Based on the strength of a substance's ability to gain electrons, it can be classified into strong oxidants, moderate oxidants, and weak oxidants to roughly describe its performance in redox reactions. However, the boundary of this classification is vague. Sometimes, the boundary is based on oxygen (O2/H2O, E∅=1.229V [2]) and iron ions (Fe3+/Fe2+, E∅=0.771V [2]). Species with oxidizing power exceeding that of oxygen are strong oxidants, those weaker than those of iron ions are weak oxidants, and those in between are moderate oxidants. According to their degree of danger, they are divided into primary oxidants and secondary oxidants.
Oxidants are classified into inorganic oxidants and organic oxidants according to their chemical composition. They can also be classified into the following three categories according to the medium required for the oxidation reaction:
(1) Acidic medium oxidants (e.g., hydrogen peroxide, peracetic acid, sodium dichromate, chromic acid, nitric acid, potassium permanganate, ammonium persulfate).
(2) Oxidizing agents in alkaline media (e.g., sodium hypochlorite, sodium percarbonate, sodium perborate, potassium perborate).
(3) Oxidizing agents in neutral media (e.g., bromine, iodine).
