Oxidation removal of gaseous Hg0 using enhanced-Fenton system in a bubble column reactor

A novel removal process of elemental mercury (Hg-0) from gas using Cu2+-enhanced Fenton system in a bubble column reactor was developed. Experiments were conducted to explore the influence of several factors (concentrations of H2O2, Fe2+ and Cu2+, reagent pH, reaction temperature, concentrations of Hg-0, NO and SO2) on Hg-0 removal. Mechanism and routes of Hg-0 removal using Cu2+-enhanced Fenton system were also proposed. The results revealed that adding Cu2+ obviously strengthened removal process of Hg-0 in Fenton system. The contrast results of free radical yield found that the enhancement effect was originated from generation of more hydroxyl radicals that were produced from the synergistic role between Cu2+ and Fe2+ in Fenton system. Hg-0 removal efficiency was raised by increasing concentrations of Cu2+ and Fe2+, and was reduced via increasing reaction temperature. Increasing concentration of H2O2 and reagent pH exhibited double impact on Hg-0 removal. Hg-0 was removed by four pathways: (1) Hg-0 was oxidized by center dot OH that was produced from the synergistic role between Cu2+ and Fe2+ in Fenton system; (2) Hg-0 was oxidized by % OH that was produced from Fe2+/ H2O2 system; (3) Hg-0 was oxidized by % OH that was produced from Cu2+/ H2O2 system; (4) Hg-0 was oxidized by H2O2. The pathways (1) and (2) were the main routes of Hg-0 removal.