TECHNOLOGIES / CHEMICAL OXIDATION / MODIFIED FENTON’S REAGENT

CHEMICAL OXIDATION: MODIFIED FENTON’S REAGENT

Modified Fenton’s Reagent (MFR) is an advanced adaptation of Fenton’s chemistry, originally discovered by British chemist Henry J.H. Fenton in 1894. The reaction between hydrogen peroxide (H2O2) and an iron catalyst produces hydroxyl radicals (OH•), one of the most powerful oxidizing species for breaking down organic contaminants in water. To improve the practical application of this chemistry for in-situ chemical oxidation (ISCO), ISOTEC developed a proprietary chelated iron catalyst with peroxide stabilizers, allowing MFR to safely and efficiently degrade contaminants at neutral pH conditions. A U.S. patent was issued for ISOTEC’s MFR chemistry in November 2001 (Patent No. 6,319,328 B1). Although the patent has since lapsed in the US, MFR continues to remain a vital tool for remediation.

UNDERSTANDING THE PROCESS

Modified Fenton’s Reagent (MFR) enhances the principles of classic Fenton’s chemistry by modifying the way hydrogen peroxide is activated. This process works by:

  1. Generating Hydroxyl Radicals: The reaction between hydrogen peroxide and ISOTEC’s proprietary chelated iron catalyst initiates the formation of hydroxyl radicals (OH•), which are highly reactive and capable of breaking down a wide range of organic contaminants.
  2. Expanding Reactive Pathways: Unlike traditional Fenton’s chemistry, MFR operates at circum-neutral pH, allowing for controlled oxidation that generates both oxidative and reductive radical species. This dual mechanism enhances the desorption and degradation of many organic contaminants, including carbon tetrachloride and chloroform, which are typically recalcitrant to other oxidizing reagents, including traditional Fenton’s reagent.
  3. Enhancing Desorption & Biodegradation: The reaction products of MFR, including oxygen, improve aerobic biodegradation potential, while gas evolution from the peroxide injection helps mobilize sorbed contaminants in soil.

KEY ADVANTAGES OF MFR

  • Highly Reactive: Produces the most oxidizing radicals per volume of any ISCO treatment.
  • Neutral pH Application: Eliminates the need for acid addition, making large-scale applications more practical.
  • Enhanced Desorption: Superoxide radicals and oxygen release improve mobilization of sorbed contaminants.
  • Lower Oxidant Demand: More cost-effective for petroleum hydrocarbons compared to sodium persulfate.
  • Supports Combined Remedies: Works synergistically with activated persulfate and bioremediation for comprehensive treatment.
  • Safe & Controlled Application: Proprietary stabilizers allow optimized injection, minimizing vapor off-gassing and heat generation.

IDEAL APPLICATIONS FOR MFR

MFR is most applicable at sites characterized by:

  • Chlorinated solvents (PCE, TCE, DCE, VC)
  • Petroleum hydrocarbons (BTEX, MTBE, PAHs)
  • Persistent contaminants (carbon tetrachloride, pentachlorophenol)
  • Low permeability soils where oxidant mobility is a concern
  • Sites where neutral pH treatment is necessary to avoid aquifer acidification

ISOTEC has extensive experience designing and safely implementing MFR treatment strategies, customizing application methods to maximize performance based on your site-specific conditions.

WHY USE MODIFIED FENTON’S AGENT?


This video may have been posted over 15 years ago, but the reaction benefits of MFR are still clear to see. As the most reactive oxidant available for ISCO treatment, MFR generates more radical species per volume than any other reagent currently in the remediation industry. Our MFR process creates a more controlled reaction that lasts longer and improves subsurface distribution compared to hydrogen peroxide and conventional Fenton’s Reagent.

OXIDATION-REDUCTION MECHANISM IN MFR

The core reaction follows the classic Fenton’s process, where hydroxyl radicals (OH•) are produced through the reaction of hydrogen peroxide with ferrous iron (Fe2+):

 

H2O2 + Fe2+ → OH• + OH– + Fe3+

 

Where:

H2O2 = Hydrogen Peroxide      OH• = Hydroxyl Radicals

Fe2+= Ferrous Ion.                       OH- = Hydroxide Ion

Fe3+= Ferric Ion

 

Beyond hydroxyl radicals, MFR also produces secondary reactive species, including superoxide radicals (O2•–), perhydroxyl radicals (HO2•), and hydroperoxide anions (HO2–). These additional radicals facilitate both chemical oxidation and chemical reduction, enhancing MFR’s overall effectiveness. The nucleophilic properties of these reductants allow MFR to degrade contaminants that are resistant to oxidation alone, making it a powerful remediation tool. With the addition of stabilizers and chelated iron catalysts, MFR can also sustain controlled oxidant delivery without excessive heat generation and off-gassing, making it a safer and more efficient ISCO solution.

COMPARISON WITH OTHER PEROXIDE-BASED TECHNOLOGIES

See how our experienced engineers and scientists can design an effective approach that will safely and successfully remediate your contaminated site.

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