Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
2000-03-24
2002-08-20
Gupta, Yogendra N. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S421000, C106S634000
Reexamination Certificate
active
06436884
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a pollution remedial composition and a method of using the pollution remedial composition. More particularly, this invention relates to an improved composition for remediating polychlorinated biphenyls (“PCB”).
2. Description of the Prior Art
PCB pollutants comprise one of the most significant hazardous waste problems we face today. The PCB pollutants are man-made, can be found in soil and in water, and have relatively long half-lives. PCB compounds have been widely used as insulation in electrical equipment, such as transformers and capacitors. If an electrical equipment contains PCB compounds, the equipment, its support platform, and the soil under and around the area most likely will contain these pollutants. PCB compounds are, to a certain extent, fire resistant. When they are burned, however, some toxic dioxin is formed as a by-product of the combustion, along with phosgene and hydrochloric acid. PCB compounds biodegrade very slowly and their very low vapor pressure precludes their loss to the atmosphere. Thus, cleanup of PCB compounds is particularly expensive especially since incineration, the normal method of decontamination, is unacceptable.
U.S. Pat. No. 5,478,389 to Loomis discloses a pollution remediation composition. The composition disclosed by Loomis includes from 40 to 75 volume % of a soluble silicate (preferably sodium silicate), from about 0.25 to 5 volume % surfactant (preferably an ester of organo-phosphoric acid), from 1 to 5 volume % of a polyol (preferably ethylene glycol), and the remainder water. It has been found that the composition disclosed by Loomis, while capable of greatly reducing the level of PCB compounds, is not able to fully remediate a contaminated waste site to currently mandated levels of less than 10 ppb for residential use, less than 100 ppb for industrial use, and less than 2 ppm for soils.
Accordingly there is a need for an improved composition capable of reducing PCB levels to such approved levels.
SUMMARY OF THE INVENTION
A pollution remedial composition primarily for treating polychlorinated biphenyl compounds is disclosed. The pollution remedial composition includes from about 35 to about 40 volume % of an alkali metal, preferably a soluble silicate; from about 0.25 to about 2 volume % of a surfactant; from about 2 to about 5 volume % of a polyol; and the remainder water. The soluble silicate is preferably sodium silicate. The surfactant is preferably Tergitol brand surfactant, a NP-9.5 surfactant sold by Union Carbide. The polyol is preferably polyethylene glycol. The composition may include other constituents as necessary for added benefits.
The present composition is capable of destroying PCB compounds at ambient temperatures for soils and material surfaces (i.e., concrete or brick). The composition is used in an alkali metal catalyzed dechlorination method. Dechlorination of PCB compounds is completed through a series of chemical reactions; ultimately through a reduction reaction. Chlorinated hydrocarbon-contaminated soils can be dehalogenated by dispersion and catalysts. The presence of a catalyst allows the reduction reactions to proceed at low temperature. Critical factors are surface area, moisture content and pH. In the case of contaminated soil, the catalysts, dispersant, buffering agent, and reductive chemical must enter the intractable matrices (blind pore spaces) simultaneously, thus, maximizing surface area and pH, resulting in complete reduction of the chlorinated compound(s). Because this reduction reaction proceeds at ambient temperature, complex dehalogenation may require an extended period of time up to 24 hours.
The initial chlorinated hydrocarbon concentrations in the soils and the degree of dechlorination desired determine the quantity and composition of the reagents. Theoretically, only stoichiometric quantities (that is, one or two moles dehalogenating reagent for every mole of organic chlorine) are required. In practice, however, some multiple of the stoichiometric quantities will be necessary to allow for reagent dilution with interstitial or bound moisture in certain soils, for example clays. A biodegradable organic mobilizing or compatible surfactant (1-15%) is added when treating highly intractable matrices.
Identified by-products include biphenyl, non-chlorinated biodegradable hydrocarbons and common salts, such as sodium chloride, potassium chloride and calcium chloride. No PCB compounds or volatile organic compounds were found in off gases collected during the treatability studies.
The present composition can be used through a spray application on soils, concrete surfaces and/or sludges. Surface contact is the key to high levels of PCB destruction (greater than 95 percent destruction). At times, hydrogen peroxide can be used to disrupt soil aggregates and decompose organic matter to help penetration of the present composition. Soil moisture affects destruction efficiency by preventing the present composition, which is a water soluble liquid, from permeating soil pore spaces.
Two basic methods can be used to apply the present composition; (1) in situ or (2) excavation and processing. The in situ method is the in-place preparation of surface soils by tilling and/or discing to a depth of about 18 inches and then injection of the present composition through spray nozzles to the desired depth. Generally, one application is required. More than one application is anticipated when surfaces or soils contain high concentrations of PCB compounds.
The excavation and processing method can consist of two procedures. For one procedure, excavated soils are sprayed with the present composition and placed in a lined treatment bed or returned to the excavated trench. For compacted or clay-rich soils, a shredder modified with spray nozzles can be used.
Because it is a contact process, the present process works efficiently in the destruction of PCB compounds on concrete and steel surfaces. In one field remediation at a steel finishing facility more than 90% destruction of PCB compounds was observed from a concrete floor. This preliminary test was to be used to plan a remediation of the building floor. No preparation of the floor was conducted prior to treatment. However, with preparation, higher treatment efficiency is expected.
Other examples of treatment efficiency are:
Soil treatment—Clayey fine sandy loams were treated with the present composition with destruction of PCB compounds ranging from 82% to about 90%.
Soil treatment—Treatment with the present composition reduced the PCB compounds by more than 92% to 96%.
Soil treatment—More than 95% destruction was accomplished with the present composition in a silt loam soil.
In addition, all treatability studies on contaminated materials completed under USEPA protocols resulted in PCB compound reduction of 92% to more than 98%.
In all site cases high levels of total petroleum hydrocarbons were present. As part of the chemical reactions, the concentration of total petroleum hydrocarbons was also reduced by about 30%.
DETAILED DISCUSSION OF THE PREFERRED EMBODIMENTS
Polychlorinated Biphenyls represent one of the more toxic and persistent contaminants found in the environment today. Since first being regulated under the Toxic Substances Control Act (TSCA) in 1978, billions of dollars have been spent by industry and government managing PCB problems. A significant portion of the dollars spent have been used to dispose of PCB-containing substances.
Based upon their widespread use in the past, PCB compounds are routinely detected in a variety of media, thus representing one of the more challenging and expensive remediation obstacles facing owners and/or developers of industrial properties. Traditional methods to remediate PCB compounds have proven ineffective, expensive and in many cases, merely transfer liability from one media to another. Meeting the strict clean-up criteria mandated by governmental agencies may also pose a considerable challenge to several of the more common methods, unless co
Buchanan Ingersoll P.C.
Gupta Yogendra N.
Petruncio John M
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