In situ decomposition of PCBs in soil using microwave energy

The decomposition of individual PCBs and of Aroclors in soil using microwave energy and graphite fibers occurs quantitatively in a machinable ceramic alumina bomb. As a model for in situ remediation, the reactions were then carried out in open vessels equipped with rudimentary condensers, and using either pencil lead las a cheap graphite rod equivalent) or iron wire. Most of the chlorinated aromatics decomposed (none left in the soil), and a small portion was desorbed, collected, and dechlorinated quantitatively by catalytic hydrogenation. This procedure should allow soil remediation to any preset depth by using the appropriate length of graphite or iron rods. When C-14-2,2',5,5'-tetrachlorobiphenyl was used (with thinner pencil lead) 27% was desorbed and 1-2.5% of (CO2)-C-14, was evolved. The remaining material could not be extracted from the soil under any conditions, and this suggests that the dechlorinated fragments are very tightly bound, and possibly encapsulated, by the vitrified soil. (C) 1999 Elsevier Science Ltd. All rights reserved.