Kinetic studies of reductive dechlorination of chlorophenols with Ni/Fe bimetallic particles

The catalytic dechlorination of five chlorophenols, by Ni/Fe bimetal was investigated through batch experiments. The results showed that the destruction of chlorophenols by hydrodechlorination over Ni/Fe was very effective and followed the pseudo-first-order kinetics under aqueous conditions. The order of reaction rate was 2-chlorophenol > 4-chlorophenol > 2,4-dichlorophenol > 2,4,6-trichlorophenol > 2,6-dichlorophenol (2,6-DCP). The dechlorination rate of chlorophenol increased linearly with increasing nickel coating on iron. In general, increasing the degree of chlorine substitution on the phenol ring decreased the rate of dechlorination except for 2,6-DCP. Chlorophenols were dechlorinated to phenol via both stepwise as the major pathway and concerted mechanisms with minor contribution. The relative contribution of each reaction pathway is discussed through a model fitting.