Problem- In the purification of wastewater contaminated by pentachlorophenol and 2,3,5,6-tetrachlorophenol using ultraviolet light, it was noticed that OCDD and 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin were formed. Deduce whether the latter was formed by the coupling of a molecule of each of the phenols, or rather must have been formed by photochemical dechlorination of OCDD. What potential flaw exists in treating water by UV light, given the nature of the products that are formed? Please give detailed answer.
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