The Fenton reagent is a hydrogen peroxide solution and a ferrous ion solution. Generally, Fenton's reagent is a hydrogen peroxide solution of ferrous sulfate. The ferrous ion in this reagent serves as a catalyst and facilitates the formation of free radicals.Hydroxyl free radicals and hydroperoxyl free radicals are generated from the reactions between ferrous ions and ferric ions with hydrogen peroxide in Fenton's reaction. The pH influences Fe3+ ions' solubility, which is the limiting factor for the reaction of Fenton. The reaction rate of Fenton's reaction increases in acidic media because ferric ions are more soluble in acidic media. The reaction rate slows down under simple or alkaline media, leading to the formation of ferric hydroxide.