Hydrogen Peroxide (H2O2) alone is an oxidant, although the addition of a ferrous iron (Fe+2) salt as a catalyst dramatically increases the oxidative strength of hydrogen peroxide. This increase is due to the production of hydroxyl radicals (•OH).
The reaction of iron-catalyzed peroxide oxidation at pH of 2.5-3.5 is called a “Fenton’s reaction”, named after its founder, H.J.H. Fenton. Ferric ions (Fe+3) are produced (oxidized from Fe+2) during the reactions, which if kept in solution, can be reconverted back to Fe+2 to continue hydroxyl radical production and continued reactions with COCs. Fenton’s reaction was initially developed at low H2O2 concentrations. However in practice, higher concentrations of H2O2 solutions, ranging from 3 to 35% by weight, are utilized
- Hydrogen peroxide and Fenton’s reactions increase the dissolved oxygen concentrations of groundwater that will enhance biodegradation.
- The effective porosity may be reduced with the precipitation of Fe+3 in soil.
- Low pH can cause metals to be mobilized within the treatment zone.
- Reactions of strong peroxide solutions (> 10%) are exothermic, although if controlled, this heat can be used to enhance the desorption and dissolution of sorbed LNAPL.
- There is potential gas generation and volatilization of COCs.
Hydrogen Peroxide Enhancement involves the circulation of a dilute solution of hydrogen peroxide through the contaminated groundwater zone to increase the oxygen levels. Hydrogen peroxide decomposes rapidly to oxygen, significantly increasing existing oxygen levels in the saturated zone where hydrogen peroxide is introduced. For each part of hydrogen peroxide introduced into groundwater, one-half part of oxygen can be produced (EPA 2004).
Though hydrogen peroxide has the potential of providing some of the highest levels of available oxygen to contaminated groundwater (theoretically 10% hydrogen peroxide could provide 50,000 ppm of available oxygen), it is cytotoxic to microbes at concentrations greater than 100-200 ppm. H2O2 also decomposes quickly to oxygen, potentially within four hours (EPA 2004). This limits the extent to which hydrogen peroxide can be distributed in the subsurface before it is transformed. In addition, increased oxygen bubbles in the saturated zone can potentially reduce hydraulic permeability, which could prevent the distribution of oxygen and circulation of nutrients (ICSS 2006).
H2O2 is commercially available most commonly as a 34% and 50% solution in drums, totes, and tankers. Hepure can provide other concentrations to meet your project requirements in drums, totes, and tankers.