Abstract:
The process of dechlorination of 2,2',4,4',5,5'-hexachlorobiphenyl (PCB 153) under the action of UV radiation of a KrCl* (222 nm) barrier-discharge excilamp has been studied. The photolysis was performed in PCB 153 solutions in hexane with concentrations of 10 $\mu$g/ml (sample 1) and 1 $\mu$g/ml (sample 2) and in a PCB 153 film on a silica plate (sample 3). The degree of PCB 153 decomposition was determined using the optical transmission spectra measured in a 185–350 nm wavelength range. An analysis of these spectra showed that chlorine atoms in ortho 2,2'positions are detached first. At a UV radiation intensity of 3 mW/cm$^2$ on the sample surface, the residual PCB 153 content in samples 1–3 was below 2% (60-min exposure), below 3% (25-min exposure), and below 20% (60-min exposure), respectively.
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