Hydrogen Peroxide

Featured Visual: Representative visual for hydrogen peroxide used in ISCO applications.

Overview

Hydrogen peroxide (H2O2) alone is an oxidant, although the addition of a ferrous iron (Fe²⁺) salt as a catalyst dramatically increases the oxidative strength through the production of hydroxyl radicals (•OH). This iron-catalyzed peroxide oxidation at pH of 2.5–3.5 is called a “Fenton’s reaction.” In practice, higher concentrations of H2O2 solutions ranging from 3 to 35% by weight are utilized. Hydrogen peroxide and Fenton’s reactions also increase dissolved oxygen concentrations, enhancing biodegradation.

Fenton’s Chemistry

Ferric ions (Fe³⁺) produced during the reaction can be reconverted back to Fe²⁺ to continue hydroxyl radical production and sustained reactions with contaminants. The reactions of strong peroxide solutions (>10%) are exothermic — if controlled, this heat can enhance the desorption and dissolution of sorbed LNAPL.

Oxygen Enhancement

Hydrogen peroxide decomposes rapidly to oxygen, significantly increasing existing oxygen levels in the saturated zone. For each part of hydrogen peroxide introduced into groundwater, one-half part of oxygen can be produced. This enhanced oxygen supports aerobic biodegradation of petroleum hydrocarbons and other contaminants.