Base-catalyzed decomposition of hexachlorobenzene: effect on dechlorination efficiency of different hydrogen donors, alkalis and catalysts

Abstract

The effect of different hydrogen donors, alkalis, and catalysts on the dechlorination efficiency of hexachlorobenzene (HCB) by base-catalyzed decomposition (BCD) technology was investigated. According to an orthogonal experiment, all three factors have notable influence on the dechlorination of HCB, and four different combinations of reagents were suitable for the treatment of HCB at high concentrations: polyethylene glycol (PEG) + hydroxide, octadecane + KOH, glycerin + hydroxide, and glycerin + carbonate. Further research regarding the effects of catalysts determined that ∼100% dechlorination of HCB can be achieved in 3 h at 250 °C in the presence of PEG and hydroxide without any catalyst, and iron rather than nickel was recommended as catalyst when octadecane and KOH were used for HCB dechlorination. In addition, an investigation of the HCB dechlorination kinetics in the presence of PEG and various alkalis determined that the HCB dechlorination rate constant increased linearly with the decreasing of the ionic potential of the metal cation in the hydroxide.