Dechlorination of hexachlorobenzene using lead–iron bimetallic particles

HCB was easier to dechlorinate in acidic aqueous solutions than in alkaline, with removal efficiency greater than 50% after about 2h’s treatment at pH 1.9 and 3.8 and lower than 10% after approximately 4h’s treatment at pH 9.1 and 11.1. [Display omitted] ► The bimetal for HCB dechlorination used Pb instead of noble-metal. ► Pb impacted the dechlorination by exhibiting dots-gathered to linear-growth. ► The biggest degradation rate constant emerged at pH 7.0. ► Dechlorination at high temperature would be more effective. Synthesized lead–iron (Pb/Fe) bimetallic particles were applied to dechlorinate hexachlorobenzene (HCB) under various conditions (e.g. bimetal amount, initial pH value, reaction temperature, and reaction duration). The results showed that adding Pb onto Fe benefited the dechlorination of HCB and the bimetal with 1.4% Pb content performed best. The degradation rate decreased regularly as the initial pH value of the aqueous increased from 1.9 to 11.1 except for pH 7.0 where the fastest dechlorination rate emerged. The dechlorination could be enhanced by increasing the amount of Pb/Fe or the reaction temperature. The dechlorination ratio of HCB within 15min increased from 24.3% to 81.3% when Pb/Fe amount increased from 0.1g to 0.8g. The dechlorination followed pseudo-first-order kinetics, and the dechlorination rate constants were 0.0027, 0.0064, 0.0157, and 0.0321min−1 at 25, 50, 70, and 85°C, respectively, and the activation energy (Ea) of the dechlorination by Pb/Fe was 37.86kJmol−1.