Direct and complete cleansing of transformer oil contaminated by PCBs

Transformer oil can be directly decontaminated from PCB residues by direct treatment with metallic Ca and an alcoholic mixture, offering the possibility to recycle this product. The procedure, consisting in mixing, stirring and separating, is simple and effective. The hydrodechlorination yield is 99.6%, the remaining chlorobiphenyl belonging to the almost non-toxic family of ortho-monochloro- and ortho-dichlorobiphenyl. Low miscibility problems were overcome, using a mixture of ethanol and isopropanol.

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► A single-batch process is effective in the cleansing of transformer oil from any trace of PCBs.
► Transformer oil can thus be recycled at a cheap price, using commercial metallic Ca and simple alcohols (methanol, ethanol and isopropanol).
► The hydrodechlorination is complete, leaving only traces of mono- and dichlorobiphenyl compounds with the lowest toxicity in the PCB family.