The photochemistry of PCB'S

Polychlorinated biphenyls (PCBs), which were once so widely utilized, have been detected in worldwide environmental samples. Their stability makes them persistent pollutants.

The purpose of this work was to determine the chemical fate of this class of compounds in water, rather than in a cosolvent mixture. The study began simply—observing monochlorinated biphenyls in distilled water under anaerobic conditions. One variable was added at a time in order to understand only its effects instead of trying to unravel the workings of several simultaneously. The reactions were followed under various conditions, alone or in conjunction with others, some of which are as follows: in the absence or presence of oxygen, in distilled water and in lake water, and with or without the addition of clays.

When monochlorinated biphenyls were irradiated in water, phenyl-phenols were formed in addition to other unidentifiable reaction products. Surprisingly, biphenyl was not a photoproduct. Both meta- and para-phenylphenol were produced photochemical I y by 4- chlorophenyl. The presence of oxygen reduced the reaction rates considerably. Finally, all monochlorinated biphenyls did not react at the same rate.