1. Field of the Invention
The present invention pertains to the treatment of fluids containing polychlorinated biphenyls to convert the toxic compounds to polyhydroxylated biphenyl derivatives and to remove the resultant compounds from fluids such as petroleum base oils and the like.
2. Background Art
The development of polychlorinated biphenyls or PCBs for use as insulating and heat transfer fluids received widespread use until indications of the possibility that these fluids posed a potential health hazard. The use of PCBs in electrical transformers and the like as an insulating and heat transfer fluid has been largely discontinued and even legally banned in some countries. These fluids have been replaced by other fluids including petroleum distillates having properties similar to diesel oil, for example. However, the contamination of large numbers of electrical distribution transformers by the residual amounts of PCBs remaining in the transformer tanks after replacement by other fluids has posed a still further problem in the treatment and disposal of these contaminated fluids. Moreover, the restrictions issued by the U.S. Environmental Protection Agency under the authority of the Toxic Substances Control Act has resulted in the temporary storage of large quantities of PCB contaminated fluids of various types.
The restrictions on the treatment of PCBs has not only posed a dilemma from an environmental standpoint, but has resulted in costly treatment processes for various types of equipment during reconditioning and servicing thereof. In particular, the large number of electrical distribution transformers in use and requiring periodic servicing and reconditioning has posed a substantial problem to the electric utility and electrical equipment manufacturing industry as regards the handling of contaminated transformer oils.
Although several processes for the dechlorination of chlorinated aromatic compounds such as PCBs have been proposed, known processes suffer from several disadvantages including high cost, the use of hazardous materials in the treatment process and requiring complicated equipment and treatment processes. For example, one process which has received some attention includes the mixing of sodium napthalenide with the PCB contaminated fluid followed by distillation to rid the fluid of the residue from the reaction. This method is not only dangerous because it involves the handling of highly reactive sodium metal in the formation of the reagent, but also requires a complicated system for carrying out the treatment of the fluid being decontaminated.
The disadvantages of prior art PCB treatment processes together with the urgent need to deal with the decontamination of large quantities of fluids, particularly of the type used in electrical transformers, has led to the development of the present invention which produces an acceptable reduced level of PCBs in fluids such as petroleum distillates under less hazardous operating conditions and with the fairly simple removal of residues from the fluid wherein the fluid may be recycled for resumption of its intended use.