Encyclopedia of Environmental Science and Engineering, Volume I and II

882 PCBs AND ASSOCIATED AROMATICS

FIGURE 19 Benzyne or other free radical formation of polychlorinated naphthalenes.

FIGURE 20 Pyrolysis formation of PCDFs from PCBs.

From a chemical point of view there is little difference

between whether the electron is derived from an alkali metal

or an organometallic reagent or from radiation induced elec-

trons. The gamma-ray radiolysis of halogenated benzenes

was investigated by Choi and Willard in 1962^57 using a high

specific activity Co^60 source. Aria et al.^58 were the first to

apply the method to PCB solutions and in 1974 their work

was extended by Sawai et al.^59

Sawai et al. used Co^60 gamma-rays to induce electrons

in deoxygenated solutions of PCBs in alkaline isopropanol.

They found that the presence of small amounts of electron

acceptors resulted in an inhibition of dechlorination. Also,

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