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

Highlights • A novel removal process of Hg0 using enhanced Fenton was proposed. • Products and mechanism of Hg0 removal were studied. • Hg0 was removed by four pathways. • Hg0 removal by OH oxidation is the leading pathway. Abstract A novel removal process of elemental mercury (Hg0) 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 H 2 O 2 , Fe2+ and Cu2+, reagent pH, reaction temperature, concentrations of Hg0, NO and SO 2) on Hg0 removal. Mechanism and routes of Hg0 removal using Cu2+-enhanced Fenton system were also proposed. The results revealed that adding Cu2+ obviously strengthened removal process of Hg0 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. Hg0 removal efficiency was raised by increasing concentrations of Cu2+ and Fe2+, and was reduced via increasing reaction temperature. Increasing concentration of H 2 O 2 and reagent pH exhibited double impact on Hg0 removal. Hg0 was removed by four pathways: (1) Hg0 was oxidized by · OH that was produced from the synergistic role between Cu2+ and Fe2+ in Fenton system; (2) Hg0 was oxidized by OH that was produced from Fe2+/H 2 O 2 system; (3) Hg0 was oxidized by OH that was produced from Cu2+/H 2 O 2 system; (4) Hg0 was oxidized by H 2 O 2. The pathways (1) and (2) were the main routes of Hg0 removal. [ABSTRACT FROM AUTHOR]