PHOTODEGRADATION OF POLYCHLORINATED DIOXINS AND DIBENZOFURANS ADSORBED TO FLY-ASH

The photodegradation of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) naturally adsorbed to fly ashes was investigated. Photodegradation experiments were performed in the solid phase using a rotary photoreactor and a medium-pressure, mercury vapor lamp. Although PCDD/F photodegradation occurred in solution and when PCDD/F were spiked on silica gel, no significant photodegradation was observed for the native PCDD/F found on five different fly ashes, ranging in color from black to gray to yellow. This suggests that photodegradation of PCDD/F bound to atmospheric particles is not a significant mechanism by which these compounds are removed from the environment.