Iron-Mediated Reactions of Polychlorinated Biphenyls n Electrochemical Peroxidation Process (ECP)

Zero-valent iron has proven useful in the dechlorination of a variety of organic contaminants. In the electrochemical peroxidation process (ECP), which has been developed recently to enhance the effectiveness of the Fenton reaction, an electric current and sacrificial steel electrodes are utilized to supply soluble divalent Fe. In this study, the extent of adsorption of PCBs on steel electrodes and on Fe super(0) powder was determined and compared, and the effects of pH, induced current, and Fe super(2+) concentrations on PCB degradation were examined. An aqueous solution of Aroclor 1248 was used. A strong affinity for PCBs to adsorb on the surface of Fe was observed, which suggested that dechlorination involved either direct electron transfer or complexation via a product of Fe corrosion. pH appeared to have little influence of PCB adsorption on either Fe super(0) filings or steel electrodes. A number of daughter congeners were noted after a contact time of 48 h, which indicated preferential removal of meta- and para-chlorines. Overall, electrochemistry provided an efficient alternative to the addition of ferrous salts to promote degradation.