Ammonium persulfate (NH4)2S2O8 is a strong oxidizing agent. It is very soluble in cold water, a large fall of temperature accompanying solution. It is a radical initiator. It is used to etch copper on printed circuit boards as an alternative to ferric chloride solution.
Potassium persulfate (K2S2O8), also known as KPS, is a chemical compound.
Sodium persulfate (Na2S2O8) is a chemical compound. It is a strong oxidizer. It is a severe irritant of skin, eyes, and respiratory system. It is almost non-hygroscopic and has particularly good ability to be stored for long time. It is easy and safe to handle. It is not combustible, but releases oxygen easily and assists combustion of other materials.