Effects of activated carbon on the reactions of free chlorine with phenols

The reactions of phenol, 2,6-dimethoxyphenol, catechol and p-chlorophenol with chlorine in aqueous solution followed by those during granular activated carbon adsorption were investigated under conditions similar to those encountered in drinking water treatment practice. In aqueous solutions free chlorine reacted to produce mono-, di-, or tri-chloro derivatives. Activated carbon could act as an oxidant and catalyst with the formation of additional products, notably chlorohydroxybiphenyls, important because of their potential toxicity. Granular activated carbon exposed to chlorine was capable of promoting reactions such as hydroxylation of the aromatic ring, oxidation to quinones, chlorine substitution, carboxylation and oxidative coupling.