FREQUENTLY ASKED QUESTIONS

ISOTEC Modified Fenton's Process

Is the modified Fenton's process patented or otherwise unique; what is the difference between ISOTEC and other vendors that provide similar services?

ISOTEC modified Fenton's Process is a patented remediation technology covered by U.S. Patents 6,319,328; 4,591,443 and 5,741,427. Additional patents are currently pending. Although based upon the fundamental principles of Fenton's chemistry, our technology vastly differs from conventional Fenton-based chemical oxidation technologies. Some of the major differences are outlined as below.

Circum-neutral pH Conditions: Conventional Fenton-based processes function only under acidic conditions because of the inability of iron catalyst to remain dissolved in the natural subsurface pH range of 6-7. ISOTEC's modified Fenton's process utilizes specially developed catalysts composed of active components that chelate the iron and keep it in dissolved form as an organometallic complex that functions effectively in the circum-neutral pH range (i.e. pH @ 7.0) for contaminant destruction.

Mobility Characteristics: One of the biggest challenges of in-situ oxidation is to ensure that the injected reagents travel to the location of contamination without being subjected to losses caused by precipitation or surface fixation. Iron, which is the key component required to promote Fenton's reaction, will precipitate within inches from the point of injection when introduced as solution of any of its typical salts. For example, a ferrous sulfate catalyst tends to precipitate to its oxidized form (Ferric), thereby, making hydroxyl radical generation magnitudes slower. Typically, 95% to 97% of a ferrous sulfate catalyst gets sorbed to the soil allowing only the remaining 3% to 5% of the catalyst to be utilized for hydroxyl radical generation. Acidified iron solution will remain in solution longer than regular iron solution; however, the low pH is quickly buffered by the native soil to its natural circum-neutral pH resulting in iron precipitation. Furthermore, acidification of the entire contaminated aquifer is not only impractical but may also result in permanently increasing the corrosivity of groundwater. ISOTEC's catalysts have superior mobility compared to conventional Fenton's catalysts and as discussed in (1), they function under natural subsurface conditions. The chelating components prevent precipitation or fixation of iron to native soil, thereby promoting its availability for hydroxyl radical generation from peroxide.

Control Agents: ISOTEC also developed stabilizers and mobility control agents that control the formation and dispersion of hydroxyl radicals. ISOTEC's stabilizers significantly enhance the longevity of peroxide when introduced into the subsurface.

Research: ISOTEC developed its reagents through years of research - both in-house as well as through affiliated academic institutions. The injection technology has been fine-tuned through years of laboratory and field experimentation. ISOTEC's reagents are especially designed for in-situ application. ISOTEC performs a field pilot program based on the results of laboratory testing conducted on site-specific samples. Laboratory bench tests are conducted in an effort to determine the stoichiometric molar ratio of ISOTEC reagents best suited to achieve maximum contaminant destruction at the subject site.

What is your experience with the production of interim daughter products and their toxicity?

ISOTEC has not experienced the production of any toxic interim daughter products at sites utilizing their modified Fenton's process. The ISOTEC modified Fenton's process is a chemical oxidation technology that destroys organic compounds in the subsurface. Upon injection of the reagents, hydroxyl radicals are generated. The modified Fenton's process is non-specific; meaning that when a free radical is formed, it will oxidize any oxidizable organic compound it comes in contact with, producing carbon dioxide and water, and chloride ions if chlorinated compounds are being treated. After a short period of time, the catalyst is oxidized to simple ferrous/ferric ions, which adsorb to the soil matrix.

What are the effects of in-situ pretreatment pH and temperature on your process, including reaction kinetics?

Lab studies and corresponding field treatment programs can be performed at sites with varying subsurface conditions such as acidic pH levels to alkaline levels. ISOTEC's patented catalysts allow for the generation of hydroxyl radicals and chemical oxidation to occur throughout the pH range of 2-10. ISOTEC's 4000 series modified Fenton's catalysts are designed to function under natural subsurface conditions (i.e. pH of 7). Therefore, no acidification of the subsurface is required. Temperature increases of up to 10 degrees Celsius may be noted during treatment programs for a short time period (<24 hours).

Our typical project approach starts in the laboratory where we develop a strategy to ensure that the ISOTEC Process is optimized for your specific site conditions.  A laboratory treatability study is conducted to test several types and concentrations of our patented catalysts and oxidizers on saturated soil and groundwater samples obtained from a site.  Following the treatability study, a field pilot program is designed to evaluate not only the efficiency of our reagents, but also the distribution of the reagents within the impacted media.  The data generated during the pilot program is used to design the most effective full-scale remediation program for your site.  At some sites, appropriate geology and contaminant types allow ISOTEC to mobilize directly to the field and begin full-scale remediation.

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