposed of

By specialist collection only. It never goes down the drain or into general waste. It is normally packed in a oxidising laboratory pack with compatible chemicals.

The usual entry is waste code 16 05 06*, where the asterisk marks hazardous waste, and UN 1490 is the transport number. A pharmacy or histology unit in human healthcare may use 18 01 06*, and a veterinary practice 18 02 05*, so say which you are. Crystals and solution are described and packed separately, away from flammable, acid and organic stock, with nothing like glycerol or ethanol in the same box. It never goes down a sink or drain, into general waste or a skip, and staff should not try to treat it first. Note the stain level on the outside of the containers.

Waste codes and transport details for Potassium permanganate
EWC code, laboratory chemicals16 05 06*
Discarded inorganic chemical, not a laboratory pack16 05 07*
Human healthcare setting18 01 06*
Veterinary setting18 02 05*
Hazardous wasteYes

The code depends on where the waste came from and what it is mixed with. Use the waste code finder to see why.

Do not store with

  • FlammableOxidisers can ignite flammable materials or make a fire far more intense.
  • AcidMany oxidisers release toxic gas or become unstable in contact with acid.
  • AlkaliSome oxidisers react strongly with alkalis, and ammonia based stock is especially at risk.
  • ToxicToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
  • CorrosiveCorrosive stock can react with oxidisers, releasing heat or fumes.

Named chemicals to keep apart

  • 1,2-DimethoxyethanePeroxide forming ethers can ignite or explode with strong oxidisers.
  • 1,4-DioxanePeroxide forming ethers can ignite or explode with strong oxidisers.
  • Acetic anhydridePermanganate can ignite or explode with these materials.
  • Activated charcoalStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
  • Aluminium powderStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
  • Diethyl etherPeroxide forming ethers can ignite or explode with strong oxidisers.
  • Diisopropyl etherPeroxide forming ethers can ignite or explode with strong oxidisers.
  • EthanolPermanganate can ignite or explode with these materials.
Show 12 more
  • Ethidium bromideReaction with these oxidisers can produce unknown hazardous products.
  • FormalinFormaldehyde reacts with these materials. With hydrochloric acid it can form a potent carcinogen.
  • GlucoseStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
  • GlycerolPermanganate can ignite or explode with these materials.
  • Hydrogen peroxidePermanganate can ignite or explode with these materials.
  • Magnesium ribbonStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
  • Potassium cyanideCyanides react violently with strong oxidisers.
  • Red phosphorusStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
  • Sodium cyanideCyanides react violently with strong oxidisers.
  • SucroseStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
  • SulfurStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
  • Sulfuric acidPermanganate can ignite or explode with these materials.

Common quantities we collect

Usually held as: crystals, 0.02 M.

Part-used bottles and full containers are both fine. Tell us the size and how many, and an estimate is enough for a first price.

Where it is commonly held

Hazard statements

  • H272 May intensify fire; oxidiser.
  • H302 Harmful if swallowed.
  • H361d Suspected of damaging the unborn child.
  • H373 May cause damage to organs through prolonged or repeated exposure.
  • H410 Very toxic to aquatic life with long lasting effects.
Precautionary statements
  • P203 Obtain, read and follow all safety instructions before use.
  • P210 Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
  • P220 Keep away from clothing and other combustible materials.
  • P264 Wash hands and exposed skin thoroughly after handling.
  • P270 Do not eat, drink or smoke when using this product.
  • P273 Avoid release to the environment.
  • P280 Wear protective gloves, protective clothing, eye protection and face protection.
  • P301+P317 IF SWALLOWED: Get medical help.
  • P318 If exposed or concerned, get medical advice.
  • P330 Rinse mouth.
  • P370+P378 In case of fire: Use suitable extinguishing media to extinguish.
  • P391 Collect spillage.
  • P405 Store locked up.
  • P501 Dispose of contents and container in accordance with local, regional, national and international regulations.
  • P260 Do not breathe dust, fume, gas, mist, vapours or spray.
  • P264+P265 Wash hands and exposed skin thoroughly after handling. Do not touch eyes.
  • P301+P330+P331 IF SWALLOWED: Rinse mouth. Do NOT induce vomiting.
  • P302+P361+P354 IF ON SKIN: Take off immediately all contaminated clothing. Immediately rinse with water for several minutes.
  • P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing.
  • P305+P354+P338 IF IN EYES: Immediately rinse with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
  • P316 Get emergency medical help immediately.
  • P317 Get medical help.
  • P319 Get medical help if you feel unwell.
  • P321 Specific treatment (see supplemental first aid instruction on this label).
  • P363 Wash contaminated clothing before reuse.

Substance as classified, dilutions may differ.

Questions

Why is permanganate kept away from glycerol and ethanol?

It ignites glycerol and other organic material on contact, and ethanol is among the stock to keep apart. Store it in the oxidiser space, not in the same cupboard as organic liquids.

Our 0.02 M solution has a brown deposit. Is it still usable?

A brown deposit of manganese dioxide forms in solutions with age. It marks old stock, so record it as aged and list it for collection. Do not filter, top up or reuse it.

Which hazards does the classification cover?

Fire intensification as an oxidiser, harm if swallowed, suspected damage to the unborn child, organ damage after prolonged or repeated exposure, and very toxic effects on aquatic life with long lasting effects.

Can a vet practice dispose of old crystals as clinical waste?

No. It is a chemical waste and an oxidiser. It goes by specialist collection, not into clinical waste, general waste, a sink or a drain. Use the veterinary waste code where it applies.

Guidance only. Check your own risk assessment and your supplier's safety data sheet.

Hazard data source: PubChem GHS Classification, retrieved 31 Oct 2026. Formula KMnO4. EC number 231-760-3.

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