Effect of photosensitizer diethylamine on the photodegradation of polychlorinated biphenyls

Abstract

The objective of this study was to investigate the effect of diethylamine and xenon simulated sunlight on the photodegradation of two forms of PCBs including PCBs in transformer oil and PCB congener 138. The result of GC chromatograms illustrated the shifting pattern of higher chlorinated biphenyls in transformer oil degraded to lower chlorinated biphenyls with the extension of exposure time. The effect of diethylamine and xenon simulated sunlight was significant on the photodegradation of both PCBs in transformer oil and congener 138. The initial degradation rates of congener 138 (1.14 × 10 −9 to 4.47 × 10 −9 mol l −1 h −1) were in direct proportion to the initial concentrations of congener 138 which confirmed the pseudo-first-order reaction of PCB photodegradation. The apparent quantum yields ( φ) of congener 138 using diethylamine in xenon photoreactor were ranged between 2.08 × 10 −2 and 9.8 × 10 −4. PCB congeners 123, 97, 70, 67, 33, 29, 17, 12, and 9 were detected as the descendants of the photodegradation of congener 138 through dechlorination. The major pathway of congener 138 photodegradation in this study was via para-dechlorination.