Ambient temperature destruction of PCB wastes

There is disclosed a process for destroying halogenated hydrocarbons such as PCBs and PCBs in PCB containing fluids (e.g., Askarel) and oils (e.g., paraffin oil, transformer oil, etc.) at ambient temperature. The process comprises reacting halogenated hydrocarbons, such as PCB containing fluids or oils with a solid oxidant in the presence of a concentrated acid. Preferably, the solid oxidant is potassium permanganate and the concentrated acid is sulfuric acid. Destruction efficiency is as high as 99.95%.

BACKGROUND OF THE INVENTION 
(a) Field of Invention 
This invention relates to a process for destroying PCBs and PCBs in PCB 
containing fluids and oils using solid oxidants in the presence of a 
concentrated acid at ambient temperature. 
(b) Description of the Prior Art 
Polychlorinated biphenyls (PCBs) have been widely used as insulating 
materials in electrical equipment, heat exchange liquids, plasticizers and 
for other industrial applications. It has been determined, however, that 
PCBs and other polyhalogenated organic compounds are a source of 
ecological problems including toxic effects on humans, animals, 
vegetation, soil and air. As a result, the use of PCBs is now banned in 
many countries including Canada and the U.S. However, safe disposal of 
waste PCBs still remains a problem due to the very nature of halogenated 
hydrocarbons, i.e., high stability to chemical and biological degradation 
and production of toxic compounds. 
A number of methods have been proposed to destroy polychlorinated biphenyls 
and other halogenated hydrocarbons. Some of the proposed methods employ a 
high temperature treatment and therefore carry the risk of air pollution 
due to the emission of noxious fumes and vapors in the environment. Also, 
incineration as a way to dispose of hazardous chemicals in general has a 
notable drawback in that it requires substantial energy consumption. 
A number of patents exist on the decomposition reactions of halogenated 
organic compounds stimulated by the use of various forms of radiation, 
e.g., UV, microwave, solar energy, etc. (U.S. Pat. Nos. 4,345,983; 
4,632,742; 4,432,344 and 4,549,528). 
There is, however, still a need for a safe and efficient process for the 
destruction of halogenated or polyhalogenated hydrocarbons, where the 
risks associated with high temperature treatment would be eliminated. 
SUMMARY OF THE INVENTION 
According to this invention, there is provided a process for destroying 
halogenated hydrocarbons, such as PCBs and PCBs in PCB containing fluids 
and oils at ambient temperature. The process comprises reacting 
halogenated hydrocarbons, such as PCBs and PCBs containing fluids or oils 
with a solid oxidant in the presence of a concentrated acid. 
The amount of solid oxidant, the volume of concentrated acid, the sequence 
of addition and the duration of the reaction are not critical. These 
parameters should only be so as to be sufficient to effect the total 
destruction of halogenated hydrocarbons, such as PCBs. 
For the purpose of the present invention, the destruction of halogenated 
hydrocarbons, such as PCBs, will be understood to mean a process in which 
a cleavage of carbon-halogen bands takes place, thus practically 
eliminating all problems of toxicity.

The invention will now be illustrated by means of the following examples, 
which are not intended to limit the scope of the present invention. 
The use of solid oxidants in cleaving carbon-halogen bonds is not limited 
to PCBs and hence the conditions and reagents discussed in examples can be 
applied to the destruction of halogenated organic compounds in general. 
EXAMPLE 1 
A sample of Askarel (0.11 g) was mixed with finely ground potassium 
permanganate (0.55 g) in a 250 ml Erlenmeyer flask. Concentrated sulfuric 
acid (5 ml) was then added to the mixture and the reaction was allowed to 
proceed over a total period of approximately 90 minutes. The reaction 
mixture was then extracted with n-hexane at room temperature. The 
destruction efficiency was determined by analyzing n-hexane extract using 
a gas chromatograph equipped with an electron capture detector. The 
destruction efficiency was found to be above 99.9%. 
EXAMPLE 2 
(In this and the following examples, the apparatus, reaction and analytical 
conditions were similar to Example 1, except where indicated.) 
Askarel (0.1 g) was added to a mixture of potassium permanganate (0.5 g) 
and concentrated sulfuric acid (5 ml), over a period of approximately 40 
minutes, with stirring. The destruction efficiency was 99.99%. 
EXAMPLE 3 
Potassium permanganate (2.2 g) was added to a stirred mixture of Askarel 
(0.4 g) in concentrated sulfuric acid (20 ml). The destruction efficiency 
was 99.99%. 
EXAMPLE 4 
Paraffin oil (0.17 g) spiked with.about.500,000 ppm PCB was added dropwise 
to a stirred mixture of potassium permanganate (2.2 g) and concentrated 
sulfuric acid (20 ml) over a period of approximately 20 minutes. Contents 
were stirred for an additional 30 minutes at 60-65 degrees Celsius. The 
destruction efficiency was 99.95%. 
EXAMPLE 5 
Transformer oil (0.2 g) spiked with.about.500,000 ppm PCB was added 
dropwise to a stirred mixture of potassium permanganate (2.2 g) and 
concentrated sulfuric acid (20 ml) over a period of approximately 30 
minutes. Contents were stirred for an additional 50 minutes at 70 degrees 
Celsius. The destruction efficiency was above 99.95%. 
EXAMPLE 6 
Transformer oil (0.17 g) spiked with 5,000 ppm Aroclor 1254 was added 
dropwise to a stirred mixture of potassium permanganate (2.6 g) and 
concentrated sulfuric acid (20 ml) over a period of approximately 25 
minutes. Contents were stirred for an additional 40 minutes at 70 degrees 
Celsius. The destruction efficiency was 99.95%. 
It is evident, therefore, that the solid oxidant--potassium 
permanganate--in concentrated sulfuric acid at room temperature is 
effective in accomplishing a substantial and rapid destruction of PCBs and 
PCBs in PCB containing fluids and oils. The process according to the 
present invention, can also be used to destroy a variety of halogenated 
hydrocarbons beside PCBs. However, for each substance to be 
decontaminated, optimum amounts of the solid oxidant and the concentrated 
acid have to be adjusted with the type of halogenated hydrocarbon. 
EXAMPLE 7 
Askarel (0.1 g) was mixed with chromium dioxide (0.5 g) and concentrated 
sulfuric acid (5 ml). The mixture was maintained at 100 degrees Celsius 
for 30 minutes. The destruction efficiency was 99.99%. 
It should also be noted that the destruction process of the invention is 
not limited to PCBs and PCBs in fluids or oils. Destruction of halogenated 
hydrocarbons, by the process according to this invention, may be carried 
out in diverse matrices such as liquids, solids (PCBs in soil or other 
types of solid wastes) and gases (PCBs and other halogenated hydrocarbons 
in air).