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The patented Cool-Ox™ process is an in-situ (and ex-situ) remediation technology that combines controlled chemical oxidation with accelerated biodegradation subsequent to the oxidation phase. The process is based upon using hydrogen peroxide as the generator of the oxidizing radicals. However, unlike the Fenton or Fenton-like processes that use liquid hydrogen peroxide, the Cool-Ox™ process generates hydrogen peroxide from solid peroxygens that are injected into the soil or groundwater in an aqueous suspension. Once in place, the peroxygens react with water to produce hydrogen peroxide. This reaction is widely understood.
In conventional Fenton or Fenton-like processes, the liquid hydrogen peroxide reacts with iron salts that are introduced to produce the oxidizing radicals. This reaction is largely uncontrollable and usually produces excessive amounts of heat. Even where the iron is introduced in a separate injection sequence, the reaction can be robust. Similarly, other processes that have begun using solid peroxygens with introduced iron salts find it difficult to avoid volatilization of contaminants because of the heat produced. The Cool-Ox™ process has eliminated these problems.
The distinguishing feature of the Cool-Ox™ technology is that it does not require the injection of metal catalysts to activate the production of oxidizing radicals in the substrata; thus, the creation of heat is eliminated. Therefore, a very important characteristic of the Cool-Ox™ technology is that the chemical reaction is controllable.
Because most peroxygens are only sparingly soluble in aqueous solutions, their dissolution rate is quite slow. Therefore, once injected they remain in the contaminated media for an extended period of time before they become soluble. This low solubility characteristic also allows peroxygens to be hydraulically distributed by the injection equipment thereby, increasing the radius of influence from the injection point. This significantly increases the probability of the oxidizer contacting the contaminants. However, the greatest distinguishing feature of the Cool-Ox™ process is that it does not require the introduction of iron salts to produce the radicals necessary for chemical oxidation. Therefore, the reagents are iron free.
The Cool-Ox™ formulations include compounds that activate the catalytic metals that are intrinsic in the soil matrix being treated and eliminates the need to artificially introduce iron salts either into the oxidizing reagent or by sequential injections. The use of these reagents also imposes a second control factor (the first is the low solubility of the peroxygens) on the reaction rates of the oxidizers. Knowing how to manipulate these factors allows the oxidation reactions to proceed without producing heat. Therefore, the probability of volatilizing contaminants because of heat generation is eliminated when the Cool-Ox™ process is employed. This increased control eliminates the risk associated with other exothermic oxidizing processes, and as an added plus, there are no hazardous metals such as lead, chrome, or arsenic in the Cool-Ox™ formulations.
An additional and extremely important characteristic of the Cool-Ox™ process is the pH at which the oxidation reactions proceed. Unlike the Fenton or Fenton-like reactions that require a low acidic pH, the optimum pH of the Cool-Ox™ process is slightly basic at pH 8. This is critical when treating contaminants found in limestone or soils containing high concentrations of carbonates where a low pH would be buffered toward neutrality. Equally important is the factor that almost all phenolic, chloro-phenolic, and chlorinated organic compounds exhibit organic acid characteristics. In general, these compounds become increasing soluble in aqueous solutions as the pH is increased. Once soluble, they are quite susceptible to oxidation via the Cool-Ox™ process. Thus, a broad family of troublesome recalcitrant compounds such as creosotes, PCP, PCBs, PAHs, fuel hydrocarbons, dioxins as well as a host of herbicides and pesticides are treatable using the Cool-Ox™ process. Unlike permanganates, where the oxidation reaction is inhibited by hydrocarbons, the Cool-Ox™ process can concurrently remediate mixed plumes consisting of halogenated and hydrocarbon constituents.
The Cool-Ox™ process has been demonstrated to be very effective at treating contaminants on limestone bedrock and in high carbonate clay strata with no indication of a reaction with either material mainly because of the basic nature of the process and because the oxidation reaction is controlled. Therefore, it is not expected that the Cool-Ox™ process would impact slurry walls, either from chemical reactions or hydraulic pressure standpoints.
Because the reaction does not create heat, the volatilization of the VOCs is eliminated. This is an extremely important safety factor when dealing with compounds having low toxicity thresholds and/or the potential for flammability. The technology is enjoying success at treating excavations where contaminants such as aromatics or PAHs create significant odor problems. Unlike conventional deodorants that simply mask or isolate the contaminants, the Cool-Ox™process oxidizes the molecule thereby, converting it to an alcohol or polyol. These reaction products are converted to wetting agents and exhibit surfactant characteristics by forming a thick lather resembling shaving cream as shown in the Pit-Stop™ photos. Thus, the odor bodies are actually converted to odor control agents.
Another important feature is that the Cool-Ox™ reaction is self initiating. That is, the reaction starts when the oxidizer contacts organic contaminants. This characteristic precludes the need to catalytically “start” the reaction as is the case with persulfates.
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