Fenton’s reagent is a substance that contains hydrogen peroxide and iron. The mixture is highly reactive. It is added to polluted waters, in which it reacts with toxins to transform them into harmless compounds or compounds that can be removed from the water. This allows people to reuse the water instead of forcing it into storage until the toxins break down. The reagent is commonly used to remove chemical waste, such as phenols, from water.
Hydrogen peroxide molecules consist of two oxygen atoms and two hydrogen atoms. In solution, the molecules create hydroxide ions, which have one hydrogen and one oxygen atom. Hydroxide reacts easily with other molecules. When iron is added to a hydrogen peroxide solution, it facilitates the breakup of hydrogen peroxide into hydroxide, making the solution even more reactive. The solution of hydrogen peroxide is said to be catalyzed by the iron, and the combination is called Fenton’s reagent.
H. J. H. Fenton, who gave his name to Fenton’s reagent, discovered the potential of the mixture in 1894. At that time, however, the community of chemists did not understand why the solution acted the way that it did. Decades later, other scientists identified the process by which the solution cleaned water. After that discovery in the 1930s, factories began to use the reagent to clean industrial waste.
The solution is capable of removing a variety of wastes from water, including several common industrial by-products. For example, it can break down phenols and other toxic organic substances. It raises the quality of waste water, as measured by biochemical oxygen demand and chemical oxygen demand. The reagent also improves the aesthetic qualities of water, removing discoloration and odors caused by pollutants.
The mechanism by which Fenton’s reagent works is a general one, which means that the treatment may apply to a wide range of toxins and pollutants. This also means that the reagent does not discriminate between molecules dissolved in the waste water. The hydroxide ions may react with molecules that the people treating the water did not intend to change. Use of the reagent requires careful analysis to avoid accidental reactions.
In some cases, targeted treatment additives may be a better choice than Fenton’s reagent. It does, however, have distinct advantages. It works quickly compared to other solutions. The reagent also leaves little behind: unreacted hydrogen peroxide breaks down into oxygen and water, so the treatment does not cause further problems in the water supply.